Dosimetry audit simulation of treatment planning system in multicenters radiotherapy
Kasmuri, S.; Pawiro, S. A.
2017-07-01
Treatment Planning System (TPS) is an important modality that determines radiotherapy outcome. TPS requires input data obtained through commissioning and the potentially error occurred. Error in this stage may result in the systematic error. The aim of this study to verify the TPS dosimetry to know deviation range between calculated and measurement dose. This study used CIRS phantom 002LFC representing the human thorax and simulated all external beam radiotherapy stages. The phantom was scanned using CT Scanner and planned 8 test cases that were similar to those in clinical practice situation were made, tested in four radiotherapy centers. Dose measurement using 0.6 cc ionization chamber. The results of this study showed that generally, deviation of all test cases in four centers was within agreement criteria with average deviation about -0.17±1.59 %, -1.64±1.92 %, 0.34±1.34 % and 0.13±1.81 %. The conclusion of this study was all TPS involved in this study showed good performance. The superposition algorithm showed rather poor performance than either analytic anisotropic algorithm (AAA) and convolution algorithm with average deviation about -1.64±1.92 %, -0.17±1.59 % and -0.27±1.51 % respectively.
Dosimetry quality audit of high energy photon beams in greek radiotherapy centers
International Nuclear Information System (INIS)
Hourdakis, Constantine J.; Boziari, A.
2008-01-01
Background and purpose: Dosimetry quality audits and intercomparisons in radiotherapy centers is a useful tool in order to enhance the confidence for an accurate therapy and to explore and dissolve discrepancies in dose delivery. This is the first national comprehensive study that has been carried out in Greece. During 2002 - 2006 the Greek Atomic Energy Commission performed a dosimetry quality audit of high energy external photon beams in all (23) Greek radiotherapy centers, where 31 linacs and 13 Co-60 teletherapy units were assessed in terms of their mechanical performance characteristics and relative and absolute dosimetry. Materials and Methods: The quality audit in dosimetry of external photon beams took place by means of on-site visits, where certain parameters of the photon beams were measured, calculated and assessed according to a specific protocol and the IAEA TRS 398 dosimetry code of practice. In each radiotherapy unit (Linac or Co-60), certain functional parameters were measured and the results were compared to tolerance values and limits. Doses in water under reference and non reference conditions were measured and compared to the stated values. Also, the treatment planning systems (TPS) were evaluated with respect to irradiation time calculations. Results: The results of the mechanical tests, dosimetry measurements and TPS evaluation have been presented in this work and discussed in detail. This study showed that Co-60 units had worse performance mechanical characteristics than linacs. 28% of all irradiation units (23% of linacs and 42% of Co-60 units) exceeded the acceptance limit at least in one mechanical parameter. Dosimetry accuracy was much worse in Co60 units than in linacs. 61% of the Co60 units exhibited deviations outside ±3% and 31% outside ±5%. The relevant percentages for the linacs were 24% and 7% respectively. The results were grouped for each hospital and the sources of errors (functional and human) have been investigated and
Dosimetry quality audit of high energy photon beams in greek radiotherapy centers.
Hourdakis, Constantine J; Boziari, A
2008-04-01
Dosimetry quality audits and intercomparisons in radiotherapy centers is a useful tool in order to enhance the confidence for an accurate therapy and to explore and dissolve discrepancies in dose delivery. This is the first national comprehensive study that has been carried out in Greece. During 2002--2006 the Greek Atomic Energy Commission performed a dosimetry quality audit of high energy external photon beams in all (23) Greek radiotherapy centers, where 31 linacs and 13 Co-60 teletherapy units were assessed in terms of their mechanical performance characteristics and relative and absolute dosimetry. The quality audit in dosimetry of external photon beams took place by means of on-site visits, where certain parameters of the photon beams were measured, calculated and assessed according to a specific protocol and the IAEA TRS 398 dosimetry code of practice. In each radiotherapy unit (Linac or Co-60), certain functional parameters were measured and the results were compared to tolerance values and limits. Doses in water under reference and non reference conditions were measured and compared to the stated values. Also, the treatment planning systems (TPS) were evaluated with respect to irradiation time calculations. The results of the mechanical tests, dosimetry measurements and TPS evaluation have been presented in this work and discussed in detail. This study showed that Co-60 units had worse performance mechanical characteristics than linacs. 28% of all irradiation units (23% of linacs and 42% of Co-60 units) exceeded the acceptance limit at least in one mechanical parameter. Dosimetry accuracy was much worse in Co60 units than in linacs. 61% of the Co60 units exhibited deviations outside +/-3% and 31% outside +/-5%. The relevant percentages for the linacs were 24% and 7% respectively. The results were grouped for each hospital and the sources of errors (functional and human) have been investigated and discussed in details. This quality audit proved to be a
External audit in radiotherapy dosimetry
International Nuclear Information System (INIS)
Thwaites, D.I.; Western General Hospital, Edinburgh
1996-01-01
Quality audit forms an essential part of any comprehensive quality assurance programme. This is true in radiotherapy generally and in specific areas such as radiotherapy dosimetry. Quality audit can independently test the effectiveness of the quality system and in so doing can identify problem areas and minimize their possible consequences. Some general points concerning quality audit applied to radiotherapy are followed by specific discussion of its practical role in radiotherapy dosimetry, following its evolution from dosimetric intercomparison exercises to routine measurement-based on-going audit in the various developing audit networks both in the UK and internationally. Specific examples of methods and results are given from some of these, including the Scottish+ audit group. Quality audit in radiotherapy dosimetry is now well proven and participation by individual centres is strongly recommended. Similar audit approaches are to be encouraged in other areas of the radiotherapy process. (author)
Gershkevitsh, Eduard; Pesznyak, Csilla; Petrovic, Borislava; Grezdo, Joseph; Chelminski, Krzysztof; do Carmo Lopes, Maria; Izewska, Joanna; Van Dyk, Jacob
2014-05-01
One of the newer audit modalities operated by the International Atomic Energy Agency (IAEA) involves audits of treatment planning systems (TPS) in radiotherapy. The main focus of the audit is the dosimetry verification of the delivery of a radiation treatment plan for three-dimensional (3D) conformal radiotherapy using high energy photon beams. The audit has been carried out in eight European countries - Estonia, Hungary, Latvia, Lithuania, Serbia, Slovakia, Poland and Portugal. The corresponding results are presented. The TPS audit reviews the dosimetry, treatment planning and radiotherapy delivery processes using the 'end-to-end' approach, i.e. following the pathway similar to that of the patient, through imaging, treatment planning and dose delivery. The audit is implemented at the national level with IAEA assistance. The national counterparts conduct the TPS audit at local radiotherapy centres through on-site visits. TPS calculated doses are compared with ion chamber measurements performed in an anthropomorphic phantom for eight test cases per algorithm/beam. A set of pre-defined agreement criteria is used to analyse the performance of TPSs. TPS audit was carried out in 60 radiotherapy centres. In total, 190 data sets (combination of algorithm and beam quality) have been collected and reviewed. Dosimetry problems requiring interventions were discovered in about 10% of datasets. In addition, suboptimal beam modelling in TPSs was discovered in a number of cases. The TPS audit project using the IAEA methodology has verified the treatment planning system calculations for 3D conformal radiotherapy in a group of radiotherapy centres in Europe. It contributed to achieving better understanding of the performance of TPSs and helped to resolve issues related to imaging, dosimetry and treatment planning.
International Nuclear Information System (INIS)
Capelle, Lisa; Warkentin, Heather; MacKenzie, Marc; Joseph, Kurian; Gabos, Zsolt; Pervez, Nadeem; Tankel, Keith; Chafe, Susan; Amanie, John; Ghosh, Sunita; Parliament, Matthew; Abdulkarim, Bassam
2012-01-01
Purpose: We investigated whether treatment-planning system (TPS)-calculated dose accurately reflects skin dose received for patients receiving adjuvant breast radiotherapy (RT) with standard three-dimensional conformal RT (3D-CRT) or skin-sparing helical tomotherapy (HT). Methods and Materials: Fifty patients enrolled in a randomized controlled trial investigating acute skin toxicity from adjuvant breast RT with 3D-CRT compared to skin-sparing HT, where a 5-mm strip of ipsilateral breast skin was spared. Thermoluminescent dosimetry or optically stimulated luminescence measurements were made in multiple locations and were compared to TPS-calculated doses. Skin dosimetric parameters and acute skin toxicity were recorded in these patients. Results: With HT there was a significant correlation between calculated and measured dose in the medial and lateral ipsilateral breast (r = 0.67, P V50 (1.4% vs 5.9%, respectively; P=.001) but higher skin V40 and skin V30 (71.7% vs 64.0%, P=.02; and 99.0% vs 93.8%, P=.001, respectively) than 3D-CRT plans. Conclusion: The 3D-CRT TPS more accurately reflected skin dose than the HT TPS, which tended to overestimate dose received by 14% in patients receiving adjuvant breast RT.
An IAEA Survey of Dosimetry Audit Networks for Radiotherapy
International Nuclear Information System (INIS)
Grochowska, Paulina; Izewska, Joanna
2013-01-01
A Survey: In 2010, the IAEA undertook a task to investigate and review the coverage and operations of national and international dosimetry audit programmes for radiotherapy. The aim was to organize the global database describing the activities of dosimetry audit networks in radiotherapy. A dosimetry audit questionnaire has been designed at an IAEA consultants' meeting held in 2010 for organizations conducting various levels of dosimetry audits for radiotherapy. Using this questionnaire, a survey was conducted for the first time in 2010 and repeated in 2011. Request for information on different aspects of the dosimetry audit was included, such as the audit framework and resources, its coverage and scope, the dosimetry system used and the modes of audit operation, i.e. remotely and through on-site visits. The IAEA questionnaire was sent to over 80 organizations, members of the IAEA/WHO Network of Secondary Standards Dosimetry Laboratories (SSDLs) and other organizations known for having operated dosimetry audits for radiotherapy in their countries or internationally. Survey results and discussion: In response to the IAEA survey, 53 organizations in 45 countries confirmed that they operate dosimetry audit services for radiotherapy. Mostly, audits are conducted nationally, however there are five organizations offering audits abroad, with two of them operating in various parts of the world and three of them at the regional level, auditing radiotherapy centres in neighbouring countries. The distribution of dosimetry audit services in the world is given. (author)
Dosimetry on the radiological risks prevention in radiotherapy
International Nuclear Information System (INIS)
Fornet R, O. M.; Perez G, F.
2014-08-01
Dosimetry in its various forms plays a determining role on the radiological risks prevention in radiotherapy. To prove this in this paper is shown an analysis based on the risk matrix method, how the dosimetry can influence in each stages of a radiotherapy service; installation and acceptance, operation, maintenance and calibration. For each one of these stages the role that can play is analyzed as either the initiating event of a radiological accident or limiting barrier of these events of the dosimetric processes used for the individual dosimetry, the area monitoring, fixed or portable, for radiation beam dosimetry and of the patients for a radiotherapy service with cobalt-therapy equipment. The result of the study shows that the application of a prospective approach in the role evaluation of dosimetry in the prevention and mitigation of the consequences of a radiological accident in radiotherapy is crucial and should be subject to permanent evaluation at each development stage of these services. (author)
Dosimetry applied to radiology and radiotherapy
International Nuclear Information System (INIS)
Yoshimura, Elisabeth Mateus
2010-01-01
Full text. The uses of ionizing radiation in medicine are increasing worldwide, and the population doses increase as well. The actual radiation protection philosophy is based on the balance of risks and benefits related to the practices, and patient dosimetry has an important role in the implementation of this point of view. In radiology the goal is to obtain an image with diagnostic quality with the minimum patient dose. In modern Radiotherapy the cure indexes are higher, giving rise to longer survival times to the patients. Dosimetry in radiotherapy helps the treatment planning systems to get a better protection to critical organs, with higher doses to the tumor, with a guarantee of better life quality to the patient. We will talk about the new trends in dosimetry of medical procedures, including experimental techniques and calculation tools developed to increase reliability and precision of dose determination. In radiology the main concerns of dosimetry are: the transition from film- radiography to digital image, the pediatric patient doses, and the choice of dosimetric quantities to quantify fluoroscopy and tomography patient doses. As far as Radiotherapy is concerned, there is a search for good experimental techniques to quantify doses to tissues adjacent to the target volumes in patients treated with new radiotherapy techniques, as IMRT and heavy particle therapy. (author)
Dosimetry audit of radiotherapy treatment planning systems
International Nuclear Information System (INIS)
Bulski, Wojciech; Chelminski, Krzysztof; Rostkowska, Joanna
2015-01-01
In radiotherapy Treatment Planning Systems (TPS) various calculation algorithms are used. The accuracy of dose calculations has to be verified. Numerous phantom types, detectors and measurement methodologies are proposed to verify the TPS calculations with dosimetric measurements. A heterogeneous slab phantom has been designed within a Coordinated Research Project (CRP) of the IAEA. The heterogeneous phantom was developed in the frame of the IAEA CRP. The phantom consists of frame slabs made with polystyrene and exchangeable inhomogeneity slabs equivalent to bone or lung tissue. Special inserts allow to position thermoluminescent dosimeters (TLD) capsules within the polystyrene slabs below the bone or lung equivalent slabs and also within the lung equivalent material. Additionally, there are inserts that allow to position films or ionisation chamber in the phantom. Ten Polish radiotherapy centres (of 30 in total) were audited during on-site visits. Six different TPSs and five calculation algorithms were examined in the presence of inhomogeneities. Generally, most of the results from TLD were within 5 % tolerance. Differences between doses calculated by TPSs and measured with TLD did not exceed 4 % for bone and polystyrene equivalent materials. Under the lung equivalent material, on the beam axis the differences were lower than 5 %, whereas inside the lung equivalent material, off the beam axis, in some cases they were of around 7 %. The TLD results were confirmed with the ionisation chamber measurements. The comparison results of the calculations and the measurements allow to detect limitations of TPS calculation algorithms. The audits performed with the use of heterogeneous phantom and TLD seem to be an effective tool for detecting the limitations in the TPS performance or beam configuration errors at audited radiotherapy departments. (authors)
International Nuclear Information System (INIS)
Thompson, Larissa
2013-01-01
Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film
Dosimetry audit of radiotherapy treatment planning systems.
Bulski, Wojciech; Chełmiński, Krzysztof; Rostkowska, Joanna
2015-07-01
In radiotherapy Treatment Planning Systems (TPS) various calculation algorithms are used. The accuracy of dose calculations has to be verified. Numerous phantom types, detectors and measurement methodologies are proposed to verify the TPS calculations with dosimetric measurements. A heterogeneous slab phantom has been designed within a Coordinated Research Project (CRP) of the IAEA. The heterogeneous phantom was developed in the frame of the IAEA CRP. The phantom consists of frame slabs made with polystyrene and exchangeable inhomogeneity slabs equivalent to bone or lung tissue. Special inserts allow to position thermoluminescent dosimeters (TLD) capsules within the polystyrene slabs below the bone or lung equivalent slabs and also within the lung equivalent material. Additionally, there are inserts that allow to position films or ionisation chamber in the phantom. Ten Polish radiotherapy centres (of 30 in total) were audited during on-site visits. Six different TPSs and five calculation algorithms were examined in the presence of inhomogeneities. Generally, most of the results from TLD were within 5 % tolerance. Differences between doses calculated by TPSs and measured with TLD did not exceed 4 % for bone and polystyrene equivalent materials. Under the lung equivalent material, on the beam axis the differences were lower than 5 %, whereas inside the lung equivalent material, off the beam axis, in some cases they were of around 7 %. The TLD results were confirmed with the ionisation chamber measurements. The comparison results of the calculations and the measurements allow to detect limitations of TPS calculation algorithms. The audits performed with the use of heterogeneous phantom and TLD seem to be an effective tool for detecting the limitations in the TPS performance or beam configuration errors at audited radiotherapy departments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
Dosimetry in radiotherapy. V.1
International Nuclear Information System (INIS)
1988-01-01
A series of symposia on dosimetry in medicine and biology have been held by the IAEA in co-operation with WHO. The present symposium was the first one focusing on ''Dosimetry in Radiotherapy''. The papers presented reflected the different steps in the calibration chain such as the calibration standards established by the National Standards Laboratories and the conversion of the reading of calibrated instruments to the desired quantity, i.e. absorbed dose to water at a reference point in the user's beam at the radiotherapy clinic. The programme further examined the procedures necessary for optimization of the treatment of the patient, such as treatment planning methods, dose distribution studies, new techniques of dose measurement, improvements in the physical dose distributions/conformation therapy and special problems involved in total body treatments. Results of quality assurance in radiotherapy were presented from local hospitals as well as from national and international studies. Refs, figs and tabs
Development and clinical application of In Vivo dosimetry for radiotherapy
International Nuclear Information System (INIS)
Honda, Hirofumi; Oita, Masataka; Tominaga, Masahide; Oto, Yoshihiro
2016-01-01
In practical radiotherapy, it is important to deliver radiation to the target correctly and safely according to the treatment planning. The control of radiation dose delivered to each patient in radiotherapy mainly relies on the prediction based on the result of pre-treatment verification and irradiation accuracy of treatment machines. In Vivo dosimetry in radiotherapy is the procedure of quality assurance by the way of direct measurement for the patient whether the calculated prescribed dose in the treatment planning is delivered precisely. The history of In Vivo dosimetry is relatively long, and the TLD dosimetry for clinical radiotherapy started in early 1970's. After 1980's, owing to the development of semiconductor devices such as diode detectors, semiconductor arrays, the clinical applications for the dosimetry and diagnostic radiation imaging devices which contributed to the development of electric portal imaging devices and 2D semiconductor detectors were introduced. In recent years, these radiation measurement devices and non-invasive methods have been developed, they are becoming widespread as clinical practice. In this paper, we reviewed the In Vivo dosimetry devices and their characteristics, and technical application for radiotherapy. (author)
Gel dosimetry for conformal radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Gambarini, G [Department of Physics of the University and INFN, Milan (Italy)
2005-07-01
With the continuum development of conformal radio therapies, aimed at delivering high dose to tumor tissue and low dose to the healthy tissue around, the necessities has appeared of suitable improvement of dosimetry techniques giving the possibility of obtaining dose images to be compared with diagnostic images. Also if wide software has been developed for calculating dose distributions in the fields of various radiotherapy units, experimental verifications are necessary, in particular in the case of complex geometries in conformal radiotherapy. Gel dosimetry is a promising method for imaging the absorbed dose in tissue-equivalent phantoms, with the possibility of 3D reconstruction of the spatial dose distribution, with milli metric resolution. Optical imaging of gel dosimeters, based on visible light absorbance analysis, has shown to be a reliable technique for achieving dose distributions. (Author)
Worldwide QA networks for radiotherapy dosimetry
International Nuclear Information System (INIS)
Izewska, J.; Svensson, H.; Ibbott, G.
2002-01-01
A number of national or international organizations have developed various types and levels of external audits for radiotherapy dosimetry. There are three major programmes who make available external audits, based on mailed TLD (thermoluminescent dosimetry), to local radiotherapy centres on a regular basis. These are the IAEA/WHO TLD postal dose audit service operating worldwide, the European Society for Therapeutic Radiology and Oncology (ESTRO) system, EQUAL, in European Union (EU) and the Radiological Physics Center (RPC) in North America. The IAEA, in collaboration with WHO, was the first organization to initiate TLD audits on an international scale in 1969, using mailed system, and has a well-established programme for providing dose verification in reference conditions. Over 32 years, the IAEA/WHO TLD audit service has checked the calibration of more than 4300 radiotherapy beams in about 1200 hospitals world-wide. Only 74% of those hospitals who receive TLDs for the first time have results with deviation between measured and stated dose within acceptance limits of ±5%, while approximately 88% of the users that have benefited from a previous TLD audit are successful. EQUAL, an audit programme set up in 1998 by ESTRO, involves the verification of output for high energy photon and electron beams, and the audit of beam parameters in non-reference conditions. More than 300 beams are checked each year, mainly in the countries of EU, covering approximately 500 hospitals. The results show that although 98% of the beam calibrations are within the tolerance level of ±5%, a second check was required in 10% of the participating centres, because a deviation larger than ±5% was observed in at least one of the beam parameters in non-reference conditions. EQUAL has been linked to another European network (EC network) which tested the audit methodology prior to its application. The RPC has been funded continuously since 1968 to monitor radiation therapy dose delivery at
The United Kingdom's radiotherapy dosimetry audit network
International Nuclear Information System (INIS)
Thwaites, D.I.; Allahverdi, M.; Powley, S.K.; Nisbet, A.
2003-01-01
The first comprehensive national dosimetry intercomparison in the United Kingdom involving all UK radiotherapy centres was carried out in the late 1980s. Out of this a regular radiotherapy dosimetry audit network evolved in the early 1990s. The network is co-ordinated by the Institute of Physics and Engineering in Medicine and comprises eight co-operative regional groups. Audits are based on site visits using ionization chambers and epoxy resin water substitute phantoms. The basic audit methodology and phantom design follows that of the original national intercomparison exercise. However, most of the groups have evolved more complex methods, to extend the audit scope to include other parameters, other parts of the radiotherapy process and other treatment modalities. A number of the groups have developed phantoms to simulate various clinical treatment situations, enabling the sharing of phantoms and expertise between groups, but retaining a common base. Besides megavoltage external beam photon dosimetry, a number of the groups have also included the audit of kilovoltage X ray beams, electron beams and brachytherapy dosimetry. The National Physical Laboratory is involved in the network and carries out basic beam calibration audits to link the groups. The network is described and the methods and results are illustrated using the Scottish+ group as an example. (author)
International Nuclear Information System (INIS)
Indra Saptiama; Moch Subechi; Anung Pujiyanto; Hotman Lubis; Herlan Setiawan
2014-01-01
The medical treatment using radiation therapy for cancer diseases is increasingly developed. One of the method used in radiotherapy is brachytherapy. Brachytherapy is radiation therapy method in which a radiation source is implanted in cancer cell directly so the dose accepted by cancer cell is the highest dose and the dose accepted by normal cell is the lowest dose. I-125 Seed have been made successfully in domestic. To support the implant of I-125 seed for brachytherapy needs computer programme for the isodose calculation and Treatment Planning System (TPS). Permanent Seed Implant Dosimetry (PSID) 4.5 is one of the isodose calculation and Treatment Planning System (TPS) programme that is owned by Center for Radioisotope and Radiopharmaceutical-BATAN. In isodose calculation, PSID 4.5 uses 1D formalism and 2D formalism based on AAPM-TG43 (Association of American Physicist in Medicine- Task Group No.43). Anisotropic function on 1D formalism depend on distance function while on 2D formalism count on distance and angle function therefore 2D formalism has isodose calculation better than 1D formalism usage. PSID 4.5 can display the isodose contour of the seed I-125 radiation source in 2 dimension (2D) and 3 dimension (3D). The computer programme of isodose calculation and TPS uses PSID 4.5 is expected able to help planning for seed I-125 implantation process for brachytherapy that used by paramedics and to support the usage of seed I-125 as domestic product. (author)
Dosimetry audits and intercomparisons in radiotherapy: A Malaysian profile
International Nuclear Information System (INIS)
Noor, Noramaliza M.; Nisbet, A.; Hussein, M.; Chu S, Sarene; Kadni, T.; Abdullah, N.; Bradley, D.A.
2017-01-01
Quality audits and intercomparisons are important in ensuring control of processes in any system of endeavour. Present interest is in control of dosimetry in teletherapy, there being a need to assess the extent to which there is consistent radiation dose delivery to the patient. In this study we review significant factors that impact upon radiotherapy dosimetry, focusing upon the example situation of radiotherapy delivery in Malaysia, examining existing literature in support of such efforts. A number of recommendations are made to provide for increased quality assurance and control. In addition to this study, the first level of intercomparison audit i.e. measuring beam output under reference conditions at eight selected Malaysian radiotherapy centres is checked; use being made of 9 µm core diameter Ge-doped silica fibres (Ge-9 µm). The results of Malaysian Secondary Standard Dosimetry Laboratory (SSDL) participation in the IAEA/WHO TLD postal dose audit services during the period between 2011 and 2015 will also been discussed. In conclusion, following review of the development of dosimetry audits and the conduct of one such exercise in Malaysia, it is apparent that regular periodic radiotherapy audits and intercomparison programmes should be strongly supported and implemented worldwide. The programmes to-date demonstrate these to be a good indicator of errors and of consistency between centres. A total of ei+ght beams have been checked in eight Malaysian radiotherapy centres. One out of the eight beams checked produced an unacceptable deviation; this was found to be due to unfamiliarity with the irradiation procedures. Prior to a repeat measurement, the mean ratio of measured to quoted dose was found to be 0.99 with standard deviation of 3%. Subsequent to the repeat measurement, the mean distribution was 1.00, and the standard deviation was 1.3%. - Highlights: • We review significant factors that impact upon radiotherapy dosimetry, • We carried out the
Radiographic film orientation in radiotherapy dosimetry
International Nuclear Information System (INIS)
Suchowerska, N.; Davison, A.; Drew, J.; Metcalfe, P.
1996-01-01
Since the discovery of x-rays, film has been used as a detection medium for radiation. More recently radiographic film has become established as a practical tool for the measurement of dose distribution in radiotherapy. The accuracy and reproducibility of film dosimetry depends on photon energy, processing conditions and film plane orientation. The relationship between photon energy, processing conditions and film dosimetry accuracy has been studied. The role of film plane orientation is still controversial. The current work aims to clarify the effects film plane orientation has on film dosimetry. Poster 205. (author)
International Nuclear Information System (INIS)
Baldock, C.
2002-01-01
shapes and sizes while sparing normal tissue. The situation is further complicated if the normal tissues are critical organs or are particularly sensitive to radiation. Radiotherapy techniques employed to obtain a closer conformation of the dose distribution to the tumour volume are referred to as conformal radiotherapy techniques. The clinical implementation of conformal therapy has been delayed by limitations in the verification of conformal dose distributions calculated by treatment planning systems prior to the irradiation of the patient and the verification of complex treatments during its delivery to the patient. There are several aspects of conformal therapy that complicate dose verification. To achieve the dose distributions conforming to complex 3D volumes, high dose gradients arise in the treatment volume. Further, overdose or underdose regions can exist when separate radiation fields are used to deliver additional radiation. These aspects require that practical dose measurement (dosimetry) techniques be able to integrate dose over time and easily measure dose distributions in 3D with high spatial resolution. Traditional dosimeters, such as ion chambers, thermoluminescent dosimeters and radiographic film do not fulfil these requirements. Novel gel dosimetry techniques are being developed in which dose distributions can potentially be determined in vitro in 3D using anthropomorphic phantoms to simulate a clinically irradiated situation. As long ago as the 1950's, radiation-induced colour change in dyes was used to investigate radiation doses in gels. It was subsequently shown that radiation induced changes in nuclear magnetic resonance (NMR) relaxation properties of gels infused with conventional Fricke dosimetry solutions could be measured using magnetic resonance imaging (MRI). In Fricke gels, Fe 2+ ions in ferrous sulphate solutions are usually dispersed throughout a gelatin, agarose or PVA matrix. Radiation-induced changes in the dosimeters are considered to
Al-Karmi, Anan M; Ayaz, Ali Asghar H; Al-Enezi, Mamdouh S; Abdel-Rahman, Wamied; Dwaikat, Nidal
2015-09-01
Alanine dosimeters in the form of pure alanine powder in PMMA plastic tubes were investigated for dosimetry in a clinical application. Electron paramagnetic resonance (EPR) spectroscopy was used to measure absorbed radiation doses by detection of signals from radicals generated in irradiated alanine. The measurements were performed for low-dose ranges typical for single-fraction doses often used in external photon beam radiotherapy. First, the dosimeters were irradiated in a solid water phantom to establish calibration curves in the dose range from 0.3 to 3 Gy for 6 and 18 MV X-ray beams from a clinical linear accelerator. Next, the dosimeters were placed at various locations in an anthropomorphic pelvic phantom to measure the dose delivery of a conventional four-field box technique treatment plan to the pelvis. Finally, the doses measured with alanine dosimeters were compared against the doses calculated with a commercial treatment planning system (TPS). The results showed that the alanine dosimeters have a highly sensitive dose response with good linearity and no energy dependence in the dose range and photon beams used in this work. Also, a fairly good agreement was found between the in-phantom dose measurements with alanine dosimeters and the TPS dose calculations. The mean value of the ratios of measured to calculated dose values was found to be near unity. The measured points in the in-field region passed dose-difference acceptance criterion of 3% and those in the penumbral region passed distance-to-agreement acceptance criterion of 3 mm. These findings suggest that the pure alanine powder in PMMA tube dosimeter is a suitable option for dosimetry of radiotherapy photon beams.
Pulse-resolved radiotherapy dosimetry using fiber-coupled organic scintillators
DEFF Research Database (Denmark)
Beierholm, Anders Ravnsborg
scintillators and can be perceived as a well characterized, independent alternative to the methods that are in clinical use today. The dosimeter itself does not require a voltage supply, and is composed of water equivalent materials. The dosimeter can be fabricated with a sensitive volume smaller than a cubic...... millimeter, which is small enough to resolve the small radiation fields encountered in modern radiotherapy. The fast readout of the dosimeter enables measurements on the same time scale as the pulsed radiation delivery from the medical linear accelerators used for treatment. The dosimetry system, comprising...... for both standard and small fields. This thesis concludes that the new pulse-resolved dosimetry system holds great potential for modern radiotherapy applications, such as stereotactic radiotherapy and intensity-modulated radiotherapy....
Energy Technology Data Exchange (ETDEWEB)
Blazy-Aubignac, L
2007-09-15
The treatment planning systems (T.P.S.) occupy a key position in the radiotherapy service: they realize the projected calculation of the dose distribution and the treatment duration. Traditionally, the quality control of the calculated distribution doses relies on their comparisons with dose distributions measured under the device of treatment. This thesis proposes to substitute these dosimetry measures to the profile of reference dosimetry calculations got by the Penelope Monte-Carlo code. The Monte-Carlo simulations give a broad choice of test configurations and allow to envisage a quality control of dosimetry aspects of T.P.S. without monopolizing the treatment devices. This quality control, based on the Monte-Carlo simulations has been tested on a clinical T.P.S. and has allowed to simplify the quality procedures of the T.P.S.. This quality control, in depth, more precise and simpler to implement could be generalized to every center of radiotherapy. (N.C.)
Pulse-resolved radiotherapy dosimetry using fiber-coupled organic scintillators
Energy Technology Data Exchange (ETDEWEB)
Ravnsborg Beierholm, A.
2011-05-15
This PhD project pertains to the development and adaptation of a dosimetry system that can be used to verify the delivery of radiation in modern radiotherapy modalities involving small radiation fields and dynamic radiation delivery. The dosimetry system is based on fibre-coupled organic scintillators and can be perceived as a well characterized, independent alternative to the methods that are in clinical use today. The dosimeter itself does not require a voltage supply, and is composed of water equivalent materials. The dosimeter can be fabricated with a sensitive volume smaller than a cubic millimeter, which is small enough to resolve the small radiation fields encountered in modern radiotherapy. The fast readout of the dosimeter enables measurements on the same time scale as the pulsed radiation delivery from the medical linear accelerators used for treatment. The dosimetry system, comprising fiber-coupled organic scintillators and data acquisition hardware, was developed at the Radiation Research Division at Risoe DTU and tested using clinical x-ray beams at hospitals in Denmark and abroad. Measurements of output factors and percentage depth dose were performed and compared with reference values and Monte Carlo simulations for static square radiation fields for standard (4 cm x 4 cm to 20 cm x 20 cm) and small (down to 0.6 cm x 0.6 cm) field sizes. The accuracy of most of the obtained measurements was good, agreeing with reference and simulated dose values to within 2 % standard deviation for both standard and small fields. This thesis concludes that the new pulse-resolved dosimetry system holds great potential for modern radiotherapy applications, such as stereotactic radiotherapy and intensity-modulated radiotherapy. (Author)
Pulse-resolved radiotherapy dosimetry using fiber-coupled organic scintillators
International Nuclear Information System (INIS)
Ravnsborg Beierholm, A.
2011-05-01
This PhD project pertains to the development and adaptation of a dosimetry system that can be used to verify the delivery of radiation in modern radiotherapy modalities involving small radiation fields and dynamic radiation delivery. The dosimetry system is based on fibre-coupled organic scintillators and can be perceived as a well characterized, independent alternative to the methods that are in clinical use today. The dosimeter itself does not require a voltage supply, and is composed of water equivalent materials. The dosimeter can be fabricated with a sensitive volume smaller than a cubic millimeter, which is small enough to resolve the small radiation fields encountered in modern radiotherapy. The fast readout of the dosimeter enables measurements on the same time scale as the pulsed radiation delivery from the medical linear accelerators used for treatment. The dosimetry system, comprising fiber-coupled organic scintillators and data acquisition hardware, was developed at the Radiation Research Division at Risoe DTU and tested using clinical x-ray beams at hospitals in Denmark and abroad. Measurements of output factors and percentage depth dose were performed and compared with reference values and Monte Carlo simulations for static square radiation fields for standard (4 cm x 4 cm to 20 cm x 20 cm) and small (down to 0.6 cm x 0.6 cm) field sizes. The accuracy of most of the obtained measurements was good, agreeing with reference and simulated dose values to within 2 % standard deviation for both standard and small fields. This thesis concludes that the new pulse-resolved dosimetry system holds great potential for modern radiotherapy applications, such as stereotactic radiotherapy and intensity-modulated radiotherapy. (Author)
Development of dose audits for complex treatment techniques in radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Stefanic, A. M.; Molina, L.; Vallejos, M.; Montano, G.; Zaretzky, A.; Saravi, M., E-mail: stefanic@cae.cnea.gov.ar [Centro Regional de Referencia con Patrones Secundarios para Dosimetria - CNEA, Presbitero Juan Gonzalez y Aragon 15, B1802AYA Ezeiza (Argentina)
2014-08-15
This work was performed in the frame of a Coordinated Research Project (CRP) with IAEA whose objective was to extend the scope of activities carried out by national TLD-based networks from dosimetry audit for rectangular radiation fields to irregular and small fields relevant to modern radiotherapy. External audit is a crucial element in QA programmes for clinical dosimetry in radiotherapy, therefore a methodology and procedures were developed and were made available for dose measurement of complex radiotherapy parameters used for cancer treatment. There were three audit steps involved in this CRP: TLD based dosimetry for irregular MLC fields for conformal radiotherapy, dosimetry in the presence of heterogeneities and 2D MLC shaped fields relevant to stereotactic radiotherapy and applicable to dosimetry for IMRT. In addition, a new development of film-based 2D dosimetry for testing dose distributions in small field geometry was included. The plan for each audit step involved a pilot study and a trial audit run with a few local hospitals. The pilot study focused on conducting and evaluation of the audit procedures with all participants. The trial audit run was the running of the audit procedures by the participants to test them with a few local radiotherapy hospitals. This work intends to provide audits which are much nearer clinical practice than previous audits as they involve significant testing of Tps methods, as well as verifications to determinate whether hospitals can correctly calculate dose delivery in radiation treatments. (author)
Development of dose audits for complex treatment techniques in radiotherapy
International Nuclear Information System (INIS)
Stefanic, A. M.; Molina, L.; Vallejos, M.; Montano, G.; Zaretzky, A.; Saravi, M.
2014-08-01
This work was performed in the frame of a Coordinated Research Project (CRP) with IAEA whose objective was to extend the scope of activities carried out by national TLD-based networks from dosimetry audit for rectangular radiation fields to irregular and small fields relevant to modern radiotherapy. External audit is a crucial element in QA programmes for clinical dosimetry in radiotherapy, therefore a methodology and procedures were developed and were made available for dose measurement of complex radiotherapy parameters used for cancer treatment. There were three audit steps involved in this CRP: TLD based dosimetry for irregular MLC fields for conformal radiotherapy, dosimetry in the presence of heterogeneities and 2D MLC shaped fields relevant to stereotactic radiotherapy and applicable to dosimetry for IMRT. In addition, a new development of film-based 2D dosimetry for testing dose distributions in small field geometry was included. The plan for each audit step involved a pilot study and a trial audit run with a few local hospitals. The pilot study focused on conducting and evaluation of the audit procedures with all participants. The trial audit run was the running of the audit procedures by the participants to test them with a few local radiotherapy hospitals. This work intends to provide audits which are much nearer clinical practice than previous audits as they involve significant testing of Tps methods, as well as verifications to determinate whether hospitals can correctly calculate dose delivery in radiation treatments. (author)
Alanine-ESR dosimetry for radiotherapy IAEA experience
International Nuclear Information System (INIS)
Mehta, K.; Girzikowsky, R.; )
1997-01-01
At present, the most commonly used transfer dosimeters for radiotherapy applications are TL dosemeters. They are being used for intercomparison between SSDLs (about 70) and the IAEA dosimetry laboratory. However, there are some undesirable characteristics of this dosimetry system. We have a study in progress at the IAEA to evaluate the alanine-ESR systems as an alternative to TLDs. There are several desirable qualities which make alanine an attractive dosemeter. Preliminary data suggest that the alanine-ESR dosimetry system has the potential to replace TLDs for intercomparison amongst SSDLs in the therapy-level dose regions. (Author)
TRS 398 dosimetry protocol for radiotherapy
International Nuclear Information System (INIS)
Palmans, H.; Smyth, V.
2004-01-01
Full text: In recent years, international codes of practice based on absorbed dose to water standards have been published for the clinical reference dosimetry of external beams. It has become widely accepted that dosimetry of radiotherapeutic beams should be based on these standards. These codes of practice are a major improvement over earlier ones that used air kerma calibration factors as they are based on a calibration directly in a phantom in terms of the quantity of interest. The previous codes begin with calibration in air in terms of air kerma, then use theoretical and generic conversion factors to obtain dose to water that do not take account of chamber-to-chamber variation. Other good reasons for implementing the new codes are that they are conceptually simpler, include improved physical data and improve the consistency for various ionisation chamber types as well as between different beam types. TRS-3982,3 is a new Code of Practice (CoP) for reference dosimetry of external radiotherapy beams based on absorbed dose to, water calibrations and was published by the IAEA in a joint effort with the WHO, PAHO and ESTRO. It is the first CoP of its kind comprehensively covering all external radiotherapy beams except neutrons. The Radiotherapy Interest Group (RJG) of the ACPSEM has recommended that radiotherapy centres in Australia and New Zealand implement this CoP by the end of 2004. In this workshop, the general philosophy of the CoP will be outlined which will provide a framework for each of the individual subcodes. Although it represents just one of the potential implementations of the CoP, this workshop will deal only with dosimetry based on a cylindrical ionisation chamber with an absorbed dose calibration factor in 60Co from the standards laboratory. With the framework of the code in mind, it is straightforward to identify the basic steps that are required for measuring absorbed dose under reference conditions in a high-energy photon beam. The same is true
Energy Technology Data Exchange (ETDEWEB)
Ismail, A.; Giraud, J.Y.; Sihanath, R.; Balosso, J. [University Hospital of Grenoble, Dept. of Radiotherapy, 38 - Grenoble (France); Ismail, A. [Syrian Atomic Energy Commission, Radioprotection Dept., Damascus (Syrian Arab Republic); Luc, G.N.; Pittet, P.; Galvanc, J.M. [Claude-Bernard Univ., Lyon Nanotechnology Institute, 69 - Lyon (France)
2009-06-15
The quality insurance in radiotherapy in the frame of highly complex technical process as Intensity modulated radiotherapy (I.M.R.T.) needs independent control of the delivered dose to the patient. Actually, up to now, most of the radiotherapy treatments rely only on computed dosimetry through a rather complicated series of linked simulation tool. This dosimetry approach requires also qualified treatment means based on cautious quality insurance procedures. However, erroneous parameters could be difficult to detect and systematical errors could happen leading to radiotherapy accidents. In this context, in vivo dosimetry has a critical role of final control of the delivered dose. As many beam incidences and ports are used for any photon therapy treatment, external control could be very tedious and time consuming. Therefore, innovations are needed for in vivo dosimetry to provide ergonomic and efficient tools for these controls. This paper presents a review of technologies and products that can be used for in vivo dosimetry. It proposes also a reflection on the concepts to develop future devices suitable for this purpose. The technical means with their physical principles are reviewed, the clinical experiences demonstrating the feasibility of new techniques are then summarized and finally, the early clinical use and its impact on clinical practice is review. (authors)
Dosimetry audits and intercomparisons in radiotherapy: A Malaysian profile
M. Noor, Noramaliza; Nisbet, A.; Hussein, M.; Chu S, Sarene; Kadni, T.; Abdullah, N.; Bradley, D. A.
2017-11-01
Quality audits and intercomparisons are important in ensuring control of processes in any system of endeavour. Present interest is in control of dosimetry in teletherapy, there being a need to assess the extent to which there is consistent radiation dose delivery to the patient. In this study we review significant factors that impact upon radiotherapy dosimetry, focusing upon the example situation of radiotherapy delivery in Malaysia, examining existing literature in support of such efforts. A number of recommendations are made to provide for increased quality assurance and control. In addition to this study, the first level of intercomparison audit i.e. measuring beam output under reference conditions at eight selected Malaysian radiotherapy centres is checked; use being made of 9 μm core diameter Ge-doped silica fibres (Ge-9 μm). The results of Malaysian Secondary Standard Dosimetry Laboratory (SSDL) participation in the IAEA/WHO TLD postal dose audit services during the period between 2011 and 2015 will also been discussed. In conclusion, following review of the development of dosimetry audits and the conduct of one such exercise in Malaysia, it is apparent that regular periodic radiotherapy audits and intercomparison programmes should be strongly supported and implemented worldwide. The programmes to-date demonstrate these to be a good indicator of errors and of consistency between centres. A total of ei+ght beams have been checked in eight Malaysian radiotherapy centres. One out of the eight beams checked produced an unacceptable deviation; this was found to be due to unfamiliarity with the irradiation procedures. Prior to a repeat measurement, the mean ratio of measured to quoted dose was found to be 0.99 with standard deviation of 3%. Subsequent to the repeat measurement, the mean distribution was 1.00, and the standard deviation was 1.3%.
MOSFET Dosimetry for Evaluation of Gonad Shielding during Radiotherapy
International Nuclear Information System (INIS)
Kim, Hwi Young; Choi, Yun Seok; Park, So Yeon; Park, Yang Kyun; Ye, Sung Joon
2011-01-01
In order to confirm feasibility of MOSFET modality in use of in vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of 7.5 cm x 9.5 cm x 5.5 cm sized case and 9 cm x 9.5 cm x 1 cm sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality
MOSFET Dosimetry for Evaluation of Gonad Shielding during Radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Kim, Hwi Young; Choi, Yun Seok; Park, So Yeon; Park, Yang Kyun [Seoul National University College of Medicine, Seoul (Korea, Republic of); Ye, Sung Joon [Seoul National University, Seoul (Korea, Republic of)
2011-03-15
In order to confirm feasibility of MOSFET modality in use of in vivo dosimetry, evaluation of gonad shielding in order to minimize gonadal dose of patients undergoing radiotherapy by using MOSFET modality was performed. Gonadal dose of patients undergoing radiotherapy for rectal cancer in the department of radiation oncology of Seoul National University Hospital since 2009 was measured. 6 MV and 15 MV photon beams emitted from Varian 21EX LINAC were used for radiotherapy. In order to minimize exposed dose caused by the scattered ray not only from collimator of LINAC but also from treatment region inside radiation field, we used box.shaped lead shielding material. The shielding material was made of the lead block and consists of 7.5 cm x 9.5 cm x 5.5 cm sized case and 9 cm x 9.5 cm x 1 cm sized cover. Dosimetry for evaluation of gonad shielding was done with MOSFET modality. By protecting with gonad shielding material, average gonadal dose of patients was decreased by 23.07% compared with reference dose outside of the shielding material. Average delivered gonadal dose inside the shielding material was 0.01 Gy. By the result of MOSFET dosimetry, we verified that gonadal dose was decreased by using gonad shielding material. In compare with TLD dosimetry, we could measure the exposed dose easily and precisely with MOSFET modality.
Experimental dosimetry in conformal breast teletherapy compared with the planning system
International Nuclear Information System (INIS)
Nogueira, Luciana Batista; Silva, Hugo Leonardo Lemos; Passos Ribeiro de Campos, Tarcísio
2015-01-01
The objective of this study was to compare and analyse the absorbed dose profiles from the conformal radiotherapy planning and experimental dosimetry taken in a breast anthropomorphic and anthropometric phantom. Conformal radiotherapy planning was elaborated in the Treatment Planning System (TPS). EBT2 Gafchromic radiochromic films were applied as dosimeters, positioned internally and superficially in the breast phantom. The standard radiation protocol was applied in the breast phantom. The films were digitalised, and their responses were analysed in RGB. The optical densities were processed, reproducing the spatial dose distribution. - Highlights: • Distributions of absorbed doses were generated by the TPS and measured by radiochromic films. • The breast phantom simulated a human breast in position for treatment. • A large portion of the glandular tissue absorbed doses that were equivalent to the radiotherapy planning. • There were regions of hot spots and small areas of under dosage in deeper areas at the lung interface
Water-equivalent plastic scintillation detectors for radiotherapy dosimetry
International Nuclear Information System (INIS)
Beddar, A.S.
1995-01-01
Plastic scintillation dosimetry is a promising new method of measuring absorbed dose for high energy radiotherapy beams. The theory behind this concept will be presented along with the many advantages that it offers over conventional dosimetry. A variety of plastic scintillation detector systems have been recently developed for photon and electron dosimetry. These new water-equivalent detectors use small to miniature plastic scintillators. Their attractive feature lies in their use for field mapping in water, particularly for small fields, high dose gradient regions, and near inhomogeneous interfaces, or for in-vivo insertions. The physical characteristics and the dosimetric properties of these scintillators will be presented, discussed, and compared to the commonly used detectors in radiation dosimetry. The system first used successfully for multi-purpose radiotherapy field mapping, as well as other systems, will be described. The technical challenges of the design of these detectors including the optical coupling to small fibers will be discussed. One of the limitations, at the present time, is the radiation-induced light produced in the optical fibers that are used to transmit the signal to the photodetectors. The mechanisms of these spurious effects will be identified and discussed with emphasis on signal-to-noise improvements
Improving TL dosimetry for external radiotherapy
International Nuclear Information System (INIS)
Bustos, S.R.; Velez, G.; Rubio, M.
1998-01-01
Full text: In vivo thermoluminescence dosimetry (TLD) has always been one of the most accurate dosimetry method for external radiotherapy control, but the delay in the response is a well know drawback when it is applied. In this work we show some improvements and demonstrate that keeping the precision and accuracy of this technique, it is possible to obtain a response in few hours. Harshaw 4000 TL reader and LiF TLD-100 dosimeters, chips (3,1 x 3,1 x 0,9 mm 3 ) and rods (1 x 1 x 6 mm 3 ) have been used. The thermal treatment necessary to reuse the TLD is only 1h at 400 degree C, by using a glow curve analyser developed at the Ciemat (Spain), that allows a complete, prompt and precise identification of the individuals peaks. The dosimeters are periodically and individually calibrated. We also have study the factors contributing to the relation TL-dose like linearity, energy correction, directional response and fading. All those results are included into an Excel worksheet which automatically give us the dose resulting from the TL reading (peaks areas 4 and 5). The obtained uncertainty is better than 5%. The TLD already irradiated in radiotherapy institutions distant 30-40 Km from our centre can be read and analysed in about 3-4 hours. These facts render our methods rapid and allow a better control of radiotherapy treatment even if it is bi-fractionated. (author) [es
In vivo dosimetry in external beam radiotherapy
International Nuclear Information System (INIS)
Mijnheer, Ben; Beddar, Sam; Izewska, Joanna; Reft, Chester
2013-01-01
In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors’ opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks
In vivo dosimetry in external beam radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Mijnheer, Ben [Department of Radiation Oncology, Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Amsterdam 1066 CX (Netherlands); Beddar, Sam [Department of Radiation Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States); Izewska, Joanna [Division of Human Health, International Atomic Energy Agency, Vienna 1400 (Austria); Reft, Chester [Department of Radiation and Cellular Oncology, University of Chicago Medical Center, Chicago, Illinois 60637 (United States)
2013-07-15
In vivo dosimetry (IVD) is in use in external beam radiotherapy (EBRT) to detect major errors, to assess clinically relevant differences between planned and delivered dose, to record dose received by individual patients, and to fulfill legal requirements. After discussing briefly the main characteristics of the most commonly applied IVD systems, the clinical experience of IVD during EBRT will be summarized. Advancement of the traditional aspects of in vivo dosimetry as well as the development of currently available and newly emerging noninterventional technologies are required for large-scale implementation of IVD in EBRT. These new technologies include the development of electronic portal imaging devices for 2D and 3D patient dosimetry during advanced treatment techniques, such as IMRT and VMAT, and the use of IVD in proton and ion radiotherapy by measuring the decay of radiation-induced radionuclides. In the final analysis, we will show in this Vision 20/20 paper that in addition to regulatory compliance and reimbursement issues, the rationale for in vivo measurements is to provide an accurate and independent verification of the overall treatment procedure. It will enable the identification of potential errors in dose calculation, data transfer, dose delivery, patient setup, and changes in patient anatomy. It is the authors' opinion that all treatments with curative intent should be verified through in vivo dose measurements in combination with pretreatment checks.
Clinical application of radiation dosimetry on X-ray radiotherapy
International Nuclear Information System (INIS)
Mizutani, Takeo
1995-01-01
In the case of radiotherapy, it is important to give proper dose for a tumor, to be treated with the objective of therapy, and to evaluate the dose, considering dose for other organs at risk to a sufficient extent. To provide an exposure dose at the target volume of tumor parts, it should be required to get a good understanding of the correct dosimetric method and also to apply this to clinical application in practice. All over the country, so as not to produce any difference in the given dose, 'A practical code for the dosimetry of high energy X-rays in radiotherapy' was issued by the Japanese Associations of radiological physicists in 1972. In 1986, it was revised. At about 85% of therapeutic facilities in the country, radiation engineers perform dose measurements and controls. Therefore, I have explained the process of measurement and dose calculation, with the main objective directed at the engineers in charge of the radiotherapy so as to easily radiation dosimetry of X-ray with dosemeters and phantom used at each facility according to the 'practical code'. (author)
A reusable OSL-film for 2D radiotherapy dosimetry
Wouter, Crijns; Dirk, Vandenbroucke; Paul, Leblans; Tom, Depuydt
2017-11-01
Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Z eff). The current work studied the applicability of a 2D OSL-film with a reduced Z eff as (IMRT/VMAT) dosimeter. Based on their commercial OSL-film experience, Agfa Healthcare N.V. produced a new experimental OSL-film for RT dosimetry. This film had a lower effective atomic number compared to the films used in radiology. Typical 2D dosimeter requirements such as uniformity, dose response, signal stability with time, and angular dependence were evaluated. Additionally, the impact of a possible residual energy dependence was assessed for the infield as well as the out-of-field region of both static beams and standard intensity modulated patterns (chair and pyramid). The OSL-film’s reusable nature allowed for a film specific absolute and linear calibration including a flood-field uniformity correction. The OSL-film was scanned with a CR-15X engine based reader using a strict timing (i.e. 4 min after ‘beam on’ or as soon as possible) to account for spontaneous recombination. The OSL-film had good basic response properties: non-uniformities ⩽2.6%, a linear dose response (0-32 Gy), a linear signal decay (0.5% min-1) over the 20 min measured, and limited angular dependence ⩽2.6%. Due to variations of the energy spectrum, larger dose differences were noted outside the central region of the homogenous phantom and outside both static and IMRT fields. However, the OSL-film’s measured dose differences of the IMRT patterns were lower than those of Gafchromic EBT measurements ([-1.6%, 2.1%] versus [-2.9%, 3.6%]). The current OSL-film could be used as a reusable high resolution dosimeter with read-out immediately after
Comparison of DVH data from multiple radiotherapy treatment planning systems
International Nuclear Information System (INIS)
Ebert, M A; Kearvell, R; Hooton, B; Spry, N A; Bydder, S A; Joseph, D J; Haworth, A; Hug, B
2010-01-01
This study examined the variation of dose-volume histogram (DVH) data sourced from multiple radiotherapy treatment planning systems (TPSs). Treatment plan exports were obtained from 33 Australian and New Zealand centres during a dosimetry study. Plan information, including DVH data, was exported from the TPS at each centre and reviewed in a digital review system (SWAN). The review system was then used to produce an independent calculation of DVH information for each delineated structure. The relationships between DVHs extracted from each TPS and independently calculated were examined, particularly in terms of the influence of CT scan slice and pixel widths, the resolution of dose calculation grids and the TPS manufacturer. Calculation of total volume and DVH data was consistent between SWAN and each TPS, with the small discrepancies found tending to increase with decreasing structure size. This was significantly influenced by the TPS model used to derive the data. For target structures covered with relatively uniform dose distributions, there was a significant difference between the minimum dose in each TPS-exported DVH and that calculated independently. (note)
Endocavitary in vivo Dosimetry for IMRT Treatments of Gynecologic Tumors
International Nuclear Information System (INIS)
Cilla, Savino; Macchia, Gabriella; Digesù, Cinzia; Deodato, Francesco; Sabatino, Domenico; Morganti, Alessio G.; Piermattei, Angelo
2011-01-01
The accuracy and reproducibility of endometrial carcinoma treatment with intensity-modulated radiotherapy (IMRT) was assessed by means of in vivo dosimetry. Six patients who had previously undergone radical hysterectomy for endometrial carcinoma were treated with IMRT using a vaginal applicator with radio-opaque fiducial markers. An ion-chamber inserted into the applicator supplied an endocavitary in vivo dosimetry for quality assurance purposes. The ratio R = D/D TPS between the in vivo measured dose D and the predicted dose by the treatment planning system D TPS was determined for every fraction of the treatment. Results showed that 90% and 100% of the ratios resulted equal to 1 within 5% and 10%, respectively. The mean value of the ratios distribution for the 6 patients was R = 0.995 and the SD = 0.034. The ratio R* between the measured and predicted total doses for each patient was near to 1, within 2%. The dosimetric results suggest that the use of a vaginal applicator in an image-guided approach could make the interfractions target position stable and reproducible, allowing a safe use of the IMRT technique in the treatment of postoperative vaginal vault. In vivo dosimetry may supply useful information about the discrimination of random vs. systematic errors. The workload is minimum and this in vivo dosimetry can be applied also in the clinical routine.
Synthetic diamond devices for medical dosimetry applied to radiotherapy
International Nuclear Information System (INIS)
Descamps, C.
2007-06-01
The aim of this thesis, lead in the framework of an integrated European project entitled M.A.E.S.T.R.O. for ' Methods and Advanced Equipment for Simulation and Treatment in Radio Oncology', was to develop and test synthetic diamond detector in clinical environment for new modalities used in radiotherapy. Diamond is a good candidate for the detection of high energy beams in medical fields. It can be used for passive dosimetry, as thermoluminescent dosimeters or for active dosimetry as ionisation chambers. These two applications are presented here. Concerning the thermoluminescence, several impurities or dopants (boron, phosphorus, and nitrogen) have been incorporated in the diamond films during growth, in order to modify the material dosimetric properties and a detailed study of nitrogen-containing films is proposed. The second part presents the results obtained in active dosimetry. Two guide lines were followed: the measurement set-up optimisation and the material modification. The first dosimetric studies under radiotherapy beams concerning nitrogen-containing polycrystalline diamond as well as high purity single crystal diamond are conclusive. The detectors behaviours are in agreement with the recommendations of the International Atomic Energy Agency (IAEA). (author)
Energy Technology Data Exchange (ETDEWEB)
Fornet R, O. M.; Perez G, F., E-mail: nuclear2@citmahlg.holguin.inf.cu [Delegacion Territorial del CITMA, Peralta 16 esq. P. Feria, Rpto. Peralta, 80400 Holguin (Cuba)
2014-08-15
Dosimetry in its various forms plays a determining role on the radiological risks prevention in radiotherapy. To prove this in this paper is shown an analysis based on the risk matrix method, how the dosimetry can influence in each stages of a radiotherapy service; installation and acceptance, operation, maintenance and calibration. For each one of these stages the role that can play is analyzed as either the initiating event of a radiological accident or limiting barrier of these events of the dosimetric processes used for the individual dosimetry, the area monitoring, fixed or portable, for radiation beam dosimetry and of the patients for a radiotherapy service with cobalt-therapy equipment. The result of the study shows that the application of a prospective approach in the role evaluation of dosimetry in the prevention and mitigation of the consequences of a radiological accident in radiotherapy is crucial and should be subject to permanent evaluation at each development stage of these services. (author)
In vivo dosimetry with diodes in a radiotherapy department in Pakistan
International Nuclear Information System (INIS)
Tunio, M.; Rafi, M.; Ali, S.; Ahmed, Z.; Zameer, A.; Hashmi, A.; Maqbool, S. A.
2011-01-01
The International Commission of Radiological Units (ICRU) sets a tolerance of ±5 % on dose delivery, with more recent data limiting the overall tolerances to ±3 %. One of the best methods for accurate dose delivery and quality check is in vivo dosimetry, while radiotherapy is performed. The present study was carried out to test the applicability of diodes for performing in vivo entrance dose measurements in external photon beam radiotherapy for pelvic tumours and its implementation as quality assurance tool in radiotherapy. During November 2007 to December 2009, in 300 patients who received pelvic radiotherapy on a multi-leaf-collimator-assisted linear accelerator, the central axis dose was measured by in vivo dosimetry by p-Si diodes. Entrance dose measurements were taken by diodes and were compared with the prescribed dose. Totally 1000 calculations were performed. The mean and standard deviation between measured and prescribed dose was 1.26 ± 2.8 %. In 938 measurements (93.8 %), the deviation was 5 % (5.51 ± 2.3 %). Larger variations were seen in lateral and oblique fields more than anteroposterior fields. For larger deviations, patients and diode positional errors were found to be the common factors alone or in combination with other factors. After additional corrections, repeated measurements were achieved within tolerance levels. This study showed that diode-detector-based in vivo dosimetry was simple, cost-effective, provides quick results and can serve as a useful quality assurance tool in radiotherapy. The data acquired in the present study can be used for evaluating output calibration of therapy machine, precision of calculations, effectiveness of treatment plan and patient setup. (authors)
The Radiotherapy Dosimetry Audit System In the UK
International Nuclear Information System (INIS)
Thwaites, D.I.
1999-01-01
Two national radiotherapy dosimetry intercomparisons have been earned out in the UK, involving all radiotherapy institutes. The first was concerned with megavoltage photon beams and looked at beam calibration and simple three-field planned distributions in a geometric phantom. The intercomparisons were carried out by an independent intercomparison physicist visiting each department in turn and making measurements with ion chambers, following a fixed protocol. The beam calibration intercomparison was earned out on every 60 C o beam and every MV x-ray beam, whilst the planned comparisons were carried out on one beam only. The plans included effects of wedges, oblique incidence and inhomogeneities. The study was unfunded and took a significant time (1988-1991) to cover the 65 or so centres. It was followed up by a national electron dosimetry intercomparison which was fended (Department of Health) and which ran from 1994-1996. This audited three electron beam energies in each centre (depth dose, beam energy, dose calibration) and also included a follow-up of the original photon beam intercomparison. In general these studies showed good consistency of dosimetry across the UK centres, with mean (measured/locally stated) doses being close to unity and standard deviations of the distributions of values being approx. 1.5 and 1% for photons, 1.8% for electrons for beam calibration and 2.5-3.5% for the planned multi-beam situations. 97-100% of measurements were within the pre-set 3% tolerance for beam calibration and around 90% of the measurements within a pre-set 5% tolerance for planned situations. The studies did highlight some areas where increased on Q A could provide benefits. In particular the photon intercomparison discovered one 60 C o unit mis calibration which led to national recommendations for the implementation of Quality Systems in radiotherapy departments
Palmer, Antony L; Nash, David; Kearton, John R; Jafari, Shakardokht M; Muscat, Sarah
2017-12-01
External dosimetry audit is valuable for the assurance of radiotherapy quality. However, motion management has not been rigorously audited, despite its complexity and importance for accuracy. We describe the first end-to-end dosimetry audit for non-SABR (stereotactic ablative body radiotherapy) lung treatments, measuring dose accumulation in a moving target, and assessing adequacy of target dose coverage. A respiratory motion lung-phantom with custom-designed insert was used. Dose was measured with radiochromic film, employing triple-channel dosimetry and uncertainty reduction. The host's 4DCT scan, outlining and planning techniques were used. Measurements with the phantom static and then moving at treatment delivery separated inherent treatment uncertainties from motion effects. Calculated and measured dose distributions were compared by isodose overlay, gamma analysis, and we introduce the concept of 'dose plane histograms' for clinically relevant interpretation of film dosimetry. 12 radiotherapy centres and 19 plans were audited: conformal, IMRT (intensity modulated radiotherapy) and VMAT (volumetric modulated radiotherapy). Excellent agreement between planned and static-phantom results were seen (mean gamma pass 98.7% at 3% 2 mm). Dose blurring was evident in the moving-phantom measurements (mean gamma pass 88.2% at 3% 2 mm). Planning techniques for motion management were adequate to deliver the intended moving-target dose coverage. A novel, clinically-relevant, end-to-end dosimetry audit of motion management strategies in radiotherapy is reported. Copyright © 2017 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Ottosson, Wiviann; Behrens, C. F.; Andersen, Claus E.
2015-01-01
Bone, air passages, cavities, and lung are elements present in patients, but challenging to properly correct for in treatment planning dose calculations. Plastic scintillator detectors (PSDs) have proven to be well suited for dosimetry in non-reference conditions such as small fields. The objective...... of this study was to investigate the performance of a commercial treatment planning system (TPS) using a PSD and a specially designed thorax phantom with lung tumor inserts. 10 treatment plans of different complexity and phantom configurations were evaluated. Although the TPS agreed well with the measurements...
The UK radiotherapy dosimetry audit network
International Nuclear Information System (INIS)
Thwaites, D.I.
2002-01-01
Full text: Radiotherapy dosimetry intercomparison in the UK has been carried out in limited studies since the 1960s. However the first national dosimetry intercomparison involving all radiotherapy centres was conducted in the late 1980s. This was based on visits to each centre, using ionisation chamber dosimetry. It audited megavoltage photon beam calibration and other single field parameters. It also measured doses in a three-field 'treatment' in a trapezoidal phantom constructed from epoxy-resin water-equivalent material and compared these to locally planned doses. This included off-axis points, oblique incidence, inhomogeneities, etc. The study found mean measured beam calibration doses close to stated values (ratio 1.003), with a standard deviation (sd) of the distribution of 1.5% and 97% of doses within the pro-set 3% tolerance. For the planned multi-field irradiations, mean dose ratios (measured/stated) were 1.01 (sd 3%, 90% of results within 5%). A number of discrepancies were identified, leading to improved practice. A follow up study (mid-1990s) for electron beam audit also repeated the megavoltage photon calibration audit. For photons, an improvement was noted (mean ratio 1.003, sd 1.0%, 100% within 3%), whilst for electron beams, the mean ratio of measured/stated dose was 0.994 (sd 1.8%, 94% within 3%, 99% within 5%). In parallel with - and growing out of - this, a national audit network began to develop in 1991/2. It utilised similar methodology to the intercomparison and a network approach to allow parallel developments of the scope of the system. The network has eight regional groups, each with up to 10 radiotherapy centres, serving average populations of 7-8 million. Each group organises audits of its own centres and has developed at its own pace. Most have piloted methodology, phantoms, etc. for new audits which can then be used by other groups. All 65 UK centres are included. The network is co-ordinated by an IPEM Steering Committee (current chair
Energy Technology Data Exchange (ETDEWEB)
Descamps, C
2007-06-15
The aim of this thesis, lead in the framework of an integrated European project entitled M.A.E.S.T.R.O. for ' Methods and Advanced Equipment for Simulation and Treatment in Radio Oncology', was to develop and test synthetic diamond detector in clinical environment for new modalities used in radiotherapy. Diamond is a good candidate for the detection of high energy beams in medical fields. It can be used for passive dosimetry, as thermoluminescent dosimeters or for active dosimetry as ionisation chambers. These two applications are presented here. Concerning the thermoluminescence, several impurities or dopants (boron, phosphorus, and nitrogen) have been incorporated in the diamond films during growth, in order to modify the material dosimetric properties and a detailed study of nitrogen-containing films is proposed. The second part presents the results obtained in active dosimetry. Two guide lines were followed: the measurement set-up optimisation and the material modification. The first dosimetric studies under radiotherapy beams concerning nitrogen-containing polycrystalline diamond as well as high purity single crystal diamond are conclusive. The detectors behaviours are in agreement with the recommendations of the International Atomic Energy Agency (IAEA). (author)
Energy Technology Data Exchange (ETDEWEB)
Descamps, C
2007-06-15
The aim of this thesis, lead in the framework of an integrated European project entitled M.A.E.S.T.R.O. for ' Methods and Advanced Equipment for Simulation and Treatment in Radio Oncology', was to develop and test synthetic diamond detector in clinical environment for new modalities used in radiotherapy. Diamond is a good candidate for the detection of high energy beams in medical fields. It can be used for passive dosimetry, as thermoluminescent dosimeters or for active dosimetry as ionisation chambers. These two applications are presented here. Concerning the thermoluminescence, several impurities or dopants (boron, phosphorus, and nitrogen) have been incorporated in the diamond films during growth, in order to modify the material dosimetric properties and a detailed study of nitrogen-containing films is proposed. The second part presents the results obtained in active dosimetry. Two guide lines were followed: the measurement set-up optimisation and the material modification. The first dosimetric studies under radiotherapy beams concerning nitrogen-containing polycrystalline diamond as well as high purity single crystal diamond are conclusive. The detectors behaviours are in agreement with the recommendations of the International Atomic Energy Agency (IAEA). (author)
Skeletal dosimetry models for alpha-particles for use in molecular radiotherapy
Watchman, Christopher J.
Molecular radiotherapy is a cancer treatment methodology whereby a radionuclide is combined with a biologically active molecule to preferentially target cancer cells. Alpha-particle emitting radionuclides show significant potential for use in molecular radiotherapy due to the short range of the alpha-particles in tissue and their high rates of energy deposition. Current radiation dosimetry models used to assess alpha emitter dose in the skeleton were developed originally for occupational applications. In medical dosimetry, individual variability in uptake, translocation and other biological factors can result in poor correlation of clinical outcome with marrow dose estimates determined using existing skeletal models. Methods presented in this work were developed in response to the need for dosimetry models which account for these biological and patient-specific factors. Dosimetry models are presented for trabecular bone alpha particle dosimetry as well as a model for cortical bone dosimetry. These radiation transport models are the 3D chord-based infinite spongiosa transport model (3D-CBIST) and the chord-based infinite cortical transport model (CBICT), respectively. Absorbed fraction data for several skeletal tissues for several subjects are presented. Each modeling strategy accounts for biological parameters, such as bone marrow cellularity, not previously incorporated into alpha-particle skeletal dosimetry models used in radiation protection. Using these data a study investigating the variability in alpha-particle absorbed fractions in the human skeleton is also presented. Data is also offered relating skeletal tissue masses in individual bone sites for a range of ages. These data are necessary for dose calculations and have previously only been available as whole body tissue masses. A revised 3D-CBIST model is also presented which allows for changes in endosteum thickness to account for revised target cell location of tissues involved in the radiological
Introduction to dosimetry and risk estimation of second cancer induction following radiotherapy
International Nuclear Information System (INIS)
Harrison, R.M.
2013-01-01
This brief review of dosimetry in second cancer dosimetry introduces work carried out by Working Group 9 (Radiation Protection Dosimetry in Medicine) of the European Radiation Dosimetry Group (EURADOS). The work described in the following papers in this edition was presented at a Workshop on Dosimetry for Second Cancer Risk Estimation given at the EURADOS Annual meeting in Vienna on February 8th 2012. The work concentrates on the measurement of out-of-field doses in water tanks and BOMAB-like phantoms using a variety of dosimeters to measure photon and neutron doses. These include optically stimulated luminescence (OSL), radiophotoluminescence (RPL) and thermoluminescence (TLD) dosimeters for photon dosimetry (together with ion chambers for reference measurements traceable to primary standards) and track etch and bubble detectors for neutron measurements. A discussion of the various phantoms available for these measurements is presented together with a brief introduction to a model for the relationship between organ doses and the risk of induction of second cancers. The estimation of second cancer risks is not trivial and involves processes which are currently incompletely understood. However, progress in this field requires a robust foundation and methodology for the measurement or calculation of organ doses following radiotherapy, so that risks can be placed in perspective, algorithms for out-of-field doses can be compared with measured data, and future epidemiological studies may have a reliable foundation of organ dosimetry for retrospective dosimetry studies. -- Highlights: ► Brief review of second cancer induction following radiotherapy. ► Out-of-field doses for estimating risks to remote organs. ► Introduction to dosimetry techniques and dosimeters used. ► Out-of-field dose measurements in phantoms
Quality assurance in radiotherapy dosimetry in China
International Nuclear Information System (INIS)
Li Kaibao; Luo Suming; Cheng Jinsheng; He Zhijian; An Jinggang; Hu Yimin; Feng Ningyuan
2002-01-01
In 1995, the SSDL in the Laboratory of Industrial Hygiene cooperated with Beijing Cancer Hospital, Chinese Academy of Medical science joined the IAEA Co-ordinated Research Programme (NO.8769/RO). According to the requirements of the project, an External Audit Group (EAG) in China was established in 1996 with the responsibilities of operating TLD-based quality audit for radiotherapy dosimetry. Since then. The national TLD dose quality audit services have been carried out in 7 provinces in China. Besides this, the national programmes for brachytherapy and stereostatic radiosurgery (SRS) treatment dosimetry were initiated in 2001. The activity measurement intercomparison between the SSDL and some hospitals for Ir-192 HDR brachytherapy sources has been performed using a HDR well-type ionization chamber (Model HDR 1000 plus) and CDX-2000A Charge Digitizer, which were calibrated in Accredited Dosimetry Calibration Laboratory, University of Wisconsin, USA. The preliminary results indicated that the agreement between SSDL measured activity and hospital stated activity was within ±5% for more than 80% of total participants
External quality audit programmes for radiotherapy dosimetry and equipment
International Nuclear Information System (INIS)
Thwaites, D.I.
1997-01-01
It is widely accepted that individual radiotherapy centres should have in place a comprehensive quality assurance programme on all the necessary steps for the delivery of safe accurate treatment. As regards the performance of radiotherapy equipment and dosimetry, the most widely used process of external checking has been dosimetry intercomparison, comparing independently measured doses to locally stated doses in a variety of conditions. These have been at a number of different levels: from basic beam calibration; up to and including exercises employing anatomic or pseudo-anatomic phantoms and incorporating tests of treatment planning equipment and procedures. Some of these have been one-off exercises, whilst others are continuing, or have given rise to on-going quality audit programmes on a national (or wider) basis. A number of these have evolved, or are evolving, into audits which include external checking of the achievement of standards in performance of treatment equipment, as well as in the dosimetry in each institution involved. The principles and methodologies of the various types of external checking programmes for treatment equipment and dosimetry are reviewed, covering the experimental approaches and the tolerances applied. What is included in a given programme will, of necessity, depend on the resources available and the purpose of the exercise. Methods and tolerances must be matched to endpoint. Tolerance levels must take into account the experimental uncertainties of the measurement methods employed. Finally, external audit can only be used to complement, and in conjunction with, institutional quality assurance programmes and not as a substitute for them
Quality assurance in radiotherapy of mammary cancer
International Nuclear Information System (INIS)
Mangold, C.A.
2000-11-01
The outcome of breast conserving treatment, in terms of local control, cosmetic outcome, and complication rate depends on the quality of surgery and on the adequacy of the irradiation treatment performed. In the radiotherapy department of Leuven and the AKH Vienna about 70 % of all breast cancer patients are treated with breast conserving surgery and external radiotherapy. About 20 % of the patients treated with external radiotherapy receive an additional boost with pulse dose rate (PDR) or high dose rate (HDR) brachytherapy using Ir-192 sources. An investigation is performed to assess the accuracy of both treatment techniques. Secondly, the feasibility of in vivo measurements is studied for these two treatment techniques. For investigating the accuracy of the brachytherapy treatment two phantoms are manufactured to mimic a breast, one for TLD measurements, and one for film dosimetry using radiochromic films. The TLD phantom allows to measure at 34 dose points in three planes including the basal dose points. The film phantom is designed in such a way that films can be positioned in a plane parallel and orthogonal to the needles. In vivo measurements are simulated on one of the phantoms and carried out on 21 patients. The accuracy of the external radiotherapy treatment is checked with the thorax part of a commercially available Alderson phantom. It allows to perform measurements with TLDs in three different planes and with diodes on the surface. Furthermore, all diode characteristics and correction factors necessary for the clinical application are investigated. For the brachytherapy treatment the dose distributions calculated with the TPS are in good agreement with both TLD and radiochromic film measurements (average deviations of point doses < ± 6 %). However, close to the interface tissue-air the dose is overestimated by the TPS since it neglects the finite size of a breast and hence the associated lack of backscatter (average deviations of point doses up to -13
International Nuclear Information System (INIS)
Boutaleb, Samir
2010-01-01
This research thesis first reports a bibliographical study which addressed the use of ionizing radiations in cancer therapy (evolution from ionizing radiation to metabolic radiotherapy, biological and physical parameters, and absorbed dose in metabolic radiotherapy) and the role imagery has in customised dosimetry (absorbed dose calculation methods, determination of cumulative activity, dosimetric models for S factor calculation). Then, the author presents a software which has been specifically developed for the creation of dosimetric models, and reports its validation. He reports the comparison between different dosimetric models in the case of mice. He highlights two applications of the developed tool: radio-immunotherapy and metabolic radiotherapy. He finally proposes a general discussion on the impact of small animal dosimetry on metabolic radiotherapy [fr
Energy Technology Data Exchange (ETDEWEB)
Thompson, Larissa
2013-07-01
Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film
Radiotherapy Dosimetry Protocols For High Energy Photons And Electrons
International Nuclear Information System (INIS)
Thwaites, D.I.
1999-01-01
One vital requirement in radiotherapy is to ensure as closely as possible consistency in determination of dose between different centers and at different times, both within a given country and internationally, because the comparison and transfer of clinical experience and the evaluation of clinical trials is dependent on common statements of dose delivered. In addition at each loon] centre it is vital that the absorbed dose calibration of each beam is carried out to exacting and consistent standards, as this is the fundamental measurement upon which the quality of all treatments on that machine depend throughout its clinical lifetime. The systems in place to ensure consistency in dosimetry differ in the details from country to country, but all depend on the same basic considerations: - the use of ion chambers of similar design and similar construction materials, - traceable calibrations of these chambers to an accredited primary or secondary standard dosimetry laboratory (SSDL) in terms of some agreed relevant dosimetric quantity, - dose statements in terms of absorbed dose to a common material, water, - the application of an appropriate recommended national or international dosimetry protocol (or code of practice) which ensures commonality in the method of use of the calibrated ion chamber, the radiotherapy treatment beam calibration conditions and any data required to convert the ion chamber reading to absorbed dose to water, and - strict quality control on each step in this process
A methodology for dosimetry audit of rotational radiotherapy using a commercial detector array
International Nuclear Information System (INIS)
Hussein, Mohammad; Tsang, Yatman; Thomas, Russell A.S.; Gouldstone, Clare; Maughan, David; Snaith, Julia A.D.; Bolton, Steven C.; Nisbet, Andrew; Clark, Catharine H.
2013-01-01
Purpose: To develop a methodology for the use of a commercial detector array in dosimetry audits of rotational radiotherapy. Materials and methods: The methodology was developed as part of the development of a national audit of rotational radiotherapy. Ten cancer centres were asked to create a rotational radiotherapy treatment plan for a three-dimensional treatment-planning-system (3DTPS) test and audited. Phantom measurements using a commercial 2D ionisation chamber (IC) array were compared with measurements using 0.125 cm 3 IC, Gafchromic film and alanine pellets in the same plane. Relative and absolute gamma index (γ) comparisons were made for Gafchromic film and 2D-Array planes, respectively. Results: Comparisons between individual detectors within the 2D-Array against the corresponding IC and alanine measurement showed a statistically significant concordance correlation coefficient (both ρ c > 0.998, p < 0.001) with mean difference of −1.1 ± 1.1% and −0.8 ± 1.1%, respectively, in a high dose PTV. In the γ comparison between the 2D-Array and film it was that the 2D-Array was more likely to fail planes where there was a dose discrepancy due to the absolute analysis performed. Conclusions: It has been found that using a commercial detector array for a dosimetry audit of rotational radiotherapy is suitable in place of standard systems of dosimetry
EPR dosimetry for actual and suspected overexposures during radiotherapy treatments in Poland
International Nuclear Information System (INIS)
Trompier, F.; Sadlo, J.; Michalik, J.; Stachowicz, W.; Mazal, A.; Clairand, I.; Rostkowska, J.; Bulski, W.; Kulakowski, A.; Sluszniak, J.; Gozdz, S.; Wojcik, A.
