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Sample records for absorbed glandular dose

  1. Calculation of absorbed glandular dose using a Fortran program based on Monte Carlo X-ray spectra in mammography

    International Nuclear Information System (INIS)

    Average glandular dose calculation in mammography with Mo-Rh target-filter and dose calculation for different situations is accurate and fast. Material and Methods: In this research, first of all, x-ray spectra of a Mo target bombarded by a 28 keV electron beam with and without a Rh filter were calculated using the MCNP code. Then, we used the Sobol-Wu parameters to write a FORTRAN code to calculate average glandular dose. Results: Average glandular dose variation was calculated against the voltage of the mammographic x-ray tube for d = 5 cm, HVL= 0.35 mm Al, and different value of g. Also, the results related to average glandular absorbed dose variation per unit roentgen radiation against the glandular fraction of breast tissue for kV = 28 and HVL = 0.400 mmAl and different values of d are presented. Finally, average glandular dose against d for g = 60% and three values of kV (23, 27,35 kV) with corresponding HVLs have been calculated. Discussion and Conclusion: The absorbed dose computational program is accurate, complete, fast and user friendly. This program can be used for optimization of exposure dose in mammography. Also, the results of this research are in good agreement with the computational results of others.

  2. Media glandular dose in mammography

    International Nuclear Information System (INIS)

    The objective of this work was to determine the media glandular dose of the patients group who most frequently are exposed at mammographic studies in the General Hospital of Zone No. 1 of IMSS in Zacatecas, later to compare this dose with the value that establishes the Mexican Official Standard and to know risk-benefit that a patient is exposed when it is realized studies of this nature. This with the purpose of to know if the patients who are realized this type of studies are exhibited to irradiations of unnecessary way. In order to obtain the media glandular dose, first it was choose the age group of feminine population that is predominant to this suffering. Of the classification of the age group it was determine the frequency of each thickness of mamma, and on the basis of the thickness of the compressed mamma the conditions were registered with it radiates the patient. When having the age and compressed mamma thickness of patient and the voltage, current, anode/filter that uses the mammography equipment for to radiate it was calculated the media glandular dose. The media glandular dose was calculated using two algorithms proposed in literature and thermoluminescent dosemeters. For the case of the thermoluminescent dosemeters were used two phantoms. In this study was detected that the limits, with that they radiate the patients who are exposed at mammographic studies it is by underneath of 3 mGy. Finally, it was detected that the Mexican Official Standard lacks of at the Mexican Official Standard lacks of elements to offer radiological limits for the mammography area, because in this standard they are excluded the radiological limits for anode and filter of Mo/Rh and Rh/Rh. To know the dose applying these anodes and filters is of extreme importance because 85% of the population that is exposed to this studies type was radiated with anode and filter of Mo/Rh and Rh/Rh. (Author)

  3. Mammographic glandular dose: Definition of ''tissue at highest risk''

    International Nuclear Information System (INIS)

    In 1979, various authors published data on ''mean glandular dose.'' In their study, the glandular dose was averaged across the entire breast parenchyma. But most breast cancers occur in glandular tissues situated centrally and laterally, that is, about 1-2 cm below the skin entrance of the beam. The authors calculated the mean dosage to this ''tissue at highest risk,'' assuming compressed fat and skin thickness of 0.25 cm, and actual compressed breast thickness. The data shows a substantial increase in absorbed dose in this tissue at highest risk. The potential effect on mammographic planning, patient education, and dose risk calculations are discussed

  4. Evaluation of depth dose and glandular dose for digital mammography

    International Nuclear Information System (INIS)

    The purpose of this study is to evaluate the depth dose and mean glandular dose for the latest digital mammography. Depth doses were measured using GR-200F thin-film TLDs comprising LiF:Mg,Cu,P over three kinds of composition of mammographic phantom (glandular/fat: 30/70; 50/50; 70/30) under automatic exposure control by a digital mammographic unit (Novation DR, Siemens). Mean glandular doses were derived from entrance surface doses which were measured according to the Mammography Quality Control Manual of American College of Radiology. Two types of mean glandular dose calculation system were used and compared in this study. The depth dose could be established with thin-film TLDs and fitted by the model considered the primary and scatter radiation. The 50% depth dose falls at a depth of between 0.62 and 1.71 cm, which can represent the beam quality of X-ray spectra. The MGD calculated by Dance's method is 9-21% higher than that by Wu's method. Therefore, the difference should be considered by the Taiwan's regulation for Novation DR digital mammographic units.

  5. FORTRAN Code for Glandular Dose Calculation in Mammography Using Sobol-Wu Parameters

    Directory of Open Access Journals (Sweden)

    Mowlavi A A

    2007-07-01

    Full Text Available Background: Accurate computation of the radiation dose to the breast is essential to mammography. Various the thicknesses of breast, the composition of the breast tissue and other variables affect the optimal breast dose. Furthermore, the glandular fraction, which refers to the composition of the breasts, as partitioned between radiation-sensitive glandular tissue and the adipose tissue, also has an effect on this calculation. Fatty or fibrous breasts would have a lower value for the glandular fraction than dense breasts. Breast tissue composed of half glandular and half adipose tissue would have a glandular fraction in between that of fatty and dense breasts. Therefore, the use of a computational code for average glandular dose calculation in mammography is a more effective means of estimating the dose of radiation, and is accurate and fast. Methods: In the present work, the Sobol-Wu beam quality parameters are used to write a FORTRAN code for glandular dose calculation in molybdenum anode-molybdenum filter (Mo-Mo, molybdenum anode-rhodium filter (Mo-Rh and rhodium anode-rhodium filter (Rh-Rh target-filter combinations in mammograms. The input parameters of code are: tube voltage in kV, half-value layer (HVL of the incident x-ray spectrum in mm, breast thickness in cm (d, and glandular tissue fraction (g. Results: The average glandular dose (AGD variation against the voltage of the mammogram X-ray tube for d = 4 cm, HVL = 0.34 mm Al and g=0.5 for the three filter-target combinations, as well as its variation against the glandular fraction of breast tissue for kV=25, HVL=0.34, and d=4 cm has been calculated. The results related to the average glandular absorbed dose variation against HVL for kV = 28, d=4 cm and g= 0.6 are also presented. The results of this code are in good agreement with those previously reported in the literature. Conclusion: The code developed in this study calculates the glandular dose quickly, and it is complete and accurate. Furthermore, it is user friendly and useful for dose optimizing in mammography imaging.

  6. Average glandular dose in patients submitted to mammography exams

    International Nuclear Information System (INIS)

    Doses in mammography should be maintained as low as possible, however without reducing the standards of image quality necessary for an early detection of breast cancer. As the breast is composed of tissues with very soft composition and densities, detection of small changes in the normal anatomical structures that may be associated with breast cancer becomes more difficult. In order to achieve the standards of resolution and contrast for mammography, quality and intensity of the X- ray beam, breast positioning and compression, film-screen system, and the film processing must be in optimal operational conditions. This study aims at evaluating the average glandular dose in patients undergoing routine tests in a mammography unit in the city of Belo Horizonte. Patient image analysis was done by a radiologist who took into account 10 evaluation criteria for each CC and MLO incidences. The estimation of each patient's glandular dose and the radiographic technique parameters (kV and mA.s) as well as the thickness of the compressed breast were recorded. European image quality criteria were adopted by the radiologist in order to make the image acceptable for diagnostic purposes. For breast densities of 50%/50%, 70%/30%, 30%/70%, adipose and glandular tissues and the incident air-kerma were measured and the glandular dose calculated taking into account the X-ray output during the test. In the study carried out with 63 patients, the mean glandular dose varied from 30% incidence of CC to MLO. (author)

  7. Dosimetric evaluation of average glandular absorption radiation dose in mammography

    International Nuclear Information System (INIS)

    To evaluate the average glandular absorption radiation dose(AGARD) that results from tube voltage, target/filter material of the X-ray tube, enterance skin exposure, breast thickness and patterns in routine mammography. After obtaining craniocaudal views of left breast of 114 women, entrance skin exposure was measured by dosimetry. Under identical conditions of tube voltage and target/filter material of the X-ray tube, we obtained half value layer (HVL) and also calculated exposure-to-absorbed dose conversion factor (DgN) by Wu's methods. AGARD was calculated by entrance skin exposure multiplied by exposure-to-absorbed dose conversion factor. We analyzed AGARDs according to tube voltage, target/filter material, breast thickness and pattern using ANOVA method of the SPSS statistical packages. Breast patterns were divided into 4 groups such as DY (n=72), P1 (n=1), P2 (n=10), and N1 (n=31), respectively. Their AGARDs were 161.5, 180, 172.8, and 195.2 mrad respectively and showed no significant difference among groups. When divided by breast thickness into three groups, namely below 3 cm, 3 cm to 4.5 cm, and above 4.5 cm, the AGARD of each group was 178.3, 178.1, and 112.4 mrad respectively and the last one was significantly low. Concerning the effect of tube voltages, AGARDs gradually decreased by increasing kVp. Furthermore, AGARD was lower when rhodium (Rh) rather than when molybdenum (Mo) was used as filter/target materials. There was no difference in AGARDaterials. There was no difference in AGARDs by breast pattern. As more increasing KvP or using Rh/Rh as the target/filter material of the X-ray tube, we reduced AGARD for the patient with dense or thick breasts

  8. Average glandular dose in patients submitted to mammographic examinations

    International Nuclear Information System (INIS)

    Doses in mammography should be maintained as low as possible without reducing the high image quality needed to the early detection of the breast cancer. As the breast is composed of tissues with very soft composition and densities, it increases the difficulty to detect small changes in the normal anatomical structures that may be associated with breast cancer. To achieve the standards of resolution and contrast for mammography, the quality and intensity of the X-ray beam, the breast positioning and compression, the film screen system, and the film processing must be in optimal operational conditions. This study intended to evaluate the mean glandular dose of patients undergoing routine exams in one mammography unit. Patient image analyses were done by a radiologist doctor who took into account 10 evaluation criteria for each CC and MLO incidences. For estimating each patient glandular dose the radiographic technique parameters (kV and mAs) and the thickness of the compressed breast were recorded. European image quality criteria were adopted by the radiologist doctor to accept the image for diagnostic purpose. For breast densities of 50% adipose and 50% glandular tissues the incident air-kerma was measured and the glandular dose calculated considering the x-ray output during the exam. In the study of 50 patients the mean glandular dose varied from 0.90 to 3.27 mGy with a mean value of 1.98 mGy for CC incidences. For MLO incidences the mean glandular doses ranged from 0.97 to 3.98 mGy and a mean value of 2.60 mGy. (author)

  9. Mean glandular dose for different angles of the X-ray tube using different glandularity phantoms

    Science.gov (United States)

    Oliveira, B. B.; Nogueira, M. S.

    2014-02-01

    Digital breast tomosynthesis (DBT) is a three-dimensional radiographic technique that is beginning to be used as part of an imaging diagnostic program in some of Brazilian clinical practices. Studies are needed to evaluate the performance and to determine the radiation dose of patients that are undergoing this new procedure. The aim of this work is to present results of the mean glandular dose (DG) for different angles of the X-ray tube using a computed radiography (CR) mammography unit and different glandularity standard breast phantoms. DG values were derived from measurements of the incident air kerma (Ki) and tabulated conversion coefficients that are dependent on the half-value layer (HVL) of the X-ray spectrum. Irradiations were done in a 3000 Nova model Siemens MAMMOMAT mammography unit with the X-ray tube angle ranging from -30° to 30°. The protocol with 28 kV was used for Mo/Mo combination. The distance between focus and the 90×5-6 M model Radcal ionization chamber was 60.5 cm and the tube loading (PIt) used was 50 mA s. Exposures were done for DG determination using the semi-automatic exposure control mode and the 45 mm Computerized Imaging Reference Systems, Inc phantoms which approximately simulate a standard breast with glandularities of 0, 30, 50, 70 and 100%. DG values ranged from 1.3±0.1 to 7.6±0.7 mGy. The results are in according to the reference level of 3 mGy established by the International Basic Safety Standards (BSS115) to breast with 45 mm of thickness, 50% of glandularity and for the X-ray tube positioned in 0°. The results showed that DG increases with the glandularity and with the rotation of the X-ray tube. This work contributes to begin in Brazil the dosimetry in DBT equipments using different protocols and target/filter combinations.

  10. Evaluation of glandular dose in conventional and digital mammography systems

    International Nuclear Information System (INIS)

    A survey was conducted to estimate the average glandular dose (Dg) for patients undergoing mammography and to report the distribution of incident air kerma (Ki), patient age, compressed breast thickness and glandular tissue content. From 1183 cranio caudal mammograms clinical data were collected and doses were measured. The survey data included mammograms from six mammography equipment: two screen/film units (SFM), two computed radiography units (CR) and two full-field digital (DR). Mean value for patient age and compressed breast thickness were 57 +-12 y and 5.4 +-1.4 cm, respectively. To investigate the importance of technical characteristics of three different mammography systems and breast glandularity, Ki and Dg were measured for individual breast of 392 patients from the original sample with compressed breast thickness in the range of 5.5 cm to 6.5 cm using tissue-equivalent phantoms of different glandularities manufactured in this study to mimic both the attenuation and the density of breast tissues. Mean Ki value was 10.0 +-3.6 mGy for SFM systems, 12.0 +-3.6 mGy for CR systems and 4.9 +-1.3 mGy for DR systems. Mean Dg value was 1.4 +-0.5 mGy for S/F systems, 1.7 +-0.5 mGy for CR systems and 0.9 +-0.2 mGy for D R systems. Statistical analysis for differences in mean values of Ki and Dg between mammography systems showed significant effect of their technical characteristics (p i and Dg, it was observed statistically significant differences between the group of patients with 0 to 50% glandularity and the group of patients with 50 to 100% glandularity. (author)

  11. Mean glandular dose in a breast screening programme

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    Galvan, H. A.; Perez-Badillo, M. P.; Villasenor, Y. [Instituto Nacional de Cancerologia, Av. San Fernando No. 22, Col Seccion XVI, Mexico, D. F., C. P. 14080 (Mexico)

    2012-10-23

    Breast density has an important role in early detection of breast cancer, because has been reported the strong association between breast density and invasive breast cancer risk. Mammography is the gold standard to early detection of breast cancer, despite of this require ionizing radiation that may increase radio-induced cancer risk. This maybe limited with a quality control programme of mammographic units, with the main goal of achieving high quality images with low radiation dose. International Atomic Energy Agency (IAEA) published in 2011 the {sup Q}uality assurance programme for digital mammography{sup ,} where glandular tissue quantity is an important parameter to compute mean glandular dose (MGD), which is necessary to reduce its associated risk. In this work we show the first results in our country applying this protocol and studying breast density in a small group. MGD complies with national and IAEA dose limits.

  12. Mean glandular dose in a breast screening programme

    Science.gov (United States)

    Galván, H. A.; Pérez-Badillo, M. P.; Villaseñor, Y.

    2012-10-01

    Breast density has an important role in early detection of breast cancer, because has been reported the strong association between breast density and invasive breast cancer risk. Mammography is the gold standard to early detection of breast cancer, despite of this require ionizing radiation that may increase radio-induced cancer risk. This maybe limited with a quality control programme of mammographic units, with the main goal of achieving high quality images with low radiation dose. International Atomic Energy Agency (IAEA) published in 2011 the "Quality assurance programme for digital mammography", where glandular tissue quantity is an important parameter to compute mean glandular dose (MGD), which is necessary to reduce its associated risk. In this work we show the first results in our country applying this protocol and studying breast density in a small group. MGD complies with national and IAEA dose limits.

  13. Development of an excel spreadsheet formean glandular dose in mammography

    International Nuclear Information System (INIS)

    The purpose of this study was to develop an Excel spreadsheet to calculate mean glandular dose (Dg) in mammography using clinical exposure data. Dg can be calculated as the product of incident air kerma (Ka) and DgN (i.e., Dg=Ka x DgN). According to the method of Klein et al (Phys Med Biol 1997; 42: 651-671), Ka was measured at the entrance surface with an ionization dosimeter. Normalized glandular dose (DgN) coefficients, taking into account breast glandularity, were computed using Boone's method (Med Phys 2002; 29: 869-875). DgN coefficients can be calculated for any arbitrary X-ray spectrum. These calculation procedures were input into a Microsoft Excel spreadsheet. The resulting Excel spreadsheet is easy to use and is always applicable in the field of mammography. The exposure conditions concerning Dg in clinical practice were also investigated in 22 women. Four exposure conditions (target/filter combination and tube voltage) were automatically selected in this study. This investigation found that average Dg for each exposure was 1.9 mGy. Because it is recommended that quality control of radiation dose management in mammography is done using an American College of Radiology (ACR) phantom, information about patient dose is not obtained in many facilities. The present Excel spreadsheet was accordingly considered useful for optimization dingly considered useful for optimization of exposure conditions and explanation of mammography to patients. (author)

  14. Preliminary results of the average glandular dose to the breast with TLDS measure is computed as the conversion factors

    International Nuclear Information System (INIS)

    At mammography exams there is a risk of a breast cancer induced from the absorbed dose by the glandular tissue. According to the National Institute of Cancer, INCA, breast cancer is the second type most frequent in the world and the most common among women, therefore the necessity of monitoring the mean glandular dose, DG. Measuring methods of DG were established by some authors. Among the established methods the method of Dance is one of the most known. In this study was utilized a measurement method realized with TL dosimeters inserted in a breast tissue equivalent phantom, BTE, with 46% of glandularity and exposed using Mo/Mo and Mo/Rh target/filter combination and 28kV. To ensure this measurement method the results were compared with a calculation method, used by Dance, of DG from the measurement of incident air kerma, Ki, and conversion factors to consider mainly the beam quality, the compressed thickness and the glandularity of the breast. The results of the comparison of the DG measurement with the obtained dose by the method of Dance demonstrated that for the thickness of 4.0 and 6.0 cm the doses were consistent. For the thickness of 5.0 cm the difference was higher, indicating that the glandularity may influence, suggesting further investigation. (author)

  15. Calculation of mean glandular dose for mammography practice in Bangladesh

    International Nuclear Information System (INIS)

    The incidence of breast cancer in the western world is worryingly high now. The prognosis is best if the disease is detected early, whilst the tumour is small and before it has spread, As a consequence breast-screening programmes based upon X-ray mammography have been instigated in many countries. In Bangladesh the frequency of diagnosis by mammography is increasing day by day. Some of the examinations are repeated due to the low image contrast. This causes increase in personal dose as well as population dose. The technicians working in this field are concerned with the image quality but not about the dose that they impart to the patient. The radiation dose to breast from ionizing radiation varies with the examination types and machine types used for diagnosis. It varies with the technical parameters (kVp, mAs, source to skin distance) used during mammography examination. Many works regarding this field have been done in different countries in the world. They have a regular radiation dose assessment program but in Bangladesh, hardly any work has been done in this field. On this plea, mainly, the present work has been undertaken. The aim of this work was to evaluate the mean glandular dose to breast

  16. Estimating the glandular average dose in some mammography labs

    International Nuclear Information System (INIS)

    Mammography is the safest method of detecting breast cancer but, at the same time, the most accurate radiological examination which implies getting high quality images and a minimum dose per breast. This type of examination requires a special equipment and technique for the following reasons: a similarity of X-rays attenuating factors in the breast structure, an undetectable difference between the soft tissue density of the normal breast and of the sick breast, the importance of detecting minute details such as micro-calcifications. The present study was carried out in five mammography laboratories, from which only one has partially implemented a programme of quality control. There were evaluated the phantom image, film contrast, background optical density, density difference, and radiation beam quality. Also, the entrance surface air kerma was measured. The glandular average dose was estimated for the standard breast using the conversion coefficients corresponding to the used target-filter combination, and the values were determined for the radiation beam quality. Compared to the reference lab, all the other four labs failed all the tests, obtaining unacceptable results both for the phantom image and for the contrast, for the background optical density and density difference. The average glandular doses estimated for the standard breast varied between 0.71 and 1.59 mSv, being in four out of the five hospitals, statistically significant (p<0.001), lower than those curignificant (p<0.001), lower than those currently accepted by international authorities (3 mSv). The increasing number of breast cancer, of the equipment types and of the frequency of this type of investigation renders necessary the implementation of quality checking programmes. Such simple quality control procedures will improve the chances of accurate diagnosis and reduce the probability of false negatives. This is particularly important for early detection and treatment of breast cancer which is the most frequent type of cancer among females. (authors)

  17. Investigation of mean glandular dose in diagnostic mammography in China.

    Science.gov (United States)

    Du, Xiang; Wang, Jin; Yang, Chun Yong; Zhou, Xian Feng; Chen, Wei; Cao, Xing Jiang; Zhou, Yuan Yuan; Le Yu, Ning

    2014-05-01

    A survey of 420 exposures of mammography was performed with the parameters recorded. Entrance skin air kerma (ESAK) was measured and the mean glandular dose (MGD) was calculated according to the Dance's formula. Correlation analysis showed that several factors could affect the MGD level. Mann-whitney test and Non-parametric ANOVA analyses were used to compare the MGD level grouped by view type and radiographic systems. No significant difference was found in MGD between the craniocaudal (CC) group and the mediolateral oblique (MLO) group. The MGD level was higher in the CR group than in the other two groups. MGD was positively correlated with the compressed breast thickness (CBT). MGD varied with the half value layer (HVL) and increased first then decreased. The mean MGD level in China is about 1.6 mGy and is lower than the guidance level in the International Basic Safety Standards (IBSS). PMID:24827723

  18. Analysis of patient exposure dose for mammography. Estimation of average glandular dose in 1998 questionnaire

    International Nuclear Information System (INIS)

    Recently, patient exposure dose for mammography are varied because of a great demand for mammography, which non-palpable lesion can be detected, diffusion of special X-ray equipment, progress of CR and enlightenment or study on mammography in Japanese society of radiological technology. Therefore, the newest patient exposure dose obtained from '98 questionnaire carried out to the whole country in Japan was investigated. Furthermore, the average glandular dose based on '98 was compared with that of '93. The average glandular dose can be calculated from the product of the breast entrance skin exposure and DgN (the average glandular dose per unit entrance skin exposure). The breast entrance skin dose was estimated from the dose of 782 institutions in '98, which was calculated from data measured at 51 institutions in Tokai and Hokuriku area. DgN was used published table of 50% adipose-50% glandular breast composition and 4.2 cm breast thickness corresponding to measured half-value layer (HVL) on each tube voltages. Then, patient exposure dose for mammography was estimated from exposure condition (tube voltage, mAs value) obtained '98 questionnaire. The dose in '98 estimated 1.422 mGy was reduced that compared with in '93 estimated 1.610 mGy. The dose of '98 without grid was reduced about 30% of '93. The dose of 98 with grid was not any reduced than the dose of '93. However, the number of institution of '98 with grid was about 2.8 times than '93. The patient exposure dose times than '93. The patient exposure dose for mammography was reduced approximately 10% during 5 years. There are probability that mammography with grid for guidance level will be 1.5 mGy. (author)

  19. Average glandular dose in digital mammography and breast tomosynthesis

    International Nuclear Information System (INIS)

    Purpose: To determine the average glandular dose (AGD) in digital full-field mammography (2 D imaging mode) and in breast tomosynthesis (3 D imaging mode). Materials and Methods: Using the method described by Boone, the AGD was calculated from the exposure parameters of 2247 conventional 2 D mammograms and 984 mammograms in 3 D imaging mode of 641 patients examined with the digital mammographic system Hologic Selenia Dimensions. The breast glandular tissue content was estimated by the Hologic R2 Quantra automated volumetric breast density measurement tool for each patient from right craniocaudal (RCC) and left craniocaudal (LCC) images in 2 D imaging mode. Results: The mean compressed breast thickness (CBT) was 52.7 mm for craniocaudal (CC) and 56.0 mm for mediolateral oblique (MLO) views. The mean percentage of breast glandular tissue content was 18.0 % and 17.4 % for RCC and LCC projections, respectively. The mean AGD values in 2 D imaging mode per exposure for the standard breast were 1.57 mGy and 1.66 mGy, while the mean AGD values after correction for real breast composition were 1.82 mGy and 1.94 mGy for CC and MLO views, respectively. The mean AGD values in 3 D imaging mode per exposure for the standard breast were 2.19 mGy and 2.29 mGy, while the mean AGD values after correction for the real breast composition were 2.53 mGy and 2.63 mGy for CC and MLO views, respectively. No significant relationship was found between the AGD and CBT in 2 D imaging mode and a ghe AGD and CBT in 2 D imaging mode and a good correlation coefficient of 0.98 in 3 D imaging mode. Conclusion: In this study the mean calculated AGD per exposure in 3 D imaging mode was on average 34 % higher than for 2 D imaging mode for patients examined with the same CBT.

  20. Analysis of patient exposure dose for mammography: estimation of average glandular dose in 2007 questionnaire

    International Nuclear Information System (INIS)

    Recently, the swift progress of digital mammography has resulted in variation in patient exposure doses during mammography in Japan. We therefore carried out a study in 2007 to determine the latest patient exposure dose by means of a nationwide questionnaire survey of Japan, and compared the average glandular dose with those of 1993, 1998, and 2001. The average glandular dose can be calculated from the product of the breast entrance skin exposure and DgN (the average glandular dose per unit entrance skin exposure). The 2007 breast entrance skin dose was estimated from doses at 434 institutions, calculated on the basis of tube voltages measured at 51 institutions in the Tokai and Hokuriku regions of Japan. The DgN was calculated by using a published table of 50% adipose-50% glandular breast composition and 4.2 cm breast thickness corresponding to the measured half-value layer (HVL) at each tube voltage. The patient exposure dose for mammography was then estimated from exposure conditions (tube voltage, mAs value) obtained from the 2007 questionnaire. The 2007 estimated dose of about 1.7 mGy had increased compared with 1.4 mGy in 1998 and 1.5 mGy in 2001, returning to a value close to that of 1.6 mGy in 1993. This is the result of the great popularity of digital mammography, in particular computed radiography (CR). Digital mammography is increasing, accounting for about 70% of all mammography in the current investigation in comparison with 28.3% in 2001, 24.0% in 1998 and 8.8% in 1993, when the first survey of patient exposure dose for mammography was carried out. The patient exposure dose during digital mammography, and for CR in particular, should therefore be reconsidered. (author)

  1. Average glandular dose and phantom image quality in mammography

    Science.gov (United States)

    Oliveira, M.; Nogueira, M. S.; Guedes, E.; Andrade, M. C.; Peixoto, J. E.; Joana, G. S.; Castro, J. G.

    2007-09-01

    Doses in mammography should be maintained as low as possible without reducing the high image quality needed for early detection of the breast cancer. The breast is composed of tissues with very close composition and densities. It increases the difficulty to detect small changes in the normal anatomical structures which may be associated with breast cancer. To achieve the standards of definition and contrast for mammography, the quality and intensity of the X-ray beam, the breast positioning and compression, the film-screen system, and the film processing have to be in optimal operational conditions. This study sought to evaluate average glandular dose (AGD) and image quality on a standard phantom in 134 mammography units in the state of Minas Gerais, Brazil, between December 2004 and May 2006. AGDs were obtained by means of entrance kerma measured with TL LiF100 dosimeters on phantom surface. Phantom images were obtained with automatic exposure technique, fixed 28 kV and molybdenum anode-filter combination. The phantom used contained structures simulating tumoral masses, microcalcifications, fibers and low contrast areas. High-resolution metallic meshes to assess image definition and a stepwedge to measure image contrast index were also inserted in the phantom. The visualization of simulated structures, the mean optical density and the contrast index allowed to classify the phantom image quality in a seven-point scale. The results showed that 54.5% of the facilities did not achieve the minimum performance level for image quality. It is mainly due to insufficient film processing observed in 61.2% of the units. AGD varied from 0.41 to 2.73 mGy with a mean value of 1.32±0.44 mGy. In all optimal quality phantom images, AGDs were in this range. Additionally, in 7.3% of the mammography units, the AGD constraint of 2 mGy was exceeded. One may conclude that dose level to patient and image quality are not in conformity to regulations in most of the facilities. This indicates that ongoing actions are needed to optimize image quality and radiation dose for early detection of the breast cancer.

  2. A Methodology for Obtaining the Mean Glandular Dose in Mammography Exams

    Science.gov (United States)

    Feital, J. C.; Delgado, J. U.; Lopes, R. T.

    2015-01-01

    This study proposes to validate measurements of mean glandular dose quantity (DG) for a given thickness and glandularity of compressed breast based in a PMMA phantom. 10 exposures were made in an ionization chamber in conventional mammographic equipment for a research. It obtained an average value for the incident air kerma, Ka,I = 9.59 mGy leading to a DG = 1.82 mGy. Experimental results too were obtained for the acquisition of this quantity in other mammography clinics and these results were also reported and discussed. After the comparison of the results the methodology was validated.

  3. Evaluation of average glandular dose in digital and conventional systems of the mammography; Avaliacao da dose glandular media em sistemas digitais e convencionais de mamografia

    Energy Technology Data Exchange (ETDEWEB)

    Xavier, Aline C.S.; Barros, Vinicius S.M.; Khoury, Hellen J., E-mail: alinecx90@gmail.com, E-mail: vsmdbarros@gmail.com, E-mail: hjkhoury@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear; Mello, Francisca A. de, E-mail: francissamello@yahoo.com.br [Hospital das Clinicas do Recife (HCR/UFPE), PE (Brazil)

    2014-07-01

    Mammography is currently the most effective method of diagnosis and detection of breast pathologies. The main interest in this kid of exam comes from the high incidence rate of breast cancer and necessity of high quality images for accurate diagnosis. Digital mammography systems have several advantages compared to conventional systems, however the use of digital imaging systems is not always integrated to an image acquisition protocol. Therefore, it is questionable if digital systems truly reduce the dose received by the patient, because many times is introduced in the clinics without optimization of the image acquisition protocols. The aim of this study is to estimate the value of incident air Kerma and average glandular dose (AGD) in patients undergoing conventional and digital mammography systems in Recife. This study was conducted with 650 patients in three hospitals. The value of incident air Kerma was estimated from the measurement of the yield of equipment and irradiation parameters used for each patient. From these results and using the methodology proposed by Dance et al. the value of the average glandular dose was calculated. The results obtained show that the lowest value of AGD was found with conventional screen-film system, indicating that the parameters for image acquisition with digital systems are not optimized. It was also observed that the institutions with digital systems use lower breast compression values than the conventional. (author)

  4. Average glandular dose with amorphous silicon full-field digital mammography - clinical results

    International Nuclear Information System (INIS)

    Purpose: Determination of average glandular dose with a full-field digital mammography system using a flat-panel X-ray detector based on amorphous silicon technology for a large group of patients. Material and Methods: The patient group includes women who were examined in a 4-month period with the digital mammographic system Senographe 2000D. The number of women was 591 and the number of exposures was 1116; only cranio-caudal projections were considered. Various quantities, including entrance surface air kerma, tube loading, and compressed breast thickness, were determined during actual mammography. Average glandular dose was determined using conversion factors g for standard breast composition. Results: The mean average glandular dose was 1.51 mGy (0.66-4.05 mGy) for a single view. The mean compressed breast thickness was 55.7 mm. The mean age of patients was 55 years (34-81 years). Conclusion: The results demonstrate that full-field digital mammography with a flat-panel detector based on amorphous silicon needs about 25% less dose in comparison with conventional screen-film mammography. (orig.)

  5. Uncertainties involved in the estimation of mean glandular dose for women in the Norwegian Breast Cancer Screening Program (NBCSP).

    Science.gov (United States)

    Hauge, I H R; Olerud, H M

    2013-06-01

    The aim of this study was to reflect on the estimation of the mean glandular dose for women in Norway aged 50-69 y. Estimation of mean glandular dose (MGD) has been conducted by applying the method of Dance et al. (1990, 2000, 2009). Uncertainties in the thickness of approximately ±10 mm adds uncertainties in the MGD of approximately ±10 %, and uncertainty in the glandularity of ±0 % will lead to an uncertainty in the MGD of ±4 %. However, the inherent uncertainty in the air kerma, given by the European protocol on dosimetry, will add an uncertainty of 12 %. The total uncertainty in the MGD is estimated to be ?20 %, taking into consideration uncertainties in compressed breast thickness (±10 %), the air kerma (12 %), change in HVL by -0.05 mm (-9.0 %), uncertainty in the s-factor of ±2.1 % and changing the glandularity to an age-dependent glandularity distribution (+8.4 %). PMID:23188812

  6. Estudo comparativo de dosimetria computacional entre modelos homogêneos e um modelo voxel em mamografia: uma discussão de aplicações em testes de constância e cálculo de dose glandular em pacientes / Comparative study of computational dosimetry involving homogeneous phantoms and a voxel phantom in mammography: a discussion on applications in constancy tests and calculation of glandular dose in patients

    Scientific Electronic Library Online (English)

    Vagner Ferreira, Cassola; Gabriela, Hoff.

    2010-12-01

    Full Text Available OBJETIVO: Comparar dados de dosimetria e fluência de fótons entre diferentes modelos de mama, discutindo as aplicações em testes de constância e estudos dosimétricos aplicados à mamografia. MATERIAIS E MÉTODOS: Foram simulados diferentes modelos homogêneos e um modelo antropomórfico de mama tipo vox [...] el, sendo contabilizadas: a dose total absorvida no modelo, a dose absorvida pelo tecido glandular/material equivalente, e a dose absorvida e a fluência de fótons em diferentes profundidades dos modelos. Uma câmara de ionização simulada coletou o kerma de entrada na pele. As combinações alvo-filtro estudadas foram Mo-30Mo e Mo-25Rh, para diferentes potenciais aceleradores de 26 kVp até 34 kVp. RESULTADOS: A dose glandular normalizada, comparada ao modelo voxel, resultou em diferenças entre -15% até -21% para RMI, -10% para PhantomMama e 10% para os modelos Barts e Keithley. A variação dos valores da camada semirredutora entre modelos foi geralmente inferior a 10% para todos os volumes sensíveis. CONCLUSÃO: Para avaliar a dose glandular normalizada e a dose glandular, em mamas médias, recomenda-se o modelo de Dance. Os modelos homogêneos devem ser utilizados para realizar testes de constância em dosimetria, mas eles não são indicados para estimar a dosimetria em pacientes reais Abstract in english OBJECTIVE: To compare data regarding dosimetry and photons fluence in different breast phantoms, discussing constancy tests and dosimetry applied to mammography. MATERIALS AND METHODS: Different homogeneous breast phantoms and one anthropomorphic voxel phantom were developed for collection of data r [...] egarding total absorbed dose in the phantom, absorbed dose in the glandular tissue material-equivalent, absorbed dose and photons fluence at different depths in the phantoms. A simulated ionization chamber collected the entrance skin kerma. Target-filter combinations (Mo-30Mo and Mo-25Rh) were studied for different accelerating potentials of 26 kVp to 34 kVp. RESULTS: As compared with the voxel phantom, the normalized glandular dose resulted in differences from -15% to -21% for RMI, -10% for PhantomMama, and 10% for the Barts and Keithley models. The half-value layer variation was generally

  7. The Study of Mean Glandular Dose in Mammography in Yazd and the Factors Affecting It

    Directory of Open Access Journals (Sweden)

    F. Bouzarjomehri

    2006-08-01

    Full Text Available Backgrounds/Objective: The objective of this study was to determine the mean glandular dose (MGD resulting from mammography examinations in Yazd, southeastern Iran and to identify the factors affecting it. Patients and Methods: This survey was conducted during May to December 2005 to estimate the MGD for women undergoing mammography and to report the distribution of dose, com-pressed breast thickness, glandular tissue content, and mammography technique used. The clinical data were collected from 946 mammograms taken from 246 women who were referred to four mammography centers. The mammography instruments in these centers were four modern units with a molybdenum anode and either molybdenum or rhodium filter. The exposure conditions of each mammogram were recorded. The breast glandular content of each mammogram was estimated by a radiologist. The MGD was calculated based on measuring the normalized entrance skin dose (ESD in air, Half Value Layer (HVL, kVp, mAs, breast thickness and glandular content. HVL, kVp and ESD were measured by a solid-state detector. The analytical method of Sobol et al. was used for calculation of MGD. Results: The mean±SD MGD per film was 1.2±0.6 mGy for craniocaudal and 1.63±0.9 mGy for mediolateral oblique views. The mean±SD MGD per woman was 5.57±3.1 mGy. A positive correlation was found between the beam HVL with MGD (r=0.38 and the breast thickness with MGD (r=0.5. Conclusion: The mean±SD MGD per film of 1.42±0.8 mGy in present study was lower than most of similar reports. However, the mean MGD per woman was higher than that in other studies.

  8. DETERMINACIÓN DE UN MÉTODO DE CALCULO DE DOSIS GLANDULAR PROMEDIO EN EXAMENES DE MAMOGRAFIA CONVENCIONAL DETERMINATION OF A METHOD FOR CALCULATING MEAN GLANDULAR DOSE IN CONVENTIONAL MAMMOGRAPHY EXAMS

    Directory of Open Access Journals (Sweden)

    Oswaldo Ramos N

    2009-01-01

    Full Text Available Presentamos la aplicación de un modelo numérico para estimarla dosis glandular promedio en mamografía. Hemos utilizado un mamógrafo General Electric, tensión del tubo: 20-35 kV con incrementos de 1 kV; carga del tubo: 10-250 mAs; combinación ánodo-filtro de Molibdeno-Molibdeno. Durante dos meses datos de 162 exploraciones con proyecciones cráneo-caudal y medio lateral oblicua en ambas mamas. El espesor de mama comprimida se encuentra en el rango de 2,5 a 6,5 cm. Los rangos de dosis glandular promedio, por cada proyección cráneo-caudal, se encuentran de 0,4 a 0,7 mGy para un espesor de 2,5 cm y de 1,9 a 2,8 mGy para un espesor de 6,5 cm. Los valores medios de dosis glandular promedio estimados por proyección cráneo-caudal, en su totalidad resultan por debajo del valor de referencia dado por el Colegio Americano de Radiología (3 mGy.We present the application of a numerical model to estimate the mean glandular dose for mammography. A General Electric mammography system, tube voltaje of 20-35 kV with increments of 1 kV, tube current of 10-250 mAs, anode/filter combinations molybdenum/molybdenum was used. Over a period of two months, data from 162scans with craniocaudal and mediolateral oblique projections in both breasts were recorded. The thickness of the compressed breast ranged from 2.5 to 6.5 cm. The mean glandular dose for each craniocaudal projection ranged from 0.4 to 0.7mGy for a thickness of2.5 cm and 1.9 to 2.8 mGy for a thickness of 6.5 cm. All average values of mean glandular dose estimated by cranio-caudal projection were found to be below the international reference dose value of3 mGy recommended by the American College of Radiology.

  9. DETERMINACIÓN DE UN MÉTODO DE CALCULO DE DOSIS GLANDULAR PROMEDIO EN EXAMENES DE MAMOGRAFIA CONVENCIONAL / DETERMINATION OF A METHOD FOR CALCULATING MEAN GLANDULAR DOSE IN CONVENTIONAL MAMMOGRAPHY EXAMS

    Scientific Electronic Library Online (English)

    Oswaldo, Ramos N; Manuel, Villarreal U.

    Full Text Available Presentamos la aplicación de un modelo numérico para estimarla dosis glandular promedio en mamografía. Hemos utilizado un mamógrafo General Electric, tensión del tubo: 20-35 kV con incrementos de 1 kV; carga del tubo: 10-250 mAs; combinación ánodo-filtro de Molibdeno-Molibdeno. Durante dos meses dat [...] os de 162 exploraciones con proyecciones cráneo-caudal y medio lateral oblicua en ambas mamas. El espesor de mama comprimida se encuentra en el rango de 2,5 a 6,5 cm. Los rangos de dosis glandular promedio, por cada proyección cráneo-caudal, se encuentran de 0,4 a 0,7 mGy para un espesor de 2,5 cm y de 1,9 a 2,8 mGy para un espesor de 6,5 cm. Los valores medios de dosis glandular promedio estimados por proyección cráneo-caudal, en su totalidad resultan por debajo del valor de referencia dado por el Colegio Americano de Radiología (3 mGy). Abstract in english We present the application of a numerical model to estimate the mean glandular dose for mammography. A General Electric mammography system, tube voltaje of 20-35 kV with increments of 1 kV, tube current of 10-250 mAs, anode/filter combinations molybdenum/molybdenum was used. Over a period of two mon [...] ths, data from 162scans with craniocaudal and mediolateral oblique projections in both breasts were recorded. The thickness of the compressed breast ranged from 2.5 to 6.5 cm. The mean glandular dose for each craniocaudal projection ranged from 0.4 to 0.7mGy for a thickness of2.5 cm and 1.9 to 2.8 mGy for a thickness of 6.5 cm. All average values of mean glandular dose estimated by cranio-caudal projection were found to be below the international reference dose value of3 mGy recommended by the American College of Radiology.

  10. Estimation of average glandular dose depending on the thickness of the breast; Estimativa da dose glandular media em funcao da espessura da mama

    Energy Technology Data Exchange (ETDEWEB)

    Real, Jessica V.; Luz, Renata M. da, E-mail: jessica.real@pucrs.br, E-mail: renata.luz@pucrs.br [Hospital Sao Lucas (HSL/PUCRS), Porto Alegre, RS (Brazil); Fröhlich, Bruna D.; Pertile, Alessandra S.; Silva, Ana Maria Marques da, E-mail: bruna.frohlich@acad.pucrs.br, E-mail: lessandra.pertile@acad.pucrs.br, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2014-07-01

    Breast cancer is the most common type of cancer in women worldwide. Mammography is, to date, the most efficient method for detecting an abnormality in the patient's breast. It is a technique of imaging diagnostic that requires special care because radiographs without adequate quality may lead to a false diagnosis and lead to the need for a repeat examination, increasing the dose of radiation in the patient. This study aimed to evaluate the average glandular dose (AGD), depending on the breast thickness in patients undergoing routine tests, with a digital computer radiography processing system. Analyzed 30 exhibitions in patients aged (65 ± 12) years, in the right and left caudal skull projections, for breasts with thicknesses between 45 mm and 50 mm. The calculated value of the AGD for this track thickness was (1.600 ± 0.009) mGy. The performance of mammography quality control tests was satisfactory and the AGD values obtained for the chosen thickness range is acceptable, since the threshold achievable is 1.6 mGy and the acceptable is 2 mGy. In Brazil, it is only required the input dose calculation in skin for 45 mm breasts. However, the calculation of AGD is required for different thicknesses of the breast, to identify the best mammographic pattern aiming at better image quality at the lowest dose provided the patient.

  11. Evaluation of average glandular dose in digital and conventional systems of the mammography

    International Nuclear Information System (INIS)

    Mammography is currently the most effective method of diagnosis and detection of breast pathologies. The main interest in this kid of exam comes from the high incidence rate of breast cancer and necessity of high quality images for accurate diagnosis. Digital mammography systems have several advantages compared to conventional systems, however the use of digital imaging systems is not always integrated to an image acquisition protocol. Therefore, it is questionable if digital systems truly reduce the dose received by the patient, because many times is introduced in the clinics without optimization of the image acquisition protocols. The aim of this study is to estimate the value of incident air Kerma and average glandular dose (AGD) in patients undergoing conventional and digital mammography systems in Recife. This study was conducted with 650 patients in three hospitals. The value of incident air Kerma was estimated from the measurement of the yield of equipment and irradiation parameters used for each patient. From these results and using the methodology proposed by Dance et al. the value of the average glandular dose was calculated. The results obtained show that the lowest value of AGD was found with conventional screen-film system, indicating that the parameters for image acquisition with digital systems are not optimized. It was also observed that the institutions with digital systems use lower breast compression values than the conventional. (author)

  12. Criteria and measurements for the collection and validation of the mean glandular dose due to mammography exams

    International Nuclear Information System (INIS)

    This study proposes to validate measurements of mean glandular dose quantity (DG) for the compressed breast according to the representative's phantom measurements results. There were exposures in an ionization chamber and obtained an mean value for the absorbed dose or entrance surface air kerma (Ka,e) and other results were obtained for this quantity. In addition to the value obtained of 1.84 mGy ± 0.2 % for DG at the two major experimental projections in mammography clinic, other results were reported and discussed. Regarding the level of uncertainty associated with the DG, it was proved to be 5 times greater than the measurements of uncertainties estimated in each clinic, based on quality control tests. However, this result was expected because other components of significant uncertainty in its composition were also considered, as consistent with the practices and negligible in relation to the ultimate given quantity. After the comparison of the representative dose value with the reference level (2.5 mGy), according to literature, such measurements were validated with appropriate recommendations. (author)

  13. Criteria and measurements for the collection and validation of the mean glandular dose due to mammography exams

    Energy Technology Data Exchange (ETDEWEB)

    Feital, Joao Carlos da Silva; Delgado, Jose Ubiratan, E-mail: jfeital@ird.gov.br, E-mail: delgado@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN- RJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    This study proposes to validate measurements of mean glandular dose quantity (D{sub G}) for the compressed breast according to the representative's phantom measurements results. There were exposures in an ionization chamber and obtained an mean value for the absorbed dose or entrance surface air kerma (K{sub a,e}) and other results were obtained for this quantity. In addition to the value obtained of 1.84 mGy ± 0.2 % for D{sub G} at the two major experimental projections in mammography clinic, other results were reported and discussed. Regarding the level of uncertainty associated with the D{sub G}, it was proved to be 5 times greater than the measurements of uncertainties estimated in each clinic, based on quality control tests. However, this result was expected because other components of significant uncertainty in its composition were also considered, as consistent with the practices and negligible in relation to the ultimate given quantity. After the comparison of the representative dose value with the reference level (2.5 mGy), according to literature, such measurements were validated with appropriate recommendations. (author)

  14. Analysis of patient radiation exposure in mammography. Estimation of average glandular dose in a 1998 questionnaire

    International Nuclear Information System (INIS)

    Recently, patient radiation exposure in mammography has varied because of the great demand for mammography, the diffusion of special X-ray equipment, progress in CR, and improvement or study of mammography by the Japanese Society of Radiological Technology. Therefore, data on patient radiation exposure obtained with a 1998 questionnaire survey throughout Japan was analyzed. In addition, the average glandular dose in 1998 was compared with that in 1993. The doses at 782 institutions in 1998 were calculated from data obtained at 51 institutions in the Tokai and Hokuriku regions. The estimated dose in 1998 (1.422 mGy) was lower than that in 1993 (1.610 mGy). The target level for mammography with grid might be 1.5 mGy. (author)

  15. Analysis of patient radiation exposure in mammography. Estimation of average glandular dose in a 1998 questionnaire

    Energy Technology Data Exchange (ETDEWEB)

    Asada, Yasuo; Suzuki, Shoichi; Fujii, Shigehisa; Orito, Takeo [Fujita Health Univ., Toyoake, Aichi (Japan). School of Health Sciences; Kamei, Tetsuya; Koga, Sukehiko; Horita, Kappei; Ohuchi, Noriaki

    2000-05-01

    Recently, patient radiation exposure in mammography has varied because of the great demand for mammography, the diffusion of special X-ray equipment, progress in CR, and improvement or study of mammography by the Japanese Society of Radiological Technology. Therefore, data on patient radiation exposure obtained with a 1998 questionnaire survey throughout Japan was analyzed. In addition, the average glandular dose in 1998 was compared with that in 1993. The doses at 782 institutions in 1998 were calculated from data obtained at 51 institutions in the Tokai and Hokuriku regions. The estimated dose in 1998 (1.422 mGy) was lower than that in 1993 (1.610 mGy). The target level for mammography with grid might be 1.5 mGy. (author)

  16. Absorbed dose uncertainty estimation for proton therapy

    Directory of Open Access Journals (Sweden)

    Spasi?-Joki? Vesna

    2012-01-01

    Full Text Available Successful radiotherapy treatment depends on the absorbed dose evaluation and the possibility to define metrological characteristics of the therapy beam. Radiotherapy requires tumor dose delivery with expanded uncertainty less than ±5 %. It is particularly important to reduce uncertainty during therapy beam calibration as well as to apply all necessary ionization chamber correction factors. Absorbed dose to water was determined using ionometric method. Calibration was performed in reference cobalt beam. Combined standard uncertainty of the calculated absorbed dose to water in 65 MeV proton beam was ±1.97% while the obtained expanded uncertainty of absorbed dose for the same beam quality was ±5.02%. The uncertainty estimation method has been developed within the project TESLA.

  17. Investigation of quality control and average glandular dose and image quality in digital mammography in Hokkaido

    International Nuclear Information System (INIS)

    A questionnaire survey about mammography in Hokkaido was mailed to 121 facilities from August to September 2009. We surveyed the conditions of digital mammography with regard to quality control (QC) and average glandular dose at 79 facilities in Hokkaido in 2009, and the results of the survey were compared with those of 2004. We found that digital mammography techniques were widely used across Hokkaido and that computed radiography (CR) systems were quite widespread, with 70% of facilities having them. The average glandular dose ranged from 1.04 to 2.3 mGy (mean: 1.73 mGy) for digital equipment. The results revealed several problems. Although the use of 1-, 2-, and 3-megapixel (MP) liquid crystal displays (LCDs) was not uncommon, 5-MP LCDs were used in most cases when reading digital mammograms. Facilities that have mammography equipment are unlikely to have quality control instruments for mammography. Although daily QC is performed in most facilities, further quality control for digital mammography should be developed, including that for monitors. In a second study, we evaluated the 1 Shot Phantom M Plus (1 Shot Phantom), which enables objective evaluation by providing for one physical measurement rather than a subjective visual analysis. The results indicated that the 1 Shot Phantom was very useful for digital mammography systems in daily QC testing because it enabled objectivity. (author)

  18. Assessment of glandular dose and image quality in mammography using computerised radiography employing a polymethylmetacrilate breast simulator

    International Nuclear Information System (INIS)

    In Brazil there are around 600 mammography equipment with CR system. Taking into account the quality of image is essential to evaluate the mean glandular dose so you can optimize the radiation protection of patients evaluated with this type of system. Therefore, this study aimed to determine the mean glandular dose and quality of image for the CR system of laboratory of radioprotection applied to mammography of the Centre of Development of Nuclear Technology (CDTN). For this, we evaluated the linearity of the detector’s response, contrast to noise ratio and signal to noise ratio, which, according to European protocol, showed results within acceptable limits. Next, evaluated the quality of image with the CDMAM Phantom and mean glandular dose to the detector Fluke Biomedical TNT 12000WD, where they presented, respectively, within the results expected by the manufacturer and the limits of acceptable and desirable by the European protocol. then, the CR system of CDTN is optimized.

  19. Mammography equipment performance, image quality and mean glandular dose in Malta

    International Nuclear Information System (INIS)

    In this first Maltese national mammography survey, the effectiveness of direct digital (DR) mammography in breast cancer screening has been confirmed. Patient data were made available from three clinics out of the participating nine. A dose survey of mean glandular dose (MGD) calculated for 759 patients examined in the state-owned mammography facilities was performed. An MGD national diagnostic reference level was set at 1.87 mGy for patients with breast compression thicknesses (BCT) between 5.0 and 7.0 cm. This range was selected since patient data were retrieved from three clinics only and the results showed that other international BCT reference levels may be unsuitable for the Maltese population. In fact, the overall average BCT was 5.75±1.4 cm. The survey results have shown that the technical standard of mammographic equipment in the Malta National Breast Screening Programme is on a par with other countries, including its Western European counterparts. (authors)

  20. A new dosimetric phantom for evaluation of glandular dose in conventional and digital mammography systems

    International Nuclear Information System (INIS)

    Mammography is a screening method for early detection of breast cancer. Mammography aims to achieve a high image quality associated with a radiation dose in the patient as low as achievable where any existing abnormality or lesion is clearly visualized, ensuring the production of exams that enable a precise diagnosis. The mean glandular dose, DG, is defined as the energy deposited per unit mass of fibroglandular tissue (the most radiosensitive tissue in the breast) averaged over all the fibroglandular tissue in the breast. DG is calculated from values of entrance air kerma, the X ray beam quality (half- value layer), and compressed breast thickness. DG is the quantity that best characterizes the breast carcinogenic risk of ionizing radiation

  1. A ?-ray absorbed dose rate meter, (1)

    International Nuclear Information System (INIS)

    A measuring method and dose rate meter for ?-ray absorbed dose independent of the ?-ray maximum energy have been developed. To obtain constant dose sensitivity (counting rate per absorbed dose rate), a thin plastic scintillator is used as the detector, and the pulses selected by a single channel analyzer (SCA) are counted. The desirable pulse height distribution in obtaining a constant dose sensitivity is obtained with 2 mm thick scintillator. The lower level of discrimination and the window width of the SCA are chosen according to the epidermal thickness of tissue exposed to ?-rays. The dose sensitivity of the absorbed dose rate meter is constant at 50 cps/(mrad/hr) +-15% for ?-rays with maximum energy 0.4 -- 3.5 MeV (epidermal thickness 7 mg/cm2) and 0.3 -- 3.5 MeV (epidermal thickness 40 mg/cm2). The absorbed dose rate is given by multiplying the counting rate by a constant factor 2.0 x 10-2 (mrad/hr)/cps. The lower limit of dose rate measurement is 1.7 x 10-2 mrad/hr (7 mg/cm2) and 9.4 x 10-3 mrad/hr (40 mg/cm2). (auth.)

  2. Determination of mean glandular dose on patients and phantom in X-ray mammography

    International Nuclear Information System (INIS)

    The statistics of breast cancer rate in Bulgaria show a tendency towards increase of the morbidity from this disease. Last years campaigns against breast cancer are organized yearly. This leads to an increased number of screening and diagnostic mammograms that are made in the country. The dose associated with the examination is very low but not slightingly small. The glandular tissue in the breast is considered to be the most sensitive in relation to the radiation exposure. Several publications propose different methods, measurement set up or conversion coefficients for the calculation of the mean glandular dose (MGD) delivered to the breast during the X-ray examination. The question about the standardization of the measurement procedures arises since the differences in the results obtained using different methodologies may be quite big. The aim of this work is to develop a standard procedure for the measurement of MGD based on the recommendations mentioned in the European protocol on dosimetry in mammography, the European protocol for the quality control of the physical and technical aspects of mammography screening and the Code of practice: TRS 457 of the IAEA. Five contemporary film-screen mammography units were included in this study. Attention should be paid to the measurement set up. The reference point is chosen 6 cm from the chest wall edge laterally centered. If an ionization chamber is used for dose measurements the compression plate should be placed in close contact with it. If solid state detectors are used the compression plate should be put away from the detector and the output recalculated like if the plate is near the detector. The conversion coefficients for age dependence are not used in this study as not appropriate for the population included in it. PMMA measurements for the determination of diagnostic reference levels could be used but more correct results would be obtained with patient measurements

  3. Preliminary Studies into the Determination of Mean Glandular Dose During Diagnostic Mammography Procedure in Ghana

    Directory of Open Access Journals (Sweden)

    Irene Nsiah-Akoto

    2011-08-01

    Full Text Available The objective of this project was to determine the mean glandular dose (MGD from Craniocaudal (CC and Mediolateral Oblique (MLO views to the breast during diagnostic mammography and the total dose per woman. The study was conducted at the Mammography Unit of Komfo Anokye Teaching Hospital and Peace and Love Hospital, Oduom. Data such as age, weight, height, bust size, compressed breast thickness, time of exposure, milli-ampere second (mAs, kilovoltage peak (KVp and half value layer (HVL were recorded from 440 films from 110 women. The MGD per film was 1.17± 0.02 mGy and 1.25±0.03 mGy for the craniocaudal (CC and mediolateral oblique (MLO views, respectively. The mean MGD per woman was 1.80±0.03mGy. The only factors that were found to affect MGD were mAs and the compressed breast thickness. No significant relationships were seen between MGD per woman with respect to ethnicity and educational background. The dose values obtained fall within the internationally acceptable dose range of 1-3 mGy. This suggests mammography x-ray generators at the two hospitals are capable of achieving acceptable dose levels for patient safety and this prompted us to rule out the fact that all other factors considered, they are not at risk of induced cancer from mammography.

  4. Optimizing the anode-filter combination in the sense of image quality and average glandular dose in digital mammography

    Science.gov (United States)

    Varjonen, Mari; Strömmer, Pekka

    2008-03-01

    This paper presents the optimized image quality and average glandular dose in digital mammography, and provides recommendations concerning anode-filter combinations in digital mammography, which is based on amorphous selenium (a-Se) detector technology. The full field digital mammography (FFDM) system based on a-Se technology, which is also a platform of tomosynthesis prototype, was used in this study. X-ray tube anode-filter combinations, which we studied, were tungsten (W) - rhodium (Rh) and tungsten (W) - silver (Ag). Anatomically adaptable fully automatic exposure control (AAEC) was used. The average glandular doses (AGD) were calculated using a specific program developed by Planmed, which automates the method described by Dance et al. Image quality was evaluated in two different ways: a subjective image quality evaluation, and contrast and noise analysis. By using W-Rh and W-Ag anode-filter combinations can be achieved a significantly lower average glandular dose compared with molybdenum (Mo) - molybdenum (Mo) or Mo-Rh. The average glandular dose reduction was achieved from 25 % to 60 %. In the future, the evaluation will concentrate to study more filter combinations and the effect of higher kV (>35 kV) values, which seems be useful while optimizing the dose in digital mammography.

  5. Evaluation of absorbed dose and image quality in mammography

    International Nuclear Information System (INIS)

    Mammography refers to the X-ray examination of the human breast, and is considered the single most important diagnostic tool in the early detection of breast cancer, which is by far the most common cancer among women. There is good evidence from clinical trials, that mammographic screening can reduce the breast cancer mortality with about 30%. The side effects include a small and age related risk of carcinogenesis due to the exposure of the glandular tissues in the breast to ionising radiation. As for all X-ray examinations, and of special importance when investigating large populations of asymptomatic women, the relationship between radiation risk and diagnostic accuracy in mammography must be optimised. The overall objective of this thesis was to investigate and improve methods for average glandular dose (AGD) and image quality evaluation in mammography and provide some practical guidance. Dose protocols used for so-called reference dose levels in Sweden 1989 (Nordic) and 1998 (European) were compared in a survey of 32 mammography units. The study showed that the AGD values for a 'standard breast' became 5±2% (total variation 0-9%) higher at clinical settings, when estimated according to the European protocol. For the Sectra MDM, a digital mammography (DM) unit with a scanning geometry, it was impossible to follow procedures for characterisation of the X-ray beam (HVL=half value layer) specified in the European protocol. In an experimental setup, it was shown that an experimental setup, it was shown that non-invasive measurements of HVL can be performed accurately with a sensitive and well collimated semiconductor detector with simultaneous correction for the energy dependence. AGD values could then be estimated according to 3 different dose protocols. A dosimetry system based on radioluminescence and optically stimulated luminescence from Al2O3:C crystals was developed and tested for in vivo absorbed dose measurements. It was shown that both entrance and exit doses could be measured and that the dosemeters did not disturb the reading of the mammograms. A Monte Carlo study showed that the energy dependence could be reduced, primarily by reducing the diameter of the crystal. It is proposed that radiation scattered forward towards the breast from the compression paddle, a scanning device etc, should be considered with greater clarity in the breast dosimetry protocols, and be described with a forward-scatter factor, FSF, for the various geometries and conditions proposed. Low contrast-detail (CD) phantoms of simulated glandularity 30, 50 or 70%, and thickness 3, 5 or 7 cm, were used to compare three different mammography systems. The same number of perceivable objects was visible for the full-field DM system at 20-60% of the AGD necessary for the screen-film (SFM) system, with the largest dose reduction potential for the thickest phantoms with the highest glandularity. However, more recent research shows that CD phantoms with a homogeneous background, as used here, must be used with care due to the presence of 'anatomical noise' in the real clinical situation. Image quality criteria (IQC) recommended in a European Guideline 1996 for SFM were adjusted to be relevant also for DM images. The new set of IQC was tested in two different studies using clinical images from DM and SFM, respectively. The results indicate that the new set of IQC has a higher discriminative power than the old set. The results also suggest that AGD for the DM system used may be reduced

  6. Evaluation of absorbed dose and image quality in mammography

    Energy Technology Data Exchange (ETDEWEB)

    Hemdal, Bengt

    2009-07-01

    Mammography refers to the X-ray examination of the human breast, and is considered the single most important diagnostic tool in the early detection of breast cancer, which is by far the most common cancer among women. There is good evidence from clinical trials, that mammographic screening can reduce the breast cancer mortality with about 30%. The side effects include a small and age related risk of carcinogenesis due to the exposure of the glandular tissues in the breast to ionising radiation. As for all X-ray examinations, and of special importance when investigating large populations of asymptomatic women, the relationship between radiation risk and diagnostic accuracy in mammography must be optimised. The overall objective of this thesis was to investigate and improve methods for average glandular dose (AGD) and image quality evaluation in mammography and provide some practical guidance. Dose protocols used for so-called reference dose levels in Sweden 1989 (Nordic) and 1998 (European) were compared in a survey of 32 mammography units. The study showed that the AGD values for a 'standard breast' became 5+-2% (total variation 0-9%) higher at clinical settings, when estimated according to the European protocol. For the Sectra MDM, a digital mammography (DM) unit with a scanning geometry, it was impossible to follow procedures for characterisation of the X-ray beam (HVL=half value layer) specified in the European protocol. In an experimental setup, it was shown that non-invasive measurements of HVL can be performed accurately with a sensitive and well collimated semiconductor detector with simultaneous correction for the energy dependence. AGD values could then be estimated according to 3 different dose protocols. A dosimetry system based on radioluminescence and optically stimulated luminescence from Al2O3:C crystals was developed and tested for in vivo absorbed dose measurements. It was shown that both entrance and exit doses could be measured and that the dosemeters did not disturb the reading of the mammograms. A Monte Carlo study showed that the energy dependence could be reduced, primarily by reducing the diameter of the crystal. It is proposed that radiation scattered forward towards the breast from the compression paddle, a scanning device etc, should be considered with greater clarity in the breast dosimetry protocols, and be described with a forward-scatter factor, FSF, for the various geometries and conditions proposed. Low contrast-detail (CD) phantoms of simulated glandularity 30, 50 or 70%, and thickness 3, 5 or 7 cm, were used to compare three different mammography systems. The same number of perceivable objects was visible for the full-field DM system at 20-60% of the AGD necessary for the screen-film (SFM) system, with the largest dose reduction potential for the thickest phantoms with the highest glandularity. However, more recent research shows that CD phantoms with a homogeneous background, as used here, must be used with care due to the presence of 'anatomical noise' in the real clinical situation. Image quality criteria (IQC) recommended in a European Guideline 1996 for SFM were adjusted to be relevant also for DM images. The new set of IQC was tested in two different studies using clinical images from DM and SFM, respectively. The results indicate that the new set of IQC has a higher discriminative power than the old set. The results also suggest that AGD for the DM system used may be reduced

  7. Evaluation of mean glandular dose in a full-field digital mammography unit in Tabriz, Iran.

    Science.gov (United States)

    Alizadeh Riabi, Hamed; Mehnati, Parinaz; Mesbahi, Asghar

    2010-12-01

    This study was aimed at evaluating the mean glandular dose (MGD) and affecting factors during mammography examinations by a full-field digital mammography unit. An extensive quality control program was performed to assure that the unit is properly working. Required information including compressed breast thickness (CBT), breast parenchymal pattern and technical factors used for imaging were recorded. An entrance skin exposure measurement was also performed using slabs of polymethylmethacrylate with 2-8 cm thickness. On the basis of recorded information and measured data, the MGD was estimated for 1145 mammography examinations obtained from 298 patients. Mean CBTs of 4.9 and 5.8 cm and MGDs of 2 and 2.4 mGy were observed for craniocaudal and mediolateral oblique views, respectively. Significant correlation was seen between MGD and CBT, breast parenchymal pattern and applied kVp and mAs. PMID:20823039

  8. Estimation of average glandular dose depending on the thickness of the breast

    International Nuclear Information System (INIS)

    Breast cancer is the most common type of cancer in women worldwide. Mammography is, to date, the most efficient method for detecting an abnormality in the patient's breast. It is a technique of imaging diagnostic that requires special care because radiographs without adequate quality may lead to a false diagnosis and lead to the need for a repeat examination, increasing the dose of radiation in the patient. This study aimed to evaluate the average glandular dose (AGD), depending on the breast thickness in patients undergoing routine tests, with a digital computer radiography processing system. Analyzed 30 exhibitions in patients aged (65 ± 12) years, in the right and left caudal skull projections, for breasts with thicknesses between 45 mm and 50 mm. The calculated value of the AGD for this track thickness was (1.600 ± 0.009) mGy. The performance of mammography quality control tests was satisfactory and the AGD values obtained for the chosen thickness range is acceptable, since the threshold achievable is 1.6 mGy and the acceptable is 2 mGy. In Brazil, it is only required the input dose calculation in skin for 45 mm breasts. However, the calculation of AGD is required for different thicknesses of the breast, to identify the best mammographic pattern aiming at better image quality at the lowest dose provided the patient

  9. Glandular dose and image quality control in mammography facilities with computerized radiography systems

    International Nuclear Information System (INIS)

    Breast cancer is the most common cancer among women, and early detection is critical to its diagnosis and treatment. To date, the most effective method for early detection of breast cancer has been x-ray mammography for which the screen/film (SF) technique has been the gold standard. However, even though SF combinations have been improved and optimized over the years for breast imaging, there are some critical limitations, including a narrow exposure range, image artifacts, film processing problems, and inflexibility in image processing and film management. In recent years, digital mammography has been introduced in cancer screening programmes with the screen/film techniques gradually being phased out. Computed radiography (CR), also commonly known as photostimulable phosphor (PSP) imaging or storage phosphor, employs reusable imaging plates and associated hardware and software to acquire and to display digital projection radiographs. In this work, a protocol model was tested for performing image quality control and average glandular dose (AGD) evaluation in 19 institutions with computed radiography systems for mammography. The protocol was validated through tests at the Laboratorio de Radioprotecao Aplicada a Mamografia (LARAM) from the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). The image quality visual evaluation of CDMAM phantom showed that 53% of the facilities were able to produce images of excellent quality. Furthermore, the automated evaluation of image quality, using the analyze software cdcom.exe, showed that 57% of the images were considered to be of good quality. The detector linearity test showed that the CR response is very linear, where 95% of facilities evaluated were considered to be compliant. For the image noise was found that only 20% of facilities are in agreement with the parameters established for this test. The average glandular doses, which patients may be getting to perform an examination, were below the action levels recommended by the European Protocol for Quality Assurance in Mammography Screening in 70% of the facilities. However, if acceptable levels were considered, the situation becomes complicated because more than half of the facilities have obtained doses above these levels. Moreover, for 50 mm PMMA thickness standard, the AGD was 87 % higher than in screen/film systems. (author)

  10. Mammography equipment performance, image quality and mean glandular dose in Malta.

    Science.gov (United States)

    Borg, M; Badr, I; Royle, G J

    2013-09-01

    In this first Maltese national mammography survey, the effectiveness of direct digital (DR) mammography in breast cancer screening has been confirmed. Patient data were made available from three clinics out of the participating nine. A dose survey of mean glandular dose (MGD) calculated for 759 patients examined in the state-owned mammography facilities was performed. An MGD national diagnostic reference level was set at 1.87 mGy for patients with breast compression thicknesses (BCT) between 5.0 and 7.0 cm. This range was selected since patient data were retrieved from three clinics only and the results showed that other international BCT reference levels may be unsuitable for the Maltese population. In fact, the overall average BCT was 5.75 ± 1.4 cm. The survey results have shown that the technical standard of mammographic equipment in the Malta National Breast Screening Programme is on a par with other countries, including its Western European counterparts. PMID:23525916

  11. Absorbed Doses to Patients in Nuclear Medicine

    International Nuclear Information System (INIS)

    The work with a Swedish catalogue of radiation absorbed doses to patients undergoing nuclear medicine investigations has continued. After the previous report in 1999, biokinetic data and dose estimates (mean absorbed dose to various organs and tissues and effective dose) have been produced for a number of substances: 11C- acetate, 11C- methionine, 18F-DOPA, whole antibody labelled with either 99mTc, 111In, 123I or 131I, fragment of antibody, F(ab')2 labelled with either 99mTc, 111In, 123I or 131I and fragment of antibody, Fab' labelled with either 99mTc, 111In, 123I or 131I. The absorbed dose estimates for these substances have been made from published biokinetic information. For other substances of interest, e.g. 14C-urea (children age 3-6 years), 14C-glycocholic acid, 14C-xylose and 14C-triolein, sufficient literature data have not been available. Therefore, a large number of measurements on patients and volunteers have been carried out, in order to determine the biokinetics and dosimetry for these substances. Samples of breast milk from 50 mothers, who had been subject to nuclear medicine investigations, have been collected at various times after administration of the radiopharmaceutical to the mother. The activity concentration in the breast milk samples has been measured. The absorbed dose to various organs and tissues and the effective dose to the child who ingests the milk have been determined for 17 different radiopharmaceuticals. Based on these results revised recommendations for interruption of breast-feeding after nuclear medicine investigations are suggested

  12. Estimates of Average Glandular Dose with Auto-modes of X-ray Exposures in Digital Breast Tomosynthesis

    Science.gov (United States)

    Kamal, Izdihar; Chelliah, Kanaga K.; Mustafa, Nawal

    2015-01-01

    Objectives: The aim of this research was to examine the average glandular dose (AGD) of radiation among different breast compositions of glandular and adipose tissue with auto-modes of exposure factor selection in digital breast tomosynthesis. Methods: This experimental study was carried out in the National Cancer Society, Kuala Lumpur, Malaysia, between February 2012 and February 2013 using a tomosynthesis digital mammography X-ray machine. The entrance surface air kerma and the half-value layer were determined using a 100H thermoluminescent dosimeter on 50% glandular and 50% adipose tissue (50/50) and 20% glandular and 80% adipose tissue (20/80) commercially available breast phantoms (Computerized Imaging Reference Systems, Inc., Norfolk, Virginia, USA) with auto-time, auto-filter and auto-kilovolt modes. Results: The lowest AGD for the 20/80 phantom with auto-time was 2.28 milliGray (mGy) for two dimension (2D) and 2.48 mGy for three dimensional (3D) images. The lowest AGD for the 50/50 phantom with auto-time was 0.97 mGy for 2D and 1.0 mGy for 3D. Conclusion: The AGD values for both phantoms were lower against a high kilovolt peak and the use of auto-filter mode was more practical for quick acquisition while limiting the probability of operator error. PMID:26052465

  13. Mammography quality control program in Tokai University Hospital. The measurement of half value layer and average glandular dose

    International Nuclear Information System (INIS)

    In late years, if importance of mammography rises with increase of, cancer of the breast and introduces mammography into, cancer of the breast examination, I reach it. Several many inspection items are nominated for quality control of mammography. Reduction of quantity of being affected by exposure dose is made in those as an important item. This is because I may give excessive exposure dose so that mammography uses soft X-ray. I add some references consideration about the measurement of; half value layer and Average Glandular Dose in these studies and report it. (author)

  14. Validation of mean glandular dose values provided by a digital breast tomosynthesis system in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Beraldo O, B.; Paixao, L.; Donato da S, S. [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Post-graduation in Sciences and Technology of Radiations Minerals and Materials, Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte (Brazil); Araujo T, M. H. [Dr Maria Helena Araujo Teixeira Clinic, Guajajaras 40, 30180-100 Belo Horizonte (Brazil); Nogueira, M. S., E-mail: bbo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear / CNEN, Pte. Antonio Carlos 6627, 31270-901 Belo Horizonte (Brazil)

    2014-08-15

    Digital breast tomosynthesis (DBT) is an emerging imaging modality that provides quasi-three-dimensional structural information of the breast and has strong promise to improve the differentiation of normal tissue and suspicious masses reducing the tissue overlaps. DBT images are reconstructed from a sequence of low-dose X-ray projections of the breast acquired at a small number of angles over a limited angular range. The Ho logic Selen ia Dimensions system is equipped with an amorphous Selenium (a-Se) detector layer of 250 ?m thickness and a 70 ?m pixel pitch. Studies are needed to determine the radiation dose of patients that are undergoing this emerging procedure to compare with the results obtained in DBT images. The mean glandular dose (D{sub G}) is the dosimetric quantity used in quality control of the mammographic systems. The aim of this work is to validate D{sub G} values for different breast thicknesses provided by a Ho logic Selen ia Dimensions system using a DBT mode in comparison with the same results obtained by a calibrated 90 X 5-6M-model Radcal ionization chamber. D{sub G} values were derived from the incident air kerma (K{sub i}) measurements and tabulated conversion coefficients that are dependent on the half value layer (HVL) of the X-ray spectrum. Voltage and tube loading values were recorded in irradiations using W/Al anode/filter combination, automatic exposure control mode and polymethyl methacrylate (PMMA) slabs which simulate different breast thicknesses. For K{sub i} measurements, the ionization chamber was positioned at 655 mm from the focus and the same radiographic technique values were selected with the manual mode. D{sub G} values for a complete procedure ranged from 0.9 ± 0.1 to 3.7 ± 0.4 mGy. The results for different breast thicknesses are in accordance with values obtained by DBT images and with acceptable levels established by the Commission of the European Communities (Cec) and the International Atomic Energy Agency (IAEA). This work contributes to determine the reliable radiation dose received by the patients and validate the values provided by this DBT system. (Author)

  15. Validation of mean glandular dose values provided by a digital breast tomosynthesis system in Brazil

    International Nuclear Information System (INIS)

    Digital breast tomosynthesis (DBT) is an emerging imaging modality that provides quasi-three-dimensional structural information of the breast and has strong promise to improve the differentiation of normal tissue and suspicious masses reducing the tissue overlaps. DBT images are reconstructed from a sequence of low-dose X-ray projections of the breast acquired at a small number of angles over a limited angular range. The Ho logic Selen ia Dimensions system is equipped with an amorphous Selenium (a-Se) detector layer of 250 ?m thickness and a 70 ?m pixel pitch. Studies are needed to determine the radiation dose of patients that are undergoing this emerging procedure to compare with the results obtained in DBT images. The mean glandular dose (DG) is the dosimetric quantity used in quality control of the mammographic systems. The aim of this work is to validate DG values for different breast thicknesses provided by a Ho logic Selen ia Dimensions system using a DBT mode in comparison with the same results obtained by a calibrated 90 X 5-6M-model Radcal ionization chamber. DG values were derived from the incident air kerma (Ki) measurements and tabulated conversion coefficients that are dependent on the half value layer (HVL) of the X-ray spectrum. Voltage and tube loading values were recorded in irradiations using W/Al anode/filter combination, automatic exposure control mode and polymethyl methacrylate (PMMA) slabs which simulate different breast thicknesses. For Ki measurements, the ionization chamber was positioned at 655 mm from the focus and the same radiographic technique values were selected with the manual mode. DG values for a complete procedure ranged from 0.9 ± 0.1 to 3.7 ± 0.4 mGy. The results for different breast thicknesses are in accordance with values obtained by DBT images and with acceptable levels established by the Commission of the European Communities (Cec) and the International Atomic Energy Agency (IAEA). This work contributes to determine the reliable radiation dose received by the patients and validate the values provided by this DBT system. (Author)

  16. SU-E-I-04: A Mammography Phantom to Measure Mean Glandular Dose and Image Quality

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Pineda, E; Ruiz-Trejo, C; E, Brandan M [Instituto de Fisica UNAM, Mexico City, DF (Mexico)

    2014-06-01

    Purpose: To evaluate mean glandular dose (MGD) and image quality in a selection of mammography systems using a novel phantom based on thermoluminescent dosemeters and the ACR wax insert. Methods: The phantom consists of two acrylic, 19 cm diameter, 4.5 cm thick, semicircular modules, used in sequence. The image quality module contains the ACR insert and is used to obtain a quality control image under automatic exposure conditions. The dosimetric module carries 15 TLD-100 chips, some under Al foils, to determine air kerma and half-value-layer. TL readings take place at our laboratory under controlled conditions. Calibration was performed using an ionization chamber and a Senographe 2000D unit for a variety of beam qualities, from 24 to 40 kV, Mo and Rh anodes and filters. Phantom MGD values agree, on the average, within 3% with ionization chamber data, and their precision is better than 10% (k=1). Results: MGD and image quality have been evaluated in a selection of mammography units currently used in Mexican health services. The sample includes analogic (screen/film), flexible digital (CR), and full-field digital image receptors. The highest MDG are associated to the CR technology. The most common image quality failure is due to artifacts (dust, intensifying screen scratches, and processor marks for film/screen, laser reader defects for CR). Conclusion: The developed phantom permits the MGD measurement without the need of a calibrated ionization chamber at the mammography site and can be used by a technician without the presence of a medical physicist. The results indicate the urgent need to establish quality control programs for mammography.

