Verification of gamma knife based fractionated radiosurgery with newly developed head-thorax phantom

International Nuclear Information System (INIS)

Bisht, Raj Kishor; Kale, Shashank Sharad; Natanasabapathi, Gopishankar; Singh, Manmohan Jit; Agarwal, Deepak; Garg, Ajay; Rath, Goura Kishore; Julka, Pramod Kumar; Kumar, Pratik; Thulkar, Sanjay; Sharma, Bhawani Shankar

2016-01-01

Objective: Purpose of the study is to verify the Gamma Knife Extend™ system (ES) based fractionated stereotactic radiosurgery with newly developed head-thorax phantom. Methods: Phantoms are extensively used to measure radiation dose and verify treatment plan in radiotherapy. A human upper body shaped phantom with thorax was designed to simulate fractionated stereotactic radiosurgery using Extend™ system of Gamma Knife. The central component of the phantom aids in performing radiological precision test, dosimetric evaluation and treatment verification. A hollow right circular cylindrical space of diameter 7.0 cm was created at the centre of this component to place various dosimetric devices using suitable adaptors. The phantom is made of poly methyl methacrylate (PMMA), a transparent thermoplastic material. Two sets of disk assemblies were designed to place dosimetric films in (1) horizontal (xy) and (2) vertical (xz) planes. Specific cylindrical adaptors were designed to place thimble ionization chamber inside phantom for point dose recording along xz axis. EBT3 Gafchromic films were used to analyze and map radiation field. The focal precision test was performed using 4 mm collimator shot in phantom to check radiological accuracy of treatment. The phantom head position within the Extend™ frame was estimated using encoded aperture measurement of repositioning check tool (RCT). For treatment verification, the phantom with inserts for film and ion chamber was scanned in reference treatment position using X-ray computed tomography (CT) machine and acquired stereotactic images were transferred into Leksell Gammaplan (LGP). A patient treatment plan with hypo-fractionated regimen was delivered and identical fractions were compared using EBT3 films and in-house MATLAB codes. Results: RCT measurement showed an overall positional accuracy of 0.265 mm (range 0.223 mm–0.343 mm). Gamma index analysis across fractions exhibited close agreement between LGP and film

Radiation dose evaluation of dental cone beam computed tomography using an anthropomorphic adult head phantom

Science.gov (United States)

Wu, Jay; Shih, Cheng-Ting; Ho, Chang-hung; Liu, Yan-Lin; Chang, Yuan-Jen; Min Chao, Max; Hsu, Jui-Ting

2014-11-01

Dental cone beam computed tomography (CBCT) provides high-resolution tomographic images and has been gradually used in clinical practice. Thus, it is important to examine the amount of radiation dose resulting from dental CBCT examinations. In this study, we developed an in-house anthropomorphic adult head phantom to evaluate the level of effective dose. The anthropomorphic phantom was made of acrylic and filled with plaster to replace the bony tissue. The contour of the head was extracted from a set of adult computed tomography (CT) images. Different combinations of the scanning parameters of CBCT were applied. Thermoluminescent dosimeters (TLDs) were used to measure the absorbed doses at 19 locations in the head and neck regions. The effective doses measured using the proposed phantom at 65, 75, and 85 kVp in the D-mode were 72.23, 100.31, and 134.29 μSv, respectively. In the I-mode, the effective doses were 108.24, 190.99, and 246.48 μSv, respectively. The maximum percent error between the doses measured by the proposed phantom and the Rando phantom was l4.90%. Therefore, the proposed anthropomorphic adult head phantom is applicable for assessing the radiation dose resulting from clinical dental CBCT.

Acute renal failure following contrast injection for head computerized tomography in two patients with diabetic nephropathy

International Nuclear Information System (INIS)

Matsunaga, Hiroshi; Sando, Hiroyuki; Nunokawa, Tomoo; Murakami, Tooru; Miyakawa, Yuzo

1981-01-01

Two cases of diabetes mellitus with renal and retinal involvement developed acute renal failure after undergoing head computerized tomography. The first case was a 62-year-old male who had been diagnosed as having diabetes 25 years before. He had diabetic retinopathy of Scott IIIb. Before head computerized tomography, the serum BUN was 37 mg/dl, and creatinine was 4.1 mg/dl. Oliguria began immediately after the scanning and confinued for 48 hr. The serum levels of BUN and creatinine rose to 106 and 7.7 mg/dl, respectively. Case 2 was a 49-year-old male who had been diagnosed as having diabetes 15 years before. He showed Scott IIb and IV retinopathy. The BUN and creatinine levels in the serum were 32 and 2.3 mg/dl, respectively. After receiving head computerized tomography, he developed oliguria and remained oliguric for 48 hr. During that period, the serum levels of BUN and creatinin were elevated to 112 and 7.5 mg/dl, respectively. Fortunately, both of these patients recovered from the oliguria without resorting to hemodialysis. The iodine contrast medium routinely used for contrast enhancement in the head computerized tomography was implicated in the acute renal failure of these patients. Only elevn cases have so far been reported in the literature who developed acute renal failure following computerized tomography. In view of the three or four times greater dosis of iodine contrast medium employed in computerized tomography compared to intravenous pyelography, the acute incidence of such complications might be much higher. Among the thirteen cases including the two reported here, as many as eight were diabetic. It is well recongnized that the incidence of acute renal failure after intravenous pyelography is particularly high in cases of diabetic nephropathy. (author)

Induction and separation of motion artifacts in EEG data using a mobile phantom head device.

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Oliveira, Anderson S; Schlink, Bryan R; Hairston, W David; König, Peter; Ferris, Daniel P

2016-06-01

Electroencephalography (EEG) can assess brain activity during whole-body motion in humans but head motion can induce artifacts that obfuscate electrocortical signals. Definitive solutions for removing motion artifact from EEG have yet to be found, so creating methods to assess signal processing routines for removing motion artifact are needed. We present a novel method for investigating the influence of head motion on EEG recordings as well as for assessing the efficacy of signal processing approaches intended to remove motion artifact. We used a phantom head device to mimic electrical properties of the human head with three controlled dipolar sources of electrical activity embedded in the phantom. We induced sinusoidal vertical motions on the phantom head using a custom-built platform and recorded EEG signals with three different acquisition systems while the head was both stationary and in varied motion conditions. Recordings showed up to 80% reductions in signal-to-noise ratio (SNR) and up to 3600% increases in the power spectrum as a function of motion amplitude and frequency. Independent component analysis (ICA) successfully isolated the three dipolar sources across all conditions and systems. There was a high correlation (r > 0.85) and marginal increase in the independent components' (ICs) power spectrum (∼15%) when comparing stationary and motion parameters. The SNR of the IC activation was 400%-700% higher in comparison to the channel data SNR, attenuating the effects of motion on SNR. Our results suggest that the phantom head and motion platform can be used to assess motion artifact removal algorithms and compare different EEG systems for motion artifact sensitivity. In addition, ICA is effective in isolating target electrocortical events and marginally improving SNR in relation to stationary recordings.

Development and application of a pediatric head phantom for dosimetry in computed tomography

International Nuclear Information System (INIS)

Martins, Elaine Wirney

2016-01-01

To determine the exposure levels and the absorbed dose in patients undergoing CT scans, is necessary to calculate the CT dose index in measurements with a PMMA or water phantom. The phantom must be enough to simulate the attenuation and scattering characteristics of a human body or parts in a radiation field. The CT specific quantities : CT air kerma index (Ca,100) , weighted CT air kerma index (CW ), a total volume CT air kerma index (Cvol) and the CT air kerma-length product (PKL) must be determined and compared to literature reference levels. In this work a head pediatric phantom was developed, considering that the Brazilian published Diagnostic Reference Levels (DRL) are based on adult phantom measurements. This developed phantom shows a construction innovation using materials to simulate the skullcap, cortical bone (aluminum) and cancellous bone (PVC), and it was filled with distilled water. The phantom dimension follows the recommendations of the World Health Organization and the International Commission on Radiation Units for children from 0 to 5 years old head size: diameter of 160 mm and height of 155 mm. The skullcap has 4 mm of thickness and 111.9 mm of internal diameter. In order to evaluate its behavior, tests were carried out in calibration laboratories and in clinical beams. The results showed attenuation up to 23% when different materials are used as skullcap, demonstrating that the DRLs adopted could be overestimating the dose received by pediatric patients. It is observed that the dose received by CT skull scans presents different distribution, due to the skullcap partially attenuation and/or backscattering which is not considered when the PMMA phantom is used.

Development of a phantom for quality control of radiosurgery

International Nuclear Information System (INIS)

Scheidegger Soboll, D.; Reuters Schelin, H.

2008-01-01

The aim of this work was to build a phantom for quality control of stereotactic radiosurgery on linear accelerators. The outward appearance is a translucent human head filled with water and enclosing an insert with test objects of known shapes. The phantom was submitted to computerized tomography, magnetic resonance imaging and angiography exams, in order to perform a radiosurgery planning. Contours of the internal structures on the therapy planning system were drawn over the MRI images. Through the image fusion of CT and MRI, the contour data was transferred to CT images. Stereotactic registration of CT and angiography was made. One isocenter treatment was created, and using the stereotactic coordinates given by the therapy planning system, the phantom was placed on a linac. X-ray images were performed in order to verify the final positioning of the planned isocenter. In the whole process the phantom showed usefulness and adequacy for the positioning quality control of stereotactic radiosurgery with linacs, according to the main documents concerning the issue. (author)

An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy

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Gallas, Raya R.; Huenemohr, Nora; Runz, Armin; Niebuhr, Nina I.; Greilich, Steffen [German Cancer Research Center (DKFZ), Heidelberg (Germany). Div. of Medical Physics in Radiation Oncology; National Center for Radiation Research in Oncology, Heidelberg (Germany). Heidelberg Institute of Radiation Oncology (HIRO); Jaekel, Oliver [German Cancer Research Center (DKFZ), Heidelberg (Germany). Div. of Medical Physics in Radiation Oncology; National Center for Radiation Research in Oncology, Heidelberg (Germany). Heidelberg Institute of Radiation Oncology (HIRO); Heidelberg University Hospital (Germany). Dept. of Radiation Oncology; Heidelberg Ion-Beam Therapy Center (HIT), Heidelberg (Germany)

2015-07-01

With the increasing complexity of external beam therapy ''end-to-end'' tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification.

An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy

International Nuclear Information System (INIS)

Gallas, Raya R.; Huenemohr, Nora; Runz, Armin; Niebuhr, Nina I.; Greilich, Steffen; Jaekel, Oliver

2015-01-01

With the increasing complexity of external beam therapy ''end-to-end'' tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification.

An anthropomorphic multimodality (CT/MRI) head phantom prototype for end-to-end tests in ion radiotherapy.

Science.gov (United States)

Gallas, Raya R; Hünemohr, Nora; Runz, Armin; Niebuhr, Nina I; Jäkel, Oliver; Greilich, Steffen

2015-12-01

With the increasing complexity of external beam therapy "end-to-end" tests are intended to cover every step from therapy planning through to follow-up in order to fulfill the higher demands on quality assurance. As magnetic resonance imaging (MRI) has become an important part of the treatment process, established phantoms such as the Alderson head cannot fully be used for those tests and novel phantoms have to be developed. Here, we present a feasibility study of a customizable multimodality head phantom. It is initially intended for ion radiotherapy but may also be used in photon therapy. As basis for the anthropomorphic head shape we have used a set of patient computed tomography (CT) images. The phantom recipient consisting of epoxy resin was produced by using a 3D printer. It includes a nasal air cavity, a cranial bone surrogate (based on dipotassium phosphate), a brain surrogate (based on agarose gel), and a surrogate for cerebrospinal fluid (based on distilled water). Furthermore, a volume filled with normoxic dosimetric gel mimicked a tumor. The entire workflow of a proton therapy could be successfully applied to the phantom. CT measurements revealed CT numbers agreeing with reference values for all surrogates in the range from 2 HU to 978 HU (120 kV). MRI showed the desired contrasts between the different phantom materials especially in T2-weighted images (except for the bone surrogate). T2-weighted readout of the polymerization gel dosimeter allowed approximate range verification. Copyright © 2015. Published by Elsevier GmbH.

A study of magnification effect to precision of computerized diameter measurement of a 3-mm vessel phantom in cineangiograms

International Nuclear Information System (INIS)

Yanagihara, Yoshio; Sugahara, Tetsuo; Sugimoto, Naozou; Fukunishi, Yasunobu.

1994-01-01

To estimate influence of magnification on digitizing to Precision of computerized measurement of coronary vessel diameter, the two measurement methods, i.e., a combined filter and Entropy filter, were applied to magnified images (x1-x6) of cineangiograms radiographed for a 3-mm vessel phantom. In conclusion, the desirable precision in clinical use, we thought, was obtainable at the magnification of x3 to x4. (author)

Computed tomography scan optimization using head phantom and radiochromic films

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Fernandes, Lorena C.; Santana, P.C.; Velasquez, Carlos E.; Mourao, Arnaldo P., E-mail: lorena.cfernandes@hotmail.com, E-mail: carlosvelcab@hotmail.com, E-mail: pridili@gmail.com, E-mail: apmourao@gmail.com [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear; Centro de Imagem Molecular do INCT-Medicina Molecular (CIMol/UFMG) Belo Horizonte (Brazil); Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Belo Horizonte (Brazil)

2017-11-01

The research and development in technology applied to computed tomography has been improve in the image quality, resulting in the best identification of diseases, and therefore an increase in the number of exams, among them the head exams can be highlighted. In order to promote a radioprotection and reduction on the dose of the general public some international agencies have stipulated dose limits to be followed and the implementation of the principles of ALARA in all establishments that use ionizing radiation. One of these principles is the optimization that should be treated with substantial attention, because the reduction of radiation doses can be feasible as long as it does not compromise the tomographic images; such practice is difficult to perform due to the lack of proper guidance. In optimization of the CT exams, not only the lowest dose is evaluated to obtain diagnostic image, but also should be knowledge the dose distribution throughout the scanned area. In this work were used a cylindrical head phantom of PMMA, a GE Discovery CT scan with 64 channels, and radiochromic films. The films were positioned in the phantom in their central region for the dose evaluation using the automatic control for the voltages of 80, 100 and 120 kV. The images were acquired from the scan of the phantom and the film readings were obtained through digital images. The results show an evaluation of the longitudinal kerma profiles, dose delivered, and the image noise was also observed using the central slice images. (author)

Computed tomography scan optimization using head phantom and radiochromic films

International Nuclear Information System (INIS)

Fernandes, Lorena C.; Santana, P.C.; Velasquez, Carlos E.; Mourao, Arnaldo P.

2017-01-01

The research and development in technology applied to computed tomography has been improve in the image quality, resulting in the best identification of diseases, and therefore an increase in the number of exams, among them the head exams can be highlighted. In order to promote a radioprotection and reduction on the dose of the general public some international agencies have stipulated dose limits to be followed and the implementation of the principles of ALARA in all establishments that use ionizing radiation. One of these principles is the optimization that should be treated with substantial attention, because the reduction of radiation doses can be feasible as long as it does not compromise the tomographic images; such practice is difficult to perform due to the lack of proper guidance. In optimization of the CT exams, not only the lowest dose is evaluated to obtain diagnostic image, but also should be knowledge the dose distribution throughout the scanned area. In this work were used a cylindrical head phantom of PMMA, a GE Discovery CT scan with 64 channels, and radiochromic films. The films were positioned in the phantom in their central region for the dose evaluation using the automatic control for the voltages of 80, 100 and 120 kV. The images were acquired from the scan of the phantom and the film readings were obtained through digital images. The results show an evaluation of the longitudinal kerma profiles, dose delivered, and the image noise was also observed using the central slice images. (author)

Prognosis of the computerized tomography in the severe head injury

International Nuclear Information System (INIS)

Garcia-Nieto, J.J.; Lorenzo Dominguez, M.T.; Martin Sanchez, M.J.; Sanchez Gonzalez, E.

1991-01-01

A prospective study is made with sixty five people affected of severe head injury, that is to say, with eight or less points in the Glasgow Coma Scale (GCS), when they get to the hospital. They are studied by computerized tomography at the income, but also, three and seven days after arriving. In this way, we appraise the type of the lesion the intensity and the possible effect-wass, considering in the last case, three features: a) ventricular collapse; b) the mean line structure s shift; c) perimesencefalic cisterns affectation. The findings of this study, are parametized and we were able to introduce them into a computer, getting. The relations between these findings ands the end-results. These last ones appraised throungh the Glasgow Outcome Scale (GOS). We could confirm, that certain findings in the computerized tomography have and unavoidable prognosis, where as others have a better prognosis. (Author)

Advances in development of young-pediatric anthropometric and anthropomorphic head and neck phantoms for dosimetry

International Nuclear Information System (INIS)

Thompson, Larissa; Campos, Tarcisio P.R.

2005-01-01

The neck malign cancer in pediatric population differs significantly than adult cancer. The pediatric primary malign tumors result in the neck and head fence 5% . The malign cervical tumors, generally, are rabdomyossarcoms and lymphomas. The least frequent malign cancer includes metastasis, scammous cells and thyroid cancer. The larynx cancer treatment is surgery, preferentially. However, lesions with little infiltration, that do not compromise the vocals cords mobile, do not infiltrate cartilage, and do not compromise neither the anterior comissure neither the arytenoid, can be controlled with exclusive radiotherapy. The traditional dose for sub-clinical disease in larynx cancer, neck and head region, has been 50 to 60 Gy to standard fraction of 2 Gy/day, five times for week. When the treatment is consummated with exclusive radiotherapy in primary tumor. The dose must be higher, diversifying from 66 (for small tumors T1) to 70 Gy (for higher tumors, that T2 or T3). Phantoms are simulators utilized for dose prediction in patient simulating radiation interactions with matter. Also it is applied for radio diagnosis equipment calibration and quality control of medical image. Many kind of phantoms are developed, handmade and commercialized, with matters and forms most varied, holding distinct purpose, in senses of establishing double check parameters for reducing planning and calibration errors. This study addresses the development of a object for simulating young-pediatric anthropometric and anthropomorphic head and neck, called phantom, for dosimetric studies. The methodology will be based on the preparation of a phantom respecting the anatomic standards and its tissue equivalent composition. The hope is that phantom can be used in the scientific researches of radiation protocols applied to young-pediatric patient. (author)

CT head-scan dosimetry in an anthropomorphic phantom and associated measurement of ACR accreditation-phantom imaging metrics under clinically representative scan conditions

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Brunner, Claudia C.; Stern, Stanley H.; Chakrabarti, Kish [U.S. Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, Maryland 20993 (United States); Minniti, Ronaldo [National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899 (United States); Parry, Marie I. [Walter Reed National Military Medical Center, 8901 Rockville Pike, Bethesda, Maryland 20889 (United States); Skopec, Marlene [National Institutes of Health, 9000 Rockville Pike, Bethesda, Maryland 20892 (United States)

2013-08-15

Purpose: To measure radiation absorbed dose and its distribution in an anthropomorphic head phantom under clinically representative scan conditions in three widely used computed tomography (CT) scanners, and to relate those dose values to metrics such as high-contrast resolution, noise, and contrast-to-noise ratio (CNR) in the American College of Radiology CT accreditation phantom.Methods: By inserting optically stimulated luminescence dosimeters (OSLDs) in the head of an anthropomorphic phantom specially developed for CT dosimetry (University of Florida, Gainesville), we measured dose with three commonly used scanners (GE Discovery CT750 HD, Siemens Definition, Philips Brilliance 64) at two different clinical sites (Walter Reed National Military Medical Center, National Institutes of Health). The scanners were set to operate with the same data-acquisition and image-reconstruction protocols as used clinically for typical head scans, respective of the practices of each facility for each scanner. We also analyzed images of the ACR CT accreditation phantom with the corresponding protocols. While the Siemens Definition and the Philips Brilliance protocols utilized only conventional, filtered back-projection (FBP) image-reconstruction methods, the GE Discovery also employed its particular version of an adaptive statistical iterative reconstruction (ASIR) algorithm that can be blended in desired proportions with the FBP algorithm. We did an objective image-metrics analysis evaluating the modulation transfer function (MTF), noise power spectrum (NPS), and CNR for images reconstructed with FBP. For images reconstructed with ASIR, we only analyzed the CNR, since MTF and NPS results are expected to depend on the object for iterative reconstruction algorithms.Results: The OSLD measurements showed that the Siemens Definition and the Philips Brilliance scanners (located at two different clinical facilities) yield average absorbed doses in tissue of 42.6 and 43.1 m

Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

Science.gov (United States)

Anderson, Danielle; Siegbahn, E. Albert; Fallone, B. Gino; Serduc, Raphael; Warkentin, Brad

2012-05-01

This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm2 microbeam array in each phantom, as well as a 16 × 16 mm2 array in the 8 cm cat head, and a 32 × 32 mm2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2-49 (mouse) and 2-46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2-87% and 33-96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this study

Evaluation of dose-volume metrics for microbeam radiation therapy dose distributions in head phantoms of various sizes using Monte Carlo simulations

International Nuclear Information System (INIS)

Anderson, Danielle; Fallone, B Gino; Warkentin, Brad; Siegbahn, E Albert; Serduc, Raphael

2012-01-01

This work evaluates four dose-volume metrics applied to microbeam radiation therapy (MRT) using simulated dosimetric data as input. We seek to improve upon the most frequently used MRT metric, the peak-to-valley dose ratio (PVDR), by analyzing MRT dose distributions from a more volumetric perspective. Monte Carlo simulations were used to calculate dose distributions in three cubic head phantoms: a 2 cm mouse head, an 8 cm cat head and a 16 cm dog head. The dose distribution was calculated for a 4 × 4 mm 2 microbeam array in each phantom, as well as a 16 × 16 mm 2 array in the 8 cm cat head, and a 32 × 32 mm 2 array in the 16 cm dog head. Microbeam widths of 25, 50 and 75 µm and center-to-center spacings of 100, 200 and 400 µm were considered. The metrics calculated for each simulation were the conventional PVDR, the peak-to-mean valley dose ratio (PMVDR), the mean dose and the percentage volume below a threshold dose. The PVDR ranged between 3 and 230 for the 2 cm mouse phantom, and between 2 and 186 for the 16 cm dog phantom depending on geometry. The corresponding ranges for the PMVDR were much smaller, being 2–49 (mouse) and 2–46 (dog), and showed a slightly weaker dependence on phantom size and array size. The ratio of the PMVDR to the PVDR varied from 0.21 to 0.79 for the different collimation configurations, indicating a difference between the geometric dependence on outcome that would be predicted by these two metrics. For unidirectional irradiation, the mean lesion dose was 102%, 79% and 42% of the mean skin dose for the 2 cm mouse, 8 cm cat and 16 cm dog head phantoms, respectively. However, the mean lesion dose recovered to 83% of the mean skin dose in the 16 cm dog phantom in intersecting cross-firing regions. The percentage volume below a 10% dose threshold was highly dependent on geometry, with ranges for the different collimation configurations of 2–87% and 33–96% for the 2 cm mouse and 16 cm dog heads, respectively. The results of this

Cost-effective pediatric head and body phantoms for computed tomography dosimetry and its evaluation using pencil ion chamber and CT dose profiler

Directory of Open Access Journals (Sweden)

A Saravanakumar

2015-01-01

Full Text Available In the present work, a pediatric head and body phantom was fabricated using polymethyl methacrylate (PMMA at a low cost when compared to commercially available phantoms for the purpose of computed tomography (CT dosimetry. The dimensions of head and body phantoms were 10 cm diameter, 15 cm length and 16 cm diameter, 15 cm length, respectively. The dose from a 128-slice CT machine received by the head and body phantom at the center and periphery were measured using a 100 mm pencil ion chamber and 150 mm CT dose profiler (CTDP. Using these values, the weighted computed tomography dose index (CTDIw and in turn the volumetric CTDI (CTDIv were calculated for various combinations of tube voltage and current-time product. A similar study was carried out using standard calibrated phantom and the results have been compared with the fabricated ones to ascertain that the performance of the latter is equivalent to that of the former. Finally, CTDIv measured using fabricated and standard phantoms were compared with respective values displayed on the console. The difference between the values was well within the limits specified by Atomic Energy Regulatory Board (AERB, India. These results indicate that the cost-effective pediatric phantom can be employed for CT dosimetry.

Prediction of traumatic avascular necrosis of the femoral head by single photon emission computerized tomography and computerized tomography: an experimental study in dogs

Directory of Open Access Journals (Sweden)

SHEN Feng

2012-02-01

Full Text Available 【Abstract】 Objective: To evaluate the femoral head perfusion and to predict the traumatic avascular necrosis (AVN of the femoral head by single photon emission computerized tomography and computerized tomography (SPECT/CT. Methods: Totally 18 adult beagle dogs were divided randomly into three equal-sized (n=6 groups. Subsequently different degrees of ischemia model were developed by destroying blood vessels of the femoral head. The left hip received sham operation as normal control and the right hip underwent blood interruption. In Group A, the ligamentum teres was cut off. In Group B, the marrow cavity of the right femoral neck was destroyed while in Group C, the soft tissues at the base of the femoral neck were stripped in addition to the resection of the ligamentum teres and destruction of the marrow cavity. Three hours after surgery, SPECT/CT was performed. Laser Doppler Flowmetry (LDF measurements were also obtained at three different time points (before operation, immediately and three hours after operation in order to assess the change process of blood supply to the femoral head. Results: SPECT/CT showed no significant difference in the radionuclide uptake between the right and left femoral heads in Group A (t=-0.09, P=0.94 and Group B (t= 0.52, P=0.62. However, in Group C, it was 261±62 for the right femoral head, only 12% of that in the left femoral head. LDF measurements indicated that the femoral head perfusion was decreased from (45.0±3.3 PU to (39.1±3.7 PU in Group A, from (44.0±2.7 PU to (34.3±2.6 PU in Group B, and from (47.3±2.1 PU to (4.96±0.6 PU in Group C immediately after operation. However, the perfusion was restored and returned to normal values three hours after operation except in Group C. Conclusion: SPECT/CT could assess the perfusion of the femoral head semiquantitatively, which might be useful in predicting the development of traumatic AVN. Key words: Femur head necrosis; Femoral head; Tomography, emission

Linear versus circular polarization of head coils - comparison on phantom and in the clinic

International Nuclear Information System (INIS)

Schratter, M.; Kramer, J.; Prayer, L.; Wimberger, D.; Imhof, H.; Schmid, W.

1990-01-01

Two different head coils - one with linear polarization and the other with circular polarization - were compared under the same measurement conditions. Comparison was done on a phantom with waterfilled and gadolinium-filled pin-holes, as well as on anatomical MR images of 23 volunteers. In three volunteers the whole brain was examined while, in the remaining 20 volunteers the sella region or cerebellopontine angleregion was examined. Criteria for comparison were signal-to-noise ratio, background noise, and detail resolution (phantom), as well as subjective criteria - image sharpness, anatomical, contrast, and recognition of anatomical details -, evaluated on anatomical MR images by four radiologists independently of each other. The results show a significant improvement of signal-to-noise ratio, lower background noise and therefore marked improvement of images harpness, and moderate improvement in the recognition of anatomical details using the circular polarized head coil; as for as detail resolution and anatomical contrast were concerned, however, no significant difference was seen between the two coils. Major advantages of the circular, polarized head coil in clinical application are shorter measurement times (reduced number of acquisitions), as well as thinner slices without loss of signal-to-noise ratio. (orig.) [de

Tissue quantification for development of pediatric phantom

International Nuclear Information System (INIS)

Alves, A.F.F.; Miranda, J.R.A.; Pina, D.R.

2013-01-01

The optimization of the risk- benefit ratio is a major concern in the pediatric radiology, due to the greater vulnerability of children to the late somatic effects and genetic effects of exposure to radiation compared to adults. In Brazil, it is estimated that the causes of death from head trauma are 18 % for the age group between 1-5 years and the radiograph is the primary diagnostic test for the detection of skull fracture . Knowing that the image quality is essential to ensure the identification of structures anatomical and minimizing errors diagnostic interpretation, this paper proposed the development and construction of homogeneous phantoms skull, for the age group 1-5 years. The construction of the phantoms homogeneous was performed using the classification and quantification of tissue present in the skull of pediatric patients. In this procedure computational algorithms were used, using Matlab, to quantify distinct biological tissues present in the anatomical regions studied , using pictures retrospective CT scans. Preliminary data obtained from measurements show that between the ages of 1-5 years, assuming an average anteroposterior diameter of the pediatric skull region of the 145.73 ± 2.97 mm, can be represented by 92.34 mm ± 5.22 of lucite and 1.75 ± 0:21 mm of aluminum plates of a provision of PEP (Pacient equivalent phantom). After its construction, the phantoms will be used for image and dose optimization in pediatric protocols process to examinations of computerized radiography

Generation of a head phantom according to the 95. percentile Chinese population data for evaluating the specific absorption rate by wireless communication devices

International Nuclear Information System (INIS)

Ma, Yu; Wang, Yuduo; Shao, Qing; Wu, Tongning; Li, Congsheng

2014-01-01

A Chinese head phantom (CHP) is constructed for evaluating the specific absorption rate (SAR) by the wireless transceivers. The dimensions of the head phantom are within 4 % difference compared with the 95. percentile data from the China's standard. The shell's thickness and the configuration of the pinna are the same as those of the specific anthropomorphic mannequin (SAM). Three computable models for the mobile phones are generated and used in the SAR simulations with the SAM and the CHP. The results show that the simulated SAR from the SAM head is similar. Its morphological reason has been analysed. The authors discuss the conservativeness of the two head phantoms as well. The CHP can be used in the inter-laboratory evaluation for the SAR uncertainty. It can also provide the information for the SAR variability due to physical difference, which will benefit the maintenance and the harmonisation of the standards. (authors)

Validation of a cylindrical phantom for verification of radiotherapy treatments in head and neck with special techniques

International Nuclear Information System (INIS)

Vargas, Nicolas M.; Garcia, Marcia; Piriz, Gustavo; Perez, Niurka

2011-01-01

Verification of radiotherapy treatments in head and neck requires, among other things, small volume chambers and a phantom to reproduce the geometry and density of the anatomical structure. New documents from the ICRU (International Commission on Radiation Units and Measurements), Report 83, established the need for quality control in radiotherapy with special techniques such as IMRT (intensity-modulated radiation therapy). In this study, we built a cylindrical acrylic phantom with standing water, containing seven measuring points in the transverse plane and free location (0-20 cm) in the longitudinal plane. These points of measurement are constituted by cavities for the accommodation of the ionization chamber of 7 mm of mayor diameter (semi flex, pinpoint with build cup). The results of the phantom validation yielded percentage differences less than 1% in fixed beams and less than 2.5% in arc therapy for TPS Eclipse calculation. The preparation of this phantom, particularly made to verify the head and neck treatments, was simple and reliable for checking the dose in radiotherapy with fixed beams and/or special techniques such as arc therapy or IMRT, so that will be sent to various radiotherapy centers in the country for dosimetric verification in such treatments. (author)

Validation of a cylindrical phantom for verification of radiotherapy treatments in head and neck with special techniques

Energy Technology Data Exchange (ETDEWEB)

Vargas, Nicolas M.; Garcia, Marcia, E-mail: nimoralesv@gmail.com [Universidad de La Frontera, Temuco (Chile). Dept. de Ciencias Fisicas; Piriz, Gustavo [Instituto Nacional del Cancer, Santiago (Chile). Fisica Medica; Perez, Niurka [Instituto de Salud Publica, Santiago (Chile). QA Radioterapia. Inst. de Salud Publica

2011-07-01

Verification of radiotherapy treatments in head and neck requires, among other things, small volume chambers and a phantom to reproduce the geometry and density of the anatomical structure. New documents from the ICRU (International Commission on Radiation Units and Measurements), Report 83, established the need for quality control in radiotherapy with special techniques such as IMRT (intensity-modulated radiation therapy). In this study, we built a cylindrical acrylic phantom with standing water, containing seven measuring points in the transverse plane and free location (0-20 cm) in the longitudinal plane. These points of measurement are constituted by cavities for the accommodation of the ionization chamber of 7 mm of mayor diameter (semi flex, pinpoint with build cup). The results of the phantom validation yielded percentage differences less than 1% in fixed beams and less than 2.5% in arc therapy for TPS Eclipse calculation. The preparation of this phantom, particularly made to verify the head and neck treatments, was simple and reliable for checking the dose in radiotherapy with fixed beams and/or special techniques such as arc therapy or IMRT, so that will be sent to various radiotherapy centers in the country for dosimetric verification in such treatments. (author)

Comparison of radiation doses between newborns and 6-y-old children undergoing head, chest and abdominal CT examinations-A phantom study

International Nuclear Information System (INIS)

Sugimoto, N.; Aoyama, T.; Koyama, S.; Yamauchi-Kawaura, C.; Fujii, K.

2013-01-01

Radiation doses in paediatric computed tomography (CT) were investigated for various types of recent CT scanners with newborn and 6-y-old phantoms in which silicon-photodiode dosemeters were implanted at various organ positions. In the head, chest and abdominal CT for the newborn phantom, doses for organs within the scan region were 21-40, 3-8 and 3-12 mGy, respectively. The corresponding doses for the child phantom were 20-37, 2-11 and 4-17 mGy, respectively. In the head, chest and abdominal CT, the effective doses were respectively 2.1-3.3, 2.0-6.0 and 2.2-10.0 mSv for the newborn, and 1.0-2.0, 1.2-6.6 and 2.9-11.8 mSv for the child. Radiation doses for the newborn were at the same levels as those for the child, excepting effective doses in head CT for the newborn, which were 1.8 times higher than those for the child. (authors)

Measurement of hard tissue density of head phantom based on the HU by using CBCT

International Nuclear Information System (INIS)

Kim, Moon Sun; Kang, Dong Wan; Kim, Jae Duk

2009-01-01

The purpose of this study was to determine a conversion coefficient for Hounsfield Units(HU) to material density (g cm -3 ) obtained from cone-beam computed tomography (CBMercuRay TM ) data and to measure the hard tissue density based on the Hounsfield scale on dental head phantom. CT Scanner Phantom (AAPM) equipped with CT Number Insert consists of five cylindrical pins of materials with different densities and teflon ring was scanned by using the CBMercuRay TM (Hitachi, Tokyo, Japan) volume scanner. The raw data were converted into DICOM format and the HU of different areas of CT number insert measured by using CBWorks TM . Linear regression analysis and Student t-test were performed statistically. There was no significant difference (P>0.54) between real densities and measured densities. A linear regression was performed using the density, ρ (g cm -3 ), as the dependent variable in terms of the HU (H). The regression equation obtained was ρ=0.00072 H-0.01588 with an R2 value of 0.9968. Density values based on the Hounsfield scale was 1697.1 ± 24.9 HU in cortical bone, 526.5 ± 44.4 HU in trabecular bone, 2639.1 ± 48.7 HU in enamel, 1246.1 ± 39.4 HU in dentin of dental head phantom. CBCT provides an effective option for determination of material density expressed as Hounsfield Units.

Radiological response and dosimetry in physical phantom of head and neck for 3D conformational radiotherapy

International Nuclear Information System (INIS)

Thompson, Larissa

2013-01-01

Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film

Development of a unique phantom to assess dose error of metal artifact in head and neck cancer

Energy Technology Data Exchange (ETDEWEB)

Lee, Min Young; Kang, Sang Won; Suh, Tae Suk [Dept. of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of); Lee, Jeong Woo [Dept. of Radiation Oncology, Konkuk University Medical Center, Seoul (Korea, Republic of); Park, Ji Yeon [Dept. of Pediatrics and Molecular Imaging Program at Stanford, Stanford University, Stanford (United States)

2016-04-15

The artifacts not only blur the CT images and lead to inaccuracies in diagnosis, but also make the delineation of anatomical structures intractable, which is important in image-guided intervention procedures. These artifacts obscure the underlying anatomy, leading to uncertainty in the delineation of the target volumes and compromising the integrity of the density representation that is crucial for accurate dose calculation. Because head and neck cancer patients tend to be over the age of 50 years, they constitute a group likely to have dental prostheses. This kind of side effects considerably disturbs the therapeutic procedure. Radiation scatter from high atomic number (Z) materials is established to cause both soft tissue and bony complications in the oral cavity, making scattered radiation an important factor in head and neck region radiotherapy planning. In this study, we carried out theoretical analysis of the metal artifact, that is, streak artifact and dark artifact, and also critical analysis of dosimetric effect which cause by dental implants in CT images of head and neck cancer patients with the genuine teeth and implants inserted humanoid phantom. The phantom provides a unique and useful tool in head and neck dosimetry research. It can be used in the development of new imaging instrumentation, image acquisition strategies, and image processing and reconstruction methods.

A virtual phantom library for the quantification of deformable image registration uncertainties in patients with cancers of the head and neck.

Science.gov (United States)

Pukala, Jason; Meeks, Sanford L; Staton, Robert J; Bova, Frank J; Mañon, Rafael R; Langen, Katja M

2013-11-01

Deformable image registration (DIR) is being used increasingly in various clinical applications. However, the underlying uncertainties of DIR are not well-understood and a comprehensive methodology has not been developed for assessing a range of interfraction anatomic changes during head and neck cancer radiotherapy. This study describes the development of a library of clinically relevant virtual phantoms for the purpose of aiding clinicians in the QA of DIR software. These phantoms will also be available to the community for the independent study and comparison of other DIR algorithms and processes. Each phantom was derived from a pair of kVCT volumetric image sets. The first images were acquired of head and neck cancer patients prior to the start-of-treatment and the second were acquired near the end-of-treatment. A research algorithm was used to autosegment and deform the start-of-treatment (SOT) images according to a biomechanical model. This algorithm allowed the user to adjust the head position, mandible position, and weight loss in the neck region of the SOT images to resemble the end-of-treatment (EOT) images. A human-guided thin-plate splines algorithm was then used to iteratively apply further deformations to the images with the objective of matching the EOT anatomy as closely as possible. The deformations from each algorithm were combined into a single deformation vector field (DVF) and a simulated end-of-treatment (SEOT) image dataset was generated from that DVF. Artificial noise was added to the SEOT images and these images, along with the original SOT images, created a virtual phantom where the underlying "ground-truth" DVF is known. Images from ten patients were deformed in this fashion to create ten clinically relevant virtual phantoms. The virtual phantoms were evaluated to identify unrealistic DVFs using the normalized cross correlation (NCC) and the determinant of the Jacobian matrix. A commercial deformation algorithm was applied to the virtual

Measurement of radiation dose to ovaries from CT of the head and trunk

Energy Technology Data Exchange (ETDEWEB)

Al-Habdhan, M.A.M.; Kinsara, A.R. [King Abdul Aziz Univ., Nuclear Engineering Dept., Jeddah (Saudi Arabia)

2001-07-01

With the rise in concern about doses received by patients over recent years, there has been a growing requirement for information on typical doses and the range of dose received during Computerized Tomography (CT). This study was performed for the assessment of radiation dose to the ovaries from various CT protocols for head and trunk imaging. Thermo luminescent dosimeters (TLD) were used for the dosimetry measurement in an anthropomorphic Rando Alderson phantom. The wanted (obligatory) and unwanted (non-useful) radiation doses delivered to the ovaries during CT examinations of head, facial bone, orbits, abdomen, chest, pelvis, neck, nasopharynx, cervical spine, lumber spine and sacroiliac joint were assessed. The results are compared with the corresponding values published in the literature. A comparison of the received dose from CT examinations and general radiography examinations by the ovaries was made. It is found that relatively high doses of unwanted radiation are delivered with computerized tomography. (author)

Effect of The Measuring Parameters on The Reconstructed Images by Computerized Tomography

International Nuclear Information System (INIS)

Ali, A.M.; Ali, A.M.; Megahid, R.M.

2011-01-01

In this paper, the potential of computerized tomography by neutrons and gamma rays as a main precise technique for nondestructive assay of materials and components of prime importance in nuclear and general industries are given and discussed. Both Fast Fourier Transform (FFT) and convolution techniques are introduced. Shepp and Logan human head phantom is used for theoretical testing and studying the effect of translation value for both techniques. Moreover, the effect of the projection number discussed. Comparison between the two reconstruction techniques wasper formed for the examined object. In addition, some of the experimentally scanned images using slit beam of gamma rays emitt ed from the ETRR- 1 reactor are presented and discussed.

A deformable head and neck phantom with in-vivo dosimetry for adaptive radiotherapy quality assurance

Energy Technology Data Exchange (ETDEWEB)

Graves, Yan Jiang [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 and Department of Physics, University of California San Diego, La Jolla, California 92093 (United States); Smith, Arthur-Allen; Mcilvena, David; Manilay, Zherrina; Lai, Yuet Kong [Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California 92093 (United States); Rice, Roger; Mell, Loren; Cerviño, Laura, E-mail: lcervino@ucsd.edu, E-mail: steve.jiang@utsouthwestern.edu [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 (United States); Jia, Xun; Jiang, Steve B., E-mail: lcervino@ucsd.edu, E-mail: steve.jiang@utsouthwestern.edu [Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843 and Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75235 (United States)

2015-04-15

Purpose: Patients’ interfractional anatomic changes can compromise the initial treatment plan quality. To overcome this issue, adaptive radiotherapy (ART) has been introduced. Deformable image registration (DIR) is an important tool for ART and several deformable phantoms have been built to evaluate the algorithms’ accuracy. However, there is a lack of deformable phantoms that can also provide dosimetric information to verify the accuracy of the whole ART process. The goal of this work is to design and construct a deformable head and neck (HN) ART quality assurance (QA) phantom with in vivo dosimetry. Methods: An axial slice of a HN patient is taken as a model for the phantom construction. Six anatomic materials are considered, with HU numbers similar to a real patient. A filled balloon inside the phantom tissue is inserted to simulate tumor. Deflation of the balloon simulates tumor shrinkage. Nonradiopaque surface markers, which do not influence DIR algorithms, provide the deformation ground truth. Fixed and movable holders are built in the phantom to hold a diode for dosimetric measurements. Results: The measured deformations at the surface marker positions can be compared with deformations calculated by a DIR algorithm to evaluate its accuracy. In this study, the authors selected a Demons algorithm as a DIR algorithm example for demonstration purposes. The average error magnitude is 2.1 mm. The point dose measurements from the in vivo diode dosimeters show a good agreement with the calculated doses from the treatment planning system with a maximum difference of 3.1% of prescription dose, when the treatment plans are delivered to the phantom with original or deformed geometry. Conclusions: In this study, the authors have presented the functionality of this deformable HN phantom for testing the accuracy of DIR algorithms and verifying the ART dosimetric accuracy. The authors’ experiments demonstrate the feasibility of this phantom serving as an end

Computerized method for evaluating diagnostic image quality of calcified plaque images in cardiac CT: Validation on a physical dynamic cardiac phantom

International Nuclear Information System (INIS)

King, Martin; Rodgers, Zachary; Giger, Maryellen L.; Bardo, Dianna M. E.; Patel, Amit R.

2010-01-01

Purpose: In cardiac computed tomography (CT), important clinical indices, such as the coronary calcium score and the percentage of coronary artery stenosis, are often adversely affected by motion artifacts. As a result, the expert observer must decide whether or not to use these indices during image interpretation. Computerized methods potentially can be used to assist in these decisions. In a previous study, an artificial neural network (ANN) regression model provided assessability (image quality) indices of calcified plaque images from the software NCAT phantom that were highly agreeable with those provided by expert observers. The method predicted assessability indices based on computer-extracted features of the plaque. In the current study, the ANN-predicted assessability indices were used to identify calcified plaque images with diagnostic calcium scores (based on mass) from a physical dynamic cardiac phantom. The basic assumption was that better quality images were associated with more accurate calcium scores. Methods: A 64-channel CT scanner was used to obtain 500 calcified plaque images from a physical dynamic cardiac phantom at different heart rates, cardiac phases, and plaque locations. Two expert observers independently provided separate sets of assessability indices for each of these images. Separate sets of ANN-predicted assessability indices tailored to each observer were then generated within the framework of a bootstrap resampling scheme. For each resampling iteration, the absolute calcium score error between the calcium scores of the motion-contaminated plaque image and its corresponding stationary image served as the ground truth in terms of indicating images with diagnostic calcium scores. The performances of the ANN-predicted and observer-assigned indices in identifying images with diagnostic calcium scores were then evaluated using ROC analysis. Results: Assessability indices provided by the first observer and the corresponding ANN performed

Patient radiation exposure in computerized tomography

Energy Technology Data Exchange (ETDEWEB)

Pavlov, V [Meditsinska Akademiya, Sofia (Bulgaria)

1980-01-01

Radiation exposure to patients undergoing axial computerized tomography as a tool of neurological X-ray diagnostics was studied. Doses thereby delivered were compared with those from routine head films at X-ray tube parameters 200 W, 70 kV, and 70 cm target-to-patient distance. Radiation exposures were analyzed with a view to improving shielding and procedural techniques. Comparisons were made using LiF TLD measurements with an Alderson phantom (standard for axial computer tomography). Skin and intracranial space doses were compared using two computers, Siretom I and Siretom 2000, for various positionings: frontal, fronto-lateral, temporal, temporo-occipital, and occipital. In addition, patient body doses with or without shielding and doses to subjects attending sick children or restless adults were examined. Achievable protection was estimated for lead shields of 0.5 mm lead equivalent. It was concluded that radiation doses delivered to neurologic patients undergoing axial computer tomography are smaller than those resulting from conventional X-ray examinations.

Radiation dose verification using real tissue phantom in modern radiotherapy techniques

International Nuclear Information System (INIS)

Gurjar, Om Prakash; Mishra, S.P.; Bhandari, Virendra; Pathak, Pankaj; Patel, Prapti; Shrivastav, Garima

2014-01-01

In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as 'head phantom' and goat meat as 'tissue phantom'. The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD): 0.74), 2.36 (SD: 0.77), 3.62 (SD: 1.05), and 3.31 (SD: 0.78) for three-dimensional conformal radiotherapy (3DCRT) (head phantom), intensity modulated radiotherapy (IMRT; head phantom), 3DCRT (tissue phantom), and IMRT (tissue phantom), respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%), but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body. (author)

Radiation dose verification using real tissue phantom in modern radiotherapy techniques

Directory of Open Access Journals (Sweden)

Om Prakash Gurjar

2014-01-01

Full Text Available In vitro dosimetric verification prior to patient treatment has a key role in accurate and precision radiotherapy treatment delivery. Most of commercially available dosimetric phantoms have almost homogeneous density throughout their volume, while real interior of patient body has variable and varying densities inside. In this study an attempt has been made to verify the physical dosimetry in actual human body scenario by using goat head as "head phantom" and goat meat as "tissue phantom". The mean percentage variation between planned and measured doses was found to be 2.48 (standard deviation (SD: 0.74, 2.36 (SD: 0.77, 3.62 (SD: 1.05, and 3.31 (SD: 0.78 for three-dimensional conformal radiotherapy (3DCRT (head phantom, intensity modulated radiotherapy (IMRT; head phantom, 3DCRT (tissue phantom, and IMRT (tissue phantom, respectively. Although percentage variations in case of head phantom were within tolerance limit (< ± 3%, but still it is higher than the results obtained by using commercially available phantoms. And the percentage variations in most of cases of tissue phantom were out of tolerance limit. On the basis of these preliminary results it is logical and rational to develop radiation dosimetry methods based on real human body and also to develop an artificial phantom which should truly represent the interior of human body.

Diagnostic radiology for head and neck neoplasms with emphasis on computerized tomography

International Nuclear Information System (INIS)

Weber, A.L.; Manzione, J.V.

1986-01-01

The radiologic evaluation of head and neck neoplasms constitutes an important part in their diagnosis and treatment. The introduction of computerized tomography (CT) and the further development of this modality since 1972 have contributed significantly to the staging of these neoplasms. CT not only demonstrates soft tissue densities, but also bony structures, muscles, fascial planes, opacified vascular structures, and enlarged lymph nodes. CT, however, fails to differentiate the various histologic types of lesions in the majority of cases. Features such as size of the lesion, marginal definition, lytic bone destruction, sclerotic bony reaction, bony expansion, calcific densities, fat content, and obliteration of fascial planes are utilized to delimit the spectrum of diagnostic possibilities. Conventional films including tomography are also indicated as preliminary examinations in the investigation of head and neck neoplasms. They provide a survey of the abnormality in question and form the basis for special studies such as CT and angiography. They are often the first examination to demonstrate a lesion that may be suspected from the history and clinical examination. 13 refs.; 11 figs

Computerized method for evaluating diagnostic image quality of calcified plaque images in cardiac CT: Validation on a physical dynamic cardiac phantom

Energy Technology Data Exchange (ETDEWEB)

King, Martin; Rodgers, Zachary; Giger, Maryellen L.; Bardo, Dianna M. E.; Patel, Amit R. [Department of Radiology, Committee on Medical Physics, University of Chicago, 5841 South Maryland Avenue, MC 2026, Chicago, Illinois 60637 (United States); Department of Diagnostic Radiology, Oregon Health and Science University, 3181 Southwest Sam Jackson Park Road, Portland, Oregon 97239 (United States); Department of Medicine, University of Chicago, 5841 South Maryland Avenue, MC 5084, Chicago, Illinois 60637 (United States)

2010-11-15

Purpose: In cardiac computed tomography (CT), important clinical indices, such as the coronary calcium score and the percentage of coronary artery stenosis, are often adversely affected by motion artifacts. As a result, the expert observer must decide whether or not to use these indices during image interpretation. Computerized methods potentially can be used to assist in these decisions. In a previous study, an artificial neural network (ANN) regression model provided assessability (image quality) indices of calcified plaque images from the software NCAT phantom that were highly agreeable with those provided by expert observers. The method predicted assessability indices based on computer-extracted features of the plaque. In the current study, the ANN-predicted assessability indices were used to identify calcified plaque images with diagnostic calcium scores (based on mass) from a physical dynamic cardiac phantom. The basic assumption was that better quality images were associated with more accurate calcium scores. Methods: A 64-channel CT scanner was used to obtain 500 calcified plaque images from a physical dynamic cardiac phantom at different heart rates, cardiac phases, and plaque locations. Two expert observers independently provided separate sets of assessability indices for each of these images. Separate sets of ANN-predicted assessability indices tailored to each observer were then generated within the framework of a bootstrap resampling scheme. For each resampling iteration, the absolute calcium score error between the calcium scores of the motion-contaminated plaque image and its corresponding stationary image served as the ground truth in terms of indicating images with diagnostic calcium scores. The performances of the ANN-predicted and observer-assigned indices in identifying images with diagnostic calcium scores were then evaluated using ROC analysis. Results: Assessability indices provided by the first observer and the corresponding ANN performed

Neurosurgical operating computerized tomographic scanner system

International Nuclear Information System (INIS)

Okudera, Hiroshi; Sugita, Kenichiro; Kobayashi, Shigeaki; Kimishima, Sakae; Yoshida, Hisashi.

1988-01-01

A neurosurgical operating computerized tomography scanner system is presented. This system has been developed for obtaining intra- and postoperative CT images in the operating room. A TCT-300 scanner (manufactured by the Toshiba Co., Tokyo) is placed in the operating room. The realization of a true intraoperative CT image requires certain improvements in the CT scanner and operating table. To adjust the axis of the co-ordinates of the motor system of the MST-7000 microsurgical operating table (manufactured by the Mizuho Ika Co., Tokyo) to the CT scanner, we have designed an interface and a precise motor system so that the computer of the CT scanner can directly control the movement of the operating table. Furthermore, a new head-fixation system has been designed for producing artifact-free intraoperative CT images. The head-pins of the head-fixation system are made of carbon-fiber bars and titanium tips. A simulation study of the total system in the operating room with the CT scanner, operating table, and head holder using a skull model yielded a degree of error similar to that in the phantom testing of the original scanner. Three patients underwent resection of a glial tumor using this system. Intraoperative CT scans taken after dural opening showed a bulging of the cortex, a shift in the central structure, and a displacement of the cortical subarachnoid spaces under the influence of gravity. With a contrast medium the edge of the surrounding brain after resection was enhanced and the residual tumor mass was demonstrated clearly. This system makes it possible to obtain a noninvasive intraoperative image in a situation where structural shifts are taking place. (author)

Proposal for dose measurement in the crystalline lens and thyroid in computerized tomography of paranasal sinuses

International Nuclear Information System (INIS)

Mello, Ana Caroline; Machado Neto, Vicente

2014-01-01

With the evolution of diagnostic imaging equipment, a computerized tomography (CT) has become one of the most used tests to assess pathologies affecting the paranasal sinuses. This work aims at presenting a method of obtaining measurements of dose in the eye lenses and thyroid, from the execution of CT of the paranasal sinuses protocol. Experimental procedure will be used in an object simulator (phantom) head and neck made with accessible materials and thermoluminescent dosimeters (TLDs) of LiF: Mg,Ti for the absorbed dose in the regions of interest, when exposed to radiation in a CT scanner 16 channels. After the dosimetric evaluation with phantom use, this methodology will be applied in vivo, or in patients with medical request for the examination and approval by the Ethics Committee. Thus, at the end of this survey protocols and actions aimed at reducing the absorbed dose in the eye lenses and thyroid without impairing the diagnostic image quality can be proposed. (author)

A new head-mounted display-based augmented reality system in neurosurgical oncology: a study on phantom.

Science.gov (United States)

Cutolo, Fabrizio; Meola, Antonio; Carbone, Marina; Sinceri, Sara; Cagnazzo, Federico; Denaro, Ennio; Esposito, Nicola; Ferrari, Mauro; Ferrari, Vincenzo

2017-12-01

Benefits of minimally invasive neurosurgery mandate the development of ergonomic paradigms for neuronavigation. Augmented Reality (AR) systems can overcome the shortcomings of commercial neuronavigators. The aim of this work is to apply a novel AR system, based on a head-mounted stereoscopic video see-through display, as an aid in complex neurological lesion targeting. Effectiveness was investigated on a newly designed patient-specific head mannequin featuring an anatomically realistic brain phantom with embedded synthetically created tumors and eloquent areas. A two-phase evaluation process was adopted in a simulated small tumor resection adjacent to Broca's area. Phase I involved nine subjects without neurosurgical training in performing spatial judgment tasks. In Phase II, three surgeons were involved in assessing the effectiveness of the AR-neuronavigator in performing brain tumor targeting on a patient-specific head phantom. Phase I revealed the ability of the AR scene to evoke depth perception under different visualization modalities. Phase II confirmed the potentialities of the AR-neuronavigator in aiding the determination of the optimal surgical access to the surgical target. The AR-neuronavigator is intuitive, easy-to-use, and provides three-dimensional augmented information in a perceptually-correct way. The system proved to be effective in guiding skin incision, craniotomy, and lesion targeting. The preliminary results encourage a structured study to prove clinical effectiveness. Moreover, our testing platform might be used to facilitate training in brain tumour resection procedures.

Computerized tomography and prognosis in paediatric head injury

International Nuclear Information System (INIS)

Tomberg, T.; Rink, U.; Pikkoja, E.; Tikk, A.

1996-01-01

The authors have analysed the computerized tomography (CT) findings and their correlation with the clinical state, early and late outcome in children and adolescents with head injuries (HI). This study represents clinical and CT data of 82 consecutive HI patients under 18 years of age. Among them 51 (62%) were boys and 31 (38 %) girls. The application of CT to the evaluation of the morphologic manifestations of HI in children has shown some differences in forms and mechanisms of injury and in outcome compared to adults. In the paediatric HI the most frequent finding was diffuse brain swelling with CT evidence of ventricular and cisternal compression or obliteration. Prognostically the most unfavourable findings were shearing injury, intracerebral and subdural haematomas combined with brain swelling and parenchymal damage. According to the Lidcombe impairment scale, outcome from severe paediatric HI was determined in the 3rd and 6th months, one year and 2 years after the injury. The outcome two years after severe HI varied to a great extent and was better in children than in adults. Although there was long-term disruption of the patient's quality of life, our data show that as there are no predictors of individual outcomes in child HI, no child should be excluded from early and long-term rehabilitation. (author)

Radiological equipment analyzed by specific developed phantoms and software

International Nuclear Information System (INIS)

Soto, M.; Campayo, J. M.; Mayo, P.; Verdu, G.; Rodenas, F.

2010-10-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

Radiological equipment analyzed by specific developed phantoms and software

Energy Technology Data Exchange (ETDEWEB)

Soto, M.; Campayo, J. M. [Logistica y Acondicionamientos Industriales SAU, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Mayo, P. [TITANIA Servicios Tecnologicos SL, Sorolla Center, Local 10, Av. de las Cortes Valencianas No. 58, 46015 Valencia (Spain); Verdu, G.; Rodenas, F., E-mail: m.soto@lainsa.co [ISIRYIM Universidad Politecnica de Valencia, Camino de Vera s/n, Valencia (Spain)

2010-10-15

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be computerized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In case of film-screen equipment s this analysis could be applied digitalising the image in a professional scanner. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment s. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment s and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques... etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (m As). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (Author)

Radiological response and dosimetry in physical phantom of head and neck for 3D conformational radiotherapy; Resposta radiologica e dosimetria em phantom fisico de cabeca e pescoco para radioterapia conformacional 3D

Energy Technology Data Exchange (ETDEWEB)

Thompson, Larissa

2013-07-01

Phantoms are tools for simulation of organs and tissues of the human body in radiology and radiotherapy. This thesis describes the development, validation and, most importantly, the use of a physical head and neck phantom in radiology and radiotherapy, with the purpose of evaluating dose distribution using Gafchromic EBT2 film in 15 MV 3D conformal radiotherapy. The work was divided in two stages, (1) development of new equivalent tissues and improvement of the physical phantom, and (2) use of the physical phantom in experimental dosimetry studies. In phase (1) parameters such as mass density, chemical composition of tissues, anatomical and biometric measurements were considered, as well as aspects of imaging by computed tomography (CT) and radiological response representation in Hounsfield Units (HU), which were compared with human data. Radiological experiments of in-phantom simulated brain pathologies were also conducted. All those results matched human-sourced data, therefore the physical phantom is a suitable simulator that may be used to enhance radiological protocols and education in medical imaging. The main objective in phase (2) was to evaluate the spatial dose distribution in a brain tumor simulator inserted inside the head and neck phantom developed by the Ionizing Radiation Research Group (NRI), exposed to 15 MV 3D conformal radiotherapy, for internal dose assessment. Radiation planning was based on CT images of the physical phantom with a brain tumor simulator made with equivalent material. The treatment planning system (TPS), CAT3D software, used CT images and prescribed a dose of 200 cGy, distributed in three fields of radiation, in a T-shaped pattern. The TPS covered the planning treatment volume (PTV) with 97% of the prescribed dose. A solid water phantom and radiochromic Gafchromic EBT2 film were used for calibration procedures, generating a dose response curve as a function of optical density (OD). After calibration and irradiation, the film

Development of age-specific Japanese physical phantoms for dose evaluation in infant CT examinations

International Nuclear Information System (INIS)

Yamauchi-Kawaura, C.; Fujii, K.; Imai, K.; Ikeda, M.; Akahane, K.; Obara, S.; Yamauchi, M.; Narai, K.; Katsu, T.

2016-01-01

Secondary to the previous development of age-specific Japanese head phantoms, the authors designed Japanese torso phantoms for dose assessment in infant computed tomography (CT) examinations and completed a Japanese 3-y-old head-torso phantom. For design of age-specific torso phantoms (0, 0.5, 1 and 3 y old), anatomical structures were measured from CT images of Japanese infant patients. From the CT morphometry, it was found that rib cages of Japanese infants were smaller than those in Europeans and Americans. Radiophotoluminescence glass dosemeters were used for dose measurement of a 3-y-old head-torso phantom. To examine the validity of the developed phantom, organ and effective doses by the in-phantom dosimetry system were compared with simulation values in a web-based CT dose calculation system (WAZA-ARI). The differences in doses between the two systems were <20 % at the doses of organs within scan regions and effective doses in head, chest and abdomino-pelvic CT examinations. (authors)

The role of phantom and treatment head generated bremsstrahlung in high-energy electron beam dosimetry

International Nuclear Information System (INIS)

Sorcini, B.B.; Hyoedynmaa, S.; Brahme, A.

1996-01-01

An analytical expression has been derived for the phantom generated bremsstrahlung photons in plane-parallel monoenergetic electron beams normally incident on material of any atomic number (Be, H 2 O, Al, Cu and U). The expression is suitable for the energy range from 1 to 50 MeV and it is solely based on known scattering power and radiative and collision stopping power data for the material at the incident electron energy. The depth dose distribution due to the bremsstrahlung generated by the electrons in the phantom is derived by convolving the bremsstrahlung energy fluence produced in the phantom with a simple analytical energy deposition kernel. The kernel accounts for both electrons and photons set in motion by the bremsstrahlung photons. The energy loss by the primary electrons, the build-up of the electron fluence and the generation, attenuation and absorption of bremsstrahlung photons are all taken into account in the analytical formula. The longitudinal energy deposition kernel is derived analytically and it is consistent with both the classical biexponential relation describing the photon depth dose distribution and the exponential attenuation of the primary photons. For comparison Monte Carlo calculated energy deposition distributions using ITS3 code were used. Good agreement was found between the results with the analytical expression and the Monte Carlo calculation. For tissue equivalent materials, the maximum total energy deposition differs by less than 0.2% from Monte Carlo calculated dose distributions. The result can be used to estimate the depth dependence of phantom generated bremsstrahlung in different materials in therapeutic electron beams and the bremsstrahlung production in different electron absorbers such as scattering foils, transmission monitors and photon and electron collimators. By subtracting the phantom generated bremsstrahlung from the total bremsstrahlung background the photon contamination generated in the treatment head can be

Evaluation of radiation dose in pediatric head CT examination: a phantom study

Science.gov (United States)

Norhasrina Nik Din, Nik; Zainon, Rafidah; Rahman, Ahmad Taufek Abdul

2018-01-01

The aim of this study was to evaluate the radiation dose in pediatric head Computed Tomography examination. It was reported that decreasing tube voltage in CT examination can reduce the dose to patients significantly. A head phantom was scanned with dual-energy CT at 80 kV and 120 kV. The tube current was set using automatic exposure control mode and manual setting. The pitch was adjusted to 1.4, 1.45 and 1.5 while the slice thickness was set at 5 mm. The dose was measured based on CT Dose Index (CTDI). Results from this study have shown that the image noise increases substantially with low tube voltage. The average dose was 2.60 mGy at CT imaging parameters of 80 kV and 10 - 30 mAs. The dose increases up to 17.19 mGy when the CT tube voltage increases to 120 kV. With the reduction of tube voltage from 120 kV to 80 kV, the radiation dose can be reduced by 12.1% to 15.1% without degradation of contrast-to-noise ratio.

Adaptation and validation of a commercial head phantom for cranial radiosurgery dosimetry end-to-end audit.

