Estimating pediatric entrance skin dose from digital radiography examination using DICOM metadata: A quality assurance tool

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Brady, S. L., E-mail: samuel.brady@stjude.org; Kaufman, R. A., E-mail: robert.kaufman@stjude.org [Department of Diagnostic Imaging, St. Jude Children’s Research Hospital, Memphis, Tennessee 38105 (United States)

2015-05-15

Purpose: To develop an automated methodology to estimate patient examination dose in digital radiography (DR) imaging using DICOM metadata as a quality assurance (QA) tool. Methods: Patient examination and demographical information were gathered from metadata analysis of DICOM header data. The x-ray system radiation output (i.e., air KERMA) was characterized for all filter combinations used for patient examinations. Average patient thicknesses were measured for head, chest, abdomen, knees, and hands using volumetric images from CT. Backscatter factors (BSFs) were calculated from examination kVp. Patient entrance skin air KERMA (ESAK) was calculated by (1) looking up examination technique factors taken from DICOM header metadata (i.e., kVp and mA s) to derive an air KERMA (k{sub air}) value based on an x-ray characteristic radiation output curve; (2) scaling k{sub air} with a BSF value; and (3) correcting k{sub air} for patient thickness. Finally, patient entrance skin dose (ESD) was calculated by multiplying a mass–energy attenuation coefficient ratio by ESAK. Patient ESD calculations were computed for common DR examinations at our institution: dual view chest, anteroposterior (AP) abdomen, lateral (LAT) skull, dual view knee, and bone age (left hand only) examinations. Results: ESD was calculated for a total of 3794 patients; mean age was 11 ± 8 yr (range: 2 months to 55 yr). The mean ESD range was 0.19–0.42 mGy for dual view chest, 0.28–1.2 mGy for AP abdomen, 0.18–0.65 mGy for LAT view skull, 0.15–0.63 mGy for dual view knee, and 0.10–0.12 mGy for bone age (left hand) examinations. Conclusions: A methodology combining DICOM header metadata and basic x-ray tube characterization curves was demonstrated. In a regulatory era where patient dose reporting has become increasingly in demand, this methodology will allow a knowledgeable user the means to establish an automatable dose reporting program for DR and perform patient dose related QA testing for

Method of estimating patient skin dose from dose displayed on medical X-ray equipment with flat panel detector

International Nuclear Information System (INIS)

Fukuda, Atsushi; Koshida, Kichiro; Togashi, Atsuhiko; Matsubara, Kousuke

2004-01-01

The International Electrotechnical Commission (IEC) has stipulated that medical X-ray equipment for interventional procedures must display radiation doses such as air kerma in free air at the interventional reference point and dose area product to establish radiation safety for patients (IEC 60601-2-43). However, it is necessary to estimate entrance skin dose for the patient from air kerma for an accurate risk assessment of radiation skin injury. To estimate entrance skin dose from displayed air kerma in free air at the interventional reference point, it is necessary to consider effective energy, the ratio of the mass-energy absorption coefficient for skin and air, and the backscatter factor. In addition, since automatic exposure control is installed in medical X-ray equipment with flat panel detectors, it is necessary to know the characteristics of control to estimate exposure dose. In order to calculate entrance skin dose under various conditions, we investigated clinical parameters such as tube voltage, tube current, pulse width, additional filter, and focal spot size, as functions of patient body size. We also measured the effective energy of X-ray exposure for the patient as a function of clinical parameter settings. We found that the conversion factor from air kerma in free air to entrance skin dose is about 1.4 for protection. (author)

The need for national diagnostic reference levels: entrance surface dose measurement in intraoral radiography

International Nuclear Information System (INIS)

Mortazavi, S. M. J.; Shareghi, A.; Kavousi, A.; Ghiassi-Nejad, M.; Jafari-Zadeh, M.; Nazeri, F.; Mozdarani, H.

2004-01-01

Background: Intraoral radiographies are the most frequent X-ray examinations in humans. According to International Commission on Radiation Protection recommendations, the selection of a diagnostic reference level should be specific to a country or region. Critical organs such as thyroid gland are exposed to X-rays in intraoral radiography and these exposures should be kept as low as reasonably achievable. To assist the development of DRLs for intraoral radiography, a National Radiation Protection Department-sponsored pilot study was carried out. Materials and methods: thermoluminescent dosimetry is widely acknowledged to be the recommended method for measuring entrance surface doses. In this study, entrance surface doses was measured using LiF thermoluminescent dosimeters on the skin (either mandibular or maxillary arcs) of 40 patients. Three thermoluminescent dosimetry chips were placed on the skin of each patient. The doses were averaged for each radiography and mean entrance surface doses of all patients calculated. Results: the mean ±SD entrance surface dose at the center of the beam on the patient's skin in intraoral radiography was 1.173 ±0.606 mGy (ranged from 0.01 o 0.40 m Gy). The mean entrance surface doses for male and female patients were 1.380± 0.823, and 1.004± 0.258 respectively. No statistically significant difference was found between these means. Despite its necessity , in national level , there is no published data on the diagnostic reference levels for intraoral radiography. However, the results obtained in this study are lower than those reported by investigators in other countries. Conclusion: in IR Iran , due to lack of large scale studies, no diagnostic reference levels have been set for X-ray diagnostic procedures. Due to lack of national diagnostic reference levels, it is not possible to clarify whether in intraoral radiographies any dose reduction techniques are needed. We intend to perform similar nationwide studies to set the

Direct measurement of a patient's entrance skin dose during pediatric cardiac catheterization

International Nuclear Information System (INIS)

Sun, Lue; Mizuno, Yusuke; Goto, Takahisa; Iwamoto, Mari; Koguchi, Yasuhiro; Miyamoto, Yuka; Tsuboi, Koji; Chida, Koichi; Moritake, Takashi

2014-01-01

Children with complex congenital heart diseases often require repeated cardiac catheterization; however, children are more radiosensitive than adults. Therefore, radiation-induced carcinogenesis is an important consideration for children who undergo those procedures. We measured entrance skin doses (ESDs) using radio-photoluminescence dosimeter (RPLD) chips during cardiac catheterization for 15 pediatric patients (median age, 1.92 years; males, n = 9; females, n = 6) with cardiac diseases. Four RPLD chips were placed on the patient's posterior and right side of the chest. Correlations between maximum ESD and dose-area products (DAP), total number of frames, total fluoroscopic time, number of cine runs, cumulative dose at the interventional reference point (IRP), body weight, chest thickness, and height were analyzed. The maximum ESD was 80 ± 59 (mean ± standard deviation) mGy. Maximum ESD closely correlated with both DAP (r = 0.78) and cumulative dose at the IRP (r = 0.82). Maximum ESD for coiling and ballooning tended to be higher than that for ablation, balloon atrial septostomy, and diagnostic procedures. In conclusion, we directly measured ESD using RPLD chips and found that maximum ESD could be estimated in real-time using angiographic parameters, such as DAP and cumulative dose at the IRP. Children requiring repeated catheterizations would be exposed to high radiation levels throughout their lives, although treatment influences radiation dose. Therefore, the radiation dose associated with individual cardiac catheterizations should be analyzed, and the effects of radiation throughout the lives of such patients should be followed. (author)

Response studies of three different dosimeters for skin entrance dose measurements using diagnostic X-ray machines

International Nuclear Information System (INIS)

Sonawane, A.U.; Kulkarni, Arti; Shirva, V.K.; Butani, M.L.; Pradhan, A.S.

2008-01-01

A TLD method based on CaSO 4 :Dy Teflon discs developed at the Bhabha Atomic Research Centre, Mumbai has been extensively used for various applications in diagnostic radiology in India. This method was recently used for evaluation of radiation quality and measurement of skin entrance doses (SEDs) in various hospitals for different diagnostic examinations. The use of TLD discs for these applications involves the process of preparation of TLD discs with different combination of filters and then measurement of TL output under different combinations of filters. The measurement of SEDs in diagnostic radiology is also carried out instantaneously and accurately by using very user friendly and compact state-of-art instruments. These consist of kVp Test-O-Meter (ToM) (Model RADIFLU-9001) and the dose ToM (Model 6001) manufactured by M/s UNFORS, Sweden. The kVp meter automatically calculates kVp and updates it every second in the range from 55 to 145 kVp with the resolution of 0.1 kV. The dose ToM incorporates sealed silicon detector having lead shield under and around, which prevents backscattered radiation from influencing the measurement. The dose Test-O-Meter has excellent energy independence in the range from 50 to 150 kVp and inaccuracy not exceeding 5 % at 70 k Vp. The dose meter is capable of measuring doses up to 9999 μGy

Evaluation of entrance surface-skin doses in animals submitted on exams of abdomen in veterinary radiology using Tl dosimetry

International Nuclear Information System (INIS)

Veneziani, G. R.; Matsushima, L. C.; Campos, L. L.; Filho, A. M.

2014-08-01

The radiation protection has recently gained considerable attention in human medicine. In veterinary medicine has been some advances in radiodiagnostic and therapy for domestic animal like dogs and cats. It is notable the increase of the costs with domestic animals that are considered, by many people in the whole world, like members of family. However, an important parameter that must be taken into account is the increasing use of computed tomography and other equipment s that uses ionizing radiation, which may lead to comparatively high exposure of critical organs. The radiation dose is determined by the balance between therapeutic benefit and possible damage to surrounding normal tissues. This study aimed the evaluation of entrance surface-skin doses in dogs submitted to radiodiagnostic procedures of abdomen using the technique of thermoluminescent dosimetry (TLD). The radiation doses were measured using thermoluminescent dosimeters of LiF:Mg,Ti (TLD 100) and a dog phantom made with a plastic container, proportional to the dog size, fulfilled with water. (Author)

Evaluation of entrance surface-skin doses in animals submitted on exams of abdomen in veterinary radiology using Tl dosimetry

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Veneziani, G. R.; Matsushima, L. C.; Campos, L. L. [Instituto de Pesquisas Energeticas e Nucleares, Gerencia de Metrologia das Radiacoes / CNEN, Av. Lineu Prestes 2242, Cidade Universitaria, 05508-000 Sao Paulo (Brazil); Filho, A. M., E-mail: venezianigr@gmail.com [Centro Universitario de Rio Petro - UNIRP, Rodovia Br 153 (Transbrasiliana), Km. 69 Sao Jose do Rio Preto, Sao Paulo (Brazil)

2014-08-15

The radiation protection has recently gained considerable attention in human medicine. In veterinary medicine has been some advances in radiodiagnostic and therapy for domestic animal like dogs and cats. It is notable the increase of the costs with domestic animals that are considered, by many people in the whole world, like members of family. However, an important parameter that must be taken into account is the increasing use of computed tomography and other equipment s that uses ionizing radiation, which may lead to comparatively high exposure of critical organs. The radiation dose is determined by the balance between therapeutic benefit and possible damage to surrounding normal tissues. This study aimed the evaluation of entrance surface-skin doses in dogs submitted to radiodiagnostic procedures of abdomen using the technique of thermoluminescent dosimetry (TLD). The radiation doses were measured using thermoluminescent dosimeters of LiF:Mg,Ti (TLD 100) and a dog phantom made with a plastic container, proportional to the dog size, fulfilled with water. (Author)

Characterization of a cable-free system based on p-type MOSFET detectors for "in vivo" entrance skin dose measurements in interventional radiology.

Science.gov (United States)

Falco, Maria Daniela; D'Andrea, Marco; Strigari, Lidia; D'Alessio, Daniela; Quagliani, Francesco; Santoni, Riccardo; Bosco, Alessia Lo

2012-08-01

During radiological interventional procedures (RIP) the skin of a patient under examination may undergo a prolonged x-ray exposure, receiving a dose as high as 5 Gy in a single session. This paper describes the use of the OneDose(TM) cable-free system based on p-type MOSFET detectors to determine the entrance skin dose (ESD) at selected points during RIP. At first, some dosimetric characteristics of the detector, such as reproducibility, linearity, and fading, have been investigated using a C-arc as a source of radiation. The reference setting (RS) was: 80 kV energy, 40 cm × 40 cm field of view (FOV), current-time product of 50 mAs and source to skin distance (SSD) of 50 cm. A calibrated PMX III solid state detector was used as the reference detector and Gafchromic(®) films have been used as an independent dosimetric system to test the entire procedure. A calibration factor for the RS and correction factors as functions of tube voltage and FOV size have been determined. Reproducibility ranged from 4% at low doses (around 10 cGy as measured by the reference detector) to about 1% for high doses (around 2 Gy). The system response was found to be linear with respect to both dose measured with the PMX III and tube voltage. The fading test has shown that the maximum deviation from the optimal reading conditions (3 min after a single irradiation) was 9.1% corresponding to four irradiations in one hour read 3 min after the last exposure. The calibration factor in the RS has shown that the system response at the kV energy range is about four times larger than in the MV energy range. A fifth order and fourth order polynomial functions were found to provide correction factors for tube voltage and FOV size, respectively, in measurement settings different than the RS. ESDs measured with the system after applying the proper correction factors agreed within one standard deviation (SD) with the corresponding ESDs measured with the reference detector. The ESDs measured with

Characteristics of dosemeter types for skin dose measurements in practice

International Nuclear Information System (INIS)

Van, D. J.; Bosmans, H.; Marchal, G.; Wambersie, A.

2005-01-01

A growing number of papers report deterministic effects in the skin of patients who have undergone interventional radiological procedures. Dose measurements, and especially skin dose measurements, are therefore increasingly important. Methods and acceptable dosemeters are, however, not clearly defined. This paper is the result of a literature overview with regard to assessing the entrance skin dose during radiological examinations by putting a dosemeter on the patient's skin. The relevant intrinsic characteristics, as well as some examples of clinical use of the different detector types, are presented. In this respect, thermoluminescence, scintillation, semiconductor and film dosemeters are discussed and compared with respect to their practical use. (authors)

Skin entrance dose - thyroid: comparison between three kinds of dental appliances; Dose de entrada na pele - tireóide: comparativo entre três tipos de aparelhos odontológicos

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Savi, M.; Viana, E.; Soares, F.A., E-mail: matheus.savi@ifsc.edu.br [Dept. Acadêmico de Saúde e Serviços/CST em Radiologia, Instituto Federal de Santa Catarina, Florianópolis (Brazil)

2017-07-01

Patient dosimetry is necessary to determine dosimetric quantities, establish reference levels for radio-diagnosis and assess health risks. Part of the radiation beam of the appliances that penetrates the patient's body is absorbed by tissues and part is spread and its sum is known as the Dose of Entrance into the Skin. The objective of this study is to know and compare the DEP of dental radiology devices in the thyroid gland. Two periapical, panoramic and computerized conical beam tomographs were used in this study at a private dentistry clinic and at the Federal Institute of Santa Catarina. The periapical apparatus produced the highest total dose of radiation, as well as a higher dose rate, followed by CBCT and panoramic.

Prediction of midline dose from entrance ad exit dose using OSLD measurements for total irradiation

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Choi, Chang Heon; Park, Jong Min; Park, So Yeon; Chun, Min Soo; Han, Ji Hye; Cho, Jin Dong; Kim, Jung In [Dept. of Radiation Oncology, Seoul National University Hospital, Seoul (Korea, Republic of)

2017-06-15

This study aims to predict the midline dose based on the entrance and exit doses from optically stimulated luminescence detector (OSLD) measurements for total body irradiation (TBI). For TBI treatment, beam data sets were measured for 6 MV and 15 MV beams. To evaluate the tissue lateral effect of various thicknesses, the midline dose and peak dose were measured using a solid water phantom (SWP) and ion chamber. The entrance and exit doses were measured using OSLDs. OSLDs were attached onto the central beam axis at the entrance and exit surfaces of the phantom. The predicted midline dose was evaluated as the sum of the entrance and exit doses by OSLD measurement. The ratio of the entrance dose to the exit dose was evaluated at various thicknesses. The ratio of the peak dose to the midline dose was 1.12 for a 30 cm thick SWP at both energies. When the patient thickness is greater than 30 cm, the 15 MV should be used to ensure dose homogeneity. The ratio of the entrance dose to the exit dose was less than 1.0 for thicknesses of less than 30 cm and 40 cm at 6 MV and 15 MV, respectively. Therefore, the predicted midline dose can be underestimated for thinner body. At 15 MV, the ratios were approximately 1.06 for a thickness of 50 cm. In cases where adult patients are treated with the 15 MV photon beam, it is possible for the predicted midline dose to be overestimated for parts of the body with a thickness of 50 cm or greater. The predicted midline dose and OSLD-measured midline dose depend on the phantom thickness. For in-vivo dosimetry of TBI, the measurement dose should be corrected in order to accurately predict the midline dose.

Evaluation of Kerma rate in the skin entrance in interventional procedures guided by fluoroscopy

International Nuclear Information System (INIS)

Medeiros, Regina Bitelli; Alves, Fatima Faloppa Rodrigues; Ruberti Filha, Eny M.

2005-01-01

Interventional therapeutic procedures guided by fluoroscopy are responsible for delayed exposure to radiation of professionals and patients. The technology employed on generation of the pulsed fluoroscopy can be an important tool of protection used for reducing the exposure time. It generates constant width and varied frequency pulse or width pulse or varied frequency for a constant frequency. The typical doses into the skin and its relationship with the quality of the images in the various technical and operational conditions should be known by the professionals so that they can optimize them. Generated radiation doses were evaluated using the Toshiba Infinitix equipment used in invasive cardiology procedures and electrophysiological studies through the Kerma rate at the entrance of the patient's skin measured throughout the year of 2004. With these information shall be set out the criteria for the decision of the technical-operational conditions that allow minimizing of dose

Estimation of entrance dose on chest radiographs according to the exposure index on Computerized Radiology System: preliminary results; Estimativa de dose de entrada a partir do indice de exposicao em sistema CR: resultados preliminares

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Donomai, Luana Kaoru; Jornada, Tiago da Silva; Daros, Kellen Adriana Curci, E-mail: luana.donomai@gmail.com, E-mail: tiagosjornada@gmail.com, E-mail: daros.kellen@unifesp.br [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil)

2014-07-01

Digital radiology has improved image quality in radiographs in comparison to screen/film systems though the visual control of the quantity of radiation involved on these exams became more demanding due to the low perception of over and underexposed images. Therefore, this study aims to analyze the exposure index (EI) from chest examinations and relate them to the entrance skin dose. Indices from 29 patients and kerma entrance dose were correlated. A correlation coefficient equal to 0,6881 was calculated. EI and entrance dose are correlated positive and moderately, indicating the relevance to deepen the subject. (author)

Entrance doses during lateral lumbar spine and antero-posterior abdomen examinations: generator waveform dependence

International Nuclear Information System (INIS)

Morrison, G.D.; Underwood, A.C.

1995-01-01

In North Trent, UK, an entrance dose survey of lateral lumbar spine and antero-posterior (AP) abdomen examinations has been carried out in 17 radiology departments. The survey comprised 294 lateral lumbar spine and 322 AP abdomen entrance dose measurements. The mean entrance doses were found to be approximately half of the relevant national reference entrance dose levels of 30 mGy and 10 mGy, respectively. The effect of generator waveform on entrance dose was studied by separating the generators into two types: ''pulsating potential'' (PP) generators and ''constant potential'' (CP) generators for each examination. PP generators comprised 23% of the total number of examinations. The mean entrance dose and radiographic exposure factors from CP generators were found to be significantly lower than those from PP generators. The use of CP type generators, together with low attenuation components can significantly reduce patient entrance doses for these examinations. (author)

Calculation of midplane dose for total body irradiation from entrance and exit dose MOSFET measurements.

Science.gov (United States)

Satory, P R

2012-03-01

This work is the development of a MOSFET based surface in vivo dosimetry system for total body irradiation patients treated with bilateral extended SSD beams using PMMA missing tissue compensators adjacent to the patient. An empirical formula to calculate midplane dose from MOSFET measured entrance and exit doses has been derived. The dependency of surface dose on the air-gap between the spoiler and the surface was investigated by suspending a spoiler above a water phantom, and taking percentage depth dose measurements (PDD). Exit and entrances doses were measured with MOSFETs in conjunction with midplane doses measured with an ion chamber. The entrance and exit doses were combined using an exponential attenuation formula to give an estimate of midplane dose and were compared to the midplane ion chamber measurement for a range of phantom thicknesses. Having a maximum PDD at the surface simplifies the prediction of midplane dose, which is achieved by ensuring that the air gap between the compensator and the surface is less than 10 cm. The comparison of estimated midplane dose and measured midplane dose showed no dependence on phantom thickness and an average correction factor of 0.88 was found. If the missing tissue compensators are kept within 10 cm of the patient then MOSFET measurements of entrance and exit dose can predict the midplane dose for the patient.

Radiotherapy verification film for estimating cumulative entrance skin exposure for fluoroscopic examinations

International Nuclear Information System (INIS)

Geise, R.A.; Ansel, H.J.

1990-01-01

Measurement of skin entrance exposures during fluoroscopic procedures is complicated by the use of automatic exposure control devices and the presence of contrast media. Due to variability in positioning spot films from patient to patient, standard dosimeters, such as thermoluminescent, cannot be properly placed on the skin prior to examination. Prepackaged film of the type used for portal verification in radiation therapy held next to the patient's skin in a specially modified patient examination gown was found to be useful for determining the entrance skin exposure from both fluoroscopy and spot films during air contrast barium enema exams. The usable sensitivity range of this film has been found satisfactory for exposure measurements at exposures and kVps typically used for gastrointestinal fluoroscopic procedures. Errors in exposure estimates due to changes in film speed and contrast with kVp are less than 5% for the range of kVps used. Errors from variations in beam quality due to the adjacency of scattering material are approximately 5%. Entrance exposures determined with film agreed with those determined from TLD measurements to within 21%, with an average difference of 9%

SU-E-CAMPUS-I-04: Automatic Skin-Dose Mapping for An Angiographic System with a Region-Of-Interest, High-Resolution Detector

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Vijayan, S; Rana, V [Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center (United States); Setlur Nagesh, S [Toshiba Stroke and Vascular Research Center (United States); Ionita, C [Department of Biomedical Engineering, University at Buffalo (State University of New York), Buffalo, NY (United States); Rudin, S [Department of Radiology, Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center, Department of Biomedical Engineering, University at Buffalo (State University of New York), Buffalo, NY (United States); Bednarek, D [Department of Radiology, Department of Physiology and Biophysics, Toshiba Stroke and Vascular Research Center (United States)

2014-06-15

Purpose: Our real-time skin dose tracking system (DTS) has been upgraded to monitor dose for the micro-angiographic fluoroscope (MAF), a high-resolution, small field-of-view x-ray detector. Methods: The MAF has been mounted on a changer on a clinical C-Arm gantry so it can be used interchangeably with the standard flat-panel detector (FPD) during neuro-interventional procedures when high resolution is needed in a region-of-interest. To monitor patient skin dose when using the MAF, our DTS has been modified to automatically account for the change in scatter for the very small MAF FOV and to provide separated dose distributions for each detector. The DTS is able to provide a color-coded mapping of the cumulative skin dose on a 3D graphic model of the patient. To determine the correct entrance skin exposure to be applied by the DTS, a correction factor was determined by measuring the exposure at the entrance surface of a skull phantom with an ionization chamber as a function of entrance beam size for various beam filters and kVps. Entrance exposure measurements included primary radiation, patient backscatter and table forward scatter. To allow separation of the dose from each detector, a parameter log is kept that allows a replay of the procedure exposure events and recalculation of the dose components.The graphic display can then be constructed showing the dose distribution from the MAF and FPD separately or together. Results: The DTS is able to provide separate displays of dose for the MAF and FPD with field-size specific scatter corrections. These measured corrections change from about 49% down to 10% when changing from the FPD to the MAF. Conclusion: The upgraded DTS allows identification of the patient skin dose delivered when using each detector in order to achieve improved dose management as well as to facilitate peak skin-dose reduction through dose spreading. Research supported in part by Toshiba Medical Systems Corporation and NIH Grants R43FD0158401, R44FD

Assessment of entrance skin doses for patients undergoing diagnostic X-ray examinations in some major hospitals of Uttarakhand, India

International Nuclear Information System (INIS)

Uniyal, S.C.; Prasad, V.; Chaturvedi, V.; Raghuvanshi, S.; Sharma, S.D.

2016-01-01

Entrance skin dose (ESD) was calculated based on the X-ray beam output, the exposure parameters used for the actual examination and the standard value of backscatter factor. Descriptive statistics were generated from the data by using Microsoft Excel 2010. The third quartile values of ESDs obtained in this study for different X-ray projections of chest anterior-posterior (AP), chest posterior-anterior (PA), cervical spine, thoracic spine, lumber spine AP, lumber spine lateral, abdomen, KUB, pelvis, skull and knee joint were 0.79, 0.28, 1.20, 2.80, 4.26, 9.82, 2.68, 3.21, 2.69, 2.21 and 0.55 mGy respectively. The ratio of maximum to minimum ESD values ranges from 5.2 for thoracic spine to 19.76 for chest AP X-ray examinations. In general, the obtained ESD values were found to be either lower than or in agreement with the reported national/international values

Investigation of the Entrance Surface Dose and Dose to Different Organs in Lumbar Spine Imaging

Science.gov (United States)

Sina, S; Zeinali, B; Karimipoorfard, M; Lotfalizadeh, F; Sadeghi, M; Zamani, E; Faghihi, R

2014-01-01

Background: Dose assessment using proper dosimeters is especially important in radiation protection optimization and imaging justification in diagnostic radiology. Objective: The aim of this study is to obtain the Entrance Skin Dose (ESD) of patients undergoing lumbar spine imaging using two thermoluminescence dosimeters TLD-100 (LiF: Mg, Ti) and GR-200 (LiF: Mg, Cu, P) and also to obtain the absorbed dose to different organs in lumbar spine imaging with several views. Methods: To measure the ESD values of the patients undergoing lumbar spine imaging, the two TLD types were put on their skin surface. The ESD values for different views of lumbar spine imaging were also measured by putting the TLDs at the surface of the Rando phantom. Several TLD chips were inserted inside different organs of Rando phantom to measure the absorbed dose to different organs in lumbar spine imaging. Results: The results indicate that there is a close agreement between the results of the two dosimeters. Based on the results of this experiment, the ESD dose of the 16 patients included in this study varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for GR-200 measurements. The ESDs obtained by putting the two types of TLDs at the surface of Rando phantom are in close agreement. Conclusion: According to the results, the GR200 has greater sensitivity than the TLD-100. PMID:25599058

Investigation of the Entrance Surface Dose and Dose to Different Organs in Lumbar Spine Imaging

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Sina S

2014-12-01

Full Text Available Background: Dose assessment using proper dosimeters is especially important in radiation protection optimization and imaging justification in diagnostic radiology. Objective: The aim of this study is to obtain the Entrance Skin Dose (ESD of patients undergoing lumbar spine imaging using two thermoluminescence dosimeters TLD-100 (LiF: Mg, Ti and GR-200 (LiF: Mg, Cu, P and also to obtain the absorbed dose to different organs in lumbar spine imaging with several views. Methods: To measure the ESD values of the patients undergoing lumbar spine imaging, the two TLD types were put on their skin surface. The ESD values for different views of lumbar spine imaging were also measured by putting the TLDs at the surface of the Rando phantom. Several TLD chips were inserted inside different organs of Rando phantom to measure the absorbed dose to different organs in lumbar spine imaging. Results: The results indicate that there is a close agreement between the results of the two dosimeters. Based on the results of this experiment, the ESD dose of the 16 patients included in this study varied between 2.71 mGy and 26.29 mGy with the average of 11.89 mGy for TLD-100, and between 2.55 mGy and 27.41 mGy with the average of 12.32 mGy for GR-200 measurements. The ESDs obtained by putting the two types of TLDs at the surface of Rando phantom are in close agreement. Conclusion: According to the results, the GR200 has greater sensitivity than the TLD-100.

Assessment of Patients’ Entrance Skin Dose from Diagnostic X-ray Examinations at Public Hospitals of Akwa Ibom State, Nigeria

Directory of Open Access Journals (Sweden)

Esen Nsikan U

2015-07-01

Full Text Available Introduction High doses of ionizing radiation can lead to adverse health outcomes such as cancer induction in humans. Although the consequences are less evident at very low radiation doses, the associated risks are of societal importance. This study aimed at assessing entrance skin doses (ESDs in patients undergoing selected diagnostic X-ray examinations at public hospitals of Akwa Ibom State, Nigeria. Materials and Methods In total, six examinations were performed on 720 patients in this study.   CALDose_X5 software program was used in estimating ESDs based on patients’ information and technical exposure parameters. Results The estimated ESDs ranged from 0.59 to 0.61 mGy for PA and RLAT projections of the thorax, respectively. ESDs for the AP and RLAT projections of the cranium were 1.65 and 1.48 mGy, respectively. Also, ESD values for the AP view of the abdomen and pelvis were 1.89 and 1.88 mGy, respectively. The mean effective dose was within the range of 0.021-0.075 mGy for the thorax (mean= 0.037, 0.008-0.045 mGy for the cranium (mean= 0.016, 0.215-0.225 mGy for the abdomen (mean= 0.219 and 0.101-0.119 mGy for the pelvis (mean= 0.112. Conclusion The obtained results were comparable to the international reference dose levels, except for the PA projection of the thorax. Therefore, quality assurance programs are required in diagnostic X-ray units of Nigeria hospitals. The obtained findings add to the available data and can help authorities establish reference dose levels for diagnostic radiography in Nigeria.

An assessment of methods for monitoring entrance surface dose in fluoroscopically guided interventional procedures

International Nuclear Information System (INIS)

Waite, J.C.; Fitzgerald, M.

2001-01-01

In the light of a growing awareness of the risks of inducing skin injuries as a consequence of fluoroscopically guided interventional procedures (FGIPs), this paper compares three methods of monitoring entrance surface dose (ESD). It also reports measurements of ESDs made during the period August 1998 to June 1999 on 137 patients undergoing cardiac, neurological and general FGIPs. Although the sample is small, the results reinforce the need for routine assessments to be made of ESDs in FGIPs. At present, the most reliable and accurate form of ESD measurement would seem to be arrays of TLDs. However, transducer based methods, although likely to be less accurate, have considerable advantages in relation to a continuous monitoring programme. It is also suggested that there may be the potential locally for threshold dose area product (DAP) values to be set for specific procedures. These could be used to provide early warning of the potential for skin injuries. (author)

Correlation of patient maximum skin doses in cardiac procedures with various dose indicators

International Nuclear Information System (INIS)

Domienik, J.; Papierz, S.; Jankowski, J.; Peruga, J.Z.; Werduch, A.; Religa, W.

2008-01-01

In most countries of European Union, legislation requires the determination of the total skin dose received by patients during interventional procedures in order to prevent deterministic damages. Various dose indicators like dose-area product (DAP), cumulative dose (CD) and entrance dose at the patient plane (EFD) are used for patient dosimetry purposes in clinical practice. This study aimed at relating those dose indicators with doses ascribed to the most irradiated areas of the patient skin usually expressed in terms of local maximal skin dose (MSD). The study was performed in two different facilities for two most common cardiac procedures coronary angiography (CA) and percutaneous coronary interventions (PCI). For CA procedures, the registered values of fluoroscopy time, total DAP and MSD were in the range (0.7-27.3) min, (16-317) Gy cm 2 and (43-1507) mGy, respectively, and for interventions, accordingly (2.1-43.6) min, (17-425) Gy cm 2 , (71-1555) mGy. Moreover, for CA procedures, CD and EFD were in the ranges (295-4689) mGy and (121-1768) mGy and for PCI (267-6524) mGy and (68-2279) mGy, respectively. No general and satisfactory correlation was found for safe estimation of MSD. However, results show that the best dose indicator which might serve for rough, preliminary estimation is DAP value. In the study, the appropriate trigger levels were proposed for both facilities. (authors)

In vitro modeling of skin dose and monitoring of DCA following therapeutic intervention

International Nuclear Information System (INIS)

Balajee, Adayabalam S.; Dainiak, Nicholas

2016-01-01

Human skin is the largest organ of the body accounting for approximately 16% of the total bodyweight. Skin is readily exposed to ionizing radiation during either accidental or intentional exposure such as radiotherapy or other medical procedures because it constitutes the interface between environment and internal organs. Estimation of accurate entrance skin dose and maximum absorbed dose (MAD) is crucial to prevent serious skin injuries. Cutaneous Radiation Syndrome (CRS) is defined by a number of pathological changes manifested in the skin and severity of these changes depend on Liner Energy Transfer (LET), dose, dose-rate, geometry of exposure and volume of body part exposed. In most of the radiological accident scenarios, reconstructive dosimetry in the skin has been performed using physical (thermoluminescence and optical stimulated luminescence), biological (cytogenetics) and computational methods/models to manage radiation exposed victims.Results of the cytogenetic testing performed at the CBL on a few patients will be discussed to illustrate the potential use of DCA and other cytogenetic techniques such as micronuclei and multicolor FISH in monitoring the health of radiotherapy patients

Skin dose in longitudinal and transverse linac-MRIs using Monte Carlo and realistic 3D MRI field models.

Science.gov (United States)

Keyvanloo, A; Burke, B; Warkentin, B; Tadic, T; Rathee, S; Kirkby, C; Santos, D M; Fallone, B G

2012-10-01

The magnetic fields of linac-MR systems modify the path of contaminant electrons in photon beams, which alters patient skin dose. To accurately quantify the magnitude of changes in skin dose, the authors use Monte Carlo calculations that incorporate realistic 3D magnetic field models of longitudinal and transverse linac-MR systems. Finite element method (FEM) is used to generate complete 3D magnetic field maps for 0.56 T longitudinal and transverse linac-MR magnet assemblies, as well as for representative 0.5 and 1.0 T Helmholtz MRI systems. EGSnrc simulations implementing these 3D magnetic fields are performed. The geometry for the BEAMnrc simulations incorporates the Varian 600C 6 MV linac, magnet poles, the yoke, and the magnetic shields of the linac-MRIs. Resulting phase-space files are used to calculate the central axis percent depth-doses in a water phantom and 2D skin dose distributions for 70 μm entrance and exit layers using DOSXYZnrc. For comparison, skin doses are also calculated in the absence of magnetic field, and using a 1D magnetic field with an unrealistically large fringe field. The effects of photon field size, air gap (longitudinal configuration), and angle of obliquity (transverse configuration) are also investigated. Realistic modeling of the 3D magnetic fields shows that fringe fields decay rapidly and have a very small magnitude at the linac head. As a result, longitudinal linac-MR systems mostly confine contaminant electrons that are generated in the air gap and have an insignificant effect on electrons produced further upstream. The increase in the skin dose for the longitudinal configuration compared to the zero B-field case varies from ∼1% to ∼14% for air gaps of 5-31 cm, respectively. (All dose changes are reported as a % of D(max).) The increase is also field-size dependent, ranging from ∼3% at 20 × 20 cm(2) to ∼11% at 5 × 5 cm(2). The small changes in skin dose are in contrast to significant increases that are

Analysis of entrance skin radiation dose in mammography equipment in Rio Grande do Sul state (Ijui municipality and surroundings) and Rio de Janeiro (metropolitan area)

International Nuclear Information System (INIS)

Araujo, Geovane Silva; Padilha Filho, Lucas Gomes; Sousa, Carlos Henrique Simoes de; Feldmann, Gerson; Albrecht, Marcos R.A.; Souza, Sergio Augusto Lopes de

2016-01-01

Mammography is the technique widely used to the early detection of breast cancer, despite of not being a consensus the ideal age to initiate the radiologic examinations, it is recommended that women with the age of forty realize the examinations periodically. With the objective to analyze the entrance skin dose (ESD) in different mammography equipment, Were analyzed in the Estate of Rio Grande do Sul (Ijui City and neighborhoods) and in Rio de Janeiro (metropolitan area) 24 mammography equipment. Among them included in the study, just one presented ESD higher than the established limit of ANVISA. It was observed in the mammography equipment of Ijui and neighborhoods high levels of mAs to achieve the values of ESD next to the limit. (author)

Clinical use of carbon-loaded thermoluminescent dosimeters for skin dose determination

International Nuclear Information System (INIS)

Ostwald, Patricia M.; Kron, Tomas; Hamilton, Christopher S.; Denham, James W.

1995-01-01

Purpose: Carbon-loaded thermoluminescent dosimeters (TLDs) are designed for surface/skin dose measurements. Following 4 years in clinical use at the Mater Hospital, the accuracy and clinical usefulness of the carbon-loaded TLDs was assessed. Methods and Materials: Teflon-based carbon-loaded lithium fluoride (LiF) disks with a diameter of 13 mm were used in the present study. The TLDs were compared with ion chamber readings and TLD extrapolation to determine the effective depth of the TLD measurement. In vivo measurements were made on patients receiving open-field treatments to the chest, abdomen, and groin. Skin entry dose or entry and exit dose were assessed in comparison with doses estimated from phantom measurements. Results: The effective depth of measurement in a 6 MV therapeutic x-ray beam was found to be about 0.10 mm using TLD extrapolation as a comparison. Entrance surface dose measurements made on a solid water phantom agreed well with ion chamber and TLD extrapolation measurements, and black TLDs provide a more accurate exit dose than the other methods. Under clinical conditions, the black TLDs have an accuracy of ± 5% (± 2 SD). The dose predicted from black TLD readings correlate with observed skin reactions as assessed with reflectance spectroscopy. Conclusion: In vivo dosimetry with carbon-loaded TLDs proved to be a useful tool in assessing the dose delivered to the basal cell layer in the skin of patients undergoing radiotherapy

Entrance surface dose measurements in pediatric radiological examinations

International Nuclear Information System (INIS)

Ribeiro, L.A.; Yoshimura, E.M.

2008-01-01

A survey of pediatric radiological examinations was carried out in a reference pediatric hospital of the city of Sao Paulo, in order to investigate the doses to children undergoing conventional X-ray examinations. The results showed that the majority of pediatric patients are below 4 years, and that about 80% of the examinations correspond to chest projections. Doses to typical radiological examinations were measured in vivo with thermoluminescent dosimeters (LiF: Mg, Ti and LiF: Mg, Cu, P) attached to the skin of the children to determine entrance surface dose (ESD). Also homogeneous phantoms were used to obtain ESD to younger children, because the technique uses a so small kVp that the dosimeters would produce an artifact image in the patient radiograph. Four kinds of pediatric examinations were investigated: three conventional examinations (chest, skull and abdomen) and a fluoroscopic procedure (barium swallow). Relevant information about kVp and mAs values used in the examinations was collected, and we discuss how these parameters can affect the ESD. The ESD values measured in this work are compared to reference levels published by the European Commission for pediatric patients. The results obtained (third-quartile of the ESD distribution) for chest AP examinations in three age groups were: 0.056 mGy (2-4 years old); 0.068 mGy (5-9 years old); 0.069 mGy (10-15 years old). All of them are below the European reference level (0.100 mGy). ESD values measured to the older age group in skull and abdomen AP radiographs (mean values 3.44 and 1.20 mGy, respectively) are above the European reference levels (1.5 mGy to skull and 1.0 mGy to abdomen). ESD values measured in the barium swallow examination reached 10 mGy in skin regions corresponding to thyroid and esophagus. It was noticed during this survey that some technicians use, improperly, X-ray fluoroscopy in conventional examinations to help them in positioning the patient. The results presented here are a

Evaluation of six TPS algorithms in computing entrance and exit doses

Science.gov (United States)

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

Evaluations of gonad and fetal doses for diagnostic radiology.

Science.gov (United States)

Tung, C J; Tsai, H Y

1999-07-01

A national survey of patient doses for diagnostic radiology was planned in the Republic of China. We performed a pilot study for this survey to develop a protocol of the dose assessments. Entrance skin doses and organ (including ovary, testicle and uterus) doses were measured by thermoluminescent dosimeters and calculated by means of Monte Carlo simulations for several diagnostic procedures. We derived a formula and used the RadComp software for the computation of entrance skin doses. This formula involves several factors, such as kVp, mAs, the focus-to-skin-distance and aluminum filtration. RadComp software was applied to obtain free-air entrance exposures which were converted to entrance skin doses by considering the backscattering radiation from the body. Organ doses were measured using a RANDO phantom and calculated using a mathematical phantom for several diagnostic examinations. Genetically significant doses were calculated from ovary and testicle doses for the evaluation of hereditary effects. Embryo/fetal doses were determined from the uterine doses by considering the increase in uterus size with gestational age. We found that the patient doses studied in this work were all below the reference doses recommended by the National Radiological Protection Board of the U.K.

Dosimetry of Occupationally Exposed Persons in Diagnostic and Interventional Arteriography. Part 1: Assessment of Entrance Doses

International Nuclear Information System (INIS)

Kicken, P.J.H.; Kemerink, G.J.; Engelshoven, J.M.A. van

1999-01-01

The purpose of this study was to obtain representative quantitative information on exposure conditions and entrance doses of occupationally exposed persons (workers) in diagnostic and interventional arteriography. In a study in three hospitals all parameters of the X ray systems that are related to the exposure of workers were quantified with an automatic data acquisition system. Using LiF thermoluminescence dosemeters, entrance doses to workers were measured at the forehead, neck, thorax, abdomen, upper arms, hands and lower legs. Measurements were performed during 353 procedures, and it was found that exposure of workers was predominantly caused by fluoroscopy. Averaged over all procedures in the annual workload, entrance doses were below 120 μGy when an undercouch X ray tube and a mechanical contrast injector were used. For an overcouch tube the doses were higher. It is concluded that entrance doses are low, and that legally established annual dose limits are un-likely to be exceeded. (author)

A beta skin dose monitor using an Eberline RO-2 ion chamber

International Nuclear Information System (INIS)

Jester, W.A.; Levine, S.H.; Lin, T.J.; Hock, R.

1994-01-01

The authors have developed a portable beta skin dose monitor that uses an Eberline RO-2trademark ion chamber. The development was based, in part, upon the previous development of a beta skin dose monitor employing silicon detectors. In this current work, the two entrance windows of the RO-2 were replaced by windows having a total mass thickness of 1.74 mg/cm 2 . A two section source-detector holder was constructed. One section fastens to the RO-2 and holds the detector at the right position to determine the contact skin dose from beta emitters located on surfaces. A second section attaches to the first, and provides fixed counting geometry for radioactive samples such as hot particles. The first section also contains a slide mechanism that allows the placement of absorbers of zero (0), 8.38, and 1000 mg/cm 2 between the detector window and the beta source. The detector response to these absorbers allows for the determination of beta skin dose. The system was modeled using a Monte Carlo beta attenuation code computing the beta skin dose to RO-2 detector response as a function of absorber thickness, average beta energy, source diameter and source position. Using the RO-2 reading from each of the three absorber configurations allows the calculation of beta skin dose and the average beta energy. The results of these calculations were confirmed through the use of three massless radioactive beta sources, traceable to the National Institute of Standards and Technology, and several utility-supplied hot particles having well-established contact skin doses. An extrapolation chamber was also used to confirm the results obtained from this monitor. This system is now use at the Pennsylvania Power and Light (PP and L) Company, the project sponsor. ((orig.))

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)

Skin entrance dose with and without lead apron in digital panoramic radiography for selected sensitive body regions.

Science.gov (United States)

Schulze, Ralf Kurt Willy; Cremers, Catrin; Karle, Heiko; de Las Heras Gala, Hugo

2017-05-01

The aim of this study was to compare the dose at skin level at five significant anatomical regions for panoramic radiography devices with and without lead apron by means of a highly sensitive dosimeter. A female RANDO-phantom was exposed in five different digital panoramic radiography systems, and the dose at skin level was assessed tenfold for each measurement region by means of a highly sensitive solid-state-dosimeter. The five measurement regions selected were the thyroid, both female breasts, the gonads, and a central region in the back of the phantom. For each panoramic machine, the measurements were performed in two modes: with and without a commercial lead apron specifically designed for panoramic radiography. Reproducibility of the measurements was expressed by absolute differences and the coefficient of variation. Values between shielded and unshielded doses were pooled for each region and compared by means of the paired Wilcoxon tests (p ≤ 0.05). Reproducibility as represented by the mean CV was 22 ± 52 % (median 2.3 %) with larger variations for small dose values. Doses at skin level ranged between 0.00 μGy at the gonads and 85.39 μGy at the unshielded thyroid (mean ± SD 15 ± 24 μGy). Except for the gonads, the dose in all the other regions was significantly lower (p < 0.001) when a lead apron was applied. Unshielded doses were between 1.02-fold (thyroid) and 112-fold (at the right breast) higher than those with lead apron shielding (mean: 14-fold ± 18-fold). Although the doses were entirely very low, we observed a significant increase in dose in the radiation-sensitive female breast region when no lead apron was used. Future discussions on shielding requirements for panoramic radiography should focus on these differences in the light of the linear non-threshold (LNT) theory which is generally adopted in medical imaging.

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)

Entrance radiation doses during paediatric cardiac catheterizations performed for diagnosis or the treatment of congenital heart disease

International Nuclear Information System (INIS)

Papadopoulou, D.; Yakoumakis, Em; Sandilos, P.; Thanopoulos, V.; Makri, Tr; Gialousis, G.; Houndas, D.; Yakoumakis, N.; Georgiou, Ev

2005-01-01

The purpose of this study was to estimate the radiation exposure of children, during cardiac catheterizations for the diagnosis or treatment of congenital heart disease. Radiation doses were estimated for 45 children aged from 1 d to 13 y old. Thermoluminescent dosemeters (TLDs) were used to estimate the posterior entrance dose (D P ), the lateral entrance dose (D LAT ), the thyroid dose and the gonads dose. A dose-area product (DAP) meter was also attached externally to the tube of the angiographic system and gave a direct value in mGy cm 2 for each procedure. Posterior and lateral entrance dose values during cardiac catheterizations ranged from 1 to 197 mGy and from 1.1 to 250.3 mGy, respectively. Radiation exposure to the thyroid and the gonads ranged from 0.3 to 8.4 mGy to 0.1 and 0.7 mGy, respectively. Finally, the DAP meter values ranged between 360 and 33,200 mGy cm 2 . Radiation doses measured in this study are comparable with those reported to previous studies. Moreover, strong correlation was found between the DAP values and the entrance radiation dose measured with TLDs. (authors)

Characteristic evaluation of a real-time silicon dosimeter and measurement of entrance surface dose at radiography

International Nuclear Information System (INIS)

Fujibuchi, Toshiou; Kato, Hideyuki; Hashimoto, Masatoshi; Abe, Yukinao; Kikawa, Takashi

2006-01-01

It is important to grasp how much radiation exposure has occurred through radiation diagnosis, in respect to patient explanations and radiation protection. In this examination, we used a patient skin dosimeter (PSD) that measures entrance surface dose (ESD) in real time using a fluoroscopy procedure. The PSD has the ability to display results beginning at 1 μGy. We focused our attention on the X-ray detectability of the PSD, and performed a representative evaluation with the X-ray equipment. We measured ESD under various radiographic parameters at our facility. Although the measurements were dependent on energy, we were able to measure ESD to within an accuracy of about a 5% error by putting a calibration value on energy. The PSD can measure ESD easily without requiring preparation. It is important to be aware of the exposure dose to the radiation staff, and the PSD is a very effective radiation dose-measuring tool when daily business is active. (author)

Fundamental study on the characteristics of a radiophotoluminescence glass dosemeter with no energy compensation filter for measuring patient entrance doses in cardiac interventional procedures

International Nuclear Information System (INIS)

Kato, Mamoru; Chida, Koichi; Moritake, Takashi; Koguchi, Yasuhiro; Sato, Tadaya; Kadowaki, Ken; Oosaka, Hajime; Tosa, Tetsuo

2014-01-01

Cardiac interventional procedures have been increasing year by year. However, radiation skin injuries have been still reported. There is a necessity to measure the patient entrance skin dose (ESD), but an accurate dose measurement method has not been established. To measure the ESD, a lot of radiophotoluminescence dosemeters (RPLDs) provide an accurate measurement of the direct actual ESD at the points they are arrayed. The purpose of this study was to examine the characteristics of RPLD to measure the ESD. As a result, X-ray permeable RPLD (with no tin filter) did not interfere with the percutaneous coronary intervention procedure. The RPLD also had good fundamental performance characteristics. Although the RPLD had a little energy dependence, it showed excellent dose and dose-rate linearity, and good angular dependence. In conclusion, by calibrating the energy dependence, RPLDs are useful dosemeter to measure the ESD in cardiac intervention. (authors)

Comparative study on skin dose measurement using MOSFET and TLD for pediatric patients with acute lymphatic leukemia.

Science.gov (United States)

Al-Mohammed, Huda I; Mahyoub, Fareed H; Moftah, Belal A

2010-07-01

The object of this study was to compare the difference of skin dose measured in patients with acute lymphatic leukemia (ALL) treated with total body irradiation (TBI) using metal oxide semiconductor field-effect transistors (mobile MOSFET dose verification system (TN-RD-70-W) and thermoluminescent dosimeters (TLD-100 chips, Harshaw/ Bicron, OH, USA). Because TLD has been the most-commonly used technique in the skin dose measurement of TBI, the aim of the present study is to prove the benefit of using the mobile MOSFET (metal oxide semiconductor field effect transistor) dosimeter, for entrance dose measurements during the total body irradiation (TBI) over thermoluminescent dosimeters (TLD). The measurements involved 10 pediatric patients ages between 3 and 14 years. Thermoluminescent dosimeters and MOSFET dosimetry were performed at 9 different anatomic sites on each patient. The present results show there is a variation between skin dose measured with MOSFET and TLD in all patients, and for every anatomic site selected, there is no significant difference in the dose delivered using MOSFET as compared to the prescribed dose. However, there is a significant difference for every anatomic site using TLD compared with either the prescribed dose or MOSFET. The results indicate that the dosimeter measurements using the MOSFET gave precise measurements of prescribed dose. However, TLD measurement showed significant increased skin dose of cGy as compared to either prescribed dose or MOSFET group. MOSFET dosimeters provide superior dose accuracy for skin dose measurement in TBI as compared with TLD.

Fundamental study on the characteristics of a radiophotoluminescence glass dosemeter with no energy compensation filter for measuring patient entrance doses in cardiac interventional procedures.