2007-01-01
EPR dosimetry on bone samples was recently used for actual and suspected overexposures during radiotherapy treatments performed in Poland. In 2001 five breast-cancer patients undergoing radiotherapy in the Bialystok Oncology Center, Poland, were overexposed. The overexposure was due to a defective safety interlock and an obsolete safety system of the linear accelerator. For the three most exposed patients, pieces of rib bones removed during surgical reconstruction of the chest wall and skin transplantation allowed an estimation of the accident doses by electron paramagnetic resonance (EPR) spectrometry. The doses delivered during the accident were as high as 60-80 Gy. In 2005, a patient treated in Kielce Holy Cross Cancer Center exhibited similar deep necroses of the chest wall but 6 years following a 'standard upper mantel fields' radiotherapy for Hodgkin's disease. In order to investigate the possible late effect of an overexposure as necrosis origin, the delivered dose was afterward estimated by EPR dosimetry performed on a rib sample
Energy Technology Data Exchange (ETDEWEB)
Olbi, D.S.; Sales, C.P. [Universidade de Sao Paulo (USP), SP (Brazil). Faculdade de Medicina; Nakandakari, M.V.N., E-mail: diego.olbi@hc.fm.usp.br [Instituto do Cancer do Estado de Sao Paulo, SP (Brazil). Servico de Radioterapia
2016-07-01
The development of technologies compensator blocks, MLC, high dose rate accelerators, treatment planning systems, among others, permitted that new treatment techniques in radiotherapy were created. Such techniques have the capacity to modulate radiation beam fluency (IMRT, VMAT), or to deliver high doses in few fractions or unique fractions (SRS). Following the same tendency, quality control of planning became more complex. It is necessary to evaluate the fluency delivered by the accelerator. Its levels of does and its spatial distribution should co-occur with the fluency calculated by TPS. Acquisition of new detector devices in quality control of treatments is fundamental to apply techniques. Portal Vision is a device EPID has the capacity to operate either in image mode or dosimetry mode, with the allowance of Portal Dosimetry. To evaluated planning in IMRT, the device is irradiated using planning e, therefore, the fluency measured is compared with calculated fluency, through gamma analysis. The aim of this work was to perform tests of commissioning of this device. (author)
Usefulness and problems of film dosimetry in high energy radiotherapy
International Nuclear Information System (INIS)
Hirabayashi, Hisae
1995-01-01
Film dosimetry is a convenient and quick method of obtaining a set of high energy radiation isodose curves in the plane of the film, but it is an empirical method which presents some problems. Many authors have reported on film dosimetry for industrial films. Recently, the development of computerized densitometer systems, ready-pack films for radiotherapy and automatic film processors has helped improve the procedure. This paper reports our experiences regarding film dosimetry using the new materials, its usefulness in radiotherapy and some of technical problems encountered. The optical density value corresponding to a given dose depends upon the processing conditions, for XV-2 film, variation is about 4% when an automatic processor is used under controlled conditions. The Off-axis-ratios and the PDD in the perpendicular film plane agree well with the ion-chamber for photon and electron beams; by contrast, the PDD in the parallel film plane is significantly affected by variations in the phantom thickness, the type of film package and misalignment in phantom. But, bare films inserted into a cassette made of phantom material agree well for electron beams. Film dosimetry is effective and accurate at the edges of the field and for small fields, due to its high spatial resolution and rapid method. In addition, it is useful for electron beams OCR beam data input; for evaluating the input parameters for treatment planning systems; for quality assurance of the treatment equipment; and for preliminary clinical studies. Even when modern materials are used for film dosimetry, some technical problems will arise. Thus, to ensure the accuracy, certain precautions are required when setting conditions of film exposure and for quality control of the film processor. (author)
DEFF Research Database (Denmark)
Beierholm, Anders Ravnsborg; Ottosson, Rickard; Lindvold, Lars René
2011-01-01
A fast-readout dosimetry system based on fibre-coupled organic scintillators has been developed for the purpose of conducting point measurements of absorbed dose in radiotherapy beams involving high spatial and temporal dose gradients. The system measures the dose for each linac radiation pulse w...... and quality assurance of complex radiotherapy treatments.......A fast-readout dosimetry system based on fibre-coupled organic scintillators has been developed for the purpose of conducting point measurements of absorbed dose in radiotherapy beams involving high spatial and temporal dose gradients. The system measures the dose for each linac radiation pulse....... No significant differences between measurements and simulations were observed. The temporal resolution of the system was demonstrated by measuring dose per pulse, beam start-up transients and the quality factor for 6 MV. The precision of dose per pulse measurements was within 2.7% (1 SD) for a 10 cm × 10 cm...
Directory of Open Access Journals (Sweden)
fatemeh sari
2017-12-01
Full Text Available Introduction: Siliconeprosthetic implants are commonlyutilizedfor tissue replacement and breast augmentation after mastectomy. On the other hand, some patients require adjuvant radiotherapy in order to preventlocal-regional recurrence and increment ofthe overall survival. In case of recurrence, the radiation oncologist might have to irradiate the prosthesis.The aim of this study was to evaluate the effect of silicone prosthesis on photon dose distribution in breast radiotherapy. Materials and Methods: The experimental dosimetry was performed using theprosthetic breast phantom and the female-equivalent mathematical chest phantom. A Computerized Tomographybased treatment planning was performedusing a phantom and by CorePlan Treatment Planning System (TPS. For measuring the absorbed dose, thermoluminescent dosimeter(TLD chips (GR-207A were used. Multiple irradiations were completed for all the TLD positions, and the dose absorbed by the TLDs was read by a lighttelemetry (LTM reader. Results: Statistical comparisons were performed between the absorbed dosesassessed by the TLDs and the TPS calculations forthe same sites. Our initial resultsdemonstratedanacceptable agreement (P=0.064 between the treatment planning data and the measurements. The mean difference between the TPS and TLD resultswas 1.99%.The obtained findings showed that radiotherapy is compatible withsilicone gel prosthesis. Conclusion: It could be concludedthat the siliconbreast prosthesis has no clinicallysignificant effectondistribution of a 6 MV photon beam for reconstructed breasts.
The role of SSDL-Helsinki for dosimetry and quality audit in radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Aaltonen, P [Finnish Centre for Radiation and Nuclear Safety (STUK), Helsinki (Finland)
1996-08-01
Quality and dosimetry audit in radiotherapy has in Finland been implemented through inspections carried out by the Finnish Centre for Radiation and Nuclear Safety (STUK). In connection with the Radiation Metrology Laboratory of the Centre, the SSDL-Helsinki, there is a section for radiotherapy supervision. The inspection by STUK is an independent review of the quality and dosimetry control system which can be called quality and dosimetry audit by site visits. STUK is the responsible authority for the supervision of all use of radiation in Finland and that is why it also can set up requirements on the basis of results of the review. The disagreement of the measuring results between STUK and the radiotherapy department, of more than a given action level, will always lead to a thorough investigation of the reason and to a discussion of the most reliable results to be used for the treatments. The inspections include dose calibration for conventional X-ray therapy equipment and dose comparison, including field size dependence, for high energy equipment. For afterloading equipment the reference air kerma rate is checked. Additionally, the inspections by STUK include checks of the performance characteristics of the equipment and the accomplishment and the results of quality control procedures. Further, methods are currently being developed to supplement the direct measurements by TL-measurements in special phantoms in order to include the whole treatment chain (e.g. the treatment planning system) in the audit. (author). 7 refs, 1 tab.
Radiation dosimetry in radiotherapy with internal emitters
International Nuclear Information System (INIS)
Stabin, Michael G.
1997-01-01
Full text. Radiation dosimetry radionuclides are currently being labeled to various biological agents used in internal emitter radiotherapy. This talk will review the various technologies and types of radiolabel in current use, with focus on the characterization of the radiation dose to the various important tissues of the body. Methods for obtaining data, developing kinetic models, and calculating radiation doses will be reviewed. Monoclonal antibodies are currently being labeled with both alpha and beta emitting radionuclides in attempts to find effective agents against cancer. Several radionuclides are also being used as bone pain palliation agents. These agents must be studied in clinical trials to determine the biokinetics and radiation dosimetry prior to approval for general use. In such studies, it is important to ensure the collection of the appropriate kinds of data and to collect the data at appropriate time intervals. The uptake and retention of activity in all significant source organs and in excreta be measured periodically (with at least 2 data points phase of uptake or clearance). Then, correct dosimetry methods must be applied - the best available methods for characterizing the radionuclide kinetic and for estimating the dosimetry in the various organs of the body especially the marrow, should be used. Attempts are also under way to develop methods for estimating true patient-specific dosimetry. Cellular and animal studies are also. Valuable in evaluating the efficacy of the agents in shrinking or eliminating tumors; some results from such studies will also be discussed. The estimation of radiation doses to patients in therapy with internal emitters involves several complex phases of analysis. Careful attention to detail and the use of the best available methods are essential to the protection of the patient and a successful outcome
EPR dosimetry of radiotherapy photon beams in inhomogeneous media using alanine films
Energy Technology Data Exchange (ETDEWEB)
Oesteraas, Bjoern Helge [Department of Radiation Biology, Institute for Cancer Research, Norwegian Radium Hospital, Montebello, N-0310 Oslo (Norway); Hole, Eli Olaug [Department of Physics, University of Oslo, PO Box 1048 Blindern, N-0316 Oslo (Norway); Olsen, Dag Rune [Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo (Norway); Malinen, Eirik [Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Montebello, N-0310 Oslo (Norway)
2006-12-21
In the current work, EPR (electron paramagnetic resonance) dosimetry using alanine films (134 {mu}m thick) was utilized for dose measurements in inhomogeneous phantoms irradiated with radiotherapy photon beams. The main phantom material was PMMA, while either Styrofoam or aluminium was introduced as an inhomogeneity. The phantoms were irradiated to a maximum dose of about 30 Gy with 6 or 15 MV photons. The performance of the alanine film dosimeters was investigated and compared to results from ion chamber dosimetry, Monte Carlo simulations and radiotherapy treatment planning calculations. It was found that the alanine film dosimeters had a linear dose response above approximately 5 Gy, while a background signal obscured the response at lower dose levels. For doses between 5 and 60 Gy, the standard deviation of single alanine film dose estimates was about 2%. The alanine film dose estimates yielded results comparable to those from the Monte Carlo simulations and the ion chamber measurements, with absolute differences between estimates in the order of 1-15%. The treatment planning calculations exhibited limited applicability. The current work shows that alanine film dosimetry is a method suitable for estimating radiotherapeutical doses and for dose measurements in inhomogeneous media.
EPR dosimetry of radiotherapy photon beams in inhomogeneous media using alanine films
International Nuclear Information System (INIS)
Oesteraas, Bjoern Helge; Hole, Eli Olaug; Olsen, Dag Rune; Malinen, Eirik
2006-01-01
In the current work, EPR (electron paramagnetic resonance) dosimetry using alanine films (134 μm thick) was utilized for dose measurements in inhomogeneous phantoms irradiated with radiotherapy photon beams. The main phantom material was PMMA, while either Styrofoam or aluminium was introduced as an inhomogeneity. The phantoms were irradiated to a maximum dose of about 30 Gy with 6 or 15 MV photons. The performance of the alanine film dosimeters was investigated and compared to results from ion chamber dosimetry, Monte Carlo simulations and radiotherapy treatment planning calculations. It was found that the alanine film dosimeters had a linear dose response above approximately 5 Gy, while a background signal obscured the response at lower dose levels. For doses between 5 and 60 Gy, the standard deviation of single alanine film dose estimates was about 2%. The alanine film dose estimates yielded results comparable to those from the Monte Carlo simulations and the ion chamber measurements, with absolute differences between estimates in the order of 1-15%. The treatment planning calculations exhibited limited applicability. The current work shows that alanine film dosimetry is a method suitable for estimating radiotherapeutical doses and for dose measurements in inhomogeneous media
Clinical experience with routine diode dosimetry for electron beam radiotherapy
International Nuclear Information System (INIS)
Yaparpalvi, Ravindra; Fontenla, Doracy P.; Vikram, Bhadrasain
2000-01-01
Purpose: Electron beam radiotherapy is frequently administered based on clinical setups without formal treatment planning. We felt, therefore, that it was important to monitor electron beam treatments by in vivo dosimetry to prevent errors in treatment delivery. In this study, we present our clinical experience with patient dose verification using electron diodes and quantitatively assess the dose perturbations caused by the diodes during electron beam radiotherapy. Methods and Materials: A commercial diode dosimeter was used for the in vivo dose measurements. During patient dosimetry, the patients were set up as usual by the therapists. Before treatment, a diode was placed on the patient's skin surface and secured with hypoallergenic tape. The patient was then treated and the diode response registered and stored in the patient radiotherapy system database via our in-house software. A customized patient in vivo dosimetry report showing patient details, expected and measured dose, and percent difference was then generated and printed for analysis and record keeping. We studied the perturbation of electron beams by diodes using film dosimetry. Beam profiles at the 90% prescription isodose depths were obtained with and without the diode on the beam central axis, for 6-20 MeV electron beams and applicator/insert sizes ranging from a 3-cm diameter circular field to a 25 x 25 cm open field. Results: In vivo dose measurements on 360 patients resulted in the following ranges of deviations from the expected dose at the various anatomic sites: Breast (222 patients) -20.3 to +23.5% (median deviation 0%); Head and Neck (63 patients) -21.5 to +14.8% (median -0.7%); Other sites (75 patients) -17.6 to +18.8% (median +0.5%). Routine diode dosimetry during the first treatment on 360 patients (460 treatment sites) resulted in 11.5% of the measurements outside our acceptable ±6% dose deviation window. Only 3.7% of the total measurements were outside ±10% dose deviation. Detailed
Palmer, Antony L.; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H.
2015-11-01
There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.
International Nuclear Information System (INIS)
Palmer, Antony L; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H
2015-01-01
There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200–2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison. (paper)
SU-E-T-66: A Prototype for Couch Based Real-Time Dosimetry in External Beam Radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Ramachandran, P [Peter MacCallum Cancer Centre, Bendigo (Australia)
2015-06-15
Purpose: The main purpose of this study is to design a prototype for couch-based based real time dosimetry system in external beam radiotherapy Methods: A prototype of 100 ionization chambers was designed on a printed circuit board by etching the copper layer and each ionization chamber was wired to a 50 pin connector. The signals from the two 50 pin connectors collected from the ionization chambers were then transferred to a PXI module from National Instruments. The PXI module houses a current amplifier that amplifies the charge collected from the ionization chamber. The amplified signal is then sent to a digital multimeter module for converting the analog signal to digital signal. A software was designed in labview to read and display the signals obtained from the PXI module. A couch attachment frame was designed to house the 100 ionization chamber module. The frame was fixed underneath the treatment couch for measuring the dose during treatment. Resutls: The ionization chamber based prototype dosimetry was tested for simple radiotherapy treatment fields and found to be a useful device for measuring real time dosimetry at the treatment couch plane. This information could be used to assess the delivered dose to a patient during radiotherapy. It could be used as an invivo dosimeter during radiotherapy. Conclusion: In this study, a prototype for couch based real time dosimetry system was designed and tested. The prototype forms a basis for the development of large scale couch based real time dosimetry system that could be used to perform morning QA prior to treatment, assess real time doses delivered to patient and as a device to monitor the output of the treatment beam. Peter MacCallum Cancer Foundation.
SU-E-T-66: A Prototype for Couch Based Real-Time Dosimetry in External Beam Radiotherapy
International Nuclear Information System (INIS)
Ramachandran, P
2015-01-01
Purpose: The main purpose of this study is to design a prototype for couch-based based real time dosimetry system in external beam radiotherapy Methods: A prototype of 100 ionization chambers was designed on a printed circuit board by etching the copper layer and each ionization chamber was wired to a 50 pin connector. The signals from the two 50 pin connectors collected from the ionization chambers were then transferred to a PXI module from National Instruments. The PXI module houses a current amplifier that amplifies the charge collected from the ionization chamber. The amplified signal is then sent to a digital multimeter module for converting the analog signal to digital signal. A software was designed in labview to read and display the signals obtained from the PXI module. A couch attachment frame was designed to house the 100 ionization chamber module. The frame was fixed underneath the treatment couch for measuring the dose during treatment. Resutls: The ionization chamber based prototype dosimetry was tested for simple radiotherapy treatment fields and found to be a useful device for measuring real time dosimetry at the treatment couch plane. This information could be used to assess the delivered dose to a patient during radiotherapy. It could be used as an invivo dosimeter during radiotherapy. Conclusion: In this study, a prototype for couch based real time dosimetry system was designed and tested. The prototype forms a basis for the development of large scale couch based real time dosimetry system that could be used to perform morning QA prior to treatment, assess real time doses delivered to patient and as a device to monitor the output of the treatment beam. Peter MacCallum Cancer Foundation
Diode In-vivo Dosimetry for External Beam Radiotherapy: Patient Data Analysis
International Nuclear Information System (INIS)
Mrcela, I.; Bokulic, T.; Budanec, M; Froebe, A.; Soldic, Z.; Kusic, Z.
2008-01-01
In-vivo dosimetry is known as simple and reliable method for checking the final accuracy of the dose delivered in external radiotherapy making a supplement to the regular quality control. Entrance dose measurements in the beginning of the treatment assure detection of major errors that can affect the therapy outcome. Silicon diodes are often the detectors of choice for their ability of real time dose measurements and the simplicity of use. There are many publications describing the procedures for the implementation of in-vivo dosimetry. Routine in-vivo dosimetry has been introduced in our department after initial procedures including physical characterization, calibration and determination of correction factors for the detectors in use. This work presents patient data analysis with more than 700 field measurements taken in last 2 years period
Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit
International Nuclear Information System (INIS)
Rutonjski, Laza; Petrović, Borislava; Baucal, Milutin; Teodorović, Milan; Čudić, Ozren; Gershkevitsh, Eduard; Izewska, Joanna
2012-01-01
Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable
Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit
Directory of Open Access Journals (Sweden)
Rutonjski Laza
2012-09-01
Full Text Available Abstract Background Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. Methods The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs. The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. Results The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. Conclusions The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable.
Dosimetric verification of radiotherapy treatment planning systems in Serbia: national audit.
Rutonjski, Laza; Petrović, Borislava; Baucal, Milutin; Teodorović, Milan; Cudić, Ozren; Gershkevitsh, Eduard; Izewska, Joanna
2012-09-12
Independent external audits play an important role in quality assurance programme in radiation oncology. The audit supported by the IAEA in Serbia was designed to review the whole chain of activities in 3D conformal radiotherapy (3D-CRT) workflow, from patient data acquisition to treatment planning and dose delivery. The audit was based on the IAEA recommendations and focused on dosimetry part of the treatment planning and delivery processes. The audit was conducted in three radiotherapy departments of Serbia. An anthropomorphic phantom was scanned with a computed tomography unit (CT) and treatment plans for eight different test cases involving various beam configurations suggested by the IAEA were prepared on local treatment planning systems (TPSs). The phantom was irradiated following the treatment plans for these test cases and doses in specific points were measured with an ionization chamber. The differences between the measured and calculated doses were reported. The measurements were conducted for different photon beam energies and TPS calculation algorithms. The deviation between the measured and calculated values for all test cases made with advanced algorithms were within the agreement criteria, while the larger deviations were observed for simpler algorithms. The number of measurements with results outside the agreement criteria increased with the increase of the beam energy and decreased with TPS calculation algorithm sophistication. Also, a few errors in the basic dosimetry data in TPS were detected and corrected. The audit helped the users to better understand the operational features and limitations of their TPSs and resulted in increased confidence in dose calculation accuracy using TPSs. The audit results indicated the shortcomings of simpler algorithms for the test cases performed and, therefore the transition to more advanced algorithms is highly desirable.
[Automatic Extraction and Analysis of Dosimetry Data in Radiotherapy Plans].
Song, Wei; Zhao, Di; Lu, Hong; Zhang, Biyun; Ma, Jun; Yu, Dahai
To improve the efficiency and accuracy of extraction and analysis of dosimetry data in radiotherapy plans for a batch of patients. With the interface function provided in Matlab platform, a program was written to extract the dosimetry data exported from treatment planning system in DICOM RT format and exported the dose-volume data to an Excel file with the SPSS compatible format. This method was compared with manual operation for 14 gastric carcinoma patients to validate the efficiency and accuracy. The output Excel data were compatible with SPSS in format, the dosimetry data error for PTV dose interval of 90%-98%, PTV dose interval of 99%-106% and all OARs were -3.48E-5 ± 3.01E-5, -1.11E-3 ± 7.68E-4, -7.85E-5 ± 9.91E-5 respectively. Compared with manual operation, the time required was reduced from 5.3 h to 0.19 h and input error was reduced from 0.002 to 0. The automatic extraction of dosimetry data in DICOM RT format for batch patients, the SPSS compatible data exportation, quick analysis were achieved in this paper. The efficiency of clinical researches based on dosimetry data analysis of large number of patients will be improved with this methods.
Assessment of leakage dose in vivo in patients undergoing radiotherapy for breast cancer
Directory of Open Access Journals (Sweden)
Peta Lonski
2018-01-01
Full Text Available Background and purpose: Accurate quantification of the relatively small radiation doses delivered to untargeted regions during breast irradiation in patients with breast cancer is of increasing clinical interest for the purpose of estimating long-term radiation-related risks. Out-of-field dose calculations from commercial planning systems however may be inaccurate which can impact estimates for long-term risks associated with treatment. This work compares calculated and measured dose out-of-field and explores the application of a correction for leakage radiation. Materials and methods: Dose calculations of a Boltzmann transport equation solver, pencil beam-type, and superposition-type algorithms from a commercial treatment planning system (TPS were compared with in vivo thermoluminescent dosimetry (TLD measurements conducted out-of-field on the contralateral chest at points corresponding to the thyroid, axilla and contralateral breast of eleven patients undergoing tangential beam radiotherapy for breast cancer. Results: Overall, the TPS was found to under-estimate doses at points distal to the radiation field edge with a modern linear Boltzmann transport equation solver providing the best estimates. Application of an additive correction for leakage (0.04% of central axis dose improved correlation between the measured and calculated doses at points greater than 15 cm from the field edge. Conclusions: Application of a correction for leakage doses within peripheral regions is feasible and could improve accuracy of TPS in estimating out-of-field doses in breast radiotherapy. Keywords: Breast radiotherapy, TLD, Leakage dose, Dose calculation algorithm
International Nuclear Information System (INIS)
Andreo, P.
2001-01-01
An International Code of Practice (CoP, or dosimetry protocol) for external beam radiotherapy dosimetry based on standards of absorbed dose to water has been published by the IAEA on behalf of IAEA, WHO, PAHO and ESTRO. The CoP provides a systematic and internationally unified approach for the determination of the absorbed dose to water in reference conditions with radiotherapy beams. The development of absorbed-dose-to-water standards for high-energy photons and electrons offers the possibility of reducing the uncertainty in the dosimetry of radiotherapy beams. Many laboratories already provide calibrations at the radiation quality of 60Co gamma-rays and some have extended calibrations to high-energy photon and electron beams. The dosimetry of kilovoltage x-rays, as well as that of proton and ion beams can also be based on these standards. Thus, a coherent dosimetry system based on the same formalism is achieved for practically all radiotherapy beams. The practical use of the CoP as simple. The document is formed by a set of different CoPs for each radiation type, which include detailed procedures and worksheets. All CoPs are based on ND,w chamber calibrations at a reference beam quality Qo, together with radiation beam quality correction factors kQ preferably measured directly for the user's chamber in a standards laboratory. Calculated values of kQ are provided together with their uncertainty estimates. Beam quality specifiers are 60Co, TPR20,10 (high-energy photons), R50 (electrons), HVL and kV (x-rays) and Rres (protons and ions) [es
International Nuclear Information System (INIS)
Baek, Tae Seong; Chung, Eun Ji; Son, Jaeman; Yoon, Myonggeun
2014-01-01
The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam delivery based on detection of large errors in treatment room. Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from four lung cancer patients and used in the irradiation of an anthropomorphic phantom. The proposed method was evaluated by comparing the calculated dose map from TPS and EPID measurement on the same plane using a gamma index method with a 3% dose and 3 mm distance-to-dose agreement tolerance limit. In a simulation using a homogeneous plastic water phantom, performed to verify the effectiveness of the proposed method, the average passing rate of the transit dose based on gamma index was high enough, averaging 94.2% when there was no error during beam delivery. The passing rate of the transit dose for 24 IMRT fields was lower with the anthropomorphic phantom, averaging 86.8% ± 3.8%, a reduction partially due to the inaccuracy of TPS calculations for inhomogeneity. Compared with the TPS, the absolute value of the transit dose at the beam center differed by −0.38% ± 2.1%. The simulation study indicated that the passing rate of the gamma index was significantly reduced, to less than 40%, when a wrong field was erroneously irradiated to patient in the treatment room. This feasibility study suggested that transit dosimetry based on the calculation with commercial TPS and EPID measurement with simple calibration can provide information about large errors for treatment beam delivery
Commissioning of Portal Dosimetry and characterization of an EPID
International Nuclear Information System (INIS)
Olbi, D.S.; Sales, C.P.; Nakandakari, M.V.N.
2016-01-01
The development of technologies compensator blocks, MLC, high dose rate accelerators, treatment planning systems, among others, permitted that new treatment techniques in radiotherapy were created. Such techniques have the capacity to modulate radiation beam fluency (IMRT, VMAT), or to deliver high doses in few fractions or unique fractions (SRS). Following the same tendency, quality control of planning became more complex. It is necessary to evaluate the fluency delivered by the accelerator. Its levels of does and its spatial distribution should co-occur with the fluency calculated by TPS. Acquisition of new detector devices in quality control of treatments is fundamental to apply techniques. Portal Vision is a device EPID has the capacity to operate either in image mode or dosimetry mode, with the allowance of Portal Dosimetry. To evaluated planning in IMRT, the device is irradiated using planning e, therefore, the fluency measured is compared with calculated fluency, through gamma analysis. The aim of this work was to perform tests of commissioning of this device. (author)
SFPM opinion on the so-called 'transit' in vivo dosimetry in external radiotherapy
International Nuclear Information System (INIS)
Berger, Lucie; Dupuis, Pauline; Marchesi, Vincent; Boutry, Christine; Francois, Pascal; Crespin, Sylvain
2014-01-01
Written to the demand of the ASN to the SFPM (the French professional body in medical physics), this report states the opinion of these professionals regarding the use of the so-called 'transit' dosimetry for the control of the in vivo dose received during radiotherapy. After an overview of the use of in vivo dosimetry in medical practices, the authors outline the main benefits and drawbacks of point conventional detectors used for this dosimetry. They propose an overview of the state-of-the-art in transit in vivo dosimetry by briefly describing the different developed methodologies: the prediction-based methodology and the rear projection methodology. They also propose a literature review on transit in vivo dosimetry. Based on expert experience and on this review they give lists of technical benefits and drawbacks of techniques of in vivo dosimetry by EPID transit imagery. They finally indicate some commercially available technical solutions to transit in vivo dosimetry
Dosimetry using radiosensitive gels in radiotherapy: significance and methods
International Nuclear Information System (INIS)
Gibon, D.; Bourel, P.; Castelain, B.; Marchandise, X.; Rousseau, J.
2001-01-01
The goal of conformal radiotherapy is to concentrate the dose in a well-defined volume by avoiding the neighbouring healthy structures. This technique requires powerful treatment planning software and a rigorous control of estimated dosimetry. The usual dosimetric tools are not adapted to visualize and validate complex 3D treatment. Dosimetry by radiosensitive gel permits visualization and measurement of the three-dimensional dose distribution. The objective of this work is to report on current work in this field and, based on our results and our experience, to draw prospects for an optimal use of this technique. Further developments will relate to the realization of new radiosensitive gels satisfying, as well as possible, cost requirements, easy realization and use, magnetic resonance imagery (MRI) sensitivity, tissue equivalence, and stability. Other developments focus on scanning methods, especially in MRI to measure T1 and T2. (author)
Clark, Catharine H; Aird, Edwin G A; Bolton, Steve; Miles, Elizabeth A; Nisbet, Andrew; Snaith, Julia A D; Thomas, Russell A S; Venables, Karen; Thwaites, David I
2015-01-01
Dosimetry audit plays an important role in the development and safety of radiotherapy. National and large scale audits are able to set, maintain and improve standards, as well as having the potential to identify issues which may cause harm to patients. They can support implementation of complex techniques and can facilitate awareness and understanding of any issues which may exist by benchmarking centres with similar equipment. This review examines the development of dosimetry audit in the UK over the past 30 years, including the involvement of the UK in international audits. A summary of audit results is given, with an overview of methodologies employed and lessons learnt. Recent and forthcoming more complex audits are considered, with a focus on future needs including the arrival of proton therapy in the UK and other advanced techniques such as four-dimensional radiotherapy delivery and verification, stereotactic radiotherapy and MR linear accelerators. The work of the main quality assurance and auditing bodies is discussed, including how they are working together to streamline audit and to ensure that all radiotherapy centres are involved. Undertaking regular external audit motivates centres to modernize and develop techniques and provides assurance, not only that radiotherapy is planned and delivered accurately but also that the patient dose delivered is as prescribed.
Aird, Edwin GA; Bolton, Steve; Miles, Elizabeth A; Nisbet, Andrew; Snaith, Julia AD; Thomas, Russell AS; Venables, Karen; Thwaites, David I
2015-01-01
Dosimetry audit plays an important role in the development and safety of radiotherapy. National and large scale audits are able to set, maintain and improve standards, as well as having the potential to identify issues which may cause harm to patients. They can support implementation of complex techniques and can facilitate awareness and understanding of any issues which may exist by benchmarking centres with similar equipment. This review examines the development of dosimetry audit in the UK over the past 30 years, including the involvement of the UK in international audits. A summary of audit results is given, with an overview of methodologies employed and lessons learnt. Recent and forthcoming more complex audits are considered, with a focus on future needs including the arrival of proton therapy in the UK and other advanced techniques such as four-dimensional radiotherapy delivery and verification, stereotactic radiotherapy and MR linear accelerators. The work of the main quality assurance and auditing bodies is discussed, including how they are working together to streamline audit and to ensure that all radiotherapy centres are involved. Undertaking regular external audit motivates centres to modernize and develop techniques and provides assurance, not only that radiotherapy is planned and delivered accurately but also that the patient dose delivered is as prescribed. PMID:26329469
Directory of Open Access Journals (Sweden)
Caroline Stokke
2017-11-01
Full Text Available Abstract Background The European directive on basic safety standards (Council directive 2013/59 Euratom mandates dosimetry-based treatment planning for radiopharmaceutical therapies. The directive comes into operation February 2018, and the aim of a report produced by the Internal Dosimetry Task Force of the European Association of Nuclear Medicine is to address this aspect of the directive. A summary of the report is presented. Results A brief review of five of the most common therapy procedures is included in the current text, focused on the potential to perform patient-specific dosimetry. In the full report, 11 different therapeutic procedures are included, allowing additional considerations of effectiveness, references to specific literature on quantitative imaging and dosimetry, and existing evidence for absorbed dose-effect correlations for each treatment. Individualized treatment planning with tracer diagnostics and verification of the absorbed doses delivered following therapy is found to be scientifically feasible for almost all procedures investigated, using quantitative imaging and/or external monitoring. Translation of this directive into clinical practice will have significant implications for resource requirements. Conclusions Molecular radiotherapy is undergoing a significant expansion, and the groundwork for dosimetry-based treatment planning is already in place. The mandated individualization is likely to improve the effectiveness of the treatments, although must be adequately resourced.
DEFF Research Database (Denmark)
Christensen, Anders Nymark; Rydhög, J. S.; Søndergaard, Rikke Vicki
2016-01-01
Development of safe and efficient radiotherapy routines requires quantification of the delivered absorbed dose to the cancer tissue in individual patients. In vivo dosimetry can provide accurate information about the absorbed dose delivered during treatment. In the current study, a novel silver......-nanosensor formulation based on poly(vinylpyrrolidinone)-coated silver nanoparticles formulated in a gelation matrix composed of sucrose acetate isobutyrate has been developed for use as an in vivo dosimeter for external beam radiotherapy. In situ photonuclear reactions trigger the formation of radioactive (106)Ag......, which enables post treatment verification of the delivered dose using positron emission tomography imaging. The silver-nanosensor was investigated in a tissue equivalent thorax phantom using clinical settings and workflow for both standard fractionated radiotherapy (2 Gy) and stereotactic radiotherapy...
International Nuclear Information System (INIS)
Yahya, Noorazrul; Ebert, Martin A.; Bulsara, Max; Haworth, Annette; Kennedy, Angel; Joseph, David J.; Denham, Jim W.
2015-01-01
Purpose/objective: To identify dosimetry, clinical factors and medication intake impacting urinary symptoms after prostate radiotherapy. Material and methods: Data describing clinical factors and bladder dosimetry (reduced with principal component (PC) analysis) for 754 patients treated with external beam radiotherapy accrued by TROG 03.04 RADAR prostate radiotherapy trial were available for analysis. Urinary symptoms (frequency, incontinence, dysuria and haematuria) were prospectively assessed using LENT-SOMA to a median of 72 months. The endpoints assessed were prevalence (grade ⩾1) at the end of radiotherapy (representing acute symptoms), at 18-, 36- and 54-month follow-ups (representing late symptoms) and peak late incidence including only grade ⩾2. Impact of factors was assessed using multivariate logistic regression models with correction for over-optimism. Results: Baseline symptoms, non-insulin dependent diabetes mellitus, age and PC1 (correlated to the mean dose) impact symptoms at >1 timepoints. Associations at a single timepoint were found for cerebrovascular condition, ECOG status and non-steroidal anti-inflammatory drug intake. Peak incidence analysis shows the impact of baseline, bowel and cerebrovascular condition and smoking status. Conclusions: The prevalence and incidence analysis provide a complementary view for urinary symptom prediction. Sustained impacts across time points were found for several factors while some associations were not repeated at different time points suggesting poorer or transient impact
International Nuclear Information System (INIS)
McEwen, M.R.; Duane, S.; Thomas, R.A.S.; Rosser, K.E.
2001-01-01
There are approximately 60 radiotherapy centres in the UK. In 1999, these centres carried out over 102,000 treatments in 1.2 million fractions. These centres are organised by IPEM into eight geographical regions for the purpose of inter-departmental audits, which have been carried out on a regular basis to check the uniformity of dosimetry, treatment planning, record keeping, etc. Thwaites et al (1992) carried out a dosimetric intercomparison of megavoltage photon beams in all UK radiotherapy centres obtaining a mean value for the ratio audit/local dose of 1.003 with a standard deviation of 1.5%. The present programme covers dosimetry of megavoltage photons and electrons and low and medium energy (10-300 kV) photons. Megavoltage photon audits have the longest history, while electron audits began in 2000 and kV audits are only at the pilot stage
Advantages and disadvantages of luminescence dosimetry
Energy Technology Data Exchange (ETDEWEB)
Olko, Pawel, E-mail: Pawel.Olko@ifj.edu.p [Institute of Nuclear Physics Polish Academy of Science (IFJ PAN), Krakow (Poland)
2010-03-15
Owing to their excellent dosimetric properties, luminescence detectors of ionizing radiation are now extensively applied in individual dosimetry services. The most frequently used personal dosemeters are based on Optically Stimulated Luminescence (OSL), radiophotoluminescence (RPL) or thermoluminescence (TL). Luminescence detectors have also found several applications in clinical dosimetry, especially around new radiation modalities in radiotherapy, such as Intensity Modulated Radiotherapy (IMRT) or ion beam radiotherapy. Requirements of luminescence detectors applied in individual and clinical dosimetry and some recent developments in luminescence of detectors and techniques leading to significant improvements of the functionality and accuracy of dosimetry systems are reviewed and discussed.
Modeling of a planning system in radiotherapy and Nuclear Medicine using the MCNP6 code
International Nuclear Information System (INIS)
Massicano, Felipe
2015-01-01
Cancer therapy has many branches and one of them is the use of radiation sources as treatment leading method. Radiotherapy and nuclear medicine are examples of these treatment types. For using the ionization radiation as main tool for the therapy, there is the need of crafting many treatment simulation in order to maximum the tumoral tissue dose without surpass the dose limit in health tissue surrounding. Treatment planning systems (TPS) are systems which have the purpose of simulating these therapy types. Nuclear medicine and radiotherapy have many distinct features linked to the therapy mode and consequently they have different TPS destined for each. The radiotherapy TPS is more developed than the nuclear medicine TPS and by that reason the development of a TPS that was similar to the radiotherapy TPS, but enough generic for include other therapy types, it will contribute with significant advances in nuclear medicine and in others therapy types with radiation. Based on this, the goal of work was to model a TPS that utilizes the Monte Carlo N-Particle Transport code (MCNP6) in order to simulate radiotherapy therapy, nuclear medicine therapy and with potential for simulating other therapy types too. The result of this work was the creation of a Framework in Java language, object oriented, named IBMC which will assist in the development of new TPS with MCNP6 code. The IBMC allowed to develop rapidly and easily TPS for radiotherapy and nuclear medicine and the results were validated with systems already consolidated. The IBMC showed high potential for developing TPS by new therapy types. (author)
Clark, Catharine H; Aird, Edwin GA; Bolton, Steve; Miles, Elizabeth A; Nisbet, Andrew; Snaith, Julia AD; Thomas, Russell AS; Venables, Karen; Thwaites, David I
2015-01-01
Dosimetry audit plays an important role in the development and safety of radiotherapy. National and large scale audits are able to set, maintain and improve standards, as well as having the potential to identify issues which may cause harm to patients. They can support implementation of complex techniques and can facilitate awareness and understanding of any issues which may exist by benchmarking centres with similar equipment. This review examines the development of dosimetry audit in the UK...
Dosimetry in radiotherapy with natural diamond detectors
International Nuclear Information System (INIS)
De Angelis, C.; Onori, S.; Pacilio, M.; Cirrone, G.A.P.; Cuttone, G.; Raffaele, L.; Bucciolini, M.; Mazzocchi, S.
2002-01-01
There is wide interest in the use of diamond detectors for dosimetry in radiotherapy mainly because of the small dimensions, radiation hardness, nearly tissue equivalence of sensitive material and capability to deliver the dosimetric response 'on line'. In order to assess the dosimetric properties of PTW Riga diamond detectors type 60003, experiments were performed in conventional (high energy photon and electron) therapy beams as well as in proton therapy beams. The main detector features investigated were reproducibility of response, dose-signal relationship, temperature dependence, dose-rate dependence, energy dependence and angular dependence. High energy photons (6-25 MV) and electrons (6-22 MeV), available at the Radiotherapy Department of the Florence University, were used for investigating the general properties. Two different PTW diamond detectors of the same type were used to evidence inter-sample differences. The beam quality dependence of the detector response is probably the most critical point and this statement is of particular relevance for proton dosimetry since the proton LET changes with depth in the medium. Mainly because of the little information available on detector sensitivity variations with beam energy, the use of diamonds for clinical proton dosimetry is not widespread. In two recent papers a sensitivity dependence on proton energy of a natural PTW diamond detector has been reported. Due to the necessity to characterise each diamond detector individually the PTW Riga natural diamond detector in operation at the LNS-INFN, Catania, Italy was tested with the local proton beam line. This experiment is of main concern because this proton beam, produced by a superconducting cyclotron and used for ocular melanoma treatment, is available only since 2001 (CATANA beam). The first patient has been treated in February 2002. Proton irradiations were performed with non modulated and modulated 62 MeV beams. Attention was focused on diamond sensitivity
Clinical dosimetry in photon radiotherapy. A Monte Carlo based investigation
International Nuclear Information System (INIS)
Wulff, Joerg
2010-01-01
Practical clinical dosimetry is a fundamental step within the radiation therapy process and aims at quantifying the absorbed radiation dose within a 1-2% uncertainty. To achieve this level of accuracy, corrections are needed for calibrated and air-filled ionization chambers, which are used for dose measurement. The procedures of correction are based on cavity theory of Spencer-Attix and are defined in current dosimetry protocols. Energy dependent corrections for deviations from calibration beams account for changed ionization chamber response in the treatment beam. The corrections applied are usually based on semi-analytical models or measurements and are generally hard to determine due to their magnitude of only a few percents or even less. Furthermore the corrections are defined for fixed geometrical reference-conditions and do not apply to non-reference conditions in modern radiotherapy applications. The stochastic Monte Carlo method for the simulation of radiation transport is becoming a valuable tool in the field of Medical Physics. As a suitable tool for calculation of these corrections with high accuracy the simulations enable the investigation of ionization chambers under various conditions. The aim of this work is the consistent investigation of ionization chamber dosimetry in photon radiation therapy with the use of Monte Carlo methods. Nowadays Monte Carlo systems exist, which enable the accurate calculation of ionization chamber response in principle. Still, their bare use for studies of this type is limited due to the long calculation times needed for a meaningful result with a small statistical uncertainty, inherent to every result of a Monte Carlo simulation. Besides heavy use of computer hardware, techniques methods of variance reduction to reduce the needed calculation time can be applied. Methods for increasing the efficiency in the results of simulation were developed and incorporated in a modern and established Monte Carlo simulation environment
Anderson, N; Lawford, C; Khoo, V; Rolfo, M; Joon, D L; Wada, M
2011-12-01
Intensity-modulated radiotherapy (IMRT) has reduced the impact of acute and late toxicities associated with head and neck radiotherapy. Treatment planning system (TPS) advances in biological cost function based optimization (BBO) and improved segmentation techniques have increased organ at risk (OAR) sparing compared to conventional dose-based optimization (DBO). A planning study was undertaken to compare OAR avoidance in DBO and BBO treatment planning. Simultaneous integrated boost treatment plans were produced for 10 head and neck patients using both planning systems. Plans were compared for tar get coverage and OAR avoidance. Comparisons were made using the BBO TPS Monte Carlo dose engine to eliminate differences due to inherent algorithms. Target coverage (V95%) was maintained for both solutions. BBO produced lower OAR doses, with statistically significant improvement to left (12.3%, p = 0.005) and right parotid mean dose (16.9%, p = 0.004), larynx V50_Gy (71.0%, p = 0.005), spinal cord (21.9%, p < 0.001) and brain stem dose maximums (31.5%, p = 0.002). This study observed improved OAR avoidance with BBO planning. Further investigations will be undertaken to review any clinical benefit of this improved planned dosimetry.
International Nuclear Information System (INIS)
Spasic, E.; Noel, A.; Buchheit, I.; Bernier, V.
2011-01-01
Purpose. - To compare several techniques in order to determine the best treatment for benign brain tumours. Methods and patients. - A retrospective study was performed for five patients who received 3D-conformal radiotherapy, intensity modulated radiotherapy or CyberKnife R . These patients had a meningioma, a pituitary tumour, a cranio-pharyngioma or a neurinoma. In each case, these treatment plans were optimised and compared with the three other dosimetries. Radiobiological or positioning parameters were evaluated, as well as dosimetric parameters, in order to compare treatments with different characteristics. Results. - The dosimetric parameters showed that the choice of treatment seemed to be determined mostly by tumour size, shape and proximity with organs at risk (not tumour localisation). Whereas the results showed no significant deviations with regards to the radiobiological parameters. Therefore, with these parameters, it was difficult to give priority to a treatment. Conclusions. - With regards to benign brain tumours of medium or large size, intensity modulated radiotherapy seemed the recommended treatment. It enabled to obtain a good ratio between efficacy and toxicity for tumours that are really close to organs at risk. Concerning small benign brain tumours, the CyberKnife R was probably the best treatment. (authors)
International Nuclear Information System (INIS)
Izewska, J.; Bera, P.; Vatnitsky, S.
2002-01-01
Since 1969 the International Atomic Energy Agency, together with the World Health Organization, has performed postal TLD audits to verify calibration of radiotherapy beams in developing countries. The TLD programme also monitors activities of Secondary Standard Dosimetry Laboratories (SSDLs). The programme has checked approximately 4000 clinical beams in over 1100 hospitals, and in many instances significant errors have been detected in the beam calibration. Subsequent follow-up actions help to resolve the discrepancies, thus preventing further mistreatment of patients. The audits for SSDLs check the implementation of the dosimetry protocol in order to assure proper dissemination of dosimetry standards to the end-users. The TLD audit results for SSDLs show good consistency in the basic dosimetry worldwide. New TLD procedures and equipment have recently been introduced by the IAEA that include a modified TLD calibration methodology and computerised tools for automation of dose calculation from TLD readings. (author)
Hadad, K.; Zohrevand, M.; Faghihi, R.; Sedighi Pashaki, A.
2015-01-01
Background HDR brachytherapy is one of the commonest methods of nasopharyngeal cancer treatment. In this method, depending on how advanced one tumor is, 2 to 6 Gy dose as intracavitary brachytherapy is prescribed. Due to high dose rate and tumor location, accuracy evaluation of treatment planning system (TPS) is particularly important. Common methods used in TPS dosimetry are based on computations in a homogeneous phantom. Heterogeneous phantoms, especially patient-specific voxel phantoms can increase dosimetric accuracy. Materials and Methods In this study, using CT images taken from a patient and ctcreate-which is a part of the DOSXYZnrc computational code, patient-specific phantom was made. Dose distribution was plotted by DOSXYZnrc and compared with TPS one. Also, by extracting the voxels absorbed dose in treatment volume, dose-volume histograms (DVH) was plotted and compared with Oncentra™ TPS DVHs. Results The results from calculations were compared with data from Oncentra™ treatment planning system and it was observed that TPS calculation predicts lower dose in areas near the source, and higher dose in areas far from the source relative to MC code. Absorbed dose values in the voxels also showed that TPS reports D90 value is 40% higher than the Monte Carlo method. Conclusion Today, most treatment planning systems use TG-43 protocol. This protocol may results in errors such as neglecting tissue heterogeneity, scattered radiation as well as applicator attenuation. Due to these errors, AAPM emphasized departing from TG-43 protocol and approaching new brachytherapy protocol TG-186 in which patient-specific phantom is used and heterogeneities are affected in dosimetry. PMID:25973408
Software tool for portal dosimetry research.
Vial, P; Hunt, P; Greer, P B; Oliver, L; Baldock, C
2008-09-01
This paper describes a software tool developed for research into the use of an electronic portal imaging device (EPID) to verify dose for intensity modulated radiation therapy (IMRT) beams. A portal dose image prediction (PDIP) model that predicts the EPID response to IMRT beams has been implemented into a commercially available treatment planning system (TPS). The software tool described in this work was developed to modify the TPS PDIP model by incorporating correction factors into the predicted EPID image to account for the difference in EPID response to open beam radiation and multileaf collimator (MLC) transmitted radiation. The processes performed by the software tool include; i) read the MLC file and the PDIP from the TPS, ii) calculate the fraction of beam-on time that each point in the IMRT beam is shielded by MLC leaves, iii) interpolate correction factors from look-up tables, iv) create a corrected PDIP image from the product of the original PDIP and the correction factors and write the corrected image to file, v) display, analyse, and export various image datasets. The software tool was developed using the Microsoft Visual Studio.NET framework with the C# compiler. The operation of the software tool was validated. This software provided useful tools for EPID dosimetry research, and it is being utilised and further developed in ongoing EPID dosimetry and IMRT dosimetry projects.
SU-E-J-89: Deformable Registration Method Using B-TPS in Radiotherapy.
Xie, Y
2012-06-01
A novel deformable registration method for four-dimensional computed tomography (4DCT) images is developed in radiation therapy. The proposed method combines the thin plate spline (TPS) and B-spline together to achieve high accuracy and high efficiency. The method consists of two steps. First, TPS is used as a global registration method to deform large unfit regions in the moving image to match counterpart in the reference image. Then B-spline is used for local registration, the previous deformed moving image is further deformed to match the reference image more accurately. Two clinical CT image sets, including one pair of lung and one pair of liver, are simulated using the proposed algorithm, which results in a tremendous improvement in both run-time and registration quality, compared with the conventional methods solely using either TPS or B-spline. The proposed method can combine the efficiency of TPS and the accuracy of B-spline, performing good adaptively and robust in registration of clinical 4DCT image. © 2012 American Association of Physicists in Medicine.
Verification of Treatment Planning System (TPS) on Beam Axis of Co-60 Teletherapy
International Nuclear Information System (INIS)
Nunung-Nuraeni; Budhy-Kurniawan; Purwanto; Sugiyantari; Heru-Prasetio; Nasukha
2001-01-01
Cancer diseases up to now can be able to be treated by using surgery, chemotherapy and radiotherapy. The need of high level precision and accuracy on radiation dose are very important task. One of task is verification of Treatment Planning System (Tps) to the treatment of patients. The research has been done to verify Tps on beam exis of teletherapy Co-60. Result found that the different between Tps and measurements are about -2.682 % to 1.918% for simple geometry and homogeneous material, 5.278 % to 4.990 % for complex geometry, and -3.202 % to -2.090 % for more complex geometry. (author)
Energy Technology Data Exchange (ETDEWEB)
Matsunaga, T; Adachi, Y [Department of Radiology, Seirei Hamamatsu General Hospital, Hamamatsu, Shizuoka (Japan); Hayashi, N [Graduate School of Health Sciences, Fujita Health University, Tayoake, Aichi (Japan); Nozue, M [Department of Radiation Oncology, Seirei Hamamtsu General Hospital, Hamamatsu, Shizuoka (Japan)
2016-06-15
Purpose: Japan Standard Dosimetry of Absorbed dose to water in external beam radiotherapy (JSDP12) is widely used to measure radiation dose in radiotherapy. However, JSDP12 does not take flattening-filter-free (FFF) beam into consideration. In addition, JSDP12 applied TPR20,10 for dose quality index for photon beam. The purpose of this study is to compare JSDP12 with AAPM TG-51 addendum in order to establish optimal dosimetry procedure for FFF beam. Method: We evaluated the ion-recombination factor (ks) and the correction factor of radial beam profile (Prp) in FFF beam dosimetry. The ks was introduced by 2 voltages method and verified by Jaffe’s plot. The Prp was given by both film measurement and calculation of treatment planning system, and compared them. Next, we compared the dose quality indexes (kQ) between TPR20,10 method and PDD(10)x method. Finally we considered optimal dosimetry protocol for FFF photon beam using JSDP12 with referring TG-51 addendum protocols. The FFF photon beams of 6 MV (6X-FFF) and 10 MV (10X-FFF) from TrueBeam were investigated in this study. Results: The ks for 6X-FFF and 10X-FFF beams were 1.005 and 1.010, respectively. The Prp of 0.6 cc ionization chamber for 6X-FFF and 10X-FFF beams (Film, TPS) were (1.004, 1.008) and (1.005, 1.008), respectively. The kQ for 6X-FFF and 10X-FFF beams (JSDP12, TG-51 addendum) were (0.9950, 0.9947) and (0.9851, 0.9845), respectively. The most effective factor for uncertainty in FFF photon beam measurement was Prp for JSDP12 formalism. Total dosimetric differences between JSDP12 and TG-51 addendum for 6X-FFF and 10X-FFF were -0.47% and -0.73%, respectively. Conclusion: The total dosimetric difference between JSDP12 and TG-51 addendum was within 1%. The introduction of kQ given by JSDP is feasible for FFF photon beam dosimetry. However, we think Prp should be considered for optimal dosimetry procedure even if JSDP12 is used for FFF photon beam dosimetry.
Development of a calibration protocol for quantitative imaging for molecular radiotherapy dosimetry
International Nuclear Information System (INIS)
Wevrett, J.; Fenwick, A.; Scuffham, J.; Nisbet, A.
2017-01-01
Within the field of molecular radiotherapy, there is a significant need for standardisation in dosimetry, in both quantitative imaging and dosimetry calculations. Currently, there are a wide range of techniques used by different clinical centres and as a result there is no means to compare patient doses between centres. To help address this need, a 3 year project was funded by the European Metrology Research Programme, and a number of clinical centres were involved in the project. One of the required outcomes of the project was to develop a calibration protocol for three dimensional quantitative imaging of volumes of interest. Two radionuclides were selected as being of particular interest: iodine-131 ( 131 I, used to treat thyroid disorders) and lutetium-177 ( 177 Lu, used to treat neuroendocrine tumours). A small volume of activity within a scatter medium (water), representing a lesion within a patient body, was chosen as the calibration method. To ensure ease of use in clinical centres, an “off-the-shelf” solution was proposed – to avoid the need for in-house manufacturing. The BIODEX elliptical Jaszczak phantom and 16 ml fillable sphere were selected. The protocol was developed for use on SPECT/CT gamma cameras only, where the CT dataset would be used to correct the imaging data for attenuation of the emitted photons within the phantom. The protocol corrects for scatter of emitted photons using the triple energy window correction technique utilised by most clinical systems. A number of clinical systems were tested in the development of this protocol, covering the major manufacturers of gamma camera generally used in Europe. Initial imaging was performed with 131 I and 177 Lu at a number of clinical centres, but due to time constraints in the project, some acquisitions were performed with 177 Lu only. The protocol is relatively simplistic, and does not account for the effects of dead-time in high activity patients, the presence of background activity
The implementation of in vivo dosimetry in a small radiotherapy department
International Nuclear Information System (INIS)
Voordeckers, M.; Goosens, H.; Rutten, J.
1998-01-01
In vivo dosimetry has been shown in a number of evaluation studies, generally carried out in larger academic centres, to be a reliable method of checking the overall treatment accuracy. The object of this study was to investigate whether it was possible and useful to perform in vivo dosimetry in a small radiotherapy department and to detect if there were any systematic errors in the overall treatment set-up. All patients were treated on a cobalt-60 unit equipped with a verification system. Six hundred fifty entrance dose measurements were performed with silicon diodes. The analysis showed a mean deviation of -1.3%. This negative deviation was mainly due to the mean deviation obtained in the treatment of head and neck (-1.6%) or breast (-2.5%) cancer patients. The results for pelvic or lung irradiation showed almost no deviation. Further investigation showed that the negative values for head and neck or breast irradiation were due to the irradiation technique, the lack of scattering material causes a reduction of the dose at the reference point, which is not taken into consideration by the treatment planning system. By performing in vivo dosimetry, we were also able to detect two large errors in 650 measurements and could prevent erroneous treatment. Even when the overall treatment set-up is very accurate, in vivo dosimetry is very useful in a small department since only a small effort can detect and prevent errors. (author)
Quantitative evaluation of patient-specific quality assurance using online dosimetry system
Jung, Jae-Yong; Shin, Young-Ju; Sohn, Seung-Chang; Min, Jung-Whan; Kim, Yon-Lae; Kim, Dong-Su; Choe, Bo-Young; Suh, Tae-Suk
2018-01-01
In this study, we investigated the clinical performance of an online dosimetry system (Mobius FX system, MFX) by 1) dosimetric plan verification using gamma passing rates and dose volume metrics and 2) error-detection capability evaluation by deliberately introduced machine error. Eighteen volumetric modulated arc therapy (VMAT) plans were studied. To evaluate the clinical performance of the MFX, we used gamma analysis and dose volume histogram (DVH) analysis. In addition, to evaluate the error-detection capability, we used gamma analysis and DVH analysis utilizing three types of deliberately introduced errors (Type 1: gantry angle-independent multi-leaf collimator (MLC) error, Type 2: gantry angle-dependent MLC error, and Type 3: gantry angle error). A dosimetric verification comparison of physical dosimetry system (Delt4PT) and online dosimetry system (MFX), gamma passing rates of the two dosimetry systems showed very good agreement with treatment planning system (TPS) calculation. For the average dose difference between the TPS calculation and the MFX measurement, most of the dose metrics showed good agreement within a tolerance of 3%. For the error-detection comparison of Delta4PT and MFX, the gamma passing rates of the two dosimetry systems did not meet the 90% acceptance criterion with the magnitude of error exceeding 2 mm and 1.5 ◦, respectively, for error plans of Types 1, 2, and 3. For delivery with all error types, the average dose difference of PTV due to error magnitude showed good agreement between calculated TPS and measured MFX within 1%. Overall, the results of the online dosimetry system showed very good agreement with those of the physical dosimetry system. Our results suggest that a log file-based online dosimetry system is a very suitable verification tool for accurate and efficient clinical routines for patient-specific quality assurance (QA).
Energy Technology Data Exchange (ETDEWEB)
Nguyen, Nam P.; Krafft, Shane P. [Arizona Univ., Tucson, AZ (United States). Dept. of Radiation Oncology; Vos, Paul [East Carolina Univ., Greenville, NC (US). Dept. of Biostatistics] (and others)
2011-09-15
To compare the dosimetry of tomotherapy and the conventional half-beam technique (HBT) or non-split beam technique (NSBT) for target coverage and radiation dose to the lacrimal glands and lens. A retrospective review of 7 patients with Graves' ophthalmopathy who had radiotherapy because of disease progression on high steroid dose is reported: 3 patients were treated with tomotherapy and 4 patients with HBT. Compared to HBT, tomotherapy may provide better target coverage and significant reduction of radiation dose to the lacrimal glands and a higher dose to the lens. The NSBT improved target coverage but resulted in significantly higher doses to the lens and lacrimal glands. Tomotherapy may provide better coverage of the target volume and may be more effective in reducing severe exophthalmos compared to the conventional radiotherapy technique. (orig.)
International Nuclear Information System (INIS)
Boudou, C; Tropres, I; Rousseau, J; Lamalle, L; Adam, J F; Esteve, F; Elleaume, H
2007-01-01
Synchrotron stereotactic radiotherapy (SSR) is a radiotherapy technique that makes use of the interactions of monochromatic low energy x-rays with high atomic number (Z) elements. An important dose-enhancement can be obtained if the target volume has been loaded with a sufficient amount of a high-Z element, such as iodine. In this study, we compare experimental dose measurements, obtained with normoxic polymer gel (nPAG), with Monte Carlo computations. Gels were irradiated within an anthropomorphic head phantom and were read out by magnetic resonance imaging. The dose-enhancement due to the presence of iodine in the gel (iodine concentration: 5 and 10 mg ml -1 ) was measured at two radiation energies (35 and 80 keV) and was compared to the calculated factors. nPAG dosimetry was shown to be efficient for measuring the sharp dose gradients produced by SSR. The agreement between 3D gel dosimetry and calculated dose distributions was found to be within 4% of the dose difference criterion and a distance to agreement of 2.1 mm for 80% of the voxels. Polymer gel doped with iodine exhibited higher sensitivity, in good agreement with the calculated iodine-dose enhancement. We demonstrate in this preliminary study that iodine-doped nPAG could be used for measuring in situ dose distributions for iodine-enhanced SSR treatment
International Nuclear Information System (INIS)
Izewska, Joanna; Arib, M.; Saravi, M.
2002-01-01
This document has been prepared within the framework of a Co-ordinated Research Programme (CRP) on Development of Quality Assurance Programme for Radiation Therapy Dosimetry in Developing Countries, during two Meetings at the IAEA Headquarters in Vienna (11-14 November 1996 and 6-10 October 1997). It is based on the recommendations of ISO 9000 series and ISO/IEC guide No. 25. The document can be used as a guide on how to prepare a quality manual for national External Audit Groups (EAG), i.e., a nationally recognised group in charge of operating external quality audits for radiotherapy dosimetry. The EAG of a given country includes the SSDL, a Measuring Group and a Medical Physics Group, who work in close co-operation at all steps of the audit. The content herein should be considered as a suggestion and additions or deletions can be made in accordance with the specific conditions in each country. It is preferable that the manual itself be as concise as possible, limiting it to the core scope. Detailed working sheets describing the procedures should be included in Appendices together with data sheets, questionnaires and reporting forms. The quality manual of each country should be carefully reviewed by all members of the EAG and, as far as possible, should be approved by relevant professional bodies and supported by health authorities. It has long been recognised that accurate knowledge of the dose in radiotherapy is vital to ensure safe and effective radiation treatments. To achieve this goal, comprehensive quality assurance programmes should be established to cover all steps from dose prescription to dose delivery. These programmes should include internal checks performed by the radiotherapy centres and external audits made by independent external bodies. It is estimated that not more than 50% of radiotherapy facilities world-wide have participated in some level of dose quality audit by an independent expert. Genuine concern exists that some, or even many
International Nuclear Information System (INIS)
Thomas, R.A.S.; Duane, S.; McEwen, M.R.; Rosser, K.E.
2002-01-01
In the UK, the National Physical Laboratory, in collaboration with the Institute for Physics and Engineering in Medicine operates an audit programme to ensure national consistency in radiotherapy dosimetry. The present programme covers dosimetry of megavoltage photons and electrons (3-19 MeV) and low and medium energy (10-300 kV) photons. The aim of each audit is to verify the local measurement of absorbed dose at the radiotherapy centre. The audit measurements - principally beam quality and linac output - are made following the same protocol as the clinic but using different equipment. The audit is not an absolute measurement of the absorbed dose but amounts to a check that the equipment used by the centre is operating as expected and that the Code of Practice is being followed correctly. The protocols used in the UK are IPSM 1990 for high-energy photons, IPEMB 1996 for electrons and IPEMB 1996 for low energy photons. For the purpose of these audits, NPL maintains a set of calibrated ionisation chambers
SU-F-T-562: Validation of EPID-Based Dosimetry for FSRS Commissioning
International Nuclear Information System (INIS)
Song, Y; Saleh, Z; Obcemea, C; Chan, M; Tang, X; Lim, S; Lovelock, D; Ballangrud, A; Mueller, B; Zinovoy, M; Gelblum, D; Mychalczak, B; Both, S
2016-01-01
Purpose: The prevailing approach to frameless SRS (fSRS) small field dosimetry is Gafchromic film. Though providing continuous information, its intrinsic uncertainties in fabrication, response, scan, and calibration often make film dosimetry subject to different interpretations. In this study, we explored the feasibility of using EPID portal dosimetry as a viable alternative to film for small field dosimetry. Methods: Plans prescribed a dose of 21 Gy were created on a flat solid water phantom with Eclipse V11 and iPlan for small static square fields (1.0 to 3.0 cm). In addition, two clinical test plans were computed by employing iPlan on a CIRS Kesler head phantom for target dimensions of 1.2cm and 2.0cm. Corresponding portal dosimetry plans were computed using the Eclipse TPS and delivered on a Varian TrueBeam machine. EBT-XD film dosimetry was performed as a reference. The isocenter doses were measured using EPID, OSLD, stereotactic diode, and CC01 ion chamber. Results: EPID doses at the center of the square field were higher than Eclipse TPS predicted portal doses, with the mean difference being 2.42±0.65%. Doses measured by EBT-XD film, OSLD, stereotactic diode, and CC01 ion chamber revealed smaller differences (except OSLDs), with mean differences being 0.36±3.11%, 4.12±4.13%, 1.7±2.76%, 1.45±2.37% for Eclipse and −1.36±0.85%, 2.38±4.2%, −0.03±0.50%, −0.27±0.78% for iPlan. The profiles measured by EPID and EBT-XD film resembled TPS (Eclipse and iPlan) predicted ones within 3.0%. For the two clinical test plans, the EPID mean doses at the center of field were 2.66±0.68% and 2.33±0.32% higher than TPS predicted doses. Conclusion: We found that results obtained with EPID portal dosimetry were slightly higher (∼2%) than those obtained with EBT-XD film, diode, and CC01 ion chamber with the exception of OSLDs, but well within IROC tolerance (5.0%). Therefore, EPID has the potential to become a viable real-time alternative method to film dosimetry.
SU-F-T-562: Validation of EPID-Based Dosimetry for FSRS Commissioning
Energy Technology Data Exchange (ETDEWEB)
Song, Y; Saleh, Z; Obcemea, C; Chan, M; Tang, X; Lim, S; Lovelock, D; Ballangrud, A; Mueller, B; Zinovoy, M; Gelblum, D; Mychalczak, B; Both, S [Memorial Sloan Kettering Cancer Center, NY (United States)
2016-06-15
Purpose: The prevailing approach to frameless SRS (fSRS) small field dosimetry is Gafchromic film. Though providing continuous information, its intrinsic uncertainties in fabrication, response, scan, and calibration often make film dosimetry subject to different interpretations. In this study, we explored the feasibility of using EPID portal dosimetry as a viable alternative to film for small field dosimetry. Methods: Plans prescribed a dose of 21 Gy were created on a flat solid water phantom with Eclipse V11 and iPlan for small static square fields (1.0 to 3.0 cm). In addition, two clinical test plans were computed by employing iPlan on a CIRS Kesler head phantom for target dimensions of 1.2cm and 2.0cm. Corresponding portal dosimetry plans were computed using the Eclipse TPS and delivered on a Varian TrueBeam machine. EBT-XD film dosimetry was performed as a reference. The isocenter doses were measured using EPID, OSLD, stereotactic diode, and CC01 ion chamber. Results: EPID doses at the center of the square field were higher than Eclipse TPS predicted portal doses, with the mean difference being 2.42±0.65%. Doses measured by EBT-XD film, OSLD, stereotactic diode, and CC01 ion chamber revealed smaller differences (except OSLDs), with mean differences being 0.36±3.11%, 4.12±4.13%, 1.7±2.76%, 1.45±2.37% for Eclipse and −1.36±0.85%, 2.38±4.2%, −0.03±0.50%, −0.27±0.78% for iPlan. The profiles measured by EPID and EBT-XD film resembled TPS (Eclipse and iPlan) predicted ones within 3.0%. For the two clinical test plans, the EPID mean doses at the center of field were 2.66±0.68% and 2.33±0.32% higher than TPS predicted doses. Conclusion: We found that results obtained with EPID portal dosimetry were slightly higher (∼2%) than those obtained with EBT-XD film, diode, and CC01 ion chamber with the exception of OSLDs, but well within IROC tolerance (5.0%). Therefore, EPID has the potential to become a viable real-time alternative method to film dosimetry.
International Nuclear Information System (INIS)
Venegas Rojas, Deybith
2014-01-01
An evaluation and analysis are realized of dosimetry of the treatment planning system (TPS) of three-dimensional conformal external radiotherapy in the Servicio de Radioterapia of the Hospital Mexico of Costa Rica. An evaluation procedure is proposed based on IAEA-TECDOC-1540 document, and may continue to be applied periodically in this or other radiotherapy services. Tests realized have checked the representation of distances and electronics densities transferred to the TPS, match with those of real objects. The 16 tests applied have represented situations of real treatments with different configurations and beam modifiers in the equipment used daily. The tests have measured the absorbed dose to water in different significant points at different depths, using photon beams of 6 MeV and 18 MeV. The physical parameters of the tests were simulated. The absorbed dose has been calculated at specified points. The XiO and Eclipse TPS have been used with the calculation algorithms: Superposition, Convolution and AAA. The results of the calculations are evaluated with statistical methods and comparing them with the measurements of absorbed dose. A generalized tendency has been detected toward negative relative errors, implying an underestimation of the dose by the TPS; due to a difference found in the accelerator output factor respect to its commissioning. The AAA algorithm has determined a better performance, although with greater difficulties of calculus in the region of build-up. Convolution and Superposition algorithms have had similar performances and both have presented problems in high depths and out of edges of the fields. The result of the dosimetric evaluation has been satisfactory in real conditions of equipment; but several particularities have been found that should be reviewed and adjusted. The precision of the TPS has been adequate in the majority of situations important for treatment planning. [author] [es
Development of physical and numerical techniques of Alanine/EPR dosimetry in radiotherapy
International Nuclear Information System (INIS)
Castro, F.; Ponte, F.; Pereira, L.
2006-01-01
In this work, a set of 50 alanine dosimeters has been used in a radiotherapy context, simulating a two-dimensional treatment in a non-overlapping dosimeter configuration. The dose is reconstructed from physical and numerical simulation of the electron paramagnetic resonance signal, calculating the spin density. Thus, it can be used to better adjust the error in the calibration curve to give a final accuracy of <0.03 Gy. A complete set of experimental test parameters have been used with a standard dosimeter in order to obtain the best analysis configuration. These results indicate that for a conventional treatment of some hundreds of mGy, this method can be useful with a correct signal validation. A numerical test and fitting software has been developed. The general use of alanine/electron paramagnetic resonance dosimetry in radiotherapy context is discussed. (authors)
Safety Improvement in Radiotherapy Treatment Plan. Planning vs Redundant Check vs in vivo Dosimetry
International Nuclear Information System (INIS)
Torres Diaz, J.; Ascencion Ybarra, Y.; La Fuentes Rosales, L. de; Lara Mas, E.; Larrinaga Cortinas, E.
2013-01-01
In Cuba it is mandatory to have an independent monitor units check before any radiotherapy treatment is started. The main objective of this paper is to enhance the safety of the radiotherapy planning by developing and testing a practical tool to double check the monitor units calculation for external beam high energy photon therapy. A software for monitor units (MUs) verification was designed and coded. It considers the common in clinical practice isocentric set-ups. The in vivo dosimetry measurements were done with a silicon diode system for 6 MV photon beams to support the validation of the software. The results show a discrepancy within 5% between the 3 methods which is in accordance with international recommendations. (Author)
International Nuclear Information System (INIS)
2000-01-01
The International Atomic Energy Agency published in 1987 an International Code of Practice entitled 'Absorbed Dose Determination in Photon and Electron Beams' (IAEA Technical Reports Series No. 277 (TRS-277)), recommending procedures to obtain the absorbed dose in water from measurements made with an ionization chamber in external beam radiotherapy. A second edition of TRS-277 was published in 1997 updating the dosimetry of photon beams, mainly kilovoltage X rays. Another International Code of Practice for radiotherapy dosimetry entitled 'The Use of Plane-Parallel Ionization Chambers in High Energy Electron and Photon Beams' (IAEA Technical Reports Series No. 381 (TRS-381)) was published in 1997 to further update TRS-277 and complement it with respect to the area of parallel-plate ionization chambers. Both codes have proven extremely valuable for users involved in the dosimetry of the radiation beams used in radiotherapy. In TRS-277 the calibration of the ionization chambers was based on primary standards of air kerma; this procedure was also used in TRS-381, but the new trend of calibrating ionization chambers directly in a water phantom in terms of absorbed dose to water was introduced. The development of primary standards of absorbed dose to water for high energy photon and electron beams, and improvements in radiation dosimetry concepts, offer the possibility of reducing the uncertainty in the dosimetry of radiotherapy beams. The dosimetry of kilovoltage X rays, as well as that of proton and heavy ion beams, interest in which has grown considerably in recent years, can also be based on these standards. Thus a coherent dosimetry system based on standards of absorbed dose to water is possible for practically all radiotherapy beams. Many Primary Standard Dosimetry Laboratories (PSDLs) already provide calibrations in terms of absorbed dose to water at the radiation quality of 60 Co gamma rays. Some laboratories have extended calibrations to high energy photon and
Study of film dosimetry for radiotherapy with Gafchromic-RTQ plates
International Nuclear Information System (INIS)
Diaz Moreno, Rogelio Manuel; Lara Mas, Elier; Alfonso Laguardia, Rodolfo
2009-01-01
Film dosimetry allows quality control processes (CC) for advanced radiotherapy treatments, not achievable with other types of systems dosimetry, as is the determination of two-dimensional dose distribution provided with the planned treatment in selected planes. The aim of this work was to establish the possibilities of making this type of CC with the means available in the INOR. Plates were used radiochromic Gafchromic-RTQ, for quality control, which irradiated with Elekta Precise linear accelerator, according to the test planning developed in the treatment planning system Precise Plan. Were used as image processing software the Mephysto mc2, PTW, and routines scheduled at home on Matlab. Was prepared calibration curve Dose-response for these plates, and applied this calibration curve at other boards with known radiation dose to estimate proximity of the dose obtained through calibration. Other tests were performed to determine the conditions of repeatability and optimal parameters of the process. Conditions were established that are obtained more reliable , the which are lower than those reported Gafchromic-EBT plates, especially designed quantitative dosimetric purposes, but in certain ranges allow evaluate the of a plan with an acceptable degree of approximation. (author)
Real-time in vivo luminescence dosimetry in radiotherapy and mammography using Al2O3:C
International Nuclear Information System (INIS)
Aznar, M.C.
2005-07-01
New treatment and clinical imaging techniques have created a need for accurate and practical in vivo dosimeters in radiation medicine. This work describes the development of a new optical-fiber radiation dosimeter system, based on radioluminescence (RL) and optically stimulated luminescence (OSL) from carbon-doped aluminium oxide (Al2O3:C), for applications in radiotherapy and mammography. This system offers several features, such as a small detector, high sensitivity, real-time read-out, and the ability to measure both dose rate and absorbed dose. Measurement protocols and algorithms for the correction of responses were developed to enable a reliable absorbed dose assessment from the RL and OSL signals. At radiotherapy energies, the variation of the signal with beam parameters was smaller than 1% (1 SD). Treatment-like experiments in phantoms, and in vivo measurements during complex patient treatments (such as intensity-modulated radiation therapy) indicate that the RL/OSL dosimetry system can reliably measure the absorbed dose within 2%. The real-time RL signal also enables an individual dose assessment from each field. The RL/OSL dosimetry system was also used during mammography examinations. In such conditions, the reproducibility of the measurements showed to be around 3%. In vivo measurements on three patients showed that the presence of the RL/OSL probes did not degrade the diagnostic quality of the radiograph and that the system could be used to measure exit doses (i.e., absorbed doses on the inferior surface of the breast). A Monte Carlo study proved that the energy dependence of the RL/OSL system at these low energies could be reduced by optimizing the design of the probes. It is concluded that the new RL/OSL dosimetry system shows considerable potential for applications in both radiotherapy and mammography. (au)
Characterization of commercial MOSFETS electron dosimetry
International Nuclear Information System (INIS)
Carvajal, M. A.; Simancas, F.; Guirado, D.; Banqueri, J.; Vilches, M.; Lallena, A. M.; Palma, A. J.
2011-01-01
In recent years there have been commercial dosimetry devices based on transistors Metal-Oxide-Semiconductor (MOSFET) having a number of advantages over traditional systems for dosimetry in medical applications. These include the portability of the sensor element and a reading process quick and relatively simple dose, linearity, and so on. The use of electron beams is important in modern radiotherapy include its use in intra-operative radiotherapy (RIO). This paper presents an initial characterization of different business models MOSFET, not specific for radiation detection, to demonstrate their potential as sensors for electron beam dosimetry. (Author)
Calculation of uncertainties in the protocol of dosimetry for Co 60 beams in Radiotherapy
International Nuclear Information System (INIS)
Velazquez M, S.; Carrera M, F.; Sanchez S, J.
1998-01-01
The objective in this work is to show how the uncertainty is possible to know in the determination of the absorbed dose in Co 60 photon beams and to establish in a rational form, tolerance levels for this. It is took as base the spanish protocol of dosimetry in Radiotherapy. We have been centered in a Co 60 beam. We utilized the statistical theory of little samples. We allowed to suggest a new approach about the treatment of the tolerance levels and the uncertainty of the measurement. After two years of experience in the practical hospitable application we have gotten to put around 1 % uncertainty in the absolute dosimetry of the Co 60 beam. The presented protocol allows to execute the accuracy requirements in the determination of absorbed doses. (Author)
Energy Technology Data Exchange (ETDEWEB)
Mosher, E; Kim, S; Lee, C [Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD (United States); Lee, C [Department of Radiation Oncology, University of Michigan, Ann Arbor, MI (United States); Pelletier, C; Jung, J [Department of Physics, East Carolina University Greenville, NC (United States); Jones, E [Radiology and Imaging Sciences Clinical Center, National Institutes of Health, Bethesda, MD (United States)
2016-06-15
Purpose: Epidemiological studies of second cancer risks in breast cancer radiotherapy patients often use generic patient anatomy to reconstruct normal tissue doses when CT images of patients are not available. To evaluate the uncertainty involved in the dosimetry approach, we evaluated the esophagus dose in five sample patients by simulating breast cancer treatments. Methods: We obtained the diagnostic CT images of five anonymized adult female patients in different Body Mass Index (BMI) categories (16– 36kg/m2) from National Institutes of Health Clinical Center. We contoured the esophagus on the CT images and imported them into a Treatment Planning System (TPS) to create treatment plans and calculate esophagus doses. Esophagus dose was calculated once again via experimentally-validated Monte Carlo (MC) transport code, XVMC under the same geometries. We compared the esophagus doses from TPS and the MC method. We also investigated the degree of variation in the esophagus dose across the five patients and also the relationship between the patient characteristics and the esophagus doses. Results: Eclipse TPS using Analytical Anisotropic Algorithm (AAA) significantly underestimates the esophagus dose in breast cancer radiotherapy compared to MC. In the worst case, the esophagus dose from AAA was only 40% of the MC dose. The Coefficient of Variation across the patients was 48%. We found that the maximum esophagus dose was up to 2.7 times greater than the minimum. We finally observed linear relationship (Dose = 0.0218 × BMI – 0.1, R2=0.54) between patient’s BMI and the esophagus doses. Conclusion: We quantified the degree of uncertainty in the esophagus dose in five sample breast radiotherapy patients. The results of the study underscore the importance of individualized dose reconstruction for the study cohort to avoid misclassification in the risk analysis of second cancer. We are currently extending the number of patients up to 30.