Science.gov (United States)

Dimitriadis, Alexis; Palmer, Antony L; Thomas, Russell A S; Nisbet, Andrew; Clark, Catharine H

2017-06-01

To adapt and validate an anthropomorphic head phantom for use in a cranial radiosurgery audit. Two bespoke inserts were produced for the phantom: one for providing the target and organ at risk for delineation and the other for performing dose measurements. The inserts were tested to assess their positional accuracy. A basic treatment plan dose verification with an ionization chamber was performed to establish a baseline accuracy for the phantom and beam model. The phantom and inserts were then used to perform dose verification measurements of a radiosurgery plan. The dose was measured with alanine pellets, EBT extended dose film and a plastic scintillation detector (PSD). Both inserts showed reproducible positioning (±0.5 mm) and good positional agreement between them (±0.6 mm). The basic treatment plan measurements showed agreement to the treatment planning system (TPS) within 0.5%. Repeated film measurements showed consistent gamma passing rates with good agreement to the TPS. For 2%-2 mm global gamma, the mean passing rate was 96.7% and the variation in passing rates did not exceed 2.1%. The alanine pellets and PSD showed good agreement with the TPS (-0.1% and 0.3% dose difference in the target) and good agreement with each other (within 1%). The adaptations to the phantom showed acceptable accuracies. The presence of alanine and PSD do not affect film measurements significantly, enabling simultaneous measurements by all three detectors. Advances in knowledge: A novel method for thorough end-to-end test of radiosurgery, with capability to incorporate all steps of the clinical pathway in a time-efficient and reproducible manner, suitable for a national audit.

Dose profile study in head CT scans using a male anthropomorphic phantom

International Nuclear Information System (INIS)

Gomez, Alvaro M.L.; Santana, Priscila do C.; Mourao, Arnaldo P.

2017-01-01

Computed tomography (CT) test is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in the patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. An anthropomorphic adult male phantom was used and radiochromic film strips were placed to measure the absorbed dose deposited in areas such as the lens, thyroid and pituitary for study of dose deposited in these important areas containing high radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans. (author)

Dose profile study in head CT scans using a male anthropomorphic phantom

Energy Technology Data Exchange (ETDEWEB)

Gomez, Alvaro M.L.; Santana, Priscila do C.; Mourao, Arnaldo P., E-mail: amlgphys@gmail.com, E-mail: pridili@gmail.com, E-mail: apratabhz@gmail.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Engenharia Nuclear; Centro Federal de Educação Tecnológica de Minas Gerais (CEFET-MG), Belo Horizonte, MG (Brazil)

2017-11-01

Computed tomography (CT) test is an efficient and non-invasive method to obtain data about internal structures of the human body. CT scans contribute with the highest absorbed doses in population due X-ray beam attenuation and it has raised concern in radiosensitive tissues. Techniques for the optimization of CT scanning protocols in diagnostic services have been developing with the objective of decreasing the absorbed dose in the patient, aiming image quality within acceptable parameters for diagnosis by noise control. Routine head scans were performed using GE CT scan of 64 channels programmed with automatic exposure control and voltages of 80, 100 and 120 kV attaching the noise index in approximately 0.5%, using the tool of smart mA. An anthropomorphic adult male phantom was used and radiochromic film strips were placed to measure the absorbed dose deposited in areas such as the lens, thyroid and pituitary for study of dose deposited in these important areas containing high radiosensitive tissues. Different head scans were performed using optimized values of mA.s for the different voltages. The absorbed dose measured by the film strips were in the range of the 0.58 and 44.36 mGy. The analysis of noise in the images is within the acceptable levels for diagnosis, and the optimized protocol happens with the voltage of 100 kV. The use of other voltage values can allow obtain better protocols for head scans. (author)

A three-dimensional head-and-neck phantom for validation of multimodality deformable image registration for adaptive radiotherapy

International Nuclear Information System (INIS)

Singhrao, Kamal; Kirby, Neil; Pouliot, Jean

2014-01-01

Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H and N) phantom with realistic tissue contrast for both kilovoltage (kV) and megavoltage (MV) imaging modalities and use it to objectively evaluate deformable image registration (DIR) algorithms. Methods: The phantom represents H and N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kV and MV imaging. The phantom opens along a sagittal midsection to reveal radiotransparent markers, which were used to characterize the phantom deformation. The deformed and undeformed phantoms were scanned with kV and MV imaging modalities. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM software. Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able to represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV–kV registration, MIM produced mean and maximum errors of 1.8 and 11.5 mm, respectively. These same numbers for Velocity were 2.4 and 7.1 mm, respectively. For MV–MV, kV–MV, and kV–MC Velocity produced similar mean and maximum error values. MIM, however, produced gross errors for all three of these scenarios, with maximum errors ranging from 33.4 to 41.6 mm. Conclusions: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H and N phantom is an effective tool

Clinical value of computerized tomography scanning in severe head injury

International Nuclear Information System (INIS)

Kobayashi, Shiro; Yano, Masami; Otsuka, Toshibumi; Nakazawa, Shozo

1982-01-01

Serial computerized tomography (SCT) was performed on 138 patients suffering from severe head injuries (8 or less on the Glasgow Coma Scale). Standard practice called for scans to be done upon admission (within hours of the injury), and after 1, 3, 7 days and 1 month. Subsequent CT's depended on the patient's condition. Clinical results at the time of discharge were graded according to the Glasgow Outcome Scale. Patients who died, were in a persistent vegetative state, or were severely disabled were considered to have a ''bad outcome''. On the other hand, patients who were somewhat disabled or made good recoveries were considered to have a ''good outcome''. During the serial CT scan, there were new findings (not visualized on the initial CT but appearing on subsequent ones) in 91 of the 138 patients. These new findings were classified as follows; 1) decreased density collection in the subdural space (DDC), 2) ventricular dilation (VD), 3) intracerebral hematoma (ICH), 4) intraventricular hemorrhage (IVH), 5) extracerebral hematoma (ECH), 6) edema (E), 7) infarction (I). We defined ICH, IVH, ECH, E and I as new lesions. Of the 60 patients with new lesions 12 had good outcomes and 48 had poor outcomes. There were 78 patients who did not have any new lesions, 60 with good outcomes and 18 with poor outcomes. A significant correlation was found between good outcomes and the absence of new lesions, and between bad outcomes and the development of new lesions (p 2 = 44.038). We conclude that SCT can help predict the outcome with severe head injury patients and may be very important in their examination and care. (J.P.N.)

Celebral computerized tomography

International Nuclear Information System (INIS)

Lofteroed, B.; Sortland, O.

1985-01-01

Indications for cerebral computerized tomography (CT) and the diagnostic results from this examination are evaluated in 127 children. Pathological changes were found in 31 children, mostly based on such indications as increasing head size, suspicion of brain tumor, cerebral paresis, delayed psychomotor development and epileptic seizures. A list of indications for CT in children is given

Patient specific 3D printed phantom for IMRT quality assurance

International Nuclear Information System (INIS)

Ehler, Eric D; Higgins, Patrick D; Dusenbery, Kathryn E; Barney, Brett M

2014-01-01

The purpose of this study was to test the feasibility of a patient specific phantom for patient specific dosimetric verification. Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. Calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was compared for a parallel-opposed head and neck field geometry to establish tissue equivalence. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom as well as traditional standard phantoms. The maximum difference in calculated dose was 1.8% for the parallel-opposed configuration. Passing rates of various dosimetric parameters were compared for the IMRT plan measurements; the 3D printed phantom results showed greater disagreement at superficial depths than other methods. A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine use. (paper)

Calibration Human Voxel Phantoms for In Vivo Measurement of ''241 Am in Bone at the Whole Body Counter Facility of CIEMAT

International Nuclear Information System (INIS)

Moraleda, M.; Lopez, M. A.; Gomez Ros, J. M.; Navarro, T.; Navarro, J. F.

2002-01-01

The Whole Body Counting facility of CIEMAT is capable of carrying out In-Vivo measurements of radionuclides emitting X-rays and low energy gamma radiation internally deposited in the body. The system to use for this purpose consists of flour Low energy Germanium (LeGe) Camberra detectors working in the energy range from 10 to 1000 keV. Physical phantoms with a known contamination in the organ of interest are normally used for the calibration of the LEGe detection system. In this document we present a calibration method using the Monte Carlo technique (MCNP4C) over a voxel phantom obtained from a computerized tomography of a real human head. The phantom consists of 104017 (43x59x41) cubic voxels, 4 mn on each side, os specific tissues, but for this simulation only two types are taken into account: adipose tissue and hard bone. The skull is supposed to be contaminated with ''241 Am and the trajectories of the photons are simulated till they reach the germanium detectors. The detectors were also simulated in detail to obtain a good agreement with the reality. In order to verify the accuracy of this procedure to reproduce the experiments, the MCNP results are compared with laboratory measurements of a head phantom simulating an internal contamination of 1000 Bq of ''241 Am deposited in bone. Different relative positions source-detector were tried to look for the best counting geometry for measurement of a contaminated skull. Efficiency values are obtained and compared, resulting in the validation of the mathematical method for the assessment of internal contamination of American deposited in skeleton. (Author) 16 refs

Development and application of a pediatric head phantom for dosimetry in computed tomography; Desenvolvimento e aplicacao de um simulador pediatrico craniano para dosimetria em tomografia computadorizada

Energy Technology Data Exchange (ETDEWEB)

Martins, Elaine Wirney

2016-11-01

To determine the exposure levels and the absorbed dose in patients undergoing CT scans, is necessary to calculate the CT dose index in measurements with a PMMA or water phantom. The phantom must be enough to simulate the attenuation and scattering characteristics of a human body or parts in a radiation field. The CT specific quantities : CT air kerma index (Ca,100) , weighted CT air kerma index (CW ), a total volume CT air kerma index (Cvol) and the CT air kerma-length product (PKL) must be determined and compared to literature reference levels. In this work a head pediatric phantom was developed, considering that the Brazilian published Diagnostic Reference Levels (DRL) are based on adult phantom measurements. This developed phantom shows a construction innovation using materials to simulate the skullcap, cortical bone (aluminum) and cancellous bone (PVC), and it was filled with distilled water. The phantom dimension follows the recommendations of the World Health Organization and the International Commission on Radiation Units for children from 0 to 5 years old head size: diameter of 160 mm and height of 155 mm. The skullcap has 4 mm of thickness and 111.9 mm of internal diameter. In order to evaluate its behavior, tests were carried out in calibration laboratories and in clinical beams. The results showed attenuation up to 23% when different materials are used as skullcap, demonstrating that the DRLs adopted could be overestimating the dose received by pediatric patients. It is observed that the dose received by CT skull scans presents different distribution, due to the skullcap partially attenuation and/or backscattering which is not considered when the PMMA phantom is used.

Calibration Human Voxel Phantoms for In Vivo Measurement of ''2 sup 4 sup 1 Am in Bone at the Whole Body Counter Facility of CIEMAT

CERN Document Server

Moraleda, M; Navarro, J F; Navarro, T

2002-01-01

The Whole Body Counting facility of CIEMAT is capable of carrying out In-Vivo measurements of radionuclides emitting X-rays and low energy gamma radiation internally deposited in the body. The system to use for this purpose consists of flour Low energy Germanium (LeGe) Camberra detectors working in the energy range from 10 to 1000 keV. Physical phantoms with a known contamination in the organ of interest are normally used for the calibration of the LEGe detection system. In this document we present a calibration method using the Monte Carlo technique (MCNP4C) over a voxel phantom obtained from a computerized tomography of a real human head. The phantom consists of 104017 (43x59x41) cubic voxels, 4 mn on each side, os specific tissues, but for this simulation only two types are taken into account: adipose tissue and hard bone. The skull is supposed to be contaminated with ''241 Am and the trajectories of the photons are simulated till they reach the germanium detectors. The detectors were also simulated in det...

Determination of appropriate exposure angles for the reverse water's view using a head phantom

Energy Technology Data Exchange (ETDEWEB)

Lee, Min Su; Lee, Keun Ohk [Dept. of Radiology, Soonchunhyang University Hospital, Bucheon (Korea, Republic of); Choi, Jae Ho [Dept. of Radiological Technology, Ansan University, Ansan (Korea, Republic of); Jung, Jae Hong [Dept. of Biomedical Engineering, College of Medicine, The Catholic University, Seoul (Korea, Republic of)

2017-06-15

Early diagnosis for upper facial trauma is difficult by using the standard Water's view (S-Water's) in general radiograph due to overlapping of anatomical structures, the uncertainty of patient positioning, and specific patients with obese, pediatric, old, or high-risk. The purpose of this study was to analyze appropriate exposure angles through a comparison of two different protocols (S-Water's vs. reverse Water's view (R-Water's)) by using a head phantom. A head phantom and general radiograph with 75 kVp, 400 mA, 45 ms 18 mAs, and SID 100 cm. Images of R-Water's were obtained by different angles in the range of 0 degree to 50 degrees, which adjusted an angle at 1 degree interval in supine position. Survey elements were developed and three observers were evaluated with four elements including the maxillary sinus, zygomatic arch, petrous ridge, and image distortion. Statistical significant analysis were used the Krippendorff's alpha and Fleiss' kappa. The intra-class correlation (ICC) coefficient for three observers were high with maxillary, 0.957 (0.903, 0.995); zygomatic arch, 0.939 (0.866, 0.987); petrous ridge, 0.972 (0.897, 1.000); and image distortion, 0.949 (0.830, 1.000). The high-quality image (HI) and perfect agreement (PA) for acquired exposure angles were high in range of the maxillary sinus (36 degrees – 44 degrees), zygomatic arch (33 degrees – 40 degrees), petrous ridge (32 degrees – 50 degrees), and image distortion (44 degrees– 50 degrees). Consequently, an appropriate exposure angles for the R-Water's view in the supine position for patients with facial trauma are in the from 36 degrees to 40 degrees in this phantom study. The results of this study will be helpful for the rapid diagnosis of facial fractures by simple radiography.

Determination of appropriate exposure angles for the reverse water's view using a head phantom

International Nuclear Information System (INIS)

Lee, Min Su; Lee, Keun Ohk; Choi, Jae Ho; Jung, Jae Hong

2017-01-01

Early diagnosis for upper facial trauma is difficult by using the standard Water's view (S-Water's) in general radiograph due to overlapping of anatomical structures, the uncertainty of patient positioning, and specific patients with obese, pediatric, old, or high-risk. The purpose of this study was to analyze appropriate exposure angles through a comparison of two different protocols (S-Water's vs. reverse Water's view (R-Water's)) by using a head phantom. A head phantom and general radiograph with 75 kVp, 400 mA, 45 ms 18 mAs, and SID 100 cm. Images of R-Water's were obtained by different angles in the range of 0 degree to 50 degrees, which adjusted an angle at 1 degree interval in supine position. Survey elements were developed and three observers were evaluated with four elements including the maxillary sinus, zygomatic arch, petrous ridge, and image distortion. Statistical significant analysis were used the Krippendorff's alpha and Fleiss' kappa. The intra-class correlation (ICC) coefficient for three observers were high with maxillary, 0.957 (0.903, 0.995); zygomatic arch, 0.939 (0.866, 0.987); petrous ridge, 0.972 (0.897, 1.000); and image distortion, 0.949 (0.830, 1.000). The high-quality image (HI) and perfect agreement (PA) for acquired exposure angles were high in range of the maxillary sinus (36 degrees – 44 degrees), zygomatic arch (33 degrees – 40 degrees), petrous ridge (32 degrees – 50 degrees), and image distortion (44 degrees– 50 degrees). Consequently, an appropriate exposure angles for the R-Water's view in the supine position for patients with facial trauma are in the from 36 degrees to 40 degrees in this phantom study. The results of this study will be helpful for the rapid diagnosis of facial fractures by simple radiography

Evaluation of the absorbed dose in odontological computerized tomography

International Nuclear Information System (INIS)

Legnani, Adriano; Schelin, Hugo R.; Rocha, Anna Silvia P.S. da; Khoury, Helen J.

2011-01-01

This paper evaluated the absorbed dose at the surface entry known as 'cone beam computed tomography' (CBCT) in odontological computerized tomography. Examination were simulated with CBCT for measurements of dose. A phantom were filled with water, becoming scatter object of radiation. Thermoluminescent dosemeters were positioned on points correspondent to eyes and salivary glands

MO-F-CAMPUS-J-01: Effect of Iodine Contrast Agent Concentration On Cerebrovascular Dose for Synchrotron Radiation Microangiography Based On a Simple Mouse Head Model and a Voxel Mouse Head Phantom

Energy Technology Data Exchange (ETDEWEB)

Lin, H; Jing, J; Xie, C [Hefei University of Technology, Hefei (China); Lu, Y [Shanghai Jiao Tong University, Shanghai (China)

2015-06-15

Purpose: To find effective setting methods to mitigate the irradiation injure in synchrotron radiation microangiography(SRA) by Monte Carlo simulation. Methods: A mouse 1-D head model and a segmented voxel mouse head phantom were simulated by EGSnrc/Dosxyznrc code to investigate the dose enhancement effect of the iodine contrast agent irradiated by a monochromatic synchrotron radiation(SR) source. The influence of, like iodine concentration (IC), vessel width and depth, with and without skull layer protection and the various incident X ray energies, were simulated. The dose enhancement effect and the absolute dose based on the segmented voxel mouse head phantom were evaluated. Results: The dose enhancement ratio depends little on the irradiation depth, but strongly on the IC, which is linearly increases with IC. The skull layer protection cannot be ignored in SRA, the 700µm thick skull could decrease 10% of the dose. The incident X-ray energy can significantly affact the dose. E.g. compared to the dose of 33.2keV for 50mgI/ml, the 32.7keV dose decreases 38%, whereas the dose of 33.7 keV increases 69.2%, and the variation will strengthen more with enhanced IC. The segmented voxel mouse head phantom also showed that the average dose enhancement effect and the maximal voxel dose per photon depends little on the iodine voxel volume ratio, but strongly on IC. Conclusion: To decrease dose damage in SRA, the high-Z contrast agent should be used as little as possible, and try to avoid radiating locally the injected position immediately after the contrast agent injection. The fragile vessel containing iodine should avoid closely irradiating. Avoiding irradiating through the no or thin skull region, or appending thin equivalent material from outside to protect is also a better method. As long as SRA image quality is ensured, using incident X-ray energy as low as possible.

Measurements and calculations of neutron spectra and neutron dose distribution in human phantoms

International Nuclear Information System (INIS)

Palfalvi, J.

1984-11-01

The measurement and calculation of the radiation field around and in a phantom, with regard to the neutron component and the contaminating gamma radiation, are essential for radiation protection and radiotherapy purposes. The final report includes the development of the simple detector system, automized detector measuring facilities and a computerized evaluating system. The results of the depth dose and neutron spectra experiments and calculations in a human phantom are given

Calibration Human Voxel Phantoms for In Vivo Measurement of ''241 Am in Bone at the Whole Body Counter Facility of CIEMAT

Energy Technology Data Exchange (ETDEWEB)

Moraleda, M.; Lopez, M. A.; Gomez Ros, J. M.; Navarro, T.; Navarro, J. F.

2002-07-01

The Whole Body Counting facility of CIEMAT is capable of carrying out In-Vivo measurements of radionuclides emitting X-rays and low energy gamma radiation internally deposited in the body. The system to use for this purpose consists of flour Low energy Germanium (LeGe) Camberra detectors working in the energy range from 10 to 1000 keV. Physical phantoms with a known contamination in the organ of interest are normally used for the calibration of the LEGe detection system. In this document we present a calibration method using the Monte Carlo technique (MCNP4C) over a voxel phantom obtained from a computerized tomography of a real human head. The phantom consists of 104017 (43x59x41) cubic voxels, 4 mn on each side, os specific tissues, but for this simulation only two types are taken into account: adipose tissue and hard bone. The skull is supposed to be contaminated with ''241 Am and the trajectories of the photons are simulated till they reach the germanium detectors. The detectors were also simulated in detail to obtain a good agreement with the reality. In order to verify the accuracy of this procedure to reproduce the experiments, the MCNP results are compared with laboratory measurements of a head phantom simulating an internal contamination of 1000 Bq of ''241 Am deposited in bone. Different relative positions source-detector were tried to look for the best countring geometry for measurement of a contaminated skull. Efficiency values are obtained and compared, resulting in the validation of the mathematical method for the assessment of internal contamination of American deposited in skeleton. (Author) 16 refs.

Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

Energy Technology Data Exchange (ETDEWEB)

Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Williams, Cameron H.; Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2013-04-15

Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest-abdomen-pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore, serve

Population of anatomically variable 4D XCAT adult phantoms for imaging research and optimization

International Nuclear Information System (INIS)

Segars, W. P.; Bond, Jason; Frush, Jack; Hon, Sylvia; Eckersley, Chris; Samei, E.; Williams, Cameron H.; Frush, D.; Feng Jianqiao; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

2013-01-01

Purpose: The authors previously developed the 4D extended cardiac-torso (XCAT) phantom for multimodality imaging research. The XCAT consisted of highly detailed whole-body models for the standard male and female adult, including the cardiac and respiratory motions. In this work, the authors extend the XCAT beyond these reference anatomies by developing a series of anatomically variable 4D XCAT adult phantoms for imaging research, the first library of 4D computational phantoms. Methods: The initial anatomy of each phantom was based on chest–abdomen–pelvis computed tomography data from normal patients obtained from the Duke University database. The major organs and structures for each phantom were segmented from the corresponding data and defined using nonuniform rational B-spline surfaces. To complete the body, the authors manually added on the head, arms, and legs using the original XCAT adult male and female anatomies. The structures were scaled to best match the age and anatomy of the patient. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from the template XCAT phantom (male or female) to the target patient model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. Each new phantom was refined by checking for anatomical accuracy via inspection of the models. Results: Using these methods, the authors created a series of computerized phantoms with thousands of anatomical structures and modeling cardiac and respiratory motions. The database consists of 58 (35 male and 23 female) anatomically variable phantoms in total. Like the original XCAT, these phantoms can be combined with existing simulation packages to simulate realistic imaging data. Each new phantom contains parameterized models for the anatomy and the cardiac and respiratory motions and can, therefore

NMR-CT image and symbol phantoms

International Nuclear Information System (INIS)

Hongo, Syozo; Yamaguchi, Hiroshi; Takeshita, Hiroshi

1990-01-01

We have developed Japanese phantoms in two procedures. One is described as a mathematical expression. Another is 'symbol phantoms' in 3 dimensional picture-elements, each of which symbolize an organ name. The concept and the algorithm of the symbol phantom enables us to make a phantom for a individual in terms of all his transversal section images. We got 85 transversal section images of head and trunk parts, and those of 40 legs parts by using NMR-CT. We have made the individual phantom for computation of organ doses. The transversal section images were not so clear to identify all organs needed to dose estimation that we had to do hand-editing the shapes of organs with viewing a typical section images: we could not yet make symbol phantom in a automatic editing. Symbols were coded to be visual cords as ASCII characters. After we got the symbol phantom of the first stage, we can edit it easily using a word-processor. Symbol phantom could describe more freely the shape of organs than mathematical phantom. Symbol phantom has several advantages to be an individual phantom, but the only difficult point is how to determine its end-point as a reference man when we apply the method to build the reference man. (author)

Large scale study on the variation of RF energy absorption in the head & brain regions of adults and children and evaluation of the SAM phantom conservativeness

Science.gov (United States)

Keshvari, J.; Kivento, M.; Christ, A.; Bit-Babik, G.

2016-04-01

This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases.

Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom.

Science.gov (United States)

Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

2014-07-01

To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques.

WE-D-303-00: Computational Phantoms

Energy Technology Data Exchange (ETDEWEB)

Lewis, John [Duke University Medical Center, Durham, NC (United States); Brigham and Women’s Hospital and Dana-Farber Cancer Institute, Boston, MA (United States)

2015-06-15

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems.

WE-D-303-00: Computational Phantoms

International Nuclear Information System (INIS)

Lewis, John

2015-01-01

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems

Marvin: an anatomical phantom for dosimetric evaluation of complex radiotherapy of the head and neck

Science.gov (United States)

Aitkenhead, A. H.; Rowbottom, C. G.; Mackay, R. I.

2013-10-01

We report on the design of Marvin, a Model Anatomy for Radiotherapy Verification and audit In the head and Neck and present results demonstrating its use in the development of the Elekta volumetric modulated arc therapy (VMAT) technique at the Christie, and in the audit of TomoTherapy and Varian RapidArc at other institutions. The geometry of Marvin was generated from CT datasets of eight male and female patients lying in the treatment position, with removable inhomogeneities modelling the sinuses and mandible. A modular system allows the phantom to be used with a range of detectors, with the locations of the modules being based on an analysis of a range of typical treatment plans (27 in total) which were mapped onto the phantom geometry. Results demonstrate the use of Gafchromic EBT2/EBT3 film for measurement of relative dose in a plane through the target and organs-at-risk, and the use of a small-volume ionization chamber for measurement of absolute dose in the target and spinal cord. Measurements made during the development of the head and neck VMAT protocol at the Christie quantified the improvement in plan delivery resulting from the installation of the Elekta Integrity upgrade (which permits an effectively continuously variable dose rate), with plans delivered before and after the upgrade having 88.5 ± 9.4% and 98.0 ± 2.2% respectively of points passing a gamma analysis (at 4%, 4 mm, global). Audits of TomoTherapy and Varian RapidArc neck techniques at other institutions showed a similar quality of plan delivery as for post-Integrity Elekta VMAT: film measurements for both techniques had >99% of points passing a gamma analysis at the clinical criteria of 4%, 4 mm, global, and >95% of points passing at tighter criteria of 3%, 3 mm, global; and absolute dose measurements in the PTV and spinal cord were within 1.5% and 3.5% of the planned doses respectively for both techniques. The results demonstrate that Marvin is an efficient and effective means of

Marvin: an anatomical phantom for dosimetric evaluation of complex radiotherapy of the head and neck

International Nuclear Information System (INIS)

Aitkenhead, A H; Rowbottom, C G; Mackay, R I

2013-01-01

We report on the design of Marvin, a Model Anatomy for Radiotherapy Verification and audit In the head and Neck and present results demonstrating its use in the development of the Elekta volumetric modulated arc therapy (VMAT) technique at the Christie, and in the audit of TomoTherapy and Varian RapidArc at other institutions. The geometry of Marvin was generated from CT datasets of eight male and female patients lying in the treatment position, with removable inhomogeneities modelling the sinuses and mandible. A modular system allows the phantom to be used with a range of detectors, with the locations of the modules being based on an analysis of a range of typical treatment plans (27 in total) which were mapped onto the phantom geometry. Results demonstrate the use of Gafchromic EBT2/EBT3 film for measurement of relative dose in a plane through the target and organs-at-risk, and the use of a small-volume ionization chamber for measurement of absolute dose in the target and spinal cord. Measurements made during the development of the head and neck VMAT protocol at the Christie quantified the improvement in plan delivery resulting from the installation of the Elekta Integrity upgrade (which permits an effectively continuously variable dose rate), with plans delivered before and after the upgrade having 88.5 ± 9.4% and 98.0 ± 2.2% respectively of points passing a gamma analysis (at 4%, 4 mm, global). Audits of TomoTherapy and Varian RapidArc neck techniques at other institutions showed a similar quality of plan delivery as for post-Integrity Elekta VMAT: film measurements for both techniques had >99% of points passing a gamma analysis at the clinical criteria of 4%, 4 mm, global, and >95% of points passing at tighter criteria of 3%, 3 mm, global; and absolute dose measurements in the PTV and spinal cord were within 1.5% and 3.5% of the planned doses respectively for both techniques. The results demonstrate that Marvin is an efficient and effective means of

Reducing dose in head CT: A phantom study

International Nuclear Information System (INIS)

Perez Diaz, M.; Carvalho, A. E.; Andrade, M. E.; Khoury, H. J.

2013-01-01

Thirty two head CT scans were acquired employing an anthropomorphic phantom which contains small lesions in posterior fosse, using 2 scanners, one with 64 slices 'Siemens Sensation' and other with 6 slices P hilip Brilliance . Parameters as Tube current (I [mA]), Collimation (C [mm]), spectrum energy (kVp) and dynamic range were changed during studies, looking for the optimal acquisition/processing conditions which permit both, good lesion detectability and the lowest dose. Air kerma (mGy) was measured with a ionization chamber and the air kerma index (Ca,100 [mGy]) was calculated as dose index. Image quality was analyzed by 5 expert criteria using a 5 points-scale (1=poor, 2=fair, 3=good, 4=very good, 5=excellent) and also using 5 Figure of merit in the spatial and frequency domains: Contrast C(%), Contrast to Noise Ratio CNR, Signal to Noise Ratio SNR, Normalized Mean Square Error (NMSE) and the Spectral Distance (SD). Objective and subjective results were correlated. We observed that doses can be diminished until a 25% respect to the usual practice with both technologies, diminishing mainly the mAs, without affecting lesion detection. As a result, we propose an optimized protocol for each scanner as follow: The use of 250 mAs, 120 kVp and the collimation of 6 slices x 1.50 mm per rotation to detect the lesions in posterior fosse with good image quality for the Philips Brilliance 6 tested, while 150 mAs, 100 kVp and slice thickness of 3 mm were needed with the Siemens Sensation 64. (Author)

Organ doses from computerized tomography examinations

Energy Technology Data Exchange (ETDEWEB)

Janeczek, J.

1995-12-31

Estimates of mean organs doses from five typical computerized tomography (CT) examinations were obtained. Measurements were done using Rando-Alderson anthropomorphic phantom and thermoluminescent dosemeters (TLD). Radiation dose distributions within a phantom has been measured for each examination and results were used for organ dose calculation. Doses to organs specified by ICPR 60 Recommendations were measured for five CT scanners (CT/T8800, CT 9800, CT MAX - made by General Electric; CT 1200 SX - made by Picker; SOMATOM 2 - made by Siemens). Dose distributions from scattered radiation were measured and indicate that scattered radiation dose to thyroid and eye lens can be reduced by proper examination limits setting. The lowest mean organ doses were obtained from CT/T8800 scanner. More advanced scanners using high intensity continuous radiation were giving higher organ doses. (author). 23 refs, 6 figs, 13 tabs.

Organ doses from computerized tomography examinations

International Nuclear Information System (INIS)

Janeczek, J.

1995-01-01

Estimates of mean organs doses from five typical computerized tomography (CT) examinations were obtained. Measurements were done using Rando-Alderson anthropomorphic phantom and thermoluminescent dosemeters (TLD). Radiation dose distributions within a phantom has been measured for each examination and results were used for organ dose calculation. Doses to organs specified by ICPR 60 Recommendations were measured for five CT scanners (CT/T8800, CT 9800, CT MAX - made by General Electric; CT 1200 SX - made by Picker; SOMATOM 2 - made by Siemens). Dose distributions from scattered radiation were measured and indicate that scattered radiation dose to thyroid and eye lens can be reduced by proper examination limits setting. The lowest mean organ doses were obtained from CT/T8800 scanner. More advanced scanners using high intensity continuous radiation were giving higher organ doses. (author). 23 refs, 6 figs, 13 tabs

Large scale study on the variation of RF energy absorption in the head and brain regions of adults and children and evaluation of the SAM phantom conservativeness

International Nuclear Information System (INIS)

Keshvari, J; Kivento, M; Christ, A; Bit-Babik, G

2016-01-01

This paper presents the results of two computational large scale studies using highly realistic exposure scenarios, MRI based human head and hand models, and two mobile phone models. The objectives are (i) to study the relevance of age when people are exposed to RF by comparing adult and child heads and (ii) to analyze and discuss the conservativeness of the SAM phantom for all age groups. Representative use conditions were simulated using detailed CAD models of two mobile phones operating between 900 MHz and 1950 MHz including configurations with the hand holding the phone, which were not considered in most previous studies. The peak spatial-average specific absorption rate (psSAR) in the head and the pinna tissues is assessed using anatomically accurate head and hand models. The first of the two mentioned studies involved nine head-, four hand- and two phone-models, the second study included six head-, four hand- and three simplified phone-models (over 400 configurations in total). In addition, both studies also evaluated the exposure using the SAM phantom. Results show no systematic differences between psSAR induced in the adult and child heads. The exposure level and its variation for different age groups may be different for particular phones, but no correlation between psSAR and model age was found. The psSAR from all exposure conditions was compared to the corresponding configurations using SAM, which was found to be conservative in the large majority of cases. (paper)

Development of mathematical pediatric phantoms for internal dose calculations: designs, limitations, and prospects

International Nuclear Information System (INIS)

Cristy, M.

1980-01-01

Mathematical phantoms of the human body at various ages are employed with Monte Carlo radiation transport codes for calculation of photon specific absorbed fractions. The author has developed a pediatric phantom series based on the design of the adult phantom, but with explicit equations for each organ so that organ sizes and marrow distributions could be assigned properly. Since the phantoms comprise simple geometric shapes, predictive dose capability is limited when geometry is critical to the calculation. Hence, there is a demand for better phantom design in situations where geometry is critical, such as for external irradiation or for internal emitters with low energy photons. Recent advances in computerized axial tomography (CAT) present the potential for derivation of anatomical information, which is so critical to development of phantoms, and ongoing developmental work on compuer architecture to handle large arrays for Monte Carlo calculations should make complex-geometry dose calculations economically feasible within this decade

SU-F-T-292: Imaging and Radiation Oncology Core (IROC) Houston QA Center’s Anthropomorphic Phantom Program

International Nuclear Information System (INIS)

Mehrens, H; Lewis, B; Lujano, C; Nguyen, T; Hernandez, N; Alvarez, P; Molineu, A; Followill, D

2016-01-01

Purpose: To describe the results of IROC Houston’s international and domestic end-to-end QA phantom irradiations. Methods: IROC Houston has anthropomorphic lung, liver, head and neck, prostate, SRS and spine phantoms that are used for credentialing and quality assurance purposes. The phantoms include structures that closely mimic targets and organs at risk and are made from tissue equivalent materials: high impact polystyrene, solid water, cork and acrylic. Motion tables are used to mimic breathing motion for some lung and liver phantoms. Dose is measured with TLD and radiochromic film in various planes within the target of the phantoms. Results: The most common phantom requested is the head and neck followed by the lung phantom. The head and neck phantom was sent to 800 domestic and 148 international sites between 2011 and 2015, with average pass rates of 89% and 92%, respectively. During the past five years, a general upward trend exists regarding demand for the lung phantom for both international and domestic sites with international sites more than tripling from 5 (2011) to 16 (2015) and domestic sites doubling from 66 (2011) to 152 (2015). The pass rate for lung phantoms has been consistent from year to year despite this large increase in the number of phantoms irradiated with an average pass rate of 85% (domestic) and 95% (international) sites. The percentage of lung phantoms used in combination with motions tables increased from 38% to 79% over the 5 year time span. Conclusion: The number of domestic and international sites irradiating the head and neck and lung phantoms continues to increase and the pass rates remained constant. These end-to-end QA tests continue to be a crucial part of clinical trial credentialing and institution quality assurance. This investigation was supported by IROC grant CA180803 awarded by the NCI.

SU-F-T-292: Imaging and Radiation Oncology Core (IROC) Houston QA Center’s Anthropomorphic Phantom Program

Energy Technology Data Exchange (ETDEWEB)

Mehrens, H; Lewis, B; Lujano, C; Nguyen, T; Hernandez, N; Alvarez, P; Molineu, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

2016-06-15

Purpose: To describe the results of IROC Houston’s international and domestic end-to-end QA phantom irradiations. Methods: IROC Houston has anthropomorphic lung, liver, head and neck, prostate, SRS and spine phantoms that are used for credentialing and quality assurance purposes. The phantoms include structures that closely mimic targets and organs at risk and are made from tissue equivalent materials: high impact polystyrene, solid water, cork and acrylic. Motion tables are used to mimic breathing motion for some lung and liver phantoms. Dose is measured with TLD and radiochromic film in various planes within the target of the phantoms. Results: The most common phantom requested is the head and neck followed by the lung phantom. The head and neck phantom was sent to 800 domestic and 148 international sites between 2011 and 2015, with average pass rates of 89% and 92%, respectively. During the past five years, a general upward trend exists regarding demand for the lung phantom for both international and domestic sites with international sites more than tripling from 5 (2011) to 16 (2015) and domestic sites doubling from 66 (2011) to 152 (2015). The pass rate for lung phantoms has been consistent from year to year despite this large increase in the number of phantoms irradiated with an average pass rate of 85% (domestic) and 95% (international) sites. The percentage of lung phantoms used in combination with motions tables increased from 38% to 79% over the 5 year time span. Conclusion: The number of domestic and international sites irradiating the head and neck and lung phantoms continues to increase and the pass rates remained constant. These end-to-end QA tests continue to be a crucial part of clinical trial credentialing and institution quality assurance. This investigation was supported by IROC grant CA180803 awarded by the NCI.

Comparison of the local dose of scattered radiation of a special dental - phantom and a real human head by using a Digital Volume Tomography (DVT)

International Nuclear Information System (INIS)

Neuwirth, J.; Hefner, A.

2008-01-01

Dental Radiography Digital Volume Tomography (DVT) gains more and more importance due to its possibility of three-dimensional imaging of teeth, jaw and visercoranium and the reduced radiation dose in comparison to conventional Computer Tomography (CT). Contrary to other, well documented radiographic procedures like dental panorama X-ray imaging there are no national or international guidelines or recommendations relating to DVT which regulate the designation of areas and standardize risk assessment. This study aims to assess the parameters necessary for local radiation protection in dental practices. Measurements were carried out in dental practices in order to evaluate the local dose resulting from different DVT devices. A special dental-phantom and a real human head were used in the irradiations in order to define the local dose of scattered radiation by nominal voltage. The dental-phantom was created for conventional dental panorama X-ray devices which make use of lower nominal voltages. This poses the question if the scatter performance of the special dental-phantom is comparable to a real human head and therefore applicable to the estimation of the radiation quality of a DVT when using 120 kV. The existing guidelines for dental panorama xray are analyzed and suggestions for future recommendations concerning the designation of areas and risk assessment for DVT are then deducted by comparing both sets of measurements. The results show that the special dental-phantom is absolutely suitable for the definition of the local dose resulting from the scattered radiation of a DVT. (author)

The Japanese adult, child and infant phantoms

International Nuclear Information System (INIS)

Cristy, Mark; Egbert, Stephen D.

1987-01-01

The mathematical phantom for adult Japanese atomic-bomb survivors is a modification of the 57-kg ORNL (Oak Ridge National Laboratory) phantom for Western 15-year-old males and adult females. For younger Japanese survivors mathematical phantoms were similarly modified from the 18 and 9 kg ORNL phantoms for Western 5- and 1-year-olds, respectively. To make the phantom correspond more closely with dimensions and organ sizes recommended for Japanese adults by Maruyama and coworkers (cf E184), changes were made in the size of the lungs, the pancreas, the thyroid, and the testes and in the length of the legs. Also, the head-and-neck region was modified to improve the dose estimates for the thyroid from external radiation, after the ideas of Nagarajan et al. The arms were separated from the trunk to represent more accurately the shielding by the phantom in external exposures. Furthermore, provisions were made to provide a phantom in a kneeling posture. The elemental composition of the tissues was changed to that given by Kerr. The resulting phantom is slightly smaller in mass (55 kg). Details of these changes are given

Quantitative analysis of orthopedic metal artefact reduction in 64-slice computed tomography scans in large head metal-on-metal total hip replacement, a phantom study

NARCIS (Netherlands)

Boomsma, Martijn F.; Warringa, Niek; Edens, Mireille A.; Mueller, Dirk; Ettema, Harmen B.; Verheyen, Cees C. P. M.; Maas, Mario

2016-01-01

Purpose: Quantification of the effect of O-MAR on decreasing metal artefacts caused by large head metal on metal total hip arthroplasty (MoM THA) in a dedicated phantom setup of the hip. Background: Pathological reactions of the hip capsule on Computed tomography (CT) can be difficult to diagnose

MO-C-17A-05: A Three-Dimensional Head-And-Neck Phantom for Validation of Kilovoltage- and Megavoltage-Based Deformable Image Registration

International Nuclear Information System (INIS)

Kirby, N; Singhrao, K; Pouliot, J

2014-01-01

Purpose: To develop a three-dimensional (3D) deformable head-and-neck (H and N) phantom with realistic tissue contrast for both kilovoltage and megavoltage computed tomography and use it to objectively evaluate deformable image registration (DIR) algorithms. Methods: The phantom represents H and N patient anatomy. It is constructed from thermoplastic, which becomes pliable in boiling water, and hardened epoxy resin. Using a system of additives, the Hounsfield unit (HU) values of these materials were tuned to mimic anatomy for both kilovoltage (kV) and megavoltage (MV) imaging. The phantom opened along a sagittal midsection to reveal nonradiopaque markers, which were used to characterize the phantom deformation. The deformed and undeformed phantom was scanned with kV and MV computed tomography. Additionally, a calibration curve was created to change the HUs of the MV scans to be similar to kV HUs, (MC). The extracted ground-truth deformation was then compared to the results of two commercially available DIR algorithms, from Velocity Medical Solutions and MIM Software. Results: The phantom produced a 3D deformation, representing neck flexion, with a magnitude of up to 8 mm and was able represent tissue HUs for both kV and MV imaging modalities. The two tested deformation algorithms yielded vastly different results. For kV-kV registration, MIM made the lowest mean error, and Velocity made the lowest maximum error. For MV-MV, kV-MV, and kV-MC Velocity produced both the lowest mean and lowest maximum errors. Conclusion: The application of DIR across different imaging modalities is particularly difficult, due to differences in tissue HUs and the presence of imaging artifacts. For this reason, DIR algorithms must be validated specifically for this purpose. The developed H and N phantom is an effective tool for this purpose

Neurosurgical operating computerized tomographic scanner system. The CT scanner in the operating theater

Energy Technology Data Exchange (ETDEWEB)

Okudera, Hiroshi; Sugita, Kenichiro; Kobayashi, Shigeaki; Kimishima, Sakae; Yoshida, Hisashi

1988-12-01

A neurosurgical operating computerized tomography scanner system is presented. This system has been developed for obtaining intra- and postoperative CT images in the operating room. A TCT-300 scanner (manufactured by the Toshiba Co., Tokyo) is placed in the operating room. The realization of a true intraoperative CT image requires certain improvements in the CT scanner and operating table. To adjust the axis of the co-ordinates of the motor system of the MST-7000 microsurgical operating table (manufactured by the Mizuho Ika Co., Tokyo) to the CT scanner, we have designed an interface and a precise motor system so that the computer of the CT scanner can directly control the movement of the operating table. Furthermore, a new head-fixation system has been designed for producing artifact-free intraoperative CT images. The head-pins of the head-fixation system are made of carbon-fiber bars and titanium tips. A simulation study of the total system in the operating room with the CT scanner, operating table, and head holder using a skull model yielded a degree of error similar to that in the phantom testing of the original scanner. Three patients underwent resection of a glial tumor using this system. Intraoperative CT scans taken after dural opening showed a bulging of the cortex, a shift in the central structure, and a displacement of the cortical subarachnoid spaces under the influence of gravity. With a contrast medium the edge of the surrounding brain after resection was enhanced and the residual tumor mass was demonstrated clearly. This system makes it possible to obtain a noninvasive intraoperative image in a situation where structural shifts are taking place.

Wireless Performance of a Fully Passive Neurorecording Microsystem Embedded in Dispersive Human Head Phantom

Science.gov (United States)

Schwerdt, Helen N.; Chae, Junseok; Miranda, Felix A.

2012-01-01

This paper reports the wireless performance of a biocompatible fully passive microsystem implanted in phantom media simulating the dispersive dielectric properties of the human head, for potential application in recording cortical neuropotentials. Fully passive wireless operation is achieved by means of backscattering electromagnetic (EM) waves carrying 3rd order harmonic mixing products (2f(sub 0) plus or minus f(sub m)=4.4-4.9 GHZ) containing targeted neuropotential signals (fm approximately equal to 1-1000 Hz). The microsystem is enclosed in 4 micrometer thick parylene-C for biocompatibility and has a footprint of 4 millimeters x 12 millimeters x 500 micrometers. Preliminary testing of the microsystem implanted in the lossy biological simulating media results in signal-to-noise ratio's (SNR) near 22 (SNR approximately equal to 38 in free space) for millivolt level neuropotentials, demonstrating the potential for fully passive wireless microsystems in implantable medical applications.

Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis

International Nuclear Information System (INIS)

Negus, Ian S.; Holmes, Robin B.; Thorne, Gareth C.; Saunders, Margaret; Jordan, Kirsty C.; Nash, David A.

2016-01-01

Purpose: To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. Methods: A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain by adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding 99m Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Results: Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. Conclusions: The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable for

Technical Note: Development of a 3D printed subresolution sandwich phantom for validation of brain SPECT analysis

Energy Technology Data Exchange (ETDEWEB)

Negus, Ian S.; Holmes, Robin B.; Thorne, Gareth C.; Saunders, Margaret [Department of Medical Physics and Bioengineering, University Hospitals Bristol NHS Foundation Trust, Bristol BS28HW (United Kingdom); Jordan, Kirsty C. [Department of Biomedical Engineering, University of Strathclyde, Glasgow G11XQ (United Kingdom); Nash, David A. [Department of Medical Physics, Portsmouth Hospitals NHS Trust, Portsmouth PO63LY (United Kingdom)

2016-09-15

Purpose: To make an adaptable, head shaped radionuclide phantom to simulate molecular imaging of the brain using clinical acquisition and reconstruction protocols. This will allow the characterization and correction of scanner characteristics, and improve the accuracy of clinical image analysis, including the application of databases of normal subjects. Methods: A fused deposition modeling 3D printer was used to create a head shaped phantom made up of transaxial slabs, derived from a simulated MRI dataset. The attenuation of the printed polylactide (PLA), measured by means of the Hounsfield unit on CT scanning, was set to match that of the brain by adjusting the proportion of plastic filament and air (fill ratio). Transmission measurements were made to verify the attenuation of the printed slabs. The radionuclide distribution within the phantom was created by adding {sup 99m}Tc pertechnetate to the ink cartridge of a paper printer and printing images of gray and white matter anatomy, segmented from the same MRI data. The complete subresolution sandwich phantom was assembled from alternate 3D printed slabs and radioactive paper sheets, and then imaged on a dual headed gamma camera to simulate an HMPAO SPECT scan. Results: Reconstructions of phantom scans successfully used automated ellipse fitting to apply attenuation correction. This removed the variability inherent in manual application of attenuation correction and registration inherent in existing cylindrical phantom designs. The resulting images were assessed visually and by count profiles and found to be similar to those from an existing elliptical PMMA phantom. Conclusions: The authors have demonstrated the ability to create physically realistic HMPAO SPECT simulations using a novel head-shaped 3D printed subresolution sandwich method phantom. The phantom can be used to validate all neurological SPECT imaging applications. A simple modification of the phantom design to use thinner slabs would make it suitable

SU-E-T-87: Comparison Study of Dose Reconstruction From Cylindrical Diode Array Measurements, with TLD Measurements and Treatment Planning System Calculations in Anthropomorphic Head and Neck and Lung Phantoms

Energy Technology Data Exchange (ETDEWEB)

Benhabib, S; Cardan, R; Huang, M; Brezovich, I; Popple, R [University of Alabama at Birmingham, Birmingham, AL (United States); Faught, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

2014-06-01

Purpose: To assess dose calculated by the 3DVH software (Sun Nuclear Systems, Melbourne, FL) against TLD measurements and treatment planning system calculations in anthropomorphic phantoms. Methods: The IROC Houston (RPC) head and neck (HN) and lung phantoms were scanned and plans were generated using Eclipse (Varian Medical Systems, Milpitas, CA) following IROC Houston procedures. For the H and N phantom, 6 MV VMAT and 9-field dynamic MLC (DMLC) plans were created. For the lung phantom 6 MV VMAT and 15 MV 9-field dynamic MLC (DMLC) plans were created. The plans were delivered to the phantoms and to an ArcCHECK (Sun Nuclear Systems, Melbourne, FL). The head and neck phantom contained 8 TLDs located at PTV1 (4), PTV2 (2), and OAR Cord (2). The lung phantom contained 4 TLDs, 2 in the PTV, 1 in the cord, and 1 in the heart. Daily outputs were recorded before each measurement for correction. 3DVH dose reconstruction software was used to project the calculated dose to patient anatomy. Results: For the HN phantom, the maximum difference between 3DVH and TLDs was -3.4% and between 3DVH and Eclipse was 1.2%. For the lung plan the maximum difference between 3DVH and TLDs was 4.3%, except for the spinal cord for which 3DVH overestimated the TLD dose by 12%. The maximum difference between 3DVH and Eclipse was 0.3%. 3DVH agreed well with Eclipse because the dose reconstruction algorithm uses the diode measurements to perturb the dose calculated by the treatment planning system; therefore, if there is a problem in the modeling or heterogeneity correction, it will be carried through to 3DVH. Conclusion: 3DVH agreed well with Eclipse and TLD measurements. Comparison of 3DVH with film measurements is ongoing. Work supported by PHS grant CA10953 and CA81647 (NCI, DHHS)

Effect of titanium dental implants on proton therapy delivered for head tumors: experimental validation using an anthropomorphic head phantom

Science.gov (United States)

Oancea, C.; Shipulin, K.; Mytsin, G.; Molokanov, A.; Niculae, D.; Ambrožová, I.; Davídková, M.

2017-03-01

A dosimetric experiment was performed at the Medico-Technical Complex in the Joint Institute for Nuclear Research, Dubna, to investigate the effects of metallic dental implants in the treatment of head and neck tumours with proton therapy. The goal of the study was to evaluate the 2D dose distributions of different clinical treatment plans measured in an anthropomorphic phantom, and compare them to predictions from a treatment planning system. The anthropomorphic phantom was sliced into horizontal segments. Two grade 4 Titanium implants were inserted between 2 slices, corresponding to a maxillary area. GafChromic EBT2 films were placed between the segments containing the implants to measure the 2D delivered dose. Two different targets were designed: the first target includes the dental implants in the isocentre, and in the second target, the proton beam is delivered through the implants, which are located at the entrance region of the Bragg curve. The experimental results were compared to the treatment plans made using our custom 3D Treatment Planning System, named RayTreat. To quantitatively determine differences in the isodose distributions (measured and calculated), the gamma index (3 mm, 3%) was calculated for each target for the matrix value in the region of high isodose (> 90%): for the experimental setup, which includes the implants in the SOBP region, the result obtained was 84.3%. When the implants were localised in the entrance region of the Bragg curve, the result obtained was 86.4%. In conclusion, the uncertainties introduced by the clinically planned dose distribution are beyond reasonable limits. The linear energy transfer spectra in close proximity to the implants were investigated using solid state nuclear track detectors (TED). Scattered particles outside the target were detected.

Effect of titanium dental implants on proton therapy delivered for head tumors: experimental validation using an anthropomorphic head phantom

International Nuclear Information System (INIS)

Oancea, C.; Shipulin, K.; Mytsin, G.; Molokanov, A.; Niculae, D.; Ambrožová, I.; Davídková, M.

2017-01-01

A dosimetric experiment was performed at the Medico-Technical Complex in the Joint Institute for Nuclear Research, Dubna, to investigate the effects of metallic dental implants in the treatment of head and neck tumours with proton therapy. The goal of the study was to evaluate the 2D dose distributions of different clinical treatment plans measured in an anthropomorphic phantom, and compare them to predictions from a treatment planning system. The anthropomorphic phantom was sliced into horizontal segments. Two grade 4 Titanium implants were inserted between 2 slices, corresponding to a maxillary area. GafChromic EBT2 films were placed between the segments containing the implants to measure the 2D delivered dose. Two different targets were designed: the first target includes the dental implants in the isocentre, and in the second target, the proton beam is delivered through the implants, which are located at the entrance region of the Bragg curve. The experimental results were compared to the treatment plans made using our custom 3D Treatment Planning System, named RayTreat. To quantitatively determine differences in the isodose distributions (measured and calculated), the gamma index (3 mm, 3%) was calculated for each target for the matrix value in the region of high isodose (> 90%): for the experimental setup, which includes the implants in the SOBP region, the result obtained was 84.3%. When the implants were localised in the entrance region of the Bragg curve, the result obtained was 86.4%. In conclusion, the uncertainties introduced by the clinically planned dose distribution are beyond reasonable limits. The linear energy transfer spectra in close proximity to the implants were investigated using solid state nuclear track detectors (TED). Scattered particles outside the target were detected.

Computerized tomographic visualization of niveau by turning the head in a case of pituitary apoplexy

International Nuclear Information System (INIS)

Sasajima, Toshio; Mineura, Katsuyoshi; Kowada, Masayoshi; Sasaki, Junko; Sasajima, Hiroyasu; Sakamoto, Tetsuya

1987-01-01

A case of pituitary apoplexy is presented in which a free niveau formation, a pathognomonic sign of this entity, was proved by means of computerized tomography (CT) by turning the head. A 48-year-old female had developed a sudden, excruciating, retroorbital headache, vomiting, and visual disturbance twice prior to admission. The visual acuity was 0.1 in the right eye and 0.6 in the left eye. The optic fundi were normal. There was a right temporal field loss and a left upper temporal quadrantanopsia. A plain skull film disclosed ballooning and a double floor of the turcic sella. A CT scan of the head, performed by means of a GE CT/T 8800 Scanner, showed an intrasellar low-density mass with a slightly enhanced rim. We were not convinced of the presence of a high-density area, though there seemed to be one adjacent to the posterior clinoid process and the turcic floor, because of the partial volume effect and the artifact related to the neighboring bones. Another high-resolution CT scan on the ensuing day, as the head was turned and then kept still at about 45 degrees to the right, while the patient was supine, for ten minutes, made it possible to visualize a free fluid level, comparable to a fluid-blood-density level. A transsphenoidal pituitary exploration identified blood fluid collection in the encapsulated tumor, a finding which was histologically consistent with the sinusoidal type of chromophobe adenoma. There was some microscopic evidence of necrosis and hemosiderin laden cells. The postoperative course was uneventful; visual acuity improved without delay, and the temporal field defect became significantly smaller. Two weeks later, visual acuity had recovered to 1.2 uncorrected in each eye. CT and the pertinent position of the head might be quite helpful for the visualization and confirmation of a subtle free fluid level in cases of pituitary apoplexy. (author)

Prognosis of the computerized tomography in the severe head injury. Valor pronostico de la tomografia axial computada (TC) en los traumatismos craneoencefalicos severos

Energy Technology Data Exchange (ETDEWEB)

Garcia-Nieto, J.J.; Lorenzo Dominguez, M.T.; Martin Sanchez, M.J.; Sanchez Gonzalez, E.

1991-01-01

A prospective study is made with sixty five people affected of severe head injury, that is to say, with eight or less points in the Glasgow Coma Scale (GCS), when they get to the hospital. They are studied by computerized tomography at admission, and three and seven days after arrival. In this way, we appraise the type of the lesion, its intensity and the possible prognosis, considering in the last case three features: a) ventricular collapse; b) the mean line structure s shift; and c) effects on perimesencephalic cistern. The findings were parametized and we were able to introduce into the computer program relationships between these findings and the end results. These last ones were appraised through the Glasgow Outcome Scale (GOS). We could show that certain findings in computerized tomography scans have an unavoidable prognosis while as others have a more favorable prognosis. (Author)

Positron emission computerized tomography: a potential tool for in vivo quantitation of the distribution of radiopharmaceuticals

International Nuclear Information System (INIS)

Huebner, K.F.; King, P.; Gibbs, W.D.; Washburn, L.C.; Hayes, R.L.

1981-01-01

The principles and some of the difficulties in quantitative positron emission computerized tomography have been discussed. We have shown that randoms and scattered events are a major cause of noise and counting errors in positron emission computerized tomography. The noise has been identified as a convoluting process and a mathematical solution has been presented. Examples of phantom studies and in vivo measurements have demonstrated that the distribution of positron emitting radiopharmaceuticals can be quantitated with much improved accuracy using the deconvolution equation to remove undesired noise

Thirteen-Year Evaluation of Highly Cross-Linked Polyethylene Articulating With Either 28-mm or 36-mm Femoral Heads Using Radiostereometric Analysis and Computerized Tomography

DEFF Research Database (Denmark)

Nebergall, Audrey K; Greene, Meridith E; Rubash, Harry E

2016-01-01

BACKGROUND: The objective of this 13-year prospective evaluation of highly cross-linked ultra high molecular weight polyethylene (HXLPE) was to (1) assess the long-term wear of HXLPE articulating with 2 femoral head sizes using radiostereometric analysis (RSA) and to (2) determine if osteolysis...... is a concern with this material through the use of plain radiographs and computerized tomography (CT). METHODS: All patients received a Longevity HXLPE liner with tantalum beads and either a 28-mm or 36-mm femoral head. Twelve patients (6 in each head size group) agreed to return for 13-year RSA, plain...... scan revealed areas of remodeling of this graft. One patient's 13-year plain radiographs showed evidence of cup loosening and linear radiolucencies in zones 2 and 3. CONCLUSION: There was no evidence of significant wear over time using RSA. The CT scans did not show evidence of osteolysis due to wear...

Phantoms for IMRT dose distribution measurement and treatment verification

International Nuclear Information System (INIS)

Low, Daniel A.; Gerber, Russell L.; Mutic, Sasa; Purdy, James A.

1998-01-01

Background: The verification of intensity-modulated radiation therapy (IMRT) patient treatment dose distributions is currently based on custom-built or modified dose measurement phantoms. The only commercially available IMRT treatment planning and delivery system (Peacock, NOMOS Corp.) is supplied with a film phantom that allows accurate spatial localization of the dose distribution using radiographic film. However, measurements using other dosimeters are necessary for the thorough verification of IMRT. Methods: We have developed a phantom to enable dose measurements using a cylindrical ionization chamber and the localization of prescription isodose curves using a matrix of thermoluminescent dosimetry (TLD) chips. The external phantom cross-section is identical to that of the commercial phantom, to allow direct comparisons of measurements. A supplementary phantom has been fabricated to verify the IMRT dose distributions for pelvis treatments. Results: To date, this phantom has been used for the verification of IMRT dose distributions for head and neck and prostate cancer treatments. Designs are also presented for a phantom insert to be used with polymerizing gels (e.g., BANG-2) to obtain volumetric dose distribution measurements. Conclusion: The phantoms have proven useful in the quantitative evaluation of IMRT treatments

A phantom-based study for assessing the error and uncertainty of a neuronavigation system

Directory of Open Access Journals (Sweden)

Natalia Izquierdo-Cifuentes

2017-01-01

Full Text Available This document describes a calibration protocol with the intention to introduce a guide to standardize the metrological vocabulary among manufacturers of image-guided surgery systems. Two stages were developed to measure the errors and estimate the uncertainty of a neuronavigator in different situations, on the first one it was determined a mechanical error on a virtual model of an acrylic phantom, on the second it was determined a coordinate error on the computerized axial tomography scan of the same phantom. Ten standard coordinates of the phantom were compared with the coordinates generated by the NeuroCPS. After measurement model was established, there were identified the sources of uncertainty and the data was processed according the guide to the expression of uncertainty in measurement.

SU-F-T-168: Development and Implementation of An Anthropomorphic Head & Neck Phantom for the Assessment of Proton Therapy Treatment Procedures

Energy Technology Data Exchange (ETDEWEB)

Branco, D; Taylor, P; Frank, S; Li, H; Zhang, X; Mehrens, H; Guindani, M; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

2016-06-15

Purpose: To design a Head and Neck (H&N) anthropomorphic QA phantom that the Imaging and Radiation Oncology Core Houston (IROC-H) can use to verify the quality of intensity modulated proton therapy (IMPT) H&N treatments for institutions participating in NCI clinical trials. Methods: The phantom was created to serve as a remote auditing tool for IROC-H to evaluate an institution’s IMPT planning and delivery abilities. The design was based on the composition, size, and geometry of a generalized oropharyngeal tumor and contains critical structures (parotids and spinal cord). Radiochromic film in the axial and sagittal planes and thermoluminescent dosimeters (TLD)-100 capsules were embedded in the phantom and used to perform the dose delivery evaluation. A CT simulation was used to create a passive scatter and a spot scanning treatment plan with typical clinical constraints for H&N cancer. The IMPT plan was approved by a radiation oncologist and the phantom was irradiated multiple times. The measured dose distribution using a 7%/4mm gamma analysis (85% of pixels passing) and point doses were compared with the treatment planning system calculations. Results: The designed phantom could not achieve the target dose prescription and organ at risk dose constraints with the passive scatter treatment plan. The target prescription dose could be met but not the parotid dose constraint. The average TLD point dose ratio in the target was 0.975, well within the 5% acceptance criterion. The dose distribution analysis using various acceptance criteria, 5%/4mm, 5%/3mm, 7%/4mm and 7%/5mm, had average pixel passing rates of 85.9%, 81.8%, 89.6% and 91.6%, and respectively. Conclusion: An anthropomorphic IMPT H&N phantom was designed that can assess the dose delivery of proton sites wishing to participate in clinical trials using a 5% TLD dose and 7%/4mm gamma analysis acceptance criteria.

Field size dependence of wedge factor: miniphantom vs full phantom measurements

International Nuclear Information System (INIS)

Allen Li, X.; Szanto, J.; Soubra, M.; Gerig, L. H.

1995-01-01

It is empirically known that the transmission factor for wedge in a high-energy photon beam is dependent upon field size and depth of measurement. The field-size dependence of wedge factors may be attributed to changes in (i) head scatter, (ii) phantom scatter, and (iii) backscatter from the wedge into the linac monitor chamber. In this work we present the results of studies designed to examine each of these factors in isolation. The wedge factors for wedges with nominal wedge angles of 15 deg. , 30 deg. , 45 deg. and 60 deg. were measured with a 3-g/cm 2 -diameter narrow cylindrical phantom (miniphantom), a brass cap with 1.5-g/cm 2 side-wall thickness and a full water phantom for 6-, 10- and 18-MV photon beams. The measurements were performed with and without flattening filter in place. The wedge factors measured with the miniphantom and the brass cap exclude the phantom scatter contribution. It has been found that the field-size behaviour of wedge factor measured with full water phantom is similar to that measured with the miniphantom and cap. This indicates that the head scatter radiation is the major contributor to the field size dependence of wedge factors. Wedge factors measured with water phantom are up to 5.0% smaller than those measured with miniphantom. This difference increases with wedge angle. When Measured with the flattening filter removed, the field size dependence of the wedge factor is reduced. This justify that the flattening filter is one of the major contributors to head scatters. The measurement results made with the brass cap agree well with those made by using the miniphantom. By measuring the monitor chamber output, it is found that the backscatters from the wedge into the linac ion chamber have little effect on the field size dependence of the wedge factor

Whole-body voxel phantoms of paediatric patients—UF Series B

Science.gov (United States)

Lee, Choonik; Lee, Choonsik; Williams, Jonathan L.; Bolch, Wesley E.