Science.gov (United States)

Kato, Mamoru; Chida, Koichi; Moritake, Takashi; Koguchi, Yasuhiro; Sato, Tadaya; Oosaka, Hajime; Tosa, Tetsuo; Kadowaki, Ken

2014-12-01

Cardiac interventional procedures have been increasing year by year. However, radiation skin injuries have been still reported. There is a necessity to measure the patient entrance skin dose (ESD), but an accurate dose measurement method has not been established. To measure the ESD, a lot of radiophotoluminescence dosemeters (RPLDs) provide an accurate measurement of the direct actual ESD at the points they are arrayed. The purpose of this study was to examine the characteristics of RPLD to measure the ESD. As a result, X-ray permeable RPLD (with no tin filter) did not interfere with the percutaneous coronary intervention procedure. The RPLD also had good fundamental performance characteristics. Although the RPLD had a little energy dependence, it showed excellent dose and dose-rate linearity, and good angular dependence. In conclusion, by calibrating the energy dependence, RPLDs are useful dosemeter to measure the ESD in cardiac intervention. © The Author 2013. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

SU-G-JeP2-09: Minimal Skin Dose Increase in Longitudinal Rotating Biplanar Linac-MR Systems: Examination of Radiation Energy and Flattening Filter Design

Energy Technology Data Exchange (ETDEWEB)

Fallone, B; Keyvanloo, A; Burke, B; St Aubin, J; Baillie, D; Wachowicz, K; Warkentin, B; Steciw, S [Cross Cancer Institute, Edmonton, AB (Canada)

2016-06-15

Purpose: To quantify increase in entrance skin-dose due to magnetic fields of the Alberta longitudinal linac-MR by examining the effect of radiation energy and flattening filter, using Monte Carlo calculations and accurate 3-D models of the magnetic field. Methods: The 3-D magnetic fields generated by the bi-planar Linac-MR are calculated with FEM using Opera-3D. BEAMnrc simulates the particle phase-space in the presence of the rapidly decaying fringe field of 0.5T MRI assembled with a Varian 600C linac with an isocentre distance of 130 cm for 6 MV and 10 MV beams. Skin doses are calculated at an average depth of 70 µm using DOSXYZnrc with varying SSDs and field sizes. Furthermore, flattening filters are reshaped to compensate for the significant drop in dose rate due to increased SAD of 130 cm and skin-doses are evaluated. Results: The confinement effect of the MRI fringe field on the contaminant electrons is minimal. For SSDs of 100 – 120 cm the increase in skin dose is ∼6% – 19% and ∼1% – 9% for the 6 and 10 MV beams, respectively. For 6MV, skin dose increases from ∼10.5% to 1.5%. for field-size increases of 5×5 cm2 to 20×20 cm2. For 10 MV, skin dose increases by ∼6% for a 5×5 cm2 field, and decreases by ∼1.5% for a 20×20 cm2 field. The reshaped flattening filter increases the dose rate from 355 MU/min to 529 MU/min (6 MV) or 604 MU/min (10 MV), while the skin-dose increases by only an additional ∼2.6% (all percent increases in skin dose are relative to Dmax). Conclusion: There is minimal increase in the entrance skin dose and minimal/no decrease in the dose rate of the Alberta longitudinal linac-MR system. There is even lower skin-dose increase at 10 MV. Funding: Alberta Innovates - Health Solutions (AIHS) Conflict of Interest: Fallone is a co-founder and CEO of MagnetTx Oncology Solutions (under discussions to license Alberta bi-planar linac MR for commercialization)

Preliminary study of using imaging plates to map skin dose of patients in interventional radiology procedures

International Nuclear Information System (INIS)

Ohuchi, H.; Satoh, T.; Eguchi, Y.; Mori, K.

2005-01-01

A method using europium-doped BaFBr imaging plates (IPs) has been studied for mapping entrance skin doses during interventional radiology (IR); the mapping is useful for detecting overlap between irradiation fields and determining the most exposed skin areas. IPs, which are two-dimensional radiation sensors made of photostimulated luminescence materials, have a linear dose response up to ∼100 Gy, can accurately measure doses from 1 μGy to 10 Gy and can be used repeatedly. Because the energy dependence of IPs is rather high, the IPs were characterised in this study and a sensitivity variation of ∼13% was observed for effective energies of 32.7 to 44.7 keV, which are used in IR procedures. Simulation of actual interventional cardiology procedures showed that the variation of sensitivity was within 5%, meaning that IPs are practical for measuring skin doses during IR. Moreover, the patient data can be stored online and easily called up when IR procedures must be repeated, helping to prevent radiation injuries. (authors)

A comparison of the suitability of patient dosimetry methods for establishing diagnostic dose reference levels and optimisation strategies

International Nuclear Information System (INIS)

Gfirtner, Hans; Moores, B. Michael; Stieve, Friedrich E.

2008-01-01

For 50 adult patients referred for chest radiography, air kerma at the diaphragm KD, dose area product and entrance skin dose were measured. The air kerma at the diaphragm and the dose area product were determined using Diamentor M4KDK(PTW) which allows measuring air kerma and dose area product simultaneously. For the measurement of entrance skin dose TLDs are used. A 50% variation in dose, incident dose as well as entrance skin dose, was registered for the same patient thickness. The recommendation of ICRP to perform the measurements for DRLs at 'representative patients' and that of the CEC to use 'standard-sized patients' seem to make little sense in the case of chest radiography. It could be demonstrated, that the dose area product is the least appropriate dose quantity for patient measurements and to define dose reference levels. For some radiological examinations like chest, pelvis and lumbar spine the dose area product is even sex dependent. Incident dose and entrance surface dose are of equal quality for patient dose measurements in diagnostic radiography. (author)

Analysis on the entrance surface dose and contrast medium dose at computed tomography and angiography in cardiovascular examination

Energy Technology Data Exchange (ETDEWEB)

Seo, Young Hyun [Dept. of Cardiovascular Center, Yeocheon Jeonnam Hospital, Yeosu (Korea, Republic of); Han, Jae Bok; Choi, Nam Gil; Song, Jong Nam [Dept. of Radiological Science, Dongshin University, Naju (Korea, Republic of)

2016-12-15

This study aimed to identify dose reduction measures by retrospectively analyzing the entrance surface dose at computed tomography and angiography in cardiovascular examination and to contribute the patients with renal impairmend and a high probability of side effects to determine the inspection's direction by measuring the contrast usages actually to active actions for the dose by actually measuring the contrast medium dose. The CTDIvol value and air kerma value, which are the entrance surface doses of the two examinations, and the contrast medium dose depending on the number of slides were compared and analyzed. This study was conducted in 21 subjects (11 males; 10 females) who underwent Cardiac Computed Tomographic Angiography (CCTA) and Coronary Angiography (CAG) in this hospital during the period from May 2014 to May 2016. The subject's age was 48-85 years old (mean 65±10 years old), and the weight was 37.6~83.3 kg (mean 63±6 kg). Dose reduction could be expected in the cardiovascular examination using CCTA rather than in the examination using CAG. In terms of contrast medium dose, CAG used a smaller dose than CCTA. In particular, as the number of slides increases at CAG, the contrast medium dose increases. Therefore, in order to reduce the contrast medium dose, the number of slides suitable for the scan range must be selected.

Measurement and monitoring of entrance exposure dose rate in X-ray image intensifier television with dose rate control

Energy Technology Data Exchange (ETDEWEB)

Klein, J [Bezirkskrankenhaus Brandenburg (German Democratic Republic)

1981-03-01

For X-ray image intensifier television operation very low entrance dose rates (about 5.2 nA/kg) are stated and demanded, respectively. These required values are often manifold exceeded in practice so that a check seems to be necessary. It is shown and proved how these measurements can be performed with simple, generally available means of measurement in the radiological practice. For ZnCdS-image intensifiers should be considered that about 13 nA/kg for the large entrance size are not to be exceeded; for the CsI type lower values (factor 1.5) are practicable because of the twofold quantum absorption efficiency. Furthermore, some tests for a semiquantitative function check of the automatic dose rate control are proposed.

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

International Nuclear Information System (INIS)

Rana, V. K.; Rudin, S.; Bednarek, D. R.

2016-01-01

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be

A tracking system to calculate patient skin dose in real-time during neurointerventional procedures using a biplane x-ray imaging system

Energy Technology Data Exchange (ETDEWEB)

Rana, V. K., E-mail: vkrana@buffalo.edu [Toshiba Stroke and Vascular Research Center, Department of Neurosurgery, State University of New York at Buffalo, Buffalo, New York 14203 (United States); Rudin, S., E-mail: srudin@buffalo.edu; Bednarek, D. R., E-mail: bednarek@buffalo.edu [Toshiba Stroke and Vascular Research Center, Departments of Radiology, Neurosurgery, Physiology and Biophysics, State University of New York at Buffalo, Buffalo, New York 14203 (United States)

2016-09-15

Purpose: Neurovascular interventional procedures using biplane fluoroscopic imaging systems can lead to increased risk of radiation-induced skin injuries. The authors developed a biplane dose tracking system (Biplane-DTS) to calculate the cumulative skin dose distribution from the frontal and lateral x-ray tubes and display it in real-time as a color-coded map on a 3D graphic of the patient for immediate feedback to the physician. The agreement of the calculated values with the dose measured on phantoms was evaluated. Methods: The Biplane-DTS consists of multiple components including 3D graphic models of the imaging system and patient, an interactive graphical user interface, a data acquisition module to collect geometry and exposure parameters, the computer graphics processing unit, and functions for determining which parts of the patient graphic skin surface are within the beam and for calculating dose. The dose is calculated to individual points on the patient graphic using premeasured calibration files of entrance skin dose per mAs including backscatter; corrections are applied for field area, distance from the focal spot and patient table and pad attenuation when appropriate. The agreement of the calculated patient skin dose and its spatial distribution with measured values was evaluated in 2D and 3D for simulated procedure conditions using a PMMA block phantom and an SK-150 head phantom, respectively. Dose values calculated by the Biplane-DTS were compared to the measurements made on the phantom surface with radiochromic film and a calibrated ionization chamber, which was also used to calibrate the DTS. The agreement with measurements was specifically evaluated with variation in kVp, gantry angle, and field size. Results: The dose tracking system that was developed is able to acquire data from the two x-ray gantries on a biplane imaging system and calculate the skin dose for each exposure pulse to those vertices of a patient graphic that are determined to be

External contamination and skin dose. From ICRP and regulations to skin dose evaluation in practice

International Nuclear Information System (INIS)

Le Coulteulx, I.; Apretna, D.; Beaugerie, M.; Fenolland, J.; Frey, R.; Gonin, M.; Landry, B.; Laporte, E.; Le Guen, B.; Leval, D.

2006-01-01

Dose limitation to the skin is an objective of radiation protection. Our aim is to propose in case of skin contamination in EDF NPPs a simply, quickly and reproducible procedure for evaluating skin dose. French regulation admit an annual limit for skin dose over one square centimeter equal to 500 mSv. ICRP Publication 26 and 60 recommend that dose assessment be performed only if skin dose might be equal to or more than 50 mSv at basal cells. To respect this recommendation, an alert value (A) must be determined. This value is the lowest value of measurement from which dose assessment has to be made, based on the hypothesis that uninterrupted work time in controlled area is no more than four hours. This alert value (A) has been established for three external detection equipments, and for the ten radionuclides commonly detected. In case of external contamination, a first measurement is performed. If the value exceeds value (A), other measurements are instituted because skin dose evaluation needs to know other parameters as: - the radioactivity of the most contaminated square centimeter of the skin, - the identity of the radionuclides and their relative proportion. At the same time, we have to evaluate the length of the exposure. At last, we use different compiled results in a program developed from excel software which allow to calculate automatically the skin dose. This work has allowed us to publish an occupational health guideline about the assessment of skin dose in case of external contamination in EDF NPPs and to create an information booklet for workers. The authors propose to examine used methodology and to demonstrate the software. (authors)

Methods for implementation of in vivo dosimetry (entrance dose) using thermoluminescent dosimeters during radiotherapy treatment with photon beam

International Nuclear Information System (INIS)

Barsanelli, Cristiane

2006-01-01

Selection, calibration procedure to convert TLD signal into absorbed dose and physical characteristics at the thermoluminescent dosimeters, as well as the determination of correction factors and the methodology to determine expected entrance dose, are described in this work. Practical aspects and the utility of entrance dose measures with thermoluminescent dosimeters were investigated, as well as the exactness and the reproducibility of the daily dose release. The entrance dose measures were performed in five patients with diagnosis of breast cancer treated with a 6 MV photon beam. The measured dose and the expected dose values agreed in ± 5%, due to excellent treatment equipment stability, to automatic verification system and the good exactness in the daily treatment adjustment. Good precision can be achieved when the correction factors for each parameter of influence in the dosimeter response are carefully determined and applied to convert the thermoluminescent signal into absorbed dose. The study demonstrates the viability of thermoluminescent dosimeters use for in vivo dosimetry and its utility as part of a quality assurance program in a radiation therapy service. (author)

Development of a external exposure computational model for studying of input dose in skin for radiographs of thorax and vertebral column

International Nuclear Information System (INIS)

Muniz, Bianca C.; Menezes, Claudio J.M.; Vieira, Jose W.

2014-01-01

The dosimetric measurements do not always happen directly in the human body. Therefore, these assessments can be performed using anthropomorphic models (phantoms) evidencing models computational exposure (MCE) using techniques of Monte Carlo Method for virtual simulations. These processing techniques coupled with more powerful and affordable computers make the Monte Carlo method one of the tools most used worldwide in radiation transport area. In this work, the Monte Carlo EGS4 program was used to develop a computer model of external exposure to study the entrance skin dose for chest and column X-radiography and, aiming to optimize these practices by reducing doses to patients, professionals involved and the general public. The results obtained experimentally with the electrometer Radcal, model 9015, associated with the ionization chamber for radiology model 10X5-6, showed that the proposed computational model can be used in quality assurance programs in radiodiagnostic, evaluating the entrance skin dose when varying parameters of the radiation beam such as kilo voltage peak (kVp), current-time product (mAs), total filtration and distance surface source (DFS), optimizing the practices in radiodiagnostic and meeting the current regulation

Development of mathematical model for estimation of entrance surface dose in mammography

International Nuclear Information System (INIS)

Abdelgani, Yassir Mohammed Tahir

2013-05-01

Computer simulation is a convenient and frequently used tool in the study of x-ray mammography, for the design of novel detector systems, the evaluation of dose deposition, x-ray technique optimization, and other applications. An important component in the simulation process is the accurate computer generation of x-ray spectra. A computer model for the generation of x-ray spectra in the mammographic energy rang from 18 keV to 40 ke V has been developed by Boone et al. Due to the lack of QC and dose measurement tools, in addition to unavailability of medical physics, a mathematical tool was developed for estimation of patient exposure and entrance dose. The proposed model require no assumptions concerning the physics of x-ray production in an x-ray tube, but rather makes use of x-ray spectra recently measured experimentally by John M Boone (Department of Radiology, University of California). Using experimental dose measurements for specific tube voltage and tube current the generated x-ray spectra were calibrated. The spectrum calibration factors show a tube voltage dependency. From the calibrated x-ray spectrum, the exposure and entrance dose were estimated for different k Vp and m A. Results show good agreement between the measured and estimated values for tube voltage between 18 to 45 k Vp with a good correlation of nearly 1 and equal slope. The maximum estimated different between the measured and the simulated dose is approximately equal to 0.07%.(Author)

Paediatric doses from diagnostic radiology in Victoria

International Nuclear Information System (INIS)

Boal, T.J.; Cardillo, I.; Einsiedel, P.F.

1998-01-01

This study examines doses to paediatric patients from diagnostic radiology. Measurements were made at 29 hospitals and private radiology practices in the state of Victoria. Entrance skin doses in air were measured for the exposure factors used by hospital radiology departments and private radiology practices for a standard size 1, 5, 10 and 15 year old child, for the following procedures: chest AP/PA, lat; abdomen AP; pelvis AP; lumbar spine AP, lat; and skull AP, lat. There was a large range of doses for each particular procedure and age group. Factors contributing to the range of doses were identified. Guidance levels for paediatric radiology based on the third quartile value of the skin entrance doses have been recommended and are compared with guidance levels. Copyright (1998) Australasian Physical and Engineering Sciences in Medicine

Dose evaluation in special fluoroscopy procedures: Hysterosalpingography and Dacryocystography; Avaliacao de dose em procedimentos especiais de fluoroscopia: histerossalpingografia e dacriocistografia

Energy Technology Data Exchange (ETDEWEB)

Lopes, Cintya Carolina Barbosa

2006-04-15

The hysterosalpingography (HSG) and dacryocystography (DCG) are among the special fluoroscopy procedures. The HSG is a radiodiagnostic technique used to detect uterine and tubal pathologies and it is fundamental for the investigation of infertility. The DCG is a form of lacrimal system imaging, being important to show the level of obstruction, the presence of dilatation of the lacrimal sac, as well as alterations in nearby structures. At this research, the study of skin entrance dose was evaluated for these two special fluoroscopy procedures, besides the analyses of staff doses whose performs the exams. The exams of 22 HSG patients and 8 DCG patients were evaluated using TL-100 dosimeters attached on patient' skin at anatomical landmarks evolved on each exam. In the case of HSG, the results showed that skin entrance doses varied from 0.5 mGy to 73.4 mGy, with an average value of 22.1 mGy. The estimated uterus dose was 5.5 mGy, and 6.6 mGy was the average dose estimated to the ovaries. The patient' skin entrance dose undergoing to DCG examinations varied from 2.1 mGy to 10.6 mGy, and the average eye's dose was 6.1 mGy. The results of staff dose showed that, on HSG, the average dose on doctor's right hand was 4.3 mGy per examination. This value had to the fact that the physician introduces the contrast manually while all contrast exposures. In relation of DCG, the staff's dose values were nearby background radiation, evidencing that, inside of permitted limits, there is no risk for the physicians at this procedure. (author)

Entrance surface dose in cerebral interventional radiology procedures

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Barrera-Rico, M.; Lopez-Rendon, X.; Rivera-Ordonez, C. E.; Gamboa-deBuen, I. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, 04510 DF (Mexico); Instituto Nacional de Neurologia y Neurocirugia Manuel Velasco Suarez, 14269 DF (Mexico); Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, 04510 DF (Mexico)

2012-10-23

At the Instituto Nacional de Neurologia y Neurocirugia (INNN) diagnostic as well as therapeutic procedures of interventional radiology are carried out. Since the procedures can last from some minutes to several hours, the absorbed dose for the patient could increase dangerously. An investigation had begun in order to determine the entrance surface dose (ESD) using 25 thermoluminiscent dosimeters TLD-100 and 8 strips of 15 Multiplication-Sign 1 cm{sup 2} of Gafchromic XR-QA2 film bound in a holder of 15 Multiplication-Sign 15 cm{sup 2} in the posteroanterior (PA) and lateral (LAT) positions during all the procedure. The results show that maximum ESD could be from 0.9 to 2.9 Gy for the PA position and between 1.6 and 2.5 Gy for the lateral position. The average ESD was between 0.7 and 1.3 Gy for the PA position, and from 0.44 to 1.1 Gy for the lateral position in a therapeutic procedure.

Entrance surface dose in cerebral interventional radiology procedures

International Nuclear Information System (INIS)

Barrera-Rico, M.; López-Rendón, X.; Rivera-Ordóñez, C. E.; Gamboa-deBuen, I.

2012-01-01

At the Instituto Nacional de Neurología y Neurocirugía (INNN) diagnostic as well as therapeutic procedures of interventional radiology are carried out. Since the procedures can last from some minutes to several hours, the absorbed dose for the patient could increase dangerously. An investigation had begun in order to determine the entrance surface dose (ESD) using 25 thermoluminiscent dosimeters TLD-100 and 8 strips of 15 ×1 cm 2 of Gafchromic XR-QA2 film bound in a holder of 15×15 cm 2 in the posteroanterior (PA) and lateral (LAT) positions during all the procedure. The results show that maximum ESD could be from 0.9 to 2.9 Gy for the PA position and between 1.6 and 2.5 Gy for the lateral position. The average ESD was between 0.7 and 1.3 Gy for the PA position, and from 0.44 to 1.1 Gy for the lateral position in a therapeutic procedure.

Dose evaluation in special fluoroscopy procedures: Hysterosalpingography and Dacryocystography; Avaliacao de dose em procedimentos especiais de fluoroscopia: histerossalpingografia e dacriocistografia

Energy Technology Data Exchange (ETDEWEB)

Lopes, Cintya Carolina Barbosa

2006-04-15

The hysterosalpingography (HSG) and dacryocystography (DCG) are among the special fluoroscopy procedures. The HSG is a radiodiagnostic technique used to detect uterine and tubal pathologies and it is fundamental for the investigation of infertility. The DCG is a form of lacrimal system imaging, being important to show the level of obstruction, the presence of dilatation of the lacrimal sac, as well as alterations in nearby structures. At this research, the study of skin entrance dose was evaluated for these two special fluoroscopy procedures, besides the analyses of staff doses whose performs the exams. The exams of 22 HSG patients and 8 DCG patients were evaluated using TL-100 dosimeters attached on patient' skin at anatomical landmarks evolved on each exam. In the case of HSG, the results showed that skin entrance doses varied from 0.5 mGy to 73.4 mGy, with an average value of 22.1 mGy. The estimated uterus dose was 5.5 mGy, and 6.6 mGy was the average dose estimated to the ovaries. The patient' skin entrance dose undergoing to DCG examinations varied from 2.1 mGy to 10.6 mGy, and the average eye's dose was 6.1 mGy. The results of staff dose showed that, on HSG, the average dose on doctor's right hand was 4.3 mGy per examination. This value had to the fact that the physician introduces the contrast manually while all contrast exposures. In relation of DCG, the staff's dose values were nearby background radiation, evidencing that, inside of permitted limits, there is no risk for the physicians at this procedure. (author)

Dose evaluation in special fluoroscopy procedures: Hysterosalpingography and Dacryocystography

International Nuclear Information System (INIS)

Lopes, Cintya Carolina Barbosa

2006-04-01

The hysterosalpingography (HSG) and dacryocystography (DCG) are among the special fluoroscopy procedures. The HSG is a radiodiagnostic technique used to detect uterine and tubal pathologies and it is fundamental for the investigation of infertility. The DCG is a form of lacrimal system imaging, being important to show the level of obstruction, the presence of dilatation of the lacrimal sac, as well as alterations in nearby structures. At this research, the study of skin entrance dose was evaluated for these two special fluoroscopy procedures, besides the analyses of staff doses whose performs the exams. The exams of 22 HSG patients and 8 DCG patients were evaluated using TL-100 dosimeters attached on patient' skin at anatomical landmarks evolved on each exam. In the case of HSG, the results showed that skin entrance doses varied from 0.5 mGy to 73.4 mGy, with an average value of 22.1 mGy. The estimated uterus dose was 5.5 mGy, and 6.6 mGy was the average dose estimated to the ovaries. The patient' skin entrance dose undergoing to DCG examinations varied from 2.1 mGy to 10.6 mGy, and the average eye's dose was 6.1 mGy. The results of staff dose showed that, on HSG, the average dose on doctor's right hand was 4.3 mGy per examination. This value had to the fact that the physician introduces the contrast manually while all contrast exposures. In relation of DCG, the staff's dose values were nearby background radiation, evidencing that, inside of permitted limits, there is no risk for the physicians at this procedure. (author)

Characterization of a MOSkin detector for in vivo skin dose measurements during interventional radiology procedures

Energy Technology Data Exchange (ETDEWEB)

Safari, M. J.; Wong, J. H. D.; Ng, K. H., E-mail: ngkh@um.edu.my [Department of Biomedical Imaging, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia and University of Malaya Research Imaging Centre, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Jong, W. L. [Clinical Oncology Unit, Faculty of Medicine, University of Malaya, Kuala Lumpur 50603 (Malaysia); Cutajar, D. L.; Rosenfeld, A. B. [Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

2015-05-15

Purpose: The MOSkin is a MOSFET detector designed especially for skin dose measurements. This detector has been characterized for various factors affecting its response for megavoltage photon beams and has been used for patient dose measurements during radiotherapy procedures. However, the characteristics of this detector in kilovoltage photon beams and low dose ranges have not been studied. The purpose of this study was to characterize the MOSkin detector to determine its suitability for in vivo entrance skin dose measurements during interventional radiology procedures. Methods: The calibration and reproducibility of the MOSkin detector and its dependency on different radiation beam qualities were carried out using RQR standard radiation qualities in free-in-air geometry. Studies of the other characterization parameters, such as the dose linearity and dependency on exposure angle, field size, frame rate, depth-dose, and source-to-surface distance (SSD), were carried out using a solid water phantom under a clinical x-ray unit. Results: The MOSkin detector showed good reproducibility (94%) and dose linearity (99%) for the dose range of 2 to 213 cGy. The sensitivity did not significantly change with the variation of SSD (±1%), field size (±1%), frame rate (±3%), or beam energy (±5%). The detector angular dependence was within ±5% over 360° and the dose recorded by the MOSkin detector in different depths of a solid water phantom was in good agreement with the Markus parallel plate ionization chamber to within ±3%. Conclusions: The MOSkin detector proved to be reliable when exposed to different field sizes, SSDs, depths in solid water, dose rates, frame rates, and radiation incident angles within a clinical x-ray beam. The MOSkin detector with water equivalent depth equal to 0.07 mm is a suitable detector for in vivo skin dosimetry during interventional radiology procedures.

Reference Dose Rates for Fluoroscopy Guided Interventions

International Nuclear Information System (INIS)

Geleijns, J.; Broerse, J.J.; Hummel, W.A.; Schalij, M.J.; Schultze Kool, L.J.; Teeuwisse, W.; Zoetelief, J.

1998-01-01

The wide diversity of fluoroscopy guided interventions which have become available in recent years has improved patient care. They are being performed in increasing numbers, particularly at departments of cardiology and radiology. Some procedures are very complex and require extended fluoroscopy times, i.e. longer than 30 min, and radiation exposure of patient and medical staff is in some cases rather high. The occurrence of radiation-induced skin injuries on patients has shown that radiation protection for fluoroscopy guided interventions should not only be focused on stochastic effects, i.e. tumour induction and hereditary risks, but also on potential deterministic effects. Reference dose levels are introduced by the Council of the European Communities as an instrument to achieve optimisation of radiation protection in radiology. Reference levels in conventional diagnostic radiology are usually expressed as entrance skin dose or dose-area product. It is not possible to define a standard procedure for complex interventions due to the large inter-patient variations with regard to the complexity of specific interventional procedures. Consequently, it is not realistic to establish a reference skin dose or dose-area product for complex fluoroscopy guided interventions. As an alternative, reference values for fluoroscopy guided interventions can be expressed as the entrance dose rates on a homogeneous phantom and on the image intensifier. A protocol has been developed and applied during a nationwide survey of fluoroscopic dose rate during catheter ablations. From this survey reference entrance dose rates of respectively 30 mGy.min -1 on a polymethylmethacrylate (PMMA) phantom with a thickness of 21 cm, and of 0.8 μGy.s -1 on the image intensifier have been derived. (author)

Selection of skin dose calculation methodologies

International Nuclear Information System (INIS)

Farrell, W.E.

1987-01-01

This paper reports that good health physics practice dictates that a dose assessment be performed for any significant skin contamination incident. There are, however, several methodologies that could be used, and while there is probably o single methodology that is proper for all cases of skin contamination, some are clearly more appropriate than others. This can be demonstrated by examining two of the more distinctly different options available for estimating skin dose the calculational methods. The methods compiled by Healy require separate beta and gamma calculations. The beta calculational method is the derived by Loevinger, while the gamma dose is calculated from the equation for dose rate from an infinite plane source with an absorber between the source and the detector. Healy has provided these formulas in graphical form to facilitate rapid dose rate determinations at density thicknesses of 7 and 20 mg/cm 2 . These density thicknesses equate to the regulatory definition of the sensitive layer of the skin and a more arbitrary value to account of beta absorption in contaminated clothing

Investigation of radiation skin dose in interventional cardiology

International Nuclear Information System (INIS)

Webster, C.M.; Horrocks, J.; Hayes, D.

2001-01-01

Background - The study investigated the radiation skin doses for interventional patients in cardiology; two procedures which have the highest radiation dose are Radiofrequency Catheter Ablation (RFCA) and Percutaneous Transluminal Coronary Angioplasty (PTCA). Methods and Results - 56 patients were randomly selected and investigated; 23 patients in the RFCA group and 33 in the PTCA group. Skin and effective dose were calculated from Dose Area Product (DAP). Thermoluminescent Dosimetry was the second method of dose measurement used. Patients were followed-up for a three month period to check for possible skin reactions resulting from the radiation dose during the procedure. Radiation skin doses in 14 patients were calculated to be more than 1 Gy, including three patients who received more than 2 Gy, the threshold dose for deterministic effects of radiation. 7 patients (12.5%) reported skin reactions as a result of the radiation received to their backs during the procedure. Mean DAP and estimated effective doses were 105 Gycm 2 and 22.5 mSv for RFCA, and 32 Gycm 2 and 6.2 mSv for PTCA procedures respectively. Conclusion - Complex procedures in Interventional Cardiology can exceed the threshold level for deterministic effects in the skin. (author)

Evaluation of entrance skin air kerma in digital and conventional pediatric chest examinations performed in Parana-Brazil

International Nuclear Information System (INIS)

Oliveira, Ana L.R.; Schelin, Hugo R.; Lunelli, Neuri; Paschuk, Sergei; Tilly Jr, Joao G.; Rogacheski, Enio; Khoury, Helen J.; Ferreira, Jose R.L.

2008-01-01

Full text: In pediatric radiology it is important to evaluate patient exposure due to the high sensitivity of his/her tissue and his/her relatively longer life expectancy, which may increase the chance of radiogenic cancer development. Special attention is necessary when digital systems are used since a high dosage level for the patient may go unnoticed because the resulting image is not overexposed. The purpose of this work is to evaluate the Entrance Skin Air Kerma (ESAK) in pediatric patients submitted to digital and conventional chest examinations performed in the State of Parana, located in the Southern region of Brazil. The survey was performed in two hospitals, one located in Curitiba, the Capital of the State (A) and the other in the city of Cascavel (B). Hospital A uses a conventional image system and Hospital B uses a CR digital system. The study group consisted of 50 patients (from 2 days to six years of age) undergoing chest PA/AP examinations. At the time of the examination, the exposure parameters (kV, mAs, focal-film distance, etc) and the gender, height, weight and age of the patient were recorded. To evaluate the Entrance Skin Air Kerma (ESAK), two TLD-100 dosimeters were packaged in a polyethylene case, heat sealed and placed on the surface of each patient. The TLDs were calibrated the Metrology Laboratory of Ionizing Radiation of the Federal University of Pernambuco. The TLDs were processed on a Victoreen readout system model 2800M. The results showed that the kilovoltage values used in Hospital A are in the range of 46 to 65 kV with the average value of 51,7 kV, while the ones in Hospital B are in the range of 65 to 80 kV. On the other hand, even though hospital B uses the CR system, the mAs used for the chest exams are 4 times higher than the ones used in Hospital A. For Hospital A, the mean ESAK value was 0.044 mGy (min: 0.08 and max 0.146 mGy), and for Hospital B the mean ESAK value was 0.368 mGy (min: 0.021 and max 1.21mGy). The results made

Skin dose measurement with MICROSPEC-2 trademark

International Nuclear Information System (INIS)

Hsu, H.H.

1997-01-01

For many years, the Eberline HP-260 trademark beta detectors were used for skin dose measurements at Los Alamos National Laboratory. This detector does not measure the beta spectrum and the skin dose can only be determined if the contaminating radioactive isotope is known. A new product MICROSPEC-2 trademark, has been developed which consists of a small portable computer with a multichannel analyzer and a beta probe consisting of a phoswich detector. The system measures the beta spectrum and automatically folds in the beta fluence-to-dose conversion function to yield the skin dose

Development of a external exposure computational model for studying of input dose in skin for radiographs of thorax and vertebral column; Desenvolvimento de um modelo computacional de exposicao externa para estudo da dose de entrada na pele para radiografias de torax e coluna

Energy Technology Data Exchange (ETDEWEB)

Muniz, Bianca C.; Menezes, Claudio J.M., E-mail: bianca.cm95@gmail.com, E-mail: cjmm@cnen.gov.br [Centro Regional de Ciencias Nucleares do Nordeste (CRCN-NE/CNEN-PE), Recife, PE (Brazil); Vieira, Jose W., E-mail: jwvieira@br.inter.net [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil)

2014-07-01

The dosimetric measurements do not always happen directly in the human body. Therefore, these assessments can be performed using anthropomorphic models (phantoms) evidencing models computational exposure (MCE) using techniques of Monte Carlo Method for virtual simulations. These processing techniques coupled with more powerful and affordable computers make the Monte Carlo method one of the tools most used worldwide in radiation transport area. In this work, the Monte Carlo EGS4 program was used to develop a computer model of external exposure to study the entrance skin dose for chest and column X-radiography and, aiming to optimize these practices by reducing doses to patients, professionals involved and the general public. The results obtained experimentally with the electrometer Radcal, model 9015, associated with the ionization chamber for radiology model 10X5-6, showed that the proposed computational model can be used in quality assurance programs in radiodiagnostic, evaluating the entrance skin dose when varying parameters of the radiation beam such as kilo voltage peak (kVp), current-time product (mAs), total filtration and distance surface source (DFS), optimizing the practices in radiodiagnostic and meeting the current regulation.

Influência da dependência energética de dosímetros termoluminescentes na medida da dose na entrada da pele em procedimentos radiográficos Influence of thermoluminescent dosimeters energy dependence on the measurement of entrance skin dose in radiographic procedures

Directory of Open Access Journals (Sweden)

Mércia Liane de Oliveira

2010-04-01

Full Text Available OBJETIVO: O objetivo do presente trabalho foi avaliar a influência da dependência energética de materiais termoluminescentes na determinação da dose na entrada da pele de pacientes submetidos a exames radiográficos (radiologia geral, mamografia e radiologia odontológica. MATERIAIS E MÉTODOS: Três diferentes materiais termoluminescentes foram utilizados: LiF:Mg,Ti, LiF:Mg,Cu,P e CaSO4:Dy. Estes materiais foram expostos a fontes padronizadas de radiação X e gama, e a feixes clínicos de raios X. RESULTADOS: As curvas de calibração e de dependência energética foram obtidas. Todos os materiais apresentaram resposta linear em função do kerma no ar. Com relação à dependência energética, as amostras de CaSO4:Dy e LiF:Mg,Ti mostraram maior variação da resposta termoluminescente em função da energia efetiva do feixe de radiação. CONCLUSÃO: Os materiais testados mostraram desempenho adequado para a detecção da radiação X em feixes padronizados e clínicos. Embora as amostras de CaSO4:Dy e LiF:Mg,Ti apresentem dependência energética significativa no intervalo de energia considerado, este materiais podem ser utilizados para medição da dose de entrada na pele se fatores de correção apropriados forem utilizados.OBJECTIVE: This study was aimed at evaluating the influence of the energy dependence of thermoluminescent materials on the determination of entrance skin dose in patients submitted to conventional radiographic studies (general radiology, mammography and dental radiology. MATERIALS AND METHODS: Three different thermoluminescent materials were utilized: LiF:Mg,Ti, LiF:Mg,Cu,P and CaSO4:Dy. These materials were exposed to standardized sources of X and gamma radiation and clinical X-ray beams. RESULTS: Calibration and energy dependence curves were obtained. All the materials showed a linear response as a function of the air kerma. As far as energy dependence is concerned, the CaSO4:Dy and LiF:Mg,Ti samples showed the

Dose estimation at the entrance of the skin in diagnostic imaging equipment using distributions of workloads

International Nuclear Information System (INIS)

Pereira, Paula A.A.; Furquim, Tania A.C.; Costa, Paulo R.

2005-01-01

The work proposed to implement workload distributions with respect to radiological equipment of different technologies, the input dose calculation in the skin (DEP). With the results of the survey in the field (radiological clinics and hospitals of the city of Sao Paulo, SP, Brazil), a methodology was studied for the application of this information in the calculation of DEP and the application of statistical treatment of results of measurements performed. With the results, we can conclude that the choice of the appropriate number of samples is important in order to obtain statistically acceptable values. In addition, it can be concluded that the method presented is valid because the DEP found values are very close to the values calculated by other methods previously developed by the authors

Patient dose, gray level and exposure index with a computed radiography system

Science.gov (United States)

Silva, T. R.; Yoshimura, E. M.

2014-02-01

Computed radiography (CR) is gradually replacing conventional screen-film system in Brazil. To assess image quality, manufactures provide the calculation of an exposure index through the acquisition software of the CR system. The objective of this study is to verify if the CR image can be used as an evaluator of patient absorbed dose too, through a relationship between the entrance skin dose and the exposure index or the gray level values obtained in the image. The CR system used for this study (Agfa model 30-X with NX acquisition software) calculates an exposure index called Log of the Median (lgM), related to the absorbed dose to the IP. The lgM value depends on the average gray level (called Scan Average Level (SAL)) of the segmented pixel value histogram of the whole image. A Rando male phantom was used to simulate a human body (chest and head), and was irradiated with an X-ray equipment, using usual radiologic techniques for chest exams. Thermoluminescent dosimeters (LiF, TLD100) were used to evaluate entrance skin dose and exit dose. The results showed a logarithm relation between entrance dose and SAL in the image center, regardless of the beam filtration. The exposure index varies linearly with the entrance dose, but the angular coefficient is beam quality dependent. We conclude that, with an adequate calibration, the CR system can be used to evaluate the patient absorbed dose.

Entrance surface dose measurements in mammography using thermoluminescence technique

International Nuclear Information System (INIS)

Rivera, T.; Vega C, H.R.; Manzanares A, E; Azorin, J.; Gonzalez, P.R.

2007-01-01

Full text: Of the various techniques that can be used for personnel dosimetry, thermoluminescence dosimetry (TLD) has emerged as a superior technique due to its manifold advantages over other methods of dose estimation. Various phosphors have been therefore investigated regarding their suitability for dosimetry. In this paper, a dosimetry system based on thermally stimulated luminescence (TSL) from zirconium oxide phosphors embedded in polytetrafluorethylene (ZrO 2 +PTFE) was developed for entrance surface doses (ES) measurements in mammography. Small ZrO 2 pellets of 5 mm in diameter and 0.8 mm in thickness were used. The reproducibility of measurements and linearity of ZrO 2 were also studied. The results were compared with those obtained from LiF:Mg,Cu,P usually used for the determination of absorbed dose in mammography. Measurements both per unit air kerma and In vivo were performed using a mammography unit model DMR (General Electric). The results showed that ZrO 2 TLDs can be used for the same X-ray dosimetry applications as LiF:Mg,Cu,P, with each type having the disadvantage of a response dependent on energy, particularly at low energies. These results indicate a considerable potential for use in routine control and In vivo ES measurements in mammography. (Author)

Radiation doses in interventional neuroradiology

International Nuclear Information System (INIS)

Theodorakou, C.; Butler, P.; Horrocks, J.A.

2001-01-01

Patient radiation doses during interventional radiology (IR) procedures may reach the thresholds for radiation-induced skin and eye lens injuries. This study investigates the radiation doses received by patients undergoing cerebral embolization. Measurements were conducted using thermoluminescent dosimeters. Radiotherapy verification films were used in order to visualise the radiation field. For each procedure the fluoroscopic and digital dose-area product, the fluoroscopic time, the total number of acquired images and entrance-skin dose calculated by the angiographic unit were recorded. In this paper, the skin, eye and thyroid glands doses on a sample of patients are presented. From a preliminary study of 13 patients having undergone cerebral embolization, it was deduced that six of them have received a dose above 1 Gy. Detailed dose data from patients undergoing IR procedures will be collected in the future with the aim of developing a model to allow estimation of the dose prior to the procedure as well as to look at techniques of dose reduction. (author)

Skin dose mapping for fluoroscopically guided interventions.

Science.gov (United States)

Johnson, Perry B; Borrego, David; Balter, Stephen; Johnson, Kevin; Siragusa, Daniel; Bolch, Wesley E

2011-10-01

To introduce a new skin dose mapping software system for interventional fluoroscopy dose assessment and to analyze the benefits and limitations of patient-phantom matching. In this study, a new software system was developed for visualizing patient skin dose during interventional fluoroscopy procedures. The system works by translating the reference point air kerma to the location of the patient's skin, which is represented by a computational model. In order to orient the model with the x-ray source, geometric parameters found within the radiation dose structured report (RDSR) are used along with a limited number of in-clinic measurements. The output of the system is a visual indication of skin dose mapped onto an anthropomorphic model at a resolution of 5 mm. In order to determine if patient-dependent and patient-sculpted models increase accuracy, peak skin dose was calculated for each of 26 patient-specific models and compared with doses calculated using an elliptical stylized model, a reference hybrid model, a matched patient-dependent model and one patient-sculpted model. Results were analyzed in terms of a percent difference using the doses calculated using the patient-specific model as the true standard. Anthropometric matching, including the use of both patient-dependent and patient-sculpted phantoms, was shown most beneficial for left lateral and anterior-posterior projections. In these cases, the percent difference using a reference model was between 8 and 20%, using a patient-dependent model between 7 and 15%, and using a patient-sculpted model between 3 and 7%. Under the table tube configurations produced errors less than 5% in most situations due to the flattening affects of the table and pad, and the fact that table height is the main determination of source-to-skin distance for these configurations. In addition to these results, several skin dose maps were produced and a prototype display system was placed on the in-clinic monitor of an interventional

Fast skin dose estimation system for interventional radiology.

Science.gov (United States)

Takata, Takeshi; Kotoku, Jun'ichi; Maejima, Hideyuki; Kumagai, Shinobu; Arai, Norikazu; Kobayashi, Takenori; Shiraishi, Kenshiro; Yamamoto, Masayoshi; Kondo, Hiroshi; Furui, Shigeru

2018-03-01

To minimise the radiation dermatitis related to interventional radiology (IR), rapid and accurate dose estimation has been sought for all procedures. We propose a technique for estimating the patient skin dose rapidly and accurately using Monte Carlo (MC) simulation with a graphical processing unit (GPU, GTX 1080; Nvidia Corp.). The skin dose distribution is simulated based on an individual patient's computed tomography (CT) dataset for fluoroscopic conditions after the CT dataset has been segmented into air, water and bone based on pixel values. The skin is assumed to be one layer at the outer surface of the body. Fluoroscopic conditions are obtained from a log file of a fluoroscopic examination. Estimating the absorbed skin dose distribution requires calibration of the dose simulated by our system. For this purpose, a linear function was used to approximate the relation between the simulated dose and the measured dose using radiophotoluminescence (RPL) glass dosimeters in a water-equivalent phantom. Differences of maximum skin dose between our system and the Particle and Heavy Ion Transport code System (PHITS) were as high as 6.1%. The relative statistical error (2 σ) for the simulated dose obtained using our system was ≤3.5%. Using a GPU, the simulation on the chest CT dataset aiming at the heart was within 3.49 s on average: the GPU is 122 times faster than a CPU (Core i7-7700K; Intel Corp.). Our system (using the GPU, the log file, and the CT dataset) estimated the skin dose more rapidly and more accurately than conventional methods.

UV-radiation and skin cancer dose effect curves

International Nuclear Information System (INIS)

Henriksen, T.; Dahlback, A.; Larsen, S.H.

1988-08-01

Norwegian skin cancer data were used in an attempt to arrive at the dose effect relationship for UV-carcinogenesis. The Norwegian population is relatively homogenous with regard to skin type and live in a country where the annual effective UV-dose varies by approximately 40 percent. Four different regions of the country, each with a broadness of 1 o in latitude (approximately 111 km), were selected . The annual effective UV-doses for these regions were calculated assuming normal ozone conditions throughout the year. The incidence of malignant melanoma and non-melanoma skin cancer (mainly basal cell carcinoma) in these regions were considered and compared to the annual UV-doses. For both these types of cancer a quadratic dose effect curve seems to be valid. Depletions of the ozone layer results in larger UV-doses which in turn may yield more skin cancer. The dose effect curves suggest that the incidence rate will increase by an ''amplification factor'' of approximately 2

Radiation dose to neonates on a Special Care Baby Unit

International Nuclear Information System (INIS)

Faulkner, K.; Barry, J.L.; Smalley, P.

1989-01-01

The skin entrance dose to neonates on a special care baby unit was estimated from a knowledge of the technique factors, X-ray tube output and backscatter factors. Normalized organ dose data were employed to estimate radiation dose to a number of critical organs. Methods of reducing radiation dose to neonates were investigated. Initially, this involved changing the radiographic technique factors and introducing a lead rubber adjustable collimator, placed on top of the incubator, in addition to light beam diaphragms on the X-ray tube. These modifications to the examination technique appeared to reduce average entrance dose per radiograph from 92 μGy, to 58 μGy, a reduction of 37%. Later, a rare-earth film-screen combination was introduced to replace existing fast calcium tungstate screens. This enabled average entrance dose per radiograph to be reduced to 39 μGy, a further reduction of 33%. The mean radiation dose to a neonate is mainly determined by the number of radiographs. (author)

Radiation dose to neonates on a Special Care Baby Unit

Energy Technology Data Exchange (ETDEWEB)

Faulkner, K.; Barry, J.L.; Smalley, P.

1989-03-01

The skin entrance dose to neonates on a special care baby unit was estimated from a knowledge of the technique factors, X-ray tube output and backscatter factors. Normalized organ dose data were employed to estimate radiation dose to a number of critical organs. Methods of reducing radiation dose to neonates were investigated. Initially, this involved changing the radiographic technique factors and introducing a lead rubber adjustable collimator, placed on top of the incubator, in addition to light beam diaphragms on the X-ray tube. These modifications to the examination technique appeared to reduce average entrance dose per radiograph from 92 ..mu..Gy, to 58 ..mu..Gy, a reduction of 37%. Later, a rare-earth film-screen combination was introduced to replace existing fast calcium tungstate screens. This enabled average entrance dose per radiograph to be reduced to 39 ..mu..Gy, a further reduction of 33%. The mean radiation dose to a neonate is mainly determined by the number of radiographs.

Evaluation of organ dose and estimation of risk due to the abdominal region radiography in Indian adults

International Nuclear Information System (INIS)

Kumaresan, M.; Chaubey, Ajay; Kantharia, Surita; Karira, V.; Kumar, Rajesh; Biju, K.; Rao, B.S.

2006-01-01

Organ dose, risk of carcinogenesis and genetic effect due to the abdominal region radiography in Indian adult with the help of Monte-Carlo MCNP code by measuring the entrance skin dose by LiF: Mg, Cu, P TL phosphor and the risk coefficients provided by ICRP 60 were estimated. The entrance skin dose for abdominal region radiography was ranges from 2.75 mSv to 18.88 mSv while average entrance skin dose was 8.3 mSv. The bladder, testes and ovary are the important organ those are getting higher dose. The maximum dose for testes, ovary and bladder is 5.37 mSv, 1.45 mSv and 4.74 mSv respectively. The frequency of occurrence of fatal cancers and serious genetic disorders as a consequence of abdominal region radiography ranges from 0.1 to 38.8 risk/10 6 of fatal cancer. Although the estimated risks are small but cannot be neglected. It is important to avoid unnecessary repetitions and also to carry out proper quality assurance tests on the equipment and in the long run it will help reduce the risks and maximize the benefits of radiodiagnosis. These studies may lead to setting up of national reference levels for the diagnostic procedures India. (author)

Analysis of entrance skin radiation dose in mammography equipment in Rio Grande do Sul state (Ijui municipality and surroundings) and Rio de Janeiro (metropolitan area); Analise de dose de entrada na pele em mamografos, no Estado do Rio Grande do Sul (Municipio de Ijui e cercanias) e Rio de Janeiro (area metropolitana)

Energy Technology Data Exchange (ETDEWEB)

Araujo, Geovane Silva; Padilha Filho, Lucas Gomes, E-mail: geovane.araujo@ftesm.edu.br, E-mail: lucaspadilhaemec@gmail.com [Universidade Estacio de Sa (UNESA), Rio de Janeiro, RJ (Brazil); Sousa, Carlos Henrique Simoes de, E-mail: chenriques2@gmail.com [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil); Feldmann, Gerson; Albrecht, Marcos R.A., E-mail: gersonpraxis@gmail.com, E-mail: marcosboom@yahoo.com.br [PRAXIS Protecao Radiologica, Ijui, RS (Brazil); Souza, Sergio Augusto Lopes de, E-mail: sergioalsouza@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

2016-07-01

Mammography is the technique widely used to the early detection of breast cancer, despite of not being a consensus the ideal age to initiate the radiologic examinations, it is recommended that women with the age of forty realize the examinations periodically. With the objective to analyze the entrance skin dose (ESD) in different mammography equipment, Were analyzed in the Estate of Rio Grande do Sul (Ijui City and neighborhoods) and in Rio de Janeiro (metropolitan area) 24 mammography equipment. Among them included in the study, just one presented ESD higher than the established limit of ANVISA. It was observed in the mammography equipment of Ijui and neighborhoods high levels of mAs to achieve the values of ESD next to the limit. (author)

SU-F-P-44: A Direct Estimate of Peak Skin Dose for Interventional Fluoroscopy Procedures

International Nuclear Information System (INIS)

Weir, V; Zhang, J

2016-01-01

Purpose: There is an increasing demand for medical physicist to calculate peak skin dose (PSD) for interventional fluoroscopy procedures. The dose information (Dose-Area-Product and Air Kerma) displayed in the console cannot directly be used for this purpose. Our clinical experience shows that the use of the existing methods may overestimate or underestimate PSD. This study attempts to develop a direct estimate of PSD from the displayed dose metrics. Methods: An anthropomorphic torso phantom was used for dose measurements for a common fluoroscopic procedure. Entrance skin doses were measured with a Piranha solid state point detector placed on the table surface below the torso phantom. An initial “reference dose rate” (RE) measurement was conducted by comparing the displayed dose rate (mGy/min) to the dose rate measured. The distance from table top to focal spot was taken as the reference distance (RD at the RE. Table height was then adjusted. The displayed air kerma and DAP were recorded and sent to three physicists to estimate PSD. An inverse square correction was applied to correct displayed air kerma at various table heights. The PSD estimated by physicists and the PSD by the proposed method were then compared with the measurements. The estimated DAPs were compared to displayed DAP readings (mGycm2). Results: The difference between estimated PSD by the proposed method and direct measurements was less than 5%. For the same set of data, the estimated PSD by each of three physicists is different from measurements by ±52%. The DAP calculated by the proposed method and displayed DAP readings in the console is less than 20% at various table heights. Conclusion: PSD may be simply estimated from displayed air kerma or DAP if the distance between table top and tube focal spot or if x-ray beam area on table top is available.

SU-F-P-44: A Direct Estimate of Peak Skin Dose for Interventional Fluoroscopy Procedures

Energy Technology Data Exchange (ETDEWEB)

Weir, V [Baylor Scott and White Healthcare System, Dallas, TX (United States); Zhang, J [University of Kentucky, Lexington, KY (United States)

2016-06-15

Purpose: There is an increasing demand for medical physicist to calculate peak skin dose (PSD) for interventional fluoroscopy procedures. The dose information (Dose-Area-Product and Air Kerma) displayed in the console cannot directly be used for this purpose. Our clinical experience shows that the use of the existing methods may overestimate or underestimate PSD. This study attempts to develop a direct estimate of PSD from the displayed dose metrics. Methods: An anthropomorphic torso phantom was used for dose measurements for a common fluoroscopic procedure. Entrance skin doses were measured with a Piranha solid state point detector placed on the table surface below the torso phantom. An initial “reference dose rate” (RE) measurement was conducted by comparing the displayed dose rate (mGy/min) to the dose rate measured. The distance from table top to focal spot was taken as the reference distance (RD at the RE. Table height was then adjusted. The displayed air kerma and DAP were recorded and sent to three physicists to estimate PSD. An inverse square correction was applied to correct displayed air kerma at various table heights. The PSD estimated by physicists and the PSD by the proposed method were then compared with the measurements. The estimated DAPs were compared to displayed DAP readings (mGycm2). Results: The difference between estimated PSD by the proposed method and direct measurements was less than 5%. For the same set of data, the estimated PSD by each of three physicists is different from measurements by ±52%. The DAP calculated by the proposed method and displayed DAP readings in the console is less than 20% at various table heights. Conclusion: PSD may be simply estimated from displayed air kerma or DAP if the distance between table top and tube focal spot or if x-ray beam area on table top is available.

