International Commission On Radiological Protection Publication Research Articles

Assessing the reliability of dose coefficients for ingestion and inhalation of 226Ra and 90Sr by members of the public

Assessments of risk to a population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficient, E(50), used as a radiation protection device for the specified exposure pathway. An estimate of the uncertainty on the risk is important for informing judgements on reliability. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to radioisotopes of the alkaline earth metals, (90)Sr and (226)Ra, by members of the UK public. The study derives uncertainties in biokinetic model parameter values to calculate the distributions of the effective dose per unit intake using the ICRP Publication 60 formalism. The distributions are used to infer the uncertainty on the mean effective dose per unit intake to inform the derivation of uncertainty factors (UF) for the appropriate ICRP Publication 72 dose coefficients. Here, a UF indicates a 95 % probability that the best estimate of risk per unit intake is within a factor, UF, of the nominal risk associated with the appropriate ICRP dose coefficient, E(50), with respect to uncertainties in the biokinetic model parameter values. Ingestion: it is assumed that exposure occurs through the ingestion of radionuclides present in food and water. The results for both radionuclides suggest a UF of within 3 for all age groups, with median values close to the ICRP values. Inhalation: it is assumed that environmental exposure to radium occurs primarily due to insoluble forms present in fly ash discharged from coal-fired power stations; for strontium, exposure is assumed to occur due to residual aerosols produced as a result of atmospheric nuclear testing and nuclear reactor accidents. The results suggest a UF of around 3 and 6 for inhalation of (90)Sr and (226)Ra, respectively, by members of the public.

A review of lung-to-blood absorption rates for radon progeny

The International Commission on Radiological Protection (ICRP) Publication 66 Human Respiratory Tract Model (HRTM) treats clearance of materials from the respiratory tract as a competitive process between absorption into blood and particle transport to the alimentary tract and lymphatics. The ICRP recommended default absorption rates for lead and polonium (Type M) in ICRP Publication 71 but stated that the values were not appropriate for short-lived radon progeny. This paper reviews and evaluates published data from volunteer and laboratory animal experiments to estimate the HRTM absorption parameter values for short-lived radon progeny. Animal studies showed that lead ions have two phases of absorption: ∼10 % absorbed with a half-time of ∼15 min, the rest with a half-time of ∼10 h. The studies also indicated that some of the lead ions were bound to respiratory tract components. Bound fractions, f(b), for lead were estimated from volunteer and animal studies and ranged from 0.2 to 0.8. Based on the evaluations of published data, the following HRTM absorption parameter values were derived for lead as a decay product of radon: f(r) = 0.1, s(r) = 100 d(-1), s(s) = 1.7 d(-1), f(b) = 0.5 and s(b) = 1.7 d(-1). Effective doses calculated assuming these absorption parameter values instead of a single absorption half-time of 10 h with no binding (as has generally been assumed) are only a few per cent higher. However, as there is some conflicting evidence on the absorption kinetics for radon progeny, dose calculations have been carried out for different sets of absorption parameter values derived from different studies. The results of these calculations are discussed.

The reliability of dose coefficients for inhalation and ingestion of uranium by members of the public

The best estimate of risk to a population group resulting from internal exposure to a particular radionuclide can be used to assess the reliability of the appropriate International Commission on Radiological Protection (ICRP) dose coefficient (E⁵⁰) for the specified exposure pathway. An estimate of the uncertainty on the risk is important for reliability decisions. This paper describes the application of parameter uncertainty analysis to quantify uncertainties resulting from internal exposures to uranium (as (²³⁸U) by members of the public. The study derives uncertainties in biokinetic model parameter values to calculate the distributions of the effective dose per unit intake using the ICRP Publication 60 formalism. The central values and ranges of the distributions are used to infer the uncertainty on the mean effective dose per unit intake to inform the derivation of uncertainty factors (UF) for the dose coefficients. Here, a UF is a conditional probability statement that the value of the best estimate of risk per unit intake has a 95 % probability of being within a factor, UF, of the nominal risk associated with the appropriate ICRP dose coefficient, E⁵⁰, with respect to uncertainties in the biokinetic model parameter values. Ingestion: it is assumed that exposure occurs through the ingestion of uranium present in food and water. The results suggest a UF of within 3 for all age groups, with median values close to the ICRP values. Inhalation: it is assumed that environmental exposure to uranium occurs via inhalation of a mixture of chemical forms. The results suggest a UF of around 2 for inhalation of uranium by members of the public, with median values close to the ICRP values.