  17. SU-E-I-04: A Mammography Phantom to Measure Mean Glandular Dose and Image Quality

    International Nuclear Information System (INIS)

    Purpose: To evaluate mean glandular dose (MGD) and image quality in a selection of mammography systems using a novel phantom based on thermoluminescent dosemeters and the ACR wax insert. Methods: The phantom consists of two acrylic, 19 cm diameter, 4.5 cm thick, semicircular modules, used in sequence. The image quality module contains the ACR insert and is used to obtain a quality control image under automatic exposure conditions. The dosimetric module carries 15 TLD-100 chips, some under Al foils, to determine air kerma and half-value-layer. TL readings take place at our laboratory under controlled conditions. Calibration was performed using an ionization chamber and a Senographe 2000D unit for a variety of beam qualities, from 24 to 40 kV, Mo and Rh anodes and filters. Phantom MGD values agree, on the average, within 3% with ionization chamber data, and their precision is better than 10% (k=1). Results: MGD and image quality have been evaluated in a selection of mammography units currently used in Mexican health services. The sample includes analogic (screen/film), flexible digital (CR), and full-field digital image receptors. The highest MDG are associated to the CR technology. The most common image quality failure is due to artifacts (dust, intensifying screen scratches, and processor marks for film/screen, laser reader defects for CR). Conclusion: The developed phantom permits the MGD measurement without the need of a calibrated ionization chamber at the mammography site and can be used by a technician without the presence of a medical physicist. The results indicate the urgent need to establish quality control programs for mammography

  18. Image quality, threshold contrast and mean glandular dose in CR mammography

    International Nuclear Information System (INIS)

    In many countries, computed radiography (CR) systems represent the majority of equipment used in digital mammography. This study presents a method for optimizing image quality and dose in CR mammography of patients with breast thicknesses between 45 and 75 mm. Initially, clinical images of 67 patients (group 1) were analyzed by three experienced radiologists, reporting about anatomical structures, noise and contrast in low and high pixel value areas, and image sharpness and contrast. Exposure parameters (kV, mAs and target/filter combination) used in the examinations of these patients were reproduced to determine the contrast-to-noise ratio (CNR) and mean glandular dose (MGD). The parameters were also used to radiograph a CDMAM (version 3.4) phantom (Artinis Medical Systems, The Netherlands) for image threshold contrast evaluation. After that, different breast thicknesses were simulated with polymethylmethacrylate layers and various sets of exposure parameters were used in order to determine optimal radiographic parameters. For each simulated breast thickness, optimal beam quality was defined as giving a target CNR to reach the threshold contrast of CDMAM images for acceptable MGD. These results were used for adjustments in the automatic exposure control (AEC) by the maintenance team. Using optimized exposure parameters, clinical images of 63 patients (group 2) were evaluated as described above. Threshold contrast, CNR and MGD for such exposure parameters were also de for such exposure parameters were also determined. Results showed that the proposed optimization method was effective for all breast thicknesses studied in phantoms. The best result was found for breasts of 75 mm. While in group 1 there was no detection of the 0.1 mm critical diameter detail with threshold contrast below 23%, after the optimization, detection occurred in 47.6% of the images. There was also an average MGD reduction of 7.5%. The clinical image quality criteria were attended in 91.7% for all breast thicknesses evaluated in both patient groups. Finally, this study also concluded that the use of the AEC of the x-ray unit based on the constant dose to the detector may bring some difficulties to CR systems to operate under optimal conditions. More studies must be performed, so that the compatibility between systems and optimization methodologies can be evaluated, as well as this optimization method. Most methods are developed for phantoms, so comparative studies including clinical images must be developed. (paper)

  19. Image quality, threshold contrast and mean glandular dose in CR mammography

    Science.gov (United States)

    Jakubiak, R. R.; Gamba, H. R.; Neves, E. B.; Peixoto, J. E.

    2013-09-01

    In many countries, computed radiography (CR) systems represent the majority of equipment used in digital mammography. This study presents a method for optimizing image quality and dose in CR mammography of patients with breast thicknesses between 45 and 75 mm. Initially, clinical images of 67 patients (group 1) were analyzed by three experienced radiologists, reporting about anatomical structures, noise and contrast in low and high pixel value areas, and image sharpness and contrast. Exposure parameters (kV, mAs and target/filter combination) used in the examinations of these patients were reproduced to determine the contrast-to-noise ratio (CNR) and mean glandular dose (MGD). The parameters were also used to radiograph a CDMAM (version 3.4) phantom (Artinis Medical Systems, The Netherlands) for image threshold contrast evaluation. After that, different breast thicknesses were simulated with polymethylmethacrylate layers and various sets of exposure parameters were used in order to determine optimal radiographic parameters. For each simulated breast thickness, optimal beam quality was defined as giving a target CNR to reach the threshold contrast of CDMAM images for acceptable MGD. These results were used for adjustments in the automatic exposure control (AEC) by the maintenance team. Using optimized exposure parameters, clinical images of 63 patients (group 2) were evaluated as described above. Threshold contrast, CNR and MGD for such exposure parameters were also determined. Results showed that the proposed optimization method was effective for all breast thicknesses studied in phantoms. The best result was found for breasts of 75 mm. While in group 1 there was no detection of the 0.1 mm critical diameter detail with threshold contrast below 23%, after the optimization, detection occurred in 47.6% of the images. There was also an average MGD reduction of 7.5%. The clinical image quality criteria were attended in 91.7% for all breast thicknesses evaluated in both patient groups. Finally, this study also concluded that the use of the AEC of the x-ray unit based on the constant dose to the detector may bring some difficulties to CR systems to operate under optimal conditions. More studies must be performed, so that the compatibility between systems and optimization methodologies can be evaluated, as well as this optimization method. Most methods are developed for phantoms, so comparative studies including clinical images must be developed.

  20. Dose absorbed in adults and children thyroid due to the I123 using the dosimetry MIRD and Marinelli

    International Nuclear Information System (INIS)

    Using the dosimetry MIRD, and representation Cristy-Eckerman in the thyroid gland and organs of their bio-kinetics when I123 (Iodine) is used, the study demonstrates that the absorbed dose by the gland of an adult, children, and newly born, is their auto-dose, independent of the compartments number of their bio-kinetics. The dosimetric contributions of the organs of their bio-kinetics are insignificant. Their results are not significantly different to those obtained by the formalism MARINELLI (auto-dose) when it uses a sphere like glandular representation. In consequence, the kinetic model corresponding to the glandular representation decreases to a compartment, where the gland can also be represented like a sphere. (Author)

  1. Neutron absorbed dose in a pacemaker CMOS

    Scientific Electronic Library Online (English)

    C.G., Borja-Hernández; K.A., Guzmán-García; C., Valero-Luna; A., Bañuelos-Frías; L., Paredes-Gutiérrez; V.M., Hernández-Dávila; H.R., Vega-Carrillo.

    2012-06-01

    Full Text Available El espectro y la dosis absorbida, debida a neutrones, por un Semiconductor de Óxido Meta´lico Complementario ha sido estimada utilizando métodos Monte Carlo. Eventualmente, una persona con marcapasos se convierte en un paciente oncológico que debe ser tratado en un acelerador lineal. El marcapasos [...] contiene circuitos integrados como los CMOS que son sensibles a los campos de radiaci ón intensos y pulsados. El haz terapéutico de un LINAC operando a voltajes mayores a 7 MV está contaminado con fotoneutrones que pueden dañar el CMOS. En este trabajo se estimó el espectro de neutrones y la dosis absorbida por un CMOS; además, se calcularon los espectros de neutrones en dos detectores puntuales ubicados dentro de la sala. El espectro de neutrones en el CMOS tiene un pico entre 0.1 y 1 MeV y otro en la región de los térmicos, conectados mediante neutrones epitérmicos. Estas mismas características se observan en los otros detectores. La dosis absorbida por el CMOS es 1:522 x 10-17 Gy por cada neutrón emitido por el término fuente. Abstract in english The neutron spectrum and the absorbed dose in a Complementary Metal Oxide Semiconductor, has been estimated using Monte Carlo methods. Eventually a person with a pacemaker becomes an oncology patient that must be treated in a linear accelerator. Pacemaker has integrated circuits as CMOS that are sen [...] sitive to intense and pulsed radiation fields. Above 7 MV therapeutic beam is contaminated with photoneutrons that could damage the CMOS. Here, the neutron spectrum and the absorbed dose in a CMOS cell was calculated, also the spectra were calculated in two point-like detectors in the room. Neutron spectrum in the CMOS cell shows a small peak between 0.1 to 1 MeV and a larger peak in the thermal region, joined by epithermal neutrons, same features were observed in the point-like detectors. The absorbed dose in the CMOS was 1:522 x 10-17 Gy per neutron emitted by the source.

  2. Determination of absorbed dose in reactors

    International Nuclear Information System (INIS)

    There are many areas in the use and operation of research reactors where the absorbed dose and the neutron fluence are required. These include work on the determination of the radiolytic stability of the coolant and moderator and on the determination of radiation damage in structural materials, and reactor experiments involving radiation chemistry and radiation biology. The requirements range from rough estimates of the total heating due to radiation to precise values specifying the contributions of gamma rays, thermal neutrons and fast neutrons. To meet all these requirements a variety of experimental measurements and calculations as well as a knowledge of reactor radiations and their interactions is necessary. Realizing the complexity and importance of this field, its development at widely separated laboratories and the need to bring the experts in this work together, the IAEA has convened three panel meetings. These were: 'In-pile dosimetry', held in July 1964 (published by the Agency as Technical Reports Series No. 46); 'Neutron fluence measurements', in October 1965; and 'In-pile dosimetry', in November 1966. The recommendations of these three panels led the Agency to form a Working Group on Reactor Radiation Measurements and to commission the writing of this book and a book on Neutron Fluence Measurements. The latter was published in May 1970 (Technical Reports Series No. 107). The material on neutron fluence and absorbed dose measurements is widely scattered in reports and reviews. It was considered that it was time for all relevant information to be evaluated and put together in the form of a practical guide that would be valuable both to experienced workers and beginners in the field

  3. The BIPM Graphite Calorimeter Standard for Absorbed Dose to Water

    International Nuclear Information System (INIS)

    The BIPM has constructed a graphite calorimeter for use as a primary standard for absorbed dose. It is employed to measure absorbed dose to water in the BIPM 60Co reference beam and in accelerator photon beams. It is currently in use for a series of international comparisons of absorbed dose to water in the accelerator photon beams of national metrology institutes. The paper describes the BIPM calorimeter and presents some recent results. (author)

  4. Determination of Absorbed Dose Using a Dosimetric Film

    International Nuclear Information System (INIS)

    This paper presents the absorbed dose measurements by means of the irradiated dosimetric reference films. The dose distributions were made by MULTIDATA film densitometer using RTD-4 software, in INFLPR Linear Accelerator Department

  5. Forward-scattered radiation from the compression paddle should be considered in glandular dose estimations

    International Nuclear Information System (INIS)

    From major protocols on dosimetry in mammography, there is no doubt that the incident air kerma should be evaluated without backscattered radiation to the dosemeter. However, forward-scattered radiation from the compression paddle is neglected. The aim of this work was to analyse the contribution of forward-scattered radiation for typical air kerma measurements. Measurements of forward-scatter were performed with a plane-parallel ionisation chamber on four mammography units. The forward-scatter contribution to the air kerma was 2-10 % and increased with the compression paddle thickness, but also with the half-value layer value. For incident air kerma in mammography, it can be as important to consider forward scattered as backscattered radiation. If an ionisation chamber is used, the compression paddle should be in contact with the chamber; otherwise the air kerma and absorbed dose will be underestimated. If a dosemeter based on semiconductors with much less sensitivity to scattered radiation is used, it is suggested that a forward-scatter factor (FSF) is applied. Based on the results of this work, FSF=1.06 will lead to a maximum error of ?4 %. (authors)

  6. Absorbed dose measurements in mammography using Monte Carlo method and ZrO2+PTFE dosemeters

    International Nuclear Information System (INIS)

    Mammography test is a central tool for breast cancer diagnostic. In addition, programs are conducted periodically to detect the asymptomatic women in certain age groups; these programs have shown a reduction on breast cancer mortality. Early detection of breast cancer is achieved through a mammography, which contrasts the glandular and adipose tissue with a probable calcification. The parameters used for mammography are based on the thickness and density of the breast, their values depend on the voltage, current, focal spot and anode-filter combination. To achieve an image clear and a minimum dose must be chosen appropriate irradiation conditions. Risk associated with mammography should not be ignored. This study was performed in the General Hospital No. 1 IMSS in Zacatecas. Was used a glucose phantom and measured air Kerma at the entrance of the breast that was calculated using Monte Carlo methods and ZrO2+PTFE thermoluminescent dosemeters, this calculation was completed with calculating the absorbed dose. (author)

  7. Comportamento da dose glandular versus contraste do objeto em mamografia: determinação de formalismo semi-empírico para diferentes combinações alvo-filtro / Behavior of subject contrast versus glandular dose in mammography: determination of a semi-empirical formalism for different target-filter combinations

    Scientific Electronic Library Online (English)

    Gabriela, Hoff; Carlos Eduardo de, Almeida; Gary T., Barnes.

    2006-06-01

    Full Text Available OBJETIVO: Verificar o efeito da mudança no contraste do objeto, tempo de exposição e dose de radiação quando diferentes espessuras de filtração de molibdênio (Mo) e ródio (Rh) são empregadas em mamógrafos. MATERIAIS E MÉTODOS: Realizaram-se medidas da exposição na entrada da pele com uma câmara de i [...] onização para diferentes espessuras para os filtros de Mo e Rh. Para determinar a dose glandular média foi utilizado simulador de BR12 (50% tecido adiposo e 50% tecido glandular) de diferentes espessuras (4 cm e 8 cm). Energias na faixa de 24 kVp a 34 kVp foram empregadas e filmes Kodak MinR 2000 foram utilizados. RESULTADOS: Os resultados evidenciaram dados de contraste do objeto, dose glandular e tempo de exposição para diferentes espessuras de filtros adicionais e diferentes tensões. Esses dados indicaram aumento nos valores de contraste do objeto e tempo de exposição, com o aumento da espessura dos filtros. A dose glandular apresentou comportamento com diferentes tendências para cada caso analisado. Equações foram definidas para possibilitar a estimativa do contraste do objeto, dose glandular e tempo de exposição para os casos estudados. CONCLUSÃO: Os resultados possibilitaram a estimativa de equações que auxiliam na verificação do comportamento do contraste do objeto e da dose glandular para simuladores com espessura de 4 cm e 8 cm e para os filtros de Rh e Mo. Dessa forma, torna-se possível estimar a figura de mérito (razão entre o contraste do objeto e a dose glandular), podendo auxiliar na análise da relação risco-benefício dos casos estudados. Abstract in english OBJECTIVE: Our purpose was to verify the effect of changes in subject contrast, exposure time and radiation dose when different thicknesses of molybdenum (Mo) and rhodium (Rh) filters are used in mammography equipments. MATERIALS AND METHODS: Entrance skin exposure measurements were performed with a [...] n ionization chamber for different thicknesses of Mo and Rh filters. Average glandular dose was determined with a BR12 simulator (50% fat tissue and 50% glandular tissue) of different thicknesses (4 cm and 8 cm). Energies in the range of 24 to 34 kVp and Kodak MinR 2000 films were used. RESULTS: Results have evidenced data on subject contrast data, glandular dose and exposure time for different thicknesses of additional filters and different kVp values. These data have indicated an increase both in values of subject contrast and exposure time when filters thickness is increased. The glandular dose has presented a different behavior tendency for each case analyzed. Equations were defined to allow us to estimate subject contrast, glandular dose and exposure time for the cases studied. CONCLUSION: The results have made possible to define equations to assist with the evaluation of subject contrast and glandular dose behavior in simulators with 4 cm and 8 cm thicknesses and for Rh and Mo additional filters. In this way, it is possible to estimate the figure of merit (subject contrast/glandular dose ratio) to assist in the risk-benefit analysis of the cases studied.

  8. In vivo dosimetry for head and neck carcinoma: Determination of target absorbed dose from entrance and exit absorbed dose measurements

    International Nuclear Information System (INIS)

    Full text: Measurement of the absorbed dose in a target volume is widely considered to be an important tool for quality assurance in external radiotherapy. The aims of this work were to measure the entrance and exit doses for patients treated for head and neck tumors. The target absorbed dose was determined from the exit and entrance dose measurement Twenty patients were evaluated. Initially, measurements with commercial diodes were performed on a polystyrene phantom in order to calibrate diodes in terms of entrance and exit doses; and to determine appropriate correction factors. The results were compared to the calculated values, and the midline dose was determinate and compared with the prescribed dose. 100 entrance dose and 100 exit dose measurements were performed. The average difference from expected values was 1,2 % for entrance dose (SD 2,9%) and 0,5 % for exit dose (SD 5,3%). The target absorbed dose differed from prescribed dose values by 2.5% (2.8 %) for the results using the Noel method and 3 % (SD:3.2 %) with the Rizzotti method. The total uncertainty budget in the measurement of the absorbed entrance and exit dose with diode, including diode reading, correction factors and diode calibration coefficient, is determined as 3 % (1 SD). Simple in vivo dose measurements are an additional safeguard against major setup errors and calculation or transcription errors that can be missed during pre-treatment chart check

  9. Glandular dose and image quality control in mammography facilities with computerized radiography systems; Dose glandular e controle de qualidade da imagem em servicos de mamografia com sistema de radiografia computadorizada

    Energy Technology Data Exchange (ETDEWEB)

    Dantas, Marcelino Vicente de Almeida

    2010-07-01

    Breast cancer is the most common cancer among women, and early detection is critical to its diagnosis and treatment. To date, the most effective method for early detection of breast cancer has been x-ray mammography for which the screen/film (SF) technique has been the gold standard. However, even though SF combinations have been improved and optimized over the years for breast imaging, there are some critical limitations, including a narrow exposure range, image artifacts, film processing problems, and inflexibility in image processing and film management. In recent years, digital mammography has been introduced in cancer screening programmes with the screen/film techniques gradually being phased out. Computed radiography (CR), also commonly known as photostimulable phosphor (PSP) imaging or storage phosphor, employs reusable imaging plates and associated hardware and software to acquire and to display digital projection radiographs. In this work, a protocol model was tested for performing image quality control and average glandular dose (AGD) evaluation in 19 institutions with computed radiography systems for mammography. The protocol was validated through tests at the Laboratorio de Radioprotecao Aplicada a Mamografia (LARAM) from the Centro de Desenvolvimento da Tecnologia Nuclear (CDTN). The image quality visual evaluation of CDMAM phantom showed that 53% of the facilities were able to produce images of excellent quality. Furthermore, the automated evaluation of image quality, using the analyze software cdcom.exe, showed that 57% of the images were considered to be of good quality. The detector linearity test showed that the CR response is very linear, where 95% of facilities evaluated were considered to be compliant. For the image noise was found that only 20% of facilities are in agreement with the parameters established for this test. The average glandular doses, which patients may be getting to perform an examination, were below the action levels recommended by the European Protocol for Quality Assurance in Mammography Screening in 70% of the facilities. However, if acceptable levels were considered, the situation becomes complicated because more than half of the facilities have obtained doses above these levels. Moreover, for 50 mm PMMA thickness standard, the AGD was 87 % higher than in screen/film systems. (author)

  10. An Investigation of Mean Glandular Dose from Routine Mammography in Urmia, Northwestern Iran and the Factors Affecting It

    Directory of Open Access Journals (Sweden)

    Leili rahmatnezhad

    2012-09-01

    Full Text Available The objective of this study was to determine the Mean Glandular Dose (MGD resulting from Craniocaudal (CC and Mediolateral oblique (MLO views in one breast and the total dose per woman in Urmia, northwestern Iran and to identify the factors affecting it. This study was conducted during 9 months to estimate the MGD for women undergoing mammography and to report the distribution of dose. The clinical data were collected from 460 mammograms taken from 230 women who were referred to radiology center of Imam Reza hospital in Urmia. The piranha system version 3.8A was used for determining the MGD in this work. The MGD values are based on measurements of ESAK (entrance surface air krema and HVL. Significant differences were found between MGD from CC and MLO views. The mean±SD MGD per film was 1.18±0.38 mGy for craniocaudal and 1.39±0.51 mGy for mediolateral oblique views, (p<0.001. The mean±SD MGD per woman was 2.57±0.44 mGy. The mean± SD MGD per film in present study were lower than most of similar reports. The dose values obtained fall within the internationally acceptable dose range of 1-3mGy. This suggests mammography x-ray generators in this part of the country are capable of achieving acceptable dose levels for patient safety. Therefore, with considering the all other factors, the establishment of screening mammography program is achievable.

  11. Dosimetric evaluation of carbon fiber tabletop on absorbed doses

    International Nuclear Information System (INIS)

    Objective: To evaluate the dosimetric effect of carbon fiber tabletop on the patient doses in radiotherapy. Methods: The transmission factors of couch and inserts were measured in air and solid water phantom using 0.6 cm3 ion chamber and PTW 2D ion chamber array for 6 MV, 10 MV and 18 MV X-ray, respectively. Absorbed doses at depth of maximum dose, 5 cm and 10 cm in solid water were measured with the 2D ion chamber array. Absorbed doses fluctuations with different gantry angles and air gaps between phantom and couch were also measured. Results: The posterior field measurement showed that the reductions of absorbed doses at the depth maximum dose, 5 cm and 10 cm were within 5%. The ratios of the absorbed doses with to without couch increased with the oblique incident angles and varied slightly with the air gap at depth of 5 cm. The transmission factors of inserts were less than those of couch owing to its thinner thickness. Conclusion: The carbon-fiber tabletop affects the absorbed doses and dose distributions of the target, and this effect changes with the gantry angle and air gap. Special considerations should be taken during treatment planning. (authors)

  12. Fast neutron radiation inactivation of Bacillus subtilis: Absorbed dose determination

    International Nuclear Information System (INIS)

    In this paper, fast neutron inactivation effects of Bacillus subtilis were investigated with fission fast neutrons from CFBR-II reactor of INPC (Institute of Nuclear Physics and Chemistry) and mono-energetic neutrons from the Van de Graaff accelerator at Peking University. The method for determining the absorbed dose in the Bacillus subtilis suspension contained in test tubes is introduced. The absorbed dose, on account of its dependence on the volume and the form of confined state, was determined by combined experiments and Monte Carlo method. Using the calculation results of absorbed dose, the fast neutron inactivation effects on Bacillus subtilis were studied. The survival rates and absorbed dose curve was constructed. (authors)

  13. Specification of absorbed dose for reporting a therapeutic irradiation

    International Nuclear Information System (INIS)

    The problem of dose specification in external beam therapy with photons and electrons has been dealt with in ICRU Report 29 (1978). This problem arises from the fact that the absorbed dose distribution is usually not uniform in the target volume and that for the purpose of treatment reporting a nominal absorbed dose - which will be called target absorbed dose - has to be selected. When comparing the clinical results obtained between radiotherapy centres, the differences in the reported target absorbed doses which can be introduced by differences in the methods of dose specification often are much larger than the differences related to the dosimetric procedures themselves. This shows the importance of the problem. In this paper, some definitions of terms and concepts currently used in radiotherapy are first recalled: tumour volume, target volume, treatment volume, etc. These definitions have been proposed in ICRU Report 29 for photon and electron beams; they can be extended to any kind of irradiation. For external beam therapy with photons and electrons, the target absorbed dose is defined as the absorbed dose at selected point(s) (specification point(s)) having a meaningful relation to the target volume and/or the irradiation beams. Examples are discussed for typical cases. As far as interstitial and intracavitary therapy is concerned, the problem is more complex and no recommendations have so far been made by the ICRU Commission. A major difficulty arises from the sharp dose gradient as a function of the distance to the sources. The particular case of the treatment of cervix carcinoma is considered and some possible methods of specification are discussed: (1) the indication of the sources (in adequate units) and the duration of the application, (2) the absorbed doses at selected reference points (bladder, rectum, bony structures) and (3) the description of the tissue volume (height, width, thickness) encompassed by a given isodose surface (60Gy). (author)

  14. Fetal absorbed doses by radiopharmaceutical administration

    International Nuclear Information System (INIS)

    The radiopharmaceutical administration with diagnostic or therapeutic purpose during pregnancy implies a prenatal radiation dose. The dose assessment and the evaluation of the radiological risks become relevant due to the great radiosensitivity of the fetal tissues in development. This paper is a revision of the available data for estimating fetal doses in the cases of the more frequently used radiopharmaceuticals in nuclear medicine, taking into account recent investigation in placental crossover. The more frequent diagnostic and therapeutic procedures were analyzed according to the radiation doses implied. (author)

  15. Sensitive temperature sensors for use in absorbed dose calorimetry

    International Nuclear Information System (INIS)

    The use of optical fibres in absorbed dose calorimetry is discussed. In hybrid detectors a separate element is used as a temperature sensor and optical fibres are used to transmit the signal. In integrated detectors the optical fibre acts as the sensing element as well as transmitting information. It is estimated that absorbed doses may be measurable using optical fibre techniques with 100 times more accuracy than is currently possible using thermistor techniques

  16. In vivo dosimetry for head and neck carcinoma: determination of target absorbed dose from entrance and exit absorbed dose measurements

    International Nuclear Information System (INIS)

    The aims of this work were to measure the entrance and exit dose for patient treated for head and neck tumors. The target absorbed dose was determined from the exit and entrance dose measurement. Twenty patients were evaluated. The results were compared to the calculated values and the midline dose was determinate and compared with the prescribed dose. 80 entrance doses and 80 exit doses measurements were performed. The average difference from expected values was 1.93% for entrance dose (SD 1.92%) and -0.34% for exit dose (SD 4.1%). The target absorbed dose differed from prescribed dose values by 2.94% (1.97%) for the results using the Noel method and 3.34% (SD: 2.29%) with the Rizzotti method. The total uncertainty budget in the measurement of the absorbed entrance and exit dose with diode, including diode reading, correction factors and diode calibration coefficient, is determined as 3.02% (1 s). Simple in vivo dose measurements are an additional safeguard against major setup errors and calculation or transcription errors that were missed during pre-treatment chart check. (authors)

  17. In vivo dosimetry for head and neck carcinoma: determination of target absorbed dose from entrance and exit absorbed dose measurements

    Energy Technology Data Exchange (ETDEWEB)

    Farhat, L.; Daoud, J. [Service de radiotherapie carcinologique, CHU Habib-Bourguiba, 3029 Sfax (Tunisia); Besbes, M. [Service de radiotherapie carcinologique, Institut Salah-Azaiz, Boulevard du 9-avril-Bab-Saadoun, 1006 Tunis (Tunisia); Bridier, A. [Service de radiophysique, Institut Gustave-Roussy, 39 rue Camille-Desmoulins, 94805 Villejuif Cedex (France)

    2011-04-15

    The aims of this work were to measure the entrance and exit dose for patient treated for head and neck tumors. The target absorbed dose was determined from the exit and entrance dose measurement. Twenty patients were evaluated. The results were compared to the calculated values and the midline dose was determinate and compared with the prescribed dose. 80 entrance doses and 80 exit doses measurements were performed. The average difference from expected values was 1.93% for entrance dose (SD 1.92%) and -0.34% for exit dose (SD 4.1%). The target absorbed dose differed from prescribed dose values by 2.94% (1.97%) for the results using the Noel method and 3.34% (SD: 2.29%) with the Rizzotti method. The total uncertainty budget in the measurement of the absorbed entrance and exit dose with diode, including diode reading, correction factors and diode calibration coefficient, is determined as 3.02% (1 s). Simple in vivo dose measurements are an additional safeguard against major setup errors and calculation or transcription errors that were missed during pre-treatment chart check. (authors)

  18. Evaluation of the absorbed dose in odontological computerized tomography

    International Nuclear Information System (INIS)

    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

  19. Absorbed doses to patients from angioradiology

    International Nuclear Information System (INIS)

    The aim of study was to know patients doses exposes when three different procedures of angioradiology were carried out. The explorations considered were drainage biliary, varicocele embolization and dacriocistography made in the Radiodiagnostic Service at the University Hospital of Canary Islands, Tenerife (Spain). In total 14 patients were studied. The measurements were made using large area transmission ionisation chamber which gives the values of Dose Area Product (DAP). In addition, thermoluminescent dosimeters type TLD-100 were used in anthropomorphic phantom in order to obtain values of organ doses when the phantom was submitted to the same procedures rather than the actual patients. Furthermore, the Effdose program was used to estimate the effective doses in the procedures conditions. The values for DAP were in the range of 70-300 for drainage biliary, 43-180 for varicocele embolization and 1.4-9 for dacriocistography. The organ doses measured with TLD-100 were higher than the corresponding values estimated by Effdose program. The results for varicocele embolization were higher than other published data. In the case of drainage biliary procedure, the values were closed to other published results. It was not possible to find data for dacriocistography from other authors. (author)

  20. Effect of backscatter factor on absorbed dose in radiotherapy

    International Nuclear Information System (INIS)

    This paper is to study how the absorbed dose was affected by the organ backscatter caused in radiotherapy. With the change of radiation energy, back organ depth, different back organ material type, the backscatter factor (Bs) was determined by measuring absolute dose compared with 1 cm depth of back solid water. The actual absorbed dose was really affected by the back organ depth in radiotherapy. The Bs value increased with the increase of radiation energy, back organ depth. The absorbed dose to organ or tumor should be modified with the measured Bs based on the depth of back tissue of the tumor, back organ material type, radiation energy, so as to improve the effect of radiotherapy and to be able to protect normal tissue. (authors)

  1. Review of calorimeter-based absorbed dose to water standards

    International Nuclear Information System (INIS)

    The major techniques currently used at standards laboratories for the realization of the quantity absorbed-dose to water, can be grouped in three distinct classes: (1) ionization chamber-based absorbed-dose standards, (2) total absorption-based absorbed-dose standards, and (3) absorbed-dose calorimeter-based standards. Over the last two decades, however, water calorimeters have gained considerable interest and research has shown that estimated uncertainties using water calorimeter standards have become competitive with those associated with graphite calorimeter standards. In this paper, we review graphite calorimeter and water calorimeter-based absorbed dose to water standards. Although both techniques belong to the same class, the difference in details and approaches are so dramatic that each of the methods can be considered largely independent from the other. This review focuses on absorbed-dose calorimeter standards in high energy photon and electron beams. Graphite calorimeter-based standards Graphite calorimeters are multi-body systems where, using sensors (thermistors), the average temperature rise is measured in a central body or core that is thermally isolated from its surrounding bodies (jackets) by vacuum gaps. The system can be calibrated by dissipating a known amount of electrical energy in its bodies and measuring the corresponding temperature rise. There are three major modes of operation: (1) the quasi adiabatic mode, in which the core and the jacket temperature are raised at the same rate so as to minimize heat-loss from the core; (2) the heat-loss compensated mode, in which the heat-loss from the core is quantified by summing core and jacket signals and (3) the isothermal mode of operation, in which the heat-loss from the core is kept constant and such that its temperature drift is zero. Since graphite is an efficient conductor, the temperature variations from point to point within a body are usually ignored and the thermal behaviour of the system can be relatively easily modeled once the heat transfer coefficients between the different bodies as well as the specific heat capacities of the bodies have been determined. Determination of absorbed dose to graphite requires corrections for the effect of the gaps in the calorimeter. Absorbed dose to graphite needs to be converted into absorbed-dose to water and to this end scaling techniques or ionization chamber-based methods are being used. Although a frequently used calorimeter design at standards laboratories is that of Domen, different graphite calorimeter types have been constructed for different purposes. Estimates of typical relative (%) standard uncertainties in absorbed dose to graphite for high energy photon beams as achieved with state-of-the-art traditional graphite calorimetry are summarized. We conclude that typical standard uncertainties of absorbed dose to graphite at standards laboratories are of the order of 0.5%. The dose conversion procedure to derive absorbed dose to water from this may typically add an uncertainty of 0.3% to this figure. In contrast to water calorimetry, graphite calorimeters have been widely used for electron beam dosimetry. Areas of continued development are technical investigations into the accuracy of the electrical calibration and the development of portable systems that can be used directly in clinical beams. Water calorimeter-based standards Early water calorimeters tested at standards laboratories were small, stirred water calorimeters and were instrumental in understanding the radiation chemistry of water. In the beginning of the eighties however Domen showed that, as a result of the low thermal diffusivity of water, absorbed dose to water could be practically derived from the measured temperature rise at a point in continuous water. Water calorimetry relies on an accurate knowledge of the specific heat capacity of water under standard, constant-pressure conditions. The calibration of a water calorimeter involves a calibration of the sensors (thermistors) in terms of an absolute temperature difference rather tha

  2. Can the average glandular dose in routine digital mammography screening be reduced? A pilot study using revised image quality criteria

    International Nuclear Information System (INIS)

    There is a need for tools that in a simple way can be used for the evaluation of image quality related to clinical requirements in mammography. The aim of this work was to adjust the present European image quality criteria to be relevant also for digital mammography images, and to use as simple and as few criteria as possible. A pilot evaluation of the new set of criteria was made with mammograms of 28 women from a General Electric Senographe 2000D full-field digital mammography system. One breast was exposed using the standard automatic exposure mode, the other using about half of that absorbed dose. Three experienced radiologists evaluated the images using visual grading analysis technique. The results indicate that the new quality criteria can be used for the evaluation of image quality related to clinical requirements in digital mammography in a simple way. The results also suggest that absorbed doses for the mammography system used may be substantially reduced. (authors)

  3. Comparison of absorbed doses resulting from various intraoral periapical radiography

    International Nuclear Information System (INIS)

    This study was designed to measure the absorbed dose to organs of special interest from full mouth with intraoral film (14 films) and to compare the five periapical techniques. Thermoluminescent crystals (TLD-100 chip) were located in brain, orbit, bone marrow of mandibular ramus, bone marrow of mandibular body, bone marrow of 4th cervical spine, parotid gland, submandibular gland and thyroid gland. X-ray machine was operated at 70 kVp and round collimating film holding device (XCP) and rectangular collimating film holding device (Precision Instrument) were used. The distance from the X-ray focus to the open end of the collimator was 8 inch, 12 inch and 16 inch. The following results obtained; 1. The absorbed dose was the highest in bone marrow of mandibular body (5.656 mGy) and the lowest in brain (0.050 mGy). 2. Generally, the lowest absorbed dose was measured from 16 inch cylinder, rectangular collimating film holding device with paralleling technique. But, in bone marrow of mandibular body and the floor of mouth, the highest absorbed dose was measured from 12 inch cylinder, rectangular collimating film holding device with paralleling techniques. 3. Comparing of five intraoral radiographic techniques, it was appeared statistically significant reduction of the absorbed doses measured with rectangualr collimating film holding device compared to XCP film holding device (p0.05).

  4. Electron absorbed dose measurements in LINACs by thermoluminescent dosimeters

    International Nuclear Information System (INIS)

    In this work, electron absorbed doses measurements in radiation therapy (RT) were obtained. Radiation measurements were made using thermoluminescent dosimeters of calcium sulfate doped with dysprosium (CaSO4:Dy) and zirconium oxide (ZrO2). TL response calibration was obtained by irradiating TLDs and a Farmer cylindrical ionization chamber PTW 30013 at the same time. Each TL material showed a typical glow curve according to each material. Both calcium sulfate doped with dysprosium and zirconium oxide exhibited better light intensity to high energy electron beam compared with lithium fluoride. TL response as a function of absorbed dose was analyzed. TL response as a function of high energy electron beam was also studied. - Highlights: • Experimental results of ZrO2 irradiated by high energy electron beam. • Dosimetric characteristics of CaSO4:Dy were obtained under high energy electron effect. • Absorbed dose in electron beam was determined by TL phosphors. • Absorbed dose could be measured by TL phosphors and the results suggest that phosphors are good candidate for absorbed dose determining

  5. The BIPM graphite calorimeter standard for absorbed dose to water

    International Nuclear Information System (INIS)

    The BIPM has recently constructed a graphite calorimeter primary standard for absorbed dose to water in Co-60 and high-energy photon beams. This calorimeter is currently being used to carry out international comparisons of national primary standards for absorbed dose to water for radiotherapy applications. The calorimeter development progressed in two phases: firstly, a determination of the specific heat capacity of the graphite sample used in the calorimeter construction; secondly, the design and construction of the calorimeter itself. The determination of absorbed dose to water is made via three different measurements, using the calorimeter and a specially-designed transfer ionization chamber in graphite and in water, combined with corresponding Monte Carlo simulations. The calorimeter is now in regular use in the BIPM Co-60 beam to determine the long-term reproducibility of the absorbed-dose determination. In 2008, the Accelerator Dosimetry Working Group of the CCRI(I) recommended a comparison of the dosimetry of accelerator beams at the national laboratories using the BIPM calorimeter. The first comparison in this series took place at the NRC (Canada) in June 2009, and comparisons have been carried out at the PTB (Germany) and NIST (USA) during 2010. The paper gives a brief description of the method to determine the absorbed dose to water, concentrating on the novel conception of the calorimeter

  6. Absorbed Doses to Patients in Nuclear Medicine

    International Nuclear Information System (INIS)

    The Swedish radiation protection authority, (SSI), has supported work on estimates of radiation doses to patients from nuclear medicine examinations since more than 20 years. A number of projects have been reported. The results are put together and published under the name 'Doskatalogen' which contains data on doses to different organs and tissues from radiopharmaceuticals used for diagnostics and research. This new report contains data on: 11C-labelled substances (realistic maximum model), amino acids labelled with 11C, 18F or 75Se, 99mTc-apcitide, 123I-labelled fatty acids (123I- BMIPP and 123I-IPPA) and revised models for previously reported 15O-labelled water, 99mTc-tetrofosmin (rest as well as exercise) and 201Tl-ion Data for almost 200 substances and radionuclides are included in the 'Doskatalogen' today. Since the year 2001 the 'Doskatalogen' is available on the authority's home page (www.ssi.se)

  7. Patient absorbed radiation doses estimation related to irradiation anatomy

    International Nuclear Information System (INIS)

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

  8. Use of a new breast phantom for dosimetric determination of incident air kerma and mean glandular dose in digital mammography system

    International Nuclear Information System (INIS)

    Mammography aims to achieve a high image quality associated with a dose in the patient as low as feasible. Values of average glandular dose, DG, can be obtained by means of two dosimetric methods: one based on the measurement of incident air kerma, Ki, associated with tables of conversion factors that depend on the half value layer, the thickness and the glandular composition of the breast. And the one that makes the measure directly to thermoluminescent dosimeters, TLDs, placed in a new dosimetric phantom. Thus, this study aims to determine the incident air kerma (Ki) and average glandular dose (DG) applied on patients in a digital mammography system (DR) using the phantom dosimetric developed. Another objective is to compare the results with the values of DG determined from Ki and also with the values of Ki and DG indicated in the examination of each patient by the digital mammography unit. The result of the average values measured in 77 patients with compressed breast thickness within the range of 5.5 cm and 6.5 cm, shows that the Ki values ranged around 7.9% between the methods of action. The result of the values of DG ranged around 14.7% between the two methods of action. It is observed that the estimate of DG by the software is higher than the values measured with the dosimetric phantom. (author)

  9. Time improvement of photoelectric effect calculation for absorbed dose estimation

    International Nuclear Information System (INIS)

    Ionizing radiation therapy is a very useful tool in cancer treatment. It is very important to determine absorbed dose in human tissue to accomplish an effective treatment. A mathematical model based on affected areas is the most suitable tool to estimate the absorbed dose. Lately, Monte Carlo based techniques have become the most reliable, but they are time expensive. Absorbed dose calculating programs using different strategies have to choose between estimation quality and calculating time. This paper describes an optimized method for the photoelectron polar angle calculation in photoelectric effect, which is significant to estimate deposited energy in human tissue. In the case studies, time cost reduction nearly reached 86%, meaning that the time needed to do the calculation is approximately 1/7 th of the non optimized approach. This has been done keeping precision invariant

  10. Method for high absorbed dose measurement and standardization

    International Nuclear Information System (INIS)

    To establish the method for high absorbed dose measurements and standardization is important in the dose assurance of the product irradiation. The experiments using OAEP's cobalt-60 source including the homogeneity testing and the dose rate determination were employed by Fricke dosimeter. The cerium sulfate solutions were calibrated against the Fricke's dose rate, and the achieved G-value was within the possible range. The opti-chromic dosimeters were used as the cross-check of the locally calibrating system and the standard laboratories; the National Bureau of Standards (NBS), U.S.A. and the Boris Kidric Institute of Nuclear Science, Vinca, the results were within acceptable range

  11. Absorbed Doses to Patients in Nuclear Medicine; Doskatalogen foer nukleaermedicin

    Energy Technology Data Exchange (ETDEWEB)

    Leide-Svegborn, Sigrid; Mattsson, Soeren; Nosslin, Bertil [Universitetssjukhuset MAS, Malmoe (Sweden). Avd. foer radiofysik; Johansson, Lennart [Norrlands Universitetssjukhus, Umeaa (Sweden). Avd. foer radiofysik

    2004-09-01

    The work with a Swedish catalogue of radiation absorbed doses to patients undergoing nuclear medicine investigations has continued. After the previous report in 1999, biokinetic data and dose estimates (mean absorbed dose to various organs and tissues and effective dose) have been produced for a number of substances: {sup 11}C- acetate, {sup 11}C- methionine, {sup 18}F-DOPA, whole antibody labelled with either {sup 99m}Tc, {sup 111}In, {sup 123}I or {sup 131}I, fragment of antibody, F(ab'){sub 2} labelled with either {sup 99m}Tc, {sup 111}In, {sup 123}I or {sup 131}I and fragment of antibody, Fab' labelled with either {sup 99m}Tc, {sup 111}In, {sup 123}I or {sup 131}I. The absorbed dose estimates for these substances have been made from published biokinetic information. For other substances of interest, e.g. {sup 14}C-urea (children age 3-6 years), {sup 14}C-glycocholic acid, {sup 14}C-xylose and {sup 14}C-triolein, sufficient literature data have not been available. Therefore, a large number of measurements on patients and volunteers have been carried out, in order to determine the biokinetics and dosimetry for these substances. Samples of breast milk from 50 mothers, who had been subject to nuclear medicine investigations, have been collected at various times after administration of the radiopharmaceutical to the mother. The activity concentration in the breast milk samples has been measured. The absorbed dose to various organs and tissues and the effective dose to the child who ingests the milk have been determined for 17 different radiopharmaceuticals. Based on these results revised recommendations for interruption of breast-feeding after nuclear medicine investigations are suggested.

  12. Study of absorbed dose distribution to high energy electron beams

    International Nuclear Information System (INIS)

    The depth absorbed dose distribution by electron beams was studied. The influence of the beam energy, the energy spread, field size and design characteristics of the accelerator was relieved. Three accelerators with different scattering and collimation systems were studied leading todifferent depth dose distributions. A theoretical model was constructed in order to explain the increase in the depth dose in the build-up region with the increase of the energy. The model utilizes a three-dimensional formalism based on the Fermi-Eyges multiple scattering theory, with the introduction of modifications that takes into account the criation of secondary electrons. (Author)

  13. Calculation of absorbed dose distributions from dynamic wedges

    International Nuclear Information System (INIS)

    In radiotherapy with photon beams, the use of dynamic wedges, which are obtained by the movement of one of the jaws, offers an increasing flexibility relative to the traditional use of metal wedges. But it is a disadvantage for the measurement of absorbed dose distributions, because the absorbed dose at each measurement point can only be obtained after a complete movement of the jaw. Consequently, for radiotherapy planning, an algorithm should be available that does not require measurements for any specific dynamically wedged beam, but is based on only a modest number of measurements. In this paper, an algorithm for the calculation of the dose distribution from dynamic wedges is described. This algorithm uses the convolution of pencil beam kernels with a non-uniform field function. These pencil beam kernels are derived from empirical data resulting from measurements of the open beam only. (author)

  14. The absorbed dose to blood from blood-borne activity

    Science.gov (United States)

    Hänscheid, H.; Fernández, M.; Lassmann, M.

    2015-01-01

    The radiation absorbed dose to blood and organs from activity in the blood is relevant for nuclear medicine dosimetry and for research in biodosimetry. The present study provides coefficients for the average absorbed dose rates to the blood from blood-borne activity for radionuclides frequently used in targeted radiotherapy and in PET diagnostics. The results were deduced from published data for vessel radius-dependent dose rate coefficients and reasonable assumptions on the blood-volume distribution as a function of the vessel radius. Different parts of the circulatory system were analyzed separately. Vessel size information for heart chambers, aorta, vena cava, pulmonary artery, and capillaries was taken from published results of morphometric measurements. The remaining blood not contained in the mentioned vessels was assumed to reside in fractal-like vascular trees, the smallest branches of which are the arterioles or venules. The applied vessel size distribution is consistent with recommendations of the ICRP on the blood-volume distribution in the human. The resulting average absorbed dose rates to the blood per nuclear disintegration per milliliter (ml) of blood are (in 10?11?Gy·s?1·Bq?1·ml) Y-90: 5.58, I-131: 2.49, Lu-177: 1.72, Sm-153: 2.97, Tc-99m: 0.366, C-11: 4.56, F-18: 3.61, Ga-68: 5.94, I-124: 2.55. Photon radiation contributes 1.1–1.2·10?11?Gy·s?1·Bq?1·ml to the total dose rate for positron emitters but significantly less for the other nuclides. Blood self-absorption of the energy emitted by ß-particles in the whole blood ranges from 37% for Y-90 to 80% for Tc-99m. The correspondent values in vascular trees, which are important for the absorbed dose to organs, range from 30% for Y-90 to 82% for Tc-99m.

  15. Some comments on the concept of absorbed dose

    International Nuclear Information System (INIS)

    The main physical quantity for the evaluation of the induced effects by radiation ionizing is absorbed dose. ICRU report 51 defines this concept as quantity d? divided by dm, where d? is the mean energy imparted by radiation ionizing to matter of mass dm. However, nothing is said about the average operation concerning the stochastic energy imparted ?. Nevertheless, because considers the sum of all changes of rest mass of the involved nuclei and elementary particles in all interactions which occur within the mass (i.e. nuclear reactions and transformations of elementary particles), the average operation can not be done with an equilibrium statistical operator, rather, this has to be defined with a non-equilibrium statistical operator, therefore, absorbed dose is a function dependent on time. Furthermore, we present a discussion to clarify the equilibrium radiation and charged particle equilibrium within the context of thermodynamic equilibrium. (Author)

  16. Characteristics of the absorbed dose to water standard at ENEA

    Science.gov (United States)

    Guerra, A. S.; Laitano, R. F.; Pimpinella, M.

    1996-04-01

    The primary standard of absorbed dose to water established at ENEA for the Co-60 gamma-ray quality is based on a graphite calorimeter and an ionometric transfer system. This standard was recently improved after a more accurate assessment of some perturbation effects in the calorimeter and a modification of the water phantom shape and size. The conversion procedure requires two corresponding depths, one in graphite and one in water, where the radiation energy spectra must be the same. The energy spectra at the corresponding points were determined by a Monte Carlo simulation in water and graphite scaled phantoms. A thorough study of the calorimeter gap effect corrections was also made with regard to their dependence on depth and field size. A comparison between the ionization chamber calibration procedures based on the standards of absorbed dose to water and of air kerma was also made, confirming the consistency of the two methods.

  17. Electron absorbed dose measurements in LINACs by thermoluminescent dosimeters.

    Science.gov (United States)

    Cortés, J Rodríguez; Romero, R Alvarez; Nieto, J Azorín; Montalvo, T Rivera

    2014-01-01

    In this work, electron absorbed doses measurements in radiation therapy (RT) were obtained. Radiation measurements were made using thermoluminescent dosimeters of calcium sulfate doped with dysprosium (CaSO4:Dy) and zirconium oxide (ZrO2). TL response calibration was obtained by irradiating TLDs and a Farmer cylindrical ionization chamber PTW 30013 at the same time. Each TL material showed a typical glow curve according to each material. Both calcium sulfate doped with dysprosium and zirconium oxide exhibited better light intensity to high energy electron beam compared with lithium fluoride. TL response as a function of absorbed dose was analyzed. TL response as a function of high energy electron beam was also studied. PMID:24060149

  18. International comparison of calibration standards for exposure and absorbed dose

    International Nuclear Information System (INIS)

    A comparison was performed of the primary calibration standards for 60Co gamma radiation dose from Czechoslovakia (UDZ CSAV, Prague), Austria (OEFZS/BEV Seibersdorf) and Hungary (OMH Budapest) using ND 1005 (absolute measurement) and V-415 (by means of Nx) graphite ionization chambers. BEV achieved agreement better than 0.1%, OMH 0.35%. Good agreement was also achieved for the values of exposure obtained in absolute values and those obtained via Nx, this for the ND 1005/8105 chamber. The first ever international comparison involving Czechoslovakia was also performed of the unit of absorbed gamma radiation in a water and/or graphite phantom. The participants included Czechoslovakia (UDZ CSAV Prague), the USSR (VNIIFTRI Moscow) and Austria (OEFZS/BEV Seibersdorf). In all measurements, the agreement was better than 1%, which, in view of the differences in methodologies (VNIIFTRI, BEV: calorimetry, UDZ, UVVVR: ionometry) and the overall inaccuracies in determining the absorbed dose values, is a good result. (author)

  19. Analysis of absorbed dose to tooth enamel for ESR dosimetry

    International Nuclear Information System (INIS)

    Absorbed dose to tooth enamel was quantitatively correlated to organ doses by Monte Carlo calculations using the Electron Gamma Shower Code Version 4 for the Electron Spin Resonance (ESR) dosimetry using teeth. A region for teeth was newly added to a mathematical human model. Kerma coefficients for whole tooth and enamel part were prepared to estimate the dose to tooth enamel. Experiments were also carried out with a physical head phantom, which is made of tissue equivalent materials. Tooth samples and thermo-luminescence dosimeters (TLDs) of CaSO4 crystal were set at the teeth position in the head phantom. Addition Monte Carlo calculations were performed to verify the results of the experiments by using a Voxel-type phantom reconstructed from computed tomographic (CT) images of the physical phantom. The obtained data are to be useful for retrospective dose assessments in past radiation events by the ESR dosimetry with teeth. (author)

  20. The weighting of absorbed dose in environmental risk assessments

    International Nuclear Information System (INIS)

    Practical applications of using absorbed dose for radiation protection purposes forces consideration of the biological effectiveness of different types of radiation. For human radiation protection this is taken into account by applying dimensionless radiation weighting factors. Similarly, environmental dosimetry requires weighting factors, based on experimentally obtained RBE values, relevant for biota. The expected doses and dose rates in contaminated environments are low and the dose distribution is assumed to be highly heterogeneous. The identification of relevant RBE values for biota implies the recognition of critical end-points leading to reproductive disturbances. Concurrently, a mechanistic understanding of these end-points, whether they are of stochastic (single track) or deterministic origin, has to be elucidated. In a risk assessment framework it seems necessary to postulate the criteria for selecting appropriate RBE values, and to indicate a span for weighting factors applicable to different exposure situations and ecosystems. (author)

  1. Absorbed Dose Distribution in a Pulse Radiolysis Optical Cell

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1975-01-01

    When a liquid solution in an optical cell is irradiated by an intense pulsed electron beam, it may be important in the chemical analysis of the solution to know the distribution of energy deposited throughout the cell. For the present work, absorbed dose distributions were measured by thin radiochromic dye film dosimeters placed at various depths in a quartz glass pulse radiolysis cell. The cell was irradiated with 30 ns pulses from a field-emission electron accelerator having a broad spectrum with a maximum energy of ?MeV. The measured three-dimensional dose distributions showed sharp gradients in dose at the largest penetration depths in the cell and at the extreme lateral edges of the cell interior near the optical windows. This method of measurement was convenient because of the high spatial resolution capability of the detector and the linearity and absence of dose-rate dependence of its response.

  2. Sensors of absorbed dose of ionizing radiation based on mosfet

    Directory of Open Access Journals (Sweden)

    Perevertaylo V. L.

    2010-10-01

    Full Text Available The requirements to technology and design of p-channel and n-channel MOS transistors with a thick oxide layer designed for use in the capacity of integral dosimeters of absorbed dose of ionizing radiation are defined. The technology of radiation-sensitive MOS transistors with a thick oxide in the p-channel and n-channel version is created.

  3. Concept of radiation dose. Pt.1. Is the absorbed dose a well-defined quantity

    International Nuclear Information System (INIS)

    Radiation dosimetry is a common basis to all sciences treating with effects of ionizing radiation on matter. Radiation dose is introduced as the measure of causes of radiation effects. The absorbed dose being used as the most fundamental quantity in the current system of radiation dosimetry, it is worth while to check rigidity of its concept and adequacy of its definition from various points of view. In this presentation it is shown that the concept of the absorbed dose contains ambiguity related to its physical entities, and the definition given by ICRU contains deficiencies related to the emerging radiant energies, Rout, and to changes in the rest energies, ?Q. It is also pointed out that the dosimetric quantities, including the absorb dose, are generally not independent of time, and their values are not uniquely determined unless the elapsed time after irradiation is assigned

  4. Radon concentrations and absorbed dose measurements in a Pleistocenic cave

    International Nuclear Information System (INIS)

    Radon concentration measurements were carried out using solid-state nuclear track-etch detectors (SSNTDs) type CA 80-15 cellulose nitrate films, in a Pleistocenic cave at Petralona, in Halkidiki, Northern Greece, at 55 km from the city of Thessaloniki. Radon levels as high as 88 kBqxm-3 (2.38 nCi x l-1) have been recorded inside the cave equivalent to 11.90 WL in terms of occupational exposure to radon and its decay products. Absorbed dose rates were performed using TL dosimeters, type TLD-200 (CaF2-Dy) in a continuous monitoring program (integrated measurements). Dose rate levels as high as 110 nGy x h-1 were recorded inside the cave. In interpreting the high levels of radiation doses, radioactivity measurements regarding the naturally occurring 238U, 232Th and 40K radionuclides were carried out in various speleothems found at different sites in the cave. (author)

  5. Measurement of absorbed dose rate in 14 MW TRIGA reactor

    International Nuclear Information System (INIS)

    Almost all the energy absorbed in a material placed in the mixed radiation field of a reactor appears in the form of heat, since for the majority of materials the fraction of the energy that can result in light emission and chemical or structural change is very small. Therefore for determination of the absorbed dose essentially is the determination of the amount of heat which can be precisely determined with a calorimeter. For estimation of heat generated in different regions of the 14 MU TRIGA reactor and its experimental assemblies, two different calorimeters of heat flow calorimeter type were built. The first calorimeter is a rod type calorimeter where the heat generated in the sample is transmitted through a rod of aluminium towards cooling medium. The second calorimeter is a calorimeter with gas as heat transfer medium and uses thermal resistance of the gas and gas dumping. The sample of the both calorimeters is made of stainless steel. Outer diameter or the calorimeters is the same as the diameter of the fuel rod and their cooling is performed with water from the core. First, the calorimeters have been tested and reciprocal calibrated. Then they have been used for determination of absorbed dose rate in the core of the 14 MW TRIGA reactor. The principles of the both calorimeters were presented briefly and the results of the measurements in the reactor were discussed. (authors)

  6. The measurement of the indoor absorbed dose rate in air in Beijing

    International Nuclear Information System (INIS)

    This paper describes the indoor absorbed dose rate in air in Beijing. The average indoor absorbed dose rate in air is 8.29 ?rad/h. The ratio of indoor to outdoor absorbed dose rate for 849 buildings is 1.51

  7. Estimation of mean glandular dose for contrast enhanced digital mammography: factors for use with the UK, European and IAEA breast dosimetry protocols

    Science.gov (United States)

    Dance, D. R.; Young, K. C.

    2014-05-01

    The UK, European and IAEA protocols for breast dosimetry in mammography use tabulations of conversion factors, which relate measurements of incident air kerma to the mean glandular dose to the breast. To supplement the existing tabulations, a Monte Carlo computer program has been used to calculate conversion factors for the high-energy spectra used for contrast enhanced digital mammography. The calculations were made for the x-ray spectra from a tungsten target (tube voltage range 40-50 kV) filtered by 0.28, 0.30 and 0.32 mm of copper, and from molybdenum and rhodium targets (tube voltage range 40-49 kV), each filtered by 0.30 mm of copper. The g-factors for all of these spectra were plotted for each breast thickness as a function of half value layer (HVL) and were found to lie on smooth curves within 0.3%. These reflect the fact that the characteristic x-rays present in the spectra from molybdenum and rhodium are heavily filtered and all the spectra are essentially Bremsstrahlung. As a consequence, the s-factor previously used in the dosimetry protocols to adjust for different target/filter combinations can be taken as unity for all of the spectra considered. Tables of g-factors and c-factors are provided for breast thicknesses in the range 20-110 mm and HVLs in the range 2.4-3.6 mm of aluminium. The tables of c-factors are given for breast glandularities in the range 0.1%-100% and for typical glandularities for women in the age bands 40-49 and 50-64 attending the UK national breast screening programme.

  8. Reconciliation of Marinelli and MIRD radiation absorbed dose formulas

    International Nuclear Information System (INIS)

    For 25 years, the conventional method of radiation absorbed dose calculations for internal distributed radionuclides was based on formulas developed by Marinelli (Am. J. Roent. Radium Ther, 1942, v. 47, p. 210) et al, but was superseded by the MIRD schema (Loevinger, R.; Berman, M., MIRD Pamphlet 1, Rev., 1976, Soc. Nucl. Med.). It is shown that, although the formulas that are used in the two methods appear to be quite different, either formula can be factored into terms that, for simple cases, can be rearranged to yield the other. (U.K.)

  9. Calculation and measurements of absorbed dose in total body irradiation

    International Nuclear Information System (INIS)

    A method which is simple, reliable, and rapid to use in clinical routine for basic dose calculation in total body irradiation (TBI) has ben tested with 8 MV X-rays. The dosimetry follows, as far as possible, national and international recommendations for conventional radiotherapy. The dose rate at different locations and depths is calculated from the absorbed dose rate at dose maximum for a phantom size of 30x30x30 cm in the TBI field (dD/dtc), an inverse square law factor (SAD2/SPD2), the tissue-maximum ratio (TMR), an equivalent phantom and patient size correction factor (A), a factor for lack of back-scattering material (B), an off-axis output correction factor (O), and a factor that corrects for off-axis variations in effective photon beam energy and for oblique beam penetration of the patient (R). The collimator opening is constant for all patient sizes. It is shown that TMR, A, B and R can be measured in conventional geometry in ordinary phantoms but at an extended distance, while dD/dtc, O and SAD2/SPD2 must be measured in TBI geometry. Tests in Humanoid phantoms showed an agreement in measured and planned AP/2 doses of 2% or better. If the calculation method is used for lower photon energies or in other TBI geometires it may be necessary to correct for the elliptical shape of the patient and for back-scattered radiation from the walls or floor. (orig.)