Impact of quality control radiation doses received by patients undergoing abdomen x-ray examination in ten hospitals

International Nuclear Information System (INIS)

Aghahadi, B.; Zhang, Z.; Zareh, S.; Sarkar, S.; Tayebi, P. S.

2006-01-01

The X-ray machines used for radiodiagnosis should meet certain quality assurance programmes. These are necessary to have good quality radiographs at reasonably low exposure to patients. Materials and Methods: Dose reduction methods in abdomen X-ray examination were carried out in 10 hospitals in Tehran. This paper presents the work, which was implemented on 200 patients and evaluated using the entrance skin dose in the Anterior-Posterior abdomen projection measured directly at the center of the X-ray field. In addition, the machine room, and dark room parameters, as well as work practices and repeat rates were studied. Results: The quality control parameters and the entrance skin dose were evaluated utilizing an anthropologic phantom to define the optimal exposure condition at all hospitals before and after quality control . Results show that after using the quality control parameters and optimization of the exposure conditions, the mean of mAs and entrance skin dose can be decreased by 62% and 65% respectively. Conclusion: The quality of the radiographs generally increased. The reported method is easily implemented in any clinical situation where optimization of abdomen radiography is necessary

A study of the relationship between peak skin dose and cumulative air kerma in interventional neuroradiology and cardiology

International Nuclear Information System (INIS)

Neil, S; Padgham, C; Martin, C J

2010-01-01

A study of peak skin doses (PSDs) during neuroradiology and cardiology interventional procedures has been carried out using Gafchromic XR-RV2 film. Use of mosaics made from squares held in cling film has allowed doses to the head to be mapped successfully. The displayed cumulative air kerma (CAK) has been calibrated in terms of cumulative entrance surface dose (CESD) and results indicate that this can provide a reliable indicator of the PSD in neuroradiology. Results linking PSD to CESD for interventional cardiology were variable, but CAK is still considered to provide the best option for use as an indicator of potential radiation-induced effects. A CESD exceeding 3 Gy is considered a suitable action level for triggering follow-up of patients in neuroradiology and cardiology for possible skin effects. Application of dose action levels defined in this way would affect 8% of neurological embolisation procedures and 5% of cardiology ablation and multiple stent procedures at the hospitals where the investigations were carried out. A close relationship was observed between CESD and dose-area product (DAP) for particular types of procedure, and DAPs of 200-300 Gy cm 2 could be used as trigger levels where CAK readings were not available. The DAP value would depend on the mean field size and would need to be determined for each application.

The calculation of dose from external photon exposures using reference human phantoms and Monte Carlo methods. Pt. 3

International Nuclear Information System (INIS)

Drexler, G.; Panzer, W.; Widenmann, L.; Williams, G.; Zankl, M.

1984-03-01

This report gives tables of conversion factors for the calculation of organ doses from technical parameters of typical radiographic techniques. These conversion factors were calculated using a male and a female mathematical human phantom and an efficient Monte Carlo programme that determines the mean organ doses from the energy deposited in each organ. Each diagnostic X-ray examination is studied using three X-ray spectra resulting from three different high tension values. The conversion factors per unit entrance air dose in free air are given for sixteen organs and for the entrance and exit surface skin doses. The tables are actually valid only for the given parameters such as phantom dimensions, source-to-skin distance, projection and X-ray quality. This, of course, gives rise to some uncertainty when dealing with the individual technique and patient. The uncertainty in organ dose of adult patients, however, should not be very large, if the calculation is based on a similar geometry, and before all, on the actually administered entrance air dose in the selected high tension range according to the patient parameters. (orig.)

Multilayer detector for skin absorbed dose measuring

International Nuclear Information System (INIS)

Osanov, D.P.; Panova, V.P.; Shaks, A.I.

1985-01-01

A method for skin dosimetry based on utilization of multilayer detectors and permitting to estimate distribution of absorbed dose by skin depth is described. The detector represents a set of thin sensitive elements separated by tissue-equivalent absorbers. Quantitative evaluation and forecasting the degree of radiation injury of skin are determined by the formula based on determination of the probability of the fact that cells are not destroyed and they can divide further on. The given method ensures a possibility of quantitative evaluation of radiobiological effect and forecasting clinical consequences of skin irradiation by results of corresponding measurements of dose by means of the miultilayer detector

Evaluation of the Entrance Surface Dose (ESD and Radiation Dose to the Radiosensitive Organs in Pediatric Pelvic Radiography

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Vahid Karami

2017-06-01

Full Text Available Background Patients' dosimetry is crucial in order to enhance radiation protection optimization and to deliver low radiation dose to the patients in a radiological procedure. The aim of this study was to assess the entrance surface dose (ESD and radiation dose to the radiosensitive organs in pediatric pelvic radiography. Materials and Methods The studied population included 98 pediatric patients of both genders referred to anteroposterior (AP projection of pelvic radiography. The radiation dose was directly measured using high radiosensitive cylindrical lithium fluoride thermo-luminescent dosimeters (TLD-GR200. Two TLDs were placed at the center point of the radiation field to measure the ESD of pelvis. Moreover for each patient, 2 TLDs were placed upon each eyelid, 2 TLDs upon each breast, 2 TLDs upon the surface anatomical position of the thyroid gland and finally 2 TLDs at the surface anatomical position of the gonads to measure the received dose. Results The ESD ± standard deviation for AP pelvic radiography was obtained 591.7±76 µGy. Statistically significant difference was obtained between organs located outside and inside of the radiation field with respect to dose received (P

Skin Entrance dose to patients from routine P-A chest X-ray ...

African Journals Online (AJOL)

Background: Radiation of any amount is potentially hazardous and it should be minimized as much as possible during health care delivery. Objective: To determine and assess the variation of the dose received by patients undergoing chest x-ray examination, and to provide a useful baseline data to evaluate the dose to the ...

Comparison of Adsorbed Skin Dose Received by Patients in Cone Beam Computed Tomography, Spiral and Conventional Computed Tomography Scanninng

Directory of Open Access Journals (Sweden)

Rahimi A

2011-12-01

Full Text Available Background and Aims: The evaluation of absorbed dose received by patients could give useful information for radiation risk estimation. This study was performed to compare the entrance skin dose received by patients in cone beam computed tomography (CBCT, conventional and spiral computed tomography (CT.Materials and Methods: In this experimental study, 81 calibrated TLD chips were used. the TLD chips were placed on facial, thyroid and end of sternum skin surface in patients referred for CT of the paranasal sinuses(3 TLD chips for each area to estimate the absorbed dose received by central part of radiation field, thyroid and out of field areas, respectively. The data were analyzed using one-way ANOVA and Tukey tests. Results: The dose delivered to the center of irradiated field was about 0.79±0.09 mGy in CBCT technique compared with 16.31±3.71 and 18.84±4.12 mGy for spiral and conventional CT, respectively. The received dose by the out of field areas was about 54 percent of central area dose. There was statistical significant relationship between the imaging modalities and absorbed dose received by patients (P=0.016. The least absorbed dose was for CBCT and the greatest dose was for conventional CT imaging technique.Conclusion: The dose delivered to central area of irradiated field in conventional and spiral CT imaging modalities was about 24 times greater than of that in CBCT. Also, the highest received dose was for central area of radiated field and the lowest dose was for the out of field areas.

Radon dose to the skin and the possible induction of skin cancers

International Nuclear Information System (INIS)

Eatough, J.P.; Henshaw, D.L.

1991-01-01

The radon related alpha particle dose equivalent to the basal layer of the epidermis has been calculated and found to be at least 2 mSv.y -1 , for exposed skin at the UK average radon exposure of 20 Bq.m -3 . A considerably greater dose equivalent may be received at this same radon concentration depending on the plateout conditions. Using standard risk factors 13% of skin cancers would theoretically be attributed to radon at the UK average exposure of 20 Bq.m -3 . Direct studies of skin cancer and radon in the home are needed before the validity of this prediction can be established. There is little evidence from high dose studies suggesting the induction of malignant melanoma by ionising radiation, although some circumstantial evidence exists, and the possibility that radon may be a co-factor with UV light in the induction of malignant melanoma, should not be dismissed. Due to the nature of the radiation risk factors the majority of any skin cancers linked to radon will simultaneously be linked to ultraviolet light exposure. (author)

Dose factors for contamination of skin and clothing

International Nuclear Information System (INIS)

Henrichs, K.; Eiberweiser, C.; Paretzke, H.G.

1985-11-01

Methods are described for quantifying the radiation dose administered through radioactive contamination of the skin (and of clothing, in an approximative manner). The calculated results are presented in tables. The dose values established are of significance with regard to radiological assessment of contamination for the definition of dose limits, and for use as a criterion to select appropriate decontamination activities. Alpha, beta and monoenergetic electrons are of importance for estimating the absorbed dose in various skin depths, whereas for other body regions (as e.g. body organs) photon radiation has to be considered. The calculations are based on the assumption of homogeneous exposure of the skin, with the linear extension being large compared to the range of the emitted particle radiation. In order to be able to take into account potential penetration of radioactivity into deeper skin layers by diffusion or solution processes, the calculations have been made for contamination into various depths of the horny layers of the epidermis. The scheme of specific absorbed fraction (SAF) served as a basis for the uniform treatment of different radiation types for the calculation of dose values. (orig./HP) [de

The biological basis for dose limitation to the skin

International Nuclear Information System (INIS)

Fry, R.J.M.

1992-01-01

Ionizing radiation may cause deterministic effects and cancer. It has been the policy to base dose limits for radiation protection of the skin on the prevention of deterministic effects (1). In the case of cancer in general, dose limitation for radiation protection is based on limiting excess cancer mortality to low levels of radiation. Since skin cancers are seldom lethal, the general radiation protection standards will protect against an increase in excess mortality from skin cancer. However, with the dose limits selected to prevent deterministic effects, there is a significant probability of an excess incidence of skin cancer occurring as a result of exposure during a working lifetime. The induction of skin cancer by radiation is influenced significantly by subsequent exposure to ultraviolet radiation (UVR) from sunlight. This finding raises not only interesting questions about the mechanisms involved, but also about the differences in risk of skin cancer in different populations. The amount and distribution of melanin in the skin determines the degree of the effect of UVR. This paper discusses the mechanisms of the induction of both deterministic and stochastic effects in skin exposed to radiation in relation to radiation protection. (author)

Skin dose assessment in routine personnel beta/gamma dosimetry

International Nuclear Information System (INIS)

Christensen, P.

1980-01-01

The International Commission on Radiological Protection (Publication 26) has recommended a tissue depth of 5 to 10 mg.cm -2 for skin dose assessments. This requirement is generally not fulfilled by routine monitoring procedures because of practical difficulties in using very thin dosemeters with low sensitivity and therefore a high minimum detectable dose. Especially for low-energy beta-ray exposures underestimations of the skin dose by a factor of more than ten may occur. Low-transparent graphite-mixed sintered LiF and Li 2 B 4 0 7 : Mn dosemeters were produced which show a skin-equivalent response to beta and gamma exposures over a wide range of energies. These have found wide-spread application for extremity dosimetry but have not yet been generally introduced in routine personnel beta/gamma monitoring. The following adaptations of existing routine monitoring systems for improved skin dose assessments have been investigated: 1) Placement of a supplementary, thin, skin-dose equivalent dosemeter in the TLD badge to give additional information on low-energy exposures. 2) Introduction of a second photomultiplier in the read-out chamber which enables a simultaneous determination of emitted TL from both sides of the dosemeter separately. This method makes use of the selfshielding of the dosemeter to give information on the low-energy dose contribution. 3) By diffusion of Li 2 B 4 0 7 into solid LiF-dosemeters it was possible to produce a surface layer with a new distinct glow-peak at about 340 deg C which is not present in the undiffused part of the LiF chip, and which can be utilized for the assessment of the skin-dose. Data on energy response and accuracy of dose measurement for beta/gamma exposures are given for the three methods and advantages and disadvantages are discussed (H.K.)

Optimization of the quality and dose in thorax general radiology

International Nuclear Information System (INIS)

Hwang, Suy Ferreira

2001-01-01

Image quality and radiation dose at skin entrance in chest radiography were studied for three exposure protocols, denoted as 1, 2 and 3. Protocol 1 represents the most used technique in radiology services in our country. This technique consists of the following parameters: 81 kV tube voltage, anti-scatter grid and 2 m focus-film distance. Protocol 2 uses the same parameters of the Protocol 1, without grid. Protocol 3 uses I 33kV without grid and 3,5 m focus-film distance. In Protocols 2 and 3 a 30 em air gap was used between patient and film. Two samples of 50 patients were radiographed in two different facilities, herein denoted 1 and 2. Protocol 1 was used in facility I to radiograph the first patient sample, and Protocols 2 and 3 were used in facility 2 to radiograph the second patient sample. Three experts in chest radiology evaluated the obtained chest images according anatomical quality criteria for this examination. For each patient exposure the radiation dose at skin entrance was measured. In this work, a chest phantom, containing test objects to evaluate quantitatively image quality, was made. The phantom was radiographed with the three protocols herein investigated. Results of this study showed clearly that Protocol 3 presents an average dose at skin entrance about half than Protocol 2 and about one third of Protocol 1. In regard to chest radiographic images and radiation dose, it was statistically demonstrated that the Protocol 3 is better than Protocols 1 and 2, with the improvement of the image quality and patient dose reduction in order of 3 times. This work also discusses the perspective of using optimized exposure technique proposed by Protocol 3 as an alternative technique far chest radiographic examinations to those currently used in our diagnostic radiology facilities. (author)

Radiation injury of the skin following diagnostic and interventional fluoroscopic procedures

International Nuclear Information System (INIS)

Koenig, T.R.; Wagner, L.K.; Mettler, F.A.

2001-01-01

Many radiation injuries to the skin, resulting from diagnostic and interventional fluoroscopic procedures, have been reported in recent years. In some cases skin damage was severe and debilitating. We analyzed 72 reports of skin injuries for progression and location of injury, type and number of procedures, and contributing patient and operator factors. Most cases (46) were related to coronary angiography and percutaneous transluminal coronary angioplasty (PTCA). A smaller number was documented after cardiac radiofrequency catheter ablation (12), transjugular intrahepatic portosystemic shunt (TIPS) placement (7), neuroradiological interventions (3) and other procedures (4). Important factors leading to skin injuries were long exposure times over the same skin area, use of high dose rates, irradiation through thick tissue masses, hypersensitivity to radiation, and positioning of arms or breasts into the radiation entrance beam. Physicians were frequently unaware of the high radiation doses involved and did not recognize the injuries as radiation induced. Based on these findings, recommendations to reduce dose and improve patient care are provided. (author)

Measurement of off-axis and peripheral skin dose using radiochromic film

International Nuclear Information System (INIS)

Butson, Martin J.; Yu, P.K.N.; Metcalfe, P.E.

1998-01-01

A radiotherapy skin dose profile can be obtained with radiochromic film. The central axis skin dose relative to D max for a 10x10cm 2 field size was found to be 22%, 17% and 15.5% for 6 MV, 10 MV and 18 MV photon beams. Peripheral dose increased with increasing field size. At 10 MV the skin dose 2 cm outside the geometric field edge was measured as 6%, 10% and 17% for 10x10cm 2 , 20x20cm 2 and 30x30cm 2 field sizes respectively. Off-axis skin dose decreased as distance increased from central axis for fields with Perspex block trays. For a 20x20cm 2 field, an approximately 5-8% drop in percentage skin dose was observed from central axis to the beam edge. (author)

Verification of skin dose according to the location of tumor in Tomotherapy

International Nuclear Information System (INIS)

Yoon, Bo Reum; Park, Su Yeon; Park, Byoung Suk; KIm, Jong Sik; Song, Ki Won

2014-01-01

To verify the skin dose in Tomotherapy-based radiation treatment according to the change in tumor locations, skin dose was measured by using Gafchromic EBT3 film and compared with the planned doses to find out the gap between them. In this study, to measure the skin dose, I'm RT Phantom(IBA Dosimetry, Germany) was utilized. After obtaining the 2.5 mm CT images, tumor locations and skin dose measuring points were set by using Pinnacle(ver 9.2, Philips Medical System, USA). The tumor location was decided to be 5 mm and 10 mm away from surface of the phantom and center. Considering the attenuation of a Tomo-couch, we ensured a symmetric placement between the ceiling and floor directions of the phantom. The measuring point of skin doses was set to have 3 mm and 5 mm thickness from the surface. Measurement was done 3 times. By employing TomoHD(TomoHD treatment system, Tomotherapy Inc., Madison, Wisconsin, USA), we devised Tomotherapy plans, measured 3 times by inserting Gafchromic EBT3 film into the phantom and compared the measurement with the skin dose treatment plans. The skin doses in the upper part of the phantom, when the tumor was located in the center, were found to be 7.53 cGy and 7.25 cGy in 5 mm and 3 mm respectively. If placed 5 mm away from the skin in the ceiling direction, doses were 18.06 cGy and 16.89 cGy; if 10 mm away, 20.37 cGy and 18.27 cGy, respectively. The skin doses in the lower part of the phantom, when the tumor was located in the center, recorded 8.82 cGy and 8.29 cGy in 5 mm and 3 mm, each; if located 5mm away from the lower part skin, 21.69 cGy and 19.78 cGy were respectively recorded; and if 10 mm away, 20.48 cGy and 19.57 cGy were recorded. If the tumor was placed in the center, skin doses were found to increase by 3.2-17.1% whereas if the tumor is 5 mm away from the ceiling part, the figure decreased to 2.8-9.0%. To the Tomo-couch direction, skin doses showed an average increase of 11% or over, compared to the planned treatment

Skin dose variation: influence of energy

International Nuclear Information System (INIS)

Cheung, T.; Yu, P.K.N.; Butson, M.J.; Cancer Services, Wollongong, NSW

2004-01-01

Full text: This research aimed to quantitatively evaluate the differences in percentage dose of maximum for 6MV and 18MV x-ray beams within the first lcm of interactions. Thus provide quantitative information regarding the basal, dermal and subcutaneous dose differences achievable with these two types of high-energy x-ray beams. Percentage dose of maximum build up curves are measured for most clinical field sizes using 6MV and 18MV x-ray beams. Calculations are performed to produce quantitative results highlighting the percentage dose of maximum differences delivered to various depths within the skin and subcutaneous tissue region by these two beams Results have shown that basal cell layer doses are not significantly different for 6MV and 18Mv x-ray beams At depths beyond the surface and basal cell layer there is a measurable and significant difference in delivered dose. This variation increases to 20% of maximum and 22% of maximum at Imm and 1cm depths respectively. The percentage variations are larger for smaller field sizes where the photon in phantom component of the delivered dose is the most significant contributor to dose By producing graphs or tables of % dose differences in the build up region we can provide quantitative information to the oncologist for consideration (if skin and subcutaneous tissue doses are of importance) during the beam energy selection process for treatment. Copyright (2004) Australasian College of Physical Scientists and Engineers in Medicine

Kodak EDR2 film for patient skin dose assessment in cardiac catheterization procedures.

Science.gov (United States)

Morrell, R E; Rogers, A T

2006-07-01

Patient skin doses were measured using Kodak EDR2 film for 20 coronary angiography (CA) and 32 percutaneous transluminal coronary angioplasty (PTCA) procedures. For CA, all skin doses were well below 1 Gy. However, 23% of PTCA patients received skin doses of 1 Gy or more. Dose-area product (DAP) was also recorded and was found to be an inadequate indicator of maximum skin dose. Practical compliance with ICRP recommendations requires a robust method for skin dosimetry that is more accurate than DAP and is applicable over a wider dose range than EDR2 film.

Technical background for shallow (skin) dose equivalent evaluations

International Nuclear Information System (INIS)

Ashley, J.C.; Turner, J.E.; Crawford, O.H.; Hamm, R.N.; Reaves, K.L.; McMahan, K.L.

1991-01-01

Department of Energy Order 5480.11 describes procedures for radiation protection for occupational workers. The revisions dealing with non-uniform exposure to the skin are the subject of this report. We describe measurements and analysis required to assess shallow (skin) dose equivalent from skin contamination. 6 refs., 4 tabs

Relationship between source-surface distance and patient dose in fluoroscopic X-ray examinations

International Nuclear Information System (INIS)

Suzuki, Shoichi; Asada, Yasuki; Nishi, Kazuta; Mizuno, Emiko; Hara, Natsue; Orito, Takeo; Kamei, Tetsuya; Koga, Sukehiko

2000-01-01

The International Electrotechnical Commission, IEC provided in its standard IEC 60601-1-3 (1994) to prevent the use during radioscopic irradiation of focal spot to skin distances less than 20 cm if the X-RAY EQUIPMENT is specified for RADIOSCOPY during surgery or 30 cm for other specified applications. This standard was reflected in the Japanese Industrial Standard JIS Z 4701-1997, which provided the minimum distance from focal spot to skin to be 30 cm for the use of a fluoroscopic and radiographic table (Under-table type). However, JIS had formerly provided the minimum distance to be 40 cm and so does the current Medical Treatment Law. The draft revision for the Medical Treatment Law currently discussed has consideration to adopt the value 30 cm in accordance with the current JIS. Our research intended to investigate the impact on the entrance surface dose for the change of the focal spot to skin distance from 40 cm to 30 cm. The result was 20-30% increase of the entrance surface dose for the focal spot to skin distance 30 cm. Taking patient exposure dose into account, we need further and more sufficient discussion with this result before adopting this value to the Medical Treatment Law. (author)

Patient doses in digital cardiac imaging

International Nuclear Information System (INIS)

Huda, W.; Ogden, K.M.; Roskopf, M.L.; Phadke, K.

2001-01-01

In this pilot study, we obtained estimates of entrance skin doses and the corresponding effective doses to patients undergoing digital cardiac imaging procedures on a GE Advantx LC/LP Plus system. Data were obtained for six patients undergoing diagnostic examinations and six patients who had interventional procedures. For each patient examination, radiographic techniques for fluoroscopic and digital cine imaging were recorded, together with the irradiation geometry. The projection with the highest exposure resulted in an average skin dose of 0.64 ± 0.41 Gy (maximum of 1.6 Gy). The average patient skin doses taking into account overlapping projections was 1.1 ± 0.8 Gy (maximum of 3.0 Gy). The exposure area product (EAP) incident on the patient was converted into the energy imparted to the patient and the corresponding effective dose. The average patient effective dose was 28 ± 14 mSv (maximum 62 mSv), with the resultant average fatal cancer risk estimated to be of the order of 8x10 -3 . Average doses for interventional procedures in cardiac imaging are higher than those associated with diagnostic examinations by approximately 50%. (author)

Repair of skin damage during fractionated irradiation with gamma rays and low-LET carbon ions

International Nuclear Information System (INIS)

Ando, Koichi; Koike, Sachiko; Uzawa, Akiko; Takai, Nobuhiko; Fukawa, Takeshi; Furusawa, Yoshiya; Aoki, Mizuho; Hirayama, Ryoichi

2006-01-01

In clinical use of carbon-ion beams, a deep-seated tumor is irradiated with a Spread-Out Bragg peak (SOBP) with a high-linear energy transfer (LET) feature, whereas surface skin is irradiated with an entrance plateau, the LET of which is lower than that of the peak. The repair kinetics of murine skin damage caused by an entrance plateau of carbon ions was compared with that caused by photons using a scheme of daily fractionated doses followed by a top-up dose. Right hind legs received local irradiations with either 20 keV/μm carbon ions or γ rays. The skin reaction of the irradiated legs was scored every other day up to Day 35 using a scoring scale that consisted of 10 steps, ranging from 0.5 to 5.0. An isoeffect dose to produce a skin reaction score of 3.0 was used to obtain a total dose and a top-up dose for each fractionation. Dependence on a preceding dose and on the time interval of a top-up dose was examined using γ rays. For fractionated γ rays, the total dose linearly increased while the top-up dose linearly decreased with an increase in the number of fractions. The magnitude of damage repair depended on the size of dose per fraction, and was larger for 5.2 Gy than 12.5 Gy. The total dose of carbon ions with 5.2 Gy per fraction did not change till 2 fractions, but abruptly increased at the 3rd fraction. Factors such as rapid repopulation, induced repair and cell cycle synchronization are possible explanations for the abrupt increase. As an abrupt increase/decrease of normal tissue damage could be caused by changing the number of fractions in carbon-ion radiotherapy, we conclude that, unlike photon therapy, skin damage should be carefully studied when the number of fractions is changed in new clinical trials. (author)

A novel method for patient exit and entrance dose prediction based on water equivalent path length measured with an amorphous silicon electronic portal imaging device

Science.gov (United States)

Kavuma, Awusi; Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2010-01-01

In vivo dosimetry is one of the quality assurance tools used in radiotherapy to monitor the dose delivered to the patient. Electronic portal imaging device (EPID) images for a set of solid water phantoms of varying thicknesses were acquired and the data fitted onto a quadratic equation, which relates the reduction in photon beam intensity to the attenuation coefficient and material thickness at a reference condition. The quadratic model is used to convert the measured grey scale value into water equivalent path length (EPL) at each pixel for any material imaged by the detector. For any other non-reference conditions, scatter, field size and MU variation effects on the image were corrected by relative measurements using an ionization chamber and an EPID. The 2D EPL is linked to the percentage exit dose table, for different thicknesses and field sizes, thereby converting the plane pixel values at each point into a 2D dose map. The off-axis ratio is corrected using envelope and boundary profiles generated from the treatment planning system (TPS). The method requires field size, monitor unit and source-to-surface distance (SSD) as clinical input parameters to predict the exit dose, which is then used to determine the entrance dose. The measured pixel dose maps were compared with calculated doses from TPS for both entrance and exit depth of phantom. The gamma index at 3% dose difference (DD) and 3 mm distance to agreement (DTA) resulted in an average of 97% passing for the square fields of 5, 10, 15 and 20 cm. The exit dose EPID dose distributions predicted by the algorithm were in better agreement with TPS-calculated doses than phantom entrance dose distributions.

Technical basis for beta skin dose calculations at the Y-12 Plant

International Nuclear Information System (INIS)

Thomas, J.M.; Bogard, R.S.

1994-03-01

This report describes the methods for determining shallow dose equivalent to workers at the Oak Ridge Y-12 Plant from skin contamination detected by survey instrumentation. Included is a discussion of how the computer code VARSKIN is used to calculate beta skin dose and how the code input parameters affect skin dose calculation results. A summary of Y-12 Plant specific assumptions used in performing VARSKIN calculations is presented. Derivations of contamination levels that trigger the need for skin dose assessment are given for both enriched and depleted uranium with the use of Y-12 Plant site-specific survey instruments. Department of Energy recording requirements for nonuniform exposure of the skin are illustrated with sample calculations

Multilayer detector for measuring absorbed dose in skin

International Nuclear Information System (INIS)

Osanov, D.P.; Panova, V.P.; Shaks, A.I.

1985-01-01

A method of skin dosimetry using multilayer dosimeters is described that allows the skin-depth distribution of absorbed dose to be estimated. A method of quantitative estimation and prediction of the degree of skin radiation damage using a three-layer dosimeter is demonstrated. Dosimeters are holders of tissue-equivalent material that contain photographic film, a scintillator, thermoluminophor, or any other radiation-sensitive element

Measurement and comparison of skin dose using OneDose MOSFET and Mobile MOSFET for patients with acute lymphoblastic leukemia.

Science.gov (United States)

Mattar, Essam H; Hammad, Lina F; Al-Mohammed, Huda I

2011-07-01

Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to bone marrow transplant. It is involved in the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore measuring and monitoring the skin dose during the treatment is important. Two kinds of metal oxide semiconductor field effect transistor (OneDose MOSFET and mobile MOSEFT) dosimeter are used during the treatment delivery to measure the skin dose to specific points and compare it with the target prescribed dose. The objective of this study was to compare the variation of skin dose in patients with acute lymphatic leukemia (ALL) treated with total body irradiation (TBI) using OneDose MOSFET detectors and Mobile MOSFET, and then compare both results with the target prescribed dose. The measurements involved 32 patient's (16 males, 16 females), aged between 14-30 years, with an average age of 22.41 years. One-Dose MOSFET and Mobile MOSFET dosimetry were performed at 10 different anatomical sites on every patient. The results showed there was no variation between skin dose measured with OneDose MOSFET and Mobile MOSFET in all patients. Furthermore, the results showed for every anatomical site selected there was no significant difference in the dose delivered using either OneDose MOSFET detector or Mobile MOSFET as compared to the prescribed dose. The study concludes that One-Dose MOSFET detectors and Mobile MOSFET both give a direct read-out immediately after the treatment; therefore both detectors are suitable options when measuring skin dose for total body irradiation treatment.

A simplified model for predicting skin dose received by patients from ...

African Journals Online (AJOL)

Use of ionising radiation in any sector requires doses to be kept as low as reasonable achievable (ARALA). Thus, in keeping radiation dose to skin from diagnostic X-rays, as low as is required by this philosophy, it is useful to obtain an estimate of skin dose before the actual dose is administered. The aim of this paper is to ...

Evaluation of Patient Radiation Dose during Cardiac Interventional Procedures: What Is the Most Effective Method?

International Nuclear Information System (INIS)

Chida, K.; Saito, H.; Ishibashi, T.; Zuguchi, M.; Kagaya, Y.; Takahashi, S.

2009-01-01

Cardiac interventional radiology has lower risks than surgical procedures. This is despite the fact that radiation doses from cardiac intervention procedures are the highest of any commonly performed general X-ray examination. Maximum radiation skin doses (MSDs) should be determined to avoid radiation-associated skin injuries in patients undergoing cardiac intervention procedures. However, real-time evaluation of MSD is unavailable for many cardiac intervention procedures. This review describes methods of determining MSD during cardiac intervention procedures. Currently, in most cardiac intervention procedures, real-time measuring of MSD is not feasible. Thus, we recommend that physicians record the patient's total entrance skin dose, such as the dose at the interventional reference point when it can be monitored, in order to estimate MSD in intervention procedures

Assessment of radiological parameters and patient dose audit using semi-empirical model

International Nuclear Information System (INIS)

Olowookere, C.J.; Onabiyi, B.; Ajumobi, S. A.; Obed, R.I.; Babalola, I. A.; Bamidele, L.

2011-01-01

Risk is associated with all human activities, medical imaging is no exception. The risk in medical imaging is quantified using effective dose. However, measurement of effective dose is rather difficult and time consuming, therefore, energy imparted and entrance surface dose are obtained and converted into effective dose using the appropriate conversion factors. In this study, data on exposure parameters and patient characteristics were obtained during the routine diagnostic examinations for four common types of X-ray procedures. A semi-empirical model involving computer software Xcomp5 was used to determine energy imparted per unit exposure-area product, entrance skin exposure(ESE) and incident air kerma which are radiation dose indices. The value of energy imparted per unit exposure-area product ranges between 0.60 and 1.21x 10 -3 JR -1 cm -2 and entrance skin exposure range from 5.07±1.25 to 36.62±27.79 mR, while the incident air kerma range between 43.93μGy and 265.5μGy. The filtrations of two of the three machines investigated were lower than the standard requirement of CEC for the machines used in conventional radiography. The values of and ESE obtained in the study were relatively lower compared to the published data, indicating that patients irradiated during the routine examinations in this study are at lower health risk. The energy imparted per unit exposure- area product could be used to determine the energy delivered to the patient during diagnostic examinations, and it is an approximate indicator of patient risk.

Monte Carlo skin dose simulation in intraoperative radiotherapy of breast cancer using spherical applicators

Science.gov (United States)

Moradi, F.; Ung, N. M.; Khandaker, M. U.; Mahdiraji, G. A.; Saad, M.; Malik, R. Abdul; Bustam, A. Z.; Zaili, Z.; Bradley, D. A.

2017-08-01

The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators. Highlights: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin

Report of task group on the biological basis for dose limitation in the skin

International Nuclear Information System (INIS)

1989-08-01

Researchers have drawn attention to what they consider inconsistencies in the manner in which ICRP have considered skin in relation to the effective dose equivalent. They urge that the dose to the skin should be considered routinely for inclusion in the effective dose equivalent in the context of protection of individuals and population groups. They note that even with a weighting factor of only 0.01 that the dose to the skin can be a significant contributor to the effective dose equivalent including skin for practical exposure conditions. In the case of many exposures the risk to the skin can be ignored but exposure in an uniformly contaminated cloud that might occur with 85 Kr the dose to the skin could contribute 60% of the stochastic risk if included in the effective dose equivalent with a W T of 0.01. Through the years and even today the same questions about radiation effects in the skin and dosimetry keep being asked. This report collates the available data and current understanding of radiation effects on the skin, and may make it possible to estimate risks more accurately and to improve the approach to characterizing skin irradiations. 294 refs., 29 figs

Additional radiation dose to population due to X-ray diagnostic procedures

International Nuclear Information System (INIS)

Chougule, A.

2006-01-01

Full text of publication follows: Discovery of X rays has revolutionised the medical diagnosis but the fact that the diagnostic radiological procedures contribute about 80 to 90 % of the radiation dose to population as compared to other man made radiation sources cannot be ignored especially when X ray diagnostic facilities are being made available to larger section of the society. The estimated frequency of radiological procedures in India is 12,000 procedures/ year/100,000 population, though it is quite less as compared to developed countries, its increasing day by day. As part of the project, a radiation protection survey of X ray installations and patient radiation dose measurement during various radiological procedures was undertaken. 193 X ray installations were surveyed and the radiation doses received by the patient during various radiological procedure was measured. For measurement of radiation doses, CaSO 4 : Dy thermoluminescence (T.L.) discs of size 13.3 mm diameter and 0.8 mm thickness were used. Pre annealed T.L. discs were fixed by adhesive tape on the patient skin at the center of entrance beam before the exposure. After exposure the T.L. discs were estimated f or entrance skin dose during that particular projection/ examination. 10,000 measurements at different centers during various radiological procedures were done. It was found that chest radiography accounts for 37 % of all radiological procedures and further it was observed that 70 % of the chest X rays were normal with out any pathology indicating scope for curtailing the unwarranted radiological procedures. The special investigations like barium swallow, barium meal and fallow through accounts for about 1.5 % of the total radiological procedures. The entrance skin dose [E.S.D.] during chest radiography was 0.3 + 0.1 mGy where as during K.U.B. and cervical spine radiography it was 6.2 + 1.1 mGy and 5.1 + 0.9 mGy respectively. The details of frequency of various radiological procedures and the

Guideline values for skin decontamination measures based on nuclidspecific dose equivalent rate factors

International Nuclear Information System (INIS)

Pfob, H.; Heinemann, G.

1992-01-01

Corresponding dose equivalent rate factors for various radionuclides are now available for determining the skin dose caused by skin contamination. These dose equivalent rate factors take into account all contributions from the types of radiation emitted. Any limits for skin decontamination measures are nowhere contained or determined yet. However, radiological protection does in practice require at least guideline values in order to prevent unsuitable or detrimental measures that can be noticed quite often. New calculations of dose equivalent rate factors for the skin now make the recommendation of guideline values possible. (author)

MO-D-213-04: The Proximity to the Skin of PTV Affects PTV Coverage and Skin Dose for TomoTherapy

Energy Technology Data Exchange (ETDEWEB)

Reynolds, T; Higgins, P; Watanabe, Y [University of Minnesota, Minneapolis, MN (United States)

2015-06-15

Purpose: The proximity to the skin surface of the PTV for the patients with skin disease could be a concern in terms of the PTV coverage and actual surface dose (SD). IMRT optimization algorithms increase the beam intensity close to the skin in order to compensate for lack of scattering material, leading to enhanced SD but potential hot spots. This study aims to investigate the effect of PTV proximity to the skin on planning and measured SD Methods: All measurements were done for 6 MV X-ray beam of Helical TomoTherapy. An anthropomorphic phantom was scanned in a CT simulator in a routine manner with thermoplastic mask immobilization. PTVs were created with varying distances to the skin of 0 mm -(PTV1), 1 mm- (PTV2), 2 mm-(PTV3) and 3 mm-(PTV4). Also, a 5 mm bolus was used with PTV1 (PTV5). All planning constraints were kept the same in all studies (hard constraint: 95% of the prescription dose covered 95% of the PTV). Gafchromic film (EBT3) was placed under the mask on the phantom surface, and the resulting dose was estimated using RIT software. Results: Optimizing the dose using different PTVs lead to average planned target doses of 10.8, 10.3, 10.2, 10.3 and 10.0 Gy, with maximum doses 12.2, 11.2, 11.1, 11.1 and 10.0 Gy for PTV1, PTV2, PTV3, PTV4 and PTV5, respectively. EBT3 measurements indicated a significant decrease of SD with skin distance by 12.7% (PTV1), 21.9% (PTV2), 24.8% (PTV3) and 28.4% (PTV4) comparing to prescription dose. Placement of a 5 mm bolus on the phantom surface resulted in a SD close to prescribed (+0.5%). Conclusion: This work provides a clear demonstration of the relationship between the skin dose and the PTV to the skin distance. The results indicate the necessity of a bolus even for TomoTherapy when high skin dose is required.

MO-D-213-04: The Proximity to the Skin of PTV Affects PTV Coverage and Skin Dose for TomoTherapy

International Nuclear Information System (INIS)

Reynolds, T; Higgins, P; Watanabe, Y

2015-01-01

Purpose: The proximity to the skin surface of the PTV for the patients with skin disease could be a concern in terms of the PTV coverage and actual surface dose (SD). IMRT optimization algorithms increase the beam intensity close to the skin in order to compensate for lack of scattering material, leading to enhanced SD but potential hot spots. This study aims to investigate the effect of PTV proximity to the skin on planning and measured SD Methods: All measurements were done for 6 MV X-ray beam of Helical TomoTherapy. An anthropomorphic phantom was scanned in a CT simulator in a routine manner with thermoplastic mask immobilization. PTVs were created with varying distances to the skin of 0 mm -(PTV1), 1 mm- (PTV2), 2 mm-(PTV3) and 3 mm-(PTV4). Also, a 5 mm bolus was used with PTV1 (PTV5). All planning constraints were kept the same in all studies (hard constraint: 95% of the prescription dose covered 95% of the PTV). Gafchromic film (EBT3) was placed under the mask on the phantom surface, and the resulting dose was estimated using RIT software. Results: Optimizing the dose using different PTVs lead to average planned target doses of 10.8, 10.3, 10.2, 10.3 and 10.0 Gy, with maximum doses 12.2, 11.2, 11.1, 11.1 and 10.0 Gy for PTV1, PTV2, PTV3, PTV4 and PTV5, respectively. EBT3 measurements indicated a significant decrease of SD with skin distance by 12.7% (PTV1), 21.9% (PTV2), 24.8% (PTV3) and 28.4% (PTV4) comparing to prescription dose. Placement of a 5 mm bolus on the phantom surface resulted in a SD close to prescribed (+0.5%). Conclusion: This work provides a clear demonstration of the relationship between the skin dose and the PTV to the skin distance. The results indicate the necessity of a bolus even for TomoTherapy when high skin dose is required

Skin and gonadal dose reduction during hip radiography of the bull

International Nuclear Information System (INIS)

Wood, A.K.W.; Blockey, deB.; Reynolds, K.M.; Leith, I.S.; Burns, P.A.

1979-01-01

Radiology is being used to an increasing extent in the clinical diagnosis of hip lameness in bulls. Consequent gonadal doses may have important implications in later breeding programmes. Skin and gonadal doses were recorded during hip radiography of 18 bulls. An additional 0.13 mm copper filtration reduced skin dose by more than one third, but had no effect on gonadal dose. The average radiation dose to the gonads was approximately halved by completely surrounding the scrotum with lead sheeting 0.95 mm in thickness. (author)

Response of pig skin to fractionated radiation doses

International Nuclear Information System (INIS)

Wiernik, G.; Hopewell, J.W.; Patterson, T.J.S.; Young, C.M.A.; Foster, J.L.

1977-01-01

The individual components of a fractionated course of irradiation treatment have been considered separately. Methods of accurate measurement of individual parameters has brought to light different interpretations of the observations. Reasons are given for the necessity of having a radiobiological model which has a direct relevance to the clinical situation. Results are reported for fractionated regimes of irradiation in which the dose has been varied above and below normal tissue tolerance which has been equated with clinical skin necrosis. The components of the acute skin reaction, erythema, pigmentation and desquamation have been analysed separately and their contribution as a method of measurement assessed. Initially, the range of numerical scores attributed to erythema did not reach the scores attributed to necrosis but we now believe that radiation damage expressed as erythema can move directly into necrosis without passing through desquamation. Desquamation, on the other hand, only became a useful parameter at higher dose levels; it has also been shown to be a component associated with skin breakdown. Pigmentation showed no dose response at the dose levels employed in our experiments and it is our belief that this is due to this system being fully saturated under these circumstances. Measurement of the late radiation reaction in the skin has been considered in detail and our results have been expressed by comparing the relative lengths of irradiated and control fields in the same pig. From these findings iso-effect graphs have been constructed and time and fractionation factors have been derived. (author)

Calculational Tool for Skin Contamination Dose Assessment

CERN Document Server

Hill, R L

2002-01-01

Spreadsheet calculational tool was developed to automate the calculations preformed for dose assessment of skin contamination. This document reports on the design and testing of the spreadsheet calculational tool.

Dose-response relationships and threshold levels in skin and respiratory allergy

NARCIS (Netherlands)

Arts, J.H.E.; Mommers, C.; Heer, C.de

2006-01-01

A literature study was performed to evaluate dose-response relationships and no-effect levels for sensitization and elicitation in skin- and respiratory allergy. With respect to the skin, dose-response relationships and no-effect levels were found for both intradermal and topical induction, as well

Population dose assessment from radiodiagnosis in Portugal

International Nuclear Information System (INIS)

Serro, R.; Carreiro, J.V.; Galvao, J.P.; Reis, R.

1992-01-01

A survey of radiodiagnostic installations was carried out in Portugal covering 75 premises including public hospitals, local and regional public health centres. A total of 175 X ray tubes was surveyed using the new NEXT methodology covering data on premises, tube and operator, and projection. Average value of voltage, current-time product, HVL, ratio of beam area to film area and source to film distance for the eleven most frequent projections are reported as well as the skin entrance exposure and the doses to some organs. The weighted average dose values per projection and for the different organs allowed an estimate of the whole-body dose per caput. From the gonadal doses the genetic significant dose was also estimated

Evaluation of skin entrance radiation dose in pediatric patients undergoing chest X-rays exams

International Nuclear Information System (INIS)

Gabardo, Farly Piantini

2016-01-01

The aim of this work was to estimate the incident air kerma of lateral (LAT) and anterior-posterior (AP) together with posterior-anterior (PA) projection chest X-ray exams in one of the largest pediatric hospitals in Brazil. Dosimetric results are accompanied with the detailed analysis of patient characteristics and radiographer strategy. The exams of 225 (119 male and 106 female) patients were studied and 389 X-ray exams (200 AP/PA projections and 189 LAT projections) of pediatric patients were acquired. Patient thickness can be restored from age, height or weight with the uncertainty of ∼20-30%. Very slight correlation between the patient dose and thickness was observed with the difference in dose for patients of the same thickness reaching 4 times. By standardization of radiological protocols, it should be possible to keep dose within the intervals 50-100 μGy for LAT projection and 40-80 μGy for AP/PA projection. The dose values are lower than those recommended by major European guidelines to good practice. (author)

Patient dose measurement and dose reduction in East Anglia (UK)

International Nuclear Information System (INIS)

Wade, J.P.; Goldstone, K.E.; Dendy, P.P.

1995-01-01

At the end of 1990 a programme of patient dose measurements was introduced as part of the quality assurance service already provided for X ray departments throughout the East Anglian Health Region (UK). Thermoluminescence dosemeters (TLDs) were used to measure over 1200 skin entrance surface doses for four common radiographic views in 33 hospitals in both the NHS and private sector. The four views were chosen to cover a wide range of equipment and techniques. The data collected have enabled Regional reference doses to be set which, for all views considered, fall below the National Radiological Protection Board (NRPB) Reference levels. In departments which exceeded reference levels, techniques were reviewed, improvements suggested and doses re-measured, in accordance with the recommended procedure for patient dose audit. A significant finding was that, given appropriate controls, X ray departments in the private sector could achieve the same acceptably low doses as NHS departments. (Author)

Dose-modifying factors for skin ulceration in mouse legs exposed to gamma rays

International Nuclear Information System (INIS)

Masuda, Kouji; Miyoshi, Makoto; Uehara, Satoru; Omagari, Junichi; Withers, H.R.

1996-01-01

To assess the dose-modifying factors for skin ulceration, the hind legs of mice were irradiated using gamma-rays of various doses in single exposures. The skin ulceration began to occur 2 months after irradiation, after early skin reactions such as wet desquamation, had healed completely. No new skin ulceration was observed more than 8 months after irradiation even though the observations were continued until 12 months post-irradiation. The ulceration dose 50 (UD50), a dose required to produce skin ulceration in from 2 to 8 months in 50% of the tested animals, was calculated for each treatment schedule. The preliminary shaving procedure reduced the UD50 dose to 0.85 that of the untreated controls. The ventral aspect of the hind leg was more radioresistant to single-dose irradiation than was to the dorsal aspect. The UD50 for the ventral aspect was 1.29 times that for the dorsal aspect when the skin had been previously shaved, and 1.46 times that for the unshaved control legs. The UD50 was 7 and 14% larger when mice were kept in the dorsal rather than the abdominal position during irradiation, for the preliminarily shaved and unshaved skin, respectively. (author)

Dose characteristics of total-skin electron-beam irradiation with six-dual electron fields

International Nuclear Information System (INIS)

Choi, Tae Jin; Kim, Jin Hee; Kim, Ok Bae

1998-01-01

To obtain the uniform dose at limited depth to entire surface of the body, the dose characteristics of degraded electron beam of the large target-skin distance and the dose distribution of the six-dual electron fields were investigated. The experimental dose distributions included the depth dose curve, spatial dose and attenuated electron beam were determined with 300 cm of Target-Skin Distance (TSD) and full collimator size (35x35 cm 2 on TSD 100 cm) in 4 MeV electron beam energy. Actual collimated field size of 105 cmx105 cm at the distance of 300 cm could include entire hemibody. A patient was standing on step board with hands up and holding the pole to stabilize his/her positions for the six-dual fields technique. As a scatter-degrader, 0.5 cm of acrylic plate was inserted at 20 cm from the body surface on the electron beam path to induce ray scattering and to increase the skin dose. The Full Width at Half Maximum(FWHM) of dose profile was 130 cm in large field of 105x105 cm 2 . The width of 100±10% of the resultant dose from two adjacent fields which were separated at 25 cm from field edge for obtaining the dose uniformity was extended to 186 cm. The depth of maximum dose lies at 5 mm and the 80% depth dose lies between 7 and 8 mm for the degraded electron beam by using the 0.5 cm thickness of acrylic absorber. Total skin electron beam irradiation (TSEBI) was carried out using the six dual fields has been developed at Stanford University. The dose distribution in TSEBI showed relatively uniform around the flat region of skin except the protruding and deeply curvatured portion of the body, which showed excess of dose at the former and less dose at the latter. The percent depth dose, profile curves and superimposed dose distribution were investigated using the degraded using the degraded electron beam through the beam absorber. The dose distribution obtained by experiments of TSEBI showed within±10% difference excepts the protruding area of skin which needs a

Late occurring lesions in the skin of rats after repeated doses of X-rays

International Nuclear Information System (INIS)

Hopewell, J.W.

1985-01-01

Late radiation damage, characterized by atrophy and necrosis in the skin and subcutaneous tissues, has been demonstrated in both the tail and feet of rats. The incidence of necrosis increased with total dose. These total doses, in the range 72-144 Gy, were given as 4-8 treatment of 18 Gy, each dose separated from the next by an interval of 28 days. This treatment protocol minimized acute epithelial skin reactions. The same regime applied to the skin on the back of rats resulted in a very severe acute reaction occurring after the second to fifth dose of 18 Gy. This was surprising since back skin, like tail skin, is less sensitive to large single doses of radiation than that of the foot. The late radiation reaction in the foot and tail of rats are compared and contrasted with other attempts to assess late effects in rodent skin and with late changes seen in pig skin. (author)

Creation and clinical application of real-time dose monitor using dose area product meter

International Nuclear Information System (INIS)

Matsubara, Kosuke; Uoyama, Yoshinori; Iida, Hiroji; Mizushima, Takashi

2004-01-01

The management of patient dose has become more of an issue in recent years. Dose can be determined non-invasively and in real time through the use of a dose area product meter, but it is the area dose value that is obtained. Therefore, we created a program that estimates entrance skin dose (ESD) in real time from area dose values obtained during procedures. We used Microsoft Visual C++ 6.0 (Standard Edition) for the programming language and C language for the programming environment. The value was a maximum 285.4 mGy at ileus tube insertion when measuring ESD for radiography of the digestive organ and non-vascular type interventional radiology (IVR) using the created program and seeking the average according to the procedures. The program that we created can be considered valid for monitoring ESD correctly and in real time. (author)

Implications of the quadratic cell survival curve and human skin radiation ''tolerance doses'' on fractionation and superfractionation dose selection

International Nuclear Information System (INIS)

Douglas, B.G.

1982-01-01

An analysis of early published multifraction orthovoltage human acute skin irradiation tolerance isoeffect doses is presented. It indicates that human acute skin radiation reactions may result from the repetition, with each dose fraction, of a cell survival curve of the form: S = e/sup -(αD + βD 2 )/). The analysis also shows no need for an independent proliferation related time factor for skin, for daily treatments of six weeks or less in duration. The value obtained for the constant β/α for orthovoltage irradiation from these data is 2.9 x 10 -3 rad -1 for the cell line determining acute skin tolerance. A radiation isoeffect relationship, based on the quadratic cell survival curve, is introduced for human skin. This relationship has some advantages over the nominal standard dose (NSD). First, its use is not restricted to tolerance level reactions. Second, a modification of the relationship, which is also introduced, may be employed in the selection of doses per treatment when irradiation dose fractions are administered at short intervals where repair of sublethal injury is incomplete

Objective method to report planner-independent skin/rib maximal dose in balloon-based high dose rate (HDR) brachytherapy for breast cancer

International Nuclear Information System (INIS)

Kim, Yongbok; Trombetta, Mark G.

