ICRP Recommendations Research Articles

TH-E-211-06: Further Development of VirtualDose Software for CT Dose Assessment: Realistic Phantoms and Smartphone User Interfaces

Purpose: To demonstrate the feasibility of a new software applications for both PC and smartphone users to easily track patient CT doses. Methods: Many of existing tools for reporting CT dose are based on data derived from stylistic phantoms. Based on extensive original dose data derived from Monte Carlo simulations and computational phantoms including a new set of BMI‐adjustable obese patient phantoms, VirtualDose is being designed with interactive, user‐friendly graphical interfaces afforded both on the PC and the smartphone platforms. Organ doses and effective doses are computed using ICRP Publication 60 and 103. The software is developed using the C# for PCs and JAVA for the Android smartphones. Results: VirtualDose offers a modern graphical user interface (GUI) designed to allow interactive 3D phantom display and user‐selectable scanning parameters. Standard scanning ranges can be selected from a pull‐down menu or manually specified on the displayed phantom. The new developed morbidly obese phantom was found to have CTorgan doses on average a factor of 0.76 times smaller than that of the normal weight phantom for the same tube current because of shielding by the extra fat. For the same injected activity, the average PETorgan dose ratios were 0.95 and 0.65 for source organs and organs in the remainder, respectively. Conclusions: The preliminary GUI design and reporting features of VirtualDose improve upon existing tools by considering the latest CT scanners, smartphone platform, new ICRP recommendations and anatomically realistic patient phantoms.

Fluence-to-dose conversion coefficients for aircrew dosimetry based on the new ICRP Recommendations

The estimation of the fluence-to-effective dose conversion coefficients used especially for aircrew dosimetry is an important issue, since the geometrical conditions of aircrew exposure are considered not to be represented by the standard irradiation geometries such as the anterior-to-posterior (AP) and isotropic (ISO) geometries. We therefore calculated the dose conversion coefficients for neutrons and protons based on the ICRP 2007 Recommendations for three additional irradiation geometries: semi-isotropic irradiation from the upper hemisphere, and geometries closely representing the geometrical situations of aircrew exposure for two different flight conditions. The calculation was performed by the PHITS code coupled with the ICRP/ICRU adult reference computational phantoms. It was found from the calculation that (1) the conversion coefficients for the irradiation geometries closely representing the geometrical situations of aircrew exposure agree better with the corresponding data for the isotropic irradiation than those for the semi-isotropic irradiation; (2) the error associated with the assumption of the isotropic irradiation in the aircrew dosimetry is less than only 1% for conventional flight conditions. These findings indicate the adequacy of the use of dose conversion coefficients for the isotropic irradiation geometry in aircrew dosimetry.

SU-GG-I-75: Calculating the Effective Dose for Pediatric Patients from Multi-Detector CT Studies: New vs. Old ICRP Recommendations

Purpose: To compare calculated effective doses for pediatric CT exams using the new and old ICRP recommendations. Methods and Materials: A total of 178 pediatric patients who underwent traumaCT studies were analyzed retrospectively. Subjects were divided into 6 groups according to the type of exams performed, ranging from only a head scan to a full body assessment (head/face/neck/chest/abdomen/pelvis). Two versions of ImPACT software (ImPACT CT, version 0.99x & 1.0) were used to analyze study data and extract the effective dose: the older version used ICRP‐60 to calculate effective doses whereas ImPACT 1.0 used ICRP‐103 recommendations. The correction factors for pediatrics, which are included in spreadsheet, were applied to obtain the equivalent pediatric effective dose. A paired student's t‐test was used with significance threshold set at 0.01. Results: Pediatric effective doses using ICRP 103 were found to be significantly different from those calculated with ICRP 60 (p 0.01) were when face scans were included in the “full body” scan. This is probably due to the fact that the new tissue weighting factors of face organs did not change significantly from ICRP‐60. However, when only a head and face scans were performed, the difference was found to be highly significant most likely because of the inclusion of the brain and salivary glands, which accounted for a larger contribution of the received doses from head than face scan, in the new ICRP weighting factors.