  10. Nonisolated-sensor solid polystyrene absorbed dose measurements

    International Nuclear Information System (INIS)

    A nonisolated-sensor solid polystyrene calorimeter was constructed to test the role of thermal diffusion in limiting the length of irradiation time during which temperature measurements with nonisolated sensors could be made sufficiently free of drift for determining dose with radiation fields such as gamma rays, x rays, and high-energy electrons. From measured ratios of dose at 5.0 and 0.5 cm in polystyrene and comparisons to dose measurements with a polystyrene parallel-plate (pancake) ion chamber, it was shown that thermal diffusion is sufficiently small in polystyrene to permit accurate measurements for irradiation periods of less than 20 min. Comparison of the absorbed dose measurements and depth dose ratios with pancake ion chambers and calorimeter showed, that within the precision and accuracy of the two measuring systems, there is close agreement. The nonisolated-sensor solid polystyrene calorimeter has the interesting features of (i) simplicity of construction, (ii) simplicity of operation without vacuum or feedback for temperature control, (iii) capability of simultaneous measurements at several depths and off-axis positions, (iv) the very small thermal defect correction with polystyrene, and (v) operation with the calorimeter in any orientation

  11. ''Nonisolated-sensor'' solid polystyrene absorbed dose measurements

    International Nuclear Information System (INIS)

    A ''nonisolated-sensor'' solid polystyrene calorimeter was constructed to test the role of thermal diffusion in limiting the length of irradiation time during which temperature measurements with nonisolated sensors could be made sufficiently free of drift for determining dose with radiation fields such as gamma rays, x rays, and high-energy electrons. From measured ratios of dose at 5.0 and 0.5 cm in polystyrene and comparisons to dose measurements with a polystyrene parallel-plate (pancake) ion chamber, it was shown that thermal diffusion is sufficiently small in polystyrene to permit accurate measurements for irradiation periods of less than 20 min. Comparison of the absorbed dose measurements and depth dose ratios with pancake ion chambers and calorimeter showed, that within the precision and accuracy of the two measuring systems, there is close agreement. The nonisolated-sensor solid polystyrene calorimeter has the interesting features of (i) simplicity of construction, (ii) simplicity of operation without vacuum or feedback for temperature control, (iii) capability of simultaneous measurements at several depths and off-axis positions, (iv) the very small thermal defect correction with polystyrene, and (v) operation with the calorimeter in any orientation

  12. Absorbed dose determination in photon fields using the tandem method

    International Nuclear Information System (INIS)

    The purpose of this work is to develop an alternative method to determine the absorbed dose and effective energy of photons with unknown spectral distributions. It includes a 'tandem' system that consists of two thermoluminescent dosemeters with different energetic dependence. LiF: Mg, Ti, CaF2: Dy thermoluminescent dosemeters and a Harshaw 3500 reading system are employed. Dosemeters are characterized with 90Sr-90Y, calibrated with the energy of 60Co and irradiated with seven different qualities of x-ray beams, suggested by ANSI No. 13 and ISO 4037. The answers of each type of dosemeter are adjusted to a function that depends on the effective energy of photons. The adjustment is carried out by means of the Rosenbrock minimization algorithm. The mathematical model used for this function includes five parameters and has a gauss and a straight line. Results show that the analytical functions reproduce the experimental data of the answers, with a margin of error of less than 5%. The reason of the answers of the CaF2: Dy and LiF: Mg, Ti, according to the energy of the radiation, allows us to establish the effective energy of photons and the absorbed dose, with a margin of error of less than 10% and 20% respectively

  13. Dose absorbed in adults and children thyroid due to the I{sup 123} using the dosimetry MIRD and Marinelli; Dosis absorbida en tiroides de adultos y ninos debido al I{sup 123} utilizando las dosimetrias MIRD y Marinelli

    Energy Technology Data Exchange (ETDEWEB)

    Vasquez, M.; Castillo, C.; Cabrera, C.; Sarachaga, R.; Castaneda, J. [Universidad Nacional de Trujillo, Av. Juan Pablo II s/n, Ciudad Universitaria, Trujillo (Peru); Diaz, E., E-mail: marvva@hotmail.com [Universidade Federal do Rio Grande do Sul, Av. Paulo Gamma 110, Bairro Farropilhas, Porto Alegre, RS 90040-060 (Brazil)

    2014-08-15

    Using the dosimetry MIRD, and representation Cristy-Eckerman in the thyroid gland and organs of their bio-kinetics when I{sup 123} (Iodine) is used, the study demonstrates that the absorbed dose by the gland of an adult, children, and newly born, is their auto-dose, independent of the compartments number of their bio-kinetics. The dosimetric contributions of the organs of their bio-kinetics are insignificant. Their results are not significantly different to those obtained by the formalism MARINELLI (auto-dose) when it uses a sphere like glandular representation. In consequence, the kinetic model corresponding to the glandular representation decreases to a compartment, where the gland can also be represented like a sphere. (Author)

  14. Determination of the Absorbed Doses in Shanks of Interventional Radiologists

    International Nuclear Information System (INIS)

    Complicated procedures of interventional radiology require usually a much longer investigation time, comparing to the conventional radiography. Moreover, interventional radiology procedures require the presence of the medical staff next to the patient in order to perform the procedure. This results in higher risk for health professionals. Even though these persons reasonably keep away from the primary X ray beam, they are under the effects of scatter radiation due to the interaction of the primary beam with the patient. The protection aprons, thyroid protectors and shielding glasses are used in order to minimize the doses for the staff, but lower parts of legs remain usually unprotected and the absorbed doses in shanks are not recorded. The paper presents the measured values of the absorbed dose in lower extremities of medical staff, involved in the procedures of interventional radiology, completed with the measurements of air kerma under the patient table. Measurements were performed in one of big hospitals in Warsaw during all the procedures performed in six weeks. Majority of the procedures constituted angioplasty or angioplasty with vascular stenting, uterine fibroid embolization and cholangiography. In the angioplasty procedure, imaging techniques are used to guide a balloon-tipped catheter into an artery and advance it to where the vessel is narrow or blocked. The balloon is then inflated to open the vessel, deflated and removed. In vascular stenting, which is often performed with angioplasty, a small wire mesh tube (a stent) is permanently placed in the newly opened artery to help it remain open. In a uterine fibroid embolization procedure, the image guidance is used in order to place an embolic agent (synthetic material) inside one or more of the blood vessels that supply the fibroid tumors with blood. As a result, these vessels become occluded, or closed off, and the fibroid tissue shrinks. Percutaneous transhepatic cholangiography is a way of examining the bile duct system in the liver. During the exam, a thin needle is inserted through the skin (percutaneous) and through the liver (transhepatic) into a bile duct. Then dye is injected, and the bile duct system is outlined on x-rays. Our measurements consist of three parts: Measurements of kerma in air, under the patient table, in dependence on the dose rate and the distance from the X-ray tube, along the table; Measurements of kerma in air under the table during real interventions and comparison with the DAP values; measurements of the individual doses in shanks of medical personnel, using TLD dosemeters

  15. Development of dosimetric method for ?-ray absorbed dose by TLD

    International Nuclear Information System (INIS)

    The problem of ?-ray exposure tends to be lightly treated for the reason that ?-ray can be more easily shielded than ?-ray, but so far as the local exposure of skins concerns, the more prudent attitude is needed. In the operation handling radioactive materials, the ?-ray exposure of hands should not be neglected. The Power Reactor and Nuclear Fuel Development Corporation (PNC) incorporated ?-dosimeters in PNC type (multi-purpose) dosimeters because the radiation informations obtained from personal dosimeters are of significance in personal exposure control or radiation control. The paper is described on the structure of ?-ray dosimeters, the principle for measuring separately absorbed ?-ray dose in mixed ?- and ?-ray exposure, the calibration of the dosimeters, the results of measurement and the mixed exposure tests. The results were reported on the sensitivity to ?-ray and ?-ray, the variation in read-out values, the linearity of luminescence to exposure, and maximum ?-ray energy indicator. It became possible to isolate and measure ?-ray dose from mixed ?- and ?-ray exposure, and to evaluate the maximum energy of exposed ?-ray. The measuring precision obtained for ?-ray dose was about 48%, when the ?/? ratio was 1/1. Several issues or problems are pointed out at the end. (Wakatsuki, Y.)

  16. Absorbed Dose to Water Intercomparison Programme for Radiotherapy Centres

    International Nuclear Information System (INIS)

    The importance of intercomparison programme for radiation therapy dose delivery at radiotherapy centres (RC) has widely been reported. We at Nuclear Malaysia Agency (NM) intend to develop a national level intercomparison programme in terms of absorbed dose to water Dw. We started with one RC which has volunteered to participate in the programme in the dose delivery of 6 MV X-ray beam. Two types of comparison were made to get the accuracy. Type I is based on the measured value of the Dw at reference depth, Dw(zref)mea: RC results was compared with NM, in which NM results was taken as a standard. Type II is based on calculated value the Dw(zref), Dw(zref)cal : both NM and RC results were compared with Dw(zref)cal, in which Dw(zref)cal was taken as a standard. Two on-site measurements were made at this centre to check for results consistency and to get the average accuracy. Results obtained were consistent for the two measurements and the average values in the accuracy are within the acceptable accuracy limit of ±3 %, namely Type I: 1.10 ± 0.58 % for the RC, and Type II: 0.99 ± 0.60 % and - 0.11 ± 0.26 % respectively for the RC and NM. (author)

  17. Absorbed dose to water: Standards and traceability for radiation oncology

    International Nuclear Information System (INIS)

    Although the need for appropriate quantities and units for ionizing radiation has existed since shortly after discovery of X-rays, the quantities and units in general use today were not completely formalized until about 15 years ago. The development of appropriate national and international standards have also been ongoing. For many years the quantity, exposure, measured in units of roentgen was the national standard and they were also the quantity and units in which radiotherapy was described. With the introduction of megavoltage X-ray and electron-beam equipment and the adoption of the quantity open-quotes absorbed-doseclose quotes measured in units of rad (or gray) different approaches to calibrating these beams were needed. This was especially the case since the national standard in terms of exposure at a maximum photon energy for 60Co gamma rays was only available. Since the late 1960s various machine calibration protocols have been published. These protocols have to accommodate changes in modality, energy, quantities and units between the national standard and the user. Because of this, a new definition of traceability is proposed to accommodate the present system. By recording all intercomparisons and parameters used, an auditable calibration chain can be maintained. Even with the introduction of calibration protocols based upon national absorbed dose standards, the proposed traceability definition will still be needed be needed

  18. Impact of energy spread of electron beam on absorbed dose distribution

    International Nuclear Information System (INIS)

    The results of numerical research on dependence of absorbed dose on energy spread of electron beam with two sided irradiation are presented in this paper. The dependence of change in value of absorbed dose in the critical point on spectrum width of electron beam is shown. The dependence of dose uptake ratio on energy spread of electron beam is found.

  19. Absorbed-dose calibrations in high energy photon beams at the National Physical Laboratory: conversion procedure

    International Nuclear Information System (INIS)

    The absorbed-dose calibration service from NPL is based on a primary-standard calorimeter that measures absorbed dose to graphite. Secondary-standard dosemeters are calibrated in absorbed dose to water in a 60Co gamma-ray beam and in x-ray beams over a range of generating potentials from 4 MV to 19 MV. Two methods were used to convert the calibrations of working-standard ionization chambers from absorbed dose to graphite into absorbed dose to water. One method involved the use of published interaction data for photons and secondary electrons, and required a knowledge of the chamber construction. The second method involved the calculation of the ratio of absorbed dose in graphite and water phantoms irradiated consecutively in the same photon beam using the photon-fluence scaling theorem. The two methods were in agreement to 0.1%. (author)

  20. Measurement of absorbed dose received by people subjected to chest X-rays

    International Nuclear Information System (INIS)

    A first set of measurements of the absorbed dose received by people subjected to chest X-rays was undertaken with a view to comparing the values obtained by radiophotographic and standard methods respectively. Since the radiophotographic absorbed dose values appeared too high the different working parameters were reviewed; the new measurements have shown a gain of a factor 10 on the absorbed dose received by a 'standard' 70-kg man, the quality of image remaining acceptable

  1. Comparison of calculated absorbed dose to water calibration and direct absorbed dose to water calibration coefficients of farmer type ionization chambers

    International Nuclear Information System (INIS)

    Results of the calculated absorbed dose to water calibration coefficients using air kerma calibrations and direct absorbed dose to water calibration coefficients ND,W for eight Farmer Type ionization chambers were compared using Co-60 radiation quality and following the dosimetry Codes of Practice (TRS-277, TRS-381 and the new International Code of Practice, TRS-398. The percentage deviation in the results of calculated and direct absorbed dose to water calibration coefficients for NE-2571 type chambers ranged from -0.33 to -0.65. No significant difference was found in the results of calculated and direct absorbed dose to water calibration coefficients for these chambers following the new International Code of Practice. (author)

  2. Dose conversion for the BIPM graphite calorimeter standard for absorbed dose to water

    International Nuclear Information System (INIS)

    The existing standard for absorbed dose to water in 60Co gamma radiation at the BIPM is a parallel-plate cavity ionization chamber. The present paper describes a new standard for use in 60Co and in accelerator photon beams based on a graphite calorimeter. The realization of the standard can be divided into three major stages: a measurement of the specific heat capacity of the graphite used for the calorimeter construction; the design and construction of the graphite calorimeter itself; the conversion from the mean graphite absorbed dose to the calorimeter core, Dc, to the absorbed dose to water at the reference point in a water phantom, Dw. The dose conversion makes use of the Monte Carlo code PENELOPE and experimental measurements using a transfer ionization chamber tailored to the specific needs of the dose conversion. Results and uncertainties. Results for Cw,c will be presented for the reference 60Co beam at the BIPM. In the context of a programme of key comparisons of Dw standards for high-energy photon beams, the new standard was transported to the accelerators of the NRC in June 2009 and the PTB in March 2010, and is scheduled to be used at the NIST in September 2010. Results will be presented for these beams, evaluated using phase-space information supplied by each laboratory. A detailed analysis has addressed uncertainties associated with simulated geometries, radiation transport meculated geometries, radiation transport mechanics, interaction coefficients and phase-space spectra. The results suggest a standard uncertainty for Cw,c below 0.25 %. Additionally, in connection with the comparison at the NRC, calculations of Cw,c for the BIPM standard were made by the NRC using the EGSnrc code. Agreement between the BIPM and NRC calculations at the 0.2 % level strongly supports the uncertainty analysis and the view that the symmetry of the method results in a low sensitivity to the details of the Monte Carlo calculations

  3. Blood compounds irradiation process: assessment of absorbed dose using Fricke and Thermoluminescent dosimetric systems

    International Nuclear Information System (INIS)

    The assessment of gamma absorbed doses in irradiation facilities allows the quality assurance and control of the irradiation process. The liability of dose measurements is assign to the metrological procedures adopted including the uncertainty evaluation. Fricke and TLD 800 dosimetric systems were used to measure absorbed dose in the blood compounds using the methodology presented in this paper. The measured absorbed doses were used for evaluating the effectiveness of the irradiation procedure and the gamma dose absorption inside the irradiation room of a gamma irradiation facility. The radiation eliminates the functional and proliferative capacities of donor T-lymphocytes, preventing Transfusion associated graft-versus-host disease (TA-GVHD), a possible complication of blood transfusions. The results show the applicability of such dosimetric systems in quality assurance programs, assessment of absorbed doses in blood compounds and dose uniformity assign to the blood compounds irradiation process by dose measurements in a range between 25 Gy and 100 Gy. (author)

  4. Blood compounds irradiation process: assessment of absorbed dose using Fricke and Thermoluminescent dosimetric systems

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Gabriela de Amorim; Squair, Peterson Lima; Pinto, Fausto Carvalho; Belo, Luiz Claudio Meira; Grossi, Pablo Andrade [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN-CNEN/MG), Belo Horizonte, MG (Brazil)], e-mail: gas@cdtn.br, e-mail: pls@cdtn.br, e-mail: fcp@cdtn.br, e-mail: lcmb@cdtn.br, e-mail: pabloag@cdtn.br

    2009-07-01

    The assessment of gamma absorbed doses in irradiation facilities allows the quality assurance and control of the irradiation process. The liability of dose measurements is assign to the metrological procedures adopted including the uncertainty evaluation. Fricke and TLD 800 dosimetric systems were used to measure absorbed dose in the blood compounds using the methodology presented in this paper. The measured absorbed doses were used for evaluating the effectiveness of the irradiation procedure and the gamma dose absorption inside the irradiation room of a gamma irradiation facility. The radiation eliminates the functional and proliferative capacities of donor T-lymphocytes, preventing Transfusion associated graft-versus-host disease (TA-GVHD), a possible complication of blood transfusions. The results show the applicability of such dosimetric systems in quality assurance programs, assessment of absorbed doses in blood compounds and dose uniformity assign to the blood compounds irradiation process by dose measurements in a range between 25 Gy and 100 Gy. (author)

  5. Estimation of mean-glandular dose from monitoring breast entrance skin air kerma using a high sensitivity metal oxide semiconductor field effect transistor (MOSFET) dosimeter system in mammography

    International Nuclear Information System (INIS)

    Estimation of mean-glandular dose (MGD) has been investigated in recent years due to the potential risks of radiation-induced carcinogenesis associated with the mammographic examination for diagnostic radiology. In this study, a new technique for immediate readout of breast entrance skin air kerma (BESAK) using high sensitivity MOSFET dosimeter after mammographic projection was introduced and a formula for the prediction of tube output with exposure records was developed. A series of appropriate conversion factors was applied to the MGD determination from the BESAK. The study results showed that signal response of the high sensitivity MOSFET exhibited excellent linearity within mammographic dose ranges, and that the energy dependence was less than 3% for each anode/filter combination at the tube potentials 25-30 kV. Good agreement was observed between the BESAK and the tube exposure output measurement for breasts thicker than 30 mm. In addition, the air kerma estimated from our prediction formula provided sufficient accuracy for thinner breasts. The average MGD from 120 Asian females was 1.5 mGy, comparable to other studies. Our results suggest that the high sensitivity MOSFET dosimeter system is a good candidate for immediately readout of BESAK after mammographic procedures

  6. A comparison of mean glandular dose diagnostic reference levels within the all-digital Irish National Breast Screening Programme and the Irish Symptomatic Breast Services.

    Science.gov (United States)

    O'Leary, Desiree; Rainford, Louise

    2013-03-01

    Data on image quality, compression and radiation dose were collected from symptomatic breast units within the Republic of Ireland. Quantitative and qualitative data were analysed using SPSS. Recommendations of mean glandular dose (MGD) diagnostic reference levels were made at various levels for film-screen and full field digital mammography units to match levels published worldwide. MGDs received by symptomatic breast patients within Ireland are higher than those received in the all-digital Irish Breast Screening service; 55-65 mm breast: 1.75 mGy (screening) vs. 2.4 mGy (symptomatic) at the 95th percentile; various reasons are proposed for the differences. MGDs achieved in the screening service may be lower because of the exacting requirements for radiographer training, characteristics of the patients and equipment quality assurance levels. More precise imaging guidelines, standards and training of symptomatic radiographers performing mammography are suggested to remediate MGDs delivered to the breasts of Irish women attending the symptomatic breast services. PMID:22740646

  7. Advances in absorbed dose measurement standards at the australian radiation laboratory

    International Nuclear Information System (INIS)

    The applications of ionising radiation in the medical and industrial fields require both an accurate knowledge of the amount of ionising radiation absorbed by the medium in question and the capability of relating this to National and International standards. The most useful measure of the amount of radiation is the absorbed dose which is defined as the energy absorbed per unit mass. For radiotherapy, the reference medium is water, even though the measurement of the absorbed dose to water is not straightforward. Two methods are commonly used to provide calibrations in absorbed dose to water. The first is the calibration of the chamber in terms of exposure in a Cobalt-60 beam, followed by the conversion by a protocol into dose to water in this and higher energy beams. The other route is via the use of a graphite calorimeter as a primary standard device, where the conversion from absorbed dose to graphite to absorbed dose in water is performed either by theoretical means making use of cavity ionisation theory, or by experiment where the graphite calorimeter and secondary standard ionisation chamber are placed at scaled distances from the source of the radiation beam (known as the Dose-Ratio method). Extensive measurements have been made at Cobalt-60 at ARL using both the exposure and absorbed dose to graphite routes. Agreement between the ARL measurements and those based on standards maintained by ANSTO and NPL is within ± 0.3%. Absorbed dose measurements have also been performed at ARL with photon beams of nominal energy 16 and 19 MeV obtained from the ARL linac. The validity of the protocols at high photon energies, the validity of the methods used to convert from absorbed dose in graphite to absorbed dose in water and the validity of the indices used to specify the beams are discussed. Brief mention will also be made of the establishment of a calibration facility for neutron monitors at ARL and of progress in the development of ERP dosimetry

  8. Advances in absorbed dose measurement standards at the australian radiation laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Boas, J.F.; Hargrave, N.J.; Huntley, R.B.; Kotler, L.H.; Webb, D.V.; Wise, K.N. [Australian Radiation Laboratory, Yallambie, VIC (Australia)

    1996-12-31

    The applications of ionising radiation in the medical and industrial fields require both an accurate knowledge of the amount of ionising radiation absorbed by the medium in question and the capability of relating this to National and International standards. The most useful measure of the amount of radiation is the absorbed dose which is defined as the energy absorbed per unit mass. For radiotherapy, the reference medium is water, even though the measurement of the absorbed dose to water is not straightforward. Two methods are commonly used to provide calibrations in absorbed dose to water. The first is the calibration of the chamber in terms of exposure in a Cobalt-60 beam, followed by the conversion by a protocol into dose to water in this and higher energy beams. The other route is via the use of a graphite calorimeter as a primary standard device, where the conversion from absorbed dose to graphite to absorbed dose in water is performed either by theoretical means making use of cavity ionisation theory, or by experiment where the graphite calorimeter and secondary standard ionisation chamber are placed at scaled distances from the source of the radiation beam (known as the Dose-Ratio method). Extensive measurements have been made at Cobalt-60 at ARL using both the exposure and absorbed dose to graphite routes. Agreement between the ARL measurements and those based on standards maintained by ANSTO and NPL is within {+-} 0.3%. Absorbed dose measurements have also been performed at ARL with photon beams of nominal energy 16 and 19 MeV obtained from the ARL linac. The validity of the protocols at high photon energies, the validity of the methods used to convert from absorbed dose in graphite to absorbed dose in water and the validity of the indices used to specify the beams are discussed. Brief mention will also be made of the establishment of a calibration facility for neutron monitors at ARL and of progress in the development of ERP dosimetry.

  9. Absorbed dose determination in photon fields using the tandem method

    CERN Document Server

    Marques-Pachas, J F

    1999-01-01

    The purpose of this work is to develop an alternative method to determine the absorbed dose and effective energy of photons with unknown spectral distributions. It includes a 'tandem' system that consists of two thermoluminescent dosemeters with different energetic dependence. LiF: Mg, Ti, CaF sub 2 : Dy thermoluminescent dosemeters and a Harshaw 3500 reading system are employed. Dosemeters are characterized with sup 9 sup 0 Sr- sup 9 sup 0 Y, calibrated with the energy of sup 6 sup 0 Co and irradiated with seven different qualities of x-ray beams, suggested by ANSI No. 13 and ISO 4037. The answers of each type of dosemeter are adjusted to a function that depends on the effective energy of photons. The adjustment is carried out by means of the Rosenbrock minimization algorithm. The mathematical model used for this function includes five parameters and has a gauss and a straight line. Results show that the analytical functions reproduce the experimental data of the answers, with a margin of error of less than ...

  10. Uncertainty analysis for absorbed dose from a brain receptor imaging agent

    Energy Technology Data Exchange (ETDEWEB)

    Aydogan, B.; Miller, L.F. [Univ. of Tennessee, Knoxville, TN (United States). Nuclear Engineering Dept.; Sparks, R.B. [Oak Ridge Inst. for Science and Education, TN (United States); Stubbs, J.B. [Radiation Dosimetry Systems of Oak Ridge, Inc., Knoxville, TN (United States)

    1999-01-01

    Absorbed dose estimates are known to contain uncertainties. A recent literature search indicates that prior to this study no rigorous investigation of uncertainty associated with absorbed dose has been undertaken. A method of uncertainty analysis for absorbed dose calculations has been developed and implemented for the brain receptor imaging agent {sup 123}I-IPT. The two major sources of uncertainty considered were the uncertainty associated with the determination of residence time and that associated with the determination of the S values. There are many sources of uncertainty in the determination of the S values, but only the inter-patient organ mass variation was considered in this work. The absorbed dose uncertainties were determined for lung, liver, heart and brain. Ninety-five percent confidence intervals of the organ absorbed dose distributions for each patient and for a seven-patient population group were determined by the ``Latin Hypercube Sampling`` method. For an individual patient, the upper bound of the 95% confidence interval of the absorbed dose was found to be about 2.5 times larger than the estimated mean absorbed dose. For the seven-patient population the upper bound of the 95% confidence interval of the absorbed dose distribution was around 45% more than the estimated population mean. For example, the 95% confidence interval of the population liver dose distribution was found to be between 1.49E+0.7 Gy/MBq and 4.65E+07 Gy/MBq with a mean of 2.52E+07 Gy/MBq. This study concluded that patients in a population receiving {sup 123}I-IPT could receive absorbed doses as much as twice as large as the standard estimated absorbed dose due to these uncertainties.

  11. Determination of absorbed dose to the lens of eye from external sources

    International Nuclear Information System (INIS)

    The methods of determining absorbed dose distributions in human eyeball by means of the experiments and available theories have been reported. A water phantom was built up. The distributions of beta dose were measured by an extrapolation ionization chamber at some depths corresponding to components of human eyeball such as cornea, sclera, anterior chamber and the lens of eye. The ratios among superficial absorbed dose (at 0.07 mm) and average absorbed doses at the depths 1,2,3 mm are obtained. They can be used for confining the deterministic effects of superficial tissues and organs such as the lens of eye for weakly penetrating radiations

  12. A Survey On Mean Glandular Dose From Full-Field Digital Mammography Systems, Operate Using Mo/ Mo And W/Rh Target/ Filter Combinations

    International Nuclear Information System (INIS)

    We had conducted a survey on Mean Glandular Dose (MGD) from Full-Field Digital Mammography systems (FFDM) operate using Molybdenum/ Molybdenum (Mo/ Mo) and Tungsten/ Rhodium (W/ Rh) target/ filter combinations. A survey was carried out at two randomly selected mammography centres in Malaysia, namely National Cancer Society and International Islamic University of Malaysia. The first centre operates using a W/ Rh, while the second centre operates using an Mo/ Mo target/ filter combinations. On the basis of recorded information, data on mammographic views, MGD, age and Compressed Breast Thickness (CBT) were recorded for 100 patients, for each mammographic centre respectively. The MGD data were analyzed for variation with age group, with 5 years increment. The MGD data were also analyzed for variation with CBT, with 5 mm increment. We found that for both CC and MLO views, FFDM systems operated using Mo/ Mo and W/ Rh target/ filter combinations present the same trend on MGD. The average MGD decreases as age increases. While average MGD increases with the increasing of CBT. However, FFDM system operates using Mo/ Mo gives higher MGD as compared with FFDM system operates using W/ Rh. (author)

  13. Evaluation of scatter-to-primary ratio, grid performance and normalized average glandular dose in mammography by Monte Carlo simulation including interference and energy broadening effects

    Science.gov (United States)

    Cunha, D. M.; Tomal, A.; Poletti, M. E.

    2010-08-01

    In this work, a computational code for the study of imaging systems and dosimetry in conventional and digital mammography through Monte Carlo simulations is described. The developed code includes interference and Doppler energy broadening for simulation of elastic and inelastic photon scattering, respectively. The code estimates the contribution of scattered radiation to image quality through the spatial distribution of the scatter-to-primary ratio (S/P). It allows the inclusion of different designs of anti-scatter grids (linear or cellular), for evaluation of contrast improvement factor (CIF), Bucky factor (BF) and signal difference-to-noise ratio improvement factor (SIF). It also allows the computation of the normalized average glandular dose, \\bar{D}_{g,N} . These quantities were studied for different breast thicknesses and compositions, anode/filter combinations and tube potentials. Results showed that the S/P increases linearly with breast thickness, varying slightly with breast composition or the spectrum used. Evaluation of grid performance showed that the cellular grid provides the highest CIF with smaller BF. The SIF was also greater for the cellular grid, although both grids showed SIF HVL) of the spectrum, decreases considerably with breast thickness and has a small dependence on the anode/filter combination. Inclusion of interference effects of breast tissues affected the values of S/P obtained with the grid up to 25%, while the energy broadening effect produced smaller variations on the evaluated quantities.

  14. Application of European protocol in the evaluation of contrast-to-noise ratio and mean glandular dose for two digital mammography systems

    International Nuclear Information System (INIS)

    The performance of two digital mammography systems, Agfa CR75 and CRMM3 computed radiography (CR) and IMS Giotto MD direct digital radiography (DR), was assessed by applying a method recommended in the European protocol for quality control in mammography screening. The contrast-to-noise ratio (CNR) and mean glandular dose (MGD) values were measured and contrast detail (CD) analysis was performed. The CNRs for system CR were 21.9, 12.9, 9.5, 8.8, 7.4, 5.5 and 4.4 for 2, 3, 4, 4.5, 5, 6 and 7-cm polymethylmethacrylate (PMMA) thickness, respectively. The respective CNRs for system DR were 10.4, 8.8, 6.3, 7.3, 7.2, 6.4 and 6.54. For the same phantom thickness sequence, the MGDs were 0.7, 1.1, 1.3, 1.6, 1.9, 2.5 and 3.4 mGy for system CR, whereas they were 0.7, 1.2, 1.1, 1.3, 1.8, 3.5 and 3.9 mGy for system DR. The CNR and MGD results satisfactorily correlate with CD analysis results. The MGD values compare well with the values recommended in the European protocol. Despite being simple, CNR and MGD can provide an effective system for performance assessment and constancy checks for related optimisations. (authors)

  15. Monte Carlo simulation of absorbed dose in quartz from beta rays

    International Nuclear Information System (INIS)

    The absorbed dose in quartz samples irradiated by ? rays in TL or OSL dating protocol was simulated using the EGSnrc /DOSRZnrc code. Effects of thickness and grain size of the quartz samples on the absorbed dose were evaluated with the samples of ?0.97 cm x (10-500) ?m, in grain size of 60-300 ?m. The results show that the absorbed dose in quartz is relative to the sample thickness, and the maximum difference of the relative dose can be up to 10%. The absorbed dose is relative to the grain size, too. The relative dose increases with decreasing grain size, and the maximum difference can be up to 19%. These factors should be considered in the dating. (authors)

  16. Isoeffective dose: a concept for biological weighting of absorbed dose in proton and heavier-ion therapies

    CERN Document Server

    Wambersie, A; Menzel, H G; Gahbauer, R; DeLuca, P M; Hendry, J H; Jones, D T L

    2011-01-01

    When reporting radiation therapy procedures, International Commission on Radiation Units and Measurements (ICRU) recommends specifying absorbed dose at/in all clinically relevant points and/or volumes. In addition, treatment conditions should be reported as completely as possible in order to allow full understanding and interpretation of the treatment prescription. However, the clinical outcome does not only depend on absorbed dose but also on a number of other factors such as dose per fraction, overall treatment time and radiation quality radiation biology effectiveness (RBE). Therefore, weighting factors have to be applied when different types of treatments are to be compared or to be combined. This had led to the concept of `isoeffective absorbed dose', introduced by ICRU and International Atomic Energy Agency (IAEA). The isoeffective dose D(IsoE) is the dose of a treatment carried out under reference conditions producing the same clinical effects on the target volume as those of the actual treatment. It i...

  17. Estimates of absorbed dose in different organs in children treated with radium for skin hemangiomas

    Energy Technology Data Exchange (ETDEWEB)

    Lundell, M. [Karolinska Hospital, Stockholm (Sweden)

    1994-12-01

    Between 1930 and 1959, more than 10,000 infants were treated at Radiumhemmet, Stockholm, with radium ({sup 226}Ra) needles and/or tubes for hemangioma of the skin. Absorbed dose to the brain, eye lenses, parotid glands, thyroid gland, breast enlarge, lungs, stomach, intestine, ovaries, testicles and bone marrow were calculated for each individual. The mean absorbed dose to the different organs ranged from 0.06 to 0.48 Gy. The highest absorbed dose was given to the breast (maximum 47.7 Gy). There was a wide dose range for each organ which was due mainly to differences in the distance between the applicator and the organ. The absorbed dose to all organs decreased on average by 32% during the study period. This was due to a 25% decrease in the treatment time and a change in the distribution of the treatment sites. 17 refs., 4 figs., 4 tabs.

  18. Primary standard of absorbed dose to water in high-energy photon beam irradiation

    International Nuclear Information System (INIS)

    In radiotherapy, accurate dose evaluation must be made. One of the most important things in dose evaluation is the measurement of absorbed dose to water. National Institute of Advanced Industrial Science and Technology developed the primary standard of absorbed dose to water in high-energy photon beam irradiation, and enabled the calibration of ionization chamber dosimeters, using the photon beam with nearly the same beam quality as high-energy photon beam used in the medical front. Firstly, this paper explains the principle of the measurement of absorbed dose to water using an ionization chamber dosimeter, as well as the purpose and significance of the calibration of ionization chamber dosimeters based on the standard for the 60Co-? beam measurement of absorbed dose to water. Secondly, it introduces graphite calorimeter as the primary standard of absorbed dose to water in high-energy photon beam irradiation, which was newly developed for enabling the calibration of ionization chamber dosimeters using high-energy photon beam, while omitting the necessity of correction with the beam quality transformation coefficient. The greater part of graphite calorimeter is an acrylic phantom, and three graphite elements as calorie absorption body are installed in its central part. Finally, it describes the future prospects for the standard for absorbed dose to water. (A.O.)

  19. Determination of Absorbed Dose in Large 60-Co Fields Radiotherapy

    International Nuclear Information System (INIS)

    Radiation in radiotherapy has selective impact on ill and healthy tissue. During the therapy the healthy tissue receives certain amount of dose. Therefore dose calculations in outer radiotherapy must be accurate because too high doses produce damage in healthy tissue and too low doses cannot ensure efficient treatment of cancer cells. A requirement on accuracy in the dose calculations has lead to improvement of detectors, and development of absolute and relative dosimetry. Determination of the dose distribution with use of computer is based on data provided by the relative dosimetry. This paper compares the percentage depth doses in cubic water phantoms of various dimensions with percentage depth doses calculated with use of Mayneord factor from the experimental depth doses measured in water phantom of large dimension. Depth doses in water phantoms were calculated by the model of empirical dosimetrical functions. The calculations were based on the assumption that large 60Co photon field exceeds the phantom's limits. The experimental basis for dose calculations by the model of empirical dosimetrical functions were exposure doses measured in air and dose reduction factors because of finite phantom dimensions. Calculations were performed by fortran 90 software. It was found that the deviation of dosimetric model was small in comparison to the experimental data. (author)

  20. Absorbed dose homogenizing devices for the 7 MeV NILPRP Linac

    International Nuclear Information System (INIS)

    The 7 MeV Linac of the National Institute for Lasers Plasma and Radiation Physics is used for research works and materials irradiations for industry. In order to extend the application domain, two devices were designed and constructed for homogenizing the absorbed dose: one for 7 MeV electrons for absorbed dose and the other for 7 MeV photons. In this paper the device parameters and the transverse absorbed dose distributions are presented. They were measured by means of an ionization chamber (Klinisches Dosimeter 27012-70107). (authors)

  1. Evaluation of scatter-to-primary ratio, grid performance and normalized average glandular dose in mammography by Monte Carlo simulation including interference and energy broadening effects

    Energy Technology Data Exchange (ETDEWEB)

    Cunha, D M; Tomal, A; Poletti, M E, E-mail: poletti@ffclrp.usp.b [Departamento de Fisica e Matematica, FFCLRP, Universidade de Sao Paulo, 14040-901, Ribeirao Preto, Sao Paulo (Brazil)

    2010-08-07

    In this work, a computational code for the study of imaging systems and dosimetry in conventional and digital mammography through Monte Carlo simulations is described. The developed code includes interference and Doppler energy broadening for simulation of elastic and inelastic photon scattering, respectively. The code estimates the contribution of scattered radiation to image quality through the spatial distribution of the scatter-to-primary ratio (S/P). It allows the inclusion of different designs of anti-scatter grids (linear or cellular), for evaluation of contrast improvement factor (CIF), Bucky factor (BF) and signal difference-to-noise ratio improvement factor (SIF). It also allows the computation of the normalized average glandular dose, D-bar {sub g,N}. These quantities were studied for different breast thicknesses and compositions, anode/filter combinations and tube potentials. Results showed that the S/P increases linearly with breast thickness, varying slightly with breast composition or the spectrum used. Evaluation of grid performance showed that the cellular grid provides the highest CIF with smaller BF. The SIF was also greater for the cellular grid, although both grids showed SIF < 1 for thin breasts. Results for D-bar {sub g,N} showed that it increases with the half-value layer (HVL) of the spectrum, decreases considerably with breast thickness and has a small dependence on the anode/filter combination. Inclusion of interference effects of breast tissues affected the values of S/P obtained with the grid up to 25%, while the energy broadening effect produced smaller variations on the evaluated quantities.

  2. Evaluation of scatter-to-primary ratio, grid performance and normalized average glandular dose in mammography by Monte Carlo simulation including interference and energy broadening effects

    International Nuclear Information System (INIS)

    In this work, a computational code for the study of imaging systems and dosimetry in conventional and digital mammography through Monte Carlo simulations is described. The developed code includes interference and Doppler energy broadening for simulation of elastic and inelastic photon scattering, respectively. The code estimates the contribution of scattered radiation to image quality through the spatial distribution of the scatter-to-primary ratio (S/P). It allows the inclusion of different designs of anti-scatter grids (linear or cellular), for evaluation of contrast improvement factor (CIF), Bucky factor (BF) and signal difference-to-noise ratio improvement factor (SIF). It also allows the computation of the normalized average glandular dose, D-bar g,N. These quantities were studied for different breast thicknesses and compositions, anode/filter combinations and tube potentials. Results showed that the S/P increases linearly with breast thickness, varying slightly with breast composition or the spectrum used. Evaluation of grid performance showed that the cellular grid provides the highest CIF with smaller BF. The SIF was also greater for the cellular grid, although both grids showed SIF g,N showed that it increases with the half-value layer (HVL) of the spectrum, decreases considerably with breast thickness and has a small dependence on the anode/filter combination. Inclusion of interference effects of ion. Inclusion of interference effects of breast tissues affected the values of S/P obtained with the grid up to 25%, while the energy broadening effect produced smaller variations on the evaluated quantities.

  3. Some remarks on the calibration of clinical dose meters in terms of absorbed dose in water

    International Nuclear Information System (INIS)

    Six ionization chambers have been tested at the Hungarian National Office of Measures (OMH) in air and in a water phantom in order to check their suitability for the determination of absorbed dose in water. All ionization chambers were calibrated in air under identical conditions, using the same secondary standard to avoid any differences in the calibration procedure. Subsequently the chambers were calibrated against the same secondary standard in a water phantom. The calibration factors obtained in water were compared with the product of the air calibration factors and the rad/R conversion factors published in ICRU Report 23. The deviations were within +-3% for five radiation qualities between 100 kV X-rays and 60Co gamma rays. (author)

  4. Absorbed dose simulations in near-surface regions using high dose rate Iridium-192 sources applied for brachytherapy

    International Nuclear Information System (INIS)

    Brachytherapy treatment with Iridium-192 high dose rate (HDR) sources is widely used for various tumours and it could be developed in many anatomic regions. Iridium-192 sources are inserted inside or close to the region that will be treated. Usually, the treatment is performed in prostate, gynaecological, lung, breast and oral cavity regions for a better clinical dose coverage compared with other techniques, such as, high energy photons and Cobalt-60 machines. This work will evaluate absorbed dose distributions in near-surface regions around Ir-192 HDR sources. Near-surface dose measurements are a complex task, due to the contribution of beta particles in the near-surface regions. These dose distributions should be useful for non-tumour treatments, such as keloids, and other non-intracavitary technique. For the absorbed dose distribution simulations the Monte Carlo code PENELOPE with the general code penEasy was used. Ir-192 source geometry and a Polymethylmethacrylate (PMMA) tube, for beta particles shield were modelled to yield the percentage depth dose (PDD) on a cubic water phantom. Absorbed dose simulations were realized at the central axis to yield the Ir-192 dose fall-off along central axis. The results showed that more than 99.2% of the absorbed doses (relative to the surface) are deposited in 5 cm depth but with slower rate at higher distances. Near-surface treatments with Ir-192 HDR sources yields achievable measurements and with proper clinical technique and accessories should apply as an alternative for treatment of lesions where only beta sources were used. - Highlights: ? A PMMA (polymethylmethacrylate) tube was used to surround the HDR Ir-192 to shield the beta particles. ? 99.2% of the absorbed doses (relative to the surface) are deposited in 5 cm depth. ? Near-surface treatments with Ir-192 HDR sources yields achievable measurements

  5. Estimation of terrestrial air-absorbed dose rate from the data of regional geochemistry database

    International Nuclear Information System (INIS)

    This paper presents an estimation of air-absorbed dose rate from the data of K2O, U and Th content from Chinese regional geochemical database. A total of 421 group original data of combined samples in Zhongshan City (ZSC), Guangdong Province and south China were extracted from the national geochemical database. Estimated average value of air-absorbed dose rate is 139.4 nGy h-1 in the granite area and 73.7 nGy h-1 in the sedimentary area. The level of air-absorbed dose rate is closely related with the surface lithology. Estimated mean air-absorbed dose rate approximates to the measured average value by a portable plastic scintillator dosemeter in Zhuhai City were bordered with ZSC. The results show that the pre-evaluation of ionizing radiation level using regional geochemical data is feasible. (author)

  6. 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

  7. Development of methodology for assessment of absorbed dose and stopping power for low energy conversion electrons

    International Nuclear Information System (INIS)

    The evaluation of absorbed dose in the case of external and internal contamination due to radionuclides is sometimes hard, because of the difficulties in the assessment of the absorbed dose caused by electrons with energy less than 100 KeV in mucous membrane. In this work, a methodology for assessment of absorbed dose and stopping power in VYNS (co-polymer of polivinyl chloride - acetate) absorbers, for the 62.5 KeV and 84-88 KeV energy 109 Cd conversion electrons, working with a 4 ? proportional pressurized detector, is presented. In order to assure the reproducibility of measurement conditions, one of the detector halves has been used to obtain a spectrum of a thin 109 Cd source, without absorber. The other half of the detector was used in concomitance to obtain spectra with different thicknesses if absorber. The absorbed energy was obtained subtracting each spectrum with absorber from the spectrum without absorber, which were stored in a microcomputer connected to signal processing systems by ACE type interface. The VYNS weight and thickness were evaluated using common radionuclide metrology procedures. As VYNS has characteristics similar to a tissue equivalent material, the results obtained are consistent with dosimetric concepts and have a good agreement with those of the literature. (author)

  8. Absorbed dose determination for interstitial 125I boost therapy

    International Nuclear Information System (INIS)

    Iodine-125 implants are being used to boost external beam treatments of unresectable pancreas and lung tumors. Calculations of the 125I activity required to achieve a specific average peripheral dose are presented as a function of the average tumor dimension for spherical, ellipsoidal, and cylindrical implants. Both uniform and random seed spacings are investigated. The results indicate that the average peripheral dose is relatively insensitive to the seed distribution as well as to the seed activity. The average tumor dose is typically 20% greater than the average peripheral dose

  9. Absorbed dose evaluations in retrospective dosimetry: Methodological developments using quartz

    DEFF Research Database (Denmark)

    Bailiff, I.K.; BØtter-Jensen, L.

    2000-01-01

    Dose evaluation procedures based on luminescence techniques were applied to 50 quartz samples extracted from bricks that had been obtained from populated or partly populated settlements in Russia and Ukraine downwind of the Chernobyl NPP. Determinations of accrued dose in the range similar to 30-300 mGy were obtained using TL (210 degreesC TL and pre-dose) and OSL (single and multiple aliquot) procedures. Overall, good inter-laboratory concordance of dose evaluations was achieved, with a variance (1 sigma) of similar to+/-10 mGy for the samples examined. (C) 2000 Elsevier Science Ltd. All rights reserved.

  10. The technique of measuring of relativistic proton absorbed dose in thin biological samples

    International Nuclear Information System (INIS)

    The technique of blood samples irradiation by the 1 GeV protons is described. This experiment was carried out to study chromosomic aberrations induced in human lymphocytes by the low absorbed doses. The problems of measurement and calculation of the absorbed dose of protons in thin samples with necessary precision are discussed. The method of forming the uniform spatial distribution of the proton flux that crossed the samples and the technique of the beam monitoring are presented

  11. Absorbed neutron dose measurement on nuclear moisture density gauge operators using thermoluminescence dosimeters (TLD)

    International Nuclear Information System (INIS)

    Moisture density gauges (MDG) are widely used in monitoring soil and pavement properties but emit gamma and neutron radiation that could pose a health hazard. Neutron dose absorbed received by the personnel from using an MDG was determined using neutron thermoluminescence dosimeter (TLD). Result shows neutron dose levels received were comparable with gamma dose that could exceed the safe dose limits for radiation workers. It was also shown that radiation backscattering differs with dry and moist media. (author)

  12. Absorbed Dose Distributions in Irradiated Plastic Tubing and Wire Insulation

    DEFF Research Database (Denmark)

    Miller, Arne; McLaughlin, W. L.

    1979-01-01

    Plastic tubing and wire insulation were simulated by radiochromic dye dosimeter films having electron absorbing properties similar to the materials of interest (polyethylene and PVC). A 400-keV electron accelerator was used to irradiate from 1, 2, 3 and 4 sides simulating possible industrial irradiation situations. The results indicate that in most cases it is necessary but also sufficient to irradiate from two opposite sides.

  13. Biological indicators for radiation absorbed dose: a review

    International Nuclear Information System (INIS)

    Biological dosimetry has an important role to play in assessing the cumulative radiation exposure of persons working with radiation and also in estimating the true dose received during accidents involving external and internal exposure. Various biodosimetric methods have been tried to estimate radiation dose for the above purposes. Biodosimetric methods include cytogenetic, immunological and mutational assays. Each technique has certain advantages and disadvantages. We present here a review of each technique, the actual method used for detection of dose, the sensitivity of detection and its use in long term studies. (author)

  14. Plastic film materials for dosimetry of very large absorbed doses

    OpenAIRE

    McLaughlin, W.L.; Miller, Arne; Abdel-Rahim, F.; Preisinger, T.

    2011-01-01

    Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-01

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

  16. measurement of absorbed dose in mix-dp phantom irradiated by x and gamma rays

    International Nuclear Information System (INIS)

    It has been done of x-rays dan gamma rays absorbed dose measurement of mix-dp phantom of 70 kVp.90kvp and 110 kvp x rays kxo-12 medical exposure and cobalt-60 gamma (50 ci) by UD-170A BeO-TLD. Ionization chamber 12 cc NIRS-R2 as reference dosemeter, which was calibrated on primer dosemeter. In X-rays energy used, it was done of absorbed dose measurement on Mix-Dp phantom surface and depth (d= 10cm) beam field area 10 x 10 cm, focus distance (FSD), s=80 cm dose measurement of 90 kvp X-rays on Mix-Dp phantom surface, depth and scattering (d=15 cm) beam field area 12 x 12 cm, focus distance (FSD),s=79 cm and measurement of absorbed dose Co-60 gamma: 5 R, 10R, 20 R, 30R, 40R and 50R by dose rate 0.434 R/min. It was shown that in clinical, effective energy range of X-rays relative lower than dose range Co-60 gamma. BeO-TLD characteristic on energy dependence is low based on TI sensitivity ± 1.3 for energy below 100 keV. Relation between absorbed dose and TL response to 90 kVp X-rays shown that rperm=0.990, r ber=0.995 and r sact=0.962. In measurement of Co-60 gamma absorbed dose by BeO-TLD shown TI sensitivity decrease ± 0.900. The result still needed corrections to achieve optimum measurement of absorbed dose X-rays and gamma by UD-170A BeO-TLD, which were performed optimum fading time and anealling temperature

  17. Plastic film materials for dosimetry of very large absorbed doses

    DEFF Research Database (Denmark)

    McLaughlin, W.L.; Miller, Arne

    1985-01-01

    Most plastic films have limited response ranges for dosimetry because of radiation-induced brittleness, degradation, or saturation of the signal used for analysis (e.g. spectrophotometry) at high doses. There are, however, a few types of thin plastic films showing linearity of response even up to doses as high as 2 × 106 Gy (200 Mrad) without severe loss of mechanical properties. Among many candidate film types tested, those showing such resistance to radiation damage and continued response at such high doses are polyethylene terephthalate, high-density polyethylene, dyed polyvinylchloride, polystyrene, dyed and undyed polyhalostyrenes, dyed aromatic polyamides, and polyvinylidene fluoride. Although most of these systems have fairly stable absorption spectra after irradiation, tests of dependence on dose rate and on temperature during irradiation show that only polystyrene and some of the polyhalostyrenes have essentially rate-independent and moderately temperature-dependent responses to such large doses of ionizing radiation. While radiation-induced optical absorption in the ultraviolet for polystyrene is unstable following irradiation, thus leading to an intrinsic low-intensity rate dependence, the dyed polychlorostyrenes show essentially the same response to radiation-processing gamma-ray fields and to very high-intensity electron beams, and a relatively stable absorption spectrum at wavelengths for dosimetry analysis in the visible spectral region of ?430 nm.

  18. Assessment of the absorbed radiation dose by gas chromatography of radiolytic products in food

    International Nuclear Information System (INIS)

    Various methods of gas chromatography provide highly accurate and reliable results in the detection of radiolytic products in food. It appears wise for any laboratory of chemical analysis to continuously adjust and redefine the relevant standard rules. The yield of radiochemical product measured for the food under examination permits an accurate assessment of the absorbed dose only in cases, where the conditions of irradiation and the food constituents are known. In the low dose ranges and the absence of data on irradiation and storage conditions, any estimations of the absorbed dose on the basis of the yield measured for one single chemical product must be approached with great caution. (orig.)

  19. Distributions of absorbed dose from ?--meson beams calculated from a new Monte Carlo program

    International Nuclear Information System (INIS)

    We describe the structure and the physical input data of a new Monte Carlo program for calculations of the absorbed dose which is transferred by negatively charged pions to tissue equivalent phantoms. The program is based mainly on experimentally determined input data. Contributions to absorbed dose from nuclear reactions of pions in flight and from nuclear fragmentation following the absorption of stopped pions were studied in detail. The resulting dose distributions are presented for cases of narrow as well as extended parallel beams of ?--mesons with an initial average momentum of 170 MeV/c. (orig.)

  20. Norwegian system for implementing the IAEA code of practice based on absorbed dose to water

    International Nuclear Information System (INIS)

    In 2001 the Nordic secondary standards dosimetry laboratories (SSDLs) recommended the use of absorbed dose to water as the quantity for the calibration standard and code of practice in radiotherapy.The code of practice adopted was IAEA Technical Reports Series No. 398. The Norwegian system for implementation includes the 60Co calibration of SSDL and hospital dosimeters in terms of absorbed dose to water at the Norwegian SSDL and on-site visits to every clinic teaching the new code and performing dose measurements. Comparisons of the Norwegian Radiation Protection Authority 60Co absorbed dose to water calibration at the Finnish SSDL with the French primary standards dosimetry laboratory showed agreement within 0.4%.The on-site visit measuring system compared with the Finnish on-site equipment agreed within 0.6%.The on-site visits were welcomed, and demonstrated the need for external dosimetry audits to improve the local implementation of the code of practice. (author)

  1. Absorbed doses in tissue-equivalent spheres above radioactive sources in soil.

    Science.gov (United States)

    Ulanovsky, Alexander

    2014-11-01

    Doses due to external exposure of terrestrial biota are assessed using differential air kerma from radioactive sources in soil and energy-dependent 'absorbed dose-per-air kerma' conversion factors computed for spherical tissue-equivalent bodies. The presented approach allows computing average whole body absorbed dose for terrestrial organisms with body masses from 1 mg to 1,000 kg located at heights from 10 cm to 500 m above ground. Radioactive sources in soil emitting photons with energies from 10 keV to 10 MeV have been considered. Interpolation of the computed quantities over source energy, body mass, and height above ground results in plausible estimates of whole body average absorbed doses for non-human terrestrial biota from gamma-radiation emitted by any radionuclides in contaminated terrain. PMID:25129621

  2. Determination of the absorbed dose and dose-distribution in water for low- and medium-energetic photons

    International Nuclear Information System (INIS)

    The methods to determine the absorbed dose to water for low and medium energy photons were studied. Large differences between the results of these methods exists. So, a research proposition has been made to explain these differences. The goal of this research will be the development of a method to determine the absorbed dose below approximately 400 keV with an ionization chamber calibrated at 60Co gamma radiation. To explain the differences between the set of methods, some causes were proposed, like the influence of the ionisation chamber on the measurement in water. Also, some methods to determine the factors are proposed. (author). 29 refs

  3. New absorbed dose measurement with cylindrical water phantoms for multidetector CT

    Science.gov (United States)

    Ohno, Takeshi; Araki, Fujio; Onizuka, Ryota; Hioki, Kazunari; Tomiyama, Yuuki; Yamashita, Yusuke

    2015-06-01

    The aim of this study was to develop new dosimetry with cylindrical water phantoms for multidetector computed tomography (MDCT). The ionization measurement was performed with a Farmer ionization chamber at the center and four peripheral points in the body-type and head-type cylindrical water phantoms. The ionization was converted to the absorbed dose using a 60Co absorbed-dose-to-water calibration factor and Monte Carlo (MC) -calculated correction factors. The correction factors were calculated from MDCT (Brilliance iCT, 64-slice, Philips Electronics) modeled with GMctdospp (IMPS, Germany) software based on the EGSnrc MC code. The spectrum of incident x-ray beams and the configuration of a bowtie filter for MDCT were determined so that calculated photon intensity attenuation curves for aluminum (Al) and calculated off-center ratio (OCR) profiles in air coincided with those measured. The MC-calculated doses were calibrated by the absorbed dose measured at the center in both cylindrical water phantoms. Calculated doses were compared with measured doses at four peripheral points and the center in the phantom for various beam pitches and beam collimations. The calibration factors and the uncertainty of the absorbed dose determined using this method were also compared with those obtained by CTDIair (CT dose index in air). Calculated Al half-value layers and OCRs in air were within 0.3% and 3% agreement with the measured values, respectively. Calculated doses at four peripheral points and the centers for various beam pitches and beam collimations were within 5% and 2% agreement with measured values, respectively. The MC-calibration factors by our method were 44–50% lower than values by CTDIair due to the overbeaming effect. However, the calibration factors for CTDIair agreed within 5% with those of our method after correction for the overbeaming effect. Our method makes it possible to directly measure the absorbed dose for MDCT and is more robust and accurate than the CTDIair measurement.

  4. Three dimensional measurements of absorbed dose in BNCT by Fricke-gel imaging

    International Nuclear Information System (INIS)

    A method has been studied for absorbed dose imaging and profiling in a phantom exposed to thermal or epithermal neutron fields, also discriminating between various contributions to the absorbed dose. The proposed technique is based on optical imaging of FriXy-gel phantoms, which are proper tissue-equivalent phantoms acting as continuous dosimeters. Convenient modifications in phantom composition allow, from differential measurements, the discrimination of various contributions to the absorbed dose. The dosimetry technique is based on a chemical dosimeter incorporated in a tissue-equivalent gel (Agarose). The chemical dosimeter is a ferrous sulphate solution (which is the main component of the standard Fricke dosimeter) added with a metal ion indicator (Xylenol Orange). The absorbed dose is measured by analysing the variation of gel optical absorption in the visible spectrum, imaged by means of a CCD camera provided with a suitable filter. The technique validity has been tested by irradiating and analysing phantoms in the thermal facility of the fast research reactor TAPIRO (ENEA, Casaccia, Italy). In a cylindrical phantom simulating a head, we have imaged the therapy dose from thermal neutron reactions with 10B and the dose in healthy tissue not containing boron. In tissue without boron, we have discriminated between the two main contributions to the absorbed dose, which comes from the 1H(n,?)2H and 14N(n,p)14C reactions. The comparison with the results of other experimental techniques and of simulations reveals that the technique is very promising. A method for the discrimination of fast neutron contribution to the absorbed dose, still in an experimental stage, is proposed too. (author)

  5. Evaluation of the distribution of absorbed dose in child phantoms exposed to diagnostic medical x rays

    International Nuclear Information System (INIS)

    The purpose of this study was to determine, by theoretical calculation and experimental measurement, the absorbed dose distributions in two heterogeneous phantoms representing one-year- and five-year-old children from typical radiographic examinations for those ages. Theoretical work included the modification of an existing internal dose code which uses Monte Carlo methods to determine doses within the Snyder-Fisher mathematical phantom. A Ge(Li) detector and a pinhole collimator were used to measure x-ray spectra which served as input to the modified Monte Carlo codes which were used to calculate organ doses in children. The calculated and measured tissue-air values were compared for a number of organs. For most organs, the results of the calculated absorbed doses agreed with the measured absorbed doses within twice the coefficient of variation of the calculated value. The absorbed dose to specific organs for several selected radiological examinations are given for one-year-old, five-year-old, and adult phantoms

  6. Evaluation of the distribution of absorbed dose in child phantoms exposed to diagnostic medical x rays

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W. L.; Poston, J. W.; Warner, G. G.

    1978-04-01

    The purpose of this study was to determine, by theoretical calculation and experimental measurement, the absorbed dose distributions in two heterogeneous phantoms representing one-year- and five-year-old children from typical radiographic examinations for those ages. Theoretical work included the modification of an existing internal dose code which uses Monte Carlo methods to determine doses within the Snyder-Fisher mathematical phantom. A Ge(Li) detector and a pinhole collimator were used to measure x-ray spectra which served as input to the modified Monte Carlo codes which were used to calculate organ doses in children. The calculated and measured tissue-air values were compared for a number of organs. For most organs, the results of the calculated absorbed doses agreed with the measured absorbed doses within twice the coefficient of variation of the calculated value. The absorbed dose to specific organs for several selected radiological examinations are given for one-year-old, five-year-old, and adult phantoms.

  7. Absorbed and effective dose from periapical radiography by portable intraoral x-ray machine

    International Nuclear Information System (INIS)

    The purpose of this study was to measure the absorbed dose and to calculate the effective dose for periapical radiography done by portable intraoral x-ray machines. 14 full mouth, upper posterior and lower posterior periapical radiographs were taken by wall-type 1 and portable type 3 intraoral x-ray machines. Thermoluminescent dosemeters were placed at 23 sites at the layers of the tissue-equivalent ART woman phantom for dosimetry. Average tissue absorbed dose and radiation weighted dose were calculated for each major anatomical site. Effective dose was calculated using 2005 ICRP tissue weighted factors. On 14 full mouth periapical radiographs, the effective dose for wall-type x-ray machine was 30 Sv; for portable x-ray machines were 30 Sv, 22 Sv, 36 Sv. On upper posterior radiograph, the effective dose for wall-type x-ray machine was 4 Sv; for portable x-ray machines doses were 4 Sv, 3 Sv, 5 Sv. On lower posterior radiograph, the effective dose for wall type x-ray machine was 5 Sv; for portable x-ray machines doses were 4 Sv, 4 Sv, 5 Sv. Effective doses for periapical radiographs performed by portable intraoral x-ray machines were similar to doses for periapical radiographs taken by wall type intraoral x-ray machines

  8. Absorbed Doses to Embryo from Intravenous Urography at Selected Radiological Departments in Slovakia

    International Nuclear Information System (INIS)

    Actual legislation used in radiological protection requires quality assurance program for decreasing radiation load of patients from radiological examinations. The information about irradiation of pregnant women is very important, because the embryo is more radiosensitive as adult organism. On the basis of absence of unified calculations or measurements of absorbed doses to embryo from various radiological examinations in Slovakia we present in this study the values of absorbed doses to embryo from intravenous urography at selected radiological departments in Slovakia. Absorbed doses to embryo were obtained by measurement and calculation using the simulation of irradiation of pregnant woman by intravenous urography. The results of our study indicate, that absorbed doses to embryo were at various radiological departments considerably different, depending on type of X-ray machine and different settings of technical parameters of X-ray machine. In accordance with worldwide trend it is necessary to decrease radiation load of patients as low as possible level. Differences in radiation load between radiological departments indicate, that it is necessary to continue in solving of this problem and perform measurements and calculations of absorbed doses to embryo at different types of X-ray machines and at different examinations, where the embryo is in direct beam of X-ray. (author)

  9. Measurement of absorbed dose to water for low and medium energy X rays

    International Nuclear Information System (INIS)

    For low energy and medium energy X rays, that is for tube voltages of up to 100 kV or starting at 100 kV, the dosimetric quantity of interest in the paper is the absorbed dose to water at the surface of a water phantom or at a depth of 2 cm, sometimes 5 cm, in a water phantom, respectively. In the first part of the paper the principal methods by which these quantities can be determined with the aid of calibrated ionization chambers are described.The second part is devoted to an absolute measurement of the absorbed dose to water for medium energy X rays.The method is based on the use of an extrapolation chamber inside a graphite phantom. The steps for converting the electrical charge collected in the measuring volume to the absorbed dose to graphite are outlined, together with the steps leading from absorbed dose to graphite to absorbed dose to water in a water phantom. The method presented is used for determining what is known in X ray dosimetry as the ionization chamber replacement effect. (author)

  10. National absorbed dose to water references for radiotherapy medium energy X-rays by water calorimetry

    International Nuclear Information System (INIS)

    LNE-LNHB current references for medium energy X-rays are established in terms of air kerma. Absorbed dose to water, which is the quantity of interest for radiotherapy, is obtained by transfer dosimetric techniques following a methodology described in international protocols. The aim of the thesis is to establish standards in terms of absorbed dose to water in the reference protocol conditions by water calorimetry. The basic principle of water calorimetry is to measure the absorbed dose from the rise in temperature of water under irradiation. A calorimeter was developed to perform measurements at a 2 cm depth in water according to IAEA TRS-398 protocol for medium energy x-rays. Absorbed dose rates to water measured by calorimetry were compared to the values established using protocols based on references in terms of air kerma. A difference lower than 2.1% was reported. Standard uncertainty of water calorimetry being 0.8%, the one associated to the values from protocols being around 3.0%, results are consistent considering the uncertainties. Thanks to these new standards, it will be possible to use IAEA TRS-398 protocol to determine absorbed dose to water: a significant reduction of uncertainties is obtained (divided by 3 by comparison with the application of the IAEA TRS-277 protocol). Currently, none of the counterparts' laboratories own such an instrument allowing direct determination of standards in the reference conditions recommended by the international radiotherapy protocols. (author)

  11. Distribution of Absorbed Doses to the Important Organs of Head and Neck Region in Panoramic Radiography

    International Nuclear Information System (INIS)

    The purpose of this study was to estimate the distribution of absorbed doses of each important organs of head and neck region in panoramic radiography. Radiation dosimetry at internal anatomic sites and skin surfaces of phantom (RT-210 Humanoid Head and Neck Section R) was performed with lithium fluoride (TLD-100R) thermoluminescent dosimeters according to change of kilovoltage (65 kVp, 75 kVp and 85 kVp) with 4 miliamperage and 20 second exposure time. The results obtained were as follows; Radiation absorbed doses of internal anatomic sites were presented the highest does of 1.04 mGy, 1.065 mGy and 2.09 mGy in nasopharynx, relatively high doses of 0.525 mGy, 0.59 mGy and 1.108 mGy in deep lobe of parotid gland, 0.481 mGy, 0.68 mGy and 1.191 mGy in submandibular gland. But there were comparatively low doses of 0.172 mGy and 0.128 mGy in eyes and thyroid gland that absorbed dose was estimated at 85kVp. Radiation absorbed doses of skin surfaces were presented the highest doses of 1.263 mGy, 1.538 mGy and 2.952 mGy in back side of first cervical vertebra and relatively high doses of 0.267 mGy, 0.401 mGy and 0.481 mGy in parotid gland. But there were comparatively low doses of 0.057 mGy, 0.068 mGy and 0.081 mGy in philtrum and 0.059 mGy in middle portion of chin that absorbed dose was estimated at 85 kVp. According to increase of kilovoltage, the radiation absorbed doses were increased 1.1 times when kilovoltage changes from 65 kVp to 75 kVp and 1.9 times when kilovoltagep to 75 kVp and 1.9 times when kilovoltage changes from 75 kVp to 85 kVp at internal anatomic sites. According to increase of kilovoltage, the radiation absorbed doses were increased 1.3 times when kilovoltage changes from 65 kVp to 75 kVp and 1.6 times when kilovoltage changes from 75 kVp to 85 kVp at skin surfaces.

  12. Theoretical study of the influence of a heterogeneous activity distribution on intratumoral absorbed dose distribution

    International Nuclear Information System (INIS)

    Radioimmunotherapy of hematopoeitic cancers and micrometastases has been shown to have significant therapeutic benefit. The treatment of solid tumors with radionuclide therapy has been less successful. Previous investigations of intratumoral activity distribution and studies on intratumoral drug delivery suggest that a probable reason for the disappointing results in solid tumor treatment is nonuniform intratumoral distribution coupled with restricted intratumoral drug penetrance, thus inhibiting antineoplastic agents from reaching the tumor's center. This paper describes a nonuniform intratumoral activity distribution identified by limited radiolabeled tracer diffusion from tumor surface to tumor center. This activity was simulated using techniques that allowed the absorbed dose distributions to be estimated using different intratumoral diffusion capabilities and calculated for tumors of varying diameters. The influences of these absorbed dose distributions on solid tumor radionuclide therapy are also discussed. The absorbed dose distribution was calculated using the dose point kernel method that provided for the application of a three-dimensional (3D) convolution between a dose rate kernel function and an activity distribution function. These functions were incorporated into 3D matrices with voxels measuring 0.10x0.10x0.10 mm3. At this point fast Fourier transform (FFT) and multiplication in frequency domain followed by inverse FFT (iFFT) were used to effwed by inverse FFT (iFFT) were used to effect this phase of the dose calculation process. The absorbed dose distribution for tumors of 1, 3, 5, 10, and 15 mm in diameter were studied. Using the therapeutic radionuclides of 131I, 186Re, 188Re, and 90Y, the total average dose, center dose, and surface dose for each of the different tumor diameters were reported. The absorbed dose in the nearby normal tissue was also evaluated. When the tumor diameters exceed 15 mm, a much lower tumor center dose is delivered compared with tumors between 3 and 5 mm in diameter. Based on these findings, the use of higher ?-energy radionuclides, such as 188Re and 90Y is more effective in delivering a higher absorbed dose to the tumor center at tumor diameters around 10 mm

  13. Absorbed dose in the full-mouth periapical radiography, panoramic radiography, and zonography

    International Nuclear Information System (INIS)

    The objective of this study was to evaluate the possibility of substitution of the zonography for the full-mouth periapical radiography in aspect of radiation protection. Rando phantom and LiF TLD chips were used for dosimetry. The absorbed doses at brain, skin above the TMJ, parotid gland, bone marrow in the mandibular body, and thyroid gland during the full-mouth periapical radiography, panoramic radiography, and zonography were measured. From the zonography, the absorbed doses to the brain, the skin over the TMJ, and the parotid gland were relatively high, but the absorbed doses to the bone marrow in the mandibular body and, especially, the thyroid gland were very low. The zonography can be an alternative to the full-mouth periapical radiography in aspect of radiation protection.

  14. Contribution to the determination of a standard of absorbed dose in water for cobalt 60 photons

    International Nuclear Information System (INIS)

    A new standard, expressed in terms of absorbed dose at a depth of 5g/cm2 in a water phantom irradiated by cobalt 60 gamma photons, is determined. The procedure developed is based on a transfer method using two dosimetric techniques: Fricke dosimetry and ionometry (0.6 cm3 NE 2571 radiotherapy ionization chamber). Their calibration is performed with the primary calibration standard of absorbed dose: the graphite calorimeter. The relative discrepancy between the values of absorbed dose in water determined by the chemical dosimeter and the ionization chamber is equal to 1%. The ionization chamber has been also calibrated near the Cobalt 60 reference beam characterized in terms of air kerma

  15. The effect of latex maturity on the absorbed dose for preparing RVNRL of optimum tensile strength

    International Nuclear Information System (INIS)

    This paper present the results of the studies on the effects of using latex of different maturity periods, between 0 to 15 weeks on gamma irradiation dose require to prepare RVNRL of optimum tensile strength. Absorbed dose to prepare RVNRL of optimum tensile strength, molecular weight between cross-links and cross-link density were found to be influenced by the maturity of the latex used in the studies. With respect to optimum tensile strength and absorbed dose, latex of about six weeks maturity was found most suitable and economical for radiation vulcanization process. Using latex either with or without added secondary preservative the optimum tensile strength was determined at an absorbed of 8 kGy. However, the optimum tensile strength of RVNRL prepared from latex contained added secondary preservative was found to be higher than the optimum tensile strength of RVNRL prepared from latex without secondary preservative

  16. On the Influence of Patient Posture on Organ and Tissue Absorbed Doses Caused by Radiodiagnostic Examinations

    International Nuclear Information System (INIS)

    Virtual human phantoms, frequently used for organ and tissue absorbed dose assessment in radiology, normally represent the human body either in standing or in supine posture. This raises the question as to whether it matters dosimetrically if the postures of the patient and of the phantom do not match. This study uses the recently developed FASH2sta (Female Adult meSH) and FASH2sup phantoms which represent female adult persons in standing and supine posture. The effect of the posture on organ and tissue absorbed doses will be studied using the EGSnrc Monte Carlo code for simulating abdominal radiographs and special attention will be directed to the influence of body mass on the results. For the exposure conditions considered here, posture-dependent absorbed dose differences by up to a factor of two were found. (author)

  17. Absorbed Doses to Patients in Nuclear Medicine; Doskatalogen foer nukleaermedicin

    Energy Technology Data Exchange (ETDEWEB)

    Leide-Svegborn, Sigrid; Mattsson, Soeren; Johansson, Lennart; Fernlund, Per; Nosslin, Bertil

    2007-04-15

    The Swedish radiation protection authority, (SSI), has supported work on estimates of radiation doses to patients from nuclear medicine examinations since more than 20 years. A number of projects have been reported. The results are put together and published under the name 'Doskatalogen' which contains data on doses to different organs and tissues from radiopharmaceuticals used for diagnostics and research. This new report contains data on: {sup 11}C-labelled substances (realistic maximum model), amino acids labelled with {sup 11}C, {sup 18}F or {sup 75}Se, {sup 99m}Tc-apcitide, {sup 123}I-labelled fatty acids ({sup 123}I- BMIPP and {sup 123}I-IPPA) and revised models for previously reported {sup 15}O-labelled water, {sup 99m}Tc-tetrofosmin (rest as well as exercise) and {sup 201}Tl-ion Data for almost 200 substances and radionuclides are included in the 'Doskatalogen' today. Since the year 2001 the 'Doskatalogen' is available on the authority's home page (www.ssi.se)

  18. Specification of absorbed dose to water using model-based dose calculation algorithms for treatment planning in brachytherapy

    Science.gov (United States)

    Carlsson Tedgren, Åsa; Alm Carlsson, Gudrun

    2013-04-01

    Model-based dose calculation algorithms (MBDCAs), recently introduced in treatment planning systems (TPS) for brachytherapy, calculate tissue absorbed doses. In the TPS framework, doses have hereto been reported as dose to water and water may still be preferred as a dose specification medium. Dose to tissue medium Dmed then needs to be converted into dose to water in tissue Dw,med. Methods to calculate absorbed dose to differently sized water compartments/cavities inside tissue, infinitesimal (used for definition of absorbed dose), small, large or intermediate, are reviewed. Burlin theory is applied to estimate photon energies at which cavity sizes in the range 1 nm-10 mm can be considered small or large. Photon and electron energy spectra are calculated at 1 cm distance from the central axis in cylindrical phantoms of bone, muscle and adipose tissue for 20, 50, 300 keV photons and photons from 125I, 169Yb and 192Ir sources; ratios of mass-collision-stopping powers and mass energy absorption coefficients are calculated as applicable to convert Dmed into Dw,med for small and large cavities. Results show that 1-10 nm sized cavities are small at all investigated photon energies; 100 µm cavities are large only at photon energies <20 keV. A choice of an appropriate conversion coefficient Dw, med/Dmed is discussed in terms of the cavity size in relation to the size of important cellular targets. Free radicals from DNA bound water of nanometre dimensions contribute to DNA damage and cell killing and may be the most important water compartment in cells implying use of ratios of mass-collision-stopping powers for converting Dmed into Dw,med.