2006-09-01

Following the previous development of the head and torso voxel phantoms of paediatric patients for use in medical radiation protection (UF Series A), a set of whole-body voxel phantoms of paediatric patients (9-month male, 4-year female, 8-year female, 11-year male and 14-year male) has been developed through the attachment of arms and legs from segmented CT images of a healthy Korean adult (UF Series B). Even though partial-body phantoms (head-torso) may be used in a variety of medical dose reconstruction studies where the extremities are out-of-field or receive only very low levels of scatter radiation, whole-body phantoms play important roles in general radiation protection and in nuclear medicine dosimetry. Inclusion of the arms and legs is critical for dosimetry studies of paediatric patients due to the presence of active bone marrow within the extremities of children. While the UF Series A phantoms preserved the body dimensions and organ masses as seen in the original patients who were scanned, comprehensive adjustments were made for the Series B phantoms to better match International Commission on Radiological Protection (ICRP) age-interpolated reference body masses, body heights, sitting heights and internal organ masses. The CT images of arms and legs of a Korean adult were digitally rescaled and attached to each phantom of the UF series. After completion, the resolutions of the phantoms for the 9-month, 4-year, 8-year, 11-year and 14-year were set at 0.86 mm × 0.86 mm × 3.0 mm, 0.90 mm × 0.90 mm × 5.0 mm, 1.16 mm × 1.16 mm × 6.0 mm, 0.94 mm × 0.94 mm × 6.00 mm and 1.18 mm × 1.18 mm × 6.72 mm, respectively.

Specific developed phantoms and software to assess radiological equipment image quality

International Nuclear Information System (INIS)

Verdu, G.; Rodenas, F.

2011-01-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

Specific developed phantoms and software to assess radiological equipment image quality

Energy Technology Data Exchange (ETDEWEB)

Verdu, G., E-mail: gverdu@iqn.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Ingenieria Quimica y Nuclear; Mayo, P., E-mail: p.mayo@titaniast.com [TITANIA Servicios Teconologicos, Valencia (Spain); Rodenas, F., E-mail: frodenas@mat.upv.es [Universidad Politecnica de Valencia (Spain). Dept. de Matematica Aplicada; Campayo, J.M., E-mail: j.campayo@lainsa.com [Logistica y Acondicionamientos Industriales S.A.U (LAINSA), Valencia (Spain)

2011-07-01

The use of radiographic phantoms specifically designed to evaluate the operation of the radiographic equipment lets the study of the image quality obtained by this equipment in an objective way. In digital radiographic equipment, the analysis of the image quality can be automatized because the acquisition of the image is possible in different technologies that are, computerized radiography or phosphor plate and direct radiography or detector. In this work we have shown an application to assess automatically the constancy quality image in the image chain of the radiographic equipment. This application is integrated by designed radiographic phantoms which are adapted to conventional, dental equipment and specific developed software for the automatic evaluation of the phantom image quality. The software is based on digital image processing techniques that let the automatic detection of the different phantom tests by edge detector, morphological operators, threshold histogram techniques, etc. The utility developed is enough sensitive to the radiographic equipment of operating conditions of voltage (kV) and charge (mAs). It is a friendly user programme connected with a data base of the hospital or clinic where it has been used. After the phantom image processing the user can obtain an inform with a resume of the imaging system state with accepting and constancy results. (author)

Analysis of translational errors in frame-based and frameless cranial radiosurgery using an anthropomorphic phantom

Energy Technology Data Exchange (ETDEWEB)

Almeida, Taynna Vernalha Rocha [Faculdades Pequeno Principe (FPP), Curitiba, PR (Brazil); Cordova Junior, Arno Lotar; Almeida, Cristiane Maria; Piedade, Pedro Argolo; Silva, Cintia Mara da, E-mail: taynnavra@gmail.com [Centro de Radioterapia Sao Sebastiao, Florianopolis, SC (Brazil); Brincas, Gabriela R. Baseggio [Centro de Diagnostico Medico Imagem, Florianopolis, SC (Brazil); Marins, Priscila; Soboll, Danyel Scheidegger [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil)

2016-03-15

Objective: To evaluate three-dimensional translational setup errors and residual errors in image-guided radiosurgery, comparing frameless and frame-based techniques, using an anthropomorphic phantom. Materials and Methods: We initially used specific phantoms for the calibration and quality control of the image-guided system. For the hidden target test, we used an Alderson Radiation Therapy (ART)-210 anthropomorphic head phantom, into which we inserted four 5- mm metal balls to simulate target treatment volumes. Computed tomography images were the taken with the head phantom properly positioned for frameless and frame-based radiosurgery. Results: For the frameless technique, the mean error magnitude was 0.22 ± 0.04 mm for setup errors and 0.14 ± 0.02 mm for residual errors, the combined uncertainty being 0.28 mm and 0.16 mm, respectively. For the frame-based technique, the mean error magnitude was 0.73 ± 0.14 mm for setup errors and 0.31 ± 0.04 mm for residual errors, the combined uncertainty being 1.15 mm and 0.63 mm, respectively. Conclusion: The mean values, standard deviations, and combined uncertainties showed no evidence of a significant differences between the two techniques when the head phantom ART-210 was used. (author)

Phantoms for Radiation Measurements of Mobile Phones

DEFF Research Database (Denmark)

Pedersen, Gert Frølund

2001-01-01

Measurements of radiation efficiency for a handheld phone equipped with a patch and a helical antenna operated near the human user have been performed. Both measurements include a simple head plus hand phantom and live persons are considered. The position of the hand on the phone is found...... to be the main reason for the large variation in radiation efficiency among persons. The tilt angle of the phone and the distance between the head and phone only play a minor role...

Phantom dosimetry at 15 MV conformal radiation therapy

International Nuclear Information System (INIS)

Thompson, Larissa; Campos, Tarcisio P.R.; Dias, Humberto G.

2013-01-01

The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)

Phantom dosimetry at 15 MV conformal radiation therapy

International Nuclear Information System (INIS)

Thompson, Larissa; Campos, Tarcisio P.R.

2015-01-01

The main goal of this work was to evaluate the spatial dose distribution into a tumor simulator inside a head phantom exposed to a 15MV 3D conformal radiation therapy in order to validate internal doses. A head and neck phantom developed by the Ionizing Radiation Research Group (NRI) was used on the experiments. Therapy Radiation planning (TPS) was performed based on those CT images, satisfying a 200 cGy prescribed dose split in three irradiation fields. The TPS assumed 97% of prescribed dose cover the prescribed treatment volume (PTV). Radiochromic films in a solid water phantom provided dose response as a function of optical density. Spatial dosimetric distribution was generated by radiochromic film samples inserted into tumor simulator and brain. The spatial dose profiles held 70 to 120% of the prescribed dose. In spite of the stratified profile, as opposed to the smooth dose profile from TPS, the tumor internal doses were within a 5% deviation from 214.4 cGy evaluated by TPS. 83.2% of the points with a gamma value of less than 1 (3%/3mm) for TPS and experimental values, respectively. At the tumor, a few dark spots in the film caused the appearance of outlier points in 13-15% of dose deviation percentage. As final conclusion, such dosimeter choice and the physical anthropomorphic and anthropometric phantom provided an efficient method for validating radiotherapy protocols. (author)

Initial investigation of a novel light-scattering gel phantom for evaluation of optical CT scanners for radiotherapy gel dosimetry

International Nuclear Information System (INIS)

Bosi, Stephen; Naseri, Pourandokht; Puran, Alicia; Davies, Justin; Baldock, Clive

2007-01-01

There is a need for stable gel materials for phantoms used to validate optical computerized tomography (CT) scanners used in conjunction with radiation-induced polymerizing gel dosimeters. Phantoms based on addition of light-absorbing dyes to gelatine to simulate gel dosimeters have been employed. However, to more accurately simulate polymerizing gels one requires phantoms that employ light-scattering colloidal suspensions added to the gel. In this paper, we present the initial results of using an optical CT scanner to evaluate a novel phantom in which radiation-exposed polymer gels are simulated by the addition of colloidal suspensions of varying turbidity. The phantom may be useful as a calibration transfer standard for polymer gel dosimeters. The tests reveal some phenomena peculiar to light-scattering gels that need to be taken into account when calibrating polymer gel dosimeters

Fabrication and characterization of a 3-D non-homogeneous tissue-like mouse phantom for optical imaging

Science.gov (United States)

Avtzi, Stella; Zacharopoulos, Athanasios; Psycharakis, Stylianos; Zacharakis, Giannis

2013-11-01

In vivo optical imaging of biological tissue not only requires the development of new theoretical models and experimental procedures, but also the design and construction of realistic tissue-mimicking phantoms. However, most of the phantoms available currently in literature or the market, have either simple geometrical shapes (cubes, slabs, cylinders) or when realistic in shape they use homogeneous approximations of the tissue or animal under investigation. The goal of this study is to develop a non-homogeneous realistic phantom that matches the anatomical geometry and optical characteristics of the mouse head in the visible and near-infrared spectral range. The fabrication of the phantom consisted of three stages. Initially, anatomical information extracted from either mouse head atlases or structural imaging modalities (MRI, XCT) was used to design a digital phantom comprising of the three main layers of the mouse head; the brain, skull and skin. Based on that, initial prototypes were manufactured by using accurate 3D printing, allowing complex objects to be built layer by layer with sub-millimeter resolution. During the second stage the fabrication of individual molds was performed by embedding the prototypes into a rubber-like silicone mixture. In the final stage the detailed phantom was constructed by loading the molds with epoxy resin of controlled optical properties. The optical properties of the resin were regulated by using appropriate quantities of India ink and intralipid. The final phantom consisted of 3 layers, each one with different absorption and scattering coefficient (μa,μs) to simulate the region of the mouse brain, skull and skin.

A custom made phantom for dosimetric audit and quality assurance of three-dimensional conformal radiotherapy

International Nuclear Information System (INIS)

Radaideh, K.M.; Matalqah, L.M.; Matalqah, L.M.; Tajuddin, A.A.; Luen, F.W.L.; Bauk, S.; Abdel Munem, E.M.E.

2012-01-01

The ultimate check of the actual dose delivered to a patient in radiotherapy can be achieved by using dosimetric measurements. The aims of this study were to develop and evaluate a custom handmade head and neck phantom for evaluation of Three-Dimensional Conformal Radiation Therapy (3D-CRT) dose planning and delivery. A phantom of head and neck region of a medium built male patient with nasopharyngeal cancer was constructed from Perspex material. Primary and secondary Planning Target Volume (PTV) and twelve Organs at Risk (OAR) were delineated using Treatment Planning System (TPS) guided by computed tomography printout transverse images. One hundred and seven (107) holes distributed among the organs were loaded with Rod-shaped Thermoluminescent dosimeters (LiF:Mg, Ti TLDs) after common and individual calibration. Head and neck phantom was imaged, planned and irradiated conformally (3D-CRT) by linear accelerator (LINAC Siemens Artiste). The planned predicted doses by TPS at PTV and OAR regions were obtained and compared with the TLD measured doses using the phantom. Repeated TLD measurements were reproducible with a percent standard deviation of < 3.5 %. Moreover, the average of dose discrepancies between TLDs reading and TPS predicted doses were found to be < 5.3 %. The phantom's preliminary results have proved to be a valuable tool for 3D-CRT treatment dose verification. (author)

Computerized portable microwave hyperthermia quality assurance kit

International Nuclear Information System (INIS)

Cheung, A.Y.; Neyzari, A.

1985-01-01

A computerized quality assurance kit to provide precise measurement and calibration of microwave power and temperature, as well as capabilities to map SAR (Specific absorption rate) distribution in phantoms; and survey of hazardous microwave leakage has been designed. The kit is also capable of performing corelation studies on the relationship between SAR and net microwave power delivered at various anatomical sites. The kit consists of a portable microcomputer, a time-multiplexed A/D converter, a 4-channel dual directional microwave power monitor, a 4-channel thin-wire thermocouple thermometry system, an electronic thermal calibrator, a microwave leakage hazard survey meter, and a dynamic phantom tank for dosimetric analysis. Comparative performance studies were made against NBS-traceable power and temperature standards, non-perturbing optical temperature sensors, and established power and temperature measurement devices. The test results indicate that this instrument is providing its user with measurement accuracy of 0.1 0 C in temperature, 10% accuracy in power. The thin-wire thermocouple, with computer assisted error compensation, performs equally well in a strong microwave field in comparison with non-perturbing optical temperature sensors

Patient surface doses in computerized tomography examinations

International Nuclear Information System (INIS)

Vekic, B; Kovacevic, S.; Ranogajec-Komor, M.; Duvnjak, N.; Marusic, P.; Anic, P.; Dolencic, P.

1996-01-01

The diagnostic value of computerized tomography has increased due to very rapid technical advances in both equipment and techniques. When the CT scanners were introduced, a significant problem for the specification of the radiation dose imparted to the patient undergoing CT examination has been created. In CT, the conditions of exposure are quite different from those in conventional X-ray imaging. CT procedure involves the continuous tomography of thin layers. Some of these layers touch each other while others overlap. The radiation doses received by patients can vary considerably. In addition to the radiation from the collimated primary beam, patients are exposed to significant scattered doses in unpredictable amounts. Every effort should be made to keep these doses to a reasonable minimum, without sacrificing the image quality. The aims of this work were to determine the surface doses delivered to various organs of patients during various computerized tomography examinations (head, thorax, kidney, abdomen and pelvis). Particular attention was directed to the precise determination of doses received by the eyes (during CT of head) and gonads (during CT of pelvis and lower abdomen) since these organs can be near or even in the primary X-ray beam

Evaluation of the absorbed dose in odontological computerized tomography; Avaliacao da dose absorvida em tomografia computadorizada odontologica

Energy Technology Data Exchange (ETDEWEB)

Legnani, Adriano; Schelin, Hugo R; Rocha, Anna Silvia P.S. da, E-mail: schelin@utfpr.edu.b, E-mail: anna@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

2011-10-26

This paper evaluated the absorbed dose at the surface entry known as 'cone beam computed tomography' (CBCT) in odontological computerized tomography. Examination were simulated with CBCT for measurements of dose. A phantom were filled with water, becoming scatter object of radiation. Thermoluminescent dosemeters were positioned on points correspondent to eyes and salivary glands

High-resolution brain SPECT imaging by combination of parallel and tilted detector heads.

Science.gov (United States)

Suzuki, Atsuro; Takeuchi, Wataru; Ishitsu, Takafumi; Morimoto, Yuichi; Kobashi, Keiji; Ueno, Yuichiro

2015-10-01

To improve the spatial resolution of brain single-photon emission computed tomography (SPECT), we propose a new brain SPECT system in which the detector heads are tilted towards the rotation axis so that they are closer to the brain. In addition, parallel detector heads are used to obtain the complete projection data set. We evaluated this parallel and tilted detector head system (PT-SPECT) in simulations. In the simulation study, the tilt angle of the detector heads relative to the axis was 45°. The distance from the collimator surface of the parallel detector heads to the axis was 130 mm. The distance from the collimator surface of the tilted detector heads to the origin on the axis was 110 mm. A CdTe semiconductor panel with a 1.4 mm detector pitch and a parallel-hole collimator were employed in both types of detector head. A line source phantom, cold-rod brain-shaped phantom, and cerebral blood flow phantom were evaluated. The projection data were generated by forward-projection of the phantom images using physics models, and Poisson noise at clinical levels was applied to the projection data. The ordered-subsets expectation maximization algorithm with physics models was used. We also evaluated conventional SPECT using four parallel detector heads for the sake of comparison. The evaluation of the line source phantom showed that the transaxial FWHM in the central slice for conventional SPECT ranged from 6.1 to 8.5 mm, while that for PT-SPECT ranged from 5.3 to 6.9 mm. The cold-rod brain-shaped phantom image showed that conventional SPECT could visualize up to 8-mm-diameter rods. By contrast, PT-SPECT could visualize up to 6-mm-diameter rods in upper slices of a cerebrum. The cerebral blood flow phantom image showed that the PT-SPECT system provided higher resolution at the thalamus and caudate nucleus as well as at the longitudinal fissure of the cerebrum compared with conventional SPECT. PT-SPECT provides improved image resolution at not only upper but also at

WE-D-303-01: Development and Application of Digital Human Phantoms

Energy Technology Data Exchange (ETDEWEB)

Segars, P. [Duke University, Durham, NC (United States)

2015-06-15

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems.

WE-D-303-01: Development and Application of Digital Human Phantoms

International Nuclear Information System (INIS)

Segars, P.

2015-01-01

Modern medical physics deals with complex problems such as 4D radiation therapy and imaging quality optimization. Such problems involve a large number of radiological parameters, and anatomical and physiological breathing patterns. A major challenge is how to develop, test, evaluate and compare various new imaging and treatment techniques, which often involves testing over a large range of radiological parameters as well as varying patient anatomies and motions. It would be extremely challenging, if not impossible, both ethically and practically, to test every combination of parameters and every task on every type of patient under clinical conditions. Computer-based simulation using computational phantoms offers a practical technique with which to evaluate, optimize, and compare imaging technologies and methods. Within simulation, the computerized phantom provides a virtual model of the patient’s anatomy and physiology. Imaging data can be generated from it as if it was a live patient using accurate models of the physics of the imaging and treatment process. With sophisticated simulation algorithms, it is possible to perform virtual experiments entirely on the computer. By serving as virtual patients, computational phantoms hold great promise in solving some of the most complex problems in modern medical physics. In this proposed symposium, we will present the history and recent developments of computational phantom models, share experiences in their application to advanced imaging and radiation applications, and discuss their promises and limitations. Learning Objectives: Understand the need and requirements of computational phantoms in medical physics research Discuss the developments and applications of computational phantoms Know the promises and limitations of computational phantoms in solving complex problems

Chest Injuries Associated with Head Injury | Mezue | Nigerian ...

African Journals Online (AJOL)

Conclusion: Associated chest injuries result in higher mortality from head injuries. This association is more likely in the young and more productive. All patients presenting with head and spinal cord injury should be specifically and carefully evaluated for associated chest injuries. Computerized tomographic has not replaced ...

MO-F-CAMPUS-T-01: IROC Houston QA Center’s Anthropomorphic Proton Phantom Program

International Nuclear Information System (INIS)

Lujano, C; Hernandez, N; Keith, T; Nguyen, T; Taylor, P; Molineu, A; Followill, D

2015-01-01

Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to be approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647

MO-F-CAMPUS-T-01: IROC Houston QA Center’s Anthropomorphic Proton Phantom Program

Energy Technology Data Exchange (ETDEWEB)

Lujano, C; Hernandez, N; Keith, T; Nguyen, T; Taylor, P; Molineu, A; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

2015-06-15

Purpose: To describe the proton phantoms that IROC Houston uses to approve and credential proton institutions to participate in NCI-sponsored clinical trials. Methods: Photon phantoms cannot necessarily be used for proton measurements because protons react differently than photons in some plastics. As such plastics that are tissue equivalent for protons were identified. Another required alteration is to ensure that the film dosimeters are housed in the phantom with no air gap to avoid proton streaming. Proton-equivalent plastics/materials used include RMI Solid Water, Techron HPV, blue water, RANDO soft tissue material, balsa wood, compressed cork and polyethylene. Institutions wishing to be approved or credentialed request a phantom and are prioritized for delivery. At the institution, the phantom is imaged, a treatment plan is developed, positioned on the treatment couch and the treatment is delivered. The phantom is returned and the measured dose distributions are compared to the institution’s electronically submitted treatment plan dosimetry data. Results: IROC Houston has developed an extensive proton phantom approval/credentialing program consisting of five different phantoms designs: head, prostate, lung, liver and spine. The phantoms are made with proton equivalent plastics that have HU and relative stopping powers similar (within 5%) of human tissues. They also have imageable targets, avoidance structures, and heterogeneities. TLD and radiochromic film are contained in the target structures. There have been 13 head, 33 prostate, 18 lung, 2 liver and 16 spine irradiations with either passive scatter, or scanned proton beams. The pass rates have been: 100%, 69.7%, 72.2%, 50%, and 81.3%, respectively. Conclusion: IROC Houston has responded to the recent surge in proton facilities by developing a family of anthropomorphic phantoms that are able to be used for remote audits of proton beams. Work supported by PHS grant CA10953 and CA081647.

Evaluation of the absorbed dose in odontological computerized tomography; Avaliacao da dose absorvida em tomografia computadorizada odontologica

Energy Technology Data Exchange (ETDEWEB)

Legnani, Adriano; Schelin, Hugo R.; Rocha, Anna Silvia P.S. da, E-mail: schelin@utfpr.edu.b, E-mail: anna@utfpr.edu.b [Universidade Tecnologica Federal do Parana (UTFPR), Curitiba, PR (Brazil); Khoury, Helen J., E-mail: khoury@ufpe.b [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil)

2011-10-26

This paper evaluated the absorbed dose at the surface entry known as 'cone beam computed tomography' (CBCT) in odontological computerized tomography. Examination were simulated with CBCT for measurements of dose. A phantom were filled with water, becoming scatter object of radiation. Thermoluminescent dosemeters were positioned on points correspondent to eyes and salivary glands

Nation-wide anthropometric survey data in Japan to determine dimensions of total-body phantom for Reference Japanese Man

International Nuclear Information System (INIS)

Togo, Masami

1990-01-01

In order to estimate radiation dose in Japanese population accurately, a Reference Japanese Man, whose stature and body weight are 170cm and 60kg respectively, is indispensable. The MIRD 5 total-body phantom has only 8 dimensions, i.e. total head height, head length, head breadth, trunk length, trunk breadth, leg length, and breadth and depth of a leg model at its lower end. Based on Japanese anthropometric data, the dimensions were determined and its mathematical descriptions were given. In Japan, annual statistical data of stature, body weight, chest circumference and sitting height for all Japan by sex and age are published. But other nation-wide survey data necessary for determining dimensions of total-body phantom of Reference Japanese Man, are unavailable. Much more national anthropometric data of every kind necessary for defining phantoms must be compiled. (author)

Correlations between computerized tomography of the head and motor developmental disturbances of children with cerebral palsy

International Nuclear Information System (INIS)

Chen, Yu-Herng

1981-01-01

Two hundred and eighty-two children with cerebral palsy (C.P.) and thirty-seven normal children were studied by computerized tomography (C.T.) of the head for finding out the correlations between the organic damage of the brain and the motor developmental disturbance. The abnormal findings of C.T. were: enlargement of the ventricular system, high density area, low density area and porencephalus, enlargement of the sulcus and anomaly of the medial structure. Enlargement of the ventricular system seemed to have correlation with spasticity; the portion and the extent of the enlargement corresponded to the affected extremities and the severity of the spasticity. Children of other types also showed various abnormal C.T. findings but, in general, less than that of spastic types. The prognosis of the motor development of C.P. children cannot be predicted by serial C.T. examinations strictly, because early treatment could cause improvement to that of these children. However, it is of worthy notice that C.T. is an effective method of helping to diagnose the motor developmental disturbance in earlier childhood. (author)

Introduction of the Canadian CT Head Rule Reduces CT Scan Use ...

African Journals Online (AJOL)

amnesia or witnessed disorientation in a patient with a GCS score of 13–15 who has suffered a traumatic event, the evaluation of minor head injury using. Computerized Axial Tomography Scan of the Head. (CT-head) has remained controversial.(1,3). CT–head is expensive, time consuming, strenuous to human resource ...

Radiological image interpretation for hematoma and small tumors simulated in a head and neck phantom

International Nuclear Information System (INIS)

Thompson, Larissa; Campos, Tarcisio Passos Ribeiro

2009-01-01

Subarachnoidal hemorrhages (HSA) are caused by aneurysms and their symptom usually becomes evident after a rupture. Nevertheless, there are situations in which the aneurysms compress a nerve or produce a bleed before the rupture happens, as consequence one alert signal like headache occurs. It, often occurs after minutes or weeks previous the major rupture. The main goal is to prevent a massive hemorrhage. Thus the Computer Tomography (CT) scan of skull provides a basic and specific function: to reveal the position where the hemorrhage was produced, guiding to a additional medical procedures. On the other hand, CT does not prevent the cerebral tumor development, but precise diagnostic for some symptoms such as vomits, nauseas, epileptic attacks, weakness in arms or legs, require this image protocol. CT has its fundamental importance to tumor detection. Indeed CT reveals its importance in the tumor early diagnosis. Specialized training in CT analysis shall be done. Ahead of a precise diagnosis to manager an early intervention, a CT diagnostic training is suitable for a favorable prognostic. In this context, focusing on propose of radiological inquires; a head and neck phantom will be used to simulate hematomas and cerebral tumors. Images of CT of skull will be used to identify these lesions physically implanted in phantom. The radiological response will be analyzed with the purpose of validation of the skull's CT diagnosis, for a double blind test. The diagnostic with non contrast CT shows only higher 5mm diameter subjects (tumors) identified by the double blind test. Hemorrhage is identified by only the administrator (single-blind test). As conclusion, the author's launches the hypothesis that this object simulator shall provide assistance for specialized training on pathology interpretation on radiological images. (author)

SU-F-BRE-04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

International Nuclear Information System (INIS)

Ehler, E; Higgins, P; Dusenbery, K

2014-01-01

Purpose: To validate a method to create per patient phantoms for dosimetric verification measurements. Methods: Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in-vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel-opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On-board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation. Results: The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index). Conclusion: A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom

SU-F-BRE-04: Construction of 3D Printed Patient Specific Phantoms for Dosimetric Verification Measurements

Energy Technology Data Exchange (ETDEWEB)

Ehler, E; Higgins, P; Dusenbery, K [University of Minnesota, Minneapolis, MN (United States)

2014-06-15

Purpose: To validate a method to create per patient phantoms for dosimetric verification measurements. Methods: Using a RANDO phantom as a substitute for an actual patient, a model of the external features of the head and neck region of the phantom was created. A phantom was used instead of a human for two reasons: to allow for dosimetric measurements that would not be possible in-vivo and to avoid patient privacy issues. Using acrylonitrile butadiene styrene thermoplastic as the building material, a hollow replica was created using the 3D printer filled with a custom tissue equivalent mixture of paraffin wax, magnesium oxide, and calcium carbonate. A traditional parallel-opposed head and neck plan was constructed. Measurements were performed with thermoluminescent dosimeters in both the RANDO phantom and in the 3D printed phantom. Calculated and measured dose was compared at 17 points phantoms including regions in high and low dose regions and at the field edges. On-board cone beam CT was used to localize both phantoms within 1mm and 1° prior to radiation. Results: The maximum difference in calculated dose between phantoms was 1.8% of the planned dose (180 cGy). The mean difference between calculated and measured dose in the anthropomorphic phantom and the 3D printed phantom was 1.9% ± 2.8% and −0.1% ± 4.9%, respectively. The difference between measured and calculated dose was determined in the RANDO and 3D printed phantoms. The differences between measured and calculated dose in each respective phantom was within 2% for 12 of 17 points. The overlap of the RANDO and 3D printed phantom was 0.956 (Jaccard Index). Conclusion: A custom phantom was created using a 3D printer. Dosimetric calculations and measurements showed good agreement between the dose in the RANDO phantom (patient substitute) and the 3D printed phantom.

Comparative study of anatomical normalization errors in SPM and 3D-SSP using digital brain phantom.

Science.gov (United States)

Onishi, Hideo; Matsutake, Yuki; Kawashima, Hiroki; Matsutomo, Norikazu; Amijima, Hizuru

2011-01-01

In single photon emission computed tomography (SPECT) cerebral blood flow studies, two major algorithms are widely used statistical parametric mapping (SPM) and three-dimensional stereotactic surface projections (3D-SSP). The aim of this study is to compare an SPM algorithm-based easy Z score imaging system (eZIS) and a 3D-SSP system in the errors of anatomical standardization using 3D-digital brain phantom images. We developed a 3D-brain digital phantom based on MR images to simulate the effects of head tilt, perfusion defective region size, and count value reduction rate on the SPECT images. This digital phantom was used to compare the errors of anatomical standardization by the eZIS and the 3D-SSP algorithms. While the eZIS allowed accurate standardization of the images of the phantom simulating a head in rotation, lateroflexion, anteflexion, or retroflexion without angle dependency, the standardization by 3D-SSP was not accurate enough at approximately 25° or more head tilt. When the simulated head contained perfusion defective regions, one of the 3D-SSP images showed an error of 6.9% from the true value. Meanwhile, one of the eZIS images showed an error as large as 63.4%, revealing a significant underestimation. When required to evaluate regions with decreased perfusion due to such causes as hemodynamic cerebral ischemia, the 3D-SSP is desirable. In a statistical image analysis, we must reconfirm the image after anatomical standardization by all means.

Method of evaluation of diagnostics reference levels in computerized tomography

International Nuclear Information System (INIS)

Vega, Walter Flores

1999-04-01

Computerized tomography is a complex technique with several selectable exposition parameters delivering high doses to the patient. In this work it was developed a simple methodology to evaluate diagnostic reference levels in computerized tomography, using the concept of Multiple Scan Average Dose (MSAD), recently adopted by the Health Ministry. For evaluation of the MSAD, a dose distribution was obtained through a measured dose profile on the axial axis of a water phantom with thermoluminescence dosemeters, TLD-100, for different exam technique. The MSAD was evaluated hrough two distinct methods. First, it was evaluated by the integration of the dose profile of a single slice and, second, obtained by the integration on central slice of the profile of several slices. The latter is in of accordance with the ionization chamber method, suggesting to be the most practical method of dose evaluation to be applied in the diagnostic reference level assessment routine for CT, using TLDs. (author)

Effect of phantom dimension variation on Monte Carlo simulation speed and precision

International Nuclear Information System (INIS)

Lin Hui; Xu Yuanying; Xu Liangfeng; Li Guoli; Jiang Jia

2007-01-01

There is a correlation between Monte Carlo simulation speed and the phantom dimension. The effect of the phantom dimension on the Monte Carlo simulation speed and precision was studied based on a fast Monte Carlo code DPM. The results showed that when the thickness of the phantom was reduced, the efficiency would increase exponentially without compromise of its precision except for the position at the tailor. When the width of the phantom was reduced to outside the penumbra, the effect on the efficiency would be neglectable. However when it was reduced to within the penumbra, the efficiency would be increased at some extent without precision loss. This result was applied to a clinic head case, and the remarkable increased efficiency was acquired. (authors)

Electromagnetic Head-And-Neck Hyperthermia Applicator: Experimental Phantom Verification and FDTD Model

International Nuclear Information System (INIS)

Paulides, Margarethus M.; Bakker, Jurriaan F.; Rhoon, Gerard C. van

2007-01-01

Purpose: To experimentally verify the feasibility of focused heating in the neck region by an array of two rings of six electromagnetic antennas. We also measured the dynamic specific absorption rate (SAR) steering possibilities of this setup and compared these SAR patterns to simulations. Methods and Materials: Using a specially constructed laboratory prototype head-and-neck applicator, including a neck-mimicking cylindrical muscle phantom, we performed SAR measurements by electric field, Schottky-diode sheet measurements and, using the power-pulse technique, by fiberoptic thermometry and infrared thermography. Using phase steering, we also steered the SAR distribution in radial and axial directions. All measured distributions were compared with the predictions by a finite-difference time-domain-based electromagnetic simulator. Results: A central 50% iso-SAR focus of 35 ± 3 mm in diameter and about 100 ± 15 mm in length was obtained for all investigated settings. Furthermore, this SAR focus could be steered toward the desired location in the radial and axial directions with an accuracy of ∼5 mm. The SAR distributions as measured by all three experimental methods were well predicted by the simulations. Conclusion: The results of our study have shown that focused heating in the neck is feasible and that this focus can be effectively steered in the radial and axial directions. For quality assurance measurements, we believe that the Schottky-diode sheet provides the best compromise among effort, speed, and accuracy, although a more specific and improved design is warranted

Computerized tomography

International Nuclear Information System (INIS)

Rubashov, I.B.

1985-01-01

Operating principle is described for the devices of computerized tomography used in medicine for diagnosis of brain diseases. Computerized tomography is considered as a part of computerized diagnosis, as a part of information science. It is shown that computerized tomography is a real existed field of investigations in medicine and industrial production

Whole-body detector calibrating with a modular phantom

Energy Technology Data Exchange (ETDEWEB)

Minev, L; Boshkova, T; Uzunov, P [Sofia Univ. (Bulgaria). Fizicheski Fakultet

1996-12-31

Human body models (phantoms) of various size and weight are produced in order to calibrate gamma spectrometers for accurate activity measurement. The phantoms are built of separate modules with mass of 0.5 kg and size 20 x 14 x 2 cm. There are modules with standard Eu-152 and Am-241 radioactivity designed for homogenous radioactivity imitating and critical organs moulding, as well as `zero` -phantom modules without activity imitating a standard human body. Human organs are modelled by 11 x 9 x 0.5 cm modules with 0.16 kg mass. The phantoms have been used to obtain calibration curves and absolute efficiencies for selected energies of radionuclides expected to be found in the Kozloduy NPP staff. It is shown that the efficiency depends not only on the mass but on the geometric size of the measured object. Scanning of phantoms has been carried out and a profile of activity obtained. The profile consists of an abrupt rising of the sum of pulses (measuring time - 20 s) when the detector passes from neck to chest, a plateau when it moves over the head or the trunk and gradual decrease over the legs. Profiles of activity in organs are best obtained with a lead collimator. 4 refs., 7 figs., 2 tabs.

Whole-body detector calibrating with a modular phantom

International Nuclear Information System (INIS)

Minev, L.; Boshkova, T.; Uzunov, P.

1995-01-01

Human body models (phantoms) of various size and weight are produced in order to calibrate gamma spectrometers for accurate activity measurement. The phantoms are built of separate modules with mass of 0.5 kg and size 20 x 14 x 2 cm. There are modules with standard Eu-152 and Am-241 radioactivity designed for homogenous radioactivity imitating and critical organs moulding, as well as 'zero' -phantom modules without activity imitating a standard human body. Human organs are modelled by 11 x 9 x 0.5 cm modules with 0.16 kg mass. The phantoms have been used to obtain calibration curves and absolute efficiencies for selected energies of radionuclides expected to be found in the Kozloduy NPP staff. It is shown that the efficiency depends not only on the mass but on the geometric size of the measured object. Scanning of phantoms has been carried out and a profile of activity obtained. The profile consists of an abrupt rising of the sum of pulses (measuring time - 20 s) when the detector passes from neck to chest, a plateau when it moves over the head or the trunk and gradual decrease over the legs. Profiles of activity in organs are best obtained with a lead collimator. 4 refs., 7 figs., 2 tabs

Uncertainties in effective dose estimates of adult CT head scans: The effect of head size

International Nuclear Information System (INIS)

Gregory, Kent J.; Bibbo, Giovanni; Pattison, John E.

2009-01-01

Purpose: This study is an extension of a previous study where the uncertainties in effective dose estimates from adult CT head scans were calculated using four CT effective dose estimation methods, three of which were computer programs (CT-EXPO, CTDOSIMETRY, and IMPACTDOSE) and one that involved the dose length product (DLP). However, that study did not include the uncertainty contribution due to variations in head sizes. Methods: The uncertainties due to head size variations were estimated by first using the computer program data to calculate doses to small and large heads. These doses were then compared with doses calculated for the phantom heads used by the computer programs. An uncertainty was then assigned based on the difference between the small and large head doses and the doses of the phantom heads. Results: The uncertainties due to head size variations alone were found to be between 4% and 26% depending on the method used and the patient gender. When these uncertainties were included with the results of the previous study, the overall uncertainties in effective dose estimates (stated at the 95% confidence interval) were 20%-31% (CT-EXPO), 15%-30% (CTDOSIMETRY), 20%-36% (IMPACTDOSE), and 31%-40% (DLP). Conclusions: For the computer programs, the lower overall uncertainties were still achieved when measured values of CT dose index were used rather than tabulated values. For DLP dose estimates, head size variations made the largest (for males) and second largest (for females) contributions to effective dose uncertainty. An improvement in the uncertainty of the DLP method dose estimates will be achieved if head size variation can be taken into account.

Uncertainties in effective dose estimates of adult CT head scans: The effect of head size

Energy Technology Data Exchange (ETDEWEB)

Gregory, Kent J.; Bibbo, Giovanni; Pattison, John E. [Department of Medical Physics, Royal Adelaide Hospital, Adelaide, South Australia 5000 (Australia) and School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, South Australia 5095 (Australia); Division of Medical Imaging, Women' s and Children' s Hospital, North Adelaide, South Australia 5006 (Australia) and School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, South Australia 5095 (Australia); School of Electrical and Information Engineering (Applied Physics), University of South Australia, Mawson Lakes, South Australia 5095 (Australia)

2009-09-15

Purpose: This study is an extension of a previous study where the uncertainties in effective dose estimates from adult CT head scans were calculated using four CT effective dose estimation methods, three of which were computer programs (CT-EXPO, CTDOSIMETRY, and IMPACTDOSE) and one that involved the dose length product (DLP). However, that study did not include the uncertainty contribution due to variations in head sizes. Methods: The uncertainties due to head size variations were estimated by first using the computer program data to calculate doses to small and large heads. These doses were then compared with doses calculated for the phantom heads used by the computer programs. An uncertainty was then assigned based on the difference between the small and large head doses and the doses of the phantom heads. Results: The uncertainties due to head size variations alone were found to be between 4% and 26% depending on the method used and the patient gender. When these uncertainties were included with the results of the previous study, the overall uncertainties in effective dose estimates (stated at the 95% confidence interval) were 20%-31% (CT-EXPO), 15%-30% (CTDOSIMETRY), 20%-36% (IMPACTDOSE), and 31%-40% (DLP). Conclusions: For the computer programs, the lower overall uncertainties were still achieved when measured values of CT dose index were used rather than tabulated values. For DLP dose estimates, head size variations made the largest (for males) and second largest (for females) contributions to effective dose uncertainty. An improvement in the uncertainty of the DLP method dose estimates will be achieved if head size variation can be taken into account.

Development and application of anthropomorphic voxel phantom of the head for in vivo measurement.

Science.gov (United States)

Vrba, T

2007-01-01

The in vivo measurement of the activity deposited in the skeleton is a very useful source of information on human internal contaminations with transuranic elements, e.g. americium 241, especially for long time periods after intake. Measurements are performed on the skull or the larger joints such as the knee or elbow. The paper deals with the construction of an anthropomorphic numerical phantom based on CT scans, its potential for calibration and the estimation of the uncertainties of the detection system. The density of bones, activity distribution and position of the detectors were changed in individual simulations in order to estimate their effects on the result of the measurement. The results from simulations with the numerical phantom were compared with the results of physical phantoms.

A low-cost phantom for simple routine testing of single photon emission computed tomography (SPECT) cameras

International Nuclear Information System (INIS)

Ng, A.H.; Ng, K.H.; Dharmendra, H.; Perkins, A.C.

2009-01-01

A simple sphere test phantom has been developed for routine performance testing of SPECT systems in situations where expensive commercial phantoms may not be available. The phantom was based on a design with six universal syringe hubs set in the frame to support a circular array of six glass blown spheres of different sizes. The frame was then placed into a water-filled CT abdomen phantom and scanned with a triple head camera system (Philips IRIX TM , USA). Comparison was made with a commercially available phantom (Deluxe Jaszczak phantom). Whereas the commercial phantom demonstrates cold spot resolution, an important advantage of the sphere test phantom was that hot spot resolution could be easily measured using almost half (370 MBq) of the activity recommended for use in the commercial phantom. Results showed that the contrast increased non-linearly with sphere volume and radionuclide concentration. The phantom was found to be suitable as an inexpensive option for daily performance tests.

Assessment of radiation exposure in dental cone-beam computerized tomography with the use of metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters and Monte Carlo simulations.

Science.gov (United States)

Koivisto, J; Kiljunen, T; Tapiovaara, M; Wolff, J; Kortesniemi, M

2012-09-01

The aims of this study were to assess the organ and effective dose (International Commission on Radiological Protection (ICRP) 103) resulting from dental cone-beam computerized tomography (CBCT) imaging using a novel metal-oxide semiconductor field-effect transistor (MOSFET) dosimeter device, and to assess the reliability of the MOSFET measurements by comparing the results with Monte Carlo PCXMC simulations. Organ dose measurements were performed using 20 MOSFET dosimeters that were embedded in the 8 most radiosensitive organs in the maxillofacial and neck area. The dose-area product (DAP) values attained from CBCT scans were used for PCXMC simulations. The acquired MOSFET doses were then compared with the Monte Carlo simulations. The effective dose measurements using MOSFET dosimeters yielded, using 0.5-cm steps, a value of 153 μSv and the PCXMC simulations resulted in a value of 136 μSv. The MOSFET dosimeters placed in a head phantom gave results similar to Monte Carlo simulations. Minor vertical changes in the positioning of the phantom had a substantial affect on the overall effective dose. Therefore, the MOSFET dosimeters constitute a feasible method for dose assessment of CBCT units in the maxillofacial region. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of inherent misalignment and head motion in neurological PET/MR with the Philips Ingenuity TF – phantom and patient study

Energy Technology Data Exchange (ETDEWEB)

Teuho, Jarmo; Johansson, Jarkko; Saunavaara, Virva; Kemppainen, Nina; Teräs, Mika [Turku PET Centre, Turku University Hospital, Turku (Finland)

2014-07-29

The aim of the study was to evaluate the effect of misalignment and head motion on image quantification in PET/MR with a novel brain phantom and a healthy control group. The phantom was imaged at two time points in PET/MR, concurrently with PET and PET/CT. Phantom images were evaluated visually and the relative difference in hemispheric accumulation was calculated. Difference in cortical accumulation in a healthy control group was evaluated from non-attenuation corrected (NAC) and MR attenuation corrected (MRAC) images. Regional ROI mean values from F{sup 18}-FDG ratio images and regional hemispheric asymmetries were calculated. Controls were divided to high and low asymmetry groups. A student’s t-test (p<0.005) for group difference and NAC versus MRAC data was performed. Finally, mean PET-MR registration parameters were measured. Only the first phantom scan exhibited asymmetry in lateral frontal cortex (17%) and temporal cortex (19%). Correcting the misalignment of 2.63mm reduced the asymmetry to less than 5%, to a level seen in PET and PET/CT. A significant asymmetry was found in the temporal and parietal cortex between groups in MRAC data with no significant asymmetry in NAC data. Asymmetries in affected MRAC data in temporal and parietal cortex were 9.4% and 11.7%. NAC data from both groups had asymmetry less than 5% in all regions. Both groups had significant y- and z-translation, while only the asymmetry group had significant z-rotation and x-translation. The shift in x-, y-, or z-direction in both groups was less than 4 mm, with no significant differences. Thus, PET-MRAC misalignment may cause under- and overestimation of attenuation in the lines of response on opposite sides of the cortical regions, resulting to asymmetric difference between the hemispheres. Our findings stress the need for novel QC procedures for PET-MR alignment and suggest confirming the quality of PET-MRAC alignment from PET-NAC images.

Organ dose evaluation for CT scans based on in-phantom measurements

International Nuclear Information System (INIS)

Liu Haikuan; Zhuo Weihai; Chen Bo; Yi Yanling; Li Dehong

2009-01-01

Objective: To explore the organ doses and their distributions in different projections of CT scans. Methods: The CT values were measured and the linear absorption coefficients were derived for the main organs of the anthropomorphic phantom to compare with the normal values of human beings. The radiophotoluminescent glass dosimeters were set into various tissues or organs of the phantom for mimic measurements of the organ doses undergoing the head, chest, abdomen and pelvis CT scans, respectively. Results: The tissue equivalence of the phantom used in this study was good. The brain had the largest organ dose undergoing the head CT scan. The organ doses in thyroid, breast, lung and oesophagus were relatively large in performing the chest CT scan, while the liver, stomach, colon and lung had relatively hrge organ doses in abdomen CT practice. The doses in bone surface and colon exceeded by 50 mGy in a single pelvis CT scan. Conclusions: The organ doses and their distributions largely vary with different projections of CT scans. The organ doses of colon, bone marrow,gonads and bladder are fairly large in performing pelvis CT scan, which should be paid attention in the practice. (authors)

Comparative study of anatomical normalization errors in SPM and 3D-SSP using digital brain phantom

International Nuclear Information System (INIS)

Onishi, Hideo; Matsutomo, Norikazu; Matsutake, Yuki; Kawashima, Hiroki; Amijima, Hizuru

2011-01-01

In single photon emission computed tomography (SPECT) cerebral blood flow studies, two major algorithms are widely used statistical parametric mapping (SPM) and three-dimensional stereotactic surface projections (3D-SSP). The aim of this study is to compare an SPM algorithm-based easy Z score imaging system (eZIS) and a 3D-SSP system in the errors of anatomical standardization using 3D-digital brain phantom images. We developed a 3D-brain digital phantom based on MR images to simulate the effects of head tilt, perfusion defective region size, and count value reduction rate on the SPECT images. This digital phantom was used to compare the errors of anatomical standardization by the eZIS and the 3D-SSP algorithms. While the eZIS allowed accurate standardization of the images of the phantom simulating a head in rotation, lateroflexion, anteflexion, or retroflexion without angle dependency, the standardization by 3D-SSP was not accurate enough at approximately 25 deg or more head tilt. When the simulated head contained perfusion defective regions, one of the 3D-SSP images showed an error of 6.9% from the true value. Meanwhile, one of the eZIS images showed an error as large as 63.4%, revealing a significant underestimation. When required to evaluate regions with decreased perfusion due to such causes as hemodynamic cerebral ischemia, the 3D-SSP is desirable. In a statistical image analysis, we must reconfirm the image after anatomical standardization by all means. (author)

Image quality of conventional images of dual-layer SPECTRAL CT: a phantom study.

Science.gov (United States)

van Ommen, F; Bennink, E; Vlassenbroek, A; Dankbaar, J W; Schilham, A M R; Viergever, M A; de Jong, H W A M

2018-05-10

Spectral CT using a dual layer detector offers the possibility of retrospectively introducing spectral information to conventional CT images. In theory, the dual-layer technology should not come with a dose or image quality penalty for conventional images. In this study, we evaluate the influence of a dual-layer detector (IQon Spectral CT, Philips) on the image quality of conventional CT images, by comparing these images with those of a conventional but otherwise technically comparable single-layer CT scanner (Brilliance iCT, Philips), by means of phantom experiments. For both CT scanners conventional CT images were acquired using four adult scanning protocols: i) body helical, ii) body axial, iii) head helical and iv) head axial. A CATPHAN 600 phantom was scanned to conduct an assessment of image quality metrics at equivalent (CTDI) dose levels. Noise was characterized by means of noise power spectra (NPS) and standard deviation (SD) of a uniform region, and spatial resolution was evaluated with modulation transfer functions (MTF) of a tungsten wire. In addition, contrast-to-noise ratio (CNR), image uniformity, CT number linearity, slice thickness, slice spacing, and spatial linearity were measured and evaluated. Additional measurements of CNR, resolution and noise were performed in two larger phantoms. The resolution levels at 50%, 10% and 5% MTF of the iCT and IQon showed small but significant differences up to 0.25 lp/cm for body scans, and up to 0.2 lp/cm for head scans in favor of the IQon. The iCT and IQon showed perfect CT linearity for body scans, but for head scans both scanners showed an underestimation of the CT numbers of materials with a high opacity. Slice thickness was slightly overestimated for both scanners. Slice spacing was comparable and reconstructed correctly. In addition, spatial linearity was excellent for both scanners, with a maximum error of 0.11 mm. CNR was higher on the IQon compared to the iCT for both normal and larger phantoms with

Influence of different types of phantoms on the calibration of dosemeters for eye lens dosimetry

International Nuclear Information System (INIS)

Yoshitomi, H.; Kowatari, M.

2016-01-01

Both a cylinder and a slab phantom have been recommended to be used as calibration phantoms for eye lens dosimetry in the International Atomic Energy Agency TECDOC. This study describes investigations on the influence of the type of phantom on the calibration of dosemeters. In order to fulfil the purpose, backscatter radiation from practically used water-filled phantoms was evaluated by calculations and experiments. For photons, the calculations showed that the cylinder phantom had 10 % lower backscattered effect at maximum than a slab phantom, and simulated well the backscattered effect of the human head or neck to within ±10 %. The irradiation results of non-filtered optically stimulated luminescence and radio-photoluminescence glass dosemeters indicated that the differences of the calibration factors between the two types of phantoms were up to 20 and 10 %, respectively, reflecting the response to backscattered photons. For electrons, no difference was found between the two types of phantoms. (authors)

Mathematical development of a 10 years old child phantom for use in internal dosimetry

International Nuclear Information System (INIS)

Deus, S.F.; Poston, J.W.; Watanabe, S.

1989-08-01

The main objectives of this work are: 1) to develop a project of a mathematical phantom representing as far as possible a child of 10 years old and 2)to use this phantom as a base for the specific absorbed fractions (SAF) calculations in the internal organs and skeleton due to the radioisotopes most used in nuclear medicine. This phantom was similar in shape to the Fisher and Snyder one, but several changes were introduced to make the phantom more realistic. Those changes included the addition of a neck region, puting the arms outside the trunk region, changes in the trunk, head and genitalia regions shapes. Several modifications were also done in the skeleton. For instance, the head bones, rib cage, pelvis, vertebral column, scapula, clavicles and the arms and legs bones were made very close to the real anatomic shapes. Some internal organs as the brain, lungs, liver, small and large intestines were also changed as a consenquence of the above modifications. In all those cases, the changes were made not only in the shapes but also in the organs and bones position in such a way to be more representative of the 10 years old anatomic age. Estimates of the SAF obtained by the use of this phantom, resulted, as expected, significantly different from those obtained by the use of a simpler model. In other words, the ratio between the SAF in the organs of the phantom developed in this project and the SAF in the organs of the phantom similar to the adult (obtained by reducing each region of the adult phantom by the use of appropriate factor) vary from 0.37 to 5. Those differences and their meaning are also discussed. (author) [pt

CT images of an anthropomorphic and anthropometric male pelvis phantom

Energy Technology Data Exchange (ETDEWEB)

Matos, Andrea S.D. de; Campos, Tarcisio P.R. de, E-mail: campos@nuclear.ufmg.b [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Programa de Pos-graduacao em Ciencias e Tecnicas Nucleares

2009-07-01

Actually, among of the most often neoplasm types are the cancer of prostate, bladder and intestine. The incidence of the intestine neoplasm in Brazil is at fourth among the most frequent tumors of the male sex, barely close to the stomach, lung and prostate incidences. Phantoms are objects used as simulators for investigating ionizing radiation transport on humans, especially during radiation therapy or radiological diagnostic. The purpose of this work is the achievement of a set of computerized tomography (CT) images of a male pelvis phantom, with anthropomorphic and anthropometric features. It investigates and analyses the set of phantom CT images in according to a correspondent human pelvis one. The reason to develop a pelvis phantom is the needs of reproducing well established spatial dose distribution in radiation therapy, especially during calibration and protocol setup for various pelvis neoplasms. It aims to produce dose optimization on radiation therapy, improving health tissue protection and keeping control tumor dose. A male pelvis phantom with similar shape made of equivalent tissues was built for simulating the ionizing radiation transport to the human body. At the phantom, pelvis organs were reproduced including the bladder, the intestine, the prostate, the muscular and greasy tissue, as well as the bone tissue and the skin. A set of CT images was carried out in axial thin sections of 2mm thickness. As results, the constituent tissues had a tomography response on Hounsfield scale similar to values found on the human pelvis. Each tissue has its respective Hounsfield value, demonstrated here. The CT images also show that the organs have equivalent anthropometric measures and anthropomorphic features of the radiological human anatomy. The anatomical physical arrangement of the organs is also similar to of the pelvis human male, having the scales of gray and numerical scale of Hounsfield compatible with the scale of the human tissue. The phantom presents

CT images of an anthropomorphic and anthropometric male pelvis phantom

International Nuclear Information System (INIS)

Matos, Andrea S.D. de; Campos, Tarcisio P.R. de

2009-01-01

Actually, among of the most often neoplasm types are the cancer of prostate, bladder and intestine. The incidence of the intestine neoplasm in Brazil is at fourth among the most frequent tumors of the male sex, barely close to the stomach, lung and prostate incidences. Phantoms are objects used as simulators for investigating ionizing radiation transport on humans, especially during radiation therapy or radiological diagnostic. The purpose of this work is the achievement of a set of computerized tomography (CT) images of a male pelvis phantom, with anthropomorphic and anthropometric features. It investigates and analyses the set of phantom CT images in according to a correspondent human pelvis one. The reason to develop a pelvis phantom is the needs of reproducing well established spatial dose distribution in radiation therapy, especially during calibration and protocol setup for various pelvis neoplasms. It aims to produce dose optimization on radiation therapy, improving health tissue protection and keeping control tumor dose. A male pelvis phantom with similar shape made of equivalent tissues was built for simulating the ionizing radiation transport to the human body. At the phantom, pelvis organs were reproduced including the bladder, the intestine, the prostate, the muscular and greasy tissue, as well as the bone tissue and the skin. A set of CT images was carried out in axial thin sections of 2mm thickness. As results, the constituent tissues had a tomography response on Hounsfield scale similar to values found on the human pelvis. Each tissue has its respective Hounsfield value, demonstrated here. The CT images also show that the organs have equivalent anthropometric measures and anthropomorphic features of the radiological human anatomy. The anatomical physical arrangement of the organs is also similar to of the pelvis human male, having the scales of gray and numerical scale of Hounsfield compatible with the scale of the human tissue. The phantom presents

Evaluation of a video-based head motion tracking system for dedicated brain PET

Science.gov (United States)

Anishchenko, S.; Beylin, D.; Stepanov, P.; Stepanov, A.; Weinberg, I. N.; Schaeffer, S.; Zavarzin, V.; Shaposhnikov, D.; Smith, M. F.

2015-03-01

Unintentional head motion during Positron Emission Tomography (PET) data acquisition can degrade PET image quality and lead to artifacts. Poor patient compliance, head tremor, and coughing are examples of movement sources. Head motion due to patient non-compliance can be an issue with the rise of amyloid brain PET in dementia patients. To preserve PET image resolution and quantitative accuracy, head motion can be tracked and corrected in the image reconstruction algorithm. While fiducial markers can be used, a contactless approach is preferable. A video-based head motion tracking system for a dedicated portable brain PET scanner was developed. Four wide-angle cameras organized in two stereo pairs are used for capturing video of the patient's head during the PET data acquisition. Facial points are automatically tracked and used to determine the six degree of freedom head pose as a function of time. The presented work evaluated the newly designed tracking system using a head phantom and a moving American College of Radiology (ACR) phantom. The mean video-tracking error was 0.99±0.90 mm relative to the magnetic tracking device used as ground truth. Qualitative evaluation with the ACR phantom shows the advantage of the motion tracking application. The developed system is able to perform tracking with accuracy close to millimeter and can help to preserve resolution of brain PET images in presence of movements.

A set of 4D pediatric XCAT reference phantoms for multimodality research

International Nuclear Information System (INIS)

Norris, Hannah; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P.; Minhas, Anum; Frush, D.; Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I.

2014-01-01

Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

A set of 4D pediatric XCAT reference phantoms for multimodality research

Energy Technology Data Exchange (ETDEWEB)

Norris, Hannah, E-mail: Hannah.norris@duke.edu; Zhang, Yakun; Bond, Jason; Sturgeon, Gregory M.; Samei, E.; Segars, W. P. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27705 (United States); Minhas, Anum; Frush, D. [Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Tward, Daniel J.; Ratnanather, J. T.; Miller, M. I. [Center for Imaging Science, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

2014-03-15

Purpose: The authors previously developed an adult population of 4D extended cardiac-torso (XCAT) phantoms for multimodality imaging research. In this work, the authors develop a reference set of 4D pediatric XCAT phantoms consisting of male and female anatomies at ages of newborn, 1, 5, 10, and 15 years. These models will serve as the foundation from which the authors will create a vast population of pediatric phantoms for optimizing pediatric CT imaging protocols. Methods: Each phantom was based on a unique set of CT data from a normal patient obtained from the Duke University database. The datasets were selected to best match the reference values for height and weight for the different ages and genders according to ICRP Publication 89. The major organs and structures were segmented from the CT data and used to create an initial pediatric model defined using nonuniform rational B-spline surfaces. The CT data covered the entire torso and part of the head. To complete the body, the authors manually added on the top of the head and the arms and legs using scaled versions of the XCAT adult models or additional models created from cadaver data. A multichannel large deformation diffeomorphic metric mapping algorithm was then used to calculate the transform from a template XCAT phantom (male or female 50th percentile adult) to the target pediatric model. The transform was applied to the template XCAT to fill in any unsegmented structures within the target phantom and to implement the 4D cardiac and respiratory models in the new anatomy. The masses of the organs in each phantom were matched to the reference values given in ICRP Publication 89. The new reference models were checked for anatomical accuracy via visual inspection. Results: The authors created a set of ten pediatric reference phantoms that have the same level of detail and functionality as the original XCAT phantom adults. Each consists of thousands of anatomical structures and includes parameterized models

A phantom-based study for assessing the error and uncertainty of a neuronavigation system

OpenAIRE

Natalia Izquierdo-Cifuentes; Genaro Daza-Santacoloma; Walter Serna-Serna

2017-01-01

This document describes a calibration protocol with the intention to introduce a guide to standardize the metrological vocabulary among manufacturers of image-guided surgery systems. Two stages were developed to measure the errors and estimate the uncertainty of a neuronavigator in different situations, on the first one it was determined a mechanical error on a virtual model of an acrylic phantom, on the second it was determined a coordinate error on the computerized axial tomography scan of ...

A Monte Carlo-based method to estimate radiation dose from spiral CT: from phantom testing to patient-specific models

International Nuclear Information System (INIS)

Jarry, G; De Marco, J J; Beifuss, U; Cagnon, C H; McNitt-Gray, M F

2003-01-01

The purpose of this work is to develop and test a method to estimate the relative and absolute absorbed radiation dose from axial and spiral CT scans using a Monte Carlo approach. Initial testing was done in phantoms and preliminary results were obtained from a standard mathematical anthropomorphic model (MIRD V) and voxelized patient data. To accomplish this we have modified a general purpose Monte Carlo transport code (MCNP4B) to simulate the CT x-ray source and movement, and then to calculate absorbed radiation dose in desired objects. The movement of the source in either axial or spiral modes was modelled explicitly while the CT system components were modelled using published information about x-ray spectra as well as information provided by the manufacturer. Simulations were performed for single axial scans using the head and body computed tomography dose index (CTDI) polymethylmethacrylate phantoms at both central and peripheral positions for all available beam energies and slice thicknesses. For comparison, corresponding physical measurements of CTDI in phantom were made with an ion chamber. To obtain absolute dose values, simulations and measurements were performed in air at the scanner isocentre for each beam energy. To extend the verification, the CT scanner model was applied to the MIRD V model and compared with published results using similar technical factors. After verification of the model, the generalized source was simulated and applied to voxelized models of patient anatomy. The simulated and measured absolute dose data in phantom agreed to within 2% for the head phantom and within 4% for the body phantom at 120 and 140 kVp; this extends to 8% for the head and 9% for the body phantom across all available beam energies and positions. For the head phantom, the simulated and measured absolute dose data agree to within 2% across all slice thicknesses at 120 kVp. Our results in the MIRD phantom agree within 11% of all the different organ dose values

Operator radiation exposure during right or left transradial coronary angiography: A phantom study

International Nuclear Information System (INIS)

Sciahbasi, Alessandro; Rigattieri, Stefano; Sarandrea, Alessandro; Cera, Maria; Di Russo, Cristian; Fedele, Silvio; Romano, Silvio; Pugliese, Francesco Rocco; Penco, Maria

2015-01-01

Background: Previous studies showed a possible lower radiation dose absorbed by operators comparing LRA and RRA for percutaneous coronary procedures. The reasons of this lower radiation dose are not well known. The aim of this study was to evaluate the radiation dose absorbed by operators comparing left with right radial access (LRA and RRA respectively) during a simulated diagnostic coronary angiography using a phantom. Methods: A coronary angiography examination was simulated on a phantom by 5 operators using eight projections with 5 seconds fluoroscopy each. Each operator was equipped with 4 electronic dosimeters placed at thorax, at left wrist, at left head and at hip level. Radiation doses were expressed in picosievert and normalized by dose area product. Results: LRA compared to RRA was associated with a significant lower operator dose at wrist (36 pSv/cGYcm"2 [IQR 18–59 pSv/cGYcm"2] and 48 pSv/cGYcm"2 [IQR 22–148 pSv/cGYcm"2] respectively, p = 0.01) and thorax (3 pSv/cGYcm"2 [IQR 2–5 pSv/cGYcm"2] and 10 pSv/cGYcm"2 [6–23 pSv/cGYcm"2] respectively, p < 0.001) but with a significant higher radiation dose at hip level (102 pSv/cGYcm"2 [IQR 44–199 pSv/cGYcm"2] and 67 pSv/cGYcm"2 [IQR 39–132 pSv/cGYcm"2] respectively, p = 0.02). Conversely the radiation dose at left side of the head did not show significant differences between the two approaches. Conclusions: In this phantom study simulating a diagnostic coronarography the use of LRA compared to RRA was associated with a significant lower radiation dose at wrist and thorax but with an increased dose at hip level. Summary: To evaluate the radiation dose absorbed by operators comparing left with right radial access (LRA and RRA respectively) we simulated a diagnostic coronary angiography using a dedicated phantom. Operators were equipped with dedicated electronic dosimeters at wrist, hip, head and thorax level. LRA compared to RRA was associated with a significant lower operator dose at wrist and thorax

Symbol phantoms

International Nuclear Information System (INIS)

Yamaguchi, Hiroshi; Hongo, Syozo; Takeshita, Hiroshi

1990-01-01

We have developed Japanese phantoms in two procedures for computation of organ doses exposed to internal and/or external radiation sources. One method is to make mathematical phantoms on the basis of ORNL mathematical phantoms. Parameters to specify organs of Japanese mathematical phantom are determined by interpolations of the ORNL data, which define the organs of Caucasian males and females of various ages, i.e. new born, 1, 5, 10, 15 years and adult, with survey data for Japanese physiques. Another procedure is to build 'symbol phantoms' for the Japanese public. The concept and its method of the symbol phantom enables us to make a phantom for an individual when we have all of his transversal section images obtained by a medical imaging device like MRI, and thus we may achieve more realistic phantoms for Japanese public than the mathematical phantoms. Both studies are in progress in NIRS. (author)

Radiation absorbed dose and expected risk in head and neck tissues after thyroid radioiodine therapy

Energy Technology Data Exchange (ETDEWEB)

Hamed, A [National Center for Nuclear and Radiation Control, AEA., Cairo (Egypt); Farag, H I [National Cancer instiute, Cairo University, Cairo (Egypt); Saleh, A [Al-hussien Hospital, Al-Azhar University, Cairo (Egypt)

1997-12-31

Measurement of absorbed dose in head and neck phantom after applying I-131 therapeutic dose for the treatment of thyroid malignancies was conducted. The measurement were carried out at several sites of phantom using TL dosimeters. The absorbed doses were also measured on the skin of four patients during their administration of I-131 therapeutic doses 1.332 GBq (36 mci) I-131. The measurements were taken over 69 hours exposure at different sites of phantom. The same measurements were carried out on the four patients. At five sites of the patients head and neck, the absorbed dose were measured and compared with that measured on the phantom. The values measured are discussed in the light of the published individual absorbed doses in the organs by ICRP tables. High absorbed doses were absorbed in the different sites of the head and neck during the I-131 therapy (0.14-9.68 mGy/mCi). 3 figs., 2 tabs.