International Nuclear Information System (INIS)
Mosher, E; Kim, S; Lee, C; Lee, C; Pelletier, C; Jung, J; Jones, E
2016-01-01
Purpose: Epidemiological studies of second cancer risks in breast cancer radiotherapy patients often use generic patient anatomy to reconstruct normal tissue doses when CT images of patients are not available. To evaluate the uncertainty involved in the dosimetry approach, we evaluated the esophagus dose in five sample patients by simulating breast cancer treatments. Methods: We obtained the diagnostic CT images of five anonymized adult female patients in different Body Mass Index (BMI) categories (16– 36kg/m2) from National Institutes of Health Clinical Center. We contoured the esophagus on the CT images and imported them into a Treatment Planning System (TPS) to create treatment plans and calculate esophagus doses. Esophagus dose was calculated once again via experimentally-validated Monte Carlo (MC) transport code, XVMC under the same geometries. We compared the esophagus doses from TPS and the MC method. We also investigated the degree of variation in the esophagus dose across the five patients and also the relationship between the patient characteristics and the esophagus doses. Results: Eclipse TPS using Analytical Anisotropic Algorithm (AAA) significantly underestimates the esophagus dose in breast cancer radiotherapy compared to MC. In the worst case, the esophagus dose from AAA was only 40% of the MC dose. The Coefficient of Variation across the patients was 48%. We found that the maximum esophagus dose was up to 2.7 times greater than the minimum. We finally observed linear relationship (Dose = 0.0218 × BMI – 0.1, R2=0.54) between patient’s BMI and the esophagus doses. Conclusion: We quantified the degree of uncertainty in the esophagus dose in five sample breast radiotherapy patients. The results of the study underscore the importance of individualized dose reconstruction for the study cohort to avoid misclassification in the risk analysis of second cancer. We are currently extending the number of patients up to 30.
Development of manual procedures for care of pregnant patients in radiotherapy service
International Nuclear Information System (INIS)
Scarabino, M.L.; Ruggeri, R.M.; Colombo, S.; Mairal, L.; Sardi, M.E.
2013-01-01
The work involves the creation of a manual of procedures for the care of pregnant patients in a radiotherapy center in which each instance of treatment is included, from the obstetrician-oncology comprehensive assessment during admission to establishing controls newborn and its subsequent development in multidisciplinary team. For the preparation of the manual had to design an anthropomorphic phantom that resembles a pregnant woman, which was used to carry out internal and external dosimetry. In turn imparted calculations fetal doses using TPS, imaging tests with MRI, avoiding the use of the tomograph and adapted to the resonator involved were carried immobilizer. All experiences and progress made during the treated cases are introduced in the procedures manual, making it a dynamic tool for continuous improvement for the institution
Foundations of ionizing radiation dosimetry
International Nuclear Information System (INIS)
Denisenko, O.N.; Pereslegin, I.A.
1985-01-01
Foundations of dosimetry in application to radiotherapy are presented. General characteristics of ionizing radiations and main characteristics of ionizing radiation sources, mostly used in radiotherapy, are given. Values and units for measuring ionizing radiation (activity of a radioactive substance, absorbed dose, exposure dose, integral dose and dose equivalent are considered. Different methods and instruments for ionizing radiation dosimetry are discussed. The attention is paid to the foundations of clinical dosimetry (representation of anatomo-topographic information, choice of radiation conditions, realization of radiation methods, corrections for a configuration and inhomogeneity of a patient's body, account of biological factors of radiation effects, instruments of dose field formation, control of irradiation procedure chosen)
Evaluation of six TPS algorithms in computing entrance and exit doses
Metwaly, Mohamed; Glegg, Martin; Baggarley, Shaun P.; Elliott, Alex
2014-01-01
Entrance and exit doses are commonly measured in in vivo dosimetry for comparison with expected values, usually generated by the treatment planning system (TPS), to verify accuracy of treatment delivery. This report aims to evaluate the accuracy of six TPS algorithms in computing entrance and exit doses for a 6 MV beam. The algorithms tested were: pencil beam convolution (Eclipse PBC), analytical anisotropic algorithm (Eclipse AAA), AcurosXB (Eclipse AXB), FFT convolution (XiO Convolution), multigrid superposition (XiO Superposition), and Monte Carlo photon (Monaco MC). Measurements with ionization chamber (IC) and diode detector in water phantoms were used as a reference. Comparisons were done in terms of central axis point dose, 1D relative profiles, and 2D absolute gamma analysis. Entrance doses computed by all TPS algorithms agreed to within 2% of the measured values. Exit doses computed by XiO Convolution, XiO Superposition, Eclipse AXB, and Monaco MC agreed with the IC measured doses to within 2%‐3%. Meanwhile, Eclipse PBC and Eclipse AAA computed exit doses were higher than the IC measured doses by up to 5.3% and 4.8%, respectively. Both algorithms assume that full backscatter exists even at the exit level, leading to an overestimation of exit doses. Despite good agreements at the central axis for Eclipse AXB and Monaco MC, 1D relative comparisons showed profiles mismatched at depths beyond 11.5 cm. Overall, the 2D absolute gamma (3%/3 mm) pass rates were better for Monaco MC, while Eclipse AXB failed mostly at the outer 20% of the field area. The findings of this study serve as a useful baseline for the implementation of entrance and exit in vivo dosimetry in clinical departments utilizing any of these six common TPS algorithms for reference comparison. PACS numbers: 87.55.‐x, 87.55.D‐, 87.55.N‐, 87.53.Bn PMID:24892349
International Nuclear Information System (INIS)
Sanchez-Parcerisa, D; Carabe-Fernandez, A
2014-01-01
Purpose. Intensity-modulated proton therapy is usually implemented with multi-field optimization of pencil-beam scanning (PBS) proton fields. However, at the view of the experience with photon-IMRT, proton facilities equipped with double-scattering (DS) delivery and multi-leaf collimation (MLC) could produce highly conformal dose distributions (and possibly eliminate the need for patient-specific compensators) with a clever use of their MLC field shaping, provided that an optimal inverse TPS is developed. Methods. A prototype TPS was developed in MATLAB. The dose calculation process was based on a fluence-dose algorithm on an adaptive divergent grid. A database of dose kernels was precalculated in order to allow for fast variations of the field range and modulation during optimization. The inverse planning process was based on the adaptive simulated annealing approach, with direct aperture optimization of the MLC leaves. A dosimetry study was performed on a phantom formed by three concentrical semicylinders separated by 5 mm, of which the inner-most and outer-most were regarded as organs at risk (OARs), and the middle one as the PTV. We chose a concave target (which is not treatable with conventional DS fields) to show the potential of our technique. The optimizer was configured to minimize the mean dose to the OARs while keeping a good coverage of the target. Results. The plan produced by the prototype TPS achieved a conformity index of 1.34, with the mean doses to the OARs below 78% of the prescribed dose. This Result is hardly achievable with traditional conformal DS technique with compensators, and it compares to what can be obtained with PBS. Conclusion. It is certainly feasible to produce IMPT fields with MLC passive scattering fields. With a fully developed treatment planning system, the produced plans can be superior to traditional DS plans in terms of plan conformity and dose to organs at risk
DEFF Research Database (Denmark)
Aznar, M.C.; Andersen, C.E.; Bøtter-Jensen, L.
2004-01-01
, real-time read-out and the ability to measure both dose rate and absorbed dose. The measurements describing reproducibility and output dependence on dose rate, field size and energy all had standard deviations smaller than 1%. The signal variation with the angle of incidence was smaller than 2% (1 SD......). Measurements performed in clinical situations suggest the potential of using this real-time system for in vivo dosimetry in radiotherapy....
Energy Technology Data Exchange (ETDEWEB)
Rannou, A.; Aubert, B.; Lahaye, Th.; Scaff, P.; Casanova, Ph.; Van Bladel, L.; Queinnec, F.; Valendru, N.; Jehanno, J.; Grude, E.; Berard, Ph.; Desbree, A.; Kafrouni, H.; Paquet, F.; Vanhavere, F.; Bridier, A.; Ginestet, Ch.; Magne, S.; Donadille, L.; Bordy, J.M.; Bottollier-Depois, J.F.; Barrere, J.L.; Ferragut, A.; Metivier, H.; Gaillard-Lecanu, E
2008-07-01
These days organised by the section of the technical protection of the S.F.R.P. review the different techniques of dosimetry used in France and Europe, and present the future orientations.The different interventions are as follow: Individual exposures of the workers: historic assessment and perspectives; medical exposure: where are the doses; legal obligations in individual dosimetry: which are the objective and the need on the subject; the dosimetry follow-up of workers by the S.I.S.E.R.I. system: assessment and perspectives; impact of the norm ISO 20553 on the follow-up of internal exposure; the implementation of the patient dose measurement in Belgium; techniques of passive dosimetry used in Europe; Supervision radiation protection at EDF: long term and short term approach; Comparison active and passive dosimetry at Melox; methodology for the choice of new neutron dosemeters; the working group M.E.D.O.R.: guide of internal dosimetry for the use of practitioners; O.E.D.I.P.E.: tool of modeling for the personalized internal dosimetry; the use of the Monte-Carlo method for the planning of the cancer treatment by radiotherapy becomes a reality; the works of the committee 2 of the ICRP; passive dosimetry versus operational dosimetry: situation in Europe; Implementation of the in vivo dosimetry in a radiotherapy department: experience of the Gustave Roussy institute; experience feedback on the in vivo measures in radiotherapy, based on the use of O.S.L. pellets; multi points O.S.L. instrumentation for the radiation dose monitoring in radiotherapy; dosimetry for extremities for medical applications: principle results of the European contract C.O.N.R.A.D.; references and perspectives in dosimetry; what perspectives for numerical dosimetry, an example: Sievert; system of dose management: how to answer to needs; the last technical evolutions in terms of electronic dosimetry in nuclear power plant; the fourth generation type reactors: what dosimetry. (N.C.)
International Nuclear Information System (INIS)
Izewska, Joanna; Dutreix, A.; Followill, D.S.; Nisbet, A.; Novotny, J.; Sipila, P.; Dam, J. van
2002-01-01
Since 1969 the International Atomic Energy Agency (IAEA), together with the World Health Organization (WHO), has performed postal TLD audits to verify the calibration of radiotherapy beams in developing countries. The IAEA over the past 30 years, has verified the calibration of more than 3500 clinical photon beams at approximately 1000 radiotherapy hospitals. Detailed follow-up procedures have been implemented since 1996. When the TLD result of a participating institution falls outside the acceptance limits of ±5%, the institution is initially informed that there is a discrepancy and requested to try to identify the reasons why it occurred. The institution is not informed of the actual magnitude of the discrepancy (blind conditions) but is offered a second TLD audit. If the deviation cannot be resolved by the local radiotherapy institution or the national SSDL, then an on-site visit is suggested which, if accepted, is made by an IAEA expert in clinical dosimetry. The on-site visit includes a review of the dosimetry data and techniques, corrective measurements and ad-hoc training. The reasons for the discrepancy are then traced, explained, corrected and reported. Until the discrepancies are resolved and changes have been implemented by hospitals to ensure that the discrepancies do not reoccur, the safe and effective delivery of radiation doses to patients is questionable. This document provides a standardised set of procedures for resolving discrepancies during onsite visits to radiotherapy hospitals by the IAEA experts. The table below summarises the acceptance criteria to be used by the IAEA experts for dosimetry and mechanical parameters of the hospital treatment units. If some of the parameters are outside the acceptance criterion, it will not be possible for an institution to assure the adequate quality of the dosimetry practices in radiotherapy. The criteria are based on analyses of clinical data and the measurement uncertainties for various dosimetry and
Energy Technology Data Exchange (ETDEWEB)
Amaral, Leonardo L.; Oliveira, Harley F.; Fairbanks, Leandro R., E-mail: leonardo.fis@usp.br [Universidade de Sao Paulo (HCFMRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Medicina. Hospital das Clinicas; Nicolucci, Patricia; Netto, Thomaz G. [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Faculdade de Filosofia, Ciencias e Letras. Departamento de Fisica
2012-12-15
Radiotherapy of brain lesions near critical structures requires a high accuracy in the location and dose. The high precision is achieved by the location of the stereotactic apparatus. The accuracy in dose delivery should be accompanied by an accurate quality control in devices that involve the practice, however, still does not guarantee the dose at the time of therapy. The large number of fields and the small size of these conventional methods difficult dosimetry during treatment. The objective of this work was to develop a verification methodology in vivo dosimetry in stereotactic radiotherapy with the aid of the film radiochromic Linear Accelerator with multi leaf collimators Moduleaf. The technique uses film segments radiochromic Gafchromic EBT2, with dimensions of 1x1 cm{sup 2} in area outside the coupled micro-multileaf Moduleaf Siemens. These films were inserted in the region of the central axis of the beam. The films were irradiated and calibrated to obtain the factors that determine the size dependence of the dosimetric field. With these data, we designed a computer program which calculates the density of a film must acquire when subjected to an exposure in this setting. This study evaluated five non-coplanar plans, the first with 15 fields and the other with 25 fields. Before starting the procedure, the film segment is coupled to the device, and after the treatment, the relative density is evaluated and compared with the calculated. The average value of the verification at the time of radiation dosimetry compared with the calculated by the sheet was 1.5%. The data collected in this study showed a satisfactory agreement between measured and calculated by the program in the densitometer. Thus, a methodology was developed to verify in vivo dosimetry in radiotherapy and stereotactic linear accelerator collimators Moduleaf. (author)
Kamomae, Takeshi; Shimizu, Hidetoshi; Nakaya, Takayoshi; Okudaira, Kuniyasu; Aoyama, Takahiro; Oguchi, Hiroshi; Komori, Masataka; Kawamura, Mariko; Ohtakara, Kazuhiro; Monzen, Hajime; Itoh, Yoshiyuki; Naganawa, Shinji
2017-12-01
Pretreatment intensity-modulated radiotherapy quality assurance is performed using simple rectangular or cylindrical phantoms; thus, the dosimetric errors caused by complex patient-specific anatomy are absent in the evaluation objects. In this study, we construct a system for generating patient-specific three-dimensional (3D)-printed phantoms for radiotherapy dosimetry. An anthropomorphic head phantom containing the bone and hollow of the paranasal sinus is scanned by computed tomography (CT). Based on surface rendering data, a patient-specific phantom is formed using a fused-deposition-modeling-based 3D printer, with a polylactic acid filament as the printing material. Radiophotoluminescence glass dosimeters can be inserted in the 3D-printed phantom. The phantom shape, CT value, and absorbed doses are compared between the actual and 3D-printed phantoms. The shape difference between the actual and printed phantoms is less than 1 mm except in the bottom surface region. The average CT value of the infill region in the 3D-printed phantom is -6 ± 18 Hounsfield units (HU) and that of the vertical shell region is 126 ± 18 HU. When the same plans were irradiated, the dose differences were generally less than 2%. These results demonstrate the feasibility of the 3D-printed phantom for artificial in vivo dosimetry in radiotherapy quality assurance. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Individual dosimetry of workers and patients: implementation and perspectives
International Nuclear Information System (INIS)
Rannou, A.; Aubert, B.; Lahaye, Th.; Scaff, P.; Casanova, Ph.; Van Bladel, L.; Queinnec, F.; Valendru, N.; Jehanno, J.; Grude, E.; Berard, Ph.; Desbree, A.; Kafrouni, H.; Paquet, F.; Vanhavere, F.; Bridier, A.; Ginestet, Ch.; Magne, S.; Donadille, L.; Bordy, J.M.; Bottollier-Depois, J.F.; Barrere, J.L.; Ferragut, A.; Metivier, H.; Gaillard-Lecanu, E.
2008-01-01
These days organised by the section of the technical protection of the S.F.R.P. review the different techniques of dosimetry used in France and Europe, and present the future orientations.The different interventions are as follow: Individual exposures of the workers: historic assessment and perspectives; medical exposure: where are the doses; legal obligations in individual dosimetry: which are the objective and the need on the subject; the dosimetry follow-up of workers by the S.I.S.E.R.I. system: assessment and perspectives; impact of the norm ISO 20553 on the follow-up of internal exposure; the implementation of the patient dose measurement in Belgium; techniques of passive dosimetry used in Europe; Supervision radiation protection at EDF: long term and short term approach; Comparison active and passive dosimetry at Melox; methodology for the choice of new neutron dosemeters; the working group M.E.D.O.R.: guide of internal dosimetry for the use of practitioners; O.E.D.I.P.E.: tool of modeling for the personalized internal dosimetry; the use of the Monte-Carlo method for the planning of the cancer treatment by radiotherapy becomes a reality; the works of the committee 2 of the ICRP; passive dosimetry versus operational dosimetry: situation in Europe; Implementation of the in vivo dosimetry in a radiotherapy department: experience of the Gustave Roussy institute; experience feedback on the in vivo measures in radiotherapy, based on the use of O.S.L. pellets; multi points O.S.L. instrumentation for the radiation dose monitoring in radiotherapy; dosimetry for extremities for medical applications: principle results of the European contract C.O.N.R.A.D.; references and perspectives in dosimetry; what perspectives for numerical dosimetry, an example: Sievert; system of dose management: how to answer to needs; the last technical evolutions in terms of electronic dosimetry in nuclear power plant; the fourth generation type reactors: what dosimetry. (N.C.)
Energy Technology Data Exchange (ETDEWEB)
Tao, C; Liu, T; Chen, J; Zhu, J; Yin, Y [Shandong Cancer Hospital and Institute, Jinan, Shandong (China)
2016-06-15
Purpose: This study aimed to analyze dosimetry changes during radiotherapy for the mid-thoracic esophageal carcinoma, and investigate dosimetry difference between rigid and deformed registration. Methods: Twelve patients with primary middle thoracic esophageal carcinoma were selected randomly. Based on first CT scanning of each patient, plans-o were generated by experience physicists. After 20 fractions treatment, the corresponding plans-re were created with second CT scanning. And then, these two CT images were rigid and deformed registration respectively, and the dose was accumulated plan-o with plan-re. The dosimetry variation of these plans (plan-o: with 30 fractions, plan-rig: the accumulated dose with rigid registration and plan-def: the accumulated dose with deformed registration) were evaluated by paired T-test. Results: The V20 value of total lung were 32.68%, 30.3% and 29.71% for plan-o, plan-rig and plan-def respectively. The mean dose of total lung was 17.19 Gy, 16.67 Gy and 16.51 Gy for plan-o plan-rig and plan-def respectively. There were significant differences between plan-o and plan-rig or plan-def for both V20 and mean dose of total lung (with p= 0.003, p= 0.000 for V20 and p=0.008, p= 0.000 for mean dose respectively). There was no significant difference between plan-rig and plan-def (with p=0.118 for V20 and p=0.384 for mean dose). The max dose of spinal-cord was 41.95 Gy, 41.48 Gy and 41.4 Gy for plan-o, plan-rig and plan-def respectively. There were no significant differences for the max dose of spinal-cord between these plans. Conclusion: The target volume changes and anatomic position displacement of mid-thoracic esophageal carcinoma should not be neglected in clinics. These changes would cause overdose in normal tissue. Therefore, it is necessary to have another CT scanning and re-plan during the mid-thoracic esophageal carcinoma radiotherapy. And the dosimetry difference between rigid and deformed fusions was not found in this study.
In-vivo (entrance) dose measurements in external beam radiotherapy with aqueous FBX dosimetry system
International Nuclear Information System (INIS)
Semwal, M.K.; Thakur, P.K.; Bansal, A.K.; Vidyasagar, P.B.
2005-01-01
FBX aqueous chemical dosimetry system has been found useful in radiotherapy owing to its low dose measuring capability. In the present work, entrance dose measurements in external beam radiotherapy on a telecobalt machine were carried out with the system on 100 patients. Treatments involving simple beam arrangement of open parallel-opposed beams in cranial and pelvic irradiations were selected for this study. In place of a spectrophotometer, a simple and inexpensive colorimeter was used for absorbance measurements. The purpose was to assess the efficacy of the FBX system for in-vivo dose measurements. The results obtained show that the average discrepancy between the measured and expected dose for both categories of patients was 0.2% (standard deviation 3.2%) with a maximum of +1 0.3%. There were 5.5% cases showing more than ± 5% discrepancy. Comparison of the results obtained with published work on entrance dose measurements, with diode detectors, shows that the inexpensive FBX system can be used for in-vivo (entrance) dose measurements for simple beam arrangements in radiotherapy and can thus serve as a useful QA tool. (author)
International Nuclear Information System (INIS)
Chen, G.T.Y.; Collier, J.M.; Lyman, J.T.; Pitluck, S.
1982-01-01
The Radiotherapy Physics Group works on the physical and biophysical aspects of charged particle radiotherapy. Our activities include the development of isosurvival beams (beams of uniform biological effect), computerized treatment planning development for charged particle radiotherapy, design of compensation to shape dose distributions, and development of dosimetry techniques to verify planned irradiations in both phantoms and patients
Real-time in vivo luminescence dosimetry in radiotherapy and mammography using Al{sub 2}O{sub 3}:C
Energy Technology Data Exchange (ETDEWEB)
Aznar, M.C.
2005-06-15
New treatment and clinical imaging techniques have created a need for accurate and practical in vivo dosimeters in radiation medicine. This work describes the development of a new optical-fiber radiation dosimeter system, based on radioluminescence (RL) and optically stimulated luminescence (OSL) from carbon-doped aluminium oxide (Al2O3:C), for applications in radiotherapy and mammography. This system offers several features, such as a small detector, high sensitivity, real-time read-out, and the ability to measure both dose rate and absorbed dose. Measurement protocols and algorithms for the correction of responses were developed to enable a reliable absorbed dose assessment from the RL and OSL signals. At radiotherapy energies, the variation of the signal with beam parameters was smaller than 1% (1 SD). Treatment-like experiments in phantoms, and in vivo measurements during complex patient treatments (such as intensity-modulated radiation therapy) indicate that the RL/OSL dosimetry system can reliably measure the absorbed dose within 2%. The real-time RL signal also enables an individual dose assessment from each field. The RL/OSL dosimetry system was also used during mammography examinations. In such conditions, the reproducibility of the measurements showed to be around 3%. In vivo measurements on three patients showed that the presence of the RL/OSL probes did not degrade the diagnostic quality of the radiograph and that the system could be used to measure exit doses (i.e., absorbed doses on the inferior surface of the breast). A Monte Carlo study proved that the energy dependence of the RL/OSL system at these low energies could be reduced by optimizing the design of the probes. It is concluded that the new RL/OSL dosimetry system shows considerable potential for applications in both radiotherapy and mammography. (au)
Ojala, J; Hyödynmaa, S; Barańczyk, R; Góra, E; Waligórski, M P R
2014-03-01
Electron radiotherapy is applied to treat the chest wall close to the mediastinum. The performance of the GGPB and eMC algorithms implemented in the Varian Eclipse treatment planning system (TPS) was studied in this region for 9 and 16 MeV beams, against Monte Carlo (MC) simulations, point dosimetry in a water phantom and dose distributions calculated in virtual phantoms. For the 16 MeV beam, the accuracy of these algorithms was also compared over the lung-mediastinum interface region of an anthropomorphic phantom, against MC calculations and thermoluminescence dosimetry (TLD). In the phantom with a lung-equivalent slab the results were generally congruent, the eMC results for the 9 MeV beam slightly overestimating the lung dose, and the GGPB results for the 16 MeV beam underestimating the lung dose. Over the lung-mediastinum interface, for 9 and 16 MeV beams, the GGPB code underestimated the lung dose and overestimated the dose in water close to the lung, compared to the congruent eMC and MC results. In the anthropomorphic phantom, results of TLD measurements and MC and eMC calculations agreed, while the GGPB code underestimated the lung dose. Good agreement between TLD measurements and MC calculations attests to the accuracy of "full" MC simulations as a reference for benchmarking TPS codes. Application of the GGPB code in chest wall radiotherapy may result in significant underestimation of the lung dose and overestimation of dose to the mediastinum, affecting plan optimization over volumes close to the lung-mediastinum interface, such as the lung or heart. Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
A Finnish national code of practice for reference dosimetry of radiation therapy
International Nuclear Information System (INIS)
Kosunen, A.; Sipilae, P.; Jaervinen, H.; Parkkinen, R.; Jokelainen, I.
2002-01-01
Full text: A national Code of Practice (CoP) for reference dosimetry of radiation therapy in Finland will be established during 2002 and will be implemented from the beginning of 2003. The CoP will cover dosimetry of the conventional radiotherapy modalities used in Finland i.e. external radiotherapy with megavoltage photon and electron beams, external radiotherapy with low energy kilovoltage X-ray beams and brachytherapy. The formalisms for external radiation beam dosimetry are those of TRS 389. For brachytherapy the formalism will follow the general guidelines of TECDOC-1274. The CoP will be prepared by the SSDL of STUK in close co-operation with the Finnish radiotherapy physicists. For external beam radiotherapy, the main objective of the national Code of Practice for radiation therapy dosimetry is to maintain the achieved good level of consistency of the dosimetry procedures in external beam radiotherapy as the 'absorbed dose to water' based approach of TRS 389 is implemented in Finland. In the CoP the dosimetry the procedures are described for the whole dosimetry chain starting from the calibration of the ionisation chambers at the SSDL of STUK and ending to the calibration of the beam monitor ionisation chamber of a linear accelerator. For brachytherapy dosimetry the aim is to fix the national practice for reference air kerma rate calibrations both for radioactive sources and for well-type ionisation chambers. Although the dosimetry procedures are described independently of the SSDL service, CoP makes use of the special features of the calibration service offered by the SSDL of STUK. For ionisation chambers used for photon dosimetry the calibration factors for the user measurement chain are given not only for the actual reference beam quality ( 60 Co) but also for a set of user beam qualities. Furthermore, SSDL of STUK offers calibration services for plane parallel ionisation chambers in an electron beam of a user linac. For brachytherapy SSDL of STUK has
As the thermoluminescent dosimetry can help in the quality control in radiotherapy
International Nuclear Information System (INIS)
Araujo, Anna Maria Campos de; Marin, Alfredo Viamonte; Viegas, Claudio C.B.; Souza, Roberto Salomon de; Alves, Victor Gabriel Leandro
2011-01-01
According to the international (International Atomic Energy Agency) and national (Agencia Nacional de Vigilancia Sanitaria- ANVISA) rules, the irradiators of any radiotherapy department should be periodical/y checked through a quality control external audit. In Brazil, where we have about 300 radiotherapy equipment, is very difficult to perform these audits on site with a acceptable frequency. For this reason, the Quality Service on Ionizing Radiations from the National Cancer Institute-INCA/Rio de Janeiro, developed and implemented postal systems to evaluate the main parameters of the radiotherapeutic equipment (Co-60, linear accelerators and high dose rate brachytherapy). All the postal systems developed are based on thermoluminescent dosimeters. The aim of this paper is to share the INCA experience in the use of TLD for dose evaluation and quality control measurements. Following the same philosophy, INCA developed also a postal system to evaluate the doses in mammography, since Brazil has 4000 equipment and performs about 8 millions of mammograms per year. A new experience is studying the OSL dosimeters to be used also for dose evaluation, including for in vivo dosimetry. (author)
Ramm, Daniel
2018-02-01
New clinical radiotherapy dosimetry systems need comprehensive demonstration of measurement quality. Practicality and reliability are other important aspects for clinical dosimeters. In this work the performance of an optical CT scanner for true 3D dosimetry is assessed using a radiochromic gel dosimeter. The fluid-less scanner utilised dual lasers to avoid the necessity for pre-irradiation scans and give greater robustness of image quality, enhancing practicality. Calibration methods using both cuvettes and reconstructed volumes were developed. Dosimetric accuracy was similar for dual and single wavelength measurements, except that cuvette calibration reliability was reduced for dual wavelength without pre-irradiation scanning. Detailed performance parameters were specified for the dosimetry system indicating the suitability for clinical use. The most significant limitations of the system were due to the gel dosimeter rather than the optical CT scanner. Quality assurance guidelines were developed to maintain dosimetry system performance in routine use.
Energy Technology Data Exchange (ETDEWEB)
Fiebich, Martin [Technische Hochschule Mittelhessen, Giessen (Germany). Inst. fuer Medizinische Physik und Strahlenschutz
2017-07-01
In the frame of physical dosimetry new dose units have been defined: the depth personal dose (equivalent dose in 10 mm depth) and the surface personal dose (equivalent dose in 0.07 mm depth). Physical dosimetry is applied for the determination of occupational radiation exposure, the radiation protected area control, the estimation of radiation exposure of patients during radiotherapy, for quality assurance and in research projects and optimization challenges. Developments have appeared with respect to punctual measuring chambers, eye lens dosimetry, OSL (optically stimulated luminescence) dosimetry, real-time dosimetry and Monte Carlo methods. New detection limits of about 1 micro Gy were reached.
In vivo dosimetric impact of breast tissue expanders on post-mastectomy radiotherapy
International Nuclear Information System (INIS)
Gee, Harriet E.; Bignell, Fiona; Odgers, David; Gill, Simran; Martin, Darren; Toohey, Joanne; Carroll, Susan
2016-01-01
Temporary tissue expanders with metallic ports for gradual saline injection are increasingly employed to facilitate breast reconstruction after post-mastectomy radiotherapy (PMRT). Treatment beams therefore pass through a high-density rare-earth magnet. Measurements ex vivo suggest attenuation of dose to the skin and chest wall at clinical risk of relapse. The purpose of the study was to quantify the resulting dose reduction in vivo, compared with treatment planning system (TPS). Sixteen patients receiving PMRT had in vivo dosimetry prospectively performed with ethics board approval. Port was located within the expanded chest wall using the planning CT scan. Strips of radiochromic film were laid on the skin surface underneath the bolus. To aid interpretation, ex vivo measurements were also performed, including comparison with TPS predictions. An average 7% reduction in dose to skin surface was measured in 15 of 16 patients. This was reproducibly located in the ‘shadow’ of the magnet, corresponding to each of the paths of the medial and lateral tangents. The average area was 1.07 cm2 (range 0.39 cm2 to 2.36 cm2). Ex vivo measurements confirmed attenuation of the beam in the shadow of the port. The surface area of the ‘cold-spot’ varied with angle of the beam relative to the metallic port. Dose attenuation in vivo differed from that predicted by the TPS. Dose is attenuated in the ‘shadow’ of the tissue expander port in patients receiving PMRT. This is likely to be clinically insignificant for most, but centres should undertake appropriate measurements before utilising TPS predictions.
The dosimetric control in radiotherapy
International Nuclear Information System (INIS)
Veres, A.
2009-01-01
The author first presents the thermoluminescent dosimetry method developed by the Equal-Estro Laboratory to control radiotherapy systems, according to which dosimeters are mailed by the radiotherapy centres to the laboratory, and then analyzed with respect to the level of dose bias. In a second part, he discusses the different techniques used for the dosimetric control of new radiotherapy methods (intensity-modulated radiation therapy, tomo-therapy) for which film dosimetry is applied. He also evokes the development of new phantoms and the development of a method for the dosimetric control of proton beams
Energy Technology Data Exchange (ETDEWEB)
Deman, P; Vautrin, M; Stupar, V; Barbier, E L; Elleaume, H; Esteve, F; Adam, J F, E-mail: adam@esrf.fr [INSERM, U836, BP 170, Grenoble Cedex 9, F-38042 (France)
2011-07-21
Monochromatic x-ray minibeam radiotherapy is a new radiosurgery approach based on arrays of submillimetric interlaced planar x-ray beams. The aim of this study was to characterize the dose distributions obtained with this new modality when being used for preclinical trials. Monte Carlo simulations were performed in water phantoms. Percentage depth-dose curves and dose profiles were computed for single incidences and interleaved incidences of 80 keV planar x-ray minibeam (0.6 x 5 mm) arrays. Peak to valley dose ratios were also computed at various depths for an increasing number of minibeams. 3D experimental polymer gel (nPAG) dosimetry measurements were performed using MRI devices designed for small animal imaging. These very high spatial resolution (50 {mu}m) dose maps were compared to the simulations. Preclinical minibeams dose distributions were fully characterized. Experimental dosimetry correlated well with Monte Carlo calculations (Student t-tests: p > 0.1). F98 tumor-bearing rats were also irradiated with interleaved minibeams (80 keV, prescribed dose: 25 Gy). This associated preclinical trial serves as a proof of principle of the technique. The mean survival time of irradiated glioma-bearing rats increased significantly, when compared to the untreated animals (59.6 {+-} 2.8 days versus 28.25 {+-} 0.75 days, p < 0.001).
Characterising an aluminium oxide dosimetry system.
Conheady, Clement F; Gagliardi, Frank M; Ackerly, Trevor
2015-09-01
In vivo dosimetry is recommended as a defence-in-depth strategy in radiotherapy treatments and is currently employed by clinics around the world. The characteristics of a new optically stimulated luminescence dosimetry system were investigated for the purpose of replacing an aging thermoluminescence dosimetry system for in vivo dosimetry. The stability of the system was not sufficient to satisfy commissioning requirements and therefore it has not been released into clinical service at this time.
Thwaites, David
2013-06-01
In this review of the accuracy required and achievable in radiotherapy dosimetry, older approaches and evidence-based estimates for 3DCRT have been reprised, summarising and drawing together the author's earlier evaluations where still relevant. Available evidence for IMRT uncertainties has been reviewed, selecting information from tolerances, QA, verification measurements, in vivo dosimetry and dose delivery audits, to consider whether achievable uncertainties increase or decrease for current advanced treatments and practice. Overall there is some evidence that they tend to increase, but that similar levels should be achievable. Thus it is concluded that those earlier estimates of achievable dosimetric accuracy are still applicable, despite the changes and advances in technology and techniques. The one exception is where there is significant lung involvement, where it is likely that uncertainties have now improved due to widespread use of more accurate heterogeneity models. Geometric uncertainties have improved with the wide availability of IGRT.
International Nuclear Information System (INIS)
Mendes, Bruno Melo
2017-01-01
The use of Ionizing radiation (IR) in medicine has increased considerably. The benefits generated by diagnostic and therapy techniques with IR are proven. Nevertheless, the risks arising from these uses should not be underestimated. Justification, a basic radiation protection, states that the benefits from exposures must outweigh detriment. The cancer induction is one of the detriment components. Thus, the study of the benefit/detriment ratio should take into account cancer incidence and mortality estimations resulting from a given diagnosis or therapy radiological technique. The risk of cancer induction depends on the absorbed doses in the irradiated organs and tissues. Thus, IR dosimetry is essential to evaluate the benefit/detriment ratio. The present work aims to perform computational dosimetric evaluations and estimations of cancer induction risk after ionizing radiation exposure. The investigated situations cover nuclear medicine, radiological contamination and radiotherapy fields. Computational dosimetry, with MCNPx Monte Carlo Code, was used as a tool to calculate the absorbed dose in the interest organs of the voxelized human models. The simulations were also used to obtain calibration factors and optimization of in vivo monitoring systems for internal contamination dosimetry. A breast radiotherapy (RT) standard protocol was simulated using the MCNPx code. The calculation of the radiation-induced cancer risk was adapted from the BEIR VII methodology for the Brazilian population. The absorbed doses used in the risk calculations were obtained through computational simulations of different exposure scenarios. During this work, two new computational phantoms, DM B RA and VW, were generated from tomographic images. Additional twelve voxelized phantoms, including the reference phantoms, RCP A M and RCP A F, and the child, baby, and fetus models were adapted to run on MCNP. Internal Dosimetry Protocols (IDP) for radiopharmaceuticals and for internal contamination
Evaluation of radiochromic films EBT3 for in-vivo dosimetry in radiotherapy treatments with photons
International Nuclear Information System (INIS)
Galvan de la C, O. O.; Rivera M, T.; Garcia G, O. A.; Larraga G, J. M.
2015-10-01
Full text: In-vivo dosimetry is a challenge in radiotherapy due to the measures are carried out in reference conditions outside; there is no balance of charged particle and beam consists of photons own and contamination electrons. Detectors that are useful for such measures should be sufficiently small and thin so they do not disturb the beam and do not alter the dose on target. In this paper the radiochromic films Gafchromic model EBT3 are evaluated as potential detectors for in-vivo dosimetry; measurements were carried out in solid water phantom on the surface, with films of dimensions 3 x 3 cm 2 . Irradiations were performed with a linear accelerator Novalis of 6 MV. Comparison between dose values found with a diode type Sfd detector (IBA dosimetry, Germany) and a diamond detector CVD (PTW-Freiburg) for 2 different sized of field (5 x 5 cm 2 and 10 x 10 cm 2 ) on the surface of a water phantom scanning was realized. The total spreading factor (Tsf) measured on surface was of 0.831 ± 4.6%; which is greater 12.9% than Tsf measured at a depth of maximum dose. This difference may be due to the contribution of scattered electrons to the beam exit. The measures must be corroborated with Monte Carlo simulations, which they will be validated on surface by the Abdel-Rahman [et al.] method; this mechanism will determine if the films are useful detectors for in-vivo dosimetry clinically. (Author)
Dosimetry for audit and clinical trials: challenges and requirements
International Nuclear Information System (INIS)
Kron, T; Haworth, A; Williams, I
2013-01-01
Many important dosimetry audit networks for radiotherapy have their roots in clinical trial quality assurance (QA). In both scenarios it is essential to test two issues: does the treatment plan conform with the clinical requirements and is the plan a reasonable representation of what is actually delivered to a patient throughout their course of treatment. Part of a sound quality program would be an external audit of these issues with verification of the equivalence of plan and treatment typically referred to as a dosimetry audit. The increasing complexity of radiotherapy planning and delivery makes audits challenging. While verification of absolute dose delivered at a reference point was the standard of external dosimetry audits two decades ago this is often deemed inadequate for verification of treatment approaches such as Intensity Modulated Radiation Therapy (IMRT) and Volumetric Modulated Arc Therapy (VMAT). As such, most dosimetry audit networks have successfully introduced more complex tests of dose delivery using anthropomorphic phantoms that can be imaged, planned and treated as a patient would. The new challenge is to adapt this approach to ever more diversified radiotherapy procedures with image guided/adaptive radiotherapy, motion management and brachytherapy being the focus of current research.
Independent dose calculation of the Tps Iplan in radiotherapy conformed with MLC
International Nuclear Information System (INIS)
Adrada, A.; Tello, Z.; Medina, L.; Garrigo, E.; Venencia, D.
2014-08-01
The systems utilization of independent dose calculation in three dimensional-Conformal Radiation Therapy (3D-Crt) treatments allows a direct verification of the treatments times. The utilization of these systems allows diminishing the probability of errors occurrence generated by the treatment planning system (Tps), allowing a detailed analysis of the dose to delivering and review of the normalization point (Np) or prescription. The independent dose calculation is realized across the knowledge of dosimetric parameters of the treatment machine and particular characteristics of every individual field. The aim of this work is develops a calculation system of punctual doses for isocentric fields conformed with multi-leaf collimation systems (MLC), where the dose calculation is in conformity with the suggested ones by ICRU Report No. 42, 1987. Calculation software was realized in C ++ under a free platform of programming (Code::Blocks). The system uses files in format Rtp, exported from the Tps to systems of record and verification (Lantis). This file contains detailed information of the dose, Um, position of the MLC sheets and collimators for every field of treatment. The size of equivalent field is obtained from the positions of every sheet; the effective depth of calculation can be introduced from the dosimetric report of the Tps or automatically from the DFS of the field. The 3D coordinates of the isocenter and the Np for the treatment plan must be introduced manually. From this information the system looks the dosimetric parameters and calculates the Um. The calculations were realized in two accelerators a NOVALIS Tx (Varian) with 120 sheets of high definition (hd-MLC) and a PRIMUS Optifocus (Siemens) with 82 sheets. 705 patients were analyzed for a total of 1082, in plans made for both equipment s, the average uncertainty with regard to the calculation of the Tps is-0.43% ± 2.42% in a range between [-7.90 %, 7.50 %]. The major uncertainty was in Np near of the
Okamoto, Hiroyuki; Minemura, Toshiyuki; Nakamura, Mitsuhiro; Mizuno, Hideyuki; Tohyama, Naoki; Nishio, Teiji; Wakita, Akihisa; Nakamura, Satoshi; Nishioka, Shie; Iijima, Kotaro; Fujiyama, Daisuke; Itami, Jun; Nishimura, Yasumasa
2018-04-01
We developed an efficient postal audit system to independently assess the delivered dose using radiophotoluminescent glass dosimeters (RPLDs) and the positional differences of fields using EBT3 film at the axial plane for intensity-modulated radiotherapy (IMRT). The audit phantom had a C-shaped target structure as a planning target volume (PTV) with four measurement points for the RPLDs and a cylindrical structure as the organ at risk (OAR) for one measurement point. The phantoms were sent to 24 institutions. Point dose measurements with a 0.6 cm 3 PTW farmer chamber were also performed to justify glass dosimetry in IMRT. The measured dose with the RPLDs was compared to the calculated dose in the institution's treatment planning system (TPS). The mean ± 1.96σ of the ratio of the measured dose with the RPLDs to the farmer chamber was 0.997 ± 0.024 with no significant difference (p = .175). The investigations demonstrated that glass dosimetry was reliable with a high measurement accuracy comparable to the chamber. The mean ± 1.96σ for the dose differences with a reference of the TPS dose for the PTV and the OAR was 0.1 ± 2.5% and -2.1 ± 17.8%, respectively. The mean ± 1.96σ for the right-left and the anterior-posterior direction was -0.9 ± 2.8 and 0.5 ± 1.4 mm, respectively. This study is the first report to justify glass dosimetry for implementation in IMRT audit in Japan. We demonstrate that our postal audit system has high accuracy with a high-level criterion of 3%/3 mm. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Sharpe, P.H.G.; Sephton, J.P.
1999-01-01
In this paper we describe the work that has been carried out at National Physical Laboratory (NPL) to develop a mailed alanine reference dosimetry service for radiotherapy dose levels. The service is based on alanine/paraffin wax dosimeters produced at NPL. Using a data analysis technique based on spectrum fitting, it has been possible to achieve a precision of dose measurement better than ±0.05 Gy (1σ). A phantom set has been developed for use in high energy photon beams, which enables simultaneous irradiation of alanine dosimeters and ionisation chambers in a well defined geometry. Studies in photon beams of energies between 60 Co and 20 MeV have shown no significant energy dependence (<1%) for alanine relative to dose determination using a graphite calorimeter. Work is underway to extend the service to electron beams, and preliminary results are presented on the direct calibration of alanine in electron beams using a graphite calorimeter. (author)
Energy Technology Data Exchange (ETDEWEB)
Frelin, A M
2006-10-15
This thesis deals with the development of a new dosimetry device for the control of radiotherapy beams. This device is composed of a plane plastic scintillator which is set within a polystyrene phantom. When the 'DosiMap' is irradiated, light is produced. This light is composed of scintillation and Cerenkov radiation, and is accurately measured by a C.C.D. camera. The analysis of the light distribution enables us to deduce the dose distribution in the scintillator plan. This device has many advantages such as tissue equivalence, a good spatial resolution, and a linear response with regard to energy. It also provides immediate measurements, and as a consequence, it is a very adapted tool for clinical use. After the introduction about the basic notions of radiotherapy, the different steps of the 'DosiMap' development are exposed in this thesis. In a first time, plastic scintillators have been tested to determine the best one for this application. Then, the deconvolution of scintillation and Cerenkov radiation have been studied, because we only use scintillation to calculate the dose distribution. The camera being in the irradiation room, a lead shield has also been developed to protect the C.C.D. detector from scattered radiations. Finally, the dose calibration and the dose response of 'DosiMap' are exposed. All this work made feasible the measurement of dose distributions with a precision which turns out to be better than 2% for homogeneous photon beams. Excellent results were also obtained when modulated intensity beams are used. (author)
Energy Technology Data Exchange (ETDEWEB)
Frelin, A.M
2006-10-15
This thesis deals with the development of a new dosimetry device for the control of radiotherapy beams. This device is composed of a plane plastic scintillator which is set within a polystyrene phantom. When the 'DosiMap' is irradiated, light is produced. This light is composed of scintillation and Cerenkov radiation, and is accurately measured by a C.C.D. camera. The analysis of the light distribution enables us to deduce the dose distribution in the scintillator plan. This device has many advantages such as tissue equivalence, a good spatial resolution, and a linear response with regard to energy. It also provides immediate measurements, and as a consequence, it is a very adapted tool for clinical use. After the introduction about the basic notions of radiotherapy, the different steps of the 'DosiMap' development are exposed in this thesis. In a first time, plastic scintillators have been tested to determine the best one for this application. Then, the deconvolution of scintillation and Cerenkov radiation have been studied, because we only use scintillation to calculate the dose distribution. The camera being in the irradiation room, a lead shield has also been developed to protect the C.C.D. detector from scattered radiations. Finally, the dose calibration and the dose response of 'DosiMap' are exposed. All this work made feasible the measurement of dose distributions with a precision which turns out to be better than 2% for homogeneous photon beams. Excellent results were also obtained when modulated intensity beams are used. (author)
Calibration of helical tomotherapy machine using EPR/alanine dosimetry.
Perichon, Nicolas; Garcia, Tristan; François, Pascal; Lourenço, Valérie; Lesven, Caroline; Bordy, Jean-Marc
2011-03-01
Current codes of practice for clinical reference dosimetry of high-energy photon beams in conventional radiotherapy recommend using a 10 x 10 cm2 square field, with the detector at a reference depth of 10 cm in water and 100 cm source to surface distance (SSD) (AAPM TG-51) or 100 cm source-to-axis distance (SAD) (IAEA TRS-398). However, the maximum field size of a helical tomotherapy (HT) machine is 40 x 5 cm2 defined at 85 cm SAD. These nonstandard conditions prevent a direct implementation of these protocols. The purpose of this study is twofold: To check the absorbed dose in water and dose rate calibration of a tomotherapy unit as well as the accuracy of the tomotherapy treatment planning system (TPS) calculations for a specific test case. Both topics are based on the use of electron paramagnetic resonance (EPR) using alanine as transfer dosimeter between the Laboratoire National Henri Becquerel (LNHB) 60Co-gamma-ray reference beam and the Institut Curie's HT beam. Irradiations performed in the LNHB reference 60Co-gamma-ray beam allowed setting up the calibration method, which was then implemented and tested at the LNHB 6 MV linac x-ray beam, resulting in a deviation of 1.6% (at a 1% standard uncertainty) relative to the reference value determined with the standard IAEA TRS-398 protocol. HT beam dose rate estimation shows a difference of 2% with the value stated by the manufacturer at a 2% standard uncertainty. A 4% deviation between measured dose and the calculation from the tomotherapy TPS was found. The latter was originated by an inadequate representation of the phantom CT-scan values and, consequently, mass densities within the phantom. This difference has been explained by the mass density values given by the CT-scan and used by the TPS which were not the true ones. Once corrected using Monte Carlo N-Particle simulations to validate the accuracy of this process, the difference between corrected TPS calculations and alanine measured dose values was then
Recent progress in application of JAERI alanine/ESR dosimetry system
International Nuclear Information System (INIS)
Kojima, T.
1995-01-01
Feasibility studies of application of JAERI alanine/ESR dosimetry system were performed on radiotherapy level dosimetry, low dose-rate dosimetry for residual life estimation of cable insulators used in nuclear power facilities, and dose monitoring for electron processing. (author)
3D dosimetry on Ru-106 plaque for ocular melanoma treatments
International Nuclear Information System (INIS)
Gueli, A.M.; Mannino, G.; Troja, S.O.; Asero, G.; Burrafato, G.; De Vincolis, R.; Greco, C.; Longhitano, N.; Occhipinti, A.
2011-01-01
For a few years at the Azienda Ospedaliero - Universitaria “Policlinico - Vittorio Emanuele” of Catania (Italy), ocular melanoma brachytherapic treatments with Ru-106 plaques have been made. This type of treatment is planned using the specific Treatment Planning System (TPS) BEBIG “Plaque Simulator” software that simulates the delivered dose distribution from the source used on the eye tissue. Improving dosimetry for ophthalmic therapeutic applications is worthwhile. Accurate dose measurements require detectors of adequate dimensions with respect to small distances involved. The main objective of the work is the improvement of dosimetry accuracy with a high sensitivity and spatial resolution system such as EBT2 Gafchromic ® film. The relative depth dose, the 2D and 3D distributions, the source uniformity and asymmetry were obtained using custom tissue equivalent phantom. Experimental results were compared with manufacturer’s calibration certificate data, TPS calculated values and Monte Carlo simulation results.
A fiber-dosimetry method based on OSL from Al2O3:C for radiotherapy applications
International Nuclear Information System (INIS)
Gaza, R.; McKeever, S.W.S.; Akselrod, M.S.; Akselrod, A.; Underwood, T.; Yoder, C.; Andersen, C.E.; Aznar, M.C.; Marckmann, C.J.; Boetter-Jensen, L.
2004-01-01
We describe a high-sensitivity, fiber-optic dosimetry system based on optically stimulated luminescence (OSL) and radioluminescence from Al 2 O 3 :C single-crystal fibers (detectors). The detectors are coupled to a fiber optic delivery system and OSL from the detector is stimulated via the optical fiber cable using light from a Nd:YAG laser. The OSL is guided back along the same fiber and is detected by a photomultiplier tube. The Al 2 O 3 :C detectors are small and demonstrate high sensitivity with a large signal-to-noise ratio. We describe two modes of operation of the system and discuss algorithms that provide accurate estimation of dose rate and integrated dose in near real time. The system is free from magnetic and electrical interference, and is designed for use in several forms of radiotherapy, including in vitro brachytherapy source calibration, and in vivo dosimetry during patient treatment
Venkatapathy, Ethiraj; Ellerby, D.; Gage, P.; Gasch, M.; Hwang, H.; Prabhu, D.; Stackpoole, M.; Wercinski, Paul
2018-01-01
This invited talk will provide an assessment of the TPS needs for Outer Planet In-situ missions to destinations with atmosphere. The talk will outline the drivers for TPS from destination, science, mission architecture and entry environment. An assessment of the readiness of the TPS, both currently available and under development, for Saturn, Titan, Uranus and Neptune are provided. The challenges related to sustainability of the TPS for future missions are discussed.
C.T. scan based dosimetry in treating carcinoma of oral tongue
International Nuclear Information System (INIS)
Sudarshan, G.; Ranganathan, Vanisehree
1999-01-01
It is a well established norm that a combination of external radiation and iridium implant in early stage squamous cell carcinoma (SCC) of oral tongue gives good results. We have treated 10 consecutive patients of SCC of anterior 2/3 of tongue staged T1-2 NO by giving 4000 cGy external radiation and 3000 cGy boost with iridium-192 implant. Traditionally, orthogonal radiographs have been taken to determine the spatial distribution of sources. As we do not have a simulator, we have taken 2-4 C.T. scan images perpendicular to the axis of implant. By using this cross-sectional information, we identified the source points and a basal dose rate was calculated manually by following the geometric principles of Paris system as our T.P.S. did not have the required software. Clinically, 9 out of the 10 patients are in remission (N.E.D. = No evidence of disease) at 18 months follow-up. Our aim of this presentation is to compare manual dosimetry with T.P.S. generated dosimetry and to show that manual dosimetry is also dependable. (author)
International Nuclear Information System (INIS)
Pelagade, S.M.; Bopche, T.T.; Namitha, K.; Munshi, M.; Bhola, S.; Sharma, H.; Patel, B.K.; Vyas, R.K.
2008-01-01
The outcome of stereotactic radiotherapy (SRT) and stereotactic radiosurgery (SRS) in both benign and malignant tumors within the cranial region highly depends on precision in dosimetry, dose delivery and the accuracy assessment of stereotaxy associated with the unit. The frames BRW (Brown-Roberts-Wells) and GTC (Gill- Thomas-Cosman) can facilitate accurate patient positioning as well as precise targeting of tumours. The implementation of this technique may result in a significant benefit as compared to conventional therapy. As the target localization accuracy is improved, the demand for treatment planning accuracy of a TPS is also increased. The accuracy of stereotactic X Knife treatment planning system has two components to verify: (i) the dose delivery verification and the accuracy assessment of stereotaxy; (ii) to ensure that the Cartesian coordinate system associated is well established within the TPS for accurate determination of a target position. Both dose delivery verification and target positional accuracy affect dose delivery accuracy to a defined target. Hence there is a need to verify these two components in quality assurance protocol. The main intention of this paper is to present our dose delivery verification procedure using cylindrical wax phantom and accuracy assessment (target position) of stereotaxy using Geometric Phantom on Elekta's Precise linear accelerator for stereotactic installation
The dosimetry programme of the IAEA
International Nuclear Information System (INIS)
1987-01-01
Describes the activities of the IAEA's Dosimetry Laboratory which provides calibration and comparison services for secondary standard dosimetry laboratories (SSDLs) of Member States. In addition, a joint IAEA/WHO postal dosimetry service has been established for radiotherapy centers. The International Measurement System and the calibration ''chain'' from measurement standard instruments of the International Bureau of Weights and Measurements (BIPM) through the primary and secondary standards to the dosimeters of the users are presented as well
Alanine dosimetry for clinical applications. Proceedings
International Nuclear Information System (INIS)
Anton, M.
2006-05-01
The following topics are dealt with: Therapy level alanine dosimetry at the UK Nationational Physical Laboratory, alanine as a precision validation tool for reference dosimetry, composition of alanine pellet dosimeters, the angular dependence of the alanine ESR spectrum, the CIAE alanine dosimeter for radiotherapy level, a correction for temporal evolution effects in alanine dosimetry, next-generation services foe e-traceability to ionization radiation national standards, establishing e-traceability to HIST high-dose measurement standards, alanine dosimetry of dose delivery from clinical accelerators, the e-scan alanine dosimeter reader, alanine dosimetry at ISS, verification of the integral delivered dose for IMRT treatment in the head and neck region with ESR/alanine dosimetry, alanine dosimetry in helical tomotherapy beams, ESR dosimetry research and development at the University of Palermo, lithium formate as a low-dose EPR radiation dosimeter, sensitivity enhancement of alanine/EPR dosimetry. (HSI)
Thermoluminescence in medical dosimetry
International Nuclear Information System (INIS)
Rivera, T.
2011-10-01
The dosimetry by thermoluminescence (Tl) is applied in the entire world for the dosimetry of ionizing radiations specially to personal and medical dosimetry. This dosimetry method has been very interesting for measures in vivo because the Tl dosimeters have the advantage of being very sensitive in a very small volume and they are also equivalent to tissue and they do not need additional accessories (for example, cable, electrometer, etc.) The main characteristics of the diverse Tl materials to be used in the radiation measures and practical applications are: the Tl curve, the share homogeneity, the signal stability after the irradiation, precision and exactitude, the response in function with the dose and the energy influence. In this work a brief summary of the advances of the radiations dosimetry is presented by means of the thermally stimulated luminescence and its application to the dosimetry in radiotherapy. (Author)
Energy Technology Data Exchange (ETDEWEB)
Na, Y; Black, P; Wuu, C [Columbia University, New York, NY (United States); Adamovics, J [Department of Chemistry and Biology, Rider University, Skillman, NJ (United States)
2016-06-15
Purpose: With an increasing use of small field size and high dose rate irradiation in the advances of radiotherapy techniques, such as stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery (SRS), an in-depth quality assurance (QA) system is required. The purpose of this study is to investigate a high resolution optical CT-based 3D radiochromic dosimetry system for SBRT with intensity modulated radiotherapy (IMRT) and flattening filter free (FFF) volumetric modulated arc therapy (VMAT). Methods: Cylindrical PRESAGE radiochromic dosimeters of 10cm height and 11cm diameter were used to validate SBRT. Four external landmarks were placed on the surface of each dosimeter to define the isocenter of target. SBRT plans were delivered using a Varian TrueBeam™ linear accelerator (LINAC). Three validation plans, SBRT with IMRT (6MV 600MU/min), FFF-VMAT (10MV 2400MU/min), and mixed FFF-VMAT (6MV 1400MU/min, 10MV 2400MU/min), were delivered to the PRESAGE dosimeters. Each irradiated PRESAGE dosimeter was scanned using a single laser beam optical CT scanner and reconstructed with a 1mm × 1mm high spatial resolution. The comparison of measured dose distributions of irradiated PRESAGE dosimeters to those calculated by Pinnacle{sup 3} treatment planning system (TPS) were performed with a 10% dose threshold, 3% dose difference (DD), and 3mm distance-to-agreement (DTA) Gamma criteria. Results: The average pass rates for the gamma comparisons between PRESAGE and Pinnacle{sup 3} in the transverse, sagittal, coronal planes were 94.6%, 95.9%, and 96.4% for SBRT with IMRT, FFF-VMAT, and mixed FFF-VMAT plans, respectively. A good agreement of the isodose distributions of those comparisons were shown at the isodose lines 50%, 70%, 80%, 90% and 98%. Conclusion: This study demonstrates the feasibility of the high resolution optical CT-based 3D radiochromic dosimetry system for validation of SBRT with IMRT and FFF-VMAT. This dosimetry system offers higher precision QA with 3D
Energy Technology Data Exchange (ETDEWEB)
Mirabel, X.; Horn, S.; Le Tinier, F.; Attar, M.; Dewas, S.; Lacornerie, T.; Nickers, P.; Sarrazin, T.; Lartigau, E. [Centre Oscar-Lambret, 59 - Lille (France)
2009-10-15
The generalisation of the three dimensional conformal radiotherapy, then the conformal radiotherapy with intensity modulation, the receipt of a dosimetry scanner, two tomo-therapy devices and a cyberknife modified deeply our practices. The delineation of every organ at risk and the prescription of constraints to organs at risk became systematic. The new technologies by their possibilities in term of accuracy, conformity and tracking lead us to choose new therapy indications in situations where the control of dose to organs at risk is particularly crucial (hypo fractionated intra and extra cranial stereotaxic). This context make us feel the necessity to use a data base of constraints to organs at risk, for the classic fractionation and the hypo fractionation. An array containing all the data has been published as posters, it is displayed in large format in the work area for doctors in the area of simulation and data acquisition as well as dosimetry. (N.C.)
Implementation of MRI gel dosimetry in radiation therapy
International Nuclear Information System (INIS)
Baeck, S.Aa.J.
1998-12-01
Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification
Implementation of MRI gel dosimetry in radiation therapy
Energy Technology Data Exchange (ETDEWEB)
Baeck, S.Aa.J
1998-12-01
Gel dosimetry was used together with magnetic resonance imaging (MRI) to measure three-dimensional absorbed dose distributions in radiation therapy. Two different dosimeters were studied: ferrous- and monomer gel, based on the principles of radiation-induced oxidation and polymerisation, respectively. Single clinical electron and photon beams were evaluated and gel dose distributions were mainly within 2% of conventional detector results. The ferrous-gel was also used for clinical proton beams. A decrease in signal per absorbed dose was found close to the end of the range of the protons (15-20%). This effect was explained as a linear energy transfer dependence, further supported with Monte Carlo simulations. A method for analysing and comparing data from treatment planning system (TPS) and gel measurements was developed. The method enables a new pixel by pixel evaluation, isodose comparison and dose volume histogram verification. Two standard clinical radiation therapy procedures were examined using the developed TPS verification method. The treatment regimes included several beams of different radiation qualities. The TPS calculated data were in very good agreement with the dose distribution measured by the ferrous-gel. However, in a beam abutment region, larger dose difference was found. Beam adjustment errors and a minor TPS underestimation of the lateral scatter contribution outside the primary electron beam may explain the discrepancy. The overall uncertainty in the ferrous-gel dose determination was considerably reduced using an optimised MRI acquisition protocol and a new MRI scanner. The relative dose uncertainty was found to be better than 3.3% for all dose levels (95% confidence level). Using the method developed for comparing measured gel data with calculated treatment plans, the gel dosimetry method was proven to be a useful tool for radiation treatment planning verification 103 refs, 20 figs, 6 tabs
DEFF Research Database (Denmark)
Hansen, Anders T; Hansen, Søren B; Petersen, Jørgen B
2007-01-01
of absorbed dose per gram of silver. This demonstrates that it is possible to derive absorbed doses from the radioactivity induced in silver by radiation when measured with the PET scanner. Even though the physical basis for this method is found to be sound, its application, for instance to perform quality......The possible use of silver as a material for in vivo dosimetry in radiotherapy was investigated. The investigation was carried out using a positron emission tomography (PET) scanner, two clinical accelerators and a phantom with silver implants. The phantom was irradiated several times to doses...
The New Zealand audit of radiotherapy dosimetry: Practical considerations and results
International Nuclear Information System (INIS)
Smyth, V.G.; Laban, J.A.
2002-01-01
The New Zealand Radiation Protection Regulations 1982 state that the dose delivered to a radiotherapy patient must be within ±5% of the prescribed dose. Following the overdose of 153 patients because of an error in dosimetry at Royal Devon and Exeter Hospital, UK, in 1988 it was decided to audit compliance with this routinely. Since 1991 every high-energy beam in NZ used for teletherapy has been independently measured every two years by staff from NRL. Since 1997 all kV x-ray beams have been measured as well. The measurements follow the dosimetry protocol TRS-277. A Sr-90 check is taken at each site to verify stability of the measurement system. Agreement within 0.5% is accepted. The SSD on a linear accelerator is set using the optical distance indicator after checking it against a mechanical front pointer. Recombination corrections are measured on each linear accelerator beam and polarity corrections as well in the case of electron beams. The results for high-energy beams have been reassuring both to the regulators and to the physicists who appreciate the independent check. The only disagreements significantly greater than 2% have caused by the use of a cylindrical chamber on a 4MV electron beam by a hospital, and confusion between SSD and isocentric set-up. When we repeated the measurement using the same set-up as the hospital the difference was resolved
MO-B-BRB-04: 3D Dosimetry in End-To-End Dosimetry QA
Energy Technology Data Exchange (ETDEWEB)
Ibbott, G. [UT MD Anderson Cancer Center (United States)
2016-06-15
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
International Nuclear Information System (INIS)
Mirabel, X.; Horn, S.; Le Tinier, F.; Attar, M.; Dewas, S.; Lacornerie, T.; Nickers, P.; Sarrazin, T.; Lartigau, E.
2009-01-01
The generalisation of the three dimensional conformal radiotherapy, then the conformal radiotherapy with intensity modulation, the receipt of a dosimetry scanner, two tomo-therapy devices and a cyberknife modified deeply our practices. The delineation of every organ at risk and the prescription of constraints to organs at risk became systematic. The new technologies by their possibilities in term of accuracy, conformity and tracking lead us to choose new therapy indications in situations where the control of dose to organs at risk is particularly crucial (hypo fractionated intra and extra cranial stereotaxic). This context make us feel the necessity to use a data base of constraints to organs at risk, for the classic fractionation and the hypo fractionation. An array containing all the data has been published as posters, it is displayed in large format in the work area for doctors in the area of simulation and data acquisition as well as dosimetry. (N.C.)
SU-F-T-17: A Feasibility Study for the Transit Dosimetry with a Glass Dosimeter in Brachytherapy
Energy Technology Data Exchange (ETDEWEB)
Moon, S; Yoon, M [Korea University, Seoul (Korea, Republic of); Chung, W; Chung, M; Kim, D [Kyung Hee University Hospital at Gangdong, Gangdonggu, Seoul (Korea, Republic of)
2016-06-15
Purpose: Confirming the dose delivered to a patient is important to make sure the treatment quality and safety of the radiotherapy. Measuring a transit dose of the patient during the radiotherapy could be an interesting way to confirm the patient dose. In this study, we evaluated the feasibility of the transit dosimetry with a glass dosimeter in brachytherapy. Methods: We made a phantom that inserted the glass dosimeters and placed under patient lying on a couch for cervix cancer brachytherapy. The 18 glass dosimeters were placed in the phantom arranged 6 per row. A point putting 1cm vertically from the source was prescribed as 500.00 cGy. Solid phantoms of 0, 2, 4, 6, 8, 10 cm were placed between the source and the glass dosimeter. The transit dose was measured each thickness using the glass dosimeters and compared with a treatment planning system (TPS). Results: When the transit dose was smaller than 10 cGy, the average of the differences between measured values and calculated values by TPS was 0.50 cGy and the standard deviation was 0.69 cGy. If the transit dose was smaller than 100 cGy, the average of the error was 1.67 ± 4.01 cGy. The error to a point near the prescription point was −14.02 cGy per 500.00 cGy of the prescription dose. Conclusion: The distances from the sources to skin of the patient generally are within 10 cm for cervix cancer cases in brachytherapy. The results of this preliminary study showed the probability of the glass dosimeter as the transit dosimeter in brachytherapy.
Development of DosiMap: dosimetry device for radiotherapy quality assurance
International Nuclear Information System (INIS)
Frelin, A.M.
2006-10-01
This thesis deals with the development of a new dosimetry device for the control of radiotherapy beams. This device is composed of a plane plastic scintillator which is set within a polystyrene phantom. When the 'DosiMap' is irradiated, light is produced. This light is composed of scintillation and Cerenkov radiation, and is accurately measured by a C.C.D. camera. The analysis of the light distribution enables us to deduce the dose distribution in the scintillator plan. This device has many advantages such as tissue equivalence, a good spatial resolution, and a linear response with regard to energy. It also provides immediate measurements, and as a consequence, it is a very adapted tool for clinical use. After the introduction about the basic notions of radiotherapy, the different steps of the 'DosiMap' development are exposed in this thesis. In a first time, plastic scintillators have been tested to determine the best one for this application. Then, the deconvolution of scintillation and Cerenkov radiation have been studied, because we only use scintillation to calculate the dose distribution. The camera being in the irradiation room, a lead shield has also been developed to protect the C.C.D. detector from scattered radiations. Finally, the dose calibration and the dose response of 'DosiMap' are exposed. All this work made feasible the measurement of dose distributions with a precision which turns out to be better than 2% for homogeneous photon beams. Excellent results were also obtained when modulated intensity beams are used. (author)
Clinical application of in vivo dosimetry for external telecobalt machine
International Nuclear Information System (INIS)
Mohammed, H. H. M.
2011-01-01
In external beam radiotherapy quality assurance is carried out on the individual components of treatment chain. The patient simulating device, planning system and treatment machine are tested regularly according to set protocols developed by national and international organizations. Even thought these individual systems are not tested for errors which can be made in the transfer between the systems. The best quality assurance for the treatment planning chain. In vivo dosimetry is used as a quality assurance tool for verifying dosimetry as either the entrance or exit surface of the patient undergoing external beam radiotherapy. It is a proven reliable method of checking overall treatment accuracy, allowing verification of dosimetry and dose calculation as well as patient treatment setup. Accurate in vivo dosimetry is carried out if diodes and thermoluminescence dosimeters (TLDs). the main detector types in use for in vivo dosimetry, are carefully calibrated and the factors influencing their sensitivity are taken into account. The aim of this study was to verify the response of TLDs type (LiF: Mg, Cu, p) use in radiotherapy, to establish calibration procedure for TLDs and to evaluate entrance dose obtained by the treatment planning system with measured dose using thermoluminescence detectors. Calibration of TLDs was done using Cobalt-60 teletherapy machine, linearity and calibration factors were determined. Measurements were performed in random phantom for breast irradiation (for the breast irradiation ( For the breast irradiation technique considered, wedge field was used). All TLDs were processed and analyzed at RICK. In vivo dosimetry represents a technique that has been widely employed to evaluate the dose to the patient mainly in radiotherapy. Thermoluminescent dosimeters are considered the gold stander for in vivo dosimetry and do not require cables for measurements which makes them ideal for mail based studies and have no dose rate or temperature dependence
Tissue equivalence in neutron dosimetry
International Nuclear Information System (INIS)
Nutton, D.H.; Harris, S.J.
1980-01-01
A brief review is presented of the essential features of neutron tissue equivalence for radiotherapy and gives the results of a computation of relative absorbed dose for 14 MeV neutrons, using various tissue models. It is concluded that for the Bragg-Gray equation for ionometric dosimetry it is not sufficient to define the value of W to high accuracy and that it is essential that, for dosimetric measurements to be applicable to real body tissue to an accuracy of better than several per cent, a correction to the total absorbed dose must be made according to the test and tissue atomic composition, although variations in patient anatomy and other radiotherapy parameters will often limit the benefits of such detailed dosimetry. (U.K.)
International Nuclear Information System (INIS)
Bondiau, P.Y.; Thariat, J.; Benezery, K.; Herault, J.; Dalmasso, C.; Marcie, S.; Malandain, G.
2007-01-01
The stereotaxic radiotherapy robotized by 'Cyberknife fourth generation' allows a dosimetric optimization with a high conformity index on the tumor and radiation doses limited on organs at risk. A cerebral automatic anatomic segmentation atlas of organs at risk are used in routine in three dimensions. This study evaluated the superiority of the stereotaxic radiotherapy in comparison with the three dimensional conformal radiotherapy on the preservation of organs at risk in regard of the delivered dose to tumors justifying an accelerated hypo fractionation and a dose escalation. This automatic segmentation atlas should allow to establish correlations between anatomy and cerebral dosimetry; This atlas allows to underline the dosimetry optimization by stereotaxic radiotherapy robotized for organs at risk. (N.C.)
Monte Carlo simulations to replace film dosimetry in IMRT verification
International Nuclear Information System (INIS)
Goetzfried, Thomas; Trautwein, Marius; Koelbi, Oliver; Bogner, Ludwig; Rickhey, Mark
2011-01-01
Patient-specific verification of intensity-modulated radiation therapy (IMRT) plans can be done by dosimetric measurements or by independent dose or monitor unit calculations. The aim of this study was the clinical evaluation of IMRT verification based on a fast Monte Carlo (MC) program with regard to possible benefits compared to commonly used film dosimetry. 25 head-and-neck IMRT plans were recalculated by a pencil beam based treatment planning system (TPS) using an appropriate quality assurance (QA) phantom. All plans were verified both by film and diode dosimetry and compared to MC simulations. The irradiated films, the results of diode measurements and the computed dose distributions were evaluated, and the data were compared on the basis of gamma maps and dose-difference histograms. Average deviations in the high-dose region between diode measurements and point dose calculations performed with the TPS and MC program were 0.7 ± 2.7% and 1.2 ± 3.1%, respectively. For film measurements, the mean gamma values with 3% dose difference and 3 mm distance-to-agreement were 0.74 ± 0.28 (TPS as reference) with dose deviations up to 10%. Corresponding values were significantly reduced to 0.34 ± 0.09 for MC dose calculation. The total time needed for both verification procedures is comparable, however, by far less labor intensive in the case of MC simulations. The presented study showed that independent dose calculation verification of IMRT plans with a fast MC program has the potential to eclipse film dosimetry more and more in the near future. Thus, the linac-specific QA part will necessarily become more important. In combination with MC simulations and due to the simple set-up, point-dose measurements for dosimetric plausibility checks are recommended at least in the IMRT introduction phase. (orig.)
QA programme in external radiotherapy in Romania - status and perspective
International Nuclear Information System (INIS)
Dumitrescu, A.; Milu, C.
2008-01-01
Full text: Recognizing the importance of quality assurance in radiotherapy and the need to make access to radiation standards traceable to the international measurement system for every radiotherapy center, the Romanian national secondary standard dosimetry laboratory (SSDL) has started in 1999 - together with IAEA - a national quality audit programme in all the centers for external radiotherapy from Romania. At present, there are 17 radiotherapy centers in Romania, and a total of 19 teletherapy units and 4 LINCs. The programme has 3 phases: the first phase was to organize a survey in all radiotherapy centers, to collect general information on their radio therapists, medical physicists, type of equipment, dosimeters, etc. Following the survey, a quality assurance network was set up, and on-site dosimetry reviews were arranged according to a suitable timetable. The second phase consisted in performing the reference dosimetry and the calibration of the equipment. Then, a quality audit system based on mailed TLDs has been applied to all radiation beams produced by cobalt-60 therapy units and medical accelerators, in order to identify discrepancies in dosimetry larger than ± 3%. At the same time, the beam calibration performed by the SSDLs was verified. The results of the first survey were analyzed, and corrective actions were taken. A second survey was then organized, based on the mailed TLDs. This paper presents in detail the entire QA programme, its results, and the actions that are to be taken in order to improve the accuracy and consistency of the dosimetry in clinical radiotherapy in Romania. (author)
Use of a modified natural-rubber phantom for radiotherapy dosimetry measurements
International Nuclear Information System (INIS)
Bradley, D.A.; Ng, K.-H.; Aziz, Y.B.
1988-01-01
The utility of a phantom material, based on SMR(L) [Standard Malaysian Rubber] grade natural rubber and a formulation used for the proprietary rubber phantom-material, Temex, has been examined for the 1-MeV photon-energy range using γ radiation from a 60 Co source. Measurement has also been performed with 60-keV photons using the radionuclide 241 Am. At photon-therapy energy levels the measured response, when compared with tabulated central-axis percentage depth doses for defined measuring conditions, produces everywhere (in the range 1-19 cm depth) better than 2% deviation. The favourable measured response characteristics combined with the ease of processing and casting the phantom material provide the basis for useful radiotherapy machine calibration and anthropomorphic dosimetry measurements. The measured mass-attenuation coefficient, at 60 keV, of 0.204 cm 2 g -1 (± 3%) is in close agreement with tabulated values for water (0.2055 cm 2 g -1 ). (author)
SU-E-T-153: Detector-Grade CVD Diamond for Radiotherapy Dosimetry.
Lansley, S; Betzel, G; McKay, D; Meyer, J
2012-06-01
To evaluate the use of commercially available detector-grade synthetic diamond films made via chemical vapor deposition (CVD) as x- ray detectors for radiotherapy dosimetry. A detector was fabricated using high-quality single crystal CVD diamond films (0.5 × 3 × 3 mm̂3) with 0.4 mm̂3 sensitive volumes, which were encapsulated with PMMA. The detector was placed in a (30 × 30 × 30 cm̂3) PTW water phantom. Six- and ten-MV photons from an Elekta Synergy linac were measured using an SSD of 90 cm and typically a 10-cm phantom depth with a 10 × 10 cm̂2 field size in the central axis of the beam. Data acquisition was performed using a PTW UNIDOS E electrometer with a 100-V bias. The detector was evaluated by measuring leakage current, priming dose, response dynamics, dose linearity, dependence on dose rate, percent depth dose (6 and 10 MV photons) and output factors. Some measurements were compared with a Si diode detector, 0.04 and/or 0.13-cc ion chamber(s). Leakage currents were negligible (∼1 pA) given the overall average sensitivity of the material (680 nC/Gy at 100 V). Detector current rise and fall times were detectors as expected. The type of diamond tested has potential to be used for small field dosimetry due to its small sensitive volume and high sensitivity. Further experiments are ongoing and detector packaging is yet to be optimized. © 2012 American Association of Physicists in Medicine.
International Nuclear Information System (INIS)
Massey, J.B.
1971-01-01
In order to achieve safe and efficient radiotherapy, one should respect a number of technical criteria, meaning that the irradiation facility should be adapted every time to the specific patient and the dose received by the patient should be fixed. If the radio therapist should decide about the characteristics of the treatment, he might not have the technical education needed to ensure that the applied devices are appropriate for obtaining the wanted results. This is the responsibility of the medical radio physicist. Unfortunately many countries lack qualified medical doctors experienced in radiotherapy. Although these countries can supply numerous hospitals with radiotherapeutic devices and x-ray sources they cannon make good use of them. That is why the IAEA, WHO and Pan-American Health Organization organised an experts team to study the problems of dosimetry in the radiotherapeutic centres. The objective of the present manual is to supply specialists in radiotherapy with practical instructions which will enable them to apply precise physical data on the irradiation volume and applied doses
Accuracy Requirements in Medical Radiation Dosimetry
International Nuclear Information System (INIS)
Andreo, P.
2011-01-01
The need for adopting unambiguous terminology on 'accuracy in medical radiation dosimetry' which is consistent with international recommendations for metrology is emphasized. Uncertainties attainable, or the need for improving their estimates, are analysed for the fields of radiotherapy, diagnostic radiology and nuclear medicine dosimetry. This review centres on uncertainties related to the first step of the dosimetry chain in the three fields, which in all cases involves the use of a detector calibrated by a standards laboratory to determine absorbed dose, air kerma or activity under reference conditions in a clinical environment. (author)
Experiences with alanine dosimetry in afterloading brachytherapy
International Nuclear Information System (INIS)
Eberhardt, H.-J.; Gohs, U.
1996-01-01
At the present, the most commonly used dosimetry for radiotherapy applications are ionisation chambers and thermoluminescent dosimeters (TLD). However, there are some undesirable characteristics of these dosimetry systems, such as large detection volume (ionisation chamber) as well as fading of the radiation induced signal with time and destructive readout (TLG). The present study is an investigation into the use of the alanine/ESR dosimetry in fractionated afterloading brachytherapy during the whole radiotherapy course. There are some qualities which make alanine dosimetry attractive. These are the linear energy response, low fading under standard conditions, and the nondestructive readout. Thus the alanine dosimetry makes possible cumulative dose measurements during the radiotherapy course and an archival storage. By ionizing radiation (gamma, e, n, p, charged particles) free radicals (unpaired electrons) are produced in the amino acid alanine. The continuous wave electron spin resonance (ESR) spectroscopy is used to determine the number of free radicals, which is proportional to the absorbed dose and the alanine content of the dosimeter. The ESR measurements were made at room temperature using a Bruker EPR analyzer EMS-104. The dosimeters used in the test are alanine pellets (23.72 mg weight, 4.9 mm diameter, 1 mm height) as well as flexible alanine film dosimeters (thickness about 500 μm). The dosimeters consist of a blend of L-alpha-alanine and a binder. The alanine content of the pellets and the film dosimeters is about 88 % and 50 % by weight, respectively. The dosimeters for the calculation of the dose-effect-relationship were irradiated at the Physical-Technical Bundesanstalt in Braunschweig by a standard 60Co source. The maximum deviation from the calculated linear function is about 0.12 Gy in the dose range up to 80 Gy. The goal of medical applications was the superficial dose measurement in afterloading brachytherapy during the radiotherapy course in
Metrological legal frame in the field of the photon dosimetry of radiotherapy in Cuba
International Nuclear Information System (INIS)
Walwyn S, G.; Gutierrez L, S.; Gonzalez R, N.