A Bayesian analysis of uncertainties on lung doses resulting from occupational exposures to uranium

In a recent epidemiological study, Bayesian estimates of lung doses were calculated in order to determine a possible association between lung dose and lung cancer incidence resulting from occupational exposures to uranium. These calculations, which produce probability distributions of doses, used the human respiratory tract model (HRTM) published by the International Commission on Radiological Protection (ICRP) with a revised particle transport clearance model. In addition to the Bayesian analyses, point estimates (PEs) of doses were also provided for that study using the existing HRTM as it is described in ICRP Publication 66. The PEs are to be used in a preliminary analysis of risk. To explain the differences between the PEs and Bayesian analysis, in this paper the methodology was applied to former UK nuclear workers who constituted a subset of the study cohort. The resulting probability distributions of lung doses calculated using the Bayesian methodology were compared with the PEs obtained for each worker. Mean posterior lung doses were on average 8-fold higher than PEs and the uncertainties on doses varied over a wide range, being greater than two orders of magnitude for some lung tissues. It is shown that it is the prior distributions of the parameters describing absorption from the lungs to blood that are responsible for the large difference between posterior mean doses and PEs. Furthermore, it is the large prior uncertainties on these parameters that are mainly responsible for the large uncertainties on lung doses. It is concluded that accurate determination of the chemical form of inhaled uranium, as well as the absorption parameter values for these materials, is important for obtaining unbiased estimates of lung doses from occupational exposures to uranium for epidemiological studies. Finally, it should be noted that the inferences regarding the PEs described here apply only to the assessments of cases provided for the epidemiological study, where central estimates of dose were sought. Approved dosimetry service assessments of exposures are unlikely to yield significant underestimates, as pessimistic assumptions of lung solubility would almost always be used.

Evaluation of absorbed and effective doses to patients from radiopharmaceuticals using the ICRP 110 reference computational phantoms and ICRP 103 formulation

In diagnostic nuclear medicine, mean absorbed doses to patients' organs and effective doses are published for standard stylised anatomic models. To provide more realistic and detailed geometries of the human morphology, the International Commission on Radiological Protection (ICRP) has recently adopted male and female voxel phantoms to represent the reference adult. This work investigates the impact of the use of these new computational phantoms. The absorbed doses were calculated for 11 different radiopharmaceuticals currently used in diagnostic nuclear medicine. They were calculated for the ICRP 110 reference computational phantoms using the OEDIPE software and the MCNP extended Monte Carlo code. The biokinetic models were issued from ICRP Publications 53, 80 and 106. The results were then compared with published values given in these ICRP Publications. To discriminate the effect of anatomical differences on organ doses from the effect of the calculation method, the Monte Carlo calculations were repeated for the reference adult stylised phantom. The voxel effect, the influence of the use of different densities and nuclear decay data were also investigated. Effective doses were determined for the ICRP 110 adult reference computational phantom with the tissue weighting factor of ICRP Publication 60 and the tissue weighting factors of ICRP Publication 103. The calculation method and, in particular, the simulation of the electron transport have a significant influence on the calculated doses, especially, for small and walled organs. Overestimates of >200 % were observed for the urinary bladder wall of the stylised phantom compared with the computational phantoms. The unrealistic organ topology of the stylised phantom leads to important dose differences, sometimes by an order of magnitude. The effective doses calculated using the new computational phantoms and the new tissue weighting factors are globally lower than the published ones, except for some radiopharmaceuticals, where the differences can reach 60 % higher than the published values. This study analyses the first set of absorbed and effective doses with the new ICRP male and female reference computational phantoms for different radiopharmaceuticals. It highlights the importance of taking into account the electron transport and the realism of the shape and inter-organ distances of the anthropomorphic model used.