  19. The 1997 determination of the Australian standards of exposure and absorbed dose at {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Huntley, R.B.; Boas, J.F. [Australian Radiation Laboratory, Yallambie, VIC (Australia); Van der Gaast, H. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1998-05-01

    The arrangements for the maintenance of the Australian standards for {sup 60}Co are described in detail. The primary standards are a graphite cavity chamber for exposure/air kerma and a graphite calorimeter for absorbed dose. These secondary standards are described and their responses in corresponding {sup 90}Sr reference sources are reported. Accurate ratios between the Australian Radiation Laboratory (ARL) and Australian Nuclear Science and Technology (ANSTO) {sup 90}Sr reference sources are derived for use in future calibrations. The value of 28.8 years for the half-life of {sup 90}Sr is confirmed. The usefulness of {sup 90}Sr reference source measurements in quality assurance is discussed. The charge sensitivity and linearity of the ANSTO electrometers are reported by two different methods and are compared with previous results. Calibration factors for all the secondary standard ionization chambers are given, in terms of exposure, air kerma and absorbed dose to water. Calibration factors are also given for most of the chambers in terms of absorbed dose to graphite. The methods of deriving the calibration factors are explained in detail, including all the corrections applied to both the primary and secondary standard measurements. Three alternative methods of deriving the absorbed dose to water calibration factors are compared. The reported calibration factors are compared with previous results. Changes in the Australian units of exposure, air kerma and absorbed dose to graphite and water are derived from changes in the corresponding calibration factors. The Australian units of exposure and air kerma have not changed significantly since 1990. The Australian unit of absorbed dose to graphite is now 1.1 % smaller than in 1993 and 1.3 % smaller than in 1990. The Australian unit of absorbed dose to water is now 1.4 % smaller than in 1993, but is only 0.9 % smaller than in 1990. Comparisons of the Australian standards of exposure/air kerma and absorbed dose with those of the Bureau International des Poids et Mesures (BIPM) were performed in 1997 and show that the Australian units fall within the range of those of other countries. (authors) 31refs., 19 tabs., 8 figs.

  20. The 1997 determination of the Australian standards of exposure and absorbed dose at 60Co

    International Nuclear Information System (INIS)

    The arrangements for the maintenance of the Australian standards for 60Co are described in detail. The primary standards are a graphite cavity chamber for exposure/air kerma and a graphite calorimeter for absorbed dose. These secondary standards are described and their responses in corresponding 90Sr reference sources are reported. Accurate ratios between the Australian Radiation Laboratory (ARL) and Australian Nuclear Science and Technology (ANSTO) 90Sr reference sources are derived for use in future calibrations. The value of 28.8 years for the half-life of 90Sr is confirmed. The usefulness of 90Sr reference source measurements in quality assurance is discussed. The charge sensitivity and linearity of the ANSTO electrometers are reported by two different methods and are compared with previous results. Calibration factors for all the secondary standard ionization chambers are given, in terms of exposure, air kerma and absorbed dose to water. Calibration factors are also given for most of the chambers in terms of absorbed dose to graphite. The methods of deriving the calibration factors are explained in detail, including all the corrections applied to both the primary and secondary standard measurements. Three alternative methods of deriving the absorbed dose to water calibration factors are compared. The reported calibration factors are compared with previous results. Changes in the Australian units of exposure, air kerma and absorbed dose to graphite and water are derived from changes in the corresponding calibration factors. The Australian units of exposure and air kerma have not changed significantly since 1990. The Australian unit of absorbed dose to graphite is now 1.1 % smaller than in 1993 and 1.3 % smaller than in 1990. The Australian unit of absorbed dose to water is now 1.4 % smaller than in 1993, but is only 0.9 % smaller than in 1990. Comparisons of the Australian standards of exposure/air kerma and absorbed dose with those of the Bureau International des Poids et Mesures (BIPM) were performed in 1997 and show that the Australian units fall within the range of those of other countries. (authors)

  1. Neutron absorbed dose rate with 252 Cf sources for medical applications

    Directory of Open Access Journals (Sweden)

    L. Paredes

    2010-01-01

    Full Text Available The 252 Cf brachytherapy reduces the effect caused by the tumor hypoxia in photon radiotherapy and chemotherapy. The AAPM TG-43 modified formalism was used for the calculation of the fast neutron absorbed dose rate of 252 Cf brachytherapy sources for normal tissues and malignant tumors. Three models of HDR 252 Cf sources; AT, VariSource and ?Selectron were simulated using spherical geometry, Watt fission spectrum and the MCNPX code. The results show that small variations in the elemental composition between the normal tissues and malignant tumors, produce variations in the reference fast neutron absorbed dose rate up to 14%.

  2. Neutron absorbed dose rate with 252Cf sources for medical applications

    International Nuclear Information System (INIS)

    The 252Cf brachytherapy reduces the effect caused by the tumor hypoxia in photon radiotherapy and chemotherapy. The AAPM T G-43 modified formalism was used for the calculation of the fast neutron absorbed dose rate of 252Cf brachytherapy sources for normal tissues and malignant tumors. Three models of Hdr 252Cf sources; At, Vari Source and ?Selectron were simulated using spherical geometry, Watt fission spectrum and the MCNPX code. The results show that small variations in the elemental composition between the normal tissues and malignant tumors, produce variations in the reference fast neutron absorbed dose rate up to 14%. (Author)

  3. Development of graphite calorimeter for absorbed dose to water at NMIJ

    International Nuclear Information System (INIS)

    Full text: The graphite calorimeter was developed for absolute measurements of absorbed dose to water at NMIJ/AIST, Japan. To minimize the influence from outer temperature, the core area is covered with jacked and shield layer. The temperature-measuring thermistor of the core is connected to a AC Wheatstone bridge, and the resistance change is measured by lock-in amplifier and nano voltmeter. Some correction factors for evaluation of absorbed dose to water were estimated by EGS5 Monte Carlo simulations. (author)

  4. Optical fibre temperature sensor technology and potential application in absorbed dose calorimetry

    International Nuclear Information System (INIS)

    Optical fibre based sensors are proposed as a potential alternative to the thermistors traditionally used as temperature sensors in absorbed dose calorimetry. The development of optical fibre temperature sensor technology over the last ten years is reviewed. The potential resolution of various optical techniques is assessed with particular reference to the requirements of absorbed dose calorimetry. Attention is drawn to other issues which would require investigation before the development of practical optical fibre sensors for this purpose could occur. 192 refs., 5 tabs., 4 figs

  5. Model of the absorbed dose on a small sphere into a gamma irradiation field

    International Nuclear Information System (INIS)

    Several models of the absorbed dose calculated as the energy deposited by the secondary electrons on a small volume sphere are presented. The calculations use the Compton scattering of a uniform photon beam in water, the photon attenuation and the electron stopping power are included. The sphere total absorbed dose is due to the stopping of the electrons generated in three regions: into the sphere volume, ahead and behind the sphere volume. Calculations are performed for spheres of different radius and placed at various depth of the vacuum - water interface. (author)

  6. Absorbed dose distribution at a large scale gamma irradiator - a data analysis

    International Nuclear Information System (INIS)

    Laboratory experiments on the sand samples separated from sludge have been carried out to study their uncertainty associated with dose response and calibration. The uniformity of absorbed dose in a batch of sludge in a large-scale liquid sludge gamma irradiator has been examined by using sand samples separated from sludge as an in-situ dosimeter. Statistical analysis of the data, by applying ANOVA test, has been used to evaluate uniformity of dose. The re-circulation time for irradiation of sewage sludge to a dose of 3 kGy for its disinfection has been optimized using the data obtained. (author)

  7. Dose determination with nitro blue tetrazolium containing radiochromic dye films by measuring absorbed and reflected light

    DEFF Research Database (Denmark)

    Kovács, A.; Baranyai, M.

    2000-01-01

    Tetrazolium salts as heterocyclic organic compounds are known to form highly coloured, water insoluble formazans by reduction, which can be utilized in radiation processing dosimetry. Radiochromic films containing nitro blue tetrazolium dissolved in a polymer matrix were found suitable for dose determination in a wide dose range both by absorbance and reflectance measurements. The concept of measuring reflected light from dose labels has been discussed earlier and emerged recently due to the requirement of introducing semiquantitative label dose indicators for quarantine control. The usefulness of the method was studied using the newly developed radiochromic dye films as well as already existing ones. (C) 2000 Elsevier Science Ltd. All rights reserved.

  8. Plasma membrane permeabilization by 60- and 600-ns electric pulses is determined by the absorbed dose.

    Science.gov (United States)

    Ibey, Bennett L; Xiao, Shu; Schoenbach, Karl H; Murphy, Michael R; Pakhomov, Andrei G

    2009-02-01

    We explored how the effect of plasma membrane permeabilization by nanosecond-duration electric pulses (nsEP) depends on the physical characteristics of exposure. The resting membrane resistance (R(m)) and membrane potential (MP) were measured in cultured GH3 and CHO cells by conventional whole-cell patch-clamp technique. Intact cells were exposed to a single nsEP (60 or 600 ns duration, 0-22 kV/cm), followed by patch-clamp measurements after a 2-3 min delay. Consistent with earlier findings, nsEP caused long-lasting R(m) decrease, accompanied by the loss of MP. The threshold for these effects was about 6 kV/cm for 60 ns pulses, and about 1 kV/cm for 600 ns pulses. Further analysis established that it was neither pulse duration nor the E-field amplitude per se, but the absorbed dose that determined the magnitude of the biological effect. In other words, exposure to nsEP at either pulse duration caused equal effects if the absorbed doses were equal. The threshold absorbed dose to produce plasma membrane effects in either GH3 or CHO cells at either pulse duration was found to be at or below 10 mJ/g. Despite being determined by the dose, the nsEP effect clearly is not thermal, as the maximum heating at the threshold dose is less than 0.01 degrees C. The use of the absorbed dose as a universal exposure metric may help to compare and quantify nsEP sensitivity of different cell types and of cells in different physiological conditions. The absorbed dose may also prove to be a more useful metric than the incident E-field in determining safety limits for high peak, low average power EMF emissions. PMID:18839412

  9. Determination of absorbed dose in the experimental animal irradiated on the Leksell gamma knife

    International Nuclear Information System (INIS)

    The purpose of this study was to evaluate and quantify inaccuracy of Leksell GammaPlan relative and absolute dose calculations for the experimental animal and to determine necessary corrections that must be applied. Both TLD and semiconductor detectors appeared to be suitable for measurement of absorbed dose in the rat brain irradiated on the Leksell gamma knife. Both detectors, due to their size, measured mean doses, nay doses to maximum. The Leksell GammaPlan treatment planning system can be employed for the calculation of absorbed doses even in such an extreme condition like irradiation of experimental animals. However, in our concrete case, it was necessary to apply correction factor of 1.0779 for the absolute absorbed dose to obtain reliable results. Comparison of dose profiles in all three axis calculated by the treatment planning system and measured ones by polymer gel dosimeter showed acceptable agreement. Results presented in this study are strictly related to the Leksell GammaPlan treatment planning system and the special fixation device developed in Na Homolce Hospital. (authors)

  10. New method to drive absorbed dose to water from the primary standard graphite calorimeter

    International Nuclear Information System (INIS)

    Full text: The Australian primary standard of absorbed dose is a graphite calorimeter. In order to determine absorbed dose to water, ARPANSA used to use the photon fluence scaling theorem. However, recent improvements in Monte Carlo codes and computer power mean that it is possible to calculate this conversion factor at the required accuracy. We present these calculations and the uncertainty calculation for the new conversion method. EGSnrc Monte Carlo models of the Co-60 source and ARPANSA Medical Standards Linac were bench marked against measured profiles and percentage depth dose curves. The phase space files from these models were then used in another Monte Carlo model to calculate the ratio of absorbed dose to graphite at the calorimeter core to absorbed dose to water in a water phantom. Two NE 2561 chambers were calibrated at ARPANSA using this conversion factor, and then sent to the National Physical Laboratory in the UK for calibration at Co-60 and 6, 10 and 18 MV linac photon beams. The results of the comparison with NPL indicate good agreement at Co-60, 6X and [OX (within 0.3%) and relatively poor agreement at 18X (2%). ARPANSA is planning to adopt the new method for Co60 and is awaiting the results of further work before adopting the method for linac beams. We expect ARPANSA Co-60 calibration coefficients to change by 0.5% as a result of adopting the new method. (author)

  11. Monte Carlo simulation of conversion of absorbed dose in different medium for gamma-ray

    International Nuclear Information System (INIS)

    The EGSnrc Monte Carlo Code was used to calculate the converting factor of absorbed dose to water to absorbed dose to silicon. The factor is useful in the study of irradiation effects in semiconductor devices. The irradiation source, water and silicon phantom were simulated by EGSnrc code. The electron equilibrium thickness were calculated for water and silicon irradiated by 60Co gamma-ray. The factor was calculated in two ways, one is average of energy fluence of photon, the other is ratio of dose. The results showed that the factor from tow ways agreed with the result from the national standard GB/T 15447-2008. This calculating methed can be used to determinate the dose conversion of two medium that they have very different atomic number. (authors)

  12. Methods to verify absorbed dose of irradiated containers and evaluation of dosimeters

    International Nuclear Information System (INIS)

    The research on dose distribution in irradiated food containers and evaluation of several methods to verify absorbed dose were carried out. The minimum absorbed dose of treated five orange containers was in the top of the highest or in the bottom of lowest container. Dmax/Dmin in this study was 1.45 irradiated in a commercial 60Co facility. The density of orange containers was about 0.391g/cm3. The evaluation of dosimeters showed that the PMMA-YL and clear PMMA dosimeters have linear relationship with dose response, and the word NOT in STERIN-125 and STERIN-300 indicators were covered completely at the dosage of 125 and 300 Gy respectively. (author)

  13. Radiation-Induced Color Centers in LiF for Dosimetry at High Absorbed Dose Rates

    DEFF Research Database (Denmark)

    McLaughlin, W. L.; Miller, Arne

    1980-01-01

    Color centers formed by irradiation of optically clear crystals of pure LiF may be analyzed spectrophotometrically for dosimetry in the absorbed dose range from 102 to 107 Gy. Routine monitoring of intense electron beams is an important application. Both 6LiF and 7LiF forms are commercially available, and when used with filters as albedo dosimeters in pairs, they provide discrimination of neutron and gamma-ray doses.

  14. Assessment of absorbed dose rate from terrestrial gamma radiation in Red Sea State

    International Nuclear Information System (INIS)

    This study is primarily conducted to contribute in the overall strategic objective of producing Sudan radiation map which will include natural radiation levels and the resultant absorbed dose rate in air. The part covered by this study is the Red Sea State. Soil samples were collected from locations lie between latitudes 17.03° and the 20.18° N and longitudes 36.06° E during September 2007. Activity concentrations of the primordial radionuclides, 226Ra, 232Th, and 40K in the samples were measured using gamma-ray spectrometry equipped with Nal (Tl) detector. Absorbed dose rates in air a height of 1 from the ground level and the corresponding annual effective doses were calculated from the measured activities using Dose Rate Conversion Factors (DRCFs). On the average, the activity concentrations were 19.22±13.13 Bq kg-1 (232Th), 17.91±15.44 Bq kg-1 (226Ra) and (507.13±161.67) Bq kg-1 for 40K. The obtained results were found to be within the global values reported in the UNSCEAR publication for normal background areas with the exception of the samples taken from Arbaat area. The absorbed dose rate in air as calculated using UNSCEAR conversion factor averaged 40.93 n Gy h-1 which corresponds to annual effective dose of 50.23 ?Svy-1. The major contribution to the total absorbed dose ratamounts to 53.36%. Using Geographical Information System (GIS), predication maps for activity concentrations levels of the measured radionuclides in the Red Sea state was prepared to show their respective spatial distributions. Similarly, GIS predictive map was produced for annual effective dose.(Author)

  15. Monte Carlo simulation of trabecular bone remodeling and absorbed dose coefficients for tritium and 14C

    International Nuclear Information System (INIS)

    A Monte Carlo simulation of multiple trabecular bone cavities in adult bone was developed and the absorbed radiation dose factors evaluated for 3H and 14C. The model was developed to assess the dose from radionuclide uptake in quiescent bone, but also the effects of temporal changes in bone turnover by incorporating bone-modelling units (BMU). Absorbed dose fractions were calculated for target regions that include the endosteal layer where radiation-sensitive stem cells in bone marrow are considered to reside preferentially. There were large differences in the absorbed fractions for two types of bone surface, quiescent and forming. Tritium in quiescent bone results in a dose to the endosteum about 20 times that for the same activity in forming bone surface irradiating osteoblasts. When the quiescent bone surface source was extended from an infinitely thin layer to a more realistic 1 mm thick, the tritium absorbed fractions for endosteum and red marrow targets fell by more than 2-fold. (authors)

  16. Determination of gamma spectrum and absorbed dose in the center of the HERBE system

    International Nuclear Information System (INIS)

    It is important to know the influence of neutron and gamma radiation on sample during irradiation in the centre of the reactor system HERBE. It was the reason for measuring the gamma energy spectrum as well as corresponding absorbed radiation dose. In this paper the results of measurements are shown.(author)

  17. Neutron absorbed doses in fast neutron fields at the RB reactor

    International Nuclear Information System (INIS)

    Two configurations of the coupled fast-thermal system (CFTS) are given. The axial distributions of fast neutron flux density are measured in these fields. The axial distributions of fast neutron absorbed doses are computed on the basis of mentioned experimental results. These distributions are compared at the end of this paper. (author)

  18. Radiation absorbed dose distribution in a patient treated with yttrium-90 microspheres for hepatocellular carcinoma

    International Nuclear Information System (INIS)

    We have implemented a three-dimensional dose calculation technique accounting for dose inhomogeneity within the liver and tumor of a patient treated with 90Y microspheres. Single-photon emission computed tomography (SPECT) images were used to derive the activity distribution within liver. A Monte Carlo calculation was performed to create a voxel dose kernel for the 90Y source. The activity distribution was convolved with the voxel dose kernel to obtain the three-dimensional (3D) radiation absorbed dose distribution. An automated technique was developed to accurately register the computed tomography (CT) and SPECT scans in order to display the 3D dose distribution on the CT scans. In addition, dose-volume histograms were generated to fully analyze the tumor and liver doses. The calculated dose-volume histogram indicated that although the patient was treated to the nominal whole liver dose of 110 Gy, only 16% of the liver and 83% of the tumor received a dose higher than 110 Gy. The mean tumor and liver doses were 163 and 58 Gy, respectively

  19. Simulation of absorbed dose in human blood with MCNP 4C code

    International Nuclear Information System (INIS)

    Biological dosimetry, based on the analysis of solid stained dicentric chromosomes, has been used since the mid 1960s. The intervening years have seen great improvements bringing the technique to a point where dicentric analysis has become a routine component of the radiological protection programs of many countries. Experience of its application in thousands of cases of actual or suspected overexposures has proved the worth of the method. The aberrations scored in the lymphocytes are interpreted in terms of absorbed dose by reference to a dose response calibration curve. This curve will have been produced by exposure of blood in vitro to doses of the appropriate quality of radiation. The doses given to the specimens should be traceable via a physical instrument such as an ionization chamber, to a primary or secondary standard. An alternative to obtain the information about absorbed dose in a specific blood volume is through the Monte Carlo method. The use of such technique is worldwide when physical measurements are inconvenient or impossible, and particularly useful for the solution of complex problems that cannot be modeled by codes that use deterministic methods. It is applied to particle systems as neutrons and electrons, as well as photons or still in mixed systems. Due to difficulties that involve the use of neutrons, this technique has shown extreme importance for preliminary research and experimental arrangements with neutron sources. In this study, the main objective was to simulate the dose absorbed by a blood sample in an experimental arrangement through the irradiation with sources of 241AmBe. It was used the code Monte Carlo N-Particle version 4C (MCNP 4C) whose data had been processed parallel in a computational structure in a cluster. This method allowed estimating the absorbed dose in a specific blood volume, making possible the experimental setup arrangement. (author)

  20. Status of air kerma and absorbed dose standards in India

    International Nuclear Information System (INIS)

    Full text: The Radiation Safety Systems Division of Bhabha Atomic Research Centre, India maintains Primary and Secondary Standards of various parameters of radiation measurements and provides calibration services to various users of radiation in the country. This is an apex laboratory in India and plays a pivotal role in ensuring accurate radiological measurements. The laboratory coordinates national intercomparisons of radiation measurements to maintain their uniformity and traceability and is linked through various programmes with the other International organizations such as Bureau Internationale des Poids et Mesures (BIPM) Paris, International Atomic Energy Agency (IAEA) Vienna, Asia Pacific Metrology Programme (APMP) Taiwan. It is the recognized Regional Secondary Standards Dosimetry Laboratory (SSDL) of IAEA/WHO (World Health Organisation). This paper brings out the status of various primary and secondary standards for radiological measurements maintained at BARC. 1. Primary Exposure/Air-kerma standard at Co-60 energy (therapy level): The primary standard for exposure/ air-kerma measurements maintained at BARC is a graphite cavity chamber of volume 4.362 cc with an internal diameter of 1.8 cm, internal height of 1.78 cm and wall thickness of 704.3mg/cm2. Correction factors for the difference between electron stopping powers, photon mass energy absorption coefficients of air and graphite wall, correction for recombination, radiation field non-uniformity, stem scatter and polarity effect are applied and the maximum overall uncertainty in the realisation of exposure/air-kerma is around ±1%. This standard has been intercompared with IAEA and BIPM through transfer standard and the agreement in the results are better than ±1%. An intercomparison under the APMP programme is to be held during May, 2002. 2. Primary Exposure/Air-kerma standard at protection and brachytherapy level: A set of three spherical graphite-walled cavity chambers of different air-volumes are maintained as primary standards for protection level and brachytherapy measurements of Ir-192, Cs-137 and Co-60 sources. These chambers are made of high purity reactor-grade graphite of density 1700 kg/m3. The three chambers have different wall thickness, the external diameters of all the chambers being equal. A reference standard in the form of a re-entrant chamber developed at BARC, calibrated against this primary standard was intercompared with a reference standard from M.D Anderson Centre, Houston, U.S.A and the results showed a good agreement. Recently one of the chambers was used for the Cs-137 intercomparison with IAEA and showed an agreement of better than ± 1%. 3. Primary Standard for X-rays - the free air chamber (FAC): This facility is utilized in conjunction with a Philips RT-250 X-ray machine for calibrating secondary standard dosemeters at different X-ray qualities in the 75 to 250 kV range. The total uncertainty in the realization of air kerma is around ±1% using the free air chamber. Accuracy of calibration of the secondary standards is estimated to be better than ±2%. The FAC has been intercompared via transferable transfer standards with FACs at BIPM (1971), BNM (France) RCL (Canada) and Kriss (Korea), which showed good agreement within ±1% after necessary correction for the spectral differences in X-ray beams. BARC is just now taking part in intercomparisons of X-ray air kerma calibration factors organised by Institute of Nuclear Energy Research (INER), Taiwan under Asia Pacific Metrology Programme. In addition to the above-mentioned primary standards, the SSDL is also maintaining the following secondary standards. For air kerma measurements at Co-60 gamma energy, ionisation chambers of Exradin A3, NE2571, NE2577 and Victoreen 415 types are calibrated and maintained. For Co-60 radiation dose to water measurements, NE 2571 and NE 2577 chambers calibrated at BIPM in terms of ND,W are maintained. For air kerma at medium energy x-rays, chambers of the type Exradin A2, NE 2571, NE2577, Victoreen 415 B, Victoreen 415, Exradin A3 and NE 2581 are

  1. The METAS absorbed dose to water calibration service for high energy photon and electron beam radiotherapy

    International Nuclear Information System (INIS)

    Full text: The Swiss Federal Office of Metrology and Accreditation (METAS) provides an absorbed dose to water calibration service for reference dosimeters using 60Co ? radiation, ten X-ray beam qualities between TPR20,10=0.639 and 0.802 and ten electron beam qualities between R50=1.75 gcm-2 and 8.54 gcm-2. A 22 MeV microtron accelerator with a conventional treatment head is used as radiation source for the high energy photon and electron beams. The treatment head produces clinical beams. The METAS absorbed dose calibration service for high energy photons is based on a primary standard sealed water calorimeter of the Domen type, that is used to calibrate several METAS transfer standards of type NE2611A and NE2571A in terms of absorbed dose to water in the energy range from 60Co to TPR20,10 = 0.802. User reference dosimeters are compared with the transfer standards to give calibration factors in absorbed dose to water with an uncertainty of 1.0% for 60Co ? radiation and 1.4% for higher energies (coverage factor k=2). The calibration service was launched in 1997. The calibration factors measured by METAS have been compared with those derived from the Code of Practice of the International Atomic Energy Agency using the calculated kQ factors listed in table 14. The comparison showed a maximum difference of 0.8% for the NE25611A and NE 2571A chambers. At 60Co ? radiation the METAS primary standard of absorbed dose to water was bilaterally compared with the primary standards of the Bureau International des Poids et Mesures BIPM (Sevres) as well as of the National Research Council NRC (Canada). In either case the standards were in agreement within the comparison uncertainties. The METAS absorbed dose calibration service for high energy electron beams is based on a primary standard chemical dosimeter. A monoenergetic electron beam of precisely known particle energy and beam charge is totally absorbed in Fricke solution (ferrous ammonium sulphate) of a given mass. This experiment is similar to the one described by Feist, but extended to an energy range from 5.3 MeV to 22.4 MeV, allowing to determine the energy dependence of the response of the Fricke dosimeter. The absorbed dose to Fricke solution is determined using the particle energy, the total beam charge and the mass of the solution. The absorbed dose to Fricke solution is converted to an absorbed dose to water applying a general conversion factor taken from Ma et al. The thus calibrated Fricke solution is then used to calibrate several METAS plane-parallel transfer ionisation chambers of type NACP-02 in the mentioned energy range. The user dosimeters are finally compared to the METAS transfer standards following the procedures described in IAEA Technical Reports Series No. 398. It is anticipated that the overall uncertainty in the calibration factor of a user dosimeter will be around 2% (coverage factor k=2). (author)

  2. Skin Absorbed Doses from Full Mouth Standard Intraoral Radiography in Bisecting Angle and Paralleling techniques

    International Nuclear Information System (INIS)

    This study was performed to measure the skin absorbed doses from full mouth standard intraoral radiography(14 exposures) in bisecting angle and paralleling techniques. Thermoluminescent dosimeters were used in a phantom. Circular tube collimator (60 mm in diameter, 20 cm in length) and rectangular collimator (35 mm X 44 mm, 40 cm in length) were set for bisecting angle and paralleling techniques respectively. All measurement sites were classified into 8 groups according to distance from each point of central rays. The results were as follows: 1. The skin absorbed doses from the paralleling technique were significantly decreased than those from the bisecting technique in both points at central ray and points away from central ray. The percentage rats of decrease were greater at points away from central ray than those at central ray. 2. The skin absorbed doses at the lens of eye, parotid gland, submandibular gland and thyroid region were significantly decreased in paralleling technique, but those of the midline of palate remained similar in both techniques. 3. The highest doses were measured at the site 20 mm above the point of central ray for the mandibular premolars in bisecting angle technique and at the point of central ray for the mandibular premolars in paralleling techniques. The lowest doses were measured at the thyroid region in both techniques.

  3. Electron absorbed fractions and dose conversion factors for marrow and bone by skeletal regions

    Energy Technology Data Exchange (ETDEWEB)

    Eckerman, K.F.; Stabin, M.G.

    2000-02-01

    The possible inductions of bone cancer and leukemia are the two health effects of primary concern in the irradiation of the skeleton. The relevant target tissues to consider in the dosimetric evaluation have been the cells on or near endosteal surfaces of bone, from which osteosarcomas are thought to arise, and hematopoietic bone marrow, which is associated with leukemia. The complex geometry of the soft tissue-bone intermixture makes calculations of absorbed doses to these target regions a difficult problem. In the case of photon or neutron radiations, charged particle equilibrium may not exist in the vicinity of a soft tissue-bone mineral interface. In this paper, absorbed fraction data are developed for calculations of the dose in the target tissues from electron emitters deposited within the volume or on the surfaces of trabecular bone. The skeletal average absorbed fractions presented are consistent with usage of this quantity in the contemporary dosimetric formulations of the International Commission on Radiological Protection (ICRP). Implementation of the new bone and marrow model is then developed within the context of the calculational schema of the Medical Internal Radiation Dose (MIRD) Committee. Model parameters relevant to the calculation of dose conversion factors (S values) for different regions of the skeleton of individuals of various age are described, and an example calculation is performed for a monoclonal antibody which localizes in the marrow. The utility of these calculations for radiation dose calculations in nuclear medicine is discussed.

  4. The Effect of Diagnostic Absorbed Doses from 131I on Human Thyrocytes in Vitro

    Directory of Open Access Journals (Sweden)

    Zbigniew Adamczewski

    2015-06-01

    Full Text Available Background: Administration of diagnostic activities of 131I, performed in order to detect thyroid remnants after surgery and/or thyroid cancer recurrence/metastases, may lead to reduction of iodine uptake. This phenomenon is called “thyroid stunning”. We estimated radiation absorbed dose-dependent changes in genetic material, in particular in sodium iodide symporter (NIS gene promoter, and NIS protein level in human thyrocytes (HT. Materials and Methods: We used unmodified HT isolated from patients subjected to thyroidectomy exposed to 131I in culture. The different 131I activities applied were calculated to result in absorbed doses of 5, 10, and 20 Gy. Results: According to flow cytometry analysis and comet assay, 131I did not influence the HT viability in culture. Temporary increase of 8-oxo-dG concentration in HT directly after 24 h (p < 0.05 and increase in the number of AP-sites 72 h after termination of exposition to 20 Gy dose (p < 0.0001 were observed. The signs of dose-dependent DNA damage were not associated with essential changes in the NIS expression on mRNA and protein levels. Conclusions: Our observation constitutes a first attempt to evaluate the effect of the absorbed dose of 131I on HT. The results have not confirmed the theory that the “thyroid stunning” reduces the NIS protein synthesis.

  5. evaluation of the products yields-absorbed dose relationship for benzene -carbon tetrachloride gamma irradiated system

    International Nuclear Information System (INIS)

    gas chromatographic peak areas of the major products yields of ?- irradiated carbon tetrachloride - benzene system (chlorobenzene: PhCl, hexachloroethane: C2Cl6, trichloromethyl benzene: CCl3Ph, biphenyl: Ph2) was found to be linearly dependent on absorbed radiation dose from 0 kGy to 236 kGy. the linearity of the curves were evaluated according to regression coefficients (R2), and were found to be 0.9873, 09865,0.9735 and 0.9815 for PhCl, C2Cl6, CCl3Ph, and Ph2 respectively. statistical analysis of GC peak area measurements such as standard deviation, standard error, 95 %, 99 % confidences and % relative standard deviation (RSD) were calculated for each product. the uncertainty associated with products peaks areas as a response of the adsorbed dose was expressed in the term of coefficient of variation (CV %) . reproducibility of the readings at different absorbed doses as well as reliability was discussed. precision was also evaluated, according to CV % values of each product model. moreover, the knowledge of G-value of chlorobenzene in ?-irradiated carbon tetrachloride - benzene system, presents this model as a good candidate for the direct measurement of absorbed dose within the studied dose range.

  6. Simple dynamic model for calculating radiation absorbed dose to the bladder wall

    International Nuclear Information System (INIS)

    A simple model of estimating the radiation absorbed dose to the inner surface of the bladder wall has been developed. This model assumes a spherical bladder shape and takes into account the dynamic nature of the bladder filling and emptying processes. The model also allows for variable voiding schedules and a residual fraction after each voiding. Formulas for estimating the radiation absorbed dose to the bladder wall are derived analytically using classical dose calculation approaches. Two commonly used radiopharmaceuticals, F-18 labeled 2-[F-18]fluoro-2-deoxy-D-glucose (F-18-FDG) for positron imaging and Tc-99m labeled diethylenetriaminepentaacetic acid (Tc-99m-DTPA) for single-photon renal imaging, are employed to demonstrate the utility of this simple model in determining optimal strategies to achieve dose reduction. Computer simulation studies have been performed to investigate the effects of various initial bladder volumes, urine production rates, residual fractions, and voiding schedules. A general recommendation is a comfortably large initial bladder volume, a high urine production rate, and voiding after most of the activity has accumulated in the bladder, when possible. After the first few voidings at their strategically chosen times, more frequent voidings and smaller residual fractions sometimes can also reduce the radiation absorbed dose. 15 references, 14 figures, 1 table

  7. Calculation of absorbed dose of anchorage-dependent cells from internal beta-rays irradiation

    International Nuclear Information System (INIS)

    Objective: To elicit the formula of internal dosimetry in anchorage-dependent cells by beta-emitting radionuclides from uniformly distributed volume sources. Methods: By means of the definition of absorbed dose and the MIRD (Medical International Radiation Dose) scheme the formula of internal dosimetry was reasonably deduced. Firstly, studying the systems of suspension culture cells. Then, taking account of the speciality of the systems of the anchorage-dependent cells and the directions of irradiation, the absorbed dose of anchorage -dependent cells was calculated by the accumulated radioactivity, beta-ray energy, and the volume of the cultured systems. Results: The formula of internal dosimetry of suspension culture cells and anchorage-dependent cells were achieved. At the same time, the formula of internal dosimetry of suspension culture cells was compared with that of MIRD and was confirmed accurate. Conclusion: The formula of internal dosimetry is concise, reliable and accurate

  8. Fetus absorbed dose evaluation in head and neck radiotherapy procedures of pregnant patients

    Energy Technology Data Exchange (ETDEWEB)

    Camargo da C, E.; Ribeiro da R, L. A.; Santos B, D. V., E-mail: etieli@ird.gov.br [Instituto de Radioprotecao e Dosimetria / CNEN, Av. Salvador Allende s/n, Barra de Tijuca, 22783-127 Rio de Janeiro (Brazil)

    2014-08-15

    Each year a considerable amount of pregnant women needs to be submitted to radiotherapeutic procedures to combat malignant tumors. Radiation therapy is often a treatment of choice for these patients. It is possible to use shielding and beam positioning such that the potential dose to the fetus can be minimized. In this work the head and neck cancer treatment of a pregnant patient was experimentally simulated. The patient was simulated by an anthropomorphic Alderson phantom and the absorbed dose to the fetus was evaluated using micro-rod TLD-100 detectors in two conditions, namely protecting the patients abdomen with a 7 cm lead layer and using no abdomen shielding. The aim of this experiment was to evaluate the efficiency of the abdomen protection in reducing the fetus absorbed dose. Irradiations were performed with a Trilogy linear accelerator using x-rays of 6 MV. A total dose of 50 Gy to the target volume was delivered. The fetus doses evaluated with and without the lead shielding were, respectively, 0.52±0.039 and (0.88±0.052) c Gy, corresponding to a dose reduction of 59%. The dose (0.52±0.039) c Gy is within the zone of biological tolerance for the fetus. (Author)

  9. Pain and Mean Absorbed Dose to the Pubic Bone After Radiotherapy Among Gynecological Cancer Survivors

    International Nuclear Information System (INIS)

    Purpose: To analyze the relationship between mean absorbed dose to the pubic bone after pelvic radiotherapy for gynecological cancer and occurrence of pubic bone pain among long-term survivors. Methods and Materials: In an unselected, population-based study, we identified 823 long-term gynecological cancer survivors treated with pelvic radiotherapy during 1991-2003. For comparison, we used a non-radiation-treated control population of 478 matched women from the Swedish Population Register. Pain, intensity of pain, and functional impairment due to pain in the pubic bone were assessed with a study-specific postal questionnaire. Results: We analyzed data from 650 survivors (participation rate 79%) with median follow-up of 6.3 years (range, 2.3-15.0 years) along with 344 control women (participation rate, 72 %). Ten percent of the survivors were treated with radiotherapy; ninety percent with surgery plus radiotherapy. Brachytherapy was added in 81%. Complete treatment records were recovered for 538/650 survivors, with dose distribution data including dose-volume histograms over the pubic bone. Pubic bone pain was reported by 73 survivors (11%); 59/517 (11%) had been exposed to mean absorbed external beam doses <52.5 Gy to the pubic bone and 5/12 (42%) to mean absorbed external beam doses ?52.5 Gy. Thirty-three survivors reported pain affecting sleep, a 13-fold increased prevalence compared with control women. Forty-nine survivors reported functional impairment measured reported functional impairment measured as pain walking indoors, a 10-fold increased prevalence. Conclusions: Mean absorbed external beam dose above 52.5 Gy to the pubic bone increases the occurrence of pain in the pubic bone and may affect daily life of long-term survivors treated with radiotherapy for gynecological cancer.

  10. Dose absorbed by technologists in positron emission tomography procedures with FDG

    Scientific Electronic Library Online (English)

    Ademir, Amaral; Christian, Itié; Bernard, Bok.

    2007-09-01

    Full Text Available O objetivo deste trabalho foi o de avaliar doses absorvidas por profissionais de saúde em diferentes tarefas relacionadas à tomografia por emissão de pósitrons com [18F]-FDG (fluordesoxiglicose). Esta pesquisa foi realizada em dois centros de medicina nuclear na França, os quais apresentavam diferen [...] ças significativas em sua organização e radioproteção. Esses centros aplicavam aproximadamente 300 MBq por exame PET/CT, embora apenas um deles correspondesse a um serviço de medicina nuclear dedicado a exames por PET. A dose equivalente (Hp(10)) e a dose na pele Hp(0,07) foram medidas usando dosímetros eletrônicos (Siemens). Para avaliação da dose nas mãos do tecnologista durante a preparação do radiofármaco e durante injeção no paciente, um dosímetro tipo relógio de pulso (Polimaster) foi empregado. A dose absorvida e o tempo empregado durante cada tarefa foram registrados para um total de 180 exames de corpo inteiro através da PET. Neste trabalho, a metodologia empregada, os resultados e suas conseqüências na dose absorvida para o profissional de saúde são apresentados e discutidos. Abstract in english The objective of this work was to evaluate radiation doses delivered to technologists engaged in different tasks involving positron emission tomography (PET) studies with FDG (fluorodeoxyglucose). This investigation was performed in two French nuclear medicine departments, which presented significan [...] t differences in their arrangements and radiation safety conditions. Both centers administered about 300 MBq per PET/CT study, although only one of them is a dedicated clinical PET center. Dose equivalent Hp(10) and skin dose Hp(0.07) were measured using Siemens electronic personnel dosimeters. For assessment dose absorbed by hands during drawing up of tracer and injection into the patient, a Polimaster wristwatch gamma dosimeter was employed. Absorbed dose and the time spent during each investigated task were recorded for a total of 180 whole-body PET studies. In this report, the methodology employed, the results and their radioprotection issues are presented as well as discussed.

  11. Absorbed dose evaluation of thyroid during nasopharynx and breast carcinoma irradiation by in vivo dosimetry

    International Nuclear Information System (INIS)

    Aims. - The thyroid dysfunction after radiotherapy has led to evaluate the dose received by thyroid during nasopharynx and breast carcinoma irradiation. This evaluation was facilitated by in vivo dosimetry. The aims of this work were to evaluate the thyroid dose and to compare released dose at the reference point in the two localizations. Patients and methods. - A total of 30 patients were evaluated: 18 patients with nasopharynx carcinoma and 12 patients with breast carcinoma were included in the final analysis. In the first group, the total thyroid but the isthmus was irradiated. On the other hand, in the second group, only one thyroid lobe was included into the target volume. All patients have been treated by gamma rays of cobalt 60 and the thyroid absorbed dose was measured by semiconductor dosimeters (Scanditronix DPD6). These dosimeters were calibrated in the same geometric conditions of the irradiation. Results. - The measured absorbed dose of the thyroid parenchyma was equal to the calculated absorbed dose at the target that has being specified at a depth of -3 em. Under the block, the isthmus received 5.1 ± 0.9 Gy (9.9 ± 1.8%) in nasopharynx carcinoma irradiation. However, in breast carcinoma irradiation, the distal thyroid lobe and the isthmus received 2.9 ± 0.7 Gy (6.55 ± 1.56%) and 3.69 ± 0.77 (8.39 ± 1.76%),i respectively. Conclusion. - This study shows that the thyroid received a dose equal to the prescribed dose in both nasopharynx and breast cancein both nasopharynx and breast cancer, patients. It is recommended to. follow the function of the thyroid gland in these patients. (authors)

  12. Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

    Energy Technology Data Exchange (ETDEWEB)

    Willegaignon, J., E-mail: j.willegaignon@gmail.com; Sapienza, M. T.; Coura-Filho, G. B.; Buchpiguel, C. A. [Cancer Institute of São Paulo State (ICESP), Clinical Hospital, School of Medicine, University of São Paulo, São Paulo 01246-000 (Brazil); Nuclear Medicine Service, Department of Radiology, School of Medicine, University of São Paulo, Sao Paulo 01246-000 (Brazil); Watanabe, T. [Nuclear Medicine Service, Department of Radiology, School of Medicine, University of São Paulo, São Paulo 01246-000 (Brazil); Traino, A. C. [Unit of Medical Physics, Azienda Ospedaliero-Universitaria Pisana, Pisa 56126 (Italy)

    2014-01-15

    Purpose: The precise determination of organ mass (m{sub th}) and total number of disintegrations within the thyroid gland (A{sup ~}) are essential for thyroid absorbed-dose calculations for radioiodine therapy. Nevertheless, these parameters may vary according to the method employed for their estimation, thus introducing uncertainty in the estimated thyroid absorbed dose and in any dose–response relationship derived using such estimates. In consideration of these points, thyroid absorbed doses for Graves’ disease (GD) treatment planning were calculated using different approaches to estimating the m{sub th} and the A{sup ~}. Methods: Fifty patients were included in the study. Thyroid{sup 131}I uptake measurements were performed at 2, 6, 24, 48, 96, and 220 h postadministration of a tracer activity in order to estimate the effective half-time (T{sub eff}) of {sup 131}I in the thyroid; the thyroid cumulated activity was then estimated using the T{sub eff} thus determined or, alternatively, calculated by numeric integration of the measured time-activity data. Thyroid mass was estimated by ultrasonography (USG) and scintigraphy (SCTG). Absorbed doses were calculated with the OLINDA/EXM software. The relationships between thyroid absorbed dose and therapy response were evaluated at 3 months and 1 year after therapy. Results: The average ratio (±1 standard deviation) betweenm{sub th} estimated by SCTG and USG was 1.74 (±0.64) and that between A{sup ~} obtained by T{sub eff} and the integration of measured activity in the gland was 1.71 (±0.14). These differences affect the calculated absorbed dose. Overall, therapeutic success, corresponding to induction of durable hypothyroidism or euthyroidism, was achieved in 72% of all patients at 3 months and in 90% at 1 year. A therapeutic success rate of at least 95% was found in the group of patients receiving doses of 200 Gy (p = 0.0483) and 330?Gy (p = 0.0131) when m{sub th} was measured by either USG or SCTG and A{sup ~} was determined by the integration of measured {sup 131}I activity in the thyroid gland and based on T{sub eff}, respectively. No statistically significant relationship was found between therapeutic response and patients’ age, administered {sup 131}I activity (MBq), 24-h thyroid {sup 131}I uptake (%) or T{sub eff} (p ? 0.064); nonetheless, a good relationship was found between the therapeutic response and m{sub th} (p ? 0.035). Conclusions: According to the results of this study, the most effective thyroid absorbed dose to be targeted in GD therapy should not be based on a fixed dose but rather should be individualized based on the patient'sm{sub th} and A{sup ~}. To achieve a therapeutic success (i.e., durable euthyroidism or hypothyroidism) rate of at least 95%, a thyroid absorbed dose of 200 or 330?Gy is required depending on the methodology used for estimating m{sub th} and A{sup ~}.

  13. Graves' disease radioiodine-therapy: Choosing target absorbed doses for therapy planning

    International Nuclear Information System (INIS)

    Purpose: The precise determination of organ mass (mth) and total number of disintegrations within the thyroid gland (A~) are essential for thyroid absorbed-dose calculations for radioiodine therapy. Nevertheless, these parameters may vary according to the method employed for their estimation, thus introducing uncertainty in the estimated thyroid absorbed dose and in any dose–response relationship derived using such estimates. In consideration of these points, thyroid absorbed doses for Graves’ disease (GD) treatment planning were calculated using different approaches to estimating the mth and the A~. Methods: Fifty patients were included in the study. Thyroid131I uptake measurements were performed at 2, 6, 24, 48, 96, and 220 h postadministration of a tracer activity in order to estimate the effective half-time (Teff) of 131I in the thyroid; the thyroid cumulated activity was then estimated using the Teff thus determined or, alternatively, calculated by numeric integration of the measured time-activity data. Thyroid mass was estimated by ultrasonography (USG) and scintigraphy (SCTG). Absorbed doses were calculated with the OLINDA/EXM software. The relationships between thyroid absorbed dose and therapy response were evaluated at 3 months and 1 year after therapy. Results: The average ratio (±1 standard deviation) betweenmth estimated by SCTG and USG was 1.74 (±0.64) and that between A~ obtained by Teff and the integration of measured activity in the gland was 1.71 (±0.14). These differences affect the calculated absorbed dose. Overall, therapeutic success, corresponding to induction of durable hypothyroidism or euthyroidism, was achieved in 72% of all patients at 3 months and in 90% at 1 year. A therapeutic success rate of at least 95% was found in the group of patients receiving doses of 200 Gy (p = 0.0483) and 330?Gy (p = 0.0131) when mth was measured by either USG or SCTG and A~ was determined by the integration of measured 131I activity in the thyroid gland and based on Teff, respectively. No statistically significant relationship was found between therapeutic response and patients’ age, administered 131I activity (MBq), 24-h thyroid 131I uptake (%) or Teff (p ? 0.064); nonetheless, a good relationship was found between the therapeutic response and mth (p ? 0.035). Conclusions: According to the results of this study, the most effective thyroid absorbed dose to be targeted in GD therapy should not be based on a fixed dose but rather should be individualized based on the patient'smth and A~. To achieve a therapeutic success (i.e., durable euthyroidism or hypothyroidism) rate of at least 95%, a thyroid absorbed dose of 200 or 330?Gy is required depending on the methodology used for estimating mth and A~

  14. Comparison of the standards of absorbed dose to water of the OMH and the BIPM for 60Co ? rays

    International Nuclear Information System (INIS)

    A comparison of the standards of absorbed dose to water of the Orszagos Meresugyi Hivatal (OMH), Budapest, Hungary and of the Bureau International des Poids et Mesures (BIPM) has been made in 60Co radiation. The results show that the OMH and the BIPM standards for absorbed dose to water are in close agreement, the difference being within the estimated uncertainty. (authors)

  15. Radiation absorbed doses from iron-52, iron-55, and iron-59 used to study ferrokinetics

    International Nuclear Information System (INIS)

    Biological data obtained principally with Fe-59 citrate are used with physical data to calculate radiation absorbed doses for ionic or weak chelate forms of Fe-52, Fe-55, and Fe-59, administered by intravenous injection. Doses are calculated for normal subjects, primary hemochromatosis (also called idiopathic or hereditary hemochromatosis), pernicious anemia in relapse, iron-deficiency anemia, and polycythemia vera. The Fe-52 doses include the dose from the Mn-52m daughter generated after injection of Fe-52. Special attention has been given to the dose to the spleen, which has a relatively high concentration of RBCs and therefore of radioiron, and which varies significantly in size in both health and disease

  16. Absorbed radiation doses in women undergone to PET-CT exams for cancer diagnosis

    International Nuclear Information System (INIS)

    The absorbed dose in several organs and the effective dose in patients submitted to PET-CT exams with the radiopharmaceutical 18F-FDG were assessed. The ICRP-106 biokinetic model and thermoluminescent detectors in a anthropomorphic phantom were used. The use of the PET-CT image acquisition protocol, with the CT protocol for anatomical mapping, showed that 60% of effective dose was from the radiotracer administration, being the effective dose values for a female patient of (5.80 ± 1.57) mSv. In conclusion, patient doses can be reduced by using appropriate imaging acquisition in 18F-FDG PET-CT examinations and promoting the compliance with the radiation protection principles. (author)

  17. Radiation absorbed doses from iron-52, iron-55, and iron-59 used to study ferrokinetics

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, J.S.; Price, R.R.; Budinger, T.F.; Fairbanks, V.F.; Pollycove, M.

    1983-04-01

    Biological data obtained principally with Fe-59 citrate are used with physical data to calculate radiation absorbed doses for ionic or weak chelate forms of Fe-52, Fe-55, and Fe-59, administered by intravenous injection. Doses are calculated for normal subjects, primary hemochromatosis (also called idiopathic or hereditary hemochromatosis), pernicious anemia in relapse, iron-deficiency anemia, and polycythemia vera. The Fe-52 doses include the dose from the Mn-52m daughter generated after injection of Fe-52. Special attention has been given to the dose to the spleen, which has a relatively high concentration of RBCs and therefore of radioiron, and which varies significantly in size in both health and disease.

  18. Radiation dose absorbed in organs of rat after short time feeding with organically bound tritium (OBT)

    International Nuclear Information System (INIS)

    Wistar rats aged 3 months were given for 5 days standard food supplemented with 126 kBq of OBT or tritiated water (TW). The animals were sacrificed in groups of three on the 1st 6, 11, 16, 31 and 61st day after the end of 5-day feeding. The specific radioactivity of wet and dry tissue of the following organs was determined: brain, lung, heart, kidney, liver, spleen, small intestine, femur and skin (without hair). The radiation doses absorbed in organs after OBT and TW administration were calculated by two methods: assuming that the half time of tritium excretion is constant and equal to the half time of tritiated water excretion from the rat body (method recommended by ICRP) and considering the experimentally determined curve of specific activity of wet and dry mass of the particular organ. It was found that after contamination with TW, the radiation doses calculated by both methods were very similar. The radiation doses absorbed in the wet tissues of rats given OBT were about two times higher than in those given TW. The radiation doses absorbed in the dry mass of organs after OBT were three times as high as after TW. (author)

  19. Microdosimetric measurements for neutron-absorbed dose determination during proton therapy

    International Nuclear Information System (INIS)

    This work presents microdosimetric measurements performed at the Midwest Proton Radiotherapy Inst. in Bloomington, Indiana, USA. The measurements were done simulating clinical setups with a water phantom and for a variety of stopping targets. The water phantom was irradiated by a proton spread out Bragg peak (SOBP) and by a proton pencil beam. Stopping target measurements were performed only for the pencil beam. The targets used were made of polyethylene, brass and lead. The objective of this work was to determine the neutron-absorbed dose for a passive and active proton therapy delivery, and for the interactions of the proton beam with materials typically in the beam line of a proton therapy treatment nozzle. Neutron doses were found to be higher at 45 deg. and 90 deg. from the beam direction for the SOBP configuration by a factor of 1.1 and 1.3, respectively, compared with the pencil beam. Meanwhile, the pencil beam configuration produced neutron-absorbed doses 2.2 times higher at 0 deg. than the SOBP. For stopping targets, lead was found to dominate the neutron-absorbed dose for most angles due to a large production of low-energy neutrons emitted isotropically. (authors)

  20. Calculation of doses absorbed by samples irradiated in epithermal neutron spectra

    International Nuclear Information System (INIS)

    A methodology has been recently developed for evaluation of doses absorbed by samples irradiated in research reactors, in which the partial doses due to thermal neutrons, epithermal neutrons, fast neutrons and gamma radiation are individually quantified. In this methodology the calculation of the dose due to epithermal neutrons assumes that the neutron spectrum in the irradiation device has a 1/E variation over the 0.5 eV to 0.1 MeV range. Although this hypothesis is in general satisfactory there may be specific experimental situations in which it is necessary to describe the spectrum as varying with 1/E 1+?, in which ? takes into account significant deviations relatively to the 1/E variation. In the present work we present a simple formulation for evaluation of doses absorbed by samples in spectra with a 1/E 1+?, based on average elementary kerma factors, calculated for different ? values in the -0.1 to 0.2 range. We conclude that, for most multi-element samples the dose rate is a decreasing function of ?. To evaluate the doses it is necessary to know only their elementary composition and the epithermal neutron flux in the irradiation position. This formulation is valid for irradiation devices located in the neighbourhood of the reactor core, where the spectrum varies usually with 1/E 1+?. Taking into account that experiments can also be done in irradiation devices in which the spectrum does not vary in this way, e.g., in the extremity of irradiation tubes for BNCT, we present graphics with the variation of the elementary kerma factors as function of the neutron energy, in the 0.5 eV - 10 MeV range. It is thus possible to estimate the doses absorbed by multi-element samples, both for epithermal neutrons as well as for an eventual fast neutron contamination

  1. Radiation absorbed dose estimates for [1-carbon-11]-glucose in adults: The effects of hyperinsulinemia

    International Nuclear Information System (INIS)

    As preparation for studies of blood-brain glucose transport in diabetes mellitus, radiation absorbed dose estimates from intravenous administration of [1-11C]-glucose for 24 internal organs, lens, blood and total body were calculated for three physiologic conditions: euinsulinemic euglycemia, hyperinsulinemic euglycemia and hyperinsulinemic hyperglycemia. Cumulated activities in blood, insulin-independent and insulin-dependent compartments were calculated from blood time-activity curves in normal human volunteers and macaques. Apportionment of cumulated activity to individual organs in insulin-dependent and insulin-independent compartments was based on previously published data. Absorbed doses were calculated with the computer program MIRDOSE 3 for the 70-kg adult phantom. S for blood was calculated separately. The heart wall, lungs and spleen were the organs receiving the highest dose. The effect of hyperinsulinemia was demonstrated by the increase in adsorbed dose to the muscle, heart and blood with a decrease to other internal organs. This effect was more pronounced during hyperinsulinemic hyperglycemia. Hyperinsulinemia produced a decrease in effective dose due to the decrease in cumulated activity in organs with specified weighting factors greater than 0.05. The effective dose per study for [1-11C]-glucose is comparable to that reported for 2-deoxy-[2-18F]-glucose. 43 refs., 1 fig., 4 tabs

  2. Total body irradiation with 6MVX-rays. Absorbed dose distribution in a humanoid phantom

    International Nuclear Information System (INIS)

    Dose distribution in a humanoid phantom irradiated with total body irradiation of long SAD techniques by 6MV x-rays are discussed. Absorbed dose are measured by x-ray films or TLDs set in slice of the phntom. Uniformity of dose distribution is compared among the results of irradiations by anterior-posterior opposing two beams, lateral opposing two beams, and these combination (four beams). In the cases of lateral opposing two beams irradiation, irradiation is done with and without water boluses at head and neck region. In the case of four beams (anterior-posterior and bilateral), the uniformity is best among the three irradiation techniques, and the uniformity is within ±10%. In the case of anterior posterior opposing two beams irradiation, the uniformity is rather good, but exceeds ±10%. Lateral opposing two beam irradiation results the worst uniformity. But an application of boluses shows improvent of uniformity of midline of a humanoid phantom. In thoracicregion, as lung is irradiated over high absorbed dose, lung compensator is sufficiently nesessary for dose homogeneous and dose reduction. (author)

  3. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy.

    Science.gov (United States)

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-01

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,?0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380?MeV) was established by interpolating between G-values obtained for Co-60 and 250?kV x-rays.An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength.Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3?mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%.Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%.The combined standard uncertainty in the determination of absorbed dose to water at the reference position for TG-43 (1?cm from the source on the transverse axis, in a water phantom) was estimated to be 0.8% with the dominant uncertainty coming from the determination of the G-value. A comparison with absorbed dose to water obtained using the product of air-kerma strength and the dose rate constant gave agreement within 1.5% for three different Ir-192 sources, which is within the combined standard uncertainties of the two methods. PMID:25988983

  4. The Fricke dosimeter as an absorbed dose to water primary standard for Ir-192 brachytherapy

    Science.gov (United States)

    El Gamal, Islam; Cojocaru, Claudiu; Mainegra-Hing, Ernesto; McEwen, Malcolm

    2015-06-01

    The aim of this project was to develop an absorbed dose to water primary standard for Ir-192 brachytherapy based on the Fricke dosimeter. To achieve this within the framework of the existing TG-43 protocol, a determination of the absorbed dose to water at the reference position, D(r0,?0), was undertaken. Prior to this investigation, the radiation chemical yield of the ferric ions (G-value) at the Ir-192 equivalent photon energy (0.380?MeV) was established by interpolating between G-values obtained for Co-60 and 250?kV x-rays. An irradiation geometry was developed with a cylindrical holder to contain the Fricke solution and allow irradiations in a water phantom to be conducted using a standard Nucletron microSelectron V2 HDR Ir-192 afterloader. Once the geometry and holder were optimized, the dose obtained with the Fricke system was compared to the standard method used in North America, based on air-kerma strength. Initial investigations focused on reproducible positioning of the ring-shaped holder for the Fricke solution with respect to the Ir-192 source and obtaining an acceptable type A uncertainty in the optical density measurements required to yield the absorbed dose. Source positioning was found to be reproducible to better than 0.3?mm, and a careful cleaning and control procedure reduced the variation in optical density reading due to contamination of the Fricke solution by the PMMA holder. It was found that fewer than 10 irradiations were required to yield a type A standard uncertainty of less than 0.5%. Correction factors to take account of the non-water components of the geometry and the volume averaging effect of the Fricke solution volume were obtained from Monte Carlo calculations. A sensitivity analysis showed that the dependence on the input data used (e.g. interaction cross-sections) was small with a type B uncertainty for these corrections estimated to be 0.2%. The combined standard uncertainty in the determination of absorbed dose to water at the reference position for TG-43 (1?cm from the source on the transverse axis, in a water phantom) was estimated to be 0.8% with the dominant uncertainty coming from the determination of the G-value. A comparison with absorbed dose to water obtained using the product of air-kerma strength and the dose rate constant gave agreement within 1.5% for three different Ir-192 sources, which is within the combined standard uncertainties of the two methods.

  5. Absorbed fraction and dose conversion coefficients of alpha particles for radon dosimetry

    Science.gov (United States)

    Nikezic, D.; Yu, K. N.; Vucic, D.

    2001-07-01

    The sensitivity to different relevant parameters of the absorbed fraction of alpha particles emitted from the 222Rn chain in sensitive cells of the tracheo-bronchial tree have been investigated. The structure of the airway wall given by ICRP (ICRP66) has been adopted and employed in the present calculations. The source thickness (mucous gel and sol + cilia), target layer thickness and the depth of the sensitive layers have been varied within reasonable ranges around the default values recommended by ICRP66. The results have shown that the depth of the sensitive layers is the most important parameter in calculating the absorbed fraction. In addition, dose conversion coefficients were calculated and presented along with the absorbed fractions.

  6. Influence of housing condition upon absorbed dose in peritoneal cavity of mouse chronically irradiated with low dose-rate 137Cs-?-rays

    International Nuclear Information System (INIS)

    Full text: An accurate measurement of absorbed dose in mouse body is an essential prerequisite for success of the low dose whole-body exposure experiment. We have developed a specially designed small photoluminescence glass dosimeter (PLD), which is one of the most suitable systems for detecting low level exposures in individual mice monitoring. Using the PLD system, in the present study, we examined the subtle changes in the absorbed dose in mouse body depending on the caging conditions of mice, such as the number of mice housed together in a cage. Increasing number of mice kept in a cage from 1 to 5 reduced significantly the absorbed dose measured individually by PLD in the abdominal cavity to approximately 90%. The body weight of mice affected apparently the absorbed dose. The reduction in the dose by increasing mouse number in a cage is possibly explained in terms of the attenuation of ?-rays by the bodies of neighboring mice in the same cage

  7. Studies of absorbed dose determinations and spatial dose distributions for high energy proton beams

    International Nuclear Information System (INIS)

    Absolute dose determinations were made with three types of ionization chamber and a Faraday cup. Methane based tissue equivalent (TE) gas, nitrogen, carbon dioxide, air were used as an ionizing gas with flow rate of 10 ml per minute. Measurements were made at the entrance position of unmodulated beams and for a beam of a spread out Bragg peak at a depth of 17.3 mm in water. For both positions, the mean value of dose determined by the ionization chambers was 0.993 +- 0.014 cGy for which the value of TE gas was taken as unity. The agreement between the doses estimated by the ionization chambers and the Faraday cup was within 5%. Total uncertainty estimated in the ionization chamber and the Faraday cup determinations is 6 and 4%, respectively. Common sources of error in calculating the dose from ionization chamber measurements are depend on the factors of ion recombination, W value, and mass stopping power ratio. These factors were studied by both experimentally and theoretically. The observed values for the factors show a good agreement to the predicted one. Proton beam dosimetry intercomparison between Japan and the United States was held. Good agreement was obtained with standard deviation of 1.6%. The value of the TE calorimeter is close to the mean value of all. In the proton spot scanning system, lateral dose distributions at any depth for one spot beam can be simulated by the Gaussian distribution. From the Gaussian distributions and the central axis depth doses fbutions and the central axis depth doses for one spot beam, it is easy to calculate isodose distributions in the desired field by superposition of dose distribution for one spot beam. Calculated and observed isodose curves were agreed within 1 mm at any dose levels. (J.P.N.)

  8. [Patient absorbed dose in coronary angiography determined by the flat panel digital detector X-ray system].

    Science.gov (United States)

    Kitai, Takaaki; Ogawa, Takesi; Sano, Sadahiko

    2003-03-01

    The INNOVA 2000, an all-digital cardiovascular X-ray system with flat panel detector, is equipped with a monitoring function that makes it possible to track a patient's absorbed dose by displaying the real-time presumed absorbed dose. We verified this dose monitoring system and evaluated how it is affected by various parameters. We also compared the INNOVA 2000 to a conventional machine, the Advantx LC. The average absorbed dose of the INNOVA 2000 was 1,066 mGy, while that of the Advantx LC was calculated to be 2,028 mGy. Dose reduction with the INNOVA 2000 was 76% at Low mode and 52% even at Normal mode. The INNOVA provides an advantage in lowering absorbed dose, even considering that it has a rectangular image intensifier (I.I.) versus the Advantx LC's round I.I. This comparison was made by cine and digital angiography. PMID:12740566

  9. Patient absorbed dose in coronary angiography determined by the flat panel digital detector X-ray system

    International Nuclear Information System (INIS)

    The INNOVA 2000, an all-digital cardiovascular X-ray system with flat panel detector, is equipped with a monitoring function that makes it possible to track a patient's absorbed dose by displaying the real-time presumed absorbed dose. We verified this dose monitoring system and evaluated how it is affected by various parameters. We also compared the INNOVA 2000 to a conventional machine, the Advantx LC. The average absorbed dose of the INNOVA 2000 was 1,066 mGy, while that of the Adnantx LC was calculated to be 2,028 mGy. Dose reduction with the INNOVA 2000 was 76% at Low mode and 52% even at Normal mode. The INNOVA provides an advantage in lowering absorbed dose, even considering that it has a rectangular image intensifier (I.I.) versus the Advantx LC's round I.I. This comparison was made by cine and digital angiography. (author)

  10. Development of an absorbed dose calorimeter for use in IMRT and small field external beam radiotherapy

    International Nuclear Information System (INIS)

    A calorimeter is in development for the absolute measurement of absorbed dose in small fields and complex fields such as those used to deliver intensity modulated radiation therapy. The probe consists of a spherical graphite core surrounded by and separated from a spherical graphite jacket, enclosed in water-equivalent plastic envelope. A spherical geometry was chosen to give approximately isotropic response and sensitivity to dose gradients. Temperature sensing and electrical heating are provided via small thermistors embedded in the graphite, and the temperatures of each component are actively controlled at a set value. Energy absorbed from radiation is measured by substitution, using the electrical heaters. The basic measurement is one of absorbed dose rate rather than absorbed dose. The device is calibrated in terms of absorbed dose to water under standard reference conditions and corrections to its response, in smaller and irregular non-reference fields, are calculated using EGSnrc Monte Carlo and Comsol MultiPhysics to perform finite element analysis of the heat transfer equation. Linearity of the heat equation plays a critical role in analysing measurement uncertainty and the limits on calorimeter performance. In measurements on the central axis of a small field, volume averaging effects make the correction for beam non-uniformity become dominant when the field size is comparable to the core diameter which, in the initial prototype, is 5 mm. The jacket diameteral prototype, is 5 mm. The jacket diameter is 7 mm. Absorbed dose in the target volume of an IMRT treatment is measured as a time integral of dose rate, summed over the component fields in a multi-field plan, or integrated over the whole arc in an arc therapy treatment. Although the IMRT planned dose is uniform over the target volume, the instantaneous dose rate (i.e. the dose within a component field, or the dose rate during the arc delivery) is spatially non-uniform. Such variations in dose rate drive heat transfers within the calorimeter whose magnitude is inversely proportional to the time constant of heat exchange between core and jacket. So in this case, calorimeter performance is limited by the time taken to complete the delivery of each field or the whole arc. The non water- equivalent components, including gaps, perturb the radiation field being measured, and Monte Carlo simulation of the interactions in the calorimeter is required to evaluate this perturbation. The fluence perturbation correction, and its uncertainty, decreases with core diameter. However this increases the surface to volume ratio of the core, and decreases the time constant associated with heat transfer between core and jacket. In an IMRT treatment there is evidence that volume averaging effects tend to cancel provided the sensitive volume of the detector is entirely contained within the planned target volume. In a calorimetric measurement, this may indicate that the limit on core size could be relaxed so that the core is only contained within the target volume. However the non water-equivalence of the core creates a significant fluence perturbation if the core is too large. Results will be presented from measurements with the initial prototype calorimeter, with perturbation corrections evaluated using EGSnrc Monte Carlo and heat transfer corrections calculated using finite element analysis of the heat transfer equation using COMSOL

  11. The influence of the patient's posture on organ and tissue absorbed doses caused by radiodiagnostic examinations

    International Nuclear Information System (INIS)

    Due to the gravitational force, organ positions and subcutaneous fat distribution change when a standing person lies down on her/his back, which is called 'supine posture'. Both postures, standing and supine, are very common in X-ray diagnosis, however, phantoms used for the simulation of patients for organ and tissue absorbed dose assessments normally represent humans either in standing or in supine posture. Consequently, the exposure scenario simulated sometimes does not match the real X-ray examination with respect to the patient's posture. Using standing and supine versions of mesh-based female and male adult phantoms, this study investigates the 'posture-effect' on organ and tissue absorbed doses for radiographs of the pelvis and the lumbar spine in order to find out if the errors from simulating the false posture are significant. (author)

  12. Absorbed dose from 7-GeV bremsstrahlung in a PMMA phantom.

    Energy Technology Data Exchange (ETDEWEB)

    Job, P. K.; Pisharody, M.; Semones, E.