2006-01-01
The Clinical Dosimetry in the planning of the doses to administer to patients under radiant treatment is of great importance. At the moment the clinical dosemeters its are manufactured with a high technology but errors of production or manipulation cannot be discarded that lead to errors in this planning. It also exists, a group of metrological and of operation parameters that are not checked in a routine calibration, and for those that are checked, legal base that restricts its use in cases of bad operation doesn't exist. This motivated to the Cuban standard elaboration NC 352:2005, for the verification of reference dosemeters of radiotherapy, process that trafficked for an exhaustive search and study of standards and international technical reports, selecting as base document, the standard IEC 60731:1997, for essays of approval of model of clinical dosemeters used in radiotherapy. The present article shows the main technical aspects considered and the requirements and verification methods for the declaration of aptitude of the dosemeters. This document constitutes the scientific base for the implementation from a verification service to national level and an important contribution to the standardization of the metrology of ionizing radiations of Cuba. (Author)
Energy Technology Data Exchange (ETDEWEB)
Thiam, Ch O
2007-10-15
Accurate radiotherapy treatment requires the delivery of a precise dose to the tumour volume and a good knowledge of the dose deposit to the neighbouring zones. Computation of the treatments is usually carried out by a Treatment Planning System (T.P.S.) which needs to be precise and fast. The G.A.T.E. platform for Monte-Carlo simulation based on G.E.A.N.T.4 is an emerging tool for nuclear medicine application that provides functionalities for fast and reliable dosimetric calculations. In this thesis, we studied in parallel a validation of the G.A.T.E. platform for the modelling of electrons and photons low energy sources and the optimized use of grid infrastructures to reduce simulations computing time. G.A.T.E. was validated for the dose calculation of point kernels for mono-energetic electrons and compared with the results of other Monte-Carlo studies. A detailed study was made on the energy deposit during electrons transport in G.E.A.N.T.4. In order to validate G.A.T.E. for very low energy photons (<35 keV), three models of radioactive sources used in brachytherapy and containing iodine 125 (2301 of Best Medical International; Symmetra of Uro- Med/Bebig and 6711 of Amersham) were simulated. Our results were analyzed according to the recommendations of task group No43 of American Association of Physicists in Medicine (A.A.P.M.). They show a good agreement between G.A.T.E., the reference studies and A.A.P.M. recommended values. The use of Monte-Carlo simulations for a better definition of the dose deposited in the tumour volumes requires long computing time. In order to reduce it, we exploited E.G.E.E. grid infrastructure where simulations are distributed using innovative technologies taking into account the grid status. Time necessary for the computing of a radiotherapy planning simulation using electrons was reduced by a factor 30. A Web platform based on G.E.N.I.U.S. portal was developed to make easily available all the methods to submit and manage G
In vivo dosimetry with thermoluminescent dosimeters in radiotherapy: entrance and exit doses
International Nuclear Information System (INIS)
Alves, C.; Lopes, M.C.
2000-01-01
In vivo dosimetry, by entrance and exit dose measurements, is a vital part of a radiotherapy quality assurance program. The uncertainty associated with dose delivery is internationally accepted to be within 5% or inferior depending on the tumor pathology. Thermoluminescent dosimetry is one of the dosimetric techniques used to verify the agreement between delivered and prescribed doses. Nevertheless, it requires a very accurate calibration methodology. We have used LiF chips (4.5 mm diameter and 0.8 mm thick) calibrated towards a PTW ionization chamber of 0.3 cc, in three photon energies: Co-60, 4 and 6 MeV. The TLD reader used was a Rialto 688 from NE Technology and the annealing oven the Eurotherm type 815. The calibration methodology relies on the experimental determination of individual correction factors and on a correction factor derived from a control group of dosimeters. The exit and entrance dose measurements are performed in quite different situations. To be able to achieve those two quantities with TLD, these should be independently calibrated according to the measurement conditions. Alternatively, we can use a single calibration, in entrance dose, and convert the result to the exit dose value by introducing some correction factors. These corrections are related to the different measurement depths and to the different backscattering contributions. We have proved that within an acceptable error we can perform a single calibration and adopt the correction factors which are energy and field size dependent. (author)
Introduction to radiological physics and radiation dosimetry
Attix, Frank Herbert
2004-01-01
A straightforward presentation of the broad concepts underlying radiological physics and radiation dosimetry for the graduate-level student. Covers photon and neutron attenuation, radiation and charged particle equilibrium, interactions of photons and charged particles with matter, radiotherapy dosimetry, as well as photographic, calorimetric, chemical, and thermoluminescence dosimetry. Includes many new derivations, such as Kramers X-ray spectrum, as well as topics that have not been thoroughly analyzed in other texts, such as broad-beam attenuation and geometrics, and the reciprocity theorem
Overexposure of radiotherapy patients in Panama: Dosimetric aspects
International Nuclear Information System (INIS)
Borras, C.; Rudder, D.; Amer, A.
2001-01-01
In March 2001, after treatment received in the National Oncological Institute of Panama, 28 patients over reacted due to a radiation overdose calculated by mistake through the algorithm of a Computerized Therapy Planning System (TPS) with Radiotherapy. Medical Physicists planned a four blocks simultaneous digitization, even though the TPS briefings only allowed the digitization of one block per time, but the software didn't notified that the procedure was not authorized, producing serious medical consequences for all the patients [es
Skin Dosimetry in Breast Teletherapy on a Phantom Anthropomorphic and Anthropometric Phantom
International Nuclear Information System (INIS)
Batista Nogueira, Luciana; Lemos Silva, Hugo Leonardo; Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio
2015-01-01
This paper addresses the breast teletherapy dosimetry. The goal is to evaluate and compare absorbed doses in equivalent skin tissue, TE-skin, of an anthropomorphic and anthropometric breast phantom submitted to breast radiotherapy. The methodology involved the reproduction of a set of tomographic images of the phantom; the elaboration of conformational radiotherapy planning in the SOMAVISION and CadPlan (TPS) software; and the synthetic breast irradiation by parallel opposed fields in 3D conformal teletherapy at 6 MV linear accelerator Clinac-2100 C from VARIAN with prescribed dose (PD) of 180 cGy to the target volume (PTV), referent to the glandular tissue. Radiochromic films EBT2 were selected as dosimeters. Two independent calibration processes of films with solid water Gammex 457 plates and water filled box were produced. Curves of optical density (OD) versus absorbed dose were produced. Dosimeters were positioned in the external region of the breast phantom in contact with TE-skin, area of 4.0 cm 2 each. The irradiation process was prepared in duplicate to check the reproducibility of the technique. The radiochromic films were scanned and their response in RGB (Red, Green, Blue) analyzed by the ImageJ software. The optical density was obtained and converted to dose based on the calibration curves. Thus, the spatial dose distribution in the skin was reproduced. The absorbed doses measured on the radiochromic films in TE-skin showed values between upper and lower quadrants at 9 o'clock in the range of 54% of PD, between the upper and lower quadrants 3 o'clock in the range of 72% and 6 o'clock at the lower quadrant in the range of 68 % of PD. The values are ±64% (p <0.05) according to the TPS. It is concluded that the depth dose measured in solid water plates or water box reproduce equivalent dose values for both calibration processes of the radiochromic films. It was observed that the skin received doses ranging from 50% to 78% of the prescribed
Cuban experience in dosimetry quality audit program in radiotherapy
International Nuclear Information System (INIS)
Alonso-Samper, J.L.; Dominguez, L.; Yip, F.G.; Laguardia, R.A.; Morales, J.L.; Larrinaga, E.
2002-01-01
Full text: Five years ago we started a National Program of Quality Assurance in Radiotherapy. This program was possible thanks to the cooperation between the Cuban Ministry of Health and the International Atomic Energy Agency (IAEA) in the Projects ARCAL XXX and CUB/6/011. In the framework of these projects a total of ten complete dosimetry set were acquired and a large number of medical physicists were trained. At the same time, the Cuban side signed a contract for nine cobalt units, which have been gradually installed and all of them are running at the moment. During more than 20 years Cuba has taken part in the IAEA/WHO TLD postal dose audit programs and our results have been inside the (+/-)5 % acceptance limit. Cuba also joined the IAEA Coordinated Research Program E2 40 07, to extend at a national level the experience of the TLD based audits, using the capability of our SSDL to measure TLD. At the same time the work of the already existing External Audit Group was consolidated. The National Program of Quality Assurance in Radiotherapy works on base of external on-site visits. The main objective is to avoid any accident and to improve the quality of the RT treatments. Every year each Radiotherapy service is visited by a qualified team of physicists with the objective to check the physical aspects of the quality of the RT treatment, it includes: Documents and Records, safety, mechanical and dosimetric aspects, treatment planning, also we use the fixed depth phantom to simulate and verify several techniques. Although the TLD postal audit results are acceptable, in our QA audits we have detected some problems that may deviate the dose delivery to patients in more than 5%, examples of which are: Not all the clinical plans are redundantly checked by an independent person; Not all the controls (daily, monthly and annual) are performed according to the protocols approved by the National QA Committee. In some cases the controls are not well recorded; Clinical
Application of numerical analysis methods to thermoluminescence dosimetry
International Nuclear Information System (INIS)
Gomez Ros, J. M.; Delgado, A.
1989-01-01
This report presents the application of numerical methods to thermoluminescence dosimetry (TLD), showing the advantages obtained over conventional evaluation systems. Different configurations of the analysis method are presented to operate in specific dosimetric applications of TLD, such as environmental monitoring and mailed dosimetry systems for quality assurance in radiotherapy facilities. (Author) 10 refs
Andreozzi, Jacqueline M; Mooney, Karen E; Brůža, Petr; Curcuru, Austen; Gladstone, David J; Pogue, Brian W; Green, Olga
2018-06-01
Tools to perform regular quality assurance of magnetic resonance image-guided radiotherapy (MRIgRT) systems should ideally be independent of interference from the magnetic fields. Remotely acquired optical Cherenkov imaging-based dosimetry measurements in water were investigated for this purpose, comparing measures of dose accuracy, temporal dynamics, and overall integrated IMRT delivery. A 40 × 30.5 × 37.5 cm 3 water tank doped with 1 g/L of quinine sulfate was imaged using an intensified charge-coupled device (ICCD) to capture the Cherenkov emission while being irradiated by a commercial MRIgRT system (ViewRay™). The ICCD was placed down-bore at the end of the couch, 4 m from treatment isocenter and behind the 5-Gauss line of the 0.35-T MRI. After establishing optimal camera acquisition settings, square beams of increasing size (4.2 × 4.2 cm 2 , 10.5 × 10.5 cm 2 , and 14.7 × 14.7 cm 2 ) were imaged at 0.93 frames per second, from an individual cobalt-60 treatment head, to develop projection measures related to percent depth dose (PDD) curves and cross beam profiles (CPB). These Cherenkov-derived measurements were compared to ionization chamber (IC) and radiographic film dosimetry data, as well as simulation data from the treatment planning system (TPS). An intensity-modulated radiotherapy (IMRT) commissioning plan from AAPM TG-119 (C4:C-Shape) was also imaged at 2.1 frames per second, and the single linear sum image from 509 s of plan delivery was compared to the dose volume prediction generated by the TPS using gamma index analysis. Analysis of standardized test target images (1024 × 1024 pixels) yielded a pixel resolution of 0.37 mm/pixel. The beam width measured from the Cherenkov image-generated projection CBPs was within 1 mm accuracy when compared to film measurements for all beams. The 502 point measurements (i.e., pixels) of the Cherenkov image-based projection percent depth dose curves (pPDDs) were compared to p
EPR/alanine dosimetry for two therapeutic proton beams
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Marrale, Maurizio, E-mail: maurizio.marrale@unipa.it [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN di Catania, Via Santa Sofia, 64, 95123 Catania (Italy); Carlino, Antonio [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); EBG MedAustron GmbH, Marie Curie-Straße 5, A-2700 Wiener Neustadt (Austria); Gallo, Salvatore [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN di Catania, Via Santa Sofia, 64, 95123 Catania (Italy); Laboratorio PH3DRA, Dipartimento di Fisica e Astronomia, Università di Catania, Via Santa Sofia 64, 95123 Catania (Italy); Longo, Anna; Panzeca, Salvatore [Dipartimento di Fisica e Chimica, Università di Palermo, Viale delle Scienze, Edificio 18, 90128 Palermo (Italy); Gruppo V Sezione INFN di Catania, Via Santa Sofia, 64, 95123 Catania (Italy); Bolsi, Alessandra; Hrbacek, Jan; Lomax, Tony [Center for Proton Therapy, Paul Scherrer Institute, 5232 Villigen PSI (Switzerland)
2016-02-01
In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pellets exposed to two different clinical proton beams employed for radiotherapy is performed. One beam is characterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line). Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue. We investigated how collimators with different sizes and shape used to conform the dose to the planned target volume influence the delivered dose. For this purpose we performed measurements with varying the collimator size (Output Factor) and the results were compared with those obtained with other dosimetric techniques (such as Markus chamber and diode detector). This analysis showed that the dosimeter response is independent of collimator diameter if this is larger than or equal to 10 mm. The other beam is characterized by an active spot-scanning technique, the Gantry1 beam line (maximum energy 230 MeV), and is used to treat deep-seated tumors. The dose linearity of alanine response in the clinical dose range was tested and the alanine dose response at selected locations in depth was measured and compared with the TPS planned dose in a quasi-clinical scenario. The alanine response was found to be linear in the dose in the clinical explored range (from 10 to 70 Gy). Furthermore, a depth dose profile in a quasi-clinical scenario was measured and compared to the dose computed by the Treatment Planning System PSIPLAN. The comparison of calibrated proton alanine measurements and TPS dose shows a difference under 1% in the SOBP and a “quenching” effect up to 4% in the distal part of SOBP. The positive dosimetric characteristics of the alanine pellets confirm the feasibility to use these detectors for “in vivo” dosimetry in clinical proton beams.
EPR/alanine dosimetry for two therapeutic proton beams
International Nuclear Information System (INIS)
Marrale, Maurizio; Carlino, Antonio; Gallo, Salvatore; Longo, Anna; Panzeca, Salvatore; Bolsi, Alessandra; Hrbacek, Jan; Lomax, Tony
2016-01-01
In this work the analysis of the electron paramagnetic resonance (EPR) response of alanine pellets exposed to two different clinical proton beams employed for radiotherapy is performed. One beam is characterized by a passive delivery technique and is dedicated to the eyes treatment (OPTIS2 beam line). Alanine pellets were irradiated with a 70 MeV proton beam corresponding to 35 mm range in eye tissue. We investigated how collimators with different sizes and shape used to conform the dose to the planned target volume influence the delivered dose. For this purpose we performed measurements with varying the collimator size (Output Factor) and the results were compared with those obtained with other dosimetric techniques (such as Markus chamber and diode detector). This analysis showed that the dosimeter response is independent of collimator diameter if this is larger than or equal to 10 mm. The other beam is characterized by an active spot-scanning technique, the Gantry1 beam line (maximum energy 230 MeV), and is used to treat deep-seated tumors. The dose linearity of alanine response in the clinical dose range was tested and the alanine dose response at selected locations in depth was measured and compared with the TPS planned dose in a quasi-clinical scenario. The alanine response was found to be linear in the dose in the clinical explored range (from 10 to 70 Gy). Furthermore, a depth dose profile in a quasi-clinical scenario was measured and compared to the dose computed by the Treatment Planning System PSIPLAN. The comparison of calibrated proton alanine measurements and TPS dose shows a difference under 1% in the SOBP and a “quenching” effect up to 4% in the distal part of SOBP. The positive dosimetric characteristics of the alanine pellets confirm the feasibility to use these detectors for “in vivo” dosimetry in clinical proton beams.
Review of common accidents in external beam radiotherapy
International Nuclear Information System (INIS)
Ombogo, C.M
2015-02-01
This work covers patients protection in Radiotherapy which is a multi step procedure that is complex. Any error in any step has an effect on the patient and therefore the entire process requires attention to details in order to achieve patients protection. This project reviews eight case studies involving accidents that occurred during the process of therapy delivery. Professionalism in case one and two was not practiced in that in case one medical physicist failed to calculate decay data instead relied on incorrect decay graph thus giving wrong dose. While in case two a wrong TPS was approved following a formal written procedure due to new technology. In case three and seven there was a software malfunction due to uniformed choice of TPS and in case four a computer file was not updated in the TPS while in eight the failure is inter look system led to patients recieving high dose than was prescribed. Calibration in case five and six was due to wrong actions in both repairs and interpretation of treatment time than the overdose to patient. The lessen learnt seeks to act as a checklist for ensuring patient protection in radiotherapy and prevention of future accidents. (au)
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Adrada, A.; Tello, Z.; Medina, L.; Garrigo, E.; Venencia, D., E-mail: jorge.alberto.adrada@gmail.com [Instituto Privado de Radioterapia, Obispo Oro 423, X5000BFI Cordoba (Argentina)
2014-08-15
The systems utilization of independent dose calculation in three dimensional-Conformal Radiation Therapy (3D-Crt) treatments allows a direct verification of the treatments times. The utilization of these systems allows diminishing the probability of errors occurrence generated by the treatment planning system (Tps), allowing a detailed analysis of the dose to delivering and review of the normalization point (Np) or prescription. The independent dose calculation is realized across the knowledge of dosimetric parameters of the treatment machine and particular characteristics of every individual field. The aim of this work is develops a calculation system of punctual doses for isocentric fields conformed with multi-leaf collimation systems (MLC), where the dose calculation is in conformity with the suggested ones by ICRU Report No. 42, 1987. Calculation software was realized in C ++ under a free platform of programming (Code::Blocks). The system uses files in format Rtp, exported from the Tps to systems of record and verification (Lantis). This file contains detailed information of the dose, Um, position of the MLC sheets and collimators for every field of treatment. The size of equivalent field is obtained from the positions of every sheet; the effective depth of calculation can be introduced from the dosimetric report of the Tps or automatically from the DFS of the field. The 3D coordinates of the isocenter and the Np for the treatment plan must be introduced manually. From this information the system looks the dosimetric parameters and calculates the Um. The calculations were realized in two accelerators a NOVALIS Tx (Varian) with 120 sheets of high definition (hd-MLC) and a PRIMUS Optifocus (Siemens) with 82 sheets. 705 patients were analyzed for a total of 1082, in plans made for both equipment s, the average uncertainty with regard to the calculation of the Tps is-0.43% ± 2.42% in a range between [-7.90 %, 7.50 %]. The major uncertainty was in Np near of the
International Nuclear Information System (INIS)
Izewska, Joanna; Andreo, Pedro; Vatnitsky, Stanislav; Shortt, Ken R.
2003-01-01
Background and purpose: The IAEA/WHO TLD postal programme for external audits of the calibration of high-energy photon beams used in radiotherapy has been in operation since 1969. This work presents a survey of the 1317 TLD audits carried out during 1998-2001. The TLD results are discussed from the perspective of the dosimetry practices in hospitals in developing countries, based on the information provided by the participants in their TLD data sheets. Materials and methods: A detailed analysis of the TLD data sheets is systematically performed at the IAEA. It helps to trace the source of any discrepancy between the TLD measured dose and the user stated dose, and also provides information on equipment, dosimetry procedures and the use of codes of practice in the countries participating in the IAEA/WHO TLD audits. Result: The TLD results are within the 5% acceptance limit for 84% of the participants. The results for accelerator beams are typically better than for Co-60 units. Approximately 75% of participants reported dosimetry data, including details on their procedure for dose determination from ionisation chamber measurements. For the remaining 25% of hospitals, who did not submit these data, the results are poorer than the global TLD results. Most hospitals have Farmer type ionisation chambers calibrated in terms of air kerma by a standards laboratory. Less than 10% of the hospitals use new codes of practice based on standards of absorbed dose to water. Conclusion: Despite the differences in dosimetry equipment, traceability to different standards laboratories and uncertainties arising from the use of various dosimetry codes of practice, the determination of absorbed dose to water for photon beams typically agrees within 2% among hospitals. Correct implementation of any of the dosimetry protocols should ensure that significant errors in dosimetry are avoided
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Scarabino, M.L., E-mail: maliscarabino@gmail.com [Hospital Italiano de Buenos Aires (HIBA), Buenos Aires (Argentina); Ruggeri, R.M.; Colombo, S.; Mairal, L.; Sardi, M.E., E-mail: ricardoruggeri@gmail.com [Mevaterapia Centro Medico, Buenos Aires (Argentina)
2013-11-01
The work involves the creation of a manual of procedures for the care of pregnant patients in a radiotherapy center in which each instance of treatment is included, from the obstetrician-oncology comprehensive assessment during admission to establishing controls newborn and its subsequent development in multidisciplinary team. For the preparation of the manual had to design an anthropomorphic phantom that resembles a pregnant woman, which was used to carry out internal and external dosimetry. In turn imparted calculations fetal doses using TPS, imaging tests with MRI, avoiding the use of the tomograph and adapted to the resonator involved were carried immobilizer. All experiences and progress made during the treated cases are introduced in the procedures manual, making it a dynamic tool for continuous improvement for the institution.
Verification of absorbed dose calculation with XIO Radiotherapy Treatment Planning System
International Nuclear Information System (INIS)
Bokulic, T.; Budanec, M.; Frobe, A.; Gregov, M.; Kusic, Z.; Mlinaric, M.; Mrcela, I.
2013-01-01
Modern radiotherapy relies on computerized treatment planning systems (TPS) for absorbed dose calculation. Most TPS require a detailed model of a given machine and therapy beams. International Atomic Energy Agency (IAEA) recommends acceptance testing for the TPS (IAEA-TECDOC-1540). In this study we present customization of those tests for measurements with the purpose of verification of beam models intended for clinical use in our department. Elekta Synergy S linear accelerator installation and data acquisition for Elekta CMS XiO 4.62 TPS was finished in 2011. After the completion of beam modelling in TPS, tests were conducted in accordance with the IAEA protocol for TPS dose calculation verification. The deviations between the measured and calculated dose were recorded for 854 points and 11 groups of tests in a homogenous phantom. Most of the deviations were within tolerance. Similar to previously published results, results for irregular L shaped field and asymmetric wedged fields were out of tolerance for certain groups of points.(author)
International Nuclear Information System (INIS)
Gonzalez Perez, Yelina; Rodriguez Zayas, Michael; Perez Guevara, Adrian; Sola Rodriguez, Yeline; Reyes Gonzalez, Tommy; Sanchez Zamora; Luis; Caballero, Roberto
2009-01-01
Radiotherapy is one of the basic therapeutic tools to treat malignant tumors. The treatment of a tumor with ionizing radiation is a continuous process with distinct stages, which is the computerized planning, being a fundamental component within this process, it is in this phase are designed and calculated the patient treatment. Systems for Radiotherapy Treatment Planning (TPS) are the tools to perform the treatment planning. The Radiotherapy Service of the Hospital Hermanos Ameijeiras acquired MIRS software version 3.0, which has potential as conventional radiation therapy planning tools and compliance with 3D, multiple imaging studies and calculation of dose according to patient data and equipment. For the complexity of these calculations and the reliability which must have the same, the software should be subjected to rigorous acceptance testing. We verify the precision and accuracy of the TPS dosimetric calculation by applying the most recent protocol of acceptance of the IAEA for these systems (2008). After implementation of the testing set is unable to verify the dose calculations are within the tolerances allowed. (Author)
International Nuclear Information System (INIS)
Muralidhar, K.R.; Anurupa; Soubhagya; Sudhakar; Shiva; Krishnam Raju, A.; Narayana Murthy, P.
2008-01-01
The commissioning of XIO treatment planning system (TPS) was carried out by Computerized Medical Devices, USA for Siemens and Elekta linear accelerators. The Commissioning and quality assurance of the CMS XIO radiotherapy treatment planning system involves many steps, beginning from beam data acquisition and entry into the computerized TPS, through patient data acquisition, to treatment plan generation and the final transfer of data to the treatment machine and quality assurance of TPS
Dosimetry and treatment planning of Occu-Prosta 125I seeds for intraocular lesions
International Nuclear Information System (INIS)
Chaudhari, Suresh; Deshpande, Sudesh; Anand, Vivek; De, Sandeep; Kannan, V.; Saxena, Sanjay; Dash, A.; Basu, Mahua; Samant, Preetam
2008-01-01
Intraocular malignant lesions are frequently encountered in clinical practice. Plaque brachytherapy represents an effective means of treatment for intraocular lesions. Recently Radiopharmaceutical Division, BARC, Mumbai, has indigenously fabricated reasonable-cost 125 I sources. Here we are presenting the preliminary experience of dosimetry of sources, configuration of treatment planning system (TPS) and quality assurance (QA) for eye plaque therapy with Occu-Prosta 125 I seeds, treated in our hospital, for a patient with ocular lesions. 125 I seeds were calibrated using well-type chamber. BrachyVision TPS was configured with Monte Carlo computed radial dose functions and anisotropy functions for 125 I sources. Dose calculated by TPS at different points in central axis and off axis was compared with manually calculated dose. Eye plaque was fabricated of 17 karat pure gold, locally. The seeds were arranged in an outer ring near the edge of the plaque and in concentric rings throughout the plaque. The sources were manually digitized on the TPS, and dose distribution was calculated in three dimensions. Measured activity using cross-calibrated well-type chamber was within ± 10% of the activity specified by the supplier. Difference in TPS-calculated dose and manually calculated dose was within 5%. Treatment time calculated by TPS was in concordance with published data for similar plaque arrangement. (author)
International Nuclear Information System (INIS)
Kartutik, K; Pawiro, S A; Wibowo, W E
2016-01-01
Accurate calculation of dose distribution affected by inhomogeneity tissue is required in radiotherapy planning. This study was performed to determine the ratio between radiotherapy planning using 3D-CRT, IMRT, and SBRT based on a calibrated curve of CT-number in the lung for different target's shape in 3D-CRT, IMRT, and spinal cord for SBRT. Calibration curves of CT-number were generated under measurement basis and introduced into TPS, then planning was performed for 3D-CRT, IMRT, and SBRT with 7, and 15 radiation fields. Afterwards, planning evaluation was performed by comparing the DVH curve, HI, and CI. 3D-CRT and IMRT produced the lowest HI at calibration curve of CIRS 002LFC with the value 0.24 and 10. Whereas SBRT produced the lowest HI on a linear calibration curve with a value of 0.361. The highest CI in IMRT and SBRT technique achieved using a linear calibration curve was 0.97 and 1.77 respectively. For 3D-CRT, the highest CI was obtained by using calibration curve of CIRS 062M with the value of 0.45. From the results of CI and HI, it is concluded that the calibration curve of CT-number does not significantly differ with Schneider's calibrated curve, and inverse planning gives a better result than forward planning. (paper)
TU-E-201-03: Eye Lens Dosimetry in Radiotherapy Using Contact Lens-Shaped Applicator
Energy Technology Data Exchange (ETDEWEB)
Park, J. [Seoul National University Hospital (Korea, Republic of)
2015-06-15
. These actions should be considered when they are consistent with the clinical task and patient anatomy. Learning Objectives: To become familiar with method of eye dose estimation for patient in specific situation of brain perfusion CT To become familiar with level of eye lens radiation doses in patients undergoing brain perfusion MDCT To understand methods for reducing eye lens dose to patient Jong Min Park, Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Eye lens dosimetry in radiotherapy using contact lens-shaped applicator Dose calculation accuracy of commercial treatment planning systems is relatively low at shallow depths. Therefore, in-vivo measurements are often performed in the clinic to verify delivered doses to eye lens which are located at shallow depth. Current in-vivo dosimetry for eye lens during radiotherapy is generally performed with small in-vivo dosimeters on the surface of patient eyelid. Since this procedure potentially contains considerable uncertainty, a contact lens-shaped applicator made of acrylic (lens applicator) was developed for in-vivo measurements of eye lens dose during radiotherapy to reduce uncertainty. The lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistor (MOSFET) dosimeters. Computed tomography (CT) images of an anthropomorphic phantom with and without the lens applicator were acquired. A total of 20 VMAT plans were delivered to an anthropomorphic phantom and the doses with the lens applicator and the doses at the surface of the eyelid were measured using both micro and standard MOSFET dosimeters. The differences in measured dose at the surface of the eyelid from the calculated lens dose were acquired. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. The statistical significance of the
TU-E-201-03: Eye Lens Dosimetry in Radiotherapy Using Contact Lens-Shaped Applicator
International Nuclear Information System (INIS)
Park, J.
2015-01-01
. These actions should be considered when they are consistent with the clinical task and patient anatomy. Learning Objectives: To become familiar with method of eye dose estimation for patient in specific situation of brain perfusion CT To become familiar with level of eye lens radiation doses in patients undergoing brain perfusion MDCT To understand methods for reducing eye lens dose to patient Jong Min Park, Department of Radiation Oncology, Seoul National University Hospital, Seoul, Korea Eye lens dosimetry in radiotherapy using contact lens-shaped applicator Dose calculation accuracy of commercial treatment planning systems is relatively low at shallow depths. Therefore, in-vivo measurements are often performed in the clinic to verify delivered doses to eye lens which are located at shallow depth. Current in-vivo dosimetry for eye lens during radiotherapy is generally performed with small in-vivo dosimeters on the surface of patient eyelid. Since this procedure potentially contains considerable uncertainty, a contact lens-shaped applicator made of acrylic (lens applicator) was developed for in-vivo measurements of eye lens dose during radiotherapy to reduce uncertainty. The lens applicator allows the insertion of commercially available metal oxide semiconductor field effect transistor (MOSFET) dosimeters. Computed tomography (CT) images of an anthropomorphic phantom with and without the lens applicator were acquired. A total of 20 VMAT plans were delivered to an anthropomorphic phantom and the doses with the lens applicator and the doses at the surface of the eyelid were measured using both micro and standard MOSFET dosimeters. The differences in measured dose at the surface of the eyelid from the calculated lens dose were acquired. The differences between the measured and the calculated doses at the lens applicator, as well as the differences between the measured and the calculated doses at the surface of the eyelid were acquired. The statistical significance of the
Electronic database of patients in radiotherapy: Amedatos
International Nuclear Information System (INIS)
Perez Guevara, Adrian; Rodriguez Zayas, Michael; Gonzalez Perez, Yelina; Sola Rodriguez, Yeline; Reyes Gonzalez, Tommy; Caballero, Roberto
2009-01-01
Registration and monitoring of patients in the departments of radiotherapy in our country are taken manually, which is difficult when very large number of patients and treatment units in service. Due to these problems in the Department of Radiotherapy 'Hospital Hermanos Ameijeiras' AMEDATOS program was designed in Microsoft Excel. The main program relates different books, macros are used to improve visualization and facilitate the management of data on different sheets (dosimetry, Team, Daily Record, Record monitoring, patient data, dosimetry data, not treated and four sheets of Report). (Author)
Radiotherapy for MTRA/RT; Strahlentherapie fuer MTRA/RT
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Luetter, Christiana [Bonn Univ. (Germany). Radiologische Klinik
2012-07-01
The radiological practice textbook covers the following issues: tumor diseases, tumor diagnostics, fundamentals of radiotherapy, DIN, irradiation planning, documentation and quality assurance, strategies of tumor therapy, basic physics of radiotherapy and dosimetry, radiation protection - regulations and guidelines, radiobiology, biological radiation effects, special organ toxicity, psychological and medical attendance of patients, special oncology of the most important organ carcinomas, palliative radiotherapy, radiotherapy of benign diseases, other indications of radiotherapy, supportive therapy.
Film dosimetry in conformal radiotherapy
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Danciu, C; Proimos, B S [Patras Univ. (Greece). Dept. of Medical Physics
1995-12-01
Dosimetry, through a film sandwiched in a transverse cross-section of a solid phantom, is a method of choice in Conformal Radiotherapy because: (a) the blackness (density) of the film at each point offers a measure of the total dose received at that point, and (b) the film is easily calibrated by exposing a film strip in the same cross-section, through a stationary field. The film must therefore have the following properties: (a) it must be slow, in order not to be overexposed, even at a therapeutic dose of 200 cGy, and (b) the response of the film (density versus dose curve) must be independent of the photon energy spectrum. A few slow films were compared. It was found that the Kodak X-Omat V for therapy verification was the best choice. To investigate whether the film response was independent of the photon energy, response curves for six depths, starting from the depth of maximum dose to the depth of 25 cm, in solid phantom were derived. The vertical beam was perpendicular to the anterior surface of the phantom, which was at the distance of 100 cm from the source and the field was 15x15 cm at that distance. This procedure was repeated for photon beams emitted by a Cobalt-60 unit, two 6 MV and 15 MV Linear Accelerators, as well as a 45 MV Betatron. For each of those four different beams the film response was the same for all six depths. The results, as shown in the diagrams, are very satisfactory. The response curve under a geometry similar to that actually applied, when the film is irradiated in a transverse cross-section of the phantom, was derived. The horizontal beam was almost parallel (angle of 85) to the plane of the film. The same was repeated with the central ray parallel to the film (angle 90) and at a distance of 1.5 cm from the horizontal film. The field size was again 15x15 at the lateral entrance surface of the beam. The response curves remained the same, as when the beam was perpendicular to the films.
International Nuclear Information System (INIS)
Toye, Warren; Das, Ram; Kron, Tomas; Franich, Rick; Johnston, Peter; Duchesne, Gillian
2009-01-01
Purpose: To develop an in vivo dosimetry based investigative action level relevant for a corrective protocol for HDR brachytherapy boost treatment. Methods and materials: The dose delivered to points within the urethra and rectum was measured using TLD in vivo dosimetry in 56 patients. Comparisons between the urethral and rectal measurements and TPS calculations showed differences, which are related to the relative position of the implant and TLD trains, and allowed shifts of implant position relative to the prostate to be estimated. Results and conclusions: Analysis of rectal dose measurements is consistent with implant movement, which was previously only identified with the urethral data. Shift corrected doses were compared with results from the TPS. Comparison of peak doses to the urethra and rectum has been assessed against the proposed corrective protocol to limit overdosing these critical structures. An initial investigative level of 20% difference between measured and TPS peak dose was established, which corresponds to 1/3 of patients which was practical for the caseload. These patients were assessed resulting in corrective action being applied for one patient. Multiple triggering for selective investigative action is outlined. The use of a single in vivo measurement in the first fraction optimizes patient benefit at acceptable cost.
Radiotherapy Based On α Emitting Radionuclides: Geant4 For Dosimetry And Micro-/Nano-Dosimetry
International Nuclear Information System (INIS)
Guatelli, Susanna
2013-01-01
Possible physics approaches to evaluate the efficacy of TAT are dosimetry, microdosimetry and nanodosimetry. Dosimetry is adequate when mean absorbed dose to a macroscopic target volume is important to understand the biological effect of radiation. General purpose Monte Carlo (MC) codes, based on condensed history approach, are a very useful, cost effective tool to solve dosimetric problems. The condensed history approach is based on the use of multiple scattering theories to calculate the energy losses and angular changes in the direction of the particle. The short α particle range and high LET make the microdosimetric approach more suitable than dosimetry to study TAT from first physics principles, as this approach takes into account the stochastic nature of energy deposition at cellular level
International Nuclear Information System (INIS)
Milian, F. M.; Attili, A.; Russo, G; Marchetto, F.; Cirio, R.; Bourhaleb, F.
2013-01-01
A novel procedure for the generation of a realistic virtual Computed Tomography (CT) image of a patient, using the advanced Boundary RE Presentation (BREP)-based model MASH, has been implemented. This method can be used in radiotherapy assessment. It is shown that it is possible to introduce an artificial cancer, which can be modeled using mesh surfaces. The use of virtual CT images based on BREP models presents several advantages with respect to CT images of actual patients, such as automation, control and flexibility. As an example, two artificial cases, namely a brain and a prostate cancer, were created through the generation of images and tumor/organ contours. As a secondary objective, the described methodology has been used to generate input files for treatment planning system (TPS) and Monte Carlo code dose evaluation. In this paper, we consider treatment plans generated assuming a dose delivery via an active proton beam scanning performed with the INFN-IBA TPS kernel. Additionally, Monte Carlo simulations of the two treatment plans were carried out with GATE/GEANT4. The work demonstrates the feasibility of the approach based on the BREP modeling to produce virtual CT images. In conclusion, this study highlights the benefits in using digital phantom model capable of representing different anatomical structures and varying tumors across different patients. These models could be useful for assessing radiotherapy treatment planning systems (TPS) and computer simulations for the evaluation of the adsorbed dose. (author)
SU-C-BRD-07: The Radiological Physics Center (RPC): 45 Years of Improving Radiotherapy Dosimetry
Energy Technology Data Exchange (ETDEWEB)
Followill, D; Lowenstein, J; Molineu, A; Alvarez, P; Summers, P; Kry, S [UT MD Anderson Cancer Center, Houston, TX (United States)
2014-06-15
Purpose: The RPC, established in 1968 has contributed to the development, conduct, and QA of NCI funded multi-institutional cooperative group clinical trials and institutions, primarily in the USA/Canada and 242 other countries, participating in trials. Methods: The RPC QA program components were designed to audit the radiation dose calculation chain from the NIST traceable reference beam calibration, to inclusion of dosimetry parameters used to calculate tumor doses, to the delivery of the radiation dose. The QA program included: 1) remote TLD/OSLD audit of machine output, 2) on-site dosimetry review visits, 3) credentialing for advanced technologies, and 4) review of patient treatment records. The RPC presented and published their findings to the radiation oncology community. Results: The number of institutions monitored by the RPC increased from around 1200 in the late 90s, to ∼2000 in 2013. There were over 4000 megavoltage therapy machines and ∼28,000 therapy beams in the 1991 institutions monitored by the RPC by the end of 2013. Within the 14,000 photon, electron and proton beam outputs remotely monitored with TLD/OSLD annually, between 10-20% of the institutions have one or more beams outside the RPC 5% criterion. Dosimetry site visits to photon and proton centers continue to result in 2-4 recommendations affecting key dosimetry parameters that impact patient treatment times. One in four patient treatment records reviewed by the RPC have their dose data corrected by >5% before trial groups use them for outcomes analysis. Twelve of fourteen clinically active proton centers are approved to participate in NCI funded clinical trials. The RPC published 222 peer reviewed articles since 1972. Conclusion: Findings from the RPC suggest that human errors continue to play a role in radiotherapy discrepancies and without the RPC independent QA program, the number of undetected errors and time elapsed before their discovery would have been greater. Work supported by
The NUKDOS software for dosimetry in molecular radiotherapy
International Nuclear Information System (INIS)
Kletting, P.; Schimmel, S.; Haenscheid, H.; Fernandez, M.; Lassmann, M.; Broer, J.; Nosske, D.; Glatting, G.
2015-01-01
Full text of publication follows. Aim: The NUKDOS software is developed to improve and standardize therapy planning in molecular radiotherapy (MRT). Methods: NUKDOS is developed in Matlab, based on the MIRD formalism, modularly structured and currently allows dosimetry for Y-90, Lu-177, I-131. First, the user enters the basic patient data and specifies the injected activities. Second, 3D or 2D images can be loaded. Based on the voxel-size and the used nuclide the corresponding voxel S-values (>1 mm) are calculated. Serum, probe or urine data can be entered and processed. To get the activity distribution of the organs for all serial measurements, the user is led to the image processing tool. This tool includes all functionality for defining the regions or volumes of interest (ROIs/VOIs). ROIs/VOIs can also be created in a corresponding CT image and subsequently transferred to the SPECT/PET images. Time activity curves (TACs) derived from 2D scans are scaled using the averaged organ activity of a 3D image. To determine the time-integrated activity coefficients A, the areas under the time activity curves are calculated. For this purpose, a set of fit functions can be chosen. The selection of the most suitable function is based on the Akaike Information Criterion and statistical measures. The most suitable TACs are integrated analytically and including the standard errors. Absorbed dose coefficients are calculated by convolution using the voxel based A and S value matrices. Depending on the absorbed dose (or biologically effective dose) for the limiting organ the activity to administer along with the pertaining organ doses is calculated using the absorbed dose coefficients. Results: proper implementation of the mathematical methods of each module of the software was tested by comparing the results to currently available software. The applicability of the software was investigated using phantom measurement and examples from MRT. User interaction is minimized
International Nuclear Information System (INIS)
Velez, G.; Bustos, S.; Balmaceda, O.; Gutierrez, S.; Ferraris, M.
1998-01-01
In vivo dosimetry is used every time with more frequency as a valuable tool for the quality control in Radiotherapy. The measurements of input and output doses provide us information about the technique accuracy or the treatment procedure used; likewise the dose measurement which rectum or bladder receive in gynecologic implants contribute to the improving and adjusting the procedures in brachytherapy. Besides, it may be identify systematic errors in particular situations which allow to optimize the treatment and to minimize errors. It was realized a study at the Radiotherapy service in San Roque Hospital (Cordoba) to control the procedures used in the treatment of distinct oncologic pathologies. Its were selected patients, which were realized the routine planning with the planning system of computerized treatments Prowess 3000, that later its were controlled with In vivo thermoluminescent dosimetry using the Ceprocor Services (Cordoba). Its were realized dose skin measurements in treatments of mammary gland, pelvis, thorax, head and neck and it were measured doses in body cavities, as oral cavity, rectum, esophagus, etc. arranging the TLD inside special catheters. In the case of dose skin, the dosemeters were arranged in acrylic porta-dosemeters, at pairs, which later they were enveloped and sealed. It was founded a very good agreement among the In vivo measurements and the predicted by the planner. In some cases, the control allows to modify the treatment for to avoid over or sub dosages of the distinct organs affected by the radiation field. (Author)
Hussien, Mohammad
Purpose: Quality assurance (QA) for intensity modulated radiotherapy (IMRT) has evolved substantially. In recent years, various ionization chamber or diode detector arrays have become commercially available, allowing pre-treatment absolute dose verification with near real-time results. This has led to a wide uptake of this technology to replace point dose and film dosimetry and to facilitate QA streamlining. However, arrays are limited by their spatial resolution giving rise to concerns about their response to clinically relevant deviations. The common factor in all commercial array systems is the reliance on the gamma index (γ) method to provide the quantitative evaluation of the measured dose distribution against the Treatment Planning System (TPS) calculated dose distribution. The mathematical definition of the gamma index presents computational challenges that can cause a variation in the calculation in different systems. The purpose of this thesis was to evaluate the suitability of detector array systems, combined with their implementation of the gamma index, in the verification and dosimetry audit of advanced IMRT. Method: The response of various commercial detector array systems (Delta4®, ArcCHECK®, and the PTW 2D-Array seven29™ and OCTAVIUS II™ phantom combination, Gafchromic® EBT2 and composite EPID measurements) to simulated deliberate changes in clinical IMRT and VMAT plans was evaluated. The variability of the gamma index calculation in the different systems was also evaluated by comparing against a bespoke Matlab-based gamma index analysis software. A novel methodology for using a commercial detector array in a dosimetry audit of rotational radiotherapy was then developed. Comparison was made between measurements using the detector array and those performed using ionization chambers, alanine and radiochromic film. The methodology was developed as part of the development of a national audit of rotational radiotherapy. Ten cancer centres were
International Nuclear Information System (INIS)
Dicello, J.F.
1975-01-01
Negative pion beams are probably the most esoteric and most complicated type of radiation which has been suggested for use in clinical radiotherapy. Because of the limited availability of pion beams in the past, even to nuclear physicists, there exist relatively fewer basic data for this modality. Pion dosimetry is discussed
Federal Laboratory Consortium — The ARDEC TPS Laboratory provides an organic Test Program Set (TPS) development, maintenance, and life cycle management capability for DoD LCMC materiel developers....
International Nuclear Information System (INIS)
Thwaites, D.I.; Blyth, C.; Carruthers, L.; Elliott, P.A.; Kidane, G.; Millwater, C.J.; MacLeod, A.S.; Paolucci, M.; Stacey, C.
2002-01-01
A systematic programme of in vivo dosimetry using diodes to verify radiotherapy delivered doses began in Edinburgh in 1992. The aims were to investigate the feasibility of routine systematic use of diodes as part of a comprehensive QA programme, to carry out clinical pilot studies to assess the accuracy of dose delivery on each machine and for each site and technique, to identify and rectify systematic deviations, to assess departmental dosimetric precision and to compare to clinical requirements. A further aim was to carry out a cost-benefit evaluation based on the results from the pilot studies to consider how best to use diodes routinely
Energy Technology Data Exchange (ETDEWEB)
Strigari, Lidia [Regina Elena National Cancer Institute, Laboratory of Medical Physics and Expert Systems, Rome (Italy); Konijnenberg, Mark [Erasmus MC, Department of Nuclear Medicine, Rotterdam (Netherlands); Chiesa, Carlo [Instituto Nazionale Tumori, Department of Nuclear Medicine, Milan (Italy); Bardies, Manuel [UMR 1037 INSERM / Universite Paul Sabatier, Centre de Recherche en Cancerologie de Toulouse, Toulouse (France); Du, Yong [Royal Marsden NHS Foundation Trust, Department of Nuclear Medicine and PET/CT, Sutton, London (United Kingdom); Gleisner, Katarina Sjoegreen [Medical Radiation Physics, Clinical Sciences, Lund (Sweden); Lassmann, Michael [University of Wuerzburg, Department of Nuclear Medicine, Wuerzburg (Germany); Flux, Glenn [Royal Marsden NHS Foundation Trust and Institute of Cancer Research, Joint Department of Physics, Sutton (United Kingdom)
2014-10-15
Molecular radiotherapy (MRT) has demonstrated unique therapeutic advantages in the treatment of an increasing number of cancers. As with other treatment modalities, there is related toxicity to a number of organs at risk. Despite the large number of clinical trials over the past several decades, considerable uncertainties still remain regarding the optimization of this therapeutic approach and one of the vital issues to be answered is whether an absorbed radiation dose-response exists that could be used to guide personalized treatment. There are only limited and sporadic data investigating MRT dosimetry. The determination of dose-effect relationships for MRT has yet to be the explicit aim of a clinical trial. The aim of this article was to collate and discuss the available evidence for an absorbed radiation dose-effect relationships in MRT through a review of published data. Based on a PubMed search, 92 papers were found. Out of 79 studies investigating dosimetry, an absorbed dose-effect correlation was found in 48. The application of radiobiological modelling to clinical data is of increasing importance and the limited published data on absorbed dose-effect relationships based on these models are also reviewed. Based on National Cancer Institute guideline definition, the studies had a moderate or low rate of clinical relevance due to the limited number of studies investigating overall survival and absorbed dose. Nevertheless, the evidence strongly implies a correlation between the absorbed doses delivered and the response and toxicity, indicating that dosimetry-based personalized treatments would improve outcome and increase survival. (orig.)
Stevens, S; Dvorak, P; Spevacek, V; Pilarova, K; Bray-Parry, M; Gesner, J; Richmond, A
2018-01-01
To provide a 3D dosimetric evaluation of a commercial portal dosimetry system using 2D/3D detectors under ideal conditions using VMAT. A 2D ion chamber array, radiochromic film and gel dosimeter were utilised to provide a dosimetric evaluation of transit phantom and pre-treatment 'fluence' EPID back-projected dose distributions for a standard VMAT plan. In-house 2D and 3D gamma methods compared pass statistics relative to each dosimeter and TPS dose distributions. Fluence mode and transit EPID dose distributions back-projected onto phantom geometry produced 2D gamma pass rates in excess of 97% relative to other tested detectors and exported TPS dose planes when a 3%, 3 mm global gamma criterion was applied. Use of a gel dosimeter within a glass vial allowed comparison of measured 3D dose distributions versus EPID 3D dose and TPS calculated distributions. 3D gamma comparisons between modalities at 3%, 3 mm gave pass rates in excess of 92%. Use of fluence mode was indicative of transit results under ideal conditions with slightly reduced dose definition. 3D EPID back projected dose distributions were validated against detectors in both 2D and 3D. Cross validation of transit dose delivered to a patient is limited due to reasons of practicality and the tests presented are recommended as a guideline for 3D EPID dosimetry commissioning; allowing direct comparison between detector, TPS, fluence and transit modes. The results indicate achievable gamma scores for a complex VMAT plan in a homogenous phantom geometry and contributes to growing experience of 3D EPID dosimetry. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
MO-B-BRB-00: Three Dimensional Dosimetry
Energy Technology Data Exchange (ETDEWEB)
NONE
2016-06-15
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
Surface dosimetry for breast radiotherapy in the presence of immobilization cast material
International Nuclear Information System (INIS)
Kelly, Andrew; Hardcastle, Nicholas; Metcalfe, Peter; Cutajar, Dean; Quinn, Alexandra; Cardoso, Michael; Rosenfeld, Anatoly; Foo, Kerwyn; Barlin, Sheree
2011-01-01
Curative breast radiotherapy typically leaves patients with varying degrees of cosmetic damage. One problem interfering with cosmetically acceptable breast radiotherapy is the external contour for large pendulous breasts which often results in high doses to skin folds. Thermoplastic casts are often employed to secure the breasts to maintain setup reproducibility and limit the presence of skin folds. This paper aims to determine changes in surface dose that can be attributed to the use of thermoplastic immobilization casts. Skin dose for a clinical hybrid conformal/IMRT breast plan was measured using radiochromic film and MOSFET detectors at a range of water equivalent depths representative of the different skin layers. The radiochromic film was used as an integrating dosimeter, while the MOSFETs were used for real-time dosimetry to isolate the contribution of skin dose from individual IMRT segments. Strips of film were placed at various locations on the breast and the MOSFETs were used to measure skin dose at 16 positions spaced along the film strips for comparison of data. The results showed an increase in skin dose in the presence of the immobilization cast of up to 45.7% and 62.3% of the skin dose without the immobilization cast present as measured with Gafchromic EBT film and MOSFETs, respectively. The increase in skin dose due to the immobilization cast varied with the angle of beam incidence and was greatest when the beam was normally incident on the phantom. The increase in surface dose with the immobilization cast was greater under entrance dose conditions compared to exit dose conditions.
Surface dosimetry for breast radiotherapy in the presence of immobilization cast material
Kelly, Andrew; Hardcastle, Nicholas; Metcalfe, Peter; Cutajar, Dean; Quinn, Alexandra; Foo, Kerwyn; Cardoso, Michael; Barlin, Sheree; Rosenfeld, Anatoly
2011-02-01
Curative breast radiotherapy typically leaves patients with varying degrees of cosmetic damage. One problem interfering with cosmetically acceptable breast radiotherapy is the external contour for large pendulous breasts which often results in high doses to skin folds. Thermoplastic casts are often employed to secure the breasts to maintain setup reproducibility and limit the presence of skin folds. This paper aims to determine changes in surface dose that can be attributed to the use of thermoplastic immobilization casts. Skin dose for a clinical hybrid conformal/IMRT breast plan was measured using radiochromic film and MOSFET detectors at a range of water equivalent depths representative of the different skin layers. The radiochromic film was used as an integrating dosimeter, while the MOSFETs were used for real-time dosimetry to isolate the contribution of skin dose from individual IMRT segments. Strips of film were placed at various locations on the breast and the MOSFETs were used to measure skin dose at 16 positions spaced along the film strips for comparison of data. The results showed an increase in skin dose in the presence of the immobilization cast of up to 45.7% and 62.3% of the skin dose without the immobilization cast present as measured with Gafchromic EBT film and MOSFETs, respectively. The increase in skin dose due to the immobilization cast varied with the angle of beam incidence and was greatest when the beam was normally incident on the phantom. The increase in surface dose with the immobilization cast was greater under entrance dose conditions compared to exit dose conditions.
International Nuclear Information System (INIS)
2002-01-01
The development of radiation measurement standards by National Metrology Institutes (NMIs) and their dissemination to Secondary Standard Dosimetry Laboratories (SSDLs), cancer therapy centres and hospitals represent essential aspects of the radiation dosimetry measurement chain. Although the demands for accuracy in radiotherapy initiated the establishment of such measurement chains, similar traceable dosimetry procedures have been implemented, or are being developed, in other areas of radiation medicine (e.g. diagnostic radiology and nuclear medicine), in radiation protection and in industrial applications of radiation. In the past few years the development of primary standards of absorbed dose to water in 60 Co for radiotherapy dosimetry has made direct calibrations in terms of absorbed dose to water available in many countries for the first time. Some laboratories have extended the development of these standards to high energy photon and electron beams and to low and medium energy x-ray beams. Other countries, however, still base their dosimetry for radiotherapy on air kerma standards. Dosimetry for conventional external beam radiotherapy was probably the field where standardized procedures adopted by medical physicists at hospitals were developed first. Those were related to exposure and air kerma standards. The recent development of Codes of Practice (or protocols) based on the concept of absorbed dose to water has led to changes in calibration procedures at hospitals. The International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water (TRS 398) was sponsored by the International Atomic Energy Agency (IAEA), World Health Organization (WHO), Pan-American Health Organization (PAHO) and the European Society for Therapeutic Radiology and Oncology (ESTRO) and is expected to be adopted in many countries worldwide. It provides recommendations for the dosimetry of all types of beams (except neutrons) used in external radiotherapy and satisfies
Energy Technology Data Exchange (ETDEWEB)
NONE
2002-07-01
The development of radiation measurement standards by National Metrology Institutes (NMIs) and their dissemination to Secondary Standard Dosimetry Laboratories (SSDLs), cancer therapy centres and hospitals represent essential aspects of the radiation dosimetry measurement chain. Although the demands for accuracy in radiotherapy initiated the establishment of such measurement chains, similar traceable dosimetry procedures have been implemented, or are being developed, in other areas of radiation medicine (e.g. diagnostic radiology and nuclear medicine), in radiation protection and in industrial applications of radiation. In the past few years the development of primary standards of absorbed dose to water in {sup 60}Co for radiotherapy dosimetry has made direct calibrations in terms of absorbed dose to water available in many countries for the first time. Some laboratories have extended the development of these standards to high energy photon and electron beams and to low and medium energy x-ray beams. Other countries, however, still base their dosimetry for radiotherapy on air kerma standards. Dosimetry for conventional external beam radiotherapy was probably the field where standardized procedures adopted by medical physicists at hospitals were developed first. Those were related to exposure and air kerma standards. The recent development of Codes of Practice (or protocols) based on the concept of absorbed dose to water has led to changes in calibration procedures at hospitals. The International Code of Practice for Dosimetry Based on Standards of Absorbed Dose to Water (TRS 398) was sponsored by the International Atomic Energy Agency (IAEA), World Health Organization (WHO), Pan-American Health Organization (PAHO) and the European Society for Therapeutic Radiology and Oncology (ESTRO) and is expected to be adopted in many countries worldwide. It provides recommendations for the dosimetry of all types of beams (except neutrons) used in external radiotherapy and
MOSFET dosimetry on modern radiation oncology modalities
International Nuclear Information System (INIS)
Rosenfeld, A.B.
2002-01-01
The development of MOSFET dosimetry is presented with an emphasis on the development of a scanning MOSFET dosimetry system for modern radiation oncology modalities. Fundamental aspects of MOSFETs in relation to their use as dosemeters are briefly discussed. The performance of MOSFET dosemeters in conformal radiotherapy, hadron therapy, intensity-modulated radiotherapy and microbeam radiation therapy is compared with other dosimetric techniques. In particular the application of MOSFET dosemeters in the characterisation and quality assurance of the steep dose gradients associated with the penumbra of some modern radiation oncology modalities is investigated. A new in vivo, on-line, scanning MOSFET read out system is also presented. The system has the ability to read out multiple MOSFET dosemeters with excellent spatial resolution and temperature stability and minimal slow border trapping effects. (author)
Characterization of phenolic pellets for ESR dosimetry in photon beam radiotherapy
International Nuclear Information System (INIS)
Gallo, Salvatore; Veronese, Ivan; Iacoviello, Giuseppina; Panzeca, Salvatore; Bartolotta, Antonio; Longo, Anna; Dondi, Daniele; Gueli, Anna Maria; Loi, Gianfranco; Mones, Eleonora; Marrale, Maurizio
2017-01-01
This work deals with the dosimetric features of a particular phenolic compound (IRGANOX 1076 registered ) for dosimetry of clinical photon beams by using electron spin resonance (ESR) spectroscopy. After the optimization of the ESR readout parameters (namely modulation amplitude and microwave power) to maximise the signal without excessive spectrum distortions, basic dosimetric properties of laboratory-made phenolic dosimeters in pellet form, such as reproducibility, dose-response, sensitivity, linearity and dose rate dependence were investigated. The dosimeters were tested by measuring the depth dose profile of a 6 MV photon beam. A satisfactory intra-batch reproducibility of the ESR signal of the manufactured dosimeters was obtained. The ESR signal proved to increase linearly with increasing dose in the investigated dose range 1-13 Gy. The presence of an intrinsic background signal limits the minimum detectable dose to a value of approximately 0.6 Gy. Reliable and accurate assessment of the dose was achieved, independently of the dose rate. Such characteristics, together with the fact that IRGANOX 1076 registered is almost tissue-equivalent, and the stability of the ESR signal, make these dosimeters promising materials for ESR dosimetric applications in radiotherapy. (orig.)
Characterization of phenolic pellets for ESR dosimetry in photon beam radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Gallo, Salvatore; Veronese, Ivan [Universita degli Studi di Milano, Department of Physics, Milan (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Milano (Italy); Iacoviello, Giuseppina [Hospital ARNAS-Civico, Medical Physics Department, Palermo (Italy); Panzeca, Salvatore [Universita degli Studi di Palermo, Department of Physics and Chemistry, Palermo (Italy); Istituto Nazionale di Fisica Nucleare-Sezione di Catania, Catania (Italy); Bartolotta, Antonio; Longo, Anna [Universita degli Studi di Palermo, Department of Physics and Chemistry, Palermo (Italy); Dondi, Daniele [Universita degli Studi di Pavia, Department of Chemistry, Pavia (Italy); Istituto Nazionale di Fisica Nucleare, Sezione di Pavia (Italy); Gueli, Anna Maria [Istituto Nazionale di Fisica Nucleare-Sezione di Catania, Catania (Italy); Universita degli Studi di Catania, Department of Physics and Astronomy, PH3DRA Laboratories, Catania (Italy); Loi, Gianfranco; Mones, Eleonora [Azienda Ospedaliero Universitaria Maggiore della Carita, Medical Physics Department, Novara (Italy); Marrale, Maurizio [Universita degli Studi di Palermo, Department of Physics and Chemistry, Palermo (Italy); Istituto Nazionale di Fisica Nucleare-Sezione di Catania, Catania (Italy); Universita degli Studi di Palermo, Advanced Technologies Network Center (ATeN Center), Palermo (Italy)
2017-11-15
This work deals with the dosimetric features of a particular phenolic compound (IRGANOX 1076 {sup registered}) for dosimetry of clinical photon beams by using electron spin resonance (ESR) spectroscopy. After the optimization of the ESR readout parameters (namely modulation amplitude and microwave power) to maximise the signal without excessive spectrum distortions, basic dosimetric properties of laboratory-made phenolic dosimeters in pellet form, such as reproducibility, dose-response, sensitivity, linearity and dose rate dependence were investigated. The dosimeters were tested by measuring the depth dose profile of a 6 MV photon beam. A satisfactory intra-batch reproducibility of the ESR signal of the manufactured dosimeters was obtained. The ESR signal proved to increase linearly with increasing dose in the investigated dose range 1-13 Gy. The presence of an intrinsic background signal limits the minimum detectable dose to a value of approximately 0.6 Gy. Reliable and accurate assessment of the dose was achieved, independently of the dose rate. Such characteristics, together with the fact that IRGANOX 1076 {sup registered} is almost tissue-equivalent, and the stability of the ESR signal, make these dosimeters promising materials for ESR dosimetric applications in radiotherapy. (orig.)
TLD audit in radiotherapy in the Czech Republic
International Nuclear Information System (INIS)
Kroutilikova, D.; Zackova, H.; Judas, L.
1998-01-01
National Radiation Protection Institute in Prague organizes the TLD audit. The aim of the TLD postal audit is to provide control of the clinical dosimetry in the Czech Republic for purposes of state supervision in radiotherapy, to investigate and to reduce uncertainties involved in the measurements of absorbed dose and to improve consistency in dose determination in the regional radiotherapy centers. TLD audit covers absorbed dose measurements under reference conditions for 60 Co and 137 Cs beams, high-energy X-ray and electron beams of of linear accelerators and betatrons. The thermo-luminescence dosemeters are sent regularly to all radiotherapy centers. Absorbed dose measures by the TLD is compared to absorbed dose stated by radiotherapy center. Encapsulated LiF:Mg, Ti powder is used for the measurement. Deviation of 3% between stated and TLD measured dose is considered for photons and ±5% for electron beams. First TLD audit was started in 1997. A total of 135 beams was checked. There were found seven major deviations (more than ±6%), which were very carefully investigated. Medical Physicists from these departments reported a set-up mistake. However, at most of those hospitals with major deviations, an in situ audit in details was made soon after TLD audit. There were found discrepancies of clinical dosimetry but also bad technical state of some of the irradiation units. In 1998, second course TLD audit was started. No major deviation was found. Regular TLD audit seems to be a good way to eliminate big mistakes in the basic clinical dosimetry. Repeated audit in the regional radiotherapy centers that had major deviation during the first audit exhibited improvement of their dosimetry. It is intended to broaden the method and to control also beam parameters by means of a multi-purpose phantom. (authors)
Phantom dosimetry at 15 MV conformal radiation therapy
International Nuclear Information System (INIS)
Thompson, Larissa; Campos, Tarcisio P.R.; Dias, Humberto G.
2013-01-01
The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)
Phantom dosimetry at 15 MV conformal radiation therapy
International Nuclear Information System (INIS)
Thompson, Larissa; Campos, Tarcisio P.R.
2015-01-01
The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)
International Nuclear Information System (INIS)
Lo, Ching-Jung; Yang, Pei-Ying; Chao, Tsi-Chian; Tu, Shu-Ju
2015-01-01
In the treatment planning of radiation therapy, patients may be administrated with contrast media in CT scanning to assist physicians for accurate delineation of the target or organs. However, contrast media are not used in patients during the treatment delivery. In particular, contrast media contain materials with high atomic numbers and dosimetric variations may occur between scenarios where contrast media are present in treatment planning and absent in treatment delivery. In this study we evaluate the effect of contrast media on the dosimetry and biological consequence. An analytical phantom based on AAPM TG 119 and five sets of CT images from clinical patients are included. Different techniques of treatment planning are considered, including 1-field AP, 2-field AP+PA, 4-field box, 7-field IMRT, and RapidArc. RapidArc is a recent technique of volumetric modulated arc therapy and is used in our study of contrast media in clinical scenarios. The effect of RapidArc on dosimetry and biological consequence for administration of contrast media in radiotherapy is not discussed previously in literature. It is shown that dose difference is reduced as the number of external beams is increased, suggesting RapidArc may be favored to be used in the treatment planning enhanced by contrast media. Linear trend lines are fitted for assessment of percent dose differences in the planning target volume versus concentrations of contrast media between plans where contrast media are present and absent, respectively
International Nuclear Information System (INIS)
Racoveanu, N.T.
1981-01-01
Results of thermoluminescent dosimetry collected over 5 years in the Eastern Mediterranean region of WHO were analyzed in an attempt to improve clinical dosimetry. Data for 16 radiotherapy departments showed considerable inconsistencies. It was found that the clinical dosemeters used by 3 of the departments were not working properly. The remainder of the departments had one or more dosemeters in perfect working order but the procedure for measuring machine output was inadequate or the correction factors (pressure, temperature) were wrongly applied due to lack of reliable instruments for such measurements. Problems encountered in the sending and returning of TLD dosemeters for assessment are discussed
Thermoluminescence in medical dosimetry; Termoluminiscencia en dosimetria medica
Energy Technology Data Exchange (ETDEWEB)
Rivera, T., E-mail: trivera@ipn.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)
2011-10-15
The dosimetry by thermoluminescence (Tl) is applied in the entire world for the dosimetry of ionizing radiations specially to personal and medical dosimetry. This dosimetry method has been very interesting for measures in vivo because the Tl dosimeters have the advantage of being very sensitive in a very small volume and they are also equivalent to tissue and they do not need additional accessories (for example, cable, electrometer, etc.) The main characteristics of the diverse Tl materials to be used in the radiation measures and practical applications are: the Tl curve, the share homogeneity, the signal stability after the irradiation, precision and exactitude, the response in function with the dose and the energy influence. In this work a brief summary of the advances of the radiations dosimetry is presented by means of the thermally stimulated luminescence and its application to the dosimetry in radiotherapy. (Author)
Skin Dosimetry in Breast Teletherapy on a Phantom Anthropomorphic and Anthropometric Phantom
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Batista Nogueira, Luciana [Anatomy and Imaging Department, Federal University of Minas Gerais, Belo Horizonte (Brazil); Lemos Silva, Hugo Leonardo [Santa Casa Hospital, Belo Horizonte (Brazil); Donato da Silva, Sabrina; Passos Ribeiro Campos, Tarcisio [Nuclear Engineering Department, Federal University of Minas Gerais, Belo Horizonte (Brazil)
2015-07-01
This paper addresses the breast teletherapy dosimetry. The goal is to evaluate and compare absorbed doses in equivalent skin tissue, TE-skin, of an anthropomorphic and anthropometric breast phantom submitted to breast radiotherapy. The methodology involved the reproduction of a set of tomographic images of the phantom; the elaboration of conformational radiotherapy planning in the SOMAVISION and CadPlan (TPS) software; and the synthetic breast irradiation by parallel opposed fields in 3D conformal teletherapy at 6 MV linear accelerator Clinac-2100 C from VARIAN with prescribed dose (PD) of 180 cGy to the target volume (PTV), referent to the glandular tissue. Radiochromic films EBT2 were selected as dosimeters. Two independent calibration processes of films with solid water Gammex 457 plates and water filled box were produced. Curves of optical density (OD) versus absorbed dose were produced. Dosimeters were positioned in the external region of the breast phantom in contact with TE-skin, area of 4.0 cm{sup 2} each. The irradiation process was prepared in duplicate to check the reproducibility of the technique. The radiochromic films were scanned and their response in RGB (Red, Green, Blue) analyzed by the ImageJ software. The optical density was obtained and converted to dose based on the calibration curves. Thus, the spatial dose distribution in the skin was reproduced. The absorbed doses measured on the radiochromic films in TE-skin showed values between upper and lower quadrants at 9 o'clock in the range of 54% of PD, between the upper and lower quadrants 3 o'clock in the range of 72% and 6 o'clock at the lower quadrant in the range of 68 % of PD. The values are ±64% (p <0.05) according to the TPS. It is concluded that the depth dose measured in solid water plates or water box reproduce equivalent dose values for both calibration processes of the radiochromic films. It was observed that the skin received doses ranging from 50% to 78% of the
Development of targeted radiotherapy systems
International Nuclear Information System (INIS)
Ferro, Guillermina; Villarreal, Jose E.; Garcia, Laura; Tendilla, Jose I.; Paredes, Lydia; Murphy, Consuelo A.; Pedraza, Martha
2001-01-01
Conventional or external beam radiotherapy, has been a viable alternative for cancer treatment. Although this technique is effective, its use is limited if the patient has multiple malignant lesions (metastases). An alternative approach is based on the design of radiopharmaceuticals that, to be administered in the patient, are directed specifically toward the target cell producing a selective radiation delivery. This treatment is known as targeted radiotherapy. We have summarized and discussed some results related to our investigations on the development of targeted radiotherapy systems, including aspects of internal dosimetry
International Nuclear Information System (INIS)
Xing, A; Arumugam, S; Deshpande, S; George, A; Holloway, L; Vial, P; Goozee, G
2014-01-01
Purpose: The purpose of this project was to evaluate the performance of four commercially available dosimetry systems for Tomotherapy delivery quality assurance (DQA). Methods: Eight clinical patient plans were chosen to represent a range of treatment sites and typical clinical plans. Four DQA plans for each patient plan were created using the TomoTherapy DQA Station (Hi-Art version 4.2.1) on CT images of the ScandiDose Delta4, IBA MatriXX Evolution, PTW Octavius 4D and Sun Nuclear ArcCHECK phantoms. Each detector was calibrated following the manufacture-provided procedure. No angular response correction was applied. All DQA plans for each detector were delivered on the Tomotherapy Hi-Art unit in a single measurement session but on different days. The measured results were loaded into the vendor supplied software for each QA system for comparison with the TPS-calculated dose. The Gamma index was calculated using 3%/3mm, 2%/2mm with 10% dose threshold of maximum TPS calculated dose. Results: Four detector systems showed comparable gamma pass rates for 3%/3m, which is recommended by AAPM TG119 and commonly used within the radiotherapy community. The averaged pass rates ± standard deviation for all DQA plans were (98.35±1.97)% for ArcCHECK, (99.9%±0.87)% for Matrix, (98.5%±5.09)% for Octavius 4D, (98.7%±1.27)% for Delata4. The rank of the gamma pass rate for individual plans was consistent between detectors. Using 2%/2mm Gamma criteria for analysis, the Gamma pass rate decreased on average by 9%, 8%, 6.6% and 5% respectively. Profile and Gamma failure map analysis using the software tools from each dosimetry system indicated that decreased passing rate is mainly due to the threading effect of Tomo plan. Conclusion: Despite the variation in detector type and resolution, phantom geometry and software implementation, the four systems demonstrated similar dosimetric performance, with the rank of the gamma pass rate consistent for the plans considered
International Nuclear Information System (INIS)
Ozsahin, M.; Ugurluer, G.; Ballerini, G.; Letenneur, G.; Zouhair, A.; Mirimanoff, R.O.
2009-01-01
A dosimetry comparison was made between helical tomo-therapy, I.M.R.T. and classical conformal three dimensional radiotherapy for twelve first patients that received a image guided radiotherapy, the toxicity was tackled with a minimum follow-up of fourteen months. In conclusion, the CT-guided radiotherapy allows to save organs at risks superior to I.M.R.T. and conformal radiotherapy and a best homogeneity in the target volume. the toxicity is moderated and the break time is limited. (N.C.)
Why is a high accuracy needed in dosimetry
International Nuclear Information System (INIS)
Lanzl, L.H.
1976-01-01
Dose and exposure intercomparisons on a national or international basis have become an important component of quality assurance in the practice of good radiotherapy. A high degree of accuracy of γ and x radiation dosimetry is essential in our international society, where medical information is so readily exchanged and used. The value of accurate dosimetry lies mainly in the avoidance of complications in normal tissue and an optimal degree of tumor control
Physical fundamentals of the application of heavy charged particles in radiotherapy
International Nuclear Information System (INIS)
Bueche, G.
1977-01-01
In the chapter 'Medical Applications' A 'Radiotherapy' of the study, the following subjects are treated in detail by various authors: Physical fundamentals of the application of heavy charged particles in radiotherapy-radiation-biological fundamentals; clinical aspects of radiotherapy with protons and negative pions; patients and clinical dosimetry. (MG) [de
The physics of small megavoltage photon beam dosimetry.
Andreo, Pedro
2018-02-01
The increased interest during recent years in the use of small megavoltage photon beams in advanced radiotherapy techniques has led to the development of dosimetry recommendations by different national and international organizations. Their requirement of data suitable for the different clinical options available, regarding treatment units and dosimetry equipment, has generated a considerable amount of research by the scientific community during the last decade. The multiple publications in the field have led not only to the availability of new invaluable data, but have also contributed substantially to an improved understanding of the physics of their dosimetry. This work provides an overview of the most important aspects that govern the physics of small megavoltage photon beam dosimetry. Copyright © 2017 Elsevier B.V. All rights reserved.
INL Advanced Radiotherapy Research Program Annual Report 2004
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James Venhuizen
2005-06-01
This report summarizes the activities and major accomplishments for the Idaho National Laboratory Advanced Radiotherapy Research Program for calendar year 2004. Topics covered include boron analysis in biological samples, computational dosimetry and treatment planning software development, medical neutron source development and characterization, and collaborative dosimetry studies at the RA-1 facility in Buenos Aires, Argentina.
International Nuclear Information System (INIS)
Trindade, Bruno Machado
2011-02-01
This work shows the remodeling of the Computer System for Dosimetry of Neutrons and Photons in Radiotherapy Based on Stochastic Methods . SISCODES. The initial description and status, the alterations and expansions (proposed and concluded), and the latest system development status are shown. The SISCODES is a system that allows the execution of a 3D computational planning in radiation therapy, based on MCNP5 nuclear particle transport code. The SISCODES provides tools to build a patient's voxels model, to define a treatment planning, to simulate this planning, and to view the results of the simulation. The SISCODES implements a database of tissues, sources and nuclear data and an interface to access then. The graphical SISCODES modules were rewritten or were implemented using C++ language and GTKmm library. Studies about dose deviations were performed simulating a homogeneous water phantom as analogue of the human body in radiotherapy planning and a heterogeneous voxel phantom, pointing out possible dose miscalculations. The Soft-RT and PROPLAN computer codes that do interface with SISCODES are described. A set of voxels models created on the SISCODES are presented with its respective sizes and resolutions. To demonstrate the use of SISCODES, examples of radiation therapy and dosimetry simulations for prostate and heart are shown. Three protocols were simulated on the heart voxel model: Sm-153 filled balloon and P-32 stent, to prevent angioplasty restenosis; and Tl-201 myocardial perfusion, to imaging. Teletherapy with 6MV and 15MV beams were simulated to the prostate, and brachytherapy with I-125 seeds. The results of these simulations are shown on isodose curves and on dose-volume histograms. The SISCODES shows to be a useful tool for research of new radiation therapy treatments and, in future, can also be useful in medical practice. At the end, future improvements are proposed. I hope this work can contribute to develop more effective radiation therapy
Clinical dosimetry in molecular radiotherapy: protocol optimization and clinical implementation
International Nuclear Information System (INIS)
Ferrer, Ludovic
2011-01-01
Molecular radiotherapy (mrt) consists in destructing tumour targets by radiolabelled vectors. This nuclear medicine specialty is being considered with increasing interest for example via the success achieved in the treatment of non-Hodgkin lymphomas by radioimmunotherapy. One of the keys of mrt optimization relies on the personalising of absorbed doses delivered to the patient: This is required to ascertain that irradiation is focused on tumour cells while keeping surrounding healthy tissue irradiation at an acceptable - non-toxic - level. Radiation dose evaluation in mrt requires in one hand, the spatial and temporal localization of injected radioactive sources by scintigraphic imaging, and on a second hand, the knowledge of the emitted radiation propagating media, given by CT imaging. Global accuracy relies on the accuracy of each of the steps that contribute to clinical dosimetry. There is no reference, standardized dosimetric protocol to date. Due to heterogeneous implementations, evaluation of the accuracy of the absorbed dose is a difficult task. In this thesis, we developed and evaluated different dosimetric approaches that allow us to find a relationship between the absorbed dose to the bone marrow and haematological toxicity. Besides, we built a scientific project, called DosiTest, which aims at evaluating the impact of the various step that contribute to the realization of a dosimetric study, by means of a virtual multicentric comparison based on Monte-Carlo modelling. (author) [fr
Dosimetry in radiotherapy and brachytherapy by Monte-Carlo GATE simulation on computing grid
International Nuclear Information System (INIS)
Thiam, Ch.O.
2007-10-01
Accurate radiotherapy treatment requires the delivery of a precise dose to the tumour volume and a good knowledge of the dose deposit to the neighbouring zones. Computation of the treatments is usually carried out by a Treatment Planning System (T.P.S.) which needs to be precise and fast. The G.A.T.E. platform for Monte-Carlo simulation based on G.E.A.N.T.4 is an emerging tool for nuclear medicine application that provides functionalities for fast and reliable dosimetric calculations. In this thesis, we studied in parallel a validation of the G.A.T.E. platform for the modelling of electrons and photons low energy sources and the optimized use of grid infrastructures to reduce simulations computing time. G.A.T.E. was validated for the dose calculation of point kernels for mono-energetic electrons and compared with the results of other Monte-Carlo studies. A detailed study was made on the energy deposit during electrons transport in G.E.A.N.T.4. In order to validate G.A.T.E. for very low energy photons (<35 keV), three models of radioactive sources used in brachytherapy and containing iodine 125 (2301 of Best Medical International; Symmetra of Uro- Med/Bebig and 6711 of Amersham) were simulated. Our results were analyzed according to the recommendations of task group No43 of American Association of Physicists in Medicine (A.A.P.M.). They show a good agreement between G.A.T.E., the reference studies and A.A.P.M. recommended values. The use of Monte-Carlo simulations for a better definition of the dose deposited in the tumour volumes requires long computing time. In order to reduce it, we exploited E.G.E.E. grid infrastructure where simulations are distributed using innovative technologies taking into account the grid status. Time necessary for the computing of a radiotherapy planning simulation using electrons was reduced by a factor 30. A Web platform based on G.E.N.I.U.S. portal was developed to make easily available all the methods to submit and manage G
Villani, N; Gérard, K; Marchesi, V; Huger, S; François, P; Noël, A
2010-06-01
The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (IMRT) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. At Alexis-Vautrin center, pretreatment quality controls in IMRT for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multileaf collimator). Correlation between dose measured at one point, given with the EPID and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. The study allowed to demonstrate the feasibility to reduce the time devoted to
International Nuclear Information System (INIS)
Villani, N.; Noel, A.; Villani, N.; Gerard, K.; Marchesi, V.; Huger, S.; Noel, A.; Francois, P.