2011-01-01

Purpose: An objective method was proposed and compared with a manual selection method to determine planner-independent skin and rib maximal dose in balloon-based high dose rate (HDR) brachytherapy planning. Methods: The maximal dose to skin and rib was objectively extracted from a dose volume histogram (DVH) of skin and rib volumes. A virtual skin volume was produced by expanding the skin surface in three dimensions (3D) external to the breast with a certain thickness in the planning computed tomography (CT) images. Therefore, the maximal dose to this volume occurs on the skin surface the same with a conventional manual selection method. The rib was also delineated in the planning CT images and its maximal dose was extracted from its DVH. The absolute (Abdiff=|D max Man -D max DVH |) and relative (Rediff[%]=100x(|D max Man -D max DVH |)/D max DVH ) maximal skin and rib dose differences between the manual selection method (D max Man ) and the objective method (D max DVH ) were measured for 50 balloon-based HDR (25 MammoSite and 25 Contura) patients. Results: The average±standard deviation of maximal dose difference was 1.67%±1.69% of the prescribed dose (PD). No statistical difference was observed between MammoSite and Contura patients for both Abdiff and Rediff[%] values. However, a statistically significant difference (p value max >90%) compared with lower dose range (D max <90%): 2.16%±1.93% vs 1.19%±1.25% with p value of 0.0049. However, the Rediff[%] analysis eliminated the inverse square factor and there was no statistically significant difference (p value=0.8931) between high and low dose ranges. Conclusions: The objective method using volumetric information of skin and rib can determine the planner-independent maximal dose compared with the manual selection method. However, the difference was <2% of PD, on average, if appropriate attention is paid to selecting a manual dose point in 3D planning CT images.

Total skin electron irradiation: evaluation of dose uniformity throughout the skin surface

International Nuclear Information System (INIS)

Anacak, Yavuz; Arican, Zumre; Bar-Deroma, Raquel; Tamir, Ada; Kuten, Abraham

2003-01-01

In this study, in vivo dosimetic data of 67 total skin electron irradiation (TSEI) treatments were analyzed. Thermoluminescent dosimetry (TLD) measurements were made at 10 different body points for every patient. The results demonstrated that the dose inhomogeneity throughout the skin surface is around 15%. The homogeneity was better at the trunk than at the extratrunk points, and was worse when a degrader was used. There was minimal improvement of homogeneity in subsequent days of treatment

Radiation doses of patients and urologists during percutaneous nephrolithotomy

Energy Technology Data Exchange (ETDEWEB)

Safak, M; Gogus, C [Faculty of Medicine, Ibni Sina Hospital, Department of Urology, Ankara University, 06450 Samanpazari, Ankara (Turkey); Olgar, T; Bor, D; Berkmen, G [Faculty of Engineering, Department of Physics Engineering, Ankara University, 06100, Tandogan, Ankara (Turkey)], E-mail: olgar@eng.ankara.edu.tr

2009-09-01

Renal stones can be treated either by extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PCNL). Increasing use of fluoroscopic exposure for access and to detect stone location during PCNL make the measurement of patient and staff doses important. The main objective of this work was to assess patient and urologist doses for the PCNL examination. We used the tube output technique for determination of patient doses (n = 20) and lithium fluoride thermoluminescent dosimeter (TLD) chips for urologist dose measurements. The TLD technique was also used for some patient dose measurements (n = 7) for comparison with the tube output technique. Mean entrance skin doses of 191 and 117 mGy were measured by the tube output technique for anterior-posterior (AP) and right anterior oblique (RAO) 30 deg./left anterior oblique (LAO) 30 deg. projections, respectively. The mean urologist doses for eye, finger and collar were measured as 26, 33.5 and 48 {mu}Gy per procedure, respectively. The mean effective dose per procedure for the urologist was 12.7 {mu}Sv. None of the individual skin dose results approach deterministic levels.

Radiation doses of patients and urologists during percutaneous nephrolithotomy

International Nuclear Information System (INIS)

Safak, M; Gogus, C; Olgar, T; Bor, D; Berkmen, G

2009-01-01

Renal stones can be treated either by extracorporeal shock wave lithotripsy (ESWL) or percutaneous nephrolithotomy (PCNL). Increasing use of fluoroscopic exposure for access and to detect stone location during PCNL make the measurement of patient and staff doses important. The main objective of this work was to assess patient and urologist doses for the PCNL examination. We used the tube output technique for determination of patient doses (n = 20) and lithium fluoride thermoluminescent dosimeter (TLD) chips for urologist dose measurements. The TLD technique was also used for some patient dose measurements (n = 7) for comparison with the tube output technique. Mean entrance skin doses of 191 and 117 mGy were measured by the tube output technique for anterior-posterior (AP) and right anterior oblique (RAO) 30 deg./left anterior oblique (LAO) 30 deg. projections, respectively. The mean urologist doses for eye, finger and collar were measured as 26, 33.5 and 48 μGy per procedure, respectively. The mean effective dose per procedure for the urologist was 12.7 μSv. None of the individual skin dose results approach deterministic levels.

Correlation and uncertainties evaluation in backscattering of entrance surface air kerma measurements

Energy Technology Data Exchange (ETDEWEB)

Teixeira, G.J.; Sousa, C.H.S.; Peixoto, J.G.P., E-mail: gt@ird.gov.br [Instituto de Radioproteção e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

2017-07-01

The air kerma measurement is important to verify the applied doses in radiodiagnostic. The literature determines some methods to measure the entrance surface air kerma or entrance surface dose but some of this methods may increase the measurement with the backscattering. Were done setups of measurements to do correlations between them. The expanded uncertainty exceeded 5% for measurements with backscattering, reaching 8.36%, while in situations where the backscattering was avoided, the uncertainty was 3.43%. (author)

Skin Dose Equivalent Measurement from Neutron-Deficient Isotopes

International Nuclear Information System (INIS)

Hsu, Hsiao-Hua; Costigan, Steve A.; Romero, Leonard L.; Whicker, Jeffrey J.

1997-12-01

Neutron-deficient-isotopes decay via positron emission and/or electron capture often followed by x-ray, gamma-ray, and 0.511 MeV photons from positron annihilation. For cases of significant area and/or personnel contamination with these isotopes, determination of skin dose equivalent (SDE) is required by 10CFR835. For assessment of SDE, we evaluated the MICROSPEC-2(TM) system manufactured by Bubble Technology Industries of Canada which uses three different probes for dose measurement. We used two probes: (1) the X-probe which measures lower energy (4 - 120 keV) photon energy distributions and determines deep dose equivalent, SDE and dose equivalent to eyes, and (2) the B-probe which measures electron (positron) energy distributions, and determines skin dose equivalent. Also, the measured photon and beta spectra can be used to identify radioactive isotopes in the contaminated area. Measurements with several neutron-deficient sources showed that this system provided reasonably accurate SDE rate measurements when compared with calculated benchmark SDE rates with an average percent difference of 40%. Variations were expected because of differences between the assumed geometries used by MlCROSPEC-2 and the calculations when compared to the measurement conditions

Skin dose assessment in routine personnel beta/gamma dosimetry

International Nuclear Information System (INIS)

Christensen, P.

1980-01-01

Three alternative methods are outlined by which substantial improvements of the capabilities of existing routine monitoring systems for skin dose assessment can be obtained. The introduction of a supplementary skin dosemeter may be an attractive method for systems with badges that have a capability for an additional dosemeter already built-in. The two-side reading method has limited possibilities because of reduced accuracy for mixed radiation and technical difficulties in using it for TLD systems with planchet heating. The use of a boron diffused LiF layer for skin dose assessment seems to be most attractive method since the only modification needed here is replacement of a dosemeter. However the study of this method is so far only in a preliminary stage and further investigations are needed. (U.K.)

Patient doses in interventional cardiology procedures

International Nuclear Information System (INIS)

Domienik, J.; Papierz, S.; Jankowski, J.; Peruga, J.Z.

2008-01-01

In most countries of European Union legislation requires the determination of the total skin dose to patient resulting from interventional procedures to assess the risk of deterministic effect. To this end, various dose indicators like dose area product (DAP), cumulative dose (CD) and entrance dose at the patient plane (EFD) are used in clinical practice. The study aims at relating those dose indicators with doses ascribe to the most irradiated areas of the patient skin usually expressed in terms of local maximal skin dose (MSD). For the study the local MSD and related to their areas are investigated and compared for coronary angiography CA and intervention (PCI). Two methods implying radiographic films Kodak EDR2 and matrixes of thermoluminescent dosimeters (TLDs) are applied for direct measurements of dose distribution for selected procedures. Both methods are compared. Additionally, for patient dosimetry the following data: MSD, CD, EFD, fluoroscopy time (FT), number of acquired images, total DAP, fluoro-DAP and record-DAP were collected for randomly selected procedure. The statistical quantities like: median, 3 rd quartile, mean and standard deviation for all dosimetric parameters are determined. Preliminary study showed that the values of data collected for coronary procedures are in the ranges 0,7 - 27,3 min for fluoroscopy time, 50 - 350 Gy cm 2 for total DAP, 300 - 2000 mGy for CD, 140 - 2000 mGy for EFD and 100 - 1500 mGy for local maximal skin dose. For interventions the ranges are, accordingly 3,0 - 43,6 min , 25 - 450 Gy cm 2 , 270 - 6600 mGy, 80 - 2600 mGy and 80 - 1500 mGy. As a result of the study the correlations between dose indicators and local MSD are analyzed. The concentration of dose on irradiated films are going to be investigated in some detail as well. (author)

Skin dose measurements using MOSFET and TLD for head and neck patients treated with tomotherapy

International Nuclear Information System (INIS)

Kinhikar, Rajesh A.; Murthy, Vedang; Goel, Vineeta; Tambe, Chandrashekar M.; Dhote, Dipak S.; Deshpande, Deepak D.

2009-01-01

The purpose of this work was to estimate skin dose for the patients treated with tomotherapy using metal oxide semiconductor field-effect transistors (MOSFETs) and thermoluminescent dosimeters (TLDs). In vivo measurements were performed for two head and neck patients treated with tomotherapy and compared to TLD measurements. The measurements were subsequently carried out for five days to estimate the inter-fraction deviations in MOSFET measurements. The variation between skin dose measured with MOSFET and TLD for first patient was 2.2%. Similarly, the variation of 2.3% was observed between skin dose measured with MOSFET and TLD for second patient. The tomotherapy treatment planning system overestimated the skin dose as much as by 10-12% when compared to both MOSFET and TLD. However, the MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1% to 1.4%. MOSFETs may be used as a viable dosimeter for measuring skin dose in areas where the treatment planning system may not be accurate.

Skin dose measurements using MOSFET and TLD for head and neck patients treated with tomotherapy.

Science.gov (United States)

Kinhikar, Rajesh A; Murthy, Vedang; Goel, Vineeta; Tambe, Chandrashekar M; Dhote, Dipak S; Deshpande, Deepak D

2009-09-01

The purpose of this work was to estimate skin dose for the patients treated with tomotherapy using metal oxide semiconductor field-effect transistors (MOSFETs) and thermoluminescent dosimeters (TLDs). In vivo measurements were performed for two head and neck patients treated with tomotherapy and compared to TLD measurements. The measurements were subsequently carried out for five days to estimate the inter-fraction deviations in MOSFET measurements. The variation between skin dose measured with MOSFET and TLD for first patient was 2.2%. Similarly, the variation of 2.3% was observed between skin dose measured with MOSFET and TLD for second patient. The tomotherapy treatment planning system overestimated the skin dose as much as by 10-12% when compared to both MOSFET and TLD. However, the MOSFET measured patient skin doses also had good reproducibility, with inter-fraction deviations ranging from 1% to 1.4%. MOSFETs may be used as a viable dosimeter for measuring skin dose in areas where the treatment planning system may not be accurate.

Dosimetric Aspects of Personnel Skin Contamination by Radionuclides - Estimate of a Skin Dose, Monitoring and Interpretation of Results

International Nuclear Information System (INIS)

Husak, V.; Kleinbauer, K.

2001-01-01

Full text: On the basis of a critical comparison of literary data, tables are compiled of beta and gamma dose rate in mSvh -1 (kBqcm -1 ) to the basal layer of the skin at 0.07 mm depth from contamination by 75 radionuclides unsealed sources; radioactive substances are assumed to reside on the skin surface. The residence time needed for the estimate of the skin dose is calculated assuming that a residual activity per unit area of any radionuclide on the skin, which could not be removed by the repeated careful decontamination, is supposed to be eliminated with the biological half-life of 116 h as a consequence of the natural sloughing off of the skin. Radionuclides are divided into five groups according to the dose estimate in mSv (kBqcm -2 ): ≥250 (e.g. 32 P, 89 Sr, 137 Cs/ 137m Ba), 100-250 (e.g. 90 Y, 131 I, 186 Re), 10-100 (e.g. 35 S, 67 Ga, 200 Tl), 1-10 (e.g. 18 F, 51 Cr, 99m Tc), ≤1 (e.g. 63 Ni, 144 Pr, 238 U). If it is possible, doses can be determined more precisely by measuring the effective half-life of the residual activity on the contaminated area. Our dose estimates are approximately valid on the condition that, after decontamination, residual activity of radionuclides persists predominantly in the superficial layers of epidermis. This and further uncertainties connected with the dose assessment are discussed. Our tables can help to determine easily rough values of doses to personnel in contamination incidents and to interpret them in relation to regulatory derived limits. This work was supported by State Office for Nuclear Safety in Prague. (author)

Evaluation of entrance surface air kerma in pediatric chest radiography

International Nuclear Information System (INIS)

Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J.L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

2014-01-01

The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior–posterior (AP) and posterior–anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0–1 y, 1–5 y, 5–10 y, and 10–15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels. - Highlights: • The entrance surface air kerma of chest X-ray examinations in pediatric patients was estimated. • The data were analyzed for patients aged up to 15 y, stratified by age. • The doses of LAT examinations were 40% higher than of AP/PA because of kV used. • An increase in kV with a decrease in mAs leads to significant dose reduction

SU-E-I-55: The Contribution to Skin Dose Due to Scatter From the Patient Table and the Head Holder During Fluoroscopy

International Nuclear Information System (INIS)

Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D

2015-01-01

Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant

SU-E-I-55: The Contribution to Skin Dose Due to Scatter From the Patient Table and the Head Holder During Fluoroscopy

Energy Technology Data Exchange (ETDEWEB)

Islam, N; Xiong, Z; Vijayan, S; Rudin, S; Bednarek, D [Toshiba Stroke and Vascular Research Center, University at Buffalo, Buffalo, NY (United States)

2015-06-15

Purpose: To determine contributions to skin dose due to scatter from the table and head holder used during fluoroscopy, and also to explore alternative design material to reduce the scatter dose. Methods: Measurements were made of the primary and scatter components of the xray beam exiting the patient table and a cylindrical head holder used on a Toshiba Infinix c-arm unit as a function of kVp for the various beam filters on the machine and for various field sizes. The primary component of the beam was measured in air with the object placed close to the x-ray tube with an air gap between it and a 6 cc parallel-plate ionization chamber and with the beam collimated to a size just larger than the chamber. The primary plus scatter radiation components were measured with the object moved to a position in the beam next to the chamber for larger field sizes. Both sets of measurements were preformed while keeping the source-to-chamber distance fixed. The scatter fraction was estimated by taking the ratio of the difference between the two measurements and the reading that included both primary and scatter. Similar measurements were also made for a 2.3 cm thick Styrofoam block which could substitute for the patient support. Results: The measured scatter fractions indicate that the patient table as well as the head holder contributes an additional 10–16% to the patient entrance dose depending on field size. Forward scatter was reduced with the Styrofoam block so that the scatter fraction was about 4–5%. Conclusion: The results of this investigation demonstrated that scatter from the table and head holder used in clinical fluoroscopy contribute substantially to the skin dose. The lower contribution of scatter from Styrofoam suggests that there is an opportunity to redesign patient support accessories to reduce the skin dose. Partial support from NIH grant R01EB002873 and Toshiba Medical Systems Corporation Equipment Grant.

Comparison of entrance exposure and signal-to-noise ratio between an SBDX prototype and a wide-beam cardiac angiographic system

International Nuclear Information System (INIS)

Speidel, Michael A.; Wilfley, Brian P.; Star-Lack, Josh M.; Heanue, Joseph A.; Betts, Timothy D.; Van Lysel, Michael S.

2006-01-01

The scanning-beam digital x-ray (SBDX) system uses an inverse geometry, narrow x-ray beam, and a 2-mm thick CdTe detector to improve the dose efficiency of the coronary angiographic procedure. Entrance exposure and large-area iodine signal-to-noise ratio (SNR) were measured with the SBDX prototype and compared to that of a clinical cardiac interventional system with image intensifier (II) and charge coupled device (CCD) camera (Philips H5000, MRC-200 x-ray tube, 72 kWp max). Phantoms were 18.6-35.0 cm acrylic with an iohexol-equivalent disk placed at midthickness (35 mg/cm 2 iodine radiographic density). Imaging was performed at 15 frame/s, with the disk at mechanical isocenter and an 11-cm object-plane field width. The II/CCD system was operated in cine mode with automatic exposure control. With the SBDX prototype at maximum x-ray output (120 kVp, 24.3 kWp), the SBDX SNR was 107%-69% of the II/CCD SNR, depending on phantom thickness, and the SBDX entrance exposure rate was 10.7-9.3 R/min (9.4-8.2 cGy/min air kerma). For phantoms where an equal-kVp imaging comparison was possible (≥23.3 cm), the SBDX SNR ranged from 47% to 69% of the II/CCD SNR while delivering 6% to 9% of the II/CCD entrance exposure rate. From these measurements it was determined that the relative SBDX entrance exposure at equal SNR would be 31%-16%. Results were consistent with a model for relative entrance exposure at equal SNR, which predicted a 3-7 times reduction in entrance exposure due to SBDX's comparatively low scatter fraction (5.5%-8.1% measured, including off-focus radiation), high detector detective quantum efficiency (66%-73%, measured from 70 to 120 kVp), and large entrance field area (1.7x-2.3x, for the same object-plane field width). With improvements to the system geometry, detector, and x-ray source, SBDX technology is projected to achieve conventional cine-quality SNR over a full range of patient thicknesses, with 5-10 times lower skin dose

The establishment and use of dose reference levels in general paediatric radiology

International Nuclear Information System (INIS)

Marsden, P.J.; Hardwick, J.; Mencik, C.; McLaren, C.; Young, C.; Mashford, P.

2001-01-01

Diagnostic reference levels for general paediatric radiology have been established in terms of delivered exposure parameters rather than skin dose or dose-area product. With supporting measurements from equipment quality assurance and assumptions of standard patient sizes it was possible to derive reference levels in terms of entrance surface dose. This allowed comparison to be made with other published data. The reference levels for common examinations are presented for different age bands. There is a notable variation with patient age for some examinations which is not apparent in other published data. (author)

Measurement and estimation of maximum skin dose to the patient for different interventional procedures

International Nuclear Information System (INIS)

Cheng Yuxi; Liu Lantao; Wei Kedao; Yu Peng; Yan Shulin; Li Tianchang

2005-01-01

Objective: To determine the dose distribution and maximum skin dose to the patient for four interventional procedures: coronary angiography (CA), hepatic angiography (HA), radiofrequency ablation (RF) and cerebral angiography (CAG), and to estimate the definitive effect of radiation on skin. Methods: Skin dose was measured using LiF: Mg, Cu, P TLD chips. A total of 9 measuring points were chosen on the back of the patient with two TLDs placed at each point, for CA, HA and RF interventional procedures, whereas two TLDs were placed on one point each at the postero-anterior (PA) and lateral side (LAT) respectively, during the CAG procedure. Results: The results revealed that the maximum skin dose to the patient was 1683.91 mGy for the HA procedure with a mean value of 607.29 mGy. The maximum skin dose at the PA point was 959.3 mGy for the CAG with a mean value of 418.79 mGy; While the maximum and the mean doses at the LAT point were 704 mGy and 191.52 mGy, respectively. For the RF procedure the maximum dose was 853.82 mGy and the mean was 219.67 mGy. For the CA procedure the maximum dose was 456.1 mGy and the mean was 227.63 mGy. Conclusion: All the measured dose values in this study are estimated ones which could not provide the accurate maximum value because it is difficult to measure using a great deal of TLDs. On the other hand, the small area of skin exposed to high dose could be missed as the distribution of the dose is successive. (authors)

Association Between Maximal Skin Dose and Breast Brachytherapy Outcome: A Proposal for More Rigorous Dosimetric Constraints

International Nuclear Information System (INIS)

Cuttino, Laurie W.; Heffernan, Jill; Vera, Robyn; Rosu, Mihaela; Ramakrishnan, V. Ramesh; Arthur, Douglas W.

2011-01-01

Purpose: Multiple investigations have used the skin distance as a surrogate for the skin dose and have shown that distances 4.05 Gy/fraction. Conclusion: The initial skin dose recommendations have been based on safe use and the avoidance of significant toxicity. The results from the present study have suggested that patients might further benefit if more rigorous constraints were applied and if the skin dose were limited to 120% of the prescription dose.

Validation of radiosterilization dose of human skin dressings for burnt treatment: preliminary study

International Nuclear Information System (INIS)

Castro, E.

2008-01-01

Full text: Due to the need for better materials to treat burnt patients, the Peruvian Institute of Nuclear Energy (IPEN) and the Rosa Guerzoni Chambergo Tissue Bank are collaborating for developing human skin dressings. Skin was procured from living donors, who surgically were performed a dermolipectomy. Exclusion criteria, stated by the Peruvian Organization for Transplant and Donation were observed. Glycerolized human skin dressings were processed at the tissue bank and sent to IPEN, where the gamma irradiation sterilizing dose was determined. The purpose of this work is to validate the radiation sterilization dose delivered to human skin dressings using the IAEA Code of Practice for the Radiation Sterilization of Tissue Allografts: Requirements for Validation and Routine Control. A batch of human skin dressings was tested. Average values of bioburden present in ten samples was 30 UFC/item, obtaining a sub-sterilization dose of 4 kGy. Irradiations were performed in the GammacellExcel 220. Sterility tests performed fulfilled the requirements established by the Code, achieving a validated dose value of 19.7 kGy. This preliminary study, that should be repeated in two other batches of processed human skin, allows to diminish 25 kGy the sterilizing dose to the stated above dose value, in a frame of a quality assurance system that also comprises the processes held at tissue banks previous irradiation. It also permit the availability of these materials in Peruvian hospitals. (Author)

Monte Carlo simulation for radiation dose in children radiology

International Nuclear Information System (INIS)

Mendes, Hitalo R.; Tomal, Alessandra

2016-01-01

The dosimetry in pediatric radiology is essential due to the higher risk that children have in comparison to adults. The focus of this study is to present how the dose varies depending on the depth in a 10 year old and a newborn, for this purpose simulations are made using the Monte Carlo method. Potential differences were considered 70 and 90 kVp for the 10 year old and 70 and 80 kVp for the newborn. The results show that in both cases, the dose at the skin surface is larger for smaller potential value, however, it decreases faster for larger potential values. Another observation made is that because the newborn is less thick the ratio between the initial dose and the final is lower compared to the case of a 10 year old, showing that it is possible to make an image using a smaller entrance dose in the skin, keeping the same level of exposure at the detector. (author)

Maximum skin dose assessment in interventional cardiology: large area detectors and calculation methods

International Nuclear Information System (INIS)

Quail, E.; Petersol, A.

2002-01-01

Advances in imaging technology have facilitated the development of increasingly complex radiological procedures for interventional radiology. Such interventional procedures can involve significant patient exposure, although often represent alternatives to more hazardous surgery or are the sole method for treatment. Interventional radiology is already an established part of mainstream medicine and is likely to expand further with the continuing development and adoption of new procedures. Between all medical exposures, interventional radiology is first of the list of the more expansive radiological practice in terms of effective dose per examination with a mean value of 20 mSv. Currently interventional radiology contribute 4% to the annual collective dose, in spite of contributing to total annual frequency only 0.3% but considering the perspectives of this method can be expected a large expansion of this value. In IR procedures the potential for deterministic effects on the skin is a risk to be taken into account together with stochastic long term risk. Indeed, the International Commission on Radiological Protection (ICRP) in its publication No 85, affirms that the patient dose of priority concern is the absorbed dose in the area of skin that receives the maximum dose during an interventional procedure. For the mentioned reasons, in IR it is important to give to practitioners information on the dose received by the skin of the patient during the procedure. In this paper maximum local skin dose (MSD) is called the absorbed dose in the area of skin receiving the maximum dose during an interventional procedure

Calculation of entrance exposed area from recorded images in cardiac diagnostic and interventional procedures

International Nuclear Information System (INIS)

Bibbo, G.; Balman, D.

2000-01-01

With increasing number of interventional radiological procedures performed on patients of all ages, it is important to determine the skin entrance dose of patients to limit the side effects of radiation. In most cases the skin dose is measured using thermoluminescent detectors (TLD). However, these detectors need to be placed in the radiation field on the skin of the patient, which may interfere with the procedure. Also, not all radiological practices are equipped with TLD readers which are expensive or have staff with the appropriate knowledge and expertise to be able to make use of TLD. The alternative to TLD is to use the dose area product (DAP) measured with a diamentor fitted to the angiography x-ray equipment. The difficulties in using DAP to calculate skin dose is that the irradiated area of the skin is not known. The area could change in size and location during the procedure as the radiologist/medical specialist varies the collimation and region of interest. For angiography equipment the distance between the anode and image intensifier is variable, as is the height of the examination table. The only point of reference is the isocentre. With recorded images it is possible to determine the irradiated area of the patient at the isocentre plane using the stenosis algorithm. The recorded image is calibrated such that it corresponds to the physical size in the plane of the isocentre. For non-recorded images, it may be necessary to assume that collimation has not changed and that the irradiated area is the same as that shown on the recorded images. The Women's and Children's Hospital has a Toshiba DFP2000 Biplane Digital Imaging system used for all cardiac and general angiography and interventional procedures. With this system the exposure factors (kVp, mA, field sizes) are recorded with the images. The source to image distance (SID), magnification factor (calibration factor of the recorded images) and angle of rotation are displayed on the Display Panel of the

The minimal melanogenesis dose/minimal erythema dose ratio declines with increasing skin pigmentation using solar simulator and narrowband ultraviolet B exposure

DEFF Research Database (Denmark)

Ravnbak, Mette H; Philipsen, Peter A; Wulf, Hans Christian

2010-01-01

To investigate the relation between pre-exposure skin pigmentation and the minimal melanogenesis dose (MMD)/minimal erythema dose (MED) ratio after a single narrowband ultraviolet B (nUVB) and solar simulator (Solar) exposure.......To investigate the relation between pre-exposure skin pigmentation and the minimal melanogenesis dose (MMD)/minimal erythema dose (MED) ratio after a single narrowband ultraviolet B (nUVB) and solar simulator (Solar) exposure....

The difference in backscatter factors of diagnostic X-rays by the difference in the scattering medium and in the objective dose

International Nuclear Information System (INIS)

Kato, Hideki; Sakai, Keita; Uchiyama, Mizuki; Suzuki, Kentaro

2016-01-01

The diagnostic reference levels (DRLs) of the general X-ray radiography are defined by the absorbed dose of air at the entrance surface with backscattered radiation from a scattering medium. Generally, the entrance surface dose of the general X-ray radiography is calculated from measured air kerma of primary X-ray multiplied by a backscatter factor (BSF). However, the BSF data employed at present used water for scattering medium, and was calculated based on the water-absorbed dose by incident primary photons and backscattered photons from the scattering medium. In the calculation of air dose at the entrance surface defined in DRLs, there are no theoretical consistencies for using BSF based on water dose, and this may be a cause of calculation error. In this paper, we verified the difference in BSF by the difference in the scattering medium and by the difference in the objective dose by means of the Monte Carlo simulation. In this calculation, the scattering medium was set as water and the soft-tissue, and the objective dose was set as air dose, water dose, soft-tissue dose, and skin dose. The difference in BSF calculated by the respective combination was at most about 1.3% and was less than 1% in most cases. In conclusion, even if the entrance surface dose defined by DRLs of general X-ray radiography is calculated using BSF, which set both the scattering medium and the object substance of the absorbed dose as water, a so big error doesn't show. (author)

Technical specification of the NRPB thermoluminescent dosemeter used for the measurement of body dose and skin dose

CERN Document Server

Shaw, K B

1977-01-01

This report specifies the NRPB thermoluminescent dosemeter used for the measurement of radiation dose in tissue at a depth of 700 mg cm sup - sup 2 (body dose) and at a depth of 5-10 mg cm sup - sup 2 (skin dose).

Calculation of skin dose due to beta contamination using the new quantity of the ICRP 116: the local skin dose

International Nuclear Information System (INIS)

Bourgois, L.; Menard, S.; Comte, N.

2017-01-01

Values of the new protection quantity Local Skin Dose 'LSD', introduced by the International Commission on Radiological Protection (ICRP) Publication 116, were calculated for 134 β - or β + emitting radionuclides, using the Monte Carlo code MCNP6. Two types of source geometry are considered: a point source and disc-type surface contamination (the source is placed in contact with the skin). This new protection quantity is compared with the operational quantity H2 (0.07, 0 deg.), leading us to conclude that, in accordance with the rules of the ICRP, the operational quantity over-estimates the protection quantity to a reasonable extent, except in very rare cases for very low average beta energies. Thus, with the new skin model described in ICRP 116, there are no longer any major differences between the operational quantities and protection quantities estimated with the skin model described in ICRP 74. (authors)

Dosimetry studies with 32P source and correlation of skin and eye lens doses

International Nuclear Information System (INIS)

Kumar, Munish; Gaonkar, U.P.; Koul, D.K.; Datta, D.; Saxena, S.K.; Kumar, Yogendra; Dash, A.

2018-01-01

Beta particles are one of the major contributors toward skin and eye lens doses at facilities handling beta sources. These sources find applications in industry, pharmaceuticals as well as in brachytherapy applications. The beta particles having maximum (E max ) energy > 0.07 MeV are capable of delivering skin dose whereas beta particles having maximum (E max ) energy > 0.7 MeV may also contribute towards dose to eye lens. Studies are performed using 32 P beta source as its maximum beta energy (E max ) is such that for sources having (E max ) of 1.71 MeV or beyond, there can be substantial contribution towards dose to eye lens even the dose limit recommended for skin is followed

Evaluating the consistency of location of the most severe acute skin reaction and highest skin dose measured by thermoluminescent dosimeter during radiotherapy for breast cancer

Energy Technology Data Exchange (ETDEWEB)

Sun, Li-Min, E-mail: limin.sun@yahoo.com [Department of Radiation Oncology, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China); Huang, Chih-Jen [Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Department of Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Department of College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Chen, Hsiao-Yun [Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Chang, Gia-Hsin [Department of Radiation Oncology, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China); Tsao, Min-Jen [Department of General Surgery, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China)

2016-10-01

We conducted this prospective study to evaluate whether the location of the most severe acute skin reaction matches the highest skin dose measured by thermoluminescent dosimeter (TLD) during adjuvant radiotherapy (RT) for patients with breast cancer after breast conservative surgery. To determine whether TLD measurement can reflect the location of the most severe acute skin reaction, 80 consecutive patients were enrolled in this prospective study. We divided the irradiated field into breast, axillary, inframammary fold, and areola/nipple areas. In 1 treatment session when obvious skin reaction occurred, we placed the TLD chips onto the 4 areas and measured the skin dose. We determined whether the highest measured skin dose area is consistent with the location of the most severe skin reaction. The McNemar test revealed that the clinical skin reaction and TLD measurement are more consistent when the most severe skin reaction occurred at the axillary area, and the p = 0.0108. On the contrary, TLD measurement of skin dose is less likely consistent with clinical observation when the most severe skin reaction occurred at the inframammary fold, breast, and areola/nipple areas (all the p > 0.05). Considering the common site of severe skin reaction over the axillary area, TLD measurement may be an appropriate way to predict skin reaction during RT.

Skin dose estimation due to a contamination by a radionuclide β emitter: are doses equivalent good estimator of protection quantities?

International Nuclear Information System (INIS)

Bourgois, L.

2011-01-01

When handling radioactive β emitters, measurements in terms of personal dose equivalents H p (0.07) are used to estimate the equivalent dose limit to skin or extremities given by regulations. First of all, analytical expressions for individual dose equivalents H p (0.07) and equivalent doses to the extremities H skin are given for a point source and for contamination with a radionuclide β emitter. Second of all, operational quantities and protection quantities are compared. It is shown that in this case the operational quantities significantly overstate the protection quantities. For a skin contamination the ratio between operational quantities and protection quantities is 2 for a maximum β energy of 3 MeV and 90 for a maximum β energy of 150 keV. (author)

Dosimetry using Gafchromic XR-RV2 radiochromic films in interventional radiology

International Nuclear Information System (INIS)

Neocleous, A.; Yakoumakis, E.; Gialousis, G.; Dimitriadis, A.; Yakoumakis, N.; Georgiou, E.

2011-01-01

Patient dose measurements of local entrance dose to the skin have been carried out using radiochromic film (Gafchromic XR-RV2) in a sample of interventional procedures. The major aim of the work was to measure patient entrance dose from such examinations using Gafchromic XR-RV2. Forty-five various interventional procedures (including nephrostomies and urinary stenting, biliary stenting and percutaneous transhepatic biliary drainage (PTBD) and aorta stent grafting) were evaluated. Maximum entrance doses were 537±119 mGy in nephrostomies, 943±631 mGy in biliary stenting and PTBD and 2425±569 mGy in aorta stent grafting. Results indicate that all patients undergoing aorta stent grafting received skin dose above 1500 mGy, which means that there is an increasing potential to suffer radiation-induced skin injuries. The film provides dose mapping, the position of the skin area with highest dose and can be used for immediate qualitative and as well as for quantitative assessment of patient skin dose. (authors)

Evaluation of the breast plan using the TLD and MOSFET for the skin dose

Energy Technology Data Exchange (ETDEWEB)

Kim, Seon Myeong; Kim, Young Bum; Bak, Sang Yun; Lee, Sang Rok; Jeong, Se Young [Dept. of Radiation Oncology, Korea University Ansan Hospital, Ansan (Korea, Republic of)

2015-12-15

The measurement of skin dose is very important that treatment of breast cancer. On account of the cold or hot dose as compared with prescription dose, it is necessary to analyse the skin dose occurring during the various plan of the breast cancer treatment. At our hospital, we want to apply various analyses using a diversity of dosimeters to the breast cancer treatment. In the study, the anthropomorphic phantom is used to find out the dose difference of the skin(draining site), scar and others occurring from the tangential treatment plan of breast cancer. We took computed tomography scan of the anthropomorphic phantom and made plans for the treatment planing using open and wedge, Field-in-Field, Dose fluence. Using these, we made a comparative analysis of the dose date points by using the Eclipse. For the dose comparison, we place the anthropomorphic phantom in the treatment room and compared the measurement results by using the TLD and MOSFET on the dose data points. On the central point of treatment planing basis, the upward and downward skin dose measured by the MOSFET was the highest when the fluence was used. The skin dose of inner and outer was distinguished from the figure(5.7% - 10.3%) when the measurements were fulfilled by using TLD and MOSFET. The other side of breast dose was the lowest in the open beam, on the other hand, is highest in the Dose fluence plan. In the different kinds of treatment, the dose deviation of inner and outer was the highest, and so this was the same with the TLD and MOSFET measurement case. The outer deviation was highest in the TLD, and the Inner' was highest in the MOSFET. Skin dose in relation to the treatment plan was the highest in the planing using the fluence technique in general and it was supposed that the high dose had been caused by the movement of the MLC. There's some differences among the all the treatment planning, but the sites such as IM node occurring the lack of dose, scar, drain site are needed pay

Evaluation of the breast plan using the TLD and MOSFET for the skin dose

International Nuclear Information System (INIS)

Kim, Seon Myeong; Kim, Young Bum; Bak, Sang Yun; Lee, Sang Rok; Jeong, Se Young

2015-01-01

The measurement of skin dose is very important that treatment of breast cancer. On account of the cold or hot dose as compared with prescription dose, it is necessary to analyse the skin dose occurring during the various plan of the breast cancer treatment. At our hospital, we want to apply various analyses using a diversity of dosimeters to the breast cancer treatment. In the study, the anthropomorphic phantom is used to find out the dose difference of the skin(draining site), scar and others occurring from the tangential treatment plan of breast cancer. We took computed tomography scan of the anthropomorphic phantom and made plans for the treatment planing using open and wedge, Field-in-Field, Dose fluence. Using these, we made a comparative analysis of the dose date points by using the Eclipse. For the dose comparison, we place the anthropomorphic phantom in the treatment room and compared the measurement results by using the TLD and MOSFET on the dose data points. On the central point of treatment planing basis, the upward and downward skin dose measured by the MOSFET was the highest when the fluence was used. The skin dose of inner and outer was distinguished from the figure(5.7% - 10.3%) when the measurements were fulfilled by using TLD and MOSFET. The other side of breast dose was the lowest in the open beam, on the other hand, is highest in the Dose fluence plan. In the different kinds of treatment, the dose deviation of inner and outer was the highest, and so this was the same with the TLD and MOSFET measurement case. The outer deviation was highest in the TLD, and the Inner' was highest in the MOSFET. Skin dose in relation to the treatment plan was the highest in the planing using the fluence technique in general and it was supposed that the high dose had been caused by the movement of the MLC. There's some differences among the all the treatment planning, but the sites such as IM node occurring the lack of dose, scar, drain site are needed pay

Skin dose from radiotherapy X-ray beams: the influence of energy

International Nuclear Information System (INIS)

Butson, M.J.; Metcalfe, P.E.; University of Wollongong, Wollongong, NSW; Mathur, J.N.

1997-01-01

Skin-sparing properties of megavoltage photon beams are compromised by electron contamination. Higher energy beams do not necessarily produce lower surface and basal cell layer doses due to this electron contamination. For a 5x5 cm field size the surface doses for 6 MVp and 18 M)p X-ray beams are 10% and 7% of their respective maxima. However, at a field size of 40 x 40cm the percentage surface dose is 42% for both 6 MVp and 18 MVp beams. The introduction of beam modifying devices such as block trays can further reduce the skin-sparing advantages of high energy photon beams. Using a 10 mm perspex block tray, the surface doses for 6 MVp and 18 MVp beams with a 5 x 5 cm field size are 10% and 8%, respectively. At 40 x 40cm, surface doses are 61% and 63% for 6 MVp and 18 MVp beams, respectively. This trend is followed at the basal cell layer depth. At a depth of 1 mm, 18 MVp beam doses are always at least 5% smaller than 6 MVp doses for the same depth at all field sizes when normalized to their respective Dmax values. Results have shown that higher energy photon beams produce a negligible reduction of the delivered dose to the basal cell layer (0.1 mm). Only a small increase in skin sparing is seen at the dermal layer (1 mm), which can be negated by the increased exit dose from an opposing field. (authors)

Evaluation of entrance surface air kerma in pediatric chest radiography

Science.gov (United States)

Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J. L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

2014-11-01

The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior-posterior (AP) and posterior-anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0-1 y, 1-5 y, 5-10 y, and 10-15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels.

VARSKIN MOD 2 and SADDE MOD2: Computer codes for assessing skin dose from skin contamination

International Nuclear Information System (INIS)

Durham, J.S.

1992-12-01

The computer code VARSKIN has been modified to calculate dose to skin from three-dimensional sources, sources separated from the skin by layers of protective clothing, and gamma dose from certain radionuclides correction for backscatter has also been incorporated for certain geometries. This document describes the new code, VARSKIN Mod 2, including installation and operation instructions, provides detailed descriptions of the models used, and suggests methods for avoiding misuse of the code. The input data file for VARSKIN Mod 2 has been modified to reflect current physical data, to include the contribution to dose from internal conversion and Auger electrons, and to reflect a correction for low-energy electrons. In addition, the computer code SADDE: Scaled Absorbed Dose Distribution Evaluator has been modified to allow the generation of scaled absorbed dose distributions for mixtures of radionuclides and intereat conversion and Auger electrons. This new code, SADDE Mod 2, is also described in this document. Instructions for installation and operation of the code and detailed descriptions of the models used in the code are provided

SU-D-204-06: Dose and Image Quality Evaluation of a Low-Dose Slot-Scanning X-Ray System for Pediatric Orthopedic Studies

Energy Technology Data Exchange (ETDEWEB)

Liu, Z; Hoerner, M; Lamoureux, R; Rill, L; Arreola, M [Univ Florida, Jacksonville Beach, FL (United States)

2015-06-15

Purpose: Children in early teens with scoliosis require repeated radiographic exams over a number of years. The EOS (EOS imaging S.A., Paris, France) is a novel low-dose slot-scanning digital radiographic system designed to produce full-spine images of a free-standing patient. The radiation dose and image quality characteristics of the EOS were evaluated relative to those of a Computed Radiography (CR) system for scoliosis imaging. Methods: For dose evaluation, a full-torso anthropomorphic phantom was scanned five times using the default standard clinical protocols for both the EOS and a CR system, which include both posteroanterior and lateral full-spine views. Optically stimulated luminescent dosimeters (OSLDs), also known as nanoDots™ (Landauer, Inc., Glenwood, IL), were placed on the phantom’s surface to measure entrance skin dose. To assess image quality, MTF curves were generated from sampling the noise levels within the high-contrast regions of a line-pair phantom. Vertical and horizontal distortions were measured for the square line-pair phantom with the EOS system to evaluate the effects of geometric magnification and misalignment with the indicated imaging plane. Results: The entrance skin dose was measured to be 0.4 to 1.1 mGy for the EOS, and 0.7 to 3.6 mGy for the CR study. MTF comparison shows that CR greatly outperforms the EOS, despite both systems having a limiting resolution at 1.8 line-pairs per mm. Vertical distortion was unaffected by phantom positioning, because of the EOS slot-scanning geometry. Horizontal distortion increased linearly with miscentering distance. Conclusion: The EOS system resulted in approximately 70% lower radiation dose than CR for full-spine images. Image quality was found to be inferior to CR. Further investigation is required to see if EOS system is an acceptable modality for performing clinically diagnostic scoliosis examinations.

SU-D-204-06: Dose and Image Quality Evaluation of a Low-Dose Slot-Scanning X-Ray System for Pediatric Orthopedic Studies

International Nuclear Information System (INIS)

Liu, Z; Hoerner, M; Lamoureux, R; Rill, L; Arreola, M

2015-01-01

Purpose: Children in early teens with scoliosis require repeated radiographic exams over a number of years. The EOS (EOS imaging S.A., Paris, France) is a novel low-dose slot-scanning digital radiographic system designed to produce full-spine images of a free-standing patient. The radiation dose and image quality characteristics of the EOS were evaluated relative to those of a Computed Radiography (CR) system for scoliosis imaging. Methods: For dose evaluation, a full-torso anthropomorphic phantom was scanned five times using the default standard clinical protocols for both the EOS and a CR system, which include both posteroanterior and lateral full-spine views. Optically stimulated luminescent dosimeters (OSLDs), also known as nanoDots™ (Landauer, Inc., Glenwood, IL), were placed on the phantom’s surface to measure entrance skin dose. To assess image quality, MTF curves were generated from sampling the noise levels within the high-contrast regions of a line-pair phantom. Vertical and horizontal distortions were measured for the square line-pair phantom with the EOS system to evaluate the effects of geometric magnification and misalignment with the indicated imaging plane. Results: The entrance skin dose was measured to be 0.4 to 1.1 mGy for the EOS, and 0.7 to 3.6 mGy for the CR study. MTF comparison shows that CR greatly outperforms the EOS, despite both systems having a limiting resolution at 1.8 line-pairs per mm. Vertical distortion was unaffected by phantom positioning, because of the EOS slot-scanning geometry. Horizontal distortion increased linearly with miscentering distance. Conclusion: The EOS system resulted in approximately 70% lower radiation dose than CR for full-spine images. Image quality was found to be inferior to CR. Further investigation is required to see if EOS system is an acceptable modality for performing clinically diagnostic scoliosis examinations

SU-E-I-15: Comparison of Radiation Dose for Radiography and EOS in Adolescent Scoliosis Patients

Energy Technology Data Exchange (ETDEWEB)

Schueler, B; Walz-Flannigan, A [Mayo Clinic, Rochester, MN (United States)

2014-06-01

Purpose: To estimate patient radiation dose for whole spine imaging using EOS, a new biplanar slot-scanning radiographic system and compare with standard scoliosis radiography. Methods: The EOS imaging system (EOS Imaging, Paris, France) consists of two orthogonal x-ray fan beams which simultaneously acquire frontal and lateral projection images of a standing patient. The patient entrance skin air kerma was measured for each projection image using manufacturer-recommended exposure parameters for spine imaging. Organ and effective doses were estimated using a commercially-available Monte Carlo simulation program (PCXMC, STUK, Radiation and Nuclear Safety Authority, Helsinki, Finland) for a 15 year old mathematical phantom model. These results were compared to organ and effective dose estimated for scoliosis radiography using computed radiography (CR) with standard exposure parameters obtained from a survey of pediatric radiographic projections. Results: The entrance skin air kerma for EOS was found to be 0.18 mGy and 0.33 mGy for posterior-anterior (PA) and lateral projections, respectively. This compares to 0.76 mGy and 1.4 mGy for CR, PA and lateral projections. Effective dose for EOS (PA and lateral projections combined) is 0.19 mSv compared to 0.51 mSv for CR. Conclusion: The EOS slot-scanning radiographic system allows for reduced patient radiation dose in scoliosis patients as compared to standard CR radiography.

Estimation of entrance dose during selected fluoroscopic examinations in some hospitals in Khartoum state

International Nuclear Information System (INIS)

Mohammed, Heba Abdalkareem Osman

2016-01-01

A diagnostic fluoroscopy is a modality that involves visualizing the anatomy using radiation in real time. Therefore, patients doses have a potential for being great, increasing the chance of the radiation induced carcinogenesis. The objective of this study was to determine the mean entrance surface dose (ESD) from selected fluoroscopic examinations namely, hysterosalpingography (HSG) and ascendingurethogram (ASU) in three hospitals in Khartoum State. A total of 87 and 110 patents for HSG and ASU respectively were examined. The data were collected over four months. The mean ESD for patients who underwent HSG were 16.2 mGy, 20.6 mGy and 25.9 mGY respectively, while the ESD for patient who underwent ascendingurethrogram for AP view were 3.5mGy, 2.9mGy and 11.9mGy and for OB view 15.9 mGy, 18.3 mGy and 25.4 mGy. Patient doses were calculated using mathematical equation and the results were compared with the ESDs calculated using mathematical equation and the results were found to be comparable with the ESDs reported in previous studies and within the guidance level established by the ICRP. Fluoroscopy time, operator skills, x-ray machine type and clinical complexity of the procedures were shown to be major contributors to the variations reported in the measured ESDs. The study demonstrated the need for standardization of techniques throughout the hospitals and suggested that there ia a need to optimize the procedures.(Author)

Skin dose estimation for various beam modifiers and source-to-surface distances for 6MV photons

Directory of Open Access Journals (Sweden)

Yadav Girigesh

2009-01-01

Full Text Available The purpose of this study was to learn the skin dose estimation for various beam modifiers at various source-to-surface distances (SSDs for a 6 MV photon. Surface and buildup region doses were measured with an acrylic slab phantom and Markus 0.055 cc parallel plate (PP ionization chamber. Measurements were carried out for open fields, motorized wedge fields, acrylic block tray fields ranging from 3 x 3 cm 2 to 30 x 30 cm 2 . Twenty-five percent of the field was blocked with a cerrobend block and a Multileaf collimator (MLC. The effect of the blocks on the skin dose was measured for a 20 x 20 cm 2 field size, at 80 cm, 100 cm and 120 cm SSD. During the use of isocentric treatments, whereby the tumor is positioned at 100 cm from the source, depending on the depth of the tumor and size of the patient, the SSD can vary from 80 cm to 100 cm. To achieve a larger field size, the SSD can also be extended up to 120 cm at times. The skin dose increased as field size increased. The skin dose for the open 10 x10 cm 2 field was 15.5%, 14.8% and 15.5% at 80 cm, 100 cm and 120 cm SSDs, respectively. The skin dose due to a motorized 60 0 wedge for the 10 x 10 cm 2 field was 9.9%, 9.5%, and 9.5% at 80 cm, 100 cm and 120 cm SSDs. The skin dose due to acrylic block tray, of thickness 1.0 cm for a 10 x 10 cm 2 field was 27.0%, 17.2% and 16.1% at 80, 100 and 120 cm SSD respectively. Due to the use of an acrylic block tray, the surface dose was increased for all field sizes at the above three SSDs and the percentage skin dose was more dominant at the lower SSD and larger field size. The skin dose for a 30 x 30 cm 2 field size at 80 cm SSD was 38.3% and it was 70.4% for the open and acrylic block tray fields, respectively. The skin doses for motorized wedge fields were lower than for open fields. The effect of SSDs on the surface dose for motorized 60° wedge fields was not significant for a small field size (difference was less than 1% up to a 15 x 15 cm 2 field size

Patient absorbed radiation doses estimation related to irradiation anatomy; Estimativa de dose absorvida pelo paciente relacionada a anatomia irradiada

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Soares, Flavio Augusto Penna; Soares, Amanda Anastacio; Kahl, Gabrielly Gomes, E-mail: prof.flavio@gmail.com, E-mail: amanda-a-soares@hotmail.com, E-mail: gabriellygkahl@gmail.com [Instituto Federal de Eduacao, Ciencia e Tecnologia de Santa Catarina (IFSC), Florianopolis, SC (Brazil)

2014-07-01

Developed a direct equation to estimate the absorbed dose to the patient in x-ray examinations, using electric, geometric parameters and filtering combined with data from irradiated anatomy. To determine the absorbed dose for each examination, the entrance skin dose (ESD) is adjusted to the thickness of the patient's specific anatomy. ESD is calculated from the estimated KERMA greatness in the air. Beer-Lambert equations derived from power data mass absorption coefficients obtained from the NIST / USA, were developed for each tissue: bone, muscle, fat and skin. Skin thickness was set at 2 mm and the bone was estimated in the central ray of the site, in the anteroposterior view. Because they are similar in density and attenuation coefficients, muscle and fat are treated as a single tissue. For evaluation of the full equations, we chose three different anatomies: chest, hand and thigh. Although complex in its shape, the equations simplify direct determination of absorbed dose from the characteristics of the equipment and patient. The input data is inserted at a single time and total absorbed dose (mGy) is calculated instantly. The average error, when compared with available data, is less than 5% in any combination of device data and exams. In calculating the dose for an exam and patient, the operator can choose the variables that will deposit less radiation to the patient through the prior analysis of each combination of variables, using the ALARA principle in routine diagnostic radiology sector.

How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

International Nuclear Information System (INIS)

Jones, A. Kyle; Ensor, Joe E.; Pasciak, Alexander S.