Risk of medical imaging

Risk of medical imaging

Calculated organ doses using Monte Carlo simulations in a reference male phantom undergoing HDR brachytherapy applied to localized prostate carcinoma

The aim of this study was to obtain equivalent doses in radiosensitive organs (aside from the bladder and rectum) when applying high-dose-rate (HDR) brachytherapy to a localized prostate carcinoma using (60)Co or (192)Ir sources. These data are compared with results in a water phantom and with expected values in an infinite water medium. A comparison with reported values from proton therapy and intensity-modulated radiation therapy (IMRT) is also provided. Monte Carlo simulations in Geant4 were performed using a voxelized phantom described in International Commission on Radiological Protection (ICRP) Publication 110, which reproduces masses and shapes from an adult reference man defined in ICRP Publication 89. Point sources of (60)Co or (192)Ir with photon energy spectra corresponding to those exiting their capsules were placed in the center of the prostate, and equivalent doses per clinical absorbed dose in this target organ were obtained in several radiosensitive organs. Values were corrected to account for clinical circumstances with the source located at various positions with differing dwell times throughout the prostate. This was repeated for a homogeneous water phantom. For the nearest organs considered (bladder, rectum, testes, small intestine, and colon), equivalent doses given by (60)Co source were smaller (8%-19%) than from (192)Ir. However, as the distance increases, the more penetrating gamma rays produced by (60)Co deliver higher organ equivalent doses. The overall result is that effective dose per clinical absorbed dose from a (60)Co source (11.1 mSv/Gy) is lower than from a (192)Ir source (13.2 mSv/Gy). On the other hand, equivalent doses were the same in the tissue and the homogeneous water phantom for those soft tissues closer to the prostate than about 30 cm. As the distance increased, the differences of photoelectric effect in water and soft tissue, and appearance of other materials such as air, bone, or lungs, produced variations between both phantoms which were at most 35% in the considered organ equivalent doses. Finally, effective doses per clinical absorbed dose from IMRT and proton therapy were comparable to those from both brachytherapy sources, with brachytherapy being advantageous over external beam radiation therapy for the furthest organs. A database of organ equivalent doses when applying HDR brachytherapy to the prostate with either (60)Co or (192)Ir is provided. According to physical considerations, (192)Ir is dosimetrically advantageous over (60)Co sources at large distances, but not in the closest organs. Damage to distant healthy organs per clinical absorbed dose is lower with brachytherapy than with IMRT or protons, although the overall effective dose per Gy given to the prostate seems very similar. Given that there are several possible fractionation schemes, which result in different total amounts of therapeutic absorbed dose, advantage of a radiation treatment (according to equivalent dose to healthy organs) is treatment and facility dependent.

Computational lymphatic node models in pediatric and adult hybrid phantoms for radiation dosimetry