2010-01-01
Purpose The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (I.M.R.T.) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. Patients and methods At Alexis-Vautrin center, pretreatment quality controls in I.M.R.T. for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. Results Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multi-leaf collimator). Correlation between dose measured at one point, given with the E.P.I.D. and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. Conclusion The study allowed to
DEFF Research Database (Denmark)
Hansen, Nikolaj Lervad; Nissen, Jakob N.; Hamberger, Björn Robert
2017-01-01
residue gave mixed product profiles. Two mutants, TwTPS14:Y265H and TwTPS21:A325V, also produced ent-copalyl diphosphate, highlighting the evolutionary potential of enzymes of this family to drive rapid diversification of plant diterpene biosynthesis through neo-functionalization. Our study contributes......The medicinal plant Tripterygium wilfordii (Celastraceae) contains a pair of class II diterpene synthases (diTPS) of specialized labdane-type metabolism that, despite remarkably close homology, form strikingly different products. TwTPS21 catalyzes bicyclization of the linear C20 precursor......-directed mutagenesis, we generated a panel of six variants, where one, or both positions were exchanged between the enzymes. In coupled heterologous assays with a corresponding class I diTPS, TwTPS2, complete product interchange was observed in variants with both reciprocal mutations, while substitutions of either...
In vivo dosimetry: measurement of entrance and exit dose using MOSFET dosimeter
International Nuclear Information System (INIS)
Gopiraj, A.; Billimagga, Ramesh S.; Rekha, M.; Ramasubramaniam, V.
2007-01-01
Patient dose verification is an essential part of a Quality Assurance (QA) program in a Radiotherapy Department. As the transition is made from the conventional two-dimensional (2D) to three-dimensional (3D) conformal and intensity modulated therapy, it is recommended that new treatment techniques be checked systematically to guarantee accurate dose delivery by means of a comprehensive in vivo dosimetry program (i.e. real-time dosimetry during patient treatment). The authors conducted a study to assess the clinical utility of in vivo dosimetry in the Dept. of Radiation Oncology using MOSFET dosimetry system
Dosimetry of clinical neutron and proton beams: An overview of recommendations
International Nuclear Information System (INIS)
Vynckier, S.
2004-01-01
Neutron therapy beams are obtained by accelerating protons or deuterons on Beryllium. These neutron therapy beams present comparable dosimetric characteristics as those for photon beams obtained with linear accelerators; for instance, the penetration of a p(65) + Be neutron beam is comparable with the penetration of an 8 MV photon beam. In order to be competitive with conventional photon beam therapy, the dosimetric characteristics of the neutron beam should therefore not deviate too much from the photon beam characteristics. This paper presents a brief summary of the neutron beams used in radiotherapy. The dosimetry of the clinical neutron beams is described. Finally, recent and future developments in the field of physics for neutron therapy is mentioned. In the last two decades, a considerable number of centres have established radiotherapy treatment facilities using proton beams with energies between 50 and 250 MeV. Clinical applications require a relatively uniform dose to be delivered to the volume to be treated, and for this purpose the proton beam has to be spread out, both laterally and in depth. The technique is called 'beam modulation' and creates a region of high dose uniformity referred to as the 'spread-out Bragg peak'. Meanwhile, reference dosimetry in these beams had to catch up with photon and electron beams for which a much longer tradition of dosimetry exists. Proton beam dosimetry can be performed using different types of dosemeters, such as calorimeters, Faraday cups, track detectors and ionisation chambers. National standard dosimetry laboratories will, however, not provide a standard for the dosimetry of proton beams. To achieve uniformity on an international level, the use of an ionisation chamber should be considered. This paper reviews and summarises the basic principles and recommendations for the absorbed dose determination in a proton beam, utilising ionisation chambers calibrated in terms of absorbed dose to water. These recommendations
International Nuclear Information System (INIS)
Rosenwald, Jean Claude; Bonvalet, Laurent; Mazurier, Jocelyne; Metayer, Christine; Beaudre, Anne; Garcia, Robin; Ruchaud, Romain; Dedieu, Veronique; Bramoulle, Celine; Caselles, Olivier; Lacaze, Brigitte; Mazurier, Jocelyne
2010-01-01
This report aims at bringing risks related to the use of Treatment Planning Systems (TPS) to the attention of French medical physicists, and to provide them with practical, precise and updated recommendations related to new legal requirements on commissioning and use of a new planning system. It addresses TPS used in external radiation therapy. It is based on various international (IAEA, ESTRO, AAPM, and so on) and national recommendations, and proposes some rules of good practices for the implementation of a quality insurance policy as well as for the procurement and implementation of a new planning system, as for the performance follow-up of an already installed system. The authors address the following issues: risks associated with the use of a TPS, organisational aspects, dose calculation algorithms and required precision, TPS acceptance, adjustment and tests, periodic controls, treatment plan verification procedures
In vivo dosimetry in radiation therapy in Sweden; In vivo-dosimetri inom straalbehandling i Sverige
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Eriksson, Jacob; Blomquist, Michael (Norrlands universitetssjukhus, Umeaa (Sweden))
2010-07-15
A prerequisite for achieving high radiation safety for patients receiving external beam radiation therapy is that the hospitals have a quality assurance program. The program should include include monitoring of the radiation dose given to the patient. Control measurements are performed both at the system level and at the individual level. Control measurement is normally performed using in vivo dosimetry, e.g. a method to measure the radiation dose at the individual level during the actual radiation treatment time. In vivo dosimetry has proven to be an important tool to detect and prevent serious errors in patient treatment. The purpose of this research project was to identify the extent to which vivo dosimetry is used and the methods available for this at Swedish radiation therapy clinics. The authority also wanted to get an overall picture of how hospitals manage results of in vivo dosimetry, and how clinics control radiation dose when using modern treatment techniques. The report reflects the situation in Swedish radiotherapy clinics 2007. The report shows that all hospitals use some form of in vivo dosimetry. The instruments used are mainly diodes and termoluminiscence dosimeters
Thermoluminescence dosimetry and its applications in medicine. Part 2: history and applications
International Nuclear Information System (INIS)
Kron, T.
1995-01-01
Thermoluminescence dosimetry (TLD) has been available for dosimetry of ionising radiation for nearly 100 years. The variety of materials and their different physical forms allow the determination of different radiation qualities over a wide range of absorbed dose. This makes TL dosimeters useful in radiation protection where dose levels of μ Gy are monitored as well as in radiotherapy where doses up to several Gray are to be measured. The major advantages of TL detectors are their small physical size and that no cables or auxiliary equipment is required during the dose assessment. TLD is considered to be a good method for point dose measurements in phantoms as well as for in vivo dosimetry on patients during radiotherapy treatment. As an integrative dosimetric technique, it can be applied to personal dosimetry and it lends itself to the determination of dose distributions due to multiple or moving radiation sources (e.g. conformal and dynamic radiotherapy, computed tomography). In addition, TL dosimeters are easy to transport, and they can be mailed. This makes them well suited for intercomparison of doses delivered in different institutions. The present article aims at describing the various applications TLD has found in medicine by taking into consideration the physics and practice of TLD measurements which have been discussed in the first part of this review. 198 refs., 4 tabs., 2 figs
Directory of Open Access Journals (Sweden)
Rajesh Kinhikar
2012-01-01
Full Text Available Introduction: The new diode Isorad was validated for intensity modulated radiotherapy (IMRT and the observations during the validation are reported. Materials and Methods: The validation includes intrinsic precision, post-irradiation stability, dose linearity, dose-rate effect, angular response, source to surface (SSD dependence, field size dependence, and dose calibration. Results: The intrinsic precision of the diode was more than 1% (1 σ. The linearity found in the whole range of dose analyzed was 1.93% (R 2 = 1. The minimum and maximum variation in the measured and calculated dose were found to be 0.78% (with 25 MU at ioscentre and 4.8% (with 1000 MU at isocentre, respectively. The maximal variation in angular response with respect to arbitrary angle 0° found was 1.31%. The diode exhibited a 51.7% and 35% decrease in the response in the 35 cm and 20 cm SSD range, respectively. The minimum and the maximum variation in the measured dose from the diode and calculated dose were 0.82% (5 cm × 5 cm and 3.75% (30 cm × 30 cm, respectively. At couch 270°, the response of the diode was found to vary maximum by 1.4% with 60 gantry angle. Mean variation between measured dose with diode and planned dose by TPS was found to be 1.3% (SD 0.75 for IMRT patient-specific quality assurance. Conclusion: For the evaluation of IMRT, use of cylindrical diode is strongly recommended.
International Nuclear Information System (INIS)
Perrot, Y; Donnarieix, D; Maigne, L; Degoul, F; Auzeloux, P; Bonnet, M; Cachin, F; Chezal, J M; Labarre, P; Moins, N; Papon, J; Rbah-Vidal, L; Vidal, A; Miot-Noirault, E
2014-01-01
The GATE Monte Carlo simulation platform based on the Geant4 toolkit is under constant improvement for dosimetric calculations. In this study, we explore its use for the dosimetry of the preclinical targeted radiotherapy of melanoma using a new specific melanin-targeting radiotracer labeled with iodine 131. Calculated absorbed fractions and S values for spheres and murine models (digital and CT-scan-based mouse phantoms) are compared between GATE and EGSnrc Monte Carlo codes considering monoenergetic electrons and the detailed energy spectrum of iodine 131. The behavior of Geant4 standard and low energy models is also tested. Following the different authors’ guidelines concerning the parameterization of electron physics models, this study demonstrates an agreement of 1.2% and 1.5% with EGSnrc, respectively, for the calculation of S values for small spheres and mouse phantoms. S values calculated with GATE are then used to compute the dose distribution in organs of interest using the activity distribution in mouse phantoms. This study gives the dosimetric data required for the translation of the new treatment to the clinic. (paper)
New TPS materials for aerocapture
International Nuclear Information System (INIS)
Laub, Bernard
2002-01-01
Many planetary probes, landers and aerocapture concepts are conceived for entry trajectories where peak convective heat flux is in the range 150-400 W/cm2. This may be too severe an environment for either reusable or low-density ablative materials. The high-density ablatives will work in such environments but the associated TPS weight requirements can be prohibitive. Unfortunately, there are few, if any, well-understood materials that provide reliable, predictable ablative performance for the 150-400 W/cm2 regime while still providing weight efficient TPS solutions. JPL has recently been evaluating an Earth aerocapture demonstration at an entry velocity of ≅10 km/s. TPS thickness and areal weight requirements were determined for current ablative TPS candidates (e.g., SLA-561V, PICA) where, for the large integrated heat loads associated with aerocapture, it is shown that some of these materials may not provide efficient thermal protection. A new concept, employing a low catalycity, high emissivity coating on a low-density ceramic tile is evaluated and shown to provide significant benefits for such missions
Wognum, S; Bondar, L; Zolnay, A G; Chai, X; Hulshof, M C C M; Hoogeman, M S; Bel, A
2013-02-01
Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors' unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight parameters were determined
International Nuclear Information System (INIS)
Wognum, S.; Chai, X.; Hulshof, M. C. C. M.; Bel, A.; Bondar, L.; Zolnay, A. G.; Hoogeman, M. S.
2013-01-01
Purpose: Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors’ unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. Methods: The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight
Energy Technology Data Exchange (ETDEWEB)
Wognum, S.; Chai, X.; Hulshof, M. C. C. M.; Bel, A. [Department of Radiotherapy, Academic Medical Center, Meiberdreef 9, 1105 AZ Amsterdam (Netherlands); Bondar, L.; Zolnay, A. G.; Hoogeman, M. S. [Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus Medical Center, Groene Hilledijk 301, 3075 EA Rotterdam (Netherlands)
2013-02-15
Purpose: Future developments in image guided adaptive radiotherapy (IGART) for bladder cancer require accurate deformable image registration techniques for the precise assessment of tumor and bladder motion and deformation that occur as a result of large bladder volume changes during the course of radiotherapy treatment. The aim was to employ an extended version of a point-based deformable registration algorithm that allows control over tissue-specific flexibility in combination with the authors' unique patient dataset, in order to overcome two major challenges of bladder cancer registration, i.e., the difficulty in accounting for the difference in flexibility between the bladder wall and tumor and the lack of visible anatomical landmarks for validation. Methods: The registration algorithm used in the current study is an extension of the symmetric-thin plate splines-robust point matching (S-TPS-RPM) algorithm, a symmetric feature-based registration method. The S-TPS-RPM algorithm has been previously extended to allow control over the degree of flexibility of different structures via a weight parameter. The extended weighted S-TPS-RPM algorithm was tested and validated on CT data (planning- and four to five repeat-CTs) of five urinary bladder cancer patients who received lipiodol injections before radiotherapy. The performance of the weighted S-TPS-RPM method, applied to bladder and tumor structures simultaneously, was compared with a previous version of the S-TPS-RPM algorithm applied to bladder wall structure alone and with a simultaneous nonweighted S-TPS-RPM registration of the bladder and tumor structures. Performance was assessed in terms of anatomical and geometric accuracy. The anatomical accuracy was calculated as the residual distance error (RDE) of the lipiodol markers and the geometric accuracy was determined by the surface distance, surface coverage, and inverse consistency errors. Optimal parameter values for the flexibility and bladder weight
IAEA/WHO postal dose audits for radiotherapy hospitals in Eastern and South-Eastern Europe
International Nuclear Information System (INIS)
Izewska, J.; Vatnitsky, S.; Shortt, K.R.
2004-01-01
The IAEA/WHO TLD programme has been in operation for 34 years. In this period the calibration of approximately 5200 high-energy photon beams in over 1300 radiotherapy hospitals in 115 countries worldwide was checked. Of these, 18% of the audits were performed in Eastern and South-Eastern Europe. There are large contrasts in the region; while the results are very good for most countries, a few countries struggle with basic problems in dosimetry. The hospitals operating radiotherapy services without qualified medical physicists or dosimetry equipment have poorer results than those properly equipped and staffed. Only about 2/3 of TLD audit participants in Eastern Europe have the appropriate dosimetry equipment. To achieve consistency of the audit results within Eastern and South-Eastern Europe, strengthening of radiotherapy infrastructure in a few countries would be necessary. (authors)
The work programme of EURADOS on internal and external dosimetry.
Rühm, W; Bottollier-Depois, J F; Gilvin, P; Harrison, R; Knežević, Ž; Lopez, M A; Tanner, R; Vargas, A; Woda, C
2018-01-01
Since the early 1980s, the European Radiation Dosimetry Group (EURADOS) has been maintaining a network of institutions interested in the dosimetry of ionising radiation. As of 2017, this network includes more than 70 institutions (research centres, dosimetry services, university institutes, etc.), and the EURADOS database lists more than 500 scientists who contribute to the EURADOS mission, which is to promote research and technical development in dosimetry and its implementation into practice, and to contribute to harmonisation of dosimetry in Europe and its conformance with international practices. The EURADOS working programme is organised into eight working groups dealing with environmental, computational, internal, and retrospective dosimetry; dosimetry in medical imaging; dosimetry in radiotherapy; dosimetry in high-energy radiation fields; and harmonisation of individual monitoring. Results are published as freely available EURADOS reports and in the peer-reviewed scientific literature. Moreover, EURADOS organises winter schools and training courses on various aspects relevant for radiation dosimetry, and formulates the strategic research needs in dosimetry important for Europe. This paper gives an overview on the most important EURADOS activities. More details can be found at www.eurados.org .
Majewsky, Marius; Wagner, Danny; Delay, Markus; Bräse, Stefan; Yargeau, Viviane; Horn, Harald
2014-10-20
Sulfonamide antibiotics undergo transformation in the aquatic environment through biodegradation, photolysis, or hydrolysis. In this study, the residual antibacterial activity of 11 transformation products (TPs) of sulfamethoxazole (SMX) was investigated with regard to their in vitro growth and luminescence inhibition on Vibrio fischeri (30 min and 24 h exposure). Two transformation products, 4-hydroxy-SMX and N(4)-hydroxy-acetyl-SMX, were synthesized in-house and confirmed by nuclear magnetic resonance and high-resolution mass spectrometry. Results of individual compound experiments showed that TPs modified at the para amino group still exhibit clear antibacterial effects, whereas TPs resulting from breakdown of the SMX structure lost this mechanism of action. 4-NO2- and 4-OH-SMX were found to inhibit growth to a clearly greater extent than the parent compound, SMX. In contrast, the N(4)-acetyl- and N(4)-hydroxy-acetyl-derivatives retain less than 10 and 5% of the effect of SMX on growth and luminescence inhibition, respectively. The effect of a mixture of para-modified TPs was observed to be additive. Considering the homologous series of sulfa drugs widely prescribed and their common mechanism of action, the potential environmental impact must consider the total amount of sulfonamide antibiotics and their derivative TPs, which might end up in a water body. Extrapolating the results obtained here for the para TPs of SMX to other sulfa drugs and determining the persistence and occurrence of these compounds in the aquatic environment is required for improved risk assessment.
Ongoing development of digital radiotherapy plan review tools
International Nuclear Information System (INIS)
Ebert, M.A.; Hatton, J.; Cornes, D.
2011-01-01
Full text: To describe ongoing development of software to support the review of radiotherapy treatment planning system (TPS) data. The 'SWAN' software program was conceived in 2000 and initially developed for the RADAR (TROG 03.04) prostate radiotherapy trial. Validation of the SWAN program has been occurring via implementation by TROG in support of multiple clinical trials. Development has continued and the SWAN software program is now supported by modular components which comprise the 'SW AN system'. This provides a comprehensive set of tools for the review, analysis and archive of TPS exports. The SWAN system has now been used in support of over 20 radiotherapy trials and to review the plans of over 2,000 trial participants. The use of the system for the RADAR trial is now culminating in the derivation of dose-outcomes indices for prostate treatment toxicity. Newly developed SWAN tools include enhanced remote data archive/retrieval, display of dose in both relative and absolute modes, and interfacing to a Matlab-based add-on ('VAST') that allows quantitative analysis of delineated volumes including regional overlap statistics for multi-observer studies. Efforts are continuing to develop the SWAN system in the context of international collaboration aimed at harmonising the quality-assurance activities of collaborative trials groups. Tools such as the SWAN system are essential for ensuring the collection of accurate and reliable evidence to guide future radiotherapy treatments. One of the principal challenges of developing such a tool is establishing a development path that will ensure its validity and applicability well into the future.
International Nuclear Information System (INIS)
Banos-Capilla, M. C.; Garcia, M. A.; Bea, J.; Pla, C.; Larrea, L.; Lopez, E.
2007-01-01
The quality of dosimetry in radiotherapy treatment requires the accurate delimitation of the gross tumor volume. This can be achieved by complementing the anatomical detail provided by CT images through fusion with other imaging modalities that provide additional metabolic and physiological information. Therefore, use of multiple imaging modalities for radiotherapy treatment planning requires an accurate image registration method. This work describes tests carried out on a Discovery LS positron emission/computed tomography (PET/CT) system by General Electric Medical Systems (GEMS), for its later use to obtain images to delimit the target in radiotherapy treatment. Several phantoms have been used to verify image correlation, in combination with fiducial markers, which were used as a system of external landmarks. We analyzed the geometrical accuracy of two different fusion methods with the images obtained with these phantoms. We first studied the fusion method used by the PET/CT system by GEMS (hardware fusion) on the basis that there is satisfactory coincidence between the reconstruction centers in CT and PET systems; and secondly the fiducial fusion, a registration method, by means of least-squares fitting algorithm of a landmark points system. The study concluded with the verification of the centroid position of some phantom components in both imaging modalities. Centroids were estimated through a calculation similar to center-of-mass, weighted by the value of the CT number and the uptake intensity in PET. The mean deviations found for the hardware fusion method were: vertical bar Δx vertical bar ±σ=3.3 mm±1.0 mm and vertical bar Δy vertical bar ±σ=3.6 mm±1.0 mm. These values were substantially improved upon applying fiducial fusion based on external landmark points: vertical bar Δx vertical bar ±σ=0.7 mm±0.8 mm and vertical bar Δy vertical bar ±σ=0.3 mm±1.7 mm. We also noted that differences found for each of the fusion methods were similar for
Recent developments in detectors/phantoms for dosimetry, X-ray quality assurance and imaging
International Nuclear Information System (INIS)
Sankaran, A.
2009-01-01
During the past years, many new developments have taken place in detectors/phantoms for high energy photon and electron dosimetry (for radiotherapy), protection monitoring, X-ray quality assurance and X-ray imaging (for radiodiagnosis). A variety of detectors and systems, quality assurance (QA) gadgets and special phantoms have been developed for diverse applications. This paper discusses the important developments with some of which the author was actively associated in the past. For dosimetry and QA of 60 Co and high energy X-ray units, state-of-the-art radiation field analyzers, matrix ion chambers, MOSFET devices and Gafchromic films are described. OSL detectors find wide use in radiotherapy dosimetry and provide a good alternative for personnel monitoring. New systems introduced for QA/dosimetry of X-ray units and CT scanners include: multi-function instruments for simultaneous measurement of kVp, dose, time, X-ray waveform and HVT on diagnostic X-ray units; pencil chamber with head and body phantoms for CTDI check on CT scanners. Examples of phantoms used for dosimetry and imaging are given. Advancements in the field of diagnostic X-ray imaging (with applications in portal imaging/dosimetry of megavoltage X-ray units) have led to emergence of: film-replacement systems employing CCD-scintillator arrays, computed radiography (CR) using storage phosphor plate; digital radiography (DR), using a pixel-matrix of amorphous selenium, or amorphous silicon diode coupled to scintillator. All these provide (a) in radiotherapy, accurate dose delivery to tumour, saving the surrounding tissues and (b) in radiodiagnosis, superior image quality with low patient exposure. Lastly, iPODs and flash drives are utilized for storage of gigabyte-size images encountered in medical and allied fields. Although oriented towards medical applications, some of these have been of great utility in other fields, such as industrial radiography as well as a host of other research areas. (author)
Assessment of national dosimetry quality audits results for teletherapy machines from 1989 to 2015.
Muhammad, Wazir; Ullah, Asad; Mahmood, Khalid; Matiullah
2016-01-01
The purpose of this study was to ensure accuracy in radiation dose delivery, external dosimetry quality audit has an equal importance with routine dosimetry performed at clinics. To do so, dosimetry quality audit was organized by the Secondary Standard Dosimetry Laboratory (SSDL) of Pakistan Institute of Nuclear Science and Technology (PINSTECH) at the national level to investigate and minimize uncertainties involved in the measurement of absorbed dose, and to improve the accuracy of dose measurement at different radiotherapy hospitals. A total of 181 dosimetry quality audits (i.e., 102 of Co-60 and 79 of linear accelerators) for teletherapy units installed at 22 different sites were performed from 1989 to 2015. The percent deviation between users’ calculated/stated dose and evaluated dose (in the result of on-site dosimetry visits) were calculated and the results were analyzed with respect to the limits of ± 2.5% (ICRU "optimal model") ± 3.0% (IAEA on-site dosimetry visits limit) and ± 5.0% (ICRU minimal or "lowest acceptable" model). The results showed that out of 181 total on-site dosimetry visits, 20.44%, 16.02%, and 4.42% were out of acceptable limits of ± 2.5% ± 3.0%, and ± 5.0%, respectively. The importance of a proper ongoing quality assurance program, recommendations of the followed protocols, and properly calibrated thermometers, pressure gauges, and humidity meters at radiotherapy hospitals are essential in maintaining consistency and uniformity of absorbed dose measurements for precision in dose delivery.
Modeling of the metallic port in breast tissue expanders for photon radiotherapy.
Yoon, Jihyung; Xie, Yibo; Heins, David; Zhang, Rui
2018-03-30
The purpose of this study was to model the metallic port in breast tissue expanders and to improve the accuracy of dose calculations in a commercial photon treatment planning system (TPS). The density of the model was determined by comparing TPS calculations and ion chamber (IC) measurements. The model was further validated and compared with two widely used clinical models by using a simplified anthropomorphic phantom and thermoluminescent dosimeters (TLD) measurements. Dose perturbations and target coverage for a single postmastectomy radiotherapy (PMRT) patient were also evaluated. The dimensions of the metallic port model were determined to be 1.75 cm in diameter and 5 mm in thickness. The density of the port was adjusted to be 7.5 g/cm 3 which minimized the differences between IC measurements and TPS calculations. Using the simplified anthropomorphic phantom, we found the TPS calculated point doses based on the new model were in agreement with TLD measurements within 5.0% and were more accurate than doses calculated based on the clinical models. Based on the photon treatment plans for a real patient, we found that the metallic port has a negligible dosimetric impact on chest wall, while the port introduced significant dose shadow in skin area. The current clinical port models either overestimate or underestimate the attenuation from the metallic port, and the dose perturbation depends on the plan and the model in a complex way. TPS calculations based on our model of the metallic port showed good agreement with measurements for all cases. This new model could improve the accuracy of dose calculations for PMRT patients who have temporary tissue expanders implanted during radiotherapy and could potentially reduce the risk of complications after the treatment. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.
Energy Technology Data Exchange (ETDEWEB)
Villani, N.; Noel, A. [Laboratoire de recherche en radiophysique, CRAN UMR 7039, Nancy universite-CNRS, 54 - Vandoeuvre-les-Nancy (France); Villani, N.; Gerard, K.; Marchesi, V.; Huger, S.; Noel, A. [Departement de radiophysique, centre Alexis-Vautrin, 54 - Vandoeuvre-les-Nancy (France); Francois, P. [Institut Curie, 75 - Paris (France)
2010-06-15
Purpose The first purpose of this study was to illustrate the contribution of statistical process control for a better security in intensity modulated radiotherapy (I.M.R.T.) treatments. This improvement is possible by controlling the dose delivery process, characterized by pretreatment quality control results. So, it is necessary to put under control portal dosimetry measurements (currently, the ionisation chamber measurements were already monitored by statistical process control thanks to statistical process control tools). The second objective was to state whether it is possible to substitute ionisation chamber with portal dosimetry in order to optimize time devoted to pretreatment quality control. Patients and methods At Alexis-Vautrin center, pretreatment quality controls in I.M.R.T. for prostate and head and neck treatments were performed for each beam of each patient. These controls were made with an ionisation chamber, which is the reference detector for the absolute dose measurement, and with portal dosimetry for the verification of dose distribution. Statistical process control is a statistical analysis method, coming from industry, used to control and improve the studied process quality. It uses graphic tools as control maps to follow-up process, warning the operator in case of failure, and quantitative tools to evaluate the process toward its ability to respect guidelines: this is the capability study. The study was performed on 450 head and neck beams and on 100 prostate beams. Results Control charts, showing drifts, both slow and weak, and also both strong and fast, of mean and standard deviation have been established and have shown special cause introduced (manual shift of the leaf gap of the multi-leaf collimator). Correlation between dose measured at one point, given with the E.P.I.D. and the ionisation chamber has been evaluated at more than 97% and disagreement cases between the two measurements were identified. Conclusion The study allowed to
Experimental IMRT breast dosimetry in a thorax phantom
International Nuclear Information System (INIS)
Pimenta, Elsa B.; Campos, Tarcisio P.R.; Nogueira, Luciana B.; Lima, Andre C.S.
2017-01-01
Radiation therapy (RT) is an essential therapeutic method. RT is often used as adjuvant therapy in the treatment of breast cancer. The dose-volume restrictions of the organs at risk limit the prescribed dose to the target volume and biological and clinical effects may influence the final treatment outcome. The breast RT provides large risks to the adjacent organs and consequently the recommended dosimetry to the prescribed dose volume (PTV) is 50 Gy, lower than the most prescribed dose in other treatments (70-85 Gy). Such values implies in less tumor control compared to other sites. The present research proposal aimed to measure absorbed dose in a thorax phantom with synthetic breasts provided by an Intensity-Modulate Radiation Therapy (IMRT) protocol in a RT center. On the methodology, IMRT protocol was selected following recommendations from the Radiation Therapy Oncology Group (RTOG). Radiochromic films and a thorax simulator were prepared by the Ionizing Radiation Research Group (NRI). Dosimeters were calibrated on a selected linear accelerator (LINAC). The comparison of the dosimetry from treatment planning system (TPS), Xio (Elekta) and from experimental data was performed. The spatial distribution of the breast internal dose and in the adjacent organs was depicted by the experimental data. In the film's calibration, the quadratic polynomial fit presented a satisfactory coefficient. Two-dimensional dose profiles were obtained in the breast suggesting that films can supply details and information that TPS does not provide. At the phantom's dosimetry, the internal mean doses taken at the synthetic breast presented usual values above the prescribed dose, besides overall values were within the dosimetric MSKCC criterion. The non full reproduction of the build-up region in the films had occurred due to the asymmetrical positioning of the films in the inner breast, in addition to their non constant distance from the skin. The hot regions were present may be due to
International Nuclear Information System (INIS)
2007-03-01
The IAEA has a long standing history of providing support and assistance for radiotherapy dosimetry audits in Member States, for educating and training radiotherapy professionals, and for reviewing the radiotherapy process in a variety of situations. Since 1969, and in collaboration with the World Health Organization (WHO), the IAEA has implemented a dosimetry audit service using mailed thermoluminescent dosimeters (TLD) to verify the calibration of radiotherapy beams in hospitals in Member States. The IAEA/WHO TLD service aims at improving the accuracy and consistency of clinical radiotherapy dosimetry worldwide. Detailed follow-up procedures have been implemented for correcting incorrect beam calibrations. When necessary, on-site visits by IAEA experts in radiotherapy physics are organized to identify and rectify dosimetry problems in hospitals. The IAEA has also been requested to organize expert missions in response to problems found during the radiation treatment planning process. Assessment of the doses received by affected patients and a medical assessment were undertaken when appropriate. Although vital for the radiotherapy process, accurate beam dosimetry and treatment planning alone cannot guarantee the successful treatment of a patient. The quality assurance (QA) of the entire radiotherapy process has to be taken into account. Hence, a new approach has been developed and named 'Quality Assurance Team for Radiation Oncology (QUATRO)'. The principal aim of QUATRO is to review the radiotherapy process, including the organization, infrastructure, clinical and medical physics aspects of the radiotherapy services. It also includes reviewing the hospital's professional competence, with a view to quality improvement. The QUATRO methodology is described in the IAEA publication Comprehensive Audits of Radiotherapy Practices: A Tool for Quality Improvement. QUATRO, in addition, offers assistance in the resolution of suspected or actual dose misadministrations (over
Energy Technology Data Exchange (ETDEWEB)
Lee, Jason Joon Bock; Choi, Jin Hyun; Lee, Ik Jae; Park, Kwang Woo; Kim, Kang Pyo; Kim, Jun Won [Dept. of Radiation Oncology, Yonsei University College of Medicine, Seoul (Korea, Republic of); Ahn, Sung Gwe; Jeong, Joon [Dept. of Surgery, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of)
2017-06-15
To report the results of a correlation analysis of skin dose assessed by in vivo dosimetry and the incidence of acute toxicity. This is a phase 2 trial evaluating the feasibility of intraoperative radiotherapy (IORT) as a boost for breast cancer patients. Eligible patients were treated with IORT of 20 Gy followed by whole breast irradiation (WBI) of 46 Gy. A total of 55 patients with a minimum follow-up of 1 month after WBI were evaluated. Optically stimulated luminescence dosimeter (OSLD) detected radiation dose delivered to the skin during IORT. Acute toxicity was recorded according to the Common Terminology Criteria for Adverse Events v4.0. Clinical parameters were correlated with seroma formation and maximum skin dose. Median follow-up after IORT was 25.9 weeks (range, 12.7 to 50.3 weeks). Prior to WBI, only one patient developed acute toxicity. Following WBI, 30 patients experienced grade 1 skin toxicity and three patients had grade 2 skin toxicity. Skin dose during IORT exceeded 5 Gy in two patients: with grade 2 complications around the surgical scar in one patient who received 8.42 Gy. Breast volume on preoperative images (p = 0.001), ratio of applicator diameter and breast volume (p = 0.002), and distance between skin and tumor (p = 0.003) showed significant correlations with maximum skin dose. IORT as a boost was well-tolerated among Korean women without severe acute complication. In vivo dosimetry with OSLD can help ensure safe delivery of IORT as a boost.
Dosimetry of radiolabeled monoclonal antibodies used for therapy
International Nuclear Information System (INIS)
Myers, M.J.; Hooker, G.R.; Epenetos, A.A.
1986-01-01
The present state of radiotherapy using labeled antibodies is reviewed. From the point of view of dosimetry, antibody therapy does not seem to have reached a stable and practicable enough state to provide an input to any but rather tentative dosimetry models. These, therefore, should not be taken too far until the problems of antibody targeting have been more fully developed. Some of the instrumental techniques for acquiring dosimetric data under clinical conditions are discussed as are some of the techniques of therapy in use today. 8 references, 3 figures
International Nuclear Information System (INIS)
Boissard, Philippe
2012-01-01
In vivo dose verification is used to prevent major deviations between the prescribed dose and the dose really delivered to the patient. This quality control was, nationally and internationally, widely recommended by scientific organizations. In France, its implementation and its use are now regulated. To do this, small detectors are fixed on the patient skin at the beginning of the treatment. However, the treatment delay is increased and not all treatment techniques could be assessed, such as IMRT plans (Intensity Modulated Radiation Therapy). In this context, Transit dosimetry performed with Electronic Portal Imaging Devices (EPIDs) appears as an interesting alternative for in vivo dose verification. During the treatment session, a transit dose is measured with the EPID, in two dimensions, and the dose in the patient is estimated from back projection of the portal dose. This work presents a quick and simple alternative method for verification of dose delivered to the patient using photon beams. Verifications in cases of complexes patient shapes and Intensity Modulated Radiation Therapy (IMRT) have been improved by using a Clarkson-Cunningham's integration method. 46 phantom test cases were designed to assess the accuracy of the method for 4, 6, 10 and 20 MV photon beams. For some points of interest the dose reconstructed by the method is compared to the dose measured with an ionization chamber. An additional in vivo uncertainty due to day to day deviations is defined and investigated. In the same time, a clinical study was driven during three years. In vivo dosimetry was performed for 494 patients treated for various tumors sites. Most of the patients were treated for a prostate cancer using IMRT. The in vivo dose is here compared to the dose calculated by the Treatment Planning System, TPS. The results of these two ways of validations are within the accepted tolerance of classical in vivo dosimetry. From the phantom study, we have estimated that the standard
Study of a 3D dosimetry system response: ARCCHECK®
Energy Technology Data Exchange (ETDEWEB)
Mazer, Amanda C.; Yoriyaz, Hélio, E-mail: amandamazer18@gmail.com, E-mail: hyoriyaz@ipen.br [Instituto de Pesquisas Energéticas e Nucleares (IPEN/CNEN-SP), São Paulo, SP (Brazil); Nakandakari, Marcos V.N., E-mail: marcos.sake@gmail.com [Beneficência Portuguesa de São Paulo, SP (Brazil)
2017-07-01
Ionizing radiation therapies have improved over the years, becoming more specific for each patient. Thereby as the treatment planning system (TPS) complexities increases, the quality assurance (QA) methods have to be in a constant evolution. One of the techniques that demand great complexity is the Volumetric Modulated Arc Therapy (VMAT). One possible way to VMAT commissioning is using 3D dosimetry systems and recently a new 3D dosimetry system called ArcCheck had been developed and commercialized mainly for VMAT quality assurance. It is water-equivalent and composed by an array of 1386 diodes arranged in a spiral pattern. Since simulation methods, like Monte Carlo method, ensure highly accurate results, MCNP (A General Monte Carlo N-Particle Transport Code System) is totally reliable for problems that involve radiation transport. This work presents a preliminary study of the 3D dosimetry system ArcCheck by developing two computational models in MCNP6. In addition, experimental measures were acquired using the ArcCheck in a Linear Accelerator and then these values were compared with the results obtained by simulations of both models. The comparisons showed good reproducibility. (author)
Initiation of conformal radiotherapy with a multileaf-collimator - An approach to clinical routine
International Nuclear Information System (INIS)
Bannach, B.; Doll, Th.; Pape, H.; Schmitt, G.
1995-01-01
The implementation of a three-dimensional conformal radiotherapy facility in the radiotherapy department of the Heinrich Heine University is described. Complex radiotherapy techniques with commercially available networked systems are introduced to improve clinical work. Over 18 month we have gained clinical experience with a PHILIPS Multileaf Collimator (MLC) mounted on a SL 25 linear accelerator. For a limited period the MLC was used as a conventional blocking device. The standard MLC-shapes are controlled with a stand-alone computer system. In addition, a three-dimensional treatment planning system (3-D-TPS / TMS-Radix, Helax AB) based on convolution/superposition algorithms was recently installed. Treatment optimization is achieved using static field arrangements with complete volumetric computerized tomographic patient data for 3-D-TPS. Conformal adaptation of the 95%-isodose to the Planning Target Volume (PTV, ICRU 50) results in MLC-field-shaping concerning size, position and contour to PTV-projection in beams-eye-view (BEV). Field prescription with defined leaf positions of the MLC-setting for geometrical beam shaping is transferred from TPS via TCP/IP. Patient treatment with complex coplanar and non-coplanar field arrangements is performed with an automatic set-up for gantry and collimator angle position contolled by a verification system. Quality assurance for treatment set-up is gained with a mega-voltage imaging device (MVI / PHILIPS SRI 100). Actual treatment outcome and accurate dose delivery for conformal therapy is verified by intercomparison of geometrical field matching of MVI and digitally reconstructed radiographs (DRR) for each delivered beam in BEV
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Rivard, MJ [Tufts University School of Medicine, Boston, MA (United States)
2016-06-15
Purpose: The CivaSheet is a new LDR Pd-103 brachytherapy device offering directional-radiation for preferentially irradiating malignancies with healthy-tissue sparing. Observations are presented on dosimetric characterization, TPS commissioning, and evaluation of the dosesuperposition- principle for summing individual elements comprising a planar CivaSheet Methods: The CivaSheet comprises individual sources (CivaDots, 0.05cm thick and 0.25cm diam.) inside a flexible bioabsorbable substrate with a 0.8cm center-to-center rectangular array. All non-radioactive components were measured to ensure accuracy of manufacturer-provided dimensional information. The Pd spatial distribution was gleaned from radioactive and inert samples, then modeled with the MCNP6 radiation-transport-code. A 6×6 array CivaSheet was modeled to evaluate the dose superposition principle for treatment planning. Air-kerma-strength was estimated using the NIST WAFAC geometry. Absorbed dose was estimated in water with polar sampling covering 0.05≤r≤15cm in 0.05cm increments and 0°≤θ≤180° in 1° increments. These data were entered into VariSeed9.0 and tested for the dose-superposition-principle. Results: The dose-rate-constant was 0.579 cGy/h/U with g(r) determined along the rotational-axis of symmetry (0°) instead of 90°. gP(r) values at 0.1, 0.5, 2, 5, and 10cm were 1.884, 1.344, 0.558, 0.088, and 0.0046. F(r,θ) decreased between 0° and 180° by factors of 270, 23, and 5.1 at 0.1, 1, and 10cm. The highest dose-gradient was at 92°, changing by a factor of 3 within 1° due to Au-foil shielding. TPS commissioning from 0.1≤r≤11cm and 0°≤θ≤180° demonstrated 2% reproducibility of input data except at the high-dose-gradient where interpolations caused 3% differences. Dose superposition of CivaDots replicated a multi-source CivaSheet array within 2% except where another CivaDot was present. Following implantation, the device is not perfectly planar. TPS accuracy utilizing the dose
International Nuclear Information System (INIS)
Rozendaal, Roel A.; Mijnheer, Ben J.; Hamming-Vrieze, Olga; Mans, Anton; Herk, Marcel van
2015-01-01
Background and purpose: Target dose verification for VMAT treatments of head-and-neck (H&N) cancer using 3D in vivo EPID dosimetry is expected to be affected by daily anatomical changes. By including these anatomical changes through cone-beam CT (CBCT) information, the magnitude of this effect is investigated. Materials and methods: For 20 VMAT-treated H&N cancer patients, all plan-CTs (pCTs), 633 CBCTs and 1266 EPID movies were used to compare four dose distributions per fraction: treatment planning system (TPS) calculated dose and EPID reconstructed in vivo dose, both determined using the pCT and using the CBCT. D2, D50 and D98 of the planning target volume (PTV) were determined per dose distribution. Results: When including daily anatomical information, D2, D50 and D98 of the PTV change on average by 0.0 ± 0.4% according to TPS calculations; the standard deviation of the difference between EPID and TPS target dose changes from 2.5% (pCT) to 2.1% (CBCT). Small time trends are seen for both TPS and EPID dose distributions when using the pCT, which disappear when including CBCT information. Conclusions: Daily anatomical changes hardly influence the target dose distribution for H&N VMAT treatments according to TPS recalculations. Including CBCT information in EPID dose reconstructions slightly improves the agreement with TPS calculations
SU-G-TeP2-06: Development of Novel Radiochromic Films for Radiotherapy Dosimetry
Energy Technology Data Exchange (ETDEWEB)
Alqathami, M; Lee, H; Ibbott, G [UT MD Anderson Cancer Center, Houston, TX (United States); Won Choi, G [UT MD Anderson Cancer Center, Houston, TX-Texas (United States); Blencowe, A [The University of South Australia, South Australia, SA (Australia); Wen, Z [MD Anderson Cancer Center, Houston, TX (United States); Adamovics, J [Department of Chemistry and Biology, Rider University, Skillman, NJ (United States)
2016-06-15
Purpose: To develop and evaluate novel radiochromic films for quality assurance in radiotherapy dosimetry. Materials and Methods: Novel radiochromic film compositions were formulated using leuco crystal violet (LCV) as a reporting system and tetrabromoethane as a free radical source. The film matrix used consisted of polyurethane polymer mixed with dibutyl phthalate plasticizer (20 wt%). The concentration of the radical initiator was kept constant at 10 wt% and the concentration of the LCV dye varied (1 and 2 wt%). To ensure uniform thickness of the film, its precursors were sandwiched between two pieces of glass separated by a 1 mm gap between during the curing process. The films were cut into pieces and were irradiated with a 6 MV X-ray beam to selected doses. The change in optical density was measured using a flatbed scanner and a spectrophotometer. Results: The results showed that all film formulations exhibited a linear response with dose and an absorption maximum at ∼ 590 nm. The formulation with 2 wt% LCV was ∼ 30% more sensitive to dose than the formulation with 1 wt% LCV. Both films were very deformable. In addition, the radiochromic response of the film was found to bleach over a short period of time (few weeks) allowing the film to be reused for dose verification measurements. Conclusion: Both film formulations displayed excellent sensitivity and linearity to radiation dose and thus can be used for the 2D dosimetry of clinical megavoltage and kilovoltage X-ray beams. In addition, the thickness of the film could easily be increased allowing for their potential use as a deformable bolus material. However, thicker films would need more optimization of the manufacturing procedure to ensure consistent material uniformity and sensitivity are recommended.
International Nuclear Information System (INIS)
Scalchi, Paolo; Righetto, Roberto; Cavedon, Carlo; Francescon, Paolo; Colombo, Federico
2010-01-01
Purpose: In highly-conformal radiotherapy, due to the complexity of both beam configurations and dose distributions, traditional in vivo dosimetry is unpractical or even impossible. The ideal dosimeter would be implanted inside the planning treatment volume so that it can directly measure the total delivered dose during each fraction with no additional uncertainty due to calculation models. The aim of this work is to verify if implantable metal oxide semiconductors field effect transistors (MOSFETs) can achieve a sufficient degree of dosimetric accuracy when used inside extracranial targets undergoing radiotherapy treatments using the Cyberknife system. Methods: Based on the preliminary findings of this study, new prototypes for high dose fractionations were developed to reduce the time dependence for long treatment delivery times. These dosimeters were recently cleared and are marketed as DVS-HFT. Multiple measurements were performed using both Virtual Water and water phantoms to characterize implantable MOSFETs under the Cyberknife beams, and included the reference-dosimetry consistency, the dependence of the response on the collimator size, on the daily delivered dose, and the time irradiation modality. Finally a Cyberknife prostate treatment simulation using a body phantom was conducted, and both MOSFET and ionization readings were compared to Monte Carlo calculations. The feasibility analysis was conducted based on the ratios of the absorbed dose divided by the dose reading, named as ''further calibration factor'' (FCF). Results: The average FCFs resulted to be 0.98 for the collimator dependence test, and about 1.00 for the reference-dosimetry test, the dose-dependence test, and the time-dependence test. The average FCF of the prostate treatment simulation test was 0.99. Conclusions: The obtained results are well within DVS specifications, that is, the factory calibration is still valid for such kind of treatments using the Cyberknife system, with no need of
International Nuclear Information System (INIS)
Petitguillaume, Alice
2014-01-01
Medical techniques in full expansion arousing high therapeutic expectations, targeted radionuclide therapies (TRT) consist of administering a radiopharmaceutical to selectively treat tumors. Nowadays, the activity injected to the patient is generally standardized. However, in order to establish robust dose-effect relationships and to optimize treatments while sparing healthy tissues at best, a personalized dosimetry must be performed, just like actual clinical practice in external beam radiotherapy. In that context, this PhD main objective was to develop, using the OEDIPE software, a methodology for personalized dosimetry based on direct Monte Carlo calculations. The developed method enables to calculate the tridimensional distribution of absorbed doses depending on the patient anatomy, defined from CT or MRI data, and on the patient-specific activity biodistribution, defined from SPECT or PET data. Radiobiological aspects, such as differences in radiosensitivities and repair time constants between tumoral and healthy tissues, have also been integrated through the linear-quadratic model. This methodology has been applied to the selective internal radiation therapy (SIRT) which consists in the injection of 90 Y-microspheres to selectively treat unresectable hepatic cancers. Distributions of absorbed doses and biologically effective doses (BED) along with the equivalent uniform biologically effective doses (EUD) to hepatic lesions have been calculated from 99m Tc-MAA activity distributions obtained during the evaluation step for 18 patients treated at Hopital Europeen Georges Pompidou. Those results have been compared to classical methods used in clinics and the interest of accurate and personalized dosimetry for treatment planning has been investigated. On the one hand, the possibility to increase the activity in a personalized way has been highlighted with the calculation of the maximal activity that could be injected to the patient while meeting tolerance criteria
Directory of Open Access Journals (Sweden)
Om Prakash Gurjar
2015-01-01
Full Text Available Purpose: To compare the results of patient specific absolute dosimetry using slab phantom, acrylic body phantom and goat head phantom. Methods: Fifteen intensity modulated radiotherapy (IMRT plans already planned on treatment planning system (TPS for head-and-neck cancer patients were exported on all three kinds of phantoms viz. slab phantom, acrylic body phantom and goat head phantom, and dose was calculated using anisotropic analytic algorithm (AAA. All the gantry angles were set to zero in case of slab phantom while set to as it is in actual plan in case of other two phantoms. All the plans were delivered by linear accelerator (LA and dose for each plan was measured by 0.13 cc ion chamber. The percentage (% variations between planned and measured doses were calculated and analyzed. Results: The mean % variations between planned and measured doses of all IMRT quality assurance (QA plans were as 0.65 (Standard deviation (SD: 0.38 with confidence limit (CL 1.39, 1.16 (SD: 0.61 with CL 2.36 and 2.40 (SD: 0.86 with CL 4.09 for slab phantom, acrylic head phantom and goat head phantom respectively. Conclusion: Higher dose variations found in case of real tissue phantom compare to results in case of slab and acrylic body phantoms. The algorithm AAA does not calculate doses in heterogeneous medium as accurate as it calculates in homogeneous medium. Therefore the patient specific absolute dosimetry should be done using heterogeneous phantom mimicking density wise as well as design wise to the actual human body.
Magnetic resonance imaging for precise radiotherapy of small laboratory animals
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Frenzel, Thorsten [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Bereich Strahlentherapie; Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Inst. fuer Anatomie und Experimentelle Morphologie; Kaul, Michael Gerhard; Ernst, Thomas Michael; Salamon, Johannes [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Klinik und Poliklinik fuer Diagnostische und Interventionelle Radiologie; Jaeckel, Maria [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Klinik und Poliklinik fuer Strahlentherapie und Radioonkologie; Schumacher, Udo [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Inst. fuer Anatomie und Experimentelle Morphologie; Kruell, Andreas [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Bereich Strahlentherapie
2017-05-01
Radiotherapy of small laboratory animals (SLA) is often not as precisely applied as in humans. Here we describe the use of a dedicated SLA magnetic resonance imaging (MRI) scanner for precise tumor volumetry, radiotherapy treatment planning, and diagnostic imaging in order to make the experiments more accurate. Different human cancer cells were injected at the lower trunk of pfp/rag2 and SCID mice to allow for local tumor growth. Data from cross sectional MRI scans were transferred to a clinical treatment planning system (TPS) for humans. Manual palpation of the tumor size was compared with calculated tumor size of the TPS and with tumor weight at necropsy. As a feasibility study MRI based treatment plans were calculated for a clinical 6 MV linear accelerator using a micro multileaf collimator (μMLC). In addition, diagnostic MRI scans were used to investigate animals which did clinical poorly during the study. MRI is superior in precise tumor volume definition whereas manual palpation underestimates their size. Cross sectional MRI allow for treatment planning so that conformal irradiation of mice with a clinical linear accelerator using a μMLC is in principle feasible. Several internal pathologies were detected during the experiment using the dedicated scanner. MRI is a key technology for precise radiotherapy of SLA. The scanning protocols provided are suited for tumor volumetry, treatment planning, and diagnostic imaging.
International Nuclear Information System (INIS)
Wong, Sharon; Back, Michael; Tan, Poh Wee; Lee, Khai Mun; Baggarley, Shaun; Lu, Jaide Jay
2012-01-01
Skin doses have been an important factor in the dose prescription for breast radiotherapy. Recent advances in radiotherapy treatment techniques, such as intensity-modulated radiation therapy (IMRT) and new treatment schemes such as hypofractionated breast therapy have made the precise determination of the surface dose necessary. Detailed information of the dose at various depths of the skin is also critical in designing new treatment strategies. The purpose of this work was to assess the accuracy of surface dose calculation by a clinically used treatment planning system and those measured by thermoluminescence dosimeters (TLDs) in a customized chest wall phantom. This study involved the construction of a chest wall phantom for skin dose assessment. Seven TLDs were distributed throughout each right chest wall phantom to give adequate representation of measured radiation doses. Point doses from the CMS Xio® treatment planning system (TPS) were calculated for each relevant TLD positions and results correlated. There were no significant difference between measured absorbed dose by TLD and calculated doses by the TPS (p > 0.05 (1-tailed). Dose accuracy of up to 2.21% was found. The deviations from the calculated absorbed doses were overall larger (3.4%) when wedges and bolus were used. 3D radiotherapy TPS is a useful and accurate tool to assess the accuracy of surface dose. Our studies have shown that radiation treatment accuracy expressed as a comparison between calculated doses (by TPS) and measured doses (by TLD dosimetry) can be accurately predicted for tangential treatment of the chest wall after mastectomy.
Advances in electron dosimetry of irregular fields
International Nuclear Information System (INIS)
Mendez V, J.
1998-01-01
In this work it is presented an advance in Electron dosimetry of irregular fields for beams emitted by linear accelerators. At present diverse methods exist which are coming to apply in the Radiotherapy centers. In this work it is proposed a method for irregular fields dosimetry. It will be allow to calculate the dose rate absorbed required for evaluating the time for the treatment of cancer patients. Utilizing the results obtained by the dosimetric system, it has been possible to prove the validity of the method describe for 12 MeV energy and for square field 7.5 x 7.5 cm 2 with percentile error less than 1 % . (Author)
How feasible is remote 3D dosimetry for MR guided Radiation Therapy (MRgRT)?
International Nuclear Information System (INIS)
Mein, S; Miles, D; Juang, T; Fenoli, J; Oldham, M; Rankine, L; Cai, B; Curcuru, A; Mutic, S; Li, H; Adamovics, J
2017-01-01
To develop and apply a remote dosimetry protocol with PRESAGE® radiochromic plastic and optical-CT readout in the validation of MRI guided radiation therapy (MRgRT) treatments (MRIdian® by ViewRay®). Through multi-institutional collaboration we performed PRESAGE® dosimetry studies in 4ml cuvettes to investigate dose-response linearity, MR-compatibility, and energy-independence. An open calibration field and symmetrical 3-field plans were delivered to 10cm diameter PRESAGE® to examine percent depth dose and response uniformity under a magnetic field. Evidence of non-linear dose response led to a large volume PRESAGE® study where small corrections were developed for temporally- and spatially-dependent behaviors observed between irradiation and delayed readout. TG-119 plans were created in the MRIdian® TPS and then delivered to 14.5cm 2kg PRESAGE® dosimeters. Through the domestic investigation of an off-site MRgRT system, a refined 3D remote dosimetry protocol is presented capable of validation of advanced MRgRT radiation treatments. (paper)
How feasible is remote 3D dosimetry for MR guided Radiation Therapy (MRgRT)?
Mein, S.; Rankine, L.; Miles, D.; Juang, T.; Cai, B.; Curcuru, A.; Mutic, S.; Fenoli, J.; Adamovics, J.; Li, H.; Oldham, M.
2017-05-01
To develop and apply a remote dosimetry protocol with PRESAGE® radiochromic plastic and optical-CT readout in the validation of MRI guided radiation therapy (MRgRT) treatments (MRIdian® by ViewRay®). Through multi-institutional collaboration we performed PRESAGE® dosimetry studies in 4ml cuvettes to investigate dose-response linearity, MR-compatibility, and energy-independence. An open calibration field and symmetrical 3-field plans were delivered to 10cm diameter PRESAGE® to examine percent depth dose and response uniformity under a magnetic field. Evidence of non-linear dose response led to a large volume PRESAGE® study where small corrections were developed for temporally- and spatially-dependent behaviors observed between irradiation and delayed readout. TG-119 plans were created in the MRIdian® TPS and then delivered to 14.5cm 2kg PRESAGE® dosimeters. Through the domestic investigation of an off-site MRgRT system, a refined 3D remote dosimetry protocol is presented capable of validation of advanced MRgRT radiation treatments.
The ESTRO-EQUAL quality assurance network for photon and electron radiotherapy beams in Germany
International Nuclear Information System (INIS)
Ferreira, I.H.; Dutreix, A.; Richter, J.; Bridier, A.; Chavaudra, J.; Svensson, H.
2001-01-01
Background: In 1998 an ESTRO Quality Assurance Network for radiotherapy (EQUAL) has been set up for 25 European countries for photon and electron beams in reference and non-reference conditions. Material and Methods: Measurements are done using LiF powder (DTL937-Philitech, France) that is processed with the PCL3 automatic reader (Fimel-PTW). The participating centers irradiate the TLDs with an absorbed dose of 2 Gy according to the clinical routine. Results: Until September 2000 EQUAL has checked 135 photon beams (including the beams rechecked) from 51 radiotherapy centers in Germany out of 86 accepted centers. The results show that 2% of the beam outputs in reference conditions and 3% of the percentage depth doses are outside the tolerance level (deviation > ± 5%). 6% of the beam output variations and of the wedge transmission factors show deviations > ± 5%. The global analysis of results shows deviations > ± 5% in at least one parameter for 18 beams out of the 135 beams checked. Five rechecked beams present one ''real dosimetric'' problem in one or more parameters, corresponding to 4% of the 114 beams for which the deviations cannot be attributed to set-up errors. - The EQUAL network has checked 89 electron beams in Germany. The results show that all beam outputs checked are within the tolerance level. The standard deviation for the beam output in reference conditions is 2.0% and 2.2% for the beam output for the others field sizes. The percentage of deviations > 3% and ≤ 5% for the reference beam output is higher for electron beams than for photon beam checks. Therefore the electron beam calibration and the TPS algorithms should be improved to increase the accuracy of the patient dosimetry for radiotherapy. (orig.) [de
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Reither, M; Schorn, B; Schneider, E
1981-01-01
The development of paediatric radiology which began in the late 195O's has been characterised by the need to limit the dose of ionising radiation to which the child is subjected. The aim has been to keep radiation exposure as low as possible by the introduction of suitable techniques and by the development of new methods. It is therefore surprising that studies in dosimetry in the paediaytric age range have only been carried out in recent years. One reason for this may have been the fact that a suitable technique of measurement was not available at the time. The introduction of solid state dosimetry based on thermo-luminescence, first into radiotherapy (1968) and subsequently into radiodiagnosis, has made it possible to abandon the previously widely used ionisation chamber. The purpose of the present paper is to indicate the suitability of this form of dose measurement for paediatric radiological purposes and to stimulate its application in this field.
International Nuclear Information System (INIS)
2007-10-01
As part of a comprehensive approach to quality assurance (QA) in the treatment of cancer by radiation, an independent external audit (peer review) is important to ensure adequate quality of practice and delivery of treatment. Quality audits can be of various types and at various levels, either reviewing critical parts of the radiotherapy process (partial audits) or assessing the whole process (comprehensive audits). The IAEA has a long history of providing assistance for dosimetry (partial) audits in radiotherapy to its Member States. Together with the World Health Organization (WHO), it has operated postal audit programmes using thermoluminescence dosimetry (TLD) to verify the calibration of radiotherapy beams since 1969. Furthermore, it has developed a set of procedures for experts undertaking missions to radiotherapy hospitals in Member States for on-site review of dosimetry equipment, data and techniques, measurements and training of local staff. This methodology involves dosimetry and medical radiation physics aspects of the radiotherapy process without entering into clinical areas. The IAEA, through its technical cooperation programme, has received numerous requests from developing countries to perform comprehensive audits of radiotherapy programmes to assess the whole process. including aspects such as organization, infrastructure, and clinical and medical physics components. The objective of a comprehensive clinical audit is to review and evaluate thc quality of all of the components of the practice of radiotherapy at an institution, including its professional competence, with a view to quality improvement. A multidisciplinary team, comprising a radiation oncologist, a medical physicist and a radiotherapy technologist, carries out the audit. The present publication has been field tested by IAEA teams performing audits in radiotherapy programmes in hospitals in Africa, Asia, Europe and Latin America. Their comments, corrections and feedback have been taken
International Nuclear Information System (INIS)
2008-08-01
As part of a comprehensive approach to quality assurance (QA) in the treatment of cancer by radiation, an independent external audit (peer review) is important to ensure adequate quality of practice and delivery of treatment. Quality audits can be of various types and at various levels, either reviewing critical parts of the radiotherapy process (partial audits) or assessing the whole process (comprehensive audits). The IAEA has a long history of providing assistance for dosimetry (partial) audits in radiotherapy to its Member States. Together with the World Health Organization (WHO), it has operated postal audit programmes using thermoluminescence dosimetry (TLD) to verify the calibration of radiotherapy beams since 1969. Furthermore, it has developed a set of procedures for experts undertaking missions to radiotherapy hospitals in Member States for on-site review of dosimetry equipment, data and techniques, measurements and training of local staff. This methodology involves dosimetry and medical radiation physics aspects of the radiotherapy process without entering into clinical areas. The IAEA, through its technical cooperation programme, has received numerous requests from developing countries to perform comprehensive audits of radiotherapy programmes to assess the whole process. including aspects such as organization, infrastructure, and clinical and medical physics components. The objective of a comprehensive clinical audit is to review and evaluate thc quality of all of the components of the practice of radiotherapy at an institution, including its professional competence, with a view to quality improvement. A multidisciplinary team, comprising a radiation oncologist, a medical physicist and a radiotherapy technologist, carries out the audit. The present publication has been field tested by IAEA teams performing audits in radiotherapy programmes in hospitals in Africa, Asia, Europe and Latin America. Their comments, corrections and feedback have been taken
Report of a consultants meeting on dosimetry in diagnostic radiology
International Nuclear Information System (INIS)
Pernicka, F.
1999-01-01
During its biennial meeting in 1996, the Standing Advisory Committee 'SSDL Scientific Committee', recommended extending the long experience of the Agency in the field of standardization and monitoring dosimetry calibrations at radiotherapy and radiation protection level for the Secondary Standard Dosimetry Laboratory (SSDL) Network, to the field of diagnostic x-ray dosimetry. It was emphasized that 'Measurements on diagnostic x-ray machines have become increasingly important and some SSDLs are involved in such measurements. The Agency's dosimetry laboratory should, therefore, have proper radiation sources available to provide traceable calibrations to the SSDLs'. The purpose of the consultants' meeting was to advise the Agency on dosimetry in diagnostic radiology. They were specifically requested to overview scientific achievements in the field and to give advice to the Agency on the need for further developments. The purpose of the consultants' meeting was to advise the Agency on dosimetry in diagnostic radiology. They were specifically requested to overview scientific achievements in the field and to give advice to the Agency on the need for further developments
Registration and planning of radiotherapy and proton therapy treatment
International Nuclear Information System (INIS)
Bausse, Jerome
2010-01-01
Within the frame of an update and renewal project, the Orsay Proton Therapy Centre of the Curie Institute (IPCO) renews its software used for the treatment of patients by proton therapy, a radiotherapy technique which uses proton beams. High energies used in these treatments and the precision provided by proton particle characteristics require a more precise patient positioning than conventional radiotherapy: proton therapy requires a precision of about a millimetre. Thus, markers are placed on the skull which are generally well accepted by patients, but are a problem in the case of paediatric treatment, notably for the youngest children whose skull is still growing. The first objective of this research is thus to use only intrinsic information from X-ray images used when positioning the patient. A second objective is to make the new software (TPS Isogray) perfectly compatible with IPCO requirements by maintaining the strengths of the previous TPS (Treatment Planning System) and being prepared to the implementation of a new installation. After a presentation of the context and state of the art in radiotherapy and patient positioning, the author proposes an overview of 2D registration methods, presents a new method for 2x2D registration, and addresses the problem of 3D registration. Then, after a presentation of proton therapy, the author addresses different specific issues and aspects: the compensator (simulation, calculation, and tests), dose calculation, the 'Pencil-Beam' algorithm, tests, and introduced improvements [fr
Dosimetry through the Secondary Laboratory of Dosimetric Calibration of Mexico
International Nuclear Information System (INIS)
Tovar M, V.M.; Alvarez R, J.T.; Medina O, V.P.; Vergara M, F.; Anaya M, R.; Cejudo A, J.; Salinas L, B.
2004-01-01
In the beginnings of the sixty years an urgent necessity is presented mainly in the developing countries, of improving in important form the accuracy in the dosimetry of external faces in therapy of radiations (radiotherapy centers), mainly in the calibration of c linical dosemeters . In 1976 the International Atomic Energy Agency, (IAEA), and the World Health Organization, (WHO), they carried out a mutual agreement with regard to the establishment and operation of a net of Secondary Patron Laboratories of Dosimetry, (LSCD). The necessity to establish measure patterns in the field of the dosimetry of the ionizing radiations, is necessary, to have an accuracy but high in the dosimetry of the radiation beams in therapy which is highly dependent of the dose given to the tumor of those patient with cancer. Similar levels of accuracy are required in protection measures to the radiation with an acceptable smaller accuracy, however, when the personal dosemeters are used to determine the doses received by the individuals under work conditions, such mensurations in therapy of radiations and radiological protection will have traceability through a chain of comparisons to primary or national patterns. The traceability is necessary to assure the accuracy and acceptability of the dosimetric measures, as well as, the legal and economic implications. The traceability is also necessary in the dosimetry of high dose like in the sterilization of different products. The main function of the LSCD is to provide a service in metrology of ionizing radiations, maintaining the secondary or national patterns, which have a traceability to the International System of measures, which is based for if same in the comparison of patterns in the Primary Laboratories of Dosimetry (LPD) under the auspice of the International Office of Weights and Measure (BIPM). The secondary and national patterns in the LSCD constitute in Mexico, the national patterns of the magnitudes in the dosimetry of the
In vivo thermoluminescent dosimetry in studies of helicoid computed tomography and excretory urogram
International Nuclear Information System (INIS)
Cruz C, D.; Azorin N, J.; Saucedo A, V.M.; Barajas O, J.L.
2005-01-01
The dosimetry is the field of measurement of the ionizing radiations. It final objective is to determine the 'absorbed dose' for people. The dosimetry is vital in the radiotherapy, the radiological protection and the treatment technologies by irradiation. Presently work, we develop 'In vivo' dosimetry, in exposed patients to studies of helical computed tomography and excretory urogram. The dosimetry 'in vivo' was carried out in 20 patients selected aleatorily, for each medical study. The absorbed dose was measured in points of interest located in crystalline, thyroid, chest and abdomen of each patient, by means of thermoluminescent dosemeters (TLD) LiF: Mg,Cu,P + Ptfe of national fabrication. Also it was quantified the dose in the working area. (Author)
In vivo dosimetry in radiation therapy in Sweden
International Nuclear Information System (INIS)
Eriksson, Jacob; Blomquist, Michael
2010-07-01
A prerequisite for achieving high radiation safety for patients receiving external beam radiation therapy is that the hospitals have a quality assurance program. The program should include include monitoring of the radiation dose given to the patient. Control measurements are performed both at the system level and at the individual level. Control measurement is normally performed using in vivo dosimetry, e.g. a method to measure the radiation dose at the individual level during the actual radiation treatment time. In vivo dosimetry has proven to be an important tool to detect and prevent serious errors in patient treatment. The purpose of this research project was to identify the extent to which vivo dosimetry is used and the methods available for this at Swedish radiation therapy clinics. The authority also wanted to get an overall picture of how hospitals manage results of in vivo dosimetry, and how clinics control radiation dose when using modern treatment techniques. The report reflects the situation in Swedish radiotherapy clinics 2007. The report shows that all hospitals use some form of in vivo dosimetry. The instruments used are mainly diodes and termoluminiscence dosimeters
International Nuclear Information System (INIS)
Gutierrez Lores, S.; Walwyn Salas, G.; Alonso Villanueva, G.
2008-01-01
Discusses the practical consideration and preliminary results of the Cuban's SSDL in Pilot Postal Audit in Radiotherapy for Co-60 in non-reference conditions under IAEA Coordinated Research Project E2.40.12. A strategy for national TLD audit programmes has been developed by the international Atomic Energy Agency (IAEA). It involves progression through three sequential dosimetry audit steps. The first step audits are for the beam output in reference conditions for photon beams. The second step audits are for the dose in reference and non-reference conditions on the beam axis for photon beams. The third step audits involve measurements of the dose in reference, and non-reference conditions off-axis for open and wedged symmetric and symmetric fields for photon beams. Under coordinated research project E2.40.12 were characterized 100 micro rods. All of these rods were identified individually with a consecutive number made over one of its sides, using a fine tip of graphite. The method used to determinate the individual sensibility of the TL detectors was: irradiating a group of them, with the same history of irradiation and readout. The TLD signal was read using HARSHAW 2000C/B reader. Based on the IAEA standard TLD holder for photon beams, a TLD holder was developed with horizontal arm to enable measurements 5 cm off the central axis. Successful results in two external trial carried out using the IAEA TLD service in the years 2003 - 2004 were obtained. Five 5 facilities were considered to be included in the Pilot Audit Audits in Radiotherapy for Co-60 in non reference conditions (on-axis) in the year 2003, according to recommendation of External Audit Group (EAG). For the year 2004 were considered only 3 facilities in the Pilot Audit Audits in Radiotherapy for Co-60 in non reference conditions (off-axis). Extend the postal dose audits to the rest of the institutions around the country. The participation in these audits promotes a major understanding of the physicists
Development of film dosimetric measurement system for verification of RTP
International Nuclear Information System (INIS)
Chen Yong; Bao Shanglian; Ji Changguo; Zhang Xin; Wu Hao; Han Shukui; Xiao Guiping
2007-01-01
Objective: To develop a novel film dosimetry system based on general laser scanner in order to verify patient-specific Radiotherapy Treatment Plan(RTP) in three-Dimensional Adaptable Radiotherapy(3D ART) and Intensity Modulated Radiotherapy (IMRT). Methods: Some advanced methods, including film saturated development, wavelet filtering with multi-resolution thresholds and discrete Fourier reconstruction are employed in this system to reduce artifacts, noise and distortion induced by film digitizing with general scanner; a set of coefficients derived from Monte Carlo(MC) simulation are adopted to correct the film over-response to low energy scattering photons; a set of newly emerging criteria, including γ index and Normalized Agreement Test (NAT) method, are employed to quantitatively evaluate agreement of 2D dose distributions between the results measured by the films and calculated by Treatment Planning System(TPS), so as to obtain straightforward presentations, displays and results with high accuracy and reliability. Results: Radiotherapy doses measured by developed system agree within 2% with those measured by ionization chamber and VeriSoft Film Dosimetry System, and quantitative evaluation indexes are within 3%. Conclusions: The developed system can be used to accurately measure the radiotherapy dose and reliably make quantitative evaluation for RTP dose verification. (authors)
Metrological issues in molecular radiotherapy
International Nuclear Information System (INIS)
D'Arienzo, Marco; Capogni, Marco; Smyth, Vere; Cox, Maurice; Johansson, Lena; Bobin, Christophe
2014-01-01
The therapeutic effect from molecular radiation therapy (MRT), on both tumour and normal tissue, is determined by the radiation absorbed dose. Recent research indicates that as a consequence of biological variation across patients the absorbed dose can vary, for the same administered activity, by as much as two orders of magnitude. The international collaborative EURAMET-EMRP project Metrology for molecular radiotherapy (MetroMRT) is addressing this problem. The overall aim of the project is to develop methods of calibrating and verifying clinical dosimetry in MRT. In the present paper an overview of the metrological issues in molecular radiotherapy is provided. (authors)
Dosimetry intercomparisons between fast neutron radiotherapy facilities
International Nuclear Information System (INIS)
Almond, P.R.; Smith, A.R.; Smathers, J.B.; Otte, V.A.
1975-01-01
Neutron dosimetry intercomparisons have been made between M.D. Anderson Hospital and Tumor Institute, Naval Research Laboratory, University of Washington Hospital, and Hammersmith Hospital. The parameters that are measured during these visits are: tissue kerma in air, tissue dose at depth of dose maximum, depth dose, beam profiles, neutron/gamma ratios and photon calibrations of ionization chambers. A preliminary report of these intercomparisons will be given including a comparison of the calculation and statement of tumor doses for each institution
Field arrangement and dosimetry verification for concave target
International Nuclear Information System (INIS)
Chen Liang; Wang Huankun; Li Yumin
2005-01-01
Objective: To provide a method of radiotherapy field arrangement for concave paraspinal target. Methods: Plan was designed for concave target in wax phantom and the selected patients by the guidance of beam eye view (BEV) provided by a 3D treatment planning system (CREAT EXPERT). In BEV, the inner border of all tangential fields was 2 mm out of the organ at risk (OAR) and the outer border was 5 mm beyond the target. Dosimetry films and ion chamber were used to verify the dose distribution and point dose in the wax phantom. Results: Dose distribution in phantom and patient was homogeneous. The mean dose of OAR in phantom did not exceed 16% of the prescribed dose. Isodose curves dropped more than 8% per mm between the target and OAR in the phantom. Film dosimetry coincided well with the calculated results. Position error in high dose region was with- in 4 mm and absolute dose errors were no more than 5%. Conclusion: Tangential field arrangement is valuable and practical in radiotherapy for concave paraspinal targets. (authors)
Experimental IMRT breast dosimetry in a thorax phantom
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Pimenta, Elsa B.; Campos, Tarcisio P.R.; Nogueira, Luciana B.; Lima, Andre C.S., E-mail: elsabpimenta@gmail.com, E-mail: tprcampos@pq.cnpq.br, E-mail: lucibn19@yahoo.com.br, E-mail: radioterapia.andre@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil); Centro de Tratamento em Radioterapia, Betim, MG (Brazil)
2017-11-01
Radiation therapy (RT) is an essential therapeutic method. RT is often used as adjuvant therapy in the treatment of breast cancer. The dose-volume restrictions of the organs at risk limit the prescribed dose to the target volume and biological and clinical effects may influence the final treatment outcome. The breast RT provides large risks to the adjacent organs and consequently the recommended dosimetry to the prescribed dose volume (PTV) is 50 Gy, lower than the most prescribed dose in other treatments (70-85 Gy). Such values implies in less tumor control compared to other sites. The present research proposal aimed to measure absorbed dose in a thorax phantom with synthetic breasts provided by an Intensity-Modulate Radiation Therapy (IMRT) protocol in a RT center. On the methodology, IMRT protocol was selected following recommendations from the Radiation Therapy Oncology Group (RTOG). Radiochromic films and a thorax simulator were prepared by the Ionizing Radiation Research Group (NRI). Dosimeters were calibrated on a selected linear accelerator (LINAC). The comparison of the dosimetry from treatment planning system (TPS), Xio (Elekta) and from experimental data was performed. The spatial distribution of the breast internal dose and in the adjacent organs was depicted by the experimental data. In the film's calibration, the quadratic polynomial fit presented a satisfactory coefficient. Two-dimensional dose profiles were obtained in the breast suggesting that films can supply details and information that TPS does not provide. At the phantom's dosimetry, the internal mean doses taken at the synthetic breast presented usual values above the prescribed dose, besides overall values were within the dosimetric MSKCC criterion. The non full reproduction of the build-up region in the films had occurred due to the asymmetrical positioning of the films in the inner breast, in addition to their non constant distance from the skin. The hot regions were present may
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Prajapati, S [M D Anderson Cancer Center, Houston, TX (United States); Mo, X; Bednarz, B; Lawless, M; Hammer, C; Jeraj, R; Mackie, T [University of Wisconsin- Madison, Madison, WI (United States); Flynn, R [University of Iowa Hospitals and Clinics, Iowa City, IA (United States); Westerly, D [University of Colorado Denver, Aurora, CO (United States)
2016-06-15
Purpose: An open-source, convolution/superposition based kV-treatment planning system(TPS) was developed for small animal radiotherapy from previously existed in-house MV-TPS. It is flexible and applicable to both step and shoot and helical tomotherapy treatment delivery. For initial commissioning process, the dose calculation from kV-TPS was compared with measurements and Monte Carlo(MC) simulations. Methods: High resolution, low energy kernels were simulated using EGSnrc user code EDKnrc, which was used as an input in kV-TPS together with MC-simulated x-ray beam spectrum. The Blue Water™ homogeneous phantom (with film inserts) and heterogeneous phantom (with film and TLD inserts) were fabricated. Phantom was placed at 100cm SSD, and was irradiated with 250 kVp beam for 10mins with 1.1cm × 1.1cm open field (at 100cm) created by newly designed binary micro-MLC assembly positioned at 90cm SSD. Gafchromic™ EBT3 film was calibrated in-phantom following AAPM TG-61 guidelines, and were used for measurement at 5 different depths in phantom. Calibrated TLD-100s were obtained from ADCL. EGS and MNCP5 simulation were used to model experimental irradiation set up calculation of dose in phantom. Results: Using the homogeneous phantom, dose difference between film and kV-TPS was calculated: mean(x)=0.9%; maximum difference(MD)=3.1%; standard deviation(σ)=1.1%. Dose difference between MCNP5 and kV-TPS was: x=1.5%; MD=4.6%; σ=1.9%. Dose difference between EGS and kV-TPS was: x=0.8%; MD=1.9%; σ=0.8%. Using the heterogeneous phantom, dose difference between film and kV-TPS was: x=2.6%; MD=3%; σ=1.1%; and dose difference between TLD and kV-TPS was: x=2.9%; MD=6.4%; σ=2.5%. Conclusion: The inhouse, open-source kV-TPS dose calculation system was comparable within 5% of measurements and MC simulations in both homogeneous and heterogeneous phantoms. The dose calculation system of the kV-TPS is validated as a part of initial commissioning process for small animal radiotherapy
A literature review of electronic portal imaging for radiotherapy dosimetry
van Elmpt, Wouter; McDermott, Leah; Nijsten, Sebastiaan; Wendling, Markus; Lambin, Philippe; Mijnheer, Ben
2008-01-01
Electronic portal imaging devices (EPIDs) have been the preferred tools for verification of patient positioning for radiotherapy in recent decades. Since EPID images contain dose information, many groups have investigated their use for radiotherapy dose measurement. With the introduction of the
Alanine-EPR dosimetry system for high industrial as well radiotherapeutic dose measurement
International Nuclear Information System (INIS)
Dobrovodsky, J.; Bukovjan, J.