2014-01-01

Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ±50% using indirect dose metrics for embolization procedures. Methods: PSD were measured directly using radiochromic film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined. Results: When using the standard calculation method, calculated PSD were within ±35% for all 41 procedures studied. Calculated PSD were within ±50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ±50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (±35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from cone

Direct dose measurement on patient during percutaneous coronary intervention procedures using radiophotoluminescence glass dosimeters

International Nuclear Information System (INIS)

Kato, Mamoru; Chida, Koichi; Moritake, Takashi; Sato, Tadaya; Oosaka, Hajime; Toyoshima, Hideto; Zuguchi, Masayuki; Abe, Yoshihisa

2017-01-01

The purpose of this research was to measure accurate patient entrance skin dose and maximum skin absorbed dose (MSD) to prevent radiation skin injuries in percutaneous coronary interventions (PCIs). We directly measured the MSD on 50 PCIs by using multiple radiophotoluminescence glass dosimeters and a modified dosimetry gown. Also, we analysed the correlation between the MSD and indirect measurement parameters, such as fluoroscopic time (FT), dose-area product (DAP) and cumulative air kerma (C-AK). There were very strong correlations between MSD and FT, DAP and C-AK, with the correlation between MSD and C-AK being the strongest (r = 0.938). In conclusion, the regression lines using MSD as an outcome value (y) and C-AK as predictor variables (x) were y = 1.12x (R"2 = 0.880). From the linear regression equation, MSD is estimated to be ∼1.12 times that of C-AK in real time. (authors)

Proposal of a dosemeter for skin beta radiation dose assessment

International Nuclear Information System (INIS)

Rosa, L.A.R. da; Caldas, L.V.E.

1987-08-01

Beta radiation is, undoubtedly, less penetrating than X or gamma radiation. Thus, beta radiation sources external to the human body do not cause a significant irradiation of its deeper tissues. However, in some cases, they may contribute in a very important way to the irradiation of the lens of the eyes and, mainly, of the skin. Specially, the hands and finger tips may receive a high dose. In this work some relevant aspects of the individual monitoring in beta radiation fields are discussed and the importance of monitoring this kind of radiation in some activities where the skin absorbed dose may be a limiting factor is evidenced. The main characteristics of the thermoluminescent (TL) response of ultra-thin CaSO 4 : Dy detectors (UT-CaSO 4 : Dy) in the detection of this kind of radiation are also studied. The irradiation are performed with 90 Sr 90 Y, 204 TI and 147 Pm sources. The reproducibility, linearity, dependence on the absorbed dose rate, optical fading, energy and angular dependences of the detector TL responce are investigated. Transmission factors for different thicknesses of tissue equivalent material are obtained for the TL detectors using the three available beta sources. Based on the results obtained, a dosemeter for skin beta radiation absorbed dose assessment with an energy dependence better than 12% is proposed. (Author) [pt

Time and dose-related changes in the thickness of pig skin after irradiation with single doses of 90Sr/90Y β-rays

International Nuclear Information System (INIS)

Rezvani, M.; Hamlet, R.; Hopewell, J.W.; Sieber, V.K.

1994-01-01

Time-related changes in pig skin thickness have been evaluated using a non-invasive ultrasound technique after exposure to a range of single doses of 90 Sr/ 90 Yr β-rays. The reduction in relative skin thickness developed in two distinct phases: the first was between 12 and 20 weeks postirradiation. No further changes were then seen until 52 weeks postirradiation when a second phase of skin thinning was observed. This was complete after 76 weeks and no further changes in relative skin thickness were seen in the maximum follow up period of 129 weeks. The timings of these phases of damage were independent of the radiation dose, however, the severity of both phases of radiation-induced skin thinning were dose related. (Author)

Skin dose for head and neck cancer patients treated with intensity-modulated radiation therapy(IMRT)

Science.gov (United States)

Fu, Hsiao-Ju; Li, Chi-Wei; Tsai, Wei-Ta; Chang, Chih-Chia; Tsang, Yuk-Wah

2017-11-01

The reliability of thermoluminescent dosimeters (ultrathin TLD) and ISP Gafchromic EBT2 film to measure the surface dose in phantom and the skin dose in head-and-neck patients treated with intensity-modulated radiation therapy technique(IMRT) is the research focus. Seven-field treatment plans with prescribed dose of 180 cGy were performed on Eclipse treatment planning system which utilized pencil beam calculation algorithm(PBC). In calibration tests, the variance coefficient of the ultrathin TLDs were within 3%. The points on the calibration curve of the Gafchromic film was within 1% variation. Five measurements were taken on phantom using ultrathin TLD and EBT2 film respectively. The measured mean surface doses between ultrathin TLD or EBT2 film were within 5% deviation. Skin doses of 6 patients were measured for initial 5 fractions and the mean dose per-fraction was calculated. If the extrapolated doses for 30 fractions were below 4000 cGy, the skin reaction grading observed according to Radiation Therapy Oncology Group (RTOG) was either grade 1 or grade 2. If surface dose exceeded 5000 cGy in 32 fractions, then grade 3 skin reactions were observed.

A computer-assisted procedure for estimating patient exposure and fetal dose in radiographic examinations

International Nuclear Information System (INIS)

Glaze, S.; Schneiders, N.; Bushong, S.C.

1982-01-01

A computer program for calculating patient entrance exposure and fetal dose for 11 common radiographic examinations was developed. The output intensity measured at 70 kVp and a 30-inch (76-cm) source-to-skin distance was entered into the program. The change in output intensity with changing kVp was examined for 17 single-phase and 12 three-phase x-ray units. The relationships obtained from a least squares regression analysis of the data, along with the technique factors for each examination, were used to calculate patient exposure. Fetal dose was estimated using published fetal dose in mrad (10 -5 Gy) per 1,000 mR (258 μC/kg) entrance exposure values. The computations are fully automated and individualized to each radiographic unit. The information provides a ready reference in large institutions and is particularly useful at smaller facilities that do not have available physicists who can make the calculations immediately

A computer-assisted procedure for estimating patient exposure and fetal dose in radiographic examinations

International Nuclear Information System (INIS)

Glaze, S.; Schneiders, N.; Bushong, S.C.

1982-01-01

A computer program for calculating patient entrance exposure and fetal dose for 11 common radiographic examinations was developed. The output intensity measured at 70 kVp and a 30-inch (76-cm) source-to-skin distance was entered into the program. The change in output intensity with changing kVp was examined for 17 single-phase and 12 three-phase x-ray units. The relationships obtained from a least squares regression analysis of the data, along with the technique factors for each examination, were used to calculate patient exposure. Fetal dose was estimated using published fetal dose in mrad (10(-5) Gy) per 1,000 mR (258 microC/kg) entrance exposure values. The computations are fully automated and individualized to each radiographic unit. The information provides a ready reference in large institutions and is particularly useful at smaller facilities that do not have available physicians who can make the calculations immediately

Measurement of Skin Dose from Using the Treatment Immobilization Devices

International Nuclear Information System (INIS)

Je, Jae Yong; Park, Chul Woo; Noh, Kyung Suk

2009-01-01

The research was about the relation between the dorsal side dose measured by using the phantom body (Alderson Rando Phantom) and factors like contacted material of the patients, the size of the field, angle of incidence. Compared with mylar (tennis racket), the dose on 10 x 10 cm 2 field size of cotton was increased by 2% and by 8% in the case of breast board. In the case of 15 x 15 cm 2 field size, the dose was increased by 6% compared with 10 x 10 cm 2 size. The field size of 20 x 20 cm 2 resulted in 10% increase of dose, while 5 x 5 cm 2 produced 13% decrease. Compared with incident angle 0 degree, the cases for the incident angle 5 degrees had 0.4% less dose for breast board, 0.5% for tennis racket, 1.1% for cotton. The cases for the incident angle 10 degrees had 1.5% less dose for breast board, 1.9% for tennis racket, 2.6% for cotton. For the incident angle 15 degrees, breast board, tennis racket, cotton caused decrease of dose by 3.9%, 2.6%, 3.86% respectively. Resultantly carbon material can cause more skin dose in treatment field. By the results of this study, we recommend that one should avoid the contact between the carbon material and skin.

Characterization of a team intraoperative Radiation therapy and measurement of dose in skin with film radiochromic

International Nuclear Information System (INIS)

Onses Segarra, A.; Sancho Kolster, I.; Eraso Urien, A.; Pla Farnos, M. J.; Picon Olmos, C.

2015-01-01

This paper presents the results of the initial reference state of intraoperative radiotherapy equipment lntraBeam, for performing breast treatments are analyzed. To the initial reference team was established for the following dosimetric and geometric beam parameters: percentage depth dose, beam quality, isotropy, linearity and mechanical and geometric integrity for both the source RX as for different spherical applicators of the team. Based on these checks, a program of periodic quality control was established. One of the exclusion criteria for this treatment is that the tumor is less than l cm of the skin, yaque give doses received in this organ can be high. For this reason it is important to know exactly the absorbed dose in skin during these treatments. In this regard we have implemented a system for measuring the skin dose during treatment with Radiochromic film, placing 4 film segments in fixed positions of the skin around the surgical incision. It .ha obtained calibration curve of sterilized films and compared the results with a calibration beam megavoltage. The results of the skin dose measurements are compared with theoretical estimates given by the planning system equipment. The results indicate the need to measure individually the skin dose for these treatments. (Author)

Evaluation of patients skin dose undergoing interventional cardiology procedure using radiochromic films

International Nuclear Information System (INIS)

Silva, Mauro W. Oliveira da; Canevaro, Lucia V.; Rodrigues, Barbara B. Dias

2011-01-01

In interventional cardiology (IC), coronary angiography (CA) and percutaneous transluminal coronary angioplasty (PTCA) procedures are the most frequent ones. Since the 1990s, the number of IC procedures has increased rapidly. It is also known that these procedures are associated with high radiation doses due to long fluoroscopy time (FT) and large number of cine-frames (CF) acquired to document the procedure. Mapping skin doses in IC is useful to find the probability of skin injuries, to detect areas of overlapping field, and to get a permanent record of the most exposed areas of skin. The purpose of this study was to estimate the maximum skin dose (MSD) in patients undergoing CA and PTCA, and to compare these values with the reference levels proposed in the literature. Patients' dose measurements were carried out on a sample of 38 patients at the hemodynamic department, in four local hospitals in Rio de Janeiro, Brazil, using Gafchromic XR-RV2 films. In PTCA procedures, the median and third quartile values of MSD were estimated at 2.5 and 5.3 Gy, respectively. For the CA procedures, the median and third quartile values of MSD were estimated at 0.5 and 0.7 Gy, respectively. In this paper, we used the Pearson's correlation coefficient (r), and we found a fairly strong correlation between FT and MSD (r=0.8334, p<0.0001), for CA procedures. The 1 Gy threshold for deterministic effects was exceeded in nine patients. The use of Gafchromic XR-RV2 films was shown to be an effective method to measure MSD and the dose distribution map. The method is effective to identify the distribution of radiation fields, thus allowing the follow-up of the patient to investigate the appearance of skin injuries. (author)

The study of mean glandular dose in mammography in Yazd and the factors affecting it

International Nuclear Information System (INIS)

Bouzarjomehri, F.; Mostaar, A.; Ghasemi, A.; Ehramposh, M. H.; Khosravi, H.

2006-01-01

The objective of this study was to determine the mean glandular dose resulting from mammography examinations in Yazd, southeastern Iran and to identify the factors affecting it. Patients and Methods: This survey was conducted during May to December 2005 to estimate the mean glandular dose for women undergoing mammography and to report the distribution of dose. compressed breast thickness, glandular tissue content, and mammography technique used. The clinical data were collected from 946 mammograms taken from 246 women who were referred to four mammography centers. The mammography instruments in these centers were four modern units with a molybdenum anode and either molybdenum or rhodium filter. The exposure conditions of each mammogram were recorded. The breast glandular content of each mammogram was estimated by a radiologist. The mean glandular dose was calculated based on measuring the normalized entrance skin dose in air. half value layer, kVp, mAs, breast thickness and glandular content. Half value layer, kVp and entrance skin dose were measured by a solid-state detector. The analytical method of Sobol et al. was used for calculation of mean glandular dose . Results: The mean±SD mean glandular dose per film was.2±0.6 mGy for cranio caudal and 1.63±O.9 mGy for mediolateral oblique views. The mean±SD mean glandular dose per woman was 5.5 3.1.mGy. A positive correlation was found between the beam Half value layer with mean glandular dose (r=O.38) and the breast thickness with mean glandular dose (r=O.5). Conclusion: The mean±SD mean glandular dose per film of 1.42±0.8 mGy in present study was lower than most of similar reports. However, the mean mean glandular dose per woman was higher than that in other studies

Skin dose reduction by a clinically viable magnetic deflector

International Nuclear Information System (INIS)

Butson, M.J.; Carolan, M.; Metcalfe, J.N.; University of Wollongong, NSW; Mathur, J.N.; Yu, P.; Young, E.; Kan, M.; City University of Hong Kong, Kowloon

1997-01-01

A variable magnetic deflector which attaches onto the treatment head of a linear accelerator has reduced skin dose by as much as 65% for 6MV x-rays. The magnetic deflector is constructed from Neodymium Iron Boron (NdFeB) rare earth magnets. It weighs approximately 15 kg and is designed to easily fit onto the accessory mount of a clinical linear accelerator. All field sizes are attainable up to 35 cm x 35 cm at 100 cm SSD. The gap between the magnetic poles can be adjusted, providing the highest field strength for each field size. Magnetic field strengths up to 0.55 Tesla are attainable. For a 6MV x-ray beam with a 10 mm perspex block tray, surface dose is reduced from 29% to 14% and from 59% to 37% for a 20 cm x 20 cm and 35 cm x 35 cm field size, respectively. Results at varying SSD's have shown at least 10 cm of space must be allowed between the magnets and patient for adequate reduction of skin dose through removal of electron contaminants. (authors)

Entrances and entrance halls of residential buildings in Belgrade: 1918-1941

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Putnik Vladana

2015-01-01

Full Text Available Between the two world wars Belgrade saw a surge in housing construction, including many rental apartment buildings, so-called 'luxury city palaces'. In addition to richly decorated street façades in the style of academism, eclecticism and Art Deco, architects paid much attention to the design of entrances and entrance halls. The entrance frequently was the main element of the façade even in buildings in a moderate modernist style. Since this aspect of architectural design is scantily documented, this paper seeks to identify its main trends in the 1920s and 1930s and to establish a typology of entrances and entrance halls of residential buildings. It also outlines the parameters and social circumstances that played a role in giving special attention to this element of residential buildings, and examines whether Belgrade architects pursued a sort of total design inspired by European models.

Evaluation of Patient Radiation Dose during Orthopedic Surgery

International Nuclear Information System (INIS)

Osman, H; Elzaki, A.; Sam, A.K.; Sulieman, A.

2013-01-01

The number of orthopedic procedures requiring the use of the fluoroscopic guidance has increased over the recent years. Consequently the patient exposed to un avoidable radiation doses. The aim of the current study was to evaluate patient radiation dose during these procedures.37 patients under went dynamic hip screw (DHS) and dynamic cannulated screw (DCS) were evaluated using calibrated Thermolumincent Dosimeters (TLDs), under carm fluoroscopic machines ,in three centers in Khartoum-Sudan. The mean Entrance Skin Dose (ESD) was 7.9 m Gy per procedure. The bone marrow and gonad organ exposed to significant doses. No correlation was found between ESD and Body Mass Index (BMI), or patient weight. Well correlation was found between kilo voltage applied and ESD. Orthopedic surgeries delivered lower radiation dose to patients than cardiac catheterization or hysterosalpingraphy (HSG) procedures. More study should be implemented to follow radiation dose before surgery and after surgery

Dose-image quality study in digital chest radiography using Monte Carlo simulation

International Nuclear Information System (INIS)

Correa, S.C.A.; Souza, E.M.; Silva, A.X.; Lopes, R.T.; Yoriyaz, H.

2008-01-01

One of the main preoccupations of diagnostic radiology is to guarantee a good image-sparing dose to the patient. In the present study, Monte Carlo simulations, with MCNPX code, coupled with an adult voxel female model (FAX) were performed to investigate how image quality and dose in digital chest radiography vary with tube voltage (80-150 kV) using air-gap technique and a computed radiography system. Calculated quantities were normalized to a fixed value of entrance skin exposure (ESE) of 0.0136 R. The results of the present analysis show that the image quality for chest radiography with imaging plate is improved and the dose reduced at lower tube voltage

Patient doses due to a diagnostic X-ray picture

International Nuclear Information System (INIS)

Riet, A. van 't.

1977-09-01

The influence of technical parameters on patient doses in X-ray diagnostics has been investigated. During an X-ray picture (30 x 40 or 35 x 43 cm 2 ) for general survey in intraveneous pyelography (IVP), skin exposure measurements in the centre of the radiation beam were carried out at 650 adult female patients in 46 Dutch hospitals. In addition, the first half-value layer of the radiation was measured. In 15 of these hospitals, similar measurements were also carried out at a Rando phantom. Small LiF thermoluminescent dosemeters were used for all measurements. The results show a remarkable variation in the mean entrance- and exit-exposure per hospital. The variation in the mean entrance-exposure per hospital (factor 8) is mainly caused by differences in radiation quality. In some hospitals, no added filtration is used while others use a relatively heavy filtration. The variation in the mean exit-exposure per hospital could not be explained uniquely from technical parameters like grid, screen and film sensivity. From phantom measurements it was found that other parameters like adjustment of the automatic exposure timer and film density required by the radiographer are of importance. The measuring system used has shown to be an adequate and simple tool for a crude selection of those hospitals where skin exposures are relatively high. On the basis of the collected data some recommendations are given to promote dose reduction in X-ray diagnostics. The use of fast screen-film combinations is of great potential importance. However further investigation seems desirable, especially concerning patient dose during fluoroscopy 0

A comparison of skin and chest wall dose delivered with multicatheter, Contura multilumen balloon, and MammoSite breast brachytherapy.

Science.gov (United States)

Cuttino, Laurie W; Todor, Dorin; Rosu, Mihaela; Arthur, Douglas W

2011-01-01

Skin and chest wall doses have been correlated with toxicity in patients treated with breast brachytherapy . This investigation compared the ability to control skin and chest wall doses between patients treated with multicatheter (MC), Contura multilumen balloon (CMLB), and MammoSite (MS) brachytherapy. 43 patients treated with the MC technique, 45 patients treated with the CMLB, and 83 patients treated with the MS were reviewed. The maximum doses delivered to the skin and chest wall were calculated for all patients. The mean maximum skin doses for the MC, CMLB, and MS were 2.3 Gy (67% of prescription dose), 2.8 Gy (82% of prescription dose), and 3.2 Gy per fraction (94% of prescription dose), respectively. Although the skin distances were similar (p = 0.23) for the two balloon techniques, the mean skin dose with the CMLB was significantly lower than with the MS (p = 0.05). The mean maximum rib doses for the MC, CMLB, and MS were 2.3 Gy (67% of prescription dose), 2.8 Gy (82% of prescription dose), and 3.6 Gy per fraction (105% of prescription dose), respectively. Again, the mean rib dose with the CMLB was significantly lower than with the MS (p = 0.002). The MC and CMLB techniques are associated with significantly lower mean skin and rib doses than is the MS. Treatment with the MS was associated with significantly more patients receiving doses to the skin or rib in excess of 125% of the prescription. Treatment with the CMLB may prove to yield less normal tissue toxicity than treatment with the MS. Copyright © 2011 Elsevier Inc. All rights reserved.

A Comparison of Skin and Chest Wall Dose Delivered With Multicatheter, Contura Multilumen Balloon, and MammoSite Breast Brachytherapy

International Nuclear Information System (INIS)

Cuttino, Laurie W.; Todor, Dorin; Rosu, Mihaela; Arthur, Douglas W.

2011-01-01

Purpose: Skin and chest wall doses have been correlated with toxicity in patients treated with breast brachytherapy . This investigation compared the ability to control skin and chest wall doses between patients treated with multicatheter (MC), Contura multilumen balloon (CMLB), and MammoSite (MS) brachytherapy. Methods and Materials: 43 patients treated with the MC technique, 45 patients treated with the CMLB, and 83 patients treated with the MS were reviewed. The maximum doses delivered to the skin and chest wall were calculated for all patients. Results: The mean maximum skin doses for the MC, CMLB, and MS were 2.3 Gy (67% of prescription dose), 2.8 Gy (82% of prescription dose), and 3.2 Gy per fraction (94% of prescription dose), respectively. Although the skin distances were similar (p = 0.23) for the two balloon techniques, the mean skin dose with the CMLB was significantly lower than with the MS (p = 0.05). The mean maximum rib doses for the MC, CMLB, and MS were 2.3 Gy (67% of prescription dose), 2.8 Gy (82% of prescription dose), and 3.6 Gy per fraction (105% of prescription dose), respectively. Again, the mean rib dose with the CMLB was significantly lower than with the MS (p = 0.002). Conclusion: The MC and CMLB techniques are associated with significantly lower mean skin and rib doses than is the MS. Treatment with the MS was associated with significantly more patients receiving doses to the skin or rib in excess of 125% of the prescription. Treatment with the CMLB may prove to yield less normal tissue toxicity than treatment with the MS.

Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

International Nuclear Information System (INIS)

Poellaenen, R.

2002-05-01

In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has been higher

The relationship of over density to overexposure each film/screen systems in chest radiography

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung Min; Huo Joon [Korea University, Seoul (Korea, Republic of); Taro, Hayash; Yuji, Ishida; Tatsuya, Sakurai [The Chemotherapeutic Istitute Hospital, Tokyo (Japan)

1999-06-01

This study is to calculate the exposed radiation dose using Bit method, NDD calculation method and monogram method without dosimeter. In addition,we can calculate the radiation dose from x-ray film density as a film badge. The authors examined the entrance skin dose from 2 {approx} 3 intercostal chest x-ray film density. We also studied the relationship between film density and equivalent dose in the each screen film system under the different radiation quality and the poor geometry condition of grid ratio. As results, we established the deductive method to define the entrance skin dose from chest x-ray film density. The error range was found in the range -13 percent {approx} +17 percent for between deductive entrance skin dose and the 2 {approx} 3 inter coastal chest x-ray film density to actual detective radiation dose with dosimeter. (author)

Research and development of a beta skin-dose monitor using silicon detectors

International Nuclear Information System (INIS)

Chung Manho.

1991-01-01

The purpose of the research is to develop improved ways to computer and measure the beta skin dose. Beta spectra for the various sources were calculated based on the Fermi beta decay theory. The calculated average energies of the spectra agreed with the literature values within 6%. Monte Carlo electron transport codes have been developed for use on microcomputers. The one-dimensional code ZEBRA has been converted to a microcomputer version called Eltran2 which runs on the Macintosh or any IBM compatible microcomputers. Eltran2 has then been modified into a two-dimensional program called Eltran3. Using Eltran2 and Eltran3, different source distributions and the hot particle dose have been studied. It has been found that the VARSKIN code overestimates the skin dose from hot particles by about 10 to 40% in comparison with Eltran3 calculations, because the VARSKIN code is based on the data tables for an unbounded medium. An ion-implanted silicon detector was selected because of its small size, high sensitivity, and low leakage current. To cover a wide range of dose rate, both the pulse and current mode operations of the silicon detector were used, with an overlap of one order of magnitude in the measurable dose rate ranges. By using a gradient shield of about 7 mg/cm 2 on the detector, dose gradient measurements have been performed. Five 60 Co hot particles received from GPU Nuclear Corporation have been measured by the silicon detector and the measurements agreed well with Eltran3 calculations. In the pulse mode, variation of the depletion depth of the silicon detector due to the changes of bias voltage was confirmed. Based on this research, a prototype beta skin dose monitor has been constructed. The device includes an 8-bit analogue-to-digital converter and a Z-80 microprocessor with a machine-coded program, to calculate the skin dose

Radiation Dose from Voiding Cystourethrography (VCUG) Examination in Children

International Nuclear Information System (INIS)

Siriwiladluk, T.; Krisanachinda, A.

2012-01-01

Introduction: The purpose of this study is to determine entrance skin dose (ESD) from fluoroscopy and radiography procedures in voiding cystourethrography (VCUG) studies of pediatric patients by dose-area product (DAP) recording. Methods: Radiation doses received by 70 patients underwent VCUG procedures were determined by the DAP Meter, Wellh?fer Dosimetrie GmbH, Germany) directly coupled to the x-ray tube window (Philips Omni Diagnost Eleva) and an electrometer connected to a computer for data collection. The study revealed the radiation dose for VCUG and the baseline data on the entrance skin dose, ESD, dose area-product (DAP) and the effective dose, E, to establish local reference dose levels for VCUG in pediatric patients. Results: The mean(minimum-maximum) ESD, DAP and the effective dose of pediatric patients in 4 age ranges were 3.41(1-9) mGy, 46.58 (21.90-158.90) cGycm 2 and 0.10(0.05-0.33) mSv for 0- 1 years, 6.80(2-16) mGy, 115.55 (20.70-258.70)cGycm 2 and 0.24(0.04-0.54) mSv for >1-5 years, 11.76 (3-23) mGy, 292.28 (88.90-593.50)cGycm 2 and 0.61(0.19-1.25) mSv for >5-10 years, and 20.50(10-42) mGy, 575.98(255.60-1247.80) cGycm 2 and 1.12(0.54-2.62) mSv for >10-15 years respectively. Discussion: The dose levels for VCUG as recommended by the national reference doses (NRDs) of UK are classified at patient age of 0-1 years, 90 cGy.cm 2 , >1-5 years, 110 cGy.cm 2 , >5-10 years, 210 cGy.cm 2 and >10-15 years, 470 cGy.cm 2 respectively. Conclusions: The mean DAP of pediatric patients were higher than the dose level as recommended by NRD at the age range >1-5, >5-10 and >10-15 years. The limitation in this study was the non uniform in the number of patients at the higher age. Attempts could be made to lower the radiation dose to avoid the higher risk of developing radiation-induced cancer in children. (author)

Clinical application of a OneDose MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast.

Science.gov (United States)

Kinhikar, Rajesh A; Sharma, Pramod K; Tambe, Chandrashekhar M; Mahantshetty, Umesh M; Sarin, Rajiv; Deshpande, Deepak D; Shrivastava, Shyam K

2006-07-21

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs.

Survey on patient doses in cardiology in Latin America. Criteria for high skin doses follow up

International Nuclear Information System (INIS)

Duran, Ariel; Duro, Ivanna; Lopez, Leonardo; Ramirez, Alfredo; Herrera, Carlos; Navarro, Joaquin; Rivarola, Carlos; Lopez, Jose A.

2008-01-01

Full text: As part of the International Action Plan for Protection of Patients and supporting by the IAEA, a survey on patient doses in fluoroscopy guided procedures in cardiology in Latin America has been conducted since 2006. One of the objectives of the survey was to set criteria for the identification and evaluation of high skin doses in a certain number of patients to recommend a clinical follow up for potential radiation injuries (more than 3 Gy at the skin). The used methodology for the survey was initiated with two dedicated workshops held in Santiago de Chile (2005) and San Jose de Costa Rica (2007) involving relevant cardiologists from 15 different Latin American Countries. Some sessions were also attended by experts from the Regulatory and Health Authorities. Standardized forms to collect demographic and patient dosimetric data were agreed. Considering that most of the involved centres had still not dosimeters installed in the cardiology x-ray systems, it was agreed to collect data on fluoroscopy time and total number of cine frames per procedure. Relevant factors influencing radio sensitivity of the skin were also collected. Data from 10 countries representing a sample of 709 patients were received during the first year. Procedures included were diagnostic (DG) (coronary angiography and electrophysiology studies), therapeutic (TH) (percutaneous transluminal coronary angioplasties, cardiac ablations and valvuloplasties) or including both DG and TH. A total of 26 patients (3.7%) were selected for potential high skin doses. Initial considered criteria for selection were more than 30 minutes of fluoroscopy, more than 3,000 cine frames per procedure or patients with more than 100 kg of weight. Maximum reported values were 72 minutes and 8,100 frames. In addition, 5 of these patients were diabetic, 6 have previous fluoroscopy procedures and 5 were over 95 kg. The percentage of selected cases for clinical follow up derived from potential skin injuries seem

Patient absorbed radiation doses estimation related to irradiation anatomy

International Nuclear Information System (INIS)

Soares, Flavio Augusto Penna; Soares, Amanda Anastacio; Kahl, Gabrielly Gomes

2014-01-01

Developed a direct equation to estimate the absorbed dose to the patient in x-ray examinations, using electric, geometric parameters and filtering combined with data from irradiated anatomy. To determine the absorbed dose for each examination, the entrance skin dose (ESD) is adjusted to the thickness of the patient's specific anatomy. ESD is calculated from the estimated KERMA greatness in the air. Beer-Lambert equations derived from power data mass absorption coefficients obtained from the NIST / USA, were developed for each tissue: bone, muscle, fat and skin. Skin thickness was set at 2 mm and the bone was estimated in the central ray of the site, in the anteroposterior view. Because they are similar in density and attenuation coefficients, muscle and fat are treated as a single tissue. For evaluation of the full equations, we chose three different anatomies: chest, hand and thigh. Although complex in its shape, the equations simplify direct determination of absorbed dose from the characteristics of the equipment and patient. The input data is inserted at a single time and total absorbed dose (mGy) is calculated instantly. The average error, when compared with available data, is less than 5% in any combination of device data and exams. In calculating the dose for an exam and patient, the operator can choose the variables that will deposit less radiation to the patient through the prior analysis of each combination of variables, using the ALARA principle in routine diagnostic radiology sector

A prospective, open-label study of low-dose total skin electron beam therapy in mycosis fungoides

DEFF Research Database (Denmark)

Kamstrup, Maria R; Specht, Lena; Skovgaard, Gunhild L

2008-01-01

causes and did not complete treatment. Acute side effects included desquamation, xerosis, and erythema of the skin. No severe side effects were observed. CONCLUSION: Low-dose total skin electron beam therapy can induce complete and partial responses in Stage IB-II mycosis fungoides; however, the duration......PURPOSE: To determine the effect of low-dose (4 Gy) total skin electron beam therapy as a second-line treatment of Stage IB-II mycosis fungoides in a prospective, open-label study. METHODS AND MATERIALS: Ten patients (6 men, 4 women, average age 68.7 years [range, 55-82 years......]) with histopathologically confirmed mycosis fungoides T2-T4 N0-N1 M0 who did not achieve complete remission or relapsed within 4 months after treatment with psoralen plus ultraviolet-A were included. Treatment consisted of low-dose total skin electron beam therapy administered at a total skin dose of 4 Gy given in 4...

Combination of MALDI-MSI and cassette dosing for evaluation of drug distribution in human skin explant

DEFF Research Database (Denmark)

Sørensen, Isabella S; Janfelt, Christian; Nielsen, Mette Marie B

2017-01-01

Study of skin penetration and distribution of the drug compounds in the skin is a major challenge in the development of topical drug products for treatment of skin diseases. It is crucial to have fast and efficacious screening methods which can provide information concerning the skin penetration ...... that combination of MALDI-MSI and cassette dosing can be used as a medium throughput screening tool at an early stage in the drug discovery/development process. Graphical abstract Investigation of drug distribution in human skin explant by MALDI-MSI after cassette dosing....

Persistent DNA damage after high dose in vivo gamma exposure of minipig skin.

Directory of Open Access Journals (Sweden)

Emad A Ahmed

Full Text Available Exposure to high doses of ionizing radiation (IR can lead to localized radiation injury of the skin and exposed cells suffer dsDNA breaks that may elicit cell death or stochastic changes. Little is known about the DNA damage response after high-dose exposure of the skin. Here, we investigate the cellular and DNA damage response in acutely irradiated minipig skin.IR-induced DNA damage, repair and cellular survival were studied in 15 cm(2 of minipig skin exposed in vivo to ~50 Co-60 γ rays. Skin biopsies of control and 4 h up to 96 days post exposure were investigated for radiation-induced foci (RIF formation using γ-H2AX, 53BP1, and active ATM-p immunofluorescence. High-dose IR induced massive γ-H2AX phosphorylation and high 53BP1 RIF numbers 4 h, 20 h after IR. As time progressed RIF numbers dropped to a low of 3-fold elevated at all subsequent time points. Replicating basal cells (Ki67+ were reduced 3 days post IR followed by increased proliferation and recovery of epidermal cellularity after 28 days.Acute high dose irradiation of minipig epidermis impaired stem cell replication and induced elevated apoptosis from 3 days onward. DNA repair cleared the high numbers of DBSs in skin cells, while RIFs that persisted in <1% cells marked complex and potentially lethal DNA damage up to several weeks after exposure. An elevated frequency of keratinocytes with persistent RIFs may thus serve as indicator of previous acute radiation exposure, which may be useful in the follow up of nuclear or radiological accident scenarios.

Increased dose near the skin due to electromagnetic surface beacon transponder.

Science.gov (United States)

Ahn, Kang-Hyun; Manger, Ryan; Halpern, Howard J; Aydogan, Bulent

2015-05-08

The purpose of this study was to evaluate the increased dose near the skin from an electromagnetic surface beacon transponder, which is used for localization and tracking organ motion. The bolus effect due to the copper coil surface beacon was evaluated with radiographic film measurements and Monte Carlo simulations. Various beam incidence angles were evaluated for both 6 MV and 18 MV experimentally. We performed simulations using a general-purpose Monte Carlo code MCNPX (Monte Carlo N-Particle) to supplement the experimental data. We modeled the surface beacon geometry using the actual mass of the glass vial and copper coil placed in its L-shaped polyethylene terephthalate tubing casing. Film dosimetry measured factors of 2.2 and 3.0 enhancement in the surface dose for normally incident 6 MV and 18 MV beams, respectively. Although surface dose further increased with incidence angle, the relative contribution from the bolus effect was reduced at the oblique incidence. The enhancement factors were 1.5 and 1.8 for 6 MV and 18 MV, respectively, at an incidence angle of 60°. Monte Carlo simulation confirmed the experimental results and indicated that the epidermal skin dose can reach approximately 50% of the dose at dmax at normal incidence. The overall effect could be acceptable considering the skin dose enhancement is confined to a small area (~ 1 cm2), and can be further reduced by using an opposite beam technique. Further clinical studies are justified in order to study the dosimetric benefit versus possible cosmetic effects of the surface beacon. One such clinical situation would be intact breast radiation therapy, especially large-breasted women.

Time and dose-related changes in the thickness of pig skin after irradiation with single doses of [sup 90]Sr/[sup 90]Y [beta]-rays

Energy Technology Data Exchange (ETDEWEB)

Rezvani, M.; Hamlet, R.; Hopewell, J.W.; Sieber, V.K. (Churchill Hospital, Oxford (United Kingdom))

1994-04-01

Time-related changes in pig skin thickness have been evaluated using a non-invasive ultrasound technique after exposure to a range of single doses of [sup 90]Sr/[sup 90]Yr [beta]-rays. The reduction in relative skin thickness developed in two distinct phases: the first was between 12 and 20 weeks postirradiation. No further changes were then seen until 52 weeks postirradiation when a second phase of skin thinning was observed. This was complete after 76 weeks and no further changes in relative skin thickness were seen in the maximum follow up period of 129 weeks. The timings of these phases of damage were independent of the radiation dose, however, the severity of both phases of radiation-induced skin thinning were dose related. (Author).

Skin dose reduction by a clinically viable magnetic deflector

Energy Technology Data Exchange (ETDEWEB)

Butson, M.J.; Carolan, M.; Metcalfe, J.N. [Illawarra Cancer Centre, NSW (Australia). Department of Radiotherapy]|[University of Wollongong, NSW (Australia). Department of Physics; Mathur, J.N. [University of Wollongong, NSW (Australia). Department of Physics; Yu, P.; Young, E. [City University of Hong Kong, Kowloon (Hong Kong). Department of Physics; Kan, M. [Hong Kong Polytechnic University, Kowloon (Hong Kong). Department of Optometry and Radiography]|[City University of Hong Kong, Kowloon (Hong Kong). Department of Physics

1997-06-01

A variable magnetic deflector which attaches onto the treatment head of a linear accelerator has reduced skin dose by as much as 65% for 6MV x-rays. The magnetic deflector is constructed from Neodymium Iron Boron (NdFeB) rare earth magnets. It weighs approximately 15 kg and is designed to easily fit onto the accessory mount of a clinical linear accelerator. All field sizes are attainable up to 35 cm x 35 cm at 100 cm SSD. The gap between the magnetic poles can be adjusted, providing the highest field strength for each field size. Magnetic field strengths up to 0.55 Tesla are attainable. For a 6MV x-ray beam with a 10 mm perspex block tray, surface dose is reduced from 29% to 14% and from 59% to 37% for a 20 cm x 20 cm and 35 cm x 35 cm field size, respectively. Results at varying SSD`s have shown at least 10 cm of space must be allowed between the magnets and patient for adequate reduction of skin dose through removal of electron contaminants. (authors). 14 refs., 6 figs.

Rate air Kerma entrance skin of patients undergoing hemodynamic procedures in the State of Santa Catarina, Brazil; Taxa de Kerma no ar na entrada da pele de pacientes submetidos a procedimentos hemodinamicos no Estado de Santa Catarina

Energy Technology Data Exchange (ETDEWEB)

Queiroz, Carlos Eduardo B.; Grechi, Bruna E.; Hahn, Tiago T.; Dalcin, Rodrigo C.; Augusto, Israel J.; Bolzan, Vagner; Jahn, Tiago R.; Gerber Junior, Walmoli, E-mail: brasilrad@brasilrad.com.br [Brasilrad - Consultoria em Radioprotecao, Florianopolis, SC (Brazil)

2013-12-15

This paper presents the results of the measured values of the skin entrance Air Kerma Rate in patients submitted to hemodynamic procedures, in the State of Santa Catarina, using as limit values set by the International Basic Safety Standards Guide, published by the International Atomic Energy Agency (IAEA ), and comparing them to the limits established by the Ordinance No. 453/1998. Tests were performed to measure the rate of Kerma skin entrance in 13 hemodynamic equipment in 10 hospitals in the state of Santa Catarina, between January 2011 and December 2012, in hemodynamic operated through fluoroscopy mode. Among the evaluated equipment, 77% disagree with the limits established in the International Basic Safety Standards, however, if compared the values of the Air Kerma rate obtained with the limit established by Ordinance No. 453, 100% of the devices are approved. The results obtained in this paper suggest the need for revision of the Ordinance No. 453/1998, by the regulatory agencies. (author)

Clinical application of a OneDose(TM) MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast

International Nuclear Information System (INIS)

Kinhikar, Rajesh A; Sharma, Pramod K; Tambe, Chandrashekhar M; Mahantshetty, Umesh M; Sarin, Rajiv; Deshpande, Deepak D; Shrivastava, Shyam K

2006-01-01

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose(TM) in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs. (note)

Fractional sunburn threshold UVR doses generate equivalent vitamin D and DNA damage in skin types I-VI, but with epidermal DNA damage gradient correlated to skin darkness.

Science.gov (United States)

Shih, Barbara B; Farrar, Mark D; Cooke, Marcus S; Osman, Joanne; Langton, Abigail K; Kift, Richard; Webb, Ann R; Berry, Jacqueline L; Watson, Rachel E B; Vail, Andy; de Gruijl, Frank R; Rhodes, Lesley E

2018-05-03

Public health guidance recommends limiting sun-exposure to sub-sunburn levels, but it's unknown whether these can gain vitamin D (for musculoskeletal health) whilst avoiding epidermal DNA damage (initiates skin cancer). Well-characterised healthy humans of all skin types (I-VI; lightest to darkest skin) were exposed to a low dose-series of solar simulated UVR of 20-80% their individual sunburn threshold dose (minimal erythemal dose, MED). Significant UVR dose-responses were seen for serum 25(OH)D and whole epidermal CPD, with as little as 0.2 MED concurrently producing 25(OH)D and CPD. Notably, fractional MEDs generated equivalent levels of whole epidermal CPD and 25(OH)D across all skin types. Crucially, we demonstrated an epidermal gradient of CPD formation strongly correlated with skin darkness (r=0.74; Pskin types, ranging from darkest skin, where high CPD levels occurred superficially with none in the germinative basal layer, through to lightest skin where CPD were induced evenly across the epidermal depth. Darker skin people can be encouraged to utilise sub-sunburn UVR-exposure to enhance their vitamin D. In lighter skin people, basal cell damage occurs concurrent with vitamin D synthesis at exquisitely low UVR levels, providing an explanation for their high skin cancer incidence; greater caution is required. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Skin dose from distributed radioactive sources and hot particles - Regulations and recommendations

International Nuclear Information System (INIS)

Porter, S.W.

1991-01-01

The issues concerning Beta Dosimetry, Hot Particle Dosimetry, and associated dose to skin have been highlighted since the 1979 TMI-2 accident report of the Presidential Commission. The conclusions drawn from the DOE/EML International Beta Dosimetry Symposium of 1983 are still valid. The questions of location(s) of the radiosensitive layer of human skin, the most valid method of skin dose measurement and interpretation of associated radiobiological data are still lingering. The need for improving beta calculation standards and procedures are more evident now than in 1983. This paper will discuss the newest ICRP and NCRP recommendations, as well as the regulations and guidelines from the NRC. I would expect that the draft recommendations published in this paper will be considerably changed by the time of the January, 1991 presentation of this paper

Dosimetric effects of thermoplastic immobilizing devices on skin dose

International Nuclear Information System (INIS)

Adu-Poku Olivia

2017-07-01

This work shows the increase in surface dose caused by thermoplastic immobilizing masks used for positioning and immobilization of patients. Thermoplastics are organic materials which soften when they are heated. They can be formed after softening and retain their final shape when cooled. The use of these thermoplastic masks are relevant during patient treatment. However, it can lead to an increased skin dose. Measurements were done at source-to-surface distance of 80 cm for external radiation beams produced by cobalt 60 using the Farmer type ionization chamber and the Unidos electrometer. Measurements were carried out using various mask thicknesses and no mask material on a solid water phantom. The thermoplastic percentage depth dose (PDD), equivalent thickness of water of the various thicknesses of the mask and surface doses were determined. The increase in the surface dose caused by the thermoplastic mask was compared by looking at the PDD at depth 0 with and without the mask present and was found to increase between 0.76 and 0.79% with no mask for a field size of 5 x 5 cm 2 . It was found that, the presence of the mask shifted the percentage depth dose curve to lower values. The physical thermoplastic thickness was measured to be between 2.30 and 1.80 mm, and the equivalent thicknesses of water, d e , were determined to be 1.2, 1.15, 1.10 and 1.09 and 1.00 mm for the unstretched, 5 cm stretched, 10 cm stretched, 15 cm stretched and 20 cm stretched masks, respectively. This meant that, as the mask thickness decreased, its water equivalent thickness also decreased. The presence of the mask material did not increase the skin dose significantly ( less than 1%). (au)

Assessment of patients' skin dose during interventional cardiology procedures

International Nuclear Information System (INIS)

Tsapaki, V.; Vardalaki, E.; Kottou, S.; Molfetas, M.; Neofotistou, V.

2002-01-01

During the last 30 years the use of Interventional Cardiology (IC) procedures has increased significantly, mainly due to the benefits and advantages of the method that offers more accurate diagnosis and treatment along with less complications and hospitalization. However, IC procedures are based on the use of x-ray radiation, mostly localized at certain areas of patient's body and for extended periods of time. Consequently, patient may receive high radiation dose and deterministic effects, such as erythema, epilation or even dermal necrosis may be observed. Therefore, the need for reducing radiation dose is highly important. In order to achieve this, good knowledge of the dose levels delivered to the patient during IC procedures is essential since radiation effects are known to increase with dose. It is of great interest to know the point where the maximum skin dose (MSD) is noted since individual sensitivity may vary. MSDs greater than 1 Gy should be recorded. Patient dosimetry during IC procedures is a complex task since these type of procedures depend on various factors, such as complexity and severity of case, different specifications of x-ray equipment and patient's physical characteristics. Moreover, cardiologist's experience plays an important role. For these reasons, Food and Drug Administration (FDA), the International Commission on Radiological Protection (ICRP) as well as the World Health Organization (WHO), have published documents on radiation safety and ways to reduce skin injuries during IC procedures. Various methods have been proposed for measuring MSD such as the use of slow radiotherapy films, thermoluminescent detectors (TLD), scintillation detectors, Dose-Area Product (DAP) meter, as well as a combination of DAP and air kerma. A literature review on MSDs measured during IC procedures showed that doses ranged from 300 to 43000 mGy

Assessment of skin dose modification caused by application of immobilizing cast in head and neck radiotherapy

International Nuclear Information System (INIS)

Soleymanifard, Shokouhozaman; Toossi, Mohammad T.B.; Khosroabadi, Mohsen; Noghreiyan, Atefeh Vejdani; Shahidsales, Soodabeh; Tabrizi, Fatemeh Varshoee

2014-01-01

Skin dose assessment for radiotherapy patients is important to ensure that the dose received by skin is not excessive and does not cause skin reactions. Immobilizing casts may have a buildup effect, and can enhance the skin dose. This study has quantified changes to the surface dose as a result of head and neck immobilizing casts. Medtech and Renfu casts were stretched on the head of an Alderson Rando-Phantom. Irradiation was performed using 6 and 15 MV X-rays, and surface dose was measured by thermoluminescence dosimeters. In the case of 15MV photons, immobilizing casts had no effect on the surface dose. However, the mean surface dose increase reached up to 20 % when 6MV X-rays were applied. Radiation incidence angle, thickness, and meshed pattern of the casts affected the quantity of dose enhancement. For vertical beams, the surface dose increase was more than tangential beams, and when doses of the points under different areas of the casts were analysed separately, results showed that only doses of the points under the thick area had been changed. Doses of the points under the thin area and those within the holes were identical to the same points without immobilizing casts. Higher dose which was incurred due to application of immobilizing casts (20 %) would not affect the quality of life and treatment of patients whose head and neck are treated. Therefore, the benefits of head and neck thermoplastic casts are more than their detriments. However, producing thinner casts with larger holes may reduce the dose enhancement effect.

Skin Dose Assessment by Hot Particles in Domestic Nuclear Power Plant

International Nuclear Information System (INIS)

Choi, Bo Yeol; Cho, Woon Kap; Lee, Jai Ki

2009-01-01

Since a contamination event by hot particles happened due to damaged nuclear fuel at a nuclear power plant (NPP) in the 1980's, skin exposure resulted from hot particles has gotten considerable attention from all the radiation workers in the nuclear industry. In particular, contamination incident caused by hot particles which happened at a NPP in Susquehanna proved that there existed hot particles with the radioactivity of 0.7 GBq, 0.78 GBq, and even 2.78 GBq at maximum. One of these particles was found on a worker's shoe and gave out a dose of 170 mSv. Although there has been no contamination event reported in domestic NPPs which are caused by hot particles, it is hard to conclude that there is no possibility of such contamination for radiation workers. The contaminated samples employed in this study were taken from local NPPs and supposes a case of a worker's skin contaminated by hot particles to evaluate the dose provided to the worker's skin

The response of mouse skin to multiple small doses of radiation

International Nuclear Information System (INIS)

Denekamp, J.; Harris, S.R.

1975-01-01

The response of mouse skin has been tested by irradiating the foot of albino mice and scoring erythema and desquamation during the following month. Multiple small doses of 150, 250 and 350 rad have been given 'daily', and the test dose necessary to achieve a given reaction has been determined one day after the last small fraction. This test dose has been compared with the single dose necessary to produce the same reaction level in previously untreated mice, in order to determine the ratio of the slopes of the dose-response curve at low and high doses: Slope ratio = (single dose - test dose)/total fractionated priming dose. In three separate experiments the slope ratio decreased as the dose per fraction was reduced from 350 to 150 rad. This conflicts with the data of Dutreix et al, who found a constant slope ratio over this dose range. The present data are compared with those obtained by Denekamp using 4, 9 and 14 fractions of 300 rad and by Douglas et al, using the same experimental technique, over the dose range 45 to 200 rad/fraction. In addition, the results from multifraction experiments in which equal dose increments were administered until the requisite skin reaction was achieved are also analysed in terms of their slope ratio (Fowler et al. Douglas et al). When all these results are plotted it is impossible to be sure whether the slope ratio is decreasing over the range 300 to 45 rad per fraction, although it seems likely. Most of the values at low doses lie in the range 0.15 to 0.25, indicating that at low doses the radiation is only 15 to 25% as effective per rad in causing cell death as at higher doses. (author)

Nuclear fuel particles in the environment - characteristics, atmospheric transport and skin doses

Energy Technology Data Exchange (ETDEWEB)

Poellaenen, R

2002-05-01

In the present thesis, nuclear fuel particles are studied from the perspective of their characteristics, atmospheric transport and possible skin doses. These particles, often referred to as 'hot' particles, can be released into the environment, as has happened in past years, through human activities, incidents and accidents, such as the Chernobyl nuclear power plant accident in 1986. Nuclear fuel particles with a diameter of tens of micrometers, referred to here as large particles, may be hundreds of kilobecquerels in activity and even an individual particle may present a quantifiable health hazard. The detection of individual nuclear fuel particles in the environment, their isolation for subsequent analysis and their characterisation are complicated and require well-designed sampling and tailored analytical methods. In the present study, the need to develop particle analysis methods is highlighted. It is shown that complementary analytical techniques are necessary for proper characterisation of the particles. Methods routinely used for homogeneous samples may produce erroneous results if they are carelessly applied to radioactive particles. Large nuclear fuel particles are transported differently in the atmosphere compared with small particles or gaseous species. Thus, the trajectories of gaseous species are not necessarily appropriate for calculating the areas that may receive large particle fallout. A simplified model and a more advanced model based on the data on real weather conditions were applied in the case of the Chernobyl accident to calculate the transport of the particles of different sizes. The models were appropriate in characterising general transport properties but were not able to properly predict the transport of the particles with an aerodynamic diameter of tens of micrometers, detected at distances of hundreds of kilometres from the source, using only the current knowledge of the source term. Either the effective release height has

Capture and analysis of radiation dose reports for radiology

International Nuclear Information System (INIS)

Midgley, S.M.

2014-01-01

Radiographic imaging systems can produce records of exposure and dose parameters for each patient. A variety of file formats are in use including plain text, bit map images showing pictures of written text and radiation dose structured reports as text or extended markup language files. Whilst some of this information is available with image data on the hospital picture archive and communication system, access is restricted to individual patient records, thereby making it difficult to locate multiple records for the same scan protocol. This study considers the exposure records and dose reports from four modalities. Exposure records for mammography and general radiography are utilized for repeat analysis. Dose reports for fluoroscopy and computed tomography (CT) are utilized to study the distribution of patient doses for each protocol. Results for dosimetric quantities measured by General Radiography, Fluoroscopy and CT equipment are summarised and presented in the Appendix. Projection imaging uses the dose (in air) area product and derived quantities including the dose to the reference point as a measure of the air kerma reaching the skin, ignoring movement of the beam for fluoroscopy. CT uses the dose indices CTDIvol and dose length product as a measure of the dose per axial slice, and to the scanned volume. Suitable conversion factors are identified and used to estimate the effective dose to an average size patient (for CT and fluoroscopy) and the entrance skin dose for fluoroscopy.