We developed models of lymphatic nodes for six pediatric and two adult hybrid computational phantoms to calculate the lymphatic node dose estimates from external and internal radiation exposures. We derived the number of lymphatic nodes from the recommendations in International Commission on Radiological Protection (ICRP) Publications 23 and 89 at 16 cluster locations for the lymphatic nodes: extrathoracic, cervical, thoracic (upper and lower), breast (left and right), mesentery (left and right), axillary (left and right), cubital (left and right), inguinal (left and right) and popliteal (left and right), for different ages (newborn, 1-, 5-, 10-, 15-year-old and adult). We modeled each lymphatic node within the voxel format of the hybrid phantoms by assuming that all nodes have identical size derived from published data except narrow cluster sites. The lymph nodes were generated by the following algorithm: (1) selection of the lymph node site among the 16 cluster sites; (2) random sampling of the location of the lymph node within a spherical space centered at the chosen cluster site; (3) creation of the sphere or ovoid of tissue representing the node based on lymphatic node characteristics defined in ICRP Publications 23 and 89. We created lymph nodes until the pre-defined number of lymphatic nodes at the selected cluster site was reached. This algorithm was applied to pediatric (newborn, 1-, 5-and 10-year-old male, and 15-year-old males) and adult male and female ICRP-compliant hybrid phantoms after voxelization. To assess the performance of our models for internal dosimetry, we calculated dose conversion coefficients, called S values, for selected organs and tissues with Iodine-131 distributed in six lymphatic node cluster sites using MCNPX2.6, a well validated Monte Carlo radiation transport code. Our analysis of the calculations indicates that the S values were significantly affected by the location of the lymph node clusters and that the values increased for smaller phantoms due to the shorter inter-organ distances compared to the bigger phantoms. By testing sensitivity of S values to random sampling and voxel resolution, we confirmed that the lymph node model is reasonably stable and consistent for different random samplings and voxel resolutions.

Translation of Dose Coefficients From ICRP 53 to ICRP 80

The effective dose coefficients tabulated in Publication 80 of the International Commission on Radiological Protection (ICRP) for the radiopharmaceuticals addressed earlier in ICRP Publication 53 are based on the tissue weighting factors of ICRP Publication 60. Presumably these values are derived from the tissue dose coefficients tabulated in Publication 53; however, no details regarding their derivation are provided. The tissue weighting factors of Publication 60 explicitly address tissue for which no dose coefficients were tabulated in Publication 53; for example, esophagus and a number of tissues comprising the remainder. In the absence of guidance, the authors have defined a set of rules for the translation and have undertaken an effort to derive the effective dose coefficients of Publication 80 starting with the organ/tissue dose coefficient of Publication 53.

Biokinetic models for radiocaesium and its progeny

The International Commission on Radiological Protection (ICRP) is preparing a series of reports that will provide updated biokinetic and dosimetric models and dose coefficients for occupational intake of radionuclides. The biokinetic modelling scheme continues a trend in ICRP reports towards physiologically realistic descriptions of the time-dependent behaviour of absorbed radionuclides and their radioactive progeny. This paper proposes systemic biokinetic models for caesium isotopes and their ingrowing chain members and examines the dosimetric implications of the proposed models. Comparisons of D68 = tissue dose per unit input to blood based on current ICRP models for workers (ICRP Publication 68, 1994) with DP = corresponding values based on the proposed biokinetic models (but using the dosimetry models of Publication 68) yields the following ranges of the ratios DP:D68 for the tissues addressed in Publication 68: 0.5–25 for 130Cs (T1/2 = 29.2 min), 0.6–9.5 for 134mCs (2.9 h), 0.7–1.7 for 131Cs (9.69 d), 0.7–1.1 for 134Cs (2.06 y), 0.5–1.9 for 137Cs (30.2 y) and 0.2–3.7 for 135Cs (2.3 × 106 y). The large differences in the derived dose coefficients for some tissues and caesium isotopes, particularly short-lived isotopes, result mainly from differences in predictions of the time-dependent distributions of caesium in the body. For example, the proposed model and the current ICRP model for occupational intake of caesium predict peak kidney contents of ∼22% and ∼0.4%, respectively, following intravenous injection of stable caesium. Based on the proposed models for caesium and its progeny, the only dosimetrically significant chain members of caesium isotopes with half-life ≥10 min are 137mBa, which represents 32–85% of the estimated tissue doses from injected 137Cs, and 134Cs, which represents 4–53% of the estimated tissue doses from injected 134mCs.