TH-C-201B-10: Development and Testing of a CT Dose Software “VirtualDose” Using Anatomically Realistic Patient Phantoms: Preliminary Results for the Phase I of the Project

Purpose: To demonstrate the need and feasibility for developing a new software for reporting patient imaging dose who undergoing CT or PET/CT examinations. Method and Materials: Existing CT dose reporting software do not meet the need because of the simplified anatomical phantoms updated ICRP data and scanner information. A new software is being designed with original dose data derived from Monte Carlo simulations involving CTscannermodels and anatomically realistic phantoms. Specified scanning protocols and CT sources are modeled. Dosimetry capabilities for tube current modulation (TCM) and PET/CT protocols are currently under development. The RPI Pregnant Women series RPI Adult Male and Adult Female phantoms are used in the dose calculation. Organ doses and effective doses are computed using ICRP Publication 60 and 103. The software framework is developed using the Visual C#.NET. Results: VirtualDose offers a modern graphical user interface (GUI) designed to allow interactive 3D phantom display and user‐selectable scanning parameters. Standard scanning ranges can be selected from a pull‐down menu or manually specified on the displayed phantom. When compared with data reported by existing software using stylized MIRD‐type phantoms the organ dose estimates have been found to differ by a ratio ranging from 0.77 to 1.24 for organs or tissues covered in the scan range and a ratio as small as 0.13 for organs outside of the scan region. The TCM technique can reduce the dose by around 20% for pregnant patient phantoms. Conclusion: It is clear that existing software do not meet the need for accurate and state‐of‐the‐art CT dose reporting. The preliminary GUI design and reporting features of VirtualDose improve upon existing tools by considering the latest CTscanners new ICRP recommendations and anatomically realistic patient phantoms. VirtualDose is expected to improve both the accuracy and usability in reporting CT doses in the future.

Risk assessment due to ingestion of natural radionuclides and heavy metals in the milk samples: a case study from a proposed uranium mining area, Jharkhand

Ingestion of radionuclides and heavy metals through drinking water and food intake represents one of the important pathways for long-term health considerations. Milk and milk products are main constituents of the daily diet. Radionuclides and heavy metals can be apprehended in the ecosystem of the East Singhbhum region which is known for its viable grades of uranium, copper and other minerals. For the risk assessment studies, samples of milk were collected from twelve villages around Bagjata mining area and analysed for U(nat), 226Ra, 230Th, 210Po, Fe, Mn, Zn, Pb, Cu and Ni. Analysis of the results of the study reveals that the geometric mean of U(nat), 226Ra, 230Th and 210Po was 0.021, 0.24, 0.23 and 1.08 Bq l(-1), respectively. The ingestion dose was calculated to be 12.34 μSvY(-1) which is reflecting the natural background dose via the route of ingestion, and much below the 1 mSv limit set in the new ICRP recommendations. The excess lifetime cancer risk was estimated to be 1.72×10(-4) which is within the acceptable excess individual lifetime cancer risk value of 1×10(-4). The geometric mean of Fe, Mn, Zn, Cu and Ni was 4.91, 0.29, 4.77, 0.56 and 0.48 mgl(-1), respectively; whereas the daily intake was computed to be 0.44, 0.03, 0.43, 0.05 and 0.04 mg/day, respectively. Pb was not detected in any of the samples. The hazard quotient revealed that the intake of the heavy metals through the ingestion of milk does not pose any apparent threat to the local people as none of the HQ of the heavy metals exceeds the limit of 1.