Dosimetric quality of postal kit used for evaluation in IRD/CNEN of radiation protection parameters in dental radiology in the State of Rio de Janeiro; Qualidade dosimetrica do kit postal utilizado pelo IRD/CNEN para a avaliacao dos parametros de radioprotecao em radiologia odontologica no Estado do Rio de Janeiro

Energy Technology Data Exchange (ETDEWEB)

Coutinho, Soray Abbud; Mota, Helvecio C; Dovales, Ana Cristina M [Instituto de Radioprotecao e Dosimetria (IRD), Rio de Janeiro, RJ (Brazil). Dept. de Fisica Medica

2001-07-01

This work shows the results of a comparison between the skin entrance doses determined using an ionization chamber or a postal kit routinely used for the evaluation of radiation protection parameters in dental radiology in the state of Rio de Janeiro. By using the dosimetric kit, entrance skin dose is determined from two thermoluminescent dosimeters (TLDs) - previously calibrated in a {sup 137} Cs source - by using calibration factors determined in TLDs irradiated in air, on a water phantom and on an aluminium filter. The correspondence between the doses obtained with different methods was evaluated for three different X-ray spectra as radiation source. Results indicate that calibration factors used are adequate and that the kit has enough sensibility and reproducibility, measuring properly the skin entrance dose in dental X-rays. (author)

Proposed derivation of skin contamination and skin decontamination limits

International Nuclear Information System (INIS)

Schieferdecker, H.; Koelzer, W.; Henrichs, K.

1986-01-01

From the primary dose limits for the skin, secondary dose limits were derived for skin contamination which can be used in practical radiation protection work. Analogous to the secondary dose limit for the maximum permissible body burden in the case of incorporation, dose limits for the 'maximum permissible skin burden' were calculated, with the help of dose factors, for application in the case of skin contamination. They can be derived from the skin dose limit values. For conditions in which the skin is exposed to temporary contamination, a limit of skin contamination was derived for immediately removable contamination and for one day of exposure. For non-removable contamination a dose limit of annual skin contamination was defined, taking into account the renewal of the skin. An investigation level for skin contamination was assumed, as a threshold, above which certain measures must be taken; these to include appropriate washing not more than three times, with the subsequent procedure determined by the level of residual contamination. The dose limits are indicated for selected radionuclides. (author)

Evaluation of skin surface dose for head and neck cancer patients treated with intensity-modulated radiation therapy using in vivo dosimetry

International Nuclear Information System (INIS)

Kim, Yeon Sil; Lee, Dong Soo; Yoo, Mi Na; Hong, Joo Young; Yoon, Se Chul; Jang, Hong Suk

2011-01-01

Use of intensity-modulated radiation therapy (IMRT) for head and neck cancer is gradually increasing, because it could facilitate more sophsticated treatment of target volumes and reduction of acute and late sequelae. However, theoretically, there is a potential risk of increased skin surface dose resulting from multiple obliquity effects caused by multiple tangential beams. Moreover, we sometimes confronted with more skin reactions in the patients treated with IMRT than conventional techniques. In this study, we evaluated skin surface dose adjacent to the target volumes to verify whether the use of IMRT would increase the skin dose more than we predicted. This study had shown that the use of IMRT did not increase the skin surface hot point dose. The measured skin surface dose was 20 to 40 percent of the adjacent target prescription dose, and was within acceptable dose range. Our study had some limitations with small number of experimental patients and methodological problems. Potential risk of increasing skin dose with bolus effect of aquaplaster should be examined in the future trials. In addition, the accurate set-up verification should be maintained because of steep dose gradient between skin surface and target volumes within a short distance in the head and neck cancer patients.

Multiple methods for assessing the dose to skin exposed to radioactive contamination

International Nuclear Information System (INIS)

Dubeau, J.; Heinmiller, B.E.; Corrigan, M.

2017-01-01

There is the possibility for a worker at a nuclear installation, such as a nuclear power reactor, a fuel production facility or a medical facility, to come in contact with radioactive contaminants. When such an event occurs, the first order of business is to care for the worker by promptly initiating a decontamination process. Usually, the radiation protection personnel performs a G-M pancake probe measurement of the contamination in situ and collects part or all of the radioactive contamination for further laboratory analysis. The health physicist on duty must then perform, using the available information, a skin dose assessment that will go into the worker's permanent dose record. The contamination situations are often complex and the dose assessment can be laborious. This article compares five dose assessment methods that involve analysis, new technologies and new software. The five methods are applied to 13 actual contamination incidents consisting of direct skin contact, contamination on clothing and contamination on clothing in the presence of an air gap between the clothing and the skin. This work shows that, for the cases studied, the methods provided dose estimates that were usually within 12% (1σ) of each other, for those cases where absolute activity information for every radionuclide was available. One method, which relies simply on a G-M pancake probe measurement, appeared to be particularly useful in situations where a contamination sample could not be recovered for laboratory analysis. (authors)

Benefits of the effective dose equivalent concept at a medical center

International Nuclear Information System (INIS)

Vetter, R.J.; Classic, K.L.

1991-01-01

A primary objective of the recommendations of the International Committee on Radiological Protection Publication 26 is to insure that no source of radiation exposure is unjustified in relation to its benefits. This objective is consistent with goals of the Radiation Safety Committee and Institutional Review Board at medical centers where research may involve radiation exposure of human subjects. The effective dose equivalent concept facilitates evaluation of risk by those who have little or no knowledge of quantities or biological effects of radiation. This paper presents effective dose equivalent data used by radiation workers and those who evaluate human research protocols as these data relate to personal dosimeter reading, entrance skin exposure, and target organ dose. The benefits of using effective dose equivalent to evaluate risk of medical radiation environments and research protocols are also described

Incorporating partial shining effects in proton pencil-beam dose calculation

International Nuclear Information System (INIS)

Li Yupeng; Zhang Xiaodong; Lii Mingfwu; Sahoo, Narayan; Zhu, Ron X; Gillin, Michael; Mohan, Radhe

2008-01-01

A range modulator wheel (RMW) is an essential component in passively scattered proton therapy. We have observed that a proton beam spot may shine on multiple steps of the RMW. Proton dose calculation algorithms normally do not consider the partial shining effect, and thus overestimate the dose at the proximal shoulder of spread-out Bragg peak (SOBP) compared with the measurement. If the SOBP is adjusted to better fit the plateau region, the entrance dose is likely to be underestimated. In this work, we developed an algorithm that can be used to model this effect and to allow for dose calculations that better fit the measured SOBP. First, a set of apparent modulator weights was calculated without considering partial shining. Next, protons spilled from the accelerator reaching the modulator wheel were simplified as a circular spot of uniform intensity. A weight-splitting process was then performed to generate a set of effective modulator weights with the partial shining effect incorporated. The SOBPs of eight options, which are used to label different combinations of proton-beam energy and scattering devices, were calculated with the generated effective weights. Our algorithm fitted the measured SOBP at the proximal and entrance regions much better than the ones without considering partial shining effect for all SOBPs of the eight options. In a prostate patient, we found that dose calculation without considering partial shining effect underestimated the femoral head and skin dose

Using a thermoluminescent dosimeter to evaluate the location reliability of the highest–skin dose area detected by treatment planning in radiotherapy for breast cancer

Energy Technology Data Exchange (ETDEWEB)

Sun, Li-Min, E-mail: limin.sun@yahoo.com [Department of Radiation Oncology, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China); Huang, Chih-Jen [Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan (China); Faculty of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan (China); College of Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan (China); Chen, Hsiao-Yun [Department of Radiation Oncology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung City, Taiwan (China); Meng, Fan-Yun [Department of General Surgery, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China); Lu, Tsung-Hsien [Department of Radiation Oncology, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China); Tsao, Min-Jen [Department of General Surgery, Zuoying Branch of Kaohsiung Armed Forces General Hospital, Kaohsiung City, Taiwan (China)

2014-01-01

Acute skin reaction during adjuvant radiotherapy for breast cancer is an inevitable process, and its severity is related to the skin dose. A high–skin dose area can be speculated based on the isodose distribution shown on a treatment planning. To determine whether treatment planning can reflect high–skin dose location, 80 patients were collected and their skin doses in different areas were measured using a thermoluminescent dosimeter to locate the highest–skin dose area in each patient. We determined whether the skin dose is consistent with the highest-dose area estimated by the treatment planning of the same patient. The χ{sup 2} and Fisher exact tests revealed that these 2 methods yielded more consistent results when the highest-dose spots were located in the axillary and breast areas but not in the inframammary area. We suggest that skin doses shown on the treatment planning might be a reliable and simple alternative method for estimating the highest skin doses in some areas.

Using a thermoluminescent dosimeter to evaluate the location reliability of the highest–skin dose area detected by treatment planning in radiotherapy for breast cancer

International Nuclear Information System (INIS)

Sun, Li-Min; Huang, Chih-Jen; Chen, Hsiao-Yun; Meng, Fan-Yun; Lu, Tsung-Hsien; Tsao, Min-Jen

2014-01-01

Acute skin reaction during adjuvant radiotherapy for breast cancer is an inevitable process, and its severity is related to the skin dose. A high–skin dose area can be speculated based on the isodose distribution shown on a treatment planning. To determine whether treatment planning can reflect high–skin dose location, 80 patients were collected and their skin doses in different areas were measured using a thermoluminescent dosimeter to locate the highest–skin dose area in each patient. We determined whether the skin dose is consistent with the highest-dose area estimated by the treatment planning of the same patient. The χ 2 and Fisher exact tests revealed that these 2 methods yielded more consistent results when the highest-dose spots were located in the axillary and breast areas but not in the inframammary area. We suggest that skin doses shown on the treatment planning might be a reliable and simple alternative method for estimating the highest skin doses in some areas

The study on clinical conditions and skin dose of upper-gastrointestinal x-ray fluoroscopy

International Nuclear Information System (INIS)

Kim, Sung Chul; Ahn, Sung Min; Jang, Sang Sup

2007-01-01

This study examined present conditions of upper-gastrointestinal X-ray fluoroscopy and patient skin dose. The authors elected 21 equipment to check the X-ray equipment and exposure factor of fluoroscopy and spot exposure in university hospitals, hospitals, and clinics where perform upper-gastrointestinal X-ray fluoroscopy more than five times every day in Incheon areas. The amount of patient's skin dose during upper-gastrointestinal X-ray fluoroscopy was measured by ionization chamber

The radiation dose from a proposed measurement of arsenic and selenium in human skin

Energy Technology Data Exchange (ETDEWEB)

Gherase, Mihai R; Mader, Joanna E; Fleming, David E B, E-mail: mgherase@mta.c [Department of Physics, Mount Allison University, 67 York Street, Sackville, NB E4L 1E6 (Canada)

2010-09-21

Dose measurements following 10 min irradiations with a portable x-ray fluorescence spectrometer composed of a miniature x-ray tube and a silicon PiN diode detector were performed using thermoluminescent dosimeters consisting of LiF:Mg,Ti chips of 3 mm diameter and 0.4 mm thickness. The table-top setup of the spectrometer was used for all measurements. The setup included a stainless steel lid which served as a radiation shield. Two rectangular polyethylene skin/soft tissue phantoms with two cylindrical plaster of Paris bone phantoms were used to study the effect of x-ray beam attenuation and backscatter on the measured dose. Eight different irradiation experiments were performed. The average dose rate values measured with TLD chips within a 1 x 1 cm{sup 2} area were between 4.8 and 12.8 mGy min{sup -1}. The equivalent dose for a 1 x 1 cm{sup 2} skin area was estimated to be 13.2 mSv. The maximum measured dose rate values with a single TLD chip were between 7.5 and 25.1 mGy min{sup -1}. The effective dose corresponding to a proposed arsenic/selenium skin measurement was estimated to be 0.13 {mu}Sv for a 2 min irradiation.

An effective dose assessment technique with NORM added consumer products using skin-point source on computational human phantom

International Nuclear Information System (INIS)

Yoo, Do Hyeon; Shin, Wook-Geun; Lee, Hyun Cheol; Choi, Hyun Joon; Testa, Mauro; Lee, Jae Kook; Yeom, Yeon Soo; Kim, Chan Hyeong; Min, Chul Hee

2016-01-01

The aim of this study is to develop the assessment technique of the effective dose by calculating the organ equivalent dose with a Monte Carlo (MC) simulation and a computational human phantom for the naturally occurring radioactive material (NORM) added consumer products. In this study, we suggests the method determining the MC source term based on the skin-point source enabling the convenient and conservative modeling of the various type of the products. To validate the skin-point source method, the organ equivalent doses were compared with that by the product modeling source of the realistic shape for the pillow, waist supporter, sleeping mattress etc. Our results show that according to the source location, the organ equivalent doses were observed as the similar tendency for both source determining methods, however, it was observed that the annual effective dose with the skin-point source was conservative than that with the modeling source with the maximum 3.3 times higher dose. With the assumption of the gamma energy of 1 MeV and product activity of 1 Bq g"−"1, the annual effective doses of the pillow, waist supporter and sleeping mattress with skin-point source was 3.09E-16 Sv Bq"−"1 year"−"1, 1.45E-15 Sv Bq"−"1 year"−"1, and 2,82E-16 Sv Bq"−"1 year"−"1, respectively, while the product modeling source showed 9.22E-17 Sv Bq"−"1 year"−"1, 9.29E-16 Sv Bq"−"1 year"−"1, and 8.83E-17 Sv Bq"−"1 year"−"1, respectively. In conclusion, it was demonstrated in this study that the skin-point source method could be employed to efficiently evaluate the annual effective dose due to the usage of the NORM added consumer products. - Highlights: • We evaluate the exposure dose from the usage of NORM added consumer products. • We suggest the method determining the MC source term based on the skin-point source. • To validate the skin-point source, the organ equivalent doses were compared with that the modeling source. • The skin-point source could

Skin dose rate conversion factors after contamination with radiopharmaceuticals: influence of contamination area, epidermal thickness and percutaneous absorption

International Nuclear Information System (INIS)

Covens, P; Berus, D; Caveliers, V; Struelens, L; Vanhavere, F; Verellen, D

2013-01-01

Skin contamination with radiopharmaceuticals can occur during biomedical research and daily nuclear medicine practice as a result of accidental spills, after contact with bodily fluids of patients or by inattentively touching contaminated materials. Skin dose assessment should be carried out by repeated quantification to map the course of the contamination together with the use of appropriate skin dose rate conversion factors. Contamination is generally characterised by local spots on the palmar surface of the hand and complete decontamination is difficult as a result of percutaneous absorption. This specific issue requires special consideration as to the skin dose rate conversion factors as a measure for the absorbed dose rate to the basal layer of the epidermis. In this work we used Monte Carlo simulations to study the influence of the contamination area, the epidermal thickness and the percutaneous absorption on the absorbed skin dose rate conversion factors for a set of 39 medical radionuclides. The results show that the absorbed dose to the basal layer of the epidermis can differ by up to two orders of magnitude from the operational quantity H p (0.07) when using an appropriate epidermal thickness in combination with the effect of percutaneous absorption. (paper)

Rat skin carcinogenesis as a basis for estimating risks at low doses and dose rates of various types of radiation

International Nuclear Information System (INIS)

Burns, F.J.; Vanderlaan, M.; Strickland, P.; Albert, R.E.

1976-01-01

The recovery rate, age dependence and latent period for tumor induction in rat skin were measured for single and split doses of radiation, and the data were analyzed in terms of a general model in an attempt to estimate the expected tumor response for various types of radiation given at low dose rates for long periods of time. The dorsal skin of male rats was exposed to electrons, x rays, or protons in either single or split doses for several doses and the tumor responses were compared during 80 weeks of observation. A two stage model incorporating a reversible or recoverable mode was developed and various parameters in the model, including recovery rate, dose-response coefficients, and indices of age sensitivity, were evaluated experimentally. The measured parameters were then utilized to calculate expected tumor responses for exposure periods extending for duration of life. The calculations indicated that low dose rates could be markedly ( 1 / 100 to 1 / 1000 ) less effective in producing tumors than the same dose given in a short or acute exposure, although the magnitude of the reduction in effectiveness declines as the dose declines

Evaluation of Skin Dose and Image Quality on Cone Beam Computed Tomography

International Nuclear Information System (INIS)

Ahn, Jong Ho; Hong, Chae Seon; Kim, Jin Man; Jang, Jun Young

2008-01-01

Cone-beam CT using linear accelerator attached to on-board imager is a image guided therapy equipment. Because it is to check the patient's set-up error, correction, organ and target movement. But imaging dose should be cause of the secondary cancer when taking a image. The aim of this study is investigation of appropriate cone beam CT scan mode to compare and estimate the image quality and skin dose. Measurement by Thermoluminescence dosimeter (TLD-100, Harshaw) with using the Rando phantom are placed on each eight sites in separately H and N, thoracic, abdominal section. each 4 methods of scan modes of are measured the for skin dose in three time. Subsequently, obtained average value. Following image quality QA protocol of equipment manufacturers using the catphan 504 phantom, image quality of each scan mode is compared and analyzed. The results of the measured skin dose are described in here. The skin dose of Head and Neck are measured mode A: 8.96 cGy, mode B: 4.59 cGy, mode C: 3.46 cGy mode D: 1.76 cGy and thoracic mode A: 9.42 cGy, mode B: 4.58 cGy, mode C: 3.65 cGy, mode D: 1.85 cGy, and abdominal mode A: 9.97 cGy, mode B: 5.12 cGy, mode C: 4.03 cGy, mode D: 2.21 cGy. Approximately, dose of mode B are reduced 50%, mode C are reduced 60%, mode D are reduced 80% a point of reference dose of mode A. the results of analyzed HU reproducibility, low contrast resolution, spatial resolution (high contrast resolution), HU uniformity in evaluation item of image quality are within the tolerance value by recommended equipment manufacturer in all scan mode. Maintaining the image quality as well as reducing the image dose are very important in cone beam CT. In the result of this study, we are considered when to take mode A when interested in soft tissue. And we are considered to take mode D when interested in bone scan and we are considered to take mode B, C when standard scan. Increasing secondary cancer risk due to cone beam CT scan should be reduced by low m

Pediatric patient doses in interventional cardiology procedures; Doses em paciente pediatrico em procedimentos de cardiologia intervencionista

Energy Technology Data Exchange (ETDEWEB)

Medeiros, R.B.; Murata, C.H.; Moreira, A.C., E-mail: rbitelli2012@gmail.com, E-mail: camila.murata@gmail.com, E-mail: antonio.xray@gmail.com [Universidade Federal de Sao Paulo (UNIFESP), Sao Paulo, SP (Brazil). Escola Pulista de Medicina; Khoury, H.J.; Borras, C., E-mail: hjkhoury@gmail.com, E-mail: cariborras@starpower.net [Universidade Federal de Pernambuco (DEN/UFPE), Recife, PE (Brazil). Dept. de Engenharia Nuclear; Silva, M.S.R da, E-mail: msrochas2003@yahoo.com.br [Instituto Federal de Educacao, Ciencia e Tecnologia de Pernambuco (IFPE), Recife, PE (Brazil)

2014-07-01

The radiation doses from interventional procedures is relevant when treating children because of their greater radiosensitivity compared with adults. The purposes of this paper were to estimate the dose received by 18 pediatric patients who underwent cardiac interventional procedures and to correlate the maximum entrance surface air kerma (Ke,max), estimated with radiochromic films, with the cumulative air kerma values displayed at the end of procedures. This study was performed in children up to 6 years. The study was performed in two hospitals, one located in Recife and the other one in São Paulo. The x-ray imaging systems used were Phillips Allura 12 model with image intensifier system and a Phillips Allura FD10 flat panel system. To estimate the Ke,max on the patient’s skin radiochromic films(Gafchromic XR-RV2) were used. These values were estimated from the maximum optical density measured on film using a calibration curve. The results showed cumulative air kerma values ranging from 78.3- 500.0mGy, with a mean value of 242,3 mGy. The resulting Ke,max values ranged from 20.0-461.8 mGy, with a mean value of 208,8 mGy. The Ke,max values were correlated with the displayed cumulative air kerma values. The correlation factor R² was 0.78, meaning that the value displayed in the equipment’s console can be useful for monitoring the skin absorbed dose throughout the procedure. The routine fluoroscopy time records is not able by itself alert the physician about the risk of dose exceeding the threshold of adverse reactions, which can vary from an early erythema to serious harmful skin damage. (author)

Increased Skin Dose With the Use of a Custom Mattress for Prone Breast Radiotherapy

International Nuclear Information System (INIS)

Becker, Stewart J.; Patel, Rakesh R.; Mackie, Thomas R.

2007-01-01

The purpose of this study was to measure and compare the loss of buildup to the skin of the breast in the prone position due to 2 different positioning systems during tangential external beam irradiation. Two experiments were performed; one with a standard nylon-covered foam support and another with a novel helium-filled Mylar bag support. The choice of helium-filled Mylar was to reduce the contamination to as low as possible. The experiments were designed to allow a surface dose measurement and a depth dose profile with the pads placed in the path of the beam in front of the detector. All measurements were taken using a Capintec PS-033 thin-window parallel plate ionization chamber. The standard nylon-covered foam pad caused the surface dose to rise as it got closer to the skin. When the pad was directly touching the surface, the surface dose increased by 300% compared to the result when no pad was present. This loss of buildup to the surface was similar to that of a custom bolus material. The opposite effect occurred with the use of the helium-filled Mylar bag, namely the surface dose gradually decreased as the pad got closer to the phantom. When the Mylar pad was directly touching the phantom, the surface dose was decreased by 7% compared to when no pad was present. The use of a foam pad could potentially result in a significant higher dose to the skin, resulting in an enhanced acute skin reaction. Therefore, special care should be taken in this clinical scenario and further investigation of an air- or helium-based mylar support pad should be investigated in the context of definitive breast radiation treatment

Analysis of Dose and Dose Distribution for Patients Undergoing Selected X-Ray Diagnostic Procedures in Ghana

Energy Technology Data Exchange (ETDEWEB)

Schandorf, C.; Tetteh, G.K

1998-07-01

The levels of dose and dose distributions for adult patients undergoing five selected common types of X ray examination in Ghana were determined using thermoluminescence dosemeters (TLD) attached to the skin where the beam enters the patient. To assess the performance of each X ray room surveyed, the mean of the entrance surface dose for patients whose statistics were close to a standard patient (70 kg weight and 20 cm AP trunk thickness) were compared to the Commission of the European Communities guideline values for chest PA, lumbar spine AP, pelvis/abdomen AP and skull AP examinations. The third quartiles dose values were 1.3 mGy, 14.5 mGy, 12.0 mGy and 7.9 mGy for chest PA, lumbar spine AP, pelvis/abdomen AP and skull AP respectively. Analysis of the data show that 86%, 58%, 37.5% and 50% of radiographic rooms delivered a mean dose greater than the CEC guideline values for chest PA, lumbar spine AP, pelvis/abdomen and skull AP respectively. This suggests that radiographic departments should undertake a review of their radiographic practice in order to bring their doses to optimum levels. (author)

Analysis of Dose and Dose Distribution for Patients Undergoing Selected X-Ray Diagnostic Procedures in Ghana

International Nuclear Information System (INIS)

Schandorf, C.; Tetteh, G.K.

1998-01-01

The levels of dose and dose distributions for adult patients undergoing five selected common types of X ray examination in Ghana were determined using thermoluminescence dosemeters (TLD) attached to the skin where the beam enters the patient. To assess the performance of each X ray room surveyed, the mean of the entrance surface dose for patients whose statistics were close to a standard patient (70 kg weight and 20 cm AP trunk thickness) were compared to the Commission of the European Communities guideline values for chest PA, lumbar spine AP, pelvis/abdomen AP and skull AP examinations. The third quartiles dose values were 1.3 mGy, 14.5 mGy, 12.0 mGy and 7.9 mGy for chest PA, lumbar spine AP, pelvis/abdomen AP and skull AP respectively. Analysis of the data show that 86%, 58%, 37.5% and 50% of radiographic rooms delivered a mean dose greater than the CEC guideline values for chest PA, lumbar spine AP, pelvis/abdomen and skull AP respectively. This suggests that radiographic departments should undertake a review of their radiographic practice in order to bring their doses to optimum levels. (author)

Underprediction of human skin erythema at low doses per fraction by the linear quadratic model

International Nuclear Information System (INIS)

Hamilton, Christopher S.; Denham, James W.; O'Brien, Maree; Ostwald, Patricia; Kron, Tomas; Wright, Suzanne; Doerr, Wolfgang

1996-01-01

Background and purpose. The erythematous response of human skin to radiotherapy has proven useful for testing the predictions of the linear quadratic (LQ) model in terms of fractionation sensitivity and repair half time. No formal investigation of the response of human skin to doses less than 2 Gy per fraction has occurred. This study aims to test the validity of the LQ model for human skin at doses ranging from 0.4 to 5.2 Gy per fraction. Materials and methods. Complete erythema reaction profiles were obtained using reflectance spectrophotometry in two patient populations: 65 patients treated palliatively with 5, 10, 12 and 20 daily treatment fractions (varying thicknesses of bolus, various body sites) and 52 patients undergoing prostatic irradiation for localised carcinoma of the prostate (no bolus, 30-32 fractions). Results and conclusions. Gender, age, site and prior sun exposure influence pre- and post-treatment erythema values independently of dose administered. Out-of-field effects were also noted. The linear quadratic model significantly underpredicted peak erythema values at doses less than 1.5 Gy per fraction. This suggests that either the conventional linear quadratic model does not apply for low doses per fraction in human skin or that erythema is not exclusively initiated by radiation damage to the basal layer. The data are potentially explained by an induced repair model

Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

International Nuclear Information System (INIS)

Lucero, J. F.; Rojas, J. I.

2016-01-01

Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient’s entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

Clinical implementation of total skin electron irradiation treatment with a 6 MeV electron beam in high-dose total skin electron mode

Energy Technology Data Exchange (ETDEWEB)

Lucero, J. F., E-mail: fernando.lucero@hoperadiotherapy.com.gt [Universidad Nacional de Costa Rica, Heredia (Costa Rica); Hope International, Guatemala (Guatemala); Rojas, J. I., E-mail: isaac.rojas@siglo21.cr [Centro Médico Radioterapia Siglo XXI, San José (Costa Rica)

2016-07-07

Total skin electron irradiation (TSEI) is a special treatment technique offered by modern radiation oncology facilities, given for the treatment of mycosis fungoides, a rare skin disease, which is type of cutaneous T-cell lymphoma [1]. During treatment the patient’s entire skin is irradiated with a uniform dose. The aim of this work is to present implementation of total skin electron irradiation treatment using IAEA TRS-398 code of practice for absolute dosimetry and taking advantage of the use of radiochromic films.

SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms

Energy Technology Data Exchange (ETDEWEB)

Liu, Q [Institute of Radiation Medicine Fudan University, Shanghai (China); Shanghai General Hospital, Shanghai, Shanghai (China); Zhuo, W; Liu, H [Institute of Radiation Medicine Fudan University, Shanghai (China); Liu, Y; Chen, T [Shanghai General Hospital, Shanghai, Shanghai (China)

2016-06-15

Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominal antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients of stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)

SU-D-209-06: Study On the Dose Conversion Coefficients in Pediatric Radiography with the Development of Children Voxel Phantoms

International Nuclear Information System (INIS)

Liu, Q; Zhuo, W; Liu, H; Liu, Y; Chen, T

2016-01-01

Purpose: Conversion coefficients of organ dose normalized to entrance skin dose (ESD) are widely used to evaluate the organ doses directly using ESD without time-consuming dose measurement, this work aims to investigate the dose conversion coefficients in pediatric chest and abdomen radiography with the development of 5 years and 10 years old children voxel phantoms. Methods: After segmentation of organs and tissues from CT slice images of ATOM tissue-equivalent phantoms, a 5-year-old and a 10-year-old children computational voxel phantoms were developed for Monte Carlo simulation. The organ doses and the entrance skin dose for pediatric chest postero-anterior projection and abdominal antero-posterior projection were simulated at the same time, and then the organ dose conversion coefficients were calculated.To verify the simulated results, dose measurement was carried out with ATOM tissue-equivalent phantoms for 5 year chest radiography. Results: Simulated results and experimental results matched very well with each other, the result differences of all the organs covered in radiation field were below 16% for 5-year-old child in chest projection. I showed that the conversion coefficients of organs covered in the radiation field were much larger than organs out of the field for all the study cases, for example, the conversion coefficients of stomach, liver intestines, and pancreas are larger for abdomen radiography while conversion coefficients of lungs are larger for chest radiography. Conclusion: The voxel children phantoms were helpful to evaluate the radiation doses more accurately and efficiently. Radiation field was the essential factor that affects the organ dose, use reasonably small field should be encouraged for radiation protection. This work was supported by the National Natural Science Foundation of China(11475047)

The effect of low dose ionizing radiation on homeostasis and functional integrity in an organotypic human skin model

Energy Technology Data Exchange (ETDEWEB)

Neubeck, Claere von [German Cancer Consortium DKTK partner site Dresden, OncoRay - National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Fetscherstrasse 74, 01307 Dresden (Germany); German Cancer Research Center (DKFZ), Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Geniza, Matthew J. [Molecular and Cellular Biology Program, Oregon State University, Corvallis OR 97331 (United States); Kauer, Paula M.; Robinson, R. Joe; Chrisler, William B. [Health Impacts and Exposure Science, Pacific Northwest National Laboratory, Richland WA 99352 (United States); Sowa, Marianne B., E-mail: marianne.sowa@pnnl.gov [Health Impacts and Exposure Science, Pacific Northwest National Laboratory, Richland WA 99352 (United States)

2015-05-15

Highlights: • Low doses of high LET radiation influence skin homeostasis. • Effects on proliferation and differentiation profiles are LET dependent. • Skin barrier function is not compromised following low dose exposure. - Abstract: Outside the protection of Earth's atmosphere, astronauts are exposed to low doses of high linear energy transfer (LET) radiation. Future NASA plans for deep space missions or a permanent settlement on the moon are limited by the health risks associated with space radiation exposures. There is a paucity of direct epidemiological data for low dose exposures to space radiation-relevant high LET ions. Health risk models are used to estimate the risk for such exposures, though these models are based on high dose experiments. There is increasing evidence, however, that low and high dose exposures result in different signaling events at the molecular level, and may involve different response mechanisms. Further, despite their low abundance, high LET particles have been identified as the major contributor to health risk during manned space flight. The human skin is exposed in every external radiation scenario, making it an ideal epithelial tissue model in which to study radiation induced effects. Here, we exposed an in vitro three dimensional (3-D) human organotypic skin tissue model to low doses of high LET oxygen (O), silicon (Si) and iron (Fe) ions. We measured proliferation and differentiation profiles in the skin tissue and examined the integrity of the skin's barrier function. We discuss the role of secondary particles in changing the proportion of cells receiving a radiation dose, emphasizing the possible impact on radiation-induced health issues in astronauts.

Measurement of entrance surface dose on an anthropomorphic thorax phantom using a miniature fiber-optic dosimeter.

Science.gov (United States)

Yoo, Wook Jae; Shin, Sang Hun; Jeon, Dayeong; Hong, Seunghan; Sim, Hyeok In; Kim, Seon Geun; Jang, Kyoung Won; Cho, Seunghyun; Youn, Won Sik; Lee, Bongsoo

2014-04-01

A miniature fiber-optic dosimeter (FOD) system was fabricated using a plastic scintillating fiber, a plastic optical fiber, and a multi-pixel photon counter to measure real-time entrance surface dose (ESD) during radiation diagnosis. Under varying exposure parameters of a digital radiography (DR) system, we measured the scintillating light related to the ESD using the sensing probe of the FOD, which was placed at the center of the beam field on an anthropomorphic thorax phantom. Also, we obtained DR images using a flat panel detector of the DR system to evaluate the effects of the dosimeter on image artifacts during posteroanterior (PA) chest radiography. From the experimental results, the scintillation output signals of the FOD were similar to the ESDs including backscatter simultaneously obtained using a semiconductor dosimeter. We demonstrated that the proposed miniature FOD can be used to measure real-time ESDs with minimization of DR image artifacts in the X-ray energy range of diagnostic radiology.

Measurement of Entrance Surface Dose on an Anthropomorphic Thorax Phantom Using a Miniature Fiber-Optic Dosimeter

Directory of Open Access Journals (Sweden)

Wook Jae Yoo

2014-04-01

Full Text Available A miniature fiber-optic dosimeter (FOD system was fabricated using a plastic scintillating fiber, a plastic optical fiber, and a multi-pixel photon counter to measure real-time entrance surface dose (ESD during radiation diagnosis. Under varying exposure parameters of a digital radiography (DR system, we measured the scintillating light related to the ESD using the sensing probe of the FOD, which was placed at the center of the beam field on an anthropomorphic thorax phantom. Also, we obtained DR images using a flat panel detector of the DR system to evaluate the effects of the dosimeter on image artifacts during posteroanterior (PA chest radiography. From the experimental results, the scintillation output signals of the FOD were similar to the ESDs including backscatter simultaneously obtained using a semiconductor dosimeter. We demonstrated that the proposed miniature FOD can be used to measure real-time ESDs with minimization of DR image artifacts in the X-ray energy range of diagnostic radiology.

Patient dose in neonatal units

International Nuclear Information System (INIS)

Smans, K.; Struelens, L.; Smet, M.; Bosmans, H.; Vanhavere, F.

2008-01-01

Lung disease represents one of the most life-threatening conditions in prematurely born children. In the evaluation of the neonatal chest, the primary and most important diagnostic study is therefore the chest radiograph. Since prematurely born children are very sensitive to radiation, those radiographs may lead to a significant radiation detriment. Hence, knowledge of the patient dose is necessary to justify the exposures. A study to assess the patient doses was started at the neonatal intensive care unit (NICU) of the Univ. Hospital in Leuven. Between September 2004 and September 2005, prematurely born babies underwent on average 10 X-ray examinations in the NICU. In this sample, the maximum was 78 X-ray examinations. For chest radiographs, the median entrance skin dose was 34 μGy and the median dose area product was 7.1 mGy.cm 2 . By means of conversion coefficients, the measured values were converted to organ doses. Organ doses were calculated for three different weight classes: extremely low birth weight infants ( 2500 g). The doses to the lungs for a single chest radiograph for infants with extremely low birth weights, low birth weights and normal birth weights were 24, 25 and 32 μGy, respectively. (authors)

Science for common entrance physics : answers

CERN Document Server

Pickering, W R

2015-01-01

This book contains answers to all exercises featured in the accompanying textbook Science for Common Entrance: Physics , which covers every Level 1 and 2 topic in the ISEB 13+ Physics Common Entrance exam syllabus. - Clean, clear layout for easy marking. - Includes examples of high-scoring answers with diagrams and workings. - Suitable for ISEB 13+ Mathematics Common Entrance exams taken from Autumn 2017 onwards. Also available to purchase from the Galore Park website www.galorepark.co.uk :. - Science for Common Entrance: Physics. - Science for Common Entrance: Biology. - Science for Common En

Calculational methods for estimating skin dose from electrons in Co-60 gamma-ray beams

International Nuclear Information System (INIS)

Higgins, P.D.; Sibata, C.H.; Attix, F.H.; Paliwal, B.R.

1983-01-01

Several methods have been employed to calculate the relative contribution to skin dose due to scattered electrons in Co-60 gamma-ray beams. Either the Klein-Nishina differential scattering probability is employed to determine the number and initial energy of electrons scattered into the direction of a detector, or a Gaussian approximation is used to specify the surface distribution of initial pencil electron beams created by parallel or diverging photon fields. Results of these calculations are compared with experimental data. In addition, that fraction of relative surface dose resulting from photon interactions in air alone is estimated and compared with data extrapolated from measurements at large source-surface distance (SSD). The contribution to surface dose from electrons generated in air is 50% or more of the total skin dose for SSDs greater than 80 cm

Calculational methods for estimating skin dose from electrons in Co-60 gamma-ray beams

International Nuclear Information System (INIS)

Higgins, P.D.; Sibata, C.H.; Attix, F.H.; Paliwal, B.R.

1983-01-01

Several methods have been employed to calculate the relative contribution to skin dose due to scattered electrons in Co-60 γ-ray beams. Either the Klein--Nishina differential scattering probability is employed to determine the number and initial energy of electrons scattered into the direction of a detector, or a Gaussian approximation is used to specify the surface distribution of initial pencil electron beams created by parallel or diverging photon fields. Results of these calculations are compared with experimental data. In addition, that fraction of relative surface dose resulting from photon interactions in air alone is estimated and compared with data extrapolated from measurements at large source--surface distance (SSD). The contribution to surface dose from electrons generated in air is 50% or more of the total skin dose for SSDs greater than 80 cm

Sensitivity of coefficients for converting entrance surface dose and kerma-area product to effective dose and energy imparted to the patient

International Nuclear Information System (INIS)

Wise, K.N.; Sandborg, M.; Persliden, J.; Alm Carlsson, G.

1999-01-01

We investigate the sensitivity of the conversions from entrance surface dose (ESD) or kerma-area product (KAP) to effective dose (E) or to energy imparted to the patient (ε) to the likely variations in tube potential, field size, patient size and sex which occur in clinical work. As part of a factorial design study for chest and lumbar spine examinations, the tube potentials were varied to be ±10% of the typical values for the examinations while field sizes and the positions of the field centres were varied to be representative of values drawn from measurements on patient images. Variation over sex and patient size was based on anthropomorphic phantoms representing males and females of ages 15 years (small adult) and 21 years (reference adult). All the conversion coefficients were estimated using a mathematical phantom programmed with the Monte Carlo code EGS4 for all factor combinations and analysed statistically to derive factor effects. In general, the factors studied behaved independently in the sense that interaction of the physical factors generally gave no more than a 5% variation in a conversion coefficient. Taken together, variation of patient size, sex, field size and field position can lead to significant variation of E/KAP by up to a factor of 2, of E/ESD by up to a factor of 3, of ε/KAP by a factor of 1.3 and of ε/ESD by up to a factor of 2. While KAP is preferred to determine ε, the results show no strong preference of KAP over ESD in determining E. The mean absorbed dose D-bar in the patient obtained by dividing ε (determined using KAP) by the patient's mass was found to be the most robust measure of E. (author)

The Effects of Low Dose Irradiation on Inflammatory Response Proteins in a 3D Reconstituted Human Skin Tissue Model

Energy Technology Data Exchange (ETDEWEB)

Varnum, Susan M.; Springer, David L.; Chaffee, Mary E.; Lien, Katie A.; Webb-Robertson, Bobbie-Jo M.; Waters, Katrina M.; Sacksteder, Colette A.

2012-12-01

Skin responses to moderate and high doses of ionizing radiation include the induction of DNA repair, apoptosis, and stress response pathways. Additionally, numerous studies indicate that radiation exposure leads to inflammatory responses in skin cells and tissue. However, the inflammatory response of skin tissue to low dose radiation (<10 cGy) is poorly understood. In order to address this, we have utilized a reconstituted human skin tissue model (MatTek EpiDerm FT) and assessed changes in 23 cytokines twenty-four and forty eight hours following treatment of skin with either 3 or 10 cGy low-dose of radiation. Three cytokines, IFN-γ, IL-2, MIP-1α, were significantly altered in response to low dose radiation. In contrast, seven cytokines were significantly altered in response to a high radiation dose of 200 cGy (IL-2, IL-10, IL-13, IFN-γ, MIP-1α, TNF α, and VEGF) or the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (G-CSF, GM-CSF, IL-1α, IL-8, MIP-1α, MIP-1β, RANTES). Additionally, radiation induced inflammation appears to have a distinct cytokine response relative to the non-radiation induced stressor, TPA. Overall, these results indicate that there are subtle changes in the inflammatory protein levels following exposure to low dose radiation and this response is a sub-set of what is seen following a high dose in a human skin tissue model.

Skin dosimetry - radiological protection aspects of skin dosimetry

International Nuclear Information System (INIS)

Dennis, J.A.

1991-01-01

Following a Workshop in Skin Dosimetry, a summary of the radiological protection aspects is given. Aspects discussed include routine skin monitoring and dose limits, the need for careful skin dosimetry in high accidental exposures, techniques for assessing skin dose at all relevant depths and the specification of dose quantities to be measured by personal dosemeters and the appropriate methods to be used in their calibration. (UK)

Effects of low or high doses of short wavelength ultraviolet light (UVB) on Langerhans cells and skin allograft survival

International Nuclear Information System (INIS)

Odling, K.A.; Halliday, G.M.; Muller, H.K.

1987-01-01

Donor C57BL mouse shaved dorsal trunk or tail skin was exposed to high (200 mJ/cm 2 ) or low (40 mJ/cm 2 ) doses of short wavelength ultraviolet light (UVB) before grafting on to the thorax of BALB/c mouse recipients of the same sex. Skin grafted 1-14 days following a single high dose of UVB irradiation was ultrastructurally depleted of LC and survived significantly longer than unirradiated skin before being rejected. After a 21-day interval between exposure and grafting when LC were again present in the epidermis there was no significant difference between treated and control graft survival. Exposure to low dose UVB irradiation only significantly increased graft survival for skin transplanted 1-3 days after irradiation; skin grafted 4 days following irradiation survived for a similar period to unirradiated control skin grafts. Electronmicroscopy showed that the low UVB dose did not deplete LC from the epidermis. We conclude that after low dose UVB treatment the class II MHC antigens on the LC Plasma membrane were lost temporarily, thus prolonging graft survival, but when the plasma membrane antigens were re-expressed graft survival returned to normal. In contrast, high-dose UVB irradiation prolonged graft survival by depleting LC from the epidermis, with graft survival only returning to control values as LC repopulated the epidermis

Evaluation of F/E·DOI method as an approximate estimate of skin dose during percutaneous coronary intervention procedure

International Nuclear Information System (INIS)

Nakahara, Makoto; Yoshino, Akira; Kitano, K.; Yamaguchi, M.; Morone, Takayuki; Tani, K.

2005-01-01

The purpose of this study was to evaluate the efficacy of fluoroscopy time/total exposure times exposure times · in direction of interest (F/E·DOI) method as an approximate estimate of skin dose during percutaneous coronary intervention (PCI) procedure. Up to March 10, 2004, fifty-seven patients (male: 46 cases, female: 11 cases, age range 38-85 years; mean age 67±11 years) had undergone PCI and 157 directions of exposure was measured using X-ray films (KONICA MINOLTA SR-DUP) placed under the back of each patient during the procedure. The fluoroscopy time (minutes), the times of exposure in each direction during the procedure, and the thickness of chest (cm) was recorded. The relation of the skin dose to fluoroscopic time, exposure times in direction of interest, and F/E·DOI was assessed. The relationship between fluoroscopy time and skin dose was shown as y=0.02x+0.22 (r=0.54, p<0.0001, m.e=0.00±0.71 Gy, e.a=-2.19∼l.53 Gy). In addition, the relation of skin dose to exposure times in the direction of interest was y=0.07x+0.27 (r=0.77, p<0.0001, m.e=-0.00±0.53 Gy, e.a=-2.45∼1.76 Gy). The relationship between skin dose and F/E·DOI was y=0.06x+0.30 (r=0.85, p<0.0001, m.e=-0.00±0.44 Gy, e.a=-1.28∼1.06 Gy). Moreover, the relationship between skin dose and (F/E·DOI x 0.06+0.30) x coefficient of direction x coefficient in thickness of chest was y=0.99x-0.02 (r=0.89, p<0.0001, m.e=0.00±0.38 Gy, e.a=-1.12∼l.27 Gy). The calculated results corresponded to the skin dose during the procedure. F/E·DOI method was simple and effective, moreover, that enabled us to inform the skin dose during the PCI procedure to the interventionalist easily. (authors)

Accelerated partial-breast irradiation with interstitial implants. The clinical relevance of the calculation of skin doses

International Nuclear Information System (INIS)

Ott, O.J.; Lotter, M.; Sauer, R.; Strnad, V.

2007-01-01

Purpose: To describe relative skin dose estimations and their impact on cosmetic outcome in interstitial multicatheter accelerated partial-breast irradiation (APBI). Patients and Methods: Between April 2001 and January 2005, 105 consecutive patients with early breast cancer were recruited in Erlangen, Germany, for this substudy of the German-Austrian APBI phase II trial. 51% (54/105) received pulsed-dose-rate (PDR), and 49% (51/105) high-dose-rate (HDR) brachytherapy. Prescribed reference dose for HDR brachytherapy was 32 Gy in eight fractions of 4 Gy, twice daily. Prescribed reference dose in PDR brachytherapy was 49.8 Gy in 83 consecutive fractions of 0.6 Gy every hour. Total treatment time was 3-4 days. With a wire cross on the skin surface during the brachytherapy-planning procedure the minimal, mean and maximal relative skin doses (SD min% , SD max% , SD mean% ) were recorded. Endpoint of this evaluation was the cosmetic outcome in relation to the relative skin doses. Results: Median follow-up time was 38 months (range, 19-65 months). Cosmetic results for all patients were excellent in 57% (60/105), good in 36% (38/105), and fair in 7% (7/105). The SD min% (27.0% vs. 31.7%; p = 0.032), SD mean% (34.2% vs. 38.1%; p 0.008), and SD max% (38.2% vs. 46.4%; p 0.003) were significantly lower for patients with excellent cosmetic outcome compared to patients with a suboptimal outcome. SD mean% (37.6% vs. 34.2%; p = 0.026) and SD max% (45.4% vs. 38.2%; p = 0.008) were significantly higher for patients with good cosmetic outcome compared with the patients with excellent results. Conclusion: The appraisal of skin doses has been shown to be relevant to the achievement of excellent cosmetic outcome. Further investigations are necessary, especially on the basis of CT-based brachytherapy planning, to further improve the treatment results of multicatheter APBI. (orig.)

Evaluating the maximum patient radiation dose in cardiac interventional procedures

International Nuclear Information System (INIS)

Kato, M.; Chida, K.; Sato, T.; Oosaka, H.; Tosa, T.; Kadowaki, K.

2011-01-01

Many of the X-ray systems that are used for cardiac interventional radiology provide no way to evaluate the patient maximum skin dose (MSD). The authors report a new method for evaluating the MSD by using the cumulative patient entrance skin dose (ESD), which includes a back-scatter factor and the number of cine-angiography frames during percutaneous coronary intervention (PCI). Four hundred consecutive PCI patients (315 men and 85 women) were studied. The correlation between the cumulative ESD and number of cine-angiography frames was investigated. The irradiation and overlapping fields were verified using dose-mapping software. A good correlation was found between the cumulative ESD and the number of cine-angiography frames. The MSD could be estimated using the proportion of cine-angiography frames used for the main angle of view relative to the total number of cine-angiography frames and multiplying this by the cumulative ESD. The average MSD (3.0±1.9 Gy) was lower than the average cumulative ESD (4.6±2.6 Gy). This method is an easy way to estimate the MSD during PCI. (authors)

Trends and the determination of effective doses for standard X-ray procedures

International Nuclear Information System (INIS)

Johnson, H.M.; Neduzak, C.; Gallet, J.; Sandeman, J.

2001-01-01

Trends in the entrance skin exposures (air kerma) for standard x-ray imaging procedures are reported for the Province of Manitoba, Canada. Average annual data per procedure using standard phantoms and standard ion chambers have been recorded since 1981. For example, chest air kerma (backscatter included) has decreased from 0.14 to 0.09 mGy. Confounding factors may negate the gains unless facility quality control programs are maintained. The data were obtained for a quality assurance and regulatory compliance program. Quoting such data for risk evaluation purposes lacks rigor hence a compartment model for organ apportioning, using organ absorbed doses and weighting factors, has been applied to determine effective dose per procedure. The effective doses for the standard procedures are presented, including the value of 0.027 mSv (1999) calculated for the effective dose in PA chest imaging. (author)

SU-F-P-47: Estimation of Skin Dose by Performing the Measurements On Cylindrical Phantom

Energy Technology Data Exchange (ETDEWEB)

Bosma, S; Sanders, M; Aryal, P [University Kentucky - Chandler Medical Ctr, Lexington, KY (United States)

2016-06-15

Purpose: To evaluate the skin dose by performing the measurements on cylindrical phantom with 6X beam. Methods: A cylindrical phantom was used to best model a patient surface. The source to surface distance (SSD) was 100 cm at phantom surface along central axis (CAX). The EBT2 films were cut into 2×2 cm2 pieces. Each piece of film was placed at CAX on phantom surface for each measurement at 0°, 15°, 30°, 45°, 60°, 75°, and 90° gantry angles for field sizes of 5×5, 10×10, 15×15, and 20×20 cm{sup 2} respectively. One hundred monitor units (MU) with 6X beam were delivered for each set up. Similarly, the measurements were repeated using lithium fluoride (LiF) thermoluminescent dosimeter (TLD) chips (1X1X1 mm{sup 3}). Two TLD chips were placed for each gantry angle and field size. The calibration curves were produced for both film and TLD. The computed tomography (CT) was also performed on the same cylindrical phantom and dose was evaluated at the phantom surface using Eclipse treatment planning system ( AAA algorithm) for skin dose comparison. Results: Data showed small differences at smaller angles among EBT2, TLD and Eclipse treatment planning system. But Eclipse treatment planning system under estimated the skin dose between 20% and 50% at larger gantry angles (between 40° and 80°) at all field sizes before dose differences began to converge. Conclusion: Given this data, we can conclude that Eclipse treatment planning system under estimated the dose especially between 40 and 80 degrees of obliquity compared to the measurements results. Ideally, this study can be applied largely to head and neck patients where contours differ drastically and where skin dose is paramount.

Pediatric patient doses in interventional cardiology procedures

International Nuclear Information System (INIS)

Medeiros, R.B.; Murata, C.H.; Moreira, A.C.