Dose conversion coefficients for electron exposure of the human eye lens: calculations including a whole body phantom

In this work, conversion coefficients from electron fluence to absorbed dose to the eye lens were calculated using Monte Carlo simulations based on a detailed stylised eye model and a very simple but whole body phantom. These data supersede and complement data published earlier based on the simulation of only a single stylised eye. The new data differ from the old ones by not more than 3, 4, 7 and 16 % for angles of radiation incidence of α=0°, 15°, 30° and 45°, respectively, due to the inclusion of the whole body phantom. The data presented in the present work also complement those of a recent report of the International Commission on Radiological Protection (ICRP) (ICRP Publication 116), where conversion coefficients from electron fluence to absorbed dose to the lens of the eye are shown for solely 0°, 180° and isotropic radiation incidence (but for a much broader range of energies). In this article, values are provided for angles of incidence of 0° up to 180° in steps of 15° and for rotational geometry; no systematic deviation was observed from the values given in ICRP Publication 116 for 0° (based on the application of a bare eye) and 180° (based on the application of a voxel whole body phantom). Data are given for monoenergetic electrons from 0.1 up to 10 MeV and for a broad parallel beam geometry in vacuum.

Tools for risk assessment in radiation therapy

Radiotherapy has unquestionable benefits, but it is also associated with unique and specific safety issues. It is the only application of radiation in which humans are intentionally delivered very high doses. Safety in radiotherapy remains heavily dependent on human actions. A step-by-step approach is suggested for the prevention of accidental exposures in radiation therapy: (1) allocation of responsibilities to qualified professionals, and design of a quality and safety programme – no radiotherapy practice should be operated without these key elements; (2) use of the lessons from accidental exposures to test whether the quality and safety programme is sufficiently robust against these types of events –publications by the International Commission on Radiological Protection (ICRP) and the International Atomic Energy Agency provide a collection of lessons to facilitate this step; and (3) find other latent risks by posing the questions ‘What else could go wrong?’ or ‘What other potential hazards might be present?’ in a systematic, anticipative manner – methods to do so are described briefly in ICRP Publication 112.

Report of ICRP Task Group 80: ‘Radiological protection in geological disposal of long-lived solid radioactive waste’

The report of International Commission on Radiological Protection (ICRP) Task Group 80 entitled ‘Radiological protection in geological disposal of long-lived solid radioactive waste’ updates and consolidates previous ICRP recommendations related to solid waste disposal (ICRP Publications 46, 77, and 81). The recommendations given in this report apply specifically to geological disposal of long-lived solid radioactive waste. The report explains how the 2007 system of radiological protection, described in ICRP Publication 103, can be applied in the context of the geological disposal of long-lived solid radioactive waste. The report is written as a self-standing document. It describes the different stages in the lifetime of a geological disposal facility, and addresses the application of relevant radiological protection principles for each stage depending on the various exposure situations that can be encountered. In particular, the crucial factor that influences application of the protection system over the different phases in the lifetime of a disposal facility is the level of oversight that is present. The level of oversight affects the capability to reduce or avoid exposures. Three main time frames have to be considered for the purpose of radiological protection: time of direct oversight when the disposal facility is being implemented and active oversight is taking place; time of indirect oversight when the disposal facility is sealed and indirect oversight is being exercised to provide additional assurance on behalf of the population; and time of no oversight when oversight is no longer exercised because memory is lost.