Computerized tomography of orbital lesions

International Nuclear Information System (INIS)

Kuroiwa, Mayumi

1981-01-01

Two different types of computerized tomography scanners (CT scanner), i.e. a whole-body CT scanner (GE-CT/T8800) and a cerebral CT scanner (EMI-1010), were compared in the assessment and diagnosis of various orbital lesions. The whole-body CT scanner was found to be advantageous over the cerebral CT scanner for the following reasons: (1) CT images were more informative due to thinner slices associated with smaller-sized and larger-numbered matrices; (2) less artifacts derived from motion of the head or eyeball were produced because of the shorter scanning time; (3) with a devised gantry, coronal dissections were available whenever demanded. (author)

Computerized tomography and head growth curve infantile macrocephaly with normal psychomotor development

International Nuclear Information System (INIS)

Eda, Isematsu; Kitahara, Tadashi; Takashima, Sachio; Takeshita, Kenzo

1982-01-01

Macrocephaly was defined as a head measuring larger than 98th percentile. We have evaluated CT findings and head growth curves in 25 infants with large heads. Ten (40%) of 25 infants with large heads were normal developmentally and neurologically. Five (20%) of those were mentally retarded. The other 10 infants (40%) included hydrocephalus (4 cases), malformation syndrome (3 cases), brain tumor (1 case), metabolic disorder (1 case) and degenerative disorder (1 case). Their head growth curves were typed as (I), (II) and (III): Type (I) (excessive head growth curve to 2 SDs above normal); Type (II) (head growth curve gradually approached to 2 SDs above normal); Type (III) (head growth curve parallel to 2 SDs above normal). Ten of macrocephaly with normal psychomotor development were studied clinically and radiologically in details. They were all male. CT pictures of those showed normal or various abnormal findings: ventricular dilatations, wide frontal and temporal subdural spaces, wide interhemispheric fissures, wide cerebral sulci, and large sylvian fissures. CT findings in 2 of those, which because normal after repeated CT examinations, resembled benign subdural collection. CT findings in one of those were external hydrocephalus. Head growth curves were obtained from 8 of those. Six cases revealed type (II) and two cases did type (III). The remaining 2 cases could not be followed up. We consider that CT findings of infants showed macrocephaly with normal psychomotor development reveals normal or various abnormal (ventricular dilatations, benign subdural collection, external hydrocephalus) and their head growth curves are not at least excessive. Infants with mental retardation showed similar CT findings and head growth curves as those with normal psychomotor development. It was difficult to distinguish normal from mentally retarded infants by either CT findings or head growth curves. (author)

[Development of a Striatal and Skull Phantom for Quantitative 123I-FP-CIT SPECT].

Science.gov (United States)

Ishiguro, Masanobu; Uno, Masaki; Miyazaki, Takuma; Kataoka, Yumi; Toyama, Hiroshi; Ichihara, Takashi

123 Iodine-labelled N-(3-fluoropropyl) -2β-carbomethoxy-3β-(4-iodophenyl) nortropane ( 123 I-FP-CIT) single photon emission computerized tomography (SPECT) images are used for differential diagnosis such as Parkinson's disease (PD). Specific binding ratio (SBR) is affected by scattering and attenuation in SPECT imaging, because gender and age lead to changes in skull density. It is necessary to clarify and correct the influence of the phantom simulating the the skull. The purpose of this study was to develop phantoms that can evaluate scattering and attenuation correction. Skull phantoms were prepared based on the measuring the results of the average computed tomography (CT) value, average skull thickness of 12 males and 16 females. 123 I-FP-CIT SPECT imaging of striatal phantom was performed with these skull phantoms, which reproduced normal and PD. SPECT images, were reconstructed with scattering and attenuation correction. SBR with partial volume effect corrected (SBR act ) and conventional SBR (SBR Bolt ) were measured and compared. The striatum and the skull phantoms along with 123 I-FP-CIT were able to reproduce the normal accumulation and disease state of PD and further those reproduced the influence of skull density on SPECT imaging. The error rate with the true SBR, SBR act was much smaller than SBR Bolt . The effect on SBR could be corrected by scattering and attenuation correction even if the skull density changes with 123 I-FP-CIT on SPECT imaging. The combination of triple energy window method and CT-attenuation correction method would be the best correction method for SBR act .

Development of computer assisted learning program using cone beam projection for head radiography

International Nuclear Information System (INIS)

Nakazeko, Kazuma; Araki, Misao; Kajiwara, Hironori; Watanabe, Hiroyuki; Kuwayama, Jun; Karube, Shuhei; Hashimoto, Takeyuki; Shinohara, Hiroyuki

2012-01-01

We present a computer assisted learning (CAL) program to simulate head radiography. The program provides cone beam projections of a target volume, simulating three-dimensional computed tomography (CT) of a head phantom. The generated image is 512 x 512 x 512 pixels with each pixel 0.6 mm on a side. The imaging geometry, such as X-ray tube orientation and phantom orientation, can be varied. The graphical user interface (GUI) of the CAL program allows the study of the effects of varying the imaging geometry; each simulated projection image is shown quickly in an adjoining window. Simulated images with an assigned geometry were compared with the image obtained using the standard geometry in clinical use. The accuracy of the simulated image was verified through comparison with the image acquired using radiography of the head phantom, subsequently processed with a computed radiography system (CR image). Based on correlation coefficient analysis and visual assessment, it was concluded that the CAL program can satisfactorily simulate the CR image. Therefore, it should be useful for the training of head radiography. (author)

Position displacement effect on the doses in the peripheral head regions

International Nuclear Information System (INIS)

Kortesniemi, M.; Seppaelae, T.; Bjugg, H.; Seren, T.; Kotiluoto, P.; Auterinen, I.; Parkkinen, R.; Savolainen, S.

2000-01-01

Patient positioning is a challenging task in BNCT-treatments due to the use of multiple fields and a static horizontal beam construction. Positioning accuracy of 5 mm is required for acceptable dose delivery within appropriate limits of dose uncertainty (up to 10% of point dose in target volume). The aim of this study was to determine if a patient head position creating a clear gap between the beam port and the head would have a significant effect on the doses to the peripheral regions of the head, e.g. to the eyes. The gamma dose rates were measured in a water filled ellipsoidal phantom with an ionisation chamber (IC). Mn activation wires were used to determine the Mn-55(n, γ) reaction rates. Twelve measurement points were chosen in the phantom and two phantom positions were applied. According to this study the 35 mm position change and the resulting gap has an obvious effect on the peripheral doses in BNCT. The Mn activation reaction rates were on the average 80% higher in the deviation position than in the reference position. Increasing depth from the surface inside the phantom diminished the gamma dose difference between the two positions. Scattering environment changes with position displacement and resulting gap causes differences in neutron fluences and gamma doses. (author)

Monte Carlo study of the influence of energy spectra, mesh size, high Z element on dose and PVDR based on 1-D and 3-D heterogeneous mouse head phantom for Microbeam Radiation Therapy.

Science.gov (United States)

Lin, Hui; Jing, Jia; Xu, Liangfeng; Mao, Xiaoli

2017-12-01

To evaluate the influence of energy spectra, mesh sizes, high Z element on dose and PVDR in Microbeam Radiation Therapy (MRT) based on 1-D analogy-mouse-head-model (1-D MHM) and 3-D voxel-mouse-head-phantom (3-D VMHP) by Monte Carlo simulation. A Microbeam-Array-Source-Model was implemented into EGSnrc/DOSXYZnrc. The microbeam size is assumed to be 25μm, 50μm or 75μm in thickness and fixed 1mm in height with 200μmc-t-c. The influence of the energy spectra of ID17@ESRF and BMIT@CLS were investigated. The mesh size was optimized. PVDR in 1-D MHM and 3-D VMHP was compared with the homogeneous water phantom. The arc influence of 3-D VMHP filled with water (3-D VMHWP) was compared with the rectangle phantom. PVDR of the lower BMIT@CLS spectrum is 2.4times that of ID17@ESRF for lower valley dose. The optimized mesh is 5µm for 25µm, and 10µm for 50µm and 75µm microbeams with 200µmc-t-c. A 500μm skull layer could make PVDR difference up to 62.5% for 1-D MHM. However this influence is limited (influence is limited for the more depth (influence of 3-D heterogeneous media. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

SU-F-I-32: Organ Doses from Pediatric Head CT Scan

Energy Technology Data Exchange (ETDEWEB)

Liu, H; Liu, Q; Qiu, J; Zhuo, W [Institute of Radiation Medicine Fudan University, Shanghai (China); Majer, M; Knezevic, Z; Miljanic, S [Radiation Chemistry and Dosimetry Laboratory, Ruder Boskovic Institute, Zagreb (Croatia); Hrsak, H [Clinical Hospital Centre Zagreb, Zagreb (Croatia)

2016-06-15

Purpose: To evaluate the organ doses of pediatric patients who undergoing head CT scan using Monte Carlo (MC) simulation and compare it with measurements in anthropomorphic child phantom.. Methods: A ten years old children voxel phantom was developed from CT images, the voxel size of the phantom was 2mm*2mm*2mm. Organ doses from head CT scan were simulated using MCNPX software, 180 detectors were placed in the voxel phantom to tally the doses of the represented tissues or organs. When performing the simulation, 120 kVp and 88 mA were selected as the scan parameters. The scan range covered from the top of the head to the end of the chain, this protocol was used at CT simulator for radiotherapy. To validate the simulated results, organ doses were measured with radiophotoluminescence (RPL) detectors, placed in the 28 organs of the 10 years old CIRS ATOM phantom. Results: The organ doses results matched well between MC simulation and phantom measurements. The eyes dose was showed to be as expected the highest organ dose: 28.11 mGy by simulation and 27.34 mGy by measurement respectively. Doses for organs not included in the scan volume were much lower than those included in the scan volume, thymus doses were observed more than 10 mGy due the CT protocol for radiotherapy covered more body part than routine head CT scan. Conclusion: As the eyes are superficial organs, they may receive the highest radiation dose during the CT scan. Considering the relatively high radio sensitivity, using shielding material or organ based tube current modulation technique should be encouraged to reduce the eye radiation risks. Scan range was one of the most important factors that affects the organ doses during the CT scan. Use as short as reasonably possible scan range should be helpful to reduce the patient radiation dose. This work was supported by the National Natural Science Foundation of China(11475047)

Impact of magnetic field strength and receiver coil in ocular MRI: a phantom and patient study.

Science.gov (United States)

Erb-Eigner, K; Warmuth, C; Taupitz, M; Willerding, G; Bertelmann, E; Asbach, P

2013-09-01

Generally, high-resolution MRI of the eye is performed with small loop surface coils. The purpose of this phantom and patient study was to investigate the influence of magnetic field strength and receiver coils on image quality in ocular MRI. The eyeball and the complex geometry of the facial bone were simulated by a skull phantom with swine eyes. MR images were acquired with two small loop surface coils with diameters of 4 cm and 7 cm and with a multi-channel head coil at 1.5 and 3 Tesla, respectively. Furthermore, MRI of the eye was performed prospectively in 20 patients at 1.5 Tesla (7 cm loop surface coil) and 3 Tesla (head coil). These images were analysed qualitatively and quantitatively and statistical significance was tested using the Wilcoxon-signed-rank test (a p-value of less than 0.05 was considered to indicate statistical significance). The analysis of the phantom images yielded the highest mean signal-to-noise ratio (SNR) at 3 Tesla with the use of the 4 cm loop surface coil. In the phantom experiment as well as in the patient studies the SNR was higher at 1.5 Tesla by applying the 7 cm surface coil than at 3 Tesla by applying the head coil. Concerning the delineation of anatomic structures no statistically significant differences were found. Our results show that the influence of small loop surface coils on image quality (expressed in SNR) in ocular MRI is higher than the influence of the magnetic field strength. The similar visibility of detailed anatomy leads to the conclusion that the image quality of ocular MRI at 3 Tesla remains acceptable by applying the head coil as a receiver coil. © Georg Thieme Verlag KG Stuttgart · New York.

Conversion of ICRP male reference phantom to polygon-surface phantom

Science.gov (United States)

Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong; Jeong, Jong Hwi

2013-10-01

The International Commission on Radiological Protection (ICRP) reference phantoms, developed based on computed tomography images of human bodies, provide much more realism of human anatomy than the previously used MIRD5 (Medical Internal Radiation Dose) mathematical phantoms. It has been, however, realized that the ICRP reference phantoms have some critical limitations showing a considerable amount of holes for the skin and wall organs mainly due to the nature of voxels of which the phantoms are made, especially due to their low voxel resolutions. To address this problem, we are planning to develop the polygon-surface version of ICRP reference phantoms by directly converting the ICRP reference phantoms (voxel phantoms) to polygon-surface phantoms. The objective of this preliminary study is to see if it is indeed possible to construct the high-quality polygon-surface phantoms based on the ICRP reference phantoms maintaining identical organ morphology and also to identify any potential issues, and technologies to address these issues, in advance. For this purpose, in the present study, the ICRP reference male phantom was roughly converted to a polygon-surface phantom. Then, the constructed phantom was implemented in Geant4, Monte Carlo particle transport code, for dose calculations, and the calculated dose values were compared with those of the original ICRP reference phantom to see how much the calculated dose values are sensitive to the accuracy of the conversion process. The results of the present study show that it is certainly possible to convert the ICRP reference phantoms to surface phantoms with enough accuracy. In spite of using relatively less resources (original ICRP reference phantoms, it is believed that the polygon-surface version of ICRP reference phantoms properly developed will not only provide the same or similar dose values (say, difference <5 or 10%) for highly penetrating radiations, but also provide correct dose values for the weakly penetrating

Validation of dose planning calculations for boron neutron capture therapy using cylindrical and anthropomorphic phantoms

Energy Technology Data Exchange (ETDEWEB)

Koivunoro, Hanna; Seppaelae, Tiina; Uusi-Simola, Jouni; Merimaa, Katja; Savolainen, Sauli [Department of Physics, POB 64, FI-00014 University of Helsinki (Finland); Kotiluoto, Petri; Seren, Tom; Auterinen, Iiro [VTT Technical Research Centre of Finland, Espoo, POB 1000, FI-02044 VTT (Finland); Kortesniemi, Mika, E-mail: hanna.koivunoro@helsinki.f [HUS Helsinki Medical Imaging Center, University of Helsinki, POB 340, FI-00029 HUS (Finland)

2010-06-21

In this paper, the accuracy of dose planning calculations for boron neutron capture therapy (BNCT) of brain and head and neck cancer was studied at the FiR 1 epithermal neutron beam. A cylindrical water phantom and an anthropomorphic head phantom were applied with two beam aperture-to-surface distances (ASD). The calculations using the simulation environment for radiation application (SERA) treatment planning system were compared to neutron activation measurements with Au and Mn foils, photon dose measurements with an ionization chamber and the reference simulations with the MCNP5 code. Photon dose calculations using SERA differ from the ionization chamber measurements by 2-13% (disagreement increased along the depth in the phantom), but are in agreement with the MCNP5 calculations within 2%. The {sup 55}Mn(n,{gamma}) and {sup 197}Au(n,{gamma}) reaction rates calculated using SERA agree within 10% and 8%, respectively, with the measurements and within 5% with the MCNP5 calculations at depths >0.5 cm from the phantom surface. The {sup 55}Mn(n,{gamma}) reaction rate represents the nitrogen and boron depth dose within 1%. Discrepancy in the SERA fast neutron dose calculation (of up to 37%) is corrected if the biased fast neutron dose calculation option is not applied. Reduced voxel cell size ({<=}0.5 cm) improves the SERA calculation accuracy on the phantom surface. Despite the slight overestimation of the epithermal neutrons and underestimation of the thermal neutrons in the beam model, neutron calculation accuracy with the SERA system is sufficient for reliable BNCT treatment planning with the two studied treatment distances. The discrepancy between measured and calculated photon dose remains unsatisfactorily high for depths >6 cm from the phantom surface. Increasing discrepancy along the phantom depth is expected to be caused by the inaccurately determined effective point of the ionization chamber.

Conversion of ICRP male reference phantom to polygon-surface phantom

International Nuclear Information System (INIS)

Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong; Jeong, Jong Hwi

2013-01-01

The International Commission on Radiological Protection (ICRP) reference phantoms, developed based on computed tomography images of human bodies, provide much more realism of human anatomy than the previously used MIRD5 (Medical Internal Radiation Dose) mathematical phantoms. It has been, however, realized that the ICRP reference phantoms have some critical limitations showing a considerable amount of holes for the skin and wall organs mainly due to the nature of voxels of which the phantoms are made, especially due to their low voxel resolutions. To address this problem, we are planning to develop the polygon-surface version of ICRP reference phantoms by directly converting the ICRP reference phantoms (voxel phantoms) to polygon-surface phantoms. The objective of this preliminary study is to see if it is indeed possible to construct the high-quality polygon-surface phantoms based on the ICRP reference phantoms maintaining identical organ morphology and also to identify any potential issues, and technologies to address these issues, in advance. For this purpose, in the present study, the ICRP reference male phantom was roughly converted to a polygon-surface phantom. Then, the constructed phantom was implemented in Geant4, Monte Carlo particle transport code, for dose calculations, and the calculated dose values were compared with those of the original ICRP reference phantom to see how much the calculated dose values are sensitive to the accuracy of the conversion process. The results of the present study show that it is certainly possible to convert the ICRP reference phantoms to surface phantoms with enough accuracy. In spite of using relatively less resources (<2 man-months), we were able to construct the polygon-surface phantom with the organ masses perfectly matching the ICRP reference values. The analysis of the calculated dose values also implies that the dose values are indeed not very sensitive to the detailed morphology of the organ models in the phantom

The industrial computerized tomography applied to the rock analysis

International Nuclear Information System (INIS)

Tetzner, Guaraciaba de Campos

2008-01-01

This work is a study of the possibilities of the technical applications of Computerized Tomography (CT) by using a device developed in the Radiation Technology Center (CTR), Institute for Energy and Nuclear Research (IPEN-CNEN/SP). The equipment consists of a gamma radiation source ( 60 Co), a scintillation detector of sodium iodide doped with thallium (NaI (Tl)), a mechanical system to move the object (rotation and translation) and a computer system. This operating system has been designed and developed by the CTR-IPEN-CNEN/SP team using national resources and technology. The first validation test of the equipment was carried out using a cylindrical sample of polypropylene (phantom) with two cylindrical cavities (holes) of 5 x 25 cm (diameter and length). In these tests, the holes were filled with materials of different density (air, oil and metal), whose attenuation coefficients are well known. The goal of this first test was to assess the response quality of the equipment. The present report is a study comparing computerized tomography equipment CTR-IPEN-CNEN/SP which uses a source of gamma radiation ( 60 Co) and other equipment provided by the Department of Geosciences in the University of Texas (CTUT), which uses an X-ray source (450 kV and 3.2 mA). As a result, the images obtained and the comprehensive study of the usefulness of the equipment developed here strengthened the proposition that the development of industrial computerized tomography is an important step toward consolidating the national technology. (author)

Dose profile study in head CT scans using radiochromic films

International Nuclear Information System (INIS)

Ladino G, A. M.; Prata M, A.

2016-10-01

Diagnostic images of computed tomography generate higher doses than other methods of diagnostic radiology using X-ray beam attenuation. Clinical applications of CT have been increased by technological advances, what leads to a wide variety of scanner in the Brazilian technological pool. It has been difficult to implement dose reduction strategies because of the lack of proper guidance on computed tomography examinations. However, CT scanners allow adjusting acquisition parameter according to the patients physical profile and diagnostic application for which the scan is intended. The knowledge of the dose distribution is important because changes in image acquisition parameters may provide dose reduction. In this study, it was used a cylindrical head phantom in PMMA with 5 openings, what allows dose measurement in 5 regions. In a GE CT scanner, Discovery model of 64 channels, the central slice of the head phantom was irradiated and the absorbed doses were measured using a pencil ionization chamber. Radiochromic film strips were placed in the peripheral and in the central region of the head phantom and was performed a scan of 10 cm in the phantom central region. The scan was performed using the head scanning protocol of the radiobiology service, with a voltage of 120 kV. After scanning, the radiochromic film strips were digitalized and their digital images were used to have the dose longitudinal profiles. The dose values recorded have variation in a range of 18.66 to 23.57 mGy. In the results it was compared the dose index values obtained by the pencil chamber measurement to the dose longitudinal profiles recorded by the film strips. (Author)

Dose profile study in head CT scans using radiochromic films

Energy Technology Data Exchange (ETDEWEB)

Ladino G, A. M.; Prata M, A., E-mail: amlgphys@gmail.com [Universidade Federal de Minas Gerais, Departamento de Engenharia Nuclear, Av. Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte, Minas Gerais (Brazil)

2016-10-15

Diagnostic images of computed tomography generate higher doses than other methods of diagnostic radiology using X-ray beam attenuation. Clinical applications of CT have been increased by technological advances, what leads to a wide variety of scanner in the Brazilian technological pool. It has been difficult to implement dose reduction strategies because of the lack of proper guidance on computed tomography examinations. However, CT scanners allow adjusting acquisition parameter according to the patients physical profile and diagnostic application for which the scan is intended. The knowledge of the dose distribution is important because changes in image acquisition parameters may provide dose reduction. In this study, it was used a cylindrical head phantom in PMMA with 5 openings, what allows dose measurement in 5 regions. In a GE CT scanner, Discovery model of 64 channels, the central slice of the head phantom was irradiated and the absorbed doses were measured using a pencil ionization chamber. Radiochromic film strips were placed in the peripheral and in the central region of the head phantom and was performed a scan of 10 cm in the phantom central region. The scan was performed using the head scanning protocol of the radiobiology service, with a voltage of 120 kV. After scanning, the radiochromic film strips were digitalized and their digital images were used to have the dose longitudinal profiles. The dose values recorded have variation in a range of 18.66 to 23.57 mGy. In the results it was compared the dose index values obtained by the pencil chamber measurement to the dose longitudinal profiles recorded by the film strips. (Author)

Development of the voxel computational phantoms of pediatric patients and their application to organ dose assessment

Science.gov (United States)

Lee, Choonik

A series of realistic voxel computational phantoms of pediatric patients were developed and then used for the radiation risk assessment for various exposure scenarios. The high-resolution computed tomographic images of live patients were utilized for the development of the five voxel phantoms of pediatric patients, 9-month male, 4-year female, 8-year female, 11-year male, and 14-year male. The phantoms were first developed as head and torso phantoms and then extended into whole body phantoms by utilizing computed tomographic images of a healthy adult volunteer. The whole body phantom series was modified to have the same anthropometrics with the most recent reference data reported by the international commission on radiological protection. The phantoms, named as the University of Florida series B, are the first complete set of the pediatric voxel phantoms having reference organ masses and total heights. As part of the dosimetry study, the investigation on skeletal tissue dosimetry methods was performed for better understanding of the radiation dose to the active bone marrow and bone endosteum. All of the currently available methodologies were inter-compared and benchmarked with the paired-image radiation transport model. The dosimetric characteristics of the phantoms were investigated by using Monte Carlo simulation of the broad parallel beams of external phantom in anterior-posterior, posterior-anterior, left lateral, right lateral, rotational, and isotropic angles. Organ dose conversion coefficients were calculated for extensive photon energies and compared with the conventional stylized pediatric phantoms of Oak Ridge National Laboratory. The multi-slice helical computed tomography exams were simulated using Monte Carlo simulation code for various exams protocols, head, chest, abdomen, pelvis, and chest-abdomen-pelvis studies. Results have found realistic estimates of the effective doses for frequently used protocols in pediatric radiology. The results were very

Influence of dentures on SAR in the visible Chinese human head voxel phantom exposed to a mobile phone at 900 and 1800 MHz.

Science.gov (United States)

Yu, Dong; Zhang, Ruoyu; Liu, Qian

2012-09-01

To investigate the influence of dentures on electromagnetic energy absorption during the daily use of a mobile phone, a high-resolution head phantom based on the Visible Chinese Human dataset was reconstructed. Simulations on phantoms with various dentures were performed by using the finite-difference time-domain method with a 0.47 wavelength dipole antenna and a mobile phone model as radiation sources at 900 and 1800 MHz. The Specific energy Absorption Rate (SAR) values including 1 and 10 g average SAR values were assessed. When the metallic dental crowns with resonance lengths of approximately one-third to one-half wavelength in the tissue nearby are parallel to the radiation source, up to 121.6% relative enhancement for 1 g average SAR and 17.1% relative enhancement for 10 g average SAR are observed due to the resonance effect in energy absorption. When the radiation sources operate in the normal configuration, the 10 g average SAR values are still in compliance with the basic restrictions established by the Institute of Electrical and Electronic Engineers (IEEE) and the International Commission on Non-Ionizing Radiation Protection (ICNIRP), indicating that the safety limits will not be challenged by the usage of dentures. Copyright © 2012 Wiley Periodicals, Inc.

Acceptance and implementation of a system of planning computerized based on Monte Carlo

International Nuclear Information System (INIS)

Lopez-Tarjuelo, J.; Garcia-Molla, R.; Suan-Senabre, X. J.; Quiros-Higueras, J. Q.; Santos-Serra, A.; Marco-Blancas, N.; Calzada-Feliu, S.

2013-01-01

It has been done the acceptance for use clinical Monaco computerized planning system, based on an on a virtual model of the energy yield of the head of the linear electron Accelerator and that performs the calculation of the dose with an algorithm of x-rays (XVMC) based on Monte Carlo algorithm. (Author)

Radiation Dose to the Lens of the Eye from Computed Tomography Scans of the Head

Science.gov (United States)

Januzis, Natalie Ann

While it is well known that exposure to radiation can result in cataract formation, questions still remain about the presence of a dose threshold in radiation cataractogenesis. Since the exposure history from diagnostic CT exams is well documented in a patient's medical record, the population of patients chronically exposed to radiation from head CT exams may be an interesting area to explore for further research in this area. However, there are some challenges in estimating lens dose from head CT exams. An accurate lens dosimetry model would have to account for differences in imaging protocols, differences in head size, and the use of any dose reduction methods. The overall objective of this dissertation was to develop a comprehensive method to estimate radiation dose to the lens of the eye for patients receiving CT scans of the head. This research is comprised of a physics component, in which a lens dosimetry model was derived for head CT, and a clinical component, which involved the application of that dosimetry model to patient data. The physics component includes experiments related to the physical measurement of the radiation dose to the lens by various types of dosimeters placed within anthropomorphic phantoms. These dosimeters include high-sensitivity MOSFETs, TLDs, and radiochromic film. The six anthropomorphic phantoms used in these experiments range in age from newborn to adult. First, the lens dose from five clinically relevant head CT protocols was measured in the anthropomorphic phantoms with MOSFET dosimeters on two state-of-the-art CT scanners. The volume CT dose index (CTDIvol), which is a standard CT output index, was compared to the measured lens doses. Phantom age-specific CTDIvol-to-lens dose conversion factors were derived using linear regression analysis. Since head size can vary among individuals of the same age, a method was derived to estimate the CTDIvol-to-lens dose conversion factor using the effective head diameter. These conversion

The UF family of reference hybrid phantoms for computational radiation dosimetry

International Nuclear Information System (INIS)

Lee, Choonsik; Lodwick, Daniel; Hurtado, Jorge; Pafundi, Deanna; Williams, Jonathan L; Bolch, Wesley E

2010-01-01

Computational human phantoms are computer models used to obtain dose distributions within the human body exposed to internal or external radiation sources. In addition, they are increasingly used to develop detector efficiencies for in vivo whole-body counters. Two classes of computational human phantoms have been widely utilized for dosimetry calculation: stylized and voxel phantoms that describe human anatomy through mathematical surface equations and 3D voxel matrices, respectively. Stylized phantoms are flexible in that changes to organ position and shape are possible given avoidance of region overlap, while voxel phantoms are typically fixed to a given patient anatomy, yet can be proportionally scaled to match individuals of larger or smaller stature, but of equivalent organ anatomy. Voxel phantoms provide much better anatomical realism as compared to stylized phantoms which are intrinsically limited by mathematical surface equations. To address the drawbacks of these phantoms, hybrid phantoms based on non-uniform rational B-spline (NURBS) surfaces have been introduced wherein anthropomorphic flexibility and anatomic realism are both preserved. Researchers at the University of Florida have introduced a series of hybrid phantoms representing the ICRP Publication 89 reference newborn, 15 year, and adult male and female. In this study, six additional phantoms are added to the UF family of hybrid phantoms-those of the reference 1 year, 5 year and 10 year child. Head and torso CT images of patients whose ages were close to the targeted ages were obtained under approved protocols. Major organs and tissues were segmented from these images using an image processing software, 3D-DOCTOR(TM). NURBS and polygon mesh surfaces were then used to model individual organs and tissues after importing the segmented organ models to the 3D NURBS modeling software, Rhinoceros(TM). The phantoms were matched to four reference datasets: (1) standard anthropometric data, (2) reference

Ocular MR imaging. Evaluation of different coil setups in a phantom study

International Nuclear Information System (INIS)

Erb-Eigner, Katharina; Warmuth, Carsten; Taupitz, Matthias; Bertelmann, Eckart; Hamm, Bernd; Asbach, Patrick

2013-01-01

Small loop surface coils are generally recommended for ocular magnetic resonance (MR) imaging, but the optimal coil setup has not been systematically investigated. In this phantom study, we investigated which coil setup of those coils available for our MR imaging system provides the highest signal-to-noise ratio (SNR) in ocular MR imaging at 1.5 tesla. Using a phantom to simulate the eyeball and the orbital fat, we employed loop surface coils of 4- and 6-cm diameter and a multi-channel head coil to obtain images using a T 1 -weighted spin-echo sequence and then measured the SNR for each coil and coil combination. Use of the 6-cm loop coil alone yielded the highest mean SNR (27.5). Even in superficial regions (mesial and temporal), the SNR was higher using the 6-cm loop coil (33.6 and 45.5) than the 4-cm loop coil (28.0 and 33.8). Additional use of the head coil reduced the mean SNR to 10.4. This quantitative analysis suggests that use of a 6-cm loop surface coil offers the best results in ocular MR imaging. Combinations of loop coils or additional use of a head coil cannot be recommended because higher noise degrades image quality. (author)

A head-mounted display system for augmented reality: Initial evaluation for interventional MRI

International Nuclear Information System (INIS)

Wendt, M.; Wacker, F.K.

2003-01-01

Purpose: To discuss the technical details of a head mounted display with an augmented reality (AR) system and to describe a first pre-clinical evaluation in interventional MRI. Method: The AR system consists of a video-see-through head mounted display (HMD), mounted with a mini video camera for tracking and a stereo pair of mini cameras that capture live images of the scene. The live video view of the phantom/patient is augmented with graphical representations of anatomical structures from MRI image data and is displayed on the HMD. The application of the AR system with interventional MRI was tested using a MRI data set of the head and a head phantom. Results: The HMD enables the user to move around and observe the scene dynamically from various viewpoints. Within a short time the natural hand-eye coordination can easily be adapted to the slightly different view. The 3D perception is based on stereo and kinetic depth cues. A circular target with a diameter of 0.5 square centimeter was hit in 19 of 20 attempts. In a first evaluation the MRI image data augmented reality scene of a head phantom allowed good planning and precise simulation of a puncture. Conclusion: The HMD in combination with AR provides a direct, intuitive guidance for interventional MR procedures. (orig.) [de

Emission computerized axial tomography from multiple gamma-camera views using frequency filtering.

Science.gov (United States)

Pelletier, J L; Milan, C; Touzery, C; Coitoux, P; Gailliard, P; Budinger, T F

1980-01-01

Emission computerized axial tomography is achievable in any nuclear medicine department from multiple gamma camera views. Data are collected by rotating the patient in front of the camera. A simple fast algorithm is implemented, known as the convolution technique: first the projection data are Fourier transformed and then an original filter designed for optimizing resolution and noise suppression is applied; finally the inverse transform of the latter operation is back-projected. This program, which can also take into account the attenuation for single photon events, was executed with good results on phantoms and patients. We think that it can be easily implemented for specific diagnostic problems.

Computer tomographic phantom

International Nuclear Information System (INIS)

Lonn, A.H.R.; Jacobsen, D.R.; Zech, D.J.

1988-01-01

A reference phantom for computer tomography employs a flexible member with means for urging the flexible member into contact along the curved surface of the lumbar region of a human patient. In one embodiment, the reference phantom is pre-curved in an arc greater than required. Pressure from the weight of a patient laying upon the reference phantom is effective for straightening out the curvature sufficiently to achieve substantial contact along the lumbar region. The curvature of the reference phantom may be additionally distorted by a resilient pad between the resilient phantom and a table for urging it into contact with the lumbar region. In a second embodiment of the invention, a flexible reference phantom is disposed in a slot in the top of a resilient cushion. The resilient cushion and reference phantom may be enclosed in a flexible container. A partially curved reference phantom in a slot in a resilient cushion is also contemplated. (author)

Dose distribution in organs: patient-specific phantoms versus reference phantoms

Energy Technology Data Exchange (ETDEWEB)

Lacerda, I.V.B., E-mail: isabelle.lacerda@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife (Brazil); Vieira, J.W. [Instituto Federal de Pernambuco (IFPE), Recife (Brazil); Oliveira, M.L.; Lima, F.R.A. [Centro Regional de Ciências Nucleares do Nordeste (CRCN-NE/CNEN-PB), Recife (Brazil)

2017-07-01

Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

Dose distribution in organs: patient-specific phantoms versus reference phantoms

International Nuclear Information System (INIS)

Lacerda, I.V.B.; Vieira, J.W.; Oliveira, M.L.; Lima, F.R.A.

2017-01-01

Discrepancies between ICRP phantoms and real patients lead to disparities on patient-dose estimations. This paper aims to compare distribution of dose in organs of male/female specific-phantoms and ICRP reference phantoms. The absorbed dose estimation was performed using the EGSnrc Monte Carlo code and a parallel source algorithm. In this work were used a patient-specific phantom for a man (1.73m/70.3kg) and another for a woman (1.63m/60.3kg) and the male and female ICRP reference phantoms. The comparison of the absorbed dose from each phantom gender was performed using the relative error. The results were expressed in terms of conversion coefficients to brain, lungs, liver and kidneys. The greatest absolute relative error between the organs of the patient-specific phantom and the reference phantom was 22.92% in the liver and 62.84% in the kidneys, respectively for man and woman. There are errors that cannot be disregarded. This paper shows the need for a specific study for each patient or for the population of each country, since there are different body types, which affects the distribution of the organ doses. (author)

Development of a head phantom to be used for quality control in stereotactic radiosurgery

International Nuclear Information System (INIS)

Barbosa, Nilseia Aparecida

2010-05-01

It was designed and developed a geometric acrylic head phantom (GHP) for Quality Assurance (QA) in Stereotactic Radiosurgery (SRS). Inside the phantom there are inserts that are able to accommodate acrylic targets representing the tumor tissue and organ at risk in the region cranial brain, the brain stem. The tumor tissue is represented by two semi-spheres of acrylic with a diameter of 13.0 mm and cavities in the central region for accommodation of a TLD-100 detector and a small radiochromic EBT Gafchromic filmstrip. The brain stem is represented by the two parts of acrylic cylinder with a diameter 18.0 mm, 38.0 mm length and cavities along the central region to accommodate the 5 detectors TLD-100 and yet another of EBT film. The distance tumor - brain stem is 2.0 mm. The experimental setup was filled with water, attached to the stereotactic frame to determine the coordinates of the target and underwent computed tomography (CT). Cf images were transferred to the SRS planning system BrainLab (BrainScan). The contours of the lesion and organ at risk were delineated and, through the technique of multiple circular arcs, the planning was conduced with five arches, one isocenter and a collimator of 17.5 mm from the combination between the table and gantry . The dose delivered to the isocenter of the lesion was 3.0 Gy and the total coverage of tumor volume corresponds to the 75% isodose. This experimental arrangement is subjected to radiosurgery treatment, after which the dosimeters are evaluated and their responses compared with the values of planned doses. The linear accelerator used was a Varian CLlNAC 2300 CID, photon beam of 6 MV, installed at the National Cancer Institute (INCA). For verification of dose distributions in 3D, the films were irradiated in three planes: sagittal, caronal and axial. The .films were scanned and digitized on a scanner Microtek ScanMaker 9800XL model. The dose distributions in irradiated films were compared with the distributions of doses

Experimental validation of deterministic Acuros XB algorithm for IMRT and VMAT dose calculations with the Radiological Physics Center's head and neck phantom

International Nuclear Information System (INIS)

Han Tao; Mourtada, Firas; Kisling, Kelly; Mikell, Justin; Followill, David; Howell, Rebecca

2012-01-01

Purpose: The purpose of this study was to verify the dosimetric performance of Acuros XB (AXB), a grid-based Boltzmann solver, in intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Methods: The Radiological Physics Center (RPC) head and neck (H and N) phantom was used for all calculations and measurements in this study. Clinically equivalent IMRT and VMAT plans were created on the RPC H and N phantom in the Eclipse treatment planning system (version 10.0) by using RPC dose prescription specifications. The dose distributions were calculated with two different algorithms, AXB 11.0.03 and anisotropic analytical algorithm (AAA) 10.0.24. Two dose report modes of AXB were recorded: dose-to-medium in medium (D m,m ) and dose-to-water in medium (D w,m ). Each treatment plan was delivered to the RPC phantom three times for reproducibility by using a Varian Clinac iX linear accelerator. Absolute point dose and planar dose were measured with thermoluminescent dosimeters (TLDs) and GafChromic registered EBT2 film, respectively. Profile comparison and 2D gamma analysis were used to quantify the agreement between the film measurements and the calculated dose distributions from both AXB and AAA. The computation times for AAA and AXB were also evaluated. Results: Good agreement was observed between measured doses and those calculated with AAA or AXB. Both AAA and AXB calculated doses within 5% of TLD measurements in both the IMRT and VMAT plans. Results of AXB Dm,m (0.1% to 3.6%) were slightly better than AAA (0.2% to 4.6%) or AXB Dw,m (0.3% to 5.1%). The gamma analysis for both AAA and AXB met the RPC 7%/4 mm criteria (over 90% passed), whereas AXB Dm,m met 5%/3 mm criteria in most cases. AAA was 2 to 3 times faster than AXB for IMRT, whereas AXB was 4-6 times faster than AAA for VMAT. Conclusions: AXB was found to be satisfactorily accurate when compared to measurements in the RPC H and N phantom. Compared with AAA, AXB results were equal

Generation of a suite of 3D computer-generated breast phantoms from a limited set of human subject data

International Nuclear Information System (INIS)

Hsu, Christina M. L.; Palmeri, Mark L.; Segars, W. Paul; Veress, Alexander I.; Dobbins, James T. III

2013-01-01

Purpose: The authors previously reported on a three-dimensional computer-generated breast phantom, based on empirical human image data, including a realistic finite-element based compression model that was capable of simulating multimodality imaging data. The computerized breast phantoms are a hybrid of two phantom generation techniques, combining empirical breast CT (bCT) data with flexible computer graphics techniques. However, to date, these phantoms have been based on single human subjects. In this paper, the authors report on a new method to generate multiple phantoms, simulating additional subjects from the limited set of original dedicated breast CT data. The authors developed an image morphing technique to construct new phantoms by gradually transitioning between two human subject datasets, with the potential to generate hundreds of additional pseudoindependent phantoms from the limited bCT cases. The authors conducted a preliminary subjective assessment with a limited number of observers (n= 4) to illustrate how realistic the simulated images generated with the pseudoindependent phantoms appeared. Methods: Several mesh-based geometric transformations were developed to generate distorted breast datasets from the original human subject data. Segmented bCT data from two different human subjects were used as the “base” and “target” for morphing. Several combinations of transformations were applied to morph between the “base’ and “target” datasets such as changing the breast shape, rotating the glandular data, and changing the distribution of the glandular tissue. Following the morphing, regions of skin and fat were assigned to the morphed dataset in order to appropriately assign mechanical properties during the compression simulation. The resulting morphed breast was compressed using a finite element algorithm and simulated mammograms were generated using techniques described previously. Sixty-two simulated mammograms, generated from morphing

Radiation protection to the eye and thyroid during diagnostic cerebral angiography: a phantom study.

LENUS (Irish Health Repository)

Shortt, C P

2008-08-01

We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction. Phantom head angiographic studies were performed with bismuth (study 1) and lead shields (study 2). In study 1 (12 phantoms), thermoluminescent dosimeters (TLD) were placed over the eyes and thyroid in three groups: (i) no shields (four phantoms); (ii) anterior bismuth shields (four phantoms) and (iii) anterior and posterior bismuth shields (four phantoms). In a second study (eight phantoms), lead shields were placed over the thyroid only and TLD dose measurements obtained in two groups: (i) no shielding (four phantoms) and (ii) thyroid lead shielding (four phantoms). A standard 4-vessel cerebral angiogram was performed on each phantom. Study 1 (bismuth shields) showed higher doses to the eyes compared with thyroid (mean 13.03 vs 5.98 mSv, P < 0.001) and a higher eye dose on the X-ray tube side. Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2, a significant thyroid dose reduction was found with the use of lead shields (47%, mean 2.46 vs 4.62 mSv, P < 0.001). Considerable doses to the eyes and thyroid highlight the need for increased awareness of patient protection. Eye shielding is impractical and interferes with diagnostic capability. Thyroid lead shielding yields significant protection to the thyroid, is not in the field of view and should be used routinely.

Radiation protection to the eye and thyroid during diagnostic cerebral angiography : a phantom study

International Nuclear Information System (INIS)

Shortt, C. P.; Malone, L.; Thornton, J.; Brennan, P.; Lee, M. J.

2008-01-01

Full text: We measured radiation doses to the eye and thyroid during diagnostic cerebral angiography to assess the effectiveness of bismuth and lead shields at dose reduction. Phantom head angiographic studies were performed with bismuth (study 1) and lead shields (study 2). In study 1 (12 phantoms), thermoluminescent dosimeters (TLD) were placed over the eyes and thyroid in three groups: (i) no shields (four phantoms); (ii) anterior bismuth shields (four phantoms) and (iii) anterior and posterior bismuth shields (four phantoms). In a second study (eight phantoms), lead shields were placed over the thyroid only and TLD dose measurements obtained in two groups: (i) no shielding (four phantoms) and (ii) thyroid lead shielding (four phantoms). A standard 4-vessel cerebral angiogram was performed on each phantom. Study 1 (bismuth shields) showed higher doses to the eyes compared with thyroid (mean 13.03 vs 5.98 mSv, P < 0.001) and a higher eye dose on the X-ray tube side. Overall, the use of bismuth shielding did not significantly reduce dose to either eyes or thyroid in the measured TLD positions. In study 2, a significant thyroid dose reduction was found with the use of lead shields (47%, mean 2.46 vs 4.62 mSv, P < 0.001). Considerable doses to the eyes and thyroid highlight the need for increased awareness of patient protection. Eye shielding is impractical and interferes with diagnostic capability. Thyroid lead shielding yields significant protection to the thyroid, is not in the field of view and should be used routinely.

Construction of realistic phantoms from patient images and a commercial three-dimensional printer.

Science.gov (United States)

Leng, Shuai; Chen, Baiyu; Vrieze, Thomas; Kuhlmann, Joel; Yu, Lifeng; Alexander, Amy; Matsumoto, Jane; Morris, Jonathan; McCollough, Cynthia H

2016-07-01

The purpose of this study was to use three-dimensional (3-D) printing techniques to construct liver and brain phantoms having realistic pathologies, anatomic structures, and heterogeneous backgrounds. Patient liver and head computed tomography (CT) images were segmented into tissue, vessels, liver lesion, white and gray matter, and cerebrospinal fluid (CSF). Stereolithography files of each object were created and imported into a commercial 3-D printer. Printing materials were assigned to each object after test scans, which showed that the printing materials had CT numbers ranging from 70 to 121 HU at 120 kV. Printed phantoms were scanned on a CT scanner and images were evaluated. CT images of the liver phantom had measured CT numbers of 77.8 and 96.6 HU for the lesion and background, and 137.5 to 428.4 HU for the vessels channels, which were filled with iodine solutions. The difference in CT numbers between lesions and background (18.8 HU) was representative of the low-contrast values needed for optimization tasks. The liver phantom background was evaluated with Haralick features and showed similar texture between patient and phantom images. CT images of the brain phantom had CT numbers of 125, 134, and 108 HU for white matter, gray matter, and CSF, respectively. The CT number differences were similar to those in patient images.

Three-dimensional printer-generated patient-specific phantom for artificial in vivo dosimetry in radiotherapy quality assurance.

Science.gov (United States)

Kamomae, Takeshi; Shimizu, Hidetoshi; Nakaya, Takayoshi; Okudaira, Kuniyasu; Aoyama, Takahiro; Oguchi, Hiroshi; Komori, Masataka; Kawamura, Mariko; Ohtakara, Kazuhiro; Monzen, Hajime; Itoh, Yoshiyuki; Naganawa, Shinji

2017-12-01

Pretreatment intensity-modulated radiotherapy quality assurance is performed using simple rectangular or cylindrical phantoms; thus, the dosimetric errors caused by complex patient-specific anatomy are absent in the evaluation objects. In this study, we construct a system for generating patient-specific three-dimensional (3D)-printed phantoms for radiotherapy dosimetry. An anthropomorphic head phantom containing the bone and hollow of the paranasal sinus is scanned by computed tomography (CT). Based on surface rendering data, a patient-specific phantom is formed using a fused-deposition-modeling-based 3D printer, with a polylactic acid filament as the printing material. Radiophotoluminescence glass dosimeters can be inserted in the 3D-printed phantom. The phantom shape, CT value, and absorbed doses are compared between the actual and 3D-printed phantoms. The shape difference between the actual and printed phantoms is less than 1 mm except in the bottom surface region. The average CT value of the infill region in the 3D-printed phantom is -6 ± 18 Hounsfield units (HU) and that of the vertical shell region is 126 ± 18 HU. When the same plans were irradiated, the dose differences were generally less than 2%. These results demonstrate the feasibility of the 3D-printed phantom for artificial in vivo dosimetry in radiotherapy quality assurance. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Study on forefoot by computerized tomography

Energy Technology Data Exchange (ETDEWEB)

Machida, Eiichi (Nihon Univ., Tokyo. School of Medicine)

1983-10-01

Computerized tomography (CT) was used to study coronary sections of the forefoot in both normal and abnormal human feet. CT images of the transverse arches at the metatarsal head, middle and base of the shaft were classified into five patterns. In the pattern most commonly found in normal feet, the second metatarsus appeared elevated above the other metatarsal bones at all points, and there was a gradual and even reduction in elevation from the second to the fifth metatarsal. In cases of hallux valgus, however, a variety of deformities were noted in the arc of the second to fifth metatarsals, particularly at the head. The rotation of the first metatarsus and shift of the sesamoids were measured from CT images at the head of the first metatarsus. In hallux valgus, both the rotation and the sesamoid shift appeared to have a wider angle than in the case of normal feet. In normal feet, the differences between the rotation of the first metatarsus and shift of the sesamoids were relatively small, whereas in hallux valgus there was a much greater degree of variation. Furthermore, while normal feet the variation in rotation of the first metatarsus and sesamoid shift both tended to be either great or small, in hallux valgus a large degree of sesamoid shift was sometimes found in combination with a small degree of rotation of the first metatarsus.

Study on forefoot by computerized tomography

International Nuclear Information System (INIS)

Machida, Eiichi

1983-01-01

Computerized tomography (CT) was used to study coronary sections of the forefoot in both normal and abnormal human feet. CT images of the transverse arches at the metatarsal head, middle and base of the shaft were classified into five patterns. In the pattern most commonly found in normal feet, the second metatarsus appeared elevated above the other metatarsal bones at all points, and there was a gradual and even reduction in elevation from the second to the fifth metatarsal. In cases of hallux valgus, however, a variety of deformities were noted in the arc of the second to fifth metatarsals, particularly at the head. The rotation of the first metatarsus and shift of the sesamoids were measured from CT images at the head of the first metatarsus. In hallux valgus, both the rotation and the sesamoid shift appeared to have a wider angle than in the case of normal feet. In normal feet, the differences between the rotation of the first metatarsus and shift of the sesamoids were relatively small, whereas in hallux valgus there was a much greater degree of variation. Furthermore, while normal feet the variation in rotation of the first metatarsus and sesamoid shift both tended to be either great or small, in hallux valgus a large degree of sesamoid shift was sometimes found in combination with a small degree of rotatin of the first metatarsus. (author)

Effectiveness of mirror therapy, motor imagery, and virtual feedback on phantom limb pain following amputation: A systematic review.

Science.gov (United States)

Herrador Colmenero, Laura; Perez Marmol, Jose Manuel; Martí-García, Celia; Querol Zaldivar, María de Los Ángeles; Tapia Haro, Rosa María; Castro Sánchez, Adelaida María; Aguilar-Ferrándiz, María Encarnación

2017-11-01

Phantom limb pain is reported in 50%-85% of people with amputation. Clinical interventions in treating central pain, such as mirror therapy, motor imagery, or virtual visual feedback, could redound in benefits to amputee patients with phantom limb pain. To provide an overview of the effectiveness of different techniques for treating phantom limb pain in amputee patients. Systematic review. A computerized literature search up to April 2017 was performed using the following databases: PubMed, Scopus, CINAHL, MEDLINE, ProQuest, PEDro, EBSCOhost, and Cochrane Plus. Methodological quality and internal validity score of each study were assessed using PEDro scale. For data synthesis, qualitative methods from the Cochrane Back Review Group were applied. In all, 12 studies met our inclusion criteria, where 9 were rated as low methodological quality and 3 rated moderate quality. All studies showed a significant reduction in pain, but there was heterogeneity among subjects and methodologies and any high-quality clinical trial (PEDro score ≤8; internal validity score ≤5) was not found. Mirror therapy, motor imaginary, and virtual visual feedback reduce phantom limb pain; however, there is limited scientific evidence supporting their effectiveness. Future studies should include designs with more solid research methods, exploring short- and long-term benefits of these therapies. Clinical relevance This systematic review investigates the effectiveness of mirror therapy, motor imagery, and virtual visual feedback on phantom limb pain, summarizing the currently published trials and evaluating the research quality. Although these interventions have positive benefits in phantom limb pain, there is still a lack of evidence for supporting their effectiveness.

Phantom position dependence

International Nuclear Information System (INIS)

Thorson, M.R.; Endres, G.W.R.

1981-01-01

Sensitivity of the Hanford dosimeter response to its position relative to the phantom and the neutron source has always been recognized. A thorough investigation was performed to quantify dosimeter response according to: (a) dosimeter position on phantom, (b) dosimeter distance from phantom, and (c) angular relationship of dosimeter relative to neutron source and phantom. Results were obtained for neutron irradiation at several different energies

Computerized adaptive testing item selection in computerized adaptive learning systems

NARCIS (Netherlands)

Eggen, Theodorus Johannes Hendrikus Maria; Eggen, T.J.H.M.; Veldkamp, B.P.

2012-01-01

Item selection methods traditionally developed for computerized adaptive testing (CAT) are explored for their usefulness in item-based computerized adaptive learning (CAL) systems. While in CAT Fisher information-based selection is optimal, for recovering learning populations in CAL systems item

Influence of the phantom shape (slab, cylinder or Alderson) on the performance of an Hp(3) eye dosemeter

International Nuclear Information System (INIS)

Behrens, R.; Hupe, O.

2016-01-01

In the past, the operational quantity H p (3) was defined for calibration purposes in a slab phantom. Recently, an additional phantom in the form of a cylinder has been suggested for eye lens dosimetry, as a cylinder much better approximates the shape of a human head. Therefore, this work investigates which of the two phantoms, slab or cylinder, is more suitable for calibrations and type tests of eye dosemeters. For that purpose, a typical H p (3) eye dosemeter was irradiated on a slab, a cylinder and on a human-like Alderson phantom. It turned out that the response on the three phantoms is nearly equal for angles of radiation incidence up to 45 deg. and deviates only at larger angles of incidence. Thus, calibrations (usually performed at 0 deg. radiation incidence) are practically equivalent on both the slab and the cylinder phantoms. However, type tests (up to 75 deg. or even 90 deg. radiation incidence) should be carried out on a cylinder phantom, as also for large angles of incidence the response on the cylinder and the Alderson phantoms is rather similar, whereas the response on the slab significantly deviates from the one on the Alderson phantom. (authors)

Sequential computerized tomography changes and related final outcome in severe head injury patients

International Nuclear Information System (INIS)

Lobato, R.D.; Gomez, P.A.; Alday, R.

1997-01-01

The authors analyzed the serial computerized tomography (CT) findings in a large series of severely head injured patients in order to assess the variability in gross intracranial pathology through the acute posttraumatic period and determine the most common patterns of CT change. A second aim was to compare the prognostic significance of the different CT diagnostic categories used in the study (Traumatic Coma Data Bank CT pathological classification) when gleaned either from the initial (postadmission) or the control CT scans, and determine the extent to which having a second CT scan provides more prognostic information than only one scan. 92 patients (13.3 % of the total population) died soon after injury. Of the 587 who survived long enough to have at least one control CT scan 23.6 % developed new diffuse brain swelling, and 20.9 % new focal mass lesions most of which had to be evacuated. The relative risk for requiring a delayed operation as related to the diagnostic category established by using the initial CT scans was by decreasing order: diffuse injury IV (30.7 %), diffuse injury III (30.5 %), non evacuated mass (20 %), evacuated mass (20.2 %), diffuse injury II (12.1 %), and diffuse injury I (8.6 %). Overall, 51.2 % of the patients developed significant CT changes (for worse or better) occurring either spontaneously or following surgery, and their final outcomes were more closely related to the control than to the initial CT diagnoses. In fact, the final outcome was more accurately predicted by using the control CT scans (81.2 % of the cases) than by using the initial CT scans (71.5 % of the cases only). Since the majority of relevant CT changes developed within 48 hours after injury a pathological categorization made by using an early control CT scan seems to be most useful for prognostic purposes. Prognosis associated with the CT pathological categories used in the study was similar independently of the moment of the acute posttraumatic period at which

Quantitative computed tomography derived structural geometric accuracy using custom built anthropometric phantom of the proximal femur

International Nuclear Information System (INIS)

Khoo, B.C.C.; Price, R.; Hicks, N.

2011-01-01

Full text: Material and structural properties influence bone strength. Structural strength may be determined through imaging methods, though currently there is no commercially available phantom to assess structural geometrical (SG) accuracy. This paper describes the design of an anthropometric SG phantom of the proximal femur and the performance testing on quantitative computed tomography (QCT) derived SG outcomes. Aims of study were to determine accuracy of QCT-derived SG outcomes and its effects from kYp. The phantom consists of three basic components; femoral head, a modular and interchangeable neck insert and shaft. The interchangeable neck modules were designed with different cortical thickness and shape. QCT scans were performed with Mindways QA (Mindways Software Inc., USA) phantom, then with anthropometric phantom in water bath together with Mindways calibration phantom. All QCT scans were done on Philips 64 MDCT (Philips Healthcare, USA). Three neck modules were selected and scanned. Each neck module was repeated scanned five times at 120 mAs, 0.67 mm slice thickness and 0.33 mm increment and at 80, 120 and 140 kYps. SG parameters analysed included bone mineral density(aBMD) and outer-diameter (OD).

A two-dimensional deformable phantom for quantitatively verifying deformation algorithms

Energy Technology Data Exchange (ETDEWEB)

Kirby, Neil; Chuang, Cynthia; Pouliot, Jean [Department of Radiation Oncology, University of California San Francisco, San Francisco, California 94143-1708 (United States)

2011-08-15

Purpose: The incorporation of deformable image registration into the treatment planning process is rapidly advancing. For this reason, the methods used to verify the underlying deformation algorithms must evolve equally fast. This manuscript proposes a two-dimensional deformable phantom, which can objectively verify the accuracy of deformation algorithms, as the next step for improving these techniques. Methods: The phantom represents a single plane of the anatomy for a head and neck patient. Inflation of a balloon catheter inside the phantom simulates tumor growth. CT and camera images of the phantom are acquired before and after its deformation. Nonradiopaque markers reside on the surface of the deformable anatomy and are visible through an acrylic plate, which enables an optical camera to measure their positions; thus, establishing the ground-truth deformation. This measured deformation is directly compared to the predictions of deformation algorithms, using several similarity metrics. The ratio of the number of points with more than a 3 mm deformation error over the number that are deformed by more than 3 mm is used for an error metric to evaluate algorithm accuracy. Results: An optical method of characterizing deformation has been successfully demonstrated. For the tests of this method, the balloon catheter deforms 32 out of the 54 surface markers by more than 3 mm. Different deformation errors result from the different similarity metrics. The most accurate deformation predictions had an error of 75%. Conclusions: The results presented here demonstrate the utility of the phantom for objectively verifying deformation algorithms and determining which is the most accurate. They also indicate that the phantom would benefit from more electron density heterogeneity. The reduction of the deformable anatomy to a two-dimensional system allows for the use of nonradiopaque markers, which do not influence deformation algorithms. This is the fundamental advantage of this

Assessment of diffusion tensor image quality across sites and vendors using the American College of Radiology head phantom.

Science.gov (United States)

Wang, Zhiyue J; Seo, Youngseob; Babcock, Evelyn; Huang, Hao; Bluml, Stefan; Wisnowski, Jessica; Holshouser, Barbara; Panigrahy, Ashok; Shaw, Dennis W W; Altman, Nolan; McColl, Roderick W; Rollins, Nancy K

2016-05-08

The purpose of this study was to explore the feasibility of assessing quality of diffusion tensor imaging (DTI) from multiple sites and vendors using American College of Radiology (ACR) phantom. Participating sites (Siemens (n = 2), GE (n= 2), and Philips (n = 4)) reached consensus on parameters for DTI and used the widely available ACR phantom. Tensor data were processed at one site. B0 and eddy current distortions were assessed using grid line displacement on phantom Slice 5; signal-to-noise ratio (SNR) was measured at the center and periphery of the b = 0 image; fractional anisotropy (FA) and mean diffusivity (MD) were assessed using phantom Slice 7. Variations of acquisition parameters and deviations from specified sequence parameters were recorded. Nonlinear grid line distortion was higher with linear shimming and could be corrected using the 2nd order shimming. Following image registration, eddy current distortion was consistently smaller than acquisi-tion voxel size. SNR was consistently higher in the image periphery than center by a factor of 1.3-2.0. ROI-based FA ranged from 0.007 to 0.024. ROI-based MD ranged from 1.90 × 10-3 to 2.33 × 10-3 mm2/s (median = 2.04 × 10-3 mm2/s). Two sites had image void artifacts. The ACR phantom can be used to compare key qual-ity measures of diffusion images acquired from multiple vendors at multiple sites.

Application of the method of phantom experimental simulation for evaluation of tissue doses for the Ukrytie object personnel at the Chernobyl' NPP

International Nuclear Information System (INIS)

Shcherbina, V.G.; Kochetkov, O.A.; Sokolova, I.K.; Timofeev, L.B.; Ponomarev, V.N.; Drabkin, Yu.A.; Tsov'yanov, A.G.; Panfilenko, V.I.

1992-01-01

It is suggested to use the method of experimental phantom simulation when solving the problem of minimization of personnel external irradiation dose loading. The method discussed gives an opportunity to obtain information on dose distributions on surface, inside human body and data on dose loading for individual organs of a human organism. The phantoms, which are used for determination of the laws of external irradiation dose distribution of several positions of the machine room of the fourth unit Ukrytie object, are described. The scheme of the phantom arrangement and the values of does in organism of the human head phantom are given. 6 refs.; 7 figs.; 2 tabs

Advances in otolaryngology-Head and neck surgery. Volume 1

International Nuclear Information System (INIS)

Myers, E.N.; Bluestone, C.D.

1987-01-01

This book consists of 14 sections. The section titles are: The impact of AIDS on otolaryngology--head and neck surgery; The management of sleep apneas and snoring; Antimicrobial agents for infections in the ear, nose, and throat--head and neck; Nasal allergy: Medical and surgical treatment; Uses of computerized tomography and magnetic resonance imaging in temporal bone imaging; Surgical management of otitis media with effusion; middle ear reconstruction: Current status; Cochlear implants: an overview; Diagnosis and management of acute facial paralysis; The use of the laser in head and neck surgery; The management and prevention of subglottic stenosis in infants and children; Management of the mass in the thyroid; Suction-assisted lipectomy of the head and neck area; and Ambulatory surgery

Advances in otolaryngology-Head and neck surgery. Volume 1

Energy Technology Data Exchange (ETDEWEB)

Myers, E.N. (Univ. of Pittsburgh School of Medicine, Pittsburgh, PA (US)); Bluestone, C.D. (Univ. of Pittsburgh, Pittsburgh, PA (US))

1987-01-01

This book consists of 14 sections. The section titles are: The impact of AIDS on otolaryngology--head and neck surgery; The management of sleep apneas and snoring; Antimicrobial agents for infections in the ear, nose, and throat--head and neck; Nasal allergy: Medical and surgical treatment; Uses of computerized tomography and magnetic resonance imaging in temporal bone imaging; Surgical management of otitis media with effusion; middle ear reconstruction: Current status; Cochlear implants: an overview; Diagnosis and management of acute facial paralysis; The use of the laser in head and neck surgery; The management and prevention of subglottic stenosis in infants and children; Management of the mass in the thyroid; Suction-assisted lipectomy of the head and neck area; and Ambulatory surgery.

Dose calculation on voxels phantoms using the GEANT4 code

International Nuclear Information System (INIS)

Martins, Maximiano C.; Santos, Denison S.; Queiroz Filho, Pedro P.; Begalli, Marcia

2009-01-01

This work implemented an anthropomorphic phantom of voxels on the structure of Monte Carlo GEANT4, for utilization by professionals from the radioprotection, external dosimetry and medical physics. This phantom allows the source displacement that can be isotropic punctual, plain beam, linear or radioactive gas, in order to obtain diverse irradiation geometries. In them, the radioactive sources exposure is simulated viewing the determination of effective dose or the dose in each organ of the human body. The Zubal head and body trunk phantom was used, and we can differentiate the organs and tissues by the chemical constitution in soft tissue, lung tissue, bone tissue, water and air. The calculation method was validated through the comparison with other well established method, the Visual Monte Carlo (VMC). Besides, a comparison was done with the international recommendation for the evaluation of dose by exposure to punctual sources, described in the document TECDOC - 1162- Generic Procedures for Assessment and Response During a Radiological Emergency, where analytical expressions for this calculation are given. Considerations are made on the validity limits of these expressions for various irradiation geometries, including linear sources, immersion into clouds and contaminated soils

Rotating and translating anthropomorphic head voxel models to establish an horizontal Frankfort plane for dental CBCT Monte Carlo simulations: a dose comparison study

Science.gov (United States)

Stratis, A.; Zhang, G.; Jacobs, R.; Bogaerts, R.; Bosmans, H.