2005-01-01
Slovak Institute of Metrology is developing new metrology standard for high doses, based on the alanine-EPR as a reference dosimetry system. A Bruker e-scan EPR analyser developed specifically for alanine dosimetry has improved stability of EPR measurement, especially at lower dose range. The standard e-scan system provides sensitivity below 1 Gray. After further improvement of the system and lowering of dose determination expanded uncertainty down below 1 %, its utilisation for radiotherapy field is expected (authors)
Energy Technology Data Exchange (ETDEWEB)
Velazquez M, S.; Carrera M, F.; Sanchez S, J. [Hospital Juan Ramon Jimenez, Ronda Norte s/n 21005 Huelva (Spain)
1998-12-31
The objective in this work is to show how the uncertainty is possible to know in the determination of the absorbed dose in Co 60 photon beams and to establish in a rational form, tolerance levels for this. It is took as base the spanish protocol of dosimetry in Radiotherapy. We have been centered in a Co 60 beam. We utilized the statistical theory of little samples. We allowed to suggest a new approach about the treatment of the tolerance levels and the uncertainty of the measurement. After two years of experience in the practical hospitable application we have gotten to put around 1 % uncertainty in the absolute dosimetry of the Co 60 beam. The presented protocol allows to execute the accuracy requirements in the determination of absorbed doses. (Author)
MO-B-BRB-03: 3D Dosimetry in the Clinic: Validating Special Techniques
Energy Technology Data Exchange (ETDEWEB)
Juang, T. [Stanford Cancer Center (United States)
2016-06-15
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
MO-B-BRB-01: 3D Dosimetry in the Clinic: Background and Motivation
Energy Technology Data Exchange (ETDEWEB)
Schreiner, L. [Cancer Center of Southeastern Ontario (Canada)
2016-06-15
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
MO-B-BRB-01: 3D Dosimetry in the Clinic: Background and Motivation
International Nuclear Information System (INIS)
Schreiner, L.
2016-01-01
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
MO-B-BRB-03: 3D Dosimetry in the Clinic: Validating Special Techniques
International Nuclear Information System (INIS)
Juang, T.
2016-01-01
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
Dosimetry at the location of secondary tumors after radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Baas, H W; Davelaar, J J; Broerse, J J; Noordijk, E M [University Hospital, Leiden (Netherlands). Dept. of Clinical Oncology
1995-12-01
After a latency period of many years the incidence of a secondary tumor is considered a serious late effect of radiotherapy. Analysis of about 200 patients, treated by radiotherapy for Hodgkin`s disease in our hospital, shows an actuarial risk for the incidence of a secondary tumor of about 7% after 10 years. The chance of tumor induction depends on the dose at the location of the tumor and therefore a good dose estimation is mandatory. Radiotherapy was given with Co-60 in the early years and with linear accelerators thereafter, exposing the target areas to 36 - 40 Gy. For dose estimations at the penumbra and outside the beam, where tumor incidence is expected to be high, we used a.o. Monte Carlo calculations. We developed an EGS4 computer simulation for a treatment beam from a linear accelerator irradiating a mathematical phantom representing the patient geometry (GSF ADAM phantom). The isodose curves at certain energies were obtained for a water phantom and fitted quite well with measurements. In addition to Monte Carlo calculations we also used existing treatment planning systems. The dose estimations of a number of patients and the derived risk per unit of dose, which is important for both radiotherapy as well as radiation protection in general, is discussed.
Directory of Open Access Journals (Sweden)
Seied R Mahdavi
2012-01-01
Full Text Available Aims: The objective of this study is to evaluate the accuracy of a treatment planning system (TPS for calculating the dose distribution parameters in conformal fields (CF. Dosimetric parameters of CF′s were compared between measurement, Monte Carlo simulation (MCNP4C and TPS calculation. Materials and Methods: Field analyzer water phantom was used for obtaining percentage depth dose (PDD curves and beam profiles (BP of different conformal fields. MCNP4C was used to model conformal fields dose specification factors and head of linear accelerator varian model 2100C/D. Results: Results showed that the distance to agreement (DTA and dose difference (DD of our findings were well within the acceptance criteria of 3 mm and 3%, respectively. Conclusions: According to this study it can be revealed that TPS using equivalent tissue air ratio calculation method is still convenient for dose prediction in non small conformal fields normally used in prostate radiotherapy. It was also showed that, since there is a close correlation with Monte Carlo simulation, measurements and TPS, Monte Carlo can be further confirmed for implementation and calculation dose distribution in non standard and complex conformal irradiation field for treatment planning systems.
GATE: computation code for medical imagery, radiotherapy and dosimetry
International Nuclear Information System (INIS)
Jan, S.
2010-01-01
The author presents the GATE code, a simulation software based on the Geant4 development environment developed by the CERN (the European organization for nuclear research) which enables Monte-Carlo type simulation to be developed for tomography imagery using ionizing radiation, and radiotherapy examinations (conventional and hadron therapy) to be simulated. The authors concentrate on the use of medical imagery in carcinology. They comment some results obtained in nuclear imagery and in radiotherapy
Kneževic, Ž; Ambrozova, I; Domingo, C; De Saint-Hubert, M; Majer, M; Martínez-Rovira, I; Miljanic, S; Mojzeszek, N; Porwol, P; Ploc, O; Romero-Expósito, M; Stolarczyk, L; Trinkl, S; Harrison, R M; Olko, P
2017-11-18
Proton beam therapy has advantages in comparison to conventional photon radiotherapy due to the physical properties of proton beams (e.g. sharp distal fall off, adjustable range and modulation). In proton therapy, there is the possibility of sparing healthy tissue close to the target volume. This is especially important when tumours are located next to critical organs and while treating cancer in paediatric patients. On the other hand, the interactions of protons with matter result in the production of secondary radiation, mostly neutrons and gamma radiation, which deposit their energy at a distance from the target. The aim of this study was to compare the response of different passive dosimetry systems in mixed radiation field induced by proton pencil beam inside anthropomorphic phantoms representing 5 and 10 years old children. Doses were measured in different organs with thermoluminescent (MTS-7, MTS-6 and MCP-N), radiophotoluminescent (GD-352 M and GD-302M), bubble and poly-allyl-diglycol carbonate (PADC) track detectors. Results show that RPL detectors are the less sensitive for neutrons than LiF TLDs and can be applied for in-phantom dosimetry of gamma component. Neutron doses determined using track detectors, bubble detectors and pairs of MTS-7/MTS-6 are consistent within the uncertainty range. This is the first study dealing with measurements on child anthropomorphic phantoms irradiated by a pencil scanning beam technique. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
International Nuclear Information System (INIS)
Viegas, Claudio Castelo Branco
2003-03-01
In vivo dosimetry in radiotherapy, i. e, the assessment of the doses received by patients during their treatments, permits a verification of the therapy quality. A routine of in vivo dosimetry is, undoubtedly, a direct benefit for the patient. Unfortunately, in Brazil and in Latin America this procedure is still a privilege for only a few patients. This routine is of common application only in developed countries. The aim of this work is to show the viability and implementation of a routine in vivo dosimetry, using diodes semiconductors and thermoluminescent dosimeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck cancer treatment. In order to reach that aim, the characteristics of the response of diodes ISORAD-p and LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performance of those detectors for in vivo dosimetry was tested using an RANDO Alderson anthropomorfic phantom and, once their adequacy proved for the kind of measurements proposed, they were used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)
Heart dosimetry in radiotherapy with hybrid computational phantoms
International Nuclear Information System (INIS)
Moignier, Cyril
2014-01-01
Cardiovascular diseases following radiotherapy are major secondary late effects raising questions among the scientific community, especially regarding the dose-effect relationship and confounding risk factors (chemotherapy, cholesterolemia, age at treatment, blood pressure,..). Post-radiation coronary diseases are one of the main causes of cardiac morbidity. Some approximations are made when coronary doses due to radiotherapy are estimated, especially regarding the morphology. For retrospective studies with old medical records, only radiographs are usually available with sometimes some contours made with a simulator. For recent medical records, CT scans displaying the anatomy in 3D are used for radiotherapy simulation but do not allow the coronary artery visualization due to low resolution and contrast. Currently, coronary doses are barely assessed in clinical practice, and when it is done, anatomical prior knowledge is generally used. This thesis proposes an original approach based on hybrid computational phantoms to study coronary artery doses following radiotherapy for left-side breast cancer and Hodgkin lymphoma. During the thesis, a method inserting hybrid computational phantoms in a DICOM format into the treatment planning system has been developed and validated. It has been adapted and tested in conditions where only radiographs provide anatomical information, as with old medical records for left side breast radiotherapy. The method has also been adapted to perform precise dose reconstructions to the coronary artery for patients treated for a mediastinal Hodgkin lymphoma and diagnosed with coronary stenosis through a coroscanner. A case-control study was carried out and the risk of coronary stenosis on a coronary artery segment was assessed to be multiplied by 1.049 at each additional gray on the median dose to the coronary artery segment. For recent medical records, coronary doses uncertainties related to an approach by anatomical prior knowledge
Woven TPS Enabling Missions Beyond Heritage Carbon Phenolic
Stackpoole, Margaret M.; Venkatapathy, Ethiraj; Feldman, Jay D.
2013-01-01
NASAs Office of the Chief Technologist (OCT) Game Changing Division recently funded an effort to advance a Woven TPS (WTPS) concept. WTPS is a new approach to producing TPS architectures that uses precisely engineered 3D weaving techniques to customize material characteristics needed to meet specific missions requirements for protecting space vehicles from the intense heating generated during atmospheric entry. Using WTPS, sustainable, scalable, mission-optimized TPS solutions can be achieved with relatively low life cycle costs compared with the high costs and long development schedules currently associated with material development and certification. WTPS leverages the mature state-of-the-art weaving technology that has evolved from the textile industry to design TPS materials with tailorable performance. Currently, missions anticipated encountering heat fluxes in the range of 1500 4000 Wcm2 and pressures greater than 1.5 atm are limited to using fully dense Carbon Phenolic. However, fully dense carbon phenolic is only mass efficient at higher heat fluxes g(reater than 4000 Wcm2), and current mission designs suffer this mass inefficiency for lack of an alternative mid-density TPS. WTPS not only bridges this mid-density TPS gap but also offers a replacement for carbon phenolic, which itself requires a significant and costly redevelopment effort to re-establish its capability for use in the high heat flux missions recently prioritized in the NRC Decadal survey, including probe missions to Venus, Saturn and Neptune. This presentation will overview the WTPS concept and present some results from initial testing completed comparing WTPS architectures to heritage carbon phenolic.
Energy Technology Data Exchange (ETDEWEB)
Jan, S. [CEA Direction des Sciences du Vivant, Institut d ' Imagerie Bio-Medicale, Service Hospitalier Frederic Joliot, 4 pl. du Gn. Leclerc 91401 Orsay Cedex (France)
2010-07-01
The author presents the GATE code, a simulation software based on the Geant4 development environment developed by the CERN (the European organization for nuclear research) which enables Monte-Carlo type simulation to be developed for tomography imagery using ionizing radiation, and radiotherapy examinations (conventional and hadron therapy) to be simulated. The authors concentrate on the use of medical imagery in carcinology. They comment some results obtained in nuclear imagery and in radiotherapy
Film dosimetry for IMRT: sensitivity corrections
International Nuclear Information System (INIS)
Suchowerska, N.; Hoban, P.; Davison, A.; Metcalfe, P.
2000-01-01
Full text: The trend towards conformal, dynamic and intensity modulated radiotherapy treatments has furthered the need for true integrating dosimetry. In traditional radiotherapy, film dosimetry is commonly used. The accuracy and reproducibility of film optical density as an indicator of dose, has been associated with several variables. These include the effects of film specific sensitivity, direction of exposure, chemical processing and film scanner sensitivity. In this study, a procedure is developed to account for these variables, with a particular view to film being used as a dosimeter for conformal treatments. An effective sensitometric curve was established by exposing part of a single sheet of film to known doses. All films were processed together and scanned using a DuoscanT1200 transmission scanner, resulting in 12 bit image files. The images were analysed using Osiris software and the results fitted to the modified Williamson equation: P P s (l - 10 αD ) This yields values of α [film sensitivity], and P s [saturation pixel value], allowing individual dosimetry films to be normalised to this sensitometric calibration curve. For validation, a piece of Kodak X Omat-V film was sealed in a head phantom and exposed to a total of 51 IMRT fields, delivered from 6 gantry angles. The rest of the sheet of film was resealed and exposed to four known doses, providing sensitometric data, specific to this exposure. All films were then processed, scanned and analysed as described above. Observed variations in serial films exposed to 50cGy is in the order of 9% [mean 25.0,standard deviation = 3.2]. The automatic gain of the scanner system typically contributed 4% variation and needs to be carefully monitored. Results indicate that by using the sensitometric data from each exposure, the collective errors can be minimised. The IMRT exposure results confirm that the above process is viable for use in dosimetry for conformal radiation therapy. Copyright (2000) Australasian
Why Radiotherapy Works. Chapter 6
International Nuclear Information System (INIS)
Tashiro, S.; Nishibuchi, I.; Wondergem, J.
2017-01-01
The history of radiotherapy began in 1895, when Röntgen discovered X rays, and in the following year, radiation was used for medical treatment. In the early days, the development of radiotherapy was based extensively on empiricism. Radiotherapists worked closely with radiation biologists in attempting to describe and understand the phenomena produced by ionizing radiation in the clinic and in biological systems. During the ensuing 120 years, radiotherapy has been improved significantly and, in addition to radiation biology, medical physics has played an important role in the design and development of equipment, quality assurance and dosimetry. Over recent decades, advances have been made in the field of molecular biology. Currently available techniques enable us to elucidate the molecular mechanisms of cellular response to ionizing irradiation, and it is anticipated that the role and contributions of radiation biology in radiotherapy will remain relevant. This chapter describes the clinically important biological points, including knowledge from current molecular biology.
New 2-D dosimetric technique for radiotherapy based on planar thermoluminescent detectors
International Nuclear Information System (INIS)
Olko, P.; Marczewska, B.; Czopyk, L.; Czermak, M. A.; Klosowski, M.; Waligorski, M. P. R.
2006-01-01
At the Inst. of Nuclear Physics of the Polish Academy of Sciences (IFJ) in Krakow, a two-dimensional (2-D) thermoluminescence (TL) dosimetry system was developed within the MAESTRO (Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology) 6 Framework Programme and tested by evaluating 2-D dose distributions around radioactive sources. A thermoluminescent detector (TLD) foil was developed, of thickness 0.3 mm and diameter 60 mm, containing a mixture of highly sensitive LiF:Mg,Cu,P powder and Ethylene Tetrafluoroethylene (ETFE) polymer. Foil detectors were irradiated with 226 Ra brachytherapy sources and a 90 Sr/ 90 Y source. 2-D dose distributions were evaluated using a prototype planar (diameter 60 mm) reader, equipped with a 12 bit Charge Coupled Devices (CCD) PCO AG camera, with a resolution of 640 x 480 pixels. The new detectors, showing a spatial resolution better than 0.5 mm and a measurable dose range typical for radiotherapy, can find many applications in clinical dosimetry. Another technology applicable to clinical dosimetry, also developed at IFJ, is the Si microstrip detector of size 95 x 95 mm 2 , which may be used to evaluate the dose distribution with a spatial resolution of 120 μm along one direction, in real-time mode. The microstrip and TLD technology will be further improved, especially to develop detectors of larger area, and to make them applicable to some advanced radiotherapy modalities, such as intensity modulated radiotherapy (IMRT) or proton radiotherapy. (authors)
Improving the accuracy of ionization chamber dosimetry in small megavoltage x-ray fields
McNiven, Andrea L.
The dosimetry of small x-ray fields is difficult, but important, in many radiation therapy delivery methods. The accuracy of ion chambers for small field applications, however, is limited due to the relatively large size of the chamber with respect to the field size, leading to partial volume effects, lateral electronic disequilibrium and calibration difficulties. The goal of this dissertation was to investigate the use of ionization chambers for the purpose of dosimetry in small megavoltage photon beams with the aim of improving clinical dose measurements in stereotactic radiotherapy and helical tomotherapy. A new method for the direct determination of the sensitive volume of small-volume ion chambers using micro computed tomography (muCT) was investigated using four nominally identical small-volume (0.56 cm3) cylindrical ion chambers. Agreement between their measured relative volume and ionization measurements (within 2%) demonstrated the feasibility of volume determination through muCT. Cavity-gas calibration coefficients were also determined, demonstrating the promise for accurate ion chamber calibration based partially on muCT. The accuracy of relative dose factor measurements in 6MV stereotactic x-ray fields (5 to 40mm diameter) was investigated using a set of prototype plane-parallel ionization chambers (diameters of 2, 4, 10 and 20mm). Chamber and field size specific correction factors ( CSFQ ), that account for perturbation of the secondary electron fluence, were calculated using Monte Carlo simulation methods (BEAM/EGSnrc simulations). These correction factors (e.g. CSFQ = 1.76 (2mm chamber, 5mm field) allow for accurate relative dose factor (RDF) measurement when applied to ionization readings, under conditions of electronic disequilibrium. With respect to the dosimetry of helical tomotherapy, a novel application of the ion chambers was developed to characterize the fan beam size and effective dose rate. Characterization was based on an adaptation of the
Characterisation of a CZT detector for dosimetry of molecular radiotherapy
McAreavey, L. H.; Harkness-Brennan, L. J.; Colosimo, S. J.; Judson, D. S.; Boston, A. J.; Boston, H. C.; Nolan, P. J.; Flux, G. D.; Denis-Bacelar, A. M.; Harris, B.; Radley, I.; Carroll, M.
2017-03-01
A pixelated cadmium zinc telluride (CZT) detector has been characterised for the purpose of developing a quantitative single photon emission computed tomography (SPECT) system for dosimetry of molecular radiotherapy (MRT). This is the aim of the Dosimetric Imaging with CZT (DEPICT) project, which is a collaboration between the University of Liverpool, The Royal Marsden Hospital, The Royal Liverpool and Broadgreen University Hospital, and the commercial partner Kromek. CZT is a direct band gap semiconductor with superior energy resolution and stopping power compared to scintillator detectors used in current SPECT systems. The inherent detector properties have been investigated and operational parameters such as bias voltage and peaking time have been selected to optimise the performance of the system. Good energy resolution is required to discriminate γ-rays that are scattered as they are emitted from the body and within the collimator, and high photon throughput is essential due to the high activities of isotopes administered in MRT. The system has an average measured electronic noise of 3.31 keV full width at half maximum (FWHM), determined through the use of an internal pulser. The energy response of the system was measured across the energy region of interest 59.5 keV to 364.5 keV and found to be linear. The reverse bias voltage and peaking time producing the optimum FWHM and maximum photon throughput were 600 V and 0.5 μs respectively. The average dead time of the system was measured as 4.84 μs and charge sharing was quantified to be 0.71 % at 59.5 keV . A pixel sensitivity calibration map was created and planar images of the medical imaging isotopes 99mTc and 123I were acquired by coupling the device to a prototype collimator, thereby demonstrating the suitability of the detector for the DEPICT project.
In vivo real-time rectal wall dosimetry for prostate radiotherapy
International Nuclear Information System (INIS)
Hardcastle, Nicholas; Cutajar, Dean L; Metcalfe, Peter E; Lerch, Michael L F; Tome, Wolfgang A; Rosenfeld, Anatoly B; Perevertaylo, Vladimir L
2010-01-01
Rectal balloons are used in external beam prostate radiotherapy to provide reproducible anatomy and rectal dose reductions. This is an investigation into the combination of a MOSFET radiation detector with a rectal balloon for real-time in vivo rectal wall dosimetry. The MOSFET used in the study is a radiation detector that provides a water equivalent depth of measurement of 70 μm. Two MOSFETs were combined in a face-to-face orientation. The reproducibility, sensitivity and angular dependence were measured for the dual MOSFET in a 6 MV photon beam. The dual MOSFET was combined with a rectal balloon and irradiated with hypothetical prostate treatments in a phantom. The anterior rectal wall dose was measured in real time and compared with the planning system calculated dose. The dual MOSFET showed angular dependence within ±2.5% in the azimuth and +2.5%/-4% in the polar axes. When compared with an ion chamber measurement in a phantom, the dual MOSFET agreed within 2.5% for a range of radiation path lengths and incident angles. The dual MOSFET had reproducible sensitivity for fraction sizes of 2-10 Gy. For the hypothetical prostate treatments the measured anterior rectal wall dose was 2.6 and 3.2% lower than the calculated dose for 3DCRT and IMRT plans. This was expected due to limitations of the dose calculation method used at the balloon cavity interface. A dual MOSFET combined with a commercial rectal balloon was shown to provide reproducible measurements of the anterior rectal wall dose in real time. The measured anterior rectal wall dose agreed with the expected dose from the treatment plan for 3DCRT and IMRT plans. The dual MOSFET could be read out in real time during the irradiation, providing the capability for real-time dose monitoring of the rectal wall dose during treatment.
A neurosurgery/stereotactic radiotherapy dedicated PACS for conformal radiotherapy
International Nuclear Information System (INIS)
Lefkopoulos, D.; Bocquiault, P.; Levrier, M.; Merienne, L.; Schlienger, M.
1995-01-01
To realise conformal cerebral stereotactic irradiations we use a Neurosurgery/stereotactic dedicated PACS between two distant hospitals. It connects the stereotactic neurosurgery planification imaging system NEUROAXIS (Sopelem-Sofretec/Ste Anne Hospital) with the dosimetric TPS ARTEMIS-3D/Dosigray (Tenon Hospital). NEUROAXIS is a computer aided stereotactic biopsies and stereo-electroencephalographies, used by surgeons in operating room. The system determines the precise location data for Talairach radiological equipment (X ray source at 5 meters from film) and the geometry of scanner and MRI stereotactical referentials. It provides a full set of features for lesion localization, geometrical computations, surgical planifications, picture archiving, stereotactic angiography, CT and MRI image processing and networking. It sends images through the French public digital network ISDN (NUMERIS/France Telecom : 2x64 Kbits/s) from Ste Anne to Tenon Hospital. Stereotactic angiographic and CT images are reformatted into the DOSIGRAY image processing environment where 3-D dose distributions, displays and DVHs are computed to determine the optimal treatment. ARTEMIS-3D/Dosigray is a TPS for stereotactic radiotherapy devised by the Tenon Hospital for clinical methodology and 3D dose calculations, optimization software development and the Dosigray company for multimodality imaging, (2D(3D)) computer graphics for dose and anatomical representation and data networking. Communication within the radiation oncology department is provided by local area ETHERNET network, linking heterogeneous systems (Vaxstations-3200; Decstation (5000(240))) by means of different protocols. The works in progress are to send back via the same network the 3-D dose matrix to Neurosurgery department NEUROAXIS system. Our PACS is used since six months to treat patients. It has permitted to improve the treatment quality in comparison with our first version TPS ARTEMIS-3D
Ramm, Daniel
2018-02-01
Three dimensional dosimetry by optical CT readout of radiosensitive gels or solids has previously been indicated as a solution for measurement of radiotherapy 3D dose distributions. The clinical uptake of these dosimetry methods has been limited, partly due to impracticalities of the optical readout such as the expertise and labour required for refractive index fluid matching. In this work a fast laser beam optical CT scanner is described, featuring fluid-less and dual wavelength operation. A second laser with a different wavelength is used to provide an alternative reference scan to the commonly used pre-irradiation scan. Transmission data for both wavelengths is effectively acquired simultaneously, giving a single scan process. Together with the elimination of refractive index fluid matching issues, scanning practicality is substantially improved. Image quality and quantitative accuracy were assessed for both dual and single wavelength methods. The dual wavelength scan technique gave improvements in uniformity of reconstructed optical attenuation coefficients in the sample 3D volume. This was due to a reduction of artefacts caused by scan to scan changes. Optical attenuation measurement accuracy was similar for both dual and single wavelength modes of operation. These results established the basis for further work on dosimetric performance.
Advances in biomedical dosimetry
International Nuclear Information System (INIS)
1981-01-01
Full text: Radiation dosimetry, the accurate determination of the absorbed dose within an irradiated body or a piece of material, is a prerequisite for all applications of ionizing radiation. This has been known since the very first radiation applications in medicine and biology, and increasing efforts are being made by radiation researchers to develop more reliable, effective and safe instruments, and to further improve dosimetric accuracy for all types of radiation used. Development of new techniques and instrumentation was particularly fast in the field of both medical diagnostic and therapeutic radiology. Thus, in Paris in October the IAEA held the latest symposium in its continuing series on dosimetry in medicine and biology. The last one was held in Vienna in 1975. High-quality dosimetry is obviously of great importance for human health, whether the objectives lie in the prevention and control of risks associated with the nuclear industry, in medical uses of radioactive substances or X-ray beams for diagnostic purposes, or in the application of photon, electron or neutron beams in radiotherapy. The symposium dealt with the following subjects: General aspects of dosimetry; Special physical and biomedical aspects; Determination of absorbed dose; Standardization and calibration of dosimetric systems; and Development of dosimetric systems. The forty or so papers presented and the discussions that followed them brought out a certain number of dominant themes, among which three deserve particular mention. - The recent generalization of the International System of Units having prompted a fundamental reassessment of the dosimetric quantities to be considered in calibrating measuring instruments, various proposals were advanced by the representatives of national metrology laboratories to replace the quantity 'exposure' (SI unit = coulomb/kg) by 'Kerma' or 'absorbed dose' (unit joule/kg, the special name of which is 'gray'), this latter being closer to the practical
Fetal dose reduction in head and neck radiotherapy of a pregnant woman
International Nuclear Information System (INIS)
Moeckli, R.; Pache, G.; Valley, J.F.; Ozsahin, M.; Mirimanoff, R.O.; Azria, D.
2004-01-01
Background and purpose: a pregnant woman was referred for post-operative radiotherapy of a malignant schwannoma in the head and neck region. A best-treatment plan was devised in order to minimize the fetal dose. Material and methods: the fetal dose resulting from radiological examinations was determined according to international protocols, that resulting from radiotherapy was calculated according to recommendation 36 of the American Association of Physicists in Medicine (AAPM) Task Group. Pre-treatment dosimetry was performed with an anthropomorphic phantom. Several alternative treatment plans were evaluated. The use of a multileaf collimator (MLC) and a virtual wedge (VW) was compared to cerrobend blocks (CB) and physical wedge (PW). In-vivo dosimetry was performed using a vaginal probe containing thermoluminescent dosimeters (TLD). Results: the total fetal dose resulting from diagnostic and radiotherapy procedures was estimated to be 36 mGy. The technique based on MLC and VW was elected for patient treatment. Measurements for this configuration resulted in a fetal dose reduction of 82%. The shielding of the patient's abdomen further reduced the fetal dose by 42%. Conclusion: the use of VW and MLC for the treatment of a pregnant woman is highly recommended. Each case should be individually studied with pre-treatment and in-vivo dosimetry. (orig.)
Conformal Radiotherapy: Physics, Treatment Planning and Verification. Proceedings book
Energy Technology Data Exchange (ETDEWEB)
De Wagter, C [ed.
1995-12-01
The goal of conformal radiotherapy is to establish radiation dose distributions that conform tightly to the target volume in view of limiting radiation to normal tissues. Conformal radiotherapy significantly improves both local control and palliation and thus contributes to increase survival and to improve the quality of life. The subjects covered by the symposium include : (1) conformal radiotherapy and multi-leaf collimation; (2) three dimensional imaging; (3) treatment simulation, planning and optimization; (4) quality assurance; and (5) dosimetry. The book of proceedings contains the abstracts of the invited lectures, papers and poster presentations as well as the full papers of these contributions.
Conformal Radiotherapy: Physics, Treatment Planning and Verification. Proceedings book
International Nuclear Information System (INIS)
De Wagter, C.
1995-12-01
The goal of conformal radiotherapy is to establish radiation dose distributions that conform tightly to the target volume in view of limiting radiation to normal tissues. Conformal radiotherapy significantly improves both local control and palliation and thus contributes to increase survival and to improve the quality of life. The subjects covered by the symposium include : (1) conformal radiotherapy and multi-leaf collimation; (2) three dimensional imaging; (3) treatment simulation, planning and optimization; (4) quality assurance; and (5) dosimetry. The book of proceedings contains the abstracts of the invited lectures, papers and poster presentations as well as the full papers of these contributions
Biological dosimetry study in differentiated thyroid carcinoma patients treated with 131Iodine
International Nuclear Information System (INIS)
Vallerga, Maria Belen
2008-11-01
Biological Dosimetry allows individual dose assessments based on the effect produced by ionizing radiation on a given biological parameter. The current biological endpoint being scored is chromosomal aberrations, relying on a lymphocytes culture from the patient's blood. The measured yield of chromosome aberrations is referred to a calibration curve obtaining the whole body dose. Different scenarios of overexposure can be taken into account by modifying the calculations leading to the dose estimate. Differentiated Thyroid Carcinoma patients undergo thyroidectomy followed by internal radiotherapy with 131 I. The treatment's success entails the delivery of a lethal dose to the tumour within the maximum tolerable dose to a critical organ (blood doses over 2 Gy could lead to bone marrow depression). Currently, there is no established agreement for the selection of radioiodine dosage. Historically, the empiric approach, based on clinical and biochemical data, has been recommended. Nevertheless, this method may not be associated with optimal outcomes. On the other hand, the dosimetric approach attempts to determine the maximum allowable activity to be administered, establishing its biokinetics by a diagnostic 131 I study. The methodology may be modified to further individualized treatment, however it requires validation. Biological dosimetry provides an independent measure of radiotherapy effect, as such it might aid in the validation process. Nonetheless, biological dosimetry has traditionally been applied in cases of external and accidental overexposure to ionizing radiation. Accordingly, it is mandatory to assess its value in medical internal incorporations (main objective of the present study). The applied treatment strategy comprises whole body dose assessment by biological and internal dosimetry in order to administer a personalized therapeutic activity. Overall, 20 patients with differentiated thyroid carcinoma were included in the study. For biological dosimetry
INEEL Advanced Radiotherapy Research Program Annual Report 2002
Energy Technology Data Exchange (ETDEWEB)
Venhuizen, J.R.
2003-05-23
This report summarizes the activities and major accomplishments for the Idaho National Engineering and Environmental Laboratory (INEEL) Advanced Radiotherapy Research Program for calendar year 2002. Topics covered include computational dosimetry and treatment planning software development, medical neutron source development and characterization, and boron analytical chemistry.
International Nuclear Information System (INIS)
Velez, G.; Balmaceda, O.; Gutierrez, S.; Ferraris, M.; Bustos, S.
1998-01-01
Full text: The dosimetry 'in vivo' is used frequently as a valuable tool for the quality control in radiotherapy. Measurements of the entry and exit doses provide us of information on the precision of the technique or the procedure of used treatment; the measurement of the doses in rectal or bladder in gynecological implants contribute to perfect or to adjust the procedures in brachytherapy. Also systematic errors can be identified in particular situations that allow to optimize the treatment and to minimize errors. A study in the service of Radiotherapy of the San Roque Hospital, was realized for to control the procedures used in the treatment of different cancer therapy. Patients were selected, to which were carried out a routine planning with the system of planning of on line treatment Prowess 3000 that then were controlled with thermoluminescent dosemeters 'in vivo' using the Ceprocor Services. Skin doses were measurement in treatment of breast, pelvis, thorax, head and neck, and doses was measured in cavities of the body as oral cavity, rectal, esophagus, etc., placing the TLD inside special catheters. In the case of doses in skin, the dosimeters was placed in acrylic badges. A very good agreement was found between the measurements 'in vivo' and the plans of the planner. In some cases the control allowed to modify the doses to avoid organs damage for the radiation fields. (author) [es
Energy Technology Data Exchange (ETDEWEB)
Alves, G.G. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Kinoshita, A. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Universidade Sagrado Coração, Bauru, SP (Brazil); Oliveira, H.F. de; Guimarães, F.S.; Amaral, L.L. [Serviço de Radioterapia, Hospital das Clínicas, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Baffa, O. [Departamento de Física, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)
2015-05-26
Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.
Alves, G G; Kinoshita, A; Oliveira, H F de; Guimarães, F S; Amaral, L L; Baffa, O
2015-07-01
Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses.
International Nuclear Information System (INIS)
Alves, G.G.; Kinoshita, A.; Oliveira, H.F. de; Guimarães, F.S.; Amaral, L.L.; Baffa, O.
2015-01-01
Radiotherapy is one of the main approaches to cure prostate cancer, and its success depends on the accuracy of dose planning. A complicating factor is the presence of a metallic prosthesis in the femur and pelvis, which is becoming more common in elderly populations. The goal of this work was to perform dose measurements to check the accuracy of radiotherapy treatment planning under these complicated conditions. To accomplish this, a scale phantom of an adult pelvic region was used with alanine dosimeters inserted in the prostate region. This phantom was irradiated according to the planned treatment under the following three conditions: with two metallic prostheses in the region of the femur head, with only one prosthesis, and without any prostheses. The combined relative standard uncertainty of dose measurement by electron spin resonance (ESR)/alanine was 5.05%, whereas the combined relative standard uncertainty of the applied dose was 3.35%, resulting in a combined relative standard uncertainty of the whole process of 6.06%. The ESR dosimetry indicated that there was no difference (P>0.05, ANOVA) in dosage between the planned dose and treatments. The results are in the range of the planned dose, within the combined relative uncertainty, demonstrating that the treatment-planning system compensates for the effects caused by the presence of femur and hip metal prostheses
Energy Technology Data Exchange (ETDEWEB)
Livingstone, Jayde, E-mail: Jayde.Livingstone@synchrotron.org.au; Häusermann, Daniel [Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168 (Australia); Stevenson, Andrew W. [Imaging and Medical Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia and CSIRO Manufacturing, Clayton South, Victoria 3169 (Australia); Butler, Duncan J. [Australian Radiation Protection and Nuclear Safety Agency, Yallambie, Victoria 3085 (Australia); Adam, Jean-François [Equipe d’accueil Rayonnement Synchrotron et Recherche Médicale, Université Grenoble Alpes, European Synchrotron Radiation Facility - ID17, Grenoble 38043, France and Centre Hospitalier Universitaire de Grenoble, Grenoble 38043 (France)
2016-07-15
Purpose: Modern radiotherapy modalities often use small or nonstandard fields to ensure highly localized and precise dose delivery, challenging conventional clinical dosimetry protocols. The emergence of preclinical spatially fractionated synchrotron radiotherapies with high dose-rate, sub-millimetric parallel kilovoltage x-ray beams, has pushed clinical dosimetry to its limit. A commercially available synthetic single crystal diamond detector designed for small field dosimetry has been characterized to assess its potential as a dosimeter for synchrotron microbeam and minibeam radiotherapy. Methods: Experiments were carried out using a synthetic diamond detector on the imaging and medical beamline (IMBL) at the Australian Synchrotron. The energy dependence of the detector was characterized by cross-referencing with a calibrated ionization chamber in monoenergetic beams in the energy range 30–120 keV. The dose-rate dependence was measured in the range 1–700 Gy/s. Dosimetric quantities were measured in filtered white beams, with a weighted mean energy of 95 keV, in broadbeam and spatially fractionated geometries, and compared to reference dosimeters. Results: The detector exhibits an energy dependence; however, beam quality correction factors (k{sub Q}) have been measured for energies in the range 30–120 keV. The k{sub Q} factor for the weighted mean energy of the IMBL radiotherapy spectrum, 95 keV, is 1.05 ± 0.09. The detector response is independent of dose-rate in the range 1–700 Gy/s. The percentage depth dose curves measured by the diamond detector were compared to ionization chambers and agreed to within 2%. Profile measurements of microbeam and minibeam arrays were performed. The beams are well resolved and the full width at halfmaximum agrees with the nominal width of the beams. The peak to valley dose ratio (PVDR) calculated from the profiles at various depths in water agrees within experimental error with PVDR calculations from Gafchromic film data
Treatment planning systems dosimetry auditing project in Portugal.
Lopes, M C; Cavaco, A; Jacob, K; Madureira, L; Germano, S; Faustino, S; Lencart, J; Trindade, M; Vale, J; Batel, V; Sousa, M; Bernardo, A; Brás, S; Macedo, S; Pimparel, D; Ponte, F; Diaz, E; Martins, A; Pinheiro, A; Marques, F; Batista, C; Silva, L; Rodrigues, M; Carita, L; Gershkevitsh, E; Izewska, J
2014-02-01
The Medical Physics Division of the Portuguese Physics Society (DFM_SPF) in collaboration with the IAEA, carried out a national auditing project in radiotherapy, between September 2011 and April 2012. The objective of this audit was to ensure the optimal usage of treatment planning systems. The national results are presented in this paper. The audit methodology simulated all steps of external beam radiotherapy workflow, from image acquisition to treatment planning and dose delivery. A thorax CIRS phantom lend by IAEA was used in 8 planning test-cases for photon beams corresponding to 15 measuring points (33 point dose results, including individual fields in multi-field test cases and 5 sum results) in different phantom materials covering a set of typical clinical delivery techniques in 3D Conformal Radiotherapy. All 24 radiotherapy centers in Portugal have participated. 50 photon beams with energies 4-18 MV have been audited using 25 linear accelerators and 32 calculation algorithms. In general a very good consistency was observed for the same type of algorithm in all centres and for each beam quality. The overall results confirmed that the national status of TPS calculations and dose delivery for 3D conformal radiotherapy is generally acceptable with no major causes for concern. This project contributed to the strengthening of the cooperation between the centres and professionals, paving the way to further national collaborations. Copyright © 2013 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Gomez Ros, J M; Delgado, A
1989-07-01
This report presents the application of numerical methods to thermoluminescence dosimetry (TLD), showing the advantages obtained over conventional evaluation systems. Different configurations of the analysis method are presented to operate in specific dosimetric applications of TLD, such as environmental monitoring and mailed dosimetry systems for quality assurance in radiotherapy facilities. (Author) 10 refs.
Measurement uncertainty. A practical guide for Secondary Standards Dosimetry Laboratories
International Nuclear Information System (INIS)
2008-05-01
The need for international traceability for radiation dose measurements has been understood since the early nineteen-sixties. The benefits of high dosimetric accuracy were recognized, particularly in radiotherapy, where the outcome of treatments is dependent on the radiation dose delivered to patients. When considering radiation protection dosimetry, the uncertainty may be greater than for therapy, but proper traceability of the measurements is no less important. To ensure harmonization and consistency in radiation measurements, the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) created a Network of Secondary Standards Dosimetry Laboratories (SSDLs) in 1976. An SSDL is a laboratory that has been designated by the competent national authorities to undertake the duty of providing the necessary link in the traceability chain of radiation dosimetry to the international measurement system (SI, for Systeme International) for radiation metrology users. The role of the SSDLs is crucial in providing traceable calibrations; they disseminate calibrations at specific radiation qualities appropriate for the use of radiation measuring instruments. Historically, although the first SSDLs were established mainly to provide radiotherapy level calibrations, the scope of their work has expanded over the years. Today, many SSDLs provide traceability for radiation protection measurements and diagnostic radiology in addition to radiotherapy. Some SSDLs, with the appropriate facilities and expertise, also conduct quality audits of the clinical use of the calibrated dosimeters - for example, by providing postal dosimeters for dose comparisons for medical institutions or on-site dosimetry audits with an ion chamber and other appropriate equipment. The requirements for traceable and reliable calibrations are becoming more important. For example, for international trade where radiation products are manufactured within strict quality control systems, it is
Dosimetry of internal emitting: principles and perspectives of the MIRD technology
International Nuclear Information System (INIS)
Ferro F, G.
1999-01-01
The development of the radiopharmaceutical technology have multiplied the number of radioisotopes with applications in therapeutical nuclear medicine so known as Directed radiotherapy. Assuming the radiation is capable to produce noxious effects in the biological systems, it is important to evaluate appropriately the risks and benefits of the administration of radioactive agents in the patient. The outstanding parameter in this evaluation is the absorbed dose, which is product of the radiation emitted by a radionuclide that is localized or distributed to the interior of the human body in study and whose its estimation helps to predict the efficacy of the treatment. The scheme generalized of MIRD, it was formulated from thirty years ago for evaluating the interior dosimetry at level of organs.The finality of this work is to show the basic principles of the MIRD methodology and its perspectives using innovator tools as the dosimetry for dynamic masses, in particular the personnel dosimetry for the organs of each patient, the dosimetry for the small structures inside the organs (sub organic dosimetry), the distributions of doses in three dimensions (S voxel), the dosimetry at cellular level and the quantitative acquisition of pharmaceutical data. (Author)
High-temperature behavior of advanced spacecraft TPS
Pallix, Joan
1994-05-01
The objective of this work has been to develop more efficient, lighter weight, and higher temperature thermal protection systems (TPS) for future reentry space vehicles. The research carried out during this funding period involved the design, analysis, testing, fabrication, and characterization of thermal protection materials to be used on future hypersonic vehicles. This work is important for the prediction of material performance at high temperature and aids in the design of thermal protection systems for a number of programs including programs such as the National Aerospace Plane (NASP), Pegasus and Pegasus/SWERVE, the Comet Rendezvous and Flyby Vehicle (CRAF), and the Mars mission entry vehicles. Research has been performed in two main areas including development and testing of thermal protection systems (TPS) and computational research. A variety of TPS materials and coatings have been developed during this funding period. Ceramic coatings were developed for flexible insulations as well as for low density ceramic insulators. Chemical vapor deposition processes were established for the fabrication of ceramic matrix composites. Experimental testing and characterization of these materials has been carried out in the NASA Ames Research Center Thermophysics Facilities and in the Ames time-of-flight mass spectrometer facility. By means of computation, we have been better able to understand the flow structure and properties of the TPS components and to estimate the aerothermal heating, stress, ablation rate, thermal response, and shape change on the surfaces of TPS. In addition, work for the computational surface thermochemistry project has included modification of existing computer codes and creating new codes to model material response and shape change on atmospheric entry vehicles in a variety of environments (e.g., earth and Mars atmospheres).
International Nuclear Information System (INIS)
Campos, Adriana de; Marconcini, Jose M.; Mattoso, Luiz H.C.
2011-01-01
Thermal, mechanical and morphological properties of thermoplastic starch (TPS) and polycaprolactone (PCL) blend obtained by extrusion was studied. The results showed that TPS/PCL blends are immiscible, however it is suggested some interaction in the interphase between TPS and PCL as observed by crystallinity decrease of the blend. The PCL addition in the TPS improves the properties and decreases the cost of the blend. (author)
Automation of the Calibration of Reference Dosimeters Used in Radiotherapy
International Nuclear Information System (INIS)
Romero Acosta, A.; Gutierrez Lores, S.
2013-01-01
Traceability, accuracy and consistency of radiation measurements are essential in radiation dosimetry, particularly in radiotherapy, where the outcome of treatments is highly dependent on the radiation dose delivered to patients. The role of Secondary Standard Dosimetry Laboratories (SSDLs) is crucial in providing traceable calibrations to hospitals, since these laboratories disseminate calibrations at specific radiation qualities appropriate to the use of radiation measuring instruments. These laboratories follow IAEA/WHO guidelines for calibration procedures, often being current and charge measurements described in these guidelines a tedious task. However, these measurements are usually done using modern electrometers which are equipped with a RS-232 interface that allows instrument control from a PC. This paper presents the design and employment of an automated system aimed to the measurements of the radiotherapy dosimeters calibration process for Cobalt-60 gamma rays. A software was developed using Lab View, in order to achieve the acquisition of the charge values measured, calculation of the calibration coefficient and issue of a calibration certificate. A primary data report file is filled and stored in the PC's hard disk. By using this software tool, a better control over the calibration process is achieved, it reduces the need for human intervention and it also reduces the exposure of the laboratory staff. The automated system has been used for the calibration of reference dosimeters used in radiotherapy at the Cuban Secondary Standard Dosimetry Laboratory of the Center for Radiation Protection and Hygiene (Author)
Time-resolved dosimetry using a pinpoint ionization chamber as quality assurance for IMRT and VMAT
Energy Technology Data Exchange (ETDEWEB)
Louwe, Robert J. W., E-mail: rob.louwe@ccdbh.org.nz; Satherley, Thomas; Day, Rebecca A.; Greig, Lynne [Department of Radiation Oncology, Wellington Blood and Cancer Centre, Wellington Hospital, Wellington 6242 (New Zealand); Wendling, Markus; Monshouwer, René [Department of Radiation Oncology, Radboud University Medical Center, Nijmegen 6500 HB (Netherlands)
2015-04-15
Purpose: To develop a method to verify the dose delivery in relation to the individual control points of intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) using an ionization chamber. In addition to more effective problem solving during patient-specific quality assurance (QA), the aim is to eventually map out the limitations in the treatment chain and enable a targeted improvement of the treatment technique in an efficient way. Methods: Pretreatment verification was carried out for 255 treatment plans that included a broad range of treatment indications in two departments using the equipment of different vendors. In-house developed software was used to enable calculation of the dose delivery for the individual beamlets in the treatment planning system (TPS), for data acquisition, and for analysis of the data. The observed deviations were related to various delivery and measurement parameters such as gantry angle, field size, and the position of the detector with respect to the field edge to distinguish between error sources. Results: The average deviation of the integral fraction dose during pretreatment verification of the planning target volume dose was −2.1% ± 2.2% (1 SD), −1.7% ± 1.7% (1 SD), and 0.0% ± 1.3% (1 SD) for IMRT at the Radboud University Medical Center (RUMC), VMAT (RUMC), and VMAT at the Wellington Blood and Cancer Centre, respectively. Verification of the dose to organs at risk gave very similar results but was generally subject to a larger measurement uncertainty due to the position of the detector at a high dose gradient. The observed deviations could be related to limitations of the TPS beam models, attenuation of the treatment couch, as well as measurement errors. The apparent systematic error of about −2% in the average deviation of the integral fraction dose in the RUMC results could be explained by the limitations of the TPS beam model in the calculation of the beam penumbra. Conclusions: This
Codes of practice and protocols for the dosimetry in reference conditions of proton and ion beams
International Nuclear Information System (INIS)
Vatnitsky, S.; Andreo, P.
2002-01-01
The advantages of radiotherapy protons and heavier charged-particle beams, the technological feasibility, and the clinical results obtained so far have led to the establishment of about 20 treatment facilities worldwide and plans to open another 20 proton and light-ion therapy centres in the next five years. In order to meet the expanding capabilities of treatment techniques, considerable effort has been devoted during the last fifteen years to the development of the dosimetry and calibration of such beams. This paper reviews these developments and summarizes the present status of Codes of Practice and protocols for the dosimetry in reference conditions of proton and ion beams. The first dosimetry protocol for heavy-particle radiotherapy beams, AAPM TG 20, was based on the use of Faraday cups and calorimeters, whereas ionization chamber dosimetry received little attention. Following the trends in 'nuclear particle' radiotherapy, TG 20 included recommendations for specifying 'dose to tissue'. The lack of availability of a harmonized set of data for the different particles made this protocol to include data for stopping-powers and for the mean energy required to produce and ion pair in air, W air , from multiple authors, without enough attention being paid to their consistency. The increased focus into proton beams was materialized in the publication of the ECHED Code of Practice, dedicated exclusively to protons, where ionization dosimetry received more attention than in TG 20. It was not until the publication of the Supplement to the ECHED recommendations that ionization chambers having a 60 CO calibration factor were recommended as a reference detector for proton dosimetry, and data supplied for chambers with different wall materials. The emphasis on ionization chamber-based proton dosimetry was complemented with a recommendation for using water as dosimetry phantom material and the necessary data on tissue and water to air stopping-power ratios and W air . One of
MO-B-BRB-02: 3D Dosimetry in the Clinic: IMRT Technique Validation in Sweden
Energy Technology Data Exchange (ETDEWEB)
Ceberg, S. [Lund University (Sweden)
2016-06-15
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
MO-B-BRB-02: 3D Dosimetry in the Clinic: IMRT Technique Validation in Sweden
International Nuclear Information System (INIS)
Ceberg, S.
2016-01-01
Full three-dimensional (3D) dosimetry using volumetric chemical dosimeters probed by 3D imaging systems has long been a promising technique for the radiation therapy clinic, since it provides a unique methodology for dose measurements in the volume irradiated using complex conformal delivery techniques such as IMRT and VMAT. To date true 3D dosimetry is still not widely practiced in the community; it has been confined to centres of specialized expertise especially for quality assurance or commissioning roles where other dosimetry techniques are difficult to implement. The potential for improved clinical applicability has been advanced considerably in the last decade by the development of improved 3D dosimeters (e.g., radiochromic plastics, radiochromic gel dosimeters and normoxic polymer gel systems) and by improved readout protocols using optical computed tomography or magnetic resonance imaging. In this session, established users of some current 3D chemical dosimeters will briefly review the current status of 3D dosimetry, describe several dosimeters and their appropriate imaging for dose readout, present workflow procedures required for good dosimetry, and analyze some limitations for applications in select settings. We will review the application of 3D dosimetry to various clinical situations describing how 3D approaches can complement other dose delivery validation approaches already available in the clinic. The applications presented will be selected to inform attendees of the unique features provided by full 3D techniques. Learning Objectives: L. John Schreiner: Background and Motivation Understand recent developments enabling clinically practical 3D dosimetry, Appreciate 3D dosimetry workflow and dosimetry procedures, and Observe select examples from the clinic. Sofie Ceberg: Application to dynamic radiotherapy Observe full dosimetry under dynamic radiotherapy during respiratory motion, and Understand how the measurement of high resolution dose data in an
International Nuclear Information System (INIS)
Magnata, Simey de Souza Leao Pereira
2002-09-01
Absorbed dose determination is an important step for risk assessment related to an exposure to ionizing radiation. However, physical dosimetry cannot be always performed, principally in the case of retrospective estimates. In this context, the use of bioindicators (biological effects) has been proposed, which defines the so-called biological dosimetry. In particular, scoring of unstable chromosomes aberrations (dicentrics, centric rings and fragments) of peripheral blood lymphocytes, while is the most reliable biological method for estimating individual exposure to ionizing radiation. In this work, blood samples from 5 patients, with cervical uterine cancer, were evaluated after partial-body radiotherapy with a source of 69 Co. For this, conventional cytogenetic method was employed, based on Giemsa coloration and fluorescence in situ hybridization, in order to correlate the frequency of unstable chromosome aberrations of blood lymphocytes with absorbed dose, as a result of the radiotherapy. A good agreement was observed between the frequency of chromosome aberrations scored and the values of dose previously calculated by physical dosimetry during patient's radiotherapy. The results presented in this work point out the importance of concerning analyses of unstable chromosome aberrations as biological dosimeter in the investigation of partial-body exposure to ionizing radiation. (author)
International Nuclear Information System (INIS)
Miljanic, S.; Knezevic, Z.; Bessieres, I.; Bordy, J.-M.; D'Agostino, E.; d'Errico, F.; di Fulvio, A.; Domingo, C.; Olko, P.; Stolarczyk; Silari, M.; Harrison, R.
2011-01-01
It has been known for a long time that patients treated with ionizing radiation carry a risk of developing radiation induced cancer in their lifetimes. It is recognized that cure/survival rates in radiotherapy are increasing, but so are secondary cancers. These occurrences are amplified by the early detection of disease in younger patients. These patients are cured from the primary disease and have long life-expectancies, which increase their chances of developing secondary malignancies. The motivation of the EURADOS Working Group 9 (WG 9) ''Radiation protection dosimetry in medicine'' is to assess undue non-target patient doses in radiotherapy and the related risks of secondary malignancy with the most accredited available methods and with the emphasis on a thorough evaluation of dosimetry methods for the measurements of doses remote from the target volume, in phantom experiments. The development of a unified and comprehensive dosimetry methodology for non-target dose estimation is the key element of the WG9 current work. The first scientific aim is to select and review dosimeters suitable for photon and neutron dosimetry in radiotherapy and to evaluate the characteristics of dosimeters at CEA LIST Saclay in reference clinical LINAC beam. (author)
International Nuclear Information System (INIS)
2008-01-01
Quality Assurance (QA) in the radiation therapy treatment planning process is essential to ensure accurate dose delivery to the patient and to minimize the possibility of accidental exposure. Computerized radiotherapy treatment planning systems (RTPSs) are now widely available in both industrialised and developing countries so, it is of special importance to support hospitals in the IAEA Member States in developing procedures for acceptance testing, commissioning and ongoing QA of their RTPSs. Responding to these needs, a group of experts developed a comprehensive report, the IAEA Technical Reports Series No 430 'Commissioning and quality assurance of computerized planning systems for radiation treatment of cancer', that provides the general framework and describes a large number of tests and procedures to be considered by the RTPS users. To provide practical guidance for implementation of IAEA Technical Reports Series No. 430 in radiotherapy hospitals and particularly in those with limited resources, a coordinated research project (CRP E2.40.13) 'Development of procedures for dosimetry calculation in radiotherapy' was established. The main goal of the project was to create a set of practical acceptance and commissioning tests for dosimetry calculations in radiotherapy, defined in a dedicated protocol. Two specific guidance publications that were developed in the framework of the Coordinated Research Project E2.40.13 are based on guidelines described in the IAEA Technical Report Series No. 430 and provide a step-by-step description for users at hospitals or cancer centres how to implement acceptance and commissioning procedures for their RTPSs. The first publication, 'Specification and acceptance testing of radiotherapy treatment planning systems' IAEA-TECDOC-1540 uses the International Electrotechnical Commission (IEC) standard IEC 62083 as its basis and addresses the procedures for specification and acceptance testing of RTPSs to be used by both manufacturers and
High-accuracy dosimetry study for intensity-modulated radiation therapy(IMRT) commissioning
International Nuclear Information System (INIS)
Jeong, Hae Sun
2010-02-01
Intensity-modulated radiation therapy (IMRT), an advanced modality of high-precision radiotherapy, allows for an increase in dose to the tumor volume without increasing the dose to nearby critical organs. In order to successfully achieve the treatment, intensive dosimetry with accurate dose verification is necessary. A dosimetry for IMRT, however, is a challenging task due to dosimetric ally unfavorable phenomena such as dramatic changes of the dose at the field boundaries, dis-equilibrium of the electrons, non-uniformity between the detector and the phantom materials, and distortion of scanner-read doses. In the present study, therefore, the LEGO-type multi-purpose dosimetry phantom was developed and used for the studies on dose measurements and correction. Phantom materials for muscle, fat, bone, and lung tissue were selected after considering mass density, atomic composition, effective atomic number, and photon interaction coefficients. The phantom also includes dosimeter holders for several different types of detectors including films, which accommodates a construction of different designs of phantoms as necessary. In order to evaluate its performance, the developed phantom was tested by measuring the point dose and the percent depth dose (PDD) for small size fields under several heterogeneous conditions. However, the measurements with the two types of dosimeter did not agree well for the field sizes less than 1 x 1 cm 2 in muscle and bone, and less than 3 x 3 cm 2 in air cavity. Thus, it was recognized that several studies on small fields dosimetry and correction methods for the calculation with a PMCEPT code are needed. The under-estimated values from the ion chamber were corrected with a convolution method employed to eliminate the volume effect of the chamber. As a result, the discrepancies between the EBT film and the ion chamber measurements were significantly decreased, from 14% to 1% (1 x 1 cm 2 ), 10% to 1% (0.7 x 0.7 cm 2 ), and 42% to 7% (0.5 x 0
Conformal Ablative Thermal Protection Systems (CA-TPS) for Venus and Saturn Backshells
Beck, R.; Gasch, M.; Stackpoole, M.; Wilder, M.; Boghozian, T.; Chavez-Garcia, J.; Prabhu, Dinesh; Kazemba, Cole D.; Venkatapathy, E.
2016-01-01
This poster provides an overview of the work performed to date on the Conformal Ablative TPS (CA-TPS) element of the TPSM project out of GCDP. Under this element, NASA is developing improved ablative TPS materials based on flexible felt for reinforcement rather than rigid reinforcements. By replacing the reinforcements with felt, the resulting materials have much higher strain-to-failure and are much lower in thermal conductivity than their rigid counterparts. These characteristics should allow for larger tile sizes, direct bonding to aeroshells and even lower weight TPS. The conformal phenolic impregnated carbon felt (C-PICA) is a candidate for backshell TPS for both Venus and Saturn entry vehicles.
International Nuclear Information System (INIS)
Pasquier, David
2006-01-01
Radiotherapy is a curative treatment of malignant tumours. Radiotherapy techniques considerably evolved last years with the increasing integration of medical images in conformal radiotherapy. This technique makes it possible to elaborate a complex ballistics conforming to target volume and sparing healthy tissues. The examination currently used to delineate volumes of interest is Computed Tomography (CT), on account of its geometrical precision and the information that it provides on electronic densities needed to dose calculation. Magnetic Resonance Imaging (MRI) ensures a more precise delineation of target volumes in many locations, such as pelvis and brain. For pelvic tumours, the use of MRI needs image registration, which complicates treatment planning and poses the problem of the lack of in vivo standard method of validation. The obstacles in the use of MRI alone in treatment planning were evaluated. Neither geometrical distortion linked with the system and the patient nor the lack of information on electronic densities represent stumbling obstacles. Distortion remained low even in edge of large field of view on modern machines. The assignment of electronic densities to bone structures and soft tissues in MR images permitted to obtain equivalent dosimetry to that carried out on the original CT, with a good reproducibility and homogeneous distribution within target volume. The assignment of electronic densities could not be carried out using 20 MV photons and suitable ballistics. The development of Image Guided Radiotherapy could facilitate the use of MRI alone in treatment planning. Target volumes and organ at risk delineation is a time consuming task in radiotherapy planning. We took part in the development and evaluated a method of automatic and semi automatic delineation of volumes of interest from MRI images for prostate cancer radiotherapy. For prostate and organ at risk automatic delineation an organ model-based method and a seeded region growing method
Dosimetry applications in GATE Monte Carlo toolkit.
Papadimitroulas, Panagiotis
2017-09-01
Monte Carlo (MC) simulations are a well-established method for studying physical processes in medical physics. The purpose of this review is to present GATE dosimetry applications on diagnostic and therapeutic simulated protocols. There is a significant need for accurate quantification of the absorbed dose in several specific applications such as preclinical and pediatric studies. GATE is an open-source MC toolkit for simulating imaging, radiotherapy (RT) and dosimetry applications in a user-friendly environment, which is well validated and widely accepted by the scientific community. In RT applications, during treatment planning, it is essential to accurately assess the deposited energy and the absorbed dose per tissue/organ of interest, as well as the local statistical uncertainty. Several types of realistic dosimetric applications are described including: molecular imaging, radio-immunotherapy, radiotherapy and brachytherapy. GATE has been efficiently used in several applications, such as Dose Point Kernels, S-values, Brachytherapy parameters, and has been compared against various MC codes which are considered as standard tools for decades. Furthermore, the presented studies show reliable modeling of particle beams when comparing experimental with simulated data. Examples of different dosimetric protocols are reported for individualized dosimetry and simulations combining imaging and therapy dose monitoring, with the use of modern computational phantoms. Personalization of medical protocols can be achieved by combining GATE MC simulations with anthropomorphic computational models and clinical anatomical data. This is a review study, covering several dosimetric applications of GATE, and the different tools used for modeling realistic clinical acquisitions with accurate dose assessment. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
Conformal radiotherapy using multileaf collimation: quality assurance and in vivo dosimetry
Energy Technology Data Exchange (ETDEWEB)
Aletti, P [Centre A. Vautrin, Nancy (France)
1995-12-01
The application of quality assurance principles in three dimensional conformal therapy is discussed.Critical requirements in three dimensional radiotherapy are the patient immobilization, the location, and the delivered dose. General recommendations with respect to the equipment for conformal radiotherapy and personnel are made.
Conformal radiotherapy using multileaf collimation: quality assurance and in vivo dosimetry
International Nuclear Information System (INIS)
Aletti, P.
1995-01-01
The application of quality assurance principles in three dimensional conformal therapy is discussed.Critical requirements in three dimensional radiotherapy are the patient immobilization, the location, and the delivered dose. General recommendations with respect to the equipment for conformal radiotherapy and personnel are made
INEEL Advanced Radiotherapy Research Program Annual Report for 2002
Energy Technology Data Exchange (ETDEWEB)
J. R. Venhuizen
2003-05-01
This report summarizes the activities and major accomplishments for the Idaho National Engineering and Environmental Laboratory (INEEL) Advanced Radiotherapy Research Program for calendar year 2002. Topics covered include computational dosimetry and treatment planning software development, medical neutron source development and characterization, and boron analytical chemistry.
Patient dosimetry improvements in longitudinal field MRI linear accelerators
International Nuclear Information System (INIS)
Oborn, B.M.; Metcalfe, P.E.; Butson, M.J.; Keall, P.
2010-01-01
Full text: Many studies exist of the often undesirable dosimetry changes in transverse field MRI-Linacs. Currently there are plans by different groups around the world to develop longitudinal MRT-Linac systems as dosimetry is potentially superior to transverse field sy tems. The objective of this study is to investigate via Monte Carlo simulations, the potential dosimetry improvements expected in lo gitudinal MRI-Linac designs over transverse field designs for advanced image-guided radiotherapy (IGRT). Geant4 Monte Carlo simulations have been performed of the dosimetry from a Varian 2100c 6 MV photon beam in lo gitudinal magnetic field typical of expected MRI-Linac designs. A 30 x 30 x 20 cm' phantom has been simulated in magnetic fields between 0 and 3 T. Beam profiles and skin dose calculations have been performed and compared with transverse field systems. Results The longitudinal magnetic field acts to reduce lateral dose spread in all locations within a patient. As well as this, the electron return effcct is absent. This equates to reductions in penumbral widths and reductions in skin dose. When compared with transverse field systems the dosimetry is superior. This will also allow for further reductions in trcatment margins as compared to transverse field MRI Linac designs.
Chemical dosimetry techniques for various applications under different geometries
Gupta, B L; Narayan, G R; Nilekani, S R
2000-01-01
This paper gives the results of dosimetry for various applications under different geometrical arrangements. These applications include: gamma chambers, blood irradiators, radiotherapy using both sup 6 sup 0 Co and accelerators, animal irradiations with different types of radiation sources, fluid irradiators for sludge and rubber latex and industrial electron irradiators. The dosimeters used were Fricke, FBX and alanine/glutamine (spectrophotometric readout).
International Nuclear Information System (INIS)
Gwiazdowska, B.; Bulski, W.
2004-01-01
The aim of this paper is to present the history and experience of the Polish SSDL (Secondary Standard Dosimetry Laboratory). It also presents the propositions in the domain of quality assurance in radiotherapy in Poland, as fulfilling the requirements of the Directive 97/43 EURATOM on health protection of individuals against the dangers of ionizing radiation in relation to medical exposure, which is obligatory for the countries of the European Union. It has been pointed out that there are, among other provisions, two concepts concerning the quality assurance in application of radiation in medicine, mentioned by the Directive, a) inspection and b) clinical audit, which should be implemented by the Member States. In the process of establishing and implementing the Directive confusion may appear as to the difference between the two concepts of external audits. The role of the SSDLs in carrying out external dosimetry audits is presented. The history of the establishment of the Polish SSDL (Secondary Standard Dosimetry Laboratory) and its inclusion into the international network of laboratories coordinated by the International Atomic Energy Agency and the World Health Organization is presented as well as the resulting advantages, obligations and perspectives for further activities. The main activities of the Polish have been presented, namely maintaining a data-base on the radiotherapy infrastructure in Poland, preparation of recommendations on dosimetry procedures and quality control, calibration of dosimeters, external postal quality audits of dosimetry, etc. These activities are illustrated with the results from the period 1991-2003. Based on the solutions and results presented in this paper, the authors conclude that the Ministry of Health should grant the Polish SSDL with a suitable legal status for carrying out external audits nationwide, especially since, according to the Directive 97/43, clinical audits in radiotherapy have to include dosimetry audits. (author)
2001 report on Medical Physics in France. Radiotherapy-Chemotherapy Group, Cancer Plan 2000-2005
International Nuclear Information System (INIS)
Aubert, Bernard; Delpech, Jean-Paul; Estivallet, Andre; Estrade, Georges; Francois, Pascal; Gardin, Isabelle; Giraud, Jean-Yves; Lisbonna, Andre; Naudy, Suzanne; Noel, Alain; Sarrazin, Thierry
2001-01-01
This report first presents the medical physics sector by indicating physicist responsibilities, by describing the situation in France, in Europe and in the World, and by analysing the French situation. In the next part, the authors presents and comments the various fields of intervention: radiotherapy, nuclear medicine (dosimetry and patient radiation protection, optimisation and quality assurance, development and use of complex equipment and techniques, recommendations at the national and international level), radiology (image quality, reduction of doses received by patients), and radiation protection. They briefly describe physicist basic and continue training, the status of physicists in public hospitals, and technical means (present status, proposals for radiotherapy equipment, for simulation and control equipment, and for dosimetry equipment)
Energy Technology Data Exchange (ETDEWEB)
Reich, H [ed.
1990-01-01
In the first chapter of the book, a brief description is given of the historical development of dosimetry, of its objectives and special role within the context of general physical metrology, followed by detailed explanations of the physical fundamentals of this science: the sources and fields of radiation, interactions between radiation and matter as well as radiation detectors. The terminology and units of measurement used in dosimetry are explained in a separate chapter. Chapters 7 and 8, which outline the various theoretical and experimental methods of dose determination, are the most essential contributions to this volume. Chapter 9 deals with the ways in which dosimetry is used in special cases in radiotherapy as well as in the measurement of very small or very large doses. Chapter 10 gives a survey of recently introduced units of measurements and methods to calculate the body dose with reference to the particular type of exposure used. Appendix A contains tables of measuring units, physical constants and measuring techniques along with at-a-glance information on the legal regulations concerning the calibration of dosimeters. Appendix B gives practical guidance on the handling of hardware-related inaccuracies of measurement in dose determination procedures and appendix C embraces 22 pages of tables showing data on radiation physics. (orig./HP) With 150 figs., 50 tabs. in the text, and annex with tables.
Beam monitoring in radiotherapy and hadron-therapy
International Nuclear Information System (INIS)
Fontbonne, J.M.
2012-01-01
Radiotherapy techniques have evolved over the past twenty years. For photon beams, the development of tools such as multi leaf collimators, machines such as Cyberknife or tomo-therapy, have improved the conformation of treatments to the tumor volume and lowered maximum dose to healthy tissue. In another register, the use of proton-therapy is expanding in all countries and the development of carbon ions beams for hadron-therapy is also increasing. If techniques improve, the control requirements for the monitoring of the dose administered to patients are always the same. This document presents, first, the ins and outs of the different techniques of external beam radiotherapy: photon treatments, protons and hadrons. Starting from the basis of clinical requirements, it sets the variables to be measured in order to ensure the quality of treatment for the different considered modalities. It then describes some implementations, based on precise and rigorous specifications, for the monitoring and measurement of beams delivered by external beam radiotherapy equipments. Two instrumental techniques are particularly highlighted, plastic scintillators dosimetry for the control of megavoltage photon beams and ionization chamber dosimetry applied to proton-therapy or radiobiology experiments conducted at the GANIL facility. Analyzes and perspectives, based on the recent developments of treatment techniques, are delivered in conclusion and can serve as guide for future instrumental developments. (author)
Cardiovascular dosimetry using hybrid computational phantoms after external radiotherapy
International Nuclear Information System (INIS)
Moignier, Alexandra
2014-01-01
Cardiovascular diseases following radiotherapy are major secondary late effects raising questions among the scientific community, especially regarding the dose-effect relationship and confounding risk factors (chemotherapy, cholesterolemia, age at treatment, blood pressure,..). Post-radiation coronary diseases are one of the main causes of cardiac morbidity. Some approximations are made when coronary doses due to radiotherapy are estimated, especially regarding the morphology. For retrospective studies with old medical records, only radiographs are usually available with sometimes some contours made with a simulator. For recent medical records, CT scans displaying the anatomy in 3D are used for radiotherapy simulation but do not allow the coronary artery visualization due to low resolution and contrast. Currently, coronary doses are barely assessed in clinical practice, and when it is done, anatomical prior knowledge is generally used. This thesis proposes an original approach based on hybrid computational phantoms to study coronary artery doses following radiotherapy for left-side breast cancer and Hodgkin lymphoma. During the thesis, a method inserting hybrid computational phantoms in a DICOM format into the treatment planning system has been developed and validated. It has been adapted and tested in conditions where only radiographs provide anatomical information, as with old medical records for left side breast radiotherapy. The method has also been adapted to perform precise dose reconstructions to the coronary artery for patients treated for a mediastinal Hodgkin lymphoma and diagnosed with coronary stenosis through a coro-scanner. A case-control study was carried out and the risk of coronary stenosis on a coronary artery segment was assessed to be multiplied by 1.049 at each additional gray on the median dose to the coronary artery segment. For recent medical records, coronary doses uncertainties related to an approach by anatomical prior knowledge
International Nuclear Information System (INIS)
Kozak, Kevin R.; Kachnic, Lisa A.; Adams, Judith C; Crowley, Elizabeth M.; Alexander, Brian M.; Mamon, Harvey J.; Fernandez-Del Castillo, Carlos; Ryan, David P.; DeLaney, Thomas F.; Hong, Theodore S.
2007-01-01
Purpose: To evaluate tumor and normal tissue dosimetry of a 5 cobalt gray equivalent (CGE) x 5 fraction proton radiotherapy schedule, before initiating a clinical trial of neoadjuvant, short-course proton radiotherapy for pancreatic adenocarcinoma. Methods and Materials: The first 9 pancreatic cancer patients treated with neoadjuvant intensity-modulated radiotherapy (1.8 Gy x 28) at the Massachusetts General Hospital had treatment plans generated using a 5 CGE x 5 fraction proton regimen. To facilitate dosimetric comparisons, clinical target volumes and normal tissue volumes were held constant. Plans were optimized for target volume coverage and normal tissue sparing. Results: Hypofractionated proton and conventionally fractionated intensity-modulated radiotherapy plans both provided acceptable target volume coverage and dose homogeneity. Improved dose conformality provided by the hypofractionated proton regimen resulted in significant sparing of kidneys, liver, and small bowel, evidenced by significant reductions in the mean doses, expressed as percentage prescribed dose, to these structures. Kidney and liver sparing was most evident in low-dose regions (≤20% prescribed dose for both kidneys and ≤60% prescribed dose for liver). Improvements in small-bowel dosimetry were observed in high- and low-dose regions. Mean stomach and duodenum doses, expressed as percentage prescribed dose, were similar for the two techniques. Conclusions: A proton radiotherapy schedule consisting of 5 fractions of 5 CGE as part of neoadjuvant therapy for adenocarcinoma of the pancreas seems dosimetrically feasible, providing excellent target volume coverage, dose homogeneity, and normal tissue sparing. Hypofractionated proton radiotherapy in this setting merits Phase I clinical trial investigation
High Radiation Doses from Radiotherapy Measured by Electron Spin Resonance in Dental Enamel
International Nuclear Information System (INIS)
Pass, B.; Wood, R.E.; Liu, F.; McLean, M.; Aldrich, J.E.
1998-01-01
For radiotherapy, an error in the complicated treatment planning or treatment procedure is a possibility, however remote. Thus, in the present study electron spin resonance (ESR) in dental enamel was investigated for the first time as a means of retrospective dosimetry for validating applied radiotherapy doses to the head and neck regions. Total absorbed radiation doses measured by ESR in dental enamel were compared to the doses determined by treatment planning for 19 patients who received radiotherapy for intra-oral, pharyngeal or laryngeal malignancies, or total-body irradiation prior to bone marrow transplants (BMT). For the 15 tumour irradiations there was, within the framework of the tooth positions as presented, general agreement between the treatment planned and ESR dose determinations. There were, however, both significant and minor discrepancies. For the BMT patients there were major discrepancies for two of the four patients investigated. This study indicates that ESR in dental enamel may be useful as the only means of retrospective dosimetry for validating applied radiotherapy doses after treatment. However, further research must be carried out before this technique can be accepted as accurate and reliable. (author)
Tangential breast irradiation - rationale and methods for improving dosimetry
International Nuclear Information System (INIS)
Neal, A.J.; Mayles, W.P.M.; Yarnold, J.R.
1994-01-01
In recent years there have been great advances and innovations in all technical aspects of radiotherapy, including three dimensional (3D) computer planning, patient immobilization, radiation delivery and treatment verification. Despite this progress, the technique of tangential breast irradiation has changed little over this period and has not exploited these advances. There is increasing evidence that dose inhomogeneity within the breast is greater than at other anatomical sites, especially in women with large breasts. This paper is a review of the factors contributing to poor dosimetry in the breast, the clinical consequences of an inhomogeneous dose distribution, and how breast dosimetry could be improved by considering each of the stages from planning to accurate treatment delivery. It also highlights the particular problem of women with large breasts who may be more likely to have a poorer outcome after a fractionated course of radiotherapy than women with small/medium-sized breasts, and supports the clinical impression that such women are also more likely to have greater inhomogenicity when 3D treatment plans are examined. Preliminary data from our current computed tomography (CT) planning study are presented to support these observations. (author)
The effect of different dopant concentration of tailor-made silica fibers in radiotherapy dosimetry
Begum, Mahfuza; Mizanur Rahman, A. K. M.; Zubair, H. T.; Abdul-Rashid, H. A.; Yusoff, Z.; Begum, Mahbuba; Alkhorayef, M.; Alzimami, K.; Bradley, D. A.
2017-12-01
In thermoluminescence (TL) material dopant concentration has an important effect on their characteristics as a ;radiation-sensor;. The study investigates dosimetric properties of four different concentration (4 mol%, 5 mol%, 7 mol% and 25 mol%) tailor-made Ge-doped silica fibers. The intention is to seek development of alternative TL materials that offer exceptional advantages over existing passive systems of dosimetry, including improved spatial resolution, a water impervious nature and low cost. Photon beams (6 MV and 10 MV) from a clinical linear accelerator were used for irradiation of the fiber samples over radiation therapy doses, ranging from 0.5 Gy to 8 Gy. SEM-EDX analysis was also performed to investigate the homogeneity of distribution of Ge dopant concentration from the fiber samples. The results of measurement were also compared with two of the more commonly used standard TLDs, TLD-100 (LiF: Mg,Ti-7.5% 6LiF) and TLD-700 ((7LiF: Mg,Ti-99.9%7LiF) chips respectively. The TL intensity of the fiber samples was found to strongly depend on Ge dopant concentration, with samples showing enhanced TL yields with decreasing Ge dopant concentration. 4 mol% Ge-doped silica fiber provided the greatest response whereas the 25 mol% samples showed the least, indicative of the well-known concentration quenching effects All fiber TLDs provided linear dose response over the delivered radiotherapy dose-range, the fibers also showing a weak dependence on photon beam energies in comparing the TL yields at 6 and 10 MV. The fading behavior of the different concentration Ge doped TLD-materials were also measured over a period of thirty (30) days subsequent to irradiation. The relative sensitivity of the samples with respect to standard TLD-100 were found to be 0.37, 0.26, 0.13 and 0.02 in respect of the 4, 5, 7 and 25 mol% fibers. The primary dosimetry peak, which was by far the most prominent of any other feature covered by the glow curve, was found to be around 244 °C using
International Nuclear Information System (INIS)
Ostrowsky, A.; Bordy, J.M.; Daures, J.; De Carlan, L.; Delaunay, F.
2010-01-01
Solving the problem of traceability of the absorbed dose to the tumour for the radiation fields of small and very small dimensions, like those used for new treatment modality usually results in the use of dosemeters of much smaller size than those of the beam. For the realisation of the reference in primary standards laboratories, the absence of technology likely to produce absolute small-size dosemeters leaves no possibility for the direct measurement of the absorbed dose at a point and implies the use of passive or active small-size transfer dosemeters. This report intends to introduce a new kind of dose quantity for radiotherapy similar do the Dose Area Product concept used in radiology. Such a new concept has to be propagated through the metrology chain, including the TPS, to the calculation of the absorbed dose to the tumour. (authors)
TLD Quality Assurance (QA) network in radiotherapy and radiology in the Czech Republic
International Nuclear Information System (INIS)
Kroutilikova, D.; Novak, N.; Novotny, J.
2002-01-01
Full text: The Czech TLD QA network was established in 1997, as a part of the External Auditing Group (EAG) originated in 1995, in order to perform an independent quality audit in external beam therapy for two purposes: a) to unify the dose within radiotherapy departments, b) to impact state supervision. On basis of a good experience with this network in radiotherapy, new methods were developed to expand the network also to radiology in order to simplify the operation of state supervision. The TLD QA network in dental radiology has been brought into practice in 2001. Both the TLD audits performed in radiotherapy and radiology are realized via mailed dosimetry. In radiotherapy, two modes of the audit are used. Basic mode of TLD audit covers measurements under reference conditions, specifically beam calibration checks for all clinically used photon and electron beams. According to Czech regulations every beam must be checked in this way at least once during two years' period. Advanced mode consists of measurements under both reference and non- reference conditions using Leuven multi-purpose phantom for photon beams. It enables to check a substantial part of the treatment planning process inclusive of final dose realization of the planned radiotherapy. The radiotherapy centers are instructed to deliver absorbed dose of 2 Gy to the TLDs on central beam axis based on calculated treatment time or monitor units by their treatment planning system for a particular treatment set-up. In this way the TLD measured doses are compared with the calculated ones. Deviations of ±3% are considered acceptable for both basic and advanced modes of the audit, deviations up to ±6% are still tolerable, but new audit is repeated as soon as possible to solve the dosimetry problem. Deviations above ±6% leads immediately to investigation by EAG. There are 34 centers in the Czech Republic, which provide external beam radiotherapy. Since they must undergo the basic TLD audit regularly every
International Nuclear Information System (INIS)
Goldsmith, Christy; Haviland, Joanne; Tsang, Yat; Sydenham, Mark; Yarnold, John
2011-01-01
Background and Purpose: Large breast size is associated with an increased risk of late adverse effects after breast conservation surgery and radiotherapy, even when 3D dosimetry is used. The purpose of this study is to test the hypothesis that residual dose inhomogeneity is sufficient to explain the association. Methods: Patients previously treated after breast conservation surgery with whole breast radiotherapy using 3D dosimetry and followed up in the UK FAST hypofractionation trial were selected for this analysis. The residual level of dose inhomogeneity across the whole breast treatment volume was used to test for association between residual dosimetry and post-treatment change in breast appearance at 2 years post-radiotherapy. Results: At 2 years, 201/279 (72%) of women had no change in photographic breast appearance, 61 (22%) had mild change and 17 (6%) had marked change. Breast size and dosimetry were both significantly associated with late effects in univariate analyses, but only breast size remained an independent significant risk factor for change in breast appearance when included in a multiple regression model together with other prognostic factors (p = 0.006 for trend). Conclusion: Large-breasted women are more likely to suffer change in breast size and shape after whole breast radiotherapy delivered using 3D dosimetry, but residual dose inhomogeneity is insufficient to explain the association.