Risk of lung cancer from radon exposure: contribution of recently published studies of uranium miners

The International Commission on Radiological Protection (ICRP) recently estimated the risk of lung cancer associated with radon exposure, and a statement was issued in ICRP Publication 115. This was based on recent epidemiological studies and the results from a joint analysis of cohorts of Czech, French, and German uranium miners, and indicated that the excess relative risk of lung cancer per unit of exposure should be expressed with consideration of chronic exposure over more than 10years, by modelling time since median exposure, age attained or age at exposure, and taking in account, if possible, interaction between radon and tobacco.The lifetime excess absolute risk (LEAR) calculated from occupational exposure studies is close to 5×10−4 per working level month (WLM) (14×10−5 per hmJ/m3). LEAR values estimated using risk models derived from both miners and domestic exposure studies are in good agreement after accounting for factors such as sex, attained age, and exposure scenario. A sensitivity analysis highlighted the high dependence of background mortality rates on LEAR estimates. Using lung cancer rates among Euro-American males instead of the ICRP reference rates (males and females, and Euro-American and Asian populations), the estimated LEAR is close to 7×10−4 per WLM (20×10−5 per hm J/m3).

RADAR reference adult, pediatric, and pregnant female phantom series for internal and external dosimetry.

A new generation of reference computational phantoms, based on image-based models tied to the reference masses defined by the International Commission on Radiological Protection (ICRP) for dose calculations, is presented. Anatomic models based on nonuniform rational b-spline modeling techniques were used to define reference male and female adults, 15-y-olds, 10-y-olds, 5-y-olds, 1-y-olds, newborns, and pregnant women at 3 stages of gestation, using the defined reference organ masses in ICRP publication 89. Absorbed fractions and specific absorbed fractions for internal emitters were derived using standard Monte Carlo radiation transport simulation codes. Differences were notable between many pairs of organs in specific absorbed fractions because of the improved realism of the models, with adjacent organs usually closer and sometimes touching. Final estimates of absorbed dose for radiopharmaceuticals, for example, were only slightly different overall, as many of the differences were small and most pronounced at low radiation energies. Some new important organs were defined (salivary glands, prostate, eyes, and esophagus), and the identity of a few gastrointestinal tract organs changed. A new generation of reference models for standardized internal and external dose calculations has been defined. The models will be implemented in standardized software for internal dose calculations and be used to produce new standardized dose estimates for radiopharmaceuticals and other applications.

ICRP and IAEA actions on radiation protection in computed tomography

In 1998, the International Commission on Radiological Protection (ICRP) warned that computed tomography (CT) doses were high, and the frequency of usage was likely to increase in view of spiral CT technology that enhances patient convenience and provides high-quality diagnostic information. Two ICRP publications (Publications 87 and 102) have provided patient dose management recommendations while reviewing the technology and results of optimisations to date, and stimulated interest in patient dose management. The International Atomic Energy Agency, on the other hand, has been instrumental in assessing the state of practice at grassroots level, identifying lacunae in justification and optimisation, providing guidance to counterparts in various countries, and improving practice. The results from approximately 50 less-resourced countries for adult and paediatric CT studies have become available, and some have been published. The concerted efforts and actions by these two international organisations have contributed to better awareness and improvement of patient protection in CT in adults and children in many countries.

Dosimetry for Reference Animals and Plants: current state and prospects

The enormous diversity of non-human biota is a specific challenge when developing and applying dosimetric models for assessing exposures to flora and fauna from environmental radioactivity. Dosimetric models, adopted by the International Commission on Radiological Protection (ICRP), provide dose conversion coefficients for a large variety of biota, including the Reference Animals and Plants. The models use a number of simplified approaches, often ignoring presumably insignificant details. Simple body shapes with uniform composition and density, homogeneous internal contamination, a limited set of external radiation sources for terrestrial animals and plants, and truncation of radioactive decay chains are a few examples of simplifying assumptions underlying the dose conversion coefficients included in ICRP Publication 108. However, many specific assessment tasks require dosimetric data for non-standard species or irradiation scenarios. The further development of dosimetric models aims at the implementation of flexible choices of animals and plants, as well as of their irradiation conditions (e.g. trees); more systematic consideration of internal exposures from radionuclides concentrated in specific organs; and task-oriented choice of decay chains based on ICRP Publication 107. An extensive set of non-human dosimetric data might require specific software to facilitate fast, accurate, and flexible selection of pertinent dose conversion coefficients for specific assessment tasks.