2014-01-01

The radiation doses from interventional procedures is relevant when treating children because of their greater radiosensitivity compared with adults. The purposes of this paper were to estimate the dose received by 18 pediatric patients who underwent cardiac interventional procedures and to correlate the maximum entrance surface air kerma (Ke,max), estimated with radiochromic films, with the cumulative air kerma values displayed at the end of procedures. This study was performed in children up to 6 years. The study was performed in two hospitals, one located in Recife and the other one in São Paulo. The x-ray imaging systems used were Phillips Allura 12 model with image intensifier system and a Phillips Allura FD10 flat panel system. To estimate the Ke,max on the patient’s skin radiochromic films(Gafchromic XR-RV2) were used. These values were estimated from the maximum optical density measured on film using a calibration curve. The results showed cumulative air kerma values ranging from 78.3- 500.0mGy, with a mean value of 242,3 mGy. The resulting Ke,max values ranged from 20.0-461.8 mGy, with a mean value of 208,8 mGy. The Ke,max values were correlated with the displayed cumulative air kerma values. The correlation factor R² was 0.78, meaning that the value displayed in the equipment’s console can be useful for monitoring the skin absorbed dose throughout the procedure. The routine fluoroscopy time records is not able by itself alert the physician about the risk of dose exceeding the threshold of adverse reactions, which can vary from an early erythema to serious harmful skin damage. (author)

Characterization of differences in calculated and actual measured skin doses to canine limbs during stereotactic radiosurgery using Gafchromic film

Energy Technology Data Exchange (ETDEWEB)

Walters, Jerri [Duke Energy, York, SC (United States); Colorado State University, Fort Collins, CO (United States); Ryan, Stewart [Animal Cancer Center, Colorado State University, Fort Collins, CO (United States); Harmon, Joseph F., E-mail: joseph_harmon@bshsi.org [Bon Secours Cancer Institute, Henrico, VA (United States)

2012-07-01

Accurate calculation of absorbed dose to the skin, especially the superficial and radiosensitive basal cell layer, is difficult for many reasons including, but not limited to, the build-up effect of megavoltage photons, tangential beam effects, mixed energy scatter from support devices, and dose interpolation caused by a finite resolution calculation matrix. Stereotactic body radiotherapy (SBRT) has been developed as an alternative limb salvage treatment option at Colorado State University Veterinary Teaching Hospital for dogs with extremity bone tumors. Optimal dose delivery to the tumor during SBRT treatment can be limited by uncertainty in skin dose calculation. The aim of this study was to characterize the difference between measured and calculated radiation dose by the Varian Eclipse (Varian Medical Systems, Palo Alto, CA) AAA treatment planning algorithm (for 1-mm, 2-mm, and 5-mm calculation voxel dimensions) as a function of distance from the skin surface. The study used Gafchromic EBT film (International Specialty Products, Wayne, NJ), FilmQA analysis software, a limb phantom constructed from plastic water Trade-Mark-Sign (fluke Biomedical, Everett, WA) and a canine cadaver forelimb. The limb phantom was exposed to 6-MV treatments consisting of a single-beam, a pair of parallel opposed beams, and a 7-beam coplanar treatment plan. The canine forelimb was exposed to the 7-beam coplanar plan. Radiation dose to the forelimb skin at the surface and at depths of 1.65 mm and 1.35 mm below the skin surface were also measured with the Gafchromic film. The calculation algorithm estimated the dose well at depths beyond buildup for all calculation voxel sizes. The calculation algorithm underestimated the dose in portions of the buildup region of tissue for all comparisons, with the most significant differences observed in the 5-mm calculation voxel and the least difference in the 1-mm voxel. Results indicate a significant difference between measured and calculated data

The dose penumbra of a custom-made shield used in hemibody skin electron irradiation.

Science.gov (United States)

Rivers, Charlotte I; AlDahlawi, Ismail; Wang, Iris Z; Singh, Anurag K; Podgorsak, Matthew B

2016-11-08

We report our technique for hemibody skin electron irradiation with a custom-made plywood shield. The technique is similar to our clinical total skin electron irradiation (TSEI), performed with a six-pair dual field (Stanford technique) at an extended source-to-skin distance (SSD) of 377 cm, with the addition of a plywood shield placed at 50 cm from the patient. The shield is made of three layers of stan-dard 5/8'' thick plywood (total thickness of 4.75 cm) that are clamped securely on an adjustable-height stand. Gafchromic EBT3 films were used in assessing the shield's transmission factor and the extent of the dose penumbra region for two different shield-phantom gaps. The shield transmission factor was found to be about 10%. The width of the penumbra (80%-to-20% dose falloff) was measured to be 12 cm for a 50 cm shield-phantom gap, and reduced slightly to 10 cm for a 35 cm shield-phantom gap. In vivo dosimetry of a real case confirmed the expected shielded area dose. © 2016 The Authors.

Improvement of the equivalent sphere model for better estimates of skin or eye dose in space radiation environments

International Nuclear Information System (INIS)

Lin, Z.W.

2011-01-01

It is often useful to get a quick estimate of the dose or dose equivalent of an organ, such as blood-forming organs, the eye or the skin, in a radiation field. Sometimes an equivalent sphere is used to represent the organ for this purpose. For space radiation environments, recently it has been shown that the equivalent sphere model does not work for the eye or the skin in solar particle event environments. In this study, we improve the representation of the eye and the skin using a two-component equivalent sphere model. Motivated by the two-peak structure of the body organ shielding distribution for the eye and the skin, we use an equivalent sphere with two radius parameters, for example a partial spherical shell of a smaller thickness over a proper fraction of the full solid angle combined with a concentric partial spherical shell of a larger thickness over the rest of the full solid angle, to represent the eye or the skin. We find that using an equivalent sphere with two radius parameters instead of one drastically improves the accuracy of the estimates of dose and dose equivalent in space radiation environments. For example, in solar particle event environments the average error in the estimate of the skin dose equivalent using an equivalent sphere with two radius parameters is about 8%, while the average error of the conventional equivalent sphere model using one radius parameter is around 100%.

SU-G-201-14: Is Maximum Skin Dose a Reliable Metric for Accelerated Partial Breast Irradiation with Brachytherapy?

International Nuclear Information System (INIS)

Park, S; Ragab, O; Patel, S; Demanes, J; Kamrava, M; Kim, Y

2016-01-01

Purpose: To evaluate the reliability of the maximum point dose (Dmax) to the skin surface as a dosimetric constraint, we investigated the correlation between Dmax at the skin surface and dose metrics at various definitions of skin thickness. Methods: 42 patients treated with APBI using a Strut Adjusted Volume Implant (SAVI) applicator between 2010 and 2014 were retrospectively reviewed. Target (PTV-EVAL) and organs at risk (OARs: skin, lung, and ribs) were delineated on a CT following NSABP B-39 guidelines. Six skin structures were contoured: a rind 3cm external to the body surface and 1, 2, 3, 4, and 5mm thick rinds deep to the body surface. Inverse planning simulated annealing optimization was used to deliver 32–34Gy in 8-10 fractions to the target while minimizing OAR doses. Dmax, D0.1cc, D1.0cc, and D2.0cc to the various skin structures were calculated. Linear regressions between the metrics were evaluated using the coefficient of determination (R"2). Results: The average±SD PTV-EVAL volume and cavity-to-skin distances were 71.1±28.5cc and 6.9±5.0mm. The target V90 and V95 were 97.3±2.3% and 95.1±3.2%. The Dmax to the skin structures were 78.7±10.2% (skin surface), 82.2±10.7% (skin-1mm), 89.4±12.6% (skin-2mm), 97.9±15.4% (skin-3mm), 114.1±32.5% (skin-4mm), and 157.0±85.3% (skin-5mm). Linear regression analysis showed D1.0cc and D2.0cc to the skin 1mm and Dmax to the skin-4mm and 5mm were poorly correlated with other metrics (R"2=0.413±0.204). Dmax to the skin surface was well correlated (R"2=0.910±0.047) and D1.0cc to the skin-3mm was strongly correlated with all subsurface skin layers (R"2=0.935±0.050). Conclusion: Dmax to the skin surface is a relevant metric for breast skin dose. Contouring discontinuities in the skin with a 1mm subsurface rind and the active dwells in the skin 4 and 5mm introduced significant variations in skin DVH. D0.1cc, D1.0cc, and D2.0cc to a 3mm skin rind are more robust metrics in breast brachytherapy.

Immediate hypersensitivity to iodinated contrast media: diagnostic accuracy of skin tests and intravenous provocation test with low dose.

Science.gov (United States)

Sesé, L; Gaouar, H; Autegarden, J-E; Alari, A; Amsler, E; Vial-Dupuy, A; Pecquet, C; Francès, C; Soria, A

2016-03-01

The diagnosis of HSR to iodinated contrast media (ICM) is challenging based on clinical history and skin tests. This study evaluates the negative predictive value (NPV) of skin tests and intravenous provocation test (IPT) with low-dose ICM in patients with suspected immediate hypersensitivity reaction (HSR) to ICM. Thirty-seven patients with suspected immediate hypersensitivity reaction to ICM were included retrospectively. Skin tests and a single-blind placebo-controlled intravenous provocation test (IPT) with low-dose iodinated contrast media (ICM) were performed. Skin tests with ICM were positive in five cases (one skin prick test and five intradermal test). Thirty-six patients were challenged successfully by IPT, and only one patient had a positive challenge result, with a grade I reaction by the Ring and Messmer classification. Ten of 23 patients followed up by telephone were re-exposed to a negative tested ICM during radiologic examination; two experienced a grade I immediate reaction. For immediate hypersensitivity reaction to ICM, the NPV for skin tests and IPT with low dose was 80% (95% CI 44-97%). © 2016 John Wiley & Sons Ltd.

Assessment of peak skin dose in interventional cardiology: A comparison between Gafchromic film and dosimetric software em.dose.

Science.gov (United States)

Greffier, J; Van Ngoc Ty, C; Bonniaud, G; Moliner, G; Ledermann, B; Schmutz, L; Cornillet, L; Cayla, G; Beregi, J P; Pereira, F

2017-06-01

To compare the use of a dose mapping software to Gafchromic film measurement for a simplified peak skin dose (PSD) estimation in interventional cardiology procedure. The study was conducted on a total of 40 cardiac procedures (20 complex coronary angioplasty of chronic total occlusion (CTO) and 20 coronary angiography and coronary angioplasty (CA-PTCA)) conducted between January 2014 to December 2015. PSD measurement (PSD Film ) was obtained by placing XR-RV3 Gafchromic under the patient's back for each procedure. PSD (PSD em.dose ) was computed with the software em.dose©. The calculation was performed on the dose metrics collected from the private dose report of each procedure. Two calculation methods (method A: fluoroscopic kerma equally spread on cine acquisition and B: fluoroscopic kerma is added to one air Kerma cine acquisition that contributes to the PSD) were used to calculate the fluoroscopic dose contribution as fluoroscopic data were not recorded in our interventional room. Statistical analyses were carried out to compare PSD Film and PSD em.dose . The PSD Film median (1st quartile; 3rd quartile) was 0.251(0.190;0.336)Gy for CA-PTCA and 1.453(0.767;2.011)Gy for CTO. For method-A, the PSD em.dose was 0.248(0.182;0.369)Gy for CA-PTCA and 1.601(0.892;2.178)Gy for CTO, and 0.267(0.223;0.446)Gy and 1.75 (0.912;2.584)Gy for method-B, respectively. For the two methods, the correlation between PSD Film and PSD em.dose was strong. For all cardiology procedures investigated, the mean deviation between PSD Film and PSD em.dose was 3.4±21.1% for method-A and 17.3%±23.9% for method-B. The dose mapping software is convenient to calculate peak skin dose in interventional cardiology. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A model for predicting skin dose received by patients from an x-ray ...

African Journals Online (AJOL)

Patient dosimetry has raised concern on quality assurance in hospitals. Several organisations and research groups have been advocating ways of minimising radiation dose received by patients in hospitals. In this paper we have shown that it is possible to obtain in a simple way a reasonable estimate of skin dose received ...

Successfully Managing Impending Skin Necrosis following Hyaluronic Acid Filler Injection, using High-Dose Pulsed Hyaluronidase

Directory of Open Access Journals (Sweden)

Kwok Thye David Loh, MBBS

2018-02-01

Full Text Available Summary:. Facial fillers are becoming increasingly popular as aesthetic procedures to temporarily reduce the depth of wrinkles or to contour faces. However, even in the hands of very experienced injectors, there is always a small possibility of vascular complications like intra-arterial injection of filler substance. We present a case report of a patient who developed features of vascular obstruction in right infraorbital artery and tell-tale signs of impending skin necrosis, after hyaluronic acid filler injection by an experienced injector. The diagnosis of a vascular complication was made quickly with the help of clinical features like blanching, livedo reticularis, and poor capillary refill. Patient was treated promptly with “high-dose pulsed hyaluronidase protocol” comprising three 1,000-unit pulses of hyaluronidase, administered hourly. There was no further increase in size of the involved area after the first dose of hyaluronidase. All of the involved area, along with 1 cm overlapping in uninvolved skin area, was injected during each injection pulse, using a combination of cannula and needle. Complete reperfusion and good capillary filling were achieved after completion of 3 pulses, and these were taken as the end-point of high-dose pulsed hyaluronidase treatment. Immediate skin changes after filler injections, as well as after hyaluronidase injections and during the 3-week recovery period, were documented with photographs and clinical notes. Involved skin was found to have been fully recovered from this vascular episode, thus indicating that complete recovery of the ischemic skin changes secondary to possible intra-arterial injection could be achieved using high-dose pulsed hyaluronidase protocol.

What is the effect of different skin types on the required dose for photodynamic therapy?

CSIR Research Space (South Africa)

Karsten, AE

2008-11-01

Full Text Available For effective laser treatment it is very important to provide the correct dose at the required treatment depth. In South Africa we have a richness of ethnic groups contributing to a large variety in skin tones. Effective laser treatment of skin...

Split-dose recovery in epithelial and vascular-connective tissue of pig skin

International Nuclear Information System (INIS)

Peel, D.M.; Hopewell, J.W.; Simmonds, R.H.; Dodd, P.; Meistrich, M.L.

1984-01-01

In the first 16 weeks after irradiation, two distinct waves of reaction can be observed in pig skin; the first wave (3-9 weeks) represents the expression of damage to the epithelium while the second is indicative of primary damage to the dermis, mediated through vascular injury. Following β-irradiation with a strontium-90 applicator, a severe epithelial reaction was seen with little subsequent dermal effects. X-rays (250 kV) on the other hand, produced a minimal epithelial response at doses which led to the development of dermal necrosis after 10-16 weeks. Comparison of single doses with two equal doses separated by 24 h produced a D 2 -D 1 value of 7.0 Gy at the doses which produced moist desquamation in 50% of fields (ED 50 ) after strontium-90 irradiation. After X-irradiation comparison of ED 50 doses for the later dermal reaction suggested a D 2 -D 1 value of 4.5 Gy. Over this same dose range of X-rays the D 2 -D 1 value for the first wave epithelial reaction was 3.5 Gy. These values of D 2 -D 1 for epithelial and dermal reactions in pig skin were compared with published data and were examined in relation to the theoretical predictions of a linear quadratic model for tissue target cell survival. The results were broadly in keeping with the productions of such a model. (Auth.)

SU-F-T-509: Investigation into the Impact of the Linear Accelerator Treatment Table On Skin Dose to Prone Breast Patients

Energy Technology Data Exchange (ETDEWEB)

Pedersen, K; Irwin, J; Sansourekidou, P; Kriminski, S; Pavord, D [Health Quest, Poughkeepsie, NY (United States)

2016-06-15

Purpose: To investigate the impact of the treatment table on skin dose for prone breast patients for which the breast contacts the table and to develop a method to decrease skin dose. Methods: We used 12cm stack of 15cmx15cm solid water slabs to imitate breast. Calibrated EBT3 radiochromic film was affixed to the bottom of the phantom. Treatments for 32 patients were analyzed to determine typical prone breast beam parameters. Based on the analysis, a field size and a range of gantry angles were chosen for the test beams. Three experimental setups were used. The first represented the patient setup currently used in our clinics with the phantom directly on the table. The second was the skin sparing setup, with a 1.5cm Styrofoam slab between the phantom and the table. The third used a 7.5cm Styrofoam slab to examine the extent of skin sparing potential. The calibration curve was applied to each film to determine dose. Percent difference in dose between the current and skin sparing setups was calculated for each gantry angle and gantry angle pair. Results: Data showed that beams entering through the table showed a skin dose decrease ranging from 13%–30% with the addition of 7.5cm Styrofoam, while beams exiting through the table showed no significant difference. The addition of 1.5cm Styrofoam resulted in differences ranging from 0.5%–13% with the skin sparing setup. Conclusion: The results demonstrate that skin in contact with the table receives increased dose from beams entering through the table. By creating separation between the breast and the table with Styrofoam the skin dose can be lowered, but 1.5 cm did not fully mitigate the effect. Further investigation will be performed to identify a clinically practical thickness that maximizes this mitigation.

Measurement of dose to skin using TLD of several radiodiagnostic studies in San Jose, Costa Rica

International Nuclear Information System (INIS)

Mora, P.

1998-01-01

It is quantified the radiation doses on skin for several radiodiagnostic studies in patients of the Calderon Guardia Hospital in San Jose, Costa Rica at the period October 1997-September 1998 using thermoluminescent dosemeters TLD 100. The crystals receive the decoction standard procedures and they are arranged at the middle of the irradiation field. For a total of 973 radiodiagnostic studies it was found that the dose on skin in mGy are: 2.09 for thorax AP/AP, 5.33 for thorax LAT, 5.35 for skull AP/PA, 2.98 for skull LAT, 10.74 for abdomen, hips and pelvis, 6.20 for spines AP, 9.35 for spines LAT, 11.48 for lumbar columns AP, 29.99 for lumbar columns LAT and 6.87 for intravenous skin diagrams (first plate ap). It is produced thus the first reference bank for the national hospitals, which is compared with the orientation levels of doses for IAEA. Recommendations to diminish the collective doses through quality control programs are discussed, taking as goal to have got radiographs of excellent diagnostic quality, but with the less possible doses. (Author)

Valorization of the GAFCHROMIC XR-R film for radiation dose estimation in the skin

International Nuclear Information System (INIS)

Sanchez Garcia, M.; Otero Martinez, C.; Camino, X. M.; Sendon del Rio, J. R.; Luna Vega, V.; Lobato Busto, R.; Mosquera Sueiro, J.; Pombar Camean, M.

2006-01-01

The adequacy of the couple formed by the GAFCHROMIC XR-R film and the MICROTEK Scan Maker 8700 for skin dose determination has been evaluated. The main advantages are the ease of use the films, since it can be manipulated without special care and the ability to archive it in the dosimetric history of the patient. The main limiting factors coming from the scanner are the reproducibility over time and noise in the digitization; it is shown that this last component can be minimized at the cost of resolution. From the film itself, the limiting factors are the inter and intra film uniformity. Contributing an 6,5% to the overall uncertainty in dose determination. Overall, it has been shown that skin dose determination is possible with this film with an uncertainty below 10%. (Author)

Radiation doses measured by TLD (thermoluminescent dosimeter) in x-ray examination, especially on the skin area beneath of which female gonads situate

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, S; Hiraki, M; Murakami, S; Nishikawa, N; Yagi, T [Nissei Hospital, Osaka (Japan)

1977-03-01

By means of TLD, we measured the radiation doses to the skin in the central area of the field of radiation and doses scattered outside of the radiation field, utilizing a phantom to define a suitable radiation field. Clinically, when radiography of the gall bladder and the chest was done, we measured both the radiation doses of the central skin area where radiation was done and the skin above the area of the female gonads. In radiography of the chest, the radiation doses to the skin area above the female gonads situate was under 0.1 mR. When female gonads are less than 15 cm from the margin of the radiation field of the radiation dose can be decreased by 30% if gum sheets containing lead are used to cover the skin area outside the radiation field.

The physiological and phenotypic determinants of human tanning measured as change in skin colour following a single dose of ultraviolet B radiation.

Science.gov (United States)

Wong, Terence H; Jackson, Ian J; Rees, Jonathan L

2010-07-01

Experimental study of the in vivo kinetics of tanning in human skin has been limited by the difficulties in measuring changes in melanin pigmentation independent of the ultravioletinduced changes in erythema. The present study attempted to experimentally circumvent this issue. We have studied erythemal and tanning responses following a single exposure to a range of doses of ultraviolet B irradiation on the buttock and the lower back in 98 subjects. Erythema was assessed using reflectance techniques at 24 h and tanning measured as the L* spectrophotometric score at 7 days following noradrenaline iontophoresis. We show that dose (P skin colour (P skin colour (P = 0.0365) or, as an alternative to skin colour, skin type (P = 0.0193) predict tanning, with those with lighter skin tanning slightly more to a defined UVB dose. If erythema is factored into the regression, then only dose and body site remain significant predictors of tanning: therefore neither phototype nor pigmentary factors, such as baseline skin colour, or eye or hair colour, predict change in skin colour to a unit erythemal response.

Total skin high-dose-rate electron therapy dosimetry using TG-51

International Nuclear Information System (INIS)

Gossman, Michael S.; Sharma, Subhash C.

2004-01-01

An approach to dosimetry for total skin electron therapy (TSET) is discussed using the currently accepted TG-51 high-energy calibration protocol. The methodology incorporates water phantom data for absolute calibration and plastic phantom data for efficient reference dosimetry. The scheme is simplified to include the high-dose-rate mode conversion and provides support for its use, as it becomes more available on newer linear accelerators. Using a 6-field, modified Stanford technique, one may follow the process for accurate determination of absorbed dose

Estimation of deep, eye lens and skin doses for high energy electron beams for dosimetry and protection purpose

International Nuclear Information System (INIS)

Reena Kumari; Rakesh, R.B.

2018-01-01

In the radiological protection especially for individual as well as area monitoring, it is generally considered that beta sources deposit skin and eye lens doses only as they do not have enough energy for depositing doses at 10 mm depth. Also, the skin and eye lens doses differ substantially due to attenuation of beta particles at 0.07 mm (skin) and 3 mm (eye lens) depths and the surface doses are always greater than eye lens doses even for the highest energy beta source used in brachytherapy applications. However, worldwide increase in the use of high energy electron accelerators, new challenges are being posed for radiological protection and the operational quantities defined previously by ICRU are being reviewed. In view of these developments, studies have been performed for different electron beams in the energy range from (4 - 20) MeV generated using a medical linear accelerator. The aim of the study is to measure doses deposited at various depths as defined by ICRU 39 for individual and area monitoring purposes

The dependence of percentage depth dose on the source-to-skin ...

African Journals Online (AJOL)

The variation of percentage depth dose (PDD) with source-to-skin distance (SSD) for kilovoltage X-rays used in radiotherapy has been investigated. Based on physical parameters of photon fluence, absorption and scatter during interaction of radiation with tissue, a mathematical model was developed to predict the PDDs at ...

Assessment of eye, hand and male gonadal skin dose in radiotherapy

International Nuclear Information System (INIS)

Pushap, M.P.S.

1979-01-01

An attempt has been made to gauge the dose to (1) the eye, (2) the skin of the hands and (3) the gonads from radiotherapy of other parts of the body. The study has been done on actual male patients at the Jorjani Medical Centre, Tehran. The study, indicated high dose to the eye lid i.e. about 3% of the tumour dose in the case of head irradiation. The eyes and gonads lie at unequal distances from thorax, so are their doses. It is further emphasised that a minimum dose of 400 rad in three weeks to one month has been reported to be cataractogenic in man. A 50% incidence of progressive loss of vision with a dose of 750 rad to 1000 rad in three weeks to three months time has been observed. If appropriate techniques are not employed to shield the eye, even from stray radiation, such limits may easily be reached. (K.B.)

Normal tissue tolerance to external beam radiation therapy: Skin; Dose de tolerance des tissus sains: la peau et les phaneres

Energy Technology Data Exchange (ETDEWEB)

Ginot, A.; Doyen, J.; Hannoun-Levi, J.M.; Courdi, A. [Service d' oncologie-radiotherapie, centre Antoine-Lacassagne, 06 - Nice (France)

2010-07-15

Acute skin toxicity is frequent during radiation therapy and can lead to temporary arrest of the treatment. Chronic toxicity can occur and conduct to cosmetic problems. Alopecia is the most frequent toxicity concerning hair and is most of the time reversible. Several factors linked to patients influence skin toxicity, such as under-nutrition, old age, obesity, smoking, skin diseases, autoimmune diseases, failure of DNA reparation. Skin, hair and nail toxicities depend also on radiation schedule. Acute toxicity is greater when dose per fraction increases. Chronic and acute toxicities are more often when total dose increases. Under 45 Gy, the risk of severe skin toxicity is low, and begins above 50 Gy. Skin toxicity depends also on the duration of radiotherapy and split course schedules are associated with less toxicities. Irradiation surface seems to influence skin toxicity but interaction is more complex. Reirradiation is often feasible in case of cancer recurrence but with a risk of grade 3-4 toxicity above all in head and neck cancer. The benefit/risk ratio has to be always precisely evaluated. Permanent alopecia is correlated with the follicle dose. Modern techniques of radiation therapy allow to spare skin. (authors)

Evaluation of pediatrics entrance surface air kerma during chest X-ray examinations in some Khartoum hospitals

International Nuclear Information System (INIS)

Mohamed, Hassan Ishag Yahya

2015-10-01

The aim of this study was to determine the amount of entrance surface air kerma dose in air that can reflect the amount of the risk that the children, are subjected to. The parameters that are involved in this project are x-ray tube current (mA), exposure time (sec.), and focal skin distance (FSD) in cm. ESAK is calculated using the equation: ESAK=(Output (mGy/mAs) x (100/FSD) 2 X mAs) for different examination of different patients. 65 cases were involved in this study, the results show that the ESAK mean value (0.18±0.07) mGy, (0.06±0.07) mGy, (0.045±0.017) mGy and (0.049±0.013) mGy at the hospitals (IBNIOF Omdurman, police, clinic doctor) respectively. IBNIOF presented the highest ESAK (0.18±0.07) mGy, while it was lowest in police (0.045±0.017) mGy. The estimated ESAK value were within the established international reference dose values and also the values obtained in pervious studies however, variations were observed in ESAK values among hospitals under study which could be due to the differences in exposure parameters used. Also tube output has some effect on obtained ESAK. (author)

Clinical results of entrance dose in vivo dosimetry for high energy photons in external beam radiotherapy using MOSFETs

International Nuclear Information System (INIS)

Morton, J. P.; Bhat, M.; Williams, T.; Kovendy, A.

2007-01-01

Full text: Thomson and Nielsen T N -502 R D MOSFETs were used for entrance dose in vivo dosimetry for 6 and 10 MV photons. A total of 24 patients were tested, 10 breast. 8 prostate, 5 lung and 1 head and neck. For prostates three fields were checked. For all other plans all fields were checked. An action threshold of 8% was set for any one field and 5% for all fields combined. The total number of fields tested was 56, with a mean discrepancy of 1.4% and S.D. of 2.6%. Breasts had a mean discrepancy of 1.8% and S.D. of 2.8%. Prostates had a mean discrepancy of 1.3% and S.D. of 2.9%. For 3 fields combined, prostates had a mean of 1.3% and S.D. of 1.8%. These results are similar to results obtained with diodes and TLDs for the same techniques.

Dose measurements using thermoluminescent dosimeters and DoseCal software at two paediatric hospitals in Rio de Janeiro

International Nuclear Information System (INIS)

Mohamadain, K.E.M.; Azevedo, A.C.P.; Rosa, L.A.R. da; Guebel, M.R.N.; Boechat, M.C.B.

2003-01-01

A dosimetric survey in paediatric radiology is currently being carried out at the paediatric units of two large hospitals in Rio de Janeiro city: IPPMG (Instituto de Pediatria e Puericultura Martagao Gesteira, University Hospital of Federal University of Rio de Janeiro) and IFF (Instituto Fernandes Figueira, FIOCRUZ). Chest X-ray examination doses for AP, PA and LAT projections of paediatric patients have been obtained with thermoluminescent dosimeters (TLDs) and with use of a software package DoseCal. In IPPMG and IFF 100 patients have been evaluated with the use of the TLDs and another group of 100 patients with the DoseCal software. The aim of this work was to estimate the entrance skin dose (ESD) for frontal, back and lateral chest X-rays exposure of paediatric patients. For ESD evaluation, three different TL dosimeters have been used, namely LIF:Mg, Ti (TLD100), CaSO 4 :Dy and LiF:Mg, Cu, P (TLD100H). The age intervals considered were 0-1, 1-5, 5-10 and 10-15 years. The results obtained with all dosimeters are similar, and it is in good agreement with the DoseCal software, especially for AP and PA projections. However, some larger discrepancies are presented for the LAT projection

Establishing an individual dosing system for patients undergoing interventional transcatheter arterial embolization: Radiochromic film and Monte Carlo simulation

International Nuclear Information System (INIS)

Tsai, Hui-Yu; Lai, Pei-Ling; Li, Yang-Ying; Tyan, Yeu-Sheng

2011-01-01

Less invasive imaging-guided vascular interventions with fluoroscopy and digital subtraction angiography have recently become widespread and have been successfully used for treating various diseases. However, interventional fluoroscopy procedures may present deterministic and stochastic radiation risks. The International Commission on Radiological Protection (ICRP) and the Food and Drug Administration have requested identifying procedures that may involve patient doses greater than the recommended thresholds. In this study, radiochromic dosimetric media, known as self-developing films, and measurement-based Monte Carlo simulations were used to establish an interventional radiology dosing system for individual patients undergoing interventional transcatheter arterial embolization. The peak skin dose, evaluated from the entrance surface dose distribution, was 21% less than the cumulated dose reported from the console. A 3D dose map incorporated into CT images was established. The organ doses and effective doses for individual patients were evaluated using this dosing system. This system could be applied very well to other fluoroscopic or interventional procedures for patient dose management.

Mathematics for common entrance three (extension) answers

CERN Document Server

Alexander, Serena

2015-01-01

This book contains answers to all exercises featured in the accompanying textbook Mathematics for Common Entrance Three (Extension) , which provides essential preparation for Level 3 of the ISEB 13+ Mathematics exam, as well as for CASE and other scholarship exams. - Clean, clear layout for easy marking. - Includes examples of high-scoring answers with diagrams and workings. Also available to purchase from the Galore Park website www.galorepark.co.uk :. - Mathematics for Common Entrance Three (Extension). - Mathematics for Common Entrance One. - Mathematics for Common Entrance One Answers. - M

Measurements and applications of dose indices in radiography

International Nuclear Information System (INIS)

Chen, T.R.; Tyan, Y.S.; Yang, J.J.; Shao, C.H.; Lin, J.Y.; Tung, C.J.

2011-01-01

Assessments of radiation dose and image quality are required in diagnostic radiography for quality assurance and optimization studies. In work currently being undertaken, dose indices were measured and image quality evaluated for a chest PA procedure. Thermoluminescent dosimeters of the GR-200 type were attached to the entrance and exit surfaces and placed at various depths of the PMMA phantom to measure the entrance surface dose, the exit surface dose, and the organ dose index. The effective dose was estimated from the entrance surface dose using PCXMC software. Two contrast-detail image plates, one with air holes for the low contrast objects and the other with gypsum holes for the high contrast objects, were used to obtain radiographic images. This image plate was placed at different depths from the entrance surface of the phantom to simulate objects at different positions in the body. Each image was evaluated by three independent radiologists to determine image quality. Analyses of radiation dose versus image quality were performed to determine the optimal technical factors such as, filtration and tube potential. It was found that an 11-cm thick PMMA phantom best simulated the patients. The fractional dose backscattered from this phantom was between 22% and 27% for kVp’s between 66 and 133. Optimization analyses showed that no extra filter was required. For low contrast objects, an optimal choice of tube potential was 120 kVp. For high contrast objects, a kVp as low as 77 kVp could be used, depending on the image quality requirement.

Association between cumulative radiation dose, adverse skin reactions, and changes in surface hemoglobin among women undergoing breast conserving therapy

Directory of Open Access Journals (Sweden)

Michael S. Chin

2017-06-01

Conclusion: HSI demonstrates promise in the assessment of skin dose as well as an objective measure of skin reaction. The ability to easily identify adverse skin reactions and to modify the treatment plan may circumvent the need for detrimental treatment breaks.

The dependence of skin lesions on the depth-dose distribution from β-irradiation of people in the Chernobyl nuclear power plant accident

International Nuclear Information System (INIS)

Barabanova, A.

1990-01-01

A detailed study was made of conditions of exposure of 56 Chernobyl victims who suffered skin radiation lesions. The most typical conditions were experimentally reconstructed to investigate specific characteristics of dose distribution to the skin according to depth for different exposure conditions. Absorbed doses at depths of 7 mg cm -2 and 150 mg cm -2 were calculated on the basis of measurements with multilayer skin dosemeters. Patients were classified into four groups. Dosimetric characteristics for each group were compared with clinical pictures to establish critical factors in the occurrence of lesions. It was demonstrated that depth-dose distribution of β-radiation to the skin is of great influence not only for early effects of radiation but also for later effects. Radiation lesions in the skin led to death if the area of the lesions exceeded about 50% total body surface, and if doses to the skin were about 200-300 Gy at 7 mg cm -2 and more than about 30 Gy at 150 mg cm -2 . (author)

[Evaluation of patient doses in interventional radiology].

Science.gov (United States)

Ropolo, R; Rampado, O; Isoardi, P; Gandini, G; Rabbia, C; Righi, D

2001-01-01

To verify the suitability of indicative quantities to evaluate the risk related to patient exposure, in abdominal and vascular interventional radiology, by the study of correlations between dosimetric quantities and other indicators. We performed in vivo measurements of entrance skin dose (ESD) and dose area product (DAP) during 48 procedures to evaluate the correlation among dosimetric quantities, and an estimation of spatial distribution of exposure and effective dose (E). To measure DAP we used a transmission ionization chamber and to evaluate ESD and its spatial distribution we used radiographic film packed in a single envelope and placed near the patient's skin. E was estimated by a calculation software using data from film digitalisation. From the data derived for measurements in 27 interventional procedures on 48 patients we obtained a DAP to E conversion factor of 0.15 mSv / Gy cm2, with an excellent correlation (r=.99). We also found a good correlation between DAP and exposure parameters such as fluoroscopy time and number of images. The greatest effective dose was evaluated for a multiple procedure in the hepatic region, with a DAP value of 425 Gy cm2. The greatest ESD was about 550 mGy. For groups of patients undergoing similar interventional procedures the correlation between ESD and DAP had conversion factors from 6 to 12 mGy Gy-1 cm-2. The evaluation of ESD and E by slow films represents a valid method for patient dosimetry in interventional radiology. The good correlation between DAP and fluoroscopy time and number of images confirm the suitability of these indicators as basic dosimetric information. All the ESD values found are lower than threshold doses for deterministic effects.

Local organ dose conversion coefficients for angiographic examinations of coronary arteries

International Nuclear Information System (INIS)

Schlattl, H; Zankl, M; Hausleiter, J; Hoeschen, C

2007-01-01

New organ dose conversion coefficients for coronary angiographic interventions are presented, as well as dose distributions and resulting maximal local dose conversion coefficients in the relevant organs. For the Monte Carlo based simulations, voxel models of the human anatomy were employed which represent the average Caucasian adult man and woman as defined by the International Commission on Radiological Protection. In the 21 investigated projections, the mean organ dose conversion coefficients vary from a few 0.01 to 2 mGy(Gy cm 2 ) -1 , depending on the projections. However, especially in portions of the lungs and the active bone marrow, the conversion coefficients can locally amount up to 10 mGy(Gy cm 2 ) -1 , which is half the average conversion coefficient of the skin at the field entrance. In addition to the dose conversion coefficients, the dependence of the patient dose on the projection has been estimated. It could be shown that the patient doses are highest for left anterior oblique views with strong caudal or cranial orientation. Nevertheless, for a large range of image-intensifier positions no significant dose differences could be found

8-MOP PUVA for psoriasis: a comparison of a minimal phototoxic dose-based regimen with a skin-type approach

Energy Technology Data Exchange (ETDEWEB)

Collins, P.; Wainwright, N.J.; Amorim, I.; Lakshmipathi, T.; Ferguson, J. [Ninewells Hospital and Medical School, Dundee (United Kingdom)

1996-08-01

Two ultraviolet A (UVA) regimens for oral 8-methoxypsoralen (8-MOP) photochemotherapy (PUVA) for moderate/severe chronic plaque psoriasis using a half-body study technique were compared. Each patient received both regimens. A higher-dose regimen based on minimal phototoxic dose (MPD) with percentage incremental increases was given to one-half of the body. The other half received a lower dose regimen based on skin type with fixed incremental UVA increases. Patients were treated twice weekly. Symmetrical plaques were scored to determine the rate of resolution with each regimen. In addition, the number of treatments, cumulative UVA dose and number of days in treatment to achieve overall clearance were recorded. Patients were reviewed monthly for one year to record remission data. Thirty-three patients completed the study. Both regimens were effective and well tolerated. With the MPD-based approach, number of exposures was significantly less for patients with skin types I and II but not III. Although the cumulative UVA dose was higher with the MPD regimen for all skin types studied, the reduced number of exposures required for clearance for skin types I and II but not III, combined with the security of individualized MPD testing, has practical attractions. MPD testing also identified five patients who required an increased psoralen dose and six patients who required a reduction of the initial UVA dose with the skin type regimen. Forty-two percent were still clear 1 year after treatment and there was no significant difference in the number of days in remission between the regimens for those whose psoriasis had recurred. The reduction in the number of exposures required for clearance with the MPD-based regimen may be safer and more cost effective in the long term. (author).

Assessment of Organ Radiation Dose Associated with Uterine Artery Embolization

International Nuclear Information System (INIS)

Glomset, O.; Hellesnes, J.; Heimland, N.; Hafsahl, G.; Smith, H.J.

2006-01-01

Purpose: To evaluate the radiation dose to the skin, uterus, and ovaries during uterine artery embolization. Material and Methods: Guided uterine artery embolization for leiomyomata and two types of X-ray equipment with different dose levels were utilized during fluoroscopy in 20 women (ages ranging from 32 to 52 years, body weights from 55 to 68 kg). The first 13 women were treated using a non-pulsed system A, with 3.3 mm Al filtering and, for simplicity, a fixed peak voltage 80 kV. During treatment of the other 7 women, a pulsed system B with 5.4 mm Al filtering and an identical fixed voltage was used. The dose area product (DAP) was recorded. The vaginal dose of the first 13 patients and the peak skin dose of all patients were measured with thermoluminescent dosimeters (TLDs). TLDs were placed in the posterior vaginal fornix and on the skin at the beam entrance site. The uterine and ovarian doses were estimated based on the measured skin doses, normalized depth dose, and organ depth values. The effective dose (D eff ) was estimated based on the observed DAP values. The measured vaginal doses and the corresponding estimated uterine doses were compared statistically, as were the DAP values from systems A and B. Results: For system A, the mean fluoroscopic time was 20.9 min (range 12.7-31.1), and for system B 35.9 min (range 16.4-55.4). The mean numbers of angiographic exposures for systems A and B were 82 (range 30-164) and 37 (range 20-72), respectively. The mean peak skin dose for system A was 601.5 mGy (range 279-1030) and for system B 453 mGy (range 257-875). The mean DAP for system A was 88.6 Gy cm 2 (range 41.4-161.0) and for system B 52.5 Gy cm 2 (range 20.1-107.9). Statistical analysis showed a significant difference between the DAP values, the DAP for system B being the lower one. The mean estimated effective doses from systems A and B were 32 mSv (range 15.1-58.4) and 22 mSv (range 9-46), respectively. The mean estimated maximum uterine and ovarian doses

Patient dose measurement and dose reduction in chest radiography

Directory of Open Access Journals (Sweden)

Milatović Aleksandra A.

2014-01-01

Full Text Available Investigations presented in this paper represent the first estimation of patient doses in chest radiography in Montenegro. In the initial stage of our study, we measured the entrance surface air kerma and kerma area product for chest radiography in five major health institutions in the country. A total of 214 patients were observed. We reported the mean value, minimum and third quartile values, as well as maximum values of surface air kerma and kerma area product of patient doses. In the second stage, the possibilities for dose reduction were investigated. Mean kerma area product values were 0.8 ± 0.5 Gycm2 for the posterior-anterior projection and 1.6 ± 0.9 Gycm2 for the lateral projection. The max/min ratio for the entrance surface air kerma was found to be 53 for the posterior-anterior projection and 88 for the lateral projection. Comparing the results obtained in Montenegro with results from other countries, we concluded that patient doses in our medical centres are significantly higher. Changes in exposure parameters and increased filtration contributed to a dose reduction of up to 36% for posterior-anterior chest examinations. The variability of the estimated dose values points to a significant space for dose reduction throughout the process of radiological practice optimisation.

Comparison of skin doses to large fields using tangential beams from cobalt-60 gamma rays and 4-MV x rays

International Nuclear Information System (INIS)

Gagnon, W.F.; Peterson, M.D.

1978-01-01

Excess radiation to the skin during external beam megavoltage radiation therapy has reportedly caused excessive erythema in patients treated with the Clinac 4 linear accelerator on sloping surfaces, but not for similar treatments with cobalt-60. Doses at the epidermal level were measured under geometries simulating sloping surfaces for a Clinac 4 and an Eldorado 8 cobalt-60 teletherapy machine. For equal doses to the axilla, doses to the epidermal layer were similar. When the tumor dose was calculated for the mediastinum, the dose to the skin in the axillary region was 12% higher for the Clinac 4

Comparison of programmed and cabled re-entrance systems. Elaboration of cabled re-entrance system for a CII 90.40

International Nuclear Information System (INIS)

Perraudeau, Jean

1976-01-01

The objective of this research thesis is to study problems related to re-entrance, and, more particularly, to study a re-entrance system for a CII 90.40 computer. Such a system can be realised under a programmed or cabled form, and both approaches are described and compared. A generalisation of this comparison is briefly proposed. As the computer already possesses a programmed re-entrance system, the author focuses on the study of the cabled re-entrance system which results in an improvement of performance and possibilities provided by this computer, particularly for its use in real time. The design, realisation and development of such a cabled system are reported. A first part reports a theoretical study on re-entrance (definition, problems, applications), a presentation of the computer, a description of the programmed re-entrance system, a presentation of the principle of the chosen cabled re-entrance system, a definition of the structure and operating mode of the cabled pile and a description of its various components, and a flowchart analysis of function execution. The second part reports the practical realisation: definition, technological overview, technology used in the cabled pile, sequencing and multiplexing principle, impulse transmission, logical layouts, and circuit adjustments. The third part presents practical example. An assessment and perspectives are finally discussed

TH-AB-207A-03: Skin Dose to Patients Receiving Multiple CTA and CT Exams of the Head

International Nuclear Information System (INIS)

Nawfel, RD; Young, G

2016-01-01

Purpose: To measure patient skin dose from CT angiography (CTA) and CT exams of the head, and determine if patients having multiple exams could receive cumulative doses that approach or exceed deterministic thresholds. Methods: This study was HIPAA compliant and conducted with IRB approval. Patient skin doses were measured over a 4 month period using nanoDot OSL dosimeters placed on the head of 52 patients for two CT scanners. On each scanner, 26 patients received CT exams (scanner 1: 10 females, 16 males, mean age 64.2 years; scanner 2: 18 females, 8 males, mean age 61.2 years). CT exam dose metrics, CTDIvol and dose-length product (DLP) were recorded for each exam. Additionally, skin dose was measured on an acrylic skull phantom in each scanner and on a neuro-interventional imaging system using clinical protocols. Measured dose data was used to estimate peak skin dose (PSD) for 4 patients receiving multiple exams including CTA, head CT, and cerebral angiography. Results: For scanner 1, the mean PSD for CTA exams (98.9 ± 5.3 mGy) and for routine head CT exams (39.2 ± 3.7 mGy) agreed reasonably well with the PSD measured on the phantom, 105.4 mGy and 40.0 mGy, respectively. Similarly for scanner 2, the mean PSD for CTA exams (98.8 ± 7.4 mGy) and for routine head CT exams (42.9 ± 9.4 mGy) compared well with phantom measurements, 95.2 mGy and 37.6 mGy, respectively. In addition, the mean PSD was comparable between scanners for corresponding patient exams, CTA and routine head CT respectively. PSD estimates ranged from 1.9 – 4.5 Gy among 4 patients receiving multiple exams. Conclusion: Patients having several exams including both CTA and routine head CT may receive cumulative doses approaching or exceeding the threshold for single dose deterministic effects.

TH-AB-207A-03: Skin Dose to Patients Receiving Multiple CTA and CT Exams of the Head

Energy Technology Data Exchange (ETDEWEB)

Nawfel, RD; Young, G [Brigham & Women’s Hospital, Boston, MA (United States)

2016-06-15

Purpose: To measure patient skin dose from CT angiography (CTA) and CT exams of the head, and determine if patients having multiple exams could receive cumulative doses that approach or exceed deterministic thresholds. Methods: This study was HIPAA compliant and conducted with IRB approval. Patient skin doses were measured over a 4 month period using nanoDot OSL dosimeters placed on the head of 52 patients for two CT scanners. On each scanner, 26 patients received CT exams (scanner 1: 10 females, 16 males, mean age 64.2 years; scanner 2: 18 females, 8 males, mean age 61.2 years). CT exam dose metrics, CTDIvol and dose-length product (DLP) were recorded for each exam. Additionally, skin dose was measured on an acrylic skull phantom in each scanner and on a neuro-interventional imaging system using clinical protocols. Measured dose data was used to estimate peak skin dose (PSD) for 4 patients receiving multiple exams including CTA, head CT, and cerebral angiography. Results: For scanner 1, the mean PSD for CTA exams (98.9 ± 5.3 mGy) and for routine head CT exams (39.2 ± 3.7 mGy) agreed reasonably well with the PSD measured on the phantom, 105.4 mGy and 40.0 mGy, respectively. Similarly for scanner 2, the mean PSD for CTA exams (98.8 ± 7.4 mGy) and for routine head CT exams (42.9 ± 9.4 mGy) compared well with phantom measurements, 95.2 mGy and 37.6 mGy, respectively. In addition, the mean PSD was comparable between scanners for corresponding patient exams, CTA and routine head CT respectively. PSD estimates ranged from 1.9 – 4.5 Gy among 4 patients receiving multiple exams. Conclusion: Patients having several exams including both CTA and routine head CT may receive cumulative doses approaching or exceeding the threshold for single dose deterministic effects.

WE-E-18A-03: How Accurately Can the Peak Skin Dose in Fluoroscopy Be Determined Using Indirect Dose Metrics?

International Nuclear Information System (INIS)

Jones, A; Pasciak, A

2014-01-01

Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that Result in skin reactions can be reached during these procedures. The purpose of this study was to assess the accuracy of different indirect dose estimates and to determine if PSD can be calculated within ±50% for embolization procedures. Methods: PSD were measured directly using radiochromic film for 41 consecutive embolization procedures. Indirect dose metrics from procedures were collected, including reference air kerma (RAK). Four different estimates of PSD were calculated and compared along with RAK to the measured PSD. The indirect estimates included a standard method, use of detailed information from the RDSR, and two simplified calculation methods. Indirect dosimetry was compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the indirect estimates were examined. Results: PSD calculated with the standard calculation method were within ±50% for all 41 procedures. This was also true for a simplified method using a single source-to-patient distance (SPD) for all calculations. RAK was within ±50% for all but one procedure. Cases for which RAK or calculated PSD exhibited large differences from the measured PSD were analyzed, and two causative factors were identified: ‘extreme’ SPD and large contributions to RAK from rotational angiography or runs acquired at large gantry angles. When calculated uncertainty limits [−12.8%, 10%] were applied to directly measured PSD, most indirect PSD estimates remained within ±50% of the measured PSD. Conclusions: Using indirect dose metrics, PSD can be determined within ±50% for embolization procedures, and usually to within ±35%. RAK can be used without modification to set notification limits and substantial radiation dose levels. These results can be extended to similar procedures, including vascular and interventional oncology

Skin autofluorescence reflects individual seasonal UV exposure, skin photodamage and skin cancer development in organ transplant recipients.

Science.gov (United States)

Togsverd-Bo, Katrine; Philipsen, Peter Alshede; Hædersdal, Merete; Wulf, Hans Christian Olsen

2018-01-01

Ultraviolet radiation (UVR)-induced skin cancers varies among organ transplant recipients (OTRs). To improve individual risk assessment of skin cancer, objectively quantified skin photodamage is needed. We measured personal UVR-exposure dose in OTRs and assessed the relation between individual UVR exposure, skin cancer and objectively measured photodamage in terms of skin autofluorescence, pigmentation, and black light-evaluated solar lentigines. Danish OTRs with (n=15) and without a history of skin cancer (n=15) kept sun diaries from May to September and wore personal dosimeters recording time-stamped UVR doses in standard erythema doses (SED). Photodamage was quantified as skin autofluorescence with excitation at 370nm (F370) and 430nm (F430), skin pigmentation (pigment protection factor, PPF), and black light-evaluated solar lentigines. OTRs with skin cancer received a higher UVR dose than OTRs without skin cancer (median 116 SED vs. 67 SED, p=0.07) and UVR exposure doses were correlated with increased PPF (p=0.052) and F370 on the shoulder (F370 shoulder ) (p=0.04). We found that skin cancer was associated with F370 shoulder (OR 10.53, CI 3.3-31,938; p=0.018) and time since transplantation (OR 1.34, CI 0.95-1.91, p=0.097). A cut-off at 7.2 arbitrary units, 89% of OTRs with skin cancer had F370 shoulder values above 7.2 arbitrary units and F370 shoulder was additionally related to patient age (p=0.09) and black light-evaluated solar lentigines (p=0.04). F370 autofluorescence indicates objectively measured photodamage and may be used for individual risk assessment of skin cancer development in OTRs. Copyright © 2017. Published by Elsevier B.V.

Paediatric dose measurements for chest X-ray examinations at Maternity and Children Hospital in Najran - Saudi Arabia

International Nuclear Information System (INIS)

Saeed, M.K.; Al-Qahtani, J.M.

2012-01-01

The entrance skin dose (ESD) of chest X-ray examinations for AP and PA projections of paediatric patients at Maternity and Children Hospital in Najran, Saudi Arabia have been obtained using DoseCal software. The majority of the results obtained show low measured ESD for chest X-ray examinations. The mean of ESD for the AP projection was found to be 37.5, 40.5, 41.3, and 52.3μGy for age groups 0−1, >1−5, >5−10, and >10−15 years respectively. However, the ESD for PA projection was found to be 50.7 and 56.7μGy for age groups >5−10, and >10−15 years respectively.

Dose-response models for the radiation-induction of skin tumours in mice

International Nuclear Information System (INIS)

Papworth, D.G.; Hulse, E.V.

1983-01-01

Extensive data on radiation-induced skin tumours in mice were examined using 8 models, all based on the concept that incidences of radiation-induced tumours depend on a combination of two radiation effects: a tumour induction process and the loss of reproductive integrity by the potential tumour cells. Models with and without a threshold were used, in spite of theoretical objections to threshold models. No model fitted well both the epidermal and the dermal tumour data and models which proved to be statistically satisfactory for some of the data were rejected for biological reasons. It is concluded that, for skin tumours, dose-response curves depending on a combination of cancer induction and loss of cellular reproductive integrity are distorted by some special, relatively radio-resistant, factor which we have previously postulated as being involved in radiation skin carcinogenesis. (author)

Determination of Doses for X-Ray Examinations of Paranasal Sinuses of Children

International Nuclear Information System (INIS)

Milkovic, D.; Miljanic, S.; Knezevic, Z.; Ranogajec-Komor, M.; Beck, N; Zagar, I.