Energy Technology Data Exchange (ETDEWEB)
Pappas, E; Maris, T G; Zacharopoulou, F; Papadakis, A [Department of Medical Physics, Faculty of Medicine, University of Crete, 711 10 Stavrakia-Heraklion, Crete (Greece); Manolopoulos, S; Green, S [Queen Elizabeth Medical Centre, University Hospital Birmingham NHS Trust, Birmingham B15 2TH (United Kingdom); Wojnecki, C, E-mail: epappas@edu.med.uoc.gr
2009-05-01
Small photon fields are increasingly used in modern radiotherapy and especially in IMRT and SRS/SRT treatments. Accurate beam profile measurements of such beams are crucial for a precise and effective treatment. In this work four different dosimetric methods have been used for profile measurements of three small 6 MV circular fields having diameters of 7.5, 15.0 and 30.0 mm. A small sensitive volume air ion chamber, a diamond detector, a novel silicon-diode array and Vinyl-Pyrrolidone based polymer gel dosimetry. The results of this work reveal the well-known disadvantages and/or problems of the conventional dosimeters for this kind of measurements and support that polymer gel dosimetry may overcome these problems. Conclusively, it is estimated that polymer gels could play an important role towards the minimization of the total SRS/SRT treatment error that is related with small field profile measurements.
International Nuclear Information System (INIS)
Villani, Daniel; Campos, LetIcia L.; Mancini, Anselmo; Haddad, Cecilia M.K.
2016-01-01
In modern radiotherapy, the VMAT technique has become a successful treatment alternative. Due to its complexity, a quality assurance program must be established by evaluating, among other items, the dosimetric factors. This paper aims to compare the performance between the OSL aluminum oxide (Al_2O_3:C) nanoDot™ dosimeters (Inlight™ system) manufactured by Landauer Inc. and TLD-500 Al_2O_3:C dosimeters manufactured by Rexon™ for VMAT dosimetry using an anthropomorphic phantom. The results showed that both type of Al_2O_3:C dosimeters presented good repeatability and agreement between the doses measured and calculated by planning system. However, the need of sophisticated readers to OSL analysis of the TLD-500, turns it less practical for routine usage, comparing to Inlight™ system. (author)
Physical and biological basis of hadron radiotherapy. Book of abstracts
International Nuclear Information System (INIS)
2011-09-01
The Workshop was a satellite event of the 14 th International Congress of Radiation Research (ICRR-2011). It was held in Cracow, Poland, on the 2 and 3 September 2011, at the Collegium Novum of the Jagiellonian University. The Workshop organized, jointly by the Institute of Nuclear Physics of the Polish Academy of Sciences and the Polish Radiation Research Society, would provide its participants with an opportunity to discuss current topics in proton and carbon radiotherapy, clinical aspects of ion radiotherapy, ion beam dosimetry, unwanted patient exposure, radiobiology for ion radiotherapy and other relevant subjects. Book of Abstracts contains abstracts of 33 oral presentations and 12 posters.
Directory of Open Access Journals (Sweden)
Khosravi H.
2015-03-01
Full Text Available Background: Gel polymers are considered as new dosimeters for determining radiotherapy dose distribution in three dimensions. Objective: The ability of a new formulation of MAGIC-f polymer gel was assessed by experimental measurement and Monte Carlo (MC method for studying the effect of gold nanoparticles (GNPs in prostate dose distributions under the internal Ir-192 and external 18MV radiotherapy practices. Method: A Plexiglas phantom was made representing human pelvis. The GNP shaving 15 nm in diameter and 0.1 mM concentration were synthesized using chemical reduction method. Then, a new formulation of MAGIC-f gel was synthesized. The fabricated gel was poured in the tubes located at the prostate (with and without the GNPs and bladder locations of the phantom. The phantom was irradiated to an Ir-192 source and 18 MV beam of a Varian linac separately based on common radiotherapy procedures used for prostate cancer. After 24 hours, the irradiated gels were read using a Siemens 1.5 Tesla MRI scanner. The absolute doses at the reference points and isodose curves resulted from the experimental measurement of the gels and MC simulations following the internal and external radiotherapy practices were compared. Results: The mean absorbed doses measured with the gel in the presence of the GNPs in prostate were 15% and 8 % higher than the corresponding values without the GNPs under the internal and external radiation therapies, respectively. MC simulations also indicated a dose increase of 14 % and 7 % due to presence of the GNPs, for the same experimental internal and external radiotherapy practices, respectively. Conclusion: There was a good agreement between the dose enhancement factors (DEFs estimated with MC simulations and experiment gel measurements due to the GNPs. The results indicated that the polymer gel dosimetry method as developed and used in this study, can be recommended as a reliable method for investigating the DEF of GNPs in internal
Khosravi, H; Hashemi, B; Mahdavi, S R; Hejazi, P
2015-03-01
Gel polymers are considered as new dosimeters for determining radiotherapy dose distribution in three dimensions. The ability of a new formulation of MAGIC-f polymer gel was assessed by experimental measurement and Monte Carlo (MC) method for studying the effect of gold nanoparticles (GNPs) in prostate dose distributions under the internal Ir-192 and external 18MV radiotherapy practices. A Plexiglas phantom was made representing human pelvis. The GNP shaving 15 nm in diameter and 0.1 mM concentration were synthesized using chemical reduction method. Then, a new formulation of MAGIC-f gel was synthesized. The fabricated gel was poured in the tubes located at the prostate (with and without the GNPs) and bladder locations of the phantom. The phantom was irradiated to an Ir-192 source and 18 MV beam of a Varian linac separately based on common radiotherapy procedures used for prostate cancer. After 24 hours, the irradiated gels were read using a Siemens 1.5 Tesla MRI scanner. The absolute doses at the reference points and isodose curves resulted from the experimental measurement of the gels and MC simulations following the internal and external radiotherapy practices were compared. The mean absorbed doses measured with the gel in the presence of the GNPs in prostate were 15% and 8 % higher than the corresponding values without the GNPs under the internal and external radiation therapies, respectively. MC simulations also indicated a dose increase of 14 % and 7 % due to presence of the GNPs, for the same experimental internal and external radiotherapy practices, respectively. There was a good agreement between the dose enhancement factors (DEFs) estimated with MC simulations and experiment gel measurements due to the GNPs. The results indicated that the polymer gel dosimetry method as developed and used in this study, can be recommended as a reliable method for investigating the DEF of GNPs in internal and external radiotherapy practices.
Role of TPS in 125I brachytherapy for orbital tumors
International Nuclear Information System (INIS)
Ren Ling; Dai Haojie; Li Quan
2012-01-01
Objective: To investigate the role of TPS in 125 I brachytherapy for orbital tumors. Methods: Sixty-six patients with orbital tumor treated with 125 I seeds from 2005 to 2009 were retrospectively analyzed. Forty-three patients were treated using TPS guided brachytherapy and the prescribed dose was 140 Gy. Other 23 patients were treated without TPS but simply implanted with 125 I seeds at 1 cm intervals in parallel with each other intraoperatively. CT and TPS quality verification were performed postoperatively in all patients. Also, CT and (or) MRI examination were performed at 3, 6, 12 and 24 months after brachytherapy for follow-up. χ 2 test and Kaplan-Meier survival analysis with log-rank significance test were used with SPSS 17.0. Results: A total of 1070 125 I seeds were implanted in 66 cases, on average, (16.2 ± 7.3) seeds for each patient. The satisfaction rates of postoperative quality verification in patients with and without TPS pre-plans were 79.07% (34/43) and 43.48% (10/23) respectively (χ 2 =8.542, P=0.003). Ten patients were lost in follow-up. Local recurrence rates in patients with favorable postoperative quality verification were 0 (0/37) in 3 months, 6.25% (2/32) in 6 months, 13.64% (3/22) in 12 months and 3/9 in 24 months respectively, which were significantly different from those (5.26% (1/19), 16.67% (3/18), 30.77% (4/13), 6/6) in the patients with inferior postoperative quality verification (χ 2 =9.017, P=0.0003). Conclusions: TPS plays an important role in 125 I brachytherapy for orbital tumors. Also, postoperative quality verification by TPS may help predict the local recurrence after brachytherapy. (authors)
The IAEA/WHO TLD postal programme for radiotherapy hospitals
International Nuclear Information System (INIS)
Izewska, J.; Andreo, P.
2000-01-01
Since 1969 the International Atomic Energy Agency (IAEA), together with the World Health Organization (WHO), has performed postal TLD audits to verify the calibration of radiotherapy beams in developing countries. A number of changes have recently been implemented to improve the efficiency of the IAEA/WHO TLD programme. The IAEA has increased the number of participants and reduced significantly the total turn-around time to provide results to the hospitals within the shortest possible time following the TLD irradiations. The IAEA has established a regular follow-up programme for hospitals with results outside acceptance limits of ±5%. The IAEA has, over 30 years, verified the calibration of more than 3300 clinical photon beams at approximately 1000 radiotherapy hospitals. Only 65% of those hospitals who receive TLDs for the first time have results within the acceptance limits, while more than 80% of the users that have benefited from a previous TLD audit are successful. The experience of the IAEA in TLD audits has been transferred to the national level. The IAEA offers a standardized TLD methodology, provides Guidelines and gives technical back-up to the national TLD networks. The unsatisfactory status of the dosimetry for radiotherapy, as noted in the past, is gradually improving however, the dosimetry practices in many hospitals in developing countries need to be revised in order to reach adequate conformity to hospitals that perform modern radiotherapy in Europe, USA and Australia. (author)
Jejak Karbon Pengolahan Sampah Di Tps Tlogomas Malang
Sunarto; P. Hadi, Sudharto; Purwanto
2014-01-01
JEJAK KARBON PENGOLAHAN SAMPAH DI tps tlogomas malang Carbon Footprint of Solid Waste Processing At TPS Tlogomas MalangSunarto1, Sudharto P. Hadi2, Purwanto31,2,3Program Doktor Ilmu Lingkungan Universitas DiponegoroAlamat korespondensi : Jl. Imam Bardjo, SH No. 3 Semarang 50241Email: 1) , 2) ste sector is one of human activities that cause global warming. Decomposition of organic waste in landfill produces greenhouse gas emissions in the form...
International Nuclear Information System (INIS)
Harvey, J.R.
1982-01-01
At this international conference, papers were presented on neutron dosimetry applied to the fields of radiotherapy, radiobiology and radiological protection. Papers relating to: quantities and units, radiotherapy, microdosimetry, radiobiology, quality factors, doses in nuclear power stations, instrumentation, sources and fields are discussed. It is concluded that there is a growing awareness of the importance of neutron dosimetry, particularly in the USA. A paper presented by the author, describing the present status of a proposed international filtered team project is given as an Appendix in the form in which it will appear in the Proceedings. (author)
Influence of the curve density relative electron in dosimetry clinic in treatments stereo tactics
International Nuclear Information System (INIS)
Moreno Saiz, C.; Benitez Villegas, E. M.; Casado Villalon, F. J.; Parra Osorio, V.; Bodineau Gil, C.; Garcia Pareja, S.
2013-01-01
The objective of this study is to analyze the difference between clinical dosimetry in the treatments with radiosurgery and stereotactic radiotherapy fractional obtained from the relative Electron density curve (Schneider 1996) tabulated and provided with the scanner's radiation therapy. (Author)
Germanium-doped optical fiber for real-time radiation dosimetry
International Nuclear Information System (INIS)
Mizanur Rahman, A.K.M.; Zubair, H.T.; Begum, Mahfuza; Abdul-Rashid, H.A.; Yusoff, Z.; Ung, N.M.; Mat-Sharif, K.A.; Wan Abdullah, W.S.; Amouzad Mahdiraji, Ghafour; Amin, Y.M.; Maah, M.J.; Bradley, D.A.
2015-01-01
Over the past three decades growing demand for individualized in vivo dosimetry and subsequent dose verification has led to the pursuit of newer, novel and economically feasible materials for dosimeters. These materials are to facilitate features such as real-time sensing and fast readouts. In this paper, purposely composed SiO 2 :Ge optical fiber is presented as a suitable candidate for dosimetry. The optical fiber is meant to take advantage of the RL/OSL technique, providing both online remote monitoring of dose rate, and fast readouts for absorbed dose. A laboratory-assembled OSL reader has been used to acquire the RL/OSL response to LINAC irradiations (6 MV photons). The notable RL characteristics observed include constant level of luminescence for the same dose rate (providing better consistency compared to TLD-500), and linearity of response in the radiotherapy range (1 Gy/min to 6 Gy/min). The OSL curve was found to conform to an exponential decay characteristic (illumination with low LED source). The Ge doping resulted in an effective atomic number, Z eff , of 13.5 (within the bone equivalent range). The SiO 2 :Ge optical fiber sensor, with efficient coupling, can be a viable solution for in vivo dosimetry, besides a broad range of applications. - Highlights: • Purposely fabricated Ge doped silica fiber for real-time dose measurements. • Constant RL response for dose rates in radiotherapy range. • Linearity of RL curve during irradiation using LINAC. • RL response comparison between SiO 2 :Ge optical fiber and TLD-500.
Stability of reference class ionization chambers used for radiotherapy dosimetry: IAEA experience
International Nuclear Information System (INIS)
Czap, L.; Meghzifene, A.; Shortt, K.R.; Andreo, P.
2002-01-01
The IAEA calibrates ionization chambers, used in radiotherapy, for its Member States. The calibrations are either for Secondary Standards Dosimetry Laboratories (SSDLs) or hospitals from countries without a SSDL. For that purpose, the IAEA calibrates mainly reference class instruments that are in turn used to cross-calibrate field class instruments at the hospital. Typically, the IAEA calibrates about 30-40 ionization chambers per year, of which about half are new chambers purchased by the IAEA for its Member States using Technical Cooperation funds. The IAEA database includes the calibration coefficients of 189 reference class ionization chambers of the following types: NE-2561/2611, NE-2571, W-30001/W-30010. The results of the calibrations and recalibrations of the ionization chambers in terms of air kerma and absorbed dose to water are presented and discussed. The ratio of 60 Co calibration coefficients N D,w /N K , labelled C K , was determined for all chambers. The use of C K as a chamber dependent parameter and quality control indicator to check the results of the routine IAEA calibrations is discussed. In the process of its routine calibrations, the IAEA identified a specific problem related to the W- 30001 ionization chambers. The stability of these chambers was found to exceed the 0.5% tolerance limit set by the International IEC standard. Other SSDLs reported similar findings. The manufacturer stopped the production of these W-30001 chambers to investigate the reasons for this anomalous behaviour. After identifying and correcting the problem, the manufacturer produced a new type of ionization chamber. Five of these chambers were tested at the IAEA and found to be within the tolerance limit
Kerns, James R; Followill, David S; Lowenstein, Jessica; Molineu, Andrea; Alvarez, Paola; Taylor, Paige A; Kry, Stephen F
2018-03-14
Reference dosimetry data can provide an independent second check of acquired values when commissioning or validating a treatment planning system (TPS). The Imaging and Radiation Oncology Core at Houston (IROC-Houston) has measured numerous linear accelerators throughout its existence. The results of those measurements are given here, comparing accelerators and the agreement of measurement versus institutional TPS calculations. Data from IROC-Houston on-site reviews from 2000 through 2014 were analyzed for all Elekta accelerators, approximately 50. For each, consistent point dose measurements were conducted for several basic parameters in a water phantom, including percentage depth dose, output factors, small-field output factors, off-axis factors, and wedge factors. The results were compared by accelerator type independently for 6, 10, 15, and 18 MV. Distributions of the measurements for each parameter are given, providing the mean and standard deviation. Each accelerator's measurements were also compared to its corresponding TPS calculation from the institution to determine the level of agreement, as well as determining which dosimetric parameters were most often in error. Accelerators were grouped by head type and reference dosimetric values were compiled. No class of linac had better overall agreement with its TPS, but percentage depth dose and output factors commonly agreed well, while small-field output factors, off-axis factors, and wedge factors often disagreed substantially from their TPS calculations. Reference data has been collected and analyzed for numerous Elekta linacs, which provide an independent way for a physicist to double-check their own measurements to prevent gross treatment errors. In addition, treatment planning parameters more often in error have been highlighted, providing practical caution for physicists commissioning treatment planning systems for Elekta linacs. © 2018 American Association of Physicists in Medicine.
Consorti, R; Fidanzio, A; Brainovich, V; Mangiacotti, F; De Spirito, M; Mirri, M A; Petrucci, A
2017-10-01
EPID-based in vivo dosimetry (IVD) has been implemented for stereotactic body radiotherapy treatments of non-small cell lung cancer to check both isocenter dose and the treatment reproducibility comparing EPID portal images. 15 patients with lung tumors of small dimensions and treated with volumetric modulated arc therapy were enrolled for this initial experience. IVD tests supplied ratios R between in vivo reconstructed and planned isocenter doses. Moreover a γ-like analysis between daily EPID portal images and a reference one, in terms of percentage of points with γ-value smaller than 1, P γlevels of 5% for R ratio, P γlevel, and an average P γ90%. Paradigmatic discrepancies were observed in three patients: a set-up error and a patient morphological change were identified thanks to CBCT image analysis whereas the third discrepancy was not fully justified. This procedure can provide improved patient safety as well as a first step to integrate IVD and CBCT dose recalculation. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
DEFF Research Database (Denmark)
Beierholm, Anders Ravnsborg; Behrens, Claus F.; Sibolt, Patrik
methods was performed by DTU Nutech at six Danish clinics. The first part of the intercompa-rison regarded the consistency of reference dosimetry. Absorbed dose to water under reference conditions was measured using a Farmer ionization chamber, and was found to agree within 1 % with the daily dose checks......-specific correction factors for non-reference fields....
Application of extrusion-cooking for processing of thermoplastic starch (TPS)
Moscicki, Leszek; Mitrus, Marcin; Wojtowicz, Agnieszka; Oniszczuk, Tomasz; Rejak, Andrzej; Janssen, Leon; Mościcki, Leszek
Thermoplastic starch (TPS) as fully biodegradable biopolymer appeared to be one of the most useful and promising materials for packaging purpose. To obtain TPS thermal and mechanical processing should disrupt semi-crystalline starch granules. As the melting temperature of pure starch is
Intercomparison on the usage of computational codes in radiation dosimetry
International Nuclear Information System (INIS)
Ilic, R.; Pesic, M.; Pavlovic, R.
2003-01-01
SRNA-2KG software package was modified for this work to include necessary input and output data and for predicted voxelized geometry and dosimetry. SRNA is a Monte Carlo code developed for applications in proton transport, radiotherapy and dosimetry. Protons within energy range from 100 keV to 250 MeV with predefined spectra are transported in 3D geometry through material zones confined by planes and second order surfaces or in 3D voxelized geometry. The code can treat proton transport in a few hundred different materials including elements from Z=1 to Z=98. Simulation of proton transport is based on the multiple scattering theory of charged particles and on the model for compound nucleus decay
Energy Technology Data Exchange (ETDEWEB)
Le Couteulx, I.; Apretna, D.; Beaugerie, M.F. [Electricite de France (EDF), 75 - Paris (France)] [and others
2003-07-01
Eight articles treat the dosimetry. Two articles evaluate the radiation doses in specific cases, dosimetry of patients in radiodiagnosis, three articles are devoted to detectors (neutrons and x and gamma radiations) and a computer code to build up the dosimetry of an accident due to an external exposure. (N.C.)
Effects of temperature variation on MOSFET dosimetry
International Nuclear Information System (INIS)
Cheung Tsang; Butson, Martin J; Yu, Peter K N
2004-01-01
This note investigates temperature effects on dosimetry using a metal oxide semiconductor field effect transistor (MOSFET) for radiotherapy x-ray treatment. This was performed by analysing the dose response and threshold voltage outputs for MOSFET dosimeters as a function of ambient temperature. Results have shown that the clinical semiconductor dosimetry system (CSDS) MOSFET provides stable dose measurements with temperatures varying from 15 deg. C up to 40 deg. C. Thus standard irradiations performed at room temperature can be directly compared to in vivo dose assessments performed at near body temperature without a temperature correction function. The MOSFET dosimeter threshold voltage varies with temperature and this level is dependent on the dose history of the MOSFET dosimeter. However, the variation can be accounted for in the measurement method. For accurate dosimetry, the detector should be placed for approximately 60 s on a patient to allow thermal equilibrium before measurements are taken with the final reading performed whilst still attached to the patient or conversely left for approximately 120 s after removal from the patient if initial readout was measured at room temperature to allow temperature equilibrium to be established. (note)
Use of a commercial spreadsheet for quality control in radiotherapy
International Nuclear Information System (INIS)
Sales, D.A.G.; Batista, D.V.S.
2001-01-01
This work presents the results obtained from elaboration of a spreadsheet to quality control of physical and clinical dosimetry of a radiotherapy service. It was developed using the resources of a commercial software, in the way to behave an independent verification of manual calculation and therapy planning system calculation to routine procedures of radiotherapy service of Instituto Nacional de Cancer. Its validation was made with the reference of current manual calculation proposed at literature and with the results of therapy planning system for test cases. (author)
Calculation of dosimetry parameters for fast neutron radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Wells, A.H.
1978-05-01
A computer simulation of the interactions of 50 MeV d/sup +/ on Be and 42 MeV p/sup +/ on Be neutron spectra with ICRU muscle tissue and Shonka A-150 tissue equivalent plastic was performed to allow computation of the charged particle spectra that result. Nuclear data were obtained from the Evaluated Nuclear Data File (ENDF) whenever possible and from the Intranuclear Cascade and Evaporation models otherwise. The dosimetry parameters calculated are: the kerma ratio, K/sub A-150//K/sub tissue/; the energy required to form an ion pair, W; and the stopping power ratio, S/sub g//sup W/.
Calculation of dosimetry parameters for fast neutron radiotherapy
International Nuclear Information System (INIS)
Wells, A.H.
1978-05-01
A computer simulation of the interactions of 50 MeV d + on Be and 42 MeV p + on Be neutron spectra with ICRU muscle tissue and Shonka A-150 tissue equivalent plastic was performed to allow computation of the charged particle spectra that result. Nuclear data were obtained from the Evaluated Nuclear Data File (ENDF) whenever possible and from the Intranuclear Cascade and Evaporation models otherwise. The dosimetry parameters calculated are: the kerma ratio, K/sub A-150//K/sub tissue/; the energy required to form an ion pair, W; and the stopping power ratio, S/sub g//sup W/
López-Tarjuelo, Juan; Bouché-Babiloni, Ana; Morillo-Macías, Virginia; de Marco-Blancas, Noelia; Santos-Serra, Agustín; Quirós-Higueras, Juan David; Ferrer-Albiach, Carlos
2014-10-01
In vivo dosimetry is desirable for the verification, recording, and eventual correction of treatment in intraoperative electron radiotherapy (IOERT). Our aim is to share our experience of metal oxide semiconductor field-effect transistors (MOSFETs) and radiochromic films with patients undergoing IOERT using a general-purpose linac. We used MOSFETs inserted into sterile bronchus catheters and radiochromic films that were cut, digitized, and sterilized by means of gas plasma. In all, 59 measurements were taken from 27 patients involving 15 primary tumors (seven breast and eight non-breast tumors) and 12 relapses. Data were subjected to an outliers' analysis and classified according to their compatibility with the relevant doses. Associations were sought regarding the type of detector, breast and non-breast irradiation, and the radiation oncologist's assessment of the difficulty of detector placement. At the same time, 19 measurements were carried out at the tumor bed with both detectors. MOSFET measurements ([Formula: see text] = 93.5 %, sD = 6.5 %) were not significantly shifted from film measurements ([Formula: see text] = 96.0 %, sD = 5.5 %; p = 0.109), and no associations were found (p = 0.526, p = 0.295, and p = 0.501, respectively). As regards measurements performed at the tumor bed with both detectors, MOSFET measurements ([Formula: see text] = 95.0 %, sD = 5.4 % were not significantly shifted from film measurements ([Formula: see text] = 96.4 %, sD = 5.0 %; p = 0.363). In vivo dosimetry can produce satisfactory results at every studied location with a general-purpose linac. Detector choice should depend on user factors, not on the detector performance itself. Surgical team collaboration is crucial to success.
MOSFET dosimetry: temperature effects in-vivo
International Nuclear Information System (INIS)
Yu, P.K.N.; Cheung, T.; Butson, M.J.; Cancer Services, Wollongong, NSW
2004-01-01
Full text: This note investigates temperature effects on dosimetry using a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) for radiotherapy x-ray treatment. This was performed by analysing the dose response and threshold voltage outputs for MOSFET dosimeters as a function of ambient temperature. Results have shown the clinical semiconductor dosimetry system (CSDS) MOSFET provides stable dose measurements with temperatures varying from 15 deg C up to 40 deg C. Thus standard irradiations performed at room temperature can be directly compared to in-vivo dose assessments performed at near body temperature without a temperature correction function. The MOSFET dosimeter threshold voltage varies with temperature and this level is dependant on the dose history of the MOSFET dosimeter. However the variation can be accounted for in the measurement method. For accurate dosimetry the detector should be placed for approximately 60 seconds on a patient to allow thermal equilibrium before measurements are taken with the final reading performed whilst still attached to the patient or conversely left for approximately 120 seconds after removal from the patient if initial readout was measured at room temperature to allow temperature equilibrium to be established. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine
WE-AB-201-03: TPS Commissioning and QA: Incorporating the Entire Planning Process
International Nuclear Information System (INIS)
Mutic, S.
2015-01-01
Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades. Over the same time, continuing innovations have made the TPS even more complex and more central to the clinical process. Medical goals are now expressed in terms of the dose and margins around organs and tissues that are delineated from multiple imaging modalities (CT, MR and PET); and even temporally resolved (i.e., 4D) imaging. This information is passed on to optimization algorithms to establish accelerator movements that are programmed directly for IMRT, VMAT and stereotactic treatments. These advances have made commissioning and QA of the TPS much more challenging. This education session reviews up-to-date experience and guidance on this subject; including the recently published AAPM Medical Physics Practice Guideline (MPPG) #5 “Commissioning and QA of Treatment Planning Dose Calculations: Megavoltage Photon and Electron Beams”. Treatment Planning System Commissioning and QA: Challenges and Opportunities (Greg Salomons) This session will provide some key background and review publications describing prominent incidents relating to TPS commissioning and QA. Traditional approaches have been hardware and feature oriented. They aim to establish a functional configuration and establish specifications for regular testing of features (like dose calculation) to assure stable operation and detect failures. With the advent of more complex systems, more patient-specific testing has also been adopted. A number of actual TPS defects will be presented along with heuristics for identifying similar
WE-AB-201-03: TPS Commissioning and QA: Incorporating the Entire Planning Process
Energy Technology Data Exchange (ETDEWEB)
Mutic, S. [Washington University School of Medicine (United States)
2015-06-15
Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades. Over the same time, continuing innovations have made the TPS even more complex and more central to the clinical process. Medical goals are now expressed in terms of the dose and margins around organs and tissues that are delineated from multiple imaging modalities (CT, MR and PET); and even temporally resolved (i.e., 4D) imaging. This information is passed on to optimization algorithms to establish accelerator movements that are programmed directly for IMRT, VMAT and stereotactic treatments. These advances have made commissioning and QA of the TPS much more challenging. This education session reviews up-to-date experience and guidance on this subject; including the recently published AAPM Medical Physics Practice Guideline (MPPG) #5 “Commissioning and QA of Treatment Planning Dose Calculations: Megavoltage Photon and Electron Beams”. Treatment Planning System Commissioning and QA: Challenges and Opportunities (Greg Salomons) This session will provide some key background and review publications describing prominent incidents relating to TPS commissioning and QA. Traditional approaches have been hardware and feature oriented. They aim to establish a functional configuration and establish specifications for regular testing of features (like dose calculation) to assure stable operation and detect failures. With the advent of more complex systems, more patient-specific testing has also been adopted. A number of actual TPS defects will be presented along with heuristics for identifying similar
In vivo dosimetry with silicon diodes in total body irradiation
International Nuclear Information System (INIS)
Oliveira, F.F.; Amaral, L.L.; Costa, A.M.; Netto, T.G.
2014-01-01
The aim of this work is the characterization and application of silicon diode detectors for in vivo dosimetry in total body irradiation (TBI) treatments. It was evaluated the diode response with temperature, dose rate, gantry angulations and field size. A maximum response variation of 2.2% was obtained for temperature dependence. The response variation for dose rate and angular was within 1.2%. For field size dependence, the detector response increased with field until reach a saturation region, where no more primary radiation beam contributes for dose. The calibration was performed in a TBI setup. Different lateral thicknesses from one patient were simulated and then the calibration factors were determined by means of maximum depth dose readings. Subsequent to calibration, in vivo dosimetry measurements were performed. The response difference between diode readings and the prescribed dose for all treatments was below 4%. This difference is in agreement as recommended by the International Commission on Radiation Units and Measurements (ICRU), which is ±5%. The present work to test the applicability of a silicon diode dosimetry system for performing in vivo dose measurements in TBI techniques presented good results. These measurements demonstrated the value of diode dosimetry as a treatment verification method and its applicability as a part of a quality assurance program in TBI treatments. - Highlights: ► Characterization of a silicon diode dosimetry system. ► Application of the diodes for in vivo dosimetry in total body irradiation treatments. ► Implementation of in vivo dosimetry as a part of a quality assurance program in radiotherapy
Radiotherapy and brachytherapy
International Nuclear Information System (INIS)
2007-02-01
This presentation first defines the radiotherapy and brachytherapy techniques, indicates the used ionizing radiations (electromagnetic and particles), describes the mechanisms and processes of action of ionizing radiations: they can be physical by photon-matter interactions (Compton effect and photoelectric effect) or due to electron-matter interactions (excitation, ionization), physical-chemical by direct or indirect action (DNA damage), cellular (mitotic or apoptotic death), tissue (sane and tumorous tissues and differential effect). It discusses the biological efficiency of these treatments which depends on different parameters: intrinsic radio-sensitivity, time (session fractioning and organisation in time), oxygen, radiation quality, cellular cycle, dose rate, temperature. It presents the different types of radiotherapy: external radiotherapy (general sequence, delineation, dosimetry, protection of critical organs, treatment session, quality control, monitoring consultation) and briefly presents some specific techniques (total body irradiation, total cutaneous electron therapy, pre-operation radiotherapy, radio-surgery, hadron-therapy). It proposes an overview of the main indications for this treatment: brain tumours, upper aero digestive tract tumours, bronchial tumours, oesophagus, stomach and pancreas tumours, breast tumours, cervix cancer, rectum tumour, and so on, and indicates the possible associated treatments. The next part addresses brachytherapy. It presents the principles and comments the differences with radiotherapy. It indicates the used radio-elements (Caesium 137, Iridium 192, Iodine 125), describes the implementation techniques (plastic tubes, use of iodine 125, intracavitary and endo-luminal radiation therapy). It proposes an overview of the different treated tumours (skin, breast, prostates, bronchial, oesophagus, ENT) and indicates possible early and late secondary effects for different organs
High-accuracy dosimetry study for intensity-modulated radiation therapy(IMRT) commissioning
Energy Technology Data Exchange (ETDEWEB)
Jeong, Hae Sun
2010-02-15
Intensity-modulated radiation therapy (IMRT), an advanced modality of high-precision radiotherapy, allows for an increase in dose to the tumor volume without increasing the dose to nearby critical organs. In order to successfully achieve the treatment, intensive dosimetry with accurate dose verification is necessary. A dosimetry for IMRT, however, is a challenging task due to dosimetric ally unfavorable phenomena such as dramatic changes of the dose at the field boundaries, dis-equilibrium of the electrons, non-uniformity between the detector and the phantom materials, and distortion of scanner-read doses. In the present study, therefore, the LEGO-type multi-purpose dosimetry phantom was developed and used for the studies on dose measurements and correction. Phantom materials for muscle, fat, bone, and lung tissue were selected after considering mass density, atomic composition, effective atomic number, and photon interaction coefficients. The phantom also includes dosimeter holders for several different types of detectors including films, which accommodates a construction of different designs of phantoms as necessary. In order to evaluate its performance, the developed phantom was tested by measuring the point dose and the percent depth dose (PDD) for small size fields under several heterogeneous conditions. However, the measurements with the two types of dosimeter did not agree well for the field sizes less than 1 x 1 cm{sup 2} in muscle and bone, and less than 3 x 3 cm{sup 2} in air cavity. Thus, it was recognized that several studies on small fields dosimetry and correction methods for the calculation with a PMCEPT code are needed. The under-estimated values from the ion chamber were corrected with a convolution method employed to eliminate the volume effect of the chamber. As a result, the discrepancies between the EBT film and the ion chamber measurements were significantly decreased, from 14% to 1% (1 x 1 cm{sup 2}), 10% to 1% (0.7 x 0.7 cm{sup 2}), and 42
International Nuclear Information System (INIS)
Tsai, Ping-Fang; Yang, Chi-Cheng; Chuang, Chi-Cheng; Huang, Ting-Yi; Wu, Yi-Ming; Pai, Ping-Ching; Tseng, Chen-Kan; Wu, Tung-Ho; Shen, Yi-Liang; Lin, Shinn-Yn
2015-01-01
Whole brain radiotherapy (WBRT) has been the treatment of choice for patients with brain metastases. However, change/decline of neurocognitive functions (NCFs) resulting from impaired hippocampal neurogenesis might occur after WBRT. It is reported that conformal hippocampal sparing would provide the preservation of NCFs. Our study aims to investigate the hippocampal dosimetry and to demonstrate the correlation between hippocampal dosimetry and neurocognitive outcomes in patients receiving hippocampal sparing during WBRT (HS-WBRT). Forty prospectively recruited cancer patients underwent HS-WBRT for therapeutic or prophylactic purposes. Before receiving HS-WBRT, all participants received a battery of baseline neurocognitive assessment, including memory, executive functions and psychomotor speed. The follow-up neurocognitive assessment at 4 months after HS-WBRT was also performed. For the delivery of HS-WBRT, Volumetric Modulated Arc Therapy (VMAT) with two full arcs and two non-coplanar partial arcs was employed. For each treatment planning, dose volume histograms were generated for left hippocampus, right hippocampus, and the composite hippocampal structure respectively. Biologically equivalent doses in 2-Gy fractions (EQD 2 ) assuming an alpha/beta ratio of 2 Gy were computed. To perform analyses addressing the correlation between hippocampal dosimetry and the change in scores of NCFs, pre- and post-HS-WBRT neurocognitive assessments were available in 24 patients in this study. Scores of NCFs were quite stable before and after HS-WBRT in terms of hippocampus-dependent memory. Regarding verbal memory, the corresponding EQD 2 values of 0, 10, 50, 80 % irradiating the composite hippocampal structure with <12.60 Gy, <8.81, <7.45 Gy and <5.83 Gy respectively were significantly associated with neurocognitive preservation indicated by the immediate recall of Word List Test of Wechsler Memory Scale-III. According to logistic regression analyses, it was noted that
Salas-Ramirez, Maikol; Tran-Gia, Johannes; Kesenheimer, Christian; Weng, Andreas Max; Kosmala, Aleksander; Heidemeier, Anke; Köstler, Herbert; Lassmann, Michael
2018-01-01
Absorbed dose to active bone marrow is a predictor of hematological toxicity in molecular radiotherapy. Due to the complex composition of bone marrow tissue, the necessity to improve the personalized dosimetry has led to the application of non-conventional imaging methods in nuclear medicine. The aim of this study is to apply magnetic resonance imaging (MRI) for quantification of the fat fraction in lumbar vertebrae and to analyze its implications for bone marrow dosimetry. First, a highly accelerated two-point Dixon MRI sequence for fat-water separation was validated in a 3T system against the magnetic resonance spectroscopy (MRS) gold standard. The validation was performed in a fat-water phantom composed of 11 vials with different fat fractions between 0% and 100%, and subsequently repeated in the lumbar vertebrae of three healthy volunteers. Finally, a retrospective study was performed by analyzing the fat fraction in five lumbar vertebrae of 44 patients scanned with the two-point Dixon sequence. The two-point Dixon phantom acquisition showed a good agreement (maximum difference = 2.9%) between the nominal fat fraction and MRS. In the volunteers, a statistical analysis showed a non-significant difference (p = 0.19) between MRI and MRS. In the patients, gender-specific linear fits for female and male data indicated that the age-dependent marrow conversion (red → yellow marrow) is slower in males (0.3% per year) than in females (0.5% per year). Lastly, the fat fraction values showed a considerable variability in patients of similar ages and the same gender. Two-point Dixon MRI enables a non-invasive and spatially resolved quantification of the fat fraction in bone marrow. Our study provides important evidence on the differences in marrow conversion between females and males. In addition, differences were observed in the cellularity values of the International Commission on Radiological Protection (ICRP) reference man (0.7) and the
The role of the IAEA codes of practice in the radiation dosimetry dissemination chain
International Nuclear Information System (INIS)
Andreo, P.
2002-01-01
Full text: More than 30 years ago the International Atomic Energy Agency (IAEA) published on behalf of IAEA, WHO and PAHO its first Code of Practice (CoP) for radiotherapy dosimetry, TRS-110. Aimed at kV x-rays, 60 Co and 137 Cs therapy in developing countries, and based on roentgens and rads, 'old book' readers will still find interesting practical recommendations like QA procedures that include radiographs of the ionization chamber to check that the internal electrode construction has not moved. TRS-110 was also the first and only CoP with the distinction of including the name of the author in its cover, John B Massey, recognizing that IAEA acted solely as a publisher. For the following almost 20 years IAEA dosimetry activities have prioritized the development of a Network of Secondary Standard Dosimetry Laboratories (SSDLs). In addition to disseminating traceable radiation metrology standards, in some countries the SSDLs have played the important role of compensating the lack of qualified medical physicists. The balance between radiation metrology and medical physics has now shifted towards the first area and the IAEA recommends that SSDLs should not perform the duties of medical physicists except in dire situations. During this long period, there were no updates of TRS-110 or a new IAEA CoP published, even if different generations of national dosimetry protocols had emerged. The absence of IAEA recommendations favoured the arbitrary use of such national protocols, mostly issued in UK and USA, with the result that multiple protocols were used within a given country and there were no practical links between medical physics and SSDLs except for detector calibrations. The publication in 1987 of the TRS-277 Code of Practice established a quantum leap with regard to the Agency's role in harmonizing international radiotherapy dosimetry. A new generation of N K -based national protocols had emerged in the early eighties, and the authors of TRS-277 were chosen among
Energy Technology Data Exchange (ETDEWEB)
Nogueira, Luciana B., E-mail: lucibn19@yahoo.com.br, E-mail: jonymarques@uol.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Anatomia e Imagem; Barsanelli, Cristiane; Geraldo, Jony M., E-mail: cbarsanelli@yahoo.com.br [Hospital Luxemburgo, Instituto Mário Penna, Belo Horizonte, MG (Brazil); Aquino, Jean Carlos; Campos, Tarcísio P. Ribeiro, E-mail: jeancarlosaquino@outlook.com, E-mail: tprcampos@yahoo.com.br [Universidade Federal de Minas Gerais (UGMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear
2017-07-01
existence of hot and cold spots in the radiochromic films. It was possible to reproduce the dosimetry prescribed in TPS into the anthropometric and anthropomorphic phantom exposed to a breast conformational teletherapy. The use of the radiochromic films in dosimetry proves to be increasingly useful and becomes routine in radiotherapy services. (author)
International Nuclear Information System (INIS)
Nogueira, Luciana B.; Aquino, Jean Carlos; Campos, Tarcísio P. Ribeiro
2017-01-01
existence of hot and cold spots in the radiochromic films. It was possible to reproduce the dosimetry prescribed in TPS into the anthropometric and anthropomorphic phantom exposed to a breast conformational teletherapy. The use of the radiochromic films in dosimetry proves to be increasingly useful and becomes routine in radiotherapy services. (author)
The need for international standardization in clinical beta dosimetry for brachytherapy
International Nuclear Information System (INIS)
Quast, U.; Boehm, J.; Kaulich, T.W.
2002-01-01
Beta radiation has found increasing interest in radiotherapy. Besides the curative treatment of small and medium-sized intraocular tumors by means of ophthalmic beta radiation plaques, intravascular brachytherapy has proven to successfully overcome the severe problem of restenosis after interventional treatment of arterial stenosis in coronaries and peripheral vessels in many clinical trials with a large number of patients. Prior to initiating procedures applying beta radiation in radiotherapy, however, there is a common need to specify methods for the determination and specification of the absorbed dose to water or tissue and their spatial distributions. The IAEA-TECDOC-1274 Calibration of photon and beta ray sources used in brachytherapy (2002) is a help for photon brachytherapy calibration. But, for beta seed and line sources, IAEA recommends well type ionization chambers as working standards which are far from measuring absorbed dose to water of the radiation clinically used. Although the application of such working standards seems to be more precise, large errors can occur when the medical physicist has to convert the calibration data to absorbed dose to water of the beta radiation emitted. The user must believe that the source is equally activated and that the manufacturer did not change the design and construction of the source encapsulation. With the DGMP Report 16 (2001) Guidelines for medical physical aspects of intravascular brachytherapy a very detailed code of practice is given, especially for the calibration and clinical dosimetry of intravascular beta radiation sources. As there is a global need for standardization in clinical dosimetry for intravascular brachytherapy utilizing beta radiation, the DIN-NAR, the German committee on standardization in radiology, task group dosimetry, has initiated an international adhoc working group for a new ISO work item proposal on the standardization of procedures in clinical dosimetry to guarantee reliable
Energy Technology Data Exchange (ETDEWEB)
Wen, N; Lu, S; Qin, Y; Huang, Y; Zhao, B; Liu, C; Chetty, I [Henry Ford Health System, Detroit, MI (United States)
2016-06-15
Purpose: To evaluate the dosimetric uncertainty associated with Gafchromic (EBT3) films and establish an absolute dosimetry protocol for Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SBRT). Methods: EBT3 films were irradiated at each of seven different dose levels between 1 and 15 Gy with open fields, and standard deviations of dose maps were calculated at each color channel for evaluation. A scanner non-uniform response correction map was built by registering and comparing film doses to the reference diode array-based dose map delivered with the same doses. To determine the temporal dependence of EBT3 films, the average correction factors of different dose levels as a function of time were evaluated up to four days after irradiation. An integrated film dosimetry protocol was developed for dose calibration, calibration curve fitting, dose mapping, and profile/gamma analysis. Patient specific quality assurance (PSQA) was performed for 93 SRS/SBRT treatment plans. Results: The scanner response varied within 1% for the field sizes less than 5 × 5 cm{sup 2}, and up to 5% for the field sizes of 10 × 10 cm{sup 2}. The scanner correction method was able to remove visually evident, irregular detector responses found for larger field sizes. The dose response of the film changed rapidly (∼10%) in the first two hours and plateaued afterwards, ∼3% change between 2 and 24 hours. The mean uncertainties (mean of the standard deviations) were <0.5% over the dose range 1∼15Gy for all color channels for the OD response curves. The percentage of points passing the 3%/1mm gamma criteria based on absolute dose analysis, averaged over all tests, was 95.0 ± 4.2. Conclusion: We have developed an absolute film dose dosimetry protocol using EBT3 films. The overall uncertainty has been established to be approximately 1% for SRS and SBRT PSQA. The work was supported by a Research Scholar Grant, RSG-15-137-01-CCE from the American Cancer Society.
[Development of a Software for Automatically Generated Contours in Eclipse TPS].
Xie, Zhao; Hu, Jinyou; Zou, Lian; Zhang, Weisha; Zou, Yuxin; Luo, Kelin; Liu, Xiangxiang; Yu, Luxin
2015-03-01
The automatic generation of planning targets and auxiliary contours have achieved in Eclipse TPS 11.0. The scripting language autohotkey was used to develop a software for automatically generated contours in Eclipse TPS. This software is named Contour Auto Margin (CAM), which is composed of operational functions of contours, script generated visualization and script file operations. RESULTS Ten cases in different cancers have separately selected, in Eclipse TPS 11.0 scripts generated by the software could not only automatically generate contours but also do contour post-processing. For different cancers, there was no difference between automatically generated contours and manually created contours. The CAM is a user-friendly and powerful software, and can automatically generated contours fast in Eclipse TPS 11.0. With the help of CAM, it greatly save plan preparation time and improve working efficiency of radiation therapy physicists.
Proofs of acceptance of ionization cameras for use in radiotherapy
International Nuclear Information System (INIS)
Davila, Hernan Olaya; Flores, Guillermo
2013-01-01
Shows the main technical tests released in the Secondary Standard Dosimetry Laboratory (SSDL) of one cylindrical ionization chamber and another plane parallel ionization chamber similar to used in radiotherapy services in Colombia to the radiation dose control that is delivered to the patient to the cancer treatment. The previous test of one calibration see in this work are: correction for recombination losses, polarity dependence, stabilization time, total dose dependence, atmospheric communication, stability check, leakage current and physical integrity. Calculates the acceptability values in the SSDL to be account as reference for the dosimetry systems that are carry in calibration process. (author)
Hickling, Susannah; Leger, Pierre; El Naqa, Issam
2016-02-11
Irradiating an object with a megavoltage photon beam generated by a clinical radiotherapy linear accelerator (linac) induces acoustic waves through the photoacoustic effect. The detection and characterization of such acoustic waves has potential applications in radiation therapy dosimetry. The purpose of this work was to gain insight into the properties of such acoustic waves by simulating and experimentally detecting them in a well-defined system consisting of a metal block suspended in a water tank. A novel simulation workflow was developed by combining radiotherapy Monte Carlo and acoustic wave transport simulation techniques. Different set-up parameters such as photon beam energy, metal block depth, metal block width, and metal block material were varied, and the simulated and experimental acoustic waveforms showed the same relative amplitude trends and frequency variations for such setup changes. The simulation platform developed in this work can easily be extended to other irradiation situations, and will be an invaluable tool for developing a radiotherapy dosimetry system based on the detection of the acoustic waves induced following linear accelerator irradiation.
Radiation dosimetry in human bone using electron paramagnetic resonance
International Nuclear Information System (INIS)
Breen, S.L.
1995-01-01
Accurate measurements of dose in bone are required in order to improve the dosimetry of systemic radiotherapy for osseous metastases. Bone is an integrating dosimeter which records the radiation history of the skeleton. During irradiation, electrons become trapped in the crystalline component of bone mineral (hydroxyapatite). The traps are very stable; at room temperature, emptying of the traps occurs with a half-life of many years. The population of trapped unpaired electrons is proportional to the radiation dose administered to the bone and can be measured in excised bone samples using electron paramagnetic resonance (EPR). EPR spectra of synthetic hydroxyapatite, irradiated with Co-60, were obtained at room temperature and at 77 K. At room temperature, the radiation-induced signal, with a g-value of 2.001 ± 0.001 increased linearly with absorbed dose above a lower threshold of 3 Gy, up to doses of 200 Gy. In contrast with pure hydroxyapatite, EPR spectra of excised human bone showed a broad 'native' signal, due to the organic component of bone, which masks the dosimetrically important signal. This native signal is highly variable from sample to sample and precludes the use of EPR as an absolute dosimetry technique. However, after subtraction of the background signal, irradiated human bone showed a linear response with a lower limit of measurement similar to that of synthetic hydroxyapatite. Bone is an in vivo linear dosimeter which can be exploited to develop accurate estimates of the radiation dose delivered during systemic radiotherapy and teletherapy. However, improved sensitivity of the EPR dosimetry technique is necessary before it can be applied reliably in clinical situations. (author)
DEFF Research Database (Denmark)
Buranurak, Siritorn; Andersen, Claus Erik; Beierholm, Anders Ravnsborg
2013-01-01
Fiber-coupled organic plastic scintillators have potential applications in medical dosimetry related to, for example, brachytherapy and external beam radiotherapy with MV photons. As medical dosimetry generally strives for high accuracy, we designed a study to assess if the light yield from...... commonly used scintillating fibers would change with temperature in the clinical range (15–40 °C). The study showed that the light yield in the peak regions of the scintillators studied decreases linearly with increasing temperature. For the blue BCF-12 and the green BCF-60 from Saint-Gobain, France we...
SU-E-T-05: A 2D EPID Transit Dosimetry Model Based On An Empirical Quadratic Formalism
International Nuclear Information System (INIS)
Tan, Y; Metwaly, M; Glegg, M; Baggarley, S; Elliott, A
2014-01-01
Purpose: To describe a 2D electronic portal imaging device (EPID) transit dosimetry model, based on an empirical quadratic formalism, that can predict either EPID or in-phantom dose distribution for comparisons with EPID captured image or treatment planning system (TPS) dose respectively. Methods: A quadratic equation can be used to relate the reduction in intensity of an exit beam to the equivalent path length of the attenuator. The calibration involved deriving coefficients from a set of dose planes measured for homogeneous phantoms with known thicknesses under reference conditions. In this study, calibration dose planes were measured with EPID and ionisation chamber (IC) in water for the same reference beam (6MV, 100mu, 20×20cm 2 ) and set of thicknesses (0–30cm). Since the same calibration conditions were used, the EPID and IC measurements can be related through the quadratic equation. Consequently, EPID transit dose can be predicted from TPS exported dose planes and in-phantom dose can be predicted using EPID distribution captured during treatment as an input. The model was tested with 4 open fields, 6 wedge fields, and 7 IMRT fields on homogeneous and heterogeneous phantoms. Comparisons were done using 2D absolute gamma (3%/3mm) and results were validated against measurements with a commercial 2D array device. Results: The gamma pass rates for comparisons between EPID measured and predicted ranged from 93.6% to 100.0% for all fields and phantoms tested. Results from this study agreed with 2D array measurements to within 3.1%. Meanwhile, comparisons in-phantom between TPS computed and predicted ranged from 91.6% to 100.0%. Validation with 2D array device was not possible for inphantom comparisons. Conclusion: A 2D EPID transit dosimetry model for treatment verification was described and proven to be accurate. The model has the advantage of being generic and allows comparisons at the EPID plane as well as multiple planes in-phantom
Audit on dose delivery by using TLD in Radiotherapy Centers in Malaysia
International Nuclear Information System (INIS)
Md Saion Salikin; Taiman Kadni; Husaini Salleh; Asmaliza Hashim; Hasrul Husham Hussain
2004-01-01
The External Audit Group (EAQ) is established and supported by IAEA. Its main objective is to audit the accuracy of dose delivery to patients in radiotherapy centres or hospitals in developing countries in IAEA member states. At MINT the operation of EAG is managed by Medical Physics Group and supported by Secondary Standard Dosimetry Laboratory (SSDL), MINT. The selected radiotherapy centers are supplied with TLD powder in capsule form, to be irradiated with the required radiation doses, by their physicists. The irradiated TLD is analysed at SSDL. The result of the audit for a few radiotherapy centres in Malaysia, is presented in brief in this paper. (Author)
Results of a national quality audit programme for radiotherapy centers in Iran
International Nuclear Information System (INIS)
Solimanian, A.; Ghafoori, M.
1998-01-01
The SSDL of Iran has established a quality audit programme for radiotherapy centers in the country. Most of the radiotherapy departments are now audited annually by the SSDL dosimetry team. During the site visits, beam characteristics of the teletherapy units are determined or tested. This report presents the results of the on-site output measurements conducted during the period 1985-1996 and demonstrates the role of traceability of absorbed dose to water determinations in hospitals to the SSDL standard. (author)
International Nuclear Information System (INIS)
Izewska, J.; Andreo, P.
1996-01-01
Four national External Audit Groups (EAG) in charge of operating quality audits for radiotherapy dosimetry have been created through a Co-ordinated Research Programme ''Development of a Quality Assurance Programme for Radiation Therapy Dosimetry in Developing Countries'' (E2-40-07). The present status of the development of the measuring systems and measuring procedures for the EAGs has been compared to the methodology established by Quality Audit Networks operating at present in Europe. To harmonize different EAG procedures, a document entitled ''Guidelines to prepare a Quality Manual for External Audit Groups on Dosimetry in Radiotherapy '' has been outlined and a first draft prepared. The ''Guidelines...'' covers quality policy, quality systems and quality structures including process control following the recommendations of ISO 9000 series and ISO/IEC guide No. 25. When completed, this document can be used as a guide on how to prepare the quality manual for national EAGs in developing countries. Due to increased interest in the project three new participants have been admitted. (author)
Cole, Aidan J.; McGarry, Conor K.; Butterworth, Karl T.; McMahon, Stephen J.; Hounsell, Alan R.; Prise, Kevin M.; O'Sullivan, Joe M.
2013-12-01
Respiratory motion introduces complex spatio-temporal variations in the dosimetry of radiotherapy and may contribute towards uncertainties in radiotherapy planning. This study investigates the potential radiobiological implications occurring due to tumour motion in areas of geometric miss in lung cancer radiotherapy. A bespoke phantom and motor-driven platform to replicate respiratory motion and study the consequences on tumour cell survival in vitro was constructed. Human non-small-cell lung cancer cell lines H460 and H1299 were irradiated in modulated radiotherapy configurations in the presence and absence of respiratory motion. Clonogenic survival was calculated for irradiated and shielded regions. Direction of motion, replication of dosimetry by multi-leaf collimator (MLC) manipulation and oscillating lead shielding were investigated to confirm differences in cell survival. Respiratory motion was shown to significantly increase survival for out-of-field regions for H460/H1299 cell lines when compared with static irradiation (p < 0.001). Significantly higher survival was found in the in-field region for the H460 cell line (p < 0.030). Oscillating lead shielding also produced these significant differences. Respiratory motion and oscillatory delivery of radiation dose to human tumour cells has a significant impact on in- and out-of-field survival in the presence of non-uniform irradiation in this in vitro set-up. This may have important radiobiological consequences for modulated radiotherapy in lung cancer.
Radiation dose in radiotherapy from prescription to delivery
Energy Technology Data Exchange (ETDEWEB)
NONE
1996-08-01
Cancer incidence is increasing in developed as well as in developing countries. Cancer may be expected to become a prominent problem and this will result in public pressure for higher priorities on cancer care. In some relatively advanced developing countries radiation therapy is applied in about 50% of all detected cancer cases. Approximately half of these treatments have curative intent. Surgery and radiotherapy applied individually or combined result in the cure of about 40% of all patients. The application of chemotherapy alone has curative effects only on a small percentage of cancer patients. It is encouraging to note that the results achieved by radiation therapy show continuous improvement. This can be traced back to a number of developments: increased knowledge regarding tumour and normal tissue response to radiation, early diagnosis with improved tumour localisation, improved dosimetry and dose planning. The introduction of modern equipment has been crucial in these developments and makes possible a more accurate target delineation, better treatment planning resulting in irradiation of the Planning Target Volume (PTV) with a highly uniform dose and, simultaneously, a reduction in dose to healthy tissues outside the PTV. Experience shows that high quality radiotherapy can only be achieved if its conducted by a skilled team working closely together with good communication between various categories of staff. Therefore, seminars and training courses covering all aspects of radiotherapy and dosimetry are of great importance and should be held regionally or nationally on a regular basis. Refs, figs, tabs.
Radiation dose in radiotherapy from prescription to delivery
International Nuclear Information System (INIS)
1996-08-01
Cancer incidence is increasing in developed as well as in developing countries. Cancer may be expected to become a prominent problem and this will result in public pressure for higher priorities on cancer care. In some relatively advanced developing countries radiation therapy is applied in about 50% of all detected cancer cases. Approximately half of these treatments have curative intent. Surgery and radiotherapy applied individually or combined result in the cure of about 40% of all patients. The application of chemotherapy alone has curative effects only on a small percentage of cancer patients. It is encouraging to note that the results achieved by radiation therapy show continuous improvement. This can be traced back to a number of developments: increased knowledge regarding tumour and normal tissue response to radiation, early diagnosis with improved tumour localisation, improved dosimetry and dose planning. The introduction of modern equipment has been crucial in these developments and makes possible a more accurate target delineation, better treatment planning resulting in irradiation of the Planning Target Volume (PTV) with a highly uniform dose and, simultaneously, a reduction in dose to healthy tissues outside the PTV. Experience shows that high quality radiotherapy can only be achieved if its conducted by a skilled team working closely together with good communication between various categories of staff. Therefore, seminars and training courses covering all aspects of radiotherapy and dosimetry are of great importance and should be held regionally or nationally on a regular basis. Refs, figs, tabs
Thermally stimulated current in PTFE and its application in radiation dosimetry
International Nuclear Information System (INIS)
Ozdemir, S.
1985-01-01
Thermally Stimulated Current (TSC) measurement was made on PTFE (Polytetrafluoro ethylene) in an attempt to develop an integrating radiation dosimeter material and the system. TSC spectra, dose response, energy response, fading and background charge stability characteristics were used as a measure of suitability of various untreated and heat treated PTFE samples for dosimetry applications. For practical TSC dosimetry system, it was discovered that the PTFE samples should be subjected to a specific heat treatment in order to produce samples with better dosimeter characteristics. A treatment at a temperature of 240 C produces a high dose response and low fading characteristics. It was found that the spurious charges due to storage and low sensitivity to irradiation caused the limitation in the measurement of low doses with PTFE samples for personnel protection. However, a TSC Dosimetry system using PTFE is proposed which is suitable for radiation doses in the radiotherapy range from *approx* 50 to *approx* 800 mGy. (author)
Experience in the treatment of IMRT in prostate cancer. Planning, dosimetry and quality control
International Nuclear Information System (INIS)
Gomez Barrado, A.; Garcia Vicente, F.; Fernandez Bedoya, V.; Bermudez Luna, R.; Perez Gonzalez, L.; Torres Escobar, J. J.
2011-01-01
The aim of this study is to review the treatment of prostate cancer at our center. A description of the entire procedure, involving clinical dosimetry, and procedures for verification of treatment, including physical dosimetry and parallel computing system MSure (Standard Imaging, Inc., Middleton) as part of these procedures. This system is based on the model published by trifuente Yang et al. (Yang et al. 2002) for testing treatments regarding the number of monitor unit (MU) given. In addition, this software has a module for the testing of treatments for intensity modulated radiotherapy (IMRT), which will be analyzed in this study.
Characteristics of a commercially available film digitizer and their significance for film dosimetry
International Nuclear Information System (INIS)
Mersseman, B.; De Wagter, C.
1998-01-01
Dosimetric detectors used in high-energy photon radiation dosimetry mainly perform a zero- or one-dimensional measurement. These low-dimensional methods are not always adequate in the context of conformal radiotherapy. Therefore, two-dimensional film dosimetry has attracted attention. We studied a 12-bit CCD-based film digitizer (Vidar VXR-12) with regard to accurate film dosimetry. We investigated the stability, linearity, noise, effects of aberrant light scatter and built-in conversion tables. A digitizing resolution of 75 dpi and a digitizing speed of 20 ms/line result in an optimal signal-to-noise ratio. At optical densities above 2.0, the reading accuracy of the digitizer is limited by noise. The results of various experiments prove both the capabilities and limitations of the digitizer studied. We also propose a method to acquire and process film data using such a digitizer. (author)
Du, Lisha; Qi, Siyan; Ma, Juanjuan; Xing, Libo; Fan, Sheng; Zhang, Songwen; Li, Youmei; Shen, Yawen; Zhang, Dong; Han, Mingyu
2017-11-01
Trehalose (α-D-glucopyranosyl α-D-glucopyranoside) is a non-reducing disaccharide that serves as a carbon source and stress protectant in apple trees. Trehalose-6-phosphate (T6P) is the biosynthetic precursor of trehalose. It functions as a crucial signaling molecule involved in the regulation of floral induction, and is closely related to sucrose. Trehalose-6-phosphate synthase (TPS) family members are pivotal components of the T6P biosynthetic pathway. The present study identified 13 apple TPS family members and characterized their expression patterns in different tissues and in response to exogenous application of sucrose during floral induction. 'Fuji' apple trees were sprayed with sucrose prior to the onset of floral induction. Bud growth, flowering rate, and endogenous sugar levels were then monitored. The expression of genes associated with sucrose metabolism and flowering were also characterized by RT-quantitative PCR. Results revealed that sucrose applications significantly improved flower production and increased bud size and fresh weight, as well as the sucrose content in buds and leaves. Furthermore, the expression of MdTPS1, 2, 4, 10, and 11 was rapidly and significantly up-regulated in response to the sucrose treatments. In addition, the expression levels of flowering-related genes (e.g., SPL genes, FT1, and AP1) also increased in response to the sucrose sprays. In summary, apple TPS family members were identified that may influence the regulation of floral induction and other responses to sucrose. The relationship between sucrose and T6P or TPS during the regulation of floral induction in apple trees is discussed. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
International Nuclear Information System (INIS)
Silva, Cleuza Helena Teixeira; Campos, Tarcisio Passos Ribeiro de
2005-01-01
This paper addresses a computational model of voxels through MCNP5 Code and the experimental development of an anthropometric and anthropomorphic phantom for dosimetry in human male pelvis brachytherapy focusing prostatic tumors. For elaboration of the computational model of the human male pelvis, anatomical section images from the Visible Man Project were applied. Such selected and digital images were associated to a numeric representation, one for each section. Such computational representation of the anatomical sections was transformed into a bi-dimensional mesh of equivalent tissue. The group of bidimensional meshes was concatenated forming the three-dimensional model of voxels to be used by the MCNP5 code. In association to the anatomical information, data from the density and chemical composition of the basic elements, representatives of the organs and involved tissues, were setup in a material database for the MCNP-5. The model will be applied for dosimetric evaluations in situations of irradiation of the human masculine pelvis. Such 3D model of voxel is associated to the code of transport of particles MCNP5, allowing future simulations. It was also developed the construction of human masculine pelvis phantom, based on anthropometric and anthropomorphic dates and in the use of representative equivalent tissues of the skin, fatty, muscular and glandular tissue, as well as the bony structure.This part of work was developed in stages, being built the bony cast first, later the muscular structures and internal organs. They were then jointly mounted and inserted in the skin cast. The representative component of the fatty tissue was incorporate and accomplished the final retouchings in the skin. The final result represents the development of two important essential tools for elaboration of computational and experimental dosimetry. Thus, it is possible its use in calibrations of pre-existent protocols in radiotherapy, as well as for tests of new protocols, besides
Directory of Open Access Journals (Sweden)
Ismid Achmad
2015-08-01
Full Text Available The percentage of solid waste services Denpasar City in 2013 reached 51,8 percent, the limited number and capacity TPS in Denpasar not meet the needs of waste management services in denpasar. The study was to examine the relevant strategies appropriate to the criteria and requirements related to the determination of the location of TPS and the land need. The position of the study is Part Of The City (BWK Central in Denpasar. Analysis of technical aspects will evaluation garbage production in order to know the ideal needs of TPS, the evaluation of TPS placement based on the function of the area and the land needed. Environmental aspect will analyze the environmental risk due to the presence of a TPS. Analysis of public opinion and the behavior of people will use a questionnaire in the collection of data to be analyzed with qualitative methods as a consideration in determining the location and design of a TPS. Institutional aspect will be evaluated about the understanding DKP (Office of Cleaning and Gardening Services employees of the City of Denpasar in the management of garbage, especially in the TPS. As for determining the direction and strategy of the management of garbage SWOT analysis was used.Based on the analysis, the need for the addition of TPS to improve the capacity of TPS, the shape of TPS had comply standard of SNI and environmental safety factor. Additions and changes in the shape of TPS also effect land requirement, the total area of land that must be reserved for TPS is 0,40 hectares. Determining the location of TPS is based on the need of the type of TPS over the spatial pattern. Analysis of public opinion on the determination of the location of TPS, it is obtained that the distance of a TPS with the source must be relatively close and the land use is a vacant land. It is also suggested optimizing the role of the DKP of Denpasar by increasing socialization and community development programs in waste management.
International Nuclear Information System (INIS)
Bojechko, C.; Ford, E. C.
2015-01-01
Purpose: To quantify the ability of electronic portal imaging device (EPID) dosimetry used during treatment (in vivo) in detecting variations that can occur in the course of patient treatment. Methods: Images of transmitted radiation from in vivo EPID measurements were converted to a 2D planar dose at isocenter and compared to the treatment planning dose using a prototype software system. Using the treatment planning system (TPS), four different types of variability were modeled: overall dose scaling, shifting the positions of the multileaf collimator (MLC) leaves, shifting of the patient position, and changes in the patient body contour. The gamma pass rate was calculated for the modified and unmodified plans and used to construct a receiver operator characteristic (ROC) curve to assess the detectability of the different parameter variations. The detectability is given by the area under the ROC curve (AUC). The TPS was also used to calculate the impact of the variations on the target dose–volume histogram. Results: Nine intensity modulation radiation therapy plans were measured for four different anatomical sites consisting of 70 separate fields. Results show that in vivo EPID dosimetry was most sensitive to variations in the machine output, AUC = 0.70 − 0.94, changes in patient body habitus, AUC = 0.67 − 0.88, and systematic shifts in the MLC bank positions, AUC = 0.59 − 0.82. These deviations are expected to have a relatively small clinical impact [planning target volume (PTV) D 99 change <7%]. Larger variations have even higher detectability. Displacements in the patient’s position and random variations in MLC leaf positions were not readily detectable, AUC < 0.64. The D 99 of the PTV changed by up to 57% for the patient position shifts considered here. Conclusions: In vivo EPID dosimetry is able to detect relatively small variations in overall dose, systematic shifts of the MLC’s, and changes in the patient habitus. Shifts in the patient
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Bojechko, C.; Ford, E. C., E-mail: eford@uw.edu [Department of Radiation Oncology, University of Washington, 1959 NE Pacific Street, Seattle, Washington 98195 (United States)
2015-12-15
Purpose: To quantify the ability of electronic portal imaging device (EPID) dosimetry used during treatment (in vivo) in detecting variations that can occur in the course of patient treatment. Methods: Images of transmitted radiation from in vivo EPID measurements were converted to a 2D planar dose at isocenter and compared to the treatment planning dose using a prototype software system. Using the treatment planning system (TPS), four different types of variability were modeled: overall dose scaling, shifting the positions of the multileaf collimator (MLC) leaves, shifting of the patient position, and changes in the patient body contour. The gamma pass rate was calculated for the modified and unmodified plans and used to construct a receiver operator characteristic (ROC) curve to assess the detectability of the different parameter variations. The detectability is given by the area under the ROC curve (AUC). The TPS was also used to calculate the impact of the variations on the target dose–volume histogram. Results: Nine intensity modulation radiation therapy plans were measured for four different anatomical sites consisting of 70 separate fields. Results show that in vivo EPID dosimetry was most sensitive to variations in the machine output, AUC = 0.70 − 0.94, changes in patient body habitus, AUC = 0.67 − 0.88, and systematic shifts in the MLC bank positions, AUC = 0.59 − 0.82. These deviations are expected to have a relatively small clinical impact [planning target volume (PTV) D{sub 99} change <7%]. Larger variations have even higher detectability. Displacements in the patient’s position and random variations in MLC leaf positions were not readily detectable, AUC < 0.64. The D{sub 99} of the PTV changed by up to 57% for the patient position shifts considered here. Conclusions: In vivo EPID dosimetry is able to detect relatively small variations in overall dose, systematic shifts of the MLC’s, and changes in the patient habitus. Shifts in the
International Nuclear Information System (INIS)
Ken, Soléakhéna; Cassol, Emmanuelle; Delannes, Martine; Celsis, Pierre; Cohen-Jonathan, Elizabeth Moyal; Laprie, Anne; Vieillevigne, Laure; Franceries, Xavier; Simon, Luc; Supper, Caroline; Lotterie, Jean-Albert; Filleron, Thomas; Lubrano, Vincent; Berry, Isabelle
2013-01-01
To integrate 3D MR spectroscopy imaging (MRSI) in the treatment planning system (TPS) for glioblastoma dose painting to guide simultaneous integrated boost (SIB) in intensity-modulated radiation therapy (IMRT). For sixteen glioblastoma patients, we have simulated three types of dosimetry plans, one conventional plan of 60-Gy in 3D conformational radiotherapy (3D-CRT), one 60-Gy plan in IMRT and one 72-Gy plan in SIB-IMRT. All sixteen MRSI metabolic maps were integrated into TPS, using normalization with color-space conversion and threshold-based segmentation. The fusion between the metabolic maps and the planning CT scans were assessed. Dosimetry comparisons were performed between the different plans of 60-Gy 3D-CRT, 60-Gy IMRT and 72-Gy SIB-IMRT, the last plan was targeted on MRSI abnormalities and contrast enhancement (CE). Fusion assessment was performed for 160 transformations. It resulted in maximum differences <1.00 mm for translation parameters and ≤1.15° for rotation. Dosimetry plans of 72-Gy SIB-IMRT and 60-Gy IMRT showed a significantly decreased maximum dose to the brainstem (44.00 and 44.30 vs. 57.01 Gy) and decreased high dose-volumes to normal brain (19 and 20 vs. 23% and 7 and 7 vs. 12%) compared to 60-Gy 3D-CRT (p < 0.05). Delivering standard doses to conventional target and higher doses to new target volumes characterized by MRSI and CE is now possible and does not increase dose to organs at risk. MRSI and CE abnormalities are now integrated for glioblastoma SIB-IMRT, concomitant with temozolomide, in an ongoing multi-institutional phase-III clinical trial. Our method of MR spectroscopy maps integration to TPS is robust and reliable; integration to neuronavigation systems with this method could also improve glioblastoma resection or guide biopsies
Reconstructive dosimetry for cutaneous radiation syndrome
Energy Technology Data Exchange (ETDEWEB)
Lima, C.M.A.; Lima, A.R.; Degenhardt, Ä.L.; Da Silva, F.C.A., E-mail: dasilva@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Valverde, N.J. [Fundacao Eletronuclear de Assistencia Medica, Rio de Janeiro, RJ (Brazil)
2015-10-15
According to the International Atomic Energy Agency (IAEA), a relatively significant number of radiological accidents have occurred in recent years mainly because of the practices referred to as potentially high-risk activities, such as radiotherapy, large irradiators and industrial radiography, especially in gammagraphy assays. In some instances, severe injuries have occurred in exposed persons due to high radiation doses. In industrial radiography, 80 cases involving a total of 120 radiation workers, 110 members of the public including 12 deaths have been recorded up to 2014. Radiological accidents in industrial practices in Brazil have mainly resulted in development of cutaneous radiation syndrome (CRS) in hands and fingers. Brazilian data include 5 serious cases related to industrial gammagraphy, affecting 7 radiation workers and 19 members of the public; however, none of them were fatal. Some methods of reconstructive dosimetry have been used to estimate the radiation dose to assist in prescribing medical treatment. The type and development of cutaneous manifestations in the exposed areas of a person is the first achievable gross dose estimation. This review article presents the state-of-the-art reconstructive dosimetry methods enabling estimation of local radiation doses and provides guidelines for medical handling of the exposed individuals. The review also presents the Chilean and Brazilian radiological accident cases to highlight the importance of reconstructive dosimetry. (author)
Absolute measurements methods for proton beam dosimetry
International Nuclear Information System (INIS)
Laitano, R.F.
1998-01-01
A widespread interest in improving proton beam characteristics and related dosimetry became apparent in the recent years, even if the advantages of protons in radiotherapy were pointed out since 1946. The early treatments by proton beams were made for a long time on a small number of patients in very few accelerators sharing their use with nuclear-physics experiments. The first proton accelerator totally dedicated to radiotherapy was established just in 1990 at the Loma Linda Medical Center in the USA. A further reason of the slowly growing use of protons for therapy in the early years, was the lack of adequate means for accurate localization of the treatment volume. The potentialities of protons in imparting a largest part of their energy to very small volumes became exploitable only after the established clinical use of accurate imaging techniques such as based on CT, NMR, PET, etc
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Galvan de la C, O. O.; Rivera M, T. [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria No. 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico); Garcia G, O. A.; Larraga G, J. M., E-mail: olinca@ciencias.unam.mx [Instituto Nacional de Neurologia y Neurocirugia, Laboratorio de Fisica Medica, Insurgentes Sur 3877, Col. La Fama, 14269 Mexico D. F. (Mexico)
2015-10-15
Full text: In-vivo dosimetry is a challenge in radiotherapy due to the measures are carried out in reference conditions outside; there is no balance of charged particle and beam consists of photons own and contamination electrons. Detectors that are useful for such measures should be sufficiently small and thin so they do not disturb the beam and do not alter the dose on target. In this paper the radiochromic films Gafchromic model EBT3 are evaluated as potential detectors for in-vivo dosimetry; measurements were carried out in solid water phantom on the surface, with films of dimensions 3 x 3 cm{sup 2}. Irradiations were performed with a linear accelerator Novalis of 6 MV. Comparison between dose values found with a diode type Sfd detector (IBA dosimetry, Germany) and a diamond detector CVD (PTW-Freiburg) for 2 different sized of field (5 x 5 cm{sup 2} and 10 x 10 cm{sup 2}) on the surface of a water phantom scanning was realized. The total spreading factor (Tsf) measured on surface was of 0.831 ± 4.6%; which is greater 12.9% than Tsf measured at a depth of maximum dose. This difference may be due to the contribution of scattered electrons to the beam exit. The measures must be corroborated with Monte Carlo simulations, which they will be validated on surface by the Abdel-Rahman [et al.] method; this mechanism will determine if the films are useful detectors for in-vivo dosimetry clinically. (Author)
Scattered radiation from dental metallic crowns in head and neck radiotherapy.
Shimozato, T; Igarashi, Y; Itoh, Y; Yamamoto, N; Okudaira, K; Tabushi, K; Obata, Y; Komori, M; Naganawa, S; Ueda, M
2011-09-07
We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.
A clinical implementation of in vivo dosimetry with n-type Isorad semiconductor diodes
Directory of Open Access Journals (Sweden)
Rutonjski Laza M.
2014-01-01
Full Text Available The study was aimed to check the radiotherapy treatment accuracy and definition of action levels during implementation of in vivo dosimetry as a part of quality assurance program. The calibration and correction factors for in vivo entrance dose measurements for six n-type Isorad semiconductor diodes were determined as recommended by the European Society for Radiotherapy and Oncology Booklet No. 5. The patients for in vivo measurements have been divided in groups, according to the treatment site/techique, in order to investigate and detect the groups where the uncertainty was larger or where a systematic error occurred. The tolerance/action levels for all groups were also defined and checked. In this study, the entrance dose measurements were performed for total of 451 treatment fields, and 338 patients over one year period. The mean value and the standard deviation for different groups were: breast +1.0% ± 2.89%(1 SD, brain, and head and neck - +0.74% ± 2.04%(1 SD, and isocentric pelvis and abdomen - +0.1% ± 2.86%(1 SD. All measurements - +0.72% ± 2.64%(1 SD. In our experience, systematic in vivo dosimetry proved to be a very useful tool for quality assurance of patient's plan and treatment, both in detecting systematic errors and for estimating the accuracy of radiotherapy treatment delivery.
Topics in radiation dosimetry radiation dosimetry
1972-01-01
Radiation Dosimetry, Supplement 1: Topics in Radiation Dosimetry covers instruments and techniques in dealing with special dosimetry problems. The book discusses thermoluminescence dosimetry in archeological dating; dosimetric applications of track etching; vacuum chambers of radiation measurement. The text also describes wall-less detectors in microdosimetry; dosimetry of low-energy X-rays; and the theory and general applicability of the gamma-ray theory of track effects to various systems. Dose equivalent determinations in neutron fields by means of moderator techniques; as well as developm
135La as an auger-electron emitter for targeted internal radiotherapy
DEFF Research Database (Denmark)
Fonslet, Jesper; Lee, Boon Quan; Tran, Thuy A.
2018-01-01
Introduction: 135La has favorable nuclear and chemical properties for Auger-based targeted internal radiotherapy. Here we present detailed investigations of the production, emissions, imaging characteristics, and dosimetry related to 135La therapy. Methods and Results: 135La was produced by 16.5 Me....... The generated Auger spectrum was used to recalculate cellular S-factors. Conclusion: 135La was produced with high specific activity, reactivity, radionuclidic purity, and yield. The emission spectrum and the dosimetry are favorable for internal radionuclide therapy. ....... recovered > 98 % of the 135La with an effective molar activity of 70 ±20 GBq/µmol. To better assess cellular and organ dosimetry of this nuclide, we have recalculated the X-ray and Auger emission spectra using a Monte Carlo model accounting for effects of multiple vacancies during the Auger cascade...