    1999-08-04

    Electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At the Advanced Photon Source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion devices comes down through the beamlines. The resulting absorbed dose distributions by, this radiation in a 300 mm x 300 mm x 300 mm tissue substitute phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosimeters. The average normalized absorbed dose, in a cross sectional area of 100 mm{sup 2} at a depth of 150 mm of the PMMA phantom, was measured as 3.3 x 10{sup 6} mGy h{sup {minus}1}W{sup {minus}1} for a 7-GeV bremsstrahhmg spectrum.

  13. On the absorbed dose determination method in high energy photon beams

    International Nuclear Information System (INIS)

    The absorbed dose determination method in water, based on standards of air kerma or exposure in high energy photon beams generated by electron with energies in the range of 1 MeV to 50 MeV is presented herein. The method is based on IAEA-398, AAPM TG-51, DIN 6800-2, IAEA-381, IAEA-277 and NACP-80 recommendations. The dosimetry equipment is composed of UNIDOS T 10005 electrometer and different ionization chambers calibrated in air kerma method in a Co60 beam. Starting from the general formalism showed in IAEA-381, the determination of absorbed dose in water, under reference conditions in high energy photon beams, is given. This method was adopted for the secondary standard dosimetry laboratory (SSDL) in NILPRP-Bucharest

  14. Measurement of absorbed dose by 7-GeV bremsstrahlung in a PMMA phantom

    CERN Document Server

    Job, P K; Semones, E

    1999-01-01

    High-energy electron storage rings generate energetic bremsstrahlung photons through radiative interaction of the particle beam with the residual gas molecules and other components inside the storage ring. At synchrotron radiation facilities, where beamlines are channeled out of the storage ring, a continuous bremsstrahlung spectrum, with a maximum energy of the stored particle beam, will be present. At the advanced photon source (APS), where the stored beam energy is 7 GeV, bremsstrahlung generated in the straight sections of the insertion device beamlines, which are a total of 15.38 m in length, can be significant. The contribution from each bremsstrahlung interaction adds up to produce a narrow mono-directional bremsstrahlung beam that comes down through the insertion device beamlines. The resulting absorbed dose distributions by this radiation in a 300 mmx300 mmx300 mm tissue substitute cube phantom were measured with LiF:Mg,Ti (TLD-700) thermoluminescent dosemeters. The normalized absorbed dose, in a cro...

  15. Methodology for determination of absorbed dose by individuals irradiated with neutrons

    International Nuclear Information System (INIS)

    In the present work an innovating methodology is proposed to estimate the absorbed dose received by individuals irradiated with neutrons. The method combines measurements of 24Na and 32P activated in the human body. A detailed study of papers published in the literature reporting neutron measurements in different facilities was combined to the results obtained after irradiation of an anthropomorphic phantom in the Argonauta reactor at the Institute de Engenharia Nuclear (IEN), Rio de Janeiro, Brazil. The results demonstrate that it is possible to correlate the measurements of those two activated elements (24Na e 32P) in order to assess the absorbed dose due to neutrons. A methodology was developed in which it is not necessary to know the neutron spectra inciding over the irradiated person or to use models to treat results of 32P measurements, as occurs with other theoretical and experimental proposed methods. (author)

  16. Absorbed dose assessment in particle-beam irradiated metal-oxide and metal-nonmetal memristors

    Directory of Open Access Journals (Sweden)

    Kneževi? Ivan D.

    2012-01-01

    Full Text Available Absorbed dose was estimated after Monte Carlo simulation of proton and ion beam irradiation on metal-oxide and metal-nonmetal memristors. A memristive device comprises two electrodes, each of a nanoscale width, and a double-layer active region disposed between and in electrical contact with electrodes. Following materials were considered for the active region: titanium dioxide, zirconium dioxide, hafnium dioxide, strontium titanium trioxide and galium nitride. Obtained results show that significant amount of oxygen ion - oxygen and nonmetal ion - nonmetal vacancy pairs is to be generated. The loss of such vacancies from the device is believed to deteriorate the device performance over time. Estimated absorbed dose values in the memristor for different constituting materials are of the same order of magnitude because of the close values of treshold displacement energies for the investigated materials.

  17. Estimation of skin absorbed doses due to subcutaneous leakage of radioactive pharmaceuticals

    International Nuclear Information System (INIS)

    Skin absorbed doses due to subcutaneous leakage of radioactive pharmaceuticals were estimated by three calculating methods. The radioactive pharmaceuticals used in calculation were 67Ga-citrate, 99mTc-HMDP, 111In-Cl, 123I-IMP, 131I-Adosterol, 201Tl-Chloride which are used frequently and in large amount in the daily examination. Time taken to remove contamination, range of contamination and ratio of leakage were assumed to be 30 minutes, 10 cm2 and 30% respectively. The skin absorbed doses calculated on this assumption were less than the threshold value that is found to cause skin disorders by Yamaguchi method. We confirmed the misprints of ICRU report 56 in the process of this calculation. (author)

  18. Calculation of absorbed doses in sphere volumes around the Mammosite using the Monte Carlo simulation code MCNPX

    International Nuclear Information System (INIS)

    The objective of this study is to investigate the changes observed in the absorbed doses in mammary gland tissue when irradiated with a equipment of high dose rate known as Mammosite and introducing material resources contrary to the tissue that constitutes the mammary gland. The modeling study is performed with the code MCNPX, 2005 version, the equipment and the mammary gland and calculating the absorbed doses in tissue when introduced small volumes of air or calcium in the system. (Author)

  19. Standard Guide for Absorbed-Dose Mapping in Radiation Processing Facilities

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2003-01-01

    1.1 This document provides guidance in determining absorbed-dose distributions in products, materials or substances irradiated in gamma, X-ray (bremsstrahlung) and electron beam facilities. Note 1—For irradiation of food and the radiation sterilization of health care products, other specific ISO and ISO/ASTM standards containing dose mapping requirements exist. For food irradiation, see ISO/ASTM 51204, Practice for Dosimetry in Gamma Irradiation Facilities for Food Processing and ISO/ASTM 51431, Practice for Dosimetry in Electron and Bremsstrahlung Irradiation Facilities for Food Processing. For the radiation sterilization of health care products, see ISO 11137: 1995, Sterilization of Health Care Products Requirements for Validation and Routine Control Radiation Sterilization. In those areas covered by ISO 11137, that standard takes precedence. ISO/ASTM Practice 51608, ISO/ASTM Practice 51649, and ISO/ASTM Practice 51702 also contain dose mapping requirements. 1.2 Methods of analyzing the dose map data ar...

  20. Distribution of absorbed dose in human eye simulated by SRNA-2KG computer code

    International Nuclear Information System (INIS)

    Rapidly increasing performances of personal computers and development of codes for proton transport based on Monte Carlo methods will allow, very soon, the introduction of the computer planning proton therapy as a normal activity in regular hospital procedures. A description of SRNA code used for such applications and results of calculated distributions of proton-absorbed dose in human eye are given in this paper. (author)

  1. Retrospective evaluation of absorbed doses in polluted landscapes of the Middlerussian height

    International Nuclear Information System (INIS)

    Retrospective analysis of absorbed dose at low-grade level of contamination of the area by fission-produced radionuclides of the ChNPP was conducted. The mathematical model of gamma field was developed where form, sizes, power of raditing matter, radioisotope composition and gamma spectrum feature were taken into consideration. Leading role of the solid effluence in primary radionuclide migration on contaminated areas was revealed

  2. Estimation and analysis of absorbed dose in high energy electron accelerators

    International Nuclear Information System (INIS)

    The stem predicament, in radiation protection surveillance, posed by the secondary radiations like Bremsstrahlung photons and other particles emitted from unshielded and partially shielded portions of high energy electron particle accelerator facilities, has prompted to do the present simulation studies for the estimation of absorbed dose, in human equivalent water media. Simple empirical relations based on computer simulations using Monte-Carlo methods, are derived so that 'ready reckoners' can be prepared, for the estimation of dose to the persons exposed, by chance, around those facilities. (author)

  3. Absorbed doses and energy imparted from radiographic examination of velopharyngeal function during speech

    International Nuclear Information System (INIS)

    Absorbed doses of radiation were measured by thermoluminescent dosimeters (TLDs) using a skull phantom during simulated cinefluorographic and videofluorographic examination of velopharyngeal function in frontal and lateral projections. Dosages to the thyroid gland, the parotid gland, the pituitary gland, and ocular lens were measured. Radiation dosage was found to be approximately 10 times less for videofluoroscopy when compared with that of cinefluoroscopy. In addition, precautionary measures were found to reduce further the exposure of radiation-sensitive tissues. Head fixation and shielding resulted in dose reduction for both video- and cinefluoroscopy. Pulsing exposure for cinefluoroscopy also reduced the dosage

  4. Investigation of magnevist pharmacokinetics for calculation of absorbed dose at neutron-capture therapy

    International Nuclear Information System (INIS)

    Full text: The neutron-capture therapy with use of gadolinium-containing pharmacological preparations is one of perspective and not enough investigated directions of application of neutron irradiation in medicine. At definition of the absorbed dose of neutron-capture therapy one of important questions is definition of concentration gadolinium and pharmacokinetics in irradiated tumour. In the given study has been investigated pharmacokinetics of gadolinium-containing preparation 'Magnevist' at intratumoral injection in inoculated tumours of sarcoma C180 at mice. For 'Magnevist' detection its property of radioopacity has been used. In experiments to mice with inoculated tumours C180 the various doses of 'Magnevist' (0.1, 0.2, 0.3 and 0.4 ml) were injected into tumour centre. X-ray images were made before 'Magnevist' injection (control) and after preparation injection every 5 minutes within one hour. It has been shown that at dose 0.1 ml 'Magnevist' eliminated from tumour within 10 minutes. At higher doses of preparation more slow elimination of 'Magnevist' from injection site was observed. Obtained results allow with sufficient accuracy to calculate the time of presence of optimum concentration of 'Magnevist' in tumour at intratumoral injection. It in turn gives the chance to calculate precisely the absorbed dose at irradiation by beam of epi-thermal neutrons. (author)

  5. Development of fluorescent, oscillometric and photometric methods to determine absorbed dose in irradiated fruits and nuts

    International Nuclear Information System (INIS)

    To ensure suitable quality control at food irradiation technologies and for quarantine authorities, simple routine dosimetry methods are needed for absorbed dose control. Taking into account the requirements at quarantine locations these methods would require nondestructive analysis for repeated measurements. Different dosimetry systems with different analytical evaluation methods have been tested and/or developed for absorbed dose measurements in the dose range of 0.1-10 kGy. In order to use the well accepted ethanolmonochlorobenzene dosimeter solution and the recently developed aqueous alanine solution in small volume sealed vials, a new portable, digital, and programmable oscillometric reader was developed. To make use of the availability of the very sensitive fluorimetric evaluation method, liquid and solid inorganic and organic dosimetry systems were developed for dose control using a new routine, portable, and computer controlled fluorimeter. Absorption or transmission photometric methods were also applied for dose measurements of solid or liquid phase dosimeter systems containing radiochromic dye agents, which change colour upon irradiation. (author)

  6. Depth absorbed dose characteristics for several medical electron accelerators. According to the JASTRO QA program

    International Nuclear Information System (INIS)

    Depth absorbed dose characteristics of both X-ray and electron radiation have been investigated on 10 accelerators according to the JASTRO QA program. Absorbed doses at the calibration point and at a depth specified in the program were measured over 5-7 different days. The results of the variation in the dose ratio at one depth to the other are as follows. For X-ray, the variation was as small as within the suggest tolerance (±2%) for every accelerator examined. For 5-9 MeV and 10-12 MeV electron, only a few of the linear accelerators (linacs), as well as the betatron and the microtron, satisfied the tolerance (±3%). Some machine varied as large as 18% on one measurement day. For higher energies (15-20 MeV), energy machine fell within the tolerance. In addition, the relationship between the deviation in electron dose (dose ratio) and that in position (depth) has been discussed in terms of tolerance from the results obtained with the Mevatron linac in Tokyo Medical College Hospital by repeatedly measuring electron PDD curves at every energy available. (author)

  7. Depth absorbed dose characteristics for several medical electron accelerators. According to the JASTRO QA program

    Energy Technology Data Exchange (ETDEWEB)

    Yokoyama, Koichi [Tokyo Medical Coll. Hospital (Japan); Kuwabara, Akio; Endo, Yuji; Sunaoka, Masayoshi; Tanaka, Keiichi; Shimada, Kazuyuki; Baba, Sadaaki; Ikeda, Ikuo; Sasaki, Toru

    1995-03-01

    Depth absorbed dose characteristics of both X-ray and electron radiation have been investigated on 10 accelerators according to the JASTRO QA program. Absorbed doses at the calibration point and at a depth specified in the program were measured over 5-7 different days. The results of the variation in the dose ratio at one depth to the other are as follows. For X-ray, the variation was as small as within the suggest tolerance ({+-}2%) for every accelerator examined. For 5-9 MeV and 10-12 MeV electron, only a few of the linear accelerators (linacs), as well as the betatron and the microtron, satisfied the tolerance ({+-}3%). Some machine varied as large as 18% on one measurement day. For higher energies (15-20 MeV), energy machine fell within the tolerance. In addition, the relationship between the deviation in electron dose (dose ratio) and that in position (depth) has been discussed in terms of tolerance from the results obtained with the Mevatron linac in Tokyo Medical College Hospital by repeatedly measuring electron PDD curves at every energy available. (author).

  8. Absorbed Dose Calculations Using Mesh-based Human Phantoms And Monte Carlo Methods

    Science.gov (United States)

    Kramer, Richard

    2011-08-01

    Health risks attributable to the exposure to ionizing radiation are considered to be a function of the absorbed or equivalent dose to radiosensitive organs and tissues. However, as human tissue cannot express itself in terms of equivalent dose, exposure models have to be used to determine the distribution of equivalent dose throughout the human body. An exposure model, be it physical or computational, consists of a representation of the human body, called phantom, plus a method for transporting ionizing radiation through the phantom and measuring or calculating the equivalent dose to organ and tissues of interest. The FASH2 (Female Adult meSH) and the MASH2 (Male Adult meSH) computational phantoms have been developed at the University of Pernambuco in Recife/Brazil based on polygon mesh surfaces using open source software tools and anatomical atlases. Representing standing adults, FASH2 and MASH2 have organ and tissue masses, body height and body mass adjusted to the anatomical data published by the International Commission on Radiological Protection for the reference male and female adult. For the purposes of absorbed dose calculations the phantoms have been coupled to the EGSnrc Monte Carlo code, which can transport photons, electrons and positrons through arbitrary media. This paper reviews the development of the FASH2 and the MASH2 phantoms and presents dosimetric applications for X-ray diagnosis and for prostate brachytherapy.

  9. Regression models in the determination of the absorbed dose with extrapolation chamber for ophthalmological applicators

    International Nuclear Information System (INIS)

    The absorbed dose for equivalent soft tissue is determined,it is imparted by ophthalmologic applicators, (90 Sr/90 Y, 1850 MBq) using an extrapolation chamber of variable electrodes; when estimating the slope of the extrapolation curve using a simple lineal regression model is observed that the dose values are underestimated from 17.7 percent up to a 20.4 percent in relation to the estimate of this dose by means of a regression model polynomial two grade, at the same time are observed an improvement in the standard error for the quadratic model until in 50%. Finally the global uncertainty of the dose is presented, taking into account the reproducibility of the experimental arrangement. As conclusion it can infers that in experimental arrangements where the source is to contact with the extrapolation chamber, it was recommended to substitute the lineal regression model by the quadratic regression model, in the determination of the slope of the extrapolation curve, for more exact and accurate measurements of the absorbed dose. (Author)

  10. Quantification of micronuclei in blood lymphocytes of patients exposed to gamma radiation for dose absorbed assessment

    International Nuclear Information System (INIS)

    Dose assessment in an important step to evaluate biological effects as a result of individual exposure to ionizing radiation. The use of cytogenetic dosimetry based on the quantification of micronuclei in lymphocytes is very important to complement physical dosimetry, since the measurement of absorbed dose cannot be always performed. In this research, the quantification of micronuclei was carried out in order to evaluate absorbed dose as a result of radiotherapy with 60Co, using peripheral blood samples from 5 patients with cervical uterine cancer. For this purpose, an aliquot of whole blood from the individual patients was added in culture medium RPMI 1640 supplemented with fetal calf serum and phytohaemagglutinin. The culture was incubated for 44 hours. Henceforth, cytochalasin B was added to block the dividing lymphocytes in cytokinesis. The culture was returned to the incubator for further of 28 hours. Thus, cells were harvested, processed and analyzed. Values obtained considering micronuclei frequency after pelvis irradiation with absorption of 0,08 Gy and 1,8 Gy were, respectively, 0,0021 and 0,052. These results are in agreement with some recent researches that provided some standard values related to micronuclei frequency induced by gamma radiation exposure in different exposed areas for the human body. The results presented in this report emphasizes biological dosimetry as an important tool for dose assessment of either total or partial-body exposure to ionizing radiation, mainly in retrospective dose investigation. (author)

  11. Absorbed dose/melting heat dependence studies for the PVDF homopolymer

    International Nuclear Information System (INIS)

    Differential Scanning Calorimetry (DSC) of gamma irradiated Poly (vinylidene Fluoride) [PVDF] homopolymer has been studied in connection with the use of material in industrial high gamma dose measurement. Interaction between gamma radiation and PVDF leads to the radio-induction of C=O and conjugated C=C bonds, as it can be inferred from previous infrared (FTIR) and ultraviolet-visible (UV-Vis) spectrometric data. These induced defects result in a decrease of the polymer crystallinity that can be followed with DSC scans, by measuring the latent heat during the melting transition (Hmelt). After a systematic investigation, we have found that Hmelt is unambiguously related to the delivered doses ranging from 100 to 2,000 kGy of gamma radiation. One the other hand, further fading investigation analysis has proved that the Hmelt x Dose relationship can be fitted by an exponential function that remains constant for several months. Both the very large range of dose measurement and also the possibility of evaluating high gamma doses until five months after irradiation make PVDF homopolymers very good candidates to be investigated as commercial high gamma dose dosimeters. The high gamma dose irradiation facilities in Brazil used to develop high dose dosimeters are all devoted to industrial and medical purposes. Therefore, in view of the uncertainties involved in the dose measurements related to the electronic equilibrium correction factors and backscattering in the isodose curves used at the irradiation setup, a validation process is required to correctly evaluate the delivered absorbed doses. The sample irradiations were performed with a Co-60 source, at 12kGy/h and 2,592 kGy/h, in the high gamma dose facilities at Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN, Belo Horizonte, Brazil. The comparison of the curve of the Hmelt vs Dose is presented in this paper. (author)

  12. Absorbed dose/melting heat dependence studies for the PVDF homopolymer

    Energy Technology Data Exchange (ETDEWEB)

    Batista, Adriana S.M.; Gual, Maritza R.; Pereira, Claubia, E-mail: adriananuclear@yahoo.com.br, E-mail: maritzargual@gmail.com, E-mail: claubia@nuclear.ufmg.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Faria, Luiz O., E-mail: farialo@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2013-07-01

    Differential Scanning Calorimetry (DSC) of gamma irradiated Poly (vinylidene Fluoride) [PVDF] homopolymer has been studied in connection with the use of material in industrial high gamma dose measurement. Interaction between gamma radiation and PVDF leads to the radio-induction of C=O and conjugated C=C bonds, as it can be inferred from previous infrared (FTIR) and ultraviolet-visible (UV-Vis) spectrometric data. These induced defects result in a decrease of the polymer crystallinity that can be followed with DSC scans, by measuring the latent heat during the melting transition (Hmelt). After a systematic investigation, we have found that Hmelt is unambiguously related to the delivered doses ranging from 100 to 2,000 kGy of gamma radiation. One the other hand, further fading investigation analysis has proved that the Hmelt x Dose relationship can be fitted by an exponential function that remains constant for several months. Both the very large range of dose measurement and also the possibility of evaluating high gamma doses until five months after irradiation make PVDF homopolymers very good candidates to be investigated as commercial high gamma dose dosimeters. The high gamma dose irradiation facilities in Brazil used to develop high dose dosimeters are all devoted to industrial and medical purposes. Therefore, in view of the uncertainties involved in the dose measurements related to the electronic equilibrium correction factors and backscattering in the isodose curves used at the irradiation setup, a validation process is required to correctly evaluate the delivered absorbed doses. The sample irradiations were performed with a Co-60 source, at 12kGy/h and 2,592 kGy/h, in the high gamma dose facilities at Centro de Desenvolvimento da Tecnologia Nuclear CDTN/CNEN, Belo Horizonte, Brazil. The comparison of the curve of the Hmelt vs Dose is presented in this paper. (author)

  13. Utilization of radiation protection gear for absorbed dose reduction: an integrative literature review

    International Nuclear Information System (INIS)

    Objective: The present study was aimed at evaluating the relation between the use of radiation protection gear and the decrease in absorbed dose of ionizing radiation, thereby reinforcing the efficacy of its use by both the patients and occupationally exposed personnel. Materials and Methods: The integrative literature review method was utilized to analyze 21 articles, 2 books, 1 thesis, 1 monograph, 1 computer program, 4 pieces of database research (Instituto Brasileiro de Geografia e Estatistica and Departamento de Informatica do Sistema Unico de Saude) and 2 sets of radiological protection guidelines. Results: Theoretically, a reduction of 86% to 99% in the absorbed dose is observed with the use of radiation protection gear. In practice, however, the reduction may achieve 88% in patients submitted to conventional radiology, and 95% in patients submitted to computed tomography. In occupationally exposed individuals, the reduction is around 90% during cardiac catheterization, and 75% during orthopedic surgery. Conclusion: According to findings of several previous pieces of research, the use of radiation protection gear is a low-cost and effective way to reduce absorbed dose both for patients and occupationally exposed individuals. Thus, its use is necessary for the implementation of effective radioprotection programs in radiodiagnosis centers. (author)

  14. Calculation of fluence and absorbed dose in head tissues due to different photon energies

    International Nuclear Information System (INIS)

    Calculations of fluence and absorbed dose in head tissues due to different photon energies were carried out using the MCNPX code, to simulate two models of a patient's head: one spherical and another more realistic ellipsoidal. Both head models had concentric shells to describe the scalp skin, the cranium and the brain. The tumor was located at the center of the head and it was a 1 cm-radius sphere. The MCNPX code was run for different energies. Results showed that the fluence decreases as the photons pass through the different head tissues. It can be observed that, although the fluence into the tumor is different for both head models, absorbed dose is the same. - Highlights: • A Monte Carlo algorithm to simulate the passage of photons through a homogeneous material was developed. • Two models of a patient's head, one spherical and another more realistic ellipsoidal model, were simulated using the Monte Carlo code. • The fluence into the tumor is different for both head models, but absorbed dose in the tumor is the same

  15. Utilization of radiation protection gear for absorbed dose reduction: an integrative literature review

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Flavio Augusto Penna; Flor, Rita de Cassia [Instituto Federal de Santa Catarina (IFSC), Florianopolis, SC (Brazil); Pereira, Aline Garcia, E-mail: aalinegp@gmail.co [Sinan Project - Sistema de Informacao de Agravos de Notificacao, Florianopolis, SC (Brazil)

    2011-03-15

    Objective: The present study was aimed at evaluating the relation between the use of radiation protection gear and the decrease in absorbed dose of ionizing radiation, thereby reinforcing the efficacy of its use by both the patients and occupationally exposed personnel. Materials and Methods: The integrative literature review method was utilized to analyze 21 articles, 2 books, 1 thesis, 1 monograph, 1 computer program, 4 pieces of database research (Instituto Brasileiro de Geografia e Estatistica and Departamento de Informatica do Sistema Unico de Saude) and 2 sets of radiological protection guidelines. Results: Theoretically, a reduction of 86% to 99% in the absorbed dose is observed with the use of radiation protection gear. In practice, however, the reduction may achieve 88% in patients submitted to conventional radiology, and 95% in patients submitted to computed tomography. In occupationally exposed individuals, the reduction is around 90% during cardiac catheterization, and 75% during orthopedic surgery. Conclusion: According to findings of several previous pieces of research, the use of radiation protection gear is a low-cost and effective way to reduce absorbed dose both for patients and occupationally exposed individuals. Thus, its use is necessary for the implementation of effective radioprotection programs in radiodiagnosis centers. (author)

  16. Measurement of absorbed dose to water for medium energy x-rays

    International Nuclear Information System (INIS)

    This paper evaluates the characteristics of ionization chambers for the measurement of absorbed dose to water for medium energy x-rays. The values of the chamber correction factor, kch, used in the IPEMB 1996 Code of Practice for the UK secondary standard (NE2561/NE2611) ionization chamber are derived. The comparison of the chamber responses in-air revealed that of the chambers tested, only the NE2561, NE2571 and NE2505 exhibit a flat (within 5%) energy response in air. Under no circumstances should the NACP, Sanders electron chamber or any chamber that has a wall made of high atomic number material be used for medium energy x-ray dosimetry. The measurements in water reveal that a chamber that has a substantial housing such as the PTW Grenz chamber, should not be used to measure absorbed dose to water in this energy range. The value of the perturbation correction, pu for a NE2561 chamber was determined by measuring the absorbed dose to water and comparing it with that for a NE2571 chamber, for which pu data has been published. The chamber correction factor varies from (1.023 ± 0.03) to (1.018 ± 0.001) for x-ray beams with HVL between 0.15 and 4 mm Cu. The values agree with that for a NE2571 chamber within the experimental uncertainty. (author)

  17. Calculation of absorbed doses in diagnostic and therapeutic use of monoclonal antibodies against malignant melanomas

    International Nuclear Information System (INIS)

    The aim of this investigation was to derive the biokinetics for radiolabelled 96.5 antibodies in an animal model and estimate absorbed doses. As an experimental model, nude athymic rats transplanted with human melanoma were used. Whole antibody 96.5 was labelled with 125I and injected i.v. into the rats (n=52). Experiments were done for three different tumors, two patient tumors, called UM and KS, and one melanoma cell line, 1477. The tumors were inocculated on the thighs intramuscularly and subcutaneously and their final weight was between 0.02 and 11.5g. The uptake in tumor tissue always exeeded other normal tissues. The normal tissue dominating is the lungs with uptake values somewhat smaller than tumors. The ratio between the uptake values for tumors and muscle is 5.5 for UM, 4.0 for KS and 3.9 for 1477 tumor. The animal data for percentage uptake and halflife were used directly in the MIRD formalism to calculate the mean absorbed dose from 131I-96.5 antibodies. The absorbed dose to the tumor will be in the order of 0.1 Gy/MBq. This value, however, is strongly dependant on the tumor weight. The biokinetics for the different tumors also differed. (Author)

  18. Accuracy improvement on therapy level dosimeter calibration at Enea (Italy) by the National Absorbed-Dose-to-Water Standard

    International Nuclear Information System (INIS)

    A standard of absorbed dose to water for Co-60 gamma-ray was established at ENEA (Italy) several years ago. This standard is based on a graphite calorimeter and a thick walled ionisation chamber used for absorbed dose conversion from graphite to water. To this end the ionisation chamber is irradiated at a point in graphite (where the absorbed dose to graphite is known) and then at a corresponding point in water where the energy spectrum of the radiation is the same as that at the reference point in graphite. The accuracy of this procedure was recently improved either by a more rigorous scaling of the water phantom dimensions or by a more accurate determination of the parameters involved in the conversion procedure. Moreover a more accurate gap correction for the graphite calorimeter was determined, accounting for field size dependence. The uncertainty on the absorbed dose to water is at present of about 0.45% (1?). A comparison at BIPM of both the standards of absorbed dose to graphite and to water, respectively, was carried out and in both cases the deviations between the ENEA and the BIPM resulted about 0.3%. A comparison between the ionisation chamber calibration procedures based on the standards of absorbed dose to water and of air kerma was also made confirming the consistency of the two methods. Chamber calibration in terms of absorbed dose to water will be included as a recommended procedure in the AIFB dosimetry protocol in Italyol in Italy

  19. Assessment of indoor absorbed gamma dose rate from natural radionuclides in concrete by the method of build-up factors.

    Science.gov (United States)

    Mani?, Vesna; Nikezic, Dragoslav; Krstic, Dragana; Mani?, Goran

    2014-12-01

    The specific absorbed gamma dose rates, originating from natural radionuclides in concrete, were calculated at different positions of a detection point inside the standard room, as well as inside an example room. The specific absorbed dose rates corresponding to a wall with arbitrary dimensions and thickness were also evaluated, and appropriate fitting functions were developed, enabling dose rate calculation for most realistic rooms. In order to make calculation simpler, the expressions fitting the exposure build-up factors for whole (238)U and (232)Th radionuclide series and (40)K were derived in this work, as well as the specific absorbed dose rates from a point source in concrete. Calculated values of the specific absorbed dose rates at the centre point of the standard room for (238)U, (232)Th and (40)K are in the ranges of previously obtained data. PMID:24421381

  20. Assessment of indoor absorbed gamma dose rate from natural radionuclides in concrete by the method of build-up factors

    International Nuclear Information System (INIS)

    The specific absorbed gamma dose rates, originating from natural radionuclides in concrete, were calculated at different positions of a detection point inside the standard room, as well as inside an example room. The specific absorbed dose rates corresponding to a wall with arbitrary dimensions and thickness were also evaluated, and appropriate fitting functions were developed, enabling dose rate calculation for most realistic rooms. In order to make calculation simpler, the expressions fitting the exposure build-up factors for whole 238U and 232Th radionuclide series and 40K were derived in this work, as well as the specific absorbed dose rates from a point source in concrete. Calculated values of the specific absorbed dose rates at the centre point of the standard room for 238U, 232Th and 40K are in the ranges of previously obtained data. (authors)

  1. Graphite calorimeter, the primary standard of absorbed dose at BNM-LNHB

    International Nuclear Information System (INIS)

    The graphite calorimeter is the standard for absorbed dose to water at BNM-LNHB. The transfer from absorbed dose to graphite to absorbed dose to water is then performed by means of chemical dosimeters and ionisation chamber measurements. Therefore the quality of graphite calorimeter measurements is essential. The present graphite calorimeter is described. The characteristics of this calorimeter are pointed out. Special attention is given to the thermal feedback of the core, which is the main difference with the Domen-type calorimeter. The repeatability and reproducibility of the mean absorbed dose in the calorimeter core are presented in detail. As an example, individual measurements in the 20 MV photon beam from our Saturne 43 linac are given. The y-axis quantity is the mean absorbed dose in the core divided by the reference ionisation chamber charge. Both are normalised to the monitor ionisation chamber charge. The standard deviation (of the distribution itself) is 0.12 % for the first set of measurements performed in 1999. In 2002, for each different series, the standard deviation is 0.03%. The improvement on the 2002 standard deviation is mainly due to the change of the ionisation chamber used for the beam monitoring of the linac. Some benefit also comes from changes on the thermal control and measuring systems (nanovoltmeters, Wheatstone bridges, power supplies, determination of the measuring bridge sensitivity (V/?.) ). The maximum difference between the means of the three series is 0.08%. This difference is due to the variation of not only the calorimetric measurements but also of the reference ionisation chamber response, of the position of the assembly and of the monitoring of the beam. The stability of the linac (electron energy, photon beam shape) has to be very good too in order to obtain this global performance. The correction factors necessary to determine the absorbed dose to graphite at the reference point in an homogeneous phantom from the measurement of the mean absorbed dose to the calorimeter core are examined including gradient correction factor. The uncertainties are analysed. The main uncertainty comes from the vacuum gaps correction factor determination. They are measured and calculated by Monte-Carlo code for cobalt 60, 6 MV, 12 MV and 20 MV photon beams. The influence of the irradiation on the sensitivity of the thermistor has been checked. A specific program was developed in order to perform the electrical calibration and the irradiation together. Recent measurements carried out in the 20 MV photon beam prove that there is no significant difference between the simultaneous measurement (irradiation + electrical power dissipation) and the sum of these two quantities measured separately. This confirms previous measurements in cobalt 60 beams. It is not possible to do this control with the water calorimeter because no electrical calibration is feasible. By using the same type of thermistor this result might be extrapolated to water calorimeters

  2. Determination of Absorbed and Effective Dose from Natural Background Radiation around a Nuclear Research Facility

    Directory of Open Access Journals (Sweden)

    M. A. Musa

    2011-01-01

    Full Text Available Problem statement: This study presents result of outdoor absorbed dose rate and estimated effective dose from the naturally occurring radionuclides 232Th and 238U series 40K, around a Nuclear Research Reactor at the Centre for Energy Research and Training (CERT, Zaria, Nigeria. Approach: A high-resolution in situ ?-ray spectrometry was used to carry out the study. CERT houses a 30Kw Research Reactor and other neutron and gamma sources for Research and Training. Results: The values of absorbed dose rate in air for 232Th, 238U and 40K range from 8.2 ± 2.5-24.5 ± 3.6 nGy h?1, 1.9 ± 1.2-4.6 ± 2.5 nGy h?1 and 12.2 ± 5-38 ± 6.7n Gy h?1 respectively . The estimated total annual effective dose outdoor for the sites range from 27.3-79.9 ?Sv y?1.Conclusions: This showed that radiation exposure level for the public is lower than the recommended value of 1 mSv y?1.Hence, the extensive usage of radioactive materials within and around CERT does not appear to have any impact on the radiation burden of the environment.

  3. Three-dimensional absorbed dose determinations by N.M.R. analysis of phantom-dosemeters

    International Nuclear Information System (INIS)

    Magnetic resonance imaging of a tissue-equivalent phantom is a promising technique for three-dimensional determination of absorbed dose from ionizing radiation. A reliable method of determining the spatial distribution of absorbed dose is indispensable for the planning of treatment in the presently developed radiotherapy techniques aimed at obtaining high energy selectively delivered to cancerous tissues, with low dose delivered to the surrounding healthy tissue. Aqueous gels infused with the Fricke dosemeter (i.e. with a ferrous sulphate solution), as proposed in 1984 by Gore et al., have shown interesting characteristics and, in spite of some drawbacks that cause a few limitations to their utilisation, they have shown the feasibility of three-dimensional dose determinations by nuclear magnetic resonance (NMR) imaging. Fricke-infused agarose gels with various compositions have been analysed, considering the requirements of the new radiotherapy techniques, in particular Boron Neutron Capture Therapy (B.N.C.T.) and proton therapy. Special attention was paid to obtain good tissue equivalence for every radiation type of interest. In particular, the tissue equivalence for thermal neutrons, which is a not simple problem, has also been satisfactorily attained. The responses of gel-dosemeters having the various chosen compositions have been analysed, by mean of NMR instrumentation. Spectrophotometric measurements have also been performed, to verify the consistence of the resrmed, to verify the consistence of the results. (author)

  4. Annual absorbed dose rate at the surface of 38 hot and mineral springs in Iran

    International Nuclear Information System (INIS)

    Full text of publication follows: Measurement of background radiation is very important from different points of view especially to human health. In some cases exposure rate near hot and mineral springs are higher than those of normal areas. The high background radiation of hot and mineral springs is primarily due to the presence of very high amounts of Ra 226 and its decay products. In this research, environmental gamma radiation of hot and mineral springs in Khorasan, Mazandaran and Sareeyn town in Ardabil province have been measured. Equipment used in this work included: a survey meter (R.D.S. -110), a tripod and an aluminium frame to hold the survey meter horizontally.R.D.S. -110 is a microprocessor controlled detector. This survey meter has been designed for monitoring X and 'rays and' radiation. Measurements were carried out at one meter above water level in the vicinity of hot and mineral springs. Dose rates were recorded for one hour. The average of all recorded dose rates over one hour period was taken as the exposure rate for each station. The results indicate that in Khorasan province the highest and lowest annual absorbed dose rates were equal to 10.80 mSv/y at Shanigarmab and 0.52 mSv/y at Nasradin source respectively. In Mazandaran province maximum and minimum exposure rates equal to 54.4 and 0.53 mSv/y were obtained at the surface of Talleshmahalleh and Ghormerz sources. Exposure rates at the vicinity of Sarein sources were not very different and rangedsources were not very different and ranged from 1.39 to 1.59 mSv/y. The results indicate that in Khorasan province Shahingarmab hot spring has the highest annual absorbed dose rate (10.80 mSv/y) and Nasraddin in Sarbisheh has the lowest level of radiation (0.62 mSv/y). In Mazandaran province Taleshmahalleh hot mineral spring has the highest annual absorbed dose rate (54.41 mSv/y) and Ghormerz mineral spring has the lowest radiation level (0.53 mSv/y). Also in Sareeyn (in Ardabil province) Abechashm source has the highest annual absorbed dose rate (1.59 mSv/y) and Jeneral spring the lowest (1.39 mSv/y). (authors)

  5. Error in assessing the absorbed dose from the EPR signal from dental enamel

    International Nuclear Information System (INIS)

    Dose measurements from EPR signals from dental enamel were analyzed in a random sampling of 100 teeth extracted in liquidators of the Chernobyl accident aftermath and the EPR spectra of dental enamel of 80 intact teeth from children studied. The mean square deviation of enamel sensitivity to ionizing radiation in some teeth is approximately 0.3 of the mean sensitivity value. The variability of the nature EPR spectrum of dental enamel limits in principle the lower threshold of EPR-measured 60 mGy doses. When assessing the individual absorbed doses from the EPR signal from dental enamel without additional exposure it is necessary to bear in mind the extra error of approximately 6-% at a confidence probability P=0.95 caused by the variability of enamel sensitivity to radiation in some teeth. This additional error may be ruled out by graduated additional exposure of the examined enamel samples

  6. Assessment of absorbed dose to the ovaries of patients undergoing pelvic CT examination

    International Nuclear Information System (INIS)

    Full text of publication follows: Introduction: Although Computed Tomography (CT) procedures constitute about 5% of the total diagnostic radiology procedures but are responsible for about 40% of the total ionizing radiation dose to the general population. As the dose is high especially in the CT of female pelvis, genetic radiation risk is also considerable. Materials and Methods: Radiation doses to the ovaries of the patients undergoing CT examination of the pelvis were measured from 9 different CT scanners available in Isfahan city. For each CT scanner 20 patients were selected. Measurement of organ dose was performed using TLD method. Results and Discussions: Mean and S.D. of absorbed dose to the ovaries from Shimadzo 2500 were 56.6 2.8; from GE Max 640 were 36.8 1.7; from GE Sytec 3000 were 36.6 1.8; from GE Sytec 4000 were 36.6 2.6; from Piker were 38.4 2.1; from Shimadzo 4500 were 36.4 1.2 and from Shimadzo 7800TE 28.2 1.5. Associated risks due to the measured dose are discussed. (author)

  7. Standard Guide for Selection and Use of Mathematical Methods for Calculating Absorbed Dose in Radiation Processing Applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This guide describes different mathematical methods that may be used to calculate absorbed dose and criteria for their selection. Absorbed-dose calculations can determine the effectiveness of the radiation process, estimate the absorbed-dose distribution in product, or supplement or complement, or both, the measurement of absorbed dose. 1.2 Radiation processing is an evolving field and annotated examples are provided in Annex A6 to illustrate the applications where mathematical methods have been successfully applied. While not limited by the applications cited in these examples, applications specific to neutron transport, radiation therapy and shielding design are not addressed in this document. 1.3 This guide covers the calculation of radiation transport of electrons and photons with energies up to 25 MeV. 1.4 The mathematical methods described include Monte Carlo, point kernel, discrete ordinate, semi-empirical and empirical methods. 1.5 General purpose software packages are available for the calcul...

  8. Data for absorbed dose calculations for external sources and for emitters within the body

    International Nuclear Information System (INIS)

    Tables give data for the calculation of absorbed doses from radioactivity sources accumulated in individual body organs. The tables are arranged in such manner that the gamma energy (J) absorbed in 1 kg of target organ (19 organs and total body) are given for 18 source organs (16 different organs, total doby and surrounding air) resulting from 1 decay event, this for more than 250 radioisotopes evenly distributed in the source organ (1 J/kg=100 rad). Also given are the energies of alpha and beta radiations related to one decay. In tables having the surrounding air as the source it is assumed that the intensity of the external source is 1 decay per 1 m3 of surrounding air which is constant in the entire half-space. The tables are only elaborated for radioisotopes with a half-life of more than 1 min. (B.S.)

  9. Method for determination of the mean fraction of glandular tissue in individual female breasts using mammography

    International Nuclear Information System (INIS)

    The nationwide breast cancer screening programme using mammography has been in full operation in the Netherlands since 1997. Quality control of the screening programme has been assigned to the National Expert and Training Centre for Breast Cancer Screening. Limits are set to the mean glandular dose and the centre monitors these for all facilities engaged in the screening programme. This procedure is restricted to the determination of the entrance dose on a 5 cm thick polymethylmethacrylate (PMMA) phantom. The mean glandular dose for a compressed breast is estimated from these data. Individual breasts may deviate largely from this 5 cm PMMA breast model. Not only may the compressed breast size vary from 2 to 10 cm, but breast composition varies also. The mean glandular dose is dependent on the fraction of glandular tissue (glandularity) of the breast. To estimate the risk related to individual mammograms requires the development of a method for determination of the glandularity of individual breasts. A method has been developed to derive the glandularity using the attenuation of mammography x-rays in the breast. The method was applied to a series of mammograms at a screening unit. The results, i.e., a glandularity of 93% within the range of 0 to 1, were comparable with data in the literature. The glandularity as a function of compressed breast thickness is similar to results from other investigators using differing methods

  10. Method for determination of the mean fraction of glandular tissue in individual female breasts using mammography

    Science.gov (United States)

    Jansen, J. T. M.; Veldkamp, W. J. H.; Thijssen, M. A. O.; van Woudenberg, S.; Zoetelief, J.

    2005-12-01

    The nationwide breast cancer screening programme using mammography has been in full operation in the Netherlands since 1997. Quality control of the screening programme has been assigned to the National Expert and Training Centre for Breast Cancer Screening. Limits are set to the mean glandular dose and the centre monitors these for all facilities engaged in the screening programme. This procedure is restricted to the determination of the entrance dose on a 5 cm thick polymethylmethacrylate (PMMA) phantom. The mean glandular dose for a compressed breast is estimated from these data. Individual breasts may deviate largely from this 5 cm PMMA breast model. Not only may the compressed breast size vary from 2 to 10 cm, but breast composition varies also. The mean glandular dose is dependent on the fraction of glandular tissue (glandularity) of the breast. To estimate the risk related to individual mammograms requires the development of a method for determination of the glandularity of individual breasts. A method has been developed to derive the glandularity using the attenuation of mammography x-rays in the breast. The method was applied to a series of mammograms at a screening unit. The results, i.e., a glandularity of 93% within the range of 0 to 1, were comparable with data in the literature. The glandularity as a function of compressed breast thickness is similar to results from other investigators using differing methods.

  11. Radioiodine Therapy of Hyperthyroidism. Simplified patient-specific absorbed dose planning

    International Nuclear Information System (INIS)

    Radioiodine therapy of hyperthyroidism is the most frequently performed radiopharmaceutical therapy. To calculate the activity of 131I to be administered for giving a certain absorbed dose to the thyroid, the mass of the thyroid and the individual biokinetic data, normally in the form of uptake and biologic half-time, have to be determined. The biologic half-time is estimated from several uptake measurements and the first one is usually made 24 hours after the intake of the test activity. However, many hospitals consider it time-consuming since at least three visits of the patient to the hospital are required (administration of test activity, first uptake measurement, second uptake measurement plus treatment). Instead, many hospitals use a fixed effective half-time or even a fixed administered activity, only requiring two visits. However, none of these methods considers the absorbed dose to the thyroid of the individual patient. In this work a simplified patient-specific method for treating hyperthyroidism is proposed, based on one single uptake measurement, thus requiring only two visits to the hospital. The calculation is as accurate as using the individual biokinetic data. The simplified method is as patient-convenient and time effective as using a fixed effective half-time or a fixed administered activity. The simplified method is based upon a linear relation between the late uptake measurement 4-7 days after intake of the test activity and the product take of the test activity and the product of the extrapolated initial uptake and the effective half-time. Treatments not considering individual biokinetics in the thyroid result in a distribution of administered absorbed dose to the thyroid, with a range of -50 % to +160 % compared to a protocol calculating the absorbed dose to the thyroid of the individual patient. Treatments with a fixed administered activity of 370 MBq will in general administer 250 % higher activity to the patient, with a range of -30 % to +770 %. The absorbed dose to other organs than the thyroid is also influenced. These doses should also be considered in estimating the risk of late radiation effects in the patients. This is becoming more important as an increasing number of younger patients are treated with radioiodine. If all Swedish hospitals considered the individual biokinetic data the total administrated activity of 131I would decrease by 10 % (100 GBq) corresponding to a yearly collective effective dose of 17 manSv, thyroid excluded. Seventeen different methods to determine the administered activity of 131I are in use in 23 Swedish hospitals. Only nine hospitals calculate the administered activity of 131I using individual biokinetic data. More effort should be done to consider the individual biokinetic data when calculating the administered activity of 131I and thus decrease unnecessary radiation dose to individual patients, their families and the public

  12. Studying the absorbed dose in two-layer flat samples irradiated by fast neutrons

    International Nuclear Information System (INIS)

    Fast neutron passage through two-layer fine structures is considered. Absorbed doses in quartz glass layer with polymeric coating of different thickness are calculated. The computerized calculations are carried out by means of the program permitting to apply the Monte-Carlo method for simulation of 0.1-14 MeV neutron irradiation of fine samples comprising plane layers of different materials. Accountancy of elastic ad inelastic neutron scattering as well as reactions with charged paticle escape is presupposed in the program. The calculations are performed for cases of normal drop of homogeneous neutron beams on a flat compostion of quartz glass of 2.21 g/cm3 density with polymeric caprone coating of 1.14 g/cm3 density or dacron coating of 1.38 g/cm3 density. Thickness of the glass layer is 1 mm. Thickness of the coating varied in the 0-2.5 mm range. Based on the analysis of the data obtained it is concluded that the absorbed dose in the surface layer increases several times as compared with the dose calculated for pure material under irradiation of materials with polymeric coatings by neutrons of the reactor spectrum (mean energy is 2 MeV)

  13. Performance evaluation of graphite pancake ionization chamber by comparing the absorbed dose to water calibration

    International Nuclear Information System (INIS)

    This paper describes modifications to an original design, correction factors and uncertainty evaluations for a graphite pancake ionization chamber constructed at the Institute of Nuclear Energy Research (INER, Taiwan). A bilateral comparison of the absorbed dose to water standards for 60Co using transfer chambers was performed to verify the graphite chamber experimental accuracy and measurement consistency. The comparison results showed a satisfactory agreement in the measurements within the combined standard uncertainties (k=1). This paper also compares the absorbed dose to water calibration in medical accelerator photon beams traceable to INER standards following the recommendations given in the AAPM TG-21 and TG-51 dosimetry protocols. For all types of linear accelerators and cylindrical chambers at 13 participating hospitals in Taiwan, the TG-51/TG-21 dose ratios were the same within +/-1.5%, less than the combined uncertainty, irrespective of the chamber make and model for each photon included here. A quality assurance guide for institutions switching from the TG-21 to TG-51 protocol was suggested based on the comparison results for the two dosimetry protocols

  14. Determination of calibration factors in terms of air kerma and absorbed dose to water in the 60Co ? rays

    International Nuclear Information System (INIS)

    The method of calibration of an instrument, as performed at the BIPM in the 60Co field in terms of air kerma or absorbed dose to water, is described in detail. The influence of various parameters which can affect the calibration factor is analyzed. The uncertainty is of order 0.3% and 0.5% for calibration factors in terms of air kerma and of absorbed dose to water, respectively. (author). 14 refs, 10 figs, 3 tabs

  15. Absorbed and effective dose from spiral and computed tomography for the dental implant planning

    International Nuclear Information System (INIS)

    To evaluate the absorbed and effective doses of spiral and computed tomography for the dental implant planning. For radiographic projection. TLD chips were placed in 22 sites of humanoid phantom to record the exposure to skin and the mean absorbed dose to bone marrow, thyroid, pituitary, parotid and submandibular glands and nesophages. Effective dose was calculated, using the method suggested by Frederiksen at al.. Patient situations of a single tooth gap in upper and lower midline region, edentulous maxilla and mandible were simulated for spiral tomography. 35 axial slices (maxilla) and 40 axial slices (mandible) with low and standard dose setting were used for computed tomography. All the radiographic procedures were repeated three times. The mean effective dose in case of maxilla was 0.865 mSv, 0.452 mSv, 0.136 mSv and 0.025 mSv, in spiral tomography of complete edentulous maxilla, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). That in case of mandible was 0.614 mSv, 0.448 mSv, 0.137 mSv and 0.036 mSv, in spiral tomography of complete edentulous mandible, computed tomography with standard mAs, computed tomography with low mAs and spiral tomography of a single tooth gap (p<0.05). Based on these results, it can be concluded that low mAs computed tomography is recommended instead of spiral tomography for the complete edentulous maxilla and mandible dental implant treatment planningdental implant treatment planning

  16. Radiation absorbed dose estimate for Rb-82 using in vivo measurements in man

    International Nuclear Information System (INIS)

    Radiation absorbed doses from intravenous Rb-82 (t 1/2 = 75 sec) were calculated by conjugate counting in 2 healthy adult men aged 27 and 23. Following an i.v. injection of a carefully calibrated amount of Rb-82, an organ of interest was imaged with a gamma camera equipped with a rotating tungsten collimator and data were collected in 10 second frames. Counts in the region of interest were corrected for adjacent background. Imaging was repeated from the opposite side of the body after a second injection. A calibrated reference source of Ge-68 placed on the body over the organ was similarly imaged in the absence of the rubidium activity. The integrated time activity curve in uCi-hours was obtained by comparing the observed kidney net conjugate counts with the reference source conjugate counts which represented a known number of uCi-hours. The organ self doses to the kidneys, liver, lungs, heart, and testes were determined by this technique which eliminated the effects of attenuation. Total absorbed doses to organs from all sources were calculated using the MIRD formulation and the averages of the 2 determinations (mrads/mCi) are as follows: heart (walls) 6.6; kidneys 31.3; liver 4.4; lungs 7.3; testes (1 subject only) 2.4; red marrow 1.7; and whole body 1.9. The highest dose is to the kidneys, but in an older subject (68 yr old man) the measured self dose to the left kidney was 16 mrads/mCi. These data are consistent with the decline in renal blood flow which occurs with increasing age and decreases renal exposure in older patients at increased risk of acute coronary disease who undergo myocardial perfusion imaging with Rb-82

  17. Estimation of Absorbed Dose of Salivary Glands in Radioiodine Therapy and Its Reduction Using Pilocarpine

    Directory of Open Access Journals (Sweden)

    Daryoush Shahbazi-Gahrouei

    2007-09-01

    Full Text Available Introduction:  The use of radioactive iodine (131I has become an important adjunct to the treatment of thyroid cancer and hyperthyroidism. Salivary gland has the ability to concentrate radioactive iodine under normal circumstances. Salivary gland dysfunction and dry mouth are the common side effects of high-dose radioiodine therapy. The purpose of this study was to determine the absorbed dose of salivary glands. Methods: Twenty patients who were divided into two groups of 10 were studied (A group without pilocarpine and the B group received pilocarpine during treatment. The absorbed dose of parotid glands and the submandibular glands of patients was measured using thermoluminescent dosimeter (TLD at three different times (24 hours, 8 days and 3 months after treatment. The attenuation coefficient of patients and the effects of pilocarpine were also determined. Results: In group A total attenuation coefficient was 0.335, 0.323, and 0.357 for parotid glands and the right and left submandibular glands, respectively. In group B total attenuation coefficient was 0.462, 0.482, and 0.514 for parotid glands and the right and left submandibular glands, respectively. The results also showed the dose decreases to 1 cGy after 3 and 2 half life for A and B group, respectively. Conclusion: The findings showed that the dose decreases to 1 cGy after 3 half life of Iodine therapy. The exponential coefficient attenuation of salivary glands varied 3% to 4%.  Pilocarpine appears to be effective in increasing excretion of radioactive iodine and enhancing coefficient attenuation (up to 1.5 to 2 times.

  18. Modeling the absorbed dose to the common carotid arteries following radioiodine treatment of benign thyroid disease

    International Nuclear Information System (INIS)

    External fractionated radiotherapy of cancer increases the risk of cardio- and cerebrovascular events, but less attention has been paid to the potential side effects on the arteries following internal radiotherapy with radioactive iodine (RAI), i.e. 131-iodine. About 279 per million citizens in the western countries are treated each year with RAI for benign thyroid disorders (about 140,000 a year in the EU), stressing that it is of clinical importance to be aware of even rare radiation-induced side effects. In order to induce or accelerate atherosclerosis, the dose to the carotid arteries has to exceed 2 Gy which is the known lower limit of ionizing radiation to affect the endothelial cells and thereby to induce atherosclerosis. To estimate the radiation dose to the carotid arteries following RAI therapy of benign thyroid disorders. Assuming that the lobes of the thyroid gland are ellipsoid, that the carotid artery runs through a part of the lobes, that there is a homogeneous distribution of RAI in the lobes, and that the 24 h RAI uptake in the thyroid is 35% of the 131I orally administrated, we used integrated modules for bioassay analysis and Monte Carlo simulations to calculate the dose in Gy/GBq of administrated RAI. The average radiation dose along the arteries is 4-55 Gy/GBq of the 131I orally administrated with a maximum dose of approximately 25-85 Gy/GBq. The maximum absorbed dose rate to the artery is 4.2 Gy/day per GBq 131I orally administrated. The calculated radiation dose to the carotid arteries after RAI therapy of benign thyroid disorder clearly exceeds the 2 Gy known to affect the endothelial cells and properly induce atherosclerosis. This simulation indicates a relation between the deposited dose in the arteries following RAI treatment and an increased risk of atherosclerosis and subsequent cerebrovascular events such as stroke. (author)

  19. [National primary standard of absorbed dose rate to water using a graphite calorimeter].

    Science.gov (United States)

    Morishita, Yuichiro

    2013-01-01

    The calibration service in terms of absorbed dose to water started from 2011 after establishment of the national primary standard using a graphite calorimeter at the national metrology institute of Japan (NMIJ) and JCSS accreditation of the association for nuclear technology in medicine (ANTM). Accordingly, a new dosimetry protocol was introduced as JSMP12, in which details of the national standard were also described. This report presents a short review of the standard, a key comparison result, and a comparison result of calibration coefficients by JSMP01 and JSMP12. PMID:24893493

  20. The national primary standard of absorbed dose rate to water using a graphite calorimeter

    International Nuclear Information System (INIS)

    The calibration service in terms of absorbed dose to water started from 2011 after establishment of the national primary standard using a graphite calorimeter at the national metrology institute of Japan (NMIJ) and JCSS accreditation of the association for nuclear technology in medicine (ANTM). Accordingly, a new dosimetry protocol was introduced as JSMP12, in which details of the national standard were also described. This report presents a short review of the standard, a key comparison result, and a comparison result of calibration coefficients by JSMP01 and JSMP12. (author)

  1. The 1998 calibration of Australian secondary standards of exposure and absorbed dose at 60Co

    International Nuclear Information System (INIS)

    New calibration factors are reported for several of the ionization chambers maintained at the Australian Radiation Laboratory (ARL) and at the Australian Nuclear Science and Technology Organisation (ANSTO) as Australian secondary standards of exposure/air kerma and absorbed dose at 60Co. These calibration factors supplement or replace the calibration factors given in earlier reports. Updated 90Sr reference source data are given for the ARL chambers, and for two of the ANSTO chambers. These results confirm the stability of the secondary standards. A re-calibration of the ANSTO reference electrometer is reported. This was carried out using an improved method, which is fully described

  2. Morphometric investigations to determine absorbed doses in the lungs from aspirated radionuclides

    International Nuclear Information System (INIS)

    Macro- and microtopography of the distribution of aspirated colloidal 144CeF3 in autographs of rabbit lung total sections were examined with the help of a monitoring-measuring device Videoplan and microcomputer. Quantitative assessment of photoemulsion blackening areas at the site of radionuclide concentration has confirmed that aspirated radionuclides are distributed in the lungs according to the same laws as nonradioactive aerosols: the relation of total microvolumes of actually irradiated pulmonary tissue to the entire lung volume long after radionuclide entry is shown; a possibility to use these data for determination of an actually absorbed dose in microvolumes of pulmonary tissue during aspiration of radionuclides is considered

  3. The 1998 calibration of Australian secondary standards of exposure and absorbed dose at {sup 60}Co

    Energy Technology Data Exchange (ETDEWEB)

    Huntley, R.B. [Australian Radiation Laboratory, Yallambie, VIC (Australia); Van der Gaast, H. [Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW (Australia)

    1998-10-01

    New calibration factors are reported for several of the ionization chambers maintained at the Australian Radiation Laboratory (ARL) and at the Australian Nuclear Science and Technology Organisation (ANSTO) as Australian secondary standards of exposure/air kerma and absorbed dose at {sup 60}Co. These calibration factors supplement or replace the calibration factors given in earlier reports. Updated {sup 90}Sr reference source data are given for the ARL chambers, and for two of the ANSTO chambers. These results confirm the stability of the secondary standards. A re-calibration of the ANSTO reference electrometer is reported. This was carried out using an improved method, which is fully described

  4. Intercomparison of absorbed dose to water calibration factors under WG5 of APMP programme

    International Nuclear Information System (INIS)

    In 1999, Asia Pacific Metrology Programme Technical Committee on Ionizing Radiation (TCRI), initiated regional key comparisons among its member countries. Under this programme, BARC was chosen as the organizer for Working Group 5 (WG 5) for key comparison of absorbed dose in water in 60Co radiation (at a depth of 5 g cm-2). Five institutions namely, ARPANSA (Australia), NSCL (Syria), CSIR (South Africa), INER (Taiwan) and SIRIM (Malaysia) took part in the intercomparisons. This paper brings the materials and methods used and the results of the intercomparisons

  5. Analysis of absorbed dose to tooth enamel against external photon exposure

    International Nuclear Information System (INIS)

    Absorbed dose to tooth enamel was examined against external photon exposure by measurements with thermoluminescence dosemeters (TLDs) and Monte Carlo calculations. TLDs were placed in a realistic physical phantom to measure dose to the teeth region in a head. A voxel-type phantom was constructed from computed tomography (CT) images of the physical phantom. Monte Carlo calculations with this voxel-type phantom were performed to analyse the results of the experiments. The data obtained were compared to the enamel doses, which were calculated with a modified MIRD-type phantom and already given in a previous paper. It was confirmed that the data derived with the MIRD-type phantom are applicable for retrospective individual dose assessments by electron spin resonance (ESR) dosimetry using teeth for the photon energy region above 300 keV. The analysis, however, indicated that the configuration of the head can affect the enamel dose relative to external exposure to photons with energy below 100 keV. (author)

  6. Estimation of the absorbed dose in radiation-processed food. 4. EPR measurements on eggshell

    International Nuclear Information System (INIS)

    Fresh whole eggs were treated with ionizing radiation for Salmonellae control testing. The eggshell was then removed and examined by electron paramagnetic resonance (EPR) spectroscopy to determine if EPR could be used to (1) distinguish irradiated from unirradiated eggs and (2) assess the absorbed dose. No EPR signals were detected in unirradiated eggs, while strong signals were measurable for more than 200 days after irradiation. Although a number of OPR signals were measured,the most intense resonance (g = 2.0019) was used for dosimetry throughout the study. This signal was observed to increase linearly with dose (up to approximately 6 kGy), which decayed approximately 20 % within the first 5 days after irradiation and remained relatively constant thereafter. The standard added-dose method was used to assess, retrospectively, the dose to eggs processed at 0.2, 0.7, and 1.4 kGy. Relatively good results were obtained when measurement was made on the day the shell was reradiated; with this procedure estimates were better for shell processed at the lower doses

  7. Spatial distribution analysis of absorbed dose in ocular proton radiation therapy

    International Nuclear Information System (INIS)

    Objective: the present study proposes the evaluation of the depth-dose profiles and the spatial distribution of radiation dose for ocular proton beam radiotherapy protocols, based on computer simulations in nuclear codes and an eye model discretized into voxels. Materials and methods: the employed computational tools were Geant4 (GEometry ANd Tracking) Toolkit and SISCODES (Sistema Computacional para Dosimetria em Radioterapia - Computer System for Dosimetry in Radiotherapy). Geant4 is a toolkit for simulating the passage of particles through the matter, based on Monte Carlo method. Computer simulations of proton therapy were performed based on preexisting facilities. Results: simulation data were integrated into SISCODES on the eye's model generating spatial dose distributions. Dose depth profiles reproducing the pure and modulated Bragg peaks are presented. Relevant aspects of proton beam radiotherapy planning are considered such as material absorber, modulation, collimator dimensions, incident proton energy and isodose generation. Conclusion: the conclusion is that proton therapy when properly modulated and directed can reproduce the ideal conditions for the dose deposition in the treatment of ocular tumors. (author)

  8. Methods of assessment of absorbed dose in clinical use of radionuclides

    International Nuclear Information System (INIS)

    The purpose of this publication is to extend the ICRU reports into the area of medical internal radiation doses. The report proposes the use of the formalism of Loevinger and Berman that has become familiar in the MIRD publications. The ICRU report refers often to the MIRD Committee works. The report sets out the basic concepts and formulae of internal dosimetry. It then gives an appraisal of the methods for obtaining biological data, ranging from animal distributions through scanning methods. It summarizes the procedures used in estimating absorbed dose, and six examples of dose calculations of increasing complexity are explained in an appendix. The last section of the text briefly mentions problems and recommendations. Among these are the increase in labor required to do these calculations and the need for more and better biological data. It urges the standard tabulation of data to allow for all the sources of internal dose and requests the reporting of original retention data for radiopharmaceuticals rather than just the calculations of radiation dose

  9. Assessment of the absorbed dose to organs from bone mineral density scan by using TLDS and the Monte Carlo method

    Directory of Open Access Journals (Sweden)

    Karimian Alireza

    2014-01-01

    Full Text Available Nowadays, dual energy X-ray absorptiometry is used in bone mineral density systems to assess the amount of osteoporosis. The purpose of this research is to evaluate patient organ doses from dual X-ray absorptiometry by thermoluminescence dosimeters chips and Monte Carlo method. To achieve this goal, in the first step, the surface dose of the cervix, kidney, abdomen region, and thyroid were measured by using TLD-GR 200 at various organ locations. Then, to evaluate the absorbed dose by simulation, the BMD system, patient's body, X-ray source and radiosensitive tissues were simulated by the Monte Carlo method. The results showed, for the spine (left femur bone mineral density scan by using thermoluminescence dosimeters, the absorbed doses of the cervix and kidney were 4.5 (5.64 and 162.17 (3.99(mGy, respectively. For spine (left femur bone mineral density scan in simulation, the absorbed doses of the cervix and kidney were 4.19 (5.88 and 175 (3.68(mGy, respectively. The data obtained showed that the absorbed dose of the kidney in the spine scan is noticeable. Furthermore, because of the small relative difference between the simulation and experimental results, the radiation absorbed dose may be assessed by simulation and software, especially for internal organs, and at different depths of otherwise inaccessible organs which is not possible in experiments.

  10. The dose absorbed by lymphocytes irradiated in vitro with tritiated water

    International Nuclear Information System (INIS)

    A simple method of irradiating cells in vitro with beta particles is to add the ?-emitter to a cell suspension; various dosimetric aspects of this procedure have been investigated. Is is shown that, due to the different water content of the various constituents of a blood cell suspension, the average dose Dsub(?) absorbed by a certain type of cells for a tritium nominal concentration C0 and an irradiation time t is given by Dsub(?)(t) = KEnC0etat. Typical values of the factor eta are calculated for lymphocytes. A series of experiments has demonstrated that whilst the uptake phase has negligible effect on the dose, a significant error may arise during washing-out because a proportion of the activity remains in the cells. (author)

  11. Radiation-induced biomarkers for the detection and assessment of absorbed radiation doses

    Directory of Open Access Journals (Sweden)

    Rana Sudha

    2010-01-01

    Full Text Available Radiation incident involving living organisms is an uncommon but a very serious situation. The first step in medical management including triage is high-throughput assessment of the radiation dose received. Radiation exposure levels can be assessed from viability of cells, cellular organelles such as chromosome and different intermediate metabolites. Oxidative damages by ionizing radiation result in carcinogenesis, lowering of the immune response and, ultimately, damage to the hematopoietic system, gastrointestinal system and central nervous system. Biodosimetry is based on the measurement of the radiation-induced changes, which can correlate them with the absorbed dose. Radiation biomarkers such as chromosome aberration are most widely used. Serum enzymes such as serum amylase and diamine oxidase are the most promising biodosimeters. The level of gene expression and protein are also good biomarkers of radiation.

  12. A Method of Biological Measurement of Thermal- and Fast-Neutron Doses Absorbed by Living Organisms

    International Nuclear Information System (INIS)

    After exposing young rats to a high thermal neutron flux the activated zones were determined by autoradiography at -195°C. The localization and nature of some of the activated elements were studied. Attention is drawn to the important role of P32 compared to other activation products. The authors compare the doses resulting from direct exposure to the neutron flux with those associated with local irradiation of bone and other tissue as a secondary effect of activation. The next step will be to study the possibility of using micro biopsy of bone tissue as a precise means of evaluating absorbed-neutron dose a posteriori in terms of different parts of the organism and different neutron energies. (Measurement of the samples specific P32 activity for thermal neutrons and calculation of the specific Si31 activity for fast neutrons). (author)

  13. Determination of absorbed dose to water in clinical photon beams using a graphite calorimeter and a graphite-walled ionization chamber

    International Nuclear Information System (INIS)

    The absorbed dose to water has been determined from calorimetric absorbed dose measurements in graphite. Clinical photon beams with maximum energies from 1 to 25 MeV were used. The calorimetric data have been converted into absorbed dose to water using an NE 2561 ionization chamber as a transfer device. A different approach to derive absorbed dose to water from the calorimetric data is based on a calculation method, applying mass energy absorption coefficient ratios and O'Connor's scaling theorem. The results obtained with the two methods have been compared with absorbed dose to water values derived from ionization chamber measurements and analysed according to the Dutch Code of Practice. The values for absorbed dose to water derived with the graphite calorimeter and using the two conversion methods are within 1.7% of absorbed dose to water values obtained from the ionometric data. (author). 16 refs, 3 figs

  14. Evaluation of internal absorbed dose of public resulting from radioactive patient and index of radioactive levels for discharge

    International Nuclear Information System (INIS)

    The amount of radiation internally absorbed by the public contaminated by inhalation of air or excretion (sputa, urine, sweat and so on) of the radioactive patient was calculated. This dose determined the permissible radiation level in a room occupied by a patient injected or prescribed radioisotopes. The permissible dose level of radiation absorbed internally by the public must not exceed 0.5 rem/year. The allowable radiation level in the regular room of a radioactive patient should not exceed more than 10 mrem/week of radiation absorbed by another patient in the same room. The absorbed dose by the family in the home of the radioactive patient must not exceed 0.5/3 rem per investigation. The radioactive levels are obtained by calculation for the eight radionuclides 51Cr, 59Fe, 75Se, sup(99m)Tc, 131I, 182Ta, 198Au and 203Hg in both cases. (Evans, J.)