2013-01-01

The knowledge of the absorbed doses during X-ray examination is very important, especially in paediatric radiology in order to improve radiation protection. In childhood, the paranasal sinuses diseases are very frequent and the development of sinuses has some specialities which has to be taken into consideration in X-ray diagnostics. The aim of this work was the determination of the relative doses on the thyroid gland and eyes, in respect to the entrance dose on the anthropomorphic child phantom (CIRS). The entrance doses on the phantom to the entrance dose on patients of similar age. Simultaneously the influence of human working method was studied, i.e. the performance of the radiological technicians. The age of the patients varied from 7 to 15 years, the child phantom was equivalent to 10 years age. A protective lead apron on the necks of both children and phantom was used. Doses were measured with radiophotoluminescence (RPL) and thermoluminescence (TL) dosemeters. The mean doses on the thyroid and the eyes measured in the phantom after 10 expositions were 0.20 ± 0.05 mSv, and 0.32 ± 0.02 mSv, respectively. Relative doses were calculated in relation to entrance dose of 9.96 mSv for 10 exposures, and the results were 0.02 and 0.03 for the thyroid gland and the eyes, respectively. The dosimetry results on 45 patients showed that there was a good correlation between measured doses and the body mass index (BMI). The mean entrance dose measured on the 45 patients was 0.97 ± 0.08 mSv.(author)

Estimation of dose in skin through the use of radiochromic and radiographic films in patients subjected to interventional procedures

International Nuclear Information System (INIS)

Campos Garcia, Juan Pablo

2014-01-01

Radiation doses in skin of patients subjected to interventional procedures is estimated from the utilization and analysis of GAFCHROMIC® XR-RV2 radiochromic films and KODAK® X-Omat films with aid of the ImageJ software. The distribution of the radiation fields in the films is generated to obtain the distribution of dose in skin and to find peaks of dose by isodose curves using ImageJ software. The calibration curves are realized from GAFCHROMIC® XR-RV2 radiochromic films, through the use of a densitometer and two types of scanners (reflection scanner and transmission scanner). The reflection scanner has digitalized color images of 48 bit in TIFF format. The scanner transmission has digitalized in grayscale images to 16 bit in TIFF format. Each method has determined the points with maximum dose in skin. The images of the areas of regions with maximum doses are obtained of the scanner. The quantified doses are compared in the radiochromic films with the band of doses supplied by the manufacturer. The methodologies for the estimation of the doses obtained are compared of the radiochromic films with those obtained with the KODAK® X-Omat films. The procedure of obtaining of the doses is validated in patients with KODAK® X-Omat films. The doses obtained have covered a range from the 0,1Gy to 9 Gy. Radiographic films have allowed an assessment of the doses to 900 cGy due to the saturation thereof, the doses found in that range have been consistent with the doses in radiochromic films [es

SU-E-T-632: Preliminary Study On Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculations

International Nuclear Information System (INIS)

Jin, L; Eldib, A; Li, J; Price, R; Ma, C

2015-01-01

Purpose: Uneven nose surfaces and air cavities underneath and the use of bolus present complexity and dose uncertainty when using a single electron energy beam to plan treatments of nose skin with a pencil beam-based planning system. This work demonstrates more accurate dose calculation and more optimal planning using energy and intensity modulated electron radiotherapy (MERT) delivered with a pMLC. Methods: An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reduce the scatter-caused penumbra, a short SSD (61 cm) was used. Our previous work demonstrates good agreement in percentage depth dose and off-axis dose between calculations and film measurement for various field sizes. A MERT plan was generated for treating the nose skin using a patient geometry and a dose volume histogram (DVH) was obtained. The work also shows the comparison of 2D dose distributions between a clinically used conventional single electron energy plan and the MERT plan. Results: The MERT plan resulted in improved target dose coverage as compared to the conventional plan, which demonstrated a target dose deficit at the field edge. The conventional plan showed higher dose normal tissue irradiation underneath the nose skin while the MERT plan resulted in improved conformity and thus reduces normal tissue dose. Conclusion: This preliminary work illustrates that MC-based MERT planning is a promising technique in treating nose skin, not only providing more accurate dose calculation, but also offering an improved target dose coverage and conformity. In addition, this technique may eliminate the necessity of bolus, which often produces dose delivery uncertainty due to the air gaps that may exist between the bolus and skin

Treatment of skin carcinomas of the face by high-dose-rate brachytherapy and custom-made surface molds

International Nuclear Information System (INIS)

Guix, Benjamin; Finestres, Fernando; Tello, Jose-Ignacio; Palma, Cesar; Martinez, Antonio; Guix, Jose-Ramon; Guix, Ricardo

2000-01-01

Purpose: To analyze the results obtained in a prospective group of patients with basal or squamous cell skin carcinomas of the face treated by high-dose-rate (HDR) brachytherapy via custom-made surface molds. Methods and Materials: A total of 136 patients with basal or squamous cell carcinomas of the face were treated between March 1992 and March 1997 by surface molds and HDR brachytherapy with iridium-192. Nineteen patients were treated with standard Brock applicators and 117 patients with custom-made polymethyl methacrylate applicators, built over a plaster mold obtained of the patient's face. Minimum dose administered to the tumor was 6000 to 6500 cGy in 33 to 36 fractions at 180 cGy/fraction in lesions of up to 4 cm. Lesions greater than 4 cm were boosted up to 7500-8000 cGy after a 3-week pause. Results: With the custom-made surface molds, the dose distribution was uniform in the surface of the skin and at 5 mm depth in the whole area of the applicator. Differences between the areas of maximum and minimum dose at this depth never reached values higher than 5% of the prescribed dose. At the edges of the custom-made molds dose gradient was sharp, with the detected dose at 5 mm from the applicator being negligible. All the patients were complete responders. There were 3 local recurrences, 1/73 patients treated for primary tumor and 2/63 patients treated for recurrent tumor. Actuarial local control at 5 years for all patients was 98%, for those patients with primary tumors 99%, and for recurrent patients 87%. The treatment tolerance was excellent in all cases. No severe, early, or late, complications were detected. Conclusions: Radiotherapy is a highly effective treatment of skin carcinomas of the face. Custom-made molds, to be used in conjunction with HDR brachytherapy equipment, make possible a uniform dose distribution, with a sharp dose gradient in the limits of applicators. Custom-made surface molds are easy and safe to use, and they fit very accurately for

Use of an electron reflector to improve dose uniformity at the vertex during total skin electron therapy

International Nuclear Information System (INIS)

Peters, V.G.

2000-01-01

Purpose: The vertex of the scalp is always tangentially irradiated during total skin electron therapy (TSET). This study was conducted to determine the dose distribution at the vertex for a commonly used irradiation technique and to evaluate the use of an electron reflector, positioned above the head, as a means of improving the dose uniformity. Methods and Materials: Phantoms, simulating the head of a patient, were irradiated using our standard procedure for TSET. The technique is a six-field irradiation using dual angled electron beams at a treatment distance of 3.6 meters. Vertex dosimetry was performed using ionization methods and film. Measurements were made for an unmodified 6 MeV electron beam and for a 4 MeV beam obtained by placing an acrylic scattering plate in the beam line. Studies were performed to examine the effect of electron scattering on vertex dose when a lead reflector, 50 x 50 cm in area, was positioned above the phantom. Results: The surface dose at the vertex, in the absence of the reflector, was found to be less than 40% of the prescribed skin dose. Use of the lead reflector increased this value to 73% for the 6 MeV beam and 99% for the degraded 4 MeV beam. Significant improvements in depth dose were also observed. The dose enhancement is not strongly dependent on reflector distance or angulation since the reflector acts as a large source of broadly scattered electrons. Conclusion: The vertex may be significantly underdosed using standard techniques for total skin electron therapy. Use of an electron reflector improves the dose uniformity at the vertex and may reduce or eliminate the need for supplemental irradiation

Determination of effective dose in pediatric radiodiagnostic in Medellin-Colombia

International Nuclear Information System (INIS)

Garzon, William J.; Aramburo, Javier M.; Jimenez, Angelmiro A.; Ortiz, Anselmo P.

2013-01-01

In order to know the effective dose in pediatric X-ray exams of chest, entrance surface dose measurements were performed for ages 1,5 and 10 years in the largest pediatric hospital in the city of Medellin, Colombia. The effective dose was obtained from applying the conversion coefficients to measures of the entrance surface dose (ESD) in 306 radiographic studies in AP and LAT I projections. The results were validated with PCXMC 2.0 computer program and other work reported in the literature. (author)

Absorbed dose to the skin in radiological examinations of upper and lower gastrointestinal tract

International Nuclear Information System (INIS)

Zonca, G.; Brusa, A.; Somigliana, A.; Pasqualotto, C.; Sichirollo, A.E.; Bellomi, M.; Cozzi, G.; Severini, A.

1995-01-01

Absorbed doses to the skin in radiological examinations of the upper and lower gastronintestinal tract in conventional and digital radiology are evaluated and compared. Absorbed doses were measured with LiF thermoluminescence dosemeters placed on the lower pelvis, umbilicus and forehead of the patient to evaluate the absorbed dose in and outside the primary beam. On 10 patients a reduction in absorbed dose of about 34% for double contrast barium enema and of 66% for upper gastrointestinal tract examinations was revealed with digital radiography equipment. In our working conditions the lower dose requirement for digital radiography is mainly due to image intensifiers and television chains and also, due to our equipment settings, to the dose reduction with digital spot fluorography compared with conventional spot film radiography. (Author)

Single high-dose irradiation aggravates eosinophil-mediated fibrosis through IL-33 secreted from impaired vessels in the skin compared to fractionated irradiation

International Nuclear Information System (INIS)

Lee, Eun-Jung; Kim, Jun Won; Yoo, Hyun; Kwak, Woori; Choi, Won Hoon; Cho, Seoae; Choi, Yu Jeong; Lee, Yoon-Jin; Cho, Jaeho

2015-01-01

We have revealed in a porcine skin injury model that eosinophil recruitment was dose-dependently enhanced by a single high-dose irradiation. In this study, we investigated the underlying mechanism of eosinophil-associated skin fibrosis and the effect of high-dose-per-fraction radiation. The dorsal skin of a mini-pig was divided into two sections containing 4-cm 2 fields that were irradiated with 30 Gy in a single fraction or 5 fractions and biopsied regularly over 14 weeks. Eosinophil-related Th2 cytokines such as interleukin (IL)-4, IL-5, and C–C motif chemokine-11 (CCL11/eotaxin) were evaluated by quantitative real-time PCR. RNA-sequencing using 30 Gy-irradiated mouse skin and functional assays in a co-culture system of THP-1 and irradiated-human umbilical vein endothelial cells (HUVECs) were performed to investigate the mechanism of eosinophil-mediated radiation fibrosis. Single high-dose-per-fraction irradiation caused pronounced eosinophil accumulation, increased profibrotic factors collagen and transforming growth factor-β, enhanced production of eosinophil-related cytokines including IL-4, IL-5, CCL11, IL-13, and IL-33, and reduced vessels compared with 5-fraction irradiation. IL-33 notably increased in pig and mouse skin vessels after single high-dose irradiation of 30 Gy, as well as in irradiated HUVECs following 12 Gy. Blocking IL-33 suppressed the migration ability of THP-1 cells and cytokine secretion in a co-culture system of THP-1 cells and irradiated HUVECs. Hence, high-dose-per-fraction irradiation appears to enhance eosinophil-mediated fibrotic responses, and IL-33 may be a key molecule operating in eosinophil-mediated fibrosis in high-dose-per fraction irradiated skin. - Highlights: • Single high-dose irradiation aggravates eosinophil-mediated fibrosis through IL-33. • Vascular endothelial cells damaged by high-dose radiation secrete IL-33. • Blocking IL-33 suppressed migration of inflammatory cells and cytokine secretion. • IL-33

Single high-dose irradiation aggravates eosinophil-mediated fibrosis through IL-33 secreted from impaired vessels in the skin compared to fractionated irradiation

Energy Technology Data Exchange (ETDEWEB)

Lee, Eun-Jung, E-mail: forejs2@yuhs.ac [Department of Radiation Oncology, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Kim, Jun Won, E-mail: JUNWON@yuhs.ac [Department of Radiation Oncology, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Yoo, Hyun, E-mail: gochunghee@yuhs.ac [Department of Radiation Oncology, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Kwak, Woori, E-mail: asleo02@snu.ac.kr [Interdisciplinary Program in Bioinformatics, Seoul National University, Seoul 151-747 (Korea, Republic of); Choi, Won Hoon, E-mail: wonhoon@yuhs.ac [Department of Radiation Oncology, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Cho, Seoae, E-mail: seoae@cnkgenomics.com [C& K Genomics, Seoul National University Mt.4-2, Main Bldg. #514, SNU Research Park, NakSeoungDae, Gwanakgu, Seoul 151-919 (Korea, Republic of); Choi, Yu Jeong, E-mail: yunk9275@daum.net [Department of Radiation Oncology, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of); Lee, Yoon-Jin, E-mail: yjlee8@kirams.re.kr [Division of Radiation Effects, Research Center for Radiotherapy, Korea Institute of Radiological & Medical Sciences, Seoul 139-760 (Korea, Republic of); Cho, Jaeho, E-mail: jjhmd@yuhs.ac [Department of Radiation Oncology, Yonsei University College of Medicine, Seoul 120-752 (Korea, Republic of)

2015-08-14

We have revealed in a porcine skin injury model that eosinophil recruitment was dose-dependently enhanced by a single high-dose irradiation. In this study, we investigated the underlying mechanism of eosinophil-associated skin fibrosis and the effect of high-dose-per-fraction radiation. The dorsal skin of a mini-pig was divided into two sections containing 4-cm{sup 2} fields that were irradiated with 30 Gy in a single fraction or 5 fractions and biopsied regularly over 14 weeks. Eosinophil-related Th2 cytokines such as interleukin (IL)-4, IL-5, and C–C motif chemokine-11 (CCL11/eotaxin) were evaluated by quantitative real-time PCR. RNA-sequencing using 30 Gy-irradiated mouse skin and functional assays in a co-culture system of THP-1 and irradiated-human umbilical vein endothelial cells (HUVECs) were performed to investigate the mechanism of eosinophil-mediated radiation fibrosis. Single high-dose-per-fraction irradiation caused pronounced eosinophil accumulation, increased profibrotic factors collagen and transforming growth factor-β, enhanced production of eosinophil-related cytokines including IL-4, IL-5, CCL11, IL-13, and IL-33, and reduced vessels compared with 5-fraction irradiation. IL-33 notably increased in pig and mouse skin vessels after single high-dose irradiation of 30 Gy, as well as in irradiated HUVECs following 12 Gy. Blocking IL-33 suppressed the migration ability of THP-1 cells and cytokine secretion in a co-culture system of THP-1 cells and irradiated HUVECs. Hence, high-dose-per-fraction irradiation appears to enhance eosinophil-mediated fibrotic responses, and IL-33 may be a key molecule operating in eosinophil-mediated fibrosis in high-dose-per fraction irradiated skin. - Highlights: • Single high-dose irradiation aggravates eosinophil-mediated fibrosis through IL-33. • Vascular endothelial cells damaged by high-dose radiation secrete IL-33. • Blocking IL-33 suppressed migration of inflammatory cells and cytokine secretion. • IL

SU-F-T-81: Treating Nose Skin Using Energy and Intensity Modulated Electron Beams with Monte Carlo Based Dose Calculation

Energy Technology Data Exchange (ETDEWEB)

Jin, L; Fan, J; Eldib, A; Price, R; Ma, C [Fox Chase Cancer Center, Philadelphia, PA (United States)

2016-06-15

Purpose: Treating nose skin with an electron beam is of a substantial challenge due to uneven nose surfaces and tissue heterogeneity, and consequently could have a great uncertainty of dose accuracy on the target. This work explored the method using Monte Carlo (MC)-based energy and intensity modulated electron radiotherapy (MERT), which would be delivered with a photon MLC in a standard medical linac (Artiste). Methods: The traditional treatment on the nose skin involves the usage of a bolus, often with a single energy electron beam. This work avoided using the bolus, and utilized mixed energies of electron beams. An in-house developed Monte Carlo (MC)-based dose calculation/optimization planning system was employed for treatment planning. Phase space data (6, 9, 12 and 15 MeV) were used as an input source for MC dose calculations for the linac. To reduce the scatter-caused penumbra, a short SSD (61 cm) was used. A clinical case of the nose skin, which was previously treated with a single 9 MeV electron beam, was replanned with the MERT method. The resultant dose distributions were compared with the plan previously clinically used. The dose volume histogram of the MERT plan is calculated to examine the coverage of the planning target volume (PTV) and critical structure doses. Results: The target coverage and conformality in the MERT plan are improved as compared to the conventional plan. The MERT can provide more sufficient target coverage and less normal tissue dose underneath the nose skin. Conclusion: Compared to the conventional treatment technique, using MERT for the nose skin treatment has shown the dosimetric advantages in the PTV coverage and conformality. In addition, this technique eliminates the necessity of the cutout and bolus, which makes the treatment more efficient and accurate.

Entrance C - Meyrin site: new access conditions

CERN Multimedia

2013-01-01

Entrance C on the Meyrin site, which drivers of motorised vehicles can use Mondays to Fridays from 7 a.m. to 9 a.m. and from 5 p.m. to 7 p.m., has been altered to include a turnstile to allow cyclists and pedestrians to use their access card to get in and out of the site from 6 a.m. until 10 p.m.   The following video illustrates how to use the new turnstile: A new type of entrance gate fitted with a number plate reader similar to that installed at the entrance to the Prévessin site should, once fully tested, allow drivers of motorised vehicles to access the site. For the time being, the conditions of use of Entrance C remain unchanged. Further information on the entry into force of new arrangements will be issued in due course. For further information about CERN entrances: CERN opening hours CERN control access GS Department

Main clinical, therapeutic and technical factors related to patient's maximum skin dose in interventional cardiology procedures

Science.gov (United States)

Journy, N; Sinno-Tellier, S; Maccia, C; Le Tertre, A; Pirard, P; Pagès, P; Eilstein, D; Donadieu, J; Bar, O

2012-01-01

Objective The study aimed to characterise the factors related to the X-ray dose delivered to the patient's skin during interventional cardiology procedures. Methods We studied 177 coronary angiographies (CAs) and/or percutaneous transluminal coronary angioplasties (PTCAs) carried out in a French clinic on the same radiography table. The clinical and therapeutic characteristics, and the technical parameters of the procedures, were collected. The dose area product (DAP) and the maximum skin dose (MSD) were measured by an ionisation chamber (Diamentor; Philips, Amsterdam, The Netherlands) and radiosensitive film (Gafchromic; International Specialty Products Advanced Materials Group, Wayne, NJ). Multivariate analyses were used to assess the effects of the factors of interest on dose. Results The mean MSD and DAP were respectively 389 mGy and 65 Gy cm−2 for CAs, and 916 mGy and 69 Gy cm−2 for PTCAs. For 8% of the procedures, the MSD exceeded 2 Gy. Although a linear relationship between the MSD and the DAP was observed for CAs (r=0.93), a simple extrapolation of such a model to PTCAs would lead to an inadequate assessment of the risk, especially for the highest dose values. For PTCAs, the body mass index, the therapeutic complexity, the fluoroscopy time and the number of cine frames were independent explanatory factors of the MSD, whoever the practitioner was. Moreover, the effect of technical factors such as collimation, cinematography settings and X-ray tube orientations on the DAP was shown. Conclusion Optimising the technical options for interventional procedures and training staff on radiation protection might notably reduce the dose and ultimately avoid patient skin lesions. PMID:22457404

ICRP-26 and skin contamination

International Nuclear Information System (INIS)

Finnigan, T.; Huda, W.; Newbery, G.R.

1979-01-01

The experience of dealing with skin contamination incidents at The Radiochemical Centre over a 3-year period is presented. Data are given for the primary isotopes involved, the duration of skin contamination, and the skin doses that arise from these incidents. The methods employed in performing dosimetry for skin contamination are discussed and examples involving the isotopes carbon-14 and indium-111 are described. For skin contamination incidents, the mode of penetration of the activity into skin is normally not known and this can be of major significance for the final skin dose estimate. The operational health physics difficulties encountered in complying with both ICRP-26 and UK legislation for skin contamination are considered. In the event of multiple exposure (i.e. skin doses calculated from whole body film badges, extremity TLD dose meters and skin contamination) there is ambiguity in the precise meaning of the skin dose. The usefulness of Derived Working Levels is also discussed. Experience at The Radiochemical Centre has shown that good plant design, proper training and prompt action in dealing with contamination incidents ensures that overexposures to skin from accidental contamination are rare occurrences. (author)

An investigation of entrance surface dose calculations for diagnostic radiology using Monte Carlo simulations and radiotherapy dosimetry formalisms

International Nuclear Information System (INIS)

Omrane, L Ben; Verhaegen, F; Chahed, N; Mtimet, S

2003-01-01

Our aim in this work was to investigate the methodology used in the determination of the entrance surface dose (ESD) in diagnostic radiology. In kV x-rays for low-energy photons (tube potential up to 160 kV, HVL: 1-8 mm Al), the ESD is based on the use of the ratio of mass-energy absorption coefficients and backscatter factors. A full simulation of the photon and electron transport in a kilovoltage x-ray unit, using the Monte Carlo code BEAM/EGS4, was performed to obtain an accurate beam phase space for use in dose calculation. The modelled phase space was experimentally validated for the beam qualities (measured HVL: 3.3 mm Al-2.2 mm Cu) and showed good agreement between calculated and measured HVLs, air kerma and relative dose distributions. We have computed the conversion factors from air kerma to water or soft tissue absorbed dose at the surface of a phantom for beam qualities (HVL: 3.3-8.35 mm Al). The same model was also used to calculate the ESD in water and in soft tissue for the low-energy photon range considered. The results show that the numerical differences between the air kerma and the water kerma based backscatter factors are insignificant. The same conclusion was reached for the (μ en /ρ) ratios, for soft tissue to air, evaluated using either the primary photon spectra or the spectra at the surface of a phantom. Furthermore, the good agreement obtained for the computation of the conversion factors with a full BEAM/EGS4 model confirms the previous studies which are based on different sources for the spectral distribution and different beam geometries (pencil beam or point source assumptions). On the other hand, the ESD in water or soft tissue is well described either with the B air or the B w formalism. Conversion factors from air kerma to ESD in these media are proposed in this work for several beam qualities in diagnostic radiology

Influence of a Commercial Lead Apron on Patient Skin Dose Delivered During Oral and Maxillofacial Examinations under Cone Beam Computed Tomography (CBCT).

Science.gov (United States)

Schulze, Ralf Kurt Willy; Sazgar, Mahssa; Karle, Heiko; de Las Heras Gala, Hugo

2017-08-01

The purpose of this paper is to investigate the impact of a commercial lead apron on patient skin dose delivered during maxillofacial CBCT in five critical regions by means of solid-state-dosimetry. Five anatomical regions (thyroid gland, left and right breast, gonads, back of the phantom torso) in an adult female anthropomorphic phantom were selected for dose measurement by means of the highly sensitive solid-state dosimeter QUART didoSVM. Ten repeated single exposures were assessed for each patient body region for a total of five commercial CBCT devices with and without a lead apron present. Shielded and non-shielded exposures were compared under the paired Wilcoxon test, with absolute and relative differences computed. Reproducibility was expressed as the coefficient of variation (CV) between the 10 repeated assessments. The highest doses observed at skin level were found at the thyroid (mean shielded ± SD: 450.5 ± 346.7 μGy; non-shielded: 339.2 ± 348.8 μGy, p = 0.4922). Shielding resulted in a highly significant (p < 0.001) 93% dose reduction in skin dose in the female breast region with a mean non-shielded dose of approximately 35 μGy. Dose reduction was also significantly lower for the back-region (mean: -65%, p < 0.0001) as well as for the gonad-region (mean: -98%, p < 0.0001) in the shielded situation. Reproducibility was inversely correlated to skin dose (Rspearman = -0.748, p < 0.0001) with a mean CV of 10.45% (SD: 24.53 %). Skin dose in the thyroid region of the simulated patient was relatively high and not influenced by the lead apron, which did not shield this region. Dose reduction by means of a commercial lead apron was significant in all other regions, particularly in the region of the female breast.

Radiologic exposure conditions and resultant skin doses in application of xeroradiography to the orthodontic diagnosis

International Nuclear Information System (INIS)

Nakasima, A.; Nakata, S.; Shimizu, K.; Takahama, Y.

1980-01-01

Xeroradiography is the recording of radiologic image by a photoelectric process rather than the photochemical one used in conventional radiography. In order to investigate the advantages and disadvantages of xeroradiography in the orthodontic field, minimum xeroradiologic exposure conditions for skull projections, joint projections, and hand projections were established by thirteen examiners and the relationship between the image production and x-ray radiation was compared with conventional film techniques. The advantages of xeroradiograph were finer and clear images caused by the edge effect and wide latitude of xeroradiography; the main hazard was the unavoidable larger skin dose required by the projection procedures. The skin doses with xeroradiography were 2.4 to 16.2 times larger than those with conventional film techniques

Doses to patients and staff from endovascular treatment of abdominal aortic aneurysms - Preliminary results

International Nuclear Information System (INIS)

Bjoerklund, E.G.; Widmark, A.; Gjoelberg, T.; Bay, D.; Joergensen, J.J.; Staxrud, L.E.

2001-01-01

Patient radiation doses received during endovascular treatment of abdominal aortic aneurysms (AAA) can be significant and give rise to both deterministic and stochastic effects. Recording of dose-area product (DAP), fluoroscopy time and number of exposures together with calculations of effective dose, were performed for 8 patients. In addition, the entrance surface dose was measured for 3 of the patients. Typically, DAPs of 340 Gycm 2 , fluoroscopy times of 30 minutes and 310 exposures were obtained together with maximum entrance surface doses of 1,8 Gy and effective doses of 50 mSv. Finger doses to the staff performing the procedure were in the order of a few hundred μSv. Conversion factors (effective dose/DAP) and (maximum entrance surface does/DAP) of 0,61·10 -2 Gy/Gycm 2 and 0,15 mSv/Gycm 2 were obtained, respectively. (author)

SU-E-T-09: A Clinical Implementation and Optimized Dosimetry Study of Freiberg Flap Skin Surface Treatment in High Dose Rate Brachytherapy

Energy Technology Data Exchange (ETDEWEB)

Syh, J; Syh, J; Patel, B; Wu, H; Durci, M [Willis-Knighton Medical Center, Shreveport, LA (United States)

2015-06-15

Purpose: This case study was designated to confirm the optimized plan was used to treat skin surface of left leg in three stages. 1. To evaluate dose distribution and plan quality by alternating of the source loading catheters pattern in flexible Freiberg Flap skin surface (FFSS) applicator. 2. To investigate any impact on Dose Volume Histogram (DVH) of large superficial surface target volume coverage. 3. To compare the dose distribution if it was treated with electron beam. Methods: The Freiburg Flap is a flexible mesh style surface mold for skin radiation or intraoperative surface treatments. The Freiburg Flap consists of multiple spheres that are attached to each other, holding and guiding up to 18 treatment catheters. The Freiburg Flap also ensures a constant distance of 5mm from the treatment catheter to the surface. Three treatment trials with individual planning optimization were employed: 18 channels, 9 channels of FF and 6 MeV electron beam. The comparisons were highlighted in target coverage, dose conformity and dose sparing of surrounding tissues. Results: The first 18 channels brachytherapy plan was generated with 18 catheters inside the skin-wrapped up flap (Figure 1A). A second 9 catheters plan was generated associated with the same calculation points which were assigned to match prescription for target coverage as 18 catheters plan (Figure 1B). The optimized inverse plan was employed to reduce the dose to adjacent structures such as tibia or fibula. The comparison of DVH’s was depicted on Figure 2. External beam of electron RT plan was depicted in Figure 3. Overcall comparisons among these three were illustrated in Conclusion: The 9-channel Freiburg flap flexible skin applicator offers a reasonably acceptable plan without compromising the coverage. Electron beam was discouraged to use to treat curved skin surface because of low target coverage and high dose in adjacent tissues.

Calculation of local skin doses with ICRP adult mesh-type reference computational phantoms

Science.gov (United States)

Yeom, Yeon Soo; Han, Haegin; Choi, Chansoo; Nguyen, Thang Tat; Lee, Hanjin; Shin, Bangho; Kim, Chan Hyeong; Han, Min Cheol

2018-01-01

Recently, Task Group 103 of the International Commission on Radiological Protection (ICRP) developed new mesh-type reference computational phantoms (MRCPs) for adult males and females in order to address the limitations of the current voxel-type reference phantoms described in ICRP Publication 110 due to their limited voxel resolutions and the nature of the voxel geometry. One of the substantial advantages of the MRCPs over the ICRP-110 reference phantoms is the inclusion of a 50-μm-thick radiosensitive skin basal-cell layer; however, a methodology for calculating the local skin dose (LSD), i.e., the maximum dose to the basal layer averaged over a 1-cm2 area, has yet to be developed. In the present study, a dedicated program for the LSD calculation with the MRCPs was developed based on the mean shift algorithm and the Geant4 Monte Carlo code. The developed program was used to calculate local skin dose coefficients (LSDCs) for electrons and alpha particles, which were then compared with the values given in ICRP Publication 116 that were produced with a simple tissue-equivalent cube model. The results of the present study show that the LSDCs of the MRCPs are generally in good agreement with the ICRP-116 values for alpha particles, but for electrons, significant differences are found at energies higher than 0.15 MeV. The LSDCs of the MRCPs are greater than the ICRP-116 values by as much as 2.7 times at 10 MeV, which is due mainly to the different curvature between realistic MRCPs ( i.e., curved) and the simple cube model ( i.e., flat).

Video dosimetry: evaluation of X-radiation dose by video fluoroscopic image

International Nuclear Information System (INIS)

Nova, Joao Luiz Leocadio da; Lopes, Ricardo Tadeu

1996-01-01

A new methodology to evaluate the entrance surface dose on patients under radiodiagnosis is presented. A phantom is used in video fluoroscopic procedures in on line video signal system. The images are obtained from a Siemens Polymat 50 and are digitalized. The results show that the entrance surface dose can be obtained in real time from video imaging

A biosafety evaluation of synchrotron radiation X-ray to skin and bone marrow: single dose irradiation study of rats and macaques.

Science.gov (United States)

Lu, Yifan; Tang, Guanghui; Lin, Hui; Lin, Xiaojie; Jiang, Lu; Yang, Guo-Yuan; Wang, Yongting

2017-06-01

Very limited experimental data is available regarding the safe dosages related to synchrotron radiation (SR) procedures. We used young rats and macaques to address bone marrow and skin tolerance to various doses of synchrotron radiation. Rats were subjected to 0, 0.5, 2.5, 5, 25 or 100 Gy local SR X-ray irradiation at left hind limb. Rat blood samples were analyzed at 2-90 days after irradiation. The SR X-ray irradiated skin and tibia were sectioned for morphological examination. For non-human primate study, three male macaques were subjected to 0.5 or 2.5 Gy SR X-ray on crus. Skin responses of macaques were observed. All rats that received SR X-ray irradiation doses greater than 2.5 Gy experienced hair loss and bone-growth inhibition, which were accompanied by decreased number of follicles, thickened epidermal layer, and decreased density of bone marrow cells (p X-ray but showed significant hair loss when the dose was raised above 2.5 Gy. The safety threshold doses of SR X-ray for rat skin, bone marrow and macaque skin are between 0.5 and 2.5 Gy. Our study provided essential information regarding the biosafety of SR X-ray irradiation.

Development of a fibre-optic dosemeter to measure the skin dose and percentage depth dose in the build-up region of therapeutic photon beams

International Nuclear Information System (INIS)

Kim, K. A.; Yoo, W. J.; Jang, K. W.; Moon, J.; Han, K. T.; Jeon, D.; Park, J. Y.; Cha, E. J.; Lee, B.

2013-01-01

In this study, a fibre-optic dosemeter (FOD) using an organic scintillator with a diameter of 0.5 mm for photon-beam therapy dosimetry was fabricated. The fabricated dosemeter has many advantages, including water equivalence, high spatial resolution, remote sensing and real-time measurement. The scintillating light generated from an organic-dosemeter probe embedded in a solid-water stack phantom is guided to a photomultiplier tube and an electrometer via 20 m of plastic optical fibre. Using this FOD, the skin dose and the percentage depth dose in the build-up region according to the depths of a solid-water stack phantom are measured with 6- and 15-MV photon-beam energies with field sizes of 10310 and 20320 cm 2 , respectively. The results are compared with those measured using conventional dosimetry films. It is expected that the proposed FOD can be effectively used in radiotherapy dosimetry for accurate measurement of the skin dose and the depth dose distribution in the build-up region due to its high spatial resolution. (authors)

Effect of field size on the reaction of pig skin to single doses of X rays

Energy Technology Data Exchange (ETDEWEB)

Hopewell, J W; Young, C M.A. [Churchill Hospital, Oxford (UK)

1982-05-01

The importance of the size of the treatment area for the response of the skin to radiation has been studied in the pig. The responses of skin areas of 16 cm/sup 2/ (4 x 4 cm) and 64cm/sup 2/ (16 x 4 cm) were compared after single doses of X rays. In the initial 3-9-week period after irradiation the severity of the erythema reaction, which is associated with epidermal cell death, was not influenced by the area of skin irradiated. For the later dermal response (10-16 weeks) a similar result was obtained. The dose required to produce dermal necrosis in 50% of the fields treated (ED/sub 50/) was approximately 2070 cGy for both field sizes. Additional studies have shown that the ED/sub 50/ for dermal necrosis was not influenced by the age of animals at the time of irradiation. This was despite considerable differences in the vascular density and blood flow in pig skin with increasing age. The apparent contradiction between the results of this experimental study in the pig, which shows no effect of field size, and currently accepted clinical practice is discussed.

Functional and morphological changes in pig skin after single or fractionated doses in x rays

International Nuclear Information System (INIS)

Young, C.M.A.; Hopewell, J.W.

1982-01-01

The flank skin of pigs has been treated with either single or fractionated doses of x-irradiation. A single dose (2070 cGy) was compared with treatment given as 6 fractions in 18 days (6f/18 days; 3780 cGy) or 30 fractions in 39 days (30f/39 days; 8000 cGy). The doses were selected on the basis that similar levels of late tissue damage would result. Radiation induced changes in the skin were assessed by observing the skin reactions and by the measurement of isotope clearance (functional study), relative field contraction, dermal and epidermal thickness and dermal vascular density (morphological studies). In the three treatment groups the early radiation reaction varied considerably. In the first wave reaction (3 to 6 weeks after treatment) bright red erythema was recorded in many fields but moist desquamation developed only in the 30f/39 days treatment group. The second wave (10-16 weeks) was characterized by an ischemic mauve/dusky reaction. Dermal necrosis developed in 50% of the single dose fields. In the 30f/39 days regimen persistent moist desquamation progressed to dermal necrosis. Neither desquamation nor necrosis developed after 6f/18 days. Different levels of vascular damage in the dermis were assessed using an isotope clearance technique; for example in the early reaction significant changes were recorded in the papillary dermis (faster clearance) prior to the development of moist desquamation (30f/39 days) and in the reticular dermis (slower clearance) before necrosis (single dose). Changes in clearance rates have been correlated with changes in the vascular density and thickness of the dermis. Between 26 and 52 weeks (the late reaction) relative field contraction was slightly greater in the 30f/39 days group than in the other treatment groups

Energy saving in tunnel entrance lighting.

NARCIS (Netherlands)

Schreuder, D.A. & Swart, L.

1993-01-01

Tunnel entrances may present themselves during the day as a "black hole" in which no details can be perceived. In order to ensure safe and comfortable driving at high speeds, the entrance zone must be lit to a high luminance level. Modern tunnel lighting technology is focused on two aspects:

Assessment of influence of OSL dosimeters in the skin dose in radiotherapy: study for Monte Carlo simulation; Avaliacao da influencia de dosimetros OSL na dose na pele em radioterapia: estudo por simulacao Monte Carlo

Energy Technology Data Exchange (ETDEWEB)

Schuch, Franciely F.; Nicolucci, Patricia, E-mail: franschuch@yahoo.com.br [Universidade de Sao Paulo (USP), Ribeiraoo Preto, SP (Brazil)

2017-11-01

The interest in optically stimulated luminescence (OSL) dosimetry materials is growing due to its potential use in quality control in Radiotherapy. The use of these dosimeters for in vivo dosimetry, however, may influence the dose to the skin and deeper tissues in the patient. The goal of this study is to evaluate the influence of the OSL Al{sub 2}O{sub 3} material in dose deposited in the skin and deep in Radiotherapy. Monte Carlo simulation is used to evaluate this purpose when OSL dosimeters of Al{sub 2}O{sub 3} are positioned on the skin surface of the patient. Percentage depth dose curves for clinical beams of 6 and 10 MV were simulated with and without the presence of the dosimeter on the surface of a water phantom. The results showed a decrease of doses in regions close to the surface of the skin. In the build-up region, the maximum decreases of dose produced by the presence of the dosimeters were 52,5% and 47,5% for the 6 and 10 MV beams, respectively. After the build-up region, there are not significant changes in the doses for any of the used beams. The differences of doses found are due to the influence of the dosimetric material on the relative fluence of electrons near the end surface of the dosimeter. Thus, the results showed that the presence of the dosimetric material on the surface interferes on the skin dose. However, these dosimeters do not cause dose variations in depths of clinical interest, allowing its application in routine in vivo dosimetry in Radiotherapy. (author)

A model for predicting skin dose received by patients from an x-ray ...

African Journals Online (AJOL)

We have done this by modifying a model for predicting skin dose derived by Edmonds for a triple-phase generator. Results for 100 patients based on the triple-phase generator output show a reasonable average agreement (»1%) between our present model and the Edmonds's model. Although our earlier estimated ...

Surface dose investigation of the flattening filter-free photon beams.

Science.gov (United States)

Wang, Yuenan; Khan, Mohammad K; Ting, Joseph Y; Easterling, Stephen B

2012-06-01

Flattening filter-free (FFF) x-rays can provide more efficient use of photons and a significant increase of dose rate compared with conventional flattened x-rays, features that are especially beneficial for stereotactic radiosurgery (SRS) and stereotactic body radiotherapy (SBRT). The available data on the entrance doses of the FFF photon beams remain limited. The purpose of this study was to investigate the entrance dose of FFF photons in the buildup region and to compare it with that of conventional flattened photons. A Varian TrueBeam linear accelerator has been in full clinical operation with 6-MV and 10-MV FFF and flattened x-ray photons. Entrance dose at the surface was measured using a parallel plate ionization chamber in a solid water phantom with buildup depth = 0~15 mm for 6X and 0~25 mm for 10X. Different field size (FS) patterns were created in the Eclipse Treatment Planning System by multileaf collimator (MLC) rather than jaws (FS = 2 × 2, 3 × 3, 4 × 4, 6 × 6, and 10 × 10 cm(2) by MLC and jaw size = 2.2 × 2.2, 3.2 × 3.2, 4.2 × 4.2, 6 × 6, and 10 × 10 cm(2)). The smallest FS was about four times larger than the ion chamber dimension. All buildup dose measurements were normalized to FS = 10 × 10 cm(2) at the depth of dose maximum (dmax). Good repeatability was demonstrated and surface dose increased linearly with FS for both flattened and FFF photons. The entrance dose of the FFF photons was modestly larger than that of the corresponding flattened photons for both 6X and 10X for different FS ranging from 2 × 2 cm(2) to 10 × 10 cm(2). The FFF photons have a higher entrance dose than that of the corresponding flattened photons for FS smaller than 10 × 10 cm(2). However, the difference is not substantial and may be clinically insignificant. Published by Elsevier Inc.

Evaluation of two-dimensional bolus effect of immobilization/support devices on skin doses: A radiochromic EBT film dosimetry study in phantom

International Nuclear Information System (INIS)

Chiu-Tsao, Sou-Tung; Chan, Maria F.

2010-01-01

Purpose: In this study, the authors have quantified the two-dimensional (2D) perspective of skin dose increase using EBT film dosimetry in phantom in the presence of patient immobilization devices during conventional and IMRT treatments. Methods: For 6 MV conventional photon field, the authors evaluated and quantified the 2D bolus effect on skin doses for six different common patient immobilization/support devices, including carbon fiber grid with Mylar sheet, Orfit carbon fiber base plate, balsa wood board, Styrofoam, perforated AquaPlast sheet, and alpha-cradle. For 6 and 15 MV IMRT fields, a stack of two film layers positioned above a solid phantom was exposed at the air interface or in the presence of a patient alpha-cradle. All the films were scanned and the pixel values were converted to doses based on an established calibration curve. The authors determined the 2D skin dose distributions, isodose curves, and cross-sectional profiles at the surface layers with or without the immobilization/support device. The authors also generated and compared the dose area histograms (DAHs) and dose area products from the 2D skin dose distributions. Results: In contrast with 20% relative dose [(RD) dose relative to d max on central axis] at 0.0153 cm in the film layer for 6 MV 10x10 cm 2 open field, the average RDs at the same depth in the film layer were 71%, 69%, 55%, and 57% for Orfit, balsa wood, Styrofoam, and alpha-cradle, respectively. At the same depth, the RDs were 54% under a strut and 26% between neighboring struts of a carbon fiber grid with Mylar sheet, and between 34% and 56% for stretched perforated AquaPlast sheet. In the presence of the alpha-cradle for the 6 MV (15 MV) IMRT fields, the hot spot doses at the effective measurement depths of 0.0153 and 0.0459 cm were 140% and 150% (83% and 89%), respectively, of the isocenter dose. The enhancement factor was defined as the ratio of a given DAH parameter (minimum dose received in a given area) with and without

Radiofrequency catheter ablation: Relationship between fluoroscopic time and skin doses according to diagnoses. Basis to establish a quality assurance programme

International Nuclear Information System (INIS)

Cotelo, E.; Pouso, J.; Reyes, W.

2001-01-01

Radiofrequency Cardiac Catheter Ablation is an Interventional Radiology procedure of great complexity because the cardiologist needs a simultaneous evaluation of fluoroscopic images and electrophysiologic information. Therefore, the procedure typically involves extended fluoroscopic time that may cause radiation-skin injures to patients. Skin doses depend on many factors: equipment design features and its proper use, cardiologist practice, fluoroscopic time, irradiated areas, application of radiation protection recommendations, etc. We evaluate fluoroscopic time in relation to pathology and we estimate skin doses on 233 procedures at the Electrophysiology Laboratory in Casa de Galicia, Montevideo, Uruguay. Significant differences among the medians of fluoroscopic time were found in those procedures depending on diagnoses and results. Higher fluoroscopic time was found in flutter and auricular tachycardia (median was 83 minutes, p=0.0001). In successful procedures (almost 90%), median skin doses was 2.0 Grays (p=0.0001). On the basis of records information, the standard operating procedure and the clinical protocol, expanding close cooperation between the cardiologists and the experts in Radiation Protection will secure the establishment of an Assurance Quality Program. (author)

Estimating skin sensitization potency from a single dose LLNA.

Science.gov (United States)

Roberts, David W

2015-04-01

Skin sensitization is an important aspect of safety assessment. The mouse local lymph node assay (LLNA) developed in the 1990 s is an in vivo test used for skin sensitization hazard identification and characterization. More recently a reduced version of the LLNA (rLLNA) has been developed as a means of identifying, but not quantifying, sensitization hazard. The work presented here is aimed at enabling rLLNA data to be used to give quantitative potency information that can be used, inter alia, in modeling and read-across approaches to non-animal based potency estimation. A probit function has been derived enabling estimation of EC3 from a single dose. This has led to development of a modified version of the rLLNA, whereby as a general principle the SI value at 10%, or at a lower concentration if 10% is not testable, is used to calculate the EC3. This version of the rLLNA has been evaluated against a selection of chemicals for which full LLNA data are available, and has been shown to give EC3 values in good agreement with those derived from the full LLNA. Copyright © 2015 Elsevier Inc. All rights reserved.

The dose to the patient and the quality of the image in xeromammography

International Nuclear Information System (INIS)

Ramsden, J.A.; Moores, B.M.; Asbury, D.L.

1979-01-01

Radiation dose levels in xeromammography were measured both on entry and exit surfaces of the breast. The mean skin dose in the upper inner quadrant was 2.4 rad for a complete examination. The addition of 1 mm aluminium filtration reduced this dose to 1.6 rad. The mean dose to the breast tissues is, however, a more meaningful indication of potential hazard from mammographic investigations and entrance and exit dose measurements enable this to be assessed. The ability of xeroradiography to image small glass beads was assessed by visual detection tests on specially prepared phantoms and compared with earlier work on conventional mammography using industrial film and film-screen systems. With only inherent tube filtration the performance of xeroradiography was comparable to that of industrial film. The addition of 1 mm aluminium filtration as a means of reducing the dose received by the patient reduced the performance of xeroradiography to approximately that of a medium-speed mammographic film-screen system. The incorporation of tissue-equivalent scattering material further reduced the detection capability of xeroradiography as it does also for film-screen systems. (author)

Efficacy of patient skin dose reduction by a compensating filter through of irradiation field overlaps on the area during percutaneous coronary intervention

International Nuclear Information System (INIS)

Yamasaki, Hiroyuki; Yamaguchi, Sadao; Yamamoto, Naomi; Miyagawa, Takashi; Hirose, Etsuko; Takenaka, Tatsuaki; Nakahara, Makoto

2011-01-01

Our study was involved with entrance surface dose reduction and irradiation field by the filter use of PCI, and insertion in place of an effective compensating filter to maximize entrance surface dose reduction, which we verified. The radiation dosimetry put a 6 cc ion chamber on the back side of the thorax phantom, and changed the filter of the four corners (a: upper left, b: upper right, c: lower right, d: lower left) of the monitor confirmed with fluoroscopy [(0) no filter, (1) one filter, (2) two filters]. The angle of C arm was assumed to be eight directions and 0 degrees adopted by this hospital. It was compared with a corrective rate of which one was no filter. Next, the presence of filter and irradiation field overlaps on the area in monitor in the angle of C arm was verified by this hospital's classic example. As for corrective rate, (1) becomes 0.41 and (2) become 0.25 at fluoroscopy, (1) becomes 0.26 and (2) become 0.16 at exposure. Irradiation field overlaps on the area (+) compensating filter (-) was many with d of right anterior oblique (RAO)/cranial (CAU), a of RAO and c of CAU at left coronary angiography (CAG), c of left anterior oblique (LAO) at right CAG, b of LAO/cranial (CRA) (left CAG), b of CRA (right CAG) and a and d of RAO (right CAG) at both CAG. Irradiation field overlaps on the area (+) compensating filter (+) was many with b of CRA at left CAG, a of LAO/CRA at right CAG, b of CRA (left CAG) and b of RAO (right CAG) at both CAG. When the compensating filter is used the entrance surface dose reduction effect was great. If automatic exposure control protects the part of irradiation field overlaps on the area in the range without operating excessively, the radiological risk can be reduced, and it is conceivable as useful clinical setting. (author)

Method of examination of blood microcirculation in skin by multiple using of an identical dose of radioactive Xe/sup 133/ gas

Energy Technology Data Exchange (ETDEWEB)

Lewandowski, J.; Bogdanowski, T.; Brzezinska-Wcislo, L. (Slaska Akademia Medyczna, Katowice (Poland))

1981-01-01

The introduced method of Xe/sup 133/ gas application on epidermis serves to the investigation of microcirculation of blood within skin. It consists in a single use a dose of radioactive gas which is injected under the plastic membrane adhering to the skin surface. Our method of gaseous Xe/sup 133/ contact with epidermis enabling the multiple utilization of once applied dose to further examination is described.

Radiation dose and cancer risk among pediatric patients undergoing interventional neuroradiology procedures

International Nuclear Information System (INIS)

Thierry-Chef, Isabelle; Simon, Steven L.; Miller, Donald L.

2006-01-01

During interventional neuroradiology procedures, patients can be exposed to moderate to high levels of radiation. Special considerations are required to protect children, who are generally more sensitive to the short- and long-term detrimental effects of radiation exposure. Estimates of dose to the skin of children from certain interventional procedures have been published elsewhere, but we are not aware of data on dose to the brain or on the long-term risk of cancer from brain radiation. Our goals were to estimate radiation doses to the brain in 50 pediatric patients who had undergone cerebral embolization and to assess their lifetime risks of developing radiation-related brain cancer. Entrance-peak skin dose and various assumptions on conditions of exposure were used as input for dosimetric calculations to estimate the spatial pattern of dose within the brain and the average dose to the whole brain for each child. The average dose and the age of the child at time of exposure were used to estimate the lifetime risk of developing radiation-related brain cancer. Among the 50 patients, average radiation doses to the brain were estimated to vary from 100 mGy to 1,300 mGy if exposed to non-collimated fields and from 20 mGy to 160 mGy for collimated, moving fields. The lifetime risk of developing brain cancer was estimated to be increased by 2% to 80% as a result of the exposure. Given the very small lifetime background risk of brain tumor, the excess number of cases will be small even though the relative increase might be as high as 80%. ALARA principles of collimation and dose optimization are the most effective means to minimize the risk of future radiation-related cancer. (orig.)

Study of dose modification in skin cancers induced by the kind of bolus used - Bibliography

International Nuclear Information System (INIS)

Camilleri, Jeremy

2011-01-01

As tumour irradiation modalities differ from one pathology to another, and are even proper to each pathology (they depend on tumour nature, histology, size, location, and so on), but as therapeutic objectives remain unchanged (to deliver the prescribed dose to the target-volume with the highest possible precision while preserving as much as possible sane tissues as well as neighbouring organs at risk), this bibliographical study aims, on the one hand, at quantifying the dose variation generated by heterogeneous structures crossed by the electron beam, and on the other hand, at optimising the use of boluses during surface irradiations, notably in the case of skin cancers. The author addresses therapeutic indications of irradiation of skin cancers and of thoracic wall for which the application of a bolus is required, and then the associated irradiation techniques as well as bolus characteristics

Assessment of organ doses by standard X-ray procedures in the GDR

International Nuclear Information System (INIS)

Tautz, M.; Brandt, G.A.

1986-01-01

A modern method has been described to assess the radiation burden by X-ray procedures with consideration of the standards of our Society for Medical Radiology in the GDR. The underlying methodology is a Monte Carlo computer technique, which simulates stochastically the energy deposition of X-ray photons in a mathematically described heterogeneous anthropomorphic phantom by Rosenstein (US Department of Health, Education and Welfare). To apply the procedure specific values for the following parameters must be determined for each dose estimation: projection and view, X-ray field size and location entrance exposure at skin surface, beam quality, source-to-image receptor distance. The base data are obtained in terms of tissue-air ratio. Organ doses were calculated for chest, urography, skull, cervical spine, thoracic spine, lumbar spine, pelvis and lymphography. Concluding possibilities have been discussed for reduction of radiation burden. 9 refs., 6 figs., 9 tabs. (author)