2016-12-01

In order to carry out Monte Carlo (MC) dosimetry studies, voxel phantoms, modeling human anatomy, and organ-based segmentation of CT image data sets are applied to simulation frameworks. The resulting voxel phantoms preserve patient CT acquisition geometry; in the case of head voxel models built upon head CT images, the head support with which CT scanners are equipped introduces an inclination to the head, and hence to the head voxel model. In dental cone beam CT (CBCT) imaging, patients are always positioned in such a way that the Frankfort line is horizontal, implying that there is no head inclination. The orientation of the head is important, as it influences the distance of critical radiosensitive organs like the thyroid and the esophagus from the x-ray tube. This work aims to propose a procedure to adjust head voxel phantom orientation, and to investigate the impact of head inclination on organ doses in dental CBCT MC dosimetry studies. The female adult ICRP, and three in-house-built paediatric voxel phantoms were in this study. An EGSnrc MC framework was employed to simulate two commonly used protocols; a Morita Accuitomo 170 dental CBCT scanner (FOVs: 60  ×  60 mm2 and 80  ×  80 mm2, standard resolution), and a 3D Teeth protocol (FOV: 100  ×  90 mm2) in a Planmeca Promax 3D MAX scanner. Result analysis revealed large absorbed organ dose differences in radiosensitive organs between the original and the geometrically corrected voxel models of this study, ranging from  -45.6% to 39.3%. Therefore, accurate dental CBCT MC dose calculations require geometrical adjustments to be applied to head voxel models.

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

International Nuclear Information System (INIS)

Ehler, E; Higgins, P; Dusenbery, K

2014-01-01

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use

SU-F-BRE-08: Feasibility of 3D Printed Patient Specific Phantoms for IMRT/IGRT QA

Energy Technology Data Exchange (ETDEWEB)

Ehler, E; Higgins, P; Dusenbery, K [University of Minnesota, Minneapolis, MN (United States)

2014-06-15

Purpose: Test the feasibility of 3D printed, per-patient phantoms for IMRT QA to analyze the treatment delivery quality within the patient geometry. Methods: Using the head and neck region of an anthropomorphic phantom as a substitute for an actual patient, a soft-tissue equivalent model was constructed with the use of a 3D printer. A nine-field IMRT plan was constructed and dose verification measurements were performed for the 3D printed phantom. During the delivery of the IMRT QA on to the 3D printed phantom, the same patient positioning indexing system was used on the phantom and image guidance (cone beam CT) was used to localize the phantom, serving as a test of the IGRT system as well. The 3D printed phantom was designed to accommodate four radiochromic film planes (two axial, one coronal and one sagittal) and an ionization chamber measurement. As a frame of comparison, the IMRT QA was also performed on traditional phantoms. Dosimetric tolerance levels such as 3mm / 3% Gamma Index as well as 3% and 5% dose difference were considered. All detector systems were calibrated against a NIST traceable ionization chamber. Results: Comparison of results 3D printed patient phantom with the standard IMRT QA systems showed similar passing rates for the 3D printed phantom and the standard phantoms. However, the locations of the failing regions did not necessarily correlate. The 3D printed phantom was localized within 1 mm and 1° using on-board cone beam CT. Conclusion: A custom phantom was created using a 3D printer. It was determined that the use of patient specific phantoms to perform dosimetric verification and estimate the dose in the patient is feasible. In addition, end-to-end testing on a per-patient basis was possible with the 3D printed phantom. Further refinement of the phantom construction process is needed for routine clinical use.

Head-neck-radiology; Kopf-Hals-Radiologie

Energy Technology Data Exchange (ETDEWEB)

Cohnen, Mathias (ed.) [Staedtische Kliniken Neuss Lukaskrankenhaus GmbH (Germany). Institut fuer klinische Radiologie

2012-11-01

The book on head-neck-radiology covers the following issues: (1) Methodic fundamentals: conventional radiography, angiography, sonography, computerized tomography, digital volume tomography, NMR imaging, nuclear medicine. (2) Base of the skull. (3) Petrous bone. (4) Pharynx. (5) Paranasal sinuses. (6) Eye socket. (7) Temporomandibular joint. (8) Salivary gland. (9) Oral cavity. (19) Parynx. (11) Neck soft tissue and lymph nodes. (12) Thyroid and parathyroid. (13) Teeth and jaw. (14) Interventions.

Comparison of proton therapy treatment planning for head tumors with a pencil beam algorithm on dual and single energy CT images

Energy Technology Data Exchange (ETDEWEB)

Hudobivnik, Nace; Dedes, George; Parodi, Katia; Landry, Guillaume, E-mail: g.landry@lmu.de [Department of Medical Physics, Ludwig-Maximilians-University, Munich 85748 (Germany); Schwarz, Florian; Johnson, Thorsten; Sommer, Wieland H. [Institute for Clinical Radiology, Ludwig Maximilians University Hospital Munich, 81377 Munich (Germany); Agolli, Linda [Department of Radiation Oncology, Ludwig-Maximilians-University, Munich 81377, Germany and Radiation Oncology, Sant’ Andrea Hospital, Sapienza University, Rome 00189 (Italy); Tessonnier, Thomas [Department of Medical Physics, Ludwig-Maximilians-University, Munich 85748, Germany and Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg (Germany); Verhaegen, Frank [Department of Radiation Oncology (MAASTRO), GROW School for Oncology and Developmental Biology, Maastricht 6229 ET, the Netherlands and Medical Physics Unit, Department of Oncology, McGill University, Montreal, Quebec H3A 0G4 (Canada); Thieke, Christian; Belka, Claus [Department of Radiation Oncology, Ludwig-Maximilians-University, Munich 81377 (Germany)

2016-01-15

Purpose: Dual energy CT (DECT) has recently been proposed as an improvement over single energy CT (SECT) for stopping power ratio (SPR) estimation for proton therapy treatment planning (TP), thereby potentially reducing range uncertainties. Published literature investigated phantoms. This study aims at performing proton therapy TP on SECT and DECT head images of the same patients and at evaluating whether the reported improved DECT SPR accuracy translates into clinically relevant range shifts in clinical head treatment scenarios. Methods: Two phantoms were scanned at a last generation dual source DECT scanner at 90 and 150 kVp with Sn filtration. The first phantom (Gammex phantom) was used to calibrate the scanner in terms of SPR while the second served as evaluation (CIRS phantom). DECT images of five head trauma patients were used as surrogate cancer patient images for TP of proton therapy. Pencil beam algorithm based TP was performed on SECT and DECT images and the dose distributions corresponding to the optimized proton plans were calculated using a Monte Carlo (MC) simulation platform using the same patient geometry for both plans obtained from conversion of the 150 kVp images. Range shifts between the MC dose distributions from SECT and DECT plans were assessed using 2D range maps. Results: SPR root mean square errors (RMSEs) for the inserts of the Gammex phantom were 1.9%, 1.8%, and 1.2% for SECT phantom calibration (SECT{sub phantom}), SECT stoichiometric calibration (SECT{sub stoichiometric}), and DECT calibration, respectively. For the CIRS phantom, these were 3.6%, 1.6%, and 1.0%. When investigating patient anatomy, group median range differences of up to −1.4% were observed for head cases when comparing SECT{sub stoichiometric} with DECT. For this calibration the 25th and 75th percentiles varied from −2% to 0% across the five patients. The group median was found to be limited to 0.5% when using SECT{sub phantom} and the 25th and 75th percentiles

A phantom design for assessment of detectability in PET imaging

International Nuclear Information System (INIS)

Wollenweber, Scott D.; Alessio, Adam M.; Kinahan, Paul E.

2016-01-01

Purpose: The primary clinical role of positron emission tomography (PET) imaging is the detection of anomalous regions of 18 F-FDG uptake, which are often indicative of malignant lesions. The goal of this work was to create a task-configurable fillable phantom for realistic measurements of detectability in PET imaging. Design goals included simplicity, adjustable feature size, realistic size and contrast levels, and inclusion of a lumpy (i.e., heterogeneous) background. Methods: The detection targets were hollow 3D-printed dodecahedral nylon features. The exostructure sphere-like features created voids in a background of small, solid non-porous plastic (acrylic) spheres inside a fillable tank. The features filled at full concentration while the background concentration was reduced due to filling only between the solid spheres. Results: Multiple iterations of feature size and phantom construction were used to determine a configuration at the limit of detectability for a PET/CT system. A full-scale design used a 20 cm uniform cylinder (head-size) filled with a fixed pattern of features at a contrast of approximately 3:1. Known signal-present and signal-absent PET sub-images were extracted from multiple scans of the same phantom and with detectability in a challenging (i.e., useful) range. These images enabled calculation and comparison of the quantitative observer detectability metrics between scanner designs and image reconstruction methods. The phantom design has several advantages including filling simplicity, wall-less contrast features, the control of the detectability range via feature size, and a clinically realistic lumpy background. Conclusions: This phantom provides a practical method for testing and comparison of lesion detectability as a function of imaging system, acquisition parameters, and image reconstruction methods and parameters.

A modification to the Gill-Thomas-Cosman (GTC) head frame for stereotactic radiosurgery of head and neck and cervical spine sites

International Nuclear Information System (INIS)

Qian, G.; Hasala, P.; Rashid, H.; Costantino, T.; Cangiane, L.; Lombardi, E.; Arbit, E; Lederman, G.

1996-01-01

PURPOSE/OBJECTIVE: Fractionated Stereotactic Radiosurgery (FSR) is used primarily to treat intracranial lesions. Many tumors which arise at or inferior to the base of skull and about the cervical spine area were not amenable to radiosurgery. Presented is a modification to the GTC head frame which permits stereotactic radiosurgery to be directed at head and neck tumors with accurate reproducible precision. MATERIALS AND METHODS: The original GTC head frame has two fixation points; an anterior individualized dental impression and a posterior occipital plate with a mold contoured to the occipital pertuberance. The height of the occipital plate is adjustable in its vertical plane. However, the position of the dental piece is fixed and, therefore, limits treatment to regions superior. Treatment of head and neck and cervical spine tumors has been accomplished with a modification of the dental apparatus. Presented is our new device; a bracket extension which attaches to the dental piece and allows the head frame to be lowered to multiple desired positions. The occipital plate is elevated accordingly to support the occipital pertuberance. The depth helmet is also modified for quality assurance. A Rando phantom was used to test the accuracy and reproducibility of the new equipment. Bracket extensions lowering the head frame by 3 cm and 8 cm, respectively, were tested for accuracy of relocation on the Rando Phantom. Each extension was tested 20 times and for each individual test 18 depth helmet positions were obtained. RESULTS: The standard deviation of the modified head frame for each depth helmet measurement ranged from 0.05 to 0.35mm (mean 0.20) as compared to the standard deviation for the original GTC head frame which was 0.13 to 0.34mm (mean 0.24). The new device maintains the accuracy and reproducibility of the original GTC head frame. CONCLUSION: The GTC relocatable head frame for FSR has been modified to treat tumors of the head and neck and cervical spine sites

Location of radiosensitive organs, measurement of absorbed dose to radiosensitive organs and use of bismuth shields in paediatric anthropomorphic phantoms

International Nuclear Information System (INIS)

Inkoom, S.

2014-08-01

The aim of this study was to investigate: firstly, (i) location of radiosensitive organs in the interior of four (4) paediatric anthropomorphic phantoms, and, secondly, (ii) effectiveness of single and double bismuth thyroid shields, distance between shield and phantom surface, during paediatric multi-detector computed tomography (MDCT) using fixed tube current (FTC) and automatic exposure control (AEC) on dose reduction and image quality. Four (4) paediatric anthropomorphic phantoms representing the equivalent of a newborn, 1-, 5-, and 10-y-old child underwent head, thorax and abdomen computed tomography (CT) scans. CT and magnetic resonance imaging scans of all children aged 0-16 y-old performed during a 5-y-period at the University Hospital of Heraklion, Crete, Greece were reviewed, and five hundred and three (503) were found to be eligible for normal anatomy. Anterior-posterior and lateral dimensions of twelve (12) of the above children closely matched that of the phantoms' thoracic and abdominal region in each four (4) phantoms. The mid-sagittal plane (MSP) and mid-coronal plane (MCP) were drawn on selected matching axial images of patients and phantoms. Multiple points outlining large radiosensitive organs and centres of small organs in patient images were identified at each slice level and their orthogonal distances from the MSP and MCP were measured. The outlines and centres of all radiosensitive organs were reproduced using the coordinates of each organ on the corresponding phantom's transverse images. The four (4) phantoms were also subjected to routine head and neck, neck and thorax CT scans on a 16-slice CT system. Each phantom was first scanned with both FTC and AEC for with and without bismuth shields. Each scan was repeated ten (10) times to increase thermoluminescent dosimeters (TLDs) signal and reduce measurement statistical error. For neck CT, the effect of using single and double thickness of bismuth shields and 1-3 cm cotton spacers

Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface. Cooperative research

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Uchiyama, Junzo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Endo, Kiyoshi; Yamamoto, Tetsuya; Matsumura, Akira; Nose, Tadao [Tsukuba Univ., Tsukuba, Ibaraki (Japan)

2002-12-01

Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient. (author)

Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface. Cooperative research

CERN Document Server

Yamamoto, K; Kishi, T; Kumada, H; Matsumura, A; Nose, T; Torii, Y; Uchiyama, J; Yamamoto, T

2002-01-01

Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient.

Head and hand detuning effect study of narrow-band against wide-band mobile phone antennas

DEFF Research Database (Denmark)

Bahramzy, Pevand; Pedersen, Gert Frølund

2014-01-01

Wide-band (WB) and narrow-band (NB) antennas in terms of performance are compared, when interacting with the user’s right head and hand (RHH). The investigations are done through experimental measurements, using standardised head phantom and hand. It is shown that WB antennas detune more than NB ...

Phantom pain and phantom sensations in upper limb amputees : an epidemiological study

NARCIS (Netherlands)

Kooijman, CM; Dijkstra, PU; Geertzen, JHB; Elzinga, A; van der Schans, CP

Phantom pain in subjects with an amputated limb is a well-known problem. However, estimates of the prevalence of phantom pain differ considerably in the literature. Various factors associated with phantom pain have been described including pain before the amputation, gender, dominance, and time

Individual virtual phantom reconstruction for organ dosimetry based on standard available phantoms

International Nuclear Information System (INIS)

Babapour Mofrad, F.; Aghaeizadeh Zoroofi, R.; Abbaspour Tehran Fard, A.; Akhlaghpoor, Sh.; Chen, Y. W.; Sato, Y.

2010-01-01

In nuclear medicine application often it is required to use computational methods for evaluation of organ absorbed dose. Monte Carlo Simulation and phantoms have been used in many works before. The shape, size and volume In organs are varied, and this variation will produce error in dose calculation if no correction is applied. Materials and Methods: A computational framework for constructing individual phantom for dosimetry was performed on five liver CT scan data sets of Japanese normal individuals. The Zubal phantom was used as an original phantom to be adjusted by each individual data set. This registration was done by Spherical Harmonics and Thin-Plate Spline methods. Hausdorff distance was calculated for each case. Results: Result of Hausdorff distance for five lndividual phantoms showed that before registration ranged from 140.9 to 192.1, and after registration it changed to 52.5 to 76.7. This was caused by Index similarity ranged from %56.4 to %70.3. Conclusion: A new and automatic three-dimensional (3D) phantom construction approach was-suggested for individual internal dosimetry simulation via Spherical Harmonics and Thin-Plate Spline methods. The results showed that the Individual comparable phantom can be calculated with acceptable accuracy using geometric registration. This method could be used for race-specific statistical phantom modeling with major application in nuclear medicine for absorbed dose calculation.

SU-E-J-07: IGRT Gently: Evaluating Imaging Dose in Phantoms of Different Sizes

Energy Technology Data Exchange (ETDEWEB)

Morris, B; Duggar, W; Stanford, J; Yang, C [University of Mississippi Med. Center, Jackson, MS (United States)

2015-06-15

Purpose: IGRT imaging procedures have emerged as a common method of patient position verification in radiotherapy, though imaging dose is generally neglected in the treatment plan. Consequently, evaluating and optimizing the dose from these procedures is worthwhile. This process is especially important for children, who are more radiosensitive than adults. The aim of this work was to gain some understanding of the relative doses involved with various XVI-preset parameters for an “adult” and “child” phantom set, with the hopes that imaging dose for a child can be reduced. Methods: 32 and 16cm CTDI-phantoms were used as surrogates for adult and child torsos, respectively. Dose was measured in the central and peripheral chamber positions of the phantoms. CBCT scans were made for both phantoms using Elekta’s Chest-preset to establish a dose baseline. The child-phantom was then scanned using the Elekta Head and Neck (HN) preset. A modified HN-preset (named Peds Abd-pelvis) was also created with a doubled mAs to maintain a reduction in dose to the child-phantom (relative to the baseline), while providing clinically-usable image quality. Results: The baseline dose to the child-phantom from the Chest-preset was 310% that of the adult-phantom for the center chamber position and 150% at the periphery. An average dose reduction of 97% was obtained in the childphantom by switching from the Chest-preset to the HN-preset, while the Peds Abd-pelvis-preset similarly reduced the dose by an average of 92%. Conclusion: XVI-preset parameters significantly affect dose, and should be optimized to reduce dose, while ensuring clinically-usable image quality. Using a modified imaging preset (Peds Abd-pelvis-preset) greatly reduced the dose to the child-phantom compared to the dose for the Chest-preset for both the child and adult-phantoms. This outcome provides support for the development of child-specific protocols for IGRT imaging in pediatric patients.

SU-E-J-07: IGRT Gently: Evaluating Imaging Dose in Phantoms of Different Sizes

International Nuclear Information System (INIS)

Morris, B; Duggar, W; Stanford, J; Yang, C

2015-01-01

Purpose: IGRT imaging procedures have emerged as a common method of patient position verification in radiotherapy, though imaging dose is generally neglected in the treatment plan. Consequently, evaluating and optimizing the dose from these procedures is worthwhile. This process is especially important for children, who are more radiosensitive than adults. The aim of this work was to gain some understanding of the relative doses involved with various XVI-preset parameters for an “adult” and “child” phantom set, with the hopes that imaging dose for a child can be reduced. Methods: 32 and 16cm CTDI-phantoms were used as surrogates for adult and child torsos, respectively. Dose was measured in the central and peripheral chamber positions of the phantoms. CBCT scans were made for both phantoms using Elekta’s Chest-preset to establish a dose baseline. The child-phantom was then scanned using the Elekta Head and Neck (HN) preset. A modified HN-preset (named Peds Abd-pelvis) was also created with a doubled mAs to maintain a reduction in dose to the child-phantom (relative to the baseline), while providing clinically-usable image quality. Results: The baseline dose to the child-phantom from the Chest-preset was 310% that of the adult-phantom for the center chamber position and 150% at the periphery. An average dose reduction of 97% was obtained in the childphantom by switching from the Chest-preset to the HN-preset, while the Peds Abd-pelvis-preset similarly reduced the dose by an average of 92%. Conclusion: XVI-preset parameters significantly affect dose, and should be optimized to reduce dose, while ensuring clinically-usable image quality. Using a modified imaging preset (Peds Abd-pelvis-preset) greatly reduced the dose to the child-phantom compared to the dose for the Chest-preset for both the child and adult-phantoms. This outcome provides support for the development of child-specific protocols for IGRT imaging in pediatric patients

A digital phantom of the axilla based on the Visible Human Project data set

Science.gov (United States)

McCallum, S. J.; Welch, A. E.; Baker, L.

2001-08-01

In this paper, we describe the development of a new digital phantom designed for Monte Carlo simulations of breast cancer and particularly positron emission tomography (PET) imaging of the axillary lymph nodes. The phantom was based on data from the Visible Human Project female data set. The phantom covers the head-to-diaphragm regions; 17 major tissue types were segmented and 66 individual lymph nodes were identified. The authors have used the phantom in Monte Carlo simulations to model a reduced field-of-view PET imager based on two flat plate arrays placed on either side of the shoulder. Images used a simple single angle set of projections. The authors have conducted two preliminary studies: one modeling a single-frame PET acquisition 60 min after FDG injection and the other modeling a dynamic PET acquisition simulating four time frames after FDG injection. The dynamic results were processed into parametric images using the Patlak method and show the advantage to be gained by including the temporal information for legion detection. The authors' preliminary results indicate that the performance of such an imager forming projection images is not sufficient for axillary node PET imaging.

Pediatric Phantom Dosimetry of Kodak 9000 Cone-beam Computed Tomography.

Science.gov (United States)

Yepes, Juan F; Booe, Megan R; Sanders, Brian J; Jones, James E; Ehrlich, Ygal; Ludlow, John B; Johnson, Brandon

2017-05-15

The purpose of the study was to evaluate the radiation dose of the Kodak 9000 cone-beam computed tomography (CBCT) device for different anatomical areas using a pediatric phantom. Absorbed doses resulting from maxillary and mandibular region three by five cm CBCT volumes of an anthropomorphic 10-year-old child phantom were acquired using optical stimulated dosimetry. Equivalent doses were calculated for radiosensitive tissues in the head and neck area, and effective dose for maxillary and mandibular examinations were calculated following the 2007 recommendations of the International Commission on Radiological Protection (ICRP). Of the mandibular scans, the salivary glands had the highest equivalent dose (1,598 microsieverts [μSv]), followed by oral mucosa (1,263 μSv), extrathoracic airway (pharynx, larynx, and trachea; 859 μSv), and thyroid gland (578 μSv). For the maxilla, the salivary glands had the highest equivalent dose (1,847 μSv), followed closely by oral mucosa (1,673 μSv), followed by the extrathoracic airway (pharynx, larynx, and trachea; 1,011 μSv) and lens of the eye (202 μSv). Compared to previous research of the Kodak 9000, completed with the adult phantom, a child receives one to three times more radiation for mandibular scans and two to 10 times more radiation for maxillary scans.

A study of the short- to long-phantom dose ratios for CT scanning without table translation

Energy Technology Data Exchange (ETDEWEB)

Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu [Division of Diagnostic Imaging Physics, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 and Webster Center for Advanced Research and Education in Radiation, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts 02114 (United States); Yang, Jie [Pinnacle Health - Fox Chase Regional Cancer Center, Harrisburg, Pennsylvania 17109 (United States)

2014-09-15

Purpose: For CT scanning in the stationary-table modes, AAPM Task Group 111 proposed to measure the midpoint dose on the central and peripheral axes of sufficiently long phantoms. Currently, a long cylindrical phantom is usually not available in many clinical facilities. The use of a long phantom is also challenging because of the heavy weight. In order to shed light on assessing the midpoint dose in CT scanning without table movement, the authors present a study of the short- to long-phantom dose ratios, and perform a cross-comparison of CT dose ratios on different scanner models. Methods: The authors performed Geant4-based Monte Carlo simulations with a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare), and modeled dosimetry measurements using a 0.6 cm{sup 3} Farmer type chamber and a 10-cm long pencil ion chamber. The short (15 cm) to long (90 cm) phantom dose ratios were computed for two PMMA diameters (16 and 32 cm), two phantom axes (the center and the periphery), and a range of beam apertures (3–25 cm). The results were compared with the published data of previous studies with other multiple detector CT (MDCT) scanners and cone beam CT (CBCT) scanners. Results: The short- to long-phantom dose ratios changed with beam apertures but were insensitive to beam qualities (80–140 kV, the head and body bowtie filters) and MDCT and CBCT scanner models. Conclusions: The short- to long-phantom dose ratios enable medical physicists to make dosimetry measurements using the standard CT dosimetry phantoms and a Farmer chamber or a 10 cm long pencil chamber, and to assess the midpoint dose in long phantoms. This method provides an effective approach for the dosimetry of CBCT scanning in the stationary-table modes, and is useful for perfusion and interventional CT.

A study of the short- to long-phantom dose ratios for CT scanning without table translation

International Nuclear Information System (INIS)

Li, Xinhua; Zhang, Da; Liu, Bob; Yang, Jie

2014-01-01

Purpose: For CT scanning in the stationary-table modes, AAPM Task Group 111 proposed to measure the midpoint dose on the central and peripheral axes of sufficiently long phantoms. Currently, a long cylindrical phantom is usually not available in many clinical facilities. The use of a long phantom is also challenging because of the heavy weight. In order to shed light on assessing the midpoint dose in CT scanning without table movement, the authors present a study of the short- to long-phantom dose ratios, and perform a cross-comparison of CT dose ratios on different scanner models. Methods: The authors performed Geant4-based Monte Carlo simulations with a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare), and modeled dosimetry measurements using a 0.6 cm 3 Farmer type chamber and a 10-cm long pencil ion chamber. The short (15 cm) to long (90 cm) phantom dose ratios were computed for two PMMA diameters (16 and 32 cm), two phantom axes (the center and the periphery), and a range of beam apertures (3–25 cm). The results were compared with the published data of previous studies with other multiple detector CT (MDCT) scanners and cone beam CT (CBCT) scanners. Results: The short- to long-phantom dose ratios changed with beam apertures but were insensitive to beam qualities (80–140 kV, the head and body bowtie filters) and MDCT and CBCT scanner models. Conclusions: The short- to long-phantom dose ratios enable medical physicists to make dosimetry measurements using the standard CT dosimetry phantoms and a Farmer chamber or a 10 cm long pencil chamber, and to assess the midpoint dose in long phantoms. This method provides an effective approach for the dosimetry of CBCT scanning in the stationary-table modes, and is useful for perfusion and interventional CT

SU-G-TeP2-12: IROCHouston and MDAPL SRS Anthropomorphic Phantom Results

International Nuclear Information System (INIS)

Molineu, A; Kry, S; Alvarez, P; Hernandez, N; Nguyen, T; Followill, D

2016-01-01

Purpose: To report the results of SRS phantom irradiations Methods: Anthropomorphic SRS head phantoms were sent to institutions participating in NCI sponsored SRS clinical trials and institutions interested in verifying SRS treatment delivery. The phantom shell was purchased from Phantom Laboratory and altered to house dosimetry and imaging inserts. The imaging insert has 1.9 cm diameter spherical target. The dosimetry insert holds two TLD capsules and radiochromic film in the coronal and sagittal planes through the center of the target. Institutions were asked to image, plan and treat the phantom as they would an SRS patient. GammaKnife, CyberKnife and c-arm accelerator institutions were asked to cover the target with 15 Gy, 20 Gy and 25 Gy, respectively. Following these guidelines and typical planning protocols for these three types of machines gives roughly 30 Gy to the center of the target for all units. Submission of the DICOM digital data set was required for analysis. Criteria of 5% for TLD results and 85% of pixels passing 5%/3mm gamma analysis were applied beginning in 2013. Results: The phantom was analyzed 269 times between the beginning of 2013 to present. The pass rate is 81%. Nineteen of the irradiation results failed only the TLD criteria, 19 failed only the film criteria and 12 failed both. Irradiations included 32 CyberKnife 23 GammaKnife, 3 TomoTherapy and 211 c-arm units. Planning systems included Eclipse, Ergo, GammaPlan, Hi-Art, iPlan, Monaco, MultiPlan, Pinnacle, RayStation, XiO and XKnife. Irradiations that were not accompanied with DICOM data were not included in this analysis. Conclusion: The phantom is a valuable end-to-end test used to independently verify the accuracy of SRS treatment delivery. This investigation was supported by IROC grant CA180803 awarded by the NCI.

An innovative phantom for quantitative and qualitative investigation of advanced x-ray imaging technologies

International Nuclear Information System (INIS)

Chiarot, C B; Siewerdsen, J H; Haycocks, T; Moseley, D J; Jaffray, D A

2005-01-01

Development, characterization, and quality assurance of advanced x-ray imaging technologies require phantoms that are quantitative and well suited to such modalities. This note reports on the design, construction, and use of an innovative phantom developed for advanced imaging technologies (e.g., multi-detector CT and the numerous applications of flat-panel detectors in dual-energy imaging, tomosynthesis, and cone-beam CT) in diagnostic and image-guided procedures. The design addresses shortcomings of existing phantoms by incorporating criteria satisfied by no other single phantom: (1) inserts are fully 3D-spherically symmetric rather than cylindrical; (2) modules are quantitative, presenting objects of known size and contrast for quality assurance and image quality investigation; (3) features are incorporated in ideal and semi-realistic (anthropomorphic) contexts; and (4) the phantom allows devices to be inserted and manipulated in an accessible module (right lung). The phantom consists of five primary modules: (1) head, featuring contrast-detail spheres approximate to brain lesions; (2) left lung, featuring contrast-detail spheres approximate to lung modules; (3) right lung, an accessible hull in which devices may be placed and manipulated; (4) liver, featuring conrast-detail spheres approximate to metastases; and (5) abdomen/pelvis, featuring simulated kidneys, colon, rectum, bladder, and prostate. The phantom represents a two-fold evolution in design philosophy-from 2D (cylindrically symmetric) to fully 3D, and from exclusively qualitative or quantitative to a design accommodating quantitative study within an anatomical context. It has proven a valuable tool in investigations throughout our institution, including low-dose CT, dual-energy radiography, and cone-beam CT for image-guided radiation therapy and surgery. (note)

All about FAX: a Female Adult voXel phantom for Monte Carlo calculation in radiation protection dosimetry.

Science.gov (United States)

Kramer, R; Khoury, H J; Vieira, J W; Loureiro, E C M; Lima, V J M; Lima, F R A; Hoff, G

2004-12-07

The International Commission on Radiological Protection (ICRP) has created a task group on dose calculations, which, among other objectives, should replace the currently used mathematical MIRD phantoms by voxel phantoms. Voxel phantoms are based on digital images recorded from scanning of real persons by computed tomography or magnetic resonance imaging (MRI). Compared to the mathematical MIRD phantoms, voxel phantoms are true to the natural representations of a human body. Connected to a radiation transport code, voxel phantoms serve as virtual humans for which equivalent dose to organs and tissues from exposure to ionizing radiation can be calculated. The principal database for the construction of the FAX (Female Adult voXel) phantom consisted of 151 CT images recorded from scanning of trunk and head of a female patient, whose body weight and height were close to the corresponding data recommended by the ICRP in Publication 89. All 22 organs and tissues at risk, except for the red bone marrow and the osteogenic cells on the endosteal surface of bone ('bone surface'), have been segmented manually with a technique recently developed at the Departamento de Energia Nuclear of the UFPE in Recife, Brazil. After segmentation the volumes of the organs and tissues have been adjusted to agree with the organ and tissue masses recommended by ICRP for the Reference Adult Female in Publication 89. Comparisons have been made with the organ and tissue masses of the mathematical EVA phantom, as well as with the corresponding data for other female voxel phantoms. The three-dimensional matrix of the segmented images has eventually been connected to the EGS4 Monte Carlo code. Effective dose conversion coefficients have been calculated for exposures to photons, and compared to data determined for the mathematical MIRD-type phantoms, as well as for other voxel phantoms.

3D dose distribution calculation in a voxelized human phantom by means of Monte Carlo method

International Nuclear Information System (INIS)

Abella, V.; Miro, R.; Juste, B.; Verdu, G.

2010-01-01

The aim of this work is to provide the reconstruction of a real human voxelized phantom by means of a MatLab program and the simulation of the irradiation of such phantom with the photon beam generated in a Theratron 780 (MDS Nordion) 60 Co radiotherapy unit, by using the Monte Carlo transport code MCNP (Monte Carlo N-Particle), version 5. The project results in 3D dose mapping calculations inside the voxelized antropomorphic head phantom. The program provides the voxelization by first processing the CT slices; the process follows a two-dimensional pixel and material identification algorithm on each slice and three-dimensional interpolation in order to describe the phantom geometry via small cubic cells, resulting in an MCNP input deck format output. Dose rates are calculated by using the MCNP5 tool FMESH, superimposed mesh tally, which gives the track length estimation of the particle flux in units of particles/cm 2 . Furthermore, the particle flux is converted into dose by using the conversion coefficients extracted from the NIST Physical Reference Data. The voxelization using a three-dimensional interpolation technique in combination with the use of the FMESH tool of the MCNP Monte Carlo code offers an optimal simulation which results in 3D dose mapping calculations inside anthropomorphic phantoms. This tool is very useful in radiation treatment assessments, in which voxelized phantoms are widely utilized.

γTools: A modular multifunction phantom for quality assurance in GammaKnife treatments.

Science.gov (United States)

Calusi, Silvia; Noferini, Linhsia; Marrazzo, Livia; Casati, Marta; Arilli, Chiara; Compagnucci, Antonella; Talamonti, Cinzia; Scoccianti, Silvia; Greto, Daniela; Bordi, Lorenzo; Livi, Lorenzo; Pallotta, Stefania

2017-11-01

We present the γTools, a new phantom designed to assess geometric and dosimetric accuracy in Gamma Knife treatments, together with first tests and results of applications. The phantom is composed of two modules: the imaging module, a regular grid of 1660 control points to evaluate image distortions and image registration result and the dosimetry module for delivered dose distribution measurements. The phantom is accompanied by a MatLab routine for image distortions quantification. Dose measurement are performed with Gafchromic films fixed between two inserts and placed in various positions and orientations inside the dosimetry module thus covering a volume comparable to the full volume of a head. Tests performed to assess the accuracy and precision of the imaging module demonstrated sub-millimetric values. As an example of possible applications, the phantom was employed to measure image distortions of two MRI scanners and to perform dosimetric studies of single shots delivered to homogeneous and heterogeneous materials. Due to the phantom material, the measured absolute dose do not correspond to the planned dose; doses comparisons are thus carried out between normalized dose distributions. Finally, an end-to-end test was carried out in the treatment of a neuroma-like target which resulted in a 100% gamma passing rate (2% local, 2 mm) and a distance between the real target perimeter and the prescription isodose centroids of about 1 mm. The tests demonstrate that the proposed phantom is suitable to assess both the geometrical and relative dosimetric accuracy of Gamma Knife radiosurgery treatments. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Analysis of mobile phone design features affecting radiofrequency power absorbed in a human head phantom.

Science.gov (United States)

Kuehn, Sven; Kelsh, Michael A; Kuster, Niels; Sheppard, Asher R; Shum, Mona

2013-09-01

The US FCC mandates the testing of all mobile phones to demonstrate compliance with the rule requiring that the peak spatial SAR does not exceed the limit of 1.6 W/kg averaged over any 1 g of tissue. These test data, measured in phantoms with mobile phones operating at maximum antenna input power, permitted us to evaluate the variation in SARs across mobile phone design factors such as shape and antenna design, communication technology, and test date (over a 7-year period). Descriptive statistical summaries calculated for 850 MHz and 1900 MHz phones and ANOVA were used to evaluate the influence of the foregoing factors on SARs. Service technology accounted for the greatest variability in compliance test SARs that ranged from AMPS (highest) to CDMA, iDEN, TDMA, and GSM (lowest). However, the dominant factor for SARs during use is the time-averaged antenna input power, which may be much less than the maximum power used in testing. This factor is largely defined by the communication system; e.g., the GSM phone average output can be higher than CDMA by a factor of 100. Phone shape, antenna type, and orientation of a phone were found to be significant but only on the order of up to a factor of 2 (3 dB). The SAR in the tilt position was significantly smaller than for touch. The side of the head did not affect SAR levels significantly. Among the remaining factors, external antennae produced greater SARs than internal ones, and brick and clamshell phones produced greater SARs than slide phones. Assuming phone design and usage patterns do not change significantly over time, we have developed a normalization procedure and formula that permits reliable prediction of the relative SAR between various communication systems. This approach can be applied to improve exposure assessment in epidemiological research. Copyright © 2013 Wiley Periodicals, Inc.

Results From the Imaging and Radiation Oncology Core Houston's Anthropomorphic Phantoms Used for Proton Therapy Clinical Trial Credentialing

Energy Technology Data Exchange (ETDEWEB)

Taylor, Paige A., E-mail: pataylor@mdanderson.org; Kry, Stephen F.; Alvarez, Paola; Keith, Tyler; Lujano, Carrie; Hernandez, Nadia; Followill, David S.

2016-05-01

Purpose: The purpose of this study was to summarize the findings of anthropomorphic proton phantom irradiations analyzed by the Imaging and Radiation Oncology Core Houston QA Center (IROC Houston). Methods and Materials: A total of 103 phantoms were irradiated by proton therapy centers participating in clinical trials. The anthropomorphic phantoms simulated heterogeneous anatomy of a head, liver, lung, prostate, and spine. Treatment plans included those for scattered, uniform scanning, and pencil beam scanning beam delivery modalities using 5 different treatment planning systems. For every phantom irradiation, point doses and planar doses were measured using thermoluminescent dosimeters (TLD) and film, respectively. Differences between measured and planned doses were studied as a function of phantom, beam delivery modality, motion, repeat attempt, treatment planning system, and date of irradiation. Results: The phantom pass rate (overall, 79%) was high for simple phantoms and lower for phantoms that introduced higher levels of difficulty, such as motion, multiple targets, or increased heterogeneity. All treatment planning systems overestimated dose to the target, compared to TLD measurements. Errors in range calculation resulted in several failed phantoms. There was no correlation between treatment planning system and pass rate. The pass rates for each individual phantom are not improving over time, but when individual institutions received feedback about failed phantom irradiations, pass rates did improve. Conclusions: The proton phantom pass rates are not as high as desired and emphasize potential deficiencies in proton therapy planning and/or delivery. There are many areas for improvement with the proton phantom irradiations, such as treatment planning system dose agreement, range calculations, accounting for motion, and irradiation of multiple targets.

Phantom pain after eye amputation

DEFF Research Database (Denmark)

Rasmussen, Marie L R; Prause, Jan U; Toft, Peter B

2011-01-01

Purpose: To characterize the quality of phantom pain, its intensity and frequency following eye amputation. Possible triggers and relievers of phantom pain are investigated. Methods: The hospital database was searched using surgery codes for patients who received ocular evisceration, enucleation...... was conducted by a trained interviewer. Results: Of the 173 patients in the study, 39 experienced phantom pain. The median age of patients who had experienced phantom pain was 45 years (range: 19–88). Follow-up time from eye amputation to participation in the investigation was 4 years (range: 2–46). Phantom...... scale, ranging from 0 to 100, was 36 (range: 1–89). One-third of the patients experienced phantom pain every day. Chilliness, windy weather and psychological stress/fatigue were the most commonly reported triggers for pain. Conclusions: Phantom pain after eye amputation is relatively common. The pain...

Hybrid pregnant reference phantom series based on adult female ICRP reference phantom

Science.gov (United States)

Rafat-Motavalli, Laleh; Miri-Hakimabad, Hashem; Hoseinian-Azghadi, Elie

2018-03-01

This paper presents boundary representation (BREP) models of pregnant female and her fetus at the end of each trimester. The International Commission on Radiological Protection (ICRP) female reference voxel phantom was used as a base template in development process of the pregnant hybrid phantom series. The differences in shape and location of the displaced maternal organs caused by enlarging uterus were also taken into account. The CT and MR images of fetus specimens and pregnant patients of various ages were used to replace the maternal abdominal pelvic organs of template phantom and insert the fetus inside the gravid uterus. Each fetal model contains 21 different organs and tissues. The skeletal model of the fetus also includes age-dependent cartilaginous and ossified skeletal components. The replaced maternal organ models were converted to NURBS surfaces and then modified to conform to reference values of ICRP Publication 89. The particular feature of current series compared to the previously developed pregnant phantoms is being constructed upon the basis of ICRP reference phantom. The maternal replaced organ models are NURBS surfaces. With this great potential, they might have the feasibility of being converted to high quality polygon mesh phantoms.

NOTE: An innovative phantom for quantitative and qualitative investigation of advanced x-ray imaging technologies

Science.gov (United States)

Chiarot, C. B.; Siewerdsen, J. H.; Haycocks, T.; Moseley, D. J.; Jaffray, D. A.

2005-11-01

Development, characterization, and quality assurance of advanced x-ray imaging technologies require phantoms that are quantitative and well suited to such modalities. This note reports on the design, construction, and use of an innovative phantom developed for advanced imaging technologies (e.g., multi-detector CT and the numerous applications of flat-panel detectors in dual-energy imaging, tomosynthesis, and cone-beam CT) in diagnostic and image-guided procedures. The design addresses shortcomings of existing phantoms by incorporating criteria satisfied by no other single phantom: (1) inserts are fully 3D—spherically symmetric rather than cylindrical; (2) modules are quantitative, presenting objects of known size and contrast for quality assurance and image quality investigation; (3) features are incorporated in ideal and semi-realistic (anthropomorphic) contexts; and (4) the phantom allows devices to be inserted and manipulated in an accessible module (right lung). The phantom consists of five primary modules: (1) head, featuring contrast-detail spheres approximate to brain lesions; (2) left lung, featuring contrast-detail spheres approximate to lung modules; (3) right lung, an accessible hull in which devices may be placed and manipulated; (4) liver, featuring conrast-detail spheres approximate to metastases; and (5) abdomen/pelvis, featuring simulated kidneys, colon, rectum, bladder, and prostate. The phantom represents a two-fold evolution in design philosophy—from 2D (cylindrically symmetric) to fully 3D, and from exclusively qualitative or quantitative to a design accommodating quantitative study within an anatomical context. It has proven a valuable tool in investigations throughout our institution, including low-dose CT, dual-energy radiography, and cone-beam CT for image-guided radiation therapy and surgery.

Development of realistic physical breast phantoms matched to virtual breast phantoms based on human subject data

International Nuclear Information System (INIS)

Kiarashi, Nooshin; Nolte, Adam C.; Sturgeon, Gregory M.; Ghate, Sujata V.; Segars, William P.; Nolte, Loren W.; Samei, Ehsan

2015-01-01

Purpose: Physical phantoms are essential for the development, optimization, and evaluation of x-ray breast imaging systems. Recognizing the major effect of anatomy on image quality and clinical performance, such phantoms should ideally reflect the three-dimensional structure of the human breast. Currently, there is no commercially available three-dimensional physical breast phantom that is anthropomorphic. The authors present the development of a new suite of physical breast phantoms based on human data. Methods: The phantoms were designed to match the extended cardiac-torso virtual breast phantoms that were based on dedicated breast computed tomography images of human subjects. The phantoms were fabricated by high-resolution multimaterial additive manufacturing (3D printing) technology. The glandular equivalency of the photopolymer materials was measured relative to breast tissue-equivalent plastic materials. Based on the current state-of-the-art in the technology and available materials, two variations were fabricated. The first was a dual-material phantom, the Doublet. Fibroglandular tissue and skin were represented by the most radiographically dense material available; adipose tissue was represented by the least radiographically dense material. The second variation, the Singlet, was fabricated with a single material to represent fibroglandular tissue and skin. It was subsequently filled with adipose-equivalent materials including oil, beeswax, and permanent urethane-based polymer. Simulated microcalcification clusters were further included in the phantoms via crushed eggshells. The phantoms were imaged and characterized visually and quantitatively. Results: The mammographic projections and tomosynthesis reconstructed images of the fabricated phantoms yielded realistic breast background. The mammograms of the phantoms demonstrated close correlation with simulated mammographic projection images of the corresponding virtual phantoms. Furthermore, power

Development of realistic physical breast phantoms matched to virtual breast phantoms based on human subject data

Energy Technology Data Exchange (ETDEWEB)

Kiarashi, Nooshin [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Nolte, Adam C. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Sturgeon, Gregory M.; Ghate, Sujata V. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Segars, William P. [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 and Medical Physics Graduate Program, Duke University, Durham, North Carolina 27708 (United States); Nolte, Loren W. [Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 and Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Samei, Ehsan [Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina 27710 (United States); Department of Electrical and Computer Engineering, Duke University, Durham, North Carolina 27708 (United States); Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708 (United States); Medical Physics Graduate Program, Duke University, Durham, North Carolina 27708 (United States); Department of Physics, Duke University, Durham, North Carolina 27708 (United States); and others

2015-07-15

Purpose: Physical phantoms are essential for the development, optimization, and evaluation of x-ray breast imaging systems. Recognizing the major effect of anatomy on image quality and clinical performance, such phantoms should ideally reflect the three-dimensional structure of the human breast. Currently, there is no commercially available three-dimensional physical breast phantom that is anthropomorphic. The authors present the development of a new suite of physical breast phantoms based on human data. Methods: The phantoms were designed to match the extended cardiac-torso virtual breast phantoms that were based on dedicated breast computed tomography images of human subjects. The phantoms were fabricated by high-resolution multimaterial additive manufacturing (3D printing) technology. The glandular equivalency of the photopolymer materials was measured relative to breast tissue-equivalent plastic materials. Based on the current state-of-the-art in the technology and available materials, two variations were fabricated. The first was a dual-material phantom, the Doublet. Fibroglandular tissue and skin were represented by the most radiographically dense material available; adipose tissue was represented by the least radiographically dense material. The second variation, the Singlet, was fabricated with a single material to represent fibroglandular tissue and skin. It was subsequently filled with adipose-equivalent materials including oil, beeswax, and permanent urethane-based polymer. Simulated microcalcification clusters were further included in the phantoms via crushed eggshells. The phantoms were imaged and characterized visually and quantitatively. Results: The mammographic projections and tomosynthesis reconstructed images of the fabricated phantoms yielded realistic breast background. The mammograms of the phantoms demonstrated close correlation with simulated mammographic projection images of the corresponding virtual phantoms. Furthermore, power

Estimating effective dose to pediatric patients undergoing interventional radiology procedures using anthropomorphic phantoms and MOSFET dosimeters.

Science.gov (United States)

Miksys, Nelson; Gordon, Christopher L; Thomas, Karen; Connolly, Bairbre L

2010-05-01

The purpose of this study was to estimate the effective doses received by pediatric patients during interventional radiology procedures and to present those doses in "look-up tables" standardized according to minute of fluoroscopy and frame of digital subtraction angiography (DSA). Organ doses were measured with metal oxide semiconductor field effect transistor (MOSFET) dosimeters inserted within three anthropomorphic phantoms, representing children at ages 1, 5, and 10 years, at locations corresponding to radiosensitive organs. The phantoms were exposed to mock interventional radiology procedures of the head, chest, and abdomen using posteroanterior and lateral geometries, varying magnification, and fluoroscopy or DSA exposures. Effective doses were calculated from organ doses recorded by the MOSFET dosimeters and are presented in look-up tables according to the different age groups. The largest effective dose burden for fluoroscopy was recorded for posteroanterior and lateral abdominal procedures (0.2-1.1 mSv/min of fluoroscopy), whereas procedures of the head resulted in the lowest effective doses (0.02-0.08 mSv/min of fluoroscopy). DSA exposures of the abdomen imparted higher doses (0.02-0.07 mSv/DSA frame) than did those involving the head and chest. Patient doses during interventional procedures vary significantly depending on the type of procedure. User-friendly look-up tables may provide a helpful tool for health care providers in estimating effective doses for an individual procedure.

Developing optimized CT scan protocols: Phantom measurements of image quality

International Nuclear Information System (INIS)

Zarb, Francis; Rainford, Louise; McEntee, Mark F.

2011-01-01

Purpose: The increasing frequency of computerized tomography (CT) examinations is well documented, leading to concern about potential radiation risks for patients. However, the consequences of not performing the CT examination and missing injuries and disease are potentially serious, impacting upon correct patient management. The ALARA principle of dose optimization must be employed for all justified CT examinations. Dose indicators displayed on the CT console as either CT dose index (CTDI) and/or dose length product (DLP), are used to indicate dose and can quantify improvements achieved through optimization. Key scan parameters contributing to dose have been identified in previous literature and in previous work by our group. The aim of this study was to optimize the scan parameters of mA; kV and pitch, whilst maintaining image quality and reducing dose. This research was conducted using psychophysical image quality measurements on a CT quality assurance (QA) phantom establishing the impact of dose optimization on image quality parameters. Method: Current CT scan parameters for head (posterior fossa and cerebrum), abdomen and chest examinations were collected from 57% of CT suites available nationally in Malta (n = 4). Current scan protocols were used to image a Catphan 600 CT QA phantom whereby image quality was assessed. Each scan parameter: mA; kV and pitch were systematically reduced until the contrast resolution (CR), spatial resolution (SR) and noise were significantly lowered. The Catphan 600 images, produced by the range of protocols, were evaluated by 2 expert observers assessing CR, SR and noise. The protocol considered as the optimization threshold was just above the setting that resulted in a significant reduction in CR and noise but not affecting SR at the 95% confidence interval. Results: The limit of optimization threshold was determined for each CT suite. Employing optimized parameters, CTDI and DLP were both significantly reduced (p ≤ 0.001) by

3 Tesla MRI of patients with a vagus nerve stimulator: initial experience using a T/R head coil under controlled conditions.

Science.gov (United States)

Gorny, Krzysztof R; Bernstein, Matt A; Watson, Robert E

2010-02-01

To assess safety of clinical MRI of the head in patients with implanted model 100, 102, and 103 vagus nerve stimulation (VNS) Therapy Systems (Cyberonics, Inc., Houston, TX) in 3.0 Tesla MRI (GE Healthcare, Milwaukee, WI). The distributions of the radiofrequency B(1) (+)-field produced by the clinically used transmit/receive (T/R) head coil (Advanced Imaging Research Incorporated, Cleveland, OH) and body coil were measured in a head and shoulders phantom. These measurements were supplemented by temperature measurements on the lead tips and the implantable pulse generator (IPG) of the VNS devices in a head and torso phantom with the same two coils. Clinical 3T MRI head scans were then acquired under highly controlled conditions in a series of 17 patients implanted with VNS. Phantom studies showed only weak B(1) (+) fields at the location of the VNS IPG and leads for MRI scans using the T/R head coil. The MRI-related heating on a VNS scanned in vitro at 3T was also found to be minimal (0.4-0.8 degrees C at the leads, negligible at the IPG). The patient MRI examinations were completed successfully without any adverse incidents. No patient reported any heating, discomfort, or any other unusual sensation. Safe clinical MRI head scanning of patients with implanted VNS is shown to be feasible on a GE Signa Excite 3T MRI system using one specific T/R head coil. These results apply to this particular MRI system configuration. Extrapolation or generalization of these results to more general or less controlled imaging situations without supporting data of safety is highly discouraged.

Regional cerebral blood flow during rest and skilled hand movements by xenon-133 inhalation and emission computerized tomography

DEFF Research Database (Denmark)

Lauritzen, M; Henriksen, L; Lassen, N A

1981-01-01

Regional cerebral blood flow (CBF) was studied in 16 normal adult volunteers during rest and in 10 the study was repeated during skilled hand movements. A fast-rotating ("dynamic"), single-photon emission computerized tomograph (ECT) with four detector heads was used. Xenon-133 was inhaled over a 1...... motor area on both sides by 34 +/- 15% (p less than 0.025)....

Computerizing primary schools in rural kenya

DEFF Research Database (Denmark)

Ogembo, J.G.; Ngugi, B.; Pelowski, Matthew John

2012-01-01

questions surrounding this endeavour. Specifically: 1.) what problems do rural schools actually want to solve with computerization; 2.) is computerization the most important priority for rural schools; 3.) are schools ready, in terms of infrastructure, for a computer in the classroom; or 4.) might...... and protective roofing -posing severe challenges to the outstanding conception of computerization. We consider these results and make recommendations for better adapting programs for computer introduction, and also suggest the use of new innovative devices, such as cell phones, which might already have overcome......This paper investigates the outstanding challenges facing primary schools' computerization in rural Kenya. Computerization of schools is often envisaged as a 'magic', or at least a particularly efficient, solution to many of the problems that developing countries face in improving primary school...

Evaluation of the usefulness of a MOSFET detector in an anthropomorphic phantom for 6-MV photon beam.

Science.gov (United States)

Kohno, Ryosuke; Hirano, Eriko; Kitou, Satoshi; Goka, Tomonori; Matsubara, Kana; Kameoka, Satoru; Matsuura, Taeko; Ariji, Takaki; Nishio, Teiji; Kawashima, Mitsuhiko; Ogino, Takashi

2010-07-01

In order to evaluate the usefulness of a metal oxide-silicon field-effect transistor (MOSFET) detector as a in vivo dosimeter, we performed in vivo dosimetry using the MOSFET detector with an anthropomorphic phantom. We used the RANDO phantom as an anthropomorphic phantom, and dose measurements were carried out in the abdominal, thoracic, and head and neck regions for simple square field sizes of 10 x 10, 5 x 5, and 3 x 3 cm(2) with a 6-MV photon beam. The dose measured by the MOSFET detector was verified by the dose calculations of the superposition (SP) algorithm in the XiO radiotherapy treatment-planning system. In most cases, the measured doses agreed with the results of the SP algorithm within +/-3%. Our results demonstrated the utility of the MOSFET detector for in vivo dosimetry even in the presence of clinical tissue inhomogeneities.

MRI quality assurance using the ACR phantom in a multi-unit imaging center

International Nuclear Information System (INIS)

Ihalainen, Toni M.; Kuusela, Linda J.; Savolainen, Sauli E.; Loennroth, Nadja T.; Peltonen, Juha I.; Uusi-Simola, Jouni K.; Timonen, Marjut H.; Sipilae, Outi E.

2011-01-01

Background. Magnetic resonance imaging (MRI) instrumentation is vulnerable to technical and image quality problems, and quality assurance is essential. In the studied regional imaging center the long-term quality assurance has been based on MagNET phantom measurements. American College of Radiology (ACR) has an accreditation program including a standardized image quality measurement protocol and phantom. The ACR protocol includes recommended acceptance criteria for clinical sequences and thus provides possibility to assess the clinical relevance of quality assurance. The purpose of this study was to test the ACR MRI phantom in quality assurance of a multi-unit imaging center. Material and methods. The imaging center operates 11 MRI systems of three major manufacturers with field strengths of 3.0 T, 1.5 T and 1.0 T. Images of the ACR phantom were acquired using a head coil following the ACR scanning instructions. Both ACR T1- and T2-weighted sequences as well as T1- and T2-weighted brain sequences in clinical use at each site were acquired. Measurements were performed twice. The images were analyzed and the results were compared with the ACR acceptance levels. Results. The acquisition procedure with the ACR phantom was faster than with the MagNET phantoms. On the first and second measurement rounds 91% and 73% of the systems passed the ACR test. Measured slice thickness accuracies were not within the acceptance limits in site T2 sequences. Differences in the high contrast spatial resolution between the ACR and the site sequences were observed. In 3.0 T systems the image intensity uniformity was slightly lower than the ACR acceptance limit. Conclusion. The ACR method was feasible in quality assurance of a multi-unit imaging center and the ACR protocol could replace the MagNET phantom tests. An automatic analysis of the images will further improve cost-effectiveness and objectiveness of the ACR protocol

SU-F-BRB-15: Dosimetric Study of Radiation Therapy for Head/Neck Patients with Metallic Dental Fixtures

Energy Technology Data Exchange (ETDEWEB)

Lu, L; Allan, E; Putten, M Van; Gupta, N; Blakaj, D [OH State University, Columbus, OH (United States)

2015-06-15

Purpose: To investigate the dose contributions of scattered electrons from dental amalgams during head and neck radiotherapy, and to evaluate the protective role of dosimetric dental stents during treatment to prevent oral mucositis. Methods: A phantom was produced to accurately simulate the oral cavity and head. The oral cavity consisted of a tissue equivalent upper and lower jaw and complete set of teeth. A set of 4 mm ethylene copolymer dosimetric stents was made for the upper and lower teeth. Five removable gold caps were fitted to apposing right molars, and the phantom was crafted to accomodate horizontal and vertical film for 2D dosimetry and NanoDot dosimeter for recording point doses. The head was simulated using a small cylindrical glass water bath. CT simulation was performed on the phantom with and without metal fittings and, in each case, with and without the dental stent. The CT image sets were imported into Eclipse treatment planning system for contouring and treatment planning, and a 9-field IMRT treatment plan was developed for each scenario. These plans were delivered using a Varian TrueBeam linear accelerator. Doses were recorded using GafChromic EBT2 films and NanoDot dosimeters. Results: The measurements revealed a 43% relative increase in dose measured adjacent to the metal fixtures in the horizontal plane without the use of the dental stent. This equates to a total dose of 100 Gy to the oral mucosa during a standard course of definitive radiotherapy. To our knowledge, this is the first dosimetric analysis of dental stents using an anatomically realistic phantom and modern beam arrangement. Conclusion: These results support the use of dosimetric dental stents in head and neck radiotherapy for patients with metallic dental fixtures as a way to effectively reduce dose to nearby mucosal surfaces and, hence, reduce the risk and severity of mucositis.

SU-F-BRB-15: Dosimetric Study of Radiation Therapy for Head/Neck Patients with Metallic Dental Fixtures

International Nuclear Information System (INIS)

Lu, L; Allan, E; Putten, M Van; Gupta, N; Blakaj, D

2015-01-01

Purpose: To investigate the dose contributions of scattered electrons from dental amalgams during head and neck radiotherapy, and to evaluate the protective role of dosimetric dental stents during treatment to prevent oral mucositis. Methods: A phantom was produced to accurately simulate the oral cavity and head. The oral cavity consisted of a tissue equivalent upper and lower jaw and complete set of teeth. A set of 4 mm ethylene copolymer dosimetric stents was made for the upper and lower teeth. Five removable gold caps were fitted to apposing right molars, and the phantom was crafted to accomodate horizontal and vertical film for 2D dosimetry and NanoDot dosimeter for recording point doses. The head was simulated using a small cylindrical glass water bath. CT simulation was performed on the phantom with and without metal fittings and, in each case, with and without the dental stent. The CT image sets were imported into Eclipse treatment planning system for contouring and treatment planning, and a 9-field IMRT treatment plan was developed for each scenario. These plans were delivered using a Varian TrueBeam linear accelerator. Doses were recorded using GafChromic EBT2 films and NanoDot dosimeters. Results: The measurements revealed a 43% relative increase in dose measured adjacent to the metal fixtures in the horizontal plane without the use of the dental stent. This equates to a total dose of 100 Gy to the oral mucosa during a standard course of definitive radiotherapy. To our knowledge, this is the first dosimetric analysis of dental stents using an anatomically realistic phantom and modern beam arrangement. Conclusion: These results support the use of dosimetric dental stents in head and neck radiotherapy for patients with metallic dental fixtures as a way to effectively reduce dose to nearby mucosal surfaces and, hence, reduce the risk and severity of mucositis

Measurement of radiotherapy CBCT dose in a phantom using different methods

International Nuclear Information System (INIS)

Hu, Naonori; McLean, Donald

2014-01-01

Cone beam computed tomography (CBCT) is used widely for the precise and accurate patient set up needed during radiation therapy, notably for hypo fractionated treatments, such as intensity modulated radiation therapy and stereotactic radiation therapy. Reported doses associated with CBCT indicate the potential to approach radiation tolerance levels for some critical organs. However while some manufacturers state the CBCT dose for each standard protocol, currently there are no standard or recognised protocols for CBCT dosimetry. This study has applied wide beam computed tomography dosimetry approaches as reported by the International Atomic Energy Agency and the American Association of Physicists in Medicine to investigate dosimetry for the Varian Trilogy linear accelerator with on-board imager v1.5. Three detection methods were used including (i) the use of both 100 mm and 300 mm pencil ionisation chambers, (ii) a 0.6 cm 3 ionisation chamber and (iii) gafchromic film. Measurements were performed using custom built 45 cm long PMMA phantoms as well as standard 15 cm long phantoms for both head and body simulation. The results showed good agreement between each other detector system (within 3 %). The measured CBCT dose for the above methods showed a large difference to the dose stated by Varian, with the measured dose being 40 % over the stated dose for the standard head protocol. This shows the importance of independently verifying the stated dose given by the vendor for standard procedures.

Construction of Chinese reference female phantom

International Nuclear Information System (INIS)

Sheng Yinxiangzi; Liu Lixing; Xia Xiaobin

2013-01-01

In this study, a Voxel-based Chinese Reference female Phantom (VCRP-woman) is developed from an individual female phantom which was based on high resolution cross-sectional color photographs. An in-house C ++ program was developed to adjust the phantom. Finally, a reference female phantom with have the same height, weighte and similar organs masses with the Chinese reference adult female data. The adjusted phantom is then imported to MCNPX to calculate the organs absorbed dose and effective dose conversion coefficients. Results are compared between VCRP-woman and the ICRP adult reference female phantom. (authors)

Phantom Sensations, Supernumerary Phantom Limbs and Apotemnophilia: Three Body Representation Disorders.

Science.gov (United States)

Tatu, Laurent; Bogousslavsky, Julien

2018-01-01

Body representation disorders continue to be mysterious and involve the anatomical substrate that underlies the mental representation of the body. These disorders sit on the boundaries of neurological and psychiatric diseases. We present the main characteristics of 3 examples of body representation disorders: phantom sensations, supernumerary phantom limb, and apotemnophilia. The dysfunction of anatomical circuits that regulate body representation can sometimes have paradoxical features. In the case of phantom sensations, the patient feels the painful subjective sensation of the existence of the lost part of the body after amputation, surgery or trauma. In case of apotemnophilia, now named body integrity identity disorder, the subject wishes for the disappearance of the existing and normal limb, which can occasionally lead to self-amputation. More rarely, a brain-damaged patient with 4 existing limbs can report the existence of a supernumerary phantom limb. © 2018 S. Karger AG, Basel.

21. Phantom pain.

NARCIS (Netherlands)

Wolff, A.P.; Vanduynhoven, E.; Kleef, M. van; Huygen, F.; Pope, J.E.; Mekhail, N.

2011-01-01

Phantom pain is pain caused by elimination or interruption of sensory nerve impulses by destroying or injuring the sensory nerve fibers after amputation or deafferentation. The reported incidence of phantom limb pain after trauma, injury or peripheral vascular diseases is 60% to 80%. Over half the

Dual-energy compared to single-energy CT in pediatric imaging: a phantom study for DECT clinical guidance

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiaowei; Servaes, Sabah; Darge, Kassa [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States); University of Pennsylvania, The Perelman School of Medicine, Philadelphia, PA (United States); McCullough, William P. [University of Virginia Health System, Department of Radiology and Medical Imaging, Charlottesville, VA (United States); Mecca, Patricia [The Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States)

2016-11-15

Dual-energy CT technology is available on scanners from several vendors and offers significant advantages over classic single-energy CT technology in multiple clinical applications. Many studies have detailed dual-energy CT applications in adults and several have evaluated the relative radiation dose performance of dual-energy CT in adult imaging. However, little has been published on dual-energy CT imaging in the pediatric population, and the relative dose performance of dual-energy CT imaging in the pediatric population is not well described. When evaluating dual-energy CT technology for implementation into a routine clinical pediatric imaging practice, the radiation dose implications must be considered, and when comparing relative CT dose performance, image quality must also be evaluated. Therefore the purpose of this study is to develop dual-energy CT scan protocols based on our optimized single-energy scan protocols and compare the dose. We scanned the head, chest and abdomen regions of pediatric-size anthropomorphic phantoms with contrast inserts, using our optimized single-energy clinical imaging protocols on a Siemens Flash {sup registered} CT scanner. We then scanned the phantoms in dual-energy mode using matching image-quality reference settings. The effective CT dose index volume (CTDI{sub vol}) of the scans was used as a surrogate for relative dose in comparing the single- and dual-energy scans. Additionally, we evaluated image quality using visual assessment and contrast-to-noise ratio. Dual-energy CT scans of the head and abdomen were dose-neutral for all three phantoms. Dual-energy CT scans of the chest showed a relative dose increase over the single-energy scan for 1- and 5-year-old child-based age-equivalent phantoms, ranging 11-20%. Quantitative analysis of image quality showed no statistically significant difference in image quality between the single-energy and dual-energy scans. There was no clinically significant difference in image quality by

Construction of Korean adult voxel phantoms for radiation dosimetry and their applications

Energy Technology Data Exchange (ETDEWEB)

Lee, Choon Sik

2002-08-15

stomach, thyroid, tests depending on the photon energy and the irradiation direction. These are caused by difference in trunk thickness between MIRD-type phantom and Korean voxel phantom, and differences of organ positions in the body. In the second example, dose to a brain tumor for a patient undergoing boronneutron- capture therapy(BNCT) was examined using head part of the KRMAN to demonstrate utility of voxel phantoms precisely describing an individual patient. In conclusion, although the MIRD-type phantoms are considered satisfactory for general purposes of external radiation protection dosimetry, partial modifications are needed for location and shape of some specific organs to improve accuracy of organ equivalent doses. Voxel phantoms can be used as tools providing references dosimetric values in this process. Since organ equivalent doses in internal exposure mode are sensitive to organ size and relative location, use of voxel phantoms is vital to enhance accuracy of patient dose assessment in therapy level of nuclear medicine. Refinement of KRMAN and KRWOMAN using additional image data is prerequisite of further applications. Development of methodology for accelerating voxel Monte Carlo calculations are also essential.