  15. A first order approximation of the tumor absorbed dose prior to treatment with Sr-89

    International Nuclear Information System (INIS)

    A new technique developed for the estimation of the absorbed dose prior to treatment with Sr-89 is presented. This technique implies that patient undergoes bone scanning with Tc-99m-MDP, two days before the administration of Sr-89. A number of sequential quantitative images are to be obtained over the first 8 hours after the Tc-99m-MDP injection and data are used to derive St-89 time retention curve. For the development of this technique a simplified model for the kinetics of both Sr-89 and Tc-99m-MDP was assumed. Data on the time retention of the two radiopharmaceuticals for a compartment including bone surface and bone space of trabecular and cortical bone for normal adults were combined together. A linear relationship was derived between the time required for the same percentage uptake of the two radiopharmaceuticals after single injection. The absorbed dose in the principal metastases and normal bone, of the same type and volume with the metastases, for two patients who were treated with Sr-89 for metastasized prostatic carcinoma are reported. (authors)

  16. Thyroid absorbed dose for people at Rongelap, Utirik, and Sifo on March 1, 1954

    International Nuclear Information System (INIS)

    A study was undertaken to reexamine thyroid absorbed dose estimates for people accidentally exposed to fallout at Rongelap, Sifo, and Utirik Islands from the Pacific weapon test known as Operation Castle BRAVO. The study included: (1) reevaluation of radiochemical analysis, to relate results from pooled urine to intake, retention, and excretion functions; (2) analysis of neutron-irradiation studies of archival soil samples, to estimate areal activities of the iodine isotopes; (3) analysis of source term, weather data, and meteorological functions used in predicting atmospheric diffusion and fallout deposition, to estimate airborne concentrations of the iodine isotopes; and (4) reevaluation of radioactive fallout, which contaminated a Japanese fishing vessel in the vicinity of Rongelap Island on March 1, 1954, to determine fallout components. The conclusions of the acute exposure study were that the population mean thyroid absorbed doses were 21 gray (2100 rad) at Rongelap, 6.7 gray (670 rad) at Sifo, and 2.8 gray (280 rad) at Utirik. The overall thyroid cancer risk we estimated was in agreement with results published on the Japanese exposed at Nagasaki and Hiroshima. We now postulate that the major route for intake of fallout was by direct ingestion of food prepared and consumed outdoors. 66 refs., 13 figs., 25 tabs

  17. Reconstruction of doses absorbed by radiotherapy patients by means of EPR dosimetry in tooth enamel

    International Nuclear Information System (INIS)

    The objective of this study was verification of actual doses absorbed by teeth enamel in patients undergoing radiotherapy treatment. The retrospective dosimetry was based on ex vivo measurements of electron paramagnetic resonance (EPR) signals in teeth extracted from six patients during dental treatment within a few years after radiotherapy with 60Co photons and high-energy photon and electron beams. The measured doses were compared to those calculated by radiotherapy treatment planning (RTP) algorithm (CadPlan 3.1). The total accuracy of dose reconstructions based on EPR measurements was 5-9%. The discrepancy between the planned and measured doses ranged from a few percent (for teeth positioned within the irradiated field) up to about 120% (for teeth located outside the primary beam). Such significant differences between results of RTP calculations and EPR measurement can be explained by changes in geometry of tissues within patient's oral cavity during the treatment, which cannot be accounted for by RTP based on radiotherapy simulation procedure preceding the treatment

  18. Absorbed dose measurements using TLDS in biological samples from beta radiation

    Directory of Open Access Journals (Sweden)

    José Eduardo Manzoli

    2006-01-01

    Full Text Available Irradiation of samples in peculiar experimental apparatus, subject to radiation spread, requires a special evaluation of absorbed dose implanted to the sample. Indirect calibration of the irradiation source, obtained in a different apparatus, and the spread, usually of very difficult theoretical evaluation, can cause very serious measurement errors, sometimes reaching 50%. In this work, the procedure for dose evaluation in an apparatus for beta irradiation of samples, usually biological ones,is presented, making use of calibration curves, obtained by irradiation in advance of thermoluminescent detectors in air, and so irradiating them in the same position of the sample. An application in blood sample irradiation is also presented.A irradiação de amostras em arranjos experimentais peculiares sujeitos a espalhamento necessita de uma determinação própria da dose absorvida que a amostra irá receber. A calibração indireta da fonte de irradiação, que ocorre em arranjo diferente, e o espalhamento, geralmente de difícil estimativa teórica, podem causar erros de medição muito elevados, não raro atingindo 50%. Neste trabalho é apresentado o procedimento para determinação da dose absorvida em um arranjo para irradiação beta de amostras, normalmente biológicas, utilizando curvas de calibração obtidas pela irradiação de dosímetros termoluminescentes no ar, e os irradiando na mesma posição das amostras. É apresentado um exemplo de aplicação para amostra irradiada de sangue.

  19. The measurement of integral absorbed dose in panoramic tomography and in conventional mouth radiography by film method

    International Nuclear Information System (INIS)

    The integral absorbed dose in panoramic tomography (70kVp, 0.8mA) and in conventional full mouth radiography (65kVp, 7.5mA) by means of the film method is reported. The results are as follows; 1) in panoramic tomography: 98g.rad per film 2) in full mouth radiography: 37g.rad average per film There are many reports about the integral absorbed dose but each method of arriving at an integral dose is not same and there are several variations in the experimental conditions. A comparison of the results is difficult. (author)

  20. A new method for deriving the absorbed dose in phantom material from measured ion dose for X-rays generated at voltages up to 300 kV

    International Nuclear Information System (INIS)

    Within the scope of providing primary standards for realizing the unit of absorbed dose in water for therapy level dose meters at all energies between 5 keV and 50 MeV, the low energy region for X-rays up to 300 kV generating voltage presents particular difficulties. Absorbed dose in water cannot be determined directly in water because chamber walls of solid material have to be introduced, and there is no material available which is sufficiently air or water equivalent in this energy region. Other materials have to be used which require the conversion of experimentally determined values. The paper describes how by use of extrapolation chambers made of graphite and Plexiglas data are obtained from which by a new analysing method the absorbed dose in the material is derived. The theoretical background of the applied method is discussed and results of measurements for Plexiglas and graphite phantom materials are reported. (author)

  1. Establishment of calorimetry based absorbed dose standard for newly installed Elekta Synergy accelerator at ARPANSA

    International Nuclear Information System (INIS)

    An Elekta Synergy Linear Accelerator providing 7 photon energies from 4 MeV to 25 MeV and 10 electron energies from 4MeV to 22 MeV was installed at the beginning of 2009 to provide calibration services to radiotherapy centres in the country.This accelerator is similar to the one that has been installed at NPL around the same time. After the acceptance testing and commissioning, calorimetry measurements of the photon beams at nominal energies of 6 MeV, 10 MeV and 18 MeV to establish the Australian Primary standard of absorbed dose have been done. This paper brings out the details of the measurements and the results of a bilateral intercomparison done with NPL. A graphite calorimeter procured from BEV, Austria has been established as primary standard in the '90s at the 60Co energy and a similar calorimeter loaned by IAEA has been compared giving good agreement in measurements with a 60Co source at ARPANSA. The IAEA calorimeter has been found to have better stability through a good medium control against the ambient temperature variations. This calorimeter has been used for measurements with the photon beams from the accelerator. Before the actual measurements, a study of the stability of thermistors and the electronic heater control circuitries was done through a series of electrical calibrations. The electrical calibration factor which gives the energy required to produce a fractional resistance change of the core thermistor has been found to havethe core thermistor has been found to have a constant value of -230 mJ/%R with a standard deviation of 0.4% similar to other results published for this type of calorimeter. The photon beams from the accelerator have an initial ramping dose-rate for 1-2 seconds before stabilising to a near constant value. The dose-rate profiles obtained through the output of the monitor chamber located inside the head of the accelerator is shown. The dose-rate variations are corrected in the data analysis program written in Matlab software. Calorimetry measurements have been done in both quasi-adiabatic and quasi-isothermal modes. In the quasi-isothermal mode initially all the three bodies of the calorimeter (core, jacket and shield) are raised in temperatures with constant heating rates calculated based on the dose-rate obtained through the quasi-adiabatic mode. At the end of the heating period the radiation beam is brought on and the heaters switched off. Similarly at the end of the radiation run the heaters are switched on again to continue heating. The switching off/on of the heaters with radiation beam on/off is being done through a specially designed electronic circuit triggered by the output pulses from the monitor chamber.This has helped in reducing the uncertainties and improving the consistency of repeated measurements. Conversion of graphite absorbed dose to water absorbed dose is done through calorimetry, measurements of ionisation current in a graphite-walled chamber in a graphite phantom similar to the calorimeter and chamber measurements in a water tank all at the same distance. The conversion makes use of Monte-Carlo calculated doses in the graphite and water. Gap correction for the calorimeter is calculated using EGSnrc and the correction factor for radial non-uniformity is evaluated through beam profile measurements moving a thimble chamber mounted in a graphite phantom similar in construction to the calorimeter. As part of a bilateral intercomparison of accelerator measurements a graphite walled chamber was taken to NPL, U.K and was calibrated in their photon beams. The NPL-calibrated chamber was calibrated at ARPANSA against the IAEA calorimeter and the results of this intercomparison are presented here

  2. Control letters and uncertainties of the kerma patterns in air, dose absorbed in water and dose absorbed in air of the LSCD

    International Nuclear Information System (INIS)

    With the purpose of characterizing the component of uncertainty of long term of the patron ionization chambers of the LSCD, for the magnitudes: speed of kerma in air ??·, dose speed absorbed in water D?·, and speed absorbed dose in air D?·, it use the technique of letters of control l-MR/S. This statistical technique it estimates the component of uncertainty of short term by means of the deviation standard inside groups ?? and that of long term by means of the standard deviation among groups ??, being this it finishes an estimator of the stability of the patterns.The letters of control l-MR/S it construct for: i) ??·, in radiation field of 60Co for patterns: primary CC01 series 131, secondary NE 2611 series 176, secondary PTW TN30031 series 578 and Third PTW W30001 series 365. ii) D?),en radiation field of 60Co for patterns: primary CC01 series 131, Secondary PTW TN30031 series 578 and tertiary PTW W30001 series 365. iii) I-MR/S with extrapolation chamber PTW primary pattern, measurement realizes in secondary patron fields of 90Sr-90Y. The expanded uncertainty U it is calculated of agreement with the Guide of the ISO/BIPM being observed the following thing: a. In some the cases ??, is the component of the U that more contributed to this. Therefore, it is necessary to settle down technical of sampling in those mensurations that allow to reduce the value of ??. For example with sizes of subgroup ?? 30 data, or with a number of subgroups ??. That which is achieved automating the mensuration processes. b.The component of the temperature is also one of those that but they contribute to the U, of there the necessity of: to recover the tracking for this magnitude of it influences and to increase the precision in the determinations of the temperature to diminish their influence in the U. c. The percentage difference of the magnitudes dosemeters carried out by it patterns are consistent with U certain. However, it is necessary to diminish the uncertainty in the physical factors different to ?? and ?? for the one case of the primary patterns; because these they should be those of smaller value of U. d. In the case of the secondary patterns and tertiary for the realization of the??· is necessary to determine the corrections explicitly for recombination and polarization; and to analyze their contribution in the U. e. It is necessary to recover the tracking for the mensurations of the humidity. f. It is recommended to continue the control mensurations for each pattern, taking its the least a measure every fifteen days, that it corresponds at two measured for month and 24 at the year. g. The operation of the air conditioned perturb the measurement for such as it recommends not to use it, and alone to leave in balance the chamber with the air of the engine room. (Author)

  3. Comparative evaluation of average glandular dose and breast cancer detection between single-view digital breast tomosynthesis (DBT) plus single-view digital mammography (DM) and two-view DM: correlation with breast thickness and density

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Sung Ui; Chang, Jung Min; Bae, Min Sun; Lee, Su Hyun; Cho, Nariya; Seo, Mirinae; Kim, Won Hwa; Moon, Woo Kyung [Seoul National University Hospital, Department of Radiology, Seoul (Korea, Republic of)

    2015-01-15

    To compare the average glandular dose (AGD) and diagnostic performance of mediolateral oblique (MLO) digital breast tomosynthesis (DBT) plus cranio-caudal (CC) digital mammography (DM) with two-view DM, and to evaluate the correlation of AGD with breast thickness and density. MLO and CC DM and DBT images of both breasts were obtained in 149 subjects. AGDs of DBT and DM per exposure were recorded, and their correlation with breast thickness and density were evaluated. Paired data of MLO DBT plus CC DM and two-view DM were reviewed for presence of malignancy in a jack-knife alternative free-response ROC (JAFROC) method. The AGDs of both DBT and DM, and differences in AGD between DBT and DM (?AGD), were correlated with breast thickness and density. The average JAFROC figure of merit (FOM) was significantly higher on the combined technique than two-view DM (P = 0.005). In dense breasts, the FOM and sensitivity of the combined technique was higher than that of two-view DM (P = 0.003) with small ?AGD. MLO DBT plus CC DM provided higher diagnostic performance than two-view DM in dense breasts with a small increase in AGD. (orig.)

  4. Comparative evaluation of average glandular dose and breast cancer detection between single-view digital breast tomosynthesis (DBT) plus single-view digital mammography (DM) and two-view DM: correlation with breast thickness and density

    International Nuclear Information System (INIS)

    To compare the average glandular dose (AGD) and diagnostic performance of mediolateral oblique (MLO) digital breast tomosynthesis (DBT) plus cranio-caudal (CC) digital mammography (DM) with two-view DM, and to evaluate the correlation of AGD with breast thickness and density. MLO and CC DM and DBT images of both breasts were obtained in 149 subjects. AGDs of DBT and DM per exposure were recorded, and their correlation with breast thickness and density were evaluated. Paired data of MLO DBT plus CC DM and two-view DM were reviewed for presence of malignancy in a jack-knife alternative free-response ROC (JAFROC) method. The AGDs of both DBT and DM, and differences in AGD between DBT and DM (?AGD), were correlated with breast thickness and density. The average JAFROC figure of merit (FOM) was significantly higher on the combined technique than two-view DM (P = 0.005). In dense breasts, the FOM and sensitivity of the combined technique was higher than that of two-view DM (P = 0.003) with small ?AGD. MLO DBT plus CC DM provided higher diagnostic performance than two-view DM in dense breasts with a small increase in AGD. (orig.)

  5. Absorbed dose measurements for kV-cone beam computed tomography in image-guided radiation therapy

    Science.gov (United States)

    Hioki, Kazunari; Araki, Fujio; Ohno, Takeshi; Nakaguchi, Yuji; Tomiyama, Yuuki

    2014-12-01

    In this study, we develope a novel method to directly evaluate an absorbed dose-to-water for kilovoltage-cone beam computed tomography (kV-CBCT) in image-guided radiation therapy (IGRT). Absorbed doses for the kV-CBCT systems of the Varian On-Board Imager (OBI) and the Elekta X-ray Volumetric Imager (XVI) were measured by a Farmer ionization chamber with a 60Co calibration factor. The chamber measurements were performed at the center and four peripheral points in body-type (30?cm diameter and 51?cm length) and head-type (16?cm diameter and 33?cm length) cylindrical water phantoms. The measured ionization was converted to the absorbed dose-to-water by using a 60Co calibration factor and a Monte Carlo (MC)-calculated beam quality conversion factor, kQ, for 60Co to kV-CBCT. The irradiation for OBI and XVI was performed with pelvis and head modes for the body- and the head-type phantoms, respectively. In addition, the dose distributions in the phantom for both kV-CBCT systems were calculated with MC method and were compared with measured values. The MC-calculated doses were calibrated at the center in the water phantom and compared with measured doses at four peripheral points. The measured absorbed doses at the center in the body-type phantom were 1.96?cGy for OBI and 0.83?cGy for XVI. The peripheral doses were 2.36–2.90?cGy for OBI and 0.83–1.06?cGy for XVI. The doses for XVI were lower up to approximately one-third of those for OBI. Similarly, the measured doses at the center in the head-type phantom were 0.48?cGy for OBI and 0.21?cGy for XVI. The peripheral doses were 0.26–0.66?cGy for OBI and 0.16–0.30?cGy for XVI. The calculated peripheral doses agreed within 3% in the pelvis mode and within 4% in the head mode with measured doses for both kV-CBCT systems. In addition, the absorbed dose determined in this study was approximately 4% lower than that in TG-61 but the absorbed dose by both methods was in agreement within their combined uncertainty. This method is more robust and accurate compared to the dosimetry based on a conventional air-kerma calibration factor. Therefore, it is possible to be used as a standard dosimetry protocol for kV-CBCT in IGRT.

  6. Evaluation of absorbed dose-distribution in the X-ray or gamma-irradiator for blood products

    International Nuclear Information System (INIS)

    Irradiation of blood products abrogates the proliferation of lymphocytes present in cellular component, which is currently the only accepted methodology to prevent transfusion-associated graft versus host disease (TA-GVHD). A range of irradiation dose levels between 15 Gy and 50 Gy is being used, but the majority of facilities are employing 15 Gy. It should, however, be recognized that the delivered dose in the instrument canister might differ from the actual dose absorbed by the blood bag. This study have evaluated the actual dose distribution under practical conditions where a container was loaded with blood products or water bags, or filled with distilled water. This approach provides data that the maximum attenuation occurred when the container was completely filled with a blood-compatible material. Thus, an error of approximately 20 percent should be considered in the dose measured in the in-air condition. A dose calibration in an in-air condition may lead to substantial underexposure of the blood products. A dose distribution study using adequately prearranged exposure period verified that the absorbed dose of 15 Gy was attained at any point in the container for both linear accelerator and gamma-irradiator. The maximal difference in the absorbed dose between measured points was 1.5- and 1.6-fold for linear accelerator and gamma-irradiator, respectively. In conclusion, using blood-compatible materials, a careful dose calibration study should be employed in which bration study should be employed in which the absorbed dose of 15 Gy is obtained at the point where the lowest dose could be expected. (author)

  7. Comparison of skin absorbed radiation dose in thyroid gland area during panoramic radiography and spiral tomography techniques

    Directory of Open Access Journals (Sweden)

    Najmeh Akhlaghi

    2011-01-01

    Full Text Available Introduction: Thyroid gland is one of the critical organs during radiation in the head and neck region. The aim of this study was to compare absorbed radiation dose by skin in the thyroid area during spiral tomography and panoramic radiography by means of thermoluminance dosimetry (TLD.Materials and Methods: Thirty-six LiF (TLD-100 thermoluminescence dosimetry chips were utilized in this experimental in vitro study. One TLD chip was placed on the tube side and another was placed on the opposite side of the thyroid gland of a sliced anatomic Alderson head and neck phantom during panoramic radiography and spiral tomography. The dosimeters were read by a SOLARO 2A TLD reader twice followed by calculation of the absorbed dose. The results were analyzed by Wilcoxon’s test at a confidence interval of 95%.Results: The mean dose for screen-film panoramic radiographs was 34 µGy in the left thyroid and 39 on the right side. With spiral tomography the thyroid gland received a mean dose of 30?71 µGy. There were no statistically significant differences in the mean thyroid doses between anterior and posterior spiral tomography and panoramic examination (p value > 0.05.Conclusion: Skin absorbed radiation dose of a tomographic examination, which includes four sections with a specific thickness, are almost comparable to that with a panoramic radiographic technique. Key words: Absorbed dose, Spiral tomography, Panoramic radiography.

  8. Evaluation of variations in absorbed dose and image noise according to patient forms in X-ray computed tomography

    International Nuclear Information System (INIS)

    Excessive radiation exposure in pediatric computed tomography (CT) scanning has become a serious problem, and it is difficult to select scan parameters for the scanning of small patients such as children. We investigated differences in absorbed dose and standard deviation (SD) in Hounsfield unit (HU) caused by differences in the form of the subject using a body-type phantom with removable body parts. Using four X-ray CT scanners, measurements were made with values from 50 mAs to 300 mAs, with slices of 50 mAs, using scan protocols that were assumed to perform thorough examinations. The results showed that the mAs values and absorbed doses were almost proportional, and the absorbed doses in the phantom without body parts were about 1.1-2.2-fold higher than those of the phantom with body parts at the same points. The SD values obtained indicated that the absorbed doses in the phantom with body parts were 0.3-0.6 times those of the phantom without body parts when the mAs values used were adjusted so that both SD values were the same. The absorbed doses in various patient forms can be estimated from these results, and they will become critical data for the selection of appropriate scan protocols. (author)

  9. The sensitivity analysis of tooth enamel to the absorbed dose for the application to EPR dosimetry

    International Nuclear Information System (INIS)

    Electron Paramagnetic Resonance (EPR) spectroscopy is one of the methods applicable to retrospective dosimetry. The retrospective dosimetry is a process that is a part of dose reconstruction for estimation of exposed dose occurred years before the estimation. Many techniques can be used to the retrospective dosimetry. As a physical method, EPR analysis of biological material measures the quantity of free radicals generated in the material from the interaction of radiation and material. Since the later 80s, in many countries, EPR dosimetry with tooth enamel has been studied and applied for the retrospective dosimetry. In the consideration of the biological materials for EPR dosimetry, human fingernail, hair, bone and tooth are generally considered. The tooth can be separated as enamel, dentine and cementum. Among the three parts, enamel shows the best sensitivity to the absorbed dose and is most widely used. In this study, the characteristics of tooth enamel for EPR dosimetry is examined and experimented. At the experiment, for easy separation, tooth was cut into 4 parts and then each part is treated by ultrasonic vibration in NaOH liquid to reduce mechanically induced noise in the corresponding signal. After the separation of the enamel from dentine, background EPR signal is measured and then radiation-induced EPR spectrum is estimated

  10. Measurements of spatial distribution of absorbed dose in proton therapy with Gafchromic EBT3

    Energy Technology Data Exchange (ETDEWEB)

    Gambarini, G.; Regazzoni, V.; Grisotto, S.; Artuso, E.; Giove, D. [Universita degli Studi di Milano, Department of Physics, via Celoria 16, 20133 Milano (Italy); Borroni, M.; Carrara, M.; Pignoli, E. [Fondazione IRCCS, Istituto Nazionale dei Tumori di Milano, Medical Physics Unit, via Giacomo Venezian 16, 20133 Milano (Italy); Mirandola, A.; Ciocca, M., E-mail: grazia.gambarini@mi.infn.it [Centro Nazionale Adroterapia Oncologica, Medical Physics Unit, Strada Campeggi 53, 27100 Pavia (Italy)

    2014-08-15

    A study of the response of EBT3 films has been carried out. Light transmittance images (around 630 nm) were acquired by means of a Ccd camera. The difference of optical density was assumed as dosimeter response. Calibration was performed by means of {sup 60}Co photons, at a radiotherapy facility. A study of the response variation during the time after exposure has been carried out. EBT3 films were exposed, in a solid-water phantom, to proton beams of various energies and the obtained depth-dose profiles were compared with those measured with a ionization chamber. As expected, in the Bragg peak region the values obtained with EBT3 films were lower than those obtained with the ionization chamber. The ratio of such values was evaluated, along dose profiles, for each utilized energy. A method for correcting the data measured with EBT3 has been proposed and tested. The results confirm that the method can be advantageously applied for obtaining spatial distribution of the absorbed dose in proton therapy. (author)

  11. Verification of absorbed dose calculation with XIO Radiotherapy Treatment Planning System

    International Nuclear Information System (INIS)

    Modern radiotherapy relies on computerized treatment planning systems (TPS) for absorbed dose calculation. Most TPS require a detailed model of a given machine and therapy beams. International Atomic Energy Agency (IAEA) recommends acceptance testing for the TPS (IAEA-TECDOC-1540). In this study we present customization of those tests for measurements with the purpose of verification of beam models intended for clinical use in our department. Elekta Synergy S linear accelerator installation and data acquisition for Elekta CMS XiO 4.62 TPS was finished in 2011. After the completion of beam modelling in TPS, tests were conducted in accordance with the IAEA protocol for TPS dose calculation verification. The deviations between the measured and calculated dose were recorded for 854 points and 11 groups of tests in a homogenous phantom. Most of the deviations were within tolerance. Similar to previously published results, results for irregular L shaped field and asymmetric wedged fields were out of tolerance for certain groups of points.(author)

  12. Magnetic Resonance Imaging-Based Radiation-Absorbed Dose Estimation of 166Ho Microspheres in Liver Radioembolization

    International Nuclear Information System (INIS)

    Purpose: To investigate the potential of magnetic resonance imaging (MRI) for accurate assessment of the three-dimensional 166Ho activity distribution to estimate radiation-absorbed dose distributions in 166Ho-loaded poly (L-lactic acid) microsphere (166Ho-PLLA-MS) liver radioembolization. Methods and Materials: MRI, computed tomography (CT), and single photon emission CT (SPECT) experiments were conducted on an anthropomorphic gel phantom with tumor-simulating gel samples and on an excised human tumor-bearing liver, both containing known amounts of 166Ho-PLLA-MS. Three-dimensional radiation-absorbed dose distributions were estimated at the voxel level by convolving the 166Ho activity distribution, derived from quantitative MRI data, with a 166Ho dose point-kernel generated by MCNP (Monte Carlo N-Particle transport code) and from Medical Internal Radiation Dose Pamphlet 17. MRI-based radiation-absorbed dose distributions were qualitatively compared with CT and autoradiography images and quantitatively compared with SPECT-based dose distributions. Both MRI- and SPECT-based activity estimations were validated against dose calibrator measurements. Results: Evaluation on an anthropomorphic phantom showed that MRI enables accurate assessment of local 166Ho-PLLA-MS mass and activity distributions, as supported by a regression coefficient of 1.05 and a correlation coefficient of 0.99, relating locallation coefficient of 0.99, relating local MRI-based mass and activity calculations to reference values obtained with a dose calibrator. Estimated MRI-based radiation-absorbed dose distributions of 166Ho-PLLA-MS in an ex vivo human liver visually showed high correspondence to SPECT-based radiation-absorbed dose distributions. Quantitative analysis revealed that the differences in local and total amounts of 166Ho-PLLA-MS estimated by MRI, SPECT, and the dose calibrator were within 10%. Excellent agreement was observed between MRI- and SPECT-based dose–volume histograms. Conclusions: Quantitative MRI was demonstrated to provide accurate three-dimensional 166Ho-PLLA-MS activity distributions, enabling localized intrahepatic radiation-absorbed dose estimation by convolution with a 166Ho dose point-kernel for liver radioembolization treatment optimization and evaluation.

  13. Concentration activities of natural radionuclides in three fish species in Brazilian coast and their contributions to the absorbed doses

    International Nuclear Information System (INIS)

    Activity concentrations of U-238, Ra-226, Pb-210, Th-232 e Ra-228 were analysed in three fish species at the Brasilian Coast. The fish 'Cubera snapper' (Lutjanus cyanopterus, Cuvier, 1828), in the region of Ceara and 'Whitemouth croaker' (Micropogonias furnieri, Desmarest, 1823) and 'Lebranche mullet' (Mugil liza, Valenciennes, 1836) in the region of Rio de Janeiro. These concentrations were transformed in absorbed dose rate using a dose conversion factor in unit of gray per year (?Gy y-1), per becquerel per kilogram (Bq kg-1). Only the absorbed dose due to intake of radionuclides was examined, and the contributions due to radionuclides present in water and sediment were disregarded. The radionuclides were considered to be uniformly distributed in the fish body. The limit of the dose rate used, proposed by the Department of Energy of the USA, is equal to 3.65 1003 mGy y-1. The average dose rate due to the studied radionuclides is equal to 6.09 1000 ?Gy y-1, a value minor than 0.1% than the limits indicated by DOE, and quite similar to that found in the literature for 'benthic' fish. The most important radionuclides were the alpha emitters Ra-226 having 61 % of absorbed dose rate. U-238 and Th-232, each contributes with approximately 20 % of the absorbed dose rate. These three radionuclides are responsible for almost 100% of the dose rate received by the studied organisms. The beta emitters Ra-228 and Pb-210 account for approximately 1 % of the absorbed dose rate. (author)

  14. Absorbed dose distributions in a tissue-equivalent absorber for Bremsstrahlung produced at the beamlines of the European Synchrotron Radiation Facility

    CERN Document Server

    Pisharody, M; Berkvens, P; Colomp, P

    2000-01-01

    The absorbed-dose distributions for Bremsstrahlung, incident on a tissue-equivalent phantom, were measured with LiF : Mg,Ti thermoluminescent dosimeters at two insertion device beamlines of the European Synchrotron Radiation Facility (ESRF). The measurements were carried out for two different electron beam energies of 4 and 6 GeV. The corresponding Bremsstrahlung spectra and power were measured using a high-resolution lead glass total absorption calorimeter. The results are compared with similar measurements carried out at other facilities. The normalized Bremsstrahlung absorbed dose in a cross-sectional area of 100 mm sup sup 2 , at a depth of 150 mm of the phantom, was measured as 6.1 and 3.6 kGy h sup sup - sup sup 1 W sup sup - sup sup 1 for the corresponding Bremsstrahlung spectra of 4 and 6 GeV.

  15. Absorbed dose in ion beams: comparison of ionisation- and fluence-based measurements.

    Science.gov (United States)

    Osinga, Julia-Maria; Brons, Stephan; Bartz, James A; Akselrod, Mark S; Jäkel, Oliver; Greilich, Steffen

    2014-10-01

    A direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionisation chamber is presented. Irradiations were performed using monoenergetic protons (142.66 MeV, ?=3×10(6) cm(-2)) and carbon ions (270.55 MeV u(-1), ?=3 × 10(6) cm(-2)). It was found that absorbed dose to water values as determined by fluence measurements using FNTDs are, in case of protons, in good agreement (2.4 %) with ionisation chamber measurements, if slower protons and Helium secondaries were accounted for by an effective stopping power. For carbon, however, a significant discrepancy of 4.5 % was seen, which could not be explained by fragmentation, uncertainties or experimental design. The results rather suggest a W-value of 32.10 eV ± 2.6 %. Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not observed. PMID:24497551

  16. Traceability of metrologic references of dose absorbed to water used in a Dosimetry Quality Assurance Program

    International Nuclear Information System (INIS)

    Objective: to present the solidly established traceability structure for ionometric standards and for thermoluminescent dosimetry system that ensures reliability of the Dosimetry Quality Assurance Program and is aimed to certify the highest level of accuracy of the measurements. Materials and methods: thermoluminescent powder dosimeters (DTL 937) placed into plastic capsules and packed in specific kits for each intended application were mailed to the participant centers. Results: the results of the intercomparisons performed between 'Laboratorio de Ciencias Radiologicas da Universidade do Estado do Rio de Janeiro' and EQUAL-ESTRO for the beam of 60Co gamma rays, expressed for (1?), and the results of the dose absorbed measurements obtained with the chambers of the Program EQUAL and the chambers of the Dosimetry Quality Assurance Program were lower than 0.5%. Conclusion: based on these results we concluded that the Dosimetry Quality Assurance Program reached the desired level of reliability to allow its implementation. (author)

  17. Estimated absorbed doses from exposure to a cyclotron used in production of radiopharmaceuticals

    International Nuclear Information System (INIS)

    Nuclear medicine diagnostics and therapy use radiopharmaceuticals, which are pharmaceuticals with radionuclides attached to the biologically active chemical compound with the purpose of marking it in order to follow its metabolism in a living organism. The basic advantage of using radiopharmaceuticals is that they can be monitored by nuclear methods and their deposition in a particular organ or metabolic processes followed over time. Unlike classical radiology, which shows only morphological changes in an organ, with radiopharmaceuticals we can follow their functional changes. This article discusses estimated occupational exposure of three workers to a cyclotron IBA Cyclone 18/9 at Rudjer Medikol Cyclotron Ltd. (RMC). The total absorbed annual dose is estimated to between 2.95 mSv and 6.77 mSv. The requirement of minimal exposure to any form of radiation - ALARA (As Low As Reasonably Achievable.), recommended by Croatian legislation, is fully met. (authors)

  18. Development of single grain OSL dating of ceramic materials: Spatially resolved measurement of absorbed dose

    International Nuclear Information System (INIS)

    The feasibility of using an OSL scanning technique to determine the cumulative absorbed dose for single inclusions in sliced brick samples is explored in this paper. The OSL scanner was configured to provide optical stimulation using laser sources with either blue/green or near-IR wavelengths. A regenerative OSL procedure was successfully applied to determine the palaeodose for single grains of quartz in the surface of the ceramic slices ranging in diameter from ?60 to ?750?m. The results obtained compare well with calculated values of palaeodose obtained by scaling the measured values of palaeodose obtained using a single aliquot regenerative procedure with disaggregated quartz inclusions extracted from the same brick and prepared using the conventional inclusion technique

  19. Response functions for computing absorbed dose to skeletal tissues from neutron irradiation

    International Nuclear Information System (INIS)

    Spongiosa in the adult human skeleton consists of three tissues-active marrow (AM), inactive marrow (IM) and trabecularized mineral bone (TB). AM is considered to be the target tissue for assessment of both long-term leukemia risk and acute marrow toxicity following radiation exposure. The total shallow marrow (TM50), defined as all tissues lying within the first 50 ?m of the bone surfaces, is considered to be the radiation target tissue of relevance for radiogenic bone cancer induction. For irradiation by sources external to the body, kerma to homogeneous spongiosa has been used as a surrogate for absorbed dose to both of these tissues, as direct dose calculations are not possible using computational phantoms with homogenized spongiosa. Recent micro-CT imaging of a 40 year old male cadaver has allowed for the accurate modeling of the fine microscopic structure of spongiosa in many regions of the adult skeleton (Hough et al 2011 Phys. Med. Biol. 56 2309-46). This microstructure, along with associated masses and tissue compositions, was used to compute specific absorbed fraction (SAF) values for protons originating in axial and appendicular bone sites (Jokisch et al 2011 Phys. Med. Biol. 56 6857-72). These proton SAFs, bone masses, tissue compositions and proton production cross sections, were subsequently used to construct neutron dose-response functions (DRFs) for both AM and TM50 targets in each bone of the reference adult male. Kerma conditio the reference adult male. Kerma conditions were assumed for other resultant charged particles. For comparison, AM, TM50 and spongiosa kerma coefficients were also calculated. At low incident neutron energies, AM kerma coefficients for neutrons correlate well with values of the AM DRF, while total marrow (TM) kerma coefficients correlate well with values of the TM50 DRF. At high incident neutron energies, all kerma coefficients and DRFs tend to converge as charged-particle equilibrium is established across the bone site. In the range of 10 eV to 100 MeV, substantial differences are observed among the kerma coefficients and DRF. As a result, it is recommended that the AM kerma coefficient be used to estimate the AM DRF, and that the TM kerma coefficient be used to estimate the TM50 DRF below 10 eV. Between 10 eV and 100 MeV, the appropriate DRF should be used as presented in this study. Above 100 MeV, spongiosa kerma coefficients apply well for estimating skeletal tissue doses. DRF values for each bone site as a function of energy are provided in an electronic annex to this article available at http://stacks.iop.org/0031-9155/56/6873/mmedia.

  20. Absorbed dose estimates to structures of the brain and head using a high-resolution voxel-based head phantom

    International Nuclear Information System (INIS)

    The purpose of this article is to demonstrate the viability of using a high-resolution 3-D head phantom in Monte Carlo N-Particle (MCNP) for boron neutron capture therapy (BNCT) structure dosimetry. This work describes a high-resolution voxel-based model of a human head and its use for calculating absorbed doses to the structures of the brain. The Zubal head phantom is a 3-D model of a human head that can be displayed and manipulated on a computer. Several changes were made to the original head phantom which now contains over 29 critical structures of the brain and head. The modified phantom is a 85x109x120 lattice of voxels, where each voxel is 2.2x2.2x1.4 mm3. This model was translated into MCNP lattice format. As a proof of principle study, two MCNP absorbed dose calculations were made (left and right lateral irradiations) using a uniformly distributed neutron disk source with an 1/E energy spectrum. Additionally, the results of these two calculations were combined to estimate the absorbed doses from a bilateral irradiation. Radiobiologically equivalent (RBE) doses were calculated for all structures and were normalized to 12.8 Gy-Eq. For a left lateral irradiation, the left motor cortex receives the limiting RBE dose. For a bilateral irradiation, the insula cortices receive the limiting dose. Among the nonencephalic structures, the parotid glands receive RBE doses that were within 15% of the limiting dose

  1. The analyses of the absorbed dose by the red marrow brain of wild hunting hoofed animals from incorporated 90Sr

    International Nuclear Information System (INIS)

    After research work has been valued the absorbed dose by the red marrow brain of wild hunting hoofed animals on the territory with different level of radioactive pollution was shown that the absorbed annual doses of incorporated Sr 90 by the red marrow brain on the territory of eviction and alienation zones formed for wild boar 19,5-28,3 mGy/year, roe deer european 8,0-24,2 mGy/year, and for elk 16,1-55,0 mGy/year. The absorber doses by the red marrow brain of wild hunting hoofed taken in the control regions fluctuated from 0,6 mGy/year roe deer european to 1,4 mGy/year wild boar. (authors)

  2. Dosimetry audits based on NCS report 18: Assessment of absorbed dose to water in external beam therapy

    International Nuclear Information System (INIS)

    In 2008 the Netherlands Commission for Radiation Dosimetry (NCS) published a new code of practice (NCS-18) for the absorbed dose determination in high energy photon and electron beams. NCS-18 replaces NCS-2 and NCS-5 for absolute dosimetry of clinical photon and electron beams, respectively. In contrast to NCS-2 and -5, it is based on absorbed dose to water calibration coefficients in 60Co beams. Most radiotherapy centres in Belgium and the Netherlands are currently implementing NCS-18. To monitor and verify the implementation of NCS-18, the Dutch Association of Medical Physics Engineers (NVKFM) in collaboration with the NCS established the NCS-subcommittee Dosimetry Audits. The aim of the audit is to verify local measurements of absorbed dose under reference conditions. Initially only clinical photon beams are being audited. In total 26 radiotherapy centres have been audited before the summer of 2010. In this study preliminary results of the audits until April 2010 are reported

  3. Absorbed doses profiles vs Synovia tissue depth for the Y-90 and P-32 used in radiosynoviortesis treatment

    International Nuclear Information System (INIS)

    The radiosynoviortesis treatment has been used during more of 40 years as an alternative to the chemical and surgical synovectomy to alleviate the pain and to reduce the inflammation in suffered patients of rheumatic arthropathies, haemophilic arthropathies and other articulation disorders. It consists on the injection of radioactive isotopes inside a synovial cavity. For to evaluate the dosimetry of the radiosynoviortesis treatment is of great interest to know the absorbed dose in the volume of the target (synovia). The precise calculation of the absorbed dose in the inflamed synovia it is difficult, for numerous reasons, since the same one will depend on the thickness of the synovial membrane, the size of the articular space, the structure of the synovial membrane, the distribution in the articulation, the nature of the articular liquid, etc. Also the presence of the bone and the articular cartilage, components also of the articulation, it even complicated more the calculations. The method used to evaluate the dosimetry in radioactive synovectomy is known as the Monte Carlo method. The objective of our work consists on estimating with the Monte Carlo code MCNP4B the absorbed dose of the Y-90 and the P-32 in the depth of the synovial tissue. The results are presented as absorbed dose for injected millicurie (Gy/mCi) versus depth of synovial tissue. The simulation one carries out keeping in mind several synovia areas, of 50 cm2 to 250 cm2 keeping in mind three states of progression of the illness. Those obtained values of absorbed dose using the MCNP4B code will allow to introduce in our country an optimized method of dose prescription to the patient, to treat the rheumatic arthritis in medium and big articulations using the Y-90 and the P-32, eliminating the fixed doses and fixed radionuclides for each articulation like it happens in many clinics of Europe, as well as the empiric doses. (Author)

  4. 90Y/90 Sr electron induced damages in an essential eucalyptus oil related to the absorbed dose

    International Nuclear Information System (INIS)

    A good irradiation geometry was achieved in order to carry out the irradiation of an essential eucalyptus oil with a 90Y/90 Sr electron source. The Monte Carlo simulation code MCNP-4C was employed to determine the absorbed doses in this particular experimental configuration. It also helped us to understand which electrons (from an energetic point of view) were responsible for the damages. In order to identify the induced damages, the irradiated samples were studied by mass spectrometry. The obtained results were related to the absorbed doses determined by the computational simulation

  5. Determining absorbed dose versus depth in materials exposed to the x-ray output of flash x-ray machines

    International Nuclear Information System (INIS)

    A stack of layers of materials interspersed with thin dosimeters is exposed at a large enough distance from the machine so that the direction of the incident radiation can be well defined. A set of small spheres containing dosimeters is then constructed and used to check the absorbed dose versus depth closer to the source where no single direction of the incident radiation determines the absorbed dose. The practice includes a discussion of interferences, apparatus, procedure, interpretation of results, precision, and accuracy. The practice is applicable to all machines with photon energy spectra of 100 keV to 20 MeV

  6. Effect of tungsten absorption edge filter on diagnostic x-ray spectra, image quality and absorbed dose to the patient

    International Nuclear Information System (INIS)

    The X-ray spectra from a tungsten-target diagnostic tube were measured with a lithium-drifted silicon detector. Four characteristic X-ray peaks were clearly observed. When a 0.05-0.3 mm thick tungsten absorption edge filter was added to the tube, the number of photons in the spectra above the K-absorption edge decreased dramatically. The effect of the absorption edge filter on image quality and on the absorbed dose were investigated by both measurement and Monte Carlo calculation. The absorbed dose to the patient is reduced without image quality, being degraded. (author)

  7. Monte Carlo Analysis of Pion Contribution to Absorbed Dose from Galactic Cosmic Rays

    Science.gov (United States)

    Aghara, S.K.; Battnig, S.R.; Norbury, J.W.; Singleterry, R.C.

    2009-01-01

    Accurate knowledge of the physics of interaction, particle production and transport is necessary to estimate the radiation damage to equipment used on spacecraft and the biological effects of space radiation. For long duration astronaut missions, both on the International Space Station and the planned manned missions to Moon and Mars, the shielding strategy must include a comprehensive knowledge of the secondary radiation environment. The distribution of absorbed dose and dose equivalent is a function of the type, energy and population of these secondary products. Galactic cosmic rays (GCR) comprised of protons and heavier nuclei have energies from a few MeV per nucleon to the ZeV region, with the spectra reaching flux maxima in the hundreds of MeV range. Therefore, the MeV - GeV region is most important for space radiation. Coincidentally, the pion production energy threshold is about 280 MeV. The question naturally arises as to how important these particles are with respect to space radiation problems. The space radiation transport code, HZETRN (High charge (Z) and Energy TRaNsport), currently used by NASA, performs neutron, proton and heavy ion transport explicitly, but it does not take into account the production and transport of mesons, photons and leptons. In this paper, we present results from the Monte Carlo code MCNPX (Monte Carlo N-Particle eXtended), showing the effect of leptons and mesons when they are produced and transported in a GCR environment.

  8. Study of natural radionuclide and absorbed gamma dose in Ukhimath area of Garhwal Himalaya (India))

    International Nuclear Information System (INIS)

    Natural radiation is the largest contributor to the collective radiation dose of the world population. It is widely distributed in different geological formations such as soil, rocks, air and groundwater. In the present investigation, 226Ra, 232Th and 40K were measured in soil samples of the Ukhimath region of Garhwal Himalaya (India)) using NaI(Tl) gamma-ray spectrometry. The activity concentrations of naturally occurring radionuclides 226Ra, 232Th and 40K were found to vary from 38.4±6.1 to 141.7±11.9 Bq kg-1 with an average of 80.5 Bq kg-1, 57.0±7.5 to 155.9±12.4 Bq kg-1 with an average of 118.9 Bq kg-1 and 9.0±3.0 to 672.8±25.9 Bq kg-1 with an average of 341 Bq kg-1, respectively. The total absorbed gamma dose rate varies from 70.4 to 169.1 nGy h-1 with an average of 123.4 nGy h-1. This study is important to generate a baseline data of radiation exposure in the area. Health hazard effects due to natural radiation exposure are discussed in details. (authors)

  9. Analysis of the Body Distribution of Absorbed Dose in the Organs of Three Species of Fish from Sepetiba Bay

    International Nuclear Information System (INIS)

    The body distribution of Polonium-210 in three fishes from the Sepetiba Bay (Macrodon ancylodon, Micropogonias furnieri and Mugil curema) has been studied under the approach of the Department of Energy of the United States of America (DOE) that set the limit of absorbed dose rate in biota equal to 3.5x103 ?Gy/y, and that also established the relation between dose rate (D) and radionuclide concentration (c) on a fish muscle fresh weight basis, as follows: D = 5.05 ExNxC, assuming that the radionuclide distribution is homogenous among organs. Two hypotheses were tested here, using statistical tools: 1) is the body distribution of absorbed dose homogenous among organs? and 2) is the body distribution of absorbed dose identical among studied fishes? It was concluded, as expected, that the distribution among organs is heterogeneous; but, unexpectedly, that the three fishes display identical body distribution pattern, although they belong to different trophic levels. Hence, concerning absorbed dose calculation, the statement that data distribution is homogenous must be understood merely as an approximation, at least in the case of Polonium-210

  10. Absorbed dose and image quality in examinations of the colon with digital and analogue techniques

    International Nuclear Information System (INIS)

    Purpose: Image quality and the absorbed dose to the patient are issues of primary interest in the change-over from the conventional analogue technique to the digital technique in the examination of the colon by means of fluoroscopy. The aim of this study was to compare the incident radiation and to evaluate the image quality in two different X-ray equipment types, one digital and one analogue. Material and Methods: A kerma-area product meter was used to measure the incident radiation to the patient. Both fluoroscopy and total-examination times were measured as was the number of images. An evaluation of image quality was made and statistically analysed. Results and Conclusion: No significant difference in the irradiation dose was observed between the two techniques. The fluoroscopy time was significantly lower with the conventional technique but the total-examination time decreased by 18% with the digital technique. The total number of images taken was higher with the digital technique (25 images compared to 19) owing to the limited field of the image intensifier. Significantly more noise and less sharpness were observed with the digital system but there was no significant difference in contrast or image quality in the various anatomical structures. Although the change-over to the digital system produced a reduction in sharpness and an increase in noise, and no significant dose saving was measured, the digital system was faster to work with and could well be used for d to work with and could well be used for diagnostic purposes. (orig.)

  11. Absorbed doses received by patients submitted to chest radiographs in hospitals of the city of Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Medical irradiation contributes with a significant amount to the dose received by the population. Here, this contribution was evaluated in a survey of absorbed doses received by patients submitted to chest radiological examinations (postero-anterior (PA) and lateral (LAT) projections) in hospitals of the city of Sao Paulo. Due to the variety of equipment and procedures used in radiological examinations, a selection of hospitals was made (12, totalizing 27 X-ray facilities), taking into account their representativeness as medical institutions in the city, in terms of characteristics and number of radiographs carried out. An anthropomorphic phantom, provided with thermoluminescent dosemeters (TLD-1 00), was irradiated simulating the patient, and the radiographic image quality was evaluated. Absorbed doses were determined to the thoracic region (entrance and exit skin and lung doses), and to some important organs from the radiation protection point of view (lens of the eye, thyroid and gonads). The great variation on the exposure parameters (kV, mA.s, beam size) leads to a large interval of entrance skin doses-ESD (coefficients of variation, CV, of 60% and 76%, for PA and LAT projections, respectively, were found) and of organ doses (CV of 60% and 46%. for thyroid and lung respectively). Mean values of ESD for LAT and PA projections were 0.22 and 0.98 mGy, respectively. The average absorbed doses per exam (PA and LAT) to thyroid and lung, 0.15 and 0.24 mGy respectively,showed that the thyroid was irradiated by the primary beam in many cases. Values of lens of the eye and gonad absorbed doses were below 30 ?Gy. Comparison of the lung doses obtained in this study with values in the literature, calculated by Monte Carlo simulation, showed good agreement. On the other hand, the comparison shows significant differences in the dose values to organs outside the chest region (thyroid, lens of eye and gonads). The effective dose calculated for a chest examination, PA and LAT projections, was 47 ?Sv. An estimate of 5 million for the number of radiological examinations performed annually in Sao Paulo was achieved through information provided by the hospitals and by governmental institutions. Assuming that 40% of them refers to chest radiographs, it is possible to infer that radiological examinations contribute to the annual collective effective dose with 1,600 Sv-man. The large variation found in the dose values indicates that much can be done in order to reduce the patient doses without loss of image quality. In addition, more studies should be conducted for a substantial evaluation of doses received during other types of radiological examinations in Sao Paulo. (author)

  12. Study of the influence of gold particles on the absorbed dose in soft tissue using polymer gel dosimetry

    International Nuclear Information System (INIS)

    The presence of high-Z material adjacent to soft tissue, when submitted to irradiation, enhances locally the absorbed dose in these soft tissues. Such effect occurs due to the outscattering of photoelectrons from the high-Z material. Polymer gel dosimeters have been used to investigate this effect. Analytic calculations to estimate the dose enhancement and Monte Carlo simulations have been performed. Samples containing polymer gel (PG) with 0.005 gAu/gPG and pure polymer gel have been irradiated using an X-rays beam produced by 150 kV, filtered with 4 mm Al and 5 mm Cu, which resulted in an approximately 20% higher absorbed dose in the samples with gold in comparison to those with pure polymer gel. The analytic calculations and the Monte Carlo simulation resulted in a dose enhancement factor of approximately 30%. (author)

  13. OEDIPE, a software for personalized Monte Carlo dosimetry and treatment planning optimization in nuclear medicine: absorbed dose and biologically effective dose considerations

    International Nuclear Information System (INIS)

    For targeted radionuclide therapies, treatment planning usually consists of the administration of standard activities without accounting for the patient-specific activity distribution, pharmacokinetics and dosimetry to organs at risk. The OEDIPE software is a user-friendly interface which has an automation level suitable for performing personalized Monte Carlo 3D dosimetry for diagnostic and therapeutic radionuclide administrations. Mean absorbed doses to regions of interest (ROIs), isodose curves superimposed on a personalized anatomical model of the patient and dose-volume histograms can be extracted from the absorbed dose 3D distribution. Moreover, to account for the differences in radiosensitivity between tumoral and healthy tissues, additional functionalities have been implemented to calculate the 3D distribution of the biologically effective dose (BED), mean BEDs to ROIs, isoBED curves and BED-volume histograms along with the Equivalent Uniform Biologically Effective Dose (EUD) to ROIs. Finally, optimization tools are available for treatment planning optimization using either the absorbed dose or BED distributions. These tools enable one to calculate the maximal injectable activity which meets tolerance criteria to organs at risk for a chosen fractionation protocol. This paper describes the functionalities available in the latest version of the OEDIPE software to perform personalized Monte Carlo dosimetry and treatment planning optimization in targeted radionuclide therapies. (authors)

  14. Absorbed dose to water standards established by water calorimetry at the LNE-LNHB for medium energy X-ray

    International Nuclear Information System (INIS)

    Nowadays, the absorbed dose to water for kilo-voltage X-ray beams is determined from standards in terms of air-kerma by application of international dosimetry protocols. New standards in terms of absorbed dose to water have just been established for these beams at the LNE-LNHB. A specific calorimeter was developed to do measurements at low depth in water, in order to fulfill the reference conditions required by the international dosimetry protocols for medium-energy X-ray. This new calorimeter was used to measure the absorbed dose rate in water at a depth of 2 cm for six medium-energy X-ray reference beams with a tube potential from 80 kV to 300 kV. The relative standard uncertainty obtained on the absorbed dose rate by water calorimetry is lower than 0.8%, whereas the one given by application of protocols based on air kerma is around 2.5%. (authors)

  15. DETERMINATION OF ABSORBED DOSE OF OZONE (O3) IN ANIMALS AND HUMANS USING STABLE ISOTOPE (OXYGEN-18) TRACING

    Science.gov (United States)

    A method for the determination of absorbed dose of ozone (03) in animals and humans using oxygen-18 (18)O as a physiological tracer is presented. The experimental aspects of the method are based on the instantaneous pyrolysis of tissue samples and subsequent conversion of the sam...

  16. Radiation-absorbed doses and energy imparted from panoramic tomography, cephalometric radiography, and occlusal film radiography in children

    International Nuclear Information System (INIS)

    The absorbed doses and energy imparted from radiographic examinations of children, using panoramic tomography (PTG), cephalometric radiography (CPR), and maxillary frontal occlusal overview (FOO), were examined. The absorbed dose at various sites of the head were measured with TL dosimeters in a phantom and in patients. The energy imparted was calculated from measurements of areal exposure using a planparallel ionization chamber. The maximum absorbed doses for panoramic tomography were located around the lateral rotation center, for cephalometric radiography in the left (tube side) parotid region, and for frontal occlusal radiography in the nose. The absorbed doses in the eyes, thyroid gland, and skin are discussed and compared with previous reports and, for the most part, are found to be in agreement. The mean energy imparted from all three examination methods is 5 mJ with about 57 percent from panoramic, 33 percent from cephalometric, and 10 percent from frontal occlusal examinations. The energy imparted from cephalometric radiography can be reduced to about 10 percent with the use of an improved examination technique, leaving panoramic tomography responsible for contributing about 80 percent of the total energy imparted

  17. Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations.

    Science.gov (United States)

    Kim, Sangroh; Yoshizumi, Terry T; Toncheva, Greta; Frush, Donald P; Yin, Fang-Fang

    2010-03-01

    The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board Imager((R)) was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry. PMID:19889800

  18. Estimation of absorbed doses from paediatric cone-beam CT scans: MOSFET measurements and Monte Carlo simulations

    International Nuclear Information System (INIS)

    The purpose of this study was to establish a dose estimation tool with Monte Carlo (MC) simulations. A 5-y-old paediatric anthropomorphic phantom was computed tomography (CT) scanned to create a voxelised phantom and used as an input for the abdominal cone-beam CT in a BEAMnrc/EGSnrc MC system. An X-ray tube model of the Varian On-Board ImagerR was built in the MC system. To validate the model, the absorbed doses at each organ location for standard-dose and low-dose modes were measured in the physical phantom with MOSFET detectors; effective doses were also calculated. In the results, the MC simulations were comparable to the MOSFET measurements. This voxelised phantom approach could produce a more accurate dose estimation than the stylised phantom method. This model can be easily applied to multi-detector CT dosimetry. (authors)

  19. Visible photoluminescence of color centers in LiF crystals for absorbed dose evaluation in clinical dosimetry

    Science.gov (United States)

    Villarreal-Barajas, J. E.; Piccinini, M.; Vincenti, M. A.; Bonfigli, F.; Khan, R. F.; Montereali, R. M.

    2015-04-01

    Among insulating materials, lithium fluoride (LiF) has been successfully used as ionizing radiation dosemeter for more than 60 years. Thermoluminescence (TL) has been the most commonly used reading technique to evaluate the absorbed dose. Lately, optically stimulated luminescence (OSL) of visible emitting color centers (CCs) has also been explored in pure and doped LiF. This work focuses on the experimental behaviour of nominally pure LiF crystals dosemeters for 6 MV x rays at low doses based on photoluminescence (PL) of radiation induced CCs. Polished LiF crystals were irradiated using 6 MV x rays produced by a clinical linear accelerator. The doses (absorbed dose to water) covered the 1-100 Gy range. Optical absorption spectra show stable formation of primary F defects up to a maximum concentration of 2×1016 cm?3, while no significant M absorption band at around 450 nm was detected. On the other hand, under Argon laser excitation at 458 nm, PL spectra of the irradiated LiF crystals clearly exhibited the characteristic F2 and F+3 visible broad emission bands. Their sum intensity is linearly proportional to the absorbed dose in the investigated range. PL integrated intensity was also measured using a conventional fluorescence optical microscope under blue lamp illumination. The relationship between the absorbed dose and the integrated F2 and F+3 PL intensities, represented by the net average pixel number in the optical fluorescence images, is also fairly linear. Even at the low point defect densities obtained at the investigated doses, these preliminary experimental results are encouraging for further investigation of CCs PL in LiF crystals for clinical dosimetry.

  20. Recent improvements in chemical dosimetric protocols for accurate measurements of absorbed dose in pulse radiolysis experiments

    International Nuclear Information System (INIS)

    This report describes recent improvements made in chemical dosimetric protocols for the Radiation and Photochemistry Division LINAC based pulse radiolysis (PR) experiments, keeping into perspective the current objectives and related machine parameters. In PR studies, accurate measure of absorbed dose based on free radicals' chemistry remains the backbone of all quantitative analyses. Therein, for promptness and convenience, precalibrated secondary chemical dosimeters consisting of aqueous solution of either H2 in alkali, (H2/OH-) or ferrocyanide (Fe(CN)64-), or thiocyanate (CNS-) are employed. Concentration of the free radical species produced as a result (e.g. hydrated electron, eaq-, ferricyanide anion, Fe(CN)63- or thiocyanate dimer radical anion, (SCN)2-) following respective set of chemical reactions is monitored. Amongst these the (SCN)2-) system is in use in RPCD since the machine installation in 1987, due to its sensitivity and ease of use. However, it was realized that rapid partial and variable disappearance of the transient (SCN)2-) species may occur prior to its estimation, introducing significant errors in some cases. Such deviations were searched, analyzed and then quantified, first by mapping the specific time-resolved output electron pulse profiles and the microscopic, random energy variations within each. Secondly, by incorporating such physical irregularities into the opposing set of (SCN)2- radical fast formation and decay chemical reactions, detailed time resolved kinetic analyses of the dosimetric reactions were made separately under all possible scenario. This exercise revealed the varied natures and extents of the hidden inaccuracies in different cases, and consequently also allowed their reduction to negligible levels, by their integration with a user-friendly dosimetry software that was developed in-house, resulting in substantial improvements in the measured dose. (author)

  1. Determination of human absorbed dose of 67Ga-DTPA-HCG based on distribution data in Rats

    Directory of Open Access Journals (Sweden)

    Mohamad Reza Khoshdel

    2010-10-01

    Full Text Available Introduction: Radiation dosimetry assessment often commences with measuring pharmaceutical biodistribution in rodents. In our investigation, we used a robust description of organ biodistribution (source organs in dosimetry calculations and whole body activity. In this investigation, we attempted to estimate the radiation absorbed dose to normal organs following i.v. administration of 67Ga-labeled hCG by using biodistribution data in normal rats. Methods: Four animals each were sacrificed at 15, 30, 60, 120, 240 min and 24 hours after injection of 1.2 MBq of radiotracer and exsanguinated, and the percentage of injected dose per gram of each organ were calculated. The Medical Internal Radiation Dose (MIRD formulation was applied to calculate the absorbed radiation dose for various organs. Results: The results show that most of the activity is accumulated in the testes. Nearly all excretion of activity occurred by the renal system, and hepatobiliary excretion was negligible. The testis to blood activity concentration ratio were 5.1 and 15.2 after 3 and 24 hours respectively, while target (testis:muscle ratios were 35 and 40 after 3 and 24 hours. A 185-MBq (5-mCi injection of 67Ga-DTPA-hCG into the human body caused an estimated absorbed dose of 3.52mGy for the total body and the highest absorbed dose was in the testis with 42.5 (mGy and second to the testis were spleen, liver and LLI wall which received 31.4 (mGy, 19.9 (mGy and 8.26 (mGy, respectively. Conclusion: Radiation dosimetry for 67Ga-DTPA-hCG was estimated for humans based on distribution data of 67Ga-DTPA-hCG in normal rats. Previous studies have demonstrated the usefulness of using animal distribution as a model for absorbed dose estimations in humans.The biodistribution of 67Ga-DTPA-hCG showed significant gonadal uptake of the tracer after 240 minutes and high target:muscle and target:blood ratios, allowing for early imaging of the testes anomalies and hCG receptors malignancies.Although further dosimetry work should be performed on humans as 67Ga-DTPA-hCG becomes useful in the clinic, these estimates can be used to predict potential absorbed doses in humans and for planning human studies.

  2. Absorbed dose distributions for X-ray beams and beams of electrons from the Therac 20 Saturne linear accelerator.

    Science.gov (United States)

    Tronc, D; Noël, A

    1978-11-01

    After a brief description of the Therac 20 Saturne linear accelerator a complete set of absorbed-dose distribution values is given. These values define the depths on the axis as a function of the depth dose and define the penumbra (as characterized by the positions of the intersections of the isodose curves with planes parallel to the phantom surface) for beams of X-rays and for beams of electrons. Tissue-maximum ratios are given for beams of X-rays. Analytical values for the electron depth dose curve are compared with the values obtained on the Sagittaire linear accelerator. PMID:715810

  3. Absorbed Dose in Ion Beams: Comparison of Ionization and Fluence-based Measurements

    CERN Document Server

    Osinga, Julia-Maria; Bartz, James A; Akselrod, Mark S; Jäkel, Oliver; Greilich, Steffen

    2013-01-01

    We present a direct comparison measurement of fluorescent nuclear track detectors (FNTDs) and a thimble ionization chamber. Irradiations were performed at the Heidelberg Ion-Beam Therapy Center (HIT) using monoenergetic protons (142.66 MeV, 3x10^6 1/cm2) and carbon ions (270.55 MeV/u, 3x10^6 1/cm2) in the entrance channel of the ion beam. We found that absorbed dose to water values as determined by fluence measurements using FNTDs are in case of protons in good agreement (2.2 %) with ionization chamber measurements when including slower protons and Helium secondaries by an effective stopping power. For carbon, however, we found a discrepancy of 4.6 %. This deviation is significant considering both the uncertainties for ionization chambers as given in the TRS 398 and from experimental design (e.g. inhomogeneous irradiation, machine stability, beam direction). Additionally, the abundance of secondary protons expected from Monte-Carlo transport simulation was not seen.

  4. Evaluation of absorbed dose in respiratory-gated radiotherapy using a phantom system that simulates patient respiration

    International Nuclear Information System (INIS)

    Respiratory-gated (RG) radiotherapy is useful for minimizing the irradiated volume of normal tissues resulting from the shifting of internal structures caused by respiratory movement. In this technique, although improvement in the dose distribution of the target can be expected, the actual absorbed dose distribution is not clearly determined. Therefore, it is important to clarify the absorbed dose at the tumor and at the evaluation points according to the patient's respiration. We have developed a phantom system that simulates patient respiration (TNK Co., Ltd.), to evaluate the absorbed dose and ensure precise RG radiotherapy. Actual patient respiratory signals were obtained using a respiratory synchronization and gating system (AZ-733V, Anzai Medical). The acquired data were then transferred to a phantom system driven by a ball screw to simulate the shifting of internal structures caused by respiratory movement. We measured the absorbed dose using a micro-ionization chamber dosimeter and the dose distribution using the film method for RG irradiation at expiratory phase by using Linac (PRIMUS, Toshiba Medical Systems Corp.) X-rays. When the distance of phantom movement was set to the average patient respiratory movement distance of 1.5 cm, we first compared absorbed dose with RG irradiation with a gating signal of 50% or less, and without RG irradiation. The absorbed dose at the iso-center was improved by 6.0% and 4.4% at a field size of 4 x 4 cm2, and by ield size of 4 x 4 cm2, and by 1.3% and 0.7% at a field size of 5 x 5 cm2 with an X-ray energy of 6 MV and 10 MV, respectively. There was, however, no dose change at a field size of 10 x 10 cm2 and 15 x 15 cm2. When the gating signal was reduced to 25% and 10%, absorbed dose was also improved. With regard to the flatness of the dose profile, no changes in dose distribution were observed in the lateral direction, e.g., beam flatness was within 1.4% and 1.6% at field sizes of 5 x 5 cm2 and 10 x 10 cm2, respectively, with an X-ray energy of 6 MV. In the cranial-caudal direction, the dose profile was relatively large even if a gating signal of 50% was applied, i.e., 8.1% and 10.4% at field sizes of 5 x 5 cm2 and 10 x 10 cm2, respectively. Beam flatness without RG was much worse, i.e., 37.8% and 38.2%, at field sizes of 5 x 5 cm2 and 10 x 10 cm2, respectively. In both cases, the dose was insufficient in the expiratory direction. Although RG radiotherapy is quite useful, the margins in the inspiratory and expiratory phases should be considered based on the level of gating signal and field size in order to formulate appropriate radiotherapy planning in terms of the shifting of internal structures. To ensure accurate radiotherapy, the characteristics of the RG irradiation technique and the radiotherapy equipment must be clearly understood when this technique is to be employed in clinical practice. (author)

  5. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation

    International Nuclear Information System (INIS)

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of 192Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results indicate an under dosage of the target volume of about 20%. (author)

  6. Determination of the Absorbed Dose Rate to Water for the 18-mm Helmet of a Gamma Knife

    International Nuclear Information System (INIS)

    Purpose: To measure the absorbed dose rate to water of 60Co gamma rays of a Gamma Knife Model C using water-filled phantoms (WFP). Methods and Materials: Spherical WFP with an equivalent water depth of 5, 7, 8, and 9 cm were constructed. The dose rates at the center of an 18-mm helmet were measured in an 8-cm WFP (WFP-3) and two plastic phantoms. Two independent measurement systems were used: one was calibrated to an air kerma (Set I) and the other was calibrated to the absorbed dose to water (Set II). The dose rates of WFP-3 and the plastic phantoms were converted to dose rates for an 8-cm water depth using the attenuation coefficient and the equivalent water depths. Results: The dose rate measured at the center of WFP-3 using Set II was 2.2% and 1.0% higher than dose rates measured at the center of the two plastic phantoms. The measured effective attenuation coefficient of Gamma Knife photon beam in WFPs was 0.0621 cm-1. After attenuation correction, the difference between the dose rate at an 8-cm water depth measured in WFP-3 and dose rates in the plastic phantoms was smaller than the uncertainty of the measurements. Conclusions: Systematic errors related to the characteristics of the phantom materials in the dose rate measurement of a Gamma Knife need to be corrected for. Correction of the dose rate using an equivalent water depth and attenuation provided results that were more consistent.

  7. DOSE-Analyzer. A computer program with graphical user interface to analyze absorbed dose inside a body of mouse and human upon external neutron exposure

    International Nuclear Information System (INIS)

    DOSE-Analyzer is a computer program to retrieve the dose information from a database and generate a graph through a graphical user interface (GUI). The database is constructed for absorbed dose, fluence, and energy distribution inside a body of mouse and human exposed upon external neutrons, which is calculated by our developed Monte-Carlo simulation method using voxel-based phantom and particle transport code PHITS. The input configurations of irradiation geometry, subject, and energy are set by GUI. The results are tabulated at particle types, i.e. electron, proton, deuteron, triton, and alpha particle, and target organs on a data sheet of Microsoft Office ExcelTM. Simple analysis to compare the output values for two subjects is also performed on DOSE-Analyzer. This report is a user manual of DOSE-Analyzer. (author)

  8. Influence of thyroid volume reduction on absorbed dose in 131I therapy studied by using Geant4 Monte Carlo simulation

    Science.gov (United States)

    Ziaur, Rahman; Sikander, M. Mirza; Waheed, Arshed; Nasir, M. Mirza; Waheed, Ahmed

    2014-05-01

    A simulation study has been performed to quantify the effect of volume reduction on the thyroid absorbed dose per decay and to investigate the variation of energy deposition per decay due to ?- and ?-activity of 131I with volume/mass of thyroid, for water, ICRP- and ICRU-soft tissue taken as thyroid material. A Monte Carlo model of the thyroid, in the Geant4 radiation transport simulation toolkit was constructed to compute the ?- and ?-absorbed dose in the simulated thyroid phantom for various values of its volume. The effect of the size and shape of the thyroid on energy deposition per decay has also been studied by using spherical, ellipsoidal and cylindrical models for the thyroid and varying its volume in 1-25 cm3 range. The relative differences of Geant4 results for different models with each other and MCNP results lie well below 1.870%. The maximum relative difference among the Geant4 estimated results for water with ICRP and ICRU soft tissues is not more than 0.225%. S-values for ellipsoidal, spherical and cylindrical thyroid models were estimated and the relative difference with published results lies within 3.095%. The absorbed fraction values for beta particles show a good agreement with published values within 2.105% deviation. The Geant4 based simulation results of absorbed fractions for gammas again show a good agreement with the corresponding MCNP and EGS4 results (±6.667%) but have 29.032% higher values than that of MIRD calculated values. Consistent with previous studies, the reduction of the thyroid volume is found to have a substantial effect on the absorbed dose. Geant4 simulations confirm dose dependence on the volume/mass of thyroid in agreement with MCNP and EGS4 computed values but are substantially different from MIRD8 data. Therefore, inclusion of size/mass dependence is indicated for 131I radiotherapy of the thyroid.