TH‐E‐213AB‐02: Review of the Radiobiological Principles of Radiation Protection

The radiobiological principles underlying radiation protection guidelines will be reviewed, analyzing the published results of the effects of ionizing radiation at the cellular level, in animal experiments and, especially, in epidemiological studies. To ensure a consistent terminology, the radiation dosimetry terms used in radiation biology and in radiation protection will be presented. The concepts of equivalent dose vs dose equivalent as well as the term effective dose, the Gray and Sv units, and the radiation and tissue weighting factors will be explained and illustrated. Human data on radiation induced cancer, including increases in the risk of second cancers following radiation therapy, as well as data on radiation induced tissue reactions, published by the International Commission on Radiological Protection (ICRP), the National Council on Radiation Protection and Measurements (NCRP) and the Biological Effects of Ionizing Radiation (BEIR) Committee, with their latest estimates of risk per unit dose, will be introduced. The dose response of normal tissues will be discussed, including effects on children and the developing embryo and fetus. Recent findings in NCRP and ICRP publications, which include follow up times for some tissues much longer than those common in radiotherapy (up to 20 to 40 versus 5 to 10 years), will be assessed. In particular, current information on acute and chronic radiation syndromes, as well as the newly proposed threshold dose of 0.5 Gy for cataract induction and cardiovascular effects, will be examined. The impact of the new findings and recommendations on the development of radiation protection guidelines and standards, especially in the International Basic Safety Standards on Protection against Ionizing Radiation and for the Safety of Radiation Sources (BSS), soon to be adopted world‐wide, will be evaluated.Learning Objectives:1. To define the radiation protection magnitudes and units, their values and their practical measurement2. To understand the radiobiological basis of radiation protection standards3. To distinguish between stochastic effects and tissue reactions

WE‐A‐218‐01: NCICT a Computer Program for Organ and Effective Dose Calculation for Pediatric and Adult Patients Undergoing Computed Tomography

Purpose: To develop a computer program for users to conveniently assess organ and effective doses for patients undergoing computed tomography (CT) examinations by using patient‐ and scan‐specific parameters. Methods: A comprehensive organ and effective dose database previously published by the authors was employed in this study. A series of pediatric and adult hybrid computational phantoms representing the International Commission on Radiological Protection (ICRP) reference data was coupled with a reference CT scanner model within Monte Carlo transport code to establish a set of five dimensional dose matrix, D (33 organs, 6 age groups, 2 genders, 3 tube potentials, scan positions with 1 cm z‐resolution). A graphical user interface (GUI) was designed using Visual Basic computer language to obtain user input (patient age and gender, scanner manufacturer and models, head/body filter, pitch, tube potential, tube current, a single rotation time, and scan start and end position). The GUI was then coupled with the dose matrix and a dose calculation routine was written. Organ doses were compared with the values obtained from previous CT dosimetry tools. Results: A computer program, named NCICT, was developed using pre‐ calculated dose matrix. As a result, a total of 33 organ doses and two effective doses based on ICRP Publication 60 and 103 are displayed. Major organ doses were calculated for head, chest, and abdomen‐pelvis scans and compared with the values from CT‐Expo and CTDosimetry. The comparison revealed that use of phantoms with realistic anatomy is crucial to improved accuracy in CT organ dosimetry. Conclusion: NCICT, a user‐ friendly computer program for CT dose calculation was developed and validated. The program provides more realistic patient anatomy, higher age resolution, advanced skeleton dosimetry, and several convenient features compared to the previous tools. The NCICT is under beta testing and will be available for research purpose in the near future.