Third step report of the National Committee for the follow-up of radiotherapy
International Nuclear Information System (INIS)
Maraninchi, D.; Lacoste, A.C.; Marimbert, J.; Degos, L.; Lartigau, E.; Le Du, D.; Saout, C.; Houssin, D.; Podeur, A.; Renody, N.; Depenweiller, C.; Goinere, R. c
2010-08-01
In a first part, this report presents actions undertaken during the first half of 2010 to support the evolution of radiotherapy professions and care organization (increasing the number of radiotherapists, the possibility of welcoming radio-physics trainees, supporting the profession of technician in dosimetry), to strengthen the vigilance system in radiotherapy, to support the implementation of authorizations and agreement criteria, and to define the R and D prospective in radiotherapy. The second part addresses some actions of the 2009-2013 Cancer Plan (support for practice quality and safety in authorized radiotherapy centres, strengthening of human means in these centres, updating good practice recommendations). The third part addresses actions regarding international cooperation and comparison (international conference, French posture at the European level and in proton therapy)
International Nuclear Information System (INIS)
Mijnheer, Ben
2008-01-01
The lecture encompassed the following topics: Utility of radiographic and radiochromic film dosimetry; Diode and chamber arrays; 3D gel dosimetry; 4D dosimetry; Experimental design for dosimetry; In vivo measurements. and Portal dosimetry. In conclusion, the following pitfalls, potential errors and possible actions are pointed to: (i) Lacking algorithm in the TPS for tongue-and-groove effect. Action: Design and verify a new plan in which the tongue-and-groove effect plays a minor role. Discuss the issue with the TPS manufacturer. (ii) Systematic deviations between TPS calculations and ionisation chamber measurements at the isocentre for plans with many small segments due to uncertainties in the output factor calculation. Action: Rescale the number of MUs. Discuss the issue with the TPS manufacturer. (iii) Large regions with gamma values larger than one during repeated film measurements, while ionisation chamber measurements are correct. Action: Check if the film batch is not expired and if so repeat the measurement with a new batch. (iv) Missing significant errors, e.g., resulting from MLC displacements, due to the limited resolution of the measuring device. Action: Move the device in different directions and repeat the measurement. (v) Missing errors at other parts of the PTV or in OARs by performing only one ionisation chamber measurement or an independent MU calculation at a point. Action: Perform also measurements in a plane for representative clinical cases. (vi) Wrong parameter in the TPS for the definition of leaf position. Action: Understand and verify the definition of leaf position in your TPS. (P.A.)
Energy Technology Data Exchange (ETDEWEB)
Lopez-Tarjuelo, Juan; Marco-Blancas, Noelia de; Santos-Serra, Agustin; Quiros-Higueras, Juan David [Consorcio Hospitalario Provincial de Castellon, Servicio de Radiofisica y Proteccion Radiologica, Castellon de la Plana (Spain); Bouche-Babiloni, Ana; Morillo-Macias, Virginia; Ferrer-Albiach, Carlos [Consorcio Hospitalario Provincial de Castellon, Servicio de Oncologia Radioterapica, Castellon de la Plana (Spain)
2014-11-15
In vivo dosimetry is desirable for the verification, recording, and eventual correction of treatment in intraoperative electron radiotherapy (IOERT). Our aim is to share our experience of metal oxide semiconductor field-effect transistors (MOSFETs) and radiochromic films with patients undergoing IOERT using a general-purpose linac. We used MOSFETs inserted into sterile bronchus catheters and radiochromic films that were cut, digitized, and sterilized by means of gas plasma. In all, 59 measurements were taken from 27 patients involving 15 primary tumors (seven breast and eight non-breast tumors) and 12 relapses. Data were subjected to an outliers' analysis and classified according to their compatibility with the relevant doses. Associations were sought regarding the type of detector, breast and non-breast irradiation, and the radiation oncologist's assessment of the difficulty of detector placement. At the same time, 19 measurements were carried out at the tumor bed with both detectors. MOSFET measurements (D = 93.5 %, s{sub D} = 6.5 %) were not significantly shifted from film measurements (D = 96.0 %, s{sub D} = 5.5 %; p = 0.109), and no associations were found (p = 0.526, p = 0.295, and p = 0.501, respectively). As regards measurements performed at the tumor bed with both detectors, MOSFET measurements (D = 95.0 %, s{sub D} = 5.4 %) were not significantly shifted from film measurements (D = 96.4 %, s{sub D} = 5.0 %; p = 0.363). In vivo dosimetry can produce satisfactory results at every studied location with a general-purpose linac. Detector choice should depend on user factors, not on the detector performance itself. Surgical team collaboration is crucial to success. (orig.) [German] Die In-vivo-Dosimetrie ist wuenschenswert fuer die Ueberpruefung, Registrierung und die eventuelle Korrektur der Behandlungen in der IOERT (''Intraoperative Electron Radiation Therapy''). Unser Ziel ist die Veroeffentlichung unserer Erfahrungen beim
Contribution of the Belgian hospital physicists association to quality assurance in radiotherapy
International Nuclear Information System (INIS)
Hoornaert, M.Th.; Vynckier, S.; Dam, J. van; Bouiller, A.
1997-01-01
In 1987, the Belgian Hospital Physicists Association (BHPA) has started a program in order to uniformize the dosimetry in the Belgian radiotherapy centres. Several initiatives were taken: a) Dosimetry, of photon beams: Endorsement of the Dutch dosimetry, code of practice (NCS) (1), calibration of ionisation chambers in a common laboratory (Laboratory for standard dosimetry, RUG), on site visits where, besides mechanical checks of simulators and radiation units, absorbed dose was measured at different locations in a water phantom. Since 1987, a total of 23 centres were visited involving 18 simulators, 17 cobalt units and 22 linear accelerators with 33 photon beams. The energy of those photon beams ranged from 4 to 25 MeV (2). b) Dosimetry of electron beams: Endorsement of the Dutch dosimetry code of practice (3), calibration of several parallel plate chambers following the recommendations of the IAEA (4) and the NCS, on site visits for local measurements in electron beams. This program started last year. three centres were visited with a total of 23 energies ranging from 4.5 to 21 MeV. c) Elaboration of procedures and common reporting form for daily quality control will be published. (author)
Radiation processing dosimetry - past, present and future
International Nuclear Information System (INIS)
McLaughlin, W.L.
1999-01-01
Since the two United Nations Conferences were held in Geneva in 1955 and 1958 on the Peaceful Uses of Atomic Energy and the concurrent foundation of the International Atomic Energy Agency in 1957, the IAEA has fostered high-dose dosimetry and its applications. This field is represented in industrial radiation processing, agricultural programmes, and therapeutic and preventative medicine. Such dosimetry is needed specifically for pest and quarantine control and in the processing of medical products, pharmaceuticals, blood products, foodstuffs, solid, liquid and gaseous wastes, and a variety of useful commodities, e.g. polymers, composites, natural rubber and elastomers, packaging, electronic, and automotive components, as well as in radiotherapy. Improvements and innovations of dosimetry materials and analytical systems and software continue to be important goals for these applications. Some of the recent advances in high-dose dosimetry include tetrazolium salts and substituted polydiacetylene as radiochromic media, on-line real-time as well as integrating semiconductor and diamond-detector monitors, quantitative label dosimeters, photofluorescent sensors for broad dose range applications, and improved and simplified parametric and computational codes for imaging and simulating 3D radiation dose distributions in model products. The use of certain solid-state devices, e.g. optical quality LiF, at low (down to 4K) and high (up to 500 K) temperatures, is of interest for materials testing. There have also been notable developments in experimental dose mapping procedures, e.g. 2D and 3D dose distribution analyses by flat-bed optical scanners and software applied to radiochromic and photofluorescent images. In addition, less expensive EPR spectrometers and new EPR dosimetry materials and high-resolution semiconductor diode arrays, charge injection devices, and photostimulated storage phosphors have been introduced. (author)
KOMPARASI MODEL PEMBELAJARAN TPS DAN SFE TERHADAP KEMAMPUAN PEMAHAMAN KONSEP
Directory of Open Access Journals (Sweden)
Febri Susanto
2014-03-01
Full Text Available Penelitian ini bertujuan untuk mengetahui apakah pembelajaran model Think Pair Share (TPS dan model Student Facilitator and Explaining (SFE pada siswa kelas X materi jarak pada bangun ruang dapat mencapai ketuntasan belajar dan untuk mengetahui manakah yang lebih efektif antara pembelajaran model Think Pair Share (TPS dan model Student Facilitator and Explaining (SFE. Populasi dalam penelitian ini adalah siswa kelas X SMA N 1 Kota Tegal tahun pelajaran 2012/2013 yang berada dalam sembilan kelas. Sembilan kelas tersebut kemudian dipilih dua kelas secara acak untuk dijadikan sampel dalam penelitian ini yaitu kelas X 2 sebagai kelas eksperimen 1 dan kelas X 1 sebagai kelas eksperimen 2. Uji ketuntasan belajar memberikan hasil yaitu siswa kelas eksperimen 1 dan 2 telah mencapai ketuntasan belajar. Uji kesamaan dua proporsi memberikan hasil yakni proporsi ketuntasan belajar pada aspek pemahaman konsep siswa kelas eksperimen 1 sama baiknya dibanding proporsi ketuntasan belajar pada aspek pemahaman konsep siswa kelas eksperimen 2. Hasil Penelitian menunjukkan pembelajaran model TPS dan SFE pada materi jarak pada bangun ruang telah mencapai ketuntasan belajar dan model pembelajaran TPS sama efektifnya dengan pembelajaran model SFE.
International Nuclear Information System (INIS)
Fontbonne, J.M.
2002-12-01
This work describes the design and evaluation of the performances of a scintillation dosimeter developed for the dosimetry of radiation beams used in radiotherapy. The dosimeter consists in a small plastic scintillator producing light which is guided by means of a plastic optical fiber towards photodetectors. In addition to scintillation, high energy ionizing radiations produce Cerenkov light both in the scintillator and the optical fiber. Based on a wavelength analysis, we have developed a deconvolution technique to measure the scintillation light in the presence of Cerenkov light. We stress the advantages that are anticipated from plastic scintillator, in particular concerning tissue or water equivalence (mass stopping power, mass attenuation or mass energy absorption coefficients). We show that detectors based on this material have better characteristics than conventional dosimeters such as ionisation chambers or silicon detectors. The deconvolution technique is exposed, as well as the calibration procedure using an ionisation chamber. We have studied the uncertainty of our dosimeter. The electronics noise, the fiber transmission, the deconvolution technique and the calibration errors give an overall combined experimental uncertainty of about 0,5%. The absolute response of the dosimeter is studied by means of depth dose measurements. We show that absolute uncertainty with photons or electrons beams with energies ranging from 4 MeV to 25 MeV is less than ± 1 %. Last, at variance with other devices, our scintillation dosimeter does not need dose correction with depth. (author)
Clinical research of teeth damage from radiotherapy
International Nuclear Information System (INIS)
Li Erzhou; Yan Maosheng; Chen Wei; Li Qing
2003-01-01
Objective: To analyze various factors inducing teeth damage from radiotherapy and the preventive and treatment methods. Methods: One hundred cases of patients treated by radiotherapy were divided into two groups. In group one there were 60 cases whose teeth were irradiated during treatment; in group two there were 40 cases whose teeth were not irradiated during treatment. Results: The caries incidence was 60% for group one and 15% for group two (P<0.01). By auto-control in 15 patients, the caries incidence on the sick side was obviously higher than that of the healthy side. Hundred percent caries incidence was found in 6 cases who received a dosage of 70 Gy. Conclusion: The authors believe that radiation damage to the teeth is associated with the following factors: 1. The dosage and location of irradiation are closely related to caries incidence; 2. The active dentinoblasts are very sensitive to radiation; 3. Damage to the salivary glands from radiotherapy can result in reduction of salvia and pH value, leading to a high growth rate of Streptococcus mutans. Following preventive measures could be considered in future cases: to apply a caries prevention coating or protective dental crown and TPS, to adjust the dose and time of irradiation, to select conformal radiotherapy technique. The key points for protecting the teeth and salivary gland from caries and damage are protection of the proliferation ability of pulp cells, anti-inflammation, promotion of microcirculation, and strengthening body resistance
External quality audits in radiotherapy in Poland
International Nuclear Information System (INIS)
Bulski, W.; Rostkowska, J.; Kania, M.; Gwiazdowska, B.
2002-01-01
The Secondary Standard Dosimetry Laboratory (SSDL) of the Medical Physics Department of the Centre of Oncology in Warsaw is a continuation of the Radiation Measurements Laboratory created in 1937, following the suggestions of Marie Curie, the founder of the Institute. The present SSDL is a member of the WHO/IAEA international network and is periodically audited by the International Atomic Energy Agency. The SSDL is in charge of the calibration of all radiotherapy dosimeters in Poland, and it also co-ordinates all activities carried out in radiotherapy quality assurance programmes nation-wide. The External Audit Group (EAG) was set-up according to the recommendations of the IAEA, as a part of the SSDL. The EAG is in charge of the management of the project and organization of the TLD measurements. The SSDL takes the responsibilities of the metrological aspects of the programme. The results of the efforts, aimed at the development of a quality audit programme and methodology in radiotherapy, are presented
Dose profile analysis of small fields in intensity modulated radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Medel B, E. [IMSS, Centro Medico Nacional Manuel Avila Camacho, Calle 2 Nte. 2004, Barrio de San Francisco, 72090 Puebla, Pue. (Mexico); Tejeda M, G.; Romero S, K., E-mail: romsakaren@gmail.com [Benemerita Universidad Autonoma de Puebla, Facultad de Ciencias Fisico Matematicas, Av. San Claudio y 18 Sur, Ciudad Universitaria, 72570 Puebla, Pue.(Mexico)
2015-10-15
Full text: Small field dosimetry is getting a very important worldwide task nowadays. The use of fields of few centimeters is more common with the introduction of sophisticated techniques of radiation therapy, as Intensity Modulated Radiotherapy (IMRT). In our country the implementation of such techniques is just getting started and whit it the need of baseline data acquisition. The dosimetry under small field conditions represents a challenge for the physicists community. In this work, a dose profile analysis was done, using various types of dosimeters for further comparisons. This analysis includes the study of quality parameters as flatness, symmetry, penumbra, and other in-axis measurements. (Author)
On the calibration of radiotherapy dosemeters in Australia
International Nuclear Information System (INIS)
Huntley, R.; Kotler, L.; Webb, D.
2000-01-01
Full text: Dosemeters for external beam radiotherapy are calibrated in Australia by ARPANSA, against the national primary standards of exposure and absorbed dose. The primary standards are free air chambers for exposure at low and medium energy X-rays, a graphite cavity chamber for exposure at 60 Co, and a graphite calorimeter for absorbed dose at 60 Co and high energy (MV) X -rays. Radiotherapy dosemeters are calibrated against these standards using a well documented formalism to provide calibration factors suitable for use with dosimetry protocols. A dosemeter usually comprises an ionization chamber connected to an independent electrometer. These are calibrated separately if possible. A combined calibration factor is reported together with the electrometer calibration factor (sensitivity). The dosimetry protocol used in radiotherapy centres in Australia and New Zealand is currently the simplified version of the IAEA TRS277 protocol, published by the New Zealand NRL and recommended by the ACPSEM. This protocol requires the use of an exposure or air kerma calibration factor at 60 Co (Nx or Nk) to evaluate the absorbed dose to air calibration factor N D . The chamber is then placed in a water phantom with its centre displaced from the reference point by p eff . ARPANSA can also supply calibration factors in absorbed dose to water (N D,w ), as required as input to the new IAEA CoP. If an absorbed dose to water calibration factor is used by the radiotherapy centre, the chamber should be placed with its centre at the reference point in the water phantom. ARPANSA has for some years coordinated the participation of Australian radiotherapy centres in the IAEA TLD Quality Audit service. Note that this service does not represent a calibration and should not be referred to as such. The only calibration is that provided by ARPANSA for a reference dosemeter at each radiotherapy centre. As soon as the ANSTO SSDL is operational, calibrations of reference dosemeters will also be
International Nuclear Information System (INIS)
Rosenblatt, E.; Zubizarreta, E.; Djeutie, A.; Meghzifene, A.; Mohamedou, M.M.
2017-01-01
Mauritania, a country of 3.4 million people, did not have any radiotherapy facility until 2009. As is usually the case in countries without radiotherapy services, cancer patients with a need for this treatment travelled to neighbouring countries (Morocco or Tunisia) or to Europe to receive it, or switched to alternative forms of care. Cancer is a rising cause of death in Mauritania. According to WHO estimates, about 2200 people died of cancer in 2011, of whom 1400 were aged below 70 years of age. The number of patients sent abroad for treatment by the National Health Insurance Fund rose to 500 patients in 2007, causing a significant drain on the State budget. Cancer was the main cause of health related travel abroad. The average cost of such travel was two million ouguiya per patient (US $8000). Through a technical cooperation project initiated in 2009 between the Mauritanian Government and the IAEA, the latter assisted the country with the establishment and operation of its first radiotherapy facility. The National Oncology Centre, including a radiotherapy department, was built in Nouakchott in 2010 and began operation in early 2011 with a limited staff, all hired from abroad. Its equipment includes a modern medical linac with a multileaf collimator and portal imaging, a CT simulator, a 3-D CRT TPS and a remote afterloading HDR brachytherapy system. The centre was planned with an additional bunker, where a second accelerator can be installed in the future. Except for the training of the Department Head, the entire professional team has been trained through the IAEA’s technical cooperation fellowship programme. The centre treated a total of 250 patients in 2012 and treated 176 in the first half of 2013. Most patients undergo simulation and computerized radiotherapy treatment planning. The centre ensures the sustainability of the equipment through full maintenance contracts for the major radiation equipment and source replacements for the HDR brachytherapy unit.
Standards for radiation protection and diagnostic radiology at the IAEA Dosimetry Laboratory
International Nuclear Information System (INIS)
Pernicka, F.; Andreo, P.; Meghzifene, A.; Czap, L.; Girzikowsky, R.
1999-01-01
International standardization in dosimetry is essential for the successful exploitation of radiation technology. The IAEA dosimetry programme is focused into services provided to Member States through the IAEA/WHO Network of Secondary Standard Dosimetry Laboratories (SSDLs), to radiotherapy centres and radiation processing facilities. Radiation protection quantities defined by ICRU and ICRP are used to relate the risk due to exposure to ionizing radiation to a single quantity, irrespective of the type of radiation, which takes into account the human body as a receptor. Two types of quantities, limiting and operational, can be related to basic physical quantities which are defined without need for considering specific aspects of radiation protection, e.g. air kerma for photons and fluence for neutrons. The use of a dosimeter for measurements in radiation protection requires a calibration in terms of a physical quantity together with a conversion from physical into protection quantities by means of a factor or a coefficient
International Nuclear Information System (INIS)
Derreumaux, S.; Huet, C.; Robbes, I.; Trompier, F.; Boisserie, G.; Brunet, G.; Buchheit, I.; Sarrazin, T.; Chea, M.
2008-01-01
After the radiotherapy accident in Toulouse, the French authority of nuclear safety and the French agency of health products safety have asked the IR.S.N. to establish, together with experts from the French society of medical physics and the French society of radiotherapy and oncology, a national protocol on dose calibration for the very small beams used in stereotactic radiotherapy. The research and reflexions of the working group 'GT minifaisceaux ' set up by the I.R.S.N. are presented in this final report. A review of the international literature has been performed. A national survey has been done to know the present practices in the dosimetry of small fields. A campaign of measurements of the data needed to characterize the small beams for the different stereotactic systems has started, using different types of detectors acquired by the I.R.S.N.. In this report are presented a deep synthesis on the problems related to the dosimetry of small fields, the results of the national survey, the first results of the campaign of measurements and the recommendations of the GT. (authors)
International Nuclear Information System (INIS)
2011-08-01
This report analyses the status of actions undertaken from July 2010 to July 2011 and regarding the support to the evolution of radiotherapy professions and care organization (increasing the number of radiotherapists, the possibility of welcoming radio-physics trainees, supporting the profession of technician in dosimetry), the vigilance system in radiotherapy, the implementation of authorizations and agreement criteria, and the 2009-2013 'cancer' plan for a better safety and quality of radiotherapy conditions
Development of a transfer instrument for neutron dosimetry intercomparison
International Nuclear Information System (INIS)
Greene, D.; Miles, J.
1974-01-01
Comparisons are reported for fast neutron dosemeters which were designed to be transportable so as to enable intercomparisons between institutions using neutrons for radiotherapy or radiobiology. The systems considered are : 1) the ferrous sulphate dosemeter, 2) the lithium fluoride thermoluminescent dosemeter, 3) ionization chambers with various walls and gases. Work on photographic film dosimetry indicated that the system was not suitable and was not pursued. The sources used were 60 Co, the cyclotron at Hammersmith Hospital in London and 252 Cf
Dosimetric quality control in radiotherapy using TLD methodology
International Nuclear Information System (INIS)
Saravi, M.C.; Kessler, C.; Alvarez, P.E.; Feld, D.B.
2002-01-01
In the frame of the IAEA Co-ordinated Research Project 'Development of a Quality Assurance Program for Radiation Therapy Dosimetry in Developing Countries' a Dosimetric Quality Control Group was set up in Argentina in 1996, to develop a program in order to improve radiotherapy in the country. Nowadays, this Group, briefly called External Audit Group (EAG), is composed by the national Secondary Standard Dosimetry Laboratory (SSDL), which has the responsibility for dose determinations, traceability to international dosimetry chain and TLD measurements, and two Medical Physicists from CNEA who are working at the Oncology Hospital 'Marie Curie' in Buenos Aires. The present paper reports the activities performed by the EAG with external high energy photon beams in reference conditions and the results of two pilot studies on cobalt 60 beams in non-reference conditions. The first step of the program was to update the existing data base about the radiotherapy centres operating in the country. A form was sent to each of them in order to obtain basic information about their staff, number and type of treatment machines, brachytherapy sources, measuring devices, beam calibration, treatment planning system, simulator and other relevant data. 90 radiotherapy centres were registered in the EAG data base. Forms were completed by 75/90 centres. There are nowadays 69 cobalt 60 units and 42 LINACs operating in the country (18/42 LINACs producing high energy X ray and electron beams). EAG deals with measurements performed with mailed TLD irradiated at radiotherapy centres. Internal quality control on our TLD system is made during each audit by means of reference capsules irradiated by IAEA; external controls consist in blind tests performed by IAEA once a year. The correction factor, K en , determined at our SSDL for high energy X-rays was checked with the collaboration of IAEA and Prague National Radiation Protection Institute (PNRPI) by means of a blind test. Results for 4 MV, 6 MV
The IAEA quality audits in radiotherapy
International Nuclear Information System (INIS)
Izewska, J.; Vatnitsky, S.T.; Salminen, E.
2009-01-01
The quality audits are considered as an essential component of management systems of quality in radiotherapy. this method consists in checking that the quality of activities of a radiotherapy center is consistent with the rules of correct practices. The principal objective of the quality audit is to contribute to an improvement of the quality. IAEA developed a method of complete audit in the framework of the quality assurance team in radio-oncology (Q.U.A.T.R.O.). The Q.U.A.T.R.O. missions consist in an evaluation of the radiotherapy infrastructure, including the aspects related to the patient and equipment and where appropriate, an assessment of the safety of using ionizing radiation and radiation protection of the patients. The assessment also covers the staffing and training programs for radiation oncologists and medical radiation physicists. These missions allow to identify the insufficiencies in term of infrastructures, material, human resources and procedures and to enlighten the points to improve. Their results proved useful to improve the dosimetry practices at the worldwide level. (N.C.)
Zeng, Xiangling; Liu, Cai; Zheng, Riru; Cai, Xuan; Luo, Jing; Zou, Jingjing; Wang, Caiyun
2016-01-01
Osmanthus fragrans is an ornamental and economically important plant known for its magnificent aroma, and the most important aroma-active compounds in flowers are monoterpenes, mainly β-ocimene, linalool and linalool derivatives. To understand the molecular mechanism of monoterpene production, we analyzed the emission and accumulation patterns of these compounds and the transcript levels of the genes involved in their biosynthesis in two O. fragrans cultivars during flowering stages. The results showed that both emission and accumulation of monoterpenes varied with flower development and glycosylation had an important impact on floral linalool emission during this process. Gene expression demonstrated that the transcript levels of terpene synthase (TPS) genes probably played a key role in monoterpene production, compared to the genes in the MEP pathway. Phylogenetic analysis showed that OfTPS1 and OfTPS2 belonged to a TPS-g subfamily, and OfTPS3 and OfTPS4 clustered into a TPS-b subfamily. Their transient and stable expression in tobacco leaves suggested that OfTPS1 and OfTPS2 exclusively produced β-linalool, and trans-β-ocimene was the sole product from OfTPS3, while OfTPS4, a predictive sesquiterpene synthase, produced α-farnesene. These results indicate that OfTPS1, OfTPS2, and OfTPS3 could account for the major floral monoterpenes, linalool and trans-β-ocimene, produced in O. fragrans flowers. PMID:26793212
Directory of Open Access Journals (Sweden)
Xaingling eZeng
2016-01-01
Full Text Available Osmanthus fragrans is an ornamental and economically important plant known for its magnificent aroma, and the most important aroma-active compounds in flowers are monoterpenes, mainly β-ocimene, linalool and linalool derivatives. To understand the molecular mechanism of monoterpene production, we analyzed the emission and accumulation patterns of these compounds and the transcript levels of the genes involved in their biosynthesis in two O. fragrans cultivars during flowering stages. The results showed that both emission and accumulation of monoterpenes varied with flower development and glycosylation had an important impact on floral linalool emission during this process. Gene expression demonstrated that the transcript levels of terpene synthase (TPS genes probably played a key role in monoterpene production, compared to the genes in the MEP pathway. Phylogenetic analysis showed that OfTPS1 and OfTPS2 belonged to a TPS-g subfamily, and OfTPS3 and OfTPS4 clustered into a TPS-b subfamily. Their transient and stable expression in tobacco leaves suggested that OfTPS1 and OfTPS2 exclusively produced β-linalool, and trans-β-ocimene was the sole product from OfTPS3, while OfTPS4, a predictive sesquiterpene synthase, produced α-farnesene. These results indicate that OfTPS1, OfTPS2 and OfTPS3 could account for the major floral monoterpenes, linalool and trans-β-ocimene, produced in O. fragrans flowers.
A quality assurance program for radiotherapy centers in the Republic of Korea
International Nuclear Information System (INIS)
Kim, G.Y.; Lee, H.K.; Park, K.J.; Oh, H.J.
2002-01-01
Recognizing the importance of quality assurance in radiotherapy and the need to make access to radiation standards traceable to the international measurement system to every radiotherapy center, the KFDA, as a national secondary standard dosimetry laboratory (SSDL), has started a quality assurance program from 1999. This program was initiated by tele-survey to all radiotherapy centers regarding general information about their radiotherapists, medical physicists, type of equipment, dosimeters, etc. This provided the KFDA with a data file and led to links between the KFDA and the clinics. In 1999 a national quality assurance program for ensuring dosimetry accuracy has been performed by on-site dosimetry for 4 60 Co γ ray, 47 high-energy photon beams used in 43 centers. During the audits, the procedure followed by the KFDA was to measure the outputs of the LINAC(6 MV) and Co-60 teletherapy units in terms of absorbed dose to water for fixed dose (2 Gy) in water phantom (only one phantom used in this on-site visit). For all the case, the measurements are carried out in a water phantom according to the IAEA recommended code of practice. The distributions of deviations in total audit are given. The results showed deviations varying between -7.11% and 8.38%. KFDA follow up the large deviated radiotherapy centers. The traceability to SSDL is a major factor of deviation between KFDA measurement dose and clinics quoted dose. The correction for air density (temperature and pressure) is a factor that sometimes introduces errors. Most of the clinics do not calibrate their own barometers and sometimes rely on the air pressure that is quoted during measurements by local metrological offices. In one case, the barometer and thermometer of the clinic were deviating from KFDA instruments by about 10 mmHg and 2, respectively even if the temperature was measured in air. In one case, about 4% of output variation with gantry head angle (horizontal vs. vertical). In the past two years the
International Nuclear Information System (INIS)
Descamps, C.; Tromson, D.; Mer, C.; Nesladek, M.; Bergonzo, P.
2006-01-01
In radiotherapy field, the major usage of dosimeters is in the measurement of the dose received by the patient during radiotherapy (in-vivo measurements) and in beam calibration and uniformity checks. Diamond exhibits several interesting characteristics that make it a good candidate for radiation detection. It is indeed soft-tissue equivalent (Z=6 compared to Z=7.42 for human tissue), mechanically robust and relatively insensitive to radiation damage, chemically stable and non toxic. Moreover, the recent availability of synthetic samples, grown under controlled conditions using the chemical vapour deposition (C.V.D.) technique, allowed decreasing the high cost and the long delivery time of diamond devices. Diamond can be use for off-line dosimetry as thermoluminescent dosimeters or for on-line dosimetry as ionisation chamber [2,3]. These both applications are reported here. For this study, samples were grown in the laboratory and devices were then tested under X-ray irradiations and in clinical environment under medical cobalt source. The work described in this paper was performed in the framework of the European Integrated Project M.A.E.S.T.R.O., Methods and Advanced Equipment for Simulation and Treatment in Radio-Oncology, (6. FP) which is granted by the European Commission.The first results of this study clearly show that C.V.D. diamond detectors are suitable for dosimetry in radiotherapy applications. Moreover, for both T.L. dosimeters and ionisation chambers applications, and even though the sensitivity is subsequently reduced, nitrogen incorporation in films seems to significantly improve the dosimetric characteristics of the devices. Therefore, the optimisation of the material quality appears as a very important issue in order to increase the dosimetric characteristics of devices and more particularly, for use as thermoluminescent dosimeters, other impurities (Nickel, Phosphorus) will be tested. For ionisation chamber applications, experiments with
Energy Technology Data Exchange (ETDEWEB)
Cao, Y; Li, R; Chi, Z [The Fourth Hospital of Hebei Medical University, Shijiazhuang, Hebei, CN, Shijiazhuang, Hebei (China)
2014-06-01
Purpose: To compare the performances of four commercial treatment planning systems (TPS) used for the intensity-modulated radiotherapy (IMRT). Methods: Ten patients of nasopharyngeal (4 cases), esophageal (3 cases) and cervical (3 cases) cancer were randomly selected from a 3-month IMRT plan pool at one radiotherapy center. For each patient, four IMRT plans were newly generated by using four commercial TPS (Corvus, Monaco, Pinnacle and Xio), and then verified with Matrixx (two-dimensional array/IBA Company) on Varian23EX accelerator. A pass rate (PR) calculated from the Gamma index by OminiPro IMRT 1.5 software was evaluated at four plan verification standards (1%/1mm, 2%/2mm, 3%/3mm, 4%/4mm and 5%/5mm) for each treatment plan. Overall and multiple pairwise comparisons of PRs were statistically conducted by analysis of covariance (ANOVA) F and LSD tests among four TPSs. Results: Overall significant (p>0.05) differences of PRs were found among four TPSs with F test values of 3.8 (p=0.02), 21.1(>0.01), 14.0 (>0.01), 8.3(>0.01) at standards of 1%/1mm to 4%/4mm respectively, except at 5%/5mm standard with 2.6 (p=0.06). All means (standard deviation) of PRs at 3%/3mm of 94.3 ± 3.3 (Corvus), 98.8 ± 0.8 (Monaco), 97.5± 1.7 (Pinnacle), 98.4 ± 1.0 (Xio) were above 90% and met clinical requirement. Multiple pairwise comparisons had not demonstrated a consistent low or high pattern on either TPS. Conclusion: Matrixx dose verification results show that the validation pass rates of Monaco and Xio plans are relatively higher than those of the other two; Pinnacle plan shows slight higher pass rate than Corvus plan; lowest pass rate was achieved by the Corvus plan among these four kinds of TPS.
A multi-centre dosimetry audit on advanced radiotherapy in lung as part of the Isotoxic IMRT study
Directory of Open Access Journals (Sweden)
Yat Tsang
2017-10-01
Conclusion: This multi-centre dosimetry audit of complex IMRT/VMAT delivery provides confidence in the accuracy of modern planning and delivery systems in inhomogeneous tissues. The findings from this study can be used as a reference for future dosimetry audits.
Directory of Open Access Journals (Sweden)
Zahra Falahatpour
2010-09-01
Full Text Available Introduction: Breast conserving radiotherapy is one of the most common procedures performed in any radiation oncology department. A tangential parallel-opposed pair is usually used for this purpose. This technique is performed using 2D or 3D treatment planning systems. The aim of this study was to compare 2D treatment planning with 3D treatment planning in tangential irradiation in breast conserving radiotherapy. In this comparison, homogeneity of isodoses in the breast volume and lung dose were considered. Material and Methods: Twenty patients with breast cancer treated with conservative surgery were included in this study. The patients were CT scanned. Two-dimensional treatment planning with the Alfard 2D TPS was performed for each patient using a single central CT slice. The data used on the Alfard 2D TPS was imported into the Eclipse 3D TPS, on which 3D treatment planning was performed. Cobalt-60 beams were used in all plans. Results: Comparing 2D and 3D treatment planning, homogeneity of isodoses was improved in 3D treatment planning (p30Gy was increased in 3D treatment planning (p< 0.01. Discussion and Conclusion: 3D treatment planning is a more suitable option for patients with breast cancer treated with conservative surgery because of improved dose homogeneity in 3D treatment planning. The results of the treatment can be improved with reduced recurrence probability and skin problems.
PENINGKATAN MOTIVASI DAN HASIL BELAJAR MELALUI THINK PAIR SHARE (TPS DI SEKOLAH DASAR
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Erika Puspitasari
2016-07-01
Full Text Available This study aims to improve motivation and learning outcomes through the Think Pair Share (TPS. Subjects were students of class IV SDN Margomulyo 02 Blitar. Type of research is classroom action research. Collecting data using questionnaires and test sheets. Data were analyzed using descriptive analysis. Results penilitian namely (1 there is an increased motivation to learn through TPS with an average score of the first cycle to the second cycle of 18%. (2 there is an increase learning outcomes through TPS with an average score of the first cycle to the second cycle by 14%. Advice given more time guiding students through group discussion so that students can actively work together in groups. Penelitian ini bertujuan untuk meningkatan motivasi dan hasil belajar melalui Think Pair Share (TPS. Subyek penelitian adalah siswa kelas IV SDN Margomulyo 02 Blitar. Jenis penelitiannya adalah penelitian tindakan kelas. Pengumpulan data menggunakan lembar angket dan tes. Teknik analisis data menggunakan analisis deskriptif. Hasil penilitian yaitu (1 terdapat peningkatan motivasi belajar melalui TPS dengan skor rata-rata siklus I ke siklus II sebesar 18%. (2 terdapat peningkatan hasil belajar melalui TPS dengan skor rata-rata siklus I ke siklus II sebesar 14%. Saran yang diberikan lebih membimbing siswa saat diskusi kelompok agar siswa secara aktif dapat bekerja sama dalam kelompok.
Patient Radiation Protection in Radiotherapy
International Nuclear Information System (INIS)
Hegazy, M.
2010-01-01
The Role of Radiotherapy is treatment modalities for cancer which is generally assumed that 50 to 60% of cancer patients will benefit from radiotherapy. It constitutes a peaceful application of ionizing radiation and an essential part of cancer management. The two aims of radiation protection Prevention is of deterministic effect and Reduction of the probability of stochastic effects. The Shielding fundamentals is to limit radiation exposure of staff, patients, visitors and the public to acceptable levels it also optimize protection of patients, staff and the public. Diagnosis is important for target design and the dose required for cure or palliation while Simulator is often used twice in the radiotherapy process where Patient data acquisition - target localization, contours, outlines and Verification. The Prescription is the responsibility of individual clinicians, depending on the patient’s condition, equipment available, experience and training. An ultimate check of the actual treatment given can only be made by using in vivo dosimetry. Treatment records must be kept of all relevant aspects of the treatment – including Session and Summary Record information, Records all treatment parameters, Dose Calculations and Dose Measurements
In vivo dosimetry using thermoluminescent detector in cancer therapy of head and neck
International Nuclear Information System (INIS)
Viegas, Claudio C.B.; Batista, D.V.; Campos, A.M.; Lopes, R.T.
2002-01-01
The viability and implementation of a routine in vivo dosimetry, using thermoluminescent dosemeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck treatment is shown. In order to reach that aim, the characteristics of the response of the LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performed of this detector for in vivo dosimetry was testes using an RANDO Alderson anthropomorphic phantom and, once their adequability proved for the kind of measurements proposed , it was used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)
Radiotherapy in cooperative clinical trials: Northern California Oncology Group (NCOG) method
International Nuclear Information System (INIS)
MacDonald, E.A.; Meurk, M.L.; Ray, G.; Phillips, T.L.; Carter, S.K.
1980-01-01
The inclusion of radiation therapy in multimodality clinical research has demonstrated the need for consultion and standardization of terminology and practice between participating centers. A set of guidelines has been developed to ensure that the radiotherapy section of a cooperative study is comprehensive and unambiguous, and that the techniques, fractionation and dosage used are sufficiently uniform to provide a homogeneous group of patients for comparative purposes. An outline is given for the preparation of radiotherapy protocols including the necessary details of physical factors, localization and simulation, portal and treatment volume definition, dosimetry requirements, specification of dose, and treatment documentation
Radiation dose verification using real tissue phantom in modern radiotherapy techniques
International Nuclear Information System (INIS)
Gurjar, Om Prakash; Mishra, S.P.; Bhandari, Virendra; Pathak, Pankaj; Patel, Prapti; Shrivastav, Garima
2014-01-01
In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as 'head phantom' and goat meat as 'tissue phantom'. The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD): 0.74), 2.36 (SD: 0.77), 3.62 (SD: 1.05), and 3.31 (SD: 0.78) for three-dimensional conformal radiotherapy (3DCRT) (head phantom), intensity modulated radiotherapy (IMRT; head phantom), 3DCRT (tissue phantom), and IMRT (tissue phantom), respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%), but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body. (author)
Radiation dose verification using real tissue phantom in modern radiotherapy techniques
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Om Prakash Gurjar
2014-01-01
Full Text Available In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as "head phantom" and goat meat as "tissue phantom". The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD: 0.74, 2.36 (SD: 0.77, 3.62 (SD: 1.05, and 3.31 (SD: 0.78 for three-dimensional conformal radiotherapy (3DCRT (head phantom, intensity modulated radiotherapy (IMRT; head phantom, 3DCRT (tissue phantom, and IMRT (tissue phantom, respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%, but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body.
Towards Establishing Capacity for Biological Dosimetry at Ghana Atomic Energy Commission.
Achel, Daniel Gyingiri; Achoribo, Elom; Agbenyegah, Sandra; Adaboro, Rudolph M; Donkor, Shadrack; Adu-Bobi, Nana A K; Agyekum, Akwasi A; Akuamoa, Felicia; Tagoe, Samuel N; Kyei, Kofi A; Yarney, Joel; Serafin, Antonio; Akudugu, John M
2016-01-01
The aim of this study was not only to obtain basic technical prerequisites for the establishment of capacity of biological dosimetry at the Ghana Atomic Energy Commission (GAEC) but also to stimulate interest in biological dosimetry research in Ghana and Sub-Saharan Africa. Peripheral blood from four healthy donors was exposed to different doses (0-6 Gy) of gamma rays from a radiotherapy machine and lymphocytes were subsequently stimulated, cultured, and processed according to standard protocols for 48-50 h. Processed cells were analyzed for the frequencies of dicentric and centric ring chromosomes. Radiation dose delivered to the experimental model was verified using GafChromic® EBT films in parallel experiments. Basic technical prerequisites for the establishment of capacity of biological dosimetry in the GAEC have been realized and expertise in the dicentric chromosome assay consolidated. We successfully obtained preliminary cytogenetic data for a dose-response relationship of the irradiated blood lymphocytes. The data strongly indicate the existence of significant linear (α) and quadratic (β) components and are consistent with those published for the production of chromosome aberrations in comparable absorbed dose ranges.
Use of photogrammetry for taking the outline of patients in radiotherapy
International Nuclear Information System (INIS)
Borel, F.; Defer, J.; Aget, H.; Gallet, O.; Urbajtel, M.; Laugier, A.
1975-01-01
A photogrammetric method for taking the outline of patients in radiotherapy is described. Using only one couple of photographs, this fast and very precise process may reconstruct many transversal or longitudinal cross-sections, after a photographic storage of information. An automatic numerical reading of the outline may be directly fed into a computer for dosimetry [fr
Optimization in radiotherapy treatment planning thanks to a fast dose calculation method
International Nuclear Information System (INIS)
Yang, Mingchao
2014-01-01
This thesis deals with the radiotherapy treatments planning issue which need a fast and reliable treatment planning system (TPS). The TPS is composed of a dose calculation algorithm and an optimization method. The objective is to design a plan to deliver the dose to the tumor while preserving the surrounding healthy and sensitive tissues. The treatment planning aims to determine the best suited radiation parameters for each patient's treatment. In this thesis, the parameters of treatment with IMRT (Intensity modulated radiation therapy) are the beam angle and the beam intensity. The objective function is multi-criteria with linear constraints. The main objective of this thesis is to demonstrate the feasibility of a treatment planning optimization method based on a fast dose-calculation technique developed by (Blanpain, 2009). This technique proposes to compute the dose by segmenting the patient's phantom into homogeneous meshes. The dose computation is divided into two steps. The first step impacts the meshes: projections and weights are set according to physical and geometrical criteria. The second step impacts the voxels: the dose is computed by evaluating the functions previously associated to their mesh. A reformulation of this technique makes possible to solve the optimization problem by the gradient descent algorithm. The main advantage of this method is that the beam angle parameters could be optimized continuously in 3 dimensions. The obtained results in this thesis offer many opportunities in the field of radiotherapy treatment planning optimization. (author) [fr
Roos, Jonas; Bejai, Sarosh; Mozūraitis, Raimondas; Dixelius, Christina
2015-02-01
The fungus Verticillium longisporum is a soil-borne plant pathogen of increasing economic importance, and information on plant responses to it is limited. To identify the genes and components involved in the early stages of infection, transcripts in roots of V. longisporum-challenged Arabidopsis Col-0 and the susceptible NON-RACE SPECIFIC DISEASE RESISTANCE 1 (ndr1-1) mutant were compared using ATH1 gene chips. The analysis revealed altered transcript levels of several terpene biosynthesis genes, including the monoterpene synthase TPS23/27. When transgenic 35S:TPS23/27 and TPS23/27-amiRNA plants were monitored the over-expresser line showed enhanced fungal colonization whereas the silenced genotype was indistinguishable from Col-0. Transcript analysis of terpene biosynthesis genes suggested that only the TPS23/27 pathway is affected in the two transgenic genotypes. To confirm changes in monoterpene production, emitted volatiles were determined using solid-phase microextraction and gas chromatography-mass spectrometry. Levels of all identified TPS23/27 monoterpene products were significantly altered in the transgenic plants. A stimulatory effect on conidial germination and hyphal growth of V. longisporum was also seen in co-cultivation with 35S:TPS23/27 plants and upon exposure to 1,8-cineole, the main product of TPS23/27. Methyl jasmonate treatments of myc2-1 and myc2-2 mutants and analysis of TPS23/27:uidA in the myc2-2 background suggested a dependence on jasmonic acid mediated by the transcription factor MYC2. Taken together, our results show that TPS23/27-produced monoterpenes stimulate germination and subsequent invasion of V. longisporum in Arabidopsis roots. © 2014 The Authors The Plant Journal © 2014 John Wiley & Sons Ltd.
Monte Carlo dosimetry for synchrotron stereotactic radiotherapy of brain tumours
International Nuclear Information System (INIS)
Boudou, Caroline; Balosso, Jacques; Esteve, Francois; Elleaume, Helene
2005-01-01
A radiation dose enhancement can be obtained in brain tumours after infusion of an iodinated contrast agent and irradiation with kilovoltage x-rays in tomography mode. The aim of this study was to assess dosimetric properties of the synchrotron stereotactic radiotherapy technique applied to humans (SSR) for preparing clinical trials. We designed an interface for dose computation based on a Monte Carlo code (MCNPX). A patient head was constructed from computed tomography (CT) data and a tumour volume was modelled. Dose distributions were calculated in SSR configuration for various energy beam and iodine content in the target volume. From the calculations, it appears that the iodine-filled target (10 mg ml -1 ) can be efficiently irradiated by a monochromatic beam of energy ranging from 50 to 85 keV. This paper demonstrates the feasibility of stereotactic radiotherapy for treating deep-seated brain tumours with monoenergetic x-rays from a synchrotron
International Nuclear Information System (INIS)
Rene, Nicholas J.; Brodeur, Marylene; Parker, William; Roberge, David; Freeman, Carolyn
2010-01-01
Background and purpose: Some CNS tumours present leptomeningeal dissemination. Craniospinal radiotherapy is complex and recurrences may occur at sites of target volume underdosage. IMRT, being highly conformal to the target, could theoretically underdose the optic nerves if they are not specifically targeted leading to optic nerve recurrences. We analyzed optic nerve dosimetry when they are not specifically targeted. Materials and methods: We designed 3D-conformal and tomotherapy plans for our last five patients treated to the craniospinal axis, not including the optic nerves in the target volume. We analyzed the dose delivered to the optic nerves, to the anterior and posterior half of the optic nerves, and to a theoretical optic nerve-PTV. Results: The dose delivered to the optic nerves was similar for both plans in all patients (V95% close to 100%) except one in whom tomotherapy considerably underdosed the anterior optic nerves. The dose to the optic nerve-PTV was lower with tomotherapy in all patients. Conclusion: Despite not intentionally targeting the optic nerves, the dose to the optic nerves with IMRT was similar to 3D-conformal plans in most cases but left no margin for setup error. In individual cases the anterior half of the optic nerves could be significantly underdosed.
Radiotherapy for Vestibular Schwannomas: A Critical Review
International Nuclear Information System (INIS)
Murphy, Erin S.; Suh, John H.
2011-01-01
Vestibular schwannomas are slow-growing tumors of the myelin-forming cells that cover cranial nerve VIII. The treatment options for patients with vestibular schwannoma include active observation, surgical management, and radiotherapy. However, the optimal treatment choice remains controversial. We have reviewed the available data and summarized the radiotherapeutic options, including single-session stereotactic radiosurgery, fractionated conventional radiotherapy, fractionated stereotactic radiotherapy, and proton beam therapy. The comparisons of the various radiotherapy modalities have been based on single-institution experiences, which have shown excellent tumor control rates of 91-100%. Both stereotactic radiosurgery and fractionated stereotactic radiotherapy have successfully improved cranial nerve V and VII preservation to >95%. The mixed data regarding the ideal hearing preservation therapy, inherent biases in patient selection, and differences in outcome analysis have made the comparison across radiotherapeutic modalities difficult. Early experience using proton therapy for vestibular schwannoma treatment demonstrated local control rates of 84-100% but disappointing hearing preservation rates of 33-42%. Efforts to improve radiotherapy delivery will focus on refined dosimetry with the goal of reducing the dose to the critical structures. As future randomized trials are unlikely, we suggest regimented pre- and post-treatment assessments, including validated evaluations of cranial nerves V, VII, and VIII, and quality of life assessments with long-term prospective follow-up. The results from such trials will enhance the understanding of therapy outcomes and improve our ability to inform patients.
Implementation of a gel dosimeter for dosimetric verification of treatments with RapidArcTM
International Nuclear Information System (INIS)
Cortes, H.; Vasquez, J.; Plazas, M.
2014-08-01
The gel dosimetry represents advantages on other dosimetric systems for its potential of analyzing information in third dimension (3D). This work seeks to find another alternative for the verification of treatments of high complexity like the RapidArc TM . A gel type Magic was prepared and characterized, which was irradiated with base in a plan of RapidArc TM calculated in the Treatment Planning System (Tps) Eclipse, using the Anisotropic Analytic Algorithm (Aaa) for a beam with an acceleration potential of 6 MV. The dosimeter was characterized using Magnetic Resonance Images starting from the correlation between the T2 and the dose. The dose distribution curves were analyzed in second dimension (2D) using the program Omni Pro-I mrT and were compared with the curves obtained for the Tps under the approach gamma 2D. The comparison showed that the Gel represents a valid option inside the acceptable ranges for Quality Assurance in radiotherapy. (Author)
Energy Technology Data Exchange (ETDEWEB)
Cortes, H.; Vasquez, J. [Centro de Control de Cancer Ltda., Carrera 16A No. 83 A-11, 110911 Bogota (Colombia); Plazas, M., E-mail: hhcortess@unal.edu.co [Universidad Nacional de Colombia, Av. Carrera 30 No. 45, 110911 Bogota (Colombia)
2014-08-15
The gel dosimetry represents advantages on other dosimetric systems for its potential of analyzing information in third dimension (3D). This work seeks to find another alternative for the verification of treatments of high complexity like the RapidArc{sup TM}. A gel type Magic was prepared and characterized, which was irradiated with base in a plan of RapidArc{sup TM} calculated in the Treatment Planning System (Tps) Eclipse, using the Anisotropic Analytic Algorithm (Aaa) for a beam with an acceleration potential of 6 MV. The dosimeter was characterized using Magnetic Resonance Images starting from the correlation between the T2 and the dose. The dose distribution curves were analyzed in second dimension (2D) using the program Omni Pro-I mrT and were compared with the curves obtained for the Tps under the approach gamma 2D. The comparison showed that the Gel represents a valid option inside the acceptable ranges for Quality Assurance in radiotherapy. (Author)
Energy Technology Data Exchange (ETDEWEB)
Mehdizadeh, S; Sina, S [Radiation Research Center, Shiraz University, Shiraz (Iran, Islamic Republic of); Karimipourfard, M; Lotfalizadeh, F [Nuclear Engineering department, Shiraz University, Shiraz (Iran, Islamic Republic of); Faghihi, R [Radiation Research Center, Shiraz University, Shiraz (Iran, Islamic Republic of); Nuclear Engineering department, Shiraz University, Shiraz (Iran, Islamic Republic of); Babaei, A [Shiraz University of medical sciences, Shiraz (Iran, Islamic Republic of)
2014-06-01
Purpose: The purpose of this study is the design and fabrication of a multipurpose anthropomorphic neck and thyroid phantom for use in medical applications (i.e. quality control of images in nuclear medicine, and dosimetry). Methods: The designed neck phantom is composed of seven elliptic cylindrical slices with semi-major axis of 14 and semi-minor axis of 12.5 cm, each having the thickness of 2cm. Thyroid gland, bony part of the neck, and the wind pipe were also built inside the neck phantom. Results: The phantom contains some removable plugs,inside and at its surface to accommodate the TLD chips with different shapes and dimensions, (i.e. rod, cylindrical and cubical TLD chips)for the purpose of medical dosimetry (i.e. in radiology, radiotherapy, and nuclear medicine). For the purpose of quality control of images in nuclear medicine, the removable thyroid gland was built to accommodate the radioactive iodine. The female and male thyroid glands were built in two sizes separately. Conclusion: The designed phantom is a multi-functional phantom which is applicable for dosimetry in diagnostic radiology, radiotherapy, and quality control of images in nuclear medicine.
Phase-space database for external beam radiotherapy. Summary report of a consultants' meeting
International Nuclear Information System (INIS)
Capote, R.; Jeraj, R.; Ma, C.M.; Rogers, D.W.O.; Sanchez-Doblado, F.; Sempau, J.; Seuntjens, J.; Siebers, J.V.
2006-01-01
A summary is given of a Consultants' Meeting assembled to discuss and recommend actions and activities to prepare a Phase-space Database for External Beam Radiotherapy. The new database should serve to disseminate phase-space data of those accelerators and 60 Co units used in radiotherapy through the compilation of existing data that have been properly validated. Both the technical discussions and the resulting work plan are described, along with the detailed recommendations for implementation. The meeting was jointly organized by NAPC-Nuclear Data Section and NAHU-Dosimetry and Medical Radiation Physics Section. (author)
An independent dose calculation algorithm for MLC-based stereotactic radiotherapy
International Nuclear Information System (INIS)
Lorenz, Friedlieb; Killoran, Joseph H.; Wenz, Frederik; Zygmanski, Piotr
2007-01-01
We have developed an algorithm to calculate dose in a homogeneous phantom for radiotherapy fields defined by multi-leaf collimator (MLC) for both static and dynamic MLC delivery. The algorithm was developed to supplement the dose algorithms of the commercial treatment planning systems (TPS). The motivation for this work is to provide an independent dose calculation primarily for quality assurance (QA) and secondarily for the development of static MLC field based inverse planning. The dose calculation utilizes a pencil-beam kernel. However, an explicit analytical integration results in a closed form for rectangular-shaped beamlets, defined by single leaf pairs. This approach reduces spatial integration to summation, and leads to a simple method of determination of model parameters. The total dose for any static or dynamic MLC field is obtained by summing over all individual rectangles from each segment which offers faster speed to calculate two-dimensional dose distributions at any depth in the phantom. Standard beam data used in the commissioning of the TPS was used as input data for the algorithm. The calculated results were compared with the TPS and measurements for static and dynamic MLC. The agreement was very good (<2.5%) for all tested cases except for very small static MLC sizes of 0.6 cmx0.6 cm (<6%) and some ion chamber measurements in a high gradient region (<4.4%). This finding enables us to use the algorithm for routine QA as well as for research developments
Glass, David E.
2008-01-01
Thermal protection systems (TPS) and hot structures are required for a range of hypersonic vehicles ranging from ballistic reentry to hypersonic cruise vehicles, both within Earth's atmosphere and non-Earth atmospheres. The focus of this paper is on air breathing hypersonic vehicles in the Earth's atmosphere. This includes single-stage to orbit (SSTO), two-stage to orbit (TSTO) accelerators, access to space vehicles, and hypersonic cruise vehicles. This paper will start out with a brief discussion of aerodynamic heating and thermal management techniques to address the high heating, followed by an overview of TPS for rocket-launched and air-breathing vehicles. The argument is presented that as we move from rocket-based vehicles to air-breathing vehicles, we need to move away from the insulated airplane approach used on the Space Shuttle Orbiter to a wide range of TPS and hot structure approaches. The primary portion of the paper will discuss issues and design options for CMC TPS and hot structure components, including leading edges, acreage TPS, and control surfaces. The current state-of-the-art will be briefly discussed for some of the components. The two primary technical challenges impacting the use of CMC TPS and hot structures for hypersonic vehicles are environmental durability and fabrication, and will be discussed briefly.
Personal Dosimetry in UHC Sestre Milosrdnice: 10-Years Review
International Nuclear Information System (INIS)
Bokulic, T.; Budanec, M; Gregov, M.; Kusic, Z.; Mlinaric, M.; Mrcela, I.; Suric Mihic, M.
2013-01-01
Personal dose monitoring in UHC 'Sestre milosrdnice' is regulary performed for about 300 exposed workers involved in a variety of tasks with different sources of ionizing radiation. Exposed workers are required to wear personal dosimeters which are read on monthly basis and dose records are kept in the hospital. In this paper an overview of personal dosimetry data from year 2003 till 2013 is presented. Film dosimeters were used for personal dosimetry untill 2010 when the thermoluminescent (TL) dosimetry was introduced. Dosimeters are calibrated to measure personal dose equivalent H p (10). Received doses are analyzed for workers in the field of nuclear medicine, radiotherapy (external beam and brachytherapy), general diagnostic radiology and interventional radiology. Analysis of received doses in the whole period resulted with an average individual dose in nuclear medicine of 0.6 mSv/y, which decreased to 0.21 mSv/y in the last three years, caused by more precise dosimetric methods with TL dosimetry and improved conditions of radiation protection. In the same three-year period, in interventional radiology doses were 0.32 mSv/y, compared to 0.29 mSv/y obtained for a previous seven years. This was expected due to the escalation in a number of interventions and new installed equipment. There was no such difference in diagnostic radiology doses, showing that film dosimetry is suitable for x ray energies. Analysis of all the readings showed a significant influence of measurement procedures on personal dosimeter dose and also the importance of continuous monitoring of the dose records in order to improve the conditions of radiation protection and achieving the ALARA goal.(author)
Energy Technology Data Exchange (ETDEWEB)
Mendez V, J. [Departamento de Radioterapia, Instituto de Enfermedades Neoplasicas, Avenida Angamos Este 2520, Lima 34 (Peru)
1998-12-31
In this work it is presented an advance in Electron dosimetry of irregular fields for beams emitted by linear accelerators. At present diverse methods exist which are coming to apply in the Radiotherapy centers. In this work it is proposed a method for irregular fields dosimetry. It will be allow to calculate the dose rate absorbed required for evaluating the time for the treatment of cancer patients. Utilizing the results obtained by the dosimetric system, it has been possible to prove the validity of the method describe for 12 MeV energy and for square field 7.5 x 7.5 cm{sup 2} with percentile error less than 1 % . (Author)
ESTUDIO FISICOQUÍMICO DE MEZCLAS DE ALMIDÓN TERMOPLÁSTICO (TPS Y POLICAPROLACTONA (PCL
Directory of Open Access Journals (Sweden)
JOSE MINA H.
Full Text Available Se estudiaron las propiedades físico-químicas de un almidón termoplástico (TPS de yuca, plastificado con glicerol, y el efecto de la incorporación de policaprolactona (PCL en el desarrollo de tres mezclas binarias TPS-PCL a proporciones 60-40, 50-50 y 40-60. El estudio inició con la preparación por extrusión del TPS y su posterior mezcla en caliente con la policaprolactona. El análisis de los resultados se enfocó principalmente a la identificación y seguimiento de la retrogradación, que se dio en el almidón termoplástico para diferentes tiempos de acondicionamiento (a 54% H.R. y 25ºC. Con el proceso de plastificación del almidón se generó una masa predominantemente amorfa, evidenciada por los resultados obtenidos con SEM, DRX y FTIR. Con la incorporación de la PCL se obtuvieron mezclas inmiscibles, en las cuales el TPS se constituyó en la fase dispersa y que conservaron una tendencia en la variación de las propiedades con el tiempo de acondicionamiento, similar a la observada en el TPS solo; indicando este hecho que las interacciones físico-químicas generadas entre el TPS y la policaprolactona no fueron lo suficientemente fuertes, como para incidir en la variación estructural del TPS, la cual se dio independiente del contenido de PCL.
Energy Technology Data Exchange (ETDEWEB)
Rojas C, E.L
2004-07-01
In the last decade, dosimetry has evolved in an accelerated way due in part, to the development of new techniques and advances in instruments manufactured for several applications in Medical Physics. In order to improve achievements gotten with the use of radiation sources for therapeutic use, a guessed right dosimetry must be done and clinical data must be explained with the aid of investigation and supported with scientific bases. In this context, Monte Carlo (MC) method used to simulate radiation transport in materials, contribute with extensive knowledge and extremely useful information to that objective. MC dosimetry has some advantages over experimental and analytical dosimetry but it also has limitations. Maybe the most important is the computer time required to reach to an acceptable uncertainty level in a complex problem. Though this restrictive factor, a right application of MC simulation of radiation transport is a useful, reliable and versatile instrument for dosimetric calculations. From our point of view, the problem of heterogeneities in the sources or in the treatment targets in radiotherapy is of great importance, and this is the principal question to study aboard in this work. We use the MC simulation code Penelope to calculate some dosimetric quantities.The cases we study involve dosimetric aspects of different geometric distributions of radionuclides where interfaces are evident and must be taken into account. This work is divided in five chapters. In the first chapter we give a succinctly description of MC codes for simulation of the transport of particles in a medium and we describe the code Penelope. In chapter two, we study spherical distributions of radionuclides and the effect that interfaces in the target have in the dose received by the tumor. Specifically we study the application of radiocolloids with {sup 186} Re and {sup 32} P to treat homogeneous and nonhomogeneous cystic craniopharyngioma. Chapter three is dedicated to study plane
WE-AB-201-02: TPS Commissioning and QA: A Process Orientation and Application of Control Charts
International Nuclear Information System (INIS)
Sharpe, M.
2015-01-01
Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades. Over the same time, continuing innovations have made the TPS even more complex and more central to the clinical process. Medical goals are now expressed in terms of the dose and margins around organs and tissues that are delineated from multiple imaging modalities (CT, MR and PET); and even temporally resolved (i.e., 4D) imaging. This information is passed on to optimization algorithms to establish accelerator movements that are programmed directly for IMRT, VMAT and stereotactic treatments. These advances have made commissioning and QA of the TPS much more challenging. This education session reviews up-to-date experience and guidance on this subject; including the recently published AAPM Medical Physics Practice Guideline (MPPG) #5 “Commissioning and QA of Treatment Planning Dose Calculations: Megavoltage Photon and Electron Beams”. Treatment Planning System Commissioning and QA: Challenges and Opportunities (Greg Salomons) This session will provide some key background and review publications describing prominent incidents relating to TPS commissioning and QA. Traditional approaches have been hardware and feature oriented. They aim to establish a functional configuration and establish specifications for regular testing of features (like dose calculation) to assure stable operation and detect failures. With the advent of more complex systems, more patient-specific testing has also been adopted. A number of actual TPS defects will be presented along with heuristics for identifying similar
WE-AB-201-02: TPS Commissioning and QA: A Process Orientation and Application of Control Charts
Energy Technology Data Exchange (ETDEWEB)
Sharpe, M. [The Princess Margaret Cancer Centre - UHN (Canada)
2015-06-15
Treatment planning systems (TPS) are a cornerstone of modern radiation therapy. Errors in their commissioning or use can have a devastating impact on many patients. To support safe and high quality care, medical physicists must conduct efficient and proper commissioning, good clinical integration, and ongoing quality assurance (QA) of the TPS. AAPM Task Group 53 and related publications have served as seminal benchmarks for TPS commissioning and QA over the past two decades. Over the same time, continuing innovations have made the TPS even more complex and more central to the clinical process. Medical goals are now expressed in terms of the dose and margins around organs and tissues that are delineated from multiple imaging modalities (CT, MR and PET); and even temporally resolved (i.e., 4D) imaging. This information is passed on to optimization algorithms to establish accelerator movements that are programmed directly for IMRT, VMAT and stereotactic treatments. These advances have made commissioning and QA of the TPS much more challenging. This education session reviews up-to-date experience and guidance on this subject; including the recently published AAPM Medical Physics Practice Guideline (MPPG) #5 “Commissioning and QA of Treatment Planning Dose Calculations: Megavoltage Photon and Electron Beams”. Treatment Planning System Commissioning and QA: Challenges and Opportunities (Greg Salomons) This session will provide some key background and review publications describing prominent incidents relating to TPS commissioning and QA. Traditional approaches have been hardware and feature oriented. They aim to establish a functional configuration and establish specifications for regular testing of features (like dose calculation) to assure stable operation and detect failures. With the advent of more complex systems, more patient-specific testing has also been adopted. A number of actual TPS defects will be presented along with heuristics for identifying similar
Directory of Open Access Journals (Sweden)
N Heidarloo
2017-08-01
Full Text Available Intraoperative electron radiotherapy is one of the radiotherapy methods that delivers a high single fraction of radiation dose to the patient in one session during the surgery. Beam shaper applicator is one of the applicators that is recently employed with this radiotherapy method. This applicator has a considerable application in treatment of large tumors. In this study, the dosimetric characteristics of the electron beam produced by LIAC intraoperative radiotherapy accelerator in conjunction with this applicator have been evaluated through Monte Carlo simulation by MCNP code. The results showed that the electron beam produced by the beam shaper applicator would have the desirable dosimetric characteristics, so that the mentioned applicator can be considered for clinical purposes. Furthermore, the good agreement between the results of simulation and practical dosimetry, confirms the applicability of Monte Carlo method in determining the dosimetric parameters of electron beam intraoperative radiotherapy
Energy Technology Data Exchange (ETDEWEB)
Pham, Daniel, E-mail: Daniel.Pham@petermac.org [Radiotherapy Services, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Kron, Tomas [Physical Sciences, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia); Foroudi, Farshad; Siva, Shankar [Radiation Oncology, Peter MacCallum Cancer Centre, East Melbourne, Victoria (Australia)
2013-10-01
Stereotactic ablative body radiotherapy (SABR) for primary renal cell carcinoma (RCC) targets requires motion management strategies to verify dose delivery. This case study highlights the effect of a change in patient breathing amplitude on the dosimetry to organs at risk and target structures. A 73-year-old male patient was planned for receiving 26 Gy of radiation in 1 fraction of SABR for a left primary RCC. The patient was simulated with four-dimensional computed tomography (4DCT) and the tumor internal target volume (ITV) was delineated using the 4DCT maximum intensity projection. However, the initially planned treatment was abandoned at the radiation oncologist's discretion after pretreatment cone-beam CT (CBCT) motion verification identified a greater than 50% reduction in superior to inferior diaphragm motion as compared with the planning 4DCT. This patient was resimulated with respiratory coaching instructions. To assess the effect of the change in breathing on the dosimetry to the target, each plan was recalculated on the data set representing the change in breathing condition. A change from smaller to larger breathing showed a 46% loss in planning target volume (PTV) coverage, whereas a change from larger breathing to smaller breathing resulted in an 8% decrease in PTV coverage. ITV coverage was similarly reduced by 8% in both scenarios. This case study highlights the importance of tools to verify breathing motion prior to treatment delivery. 4D image guided radiation therapy verification strategies should focus on not only verifying ITV margin coverage but also the effect on the surrounding organs at risk.
International Nuclear Information System (INIS)
Pham, Daniel; Kron, Tomas; Foroudi, Farshad; Siva, Shankar
2013-01-01
Stereotactic ablative body radiotherapy (SABR) for primary renal cell carcinoma (RCC) targets requires motion management strategies to verify dose delivery. This case study highlights the effect of a change in patient breathing amplitude on the dosimetry to organs at risk and target structures. A 73-year-old male patient was planned for receiving 26 Gy of radiation in 1 fraction of SABR for a left primary RCC. The patient was simulated with four-dimensional computed tomography (4DCT) and the tumor internal target volume (ITV) was delineated using the 4DCT maximum intensity projection. However, the initially planned treatment was abandoned at the radiation oncologist's discretion after pretreatment cone-beam CT (CBCT) motion verification identified a greater than 50% reduction in superior to inferior diaphragm motion as compared with the planning 4DCT. This patient was resimulated with respiratory coaching instructions. To assess the effect of the change in breathing on the dosimetry to the target, each plan was recalculated on the data set representing the change in breathing condition. A change from smaller to larger breathing showed a 46% loss in planning target volume (PTV) coverage, whereas a change from larger breathing to smaller breathing resulted in an 8% decrease in PTV coverage. ITV coverage was similarly reduced by 8% in both scenarios. This case study highlights the importance of tools to verify breathing motion prior to treatment delivery. 4D image guided radiation therapy verification strategies should focus on not only verifying ITV margin coverage but also the effect on the surrounding organs at risk
International Nuclear Information System (INIS)
Liu, Jia; Ng, Diana; Lee, James; Stalley, Paul; Hong, Angela
2016-01-01
Definitive radiotherapy is often used for chest wall desmoid tumours due to size or anatomical location. The delivery of radiotherapy is challenging due to the large size and constraints of normal surrounding structures. We compared the dosimetry of 3D conformal radiotherapy (3DCRT), intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc radiotherapy (VMAT) to evaluate the best treatment option. Ten consecutive patients with inoperable chest wall desmoid tumours (PTV range 416–4549 cm 3 ) were selected. For each patient, 3DCRT, IMRT and VMAT plans were generated and the Conformity Index (CI), organ at risk (OAR) doses and monitor unit (MU) were evaluated. The Wilcoxon signed-rank test was used to compare dose delivered to both target and OARs. The mean number of fields for 3DCRT and IMRT were 6.3 ± 2.1, 7.2 ± 1.8. The mean number of arcs for VMAT was 3.7 ± 1.1. The mean conformity index of VMAT (0.98 ± 0.14) was similar to that of IMRT (1.03 ± 0.13), both of which were significantly better than 3DCRT (1.35 ± 0.20; p = 0.005). The mean dose to lung was significantly higher for 3DCRT (11.9Gy ± 7.9) compared to IMRT (9.4Gy ± 5.4, p = 0.014) and VMAT (8.9Gy ± 4.5, p = 0.017). For the 3 females, the low dose regions in the ipsilateral breast for VMAT were generally less with VMAT. IMRT plans required 1427 ± 532 MU per fraction which was almost 4-fold higher than 3DCRT (313 ± 112, P = 0.005). Compared to IMRT, VMAT plans required 60 % less MU (570 ± 285, P = 0.005). For inoperable chest wall desmoid tumours, VMAT delivered equivalent target coverage when compared to IMRT but required 60 % less MU. Both VMAT and IMRT were superior to 3DCRT in terms of better PTV coverage and sparing of lung tissue
Audits for advanced treatment dosimetry
Ibbott, G. S.; Thwaites, D. I.
2015-01-01
Radiation therapy has advanced rapidly over the last few decades, progressing from 3D conformal treatment to image-guided intensity modulated therapy of several different flavors, both 3D and 4D and to adaptive radiotherapy. The use of intensity modulation has increased the complexity of quality assurance and essentially eliminated the physicist's ability to judge the validity of a treatment plan, even approximately, on the basis of appearance and experience. Instead, complex QA devices and procedures are required at the institutional level. Similarly, the assessment of treatment quality through remote and on-site audits also requires greater sophistication. The introduction of 3D and 4D dosimetry into external audit systems must follow, to enable quality assurance systems to perform meaningful and thorough audits.
Audits for advanced treatment dosimetry
International Nuclear Information System (INIS)
Ibbott, G S; Thwaites, D I
2015-01-01
Radiation therapy has advanced rapidly over the last few decades, progressing from 3D conformal treatment to image-guided intensity modulated therapy of several different flavors, both 3D and 4D and to adaptive radiotherapy. The use of intensity modulation has increased the complexity of quality assurance and essentially eliminated the physicist's ability to judge the validity of a treatment plan, even approximately, on the basis of appearance and experience. Instead, complex QA devices and procedures are required at the institutional level. Similarly, the assessment of treatment quality through remote and on-site audits also requires greater sophistication. The introduction of 3D and 4D dosimetry into external audit systems must follow, to enable quality assurance systems to perform meaningful and thorough audits
Energy Technology Data Exchange (ETDEWEB)
Petitfils, A
2007-09-15
Remarkable properties of synthetic diamond (human soft tissue equivalence, chemical stability, non-toxicity) make this material suitable for medical application as thermoluminescent dosimeter (TLD). This work highlights the interest of this material as radiotherapy TLD. In the first stage of this work, we looked after thermoluminescent (TL) and dosimetric properties of polycrystalline diamond made by Chemically Vapor Deposited (CVD) synthesis. Dosimetric characteristics are satisfactory as TLD for medical application. Luminescence thermal quenching on diamond has been investigated. This phenomenon leads to a decrease of dosimetric TL peak sensitivity when the heating rate increases. The second part of this work analyses the use of synthetic diamond as TLD in radiotherapy. Dose profiles, depth dose distributions and the cartography of an electron beam obtained with our samples are in very good agreement with results from an ionisation chamber. It is clearly shown that CVD) diamond is of interest to check beams of treatment accelerators. The use of these samples in a control of treatment with Intensity Modulated Radiation Therapy underlines good response of synthetic diamond in high dose gradient areas. These results indicate that CVD diamond is a promising material for radiotherapy dosimetry. (author)
Energy Technology Data Exchange (ETDEWEB)
Mendes, Bruno Melo
2017-07-01
The use of Ionizing radiation (IR) in medicine has increased considerably. The benefits generated by diagnostic and therapy techniques with IR are proven. Nevertheless, the risks arising from these uses should not be underestimated. Justification, a basic radiation protection, states that the benefits from exposures must outweigh detriment. The cancer induction is one of the detriment components. Thus, the study of the benefit/detriment ratio should take into account cancer incidence and mortality estimations resulting from a given diagnosis or therapy radiological technique. The risk of cancer induction depends on the absorbed doses in the irradiated organs and tissues. Thus, IR dosimetry is essential to evaluate the benefit/detriment ratio. The present work aims to perform computational dosimetric evaluations and estimations of cancer induction risk after ionizing radiation exposure. The investigated situations cover nuclear medicine, radiological contamination and radiotherapy fields. Computational dosimetry, with MCNPx Monte Carlo Code, was used as a tool to calculate the absorbed dose in the interest organs of the voxelized human models. The simulations were also used to obtain calibration factors and optimization of in vivo monitoring systems for internal contamination dosimetry. A breast radiotherapy (RT) standard protocol was simulated using the MCNPx code. The calculation of the radiation-induced cancer risk was adapted from the BEIR VII methodology for the Brazilian population. The absorbed doses used in the risk calculations were obtained through computational simulations of different exposure scenarios. During this work, two new computational phantoms, DM{sub B}RA and VW, were generated from tomographic images. Additional twelve voxelized phantoms, including the reference phantoms, RCP{sub A}M and RCP{sub A}F, and the child, baby, and fetus models were adapted to run on MCNP. Internal Dosimetry Protocols (IDP) for radiopharmaceuticals and for internal
Fiber-Coupled Spectrometer for TPS Materials, Phase I
National Aeronautics and Space Administration — Heat shield technology is a critical component of manned spaceflight. In particular, the new Crew Exploration Vehicle (CEV) requires thermal protection systems (TPS)...
National Committee for the follow-up of measures for radiotherapy 2008-2011 - Final report
International Nuclear Information System (INIS)
Buzyn, A.; Grall, J.Y; Selleret, F.X.; Lacoste, A.C.; Maraninchi, D.; Harousseau, J-L.; Chauvet, B.; LE DU, D.; Saout, C.; Renody, N.; Depenweiller, C.; Goinere, R.
2012-06-01
As always more patients suffering from cancer are treated by radiotherapy, and as several over-irradiation events occurred in 2007, measures have been implemented to guarantee radiotherapy practice quality and safety. This document reports the work and actions performed by the national follow-up committee and its work groups to define, implement and follow-up these measures. They encompassed information actions towards patients, public, physicians and establishment managers, and new authorization measures. The committee also addressed radiotherapy professions involved in manipulation, dosimetry, as well as radio-physicists and radiotherapists. It introduced measures regarding vigilance in radiation, the improvement of quality and safety in radiation therapy centres, research and development, and the financing of these measures
Dosimetry of Al2O3 optically stimulated luminescent dosimeter at high energy photons and electrons
Yusof, M. F. Mohd; Joohari, N. A.; Abdullah, R.; Shukor, N. S. Abd; Kadir, A. B. Abd; Isa, N. Mohd
2018-01-01
The linearity of Al2O3 OSL dosimeters (OSLD) were evaluated for dosimetry works in clinical photons and electrons. The measurements were made at a reference depth of Zref according to IAEA TRS 398:2000 codes of practice at 6 and 10 MV photons and 6 and 9 MeV electrons. The measured dose was compared to the thermoluminescence dosimeters (TLD) and ionization chamber commonly used for dosimetry works for higher energy photons and electrons. The results showed that the measured dose in OSL dosimeters were in good agreement with the reported by the ionization chamber in both high energy photons and electrons. A reproducibility test also reported excellent consistency of readings with the OSL at similar energy levels. The overall results confirmed the suitability of OSL dosimeters for dosimetry works involving high energy photons and electrons in radiotherapy.
Energy Technology Data Exchange (ETDEWEB)
Sarrut, David, E-mail: david.sarrut@creatis.insa-lyon.fr [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon (France); Université Lyon 1 (France); Centre Léon Bérard (France); Bardiès, Manuel; Marcatili, Sara; Mauxion, Thibault [Inserm, UMR1037 CRCT, F-31000 Toulouse, France and Université Toulouse III-Paul Sabatier, UMR1037 CRCT, F-31000 Toulouse (France); Boussion, Nicolas [INSERM, UMR 1101, LaTIM, CHU Morvan, 29609 Brest (France); Freud, Nicolas; Létang, Jean-Michel [Université de Lyon, CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Centre Léon Bérard, 69008 Lyon (France); Jan, Sébastien [CEA/DSV/I2BM/SHFJ, Orsay 91401 (France); Loudos, George [Department of Medical Instruments Technology, Technological Educational Institute of Athens, Athens 12210 (Greece); Maigne, Lydia; Perrot, Yann [UMR 6533 CNRS/IN2P3, Université Blaise Pascal, 63171 Aubière (France); Papadimitroulas, Panagiotis [Department of Biomedical Engineering, Technological Educational Institute of Athens, 12210, Athens (Greece); Pietrzyk, Uwe [Institut für Neurowissenschaften und Medizin, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany and Fachbereich für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal (Germany); Robert, Charlotte [IMNC, UMR 8165 CNRS, Universités Paris 7 et Paris 11, Orsay 91406 (France); and others
2014-06-15
In this paper, the authors' review the applicability of the open-source GATE Monte Carlo simulation platform based on the GEANT4 toolkit for radiation therapy and dosimetry applications. The many applications of GATE for state-of-the-art radiotherapy simulations are described including external beam radiotherapy, brachytherapy, intraoperative radiotherapy, hadrontherapy, molecular radiotherapy, and in vivo dose monitoring. Investigations that have been performed using GEANT4 only are also mentioned to illustrate the potential of GATE. The very practical feature of GATE making it easy to model both a treatment and an imaging acquisition within the same frameworkis emphasized. The computational times associated with several applications are provided to illustrate the practical feasibility of the simulations using current computing facilities.