Saturation measurement accuracy in clinical near-infrared cerebral oximeters with a 3D-printed channel array phantom

Science.gov (United States)

Afshari, Ali; Ghassemi, Pejhman; Halprin, Molly; Lin, Jonathan; Weininger, Sandy; Gandjbakhche, Amir H.; Wang, Jianting; Pfefer, Joshua

2018-02-01

Clinical cerebral oximeters based on near-infrared spectroscopy (NIRS) are a commonly used, non-invasive tool for intraoperative monitoring of hemoglobin saturation. Research to verify performance of cerebral oximeters in human subject trials has shown differences between commercially available devices. Test methods based on tissue-simulating phantoms have been proposed to augment clinical findings. While prior studies have focused on liquid phantoms, this work is aimed at developing methods based on solid polymer phantoms that are stable. Specifically, we have designed and fabricated a neonatal/pediatric head mimicking layered phantoms based on a 3D-printed cerebral matrix incorporating an array of vessel-simulating linear channels. Superficial layers incorporating homogeneous molded polydimethylsiloxane (PDMS) slabs were fabricated to represent CSF, scalp and skull regions. The cerebral matrix was filled with bovine blood desaturated with sodium dithionite to achieve oxygenation levels across the 40-90% range. Measurements were performed with a commercially available cerebral oximeter using two probes with different illumination-collection geometries, as designed for neonatal and pediatric patients. Reference measurements of samples were performed with a CO-oximeter before injection and after extraction. Results from applied cerebral oximeters indicate a strong sensitivity to the thickness of the superficial layer of the phantom. Better correlation with the reference CO-oximeter results were obtained in the superficial layer thickness of 0.8-2.5 mm range. Channel array phantoms with modular superficial layers represent a promising approach for performance testing of NIRS-based cerebral oximeters.

Method of evaluation of diagnostics reference levels in computerized tomography; Metodo de avaliacao de niveis de referencia de radiodiagnostico em tomografia computadorizada

Energy Technology Data Exchange (ETDEWEB)

Vega, Walter Flores

1999-04-01

Computerized tomography is a complex technique with several selectable exposition parameters delivering high doses to the patient. In this work it was developed a simple methodology to evaluate diagnostic reference levels in computerized tomography, using the concept of Multiple Scan Average Dose (MSAD), recently adopted by the Health Ministry. For evaluation of the MSAD, a dose distribution was obtained through a measured dose profile on the axial axis of a water phantom with thermoluminescence dosemeters, TLD-100, for different exam technique. The MSAD was evaluated hrough two distinct methods. First, it was evaluated by the integration of the dose profile of a single slice and, second, obtained by the integration on central slice of the profile of several slices. The latter is in of accordance with the ionization chamber method, suggesting to be the most practical method of dose evaluation to be applied in the diagnostic reference level assessment routine for CT, using TLDs. (author)

SU-G-206-03: CTDI Per KV at Phantom Center and Periphery: Comparison Between Major CT Manufacturers

Energy Technology Data Exchange (ETDEWEB)

Al-Senan, R [Columbia University Medical Center, New York, NY (United States); Demirkaya, O [King Faisal Specialist Hospital & Research Centre, Riyadh (Saudi Arabia)

2016-06-15

Purpose: The purpose of this study was to: 1) compare scanners output by measuring normalized CTDIw (mGy/100mAs) in different CT makes and models and at different kV’s, and 2) quantify the relationship between kV and CTDI and compare this relationship between the different manufacturers. Methods: Study included forty scanners of major CT manufacturers and of various models. Exposure was measured at center and 12 o’clock holes of head and body CTDI phantoms, at all available kV’s, and with the largest or second largest available collimation in each scanner. Average measured CTDI’s from each CT manufacturer were also plotted against kV and the fitting equation: CTDIw (normalized) = a.kVb was calculated. The power (b) value may be considered as an indicator of spectral filtration, which affects the degree of beam hardening. Also, HVLs were measured at several scanners. Results: Results showed GE scanners, on average, had higher normalized CTDIw than those of Siemens and Philips, in both phantom sizes and at all kV’s. ANOVA statistic indicated the difference was statistically significant (p < 0.05). Comparison between Philips and Siemens, however, was not statistically significant. Curve fitting showed b values ranged from 2.4 to 2.9 (for Head periphery and center, respectively); and was about 2.8 for Body phantom periphery, and 3.2 at the center of Body phantom. Fitting equations (kV vs. CTDI) will be presented and discussed. GE’s CTDIw vs. HVL showed very strong correlation (r > 0.99). Conclusion: Partial characterization of scanners output was performed which may be helpful in dose estimation to internal organs. The relatively higher output from GE scanners may be attributed to lower filtration. Work is still in progress to obtain CTDI values from other scanners as well as to measure their HVLs.

Head injury in children

International Nuclear Information System (INIS)

Sugiura, Makoto; Mori, Nobuhiko; Yokosuka, Reiko; Yamamoto, Masaaki; Imanaga, Hirohisa

1981-01-01

Findings of computerized tomography (CT) in 183 cases of head injury in children were investigated with special reference to CT findings of mild head injury. As was expected, CT findings of mild head injury fell within the normal range, in almost all cases. However, abnormal findings were noticed in 4 out of 34 cases (12%) in acute stage and 7 out of 76 cases (9%) in chronic stage. They were 3 cases of localized low density area in acute stage and 6 cases of mild cerebral atrophy in chronic stage, etc. There were some cases of mild head injury in which CT findings were normal while EEG examination revealed abnormality. Also in some cases, x-ray study demonstrated linear skull fracture which CT failed to show. These conventional techniques could be still remained as useful adjunct aid in diagnosis of head injury. CT findings of cases of cerebral contusion in their acute stage were divided as follows; normal, low density, small ventricle and ventricular and/or cisternal hemorrhage, frequency of incidence being 38, 17, 22, 11% respectively. These findings were invariably converted to cerebral atrophy from 10 days to 2 months after the impacts. In the cases with intracranial hematoma revealed by CT, only 32% of them showed clinical signs of Araki's type IV in their acute stage and 63% of them showed no neurological defects, that is Araki's type I and II. A case of extreme diffuse cerebral atrophy which followed acute subdural hematoma caused by tear of bridging veins without cortical contusion was presented. (author)

A Study Of EMR And SAR Distribution In Human Head Phantom ...

African Journals Online (AJOL)

power of 0.32W for both simulations were well below the limit of 1.6 W/kg of ICNIRP standard and FCC/IEEE standard of 2W/kg. Keywords: Electromagnetic radiation (EMR), Specific Absorption Rate (SAR), Electromagnetic simulation software (FEKO emss), Radio frequency field, human head, mobile phone, mobile phone ...

Measurement of two-dimensional thermal neutron flux in a water phantom and evaluation of dose distribution characteristics

International Nuclear Information System (INIS)

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Horiguchi, Yoji

2001-03-01

To evaluate nitrogen dose, boron dose and gamma-ray dose occurred by neutron capture reaction of the hydrogen at the medical irradiation, two-dimensional distribution of the thermal neutron flux is very important because these doses are proportional to the thermal neutron distribution. This report describes the measurement of the two-dimensional thermal neutron distribution in a head water phantom by neutron beams of the JRR-4 and evaluation of the dose distribution characteristic. Thermal neutron flux in the phantom was measured by gold wire placed in the spokewise of every 30 degrees in order to avoid the interaction. Distribution of the thermal neutron flux was also calculated using two-dimensional Lagrange's interpolation program (radius, angle direction) developed this time. As a result of the analysis, it was confirmed to become distorted distribution which has annular peak at outside of the void, though improved dose profile of the deep direction was confirmed in the case which the radiation field in the phantom contains void. (author)

Radiation dose and cancer risk from pediatric CT examinations on 64-slice CT: A phantom study

International Nuclear Information System (INIS)

Feng Shiting; Law, Martin Wai-Ming; Huang Bingsheng; Ng, Sherry; Li Ziping; Meng Quanfei; Khong, Pek-Lan

2010-01-01

Objective: To measure the radiation dose from CT scans in an anthropomorphic phantom using a 64-slice MDCT, and to estimate the associated cancer risk. Materials and methods: Organ doses were measured with a 5-year-old phantom and thermoluminescent dosimeters. Four protocols; head CT, thorax CT, abdomen CT and pelvis CT were studied. Cancer risks, in the form of lifetime attributable risk (LAR) of cancer incidence, were estimated by linear extrapolation using the organ radiation doses and the LAR data. Results: The effective doses for head, thorax, abdomen and pelvis CT, were 0.7 mSv, 3.5 mSv, 3.0 mSv, 1.3 mSv respectively. The organs with the highest dose were; for head CT, salivary gland (22.33 mGy); for thorax CT, breast (7.89 mGy); for abdomen CT, colon (6.62 mGy); for pelvis CT, bladder (4.28 mGy). The corresponding LARs for boys and girls were 0.015-0.053% and 0.034-0.155% respectively. The organs with highest LARs were; for head CT, thyroid gland (0.003% for boys, 0.015% for girls); for thorax CT, lung for boys (0.014%) and breast for girls (0.069%); for abdomen CT, colon for boys (0.017%) and lung for girls (0.016%); for pelvis CT, bladder for both boys and girls (0.008%). Conclusion: The effective doses from these common pediatric CT examinations ranged from 0.7 mSv to 3.5 mSv and the associated lifetime cancer risks were found to be up to 0.16%, with some organs of higher radiosensitivity including breast, thyroid gland, colon and lungs.

3D Rapid Prototyping for Otolaryngology-Head and Neck Surgery: Applications in Image-Guidance, Surgical Simulation and Patient-Specific Modeling.

Science.gov (United States)

Chan, Harley H L; Siewerdsen, Jeffrey H; Vescan, Allan; Daly, Michael J; Prisman, Eitan; Irish, Jonathan C

2015-01-01

The aim of this study was to demonstrate the role of advanced fabrication technology across a broad spectrum of head and neck surgical procedures, including applications in endoscopic sinus surgery, skull base surgery, and maxillofacial reconstruction. The initial case studies demonstrated three applications of rapid prototyping technology are in head and neck surgery: i) a mono-material paranasal sinus phantom for endoscopy training ii) a multi-material skull base simulator and iii) 3D patient-specific mandible templates. Digital processing of these phantoms is based on real patient or cadaveric 3D images such as CT or MRI data. Three endoscopic sinus surgeons examined the realism of the endoscopist training phantom. One experienced endoscopic skull base surgeon conducted advanced sinus procedures on the high-fidelity multi-material skull base simulator. Ten patients participated in a prospective clinical study examining patient-specific modeling for mandibular reconstructive surgery. Qualitative feedback to assess the realism of the endoscopy training phantom and high-fidelity multi-material phantom was acquired. Conformance comparisons using assessments from the blinded reconstructive surgeons measured the geometric performance between intra-operative and pre-operative reconstruction mandible plates. Both the endoscopy training phantom and the high-fidelity multi-material phantom received positive feedback on the realistic structure of the phantom models. Results suggested further improvement on the soft tissue structure of the phantom models is necessary. In the patient-specific mandible template study, the pre-operative plates were judged by two blinded surgeons as providing optimal conformance in 7 out of 10 cases. No statistical differences were found in plate fabrication time and conformance, with pre-operative plating providing the advantage of reducing time spent in the operation room. The applicability of common model design and fabrication techniques

Computerized adaptive testing in computer assisted learning?

NARCIS (Netherlands)

Veldkamp, Bernard P.; Matteucci, Mariagiulia; Eggen, Theodorus Johannes Hendrikus Maria; De Wannemacker, Stefan; Clarebout, Geraldine; De Causmaecker, Patrick

2011-01-01

A major goal in computerized learning systems is to optimize learning, while in computerized adaptive tests (CAT) efficient measurement of the proficiency of students is the main focus. There seems to be a common interest to integrate computerized adaptive item selection in learning systems and

Development of a generic, computerized nuclear material accountability system: NucMAS

International Nuclear Information System (INIS)

Cornell, M.D.; O'Leary, J.M.

1987-01-01

The application NucMAS provides basic computerized accountability functions for the Savannah River Plant (SRP) Separations Department Material Balance Areas (MBA's). These functions include data entry, data management, calculations, and report generation. NucMAS can be used both for routine reporting to the SRP central Material Control and Accounting (MC and A) system and for rapid ad hoc queries in emergency situations. The system is designed to work with any process handling one or more of the 17 accountable nuclear materials specified by the Department of Energy (DOE). It relies on user-supplied configuration data to drive data prompts, report headings, data validations, and calculations

The influence of a clear layer on near-infrared spectrophotometry measurements using a liquid neonatal head phantom

International Nuclear Information System (INIS)

Wolf, M.

1999-01-01

It is difficult to test near-infrared spectrophotometry instruments in vivo. Therefore we constructed a liquid phantom which mimics the neonatal head. It consists of a spherical 3.5 mm thick layer of silicone rubber simulating skin and bone and a 0.5 mm thick clear layer of polypropylene imitating cerebrospinal fluid. It acts as container for a liquid solution with Intralipid, 60 μmol l -1 haemoglobin and yeast. The solution was oxygenated using oxygen and then deoxygenated by the yeast. From the instrumental (Critikon 2020) algorithm, we found that with increasing scattering (0.5%, 1%, 1.5% and 2% Intralipid concentration) the reading was increasingly offset from the expected value of 0 μmol l -1 by 55.7, 68.6, 76.5 and 80.4 μmol l -1 (oxyhaemoglobin) and 16.0, 24.4, 29.6 and 31.7 μmol l -1 (deoxyhaemoglobin). This reduced the range of the oxygen saturation reading from the expected 100% to 31.5, 21.1, 14.3 and 11.5%. Haemoglobin concentration changes were increasingly underestimated by a factor of two to four. For a second algorithm based on the diffusion approximation the offsets were smaller: oxyhaemoglobin 11.4, 17.8, 22.5 and 25.1 μmol l -1 and deoxyhaemoglobin 1.3, 3.4, 5.2 and 6.0 μmol l -1 . The range of the oxygen saturation reading was higher: 41.3, 29.2, 23.4 and 16.6%. Concentration changes were underestimated by a factor of six to ten. This study demonstrates the need to develop algorithms which take into consideration anatomical structures. (author)

Computer-assisted planning and dosimetry for radiation treatment of head and neck cancer in Cameroon

International Nuclear Information System (INIS)

Yomi, J.; Ngniah, A.; Kingue, S.; Muna, W.F.T.; Durosinmi-Etti, F.A.

1995-01-01

This evaluation was part of a multicenter, multinational study sponsored by the International Agency for Atomic Energy (Vienna) to investigate a simple, reliable computer-assisted planning and dosimetry system for radiation treatment of head and neck cancers in developing countries. Over a 13-month period (April 1992-April 1993), 120 patients with histologically-proven head or neck cancer were included in the evaluation. In each patient, planning and dosimetry were done both manually and using the computer-assisted system. The manual and computerized systems were compared on the basis of accuracy of determination of the outer contour, target volume, and critical organs; volume inequality resolution; structure heterogeneity correction; selection of the number, angle, and size of beams; treatment time calculation; availability of dosimetry predictions; and duration and cost of the procedure. Results demonstrated that the computer-assisted procedure was superior over the manual procedure, despite less than optimal software. The accuracy provided by the completely computerized procedure is indispensable for Level II radiation therapy, which is particularly useful in tumors of the sensitive, complex structures in the head and neck. (authors). 7 refs., 3 tabs

Dose profile variation with voltage in head CT scans using radiochromic films

Science.gov (United States)

Mourão, A. P.; Alonso, T. C.; DaSilva, T. A.

2014-02-01

The voltage source used in an X-ray tube is an important part of defining the generated beam spectrum energy profile. The X-ray spectrum energy defines the X-ray beam absorption as well as the characteristics of the energy deposition in an irradiated object. Although CT scanners allow one to choose between four different voltage values, most of them employ a voltage of 120 kV in their scanning protocols, regardless of the patient characteristics. Based on this fact, this work investigated the deposited dose in a polymethyl methacrylate (PMMA) cylindrical head phantom. The entire volume was irradiated twice. Two CT scanning protocols were used with two different voltage values: 100 and 120 kV. The phantom volume was irradiated, and radiochromic films were employed to record dose profiles. Measurements were conducted with a calibrated pencil ionization chamber, which was positioned in the center and in four peripheral bores of the head PMMA phantom, to calibrate the radiochromic films. The central slice was then irradiated. This procedure allowed us to find the conversion factors necessary to obtain dose values recorded in the films. The data obtained allowed us to observe the dose variation profile inside the phantom head as well as in the peripheral and central regions. The peripheral region showed higher dose values than those of the central region for scans using both voltage values: approximately 31% higher for scanning with 120 kV and 25% higher with 100 kV. Doses recorded with the highest voltage are significantly higher, approximately 50% higher in the peripheral region and 40% higher in the central region. A longitudinal variation could be observed, and the maximum dose was recorded at the peripheral region, at the midpoint of the longitudinal axis. The obtained results will most likely contribute to the dissemination of proper procedure as well as to optimize dosimetry and tests of quality control in CT because the choice of protocols with different voltage

Evolution of dosimetric phantoms

International Nuclear Information System (INIS)

Reddy, A.R.

2010-01-01

In this oration evolution of the dosimetric phantoms for radiation protection and for medical use is briefly reviewed. Some details of the development of Indian Reference Phantom for internal dose estimation are also presented

Surface doses under head and neck immobilisation devices

International Nuclear Information System (INIS)

Baveas, E.

2004-01-01

Full text: Methods using ion chambers, TLDs and film were developed to measure the skin-sparing properties of three head and neck immobilisation devices used in radiation therapy, viz. Sinmed multi-perforated and micro-perforated posicast thermoplastic masks (used with a supporting carbon fibre back support), and a Kablite vacuum-formed shell plastic mask (used with a Perspex back support). All measurements were performed with 6 MV beams from Elekta Precise linear accelerators. Two situations have been considered in this study. In the first situation, phantom surface doses under the flat unmoulded mask and back-support materials lying on the surface of a 'solid water' phantom were measured with parallel plate ion chambers and correlated with the physical properties of the materials. In the second situation a particular head and neck treatment technique was adopted and the treatment planned on an anthropomorphic tissue-equivalent phantom. The clinical setup consisted of a wedged pair to the right parotid, planned to deliver a reference dose of 63 Gy to the isocentre, plus an anterior supraclavicular field planned to deliver a reference dose of 50 Gy at a depth of 2 cm. The 3 immobilisation masks were each moulded to the anthropomorphic tissue-equivalent phantom. TLD chips were used to measure the phantom skin dose at a set of 18 locations under each of the 3 immobilisation masks and also without an immobilisation device. The results clearly demonstrate the extent to which the various immobilisation devices increase the surface dose. Results for the first situation are summarised. The averages of the doses recorded by the TLDs in three separate regions for the second situation are shown in Table 2. The combined results show that the areal density of the unmoulded mask materials correlates with the surface dose these materials produce before moulding, but this correlation is lost after moulding for the clinical situation considered. This change upon moulding is

The clinical utility of reduced-distortion readout-segmented echo-planar imaging in the head and neck region: initial experience

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Koyasu, Sho; Iima, Mami; Umeoka, Shigeaki; Morisawa, Nobuko; Togashi, Kaori [Kyoto University, Department of Diagnostic Imaging and Nuclear Medicine, Graduate School of Medicine, Sakyo-Ku, Kyoto (Japan); Porter, David A. [Siemens AG, MED MR PLM AW Neurology, Allee am Roethelheimpark 2, Erlangen (Germany); Ito, Juichi [Kyoto University, Department of Otolaryngology, Head and Neck Surgery, Graduate School of Medicine, Sakyo-Ku, Kyoto (Japan); Le Bihan, Denis [Kyoto University, Human Brain Research Center, Graduate School of Medicine, Sakyo-Ku, Kyoto (Japan); Neurospin, CEA-Saclay Center, Gif-sur-Yvette Cedex (France)

2014-12-15

To evaluate whether readout-segmented echo-planar imaging (RS-EPI) diffusion weighted image (DWI) can diminish image distortion in the head and neck area, compared with single-shot (SS)-EPI DWI. We conducted phantom and patient studies using 3 T magnetic resonance imaging (MRI) with a 16-channel coil. For the phantom study, we evaluated distortion and signal homogeneity in gel phantoms. For the patient study, 29 consecutive patients with clinically suspicious parotid lesions were prospectively enrolled. RS-EPI and SS-EPI DWI were evaluated by two independent readers for identification of organ/lesion and distortion, using semiquantitative scales and quantitative scores. Apparent diffusion coefficient (ADC) values and contrast-noise ratios of parotid tumours (if present; n = 15) were also compared. The phantom experiments showed that RS-EPI provided less distorted and more homogeneous ADC maps than SS-EPI. In the patient study, RS-EPI was found to provide significantly less distortion in almost all organs/lesions (p < 0.05), according to both semiquantitative scales and quantitative scores. There was no significant difference in ADC values and contrast-noise ratios between the two DWI techniques. The distortion in DWI was significantly reduced with RS-EPI in both phantom and patient studies. The RS-EPI technique provided more homogenous images than SS-EPI, and can potentially offer higher image quality in the head and neck area. (orig.)

Pathogenesis of traumatic intracerebral hematoma with a sequential study of computerized tomography

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Ohmori, H; Miyazaki, S; Munekata, K; Fukushima, H [Hitachi General Hospital, Hitachi, Ibaraki (Japan); Shohji, A

1981-04-01

A sequential study with computerized tomography (CT scan) of two cases of traumatic intracerebral hematoma is reported. Case 1 was a 69-year-old man who had a head injury. The initial CT scan, taken 1 hour after his injury, showed a left temporal salt-and-pepper appearance, which proved to be a cerebral contusion. The CT scan 4.5 hours after his injury showed a left temporal high density area instead. An operation was performed, and a massive intracerebral hematoma was observed. Case 2 was a 61-year-old man who was also admitted because of a head injury. The initial CT scan, taken 1 hour after his injury, revealed several bifrontal intracerebral hemorrhagic spots in the low-density areas, suggesting contusion. A secondary CT scan (23 hours) demonstrated that the traumatic intracerebral hematoma had developed into a posttraumatic cerebral contusion. The operation disclosed a hematoma surrounded by contusion. These cases prove that traumatic intracerebral hematoma is often caused by cerebral contusion.

Human Reliability Analysis For Computerized Procedures

International Nuclear Information System (INIS)

Boring, Ronald L.; Gertman, David I.; Le Blanc, Katya

2011-01-01

This paper provides a characterization of human reliability analysis (HRA) issues for computerized procedures in nuclear power plant control rooms. It is beyond the scope of this paper to propose a new HRA approach or to recommend specific methods or refinements to those methods. Rather, this paper provides a review of HRA as applied to traditional paper-based procedures, followed by a discussion of what specific factors should additionally be considered in HRAs for computerized procedures. Performance shaping factors and failure modes unique to computerized procedures are highlighted. Since there is no definitive guide to HRA for paper-based procedures, this paper also serves to clarify the existing guidance on paper-based procedures before delving into the unique aspects of computerized procedures.

Computerized Adaptive Personality Testing: A Review and Illustration With the MMPI-2 Computerized Adaptive Version.

Science.gov (United States)

Forbey, Johnathan D.; Ben-Porath, Yossef S.

2007-01-01

Computerized adaptive testing in personality assessment can improve efficiency by significantly reducing the number of items administered to answer an assessment question. Two approaches have been explored for adaptive testing in computerized personality assessment: item response theory and the countdown method. In this article, the authors…

Correction of head motion artifacts in SPECT with fully 3-D OS-EM reconstruction

International Nuclear Information System (INIS)

Fulton, R.R.

1998-01-01

Full text: A method which relies on continuous monitoring of head position has been developed to correct for head motion in SPECT studies of the brain. Head position and orientation are monitored during data acquisition by an inexpensive head tracking system (ADL-1, Shooting Star Technology, Rosedale, British Colombia). Motion correction involves changing the projection geometry to compensate for motion (using data from the head tracker), and reconstructing with a fully 3-D OS-EM algorithm. The reconstruction algorithm can accommodate any number of movements and any projection geometry. A single iteration of 3-D OS-EM using all available projections provides a satisfactory 3-D reconstruction, essentially free of motion artifacts. The method has been validated in studies of the 3-D Hoffman brain phantom. Multiple 36- degree acquisitions, each with the phantom in a different position, were performed on a Trionix triple head camera. Movements were simulated by combining projections from the different acquisitions. Accuracy was assessed by comparison with a motion-free reconstruction, visually and by calculating mean squared error (MSE). Motion correction reduced distortion perceptibly and, depending on the motions applied, improved MSE by up to an order of magnitude. Three-dimensional reconstruction of the 128 x 128 x 128 data set took 2- minutes on a SUN Ultra 1 workstation. This motion correction technique can be retro-fitted to existing SPECT systems and could be incorporated in future SPECT camera designs. It appears to be applicable in PET as well as SPECT, to be able to correct for any head movements, and to have the potential to improve the accuracy of tomographic brain studies under clinical imaging conditions

The impact of anthropometric patient-phantom matching on organ dose: A hybrid phantom study for fluoroscopy guided interventions

International Nuclear Information System (INIS)

Johnson, Perry B.; Geyer, Amy; Borrego, David; Ficarrotta, Kayla; Johnson, Kevin; Bolch, Wesley E.

2011-01-01

Purpose: To investigate the benefits and limitations of patient-phantom matching for determining organ dose during fluoroscopy guided interventions. Methods: In this study, 27 CT datasets representing patients of different sizes and genders were contoured and converted into patient-specific computational models. Each model was matched, based on height and weight, to computational phantoms selected from the UF hybrid patient-dependent series. In order to investigate the influence of phantom type on patient organ dose, Monte Carlo methods were used to simulate two cardiac projections (PA/left lateral) and two abdominal projections (RAO/LPO). Organ dose conversion coefficients were then calculated for each patient-specific and patient-dependent phantom and also for a reference stylized and reference hybrid phantom. The coefficients were subsequently analyzed for any correlation between patient-specificity and the accuracy of the dose estimate. Accuracy was quantified by calculating an absolute percent difference using the patient-specific dose conversion coefficients as the reference. Results: Patient-phantom matching was shown most beneficial for estimating the dose to heavy patients. In these cases, the improvement over using a reference stylized phantom ranged from approximately 50% to 120% for abdominal projections and for a reference hybrid phantom from 20% to 60% for all projections. For lighter individuals, patient-phantom matching was clearly superior to using a reference stylized phantom, but not significantly better than using a reference hybrid phantom for certain fields and projections. Conclusions: The results indicate two sources of error when patients are matched with phantoms: Anatomical error, which is inherent due to differences in organ size and location, and error attributed to differences in the total soft tissue attenuation. For small patients, differences in soft tissue attenuation are minimal and are exceeded by inherent anatomical differences

3D Printing Openable Imaging Phantom Design

International Nuclear Information System (INIS)

Kim, Myoung Keun; Won, Jun Hyeok; Lee, Seung Wook

2017-01-01

The purpose of this study is to design an openable phantom that can replace the internal measurement bar used for contrast comparison in order to increase the efficiency of manufacturing imaging phantom used in the medical industry and to improve convenience using 3D printer. Phantom concept design, 3D printing, and Image reconstruction were defined as the scope of the thesis. Also, we study metal artifact reduction with openable phantom. We have designed a Openable phantom using 3D printing, and have investigated metal artifact reduction after inserting a metallic material inside the phantom. The openable phantom can be adjusted at any time to suit the user's experiment and can be easily replaced and useful.

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

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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.

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

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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.

The subresolution DaTSCAN phantom: a cost-effective, flexible alternative to traditional phantom technology.

Science.gov (United States)

Taylor, Jonathan C; Vennart, Nicholas; Negus, Ian; Holmes, Robin; Bandmann, Oliver; Lo, Christine; Fenner, John

2018-03-01

The Alderson striatal phantom is frequently used to assess I-FP-CIT (Ioflupane) image quality and to test semi-quantification software. However, its design is associated with a number of limitations, in particular: unrealistic image appearances and inflexibility. A new physical phantom approach is proposed on the basis of subresolution phantom technology. The design incorporates thin slabs of attenuating material generated through additive manufacturing, and paper sheets with radioactive ink patterns printed on their surface, created with a conventional inkjet printer. The paper sheets and attenuating slabs are interleaved before scanning. Use of thin layers ensures that they cannot be individually resolved on reconstructed images. An investigation was carried out to demonstrate the performance of such a phantom in producing simplified I-FP-CIT uptake patterns. Single photon emission computed tomography imaging was carried out on an assembled phantom designed to mimic a healthy patient. Striatal binding ratio results and linear striatal dimensions were calculated from the reconstructed data and compared with that of 22 clinical patients without evidence of Parkinsonian syndrome, determined from clinical follow-up. Striatal binding ratio results for the fully assembled phantom were: 3.1, 3.3, 2.9 and 2.6 for the right caudate, left caudate, right putamen and right caudate, respectively. All were within two SDs of results derived from a cohort of clinical patients. Medial-lateral and anterior-posterior dimensions of the simulated striata were also within the range of values seen in clinical data. This work provides the foundation for the generation of a range of more clinically realistic, physical phantoms.

Thermal neutron dose calculations in a brain phantom from 7Li(p,n) reaction based BNCT setup

International Nuclear Information System (INIS)

Elshahat, B.A.; Naqvi, A.A.; Maalej, N.; Abdallah, Khalid

2006-01-01

Monte Carlo simulations were carried out to calculate neutron dose in a brain phantom from a 7 Li(p,n) reaction based setup utilizing a high density polyethylene moderator with graphite reflector. The dimensions of the moderator and the reflector were optimized through optimization of epithermal /(fast +thermal) neutron intensity ratio as a function of geometric parameters of the setup. Results of our calculation showed the capability of our setup to treat the tumor within 4 cm of the head surface. The calculated Peak Therapeutic Ratio for the setup was found to be 2.15. With further improvement in the moderator design and brain phantom irradiation arrangement, the setup capabilities can be improved to reach further deep-seated tumor. (author)

The Usefulness of Readout-Segmented Echo-Planar Imaging (RESOLVE) for Bio-phantom Imaging Using 3-Tesla Clinical MRI.

Science.gov (United States)

Yoshimura, Yuuki; Kuroda, Masahiro; Sugiantoc, Irfan; Bamgbosec, Babatunde O; Miyahara, Kanae; Ohmura, Yuichi; Kurozumi, Akira; Matsushita, Toshi; Ohno, Seiichiro; Kanazawa, Susumu; Asaumi, Junichi

2018-02-01

Readout-segmented echo-planar imaging (RESOLVE) is a multi-shot echo-planar imaging (EPI) modality with k-space segmented in the readout direction. We investigated whether RESOLVE decreases the distortion and artifact in the phase direction and increases the signal-to-noise ratio (SNR) in phantoms image taken with 3-tesla (3T) MRI versus conventional EPI. We used a physiological saline phantom and subtraction mapping and observed that RESOLVE's SNR was higher than EPI's. Using RESOLVE, the combination of a special-purpose coil and a large-loop coil had a higher SNR compared to using only a head/neck coil. RESOLVE's image distortioas less than EPI's. We used a 120 mM polyethylene glycol phantom to examine the phase direction artifact.vThe range where the artifact appeared in the apparent diffusion coefficient (ADC) image was shorter with RESOLVE compared to EPI. We used RESOLVE to take images of a Jurkat cell bio-phantom: the cell-region ADC was 856×10-6mm2/sec and the surrounding physiological saline-region ADC was 2,951×10-6mm2/sec. The combination of RESOLVE and the 3T clinical MRI device reduced image distortion and improved SNR and the identification of accurate ADC values due to the phase direction artifact reduction. This combination is useful for obtaining accurate ADC values of bio-phantoms.

Dual-energy compared to single-energy CT in pediatric imaging: a phantom study for DECT clinical guidance

International Nuclear Information System (INIS)

Zhu, Xiaowei; Servaes, Sabah; Darge, Kassa; McCullough, William P.; Mecca, Patricia

2016-01-01

Dual-energy CT technology is available on scanners from several vendors and offers significant advantages over classic single-energy CT technology in multiple clinical applications. Many studies have detailed dual-energy CT applications in adults and several have evaluated the relative radiation dose performance of dual-energy CT in adult imaging. However, little has been published on dual-energy CT imaging in the pediatric population, and the relative dose performance of dual-energy CT imaging in the pediatric population is not well described. When evaluating dual-energy CT technology for implementation into a routine clinical pediatric imaging practice, the radiation dose implications must be considered, and when comparing relative CT dose performance, image quality must also be evaluated. Therefore the purpose of this study is to develop dual-energy CT scan protocols based on our optimized single-energy scan protocols and compare the dose. We scanned the head, chest and abdomen regions of pediatric-size anthropomorphic phantoms with contrast inserts, using our optimized single-energy clinical imaging protocols on a Siemens Flash "r"e"g"i"s"t"e"r"e"d CT scanner. We then scanned the phantoms in dual-energy mode using matching image-quality reference settings. The effective CT dose index volume (CTDI_v_o_l) of the scans was used as a surrogate for relative dose in comparing the single- and dual-energy scans. Additionally, we evaluated image quality using visual assessment and contrast-to-noise ratio. Dual-energy CT scans of the head and abdomen were dose-neutral for all three phantoms. Dual-energy CT scans of the chest showed a relative dose increase over the single-energy scan for 1- and 5-year-old child-based age-equivalent phantoms, ranging 11-20%. Quantitative analysis of image quality showed no statistically significant difference in image quality between the single-energy and dual-energy scans. There was no clinically significant difference in image quality

Phantom with pulsatile arteries to investigate the influence of blood vessel depth on pulse oximeter signal strength.

Science.gov (United States)

Stuban, Norbert; Niwayama, Masatsugu; Santha, Hunor

2012-01-01

This paper describes a three-layer head phantom with artificial pulsating arteries at five different depths (1.2 mm, 3.7 mm, 6.8 mm, 9.6 mm and 11.8 mm). The structure enables formation of spatially and temporally varying tissue properties similar to those of living tissues. In our experiment, pressure pulses were generated in the arteries by an electronically controlled pump. The physical and optical parameters of the layers and the liquid in the artificial arteries were similar to those of real tissues and blood. The amplitude of the pulsating component of the light returning from the phantom tissues was measured at each artery depth mentioned above. The build-up of the in-house-developed pulse oximeter used for performing the measurements and the physical layout of the measuring head are described. The radiant flux generated by the LED on the measuring head was measured to be 1.8 mW at 910 nm. The backscattered radiant flux was measured, and found to be 0.46 nW (0.26 ppm), 0.55 nW (0.31 ppm), and 0.18 nW (0.10 ppm) for the 1.2 mm, 3.7 mm and 6.8 mm arteries, respectively. In the case of the 9.6 mm and 11.8 mm arteries, useful measurement data were not obtained owing to weak signals. We simulated the phantom with the arteries at the above-mentioned five depths and at two additional ones (2.5 mm and 5.3 mm in depth) using the Monte Carlo method. The measurement results were verified by the simulation results. We concluded that in case of 11 mm source-detector separation the arteries at a depth of about 2.5 mm generate the strongest pulse oximeter signal level in a tissue system comprising three layers of thicknesses: 1.5 mm (skin), 5.0 mm (skull), and >50 mm (brain).

Phantom with Pulsatile Arteries to Investigate the Influence of Blood Vessel Depth on Pulse Oximeter Signal Strength

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Hunor Santha

2012-01-01

Full Text Available This paper describes a three-layer head phantom with artificial pulsating arteries at five different depths (1.2 mm, 3.7 mm, 6.8 mm, 9.6 mm and 11.8 mm. The structure enables formation of spatially and temporally varying tissue properties similar to those of living tissues. In our experiment, pressure pulses were generated in the arteries by an electronically controlled pump. The physical and optical parameters of the layers and the liquid in the artificial arteries were similar to those of real tissues and blood. The amplitude of the pulsating component of the light returning from the phantom tissues was measured at each artery depth mentioned above. The build-up of the in-house-developed pulse oximeter used for performing the measurements and the physical layout of the measuring head are described. The radiant flux generated by the LED on the measuring head was measured to be 1.8 mW at 910 nm. The backscattered radiant flux was measured, and found to be 0.46 nW (0.26 ppm, 0.55 nW (0.31 ppm, and 0.18 nW (0.10 ppm for the 1.2 mm, 3.7 mm and 6.8 mm arteries, respectively. In the case of the 9.6 mm and 11.8 mm arteries, useful measurement data were not obtained owing to weak signals. We simulated the phantom with the arteries at the above-mentioned five depths and at two additional ones (2.5 mm and 5.3 mm in depth using the Monte Carlo method. The measurement results were verified by the simulation results. We concluded that in case of 11 mm source-detector separation the arteries at a depth of about 2.5 mm generate the strongest pulse oximeter signal level in a tissue system comprising three layers of thicknesses: 1.5 mm (skin, 5.0 mm (skull, and > 50 mm (brain.

Importance of computerized tomography for surgical treatment of intracranial hematomas

International Nuclear Information System (INIS)

Diemath, H.E.

1982-01-01

The improved treatment by using computerized tomography (CT) located operating theater and intensive care unit is reported in comparison of 3,382 patients with severe head injuries. By preoperative use of CT the frequency of diagnosed hermatomas was about the same (29.5% before CT; 27.0% with CT) but the preoperative diagnosed multiple hematomas were much more frequent (14.0% resp. 27.0%). The most important advantage however is the saving of time by CT in this localisation by which the chance of survival has increased from 54% to 69%. Without any doubt everywhere in neurotraumatology the CT should be situated as near as possible to the intensive care unit and to the operating theater and should be available 24 hours a day. (Author) [de

Health physics aspects of the EMI computerized tomography brain scanner

International Nuclear Information System (INIS)

Villafana, T.; Scouras, J.; Kirkland, L.; McElroy, N.; Paras, P.

1978-01-01

The EMI computerized tomographic cranial scanner is one of the first radiological systems incorporating an on-line computer. The result is an increase in the ability to visualize such tissues as grey matter and white matter as well as blood pools and tumor volumes. This advance has already begun to revolutionize radiological practice. Because of the totally different configuration of this unit, concern has been expressed over the dosages received by the patient, consequently the health physics aspects of this unit have been studied. Specifically, doses received by the surface of head and interior brain points as well as by the lens of the eye and gonads are reported here. X-ray output, beam half-value layers and barrier shielding requirements are also reported and discussed. (author)

FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations

Energy Technology Data Exchange (ETDEWEB)

Kramer, R; Cassola, V F; Khoury, H J [Department of Nuclear Energy, Federal University of Pernambuco, Avenida Prof. Luiz Freire, 1000, CEP 50740-540, Recife (Brazil); Vieira, J W [Federal Institute of Education, Science and Technology of Pernambuco, Recife (Brazil); De Melo Lima, V J [Department of Anatomy, Federal University of Pernambuco, Recife (Brazil); Robson Brown, K [Imaging Laboratory, Department of Archaeology and Anthropology, University of Bristol, Bristol (United Kingdom)], E-mail: rkramer@uol.com.br

2010-01-07

Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon

FASH and MASH: female and male adult human phantoms based on polygon mesh surfaces: II. Dosimetric calculations

Science.gov (United States)

Kramer, R.; Cassola, V. F.; Khoury, H. J.; Vieira, J. W.; de Melo Lima, V. J.; Robson Brown, K.

2010-01-01

Female and male adult human phantoms, called FASH (Female Adult meSH) and MASH (Male Adult meSH), have been developed in the first part of this study using 3D animation software and anatomical atlases to replace the image-based FAX06 and the MAX06 voxel phantoms. 3D modelling methods allow for phantom development independent from medical images of patients, volunteers or cadavers. The second part of this study investigates the dosimetric implications for organ and tissue equivalent doses due to the anatomical differences between the new and the old phantoms. These differences are mainly caused by the supine position of human bodies during scanning in order to acquire digital images for voxel phantom development. Compared to an upright standing person, in image-based voxel phantoms organs are often coronally shifted towards the head and sometimes the sagittal diameter of the trunk is reduced by a gravitational change of the fat distribution. In addition, volumes of adipose and muscle tissue shielding internal organs are sometimes too small, because adaptation of organ volumes to ICRP-based organ masses often occurs at the expense of general soft tissues, such as adipose, muscle or unspecified soft tissue. These effects have dosimetric consequences, especially for partial body exposure, such as in x-ray diagnosis, but also for whole body external exposure and for internal exposure. Using the EGSnrc Monte Carlo code, internal and external exposure to photons and electrons has been simulated with both pairs of phantoms. The results show differences between organ and tissue equivalent doses for the upright standing FASH/MASH and the image-based supine FAX06/MAX06 phantoms of up to 80% for external exposure and up to 100% for internal exposure. Similar differences were found for external exposure between FASH/MASH and REGINA/REX, the reference voxel phantoms of the International Commission on Radiological Protection. Comparison of effective doses for external photon

Formal Verification of Computerized Procedure with Colored Petri Nets

International Nuclear Information System (INIS)

Kim, Yun Goo; Shin, Yeong Cheol

2008-01-01

Computerized Procedure System (CPS) supports nuclear power plant operators in performing operating procedures which are instructions to guide in monitoring, decision making and controlling nuclear power plants. Computerized Procedure (CP) should be loaded to CPS. Due to its execution characteristic, computerized procedure acts like a software in CPS. For example, procedure flows are determined by operator evaluation and computerized procedure logic which are pre-defined. So the verification of Computerized Procedure logic and execution flow is needed before computerized procedures are installed in the system. Formal verification methods are proposed and the modeling of operating procedures with Coloured Petri Nets(CP-nets) is presented

Technologies in computerized lexicography | Kruyt | Lexikos

African Journals Online (AJOL)

Although the topic of this paper is technology, focus is on functional rather than technical aspects of computerized lexicography. Keywords: computerized lexicography, electronic dictionary, electronic text corpus, lexicographer's workbench, integrated language database, automatic linguistic analysis, information retrieval, ...

A computer-simulated liver phantom (virtual liver phantom) for multidetector computed tomography evaluation

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Funama, Yoshinori [Kumamoto University, Department of Radiological Sciences, School of Health Sciences, Kumamoto (Japan); Awai, Kazuo; Nakayama, Yoshiharu; Liu, Da; Yamashita, Yasuyuki [Kumamoto University, Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto (Japan); Miyazaki, Osamu; Goto, Taiga [Hitachi Medical Corporation, Tokyo (Japan); Hori, Shinichi [Gate Tower Institute of Image Guided Therapy, Osaka (Japan)

2006-04-15

The purpose of study was to develop a computer-simulated liver phantom for hepatic CT studies. A computer-simulated liver phantom was mathematically constructed on a computer workstation. The computer-simulated phantom was calibrated using real CT images acquired by an actual four-detector CT. We added an inhomogeneous texture to the simulated liver by referring to CT images of chronically damaged human livers. The mean CT number of the simulated liver was 60 HU and we added numerous 5-to 10-mm structures with 60{+-}10 HU/mm. To mimic liver tumors we added nodules measuring 8, 10, and 12 mm in diameter with CT numbers of 60{+-}10, 60{+-}15, and 60{+-}20 HU. Five radiologists visually evaluated similarity of the texture of the computer-simulated liver phantom and a real human liver to confirm the appropriateness of the virtual liver images using a five-point scale. The total score was 44 in two radiologists, and 42, 41, and 39 in one radiologist each. They evaluated that the textures of virtual liver were comparable to those of human liver. Our computer-simulated liver phantom is a promising tool for the evaluation of the image quality and diagnostic performance of hepatic CT imaging. (orig.)

[Computerized medical record: deontology and legislation].

Science.gov (United States)

Allaert, F A; Dusserre, L

1996-02-01

Computerization of medical records is making headway for patients' follow-up, scientific research, and health expenses control, but it must not alter the guarantees provided to the patients by the medical code of ethics and the law of January 6, 1978. This law, modified on July 1, 1994, requires to register all computerized records of personal data and establishes rights to protect privacy against computer misdemeanor. All medical practitioners using computerized medical records must be aware that the infringement of this law may provoke suing in professional, civil or criminal court.

39 CFR 501.15 - Computerized Meter Resetting System.

Science.gov (United States)

2010-07-01

... 39 Postal Service 1 2010-07-01 2010-07-01 false Computerized Meter Resetting System. 501.15... AND DISTRIBUTE POSTAGE EVIDENCING SYSTEMS § 501.15 Computerized Meter Resetting System. (a) Description. The Computerized Meter Resetting System (CMRS) permits customers to reset their postage meters at...

An investigation into the effect of protective devices on the dose to radiosensitive organs in the head and neck

International Nuclear Information System (INIS)

Marshall, N.W.; Faulkner, K.; Clarke, P.

1992-01-01

A series of experiments were performed to determine the dose reduction afforded to radiosensitive organs in the head and neck by various protective devices. These included spectacles with plastic, standard glass, photochromic and lead-glass lenses, a thyroid collar and a lead-acrylic face mask. The measurements were performed using an anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters, in conditions realistic of clinical practice. Irradiations were performed using scattered radiation produced by a pelvic phantom, for X-ray beams generated at 80 kVp and 110 KVp. Also presented is the ratio of organ dose to dose to the bridge of the nose for thyroid, oesophagus, brain and sinuses, as measured for the case of no head or neck protection. (author)

WE-D-BRA-05: Pseudo In Vivo Patient Dosimetry Using a 3D-Printed Patient-Specific Phantom

International Nuclear Information System (INIS)

Ger, R; Craft, DF; Burgett, EA; Price, RR; Kry, SF; Howell, RM

2015-01-01

Purpose: To test the feasibility of using 3D-printed patient-specific phantoms for intensity-modulated radiation therapy (IMRT) quality assurance (QA). Methods: We created a patient-specific whole-head phantom using a 3D printer. The printer data file was created from high-resolution DICOM computed tomography (CT) images of 3-year old child treated at our institution for medulloblastoma. A custom-modified extruder system was used to create tissue-equivalent materials. For the printing process, the Hounsfield Units from the CT images were converted to proportional volumetric densities. A 5-field IMRT plan was created from the patient CT and delivered to the 3D- phantom. Dose was measured by an ion chamber placed through the eye. The ion chamber was placed at the posterior edge of the planning target volume in a high dose gradient region. CT scans of the patient and 3D-phantom were fused by using commercial treatment planning software (TPS). The patient’s plan was calculated on the phantom CT images. The ion chamber’s active volume was delineated in the TPS; dose per field and total dose were obtained. Measured and calculated doses were compared. Results: The 3D-phantom dimensions and tissue densities were in good agreement with the patient. However, because of a printing error, there was a large discrepancy in the density in the frontal cortex. The calculated and measured treatment plan doses were 1.74 Gy and 1.72 Gy, respectively. For individual fields, the absolute dose difference between measured and calculated values was on average 3.50%. Conclusion: This study demonstrated the feasibility of using 3D-printed patient-specific phantoms for IMRT QA. Such phantoms would be particularly advantageous for complex IMRT treatment plans featuring high dose gradients and/or for anatomical sites with high variation in tissue densities. Our preliminary findings are promising. We anticipate that, once the printing process is further refined, the agreement between

WE-D-BRA-05: Pseudo In Vivo Patient Dosimetry Using a 3D-Printed Patient-Specific Phantom

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Ger, R; Craft, DF [The University of Texas Graduate School of Biomedical Sciences (United States); Burgett, EA [Idaho State University, Pocatello, idaho (United States); Price, RR [RANDJ Consulting, Frederick, MD (United States); Kry, SF; Howell, RM [The University of Texas Graduate School of Biomedical Sciences (United States); The University of Texas MD Anderson Cancer Ctr., Houston, TX (United States)

2015-06-15

Purpose: To test the feasibility of using 3D-printed patient-specific phantoms for intensity-modulated radiation therapy (IMRT) quality assurance (QA). Methods: We created a patient-specific whole-head phantom using a 3D printer. The printer data file was created from high-resolution DICOM computed tomography (CT) images of 3-year old child treated at our institution for medulloblastoma. A custom-modified extruder system was used to create tissue-equivalent materials. For the printing process, the Hounsfield Units from the CT images were converted to proportional volumetric densities. A 5-field IMRT plan was created from the patient CT and delivered to the 3D- phantom. Dose was measured by an ion chamber placed through the eye. The ion chamber was placed at the posterior edge of the planning target volume in a high dose gradient region. CT scans of the patient and 3D-phantom were fused by using commercial treatment planning software (TPS). The patient’s plan was calculated on the phantom CT images. The ion chamber’s active volume was delineated in the TPS; dose per field and total dose were obtained. Measured and calculated doses were compared. Results: The 3D-phantom dimensions and tissue densities were in good agreement with the patient. However, because of a printing error, there was a large discrepancy in the density in the frontal cortex. The calculated and measured treatment plan doses were 1.74 Gy and 1.72 Gy, respectively. For individual fields, the absolute dose difference between measured and calculated values was on average 3.50%. Conclusion: This study demonstrated the feasibility of using 3D-printed patient-specific phantoms for IMRT QA. Such phantoms would be particularly advantageous for complex IMRT treatment plans featuring high dose gradients and/or for anatomical sites with high variation in tissue densities. Our preliminary findings are promising. We anticipate that, once the printing process is further refined, the agreement between

Scattered radiation from dental metallic crowns in head and neck radiotherapy.

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Shimozato, T; Igarashi, Y; Itoh, Y; Yamamoto, N; Okudaira, K; Tabushi, K; Obata, Y; Komori, M; Naganawa, S; Ueda, M

2011-09-07

We aimed to estimate the scattered radiation from dental metallic crowns during head and neck radiotherapy by irradiating a jaw phantom with external photon beams. The phantom was composed of a dental metallic plate and hydroxyapatite embedded in polymethyl methacrylate. We used radiochromic film measurement and Monte Carlo simulation to calculate the radiation dose and dose distribution inside the phantom. To estimate dose variations in scattered radiation under different clinical situations, we altered the incident energy, field size, plate thickness, plate depth and plate material. The simulation results indicated that the dose at the incident side of the metallic dental plate was approximately 140% of that without the plate. The differences between dose distributions calculated with the radiation treatment-planning system (TPS) algorithms and the data simulation, except around the dental metallic plate, were 3% for a 4 MV photon beam. Therefore, we should carefully consider the dose distribution around dental metallic crowns determined by a TPS.

3D Rapid Prototyping for Otolaryngology-Head and Neck Surgery: Applications in Image-Guidance, Surgical Simulation and Patient-Specific Modeling.

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Harley H L Chan

Full Text Available The aim of this study was to demonstrate the role of advanced fabrication technology across a broad spectrum of head and neck surgical procedures, including applications in endoscopic sinus surgery, skull base surgery, and maxillofacial reconstruction. The initial case studies demonstrated three applications of rapid prototyping technology are in head and neck surgery: i a mono-material paranasal sinus phantom for endoscopy training ii a multi-material skull base simulator and iii 3D patient-specific mandible templates. Digital processing of these phantoms is based on real patient or cadaveric 3D images such as CT or MRI data. Three endoscopic sinus surgeons examined the realism of the endoscopist training phantom. One experienced endoscopic skull base surgeon conducted advanced sinus procedures on the high-fidelity multi-material skull base simulator. Ten patients participated in a prospective clinical study examining patient-specific modeling for mandibular reconstructive surgery. Qualitative feedback to assess the realism of the endoscopy training phantom and high-fidelity multi-material phantom was acquired. Conformance comparisons using assessments from the blinded reconstructive surgeons measured the geometric performance between intra-operative and pre-operative reconstruction mandible plates. Both the endoscopy training phantom and the high-fidelity multi-material phantom received positive feedback on the realistic structure of the phantom models. Results suggested further improvement on the soft tissue structure of the phantom models is necessary. In the patient-specific mandible template study, the pre-operative plates were judged by two blinded surgeons as providing optimal conformance in 7 out of 10 cases. No statistical differences were found in plate fabrication time and conformance, with pre-operative plating providing the advantage of reducing time spent in the operation room. The applicability of common model design and

3D Rapid Prototyping for Otolaryngology—Head and Neck Surgery: Applications in Image-Guidance, Surgical Simulation and Patient-Specific Modeling

Science.gov (United States)

Chan, Harley H. L.; Siewerdsen, Jeffrey H.; Vescan, Allan; Daly, Michael J.; Prisman, Eitan; Irish, Jonathan C.

2015-01-01

The aim of this study was to demonstrate the role of advanced fabrication technology across a broad spectrum of head and neck surgical procedures, including applications in endoscopic sinus surgery, skull base surgery, and maxillofacial reconstruction. The initial case studies demonstrated three applications of rapid prototyping technology are in head and neck surgery: i) a mono-material paranasal sinus phantom for endoscopy training ii) a multi-material skull base simulator and iii) 3D patient-specific mandible templates. Digital processing of these phantoms is based on real patient or cadaveric 3D images such as CT or MRI data. Three endoscopic sinus surgeons examined the realism of the endoscopist training phantom. One experienced endoscopic skull base surgeon conducted advanced sinus procedures on the high-fidelity multi-material skull base simulator. Ten patients participated in a prospective clinical study examining patient-specific modeling for mandibular reconstructive surgery. Qualitative feedback to assess the realism of the endoscopy training phantom and high-fidelity multi-material phantom was acquired. Conformance comparisons using assessments from the blinded reconstructive surgeons measured the geometric performance between intra-operative and pre-operative reconstruction mandible plates. Both the endoscopy training phantom and the high-fidelity multi-material phantom received positive feedback on the realistic structure of the phantom models. Results suggested further improvement on the soft tissue structure of the phantom models is necessary. In the patient-specific mandible template study, the pre-operative plates were judged by two blinded surgeons as providing optimal conformance in 7 out of 10 cases. No statistical differences were found in plate fabrication time and conformance, with pre-operative plating providing the advantage of reducing time spent in the operation room. The applicability of common model design and fabrication techniques

Design, fabrication and evaluation of a new calibration phantom for in vivo measurement of bone-seeking radionuclides (invited paper)

International Nuclear Information System (INIS)

Spitz, H.B.; Lodwick, J.

2000-01-01

A new anthropometric phantom has been developed for use in calibrating in vivo measurements of bone-seeking radionuclides. The phantom has the external shape and appearance of the human adult knee and contains a realistic femur, patella, tibia, and fibula. Unique formulations of polyurethanes, CaCo 3 , and other trace materials are used in construction of the phantom to produce substitutes for human tissue having the same density, attenuation coefficient, and effective Z as that of human muscle and trabecular bone. The formulation for trabecular bone includes provision for a precisely known quantity of radioactive material that is either uniformly distributed throughout the bone matrix or deposited on the exterior surface. The knee phantom is assembled in three interlocking sections that simplify inserting the skeletal structures and prevent streaming. One or more detectors can easily be positioned on the top or sides of the phantom. Intercomparison measurements of 241 Am in bone using separate arrays of phoswich and germanium detectors demonstrate that a single knee phantom exhibits the same detection efficiency as that using the skull. In vivo measurement of the knee is a desirable alternative to the head if facial contamination is present or when evaluating recent exposure to bone seeking radionuclides, since bones of the knee exhibit more rapid uptake than the skull. In practice, greater measurement efficiency can be obtained by placing detectors over both knees since a larger fraction of the total body activity is observed. Calibration measurements using the new anthropometric knee phantom demonstrate that it is durable, easy to use, and provides consistent results over repeated measurements. (author)

Effect of phantom voxelization in CT simulations

International Nuclear Information System (INIS)

Goertzen, Andrew L.; Beekman, Freek J.; Cherry, Simon R.

2002-01-01

In computer simulations of x-ray CT systems one can either use continuous geometrical descriptions for phantoms or a voxelized representation. The voxelized approach allows arbitrary phantoms to be defined without being confined to geometrical shapes. The disadvantage of the voxelized approach is that inherent errors are introduced due to the phantom voxelization. To study effects of phantom discretization, analytical CT simulations were run for a fan-beam geometry with phantom voxel sizes ranging from 0.0625 to 2 times the reconstructed pixel size and noise levels corresponding to 10 3 -10 7 photons per detector pixel prior to attenuation. The number of rays traced per detector element was varied from 1 to 16. Differences in the filtered backprojection images caused by changing the phantom matrix sizes and number of rays traced were assessed by calculating the difference between reconstructions based on the finest matrix and coarser matrix simulations. In noise free simulations, all phantom matrix sizes produced a measurable difference in comparison with the finest phantom matrix used. When even a small amount of noise was added to the projection data, the differences due to the phantom discretization were masked by the noise, and in all cases there was almost no improvement by using a phantom matrix that was more than twice as fine as the reconstruction matrix. No substantial improvement was achieved by tracing more than 4 rays per detector pixel

TU-D-209-06: Head and Neck Tissue Dose From X-Ray Scatter to Physicians Performing Cardiovascular Procedures

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Fetterly, K; Schueler, B; Grams, M [Mayo Clinic, Rochester, MN (United States); Sturchio, G [Mayo Clinic, Jacksonville, FL (United States)

2016-06-15

Purpose: The purpose of this work was to characterize the spatial distribution of scatter radiation to the head and neck of a physician performing an x-ray interventional procedure and assess brain, eye lens, and carotid artery dose. Methods: Radiographic x-ray beams were tuned to match the peak energy (56 to 106 keV) and HVL (3.5 to 6.5 mm Al) of x-ray scatter originating from a patient during a fluoroscopic procedure. The radiographic beam was directed upon a Rando phantom from an inferior-left location to mimic a typical patient-operator geometric relationship. A lead-equivalent protective garment was secured to the phantom. Direct exposure Gafchromic film (XRQA2) was placed between the transverse plane layers of the head and neck region of the phantom and exposed with 4 scatter-equivalent radiographic beams. A 3×3 cm{sup 2} film placed at the left collar of the phantom was used to monitor incident dose in the position of a radiation monitoring badge. The films were converted to 2D dose distribution maps using FilmQA Pro software and an Epson 11000-XL scanner. The 2D dose distributions maps were normalized by the left collar dose and the percent of left collar dose (%LCD) was calculated for select tissues. Results: The dose maps had high dynamic range (10{sub 4}) and spatial detail. Considering all transverse planes and 4 scatter beam qualities, the median %LCD values were: whole brain 8.5%, left brain 13%, right brain 5.4%, left eye lens 67%, right eye lens 25%, left carotid artery 72%, and right carotid artery 28%. Conclusion: Scatter radiation dose to an operator can be simulated using a tuned radiographic beam and used to expose a phantom and Gafchromic film, thereby creating detailed 2D dose distribution maps. This work facilitates individualized estimation of dose to select head and neck tissues based on an operator’s radiation monitoring badge value.

Effect of CT scanning parameters on volumetric measurements of pulmonary nodules by 3D active contour segmentation: a phantom study

International Nuclear Information System (INIS)

Way, Ted W; Chan, H-P; Goodsitt, Mitchell M; Sahiner, Berkman; Hadjiiski, Lubomir M; Zhou Chuan; Chughtai, Aamer

2008-01-01

The purpose of this study is to investigate the effects of CT scanning and reconstruction parameters on automated segmentation and volumetric measurements of nodules in CT images. Phantom nodules of known sizes were used so that segmentation accuracy could be quantified in comparison to ground-truth volumes. Spherical nodules having 4.8, 9.5 and 16 mm diameters and 50 and 100 mg cc -1 calcium contents were embedded in lung-tissue-simulating foam which was inserted in the thoracic cavity of a chest section phantom. CT scans of the phantom were acquired with a 16-slice scanner at various tube currents, pitches, fields-of-view and slice thicknesses. Scans were also taken using identical techniques either within the same day or five months apart for study of reproducibility. The phantom nodules were segmented with a three-dimensional active contour (3DAC) model that we previously developed for use on patient nodules. The percentage volume errors relative to the ground-truth volumes were estimated under the various imaging conditions. There was no statistically significant difference in volume error for repeated CT scans or scans taken with techniques where only pitch, field of view, or tube current (mA) were changed. However, the slice thickness significantly (p < 0.05) affected the volume error. Therefore, to evaluate nodule growth, consistent imaging conditions and high resolution should be used for acquisition of the serial CT scans, especially for smaller nodules. Understanding the effects of scanning and reconstruction parameters on volume measurements by 3DAC allows better interpretation of data and assessment of growth. Tracking nodule growth with computerized segmentation methods would reduce inter- and intraobserver variabilities

Design and optimization of a beam shaping assembly for BNCT based on D-T neutron generator and dose evaluation using a simulated head phantom.

Science.gov (United States)

Rasouli, Fatemeh S; Masoudi, S Farhad

2012-12-01

A feasibility study was conducted to design a beam shaping assembly for BNCT based on D-T neutron generator. The optimization of this configuration has been realized in different steps. This proposed system consists of metallic uranium as neutron multiplier, TiF(3) and Al(2)O(3) as moderators, Pb as reflector, Ni as shield and Li-Poly as collimator to guide neutrons toward the patient position. The in-air parameters recommended by IAEA were assessed for this proposed configuration without using any filters which enables us to have a high epithermal neutron flux at the beam port. Also a simulated Snyder head phantom was used to evaluate dose profiles due to the irradiation of designed beam. The dose evaluation results and depth-dose curves show that the neutron beam designed in this work is effective for deep-seated brain tumor treatments even with D-T neutron generator with a neutron yield of 2.4×10(12) n/s. The Monte Carlo Code MCNP-4C is used in order to perform these calculations. Copyright © 2012 Elsevier Ltd. All rights reserved.