  9. Characterization of an absorbed dose standard in water through ionometric methods

    International Nuclear Information System (INIS)

    In this work the unit of absorbed dose at the Secondary Standard Dosimetry Laboratory (SSDL) of Mexico, is characterized by means of the development of a primary standard of absorbed dose to water, Dagua. The main purpose is to diminish the uncertainty in the service of dosimetric calibration of ionization chambers (employed in radiotherapy of extemal beams) that offers this laboratory. This thesis is composed of seven chapters: In Chapter 1 the position and justification of the problem is described, as well as the general and specific objectives. In Chapter 2, a presentation of the main quantities and units used in dosimetry is made, in accordance with the recommendations of the International Commission on Radiation Units and Measurements (ICRU) that establish the necessity to have a coherent system with the international system of units and dosimetric quantities. The concepts of equilibrium and transient equilibrium of charged particles (TCPE) are also presented, which are used later in the quantitative determination of Dagua. Finally, since the proposed standard of Dagua is of ionometric type, an explanation of the Bragg-Gray and Spencer-Attix cavity theories is made. These theories are the foundation of this type of standards. On the other hand, to guarantee the complete validity of the conditions demanded by these theories it is necessary to introduce correction factors. These factors are determined in Chapters 5 and 6. Since for the calculation of the correction factors Monte Carlo (MC) method is used in an important way, in Chapter 3 the fundamental concepts of this method are presented; in particular the principles of the code MCNP4C [Briesmeister 2000] are detailed, making emphasis on the basis of electron transport and variance reduction techniques used in this thesis. Because a phenomenological approach is carried out in the development of the standard of Dagua, in Chapter 4 the characteristics of the Picker C/9 unit, the ionization chamber type CC01, series 131, built by Osterreichisches Forschungszentrum Seibersdorf, and the experimental conditions are shown. The characteristics of the complementary instrumentation employed in the experimental part of the work, are also presented. In Chapter 5, two ionometric methods for the calculation of the correction factors are presented: that of the Bureau International des Poids et Mesures (BIPM) and that of the International Atomic Energy Agency (IAEA). In the BIPM method emphasis is made in the MC simulation of the spectral fluence of the photons that emits the unit (using a realistic geometry and an equivalent one) as well as its validation by means of the air-kerma output factors and the percent depth doses in water, with the aid of the condition of TCPE that apply to the CC01-131 chamber. In particular, it is presented how the factor kcav is determined, employing MC simulation of two positions of the chamber (with the chamber axis parallel or perpendicular to the beam axis), and by means of a semi-analytic approach that uses the energy dissipation functions of Spencer for the parallel position. Finally the factor kp is determined for both orientations. In the case of the IAEA method, the expressions of the correction factors in the protocols TRS-277 and TRS-398 are shown. Chapter 6 presents results and discussion, and Chapter 7 presents conclusions and recommendations. In Chapter 6, the protocol of the BIPM/ISO/TAG [ISO 1992] for the calculation of the uncertainties is detailed, later the results and its discussion is made. The main conclusion obtained of these results is that the value of the Dagua and its U for the BIPM method is bigger than that for the IAEA method. This conclusion has at least three meanings: First: The correction factors calculated using the BIPM method are overestimated, regarding the IAEA method. Second: The possible overestimation is consistent with the order of uncertainty with which are calculated, that is with the infrastructure that at the moment the SSDL-Mexico possesses to carry out the unit of absorbed dose to water (instrumentatio

  10. Fast neutron absorbed dose distributions in the energy range 0.5-80 MeV - a Monte Carlo study

    International Nuclear Information System (INIS)

    Neutron pencil-beam absorbed dose distributions in phantoms of bone, ICRU soft tissue, muscle, adipose and the tissue substitutes water, A-150 (plastic) and PMMA (acrylic) have been calculated using the Monte Carlo code FLUKA in the energy range 0.5 to 80 MeV. For neutrons of energies ?20 MeV, the results were compared to those obtained using the Monte Carlo code MCNP4B. Broad-beam depth doses and lateral dose distributions were derived. Broad-beam dose distributions in various materials were compared using two kinds of scaling factor: a depth-scaling factor and a dose-scaling factor. Build-up factors due to scattered neutrons and photons were derived and the appropriate choice of phantom material for determining dose distributions in soft tissue examined. Water was found to be a good substitute for soft tissue even at neutron energies as high as 80 MeV. The relative absorbed doses due to photons ranged from 2% to 15% for neutron energies 10-80 MeV depending on phantom material and depth. For neutron energies below 10 MeV the depth dose distributions derived with MCNP4B and FLUKA differed significantly, the difference being probably due to the use of multigroup transport of low energy (20 MeV, MCNP4B fails to describe dose build-up at the phantom interface and penumbra at the edge of the beam because it does not transport secondary charged particles. The penurt secondary charged particles. The penumbra width, defined as the distance between the 80% and 20% iso-dose levels at 5 cm depth and for a 10x10 cm2 field, was between 0.9 mm and 7.2 mm for neutron energies 10-80 MeV. (author)

  11. Fast neutron absorbed dose distributions in the energy range 0.5-80 MeV - a Monte Carlo study

    Energy Technology Data Exchange (ETDEWEB)

    Soederberg, Jonas [Department of Radiation Physics, IMV, Faculty of Health Sciences, Linkoeping University, SE-581 85 Linkoeping (Sweden). E-mail: jonas.soderberg at imv.liu.se; Carlsson, Gudrun Alm [Department of Radiation Physics, IMV, Faculty of Health Sciences, Linkoeping University, SE-581 85 Linkoeping (Sweden)

    2000-10-01

    Neutron pencil-beam absorbed dose distributions in phantoms of bone, ICRU soft tissue, muscle, adipose and the tissue substitutes water, A-150 (plastic) and PMMA (acrylic) have been calculated using the Monte Carlo code FLUKA in the energy range 0.5 to 80 MeV. For neutrons of energies {<=}20 MeV, the results were compared to those obtained using the Monte Carlo code MCNP4B. Broad-beam depth doses and lateral dose distributions were derived. Broad-beam dose distributions in various materials were compared using two kinds of scaling factor: a depth-scaling factor and a dose-scaling factor. Build-up factors due to scattered neutrons and photons were derived and the appropriate choice of phantom material for determining dose distributions in soft tissue examined. Water was found to be a good substitute for soft tissue even at neutron energies as high as 80 MeV. The relative absorbed doses due to photons ranged from 2% to 15% for neutron energies 10-80 MeV depending on phantom material and depth. For neutron energies below 10 MeV the depth dose distributions derived with MCNP4B and FLUKA differed significantly, the difference being probably due to the use of multigroup transport of low energy (<19.6 MeV) neutrons in FLUKA. Agreement improved with increasing neutron energies up to 20 MeV. At energies >20 MeV, MCNP4B fails to describe dose build-up at the phantom interface and penumbra at the edge of the beam because it does not transport secondary charged particles. The penumbra width, defined as the distance between the 80% and 20% iso-dose levels at 5 cm depth and for a 10x10 cm{sup 2} field, was between 0.9 mm and 7.2 mm for neutron energies 10-80 MeV. (author)

  12. Boron neutron capture therapy (BNCT) for malignant melanoma with special reference to absorbed doses to the normal skin and tumor

    International Nuclear Information System (INIS)

    Twenty-two patients with malignant melanoma were treated with boron neutron capture therapy (BNCT) using 10B-p-boronophenylalanine (BPA). The estimation of absorbed dose and optimization of treatment dose based on the pharmacokinetics of BPA in melanoma patients is described. The doses of ?-rays were measured using small TLDs of Mg2SiU4 (Tb) and thermal neutron fluence was measured using gold foil and wire. The total absorbed dose to the tissue from BNCT was obtained by summing the primary and capture ?-ray doses and the high LET radiation doses from 10B(n,a)7Li and 14N(n,p)14C reactions. The key point of the dose optimization is that the skin surrounding the tumour is always irradiated to 18 Gy-Eq, which is the maximum tolerable dose to the skin, regardless of the 10B-concentration in the tumor. The neutron fluence was optimized as follows. (1) The 10B concentration in the blood was measured 15-40 min after the start of neutron irradiation. The 10B-concentration in the skin was estimated by multiplying the blood 10B value by a factor of 1.3. The neutron fluence was calculated. Absorbed doses to the skin ranged from 15.7 to 37.1 Gy-Eq. Among the patients, 16 out of 22 patients exhibited tolerable skin damage. Although six patients showed skin damage that exceeded the tolerance level, three of them could be cured within a few months after BNCT and the remaining three dehs after BNCT and the remaining three developed severe skin damage requiring skin grafts. The absorbed doses to the tumor ranged from 15.7 to 68.5 Gy-Eq and the percentage of complete response was 73% (16/22). When BNCT is used in the treatment of malignant melanoma, based on the pharmacokinetics of BPA and radiobiological considerations, promising clinical results have been obtained, although many problems and issues remain to be solved. Copyright (2003) Australasian College of Physical Scientists and Engineers in Medicine

  13. Comparison of measurements of absorbed dose to water using a water calorimeter and ionization chambers for clinical radiotherapy photon and electron beams

    International Nuclear Information System (INIS)

    With the development of the water calorimeter direct measurement of absorbed dose in water becomes possible. This could lead to the establishment of an absorbed dose rather than an exposure related standard for ionization chambers for high energy electrons and photons. In changing to an absorbed dose standard it is necessary to investigate the effect of different parameters, among which are the energy dependence, the air volume, wall thickness and material of the chamber. The effect of these parameters is experimentally studied and presented for several commercially available chambers and one experimental chamber, for photons up to 25 MV and electrons up to 20 MeV, using a water calorimeter as the absorbed dose standard and the most recent formalism to calculate the absorbed dose with ion chambers. For electron beams, the dose measured with the calorimeter was 1% lower than the dose calculated with the chambers, independent of beam energy and chamber. For photon beams, the absorbed dose measured with the calorimeter was 3.8% higher than the absorbed dose calculated from the chamber readings. Such differences were found to be chamber and energy independent. The results for the photons were found to be statistically different from the results with the electron beams. Such difference could not be attributed to a difference in the calorimeter response

  14. Study of the formalism used to determine the absorbed dose for low-energy x-ray beams

    Energy Technology Data Exchange (ETDEWEB)

    Chica, U; Anguiano, M; Lallena, A M [Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Granada, E-18071 Granada (Spain)], E-mail: ur1ch2@correo.ugr.es, E-mail: mangui@ugr.es, E-mail: lallena@ugr.es

    2008-12-07

    We have studied the procedure commonly recommended by dosimetry protocols for the determination of the absorbed dose in water for low-energy x-rays beams, generated with potentials up to 150 kVp. X-ray beams with different spectra obtained with the XCOMP5R code were transported using the Monte Carlo code PENELOPE in order to calculate backscatter factors and mass-energy absorption coefficients. We have analyzed the uncertainty in the absorbed doses, calculated using the half-value layer to characterize the x-ray beams, due to the uncertainties in both backscatter factors and mass-energy absorption coefficients. We have found that this uncertainty is larger than 5% and can reach values above 11% for some HVL{sub 1} values. The characterization of these doses with the homogeneity coefficient or the generating potential, in addition to the half-value layer is also studied. Using HVL{sub 1} and the kVp, the absorbed dose to water can be reproduced to within 3% for all spectra.

  15. Study of the formalism used to determine the absorbed dose for low-energy x-ray beams

    Science.gov (United States)

    Chica, U.; Anguiano, M.; Lallena, A. M.

    2008-12-01

    We have studied the procedure commonly recommended by dosimetry protocols for the determination of the absorbed dose in water for low-energy x-rays beams, generated with potentials up to 150 kVp. X-ray beams with different spectra obtained with the XCOMP5R code were transported using the Monte Carlo code PENELOPE in order to calculate backscatter factors and mass-energy absorption coefficients. We have analyzed the uncertainty in the absorbed doses, calculated using the half-value layer to characterize the x-ray beams, due to the uncertainties in both backscatter factors and mass-energy absorption coefficients. We have found that this uncertainty is larger than 5% and can reach values above 11% for some HVL1 values. The characterization of these doses with the homogeneity coefficient or the generating potential, in addition to the half-value layer is also studied. Using HVL1 and the kVp, the absorbed dose to water can be reproduced to within 3% for all spectra.

  16. The absorbed dose in air of photons generated from secondary cosmic rays at sea level at Nagoya, Japan

    International Nuclear Information System (INIS)

    Investigations have been carried out to determine the absorbed dose in air of photons generated from secondary cosmic radiation at sea level at Nagoya, Japan. To isolate the contribution from cosmic photons, the pulse-height distributions due to ? particles and electrons were eliminated from the observed pulse-height distribution of a measurement with a 3'' diam. spherical NaI(Tl) detector. The pulse height due to ? particles and electrons was inferred from the coincidence technique using two types of scintillation detectors with different sensitivities to photons. To obtain the photon fluence rate for further dose calculation, the pulse-height distribution of cosmic photons was unfolded by the iterative method. The mean and its standard deviation of the absorbed dose in air and fluence rate due to cosmic photons calculated from a one year observation are 2.86±0.05 nGy.h-1 and 0.1342±0.0015 photons.cm-2.s-1, respectively. The absorbed dose in air from cosmic photons was 0.5% lower during autumn to winter and 0.6% higher during spring to summer than the mean taken over the year. (author)

  17. Development of standardized methods to verify absorbed dose of irradiated fresh and dried fruits, tree nuts in trade

    International Nuclear Information System (INIS)

    Investigations were carried out on standardization of desired process control parameters such as dose distribution in trade containers, container standardization and development of 'label' dosimeters. A prototype 'label' dose indicators Sterins for threshold doses of 125 Gy and 300 Gy was studied. Dose distribution was studied using fresh fruits and tree nuts in trade and standardized containers with varying product densities. The distribution of absorbed doses was measured by Fricke, Gammachrome YR, clear Polymethylmethacrylate (PMMA), EthanolChlorobenzene (ECB) and Sterin 300. These values are given as Dmax/Dmin ratios in relation to product bulk densities. It was observed that bulk densities varied greatly among different products depending on the types of fruits, containers and pattern of loading which also affected dose distribution. Dmax/Dmin obtained by proper dose mapping could be kept low by arranging proper irradiation conditions which ensured uniform dose distribution. Prototype 'label' dose indicators like Sterins and clear PMMA were used for dose mapping along with the standard primary and secondary dosimeters. Sterins and clear PMMA were also studied for their dosimetric properties, particularly for use in label dosimetry. Sterins 125 and 300 evaluated visually showed their integrity at their threshold doses. The word NOT on Sterin 125 eclipsed after 115 Gy and on Sterin 300 after 270 Gy dose. Clear PMMA samples of 410 mm thickness irradiated at 200-1000 Gy showed linear response and had postirradiation stability for over a month storage at normal temperatures (21-35 deg. C) and humidities. These could be investigated further for developing as 'label' dosimeters in insect control quarantine treatment. Other low dose indicators studied such as coloured perspex, dye solutions were not found useful at quarantine dose levels. Further investigations are required for developing a 'label' dosimeter for commercial use. (author)

  18. Renal function affects absorbed dose to the kidneys and haematological toxicity during 177Lu-DOTATATE treatment

    International Nuclear Information System (INIS)

    Peptide receptor radionuclide therapy (PRRT) has become an important treatment option in the management of advanced neuroendocrine tumours. Long-lasting responses are reported for a majority of treated patients, with good tolerability and a favourable impact on quality of life. The treatment is usually limited by the cumulative absorbed dose to the kidneys, where the radiopharmaceutical is reabsorbed and retained, or by evident haematological toxicity. The aim of this study was to evaluate how renal function affects (1) absorbed dose to the kidneys, and (2) the development of haematological toxicity during PRRT treatment. The study included 51 patients with an advanced neuroendocrine tumour who received 177Lu-DOTATATE treatment during 2006 - 2011 at Sahlgrenska University Hospital in Gothenburg. An average activity of 7.5 GBq (3.5 - 8.2 GBq) was given at intervals of 6 - 8 weeks on one to five occasions. Patient baseline characteristics according to renal and bone marrow function, tumour burden and medical history including prior treatment were recorded. Renal and bone marrow function were then monitored during treatment. Renal dosimetry was performed according to the conjugate view method, and the residence time for the radiopharmaceutical in the whole body was calculated. A significant correlation between inferior renal function before treatment and higher received renal absorbed dose per administered activity was found (p < 0.01). Patients with inferior renal function also experienced a higher grade of haematological toxicity during treatment (p = 0.01). The residence time of 177Lu in the whole body (range 0.89 - 3.0 days) was correlated with grade of haematological toxicity (p = 0.04) but not with renal absorbed dose (p = 0.53). Patients with inferior renal function were exposed to higher renal absorbed dose per administered activity and developed a higher grade of haematological toxicity during 177Lu-DOTATATE treatment. The study confirms the tolerability of PRRT in patients with an advanced neuroendocrine tumour but indicates that patients with inferior renal function are at risk of being exposed to higher absorbed doses to normal tissue on treatment. (orig.)

  19. Evaluation of the absorbed dose of the thyroid gland in conventional spiral and spiral computed tomography techniques

    Directory of Open Access Journals (Sweden)

    Hamid Badrian

    2012-01-01

    Full Text Available AbstractIntroduction: The use of sophisticated radiographic techniques is absolutely necessary in dentistry. The use of these techniques exposes the sensitive organs of head and neck to x-rays. The aim of the present study was to investigate the absorbed dose of the thyroid gland in conventional spiral and spiral computed tomography techniques. Materials and Methods: In this experimental study, 10 TLD GR-200 circular dosimeters (Thermoluminans Detector were used in male RANDO-like phantom (head and neck segment, i.e. the first 10 segments in order to determine the radiation dose absorbed by the thyroid gland. Then spiral computed tomographies were provided from the anterior and posterior regions of the maxilla and mandible along with a lateral Scout view as a guide. Conventional spiral tomographies were prepared from the maxilla, mandible and both jaws with a panoramic radiograph as a guide. Data was analyzed using Kruskal-Wallis and Mann-Whitney tests using SPSS 11.5 (a = 0.05. Results: The highest and lowest thyroid gland absorbed doses were observed with computed tomography of both jaws and conventional spiral tomography of the anterior maxilla, respectively (5.92 ± 0.01 and 0.79 ± 0.01 mSiv. The mean amount of the absorbed dose by the thyroid gland was lower in the conventional spiral tomography compared to computed tomography. The two techniques revealed significant differences in the absorbed doses except for conventional spiral tomography in the posterior and anterior regions of the mandible (p value = 0.276.Conclusion: According to results of the present study, the absorbed dose of the thyroid gland in the conventional spiral tomography in different regions of the jaws was less than CT scan techniques. As a result, it appears the use of conventional spiral tomography is preferred over CT scans in limited regions where three-dimensional and cross-sectional views are required.Key words: Thyroid gland, Film dosimetry, Spiral Computed Tomography.

  20. Renal function affects absorbed dose to the kidneys and haematological toxicity during {sup 177}Lu-DOTATATE treatment

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, Johanna; Berg, Gertrud [Sahlgrenska University Hospital, Department of Oncology, Goeteborg (Sweden); Waengberg, Bo [Sahlgrenska University Hospital, Department of Surgery, Goeteborg (Sweden); Larsson, Maria [University of Gothenburg, Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy, Goeteborg (Sweden); Forssell-Aronsson, Eva; Bernhardt, Peter [University of Gothenburg, Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy, Goeteborg (Sweden); Sahlgrenska University Hospital, Department of Medical Physics and Medical Bioengineering, Goeteborg (Sweden)

    2015-05-01

    Peptide receptor radionuclide therapy (PRRT) has become an important treatment option in the management of advanced neuroendocrine tumours. Long-lasting responses are reported for a majority of treated patients, with good tolerability and a favourable impact on quality of life. The treatment is usually limited by the cumulative absorbed dose to the kidneys, where the radiopharmaceutical is reabsorbed and retained, or by evident haematological toxicity. The aim of this study was to evaluate how renal function affects (1) absorbed dose to the kidneys, and (2) the development of haematological toxicity during PRRT treatment. The study included 51 patients with an advanced neuroendocrine tumour who received {sup 177}Lu-DOTATATE treatment during 2006 - 2011 at Sahlgrenska University Hospital in Gothenburg. An average activity of 7.5 GBq (3.5 - 8.2 GBq) was given at intervals of 6 - 8 weeks on one to five occasions. Patient baseline characteristics according to renal and bone marrow function, tumour burden and medical history including prior treatment were recorded. Renal and bone marrow function were then monitored during treatment. Renal dosimetry was performed according to the conjugate view method, and the residence time for the radiopharmaceutical in the whole body was calculated. A significant correlation between inferior renal function before treatment and higher received renal absorbed dose per administered activity was found (p < 0.01). Patients with inferior renal function also experienced a higher grade of haematological toxicity during treatment (p = 0.01). The residence time of {sup 177}Lu in the whole body (range 0.89 - 3.0 days) was correlated with grade of haematological toxicity (p = 0.04) but not with renal absorbed dose (p = 0.53). Patients with inferior renal function were exposed to higher renal absorbed dose per administered activity and developed a higher grade of haematological toxicity during {sup 177}Lu-DOTATATE treatment. The study confirms the tolerability of PRRT in patients with an advanced neuroendocrine tumour but indicates that patients with inferior renal function are at risk of being exposed to higher absorbed doses to normal tissue on treatment. (orig.)

  1. Estimation of kidney depth effective renal plasmatic flux and absorbed dose, from a radio isotopic renogram

    International Nuclear Information System (INIS)

    A technique for the estimation of kidney depth is described. It is based on a comparison between the measurements obtained in a radioisotopic renogram carried out for two specific energies and the same measurements made with a phanto-kidney at different depths. Experiments performed with kidney and abdomen phantoms provide calibration curves which are obtained by plotting the photopeak to scatter ratio for 131I pulse height spectrum against depth. Through this technique it is possible to obtain the Hippuran-131I kidney uptake with external measurements only. In fact it introduces a correction in the measurements for the depth itself and for the attenuation and scattering effects due to the tissues interposed between the kidney and the detector. When the two kidneys are not equidistant from the detector, their respective renograms are different and it is therefore very important to introduce a correction to the measurements according to the organ depth in order to obtain the exact information on Hippuran partition between the kidneys. The significative influence of the extrarenal activity is analyzed in the renogram by monitoring the praecordial region after 131I-human serum albumin injection and establishing a calibration factor relating the radioactivity level of this area to that present in each kidney area. It is shown that it is possible to obtain the values for the clearance of each kidney from the renogram once the alteration in efficiency due to the organ depth and to non-renal tissue interference in the renal area is considered. This way, values for the effective renal plasma flow were obtained, which are comparable to those obtained with other techniques, estimating the total flow of the kidneys. Finally the mean absorbed dose of the kidneys in a renography is also estimated. (Author)

  2. {sup 99m}Tc-MAA overestimates the absorbed dose to the lungs in radioembolization: a quantitative evaluation in patients treated with {sup 166}Ho-microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Elschot, Mattijs; Nijsen, Johannes F.W.; Lam, Marnix G.E.H.; Smits, Maarten L.J.; Prince, Jip F.; Bosch, Maurice A.A.J. van den; Zonnenberg, Bernard A.; Jong, Hugo W.A.M. de [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine, Utrecht (Netherlands); Viergever, Max A. [University Medical Center Utrecht, Department of Radiology and Nuclear Medicine, Utrecht (Netherlands); University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands)

    2014-10-15

    Radiation pneumonitis is a rare but serious complication of radioembolic therapy of liver tumours. Estimation of the mean absorbed dose to the lungs based on pretreatment diagnostic {sup 99m}Tc-macroaggregated albumin ({sup 99m}Tc-MAA) imaging should prevent this, with administered activities adjusted accordingly. The accuracy of {sup 99m}Tc-MAA-based lung absorbed dose estimates was evaluated and compared to absorbed dose estimates based on pretreatment diagnostic {sup 166}Ho-microsphere imaging and to the actual lung absorbed doses after {sup 166}Ho radioembolization. This prospective clinical study included 14 patients with chemorefractory, unresectable liver metastases treated with {sup 166}Ho radioembolization. {sup 99m}Tc-MAA-based and {sup 166}Ho-microsphere-based estimation of lung absorbed doses was performed on pretreatment diagnostic planar scintigraphic and SPECT/CT images. The clinical analysis was preceded by an anthropomorphic torso phantom study with simulated lung shunt fractions of 0 to 30 % to determine the accuracy of the image-based lung absorbed dose estimates after {sup 166}Ho radioembolization. In the phantom study, {sup 166}Ho SPECT/CT-based lung absorbed dose estimates were more accurate (absolute error range 0.1 to -4.4 Gy) than {sup 166}Ho planar scintigraphy-based lung absorbed dose estimates (absolute error range 9.5 to 12.1 Gy). Clinically, the actual median lung absorbed dose was 0.02 Gy (range 0.0 to 0.7 Gy) based on posttreatment {sup 166}Ho-microsphere SPECT/CT imaging. Lung absorbed doses estimated on the basis of pretreatment diagnostic {sup 166}Ho-microsphere SPECT/CT imaging (median 0.02 Gy, range 0.0 to 0.4 Gy) were significantly better predictors of the actual lung absorbed doses than doses estimated on the basis of {sup 166}Ho-microsphere planar scintigraphy (median 10.4 Gy, range 4.0 to 17.3 Gy; p < 0.001), {sup 99m}Tc-MAA SPECT/CT imaging (median 2.5 Gy, range 1.2 to 12.3 Gy; p < 0.001), and {sup 99m}Tc-MAA planar scintigraphy (median 5.5 Gy, range 2.3 to 18.2 Gy; p < 0.001). In clinical practice, lung absorbed doses are significantly overestimated by pretreatment diagnostic {sup 99m}Tc-MAA imaging. Pretreatment diagnostic {sup 166}Ho-microsphere SPECT/CT imaging accurately predicts lung absorbed doses after {sup 166}Ho radioembolization. (orig.)

  3. Incase of Same Region Treatment by using a Tomotherapy and a Linear Accelerator Absorbed Dose Evaluation of Normal Tissues and a Tumor

    Energy Technology Data Exchange (ETDEWEB)

    Cheon, Geum Seong; Kim, Chang Uk; Kim, Hoi Nam; Heo, Gyeong Hun; Song, Jin Ho; Hong, Joo Yeong [Dept. of Radiation Oncology, Catholic University Seoul St. Mary' s Hospital, Seoul (Korea, Republic of); Jeong, Jae Yong [Dept. of Radiation Oncology, Inje University Sanggye Paik Hospital, Seoul (Korea, Republic of)

    2010-09-15

    Treating same region with different modalities there is a limit to evaluate the total absorbed dose of normal tissues. The reason is that it does not support to communication each modalities yet. In this article, it evaluates absorbed dose of the patients who had been treated same region by a tomotherapy and a linear accelerator. After reconstructing anatomic structure with a anthropomorphic phantom, administrate 45 Gy to a tumor in linac plan system as well as prescribe 15 Gy in tomotherapy plan system for make an ideal treatment plan. After the plan which made by tomoplan system transfers to the oncentra plan system for reproduce plan under the same condition and realize total treatment plan with summation 45 Gy linac treatment plan. To evaluate the absorbed dose of two different modalities, do a comparative study both a simple summation dose values and integration dose values. Then compare and analyze absorbed dose of normal tissues and a tumor with the patients who had been exposured radiation by above two different modalities. The result of compared data, in case of minimum dose, there are big different dose values in spleen (12.4%). On the other hand, in case of the maximum dose, it reports big different in a small bowel (10.2%) and a cord (5.8%) in head and neck cancer patients, there presents that oral (20.3%), right lens (7.7%) in minimum dose value. About maximum dose, it represents that spinal (22.5), brain stem (12%), optic chiasm (8.9%), Rt lens (11.5%), mandible (8.1%), pituitary gland (6.2%). In case of Rt abdominal cancer patients, there represents big different minimum dose as Lt kidney (20.3%), stomach (8.1%) about pelvic cancer patients, it reports there are big different in minimum dose as a bladder (15.2%) as well as big different value in maximum dose as a small bowel (5.6%), a bladder (5.5%) in addition, making treatment plan it is able us to get. In case of comparing both simple summation absorbed dose and integration absorbed dose, the minimum dose are represented higher as well as the maximum dose come out lower and the average dose are revealed similar with our expected values data. It is able to evaluate tumor and normal tissue absorbed dose which could had been not realized by treatment plan system. The DVH of interesting region are prescribed lower dose than expected. From now on, it needs to develop the new modality which are able to realize exact dose distribution as well as integration absorbed dose evaluation in same treatment region with different modalities.

  4. Absorbed dose beam quality factors for cylindrical ion chambers: Experimental determination at 6 and 15 MV photon beams

    International Nuclear Information System (INIS)

    Ion chambers calibrated in terms of absorbed dose to water need an additional factor conventionally designed by kQ in order to determine the absorbed dose. The quantity kQ depends on beam quality and chamber characteristics. Rogers and Andreo provided calculations of the kQ factors for most commercially available ionization chambers for clinical dosimetry. Experimental determinations of the kQ factors for a number of cylindrical ion chambers have been made and are compared with the calculated values so far published. Measurements were made at 6 MV and 15 MV clinical photon beams at a point in water phantom where the ion chambers and a Fricke dosimeter were alternatively irradiated. The uncertainty on the experimental kQ factors resulted about ± 0.6%. The theoretical and experimental kQ values are in fairly good agreement. (author). 12 refs, 3 tabs

  5. The Effects on Absorbed Dose Distribution in Intraoral X-ray Imaging When Using Tube Voltages of 60 and 70 kV for Bitewing Imaging

    OpenAIRE

    Kristina Hellén-Halme; Mats Nilsson

    2013-01-01

    Objectives: Efforts are made in radiographic examinations to obtain the best image quality with the lowest possible absorbed dose to the patient. In dental radiography, the absorbed dose to patients is very low, but exposures are relatively frequent. It has been suggested that frequent low-dose exposures can pose a risk for development of future cancer. It has previously been reported that there was no significant difference in the diagnostic accuracy of approximal carious lesions in radiogra...

  6. Analyse of the international recommendations on the calculation of absorbed dose in the biota; Analise das recomendacoes internacionais sobre calculo de dose absorvida na biota

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de S.; Py Junior, Delcy de A., E-mail: wspereira@inb.gov.b, E-mail: delcy@inb.gov.b [Industrias Nucleares do Brasil (UTM/INB), Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerios; Universidade Federal Fluminense (LARARA/UFF), Niteroi, RJ (Brazil). Lab. de Radiobiologia e Radiometria; Kelecom, Alphonse [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Ciencia Ambiental

    2011-10-26

    This paper evaluates the recommendations of ICRP which has as objective the environmental radioprotection. It was analysed the recommendations 26, 60, 91, 103 and 108 of the ICRP. The ICRP-103 defined the concept of animal and plant of reference (APR) to be used in the RAP based on the calculation of absorbed dose based on APR concept. This last view allows to build a legal framework of environmental protection with a etic, moral and scientific visualization, more defensible than the anthropomorphic concept

  7. The choice of anti-scatter grids in diagnostic radiology : the optimization of image quality and absorbed dose

    OpenAIRE

    Sandborg, Michael; Dance, David R.; Alm Carlsson, Gudrun; Persliden, Jan

    1993-01-01

    A Monte Carlo model is developed to study and optimise the design of antiscatter grids in diagnostic radiology. The imaging chain including X-ray energy spectra, phantom (representing the patient), grid and image receptor is simulated. Image quality is quantified in terms of contrast (conventionai screen-film imaging) and signal-to-noise ratio, SNR (digital imaging) and the radiation detriment to the patient (risk) by the mean absorbed dose in the phantom. The advantages of using fibre instea...

  8. Measurement of patient skin absorbed dose in ablation of paroxysmal atrial fibrillation, and examination of treatment protocol

    International Nuclear Information System (INIS)

    The ablation for atrial fibrillation minute movement done in our hospital is 250 minutes or less, within an average time of 150 minutes during a fluoroscopic time of about 7 hours, with very large average inspection times numerical values. However, the skin-absorbed dose could be understood only from the numerical value of the area dosimeter. It was considered that the total dose that reached the threshold was sufficient, although radiation injury would not be reported from the ablation currently done at our hospital. Therefore, we aimed to examine the inspection protocol in this hospital, and to request the patient be given an inspection dose that was the average skin-absorbed dose by using the acryl board. The amount of a total dose for an inspection of 150 minutes of fluoroscopic time was about 2.7 Gy. Moreover, a value of 1.5 Gy was indicated in the hot spot as a result of repetition in some exposure fields. However, it was thought that the possibility of exceeding the threshold of 2 Gy depending on the inspection situation in the future and other factors was tolerable because these measurements were done so as not to overvalue it more than the necessary. (author)

  9. Mean Absorbed Dose to the Anal-Sphincter Region and Fecal Leakage among Irradiated Prostate Cancer Survivors

    International Nuclear Information System (INIS)

    Purpose: To supplement previous findings that the absorbed dose of ionizing radiation to the anal sphincter or lower rectum affects the occurrence of fecal leakage among irradiated prostate-cancer survivors. We also wanted to determine whether anatomically defining the anal-sphincter region as the organ at risk could increase the degree of evidence underlying clinical guidelines for restriction doses to eliminate this excess risk. Methods and Materials: We identified 985 men irradiated for prostate cancer between 1993 and 2006. In 2008, we assessed long-term gastrointestinal symptoms among these men using a study-specific questionnaire. We restrict the analysis to the 414 men who had been treated with external beam radiation therapy only (no brachytherapy) to a total dose of 70 Gy in 2-Gy daily fractions to the prostate or postoperative prostatic region. On reconstructed original radiation therapy dose plans, we delineated the anal-sphincter region as an organ at risk. Results: We found that the prevalence of long-term fecal leakage at least once per month was strongly correlated with the mean dose to the anal-sphincter region. Examining different dose intervals, we found a large increase at 40 Gy; ?40 Gy compared with <40 Gy gave a prevalence ratio of 3.8 (95% confidence interval 1.6-8.6). Conclusions: This long-term study shows that mean absorbed dose to the anal-sphincter region is associated with the occurrence of long-term fecal leakage among irradiated prostatm fecal leakage among irradiated prostate-cancer survivors; delineating the anal-sphincter region separately from the rectum and applying a restriction of a mean dose <40 Gy will, according to our data, reduce the risk considerably.

  10. Evaluation of natural gamma radiation and absorbed gamma dose in soil and rocks of Perambalur district (Tamil Nadu, India)

    International Nuclear Information System (INIS)

    The activity concentrations and absorbed gamma dose of primordial radionuclides 238U, 232Th and 40K were determined employing ?-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg-1 for 238U, 66 Bq kg-1 for 232Th and 340.3 Bq kg-1 for 40K as compared to mean values for rock samples (238U-8.0 Bq kg-1; 232Th-65.1 Bq kg-1; 40K-199.1 Bq kg-1). The mean absorbed gamma dose rate for soil (61.4 nGy h-1) marginally exceeded the prescribed limit of 55 nGy h-1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h-1. The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg-1) than in rock (20.0 Bq kg-1). However, these values were lower than the limit (370 Bq kg-1) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district. (author)

  11. 99mTc-MAA overestimates the absorbed dose to the lungs in radioembolization: a quantitative evaluation in patients treated with 166Ho-microspheres

    International Nuclear Information System (INIS)

    Radiation pneumonitis is a rare but serious complication of radioembolic therapy of liver tumours. Estimation of the mean absorbed dose to the lungs based on pretreatment diagnostic 99mTc-macroaggregated albumin (99mTc-MAA) imaging should prevent this, with administered activities adjusted accordingly. The accuracy of 99mTc-MAA-based lung absorbed dose estimates was evaluated and compared to absorbed dose estimates based on pretreatment diagnostic 166Ho-microsphere imaging and to the actual lung absorbed doses after 166Ho radioembolization. This prospective clinical study included 14 patients with chemorefractory, unresectable liver metastases treated with 166Ho radioembolization. 99mTc-MAA-based and 166Ho-microsphere-based estimation of lung absorbed doses was performed on pretreatment diagnostic planar scintigraphic and SPECT/CT images. The clinical analysis was preceded by an anthropomorphic torso phantom study with simulated lung shunt fractions of 0 to 30 % to determine the accuracy of the image-based lung absorbed dose estimates after 166Ho radioembolization. In the phantom study, 166Ho SPECT/CT-based lung absorbed dose estimates were more accurate (absolute error range 0.1 to -4.4 Gy) than 166Ho planar scintigraphy-based lung absorbed dose estimates (absolute error range 9.5 to 12.1 Gy). Clinically, the actual median lung absorbed dose was 0.02 Gy (range 0.0 to 0.7 Gy) based on posttreatment 166Ho-microsphere SPECT/CT imaging. Lung absorbed doses estimated on the basis of pretreatment diagnostic 166Ho-microsphere SPECT/CT imaging (median 0.02 Gy, range 0.0 to 0.4 Gy) were significantly better predictors of the actual lung absorbed doses than doses estimated on the basis of 166Ho-microsphere planar scintigraphy (median 10.4 Gy, range 4.0 to 17.3 Gy; p 99mTc-MAA SPECT/CT imaging (median 2.5 Gy, range 1.2 to 12.3 Gy; p 99mTc-MAA planar scintigraphy (median 5.5 Gy, range 2.3 to 18.2 Gy; p 99mTc-MAA imaging. Pretreatment diagnostic 166Ho-microsphere SPECT/CT imaging accurately predicts lung absorbed doses after 166Ho radioembolization. (orig.)

  12. A study of the effect of the lung shape on the lung absorbed dose in six standard photon and neutron exposure geometries

    International Nuclear Information System (INIS)

    According to the published results of radiation dosimetry studies, there are significant discrepancies in the organ absorbed doses of existing adult male phantoms. As stated, differences in the organ absorbed doses may be associated with the variations in the organs' volumes, shapes and positions in the body frame. Therefore, this paper focuses on the effect of the lung shape on the lung absorbed dose by creating a series of voxel phantoms, in which the lung shape follows a statistical distribution. These phantoms were exposed to mono-energetic photons and neutrons in six standard irradiation geometries. The results show that when the phantom is irradiated by the low-energy photons, the effects of the lung shape on the lung absorbed dose are considerable (with an uncertainty of more than 100%). For the other irradiation conditions, the variation in the lung shape causes an uncertainty of less than 10% in the dose delivered to the lung. (authors)

  13. Depth dependence of absorbed dose, dose equivalent and linear energy transfer spectra of galactic and trapped particles in polyethylene and comparison with calculations of models

    Science.gov (United States)

    Badhwar, G. D.; Cucinotta, F. A.; Wilson, J. W. (Principal Investigator)

    1998-01-01

    A matched set of five tissue-equivalent proportional counters (TEPCs), embedded at the centers of 0 (bare), 3, 5, 8 and 12-inch-diameter polyethylene spheres, were flown on the Shuttle flight STS-81 (inclination 51.65 degrees, altitude approximately 400 km). The data obtained were separated into contributions from trapped protons and galactic cosmic radiation (GCR). From the measured linear energy transfer (LET) spectra, the absorbed dose and dose-equivalent rates were calculated. The results were compared to calculations made with the radiation transport model HZETRN/NUCFRG2, using the GCR free-space spectra, orbit-averaged geomagnetic transmission function and Shuttle shielding distributions. The comparison shows that the model fits the dose rates to a root mean square (rms) error of 5%, and dose-equivalent rates to an rms error of 10%. Fairly good agreement between the LET spectra was found; however, differences are seen at both low and high LET. These differences can be understood as due to the combined effects of chord-length variation and detector response function. These results rule out a number of radiation transport/nuclear fragmentation models. Similar comparisons of trapped-proton dose rates were made between calculations made with the proton transport model BRYNTRN using the AP-8 MIN trapped-proton model and Shuttle shielding distributions. The predictions of absorbed dose and dose-equivalent rates are fairly good. However, the prediction of the LET spectra below approximately 30 keV/microm shows the need to improve the AP-8 model. These results have strong implications for shielding requirements for an interplanetary manned mission.

  14. Comparison between Radiology Science Laboratory, Brazil (LCR) and National Research Council, Canada (NRC) of the absorbed dose in water using Fricke dosimetry

    International Nuclear Information System (INIS)

    The absorbed dose to water standards for HDR brachytherapy dosimetry developed by the Radiology Science Laboratory, Brazil (LCR) and the National Research Council, Canada (NRC), were compared. The two institutions have developed absorbed dose standards based on the Fricke dosimetry system. There are significant differences between the two standards as far as the preparation and readout of the Fricke solution and irradiation geometry of the holder. Measurements were done at the NRC laboratory using a single Ir-192 source. The comparison of absorbed dose measurements was expressed as the ratio Dw(NRC)/Dw(LCR), which was found to be 1.026. (author)

  15. Radiolysis of tri-n-butyl phosphate solutions effect of absorbed dose on extractability of uranium fission products and nitric acid

    International Nuclear Information System (INIS)

    30% TBP solutions in kerosene, benzene and xylene were ? -irradiated using different exposure doses. The effect of absorbed dose on the extraction of uranium, fission products and H N O3 was investigated. Based on experimental results the effect of dose on : percentage loading free acidity and decontamination factors were calculated, a comparison between the three extraction systems were presented. 6 tab

  16. Absorbed dose to active red bone marrow from diagnostic and therapeutic uses of radiation

    International Nuclear Information System (INIS)

    The bone-marrow dose arising from radiological procedures as carried out in Australia have been determined as part of a survey of population doses. This paper describes the method of calculation of the radiation doses to the active bone marrow from diagnostic radiography, fluoroscopy and radiotherapy. The results of the calculations are compared with the results of other models of bone-marrow dose for a number of diagnostic X-ray procedures

  17. Monte Carlo calculations and measurements of absorbed dose per monitor unit for the treatment of uveal melanoma with proton therapy

    International Nuclear Information System (INIS)

    The treatment of uveal melanoma with proton radiotherapy has provided excellent clinical outcomes. However, contemporary treatment planning systems use simplistic dose algorithms that limit the accuracy of relative dose distributions. Further, absolute predictions of absorbed dose per monitor unit are not yet available in these systems. The purpose of this study was to determine if Monte Carlo methods could predict dose per monitor unit (D/MU) value at the center of a proton spread-out Bragg peak (SOBP) to within 1% on measured values for a variety of treatment fields relevant to ocular proton therapy. The MCNPX Monte Carlo transport code, in combination with realistic models for the ocular beam delivery apparatus and a water phantom, was used to calculate dose distributions and D/MU values, which were verified by the measurements. Measured proton beam data included central-axis depth dose profiles, relative cross-field profiles and absolute D/MU measurements under several combinations of beam penetration ranges and range-modulation widths. The Monte Carlo method predicted D/MU values that agreed with measurement to within 1% and dose profiles that agreed with measurement to within 3% of peak dose or within 0.5 mm distance-to-agreement. Lastly, a demonstration of the clinical utility of this technique included calculations of dose distributions and D/MU values in a realistic model of the human eye. It is possible to predict D/MU values accurately for clinical relevantMU values accurately for clinical relevant range-modulated proton beams for ocular therapy using the Monte Carlo method. It is thus feasible to use the Monte Carlo method as a routine absolute dose algorithm for ocular proton therapy

  18. Primary data for estimation of absorbed doses at an atmospheric dispersion of radioactive nuclei

    International Nuclear Information System (INIS)

    Figs. and Tables are given for estimating radiation doses in case of contamination in connection with a reactor accident. The contribution from the isotopes of Krypton, Xenon and Iodine are studied in detail and the corresponding doses are given as a function of elapsed time after the accident. Doses from other elements are given in tables. (L.K.)

  19. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow

    International Nuclear Information System (INIS)

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimated risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure

  20. Multiple myeloma among atomic bomb survivors in Hiroshima and Nagasaki, 1950-76: relationship to radiation dose absorbed by marrow

    International Nuclear Information System (INIS)

    The relationship between atomic bomb exposure and the incidence of multiple myeloma has been examined in a fixed cohort of atomic bomb survivors and controls in the life-span study sample for Hiroshima and Nagasaki. From October 1950 to December 1976, 29 cases of multiple myeloma were confirmed in this sample. Our analysis shows that the standardized relative risk (RR) adjusted for city, sex, and age at the time of bombings (ATB) increased with marrow-absorbed radiation dose. The increased RR does not appear to differ between cities or sexes and is demonstrable only for those survivors whose age ATB was between 20 and 59 years. The estimaged risk in these individuals is approximately 0.48 cases/million person-years/rad for bone marrow total dose. This excess risk did not become apparent in individuals receiving 50 rad or more in marrow total dose until 20 years or more after exposure

  1. Semi-empirical method for determination of absorbed dose at reference point in water for telecobalt units using air measurements

    International Nuclear Information System (INIS)

    Many international organizations recommend to carry out dosimetry in water phantom at 5 cm depth to arrive at dose at the depth of maximum buildup using percentage depth dose or tissue air ratio data. These recommendations minimize error in dosimetry due to contribution of low energy components of photons at maximum electronic equilibrium depth, which mainly depend upon collimator design of telecobalt units. Some centres may not be able to adopt water phantom dosimetry because of non-availability of water phantoms. In this paper a method has been described to determine the absorbed dose in water for various field sizes using a single value arrived from air measurement and an empirical equation. The empirical constants for the equation are generated for three types of telecobalt units. The results obtained from empirical equation and water phantom dosimetry are found to match closely. (author). 8 refs., 2 tabs

  2. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator.

    Science.gov (United States)

    Puchalska, Monika; Sihver, Lembit

    2015-06-21

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18?MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature. PMID:26057186

  3. PHITS simulations of absorbed dose out-of-field and neutron energy spectra for ELEKTA SL25 medical linear accelerator

    Science.gov (United States)

    Puchalska, Monika; Sihver, Lembit

    2015-06-01

    Monte Carlo (MC) based calculation methods for modeling photon and particle transport, have several potential applications in radiotherapy. An essential requirement for successful radiation therapy is that the discrepancies between dose distributions calculated at the treatment planning stage and those delivered to the patient are minimized. It is also essential to minimize the dose to radiosensitive and critical organs. With MC technique, the dose distributions from both the primary and scattered photons can be calculated. The out-of-field radiation doses are of particular concern when high energy photons are used, since then neutrons are produced both in the accelerator head and inside the patients. Using MC technique, the created photons and particles can be followed and the transport and energy deposition in all the tissues of the patient can be estimated. This is of great importance during pediatric treatments when minimizing the risk for normal healthy tissue, e.g. secondary cancer. The purpose of this work was to evaluate 3D general purpose PHITS MC code efficiency as an alternative approach for photon beam specification. In this study, we developed a model of an ELEKTA SL25 accelerator and used the transport code PHITS for calculating the total absorbed dose and the neutron energy spectra infield and outside the treatment field. This model was validated against measurements performed with bubble detector spectrometers and Boner sphere for 18?MV linacs, including both photons and neutrons. The average absolute difference between the calculated and measured absorbed dose for the out-of-field region was around 11%. Taking into account a simplification for simulated geometry, which does not include any potential scattering materials around, the obtained result is very satisfactorily. A good agreement between the simulated and measured neutron energy spectra was observed while comparing to data found in the literature.

  4. Study of the spatial distribution of the absorbed dose in blood volumes irradiated using a teletherapy unit

    International Nuclear Information System (INIS)

    Blood irradiation can be performed using a dedicated blood irradiator or a teletherapy unit. A thermal device providing appropriate storage conditions during blood components irradiation with a teletherapy unit has been recently proposed. However, the most appropriated volume of the thermal device was not indicated. The goal of this study was to indicate the most appropriated blood volume for irradiation using a teletherapy unit in order to minimize both the dose heterogeneity in the volume and the blood irradiation time using these equipments. Theoretical and experimental methods were used to study the dose distribution in the blood volume irradiated using a linear accelerator and a cobalt-60 therapy machine. The calculation of absorbed doses in the middle plane of cylindrical acrylic volumes was accomplished by a treatment planning system. Experimentally, we also used cylindrical acrylic phantoms and thermoluminescent dosimeters to confirm the calculated doses. The data obtained were represented by isodose curves. We observed that an irradiation volume should have a height of 28 cm and a diameter of 28 cm and a height of 35 cm and a diameter of 35 cm, when the irradiation is to be performed by a linear accelerator and a cobalt-60 teletherapy unit, respectively. Calculated values of relative doses varied from 93% to 100% in the smaller volume, and from 66% to 100% in the largest one. A difference of 5.0%, approximately, was observed between calculated and experimentabserved between calculated and experimental data. The size of these volumes permits the irradiation of blood bags in only one bath without compromising the homogeneity of the absorbed dose over the irradiated volume. Thus, these irradiation volumes can be recommend to minimize the irradiation time when a teletherapy unit is used to irradiate blood.

  5. A fibre optic scintillator dosemeter for absorbed dose measurements of low-energy X-ray-emitting brachytherapy sources

    International Nuclear Information System (INIS)

    A newly developed dosemeter using a 0.5 mm diameter x 0.5 mm thick cylindrical plastic scintillator coupled to the end of a fibre optic cable is capable of measuring the absorbed dose rate in water around low-activity, low-energy X-ray emitters typically used in prostate brachytherapy. Recent tests of this dosemeter showed that it is possible to measure the dose rate as a function of distance in water from 2 to 30 mm of a 103Pd source of air-kerma strength 3.4 U (1 U = 1 ?Gy m2h-1), or 97 MBq (2.6 mCi) apparent activity, with good signal-to-noise ratio. The signal-to-noise ratio is only dependent on the integration time and background subtraction. The detector volume is enclosed in optically opaque, nearly water-equivalent materials so that there is no polar response other than that due to the shape of the scintillator volume chosen, in this case cylindrical. The absorbed dose rate very close to commercial brachytherapy sources can be mapped in an automated water phantom, providing a 3-D dose distribution with sub-millimeter spatial resolution. The sensitive volume of the detector is 0.5 mm from the end of the optically opaque waterproof housing, enabling measurements at very close distances to sources. The sensitive detector electronics allow the measurement of very low dose rates, as exist at centimeter distances from these sources. The detector is also applicable to mapping dose distributions from more complex source geometries sucs from more complex source geometries such as eye applicators for treating macular degeneration. (authors)

  6. Dose calculation and dosimetry tests for clinical implementation of 1D tissue-deficit compensation by a single dynamic absorber

    International Nuclear Information System (INIS)

    Background and purpose: In this study the possibilities for implementing 1D tissue-deficit compensation techniques by a dynamic single absorber were investigated. This research firstly involved a preliminary examination on the accuracy of a pencil beam-based algorithm, implemented for irregularly shaped photon beams in our 3D treatment planning system (TPS) (Cadplan 2.7, Varian-Dosetek Oy), in calculating dose distributions delivered in 1D non-uniform fields. Once the reliability of the pencil beam (PB) algorithm for dose calculations in non-uniform beams was verified, we proceeded to test the feasibility of tissue-deficit compensation using our single absorber modulator. As an example, we considered a mantle field technique. Materials and methods: To evaluate the accuracy of the method employed in calculating dose distributions delivered in 1D non-uniform fields, three different fluence profiles, which could be considered as a small sample representative of clinically relevant applications, were selected. The incident non-uniform fluences were simulated by the sum of simple blocked fields (i.e. with rectangular 'strip' blocks, one per beam) properly weighed by the 'modulation factors' Fi, defined in each interval of the subdivided profile as the ratio between the desired fluence and the open field fluence. Depth dose distributions in a cubic phantom were then calculated by the TPS and compared with the corresponding doses (at 5 and 10 cm acrylic depths) deg doses (at 5 and 10 cm acrylic depths) delivered by the single absorber modulation system. In the present application, the absorber speed profile able to compensate for the tissue deficit along the cranio-caudal direction and then homogenizing the dose distribution on a 'midline' isocentric plane with sufficient accuracy can be directly derived from anatomic data, such as the SSDs (source-skin distances) along the patient contour. The compensation can be verified through portal dosimetry techniques (using a traditional port film system). Results: The technique was tested in isocentric conditions on the humanoid RANDO phantom in a clinically suitable situation. The agreement between expected/calculated and measured incident/exit dose profiles was found to be within 4%, with deviations generally around 1-2%. As for the PB accuracy investigation for dose calculations in non-uniform fields, calculated versus measured dose profiles were found to be in good agreement, indicating a satisfactory accuracy of the method employed for dose calculation in 1D non-uniform photon beams. A better performance should be expected if the incident fluences could be directly inserted in the TPS. Conclusions: The results show that the proposed technique should be sufficiently reliable for clinical application. The main advantages are its simplicity and the possibility of application on Linacs which have no complex options for dynamic control of collimators. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)

  7. COMPARISON BETWEEN ABSORBED DOSES IN TARGET ORGANS IN PANORAMIC RADIOGRAPHY, USING SINGLE EMULSION AND DOUBLE EMULSION FILMS

    Directory of Open Access Journals (Sweden)

    A. R. Talaeipour

    2007-07-01

    Full Text Available "nThe use of panoramic radiography, due to its numerous advantages, is increasing. Radiographic films used in this technique are of double emulsion (DE type which are used with intensifying screens. Single emulsion (SE films can also be used. The purpose of this study was to determine the exposure parameters to achieve an appropriate optical density in these two types of films, and to estimate under such parameters, radiation doses to mandibular bone marrow (MBM, thyroid gland and parotid gland. This study was performed through a tissue equivalent phantom. First, with various tube voltage and tube current, 128 radiographs were taken of phantom with these two types of films. After examining the optical densities, the exposure parameters under which both films have the same density, were determined. Then, phantom again was exposed and MBM, thyroid gland and parotid gland absorbed doses were measured, using TLDs. It was demonstrated that: 1 SE films, in order to provide appropriate optical density, require two times radiation in comparison with double emulsion film; 2 using SE films increases MBM dose, up to 2-2.5 times, thyroid gland dose up to 1.7-2 times and parotid gland dose up to 1.3 times, in comparison with DE films; 3 in DE films, under lower exposure parameters and desirable processing, MBM dose up to 3.5 times, thyroid gland dose up to 1.5 times and parotid gland dose up to 2.5 times will increase. Considering that the risk of radiation induced cancers increases with repeated radiation doses, using SE films is not recommended.

  8. Absorbed dose measurements in dual energy X-ray absorptiometry (DEXA) using film dosimetry

    International Nuclear Information System (INIS)

    Full text: There is a paucity of information regarding the effective dose to patients from dual energy X-ray absorptiometry (DEXA) studies. A predominantly film dosimetric method was used to measure the effective dose from spine and femur scans performed on a Lunar DPX-L machine. Because of the very low dose rate in scanning mode, the depth dose data were determined using a stationary detector configuration. The characteristic curve for the film (Kodak TMAT-H) was obtained and depth dose measurements were made using slabs of ''solid water''. The film was calibrated using a superficial X-ray unit (calibrated against a standard traceable to a national standard). The film was exposed to calibration beams of different half value layer (HVL), to assess the change in film response with beam hardening at depth. The HVL of the DEXA beam was determined for surface and depth doses using aluminium filters and a diamond detector (energy- independent device). All measurements were performed three times. Beam size was measured on film (stationary mode), and the scan areas and times were determined on film by scanning phantoms. The dose from a scan was calculated using Dsc= D.Tsc.Ab/Asc, where D = dose rate (stationary), Tsc scan time, Ab = beam area and Asc = scan area. Organ doses were determined using anatomical atlas and ICRP 23 female reference. Aft film measurements had high precision (coefficient of variation < 4%). There was little variation in film sensitivity with change iariation in film sensitivity with change in HVL (<1% change, first 3 HVLs) and no corrections were applied to the depth dose data. The skin entrance dose was 11.5 ?Gy and the effective dose (in females) was 0.24 ?Sv (spine) and 0.27 ?Sv (femur). In conclusion, a film dosimetric method has been developed and used to measure the effective dose from a Lunar DPX-L machine

  9. Absorbed dose at subcellular level by Monte Carlo simulation for a 99mTc-peptide with nuclear internalization

    International Nuclear Information System (INIS)

    The utility of radiolabeled peptides for the early and specific diagnosis of cancer is being investigated around the world. Recent investigations have demonstrated the specificity of 99mTc-bombesin conjugates to target breast and prostate cancer cells. The novel idea of adding the Tat (49-57) peptide to the radiopharmaceutical in order to penetrate the cell nucleus is a new proposal for therapy at cellular level. 99mTc radionuclide produces Auger energy of 0.9 keV/decay and internal conversion electron energy of 15.4 keV/decay, which represent 11.4% of the total 99mTc energy released per decay. It is expected that the dose delivered at specific microscopic levels in cancer cells induce a therapeutic effect. The aim of this research was to assess in vitro internalization kinetics in breast and prostate cancer cells of 99mTc-Tat(49-57)-bombesin and to evaluate the radiation absorbed dose at subcellular level simulating the electron transport. The pen main program from the 2006 version of the Penelope code was used to simulate and calculate the absorbed dose by Auger and internal conversion electron contribution in the membrane, cytoplasm and nucleus of Pc-3 prostate cancer and MCF7 and MDA human breast cancer cell lines. Nuclear data were obtained from the 2002 BNM-LNHB 99mTc decay scheme. The spatial distribution of the absorbed doses to the membrane, cytoplasm and nucleus were calculated using a geometric model buwere calculated using a geometric model built from real images of cancer cells. The elemental cell composition was taken from the literature. The biokinetic data were obtained evaluating total disintegrations in each subcellular compartment by integration of the time-activity curves acquired from experimental data. Results showed that 61, 63 and 46% of total disintegrations per cell-bound 99mTc-Tat-Bn activity unit occurred in the nucleus of Pc-3, MCF7 and MDA-MB231 respectively. 99mTc--Tat-Bn absorbed doses were 1.78, 5.76 and 2.59 Gy/Bq in the nucleus of Pc-3, MCF7 and MDA-MB231 correspondingly. (Author)

  10. Monthly frequency of the annual maximum absorbed dose rate in air for environmental ?-radiation in Japan

    International Nuclear Information System (INIS)

    It is known that the environmental radiation dose rate is affected by rain- or snow-falls, and the dose rate and the intensity of the rain/snow-fall are in a negative correlation. Since the amount of rain is large in the summer season, the radiation dose rate shows a seasonal variation, which occupies about 40% of the total seasonal variation. Observation of the dose rates at 46 points distributed all over Japan shows the maximum dose rate appears usually in the winter season. The month when the maximum dose rate appears depends on the pint where the observation is made and is: January in the Japan Sea area, in the inland area and in the Inland Sea area; February in the Pacific Ocean area; June in Kyushu district; March in the South-East Island area. (K. Yoshida)

  11. Measurement and modeling of gamma-absorbed doses due to atmospheric releases from Los Alamos Meson Physics Facility

    International Nuclear Information System (INIS)

    Short-term gamma-absorbed doses were measured by one high-pressure ionization chamber (HPIC) at an azimuth of 120 from the Los Alamos Meson Physics Facility (LAMPF) stack during the January 1 through February 8 operating cycle. Two HPICs were in the field during the September 8 through December 31 operating cycle, one north and the other north-northeast of the LAMPF stack, but they did not provide reliable data. Meteorological data were also measured at both East Gate and LAMPF. Airborne emission data were taken at the stack. Daily model predictions, based on the integration of modeled 15-min periods, were made for the first LAMPF operating cycle and were compared with the measured data. A comparison of the predicted and measured daily gamma doses due to LAMPF emissions is presented. There is very good correlation between measured and predicted values. During 39-day operating cycles, the model predicted an absorbed dose of 10.3 mrad compared with the 8.8 mrad that was measured, an overprediction of 17%

  12. Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828 on the coast of Ceara, Brazil

    Directory of Open Access Journals (Sweden)

    Wagner de S. Pereira

    2010-01-01

    Full Text Available A methodology was developed for converting the activity concentration of radionuclides (Bq kg-1 into absorbed dose rate (Gy y-1, aiming an approach to environmental radioprotection based on the concept of standard dose limit. The model considers only the internal absorbed dose rate. This methodology was applied to the cubera snapper fish (Lutjanus cyanopterus, Cuvier, 1828 caught off the coast of Ceará. The natural radionuclides considered were uranium-238, radium-226, lead-210, thorium-232 and radium-228. The absorbed dose rates were calculated for individual radionuclides and the type of emitted radiation. The average dose rate due to these radionuclides was 5.36 µGy y-1, a value six orders of magnitude smaller than the threshold value of absorbed dose rate used in this study (3.65 10³ mGy y-1, and similar to that found in the literature for benthic fish. Ra-226 and U-238 contributed 67% and 22% of the absorbed dose rate, followed by Th-232 with 10%. Ra-228 and Pb-210, in turn, accounted for less than 1% of the absorbed dose rate. This distribution is somewhat different from that reported in the literature, where the Ra-226 accounts for 86% of the absorbed dose rate.Visando a radioproteção ambiental, baseada no conceito de limite de taxa de dose absorvida, foi desenvolvida uma metodologia de conversão da concentração de atividade de radionuclídeos (Bq kg-1 em taxa de dose absorvida (Gy a-1. O modelo considera apenas a taxa de dose absorvida interna. Essa metodologia foi aplicada ao peixe vermelho-caranho (Lutjanus cyanopterus, Cuvier, 1828 capturado na costa do Ceará e aos radionuclídeos naturais: urânio-238, rádio-226, chumbo-210, tório-232 e rádio-228. As taxas de dose absorvidas foram calculadas por radionuclídeo e por tipo de radiação emitida. A taxa de dose média devida a esses radionuclídeos foi de 5.36 µGy a-1, valor seis ordens de grandeza menor que o valor de limite de taxa de dose absorvida utilizada no presente trabalho (3.65 10³ mGy a-1, e similar ao encontrado na literatura para peixes bentônicos. Ra-226 e U-238 contribuíram com 67% e 22% da taxa de dose absorvida, seguidos de Th-232 com 10%. Já Ra-228 e Pb-210 respondem por menos de 1% da taxa de dose absorvida. Essa distribuição é um pouco diferente do relatado na literatura, onde Ra-226 responde por 86% da taxa de dose absorvida.

  13. Activity of natural radionuclides and their contribution to the absorbed dose in the fish cubera snapper (lutjanus cyanopterus, cuvier, 1828) on the coast of Ceara, Brazil

    Scientific Electronic Library Online (English)

    Wagner de S., Pereira; Alphonse, Kelecom; Delcy de A., Py Júnior.

    Full Text Available Visando a radioproteção ambiental, baseada no conceito de limite de taxa de dose absorvida, foi desenvolvida uma metodologia de conversão da concentração de atividade de radionuclídeos (Bq kg-1) em taxa de dose absorvida (Gy a-1). O modelo considera apenas a taxa de dose absorvida interna. Essa meto [...] dologia foi aplicada ao peixe vermelho-caranho (Lutjanus cyanopterus, Cuvier, 1828) capturado na costa do Ceará e aos radionuclídeos naturais: urânio-238, rádio-226, chumbo-210, tório-232 e rádio-228. As taxas de dose absorvidas foram calculadas por radionuclídeo e por tipo de radiação emitida. A taxa de dose média devida a esses radionuclídeos foi de 5.36 µGy a-1, valor seis ordens de grandeza menor que o valor de limite de taxa de dose absorvida utilizada no presente trabalho (3.65 10³ mGy a-1), e similar ao encontrado na literatura para peixes bentônicos. Ra-226 e U-238 contribuíram com 67% e 22% da taxa de dose absorvida, seguidos de Th-232 com 10%. Já Ra-228 e Pb-210 respondem por menos de 1% da taxa de dose absorvida. Essa distribuição é um pouco diferente do relatado na literatura, onde Ra-226 responde por 86% da taxa de dose absorvida. Abstract in english A methodology was developed for converting the activity concentration of radionuclides (Bq kg-1) into absorbed dose rate (Gy y-1), aiming an approach to environmental radioprotection based on the concept of standard dose limit. The model considers only the internal absorbed dose rate. This methodolo [...] gy was applied to the cubera snapper fish (Lutjanus cyanopterus, Cuvier, 1828) caught off the coast of Ceará. The natural radionuclides considered were uranium-238, radium-226, lead-210, thorium-232 and radium-228. The absorbed dose rates were calculated for individual radionuclides and the type of emitted radiation. The average dose rate due to these radionuclides was 5.36 µGy y-1, a value six orders of magnitude smaller than the threshold value of absorbed dose rate used in this study (3.65 10³ mGy y-1), and similar to that found in the literature for benthic fish. Ra-226 and U-238 contributed 67% and 22% of the absorbed dose rate, followed by Th-232 with 10%. Ra-228 and Pb-210, in turn, accounted for less than 1% of the absorbed dose rate. This distribution is somewhat different from that reported in the literature, where the Ra-226 accounts for 86% of the absorbed dose rate.

  14. Determination of absorbed dose by single photon emission computerized tomography in the radioiodine treatment of distant metastases from thyroid carcinoma

    International Nuclear Information System (INIS)

    The purpose of this paper is to present the results of preliminary experience in the dosimetry of I-131 to metastatic tumors from thyroid cancer, utilizing SPECT for calculation of the absorbed dose. SPECT was performed with a scintillation camera, 1-20 days after the administration of a treatment dose of I-131 78-150 mCi in 15 cases. All patients were performed total thyroidectomy and/or ablation with radioiodine. All had been off thyroid-suppression medication for 2 weeks before I-131 scanning. The study population included 3 men and 12 women, with ages ranging from 20-74 years. Thirteen had had follicular carcinoma and two papillary, including mixed papillary-follicular. A SPECT system with high energy collimater, was calibrated with cylindrical volume sources containing I-131, within a 16-25 cm diameter water filled cylinder. The attenuation coefficient for the 360keV photons of I-131 in water was ?=0.05 cm, resulting in a uniform radioactivity distribution in the reconstructed image. And this value is used for attenuation correction. Half-life data and activities of I-131 have been compiled in which the isotope assumed to be concentrated in tumors. Weight of tumors was estimated by TCT images. Radiation absorbed doses were calculated using the Medical Internal Radiaton Dose (MIRD). The weight of tumors ranged from 2-80 gram and the tumor radiation dose ranged from 500-25,000 rads. These results indicate that dosimetry with SPECT correlate well with clinical course and have the added advantage of I-131 treatment

  15. On the influence of the patient's posture on organ and tissue absorbed doses caused by radiodiagnostic examinations

    International Nuclear Information System (INIS)

    Standing and supine (=lying on one's back) postures are most frequently used positions for patients submitted to examinations in radiodiagnosis. When it comes to the assessment of organ and tissue absorbed doses, human phantoms connected to Monte Carlo (MC) codes are applied which usually represent individuals either in standing or in supine posture, i.e. that depending on the protocol of the examination to be simulated, some of the MC calculations are made using a phantom with the false posture. To find out if the posture has a significant impact on organ and tissue absorbed doses, one has to model phantoms to represent humans in different postures and to use them under exactly the same exposure conditions. FASH2sta, MASH2sta and FASH2sup, MASH2sup are pairs of female and male adult phantoms in standing and supine posture, respectively. The phantoms will be used for the simulation of X-ray examinations of the thorax and the abdomen and resulting organ and tissue absorbed doses will be compared for the two postures. This synopsis will show results for a thorax radiograph of the FASH2sta and the FASH2sup phantoms. Up to 50% of all examinations of the thorax are being made with lying patients in intensive care or simply because hospitalized patients cannot stand up and/or turn around. The tube voltage is 90 kV, the filtration 2.5 mm Al, the FDD = 105 cm and the field size in the image receptor plane 35 cmeld size in the image receptor plane 35 cm x 40 cm. Normally, the patient is in supine posture and the projection is AP (ventro-dorsal). The field is centred on the middle of the sternum

  16. Standard Practice for Application of Thermoluminescence-Dosimetry (TLD) Systems for Determining Absorbed Dose in Radiation-Hardness Testing of Electronic Devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for the use of thermoluminescence dosimeters (TLDs) to determine the absorbed dose in a material irradiated by ionizing radiation. Although some elements of the procedures have broader application, the specific area of concern is radiation-hardness testing of electronic devices. This practice is applicable to the measurement of absorbed dose in materials irradiated by gamma rays, X rays, and electrons of energies from 12 to 60 MeV. Specific energy limits are covered in appropriate sections describing specific applications of the procedures. The range of absorbed dose covered is approximately from 10?2 to 104 Gy (1 to 106 rad), and the range of absorbed dose rates is approximately from 10?2 to 1010 Gy/s (1 to 1012 rad/s). Absorbed dose and absorbed dose-rate measurements in materials subjected to neutron irradiation are not covered in this practice. Further, the portion of these procedures that deal with electron irradiation are primarily intended for use in parts testin...

  17. Distributions of absorbed dose rates in air due to the ionizing components of cosmic ray in the lower atmosphere

    International Nuclear Information System (INIS)

    The variation of absorbed dose rates in air due to the ionizing components of cosmic ray with altitude have been measured by means of FJ-202 pressurized ionization chamber in this experiment. At the lower altitudes the results are in closer agreement with that given in the UNSCEAR 1988 Report, the deviations are within +-7% and the variance trend with altitude is also similar to that of China Institute of Atomic Energy (CIAE). However there is a difference between the absolute values of our measurements and those measured by CIAE. (3 tabs.)