2296 ORGAN SPECIFIC RADIATION DOSE AND EFFECTIVE DOSE FOR RENAL STONE PROTOCOL COMPUTERIZED TOMOGRAPHY (CT)

You have accessJournal of UrologyStone Disease: Basic Research II1 Apr 20122296 ORGAN SPECIFIC RADIATION DOSE AND EFFECTIVE DOSE FOR RENAL STONE PROTOCOL COMPUTERIZED TOMOGRAPHY (CT) Muhammad W. Iqbal, Agnes J. Wang, Giao Nguyen, Gastón M. Astroza, Greta Toncheva, Natalie Januzis, Carolyn Lowry, Amy M. Neville, Michael N. Ferrandino, Terry T. Yoshizumi, Glenn M. Preminger, and Michael E. Lipkin Muhammad W. IqbalMuhammad W. Iqbal Durham, NC More articles by this author , Agnes J. WangAgnes J. Wang Durham, NC More articles by this author , Giao NguyenGiao Nguyen Durham, NC More articles by this author , Gastón M. AstrozaGastón M. Astroza Durham, NC More articles by this author , Greta TonchevaGreta Toncheva Durham, NC More articles by this author , Natalie JanuzisNatalie Januzis Durham, NC More articles by this author , Carolyn LowryCarolyn Lowry Durham, NC More articles by this author , Amy M. NevilleAmy M. Neville Durham, NC More articles by this author , Michael N. FerrandinoMichael N. Ferrandino Durham, NC More articles by this author , Terry T. YoshizumiTerry T. Yoshizumi Durham, NC More articles by this author , Glenn M. PremingerGlenn M. Preminger Durham, NC More articles by this author , and Michael E. LipkinMichael E. Lipkin Durham, NC More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.2476AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Patients with nephrolithiasis are at increased risk for radiation exposure. The amount of radiation these patients are exposed to from a CT scan is evolving, as protocols evolve. The concern over increased patient radiation exposure is related to the risk of developing a malignancy. Effective dose (ED) is a value that relates the amount of radiation absorbed to the risk of developing a malignancy. This study was done to measure organ specific radiation doses and determine the effective dose for a non-contrast CT abdomen/pelvis for the evaluation of nephrolithiasis performed at our institution. METHODS An anthropomorphic, adult male phantom validated for human organ dosimetry, was placed on a GE 64-slice Volume CT scanner in prone position. A non-contrast CT abdomen/pelvis was performed with the following settings: tube voltage 120 kV, tube current 700 mA, pitch 1.375:1, noise index 17.5. High sensitivity metal oxide semiconductor field effect transistors (MOSFET) dosimeters were placed at 20 organ locations and used to measure organ radiation doses. The organ doses were multiplied by their tissue weighting factors(Wt) and summed to determine the effective dose. Tissue weighting factors are obtained from the International Commission on Radiological Protection, publication (ICRP) 103. RESULTS The bone marrow was exposed to the highest absorbed dose, with cumulative dose of 13.4 milligray (mGy), followed by the skin entrance, 7.23 mGy and bladder 6.60 mGy. The ED for the renal stone CT was 3.04 milli Sieverts(mSv). CONCLUSIONS Radiation from CT scans contributes to the overall radiation exposure for patients with nephrolithiasis. A non-contrast CT performed for the evaluation of nephrolithiasis results in an effective dose of 3.04 mSv. Accurate determination of ED enables patients and clinicians to make informed decisions regarding CT imaging and allows calculation of cumulative ED in this high risk population. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e926-e927 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Muhammad W. Iqbal Durham, NC More articles by this author Agnes J. Wang Durham, NC More articles by this author Giao Nguyen Durham, NC More articles by this author Gastón M. Astroza Durham, NC More articles by this author Greta Toncheva Durham, NC More articles by this author Natalie Januzis Durham, NC More articles by this author Carolyn Lowry Durham, NC More articles by this author Amy M. Neville Durham, NC More articles by this author Michael N. Ferrandino Durham, NC More articles by this author Terry T. Yoshizumi Durham, NC More articles by this author Glenn M. Preminger Durham, NC More articles by this author Michael E. Lipkin Durham, NC More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...