Ingestion of U(nat),226Ra,230Th and210Po in vegetables by adult inhabitants of Bagjata uranium mining area, Jharkhand, India

Ingestion of radionuclides through food intake accounts for a substantial part of radiation doses and vegetables constitute essential components of the diet, by contributing protein, vitamins, iron, calcium and other nutrients. Radionuclides can be apprehended in the ecosystem of the East Singhbhum region which is known for its viable grades of uranium. In the present study, vegetables were collected from the villages around the proposed Bagjata mining area and analysed for U(nat), 226 Ra, 230 Th and 210 Po. The geometric mean concentration of U(nat), 226 Ra, 230 Th, and 210 Po were 0.05, 0.09, 0.17 and 1.12 Bq kg-1 fresh weight, respectively. The intake of the radionuclides from vegetables was found to be 49.58 Bq y-1 while the ingestion dose was calculated to be 11.51 µSv y-1 , respectively. The estimated doses are reflecting the natural background dose via the route of ingestion, which is much below the 1 mSv limit set in the new ICRP recommendations. It is lower than the global average annual radiation dose of 2 400 µSv to man from the natural radiation sources as proposed by UNSCEAR. The total cancer risk due to the consumption of vegetables was calculated to be 6.65 × 10-9 which is negligible and much lower than the threshold risk value of 10-6 . The study also reveals that water is more conducive for high radioactivity occurrence in vegetables compared to soil systems.

New ICRP Recommendation―New Radiation Protection Principle and Standards

New ICRP Recommendation―New Radiation Protection Principle and Standards

New ICRP Recommendation―New Radiation Protection Princiole and Standards

New ICRP Recommendation―New Radiation Protection Princiole and Standards

New ICRP Recommendation―New Radiation Protection Principle and Standards (7)

New ICRP Recommendation―New Radiation Protection Principle and Standards (7)

New ICRP Recommendation―New Radiation Protection Principle and Standards(6)

New ICRP Recommendation―New Radiation Protection Principle and Standards(6)

Opinion of Young Researchers about Implementation of New ICRP Recommendation in Domestic Laws

我が国における放射線障害防止に係る現行の諸法令は，国際放射線防護委員会（ICRP）のICRP 1990年勧告の放射線防護に対する考え方が基礎となっている。ICRPは2007年，17年ぶりの主勧告の改訂を行い，ICRP 1990年勧告に代わるICRP 2007年勧告を公表した。これを受け，現在，文部科学省に置かれた放射線審議会により，ICRP 2007年勧告の国内法令取入れに関する審議がなされている。本稿では，放射線審議会における検討の中でも重要な事項として挙げられている「女性の線量限度」，「電離健康診断」，「緊急時被ばく」，「監視区域」，「線量拘束値」について，放射線防護に携わる若手の考えを述べさせていただきたい。

New ICRP Recommendation―New Radiation Protection Principle and Standards (8)

New ICRP Recommendation―New Radiation Protection Principle and Standards (8)

Overview of research on aircraft crew dosimetry during the last solar cycle

Cosmic radiation was discovered successfully in the beginning of the twentieth century by the Austrian Nobel Price winner Victor Hess. Radiation effects to humans are of major concern during human space missions and also due to the increasing aviation altitudes and flight time. ICRP recommendations lead to adaptations of the Basic Safety Standards by the European Council. Beginning in the 1990 s up to now, significant improvements and findings in aviation dosimetry and epidemiology were done word-wide. Five research projects on measurements and modelling cosmic radiation exposure were supported by European Research Framework Programmes. In-flight measurements with remarkable agreement (+/-25%) were carried out to validate calculation codes for routine dose assessment within +/-30% for galactic cosmic radiation. Measurements and improvements of modelling radiation exposure due to solar particle events (SPE) is still an objective for future research projects.

Implications of the new ICRP recommendations for aircrew dosimetry

In 2007 the International Commission on Radiological Protection has published its general recommendations replacing the previous 1990 Recommendations. In this paper mainly those parts of the recommendations, which may influence the assessment of doses to aircrews in flight heights, are presented and discussed. Aircrews are generally defined to be occupationally exposed workers and in many countries their exposure is assessed by determination of route doses in flight heights. While the definition of the operational quantities has not been changed, the paper concentrates on the definition of the effective dose, the introduction of anthropomorphic voxel phantoms, the weighting of the different organs and tissues of the human body and the radiation weighting factors. Its implications for aircrew monitoring is discussed.