Microcomputer Network for Computerized Adaptive Testing (CAT)

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1984-03-01

PRDC TR 84-33 \\Q.�d-33- \\ MICROCOMPUTER NETWOJlt FOR COMPUTERIZED ADAPTIVE TESTING ( CAT ) Baldwin Quan Thomas A . Park Gary Sandahl John H...ACCEIIION NO NPRDC TR 84-33 4. TITLE (-d Sul>tlllo) MICROCOMP UTER NETWORK FOR COMPUTERIZED ADA PTIVE TESTING ( CAT ) 1. Q B. uan T. A . Park...adaptive testing ( CAT ) Bayesian sequential testing 20. ABSTitACT (Continuo on ro•••• aide II noco .. _, _., ld-tlly ,.,. t.loclt _._.) DO Computerized

The level of detail required in a deformable phantom to accurately perform quality assurance of deformable image registration

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Saenz, Daniel L.; Kim, Hojin; Chen, Josephine; Stathakis, Sotirios; Kirby, Neil

2016-09-01

The primary purpose of the study was to determine how detailed deformable image registration (DIR) phantoms need to adequately simulate human anatomy and accurately assess the quality of DIR algorithms. In particular, how many distinct tissues are required in a phantom to simulate complex human anatomy? Pelvis and head-and-neck patient CT images were used for this study as virtual phantoms. Two data sets from each site were analyzed. The virtual phantoms were warped to create two pairs consisting of undeformed and deformed images. Otsu’s method was employed to create additional segmented image pairs of n distinct soft tissue CT number ranges (fat, muscle, etc). A realistic noise image was added to each image. Deformations were applied in MIM Software (MIM) and Velocity deformable multi-pass (DMP) and compared with the known warping. Images with more simulated tissue levels exhibit more contrast, enabling more accurate results. Deformation error (magnitude of the vector difference between known and predicted deformation) was used as a metric to evaluate how many CT number gray levels are needed for a phantom to serve as a realistic patient proxy. Stabilization of the mean deformation error was reached by three soft tissue levels for Velocity DMP and MIM, though MIM exhibited a persisting difference in accuracy between the discrete images and the unprocessed image pair. A minimum detail of three levels allows a realistic patient proxy for use with Velocity and MIM deformation algorithms.

Phantom cosmologies and fermions

International Nuclear Information System (INIS)

Chimento, Luis P; Forte, Monica; Devecchi, Fernando P; Kremer, Gilberto M

2008-01-01

Form invariance transformations can be used for constructing phantom cosmologies starting with conventional cosmological models. In this work we reconsider the scalar field case and extend the discussion to fermionic fields, where the 'phantomization' process exhibits a new class of possible accelerated regimes. As an application we analyze the cosmological constant group for a fermionic seed fluid

Computerized system for measuring cerebral metabolism

International Nuclear Information System (INIS)

McGlone, J.S.; Hibbard, L.S.; Hawkins, R.A.; Kasturi, R.

1987-01-01

A computerized stereotactic measurement system for evaluating rat brain metabolism was developed to utilize the large amount of data generated by quantitative autoradiography. Conventional methods of measurement only analyze a small percent of these data because these methods are limited by instrument design and the subjectiveness of the investigator. However, a computerized system allows digital images to be analyzed by placing data at their appropriate three-dimensional stereotactic coordinates. The system automatically registers experimental data to a standard three-dimensional image using alignment, scaling, and matching operations. Metabolic activity in different neuronal structures is then measured by generating digital masks and superimposing them on to experimental data. Several experimental data sets were evaluated and it was noticed that the structures measured by the computerized system, had in general, lower metabolic activity than manual measurements had indicated. This was expected because the computerized system measured the structure over its volume while the manual readings were taken from the most active metabolic area of a particular structure

A statistically defined anthropomorphic software breast phantom

International Nuclear Information System (INIS)

Lau, Beverly A.; Reiser, Ingrid; Nishikawa, Robert M.; Bakic, Predrag R.

2012-01-01

Purpose: Digital anthropomorphic breast phantoms have emerged in the past decade because of recent advances in 3D breast x-ray imaging techniques. Computer phantoms in the literature have incorporated power-law noise to represent glandular tissue and branching structures to represent linear components such as ducts. When power-law noise is added to those phantoms in one piece, the simulated fibroglandular tissue is distributed randomly throughout the breast, resulting in dense tissue placement that may not be observed in a real breast. The authors describe a method for enhancing an existing digital anthropomorphic breast phantom by adding binarized power-law noise to a limited area of the breast. Methods: Phantoms with (0.5 mm) 3 voxel size were generated using software developed by Bakic et al. Between 0% and 40% of adipose compartments in each phantom were replaced with binarized power-law noise (β = 3.0) ranging from 0.1 to 0.6 volumetric glandular fraction. The phantoms were compressed to 7.5 cm thickness, then blurred using a 3 × 3 boxcar kernel and up-sampled to (0.1 mm) 3 voxel size using trilinear interpolation. Following interpolation, the phantoms were adjusted for volumetric glandular fraction using global thresholding. Monoenergetic phantom projections were created, including quantum noise and simulated detector blur. Texture was quantified in the simulated projections using power-spectrum analysis to estimate the power-law exponent β from 25.6 × 25.6 mm 2 regions of interest. Results: Phantoms were generated with total volumetric glandular fraction ranging from 3% to 24%. Values for β (averaged per projection view) were found to be between 2.67 and 3.73. Thus, the range of textures of the simulated breasts covers the textures observed in clinical images. Conclusions: Using these new techniques, digital anthropomorphic breast phantoms can be generated with a variety of glandular fractions and patterns. β values for this new phantom are comparable

Evaluation of brain scintigraphy and computerized tomography

International Nuclear Information System (INIS)

Cavailloles, F.; Dairou, R.; Desbleds, M.T.; Benoit, C.; Larmande, P.; Bok, B.; Alperovitch, A.

1983-01-01

In order to assess the clinical usefulness of brain computerized tomography and radionuclide scan, a prospective study was performed on a series of 554 patients. The detection rate was assessed as well as the identification rate of lesions. In addition, the usefulness of both tests was appreciated subjectively by two neurologists reviewing the patients' files. Both give reasonably similar results: computerized tomography is superior to radionuclide scan in the diagnosis of tumors and intracerebral hematomas, the radionuclide scan being slightly superior in the diagnosis of purely ischemic CVA and subdural hematomas. The superiority which was subjectively conceded to computerized tomography was greater than that objectively demonstrated. However, clinical usefulness of computerized tomography was judged important in only 50% of the cases. Moreover, to request both computerized tomography and radionuclide scan appeared as having no interest in 83% of the cases. In that series, the diagnostic hypotheses were in agreement with the final diagnosis in 88% of the cases. Bias encountered in this type of studies are discussed [fr

Experience of development and testing of a new model of an anthropomorphic radiodosimetric phantom of the human body ARDF-10 'Roman'

International Nuclear Information System (INIS)

Bruhov, R.E.; Finkel, F.V.

2013-01-01

In 2006-2010 by the commission of the Radiation and Nuclear Safety Authority in Finland applied scientific research and development of a new model of an anthropomorphic radio dosimetric phantom of the human body (the Phantom) were performed, after the development of the production technology and initial testing in 2010-2012 the first serial copy of the Phantom under the name ARDF-10 ROMAN was produced. The main application of the new model of the Phantom ARDF-10 ROMAN: - increase of the precision of calibration and implementation of the periodic monitoring of Whole body counters (WBC) equipment, standardization of measurement procedure for inter-laboratory comparisons of the incorporated activity. - metrological support of the development and implementation of new methods for human radiation spectrometry: identification of radionuclide content of incorporated activity in the human body; measurements of the activity of incorporated technogenic and natural radionuclides in the whole body and in the lungs; measurements of 90 Sr content in the bone tissue. Study of the mechanisms of the intake, distribution, accumulation and excretion of the radionuclides in the human body, such as: daughter products of 222 Rn decay in the respiratory tract, 241 Am, other transuranic elements; isotopes of iodine in the thyroid gland; radiopharmaceuticals administered to patients for diagnostic and medicinal purposes. Obtaining estimates of spatial-temporal distribution of individual internal exposure dose of a human. The result of the work of recent years has been the creation of hygienic safe standard sample of an anthropomorphic radio dosimetric phantom of the human body ARDF-10 ROMAN, consisting of 4 anthropometric models of body parts, which are independent assembly units (head phantom, neck phantom, torso phantom, knee phantom). Phantom models are made from simulators of bone, soft (muscle) and lungs biological tissue. The Phantom contains 28 separate elements. To the first

Computerized tomography in myotonic dystrophy

International Nuclear Information System (INIS)

Gellerich, I.; Mueller, D.; Koch, R.D.

1986-01-01

Besides clinical symptoms, progress and electromyography computerized tomography improves the diagnostics of myotonic dystrophy. Even small changes in muscular structure are detectable and especially the musculus soleus exhibits early and pronounced alterations. By means of density distribution pattern an improved characterization of the disease is possible. Additional information is obtained by cerebral computerized tomography. Atrophy of brain tissue is to be expected in all patients with myotonic dystrophy. (author)

Computerized reactor monitor and control for research reactors

International Nuclear Information System (INIS)

Buerger, L.; Vegh, E.

1981-09-01

The computerized process control system developed in the Central Research Institute for Physics, Budapest, Hungary, is described together with its special applications at research reactors. The nuclear power of the Hungarian research reactor is controlled by this computerized system, too, while in Lybia many interesting reactor-hpysical calculations are built into the computerized monitor system. (author)

An improved Virtual Torso phantom

International Nuclear Information System (INIS)

Kramer, Gary H; Crowley, Paul

2000-01-01

The virtual phantom that was previously designed by the Human Monitoring Laboratory had some limitations. It contained no sternum and the ribs extended all the way round the torso, whereas in reality the central part of the chest is covered with a mixture of cartilage (ribs) and bone (sternum). The ribs were located below the chest wall which added to the thickness of the chest wall. The lungs did not touch the inner surface of the chest wall along their length due to the differences in curvature between the ellipsoidal lungs and the ellipsoidal cylinder that defined the torso. As a result there was extra intervening tissue between the lungs and the chest wall. This was shown to have a noticeable effect on the simulation of low energy photons. The virtual phantom has been redesigned and comparison of measured and calculated counting efficiencies shows that it is a good representation of both of LLNL or JAERI at all photon energies measured. The redesigned virtual phantom agrees to within 11% of the torsos' counting efficiency over the energy range 17 - 240 keV. Before modification, the virtual phantom's counting efficiency was a of factor three lower at 17 keV and a factor of two lower at 20 keV; now it is within 5% at 17 keV and within 10% at 20 keV. This phantom can now be reliably used to simulate lung counting. The virtual phantom still contains no sternum and the ribs extend all the way round the torso, whereas in reality the central part of the chest is covered with cartilage (ribs) and bone (sternum). However, the above results indicate that this is not a major flaw in the design of the virtual phantom, as agreement between the Monte Carlo results and experimental data is good. (author)

Design and investigations of a DD compact neutron generator in head radiotherapy

International Nuclear Information System (INIS)

Araujo, Wagner; Campos, Tarcisio Passos Ribeiro

2013-01-01

Neutron generators are device-based particle accelerators for producing neutrons through fusion reactions between hydrogen isotopes. Such devices may enable noninvasive treatments of head and neck tumors, which represent about one hundred twenty-nine thousand cases per year around the world. The present paper shows electromagnetic and nuclear simulations of a neutron generator coupled to collimator and evaluations of radiation dose in an analytical head phantom irradiated by the device. The results provide the generator design and the operation parameter in order to achieve prescribed tumor dose. Also, dose distribution in organs of head is presented, being suitable to surrounding brain tumors close to the skull. As conclusion, there is a visibility of neutron generator applied to brain tumor radiation therapy. (author)

Comparison of Volumes between Four-Dimensional Computed Tomography and Cone-Beam Computed Tomography Images using Dynamic Phantom

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Kim, Seong Eun; Won, Hui Su; Hong, Joo Wan; Chang, Nam Jun; Jung, Woo Hyun; Choi, Byeong Don [Dept. of Radiation Oncology, Seoul National University Bundang Hospital, Sungnam (Korea, Republic of)

2016-12-15

The aim of this study was to compare the differences between the volumes acquired with four-dimensional computed tomography (4DCT)images with a reconstruction image-filtering algorithm and cone-beam computed tomography (CBCT) images with dynamic phantom. The 4DCT images were obtained from the computerized imaging reference systems (CIRS) phantom using a computed tomography (CT) simulator. We analyzed the volumes for maximum intensity projection (MIP), minimum intensity projection (MinIP) and average intensity projection (AVG) of the images obtained with the 4DCT scanner against those acquired from CBCT images with CT ranger tools. Difference in volume for node of 1, 2 and 3 cm between CBCT and 4DCT was 0.54⁓2.33, 5.16⁓8.06, 9.03⁓20.11 ml in MIP, respectively, 0.00⁓1.48, 0.00⁓8.47, 1.42⁓24.85 ml in MinIP, respectively and 0.00⁓1.17, 0.00⁓2.19, 0.04⁓3.35 ml in AVG, respectively. After a comparative analysis of the volumes for each nodal size, it was apparent that the CBCT images were similar to the AVG images acquired using 4DCT.

On the pathogenesis of traumatic intracerebral hematoma with a sequential study of computerized tomography

International Nuclear Information System (INIS)

Ohmori, Hidetoshi; Miyazaki, Shinichiro; Munekata, Katsuharu; Fukushima, Hiromi; Shohji, Akira.

1981-01-01

A sequential study with computerized tomography (CT scan) of two cases of traumatic intracerebral hematoma is reported. Case 1 was a 69-year-old man who had a head injury. The initial CT scan, taken 1 hour after his injury, showed a left temporal salt-and-pepper appearance, which proved to be a cerebral contusion. The CT scan 4.5 hours after his injury showed a left temporal high density area instead. An operation was performed, and a massive intracerebral hematoma was observed. Case 2 was a 61-year-old man who was also admitted because of a head injury. The initial CT scan, taken 1 hour after his injury, revealed several bifrontal intracerebral hemorrhagic spots in the low-density areas, suggesting contusion. A secondary CT scan (23 hours) demonstrated that the traumatic intracerebral hematoma had developed into a posttraumatic cerebral contusion. The operation disclosed a hematoma surrounded by contusion. These cases prove that traumatic intracerebral hematoma is often caused by cerebral contusion. (author)

Comparison of methods for individualized astronaut organ dosimetry: Morphometry-based phantom library versus body contour autoscaling of a reference phantom

Science.gov (United States)

Sands, Michelle M.; Borrego, David; Maynard, Matthew R.; Bahadori, Amir A.; Bolch, Wesley E.

2017-11-01

One of the hazards faced by space crew members in low-Earth orbit or in deep space is exposure to ionizing radiation. It has been shown previously that while differences in organ-specific and whole-body risk estimates due to body size variations are small for highly-penetrating galactic cosmic rays, large differences in these quantities can result from exposure to shorter-range trapped proton or solar particle event radiations. For this reason, it is desirable to use morphometrically accurate computational phantoms representing each astronaut for a risk analysis, especially in the case of a solar particle event. An algorithm was developed to automatically sculpt and scale the UF adult male and adult female hybrid reference phantom to the individual outer body contour of a given astronaut. This process begins with the creation of a laser-measured polygon mesh model of the astronaut's body contour. Using the auto-scaling program and selecting several anatomical landmarks, the UF adult male or female phantom is adjusted to match the laser-measured outer body contour of the astronaut. A dosimetry comparison study was conducted to compare the organ dose accuracy of both the autoscaled phantom and that based upon a height-weight matched phantom from the UF/NCI Computational Phantom Library. Monte Carlo methods were used to simulate the environment of the August 1972 and February 1956 solar particle events. Using a series of individual-specific voxel phantoms as a local benchmark standard, autoscaled phantom organ dose estimates were shown to provide a 1% and 10% improvement in organ dose accuracy for a population of females and males, respectively, as compared to organ doses derived from height-weight matched phantoms from the UF/NCI Computational Phantom Library. In addition, this slight improvement in organ dose accuracy from the autoscaled phantoms is accompanied by reduced computer storage requirements and a more rapid method for individualized phantom generation

Composition of MRI phantom equivalent to human tissues

International Nuclear Information System (INIS)

Kato, Hirokazu; Kuroda, Masahiro; Yoshimura, Koichi; Yoshida, Atsushi; Hanamoto, Katsumi; Kawasaki, Shoji; Shibuya, Koichi; Kanazawa, Susumu

2005-01-01

We previously developed two new MRI phantoms (called the CAG phantom and the CAGN phantom), with T1 and T2 relaxation times equivalent to those of any human tissue at 1.5 T. The conductivity of the CAGN phantom is equivalent to that of most types of human tissue in the frequency range of 1 to 130 MHz. In this paper, the relaxation times of human tissues are summarized, and the composition of the corresponding phantoms are provided in table form. The ingredients of these phantoms are carrageenan as the gelling agent, GdCl 3 as a T1 modifier, agarose as a T2 modifier, NaCl (CAGN phantom only) as a conductivity modifier, NaN 3 as an antiseptic, and distilled water. The phantoms have T1 values of 202-1904 ms and T2 values of 38-423 ms when the concentrations of GdCl 3 and agarose are varied from 0-140 μmol/kg, and 0%-1.6%, respectively, and the CAGN phantom has a conductivity of 0.27-1.26 S/m when the NaCl concentration is varied from 0%-0.7%. These phantoms have sufficient strength to replicate a torso without the use of reinforcing agents, and can be cut by a knife into any shape. We anticipate the CAGN phantom to be highly useful and practical for MRI and hyperthermia-related research

Activity quantification of phantom using dual-head SPECT with two-view planar image

International Nuclear Information System (INIS)

Guo Leiming; Chen Tao; Sun Xiaoguang; Huang Gang

2005-01-01

The absorbed radiation dose from internally deposited radionuclide is a major factor in assessing risk and therapeutic utility in nuclear medicine diagnosis or treatment. The quantification of absolute activity in vivo is necessary procedure of estimating the absorbed dose of organ or tissue. To understand accuracy in the determination of organ activity, the experiments on 99 Tc m activity quantification were made for a body phantom using dual-heat SPECT with the two-view counting technique. Accuracy in the activity quantification is credible and is not affected by depth of source organ in vivo. When diameter of the radiation source is ≤2 cm, the most accurate activity quantification result can be obtained on the basis of establishing the system calibration factor and transmission factor. The use of Buijs's method is preferable, especially at very low source-to-background activity concentration rations. (authors)

Superficial Ultrasound Shear Wave Speed Measurements in Soft and Hard Elasticity Phantoms: Repeatability and Reproducibility Using Two Different Ultrasound Systems

Science.gov (United States)

Dillman, Jonathan R.; Chen, Shigao; Davenport, Matthew S.; Zhao, Heng; Urban, Matthew W.; Song, Pengfei; Watcharotone, Kuanwong; Carson, Paul L.

2014-01-01

Background There is a paucity of data available regarding the repeatability and reproducibility of superficial shear wave speed (SWS) measurements at imaging depths relevant to the pediatric population. Purpose To assess the repeatability and reproducibility of superficial shear wave speed (SWS) measurements acquired from elasticity phantoms at varying imaging depths using three different imaging methods, two different ultrasound systems, and multiple operators. Methods and Materials Soft and hard elasticity phantoms manufactured by Computerized Imaging Reference Systems, Inc. (Norfolk, VA) were utilized for our investigation. Institution #1 used an Acuson S3000 ultrasound system (Siemens Medical Solutions USA, Inc.) and three different shear wave imaging method/transducer combinations, while institution #2 used an Aixplorer ultrasound system (Supersonic Imagine) and two different transducers. Ten stiffness measurements were acquired from each phantom at three depths (1.0, 2.5, and 4.0 cm) by four operators at each institution. Student’s t-test was used to compare SWS measurements between imaging techniques, while SWS measurement agreement was assessed with two-way random effects single measure intra-class correlation coefficients and coefficients of variation. Mixed model regression analysis determined the effect of predictor variables on SWS measurements. Results For the soft phantom, the average of mean SWS measurements across the various imaging methods and depths was 0.84 ± 0.04 m/s (mean ± standard deviation) for the Acuson S3000 system and 0.90 ± 0.02 m/s for the Aixplorer system (p=0.003). For the hard phantom, the average of mean SWS measurements across the various imaging methods and depths was 2.14 ± 0.08 m/s for the Acuson S3000 system and 2.07 ± 0.03 m/s Aixplorer system (p>0.05). The coefficients of variation were low (0.5–6.8%), and inter-operator agreement was near-perfect (ICCs ≥0.99). Shear wave imaging method and imaging depth

Optimum size of a calibration phantom for x-ray CT to convert the Hounsfield units to stopping power ratios in charged particle therapy treatment planning.

Science.gov (United States)

Inaniwa, T; Tashima, H; Kanematsu, N

2018-03-01

In charged-particle therapy treatment planning, the volumetric distribution of stopping power ratios (SPRs) of body tissues relative to water is used for patient dose calculation. The distribution is conventionally obtained from computed tomography (CT) images of a patient using predetermined conversion functions from the CT numbers to the SPRs. One of the biggest uncertainty sources of patient SPR estimation is insufficient correction of beam hardening arising from the mismatch between the size of the patient cross section and the calibration phantom for producing the conversion functions. The uncertainty would be minimized by selecting a suitable size for the cylindrical water calibration phantom, referred to as an 'effective size' of the patient cross section, Leffective. We investigated the Leffective for pelvis, abdomen, thorax, and head and neck regions by simulating an ideal CT system using volumetric models of the reference male and female phantoms. The Leffective values were 23.3, 20.3, 22.7 and 18.8 cm for the pelvis, abdomen, thorax, and head and neck regions, respectively, and the Leffective for whole body was 21.0 cm. Using the conversion function for a 21.0-cm-diameter cylindrical water phantom, we could reduce the root mean square deviation of the SPRs and their mean deviation to ≤0.011 and ≤0.001, respectively, in the whole body. Accordingly, for simplicity, the effective size of 21.0 cm can be used for the whole body, irrespective of body-part regions for treatment planning in clinical practice.

Anti-3-[(18)F]FACBC positron emission tomography-computerized tomography and (111)In-capromab pendetide single photon emission computerized tomography-computerized tomography for recurrent prostate carcinoma: results of a prospective clinical trial.

Science.gov (United States)

Schuster, David M; Nieh, Peter T; Jani, Ashesh B; Amzat, Rianot; Bowman, F Dubois; Halkar, Raghuveer K; Master, Viraj A; Nye, Jonathon A; Odewole, Oluwaseun A; Osunkoya, Adeboye O; Savir-Baruch, Bital; Alaei-Taleghani, Pooneh; Goodman, Mark M

2014-05-01

We prospectively evaluated the amino acid analogue positron emission tomography radiotracer anti-3-[(18)F]FACBC compared to ProstaScint® ((111)In-capromab pendetide) single photon emission computerized tomography-computerized tomography to detect recurrent prostate carcinoma. A total of 93 patients met study inclusion criteria who underwent anti-3-[(18)F]FACBC positron emission tomography-computerized tomography plus (111)In-capromab pendetide single photon emission computerized tomography-computerized tomography for suspected recurrent prostate carcinoma within 90 days. Reference standards were applied by a multidisciplinary board. We calculated diagnostic performance for detecting disease. In the 91 of 93 patients with sufficient data for a consensus on the presence or absence of prostate/bed disease anti-3-[(18)F]FACBC had 90.2% sensitivity, 40.0% specificity, 73.6% accuracy, 75.3% positive predictive value and 66.7% negative predictive value compared to (111)In-capromab pendetide with 67.2%, 56.7%, 63.7%, 75.9% and 45.9%, respectively. In the 70 of 93 patients with a consensus on the presence or absence of extraprostatic disease anti-3-[(18)F]FACBC had 55.0% sensitivity, 96.7% specificity, 72.9% accuracy, 95.7% positive predictive value and 61.7% negative predictive value compared to (111)In-capromab pendetide with 10.0%, 86.7%, 42.9%, 50.0% and 41.9%, respectively. Of 77 index lesions used to prove positivity histological proof was obtained in 74 (96.1%). Anti-3-[(18)F]FACBC identified 14 more positive prostate bed recurrences (55 vs 41) and 18 more patients with extraprostatic involvement (22 vs 4). Anti-3-[(18)F]FACBC positron emission tomography-computerized tomography correctly up-staged 18 of 70 cases (25.7%) in which there was a consensus on the presence or absence of extraprostatic involvement. Better diagnostic performance was noted for anti-3-[(18)F]FACBC positron emission tomography-computerized tomography than for (111)In-capromab pendetide single

SU-E-J-119: Head-And-Neck Digital Phantoms for Geometric and Dosimetric Uncertainty Evaluation of CT-CBCT Deformable Image Registration

International Nuclear Information System (INIS)

Shen, Z; Koyfman, S; Xia, P; Bzdusek, K

2015-01-01

Purpose: To evaluate geometric and dosimetric uncertainties of CT-CBCT deformable image registration (DIR) algorithms using digital phantoms generated from real patients. Methods: We selected ten H&N cancer patients with adaptive IMRT. For each patient, a planning CT (CT1), a replanning CT (CT2), and a pretreatment CBCT (CBCT1) were used as the basis for digital phantom creation. Manually adjusted meshes were created for selected ROIs (e.g. PTVs, brainstem, spinal cord, mandible, and parotids) on CT1 and CT2. The mesh vertices were input into a thin-plate spline algorithm to generate a reference displacement vector field (DVF). The reference DVF was applied to CBCT1 to create a simulated mid-treatment CBCT (CBCT2). The CT-CBCT digital phantom consisted of CT1 and CBCT2, which were linked by the reference DVF. Three DIR algorithms (Demons, B-Spline, and intensity-based) were applied to these ten digital phantoms. The images, ROIs, and volumetric doses were mapped from CT1 to CBCT2 using the DVFs computed by these three DIRs and compared to those mapped using the reference DVF. Results: The average Dice coefficients for selected ROIs were from 0.83 to 0.94 for Demons, from 0.82 to 0.95 for B-Spline, and from 0.67 to 0.89 for intensity-based DIR. The average Hausdorff distances for selected ROIs were from 2.4 to 6.2 mm for Demons, from 1.8 to 5.9 mm for B-Spline, and from 2.8 to 11.2 mm for intensity-based DIR. The average absolute dose errors for selected ROIs were from 0.7 to 2.1 Gy for Demons, from 0.7 to 2.9 Gy for B- Spline, and from 1.3 to 4.5 Gy for intensity-based DIR. Conclusion: Using clinically realistic CT-CBCT digital phantoms, Demons and B-Spline were shown to have similar geometric and dosimetric uncertainties while intensity-based DIR had the worst uncertainties. CT-CBCT DIR has the potential to provide accurate CBCT-based dose verification for H&N adaptive radiotherapy. Z Shen: None; K Bzdusek: an employee of Philips Healthcare; S Koyfman: None; P Xia

Phantom motor execution facilitated by machine learning and augmented reality as treatment for phantom limb pain: a single group, clinical trial in patients with chronic intractable phantom limb pain.

Science.gov (United States)

Ortiz-Catalan, Max; Guðmundsdóttir, Rannveig A; Kristoffersen, Morten B; Zepeda-Echavarria, Alejandra; Caine-Winterberger, Kerstin; Kulbacka-Ortiz, Katarzyna; Widehammar, Cathrine; Eriksson, Karin; Stockselius, Anita; Ragnö, Christina; Pihlar, Zdenka; Burger, Helena; Hermansson, Liselotte

2016-12-10

Phantom limb pain is a debilitating condition for which no effective treatment has been found. We hypothesised that re-engagement of central and peripheral circuitry involved in motor execution could reduce phantom limb pain via competitive plasticity and reversal of cortical reorganisation. Patients with upper limb amputation and known chronic intractable phantom limb pain were recruited at three clinics in Sweden and one in Slovenia. Patients received 12 sessions of phantom motor execution using machine learning, augmented and virtual reality, and serious gaming. Changes in intensity, frequency, duration, quality, and intrusion of phantom limb pain were assessed by the use of the numeric rating scale, the pain rating index, the weighted pain distribution scale, and a study-specific frequency scale before each session and at follow-up interviews 1, 3, and 6 months after the last session. Changes in medication and prostheses were also monitored. Results are reported using descriptive statistics and analysed by non-parametric tests. The trial is registered at ClinicalTrials.gov, number NCT02281539. Between Sept 15, 2014, and April 10, 2015, 14 patients with intractable chronic phantom limb pain, for whom conventional treatments failed, were enrolled. After 12 sessions, patients showed statistically and clinically significant improvements in all metrics of phantom limb pain. Phantom limb pain decreased from pre-treatment to the last treatment session by 47% (SD 39; absolute mean change 1·0 [0·8]; p=0·001) for weighted pain distribution, 32% (38; absolute mean change 1·6 [1·8]; p=0·007) for the numeric rating scale, and 51% (33; absolute mean change 9·6 [8·1]; p=0·0001) for the pain rating index. The numeric rating scale score for intrusion of phantom limb pain in activities of daily living and sleep was reduced by 43% (SD 37; absolute mean change 2·4 [2·3]; p=0·004) and 61% (39; absolute mean change 2·3 [1·8]; p=0·001), respectively. Two of four

Toxicology Analysis of Tissue-Mimicking Phantom Made From Gelatin

Science.gov (United States)

Dolbashid, A. S.; Hamzah, N.; Zaman, W. S. W. K.; Mokhtar, M. S.

2017-06-01

Skin phantom mimics the biological skin tissues as it have the ability to respond to changes in its environment. The development of tissue-mimicking phantom could contributes towards the reduce usage of animal in cosmetics and pharmacokinetics. In this study, the skin phantoms made from gelatin were tested with four different commonly available cosmetic products to determine the toxicity of each substance. The four substances used were; mercury-based whitening face cream, carcinogenic liquid make-up foundation, paraben-based acne cleanser, and organic lip balm. Toxicity test were performed on all of the phantoms. For toxicity testing, topographical and electrophysiological changes of the phantoms were evaluated. The ability of each respective phantom to react with mild toxic substances and its electrical resistance were analysed in to determine the toxicity of all the phantom models. Four-electrode method along with custom made electrical impedance analyser was used to differentiate electrical resistance between intoxicated phantom and non-intoxicated phantom in this study. Electrical resistance values obtained from the phantom models were significantly higher than the control group. The result obtained suggests the phantom as a promising candidate to be used as alternative for toxicology testing in the future.

A Software Phantom : Application in Digital Tomosynthesis

Energy Technology Data Exchange (ETDEWEB)

Lazos, D; Kolitsi, Z; Badea, C; Pallikarakis, N [Medical Physics Laboratory, School of Medicine, Univercity of Patras (Greece)

1999-12-31

A software phantom intended to be used in radiographic applications has been developed. The application was used for research in the field of Digital Tomosynthesis and specifically for studying tomographic noise removal methods. The application consists of a phantom design and a phantom imaging module. The radiation-matter interaction is based on the exponential relation of attenuation. Projections are formed by simulated irradiation with selectable geometrical parameters, source spectrum and detector response. Phantoms are defined either as sets containing certain geometrical objects or as groups of voxels. Comparison with real projections taken from a physical phantom with identical geometry and composition with the simulated one, showed good approximation with improved contrast due to the absence of scatter in the simulated projections. The software phantom proved to be a very useful tool for DTS investigations. Further development to include scatter is expected to expand the use of the application to more areas in radiological imaging research. (author) 4 refs., 3 figs

A Software Phantom : Application in Digital Tomosynthesis

International Nuclear Information System (INIS)

Lazos, D.; Kolitsi, Z.; Badea, C.; Pallikarakis, N.

1998-01-01

A software phantom intended to be used in radiographic applications has been developed. The application was used for research in the field of Digital Tomosynthesis and specifically for studying tomographic noise removal methods. The application consists of a phantom design and a phantom imaging module. The radiation-matter interaction is based on the exponential relation of attenuation. Projections are formed by simulated irradiation with selectable geometrical parameters, source spectrum and detector response. Phantoms are defined either as sets containing certain geometrical objects or as groups of voxels. Comparison with real projections taken from a physical phantom with identical geometry and composition with the simulated one, showed good approximation with improved contrast due to the absence of scatter in the simulated projections. The software phantom proved to be a very useful tool for DTS investigations. Further development to include scatter is expected to expand the use of the application to more areas in radiological imaging research. (author)

Quantifying surgical access in eyebrow craniotomy with and without orbital bar removal: cadaver and surgical phantom studies.

Science.gov (United States)

Zador, Zsolt; Coope, David J; Gnanalingham, Kanna; Lawton, Michael T

2014-04-01

Eyebrow craniotomy is a recently described minimally invasive approach for tackling primarily pathology of the anterior skull base. The removal of the orbital bar may further expand the surgical corridor of this exposure, but the extent of benefit is poorly quantified. We assessed the effect of orbital bar removal with regards to surgical access in the eyebrow craniotomy using classic morphometric measurements in cadaver heads. Using surgical phantoms and neuronavigation, we also measured the 'working volume', a new parameter for characterising the volume of surgical access in these approaches. Silicon injected cadaver heads (n = 5) were used for morphometric analysis of the eyebrow craniotomy with and without orbital bar removal. Working depths and 'working areas' of surgical access were measured as defined by key anatomical landmarks. The eyebrow craniotomy with or without orbital bar removal was also simulated using surgical phantoms (n = 3, 90-120 points per trial), calibrated against a frameless neuronavigation system. Working volume was derived from reference coordinates recorded along the anatomical borders of the eyebrow craniotomy using the "α-shape algorithm" in R statistics. In cadaver heads, eyebrow craniotomy with removal of the orbital bar reduced the working depth to the ipsilateral anterior clinoid process (42 ± 2 versus 33 ± 3 mm; p < 0.05), but the working areas as defined by deep neurovascular and bony landmarks was statistically unchanged (total working areas of 418 ± 80 cm(2) versus 334 ± 48 cm(2); p = 0.4). In surgical phantom studies, however, working-volume for the simulated eyebrow craniotomies was increased with orbital bar removal (16 ± 1 cm(3) versus 21 ± 1 cm(3); p < 0.01). In laboratory studies, orbital bar removal in eyebrow craniotomy provides a modest reduction in working depth and increase in the working volume. But this must be weighed up against the added morbidity of the

Ultrasonographic Quantification of Fat Content in Fatty Liver Phantoms

International Nuclear Information System (INIS)

Kim, Il Young; Kim, Pyo Nyun; Joo, Gyung Soo; Kim, Ho Jung; Kim, Young Beom; Lee, Byoung Ho

1995-01-01

Assuming that the fat content of certain tissue might be quantified by measurirrg the ultrasound echo level, we analyzed the ultrasound histograms obtained from the fatty liver phantoms that contained various amount of fat. Various amount of margarine(Mazola. Cliff wood. USA) was mixed with 2% of agarin solution state to produce fatty liver phantoms that contained 5, 10, 20, 30 and 40% of fat. We obtained ultrasound histogram from each fatty liver phantom in gel state. We used 2% agar gel as a control. The ultrasound histograms from the control phantom showed gradual increase in echo level as the depth from the surface increased. The echo level from the phantom that contained 5% of fat showed gradual increase and subsequent decrease with the peak echo level at the depth of 3cm. The echo levels from the phantoms that contained more in 5% of fat gradually decreased as the depth from the surface increased; the change becoming more pronounced as the fat content of the phantom increased. The echo levels measured at the depth of 1cm were 9.3(control), 29.6(5%phantom), 3l.3 (10% phantom), 26.3 (20% phantom), l8.8 (30% phantom), and l6dB (40% phantom). Fat content of fatty phantoms can not be quantified by measuring only echo level. Simultaneous measurement of attenuation of ultrasound, which is not easy to do and not done in this study, is prerequisite to quantify fat content

Single photon emission computerized tomography (SPECT)

International Nuclear Information System (INIS)

Ganatra, R.D.

1992-01-01

Tomography in nuclear medicine did not originate after the introduction of X-ray computerized tomography (CT). Even in the days of rectilinear scanner, tomography was attempted with multiple detector heads rotating around the patient, but the counts at each plane were never very high to obtain a satisfactory image. A high resolution focusing collimator can look at different depths but taking several slices in one projection was a time consuming process. Rectilinear scanners lose lot of counts in the collimator to look at one point, at on time, in one plane. It is true that attempts to do tomography with gamma camera really got a boost after the success of CT. By that time, algorithms for doing reconstruction of images also were highly refined and for advanced. Clinical application of SPECT has become widespread now, because of the development of suitable radiopharmaceuticals and improvement in instrumentation. The SPECT provides a direct measure of regional organ function and is performed with nuclides such as 123 I and 99 Tc m that emit a mono-image photon during their decay. SPECT is far less expensive than positron emission tomography

Single photon emission computerized tomography (SPECT)

Energy Technology Data Exchange (ETDEWEB)

Ganatra, R D

1993-12-31

Tomography in nuclear medicine did not originate after the introduction of X-ray computerized tomography (CT). Even in the days of rectilinear scanner, tomography was attempted with multiple detector heads rotating around the patient, but the counts at each plane were never very high to obtain a satisfactory image. A high resolution focusing collimator can look at different depths but taking several slices in one projection was a time consuming process. Rectilinear scanners lose lot of counts in the collimator to look at one point, at on time, in one plane. It is true that attempts to do tomography with gamma camera really got a boost after the success of CT. By that time, algorithms for doing reconstruction of images also were highly refined and for advanced. Clinical application of SPECT has become widespread now, because of the development of suitable radiopharmaceuticals and improvement in instrumentation. The SPECT provides a direct measure of regional organ function and is performed with nuclides such as {sup 123}I and {sup 99}Tc{sup m} that emit a mono-image photon during their decay. SPECT is far less expensive than positron emission tomography

Phantom Eye Syndrome: A Review of the Literature

Directory of Open Access Journals (Sweden)

Agda M. Andreotti

2014-01-01

Full Text Available The purpose of this literature review was to describe the main features of phantom eye syndrome in relation to their possible causes, symptoms, treatments, and influence of eye amputation on quality of life of anophthalmic patients. For this, a bibliographical research was performed in Pubmed database using the following terms: “eye amputation,” “eye trauma,” “phantom eye syndrome,” “phantom pain,” and “quality of life,” associated or not. Thirteen studies were selected, besides some relevant references contained in the selected manuscripts and other studies hallowed in the literature. Thus, 56 articles were included in this review. The phantom eye syndrome is defined as any sensation reported by the patient with anophthalmia, originated anophthalmic cavity. In phantom eye syndrome, at least one of these three symptoms has to be present: phantom vision, phantom pain, and phantom sensations. This syndrome has a direct influence on the quality of life of the patients, and psychological support is recommended before and after the amputation of the eyeball as well as aid in the treatment of the syndrome. Therefore, it is suggested that, for more effective treatment of phantom eye syndrome, drug therapy should be associated with psychological approach.

A phantom for quality control in mammography

International Nuclear Information System (INIS)

Gambaccini, M.; Rimondi, O.; Marziani, M.; Toti, A.

1989-01-01

A phantom for evaluating image quality in mammography has been designed and will be used in the Italian national programme ''Dose and Quality in Mammography''. The characteristics of the phantom are (a) about the same X-ray transmission as a 5 cm 50% fat and 50% water breast for energies between 15 and 50 keV and (b) optimum energies for imaging of the test objects (included in the phantom) in very close agreement with the optimum energies for imaging of calcifications and tumours in a 5 cm 50% fat and 50% water breast. An experimental comparison between the prototype and some commercial phantoms was carried out. Measurements are in progress to test the phantom's ability to evaluate the performances of mammographic systems quantitatively. (author)

Recent developments in detectors/phantoms for dosimetry, X-ray quality assurance and imaging

International Nuclear Information System (INIS)

Sankaran, A.

2009-01-01

During the past years, many new developments have taken place in detectors/phantoms for high energy photon and electron dosimetry (for radiotherapy), protection monitoring, X-ray quality assurance and X-ray imaging (for radiodiagnosis). A variety of detectors and systems, quality assurance (QA) gadgets and special phantoms have been developed for diverse applications. This paper discusses the important developments with some of which the author was actively associated in the past. For dosimetry and QA of 60 Co and high energy X-ray units, state-of-the-art radiation field analyzers, matrix ion chambers, MOSFET devices and Gafchromic films are described. OSL detectors find wide use in radiotherapy dosimetry and provide a good alternative for personnel monitoring. New systems introduced for QA/dosimetry of X-ray units and CT scanners include: multi-function instruments for simultaneous measurement of kVp, dose, time, X-ray waveform and HVT on diagnostic X-ray units; pencil chamber with head and body phantoms for CTDI check on CT scanners. Examples of phantoms used for dosimetry and imaging are given. Advancements in the field of diagnostic X-ray imaging (with applications in portal imaging/dosimetry of megavoltage X-ray units) have led to emergence of: film-replacement systems employing CCD-scintillator arrays, computed radiography (CR) using storage phosphor plate; digital radiography (DR), using a pixel-matrix of amorphous selenium, or amorphous silicon diode coupled to scintillator. All these provide (a) in radiotherapy, accurate dose delivery to tumour, saving the surrounding tissues and (b) in radiodiagnosis, superior image quality with low patient exposure. Lastly, iPODs and flash drives are utilized for storage of gigabyte-size images encountered in medical and allied fields. Although oriented towards medical applications, some of these have been of great utility in other fields, such as industrial radiography as well as a host of other research areas. (author)

Absorbed dose to the patient by computerized whole body X-ray tomography

International Nuclear Information System (INIS)

Krauss, O.; Schuhmacher, H.

1977-01-01

The absorbed dose to the patient was measured for several medical investigations by computerized whole body scanning. An Alderson-phantom mounted with LiF-TLD was irradiated with a Delta-Scan (Ohio-Nuclear, 120 kV, 30 mA). The integral dose to the brain during a full examination (6 scans, filtration 3 mm Al) was measured to 5x10 -2 J. The maximum absorbed dose at the entrance was found to be 3.2 rd and at the exit 0.6 rd. The dose to the eyes is 0.7 rd and to the thyroid gland 0.03 rd. The integral dose to the trunk (5 scans in the region of liver and kidneys, filtration 6 mm Al) was measured to 5x10 -2 J. The maximum absorbed dose at the entrance was found to be 2.4 rd and at the exit 0.25 rd. The dose to the gonads is less than 2 and 4 mrd if the distance between the last scan and the gonads is more than 15 cm

Phantom cosmology without Big Rip singularity

Energy Technology Data Exchange (ETDEWEB)

Astashenok, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, 236041, 14, Nevsky st., Kaliningrad (Russian Federation); Nojiri, Shin' ichi, E-mail: nojiri@phys.nagoya-u.ac.jp [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya University, Nagoya 464-8602 (Japan); Odintsov, Sergei D. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan); Institucio Catalana de Recerca i Estudis Avancats - ICREA and Institut de Ciencies de l' Espai (IEEC-CSIC), Campus UAB, Facultat de Ciencies, Torre C5-Par-2a pl, E-08193 Bellaterra (Barcelona) (Spain); Tomsk State Pedagogical University, Tomsk (Russian Federation); Yurov, Artyom V. [Baltic Federal University of I. Kant, Department of Theoretical Physics, 236041, 14, Nevsky st., Kaliningrad (Russian Federation)

2012-03-23

We construct phantom energy models with the equation of state parameter w which is less than -1, w<-1, but finite-time future singularity does not occur. Such models can be divided into two classes: (i) energy density increases with time ('phantom energy' without 'Big Rip' singularity) and (ii) energy density tends to constant value with time ('cosmological constant' with asymptotically de Sitter evolution). The disintegration of bound structure is confirmed in Little Rip cosmology. Surprisingly, we find that such disintegration (on example of Sun-Earth system) may occur even in asymptotically de Sitter phantom universe consistent with observational data. We also demonstrate that non-singular phantom models admit wormhole solutions as well as possibility of Big Trip via wormholes.

Phantom cosmology without Big Rip singularity

International Nuclear Information System (INIS)

Astashenok, Artyom V.; Nojiri, Shin'ichi; Odintsov, Sergei D.; Yurov, Artyom V.

2012-01-01

We construct phantom energy models with the equation of state parameter w which is less than -1, w<-1, but finite-time future singularity does not occur. Such models can be divided into two classes: (i) energy density increases with time (“phantom energy” without “Big Rip” singularity) and (ii) energy density tends to constant value with time (“cosmological constant” with asymptotically de Sitter evolution). The disintegration of bound structure is confirmed in Little Rip cosmology. Surprisingly, we find that such disintegration (on example of Sun-Earth system) may occur even in asymptotically de Sitter phantom universe consistent with observational data. We also demonstrate that non-singular phantom models admit wormhole solutions as well as possibility of Big Trip via wormholes.

Intraindividual variability as an indicator of malingering in head injury.

Science.gov (United States)

Strauss, Esther; Slick, Daniel J; Levy-Bencheton, Judi; Hunter, Michael; MacDonald, Stuart W S; Hultsch, David F

2002-07-01

The utility of various measures of malingering was evaluated using an analog design in which half the participants (composed of three groups: naive healthy people, professionals working with head-injured people, individuals who suffered a head injury but not currently in litigation) were asked to try their best and the remainder was asked to feign believable injury. Participants were assessed with the Reliable Digit Span (RDS) task, the Victoria Symptom Validity Test (VSVT), and the Computerized Dot Counting Test (CDCT) on three separate occasions in order to determine whether repeat administration of tests improves prediction. The results indicated that regardless of an individual's experience, consideration of both level of performance (particularly on forced-choice symptom validity tasks) and intraindividual variability holds considerable promise for the detection of malingering.

Development of digital phantom for DRR evaluation

International Nuclear Information System (INIS)

Ikeda, Tsuyoshi; Katsuta, Shoichi; Oyama, Masaya; Ogino, Takashi

2009-01-01

Generally, digitally reconstructed radiograph (DRR) is evaluated by physical phantom. The CT image is camouflaged by the performance of the radiation treatment planning system and contains a variety of error factors. The CT image (as follows the digital phantom), where an arbitrary CT value is arranged in the matrix, is necessary to evaluate the pure performance of the radiation treatment planning system. In this study, the development of a digital phantom is described, and the utility is discussed. CTport and the radiation treatment planning system are evaluated with the use of a digital phantom as follows: geometrical accuracy evaluation of DRR, consisting of the center position, size of irradiation field, distortion, extension of X-ray, and beam axis, and the image quality evaluation of DRR, which consists of the contrast resolution. As for DRR made with CTport and the treatment planning system, the part that shifted geometrically was confirmed. In the image quality evaluation, there was a remarkable difference. Because the making accuracy and the installation accuracy of the phantom do not influence the digital phantom, the geometrical accuracy of the DRR is reliable. Because the CT conditions and the phantom factor have no influence, the peculiar DRR image quality can be evaluated and used to evaluate the best image processing parameters. (author)

Optimising cardiac/angiographic digital images using a Butternut as the image quality phantom

International Nuclear Information System (INIS)

Bibbo, G.; Balman, D.

2008-01-01

injected contrast can be used for high-level contrast visualisation and edge enhancement. The noise level can be evaluated from the image of the whole pulp of the phantom. A reasonable size butternut is equivalent to the head of about a 6-month-old infant. The images from patients produced using these optimised protocols were diagnostic and well received by radiologists and cardiologists. Any final fine adjustments necessary to improve the protocols can be made by evaluating patients' images. Using the butternut phantom, we were able to reduce the dose per image by a factor of about two with respect to the images produced with the original protocols supplied by the manufacturer. Butternuts are cheap, have a long storage life and can be purchased in any supermarket and greengrocer shop practically all year round. Our experience has shown that they are suitable for optimising imaging protocols used in cardiac/general/interventional angiography, general fluoroscopy and computed radiography. (author)

Development of the Reference Korean Female Voxel Phantom

International Nuclear Information System (INIS)

Ham, Bo Kyoung; Cho, Kun Woo; Yeom, Yoen Soo; Jeong, Jong Hwi; Kim, Chan Hyeong; Han, Min Cheol

2012-01-01

The objective of this study is for development of the reference Korean female phantom, HDRK-Woman. The phantom was constructed by adjusting a Korean woman voxel phantom to the Reference Korean data. The Korean woman phantom had been developed based on the high-resolution color slice images obtained from an adult Korean female cadaver. There were a total of 39 organs including the 27 organs specified in ICRP 103 for effective dose calculation. The voxel resolution of the phantom was 1.967 X 1.967 X X 2.0619 mm 3 and the voxel array size is 261 X 109 X 825 in the x, y and z directions. Then, the voxel resolution was changed to 2.0351 X 2.0351 X 2.0747 mm 3 for adjustment of the height and total bone mass of the phantom to the Reference Korean data. Finally, the internal organs and tissue were adjusted using in-house software program developed for 3D volume adjustment of the organs and tissue. The effective dose values of HDRK phantoms were calculated for broad parallel photon beams using MCNPX Monte Carlo code and compared with those of ICRP phantoms.

Development of the Reference Korean Female Voxel Phantom

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Ham, Bo Kyoung; Cho, Kun Woo [University of Science and Technology, Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of); Yeom, Yoen Soo; Jeong, Jong Hwi; Kim, Chan Hyeong; Han, Min Cheol [Hanyang University, Seoul (Korea, Republic of)

2012-03-15

The objective of this study is for development of the reference Korean female phantom, HDRK-Woman. The phantom was constructed by adjusting a Korean woman voxel phantom to the Reference Korean data. The Korean woman phantom had been developed based on the high-resolution color slice images obtained from an adult Korean female cadaver. There were a total of 39 organs including the 27 organs specified in ICRP 103 for effective dose calculation. The voxel resolution of the phantom was 1.967 X 1.967 X X 2.0619 mm{sup 3} and the voxel array size is 261 X 109 X 825 in the x, y and z directions. Then, the voxel resolution was changed to 2.0351 X 2.0351 X 2.0747 mm{sup 3} for adjustment of the height and total bone mass of the phantom to the Reference Korean data. Finally, the internal organs and tissue were adjusted using in-house software program developed for 3D volume adjustment of the organs and tissue. The effective dose values of HDRK phantoms were calculated for broad parallel photon beams using MCNPX Monte Carlo code and compared with those of ICRP phantoms.

Development of a physical 3D anthropomorphic breast phantom

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Carton, Ann-Katherine; Bakic, Predrag; Ullberg, Christer; Derand, Helen; Maidment, Andrew D. A. [Department of Radiology, University of Pennsylvania, 1 Silverstein Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104-4206 (United States); XCounter AB, Svaerdvaegen 11, SE-182 33 Danderyd (Sweden); Department of Radiology, University of Pennsylvania, 1 Silverstein Building, 3400 Spruce Street, Philadelphia, Pennsylvania 19104-4206 (United States)

2011-02-15

Purpose: Develop a technique to fabricate a 3D anthropomorphic breast phantom with known ground truth for image quality assessment of 2D and 3D breast x-ray imaging systems. Methods: The phantom design is based on an existing computer model that can generate breast voxel phantoms of varying composition, size, and shape. The physical phantom is produced in two steps. First, the portion of the voxel phantom consisting of the glandular tissue, skin, and Cooper's ligaments is separated into sections. These sections are then fabricated by high-resolution rapid prototyping using a single material with 50% glandular equivalence. The remaining adipose compartments are then filled using an epoxy-based resin (EBR) with 100% adipose equivalence. The phantom sections are stacked to form the physical anthropomorphic phantom. Results: The authors fabricated a prototype phantom corresponding to a 450 ml breast with 45% dense tissue, deformed to a 5 cm compressed thickness. Both the rapid prototype (RP) and EBR phantom materials are radiographically uniform. The coefficient of variation (CoV) of the relative attenuation between RP and EBR phantom samples was <1% and the CoV of the signal intensity within RP and EBR phantom samples was <1.5% on average. Digital mammography and reconstructed digital breast tomosynthesis images of the authors' phantom were reviewed by two radiologists; they reported that the images are similar in appearance to clinical images, noting there are still artifacts from air bubbles in the EBR. Conclusions: The authors have developed a technique to produce 3D anthropomorphic breast phantoms with known ground truth, yielding highly realistic x-ray images. Such phantoms may serve both qualitative and quantitative performance assessments for 2D and 3D breast x-ray imaging systems.

Acceptance and implementation of a system of planning computerized based on Monte Carlo; Aceptacion y puesta en marcha de un sistema de planificacion comutarizada basado en Monte Carlo

Energy Technology Data Exchange (ETDEWEB)

Lopez-Tarjuelo, J.; Garcia-Molla, R.; Suan-Senabre, X. J.; Quiros-Higueras, J. Q.; Santos-Serra, A.; Marco-Blancas, N.; Calzada-Feliu, S.

2013-07-01

It has been done the acceptance for use clinical Monaco computerized planning system, based on an on a virtual model of the energy yield of the head of the linear electron Accelerator and that performs the calculation of the dose with an algorithm of x-rays (XVMC) based on Monte Carlo algorithm. (Author)

Computational anthropomorphic phantoms for radiation protection dosimetry: evolution and prospects

International Nuclear Information System (INIS)

Lee, Choonsik; Lee, Jaiki

2006-01-01

Computational anthropomorphic phantoms are computer models of human anatomy used in the calculation of radiation dose distribution in the human body upon exposure to a radiation source. Depending on the manner to represent human anatomy, they are categorized into two classes: stylized and tomographic phantoms. Stylized phantoms, which have mainly been developed at the Oak Ridge National Laboratory (ORNL), describe human anatomy by using simple mathematical equations of analytical geometry. Several improved stylized phantoms such as male and female adults, pediatric series, and enhanced organ models have been developed following the first hermaphrodite adult stylized phantom, Medical Internal Radiation Dose (MIRD)-5 phantom. Although stylized phantoms have significantly contributed to dosimetry calculation, they provide only approximations of the true anatomical features of the human body and the resulting organ dose distribution. An alternative class of computational phantom, the tomographic phantom, is based upon three-dimensional imaging techniques such as Magnetic Resonance (MR) imaging and Computed Tomography (CT). The tomographic phantoms represent the human anatomy with a large number of voxels that are assigned tissue type and organ identity. To date, a total of around 30 tomographic phantoms including male and female adults, pediatric phantoms, and even a pregnant female, have been developed and utilized for realistic radiation dosimetry calculation. They are based on MRI/CT images or sectional color photos from patients, volunteers or cadavers. Several investigators have compared tomographic phantoms with stylized phantoms, and demonstrated the superiority of tomographic phantoms in terms of realistic anatomy and dosimetry calculation. This paper summarizes the history and current status of both stylized and tomographic phantoms, including Korean computational phantoms. Advantages, limitations, and future prospects are also discussed

SU-F-T-449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

Energy Technology Data Exchange (ETDEWEB)

Uehara, R [National Cancer Center Hospital East, Kashiwa, Chiba (Japan); Tachibana, H [National Cancer Center, Kashiwa, Chiba (Japan)

2016-06-15

Purpose: There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high-density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans. Methods: In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x-ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans had been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC-calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose-volumetric data obtained using the two different calculation algorithms were compared. Results: The results in the phantom evaluation for the shallow area ahead of the build-up region shows over-dose for AXB and under-dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high-density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin-dose. Conclusion: In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high-density media, steep dose gradient regions and skin-surface. There are limitations in skin-dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot-spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.

SU-F-T-449: Dosimetric Comparison of Acuros XB, Adaptive Convolve in Intensity Modulated Radiotherapy for Head and Neck Cancer

International Nuclear Information System (INIS)

Uehara, R; Tachibana, H

2016-01-01

Purpose: There have been several publications focusing on dose calculation in lung for a new dose calculation algorithm of Acuros XB (AXB). AXB could contribute to dose calculation for high-density media for bone and dental prosthesis rather than in lung. We compared the dosimetric performance of AXB, Adaptive Convolve (AC) in head and neck IMRT plans. Methods: In a phantom study, the difference in depth profile between AXB and AC was evaluated using Kodak EDR2 film sandwiched with tough water phantoms. 6 MV x-ray using the TrueBeam was irradiated. In a patient study, 20 head and neck IMRT plans had been clinically approved in Pinnacle3 and were transferred to Eclipse. Dose distribution was recalculated using AXB in Eclipse while maintaining AC-calculated monitor units and MLC sequence planned in Pinnacle. Subsequently, both the dose-volumetric data obtained using the two different calculation algorithms were compared. Results: The results in the phantom evaluation for the shallow area ahead of the build-up region shows over-dose for AXB and under-dose for AC, respectively. In the patient plans, AXB shows more hot spots especially around the high-density media than AC in terms of PTV (Max difference: 4.0%) and OAR (Max. difference: 1.9%). Compared to AC, there were larger dose deviations in steep dose gradient region and higher skin-dose. Conclusion: In head and neck IMRT plans, AXB and AC show different dosimetric performance for the regions inside the target volume around high-density media, steep dose gradient regions and skin-surface. There are limitations in skin-dose and complex anatomic condition using even inhomogeneous anthropomorphic phantom Thus, there is the potential for an increase of hot-spot in AXB, and an underestimation of dose in substance boundaries and skin regions in AC.

[Mirror, mirror of the wall: mirror therapy in the treatment of phantom limbs and phantom limb pain].

Science.gov (United States)

Casale, Roberto; Furnari, Anna; Lamberti, Raul Coelho; Kouloulas, Efthimios; Hagenberg, Annegret; Mallik, Maryam

2015-01-01

Phantom limb and phantom limb pain control are pivotal points in the sequence of intervention to bring the amputee to functional autonomy. The alterations of perception and sensation, the pain of the residual limb and the phantom limb are therefore aspects of amputation that should be taken into account in the "prise en charge" of these patients. Within the more advanced physical therapies to control phantom and phantom limb pain there is the use of mirrors (mirror therapy). This article willfocus on its use and on the possible side effects induced by the lack of patient selection and a conflict of body schema restoration through mirror therapy with concurrent prosthetic training and trauma acceptance. Advice on the need to select patients before treatment decisions, with regard to their psychological as well as clinical profile (including time since amputation and clinical setting), and the need to be aware of the possible adverse effects matching different and somehow conflicting therapeutic approaches, are put forward. Thus a coordinated sequence of diagnostic, prognostic and therapeutic procedures carried out by an interdisciplinary rehabilitation team that works globally on all patients' problems is fundamental in the management of amputees and phantom limb pain. Further studies and the development of a multidisciplinary network to study this and other applications of mirror therapy are needed.

Contrast detail phantom for SPECT

Energy Technology Data Exchange (ETDEWEB)

Cabrejas, M.L. de; Arashiro, J G; Giannone, C. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina); Camuyrano, M; Nohara, G [Universidad de Buenos Aires, Buenos Aires (Argentina). Facultad Ciencias Exactas

1996-06-01

A new low variable contrast phantom for single photon emission computed tomography (SPECT) was constructed, tested and compared with other existing phantoms. It contains simulated cylindrical lesions of four different diameters (D{sub i}), embedded in a cylindrical scattering medium and a uniform section to evaluate tomographic uniformity. The concentration of tracer in the simulated lesions and the scattering medium (background) can be varied to simulate hot and cold lesions. Different applications of the phantom were tested, including determination of the minimum object contrast (OCm) necessary to detect lesions as a function of lesion size, lesion type (hot or cold) and acquisition and processing protocols by visual inspection. This parameter allows categorization of instruments comparing an `image quality index` (IQI). Preliminary comparison with the Britten contrast processing method showed that the detectable OCm was of the same order of magnitude, but the presented device seems more suitable for training and intercomparison purposes. The constructed phantom, of simple design, has proved to be useful for acquisition and processing condition evaluation, OCm estimation and external quality control. (author). 11 refs, 4 figs.

Computerized Classification Testing with the Rasch Model

Science.gov (United States)

Eggen, Theo J. H. M.

2011-01-01

If classification in a limited number of categories is the purpose of testing, computerized adaptive tests (CATs) with algorithms based on sequential statistical testing perform better than estimation-based CATs (e.g., Eggen & Straetmans, 2000). In these computerized classification tests (CCTs), the Sequential Probability Ratio Test (SPRT) (Wald,…

Superficial ultrasound shear wave speed measurements in soft and hard elasticity phantoms: repeatability and reproducibility using two ultrasound systems.

Science.gov (United States)

Dillman, Jonathan R; Chen, Shigao; Davenport, Matthew S; Zhao, Heng; Urban, Matthew W; Song, Pengfei; Watcharotone, Kuanwong; Carson, Paul L

2015-03-01

There is a paucity of data available regarding the repeatability and reproducibility of superficial shear wave speed (SWS) measurements at imaging depths relevant to the pediatric population. To assess the repeatability and reproducibility of superficial shear wave speed measurements acquired from elasticity phantoms at varying imaging depths using three imaging methods, two US systems and multiple operators. Soft and hard elasticity phantoms manufactured by Computerized Imaging Reference Systems Inc. (Norfolk, VA) were utilized for our investigation. Institution No. 1 used an Acuson S3000 US system (Siemens Medical Solutions USA, Malvern, PA) and three shear wave imaging method/transducer combinations, while institution No. 2 used an Aixplorer US system (SuperSonic Imagine, Bothell, WA) and two different transducers. Ten stiffness measurements were acquired from each phantom at three depths (1.0 cm, 2.5 cm and 4.0 cm) by four operators at each institution. Student's t-test was used to compare SWS measurements between imaging techniques, while SWS measurement agreement was assessed with two-way random effects single-measure intra-class correlation coefficients (ICCs) and coefficients of variation. Mixed model regression analysis determined the effect of predictor variables on SWS measurements. For the soft phantom, the average of mean SWS measurements across the various imaging methods and depths was 0.84 ± 0.04 m/s (mean ± standard deviation) for the Acuson S3000 system and 0.90 ± 0.02 m/s for the Aixplorer system (P = 0.003). For the hard phantom, the average of mean SWS measurements across the various imaging methods and depths was 2.14 ± 0.08 m/s for the Acuson S3000 system and 2.07 ± 0.03 m/s Aixplorer system (P > 0.05). The coefficients of variation were low (0.5-6.8%), and interoperator agreement was near-perfect (ICCs ≥ 0.99). Shear wave imaging method and imaging depth significantly affected measured SWS (P�

Mathematical human phantoms and their application to radiation protection

International Nuclear Information System (INIS)

Yamaguchi, Yasuhiro

1998-01-01

This review described the characteristics of mathematical phantoms, their history over 30 years and their application. Mathematical phantoms are classified into two models of formula and voxel types. In the former, human body and organs are described by 2- and/or 3-D mathematical formula and can be seen as a combination of solid bodies like spheres, cubes and ovals. The phantom is composed from three tissue components (bone, lung and soft tissue) and made on data on Reference Man in ICRP Publ. 23. The latter voxel (volume pixel) phantom consists from a number of small cubes based on CT and MRI images of a certain man. For instance, the phantom CHILD, 1.54 x 1.54 x 8.00 mm 3 in size, is based on a 7-year old child, which consisting from about one million voxels. The mathematical phantom was first made in Oak Ridge National Laboratory in the middle of the nineteen-sixties, which have undergone various improvements to reach MIRD-5 phantom. Thereafter, many similitude phantoms have been made as a variation of MIRD-5, depending on age and sex (e.g., ADAM and EVA). Voxel phantom was made in the middle of nineteen-eighties and have undergone improvements which are continued even currently in Japan, U.S. etc. The mathematical phantoms are used for calculation of radiation transport program by Monte Carlo method in the field of radiation protection. Also in the field of medicine, the phantom is used for calculation of internal and external exposure doses, of correction constants of externally measuring instruments, of doses for neutron capture therapy and of A-bomb exposure doses in Hiroshima and Nagasaki for reevaluation. Recently, the development of phantom is in the current from formula phantom to voxel one due to the purpose of precision and standardization. (K.H.)