  18. Hormone regulation system and cyclic nucleotids in the Chernobyl accident liquidators with doses absorbed less then 1 Gy

    International Nuclear Information System (INIS)

    During 6 years after the accident (1987-1992) a functional state of endocrine system that regulate the adaptation, reproduction, metabolism, vessels tonicity and water-electrolyte balance were investigated in 249 liquidators with doses absorbed less then 1 Gy. The changes of these systems activity in state of basal secretion and peculiarities of their reactions under influence of perturbation (adrenaline, insulin) were revealed. Post-irradiation endocrinopathy was characterized and its role in decrease of the organism's adaptation and in mechanism of sanogenesis and pathogenesis was found. (author)

  19. High-Dose 131I-Tositumomab (Anti-CD20) Radioimmunotherapy for Non-Hodgkin's Lymphoma: Adjusting Radiation Absorbed Dose to Actual Organ Volumes

    International Nuclear Information System (INIS)

    Radioimmunotherapy (RIT) using 131I-tositumomab has been used successfully to treat relapsed or refractory B-cell non-Hodgin's lymphoma (NHL). Our approach to treatment planning has been to determine limits on radiation absorbed close to critical nonhematopoietic organs. This study demonstrates the feasibility of using CT to adjust for actual organ volumes in calculating organ-specific absorbed dose estimates. Methods: Records of 84 patients who underwent biodistribution studies after a trace-labeled infusion of 131I-tositumomab for RIT (January 1990 and April 2003) were reviewed. Serial planar -camera images and whole-body Nal probe counts were obtained to estimate 131I-antibody source-organ residence times as recommended by the MIRD Committee. The source-organ residence times for standard man or woman were adjusted by the ratio of the MIRD phantom organ mass to the CT-derived organ mass. Results: The mean radiation absorbed doses (in mGy/MBq) for our data using the MIRD model were lungs= 1.67; liver= 1.03; kidneys= 1.08; spleen= 2.67; and whole body= 0.3; and for CT volume-adjusted organ volumes (in mGy/MBq) were lungs= 1.30; liver= 0.92; kidneys= 0.76; spleen= 1.40; and whole body= 0.22. We determined the following correlation coefficients between the 2 methods for the various organs; lungs, 0.49; (P= 0.0001); liver, 0.64 (P= 0.004); kidneys, 0.45 (P= 0.0001), for the residence times. For therapy, patients received mean 131I administered activities of 19.2 GBq (520I administered activities of 19.2 GBq (520 mCi) after adjustment for CT-derived organ mass compared with 16.0 GBq (433 mCi) that would otherwise have been given had therapy been based only using standard MIRD organ volumes--a statistically significant difference (P= 0.0001). Conclusion: We observed large variations in organ masses among our patients. Our treatments were planned to deliver the maximally tolerated radiation dose to the dose-limiting normal organ. This work provides a simplified method for calculating patient-specific radiation doses by adjusting for the actual organ mass and shows the value of this approach in treatment planning for RIT

  20. Determinação de dose absorvida em feixes de elétrons utilizado câmara de ionizacão de placas paralelas / Determination of absorbed dose in electron beams using parallel-plane ionization chambers

    Scientific Electronic Library Online (English)

    Roseli T., Bulla; Linda V.E., Caldas.

    2004-06-01

    Full Text Available OBJETIVO: O objetivo deste trabalho foi estabelecer um procedimento para a determinação dos fatores de calibração e de doses absorvidas em feixes de elétrons. MATERIAIS E MÉTODOS: Foram utilizados um irradiador de 60Co e um acelerador linear Varian, modelo Clinac 2100C, com feixes de fótons e de elé [...] trons. Foram estudadas câmaras de ionização do tipo dedal e de placas paralelas. RESULTADOS: Os sistemas de medidas foram submetidos aos testes preliminares (estabilidade de resposta e corrente de fuga), com resultados muito bons. Quatro métodos de calibração de câmaras de ionização para utilização em feixes de elétrons foram testados. Para a determinação da dose absorvida em feixes de elétrons foram aplicadas três metodologias propostas pela Agência Internacional de Energia Atômica, com a obtenção de resultados concordantes em quase todos os casos. CONCLUSÃO: A maior parte das câmaras de ionização estudadas mostrou-se viável, com desempenho dentro dos limites internacionais estabelecidos. Abstract in english OBJECTIVE: The objective of this paper was to establish a procedure for the determination of calibration factors and absorbed doses in electron beams. MATERIALS AND METHODS: An irradiator with a 60Co source and a linear accelerator Varian, Clinac 2100C, with photon and electron beams, were utilized. [...] Thimble type and parallel-plane ionization chambers were tested. RESULTS: The measurement systems showed very good results in the preliminary tests (response stability and leakage current). The ionization chambers used for electron beam dosimetry were calibrated using four different methods. For the determination of absorbed dose, three methodologies recommended by the International Atomic Energy Agency were applied. Concordant results were obtained in almost all cases. CONCLUSION: The majority of the ionization chambers tested showed good results according to the established international limits.

  1. Determinação de dose absorvida em feixes de elétrons utilizado câmara de ionizacão de placas paralelas Determination of absorbed dose in electron beams using parallel-plane ionization chambers

    Directory of Open Access Journals (Sweden)

    Roseli T. Bulla

    2004-06-01

    Full Text Available OBJETIVO: O objetivo deste trabalho foi estabelecer um procedimento para a determinação dos fatores de calibração e de doses absorvidas em feixes de elétrons. MATERIAIS E MÉTODOS: Foram utilizados um irradiador de 60Co e um acelerador linear Varian, modelo Clinac 2100C, com feixes de fótons e de elétrons. Foram estudadas câmaras de ionização do tipo dedal e de placas paralelas. RESULTADOS: Os sistemas de medidas foram submetidos aos testes preliminares (estabilidade de resposta e corrente de fuga, com resultados muito bons. Quatro métodos de calibração de câmaras de ionização para utilização em feixes de elétrons foram testados. Para a determinação da dose absorvida em feixes de elétrons foram aplicadas três metodologias propostas pela Agência Internacional de Energia Atômica, com a obtenção de resultados concordantes em quase todos os casos. CONCLUSÃO: A maior parte das câmaras de ionização estudadas mostrou-se viável, com desempenho dentro dos limites internacionais estabelecidos.OBJECTIVE: The objective of this paper was to establish a procedure for the determination of calibration factors and absorbed doses in electron beams. MATERIALS AND METHODS: An irradiator with a 60Co source and a linear accelerator Varian, Clinac 2100C, with photon and electron beams, were utilized. Thimble type and parallel-plane ionization chambers were tested. RESULTS: The measurement systems showed very good results in the preliminary tests (response stability and leakage current. The ionization chambers used for electron beam dosimetry were calibrated using four different methods. For the determination of absorbed dose, three methodologies recommended by the International Atomic Energy Agency were applied. Concordant results were obtained in almost all cases. CONCLUSION: The majority of the ionization chambers tested showed good results according to the established international limits.

  2. The Effects on Absorbed Dose Distribution in Intraoral X-ray Imaging When Using Tube Voltages of 60 and 70 kV for Bitewing Imaging

    Directory of Open Access Journals (Sweden)

    Kristina Hellén-Halme

    2013-10-01

    Full Text Available Objectives: Efforts are made in radiographic examinations to obtain the best image quality with the lowest possible absorbed dose to the patient. In dental radiography, the absorbed dose to patients is very low, but exposures are relatively frequent. It has been suggested that frequent low-dose exposures can pose a risk for development of future cancer. It has previously been reported that there was no significant difference in the diagnostic accuracy of approximal carious lesions in radiographs obtained using tube voltages of 60 and 70 kV. The aim of this study was, therefore, to evaluate the patient dose resulting from exposures at these tube voltages to obtain intraoral bitewing radiographs.Material and Methods: The absorbed dose distributions resulting from two bitewing exposures were measured at tube voltages of 60 and 70 kV using Gafchromic® film and an anatomical head phantom. The dose was measured in the occlusal plane, and ± 50 mm cranially and caudally to evaluate the amount of scattered radiation. The same entrance dose to the phantom was used. The absorbed dose was expressed as the ratio of the maximal doses, the mean doses and the integral doses at tube voltages of 70 and 60 kV.Results: The patient receives approximately 40 - 50% higher (mean and integral absorbed dose when a tube voltage of 70 kV is used.Conclusions: The results of this study clearly indicate that 60 kV should be used for dental intraoral radiographic examinations for approximal caries detection.

  3. From Reference Air Kerma Rate to Nominal Absorbed Dose Rate to Water: Paradigm Shift in Photon Brachytherapy

    International Nuclear Information System (INIS)

    In brachytherapy (BT), photon radiation sources are presently calibrated in terms of the reference air kerma rate K? (or air kerma strength SK). By direct source calibration in terms of Dw,1, the nominal absorbed dose rate to water at the TG-43U1 reference position at 1 cm in water and with the ability to measure distributions of this quantity, the accuracy of clinical BT-dosimetry should increase due to decreased calibration uncertainties compared to present methods. Several Dw,1 primary standards are under development for high energy, high dose rate and low energy, low dose rate sources. To provide worldwide traceability and guidance for clinical medical physicists, an ISO standardization project, Clinical Dosimetry - Photon Radiation Sources Used in Brachytherapy, is considered, in continuation of ISO 21439 (2009) for beta sources. Clear terms and definitions are fundamental. Reclassification of BT-photon radiation qualities is also needed, introducing a range of medium energy photons with mean energies between 40 keV and 150 keV. Radionuclide BT-sources and electronic X ray BT-sources, BT-detectors and BT-phantoms should be characterized by sets of reference data, through which the clinical medical physicist could critically evaluate the data supplied by the manufacturer, prior to clinical application. Plastic scintillators have the potential for transfer standards of high accuracy and for verification measurements of Bcy and for verification measurements of BT-source output in phantoms. Based on and extending the AAPM TG-43U1 formalism, this planned ISO-standard will provide guidance for clinical BT-dosimetry in terms of absorbed dose to water and for estimating the uncertainties. (author)

  4. Proton absorbed dose distribution in human eye simulated by SRNA-2KG code

    International Nuclear Information System (INIS)

    The model of Monte Carlo SRNA code is described together with some numerical experiments to show feasibility of this code to be used in proton therapy, especially for tree dimensional proton absorption dose calculation in human eye. (author)

  5. Comparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulationComparison of absorbed dose in the cervix carcinoma therapy by brachytherapy of high dose rate using the conventional planning and Monte Carlo simulation

    International Nuclear Information System (INIS)

    This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of 192Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results indicate an under dosage of the target volume of about 20%. (author)This study aims to compare the doses received for patients submitted to brachytherapy High Dose Rate (HDR) brachytherapy, a method of treatment of the cervix carcinoma, performed in the planning system PLATO BPS with the doses obtained by Monte Carlo simulation using the radiation transport code MCNP 5 and one female anthropomorphic phantom based on voxel, the FAX. The implementation of HDR brachytherapy treatment for the cervix carcinoma consists of the insertion of an intrauterine probe and an intravaginal probe (ring or ovoid) and then two radiographs are obtained, anteroposterior (AP) and lateral (LAT) to confirm the position of the applicators in the patient and to allow the treatment planning and the determination of the absorbed dose at points of interest: rectum, bladder, sigmoid and point A, which corresponds anatomically to the crossings of the uterine arteries with ureters The absorbed doses obtained with the code MCNP 5, with the exception of the absorbed dose in the rectum and sigmoid for the simulation considering a point source of 192Ir, are lower than the absorbed doses from PLATO BPS calculations because the MCNP 5 considers the chemical compositions and densities of FAX body, not considering the medium as water. When considering the Monte Carlo simulation for a source with dimensions equal to that used in the brachytherapy irradiator used in this study, the values of calculated absorbed dose to the bladder, to the rectum, to the right point A and to the left point A were respectively lower than those determined by the treatment planning system in 33.29, 5.01, 22.93 and 19.04%. These values are almost all larger than the maximum acceptable deviation between patient planned and administered doses (5 %). With regard to the rectum and bladder, which are organs that must be protected, the present results are in favor of the radiological protection of patients. The point A, that is on the isodose of 100%, used to tumor treatment, the results indicate an under dosage of the target volume of abo

  6. Supplementary comparison CCRI(I)-S2 of standards for absorbed dose to water in 60Co gamma radiation at radiation processing dose levels

    DEFF Research Database (Denmark)

    Burns, D. T.; Allisy-Roberts, P. J.

    2011-01-01

    Eight national standards for absorbed dose to water in 60Co gamma radiation at the dose levels used in radiation processing have been compared over the range from 1 kGy to 30 kGy using the alanine dosimeters of the NIST and the NPL as the transfer dosimeters. The comparison was organized by the Bureau International des Poids et Mesures, who also participated at the lowest dose level using their radiotherapy-level standard for the same quantity. The national standards are in general agreement within the standard uncertainties, which are in the range from 1 to 2 parts in 102. Evidence of a dose rate effect is presented and discussed briefly. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section I, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA)

  7. Análise da distribuição espacial de dose absorvida em próton terapia ocular Spatial distribution analysis of absorbed dose in ocular proton radiation therapy

    Directory of Open Access Journals (Sweden)

    Marília Tavares Christóvão

    2010-08-01

    Full Text Available OBJETIVO: Propõe-se avaliar os perfis de dose em profundidade e as distribuições espaciais de dose para protocolos de radioterapia ocular por prótons, a partir de simulações computacionais em código nuclear e modelo de olho discretizado em voxels. MATERIAIS E MÉTODOS: As ferramentas computacionais empregadas foram o código Geant4 (GEometry ANd Tracking Toolkit e o SISCODES (Sistema Computacional para Dosimetria em Radioterapia. O Geant4 é um pacote de software livre, utilizado para simular a passagem de partículas nucleares com carga elétrica através da matéria, pelo método de Monte Carlo. Foram executadas simulações computacionais reprodutivas de radioterapia por próton baseada em instalações pré-existentes. RESULTADOS: Os dados das simulações foram integrados ao modelo de olho através do código SISCODES, para geração das distribuições espaciais de doses. Perfis de dose em profundidade reproduzindo o pico de Bragg puro e modulado são apresentados. Importantes aspectos do planejamento radioterápico com prótons são abordados, como material absorvedor, modulação, dimensões do colimador, energia incidente do próton e produção de isodoses. CONCLUSÃO: Conclui-se que a terapia por prótons, quando adequadamente modulada e direcionada, pode reproduzir condições ideais de deposição de dose em neoplasias oculares.OBJECTIVE: The present study proposes the evaluation of the depth-dose profiles and the spatial distribution of radiation dose for ocular proton beam radiotherapy protocols, based on computer simulations in nuclear codes and an eye model discretized into voxels. MATERIALS AND METHODS: The employed computational tools were Geant4 (GEometry ANd Tracking Toolkit and SISCODES (Sistema Computacional para Dosimetria em Radioterapia - Computer System for Dosimetry in Radiotherapy. Geant4 is a toolkit for simulating the passage of particles through the matter, based on Monte Carlo method. Computer simulations of proton therapy were performed based on preexisting facilities. RESULTS: Simulation data were integrated into SISCODES on the eye's model generating spatial dose distributions. Dose depth profiles reproducing the pure and modulated Bragg peaks are presented. Relevant aspects of proton beam radiotherapy planning are considered such as material absorber, modulation, collimator dimensions, incident proton energy and isodose generation. CONCLUSION: The conclusion is that proton therapy when properly modulated and directed can reproduce the ideal conditions for the dose deposition in the treatment of ocular tumors.

  8. Análise da distribuição espacial de dose absorvida em próton terapia ocular / Spatial distribution analysis of absorbed dose in ocular proton radiation therapy

    Scientific Electronic Library Online (English)

    Marília Tavares, Christóvão; Tarcísio Passos Ribeiro de, Campos.

    2010-08-01

    Full Text Available OBJETIVO: Propõe-se avaliar os perfis de dose em profundidade e as distribuições espaciais de dose para protocolos de radioterapia ocular por prótons, a partir de simulações computacionais em código nuclear e modelo de olho discretizado em voxels. MATERIAIS E MÉTODOS: As ferramentas computacionais e [...] mpregadas foram o código Geant4 (GEometry ANd Tracking) Toolkit e o SISCODES (Sistema Computacional para Dosimetria em Radioterapia). O Geant4 é um pacote de software livre, utilizado para simular a passagem de partículas nucleares com carga elétrica através da matéria, pelo método de Monte Carlo. Foram executadas simulações computacionais reprodutivas de radioterapia por próton baseada em instalações pré-existentes. RESULTADOS: Os dados das simulações foram integrados ao modelo de olho através do código SISCODES, para geração das distribuições espaciais de doses. Perfis de dose em profundidade reproduzindo o pico de Bragg puro e modulado são apresentados. Importantes aspectos do planejamento radioterápico com prótons são abordados, como material absorvedor, modulação, dimensões do colimador, energia incidente do próton e produção de isodoses. CONCLUSÃO: Conclui-se que a terapia por prótons, quando adequadamente modulada e direcionada, pode reproduzir condições ideais de deposição de dose em neoplasias oculares. Abstract in english OBJECTIVE: The present study proposes the evaluation of the depth-dose profiles and the spatial distribution of radiation dose for ocular proton beam radiotherapy protocols, based on computer simulations in nuclear codes and an eye model discretized into voxels. MATERIALS AND METHODS: The employed c [...] omputational tools were Geant4 (GEometry ANd Tracking) Toolkit and SISCODES (Sistema Computacional para Dosimetria em Radioterapia - Computer System for Dosimetry in Radiotherapy). Geant4 is a toolkit for simulating the passage of particles through the matter, based on Monte Carlo method. Computer simulations of proton therapy were performed based on preexisting facilities. RESULTS: Simulation data were integrated into SISCODES on the eye's model generating spatial dose distributions. Dose depth profiles reproducing the pure and modulated Bragg peaks are presented. Relevant aspects of proton beam radiotherapy planning are considered such as material absorber, modulation, collimator dimensions, incident proton energy and isodose generation. CONCLUSION: The conclusion is that proton therapy when properly modulated and directed can reproduce the ideal conditions for the dose deposition in the treatment of ocular tumors.

  9. A model study on the absorbed dose of radiation following respiratory intake of 238U3O8 aerosols.

    Science.gov (United States)

    Canepa, Carlo

    2014-12-01

    Aerosols of depleted uranium oxides, formed upon high-energy impact of shells on hard targets during military operations, are able to disperse, reach the alveolar region of the lungs and be absorbed and distributed throughout various parts of the body. The absorbed particles are subjected to clearance in the upper respiratory tract, distribution to other body districts, dissolution and excretion. While the soluble forms of uranium are known to deliver a small dose of radiation to the body due to their homogeneous distribution and the low specific activity of (238)U, ceramic particles exhibit a low dissolution rate and irradiate a limited volume of tissue for a long time with alpha particles with an energy of 4.267 MeV. The extent of the irradiated tissues depends on the radius of the particles and the total intake of uranium oxides. For the measured intake of U3O8 of a war veteran (15.51 ?g) the number of particles ranges from 5.56×10(4) to 6.95×10(6) for sizes of 0.4-2.0 ?m. Modelling the distribution of the particles between two compartments of the body, the averaged dose absorbed in 20 y by tissues surrounding the particles and within the range of the alpha particles varies from 6.8 mGy to 0.85 Gy for lungs and 8.1 mGy to 1.0 Gy for the lymph nodes, respectively. Correspondingly, due to the clearance and redistribution, the mass irradiated by 2.0-?m particles falls in 20 y from 6.06 mg to 0.94 ?g in the lungs and grows from 0 to 1.0 mg in the lymph nodes. The estimated rate of formation of hydroxyl radicals upon radiolysis of water in the lungs and lymph nodes is 5.17×10(4) d(-1) per cell after 1 y. PMID:24578528

  10. Contrast-enhanced radiotherapy: feasibility and characteristics of the physical absorbed dose distribution for deep-seated tumors

    International Nuclear Information System (INIS)

    Radiotherapy using kilovoltage x-rays in conjunction with contrast agents incorporated into the tumor, gold nanoparticles in particular, could represent a potential alternative to current techniques based on high-energy linear accelerators. In this paper, using the voxelized Zubal phantom in conjunction with the Monte Carlo code PENELOPE to model a prostate cancer treatment, it is shown that in combination with a 360 deg. arc delivery technique, tumoricidal doses of radiation can be delivered to deep-seated tumors while still providing acceptable doses to the skin and other organs at risk for gold concentrations in the tumor within the range of 7-10 mg-Au per gram of tissue. Under these conditions and using a x-ray beam with 90% of the fluence within the range of 80-200 keV, a 72 Gy physical absorbed dose to the prostate can be delivered, while keeping the rectal wall, bladder, skin and femoral heads below 65 Gy, 55 Gy, 40 Gy and 30 Gy, respectively. However, it is also shown that non-uniformities in the contrast agent concentration lead to a severe degradation of the dose distribution and that, therefore, techniques to locally quantify the presence of the contrast agent would be necessary in order to determine the incident x-ray fluence that best reproduces the dosimetry obtained under conditions of uniform contrast agent distribution.

  11. Tumoral fibrosis effect on the radiation absorbed dose of (177)Lu-Tyr(3)-octreotate and (177)Lu-Tyr(3)-octreotate conjugated to gold nanoparticles.

    Science.gov (United States)

    Azorín-Vega, E P; Zambrano-Ramírez, O D; Rojas-Calderón, E L; Ocampo-García, B E; Ferro-Flores, G

    2015-06-01

    The aim of this work was to evaluate the tumoral fibrosis effect on the radiation absorbed dose of the radiopharmaceuticals (177)Lu-Tyr(3)-octreotate (monomeric) and (177)Lu-Tyr(3)-octreotate-gold nanoparticles (multimeric) using an experimental HeLa cells tumoral model and the Monte Carlo PENELOPE code. Experimental and computer micro-environment models with or without fibrosis were constructed. Results showed that fibrosis increases up to 33% the tumor radiation absorbed dose, although the major effect on the dose was produced by the type of radiopharmaceutical (112Gy-multimeric vs. 43Gy-monomeric). PMID:25305748

  12. Calorimetry for absorbed dose measurement at 1-4 MeV electron accelerators

    International Nuclear Information System (INIS)

    Calorimeters are used for dose measurement, calibration and intercomparisons at industrial electron accelerators, and their use at 10 MeV electron accelerators is well documented. The work under this research agreement concerns development of calorimeters for use at electron accelerators with energies in the range of 2-4 MeV. The dose range of the calorimeters is 3-40 kGy, and their temperature stability after irradiation was found to be sufficient for practical use in an industrial environment. Measurement uncertainties were determined to be 5% at k = 2. (author)

  13. Thyroid dose of I-131 absorbed by the internal organs of a pregnant woman

    International Nuclear Information System (INIS)

    The use of nuclear techniques, for diagnosis or treatment, generates stress in the patient and its relatives. During the pregnancy some sufferings related with the thyroid gland can be presented. If the patient is pregnant, OEP or NOEP, the stress comes from the fear to that the product can it turns affected. The dose is calculated that the Iodine 131, captured by the thyroid of a woman with three months of pregnancy, it deposits in the brain, stomach, heart, kidneys, liver, lungs, ovaries, pancreas, thymus, spleen and in the uterus. The thymus is the organ that receives the biggest dose. (Author)

  14. Radiation characteristics and absorbed dose distribution in biological phantoms in the thermal neutron field in a nuclear reactor

    International Nuclear Information System (INIS)

    The thermal neutron capture therapy using the thermal neutrons from nuclear reactors is expected to produce its successful results because it can apply a large amount of radiation energy focusing to the diseased parts of living bodies and the radiation exposure to normal tissues is few. The completion and practice of this therapy involve four problems, on which the fundamental research has been carried out. The first is the problem of thermal neutron irradiation field, in which it is required that reactor bodies contain little ?-ray and provision must be made to thermalize and extract neutrons by fully moderating fast neutrons. In the neutron thermalizing facility with heavy water in the Kyoto University Reactor, thermal neutron flux of (3 to 4) x 109 n/cm2.sec and ?-dose of 100 to 150 R/h are obtained at present, supplying a fairly good, low-? thermal neutron irradiation field. The second is the problem of thermal neutron collimators requiring to satisfy several conditions. It is preferable that the secondary ? generation is small, therefore Li-containing LiF tiles or LiF polyester may be better as collimator materials, and graphite or teflon for the support. The third and fourth are the problems to measure the irradiation field for medical use and doses absorbed in living bodies. If the irradiation of human bodies is considered in biological phantom experiments, the secondarily generated ?-ray by thermal neutrons is dominant in the absorbed dose into diseased parts because the object to be irradiated is large. (Wakatsuki, Y.)

  15. Whole-body biodistribution, radiation absorbed dose and brain SPECT imaging with iodine-123-?-CIT in healthy human subjects

    International Nuclear Information System (INIS)

    SPECT imaging with 123I-labeled methyl 3?-(4-iodophenyl)tropane-2?-carboxylate ([123I]?-CIT) in nonhuman primates has shown brain striatal activity, which primarily reflects binding to the dopamine transporter. The biodistribution and calculated radiation-absorbed doses of [123]?-CIT administered to eight healthy subjects were measured with attention to the accurate determination of organ time-activity data. Whole-body transmission images were obtained with a scanning line source for attenuation correction of the emission images. Following administration of 92.5 ± 22.2 MBq (2.5 ± 0.6 mCi) of [123I]?-CIT, subjects were imaged with a whole-body imager every 30 min for 3 hr, every 60 min for the next 3 hr and at 12, 24 and 38 hr postinjection. Regional body conjugate counts were converted to microcuries of activity, with a calibration factor determined in a separate experiment using a distributed source of 123I. The peak brain uptake represented 14% of the injected dose, with 2% of the activity approximately overlying the striatal region. Highest radiation-absorbed doses were to the lung (0.1 mGy/MBq, 0.38 rads/mCi), liver (0.087 mGy/MBq, 0.32 rads/mCi) and lower large intestine (0.053 mGy/MBq, 0.20 rads/mCi). Iodine-123-?-CIT is a promising SPECT agent for imaging of the dopamine transporter in humans with favorable dosimetry and high brain uptake. 18 refs., 4 figs., 5 tabs

  16. Developing point of care and high-throughput biological assays for determining absorbed radiation dose

    International Nuclear Information System (INIS)

    Background and purpose: Systems are being developed to assess radiation exposure based on leukocyte mRNA levels obtained by finger-stick sampling. The goal is to provide accurate detection of dose exposures up to 10 Gy for up to 1 week following exposure. We previously showed that specific mRNA sequences increase expression within an hour of exposure, and some genes continue to show elevated expression for at least 24 h. Full duration and dose-dependence of this persistence remain to be determined. In the present study, real-time quantitative PCR (qPCR) was used to determine changes in gene expression. qPCR can rapidly analyze small blood samples and could be adopted into a field-portable instrument that provides a radiation dose readout within 30 min. Materials and methods: From previous microarray analysis of 21,000 genes expressed in human lymphoblastoid cells 4 h post-irradiation (0–4 Gy), 118 genes were selected for evaluation by qPCR of gene expression in the leukocytes of human blood irradiated in vitro with doses of 0–10 Gy from a Co-60 gamma source at a dose rate of 30 cGy/min. Results: Blood from 20 normal healthy human donors yielded many mRNA sequences that could be used for radiation dosimetry. We observed four genes with large and persistent responses following exposure: ASTN2, CDKN1A, GADD45A, and GDF15. Five genes were identified as reliably non-responsive and were suitable for use as endogenous controls: DPM1, ITFG1, MAP4, PGK1, and SLC25A36; of t ITFG1, MAP4, PGK1, and SLC25A36; of these, ITFG1 was used for the analyses presented here. A significant dose-responsive increase in expression occurred for CDKN1A that was >16-fold at 10 Gy and 3-fold at 0.5 Gy compared to pre-irradiation values. Conclusions: These data show large, selective increases in mRNA transcript levels that persist for at least 48 h after single exposures between 0.5 and 10 Gy. Stable, non-responsive mRNA sequences for use as endogenous controls were also identified. These results indicate that following further study to establish the most reproducible gene and dose–response models under a wide range of conditions in vivo, rapid real-time qPCR on blood samples could potentially be used to establish biologically-effective dosimetry from either accidental irradiation or clinical radiotherapy.

  17. Evaluation of Absorbed Dose of Critical Organ in Rando Phantom under Head, Abdomen and Pelvis Spiral CT Scan by Thermo Luminescent Dosimetery - TLD

    Directory of Open Access Journals (Sweden)

    Gholamhosein Haddadi

    2011-12-01

    Full Text Available Background & Objectives: Computed tomography (CT represents 11% of all diagnostic radiology procedures but it contributes to almost 67% of the total effective dose to the human population. In head and neck CT which consist of 1/3 of total CT scans, other critical organs such as lenses and thyroid are in the radiation field. Also in the abdomen and pelvis scan, irradiation of ovaries is unavoidable. Because of high sensitivity of these organs, the probability of abnormality and cancer in these organs has increased. Therefore the dose assessment in these organs is very important. The aim of this study is to estimate the absorbed dose in critical organ of patient undergoing common head, neck, abdomen and pelvic spiral CT scan. Materials & Methods: In this study, Lithium fluoride thermo luminescent dosimeters (TLD-100, Harshaw were used to determine the absorbed dose of critical organ of tissue equivalent rando phantom (Alderson research industries, Inc, Stanford, Conn, U.S.A. The phantom was sectional in design and manufactured with a 2.5 cm slab thickness. Each section contained some holes that allowed accommodation of TLDs. At least two crystals were placed in each hole. The average value of the TLD readings was taken as the organ dose. Readouts were obtained on a Harshaw 4500 reader (Harshaw, Ohio, USA. For calibration, the annealed dosimeters were exposed to an X-ray beam resulting from 120 kVp tube voltage and calibration curve was plotted. Results: result of this study showed during head CT scan the maximum absorbed dose belongs to occipital bones skin. Which were about 11.45 mGy and the minimum absorbed dose belong to thyroid gland which was 0.5 mGy. During abdomen & pelvic spiral CT, the maximum absorbed dose of abdomen skin was 23.32 mGy and the minimum absorbed dose in the eye region was 0.15 mGy. The readout results are correlated with the results of spiral CT detector with the “ALARA” principle, we recommend suitable techniques should be selected to reduce absorbed dose of critical organ without reducing image quality. Conclusion: further research is required to investigate whether modification of the parameters used during routine spiral CT scan can be limited absorbed dose of critical organ without a significant loss of image quality.

  18. Incase of Same Region Treatment by using a Tomotherapy and a Linear Accelerator Absorbed Dose Evaluation of Normal Tissues and a Tumor

    International Nuclear Information System (INIS)

    Treating same region with different modalities there is a limit to evaluate the total absorbed dose of normal tissues. The reason is that it does not support to communication each modalities yet. In this article, it evaluates absorbed dose of the patients who had been treated same region by a tomotherapy and a linear accelerator. After reconstructing anatomic structure with a anthropomorphic phantom, administrate 45 Gy to a tumor in linac plan system as well as prescribe 15 Gy in tomotherapy plan system for make an ideal treatment plan. After the plan which made by tomoplan system transfers to the oncentra plan system for reproduce plan under the same condition and realize total treatment plan with summation 45 Gy linac treatment plan. To evaluate the absorbed dose of two different modalities, do a comparative study both a simple summation dose values and integration dose values. Then compare and analyze absorbed dose of normal tissues and a tumor with the patients who had been exposured radiation by above two different modalities. The result of compared data, in case of minimum dose, there are big different dose values in spleen (12.4%). On the other hand, in case of the maximum dose, it reports big different in a small bowel (10.2%) and a cord (5.8%) in head and neck cancer patients, there presents that oral (20.3%), right lens (7.7%) in minimum dose value. About maximum dose, it represents that spinal (22.5), brain stem (12%), optic chiasm (8.9%), Rt lens (11.5%), %), optic chiasm (8.9%), Rt lens (11.5%), mandible (8.1%), pituitary gland (6.2%). In case of Rt abdominal cancer patients, there represents big different minimum dose as Lt kidney (20.3%), stomach (8.1%) about pelvic cancer patients, it reports there are big different in minimum dose as a bladder (15.2%) as well as big different value in maximum dose as a small bowel (5.6%), a bladder (5.5%) in addition, making treatment plan it is able us to get. In case of comparing both simple summation absorbed dose and integration absorbed dose, the minimum dose are represented higher as well as the maximum dose come out lower and the average dose are revealed similar with our expected values data. It is able to evaluate tumor and normal tissue absorbed dose which could had been not realized by treatment plan system. The DVH of interesting region are prescribed lower dose than expected. From now on, it needs to develop the new modality which are able to realize exact dose distribution as well as integration absorbed dose evaluation in same treatment region with different modalities.

  19. Determination of absorbed dose in body inhomogeneities such as lung, bone and fat tissue for neutron therapy

    International Nuclear Information System (INIS)

    Dose distribution calculations for an 'inhomogeneous' patient have been performed for cyclotron and 14 MeV neutron therapy facilities using radiation transport programs. Precise dose determination in the patient is very important for the success of neutron therapy. The results were evaluated and transformed into inhomogeneity correction factors appropriate for treatment-planning code systems. The kerma distribution is represented by an analytical formula. For each kind of tissue two inhomogeneity correction factors are needed; these transform the neutron and gamma dose measured in a homogeneous water phantom by a tissue-equivalent detector to the specific values of the patient. The first correction factor adjusts the water attenuation coefficient in the exponential part of the dose formula to that of the patient, and the second factor corrects the kerma from TE gas to the particular human tissue being considered. It is the second factor that is responsible for the jump or discontinuity in the absorbed dose of about 25% between soft tissue and bone or for the 14% increase of kerma in fat tissue. Various sets of inhomogeneity factors were provided, and these are stored in tabular form in the code. The external and internal contours of a patient can be derived from CT images. The user of the code has to identify the kind of tissue for each inhomogeneity volume using a specified code name. Additionally, individual CT numbers can be supplied to characterize, for example, te supplied to characterize, for example, the density and mineral content of bone, the density and water content of the lung, or the density and fat content of critical skin regions. According to the CT number given, fine adjustments of the correction factors can be used to describe the inhomogeneity effects individually for each patient. (author)

  20. Absorbed dose calorimetry with a graphite calorimeter, and G-value determinations for the Fricke dose meter in high-energy electron beams

    International Nuclear Information System (INIS)

    A graphite calorimeter has been constructed to the design of the heat-loss-compensated NBS calorimeter. The modified bridge and measuring electronics are described. Its performance was thoroughly analysed by comparison of experimental results with theoretical expectations. Special attention was given to the methods used for experimental heat-loss correction. Highly reproducible G-values for the Fricke dose meter have been measured with the calorimeter as absorbed dose standard in different electron beams. Polystyrene-coated graphite irradiation cells were constructed with small zero-dose effects and negligible wall effect at irradiation. The effect of vacuum gaps in the calorimeter was measured by gap simulation around Fricke cells with thin polystyrene-coated paper walls. Our G-value (1.604x10-6 mol.kg-1.Gy-1) and molar extinction coefficient epsilon3+sub(Fe) (217.44 m2.mol-1) are both 1.5% smaller than the ICRU recommendations, yielding a 3% lower value for the product epsilon G to be used in practical dosimetry. (author)

  1. Internal absorbed dose estimation by a TLD method for 18F-FDG and comparison with the dose estimates from whole body PET

    International Nuclear Information System (INIS)

    The thermoluminescent dosimeter (TLD) method has been proposed as a useful tool for estimating internal radiation absorbed dose in nuclear medicine. An efficient approach to verify the accuracy of the TLD method has been performed in this study. Under the standard protocol for 2-[F-18]fluoro-2-deoxy-D-glucose (18F-FDG), whole body PET experiments and simultaneous body surface dose measurements by TLDs were performed on six normal volunteers. By using the body surface dose measured with TLDs, the cumulated activities of nine source organs were estimated with a mathematical unfolding technique for three different initial guesses. The accuracy of the results obtained by the TLD method was investigated by comparison with the actual cumulated activity of the same source organs measured by whole body PET. The cumulated activities of the source organs obtained by the TLD method and whole body PET show a significant correlation (correlation coefficient, r>0.98, level of confidence, p-2 mSv MBq-1 obtained from the TLD method and 2.9x10-2 mSv MBq-1 obtained from the whole body PET. Good agreement between the results of the TLD method and whole body PET was observed. (author)

  2. Quantitative detection of absorbed dose of irradiated dried fruit by ESR spectroscopy method

    International Nuclear Information System (INIS)

    Sunflower seeds, walnuts, pistachios, and hazelnuts were used as experimental materials which were irradiated at 1.0, 3.0, 5.0 and 10.0 kGy, respectively. The relationships and correlations between ESR signal intensity and irradiation dosages were studied. The results showed that ESR spectra of irradiated samples were obviously different from that of CK, and the ESR signal intensity was positively related with the irradiation dose. After irradiation, the ESR intensity and spectrum shapes all changed and all four samples were clearly identified irradiated or unirradiated. The appearances of the two weak satellite lines which situated left and right to the intense singlet line in walnuts and pistachios proved the existence of cellulose radical. The detection dose limit of irradiated walnut was 1 kGy, and the detection limits of the other three samples were lower than 1 kGy. In conclusion, the ESR method could be used to irradiated. (authors)

  3. Population characteristics and absorbed dose to the population from nuclear medicine: United States--1982

    International Nuclear Information System (INIS)

    Those in the U.S. population who receive nuclear medicine examinations have been characterized by age and sex. Males received 42% of examinations while females received 58%. More than one-third of the examinations were done on persons older than 64 y of age and more than two-thirds on patients older than 45 y of age. The per caput effective dose equivalent from nuclear medicine procedures in 1982 was 140 muSv (14 mrem); whereas, the per caput age-specific effective dose equivalent to the U.S. population was 50 muSv (5.9 mrem). These can be compared with 2 mSv (200 mrem) from natural background

  4. Simulations of absorbed dose on the phantom surface of MATROSHKA-R experiment at the ISS.

    Czech Academy of Sciences Publication Activity Database

    Kolísková, Zlata; Sihver, L.; Ambrožová, Iva; Sato, T.; Spurný, František; Shurshakov, V. A.

    2012-01-01

    Ro?. 49, ?. 2 (2012), s. 230-236. ISSN 0273-1177 R&D Projects: GA ?R GA205/09/0171; GA AV ?R KJB100480901; GA ?R GD202/09/H086 Institutional research plan: CEZ:AV0Z10480505 Keywords : MATROSHKA-R * PHITS * Simulations * Space radiation * Dose estimation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.183, year: 2012

  5. Comparison of methods for absorbed dose determination in clinical blood product irradiators

    International Nuclear Information System (INIS)

    Clinical blood product irradiators (CBPI's) are found mainly in haematology Departments and Blood Banks. Their purpose is to irradiate whole blood and blood products prior to transfusion into immunosuppressed patients. The aim of this action is to eradicate the lymphocyte population and remove the risk of graft versus host disease (GVHD) in the recipient. Numbers of CBPI's are gradually increasing and as quality issues become more important in the medical field, users are keen to ensure that the specifications of absolute and relative dosimetry, as provided by manufacturers are accurate. Medical Physics Departments are often approached to perform such confirmatory measurements. CBPI's usually contain caesium-137 sources, typically of several tens of TBq activity. This work compares results of absolute dose rates determined in 2 different CBPI's using TLD, Fricke and Alanine Dosemeters and a method for determining the dose distribution throughout the above irradiation cells is presented. In one case, a substantial deviation from the manufacturers specification was found. The effects of 'partial' irradiation cell filling are discussed. Aspects of commercially available dose verification devices based on radiochromic film and MOSFET technology are considered

  6. Use of PET Images in Assessment of Brain Absorbed Dose of Patients Undergoing [C-11] Raclopride Positron Emission Tomography

    International Nuclear Information System (INIS)

    The positron emission tomography (PET) in combination with [C-11] raclopride is commonly used for early detection of the Parkinson's disease. Injection of considerable amount of radioactivity, typically 300?500 MBq of [C-11] at a time, for the examination calls for attention to doses to tissues of the patient, particularly to the brain. Since [C-11] raclopride is not a common radiopharmaceutical, dosimetric data for internal dose evaluation are rare yet. In this study, an attempt was made to determine doses to the brain and the striatum of patients by use of the PET images obtained for the clinical purposes. Four informed patients suffering Parkinson's disease participated in this study. Time series of 18 frames, 35 slices in each frame, of PET images of the head were obtained. By transforming the pixel intensity in the assigned region of interests into radioactivity contents, the retention curves were constructed to evaluate the residence times. Absorbed doses to the target tissues were calculated by applying the S-values given in the MIRDOSE3.1 code. The resulting dose coefficients for the whole brain and the striatum were 0.0110±0.0016 mGy/MBq and 0.0664±0.0238 mGy/MBq, respectively. The brain dose coefficient is considerably higher than the corresponding values in other studies employing healthy subjects. This may be attributed to probable enhanced capture of [C-11] raclopride by the dopamine D2 receptors in case of subjects with Parkinson's diseasee of subjects with Parkinson's disease. The transcrianial magnetic stimulation (TMS) procedures are often used in treatment of Parkinson's disease. If the procedure stimulates secretion of dopamine, less retention of [C-11] raclopride is expected due to competition. So the similar assessments were made for the same patients after TMS treatments. Disappointingly, the ratios of residence time without TMS to that with TMS were 0.943±0.074 and 0.98±0.14 for the brain and the striatum, respectively. For the striatum, the ratios for three patients were greater than 1.0 but for the rest one patient, for whom TMS treatment showed little effects on the symptom, extraordinary value(0.78) was observed. Injection of around 400 MBq of [C-11] raclopride resulted in the total absorbed doses of approximately a few mGy to the brain and a few tens of mGy to the striatum. These dose levels, together with the expected effective dose of 1?2mSv, can be justifiable when importance of early detection of the disease in taken into account. Although the developed methodology was successfully applied to dosimetry of brain tissues of patients undergoing PET scans with [C-11] raclopride, there remain marked uncertainties in the results due to limited number of subjects. Successive studies involving larger sample size are needed to refine the outcome of this study. In particular, analysis of clinical data from subjects revealed without Parkinson's disease would provide results directly comparable with other studies and identify effects of the disease

  7. A test of the IAEA code of practice for absorbed dose determination in photon and electron beams

    International Nuclear Information System (INIS)

    The IAEA Code of Practice TRS 277 gives recommendations for absorbed dose determination in high energy photon and electron beams based on the use of ionisation chambers calibrated in terms of exposure or air kerma. The scope of the present work was to test the Code for 60Co gamma radiation and for several radiation qualities at four different types of electron accelerators and to compare the ionisation chamber dosimetry with ferrous sulphate dosimetry. The results show agreement between the two methods within about one per cent for all the investigated qualities. In addition the response of the TLD capsules of the IAEA/WHO TL dosimetry service has been determined. (Authors) 5 refs., 9 tabs., 3 figs

  8. Definition of spatial distribution of the absorbed dose of ?-radiation source 60Co for installation URI

    International Nuclear Information System (INIS)

    The study of energy distribution among different objects (as well as forms of energy absorption in them) being researched in radiation chemistry, radiobiology and micro-dosimetry has become one of the actual problems recently. Impossibility of practical parameters definition makes the theoretical solution of the problem one of the major tasks in this field. The most probable primary processes of interaction the ?-radiation with subjects of inquiry are Compton dispersion and photoeffect. Therefore in this work on the base of Compton dispersion and photoeffect an entire spectrum of dispersive ?-quanta and ?-electrons formed in the result of monoenergetic ?-quanta interaction with different media (gaseous, liquid, solid) is calculated. The flux density of ?-quanta in any part of cylindrical working volume is determined. Section of interaction of monoenergetic ?-quanta with the medium is calculated by the equation of Klein-Nishina-Tamm and Bete. Depending on energy spectrum of ?-electrons obtained in the result of the interaction their average energy is determined by means of stepping method. Interaction process cross-sectional of ?-electrons with the medium is determined by the equation of Grizinsky. The account proceeded up to value of ?-electrons energy approached to value of medium ionization energy. Dose rate received by a calculation way on the formula: P = k·?i (k - the constant of transition from density of a flow to a dose) to within ±5 % cow to a dose) to within ±5 % coincides with experimental values. The account was carried out on the basis of installations available in Section of Radiation Researches National Academy of Science of Azerbaijan, and on the basis of the mathematical program Mathcad

  9. Monte Carlo Simulation Of Absorbed Dose From LINAC On VOXEL Phantom By Using MCNP5 Code

    International Nuclear Information System (INIS)

    In this work, we use MCNP5 code for simulating dose distribution calculation from LINAC on phantom CT. CT images obtained from cancer treatment cases at Cho Ray hospital. In order to transform CT images into data of MCNP5 input file we also build a program CODIM by using MATLAB programming software. The results show that there is a difference of 5% in comparison to DSS program - a semi-empirical simulation program which is being used for treatment planning in Cho Ray hospital. (author)

  10. Radon concentration, absorbed dose rate in air and concentration of natural radionuclides in soil in the Osaka district of Japan

    International Nuclear Information System (INIS)

    Radon concentrations in outdoor air at 18 sites in the Osaka district, in the central part of Japan's main island, were measured with electrostatic integrating radon monitors which were developed by Y Ikebe et al of the Osaka survey centre as part of a nationwide survey of radon indoors and outdoors in Japan conducted by the National Institute of Radiological Science. The mean radon concentration in outdoor air during 2-month periods was measured over a period of a year and a half. In addition, the absorbed dose rate in air and the concentration of natural radionuclides in soil were measured at 40 sites in Osaka Prefecture which is located in the central part of the Osaka district using thermoluminescence dosemeters and with gamma ray spectrometry, respectively. Radon concentration in outdoor air showed a seasonal pattern, reaching its maximum during the winter and its minimum during the summer, but this variation was not significant at the coastal sites. It was concluded that this variation is correlated with a seasonal wind which blows from the continental interior to the ocean in winter and in the opposite direction in summer, as well as with geographical factors. Radon concentration in outdoor air in the Osaka district ranged from 0.6 to 17.9 Bq.m-3 and mean annual radon concentration in outdoor air at the 18 sites ranged from 2.7 to 6.9 Bq.m-3. It was discovered that radon concentration in outdoor air decreased with wind speed in both winterr decreased with wind speed in both winter and summer. The absorbed dose rate in air ranged from 66 to 114 nGy.h-1, and the concentration of 226Ra in soil ranged from 20 to 60 Bq.kg-1 respectively. (author)

  11. Calculation of factors to convert from air kerma to absorbed dose to water for medium energy photons

    International Nuclear Information System (INIS)

    The IPEMB code of practice for the determination of absorbed dose for X-rays below 300 kV generating potential is a dedicated dosimetry protocol for the determination of absorbed dose based on the air kerma evaluation method for medium energy X-rays. Three separate energy ranges are dealt with in the code of practice, however, this report is only attempting to reproduce the factors in one particular range (0.5 - 4.0 nun Cu HVL) for X-rays generated at 135 and 280 kV. These X-ray qualities are used in the NPL therapy level calibration service. This new method includes the use of an air kerma calibration factor, NK, for the ionisation chamber, and the ratio of the mass-energy absorption coefficients of water to air and factors that account for the change in the response of a NE2561 ionisation chamber between calibration in air and measurement in a water phantom, kch, instead of the old F factor. This report describes the work that was undertaken to reproduce the product of the ratio of the mass-energy absorption coefficients of water to air and the kch factors. The majority of this work was carried out using Monte Carlo techniques based on the EGS4 code system. The factors calculated in this report were found to agree with values quoted in the IPEMB code of practice to within 4.2%. The quoted uncertainty for this work is 1.4% and the uncertainties for the factors quoted in the EPEMB code of practice are 3%. Hence this is reasonable agreeice are 3%. Hence this is reasonable agreement. Possible discrepancies in the values may be due either to limitations in the EGS4 code system, simplifications made in the chamber geometry or on the reliance on experimental data which is not quite applicable to its' use in this work. (author)

  12. The development of early pediatric models and their application to radiation absorbed dose calculations

    International Nuclear Information System (INIS)

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations. The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 - about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The open-quotes pediatricclose quotes models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing open-quotes individualclose quotes pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. are discussed

  13. Human absorbed dose calculations for 123I labeled phenyl pentadecanoic acid

    International Nuclear Information System (INIS)

    I-123 labeled fatty acids have been proposed for studying myocardial metabolism by scintigraphic methods. With the availability of clean I-123 and the advent of single photon emission tomography, I-123 labeled fatty acids would be well suited to study regional myocardial viability or metabolism in humans. The authors have studied I-125 and I-123 labeled iodophenyl pentadecanoic acid (IPPA) in rats and dogs. Clinical studies are in progress with I-123 (IPPA). They have studied the pharmacokinetics of this tracer in male Sprague-Dawley rats at 0.25, 0.5, 1, 3, 6, and 24 hours postinjection. The cumulated doses, due to both pure I-123 and a version contaminated with 1.4% I-125, in various organs and the total body in humans are estimated. The average dose to organs for humans injected with I-123 IPPA with pure I-123 and contaminated I-123 respectively, are (rads to organ per mCi injected): heart wall (0.0507, 0.0514), liver (0.0792, 0.0875), kidneys (0.0479, 0.0561), thyroid (0.0517, 0.0638), ovaries (0.0427, 0.0561), testes (0.0307, 0.0309), total body (0.0386, 0.0392). 12 references, 9 figures, 5 tables

  14. The development of early pediatric models and their application to radiation absorbed dose calculations

    International Nuclear Information System (INIS)

    This presentation will review and describe the development of pediatric phantoms for use in radiation dose calculations . The development of pediatric models for dose calculations essentially paralleled that of the adult. In fact, Snyder and Fisher at the Oak Ridge National Laboratory reported on a series of phantoms for such calculations in 1966 about two years before the first MIRD publication on the adult human phantom. These phantoms, for a newborn, one-, five-, ten-, and fifteen-year old, were derived from the adult phantom. The ''pediatric'' models were obtained through a series of transformations applied to the major dimensions of the adult, which were specified in a Cartesian coordinate system. These phantoms suffered from the fact that no real consideration was given to the influence of these mathematical transformations on the actual organ sizes in the other models nor to the relation of the resulting organ masses to those in humans of the particular age. Later, an extensive effort was invested in designing ''individual'' pediatric phantoms for each age based upon a careful review of the literature. Unfortunately, the phantoms had limited use and only a small number of calculations were made available to the user community. Examples of the phantoms, their typical dimensions, common weaknesses, etc. will be discussed

  15. Real time monitoring automation of dose rate absorbed in air due to environmental gamma radiation

    International Nuclear Information System (INIS)

    The Center of Radiation Protection and Hygiene (CPHR) as the head institution of the National Radiological Environmental Surveillance Network (RNVRA) has strengthened its detection and response capacity for a radiological emergency situation. The measurements of gamma dose rate at the main point of the RNVRA are obtained in real time and the CPHR receives the data coming from those points in a short time. To achieve the operability of the RNVRA it was necessary to complete the existent monitoring facilities using 4 automatic gamma probes, implementing in this way a real time measurement system. The software, GenitronProbe for obtaining the data automatically from the probe, Data Mail , for sending the data via e-mail, and Gamma Red , for receiving and processing the data in the head institution ,were developed

  16. Modeling the absorbed dose to the common carotid arteries following radioiodine treatment of benign thyroid disease

    DEFF Research Database (Denmark)

    la Cour, Jeppe Lerche; Hedemann-Jensen, Per

    2013-01-01

    External fractionated radiotherapy of cancer increases the risk of cardio- and cerebrovascular events, but less attention has been paid to the potential side effects on the arteries following internal radiotherapy with radioactive iodine (RAI), i.e. 131-iodine. About 279 per million citizens in the western countries are treated each year with RAI for benign thyroid disorders (about 140,000 a year in the EU), stressing that it is of clinical importance to be aware of even rare radiation-induced side effects. In order to induce or accelerate atherosclerosis, the dose to the carotid arteries has to exceed 2 Gy which is the known lower limit of ionizing radiation to affect the endothelial cells and thereby to induce atherosclerosis.

  17. Influence of post-harvest irradiation time and absorbed dose to potatoes and onions

    International Nuclear Information System (INIS)

    Post harvest losses of potatoes and onions were mainly due to sprouting and rotting. Irradiation dose of 50 Gy for onions and of 100 Gy for potatoes applied within the dormancy period effectively inhibited sprouting. In Vietnam conditions the optimal irradiation time after harvest is 3 - 6 weeks for potatoes, within 4 weeks for onions. Irradiated potatoes and onions stored under ambient conditions tend to be more spoiled in comparison with unirradiated ones.Irradiation caused a slight decrease of vitamin C content and an increase of reduced sugars and total sugars for potatoes and onions stored under room temperature. There are no changes in main nutritional properties of irradiated onions, no after-cooking discoloration in irradiated potatoes. (author). 8 refs, 4 tabs, 9 figs

  18. New standards of absorbed dose to water under reference conditions by graphite calorimetry for 60Co and high-energy X-rays at LNE-LNHB

    International Nuclear Information System (INIS)

    The LNE-LNHB has developed two primary standards to determine the absorbed dose to water under reference conditions (for 10 cm * 10 cm) in 60Co, 6 MV, 12 MV and 20 MV photon beams: a new graphite calorimeter and a water calorimeter. This first paper presents the results obtained with the graphite calorimeter and the new associated methodology. The associated relative standard uncertainty (k = 1) of absorbed dose to water is 0.25% for 60Co and lies between 0.32% to 0.35% for MV X-ray beams. (authors)

  19. DOSIS: a computer program for the calculation of absorbed dose in photon and electron beams from ionization measurements in a phantom

    International Nuclear Information System (INIS)

    A computer program has been developed to facilitate the calculation of the absorbed dose in photon and electron beams from measurements with an ionization chamber in a phantom. The generalized Bragg-Gray theory, introduced in the latest recommendations of the Nordic Association of Clinical Physics (NACP), is used throughout the code, including more updated parameter values than those included in the NACP protocol. The calibration factor of the ionization chamber in units of absorbed dose in the air of the cavity can be derived for most of the chambers available today by using experimental data or fitted relations to Monte Carlo results. (orig.)

  20. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    Science.gov (United States)

    Bakar, Khomsaton Abu; Ahmad, Pauzi; Zulkafli, Hashim, Siti A'aisah

    2014-09-01

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  1. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    International Nuclear Information System (INIS)

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD5, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively

  2. Degradation and decoloration of textiles wastewater by electron beam irradiation: Effect of energy, current and absorbed dose

    Energy Technology Data Exchange (ETDEWEB)

    Bakar, Khomsaton Abu; Zulkafli,; Hashim, Siti A' aisah [Malaysian Nuclear Agency (Nuclear Malaysia), Bangi 43000 Kajang Selangor (Malaysia); Ahmad, Pauzi [Universiti Kebangsaan Malaysia, 43600 UKM, Bangi Selangor (Malaysia)

    2014-09-03

    In this study, electron beam accelerator (EB) was used to treat textiles wastewater from Rawang Industrial Park, Selangor. The objectives were to determine effective energy, beam current and absorbed dose required for decoloration and degradation of the textiles effluent. The textiles effluent was irradiated in a batch with various energy of 1MeV to 3MeV at constant beam current of 30mA. It was observed that removal of color and COD increases with higher beam energy. The EB energy of 1MeV effectively to removed 58% color and 19% COD. For textile effluent sample irradiated at fix energy of 1MeV and 3Mev but at different beam current 10mA, 20mA and 30mA. It was observed that removal of color and COD increases with the increased of beam current at each energy. However removal of color was significantly better at 1Mev as compared to 3Mev. In the case of textiles effluent, irradiated at doses of 17, 20,25,30, 35, 100 and 200kGy using 30 kW power of EB (1Mev, 30mA), results shows removal of BOD{sub 5}, COD and color were in the range 9%-33%, 14%-38% and 43%-78% respectively.

  3. Early neuro-vegetative responses to head irradiation of the rabbit at mean absorbed doses of 1000 and 150 rads

    International Nuclear Information System (INIS)

    Head irradiation was studied in order to back up a previous assumption on the kinetics of vegetative responses to whole-body exposure: the earliest response might have a central origin and explain the slight increase of blood pressure, tachycardia, hyperthermia and hyperventilation. Following head exposure at a mean absorbed dose of 1000 rads, blood pressure increased on the 15 th min, reaching 0.8 - 1 cm Hg on the 30th min and during 7 - 8 hours. The increase of heart rate occured as early and was about 40% and lasted for 24 hours. Body temperature increased as early as the end of exposure, was highest within 2 - 2.30 hours and decreased on the 6th hour. Arterial blood showed a respiratory alkalosis on the 1st hour, lasting after the 6th hour and disappeared within 24 hours. At a dose of 150 rads, the changes were lasting but of lower importance and duration. The results show that early changes following whole-body exposure also occur after head exposure and are magnified. The kinetics involved are discussed

  4. Effect of external gamma-irradiation on life span of dogs and the rate of formation of absorbed doses from incorporated plutonium 239

    International Nuclear Information System (INIS)

    External ?-irradiation of dogs with doses of 103.2 and 51.6 mC/kg combined with the effect of inhaled plutonium 239 accelerates the formation of absorbed doses in secondary organs of the radionuclide deposition by 41.7 and 2.4 times, respectively, whereas the dose of 25.8 mC/kg is ineffective. As estimated by the rate of 239Pu accumulation and by the life span shortening the minimum effective and the maximum ineffective doses are 104.8 and 80.5 cGy and 89.2 and 79.2 cGy, respectively

  5. Measurement of the absorbed dose in the very small size photon beams used in stereotactic radiotherapy

    International Nuclear Information System (INIS)

    After the radiotherapy accident in Toulouse, the French authority of nuclear safety and the French agency of health products safety have asked the IR.S.N. to establish, together with experts from the French society of medical physics and the French society of radiotherapy and oncology, a national protocol on dose calibration for the very small beams used in stereotactic radiotherapy. The research and reflexions of the working group 'GT minifaisceaux ' set up by the I.R.S.N. are presented in this final report. A review of the international literature has been performed. A national survey has been done to know the present practices in the dosimetry of small fields. A campaign of measurements of the data needed to characterize the small beams for the different stereotactic systems has started, using different types of detectors acquired by the I.R.S.N.. In this report are presented a deep synthesis on the problems related to the dosimetry of small fields, the results of the national survey, the first results of the campaign of measurements and the recommendations of the GT. (authors)

  6. Study of dose levels absorbed by members of the public in the nuclear medicine departments

    International Nuclear Information System (INIS)

    In nuclear Medicine, radioisotopes are bound to various compounds (called radiopharmaceuticals) for use in various diagnostic and therapeutic applications. These unsealed sources are administered in various forms to patients, who remain radioactive for hours or days, and represent a source of potential radiation exposure for others. Thus, in nuclear medicine departments, radiation protection of workers and members of the public, especially persons accompanying patients, must consider, this exposure. In Brazil, the Comissao Nacional de Energia Nuclear (CNEN) establishes that, in nuclear medicine departments, the patients and persons accompanying should be separated each other. However, this rule is not always followed due to many factors such as physical and emotional conditions of patients. In this context, the aim of this study was the investigation of dose levels, which the persons accompanying patients are exposed to. For monitoring, thermoluminescent dosimeters were employed. The dosimeters were given to 380 persons who were accompanying patients in nuclear medicine departments. Exposure results were lower than 1 mSv. On the basis of CNEN rules, issues regarding stay conditions for members of the public in these departments are discussed. (author)

  7. Risk- and cost-benefit analyses of breast screening programs derived from absorbed dose measurements in the Netherlands

    International Nuclear Information System (INIS)

    Risk- and cost benefit analyses for breast screening programs are being performed, employing the risk-factors for induction of breast cancer from six extensive follow-up studies. For women of the age group above 35 years and for a risk period of 30 years after a 10-year latency period, a factor of extra cases of 20 x 10-6 mGy-1 can be estimated. Measurements are being performed in Dutch hospitals to determine the mean absorbed tissue dose. These doses vary from 0.6 to 4.4 mGy per radiography. For a dose of 1 mGy per radiograph and yearly screening of women between 35 and 75 years, the risk of radiogenic breast cancer is about 1% of the natural incidence (85,000 per 106 women) in this group. A recommended frequency of screening has to be based on medical, social and financial considerations. The gain in woman years and in completely cured women is being estimated for screening with intervals of 12 instead of 24 months. The medical and social benefit is 1,520 years life-time and 69 more cases completely cured per 1,000 breast cancer patients. The financial profit of a completely cured instead of an ultimately fatal cancer can be roughly estimated at 55,000 guilders. In addition the costs per gained woman-year are about 5,000 guilders. In consequence, the extra costs of annual additional rounds of mammographic screening are balanced by the benefit. (Auth.)

  8. Decoloration and mineralization of reactive dyes using electron beam irradiation, Part I: Effect of the dye structure, concentration and absorbed dose (single, binary and ternary systems)

    International Nuclear Information System (INIS)

    In this study, three different reactive dyes (C.I. Reactive Red 4, C.I. Reactive Blue 2 and C.I. Reactive Yellow 4) and their blend solutions were irradiated with 10 MeV electron beam. Effect of absorbed dose, dye structure and primary solution concentrations on the pH value changes, degree of decoloration and chemical oxygen demand (COD) removal of solutions were investigated. Results show that this method is effective in decomposition and decoloration of the dyes solutions. This method can be applied in mineralization of wastewater containing different dyes. - Highlights: ? We radiated different reactive dyes and their blend solutions with electron beam. ? We found that this technique is effective in decoloration of textile wastewaters. ? With lower doses complete decoloration of the wastewater solution was achieved. ? With increasing absorbed dose even intermediate compounds were eliminated. ? We report the effect of dose on the decoloration and degradation of dye solution.

  9. Monte Carlo estimation of radiation dose in organs of female and male adult phantoms due to FDG-F18 absorbed in the lungs

    OpenAIRE

    Belinato Walmir; Santos William S.; Silva Rogério M.V.; Souza Divanizia N.

    2014-01-01

    The determination of dose conversion factors (S values) for the radionuclide fluorodeoxyglucose (18F-FDG) absorbed in the lungs during a positron emission tomography (PET) procedure was calculated using the Monte Carlo method (MCNPX version 2.7.0). For the obtained dose conversion factors of interest, it was considered a uniform absorption of radiopharmaceutical by the lung of a healthy adult human. The spectrum of fluorine was introduced in the input data file for the simulation. The simulat...

  10. Deuterons at energies of 10 MeV to 1 TeV: Conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C

    International Nuclear Information System (INIS)

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons (2H+) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilderTM 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by < 3 %. The greatest difference, 47 %, occurred at 30 MeV. (authors)

  11. Deuterons at energies of 10 MeV to 1 TeV: conversion coefficients for fluence-to-absorbed dose, equivalent dose, effective dose and gray equivalent, calculated using Monte Carlo radiation transport code MCNPX 2.7.C.

    Science.gov (United States)

    Copeland, Kyle; Parker, Donald E; Friedberg, Wallace

    2011-01-01

    Conversion coefficients were calculated for fluence-to-absorbed dose, fluence-to-equivalent dose, fluence-to-effective dose and fluence-to-gray equivalent for isotropic exposure of an adult female and an adult male to deuterons ((2)H(+)) in the energy range 10 MeV-1 TeV (0.01-1000 GeV). Coefficients were calculated using the Monte Carlo transport code MCNPX 2.7.C and BodyBuilder™ 1.3 anthropomorphic phantoms. Phantoms were modified to allow calculation of the effective dose to a Reference Person using tissues and tissue weighting factors from 1990 and 2007 recommendations of the International Commission on Radiological Protection (ICRP) and gray equivalent to selected tissues as recommended by the National Council on Radiation Protection and Measurements. Coefficients for the equivalent and effective dose incorporated a radiation weighting factor of 2. At 15 of 19 energies for which coefficients for the effective dose were calculated, coefficients based on ICRP 1990 and 2007 recommendations differed by <3%. The greatest difference, 47%, occurred at 30 MeV. PMID:20980368

  12. Relative Importance of Hip and Sacral Pain Among Long-Term Gynecological Cancer Survivors Treated With Pelvic Radiotherapy and Their Relationships to Mean Absorbed Doses

    International Nuclear Information System (INIS)

    Purpose: To investigate the relative importance of patient-reported hip and sacral pain after pelvic radiotherapy (RT) for gynecological cancer and its relationship to the absorbed doses in these organs. Methods and Materials: We used data from a population-based study that included 650 long-term gynecological cancer survivors treated with pelvic RT in the Gothenburg and Stockholm areas in Sweden with a median follow-up of 6 years (range, 2–15) and 344 population controls. Symptoms were assessed through a study-specific postal questionnaire. We also analyzed the hip and sacral dose-volume histogram data for 358 of the survivors. Results: Of the survivors, one in three reported having or having had hip pain after completing RT. Daily pain when walking was four times as common among the survivors compared to controls. Symptoms increased in frequency with a mean absorbed dose >37.5 Gy. Also, two in five survivors reported pain in the sacrum. Sacral pain also affected their walking ability and tended to increase with a mean absorbed dose >42.5 Gy. Conclusions: Long-term survivors of gynecological cancer treated with pelvic RT experience hip and sacral pain when walking. The mean absorbed dose was significantly related to hip pain and was borderline significantly related to sacral pain. Keeping the total mean absorbed hip dose below 37.5 Gy during treatment might lower the occurrence of long-lasting pain. In relation to the controls, the survivors had a lower occurrence s, the survivors had a lower occurrence of pain and pain-related symptoms from the hips and sacrum compared with what has previously been reported for the pubic bone.

  13. Assessment of organ absorbed doses in patients undergoing chest X-ray examinations by Monte Carlo based softwares and phantom dosimetry

    International Nuclear Information System (INIS)

    Dosimetric studies in patients submitted to diagnostic radiology examinations have been done in Brazil with the aim of contributing to a radiation protection culture. In this work, a typical chest examination condition was simulated and absorbed doses in selected organs were measured with thermoluminescent dosimeters in a Rando-Alderson anthropomorphic phantom. Doses were also calculated with PCXMC® and CALDoseX Monte Carlo based softwares. In most cases, organ absorbed doses calculated by CaldoseX agreed up to 50% with values from the reliable experimental procedure based on TL dosimeters in the Rando-Alderson phantom. PCXMC® calculations showed large differences in organ absorbed doses that could not be explained. Lack of agreement among doses obtained with the three adopted methodologies could be attributed to the differences between their phantoms in terms size, weight and location of organs as well as poor representation of human anatomy. If a large survey of dose assessment in patients submitted to chest X-ray examinations is intended to be done, the results of this work should be considered.

  14. Estimation of absorbed dose for 2-[F-18]fluoro-2-deoxy-d- glucose using whole-body positron emission tomography and magnetic resonance imaging

    International Nuclear Information System (INIS)

    The purpose of this study was to measure the cumulated activity and absorbed dose in organs after i.v. administration of 18F-FDG using whole-body PET and MRI. Whole-body dynamic emission scans for 18F-FDG were performed in six normal volunteers after transmission scans. The total activity of a source organ was obtained from the activity concentration of the organ measured by whole-body PET and the volume of that organ measured by whole-body T1-weighted MRI. The cumulated activity of each source organ was calculated from the time-activity curve. Absorbed doses to the individuals were estimated by the MIRD (medical internal radiation dosimetry) method. Another calculation of cumulated activities and absorbed doses was performed using the organ volumes from the MIRD phantom and the ''Japanese reference man'' to investigate the discrepancy of actual individual results against the phantom results. The cumulated activities of 18 source organs were calculated, and absorbed doses of 27 target organs estimated. Among the target organs, bladder wall, brain and kidney received the highest doses for the above three sets of organ volumes. Using measured individual organ volumes, the average absorbed doses for those organs were found to be 3.1 x 10-1, 3.7 x 10-2 and 2.8 x 10-2 mGy/MBq, respectively. The mean effective doses in this study for individuals of average body weight (64.5 kg) and the MIRD phantom of 70 kg were the samand the MIRD phantom of 70 kg were the same, i.e. 2.9 x 10-2 mSv/MBq, while for the Japanese reference man of 60 kg the effective dose was 2.1 x 10-2 mSv/MBq. The results for measured organ volumes derived from MRI were comparable to those obtained for organ volumes from the MIRD phantom. Although this study considered 18F-FDG, combined use of whole-body PET and MRI might be quite effective for improving the accuracy of estimations of the cumulated activity and absorbed dose of positron-labelled radiopharmaceuticals.(orig./MG) (orig.)

  15. Uncertainties on measurements of absorbed-dose-to-water, from clinical high- energy electron beams: a comparison with the IAEA protocols

    International Nuclear Information System (INIS)

    A pilot study was performed to verify the troubles involved in the implementation of dosimetric protocol TRS 398 for absorbed-dose-to-water, using clinical high-energy electron beams and to accomplish an detailed evaluation of uncertainty chain components associated to the measurement, which ones were not treated in the IAEA protocols, aimed the standardization of technical procedures. (author)

  16. Experimental verification by means of thermoluminescent dosimetry of the distribution dose absorbed in water for a 137Cs Amersham CDCS-M-3 source, Monte Carlo simulated

    International Nuclear Information System (INIS)

    It verifies, in a experimental way, the Monte Carlo simulation results (PENELOPE algorithm) for the water absorbed dose distribution, imparted by a 137 Cs - Amersham source (model CDCS-M-3). The feigned results are expressed in terms of