Simulation of computed tomography dose based on voxel phantom

Science.gov (United States)

Liu, Chunyu; Lv, Xiangbo; Li, Zhaojun

2017-01-01

Computed Tomography (CT) is one of the preferred and the most valuable imaging tool used in diagnostic radiology, which provides a high-quality cross-sectional image of the body. It still causes higher doses of radiation to patients comparing to the other radiological procedures. The Monte-Carlo method is appropriate for estimation of the radiation dose during the CT examinations. The simulation of the Computed Tomography Dose Index (CTDI) phantom was developed in this paper. Under a similar conditions used in physical measurements, dose profiles were calculated and compared against the measured values that were reported. The results demonstrate a good agreement between the calculated and the measured doses. From different CT exam simulations using the voxel phantom, the highest absorbed dose was recorded for the lung, the brain, the bone surface. A comparison between the different scan type shows that the effective dose for a chest scan is the highest one, whereas the effective dose values during abdomen and pelvis scan are very close, respectively. The lowest effective dose resulted from the head scan. Although, the dose in CT is related to various parameters, such as the tube current, exposure time, beam energy, slice thickness and patient size, this study demonstrates that the MC simulation is a useful tool to accurately estimate the dose delivered to any specific organs for patients undergoing the CT exams and can be also a valuable technique for the design and the optimization of the CT x-ray source.

Limiting CT radiation dose in children with craniosynostosis: phantom study using model-based iterative reconstruction

Energy Technology Data Exchange (ETDEWEB)

Kaasalainen, Touko; Lampinen, Anniina [University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Center, Radiology, POB 340, Helsinki (Finland); University of Helsinki, Department of Physics, Helsinki (Finland); Palmu, Kirsi [University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Center, Radiology, POB 340, Helsinki (Finland); School of Science, Aalto University, Department of Biomedical Engineering and Computational Science, Helsinki (Finland); Reijonen, Vappu; Kortesniemi, Mika [University of Helsinki and Helsinki University Hospital, HUS Medical Imaging Center, Radiology, POB 340, Helsinki (Finland); Leikola, Junnu [University of Helsinki and Helsinki University Hospital, Department of Plastic Surgery, Helsinki (Finland); Kivisaari, Riku [University of Helsinki and Helsinki University Hospital, Department of Neurosurgery, Helsinki (Finland)

2015-09-15

Medical professionals need to exercise particular caution when developing CT scanning protocols for children who require multiple CT studies, such as those with craniosynostosis. To evaluate the utility of ultra-low-dose CT protocols with model-based iterative reconstruction techniques for craniosynostosis imaging. We scanned two pediatric anthropomorphic phantoms with a 64-slice CT scanner using different low-dose protocols for craniosynostosis. We measured organ doses in the head region with metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters. Numerical simulations served to estimate organ and effective doses. We objectively and subjectively evaluated the quality of images produced by adaptive statistical iterative reconstruction (ASiR) 30%, ASiR 50% and Veo (all by GE Healthcare, Waukesha, WI). Image noise and contrast were determined for different tissues. Mean organ dose with the newborn phantom was decreased up to 83% compared to the routine protocol when using ultra-low-dose scanning settings. Similarly, for the 5-year phantom the greatest radiation dose reduction was 88%. The numerical simulations supported the findings with MOSFET measurements. The image quality remained adequate with Veo reconstruction, even at the lowest dose level. Craniosynostosis CT with model-based iterative reconstruction could be performed with a 20-μSv effective dose, corresponding to the radiation exposure of plain skull radiography, without compromising required image quality. (orig.)

A dynamic phantom for radionuclide renography

International Nuclear Information System (INIS)

Heikkinen, J.O.

1999-01-01

The aim of the study was to develop and test a dynamic phantom simulating radionuclide renography. The phantom consisted of five partly lead covered plastic containers simulating kidneys, heart, bladder and background (soft tissues, liver and spleen). Dynamics were performed with multiple movable steel plates between containers and a gamma camera. Control of the plates is performed manually with a stopwatch following exact time schedules. The containers were filled with activities ( 99m Tc) which produce count rates close to clinical situations. Count rates produced by the phantom were compared with ten clinical renography cases: five 99m Tc MAG3 and five 99m Tc DTPA examinations. Two phantom simulations were repeated three times with separate fillings, acquisitions and analyses. Precision errors as a coefficient of variation (CV) of repeated measurements were calculated and theoretical values were compared with the corresponding measured ones. A multicentre comparison was made between 19 nuclear medicine laboratories and three clinical cases were simulated with the phantom. Correlations between count rates produced by the phantom and clinical studies were r=0.964 for 99m Tc MAG3 (p 99m Tc DTPA (p max was 4.0±1.6%. Images and curves of the scanned phantom were close to a real patient in all 19 laboratories but calculated parameters varied: the difference between theoretical and measured values for T max was 6.8±6.2%. The difference between laboratories is most probably due to variations in acquisition protocols and analysis programs: 19 laboratories with 18 different protocols and 8 different programs. The dynamics were found to be repeatable and suitable for calibration purposes for radionuclide renography programs and protocols as well as for multicentre comparisons. (author)

The value of attenuation correction in dual-head coincidence imaging

International Nuclear Information System (INIS)

Shi Yiping; Huang Gang; Liu Jianjun

2004-01-01

Objective: To elucidate the value of attenuation correction (AC) in dual-head coincidence imaging by comparison of phantom and patients images with and without AC. Methods: We used a 20-cm-diameter cylindrical phantom, which contains four spheres of inside diameters of 1.4-2.9 cm for phantom study (1.4 cm, n=2; 2.0 cm, n=l; 2.9 cm, n=1). The axial length of the phantom was 30 cm. The wall thickness of the spheres was 1 mm. Both the phantom and spheres were filled with a solution that contained 18F-FDG. Three acquisitions were performed with the concentrations adjusted to provide a ratio of sphere-to-background activity of 3:1, 5:1 and 10:1. There were 38 patients (30 men and 8 women, age range 31 to 78 years) with suspected lung cancer included in clinical study. All patients were performed pneumonectomies and verified by histopathology. The histological tumor types were adenocarcinoma (n=11), squamous carcinoma (n=8), adenosquamous carcinoma (n=4), large cell carcinoma (n=2), neuroendocrine carcinoma (n=l), metastatic carcinoma (n=4), bronchiolo-alveolar carcinoma (n=1) and benign mass (n=7). The patients were fasted for at least 6 hours before the start of the study. Sixty minutes after intravenous administration of 111-185MBq (3-5mCi) 18F-FDG, emission scanning was performed using a dual-head gamma camera with a 128x128x16 matrix, with energy windows of 511 keV, 180 degree rotation, 32 steps and an acquisition time of 40 s per step. Subsequently, transmission scanning was performed with energy windows of 662 keV, 360 degree rotation, 96 steps and an acquisition time of 2s per step. The coincidence gamma camera imaging data were reconstructed by MCD iterative Methods with a Wiener filter (noise factor 0.75, pixel size 3.95 mm 3 ). Visual analysis and semiquantitative analysis were performed in AC and NAC images. For visual interpretation, a positive lesion was defined as any activity above local background. The count ratio of tumor to surrounded normal tissue (T

Determination of gonad, eye and bone marrow doses with EMI-5005 head and whole body scans

International Nuclear Information System (INIS)

Nishizawa, Kanae; Iwata, Takeo; Furuya, Yoshiro; Maruyama, Takashi; Hashizume, Tadashi.

1979-01-01

Dose determinations of tissues and organs during head and whole body scanning with an EMI computed tomographic equipment have been carried out using a Rando woman phantom. The surface dose on the phantom was measured with a Sakura lith Contact film dosimeter system. The absorbed doses in the eyes, thyroids, ovaries and the bone marrow were measured with a thermoluminescent dosimeter. The resultant surface doses for head scanning were 2.8 rad (28 mGy) per scan at maximum and 0.26 rad (2.6 mGy) per scan at minimum, and the doses for whole body scanning were 2.7 rad (27 mGy) per scan at maximum and 0.1 rad (1.0 mGy) per scan at minimum. For the complete gynecological scanning consisting of 8 slices, the eye, thyroid, ovary and the bone marrow dose was 2.4 mrad (24 μGy), 3.5 mrad (35 μGy), 500 mrad (5 mGy) and 225 mrad (2.25 mGy), respectively. And, for a typical head scanning consisting of 5 slices, the eye, thyroid, ovary and the bone marrow dose was 1400 mrad (14 mGy), 46 mrad (460 μGy), 0.60 mrad (6 μGy) and 73 mrad (730 μGy), respectively. (author)

Phantom inflation and the 'Big Trip'

International Nuclear Information System (INIS)

Gonzalez-Diaz, Pedro F.; Jimenez-Madrid, Jose A.

2004-01-01

Primordial inflation is regarded to be driven by a phantom field which is here implemented as a scalar field satisfying an equation of state p=ωρ, with ω-1. Being even aggravated by the weird properties of phantom energy, this will pose a serious problem with the exit from the inflationary phase. We argue, however, in favor of the speculation that a smooth exit from the phantom inflationary phase can still be tentatively recovered by considering a multiverse scenario where the primordial phantom universe would travel in time toward a future universe filled with usual radiation, before reaching the big rip. We call this transition the 'Big Trip' and assume it to take place with the help of some form of anthropic principle which chooses our current universe as being the final destination of the time transition

Stratification of mammographic computerized analysis by BI-RADS categories

International Nuclear Information System (INIS)

Lederman, Richard; Leichter, Isaac; Buchbinder, Shalom; Novak, Boris; Bamberger, Philippe; Fields, Scott

2003-01-01

The Breast Imaging Reporting and Data System (BI-RADS) was implemented to standardize characterization of mammographic findings. The purpose of the present study was to evaluate in which BI-RADS categories the changes recommended by computerized mammographic analysis are most beneficial. Archival cases including, 170 masses (101 malignant, 69 benign) and 63 clusters of microcalcifications (MCs; 36 malignant, 27 benign), were evaluated retrospectively, using the BI-RADS categories, by several radiologists, blinded to the pathology results. A computerized system then automatically extracted from the digitized mammogram features characterizing mammographic lesions, which were used to classify the lesions. The results of the computerized classification scheme were compared, by receiver operating characteristics (ROC) analysis, to the conventional interpretation. In the ''low probability of malignancy group'' (excluding BI-RADS categories 4 and 5), computerized analysis improved the A z of the ROC curve significantly, from 0.57 to 0.89. In the ''high probability of malignancy group'' (mostly category 5) the computerized analysis yielded an ROC curve with an A z of 0.99. In the ''intermediate probability of malignancy group'' computerized analysis improved the A z significantly, from 0.66 for to 0.83. Pair-wise analysis showed that in the latter group the modifications resulting from computerized analysis were correct in 83% of cases. Computerized analysis has the ability to improve the performance of the radiologists exactly in the BI-RADS categories with the greatest difficulties in arriving at a correct diagnosis. It increased the performance significantly in the problematic group of ''intermediate probability of malignancy'' and pinpointed all the cases with missed cancers in the ''low probability'' group. (orig.)

Computerized industrial tomography

International Nuclear Information System (INIS)

Ashraf, M.M.

1999-01-01

Computerized Tomographic (CT) has been used for a number of applications in the field of medicine and industry. For the last couple of years, the technique has been applied for the material characterization and detection of defects and flaws inside the industrial components of nuclear, aerospace and missile industries. A CT scanner of first generation was developed at the institute. The scanner has been used to demonstrate couple of applications of CT in the field of non destructive testing of materials. The data acquired by placing the test objects at various angles and scanning the object through a source detector assembly has been processed on a Pentium computer for image reconstruction using a filtered back projection method. The technique has been developed which can be modified and improved to study various other applications in materials science and a modern computerized tomographic facility can be established. (author)

Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyun Gi [Ajou University School of Medicine, Ajou University Medical Center, Department of Radiology, Yeongtong-gu, Suwon (Korea, Republic of); Lee, Ho-Joon; Lee, Seung-Koo; Kim, Myung-Joon [Severance Hospital, Yonsei University College of Medicine, Department of Radiology and Research Institute of Radiological Science, Seodaemun-gu, Seoul (Korea, Republic of); Kim, Hyun Ji [Ajou University School of Medicine, Office of Biostatistics, Department of Humanities and Social Medicine, Yeongtong-gu, Suwon (Korea, Republic of)

2017-09-15

To investigate the quality of images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V), using pediatric head CT protocols. A phantom was scanned at decreasing 20% mA intervals using our standard pediatric head CT protocols. Each study was then reconstructed at 10% ASIR-V intervals. After the phantom study, we reduced mA by 10% in the protocol for <3-year-old patients and applied 30% ASIR-V and by 30% in the protocol for 3- to 15-year-old patients and applied 40% ASIR-V. Increasing the percentage of ASIR-V resulted in lower noise and higher contrast-to-noise ratio (CNR) and preserved spatial resolution in the phantom study. Compared to a conventional-protocol, reduced-dose protocol with ASIR-V achieved 12.8% to 34.0% of dose reduction and showed images of lower noise (9.22 vs. 10.73, P = 0.043) and higher CNR in different levels (centrum semiovale, 2.14 vs. 1.52, P = 0.003; basal ganglia, 1.46 vs. 1.07, P = 0.001; and cerebellum, 2.18 vs. 1.33, P < 0.001). Qualitative analysis showed higher gray-white matter differentiation and sharpness and preserved overall diagnostic quality in the images with ASIR-V. Use of ASIR-V allowed a 12.8% to 34.0% dose reduction in each age group with potential to improve image quality. (orig.)

Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children

International Nuclear Information System (INIS)

Kim, Hyun Gi; Lee, Ho-Joon; Lee, Seung-Koo; Kim, Myung-Joon; Kim, Hyun Ji

2017-01-01

To investigate the quality of images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V), using pediatric head CT protocols. A phantom was scanned at decreasing 20% mA intervals using our standard pediatric head CT protocols. Each study was then reconstructed at 10% ASIR-V intervals. After the phantom study, we reduced mA by 10% in the protocol for <3-year-old patients and applied 30% ASIR-V and by 30% in the protocol for 3- to 15-year-old patients and applied 40% ASIR-V. Increasing the percentage of ASIR-V resulted in lower noise and higher contrast-to-noise ratio (CNR) and preserved spatial resolution in the phantom study. Compared to a conventional-protocol, reduced-dose protocol with ASIR-V achieved 12.8% to 34.0% of dose reduction and showed images of lower noise (9.22 vs. 10.73, P = 0.043) and higher CNR in different levels (centrum semiovale, 2.14 vs. 1.52, P = 0.003; basal ganglia, 1.46 vs. 1.07, P = 0.001; and cerebellum, 2.18 vs. 1.33, P < 0.001). Qualitative analysis showed higher gray-white matter differentiation and sharpness and preserved overall diagnostic quality in the images with ASIR-V. Use of ASIR-V allowed a 12.8% to 34.0% dose reduction in each age group with potential to improve image quality. (orig.)

Charged black holes in phantom cosmology

Energy Technology Data Exchange (ETDEWEB)

Jamil, Mubasher; Qadir, Asghar; Rashid, Muneer Ahmad [National University of Sciences and Technology, Center for Advanced Mathematics and Physics, Rawalpindi (Pakistan)

2008-11-15

In the classical relativistic regime, the accretion of phantom-like dark energy onto a stationary black hole reduces the mass of the black hole. We have investigated the accretion of phantom energy onto a stationary charged black hole and have determined the condition under which this accretion is possible. This condition restricts the mass-to-charge ratio in a narrow range. This condition also challenges the validity of the cosmic-censorship conjecture since a naked singularity is eventually produced due to accretion of phantom energy onto black hole. (orig.)

Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms.

Science.gov (United States)

Koivisto, Juha H; Wolff, Jan E; Kiljunen, Timo; Schulze, Dirk; Kortesniemi, Mika

2015-07-08

The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50-90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point-dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k = 2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low-dose limit. The sensitivity was 3.09 ± 0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was -8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD-comparable low-dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in

Characterization of MOSFET dosimeters for low‐dose measurements in maxillofacial anthropomorphic phantoms

Science.gov (United States)

Wolff, Jan E.; Kiljunen, Timo; Schulze, Dirk; Kortesniemi, Mika

2015-01-01

The aims of this study were to characterize reinforced metal‐oxide‐semiconductor field‐effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low‐dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50–90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point‐dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k=2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low‐dose limit. The sensitivity was 3.09±0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was −8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD‐comparable low‐dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However

Phantom evaluation of a cardiac SPECT/VCT system that uses a common set of solid-state detectors for both emission and transmission scans.

Science.gov (United States)

Bai, Chuanyong; Conwell, Richard; Kindem, Joel; Babla, Hetal; Gurley, Mike; De Los Santos, Romer; Old, Rex; Weatherhead, Randy; Arram, Samia; Maddahi, Jamshid

2010-06-01

We developed a cardiac SPECT system (X-ACT) with low dose volume CT transmission-based attenuation correction (AC). Three solid-state detectors are configured to form a triple-head system for emission scans and reconfigured to form a 69-cm field-of-view detector arc for transmission scans. A near mono-energetic transmission line source is produced from the collimated fluorescence x-ray emitted from a lead target when the target is illuminated by a narrow polychromatic x-ray beam from an x-ray tube. Transmission scans can be completed in 1 min with insignificant patient dose (deep dose equivalent used phantom studies to evaluate (1) the accuracy of the reconstructed attenuation maps, (2) the effect of AC on image uniformity, and (3) the effect of AC on defect contrast (DC). The phantoms we used included an ACR phantom, an anthropomorphic phantom with a uniform cardiac insert, and an anthropomorphic phantom with two defects in the cardiac insert. The reconstructed attenuation coefficient of water at 140 keV was .150 +/- .003/cm in the uniform region of the ACR phantom, .151 +/- .003/cm and .151 +/- .002/cm in the liver and cardiac regions of the anthropomorphic phantom. The ACR phantom images with AC showed correction of the bowing effect due to attenuation in the images without AC (NC). The 17-segment scores of the images of the uniform cardiac insert were 78.3 +/- 6.5 before and 87.9 +/- 3.3 after AC (average +/- standard deviation). The inferior-to-anterior wall ratio and the septal-to-lateral wall ratio were .99 and 1.16 before and 1.02 and 1.00 after AC. The DC of the two defects was .528 and .156 before and .628 and .173 after AC. The X-ACT system generated accurate attenuation maps with 1-minute transmission scans. AC improved image quality and uniformity over NC.

Computerized tomography in orthopaedics and traumatology

International Nuclear Information System (INIS)

Boettger, E.; Heckl, R.; Rehabilitations-Krankenhaus Langensteinbach, Karlsbad

1981-01-01

Computerized tomography in traumatology is the selected method for the indications mentioned, so that angiographic investigations are only necessary in exceptional cases. Computerized tomography is also better than other methods when diagnozing soft part tumours, however, angiography is still indicated preoperatively for individual cases. CT is only good as additional help to conventional diagnostics with bone tumours. The differential diagnosis cysts-tumour is possible using contrast medium injections. The frequently large soft part share of tumours is recognizable with osteolytic tumours so that a better irradiation and operation planning can be effected. Diseases in the spinal canal can only be assessed with reservation using modern equipment. Lumbar dislocations of the disk can mostly not be sufficiently determined. Perivertebral abscesses can be certainly detected using computerized tomography. This is particularly so for abscesses prior to calcification. (orig.) [de

Correction of head movements in positron emission tomography using point source tracking system: a simulation study.

Science.gov (United States)

Nazarparvar, Babak; Shamsaei, Mojtaba; Rajabi, Hossein

2012-01-01

The motion of the head during brain positron emission tomography (PET) acquisitions has been identified as a source of artifact in the reconstructed image. In this study, a method is described to develop an image-based motion correction technique for correcting the post-acquisition data without using external optical motion-tracking system such as POLARIS. In this technique, GATE has been used to simulate PET brain scan using point sources mounted around the head to accurately monitor the position of the head during the time frames. The measurement of head motion in each frame showed a transformation in the image frame matrix, resulting in a fully corrected data set. Using different kinds of phantoms and motions, the accuracy of the correction method is tested and its applicability to experimental studies is demonstrated as well.

Experimental phantom verification studies for simulations of light interactions with skin: liquid phantoms

CSIR Research Space (South Africa)

Karsten, A

2010-09-01

Full Text Available stream_source_info Karsten_2010_P.pdf.txt stream_content_type text/plain stream_size 5080 Content-Encoding UTF-8 stream_name Karsten_2010_P.pdf.txt Content-Type text/plain; charset=UTF-8 Experimental phantom verification... studies for simulations of light interactions with skin: Solid Phantoms Aletta E Karsten, A Singh Presented by: J E Smit National Laser Center CSIR South Africa akarsten@csir.co.za Slide 2 © CSIR 2009 www.csir.co.za Where...

Patients with severe head trauma who talk and then deteriorate

Energy Technology Data Exchange (ETDEWEB)

Isayama, Kazuo; Nakazawa, Shozo; Kobayashi, Shiro; Yokota, Hiroyuki; Ikeda, Yukio; Yajima, Kouzo; Yano, Masami; Otsuka, Toshibumi

1987-08-01

Patients with severe head trauma who talk and then deteriorate (or die) are analyzed by means of clinical signs, computerized tomography (CT), and outcome. The twelve severely head-injured patients had an initial verbal score on the Glasgow coma scale (GCS) of 3 or more and a GCS score of 9 or more. There were 8 male and 4 female patients. The ages of these patients ranged from 23 to 85 years (average age 60.9 years); nine of the patients were older than 60 years of age. An initial CT revealed subdural hematoma in 7 cases and traumatic subarachnoid hemorrhage in 8 cases. Serial CT could be used for 9 cases; delayed intracerebral hematoma was found in 5 patients, and acute cerebral swelling, in 3 patients. The elderly tended to have the hematoma, while the young tended to have acute cerebral swelling. Concerning the Glasgow outcome scale of cases of head trauma who talk and then deteriorate three months after trauma, there was moderate disability in 2 cases and a persistent vegetative state in one, while 9 had died.

Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program

International Nuclear Information System (INIS)

Pirayesh Islamian, J.; Bahreyni Toosi, M. T.; Momennezhad, M.; Naseri, Sh.; Ljungberg, M.

2012-01-01

Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and rods. The calculated contrasts of the rods were 0.774, 0.627, 0.575, 0.372, 0.191, and 0.132 for an experiment with the rods diameters of 31.8, 25.4, 19.1, 15.9, 12.7, and 9.5 mm, respectively. The calculated contrasts of simulated rods were 0.661, 0.527, 0.487, 0.400, 0.23, and 0.2 for cold rods and also 0.92, 0.91, 0.88, 0.81, 0.76, and 0.56 for hot rods. Reconstructed spatial tomographic resolution of both experiment and simulated SPECTs of the phantom obtained about 9.5 mm. An executable phantom file and an input phantom file were created for the SIMIND Monte Carlo program. This phantom may be used for simulated SPECT systems and would be ideal for verification of the simulated systems with real ones by comparing the results of quality control and image evaluation. It is also envisaged that this phantom could be used with a range of radionuclide doses in simulation situations such as cold, hot, and background uptakes for the assessment of detection characteristics when a new similar clinical SPECT procedure is being simulated.

Simulation of a Quality Control Jaszczak Phantom with SIMIND Monte Carlo and Adding the Phantom as an Accessory to the Program

Directory of Open Access Journals (Sweden)

Jalil Pirayesh Islamian

2012-03-01

Full Text Available Introduction Quality control is an important phenomenon in nuclear medicine imaging. A Jaszczak SPECT Phantom provides consistent performance information for any SPECT or PET system. This article describes the simulation of a Jaszczak phantom and creating an executable phantom file for comparing assessment of SPECT cameras using SIMIND Monte Carlo simulation program which is well-established for SPECT. Materials and Methods The simulation was based on a Deluxe model of Jaszczak Phantom with defined geometry. Quality control tests were provided together with initial imaging example and suggested use for the assessment of parameters such as spatial resolution, limits of lesion detection, and contrast comparing with a Siemens E.Cam SPECT system. Results The phantom simulation was verified by matching tomographic spatial resolution, image contrast, and also uniformity compared with the experiment SPECT of the phantom from filtered backprojection reconstructed images of the spheres and rods. The calculated contrasts of the rods were 0.774, 0.627, 0.575, 0.372, 0.191, and 0.132 for an experiment with the rods diameters of 31.8, 25.4, 19.1, 15.9, 12.7, and 9.5 mm, respectively. The calculated contrasts of simulated rods were 0.661, 0.527, 0.487, 0.400, 0.23, and 0.2 for cold rods and also 0.92, 0.91, 0.88, 0.81, 0.76, and 0.56 for hot rods. Reconstructed spatial tomographic resolution of both experiment and simulated SPECTs of the phantom obtained about 9.5 mm. An executable phantom file and an input phantom file were created for the SIMIND Monte Carlo program. Conclusion This phantom may be used for simulated SPECT systems and would be ideal for verification of the simulated systems with real ones by comparing the results of quality control and image evaluation. It is also envisaged that this phantom could be used with a range of radionuclide doses in simulation situations such as cold, hot, and background uptakes for the assessment of detection

Puzzles of dark energy in the Universe—phantom

International Nuclear Information System (INIS)

Dabrowski, Mariusz P

2015-01-01

This paper is devoted to some simple approach based on general physics tools to describe the physical properties of a hypothetical particle which can be the source of dark energy in the Universe known as phantom. Phantom is characterized by the fact that it possesses negative momentum and kinetic energy and that it gives dominant negative pressure which acts as antigravity. We consider a phantom harmonic oscillator in comparison to a standard harmonic oscillator. By using the first law of thermodynamics we explain why the energy density of the Universe grows when it is filled with phantom. We also show how the collision of phantom with a standard particle leads to extraction of energy from the former by the latter (i.e. from phantom to the standard) if their masses are different. The most striking of our conclusions is that the collision of phantom and standard particles of the same mass is impossible unless both of them are at rest and suddenly start moving with opposite velocities and kinetic energies. This effect is a classic analog of quantum mechanical particle pair creation in a strong electric field or physical vacuum. (paper)

Computerized Italian criticality guide, description and validation

International Nuclear Information System (INIS)

Carotenuto, M.; Landeyro, P.A.

1988-10-01

Our group is developing an 'expert system' for collecting engineering know-how on back-end nuclear plant design. An expert system is the most suitable software tool for our problem. During the analysis, the design process was divided into different branches. At each branch of the design process the Expert System relates a computerized design procedure. Any design procedure is composed of a set of design methods, together with their condition of application and reliability limits. In the framework of this expert system, the nuclear criticality safety analysis procedure was developed, in the form of a computerized criticality guide, attempting to reproduce the designer's normal 'reasoning' process. The criticality guide is composed of two parts: A computerized text, including theory, a description of the accidents occurred in the past and a description of the italian design experience; An interactive computer aided calculation module, containing a graphical facility for critical parameter curves. In the present report are presented the criticality guide (computerized Italian Criticality Guide) and its validation test. (author)

Computerized Italian criticality guide, description and validation

Energy Technology Data Exchange (ETDEWEB)

Carotenuto, M; Landeyro, P A [ENEA - Dipartimento Ciclo del Combustibile, Centro Ricerche Energia, Casaccia (Italy)

1988-10-15

Our group is developing an 'expert system' for collecting engineering know-how on back-end nuclear plant design. An expert system is the most suitable software tool for our problem. During the analysis, the design process was divided into different branches. At each branch of the design process the Expert System relates a computerized design procedure. Any design procedure is composed of a set of design methods, together with their condition of application and reliability limits. In the framework of this expert system, the nuclear criticality safety analysis procedure was developed, in the form of a computerized criticality guide, attempting to reproduce the designer's normal 'reasoning' process. The criticality guide is composed of two parts: A computerized text, including theory, a description of the accidents occurred in the past and a description of the italian design experience; An interactive computer aided calculation module, containing a graphical facility for critical parameter curves. In the present report are presented the criticality guide (computerized Italian Criticality Guide) and its validation test. (author)

A Movable Phantom Design for Quantitative Evaluation of Motion Correction Studies on High Resolution PET Scanners

DEFF Research Database (Denmark)

Olesen, Oline Vinter; Svarer, C.; Sibomana, M.

2010-01-01

maximization algorithm with modeling of the point spread function (3DOSEM-PSF), and they were corrected for motions based on external tracking information using the Polaris Vicra real-time stereo motion-tracking system. The new automatic, movable phantom has a robust design and is a potential quality......Head movements during brain imaging using high resolution positron emission tomography (PET) impair the image quality which, along with the improvement of the spatial resolution of PET scanners, in general, raises the importance of motion correction. Here, we present a new design for an automatic...

ICRU activity in the field of phantoms in diagnostic radiology

International Nuclear Information System (INIS)

Wambersie, A.

1992-01-01

The ICRU Report on 'Phantoms and Computational Models in Radiation Therapy, Diagnosis and Protection' is presented. Different types of phantoms may be defined. They may be broadly categorized according to their primary function: dosimetry, calibration and imaging. Within each functional category, there are 3 types or designs of phantoms: body phantoms (anthropomorphic), standard phantoms and reference phantoms (used in the definition and specification of certain radiation quantities). In radiological imaging, anthropomorphic body phantoms are used for measuring the absorbed dose distribution resulting from imaging procedures. Standard phantoms have simple reproducible geometry and are used for comparing measurements under standard conditions of exposure. Imaging phantoms are useful for evaluating a given imaging system; they contain different types of test pieces. The report contains a major section on human anatomy, from fetus to adult with the variations due to ethnic origin. Tolerance levels for the phantoms (composition, dimensions) are proposed and quality assurance programs are outlined. The report contains extensive appendices; human anatomical data and full specification of over 80 phantoms and computational models. ICRU Report 46 on 'Photon, electron, proton and neutron interaction data for body tissues' is closely related to the field of phantoms. It is a logical continuation on ICRU Report 44 (1989) on 'Tissue substitutes in radiation dosimetry and measurements' and contains the interaction data for more than 100 tissues, from fetal to adult, including some diseased tissues

Stratification of mammographic computerized analysis by BI-RADS categories

Energy Technology Data Exchange (ETDEWEB)

Lederman, Richard [Department of Radiology, Hadassah University Hospital, Ein Kerem, Jerusalem (Israel); Leichter, Isaac [Department of Electro-Optics, Jerusalem College of Technology, P.O.B. 16031, Jerusalem (Israel); Buchbinder, Shalom [Department of Radiology of The Montefiore Medical Center, The University Hospital for the Albert Einstein College of Medicine, Bronx, New York (United States); Novak, Boris [Department of Applied Mathematics, Jerusalem College of Technology, P.O.B. 16031, Jerusalem 91160 (Israel); Bamberger, Philippe [Department of Electronics, Jerusalem College of Technology, POB 16031, Jerusalem (Israel); Fields, Scott [Department of Radiology, Hadassah University Hospital, Mt. Scopus, Jerusalem (Israel)

2003-02-01

The Breast Imaging Reporting and Data System (BI-RADS) was implemented to standardize characterization of mammographic findings. The purpose of the present study was to evaluate in which BI-RADS categories the changes recommended by computerized mammographic analysis are most beneficial. Archival cases including, 170 masses (101 malignant, 69 benign) and 63 clusters of microcalcifications (MCs; 36 malignant, 27 benign), were evaluated retrospectively, using the BI-RADS categories, by several radiologists, blinded to the pathology results. A computerized system then automatically extracted from the digitized mammogram features characterizing mammographic lesions, which were used to classify the lesions. The results of the computerized classification scheme were compared, by receiver operating characteristics (ROC) analysis, to the conventional interpretation. In the ''low probability of malignancy group'' (excluding BI-RADS categories 4 and 5), computerized analysis improved the A{sub z}of the ROC curve significantly, from 0.57 to 0.89. In the ''high probability of malignancy group'' (mostly category 5) the computerized analysis yielded an ROC curve with an A {sub z}of 0.99. In the ''intermediate probability of malignancy group'' computerized analysis improved the A {sub z}significantly, from 0.66 for to 0.83. Pair-wise analysis showed that in the latter group the modifications resulting from computerized analysis were correct in 83% of cases. Computerized analysis has the ability to improve the performance of the radiologists exactly in the BI-RADS categories with the greatest difficulties in arriving at a correct diagnosis. It increased the performance significantly in the problematic group of ''intermediate probability of malignancy'' and pinpointed all the cases with missed cancers in the ''low probability'' group. (orig.)

Phantom with Pulsatile Arteries to Investigate the Influence of Blood Vessel Depth on Pulse Oximeter Signal Strength

OpenAIRE

Stuban, Norbert; Niwayama, Masatsugu; Santha, Hunor

2012-01-01

This paper describes a three-layer head phantom with artificial pulsating arteries at five different depths (1.2 mm, 3.7 mm, 6.8 mm, 9.6 mm and 11.8 mm). The structure enables formation of spatially and temporally varying tissue properties similar to those of living tissues. In our experiment, pressure pulses were generated in the arteries by an electronically controlled pump. The physical and optical parameters of the layers and the liquid in the artificial arteries were similar to those of ...

Use of SMT phototransistors for dosimetry in computerized tomography

International Nuclear Information System (INIS)

Magalhaes, C.M.S. de; Silva, J.O. da; Antonio Filho, J.; Santos, L.A.P. dos

2007-01-01

A dosimetry system using commercially available SMT (Surface-Mount Technology) phototransistors is evaluated for dose measurements in X-ray computed tomography. First, the phototransistors were characterized at the laboratory using a Pantak X-ray in the standard radiation quality RQR9 from IEC61267. The following tests were realized: energy dependence, response with dose rate and repetitiveness. The phototransistors yielded a real-time readout and a 6430 Sub-femto-ammeter Keithley was used to obtain their electrical current. This methodology allowed the correlating of their results with a standard ionisation chamber, a NE2571 ionization chamber coupled to a NE2670 electrometer that measured the applied dose at the detector position. After the characterization of the phototransistors, free-in-air and in head phantom dose measurements were carried out with the dosimetry system at the Hospital. Phototransistors were used to determine the dose profile measurements along the axis of rotation undergoing CT head examination. A Flip-Flop electrometer was used to obtain these measurements. The results indicated that the current values were reliable when compared with the results of doses of CT ionization chamber under the same conditions. The loss of radiation sensitivity, postirradiation, with time is not significant and the SMT phototransistor brings some features to CT dosimetry including high sensitivity, small size, real-time measurements and linearity. (author)

Influence of Manufacturing Processes on the Performance of Phantom Lungs

International Nuclear Information System (INIS)

Traub, Richard J.

2008-01-01

Chest counting is an important tool for estimating the radiation dose to individuals who have inhaled radioactive materials. Chest counting systems are calibrated by counting the activity in the lungs of phantoms where the activity in the phantom lungs is known. In the United States a commonly used calibration phantom was developed at the Lawrence Livermore National Laboratory and is referred to as the Livermore Torso Phantom. An important feature of this phantom is that the phantom lungs can be interchanged so that the counting system can be challenged by different combinations of radionuclides and activity. Phantom lungs are made from lung tissue substitutes whose constituents are foaming plastics and various adjuvants selected to make the lung tissue substitute similar to normal healthy lung tissue. Some of the properties of phantom lungs cannot be readily controlled by phantom lung manufacturers. Some, such as density, are a complex function of the manufacturing process, while others, such as elemental composition of the bulk plastic are controlled by the plastics manufacturer without input, or knowledge of the phantom manufacturer. Despite the fact that some of these items cannot be controlled, they can be measured and accounted for. This report describes how manufacturing processes can influence the performance of phantom lungs. It is proposed that a metric that describes the brightness of the lung be employed by the phantom lung manufacturer to determine how well the phantom lung approximates the characteristics of a human lung. For many purposes, the linear attenuation of the lung tissue substitute is an appropriate surrogate for the brightness

Qualitative evaluation of Chang method of attenuation correction on heart SPECT by using custom made heart phantom

International Nuclear Information System (INIS)

Takavar, A.; Eftekhari, M.; Beiki, D.; Saghari, M.; Mostaghim, N.; Sohrabi, M.

2003-01-01

SPECT detects γ- rays from administrated radiopharmaceutical within the patient body. γ-rays pass through different tissues before reaching detectors and are attenuated. Attenuation can cause artifacts; therefore different and used to minimize attenuation effects. In our study efficacy of Chang method was evaluated for attenuation purpose, using a custom made heart phantom. Due to different tissues surrounding heart, evaluation is not uniform more over activity distribution around heart is also non- uniform. In Chang method distribution of radioactivity and attenuation due to the surrounding tissue is considered uniform. Our phantom is a piece of plastic producing similar SPECT image as left ventricle. A dual head, ADAC system was used in our study. Images were taken by 180 d ig C (limited angle) and 360 d ig C (total rotation). Images are compared with and without attenuation correction. Our results indicate that Chang attenuation correction method is not capable of eliminating attenuation artifact completely in particular attenuation effects caused by breast

3D printed phantoms mimicking cortical bone for the assessment of ultrashort echo time magnetic resonance imaging.

Science.gov (United States)

Rai, Robba; Manton, David; Jameson, Michael G; Josan, Sonal; Barton, Michael B; Holloway, Lois C; Liney, Gary P

2018-02-01

bone. The multicompartment anthropomorphic head phantom was successfully produced and able to simulate realistic air cavities, bony anatomy, and soft tissue. Image quality assessment in the tibia phantom using the PETRA sequence showed the suitability of the resin to mimic human anatomy with high SNR and contrast making it suitable for tissue segmentation. A solid resin material, which can be 3D printed, has been found to have similar magnetic resonance signal properties to human cortical bone. Phantoms replicating skeletal anatomy were successfully produced using this resin and demonstrated their use for image quality and segmentation assessment of ultrashort echo time sequences. © 2017 American Association of Physicists in Medicine.

Mathematical phantoms for evaluation of age-specific internal dose

International Nuclear Information System (INIS)

Cristy, M.

1980-01-01

A series of mathematical phantoms representing children has been developed for use with photon transport codes. These phantoms, patterned after the Fisher-Snyder adult phantom, consist of simple mathematical expressions for the boundaries of the major organs and body sections. The location and shape of the organs are consistent with drawings depicting developmental anatomy, with the organ volumes assigned such that the masses at the various ages conform closely with the data presented in Reference Man. The explicit mathematical expressions for the various ages overcome the potential misrepresentation of organ sizes that occurred in phantoms derived from simple mathematical transformations of the adult phantom. Female breast tissue has been added to the phantoms, including the adult, now allowing assessment of doses to this organ

Study of Image Quality From CT Scanner Multi-Detector by using Americans College of Radiology (ACR) Phantom

Science.gov (United States)

Mulyadin; Dewang, Syamsir; Abdullah, Bualkar; Tahir, Dahlang

2018-03-01

In this study, the image quality of CT scan using phantom American College of Radiology (ACR) was determined. Scanning multidetector CT is used to know the image quality parameters by using a solid phantom containing four modules and primarily from materials that are equivalent to water. Each module is 4 cm in diameter and 20 cm in diameter. There is white alignment marks painted white to reflect the alignment laser and there are also “HEAD”, “FOOT”, and “TOP” marks on the phantom to help align. This test obtains CT images of each module according to the routine inspection protocol of the head. Acceptance of image quality obtained for determination: CT Number Accuracy (CTN), CT Number Uniformity and Noise, Linearity CT Number, Slice Technique, Low Contrast Resolution and High Contrast Resolution represent image quality parameters. In testing CT Number Accuracy (CTN), CT Uniform number and Noise are in the range of tolerable values allowed. In the test, Linearity CT Number obtained correlation value above 0.99 is the relationship between electron density and CT Number. In a low contrast resolution test, the smallest contrast groups are visible. In contrast, the high resolution is seen up to 7 lp/cm. The quality of GE CT Scan is very high, as all the image quality tests obtained are within the tolerance brackets of values permitted by the Nuclear Power Control Agency (BAPETEN). Image quality test is a way to get very important information about the accuracy of snoring result by using phantom ACR.

Effective radiation dose of ProMax 3D cone-beam computerized tomography scanner with different dental protocols.

Science.gov (United States)

Qu, Xing-min; Li, Gang; Ludlow, John B; Zhang, Zu-yan; Ma, Xu-chen

2010-12-01

The aim of this study was to compare effective doses resulting from different scan protocols for cone-beam computerized tomography (CBCT) using International Commission on Radiological Protection (ICRP) 1990 and 2007 calculations of dose. Average tissue-absorbed dose, equivalent dose, and effective dose for a ProMax 3D CBCT with different dental protocols were calculated using thermoluminescent dosimeter chips in a human equivalent phantom. Effective doses were derived using ICRP 1990 and the superseding 2007 recommendations. Effective doses (ICRP 2007) for default patient sizes from small to large ranged from 102 to 298 μSv. The coefficient of determination (R(2)) between tube current and effective dose (ICRP 2007) was 0.90. When scanning with lower resolution settings, the effective doses were reduced significantly (P radiation dose levels. Reduction in radiation dose can be achieved when using lower settings of exposure parameters. Copyright © 2010 Mosby, Inc. All rights reserved.

Application of phantom type compensating filter in tomography

Energy Technology Data Exchange (ETDEWEB)

Okayama, A.; Mukae, H.; Itoh, M. (Yamaguchi Univ., Ube (Japan). School of Medicine)

1981-01-01

We reported a new device of phantom type compensating filters for pulmonary hilar tomography with polytome U at the 35th annual meeting of the Japanese Society of Radiological Technology. This report is to show application of this compensated method to the head, the hip joint and the lower thoracic spine in tomography. Using the filters optimal density can be obtained in all area of aim part on a X-ray film, and thus makes to get more information. 1) In the head clear shadow of pars nasalis, sinus paranasales and sella turcica is obtained. Destruction or defect of bone contour is easily detected. It is also useful to differentiate the disorders and to determine the expansivity of the lesion. 2) In the hip joint this method has advantages over the ordinary method. There is a few misdiagnosis in trochanteric lesions such as tuberculosis or bone tumor, because of high density at the trochanteric region in ordinary method, but in this method optimal density can be obtained, and misdiagnosis is improved. Soft tissue is sharply visualized, indicating usefulness in diagnosis of existence of hematoma or abscess. 3) In the lower thoracic vertebra it is useful to diagnosis of the thoracic spondylosis, tuberculous spondylitis and compression fracture of the vertebral body, since optimal density of the spine can be obtained. It is also quite useful to detect small ossifications in the vertebral foraman in ossification of the flavum ligament.

Application of phantom type compensating filter in tomography

International Nuclear Information System (INIS)

Okayama, Akio; Mukae, Hideki; Itoh, Mitsuo

1981-01-01

We reported a new device of phantom type compensating filters for pulmonary hilar tomography with polytome U at the 35th annual meeting of the Japanese Society of Radiological Technology. This report is to show application of this compensated method to the head, the hip joint and the lower thoracic spine in tomography. Using the filters optimal density can be obtained in all area of aim part on a X-ray film, and thus makes to get more information. 1) In the head clear shadow of pars nasalis, sinus paranasales and sella turcica is obtained. Destruction or defect of bone contour is easily detected. It is also useful to differentiate the disorders and to determine the expansivity of the lesion. 2) In the hip joint this method has advantages over the ordinary method. There is a few misdiagnosis in trochanteric lesions such as tuberculosis or bone tumor, because of high density at the trochanteric region in ordinary method, but in this method optimal density can be obtained, and misdiagnosis is improved. Soft tissue is sharply visualized, indicating usefulness in diagnosis of existence of hematoma or abscess. 3) In the lower thoracic vertebra it is useful to diagnosis of the thoracic spondylosis, tuberculous spondylitis and compression fracture of the vertebral body, since optimal density of the spine can be obtained. It is also quite useful to detect small ossifications in the vertebral foraman in ossification of the flavum ligament. (author)

Usefulness of a functional tracheobronchial phantom for interventional procedure

International Nuclear Information System (INIS)

Kim, Tae Hyung; Lim, Cheong Hwan; Kim, Jeong Koo

2003-01-01

To evaluate usefulness of a functional tracheobronchial phantom for interventional procedure. The functional phantom was made as a actual size with human normal anatomy used silicone and a paper clay mold. A tracheobronchial-shape clay mold was placed inside a square box and liquid silicone was poured. After the silicone was formed, the clay was removed. We measured film density and tracheobronchial angle at the human, animal and phantom respectively. The film density of trachea part were 0.76 (± 0.011) in human, 0.97 (± 0.015) in animal, 0.45 (± 0.016) in phantom. The tracheobronchial bifurcation part measured 0.51 (± 0.006) in human, 0.65 (± 0.005) in animal, 0.65 (± 0.008) in phantom. The right bronchus part measured 0.14 (± 0.008) in human, 0.59 (± 0.014) in animal and 0.04 (± 0.007) in phantom. The left bronchus were 0.54 (± 0.004) in human, 0.54 (± 0.008) in animal and 0.08 (± 0.008) in phantom. At the stent part were 0.54 (± 0.004) in human, 0.59 (± 0.011) in animal and 0.04 (± 0.007) in phantom, respectively. The tracheobronchial angle of the left bronchus site were 42.6 (± 2.07).deg. in human, 43.4 (± 2.40).deg. in animal and 35 (± 2.00).deg. in phantom, respectively. The right bronchus site were 32.8 (± 2.77).deg. in human, 34.6 (± 1.94).deg. in animal and 50.2 (± 1.30).deg. in phantom, respectively. The phantom was useful for in-vitro testing of tracheobronchial interventional procedure, since it was easy to reproduce

Research on accounting transition from computerization to informationization

Directory of Open Access Journals (Sweden)

Shu Chen

2017-11-01

Full Text Available The application for computer technology, digitalization technology and network technology in the accounting field has promoted the development of accounting informationization. Accounting informationization is a product integrated with traditional accounting theory and modern information technology, which is an inevitable trend of continuous development of modern accounting. This paper discusses the basic concepts and characteristics of accounting computerization and informationization based on the normative research method and literature data method, analyzes the feasibility of accounting transition from computerization to informationization, and finally puts forward the specific approaches and ultimate goals of accounting transition from computerization to informationization.

TH-EF-BRB-08: Robotic Motion Compensation for Radiation Therapy: A 6DOF Phantom Study

Energy Technology Data Exchange (ETDEWEB)

Belcher, AH; Liu, X; Wiersma, R [The University of Chicago, Chicago, IL (United States)

2016-06-15

Purpose: The high accuracy of frame-based stereotactic radiosurgery (SRS), which uses a rigid frame fixed to the patient’s skull, is offset by potential drawbacks of poor patient compliance and clinical workflow restrictions. Recent research into frameless SRS has so far resulted in reduced accuracy. In this study, we investigate the use of a novel 6 degree-of-freedom (6DOF) robotic head motion cancellation system that continuously detects and compensates for patient head motions during a SRS delivery. This approach has the potential to reduce invasiveness while still achieving accuracies better or equal to traditional frame-based SRS. Methods: A 6DOF parallel kinematics robotics stage was constructed, and controlled using an inverse kinematics-based motion compensation algorithm. A 6DOF stereoscopic infrared (IR) marker tracking system was used to monitor real-time motions at sub-millimeter and sub-degree levels. A novel 6DOF calibration technique was first applied to properly orient the camera coordinate frame to match that of the LINAC and robotic control frames. Simulated head motions were measured by the system, and the robotic stage responded to these 6DOF motions automatically, returning the reflective marker coordinate frame to its original position. Results: After the motions were introduced to the system in the phantom-based study, the robotic stage automatically and rapidly returned the phantom to LINAC isocenter. When errors exceeded the compensation lower threshold of 0.25 mm or 0.25 degrees, the system registered the 6DOF error and generated a cancellation trajectory. The system responded in less than 0.5 seconds and returned all axes to less than 0.1 mm and 0.1 degree after the 6DOF compensation was performed. Conclusion: The 6DOF real-time motion cancellation system was found to be effective at compensating for translational and rotational motions to current SRS requirements. This system can improve frameless SRS by automatically returning

TH-EF-BRB-08: Robotic Motion Compensation for Radiation Therapy: A 6DOF Phantom Study

International Nuclear Information System (INIS)

Belcher, AH; Liu, X; Wiersma, R

2016-01-01

Purpose: The high accuracy of frame-based stereotactic radiosurgery (SRS), which uses a rigid frame fixed to the patient’s skull, is offset by potential drawbacks of poor patient compliance and clinical workflow restrictions. Recent research into frameless SRS has so far resulted in reduced accuracy. In this study, we investigate the use of a novel 6 degree-of-freedom (6DOF) robotic head motion cancellation system that continuously detects and compensates for patient head motions during a SRS delivery. This approach has the potential to reduce invasiveness while still achieving accuracies better or equal to traditional frame-based SRS. Methods: A 6DOF parallel kinematics robotics stage was constructed, and controlled using an inverse kinematics-based motion compensation algorithm. A 6DOF stereoscopic infrared (IR) marker tracking system was used to monitor real-time motions at sub-millimeter and sub-degree levels. A novel 6DOF calibration technique was first applied to properly orient the camera coordinate frame to match that of the LINAC and robotic control frames. Simulated head motions were measured by the system, and the robotic stage responded to these 6DOF motions automatically, returning the reflective marker coordinate frame to its original position. Results: After the motions were introduced to the system in the phantom-based study, the robotic stage automatically and rapidly returned the phantom to LINAC isocenter. When errors exceeded the compensation lower threshold of 0.25 mm or 0.25 degrees, the system registered the 6DOF error and generated a cancellation trajectory. The system responded in less than 0.5 seconds and returned all axes to less than 0.1 mm and 0.1 degree after the 6DOF compensation was performed. Conclusion: The 6DOF real-time motion cancellation system was found to be effective at compensating for translational and rotational motions to current SRS requirements. This system can improve frameless SRS by automatically returning

The use of adaptive statistical iterative reconstruction in pediatric head CT: a feasibility study.

Science.gov (United States)

Vorona, G A; Zuccoli, G; Sutcavage, T; Clayton, B L; Ceschin, R C; Panigrahy, A

2013-01-01

Iterative reconstruction techniques facilitate CT dose reduction; though to our knowledge, no group has explored using iterative reconstruction with pediatric head CT. Our purpose was to perform a feasibility study to assess the use of ASIR in a small group of pediatric patients undergoing head CT. An Alderson-Rando head phantom was scanned at decreasing 10% mA intervals relative to our standard protocol, and each study was then reconstructed at 10% ASIR intervals. An intracranial region of interest was consistently placed to estimate noise. Our ventriculoperitoneal shunt CT protocol was subsequently modified, and patients were scanned at 20% ASIR with approximately 20% mA reductions. ASIR studies were anonymously compared with older non-ASIR studies from the same patients by 2 attending pediatric neuroradiologists for diagnostic utility, sharpness, noise, and artifacts. The phantom study demonstrated similar noise at 100% mA/0% ASIR (3.9) and 80% mA/20% ASIR (3.7). Twelve pediatric patients were scanned at reduced dose at 20% ASIR. The average CTDI(vol) and DLP values of the 20% ASIR studies were 22.4 mGy and 338.4 mGy-cm, and for the non-ASIR studies, they were 28.8 mGy and 444.5 mGy-cm, representing statistically significant decreases in the CTDI(vol) (22.1%, P = .00007) and DLP (23.9%, P = .0005) values. There were no significant differences between the ASIR studies and non-ASIR studies with respect to diagnostic acceptability, sharpness, noise, or artifacts. Our findings suggest that 20% ASIR can provide approximately 22% dose reduction in pediatric head CT without affecting image quality.

Cranial computerized tomography in children suffering from acute leukemia

International Nuclear Information System (INIS)

Metz, O.

1981-01-01

Cranial computerized (axial) tomography permits a more complete neurologic supervision of children with acute leukemia and a better knowledge of the frequency and varieties of cerebral complications in leukemia. Endocranial complications in acute leukemia are essentially infiltrative, hemorrhagic, infectious or iatrogenic. Cranial computerized tomography can demonstrate cerebral changes in meningeal leukemia, hemorrhages, calcifications, brain atrophy or leukencephalopathy. The preliminary results of cranial computerized tomography in childhood leukemia suggest that the iatrogenic main lesion of the brain due to combined radiation-chemotherapy is atrophy whereas that of the intrathecal cytostatic therapy is demyelination. Accurate diagnostics and control of possible cerebral complications in therapy of leukemia is essentially for appropriate therapeutic management. For that cranial computerized tomography is the best method to a effective supervision of the brain. (author)

Peculiarities of X-ray appearances of aseptic necrosis of head of the femur in adults and children and their connection with bio mechanical factors

International Nuclear Information System (INIS)

Suslova, O.Ya.; Shargorodskij, C.S.; Antipova, A.A.; Naumenko, N.A.; Kresnyj, D.I.

1987-01-01

260 patients aged from 3 to 56 with aseptic necrosis of head of the femur are examined. Experimental biomechanical simulation of load conditions on femur head and cotyloid cavity was carried out at phantom devices using tensiometry, ichnographic and polarization-optical methods. Peculiarities of X-ray appearances of asceptic necrosis with respect to age are studied. A definite connection between asceptic necrosis and biomechanical factors is established

Evaluation of the Delta4 phantom for IMRT and VMAT verification

International Nuclear Information System (INIS)

Bedford, James L; Lee, Young K; Wai, Philip; South, Christopher P; Warrington, Alan P

2009-01-01

The Delta 4 diode array phantom (Scandidos, Uppsala, Sweden) was evaluated for verification of segmental intensity-modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) on an Elekta linear accelerator (Crawley UK). The device was tested for angular sensitivity by irradiating it from 36 different gantry angles, and the responses of the device to various step-and-shoot segment doses and dose rates were evaluated using an ionization chamber as a comparison. The phantom was then compared with ionization chamber and film results for two prostate and pelvic nodes IMRT plans, two head and neck IMRT plans and two lung VMAT plans. These plans were calculated using Pinnacle 3 (Philips Radiation Oncology Systems, Madison, WI). The uniformity of angular response was better than 0.5% over the range of gantry angles. The uniformity of response of the Delta 4 to different segment monitor units and dose rates was better than 0.5%. The assessment of the IMRT and VMAT plans showed that the Delta 4 measured a dose within 2.5% of the ionization chamber, and compared to film recorded a slightly larger region (range -2% to +7%) agreeing with the planned dose to within 3% and 3 mm. The Delta 4 is a complex device and requires careful benchmarking, but following the successful completion of these measurements, the Delta 4 has been introduced into clinical use. (note)

Receiver operating characteristic analysis and its potential role in evaluating the effect of head movement in PET of the brain

International Nuclear Information System (INIS)

Patterson, H.; Clarke, G.H.; Lombardo, P.; McKay, W.J.; Austin and Repatriation Medical Centre, Heidelberg, VIC

1999-01-01

Full text: We outline an example of receiver operating characteristic (ROC) analysis in the assessment of image quality. ROC analysis is a measure of image quality that accounts for the consequences of the decision and the role of the observer. Kim and Haynie (Nuclear Diagnostic Imaging: Practical Clinical Applications. Melbourne: Macmillan, 1987) describe ROC analysis as an 'objective approach to the evaluation of diagnostic decision making'. ROC analysis is an ideal technique for evaluating images of a Hoffman brain phantom obtained using positron emission tomography. Images have been acquired with the phantom in different positions. The position of the phantom and the time the phantom remained in each position was based on the measurements of head movement during simulated brain imaging (Patterson et al., Technologists Symposium, ANZSNM, 1998). This study was undertaken to explore the potential of ROC analysis in determining the effect of movement on the ability to detect lesions of various sizes

Phantom Pain

Science.gov (United States)

... Because this is yet another version of tangled sensory wires, the result can be pain. A number of other factors are believed to contribute to phantom pain, including damaged nerve endings, scar tissue at the site of the amputation and the physical memory of pre-amputation pain in the affected area. ...

Computerized adaptive testing--ready for ambulatory monitoring?

DEFF Research Database (Denmark)

Rose, Matthias; Bjørner, Jakob; Fischer, Felix

2012-01-01

Computerized adaptive tests (CATs) have abundant theoretical advantages over established static instruments, which could improve ambulatory monitoring of patient-reported outcomes (PROs). However, an empirical demonstration of their practical benefits is warranted.......Computerized adaptive tests (CATs) have abundant theoretical advantages over established static instruments, which could improve ambulatory monitoring of patient-reported outcomes (PROs). However, an empirical demonstration of their practical benefits is warranted....

Comparison of different phantoms used in digital diagnostic imaging

Energy Technology Data Exchange (ETDEWEB)

Bor, Dogan, E-mail: bor@eng.ankara.edu.tr [Ankara University, Faculty of Engineering, Department of Engineering Physics. Tandogan, 06100 Ankara (Turkey); Unal, Elif, E-mail: elf.unall@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey); Uslu, Anil, E-mail: m.aniluslu@gmail.com [Radat Dosimetry Laboratory Services, 06830, Golbasi, Ankara (Turkey)

2015-09-21

The organs of extremity, chest, skull and lumbar were physically simulated using uniform PMMA slabs with different thicknesses alone and using these slabs together with aluminum plates and air gaps (ANSI Phantoms). The variation of entrance surface air kerma and scatter fraction with X-ray beam qualities was investigated for these phantoms and the results were compared with those measured from anthropomorphic phantoms. A flat panel digital radiographic system was used for all the experiments. Considerable variations of entrance surface air kermas were found for the same organs of different designs, and highest doses were measured for the PMMA slabs. A low contrast test tool and a contrast detail test object (CDRAD) were used together with each organ simulation of PMMA slabs and ANSI phantoms in order to test the clinical image qualities. Digital images of these phantom combinations and anthropomorphic phantoms were acquired in raw and clinically processed formats. Variation of image quality with kVp and post processing was evaluated using the numerical metrics of these test tools and measured contrast values from the anthropomorphic phantoms. Our results indicated that design of some phantoms may not be efficient enough to reveal the expected performance of the post processing algorithms.

A practical head tracking system for motion correction in neurological SPECT and PET

International Nuclear Information System (INIS)

Fulton, R.R.; Eberl, S.; Meikle, S.; Hutton, B.F.; Braun, M.

1998-01-01

Full text: Patient motion during data acquisition can degrade the quality of SPECT and PET images. Techniques for motion correction in neurological studies in both modalities based on continuous monitoring of head position have been proposed. However difficulties in developing suitable head tracking systems have so far impeded clinical implementations. We have developed a head tracking system based on the mechanical ADL-1 tracker (Shooting Star Technology, Rosedale, Canada) on a Trionix triple-head SPECT camera A software driver running on a SUN Sparc host computer communicates with the tracker over a serial line providing up to 300 updates per second with angular and positional resolutions of 0.05 degrees and 0.2 mm respectively. The SUN Sparc workstation which acquires the SPECT study also communicates with the tracker, eliminating synchronisation problems. For motion correction, the motion parameters provided by the tracker within its own coordinate system must be converted to the camera's coordinate system. The conversion requires knowledge of the rotational relationships between the two coordinate systems and the displacement of their origins, both of which are determined from a calibration procedure. The tracker has been tested under clinical SPECT imaging conditions with a 3D Hoffman brain phantom. Multiple SPECT acquisitions were performed. After each acquisition the phantom was moved to a new position and orientation. Motion parameters reported by the tracker for each applied movement were compared with those obtained by applying an automated image registration program to the sequential reconstructed studies. Maximum differences were < 0.5 degrees and < 2mm, within the expected errors of the registration procedure. We conclude that this tracking system will be suitable for clinical evaluation of motion correction in SPECT and PET

Computerized tomography in evaluation of decreased acetabular and femoral anteversion

International Nuclear Information System (INIS)

Toennis, D.; Skamel, H.J.

2003-01-01

Computerized tomography has received a new importance. It has been shown that decreased anteversion of femur and acetabulum, when both have decreased angles, are causing pain and osteoarthritis of the hip joint. Operative treatment should be performed before osteoarthritis develops. Exact measurements therefore are necessary. The investigation should be performed in prone position to have the pelvis lying in a defined and normal position. Femoral torsion is measured between the transverse axis of the knee and the femoral neck. The transverse axis for measurement of the femoral anteversion is defined by a rectangular line to the sagittal plane. For evaluation of the femoral anteversion in total the angle of the condyles has to be added to the femoral neck angle when the knee is found in internal rotation. Acetabular anteversion should be measured at the level where the femoral head is still in full contact and congruence with the anterior margin of the acetabulum. (orig.) [de

Computerized data base of the fundamental constants of nature

International Nuclear Information System (INIS)

Henry, E.A.; Hampel, V.E.

1975-01-01

Fifty-seven fundamental constants of nature were computerized from the up-to-date evaluations of E. R. Cohen and B. N. Taylor. The constants are annotated with regard to symbol, value, uncertainty, and scaling factor. This computerization is part of the scientific data base project of the Information Research Group at Lawrence Livermore Laboratory. The MASTER CONTROL data base management system is used. The computerized fundamental constants can be requested from the ERDA Computer Program Exchange and Information Center of the Argonne National Laboratory or from the National Technical Information Service of the U. S. Department of Commerce. This is the first of a series of releases on preparation of computerized scientific and technological data banks. The next release is a data bank of conversion factors for different units of measurements. 3 figures

Head CT: Image quality improvement with ASIR-V using a reduced radiation dose protocol for children.

Science.gov (United States)

Kim, Hyun Gi; Lee, Ho-Joon; Lee, Seung-Koo; Kim, Hyun Ji; Kim, Myung-Joon

2017-09-01

To investigate the quality of images reconstructed with adaptive statistical iterative reconstruction V (ASIR-V), using pediatric head CT protocols. A phantom was scanned at decreasing 20% mA intervals using our standard pediatric head CT protocols. Each study was then reconstructed at 10% ASIR-V intervals. After the phantom study, we reduced mA by 10% in the protocol for ASIR-V and by 30% in the protocol for 3- to 15-year-old patients and applied 40% ASIR-V. Increasing the percentage of ASIR-V resulted in lower noise and higher contrast-to-noise ratio (CNR) and preserved spatial resolution in the phantom study. Compared to a conventional-protocol, reduced-dose protocol with ASIR-V achieved 12.8% to 34.0% of dose reduction and showed images of lower noise (9.22 vs. 10.73, P = 0.043) and higher CNR in different levels (centrum semiovale, 2.14 vs. 1.52, P = 0.003; basal ganglia, 1.46 vs. 1.07, P = 0.001; and cerebellum, 2.18 vs. 1.33, P ASIR-V. Use of ASIR-V allowed a 12.8% to 34.0% dose reduction in each age group with potential to improve image quality. • It is possible to reduce radiation dose and improve image quality with ASIR-V. • We improved noise and CNR and decreased radiation dose. • Sharpness improved with ASIR-V. • Total radiation dose was decreased by 12.8% to 34.0%.

In vivo dosimetry using thermoluminescent detector in cancer therapy of head and neck

International Nuclear Information System (INIS)

Viegas, Claudio C.B.; Batista, D.V.; Campos, A.M.; Lopes, R.T.

2002-01-01

The viability and implementation of a routine in vivo dosimetry, using thermoluminescent dosemeters (TLD), at the radiotherapy section of the National Institute of Cancer in Brazil, in the case of head and neck treatment is shown. In order to reach that aim, the characteristics of the response of the LiF:Mg;Ti (TLD-100) thermoluminescent detectors in powder form were determined. The performed of this detector for in vivo dosimetry was testes using an RANDO Alderson anthropomorphic phantom and, once their adequability proved for the kind of measurements proposed , it was used for dose assessment in the case of tumour treatments in the head and neck regions, for Cobalt-60 irradiations. (author)