Towards a coherent conceptual framework for emergency preparedness/response and rehabilitation – the application of the new ICRP recommendations given in ICRP 103

In the past, most emphasis in planning for and response to an emergency situation has been placed on selected protective measures in the early phase of an emergency to keep the doses received below levels where severe deterministic health effects can be excluded and/or where the risk of stochastic effects in the population is considered “acceptable”. Less emphasis has been placed on the development of comprehensive protection strategies which include considerations of the consequences of all exposure pathways and all phases, e.g. long-term rehabilitation. In its new publication 103, ICRP proposed a coherent conceptual framework for protection in all types of exposure situations including “emergency exposure situations” and “existing exposure situations”. In the context of developing protection strategies for these exposure situations, the Commission recommends that national authorities set reference levels between, typically, 20 mSv and 100 mSv annual effective dose (emergency exposure situation) and 1 mSv and 20 mSv (existing exposure situation). In order to optimise protection strategies, it is necessary to identify the dominant exposure pathways, the timescales over which the dose will be received, and the effectiveness of available protection options. The characteristics of the development and implementation of such protection strategies is described.

Effective dose evaluation of multidetector CT examinations: influence of the ICRP recommendation in 2007

We compared effective doses for recent computed tomography (CT) examinations calculated based on International Commission on Radiological Protection publication number 103 (ICRP 103) with those calculated based on ICRP publication number 60 (ICRP 60), and considered the usefulness of the effective dose in CT dose evaluation. After placing radiophotoluminescence glass dosimeters (RPLDs) inside or outside an anthropomorphic phantom, we examined from the chest to the pelvis, cardiac, and cranial regions of the phantom. The absorbed dose was calculated by multiplying calibrated dose values of RPLD by the mass energy coefficient ratio. The effective dose was calculated as the sum total of the value for each tissue, which was multiplied by the equivalent dose according to the tissue weighting factor recommended in ICRP 103 and ICRP 60. Calculated effective doses based on ICRP 103 were different by –11% to +82% compared with those based on ICRP 60. The values of absorbed doses for selective tissues were relatively higher than the values for the effective dose. The effective dose represents only a mean dose value for an average human. Therefore, assessing the absolute dose of particular individuals in CT examinations based exclusively on the effective dose is not recommended.

TU‐C‐304A‐01: The Need and Feasibility of a Modern Software for Reporting Patient Doses From CT Scans

Purpose: To demonstrate the need and feasibility to develop a modern software tool for reporting the organ dose and effective dose for patients undergoing CT examinations. Method and Materials: Existing CT dose reporting software do not meet the need because of the simplified anatomical phantoms, updated ICRP data and scanner information. A new software is designed with original dose data derived from Monte Carlo simulations involving CT scanner models from various companies and anatomically realistic phantoms. X‐ray sources and protocols are modeled. The Pregnant Women, Adult Male and Adult Female phantoms are utilized. Organ doses and effective doses are computed using both the ICRP‐60 and the latest ICRP‐103 recommendations. The software is developed using the Visual C♯.NET with a modern graphical user interface (GUI) design to allow a user to specify the patient type, body scan region, and scanner operating parameters. Object‐oriented programming technology allows the phantoms to be displayed in 3D interactively. Results: Compared to values reported by the existing software, the organ dose estimates can be different by a ratio as 0.77 to 1.24 for the organ or tissue covered in the scan range, and 0.13 for the organs out of the scan region between calculations using the anatomically realistic phantoms. In addition to the improved dose accuracy, the new program offers a number pf modern GUI features through which 3D phantoms are vividly inspected for organs that receive a high doses. Based on the user‐specified scanning parameters, organ and effective doses are rapidly reported. Conclusion: Preliminary results have demonstrated the aim of the new software design in addressing the needs for new CT scanners, ICRP recommendations and anatomically realistic phantoms. When fully developed, this new tool is expected to improve both the accuracy and usability in reporting CT doses in the future.

Setting radiation safety standards from a modern perspective

The basic ideas published more than 50 years ago in A. D. Sakharov’s article “Radioactive Carbon from Nuclear Explosions and Zero-Threshold Biological Effects” are examined from the standpoint of the scientific knowledge accumulated up to 1958 in the field of radiobiology and the effect of radiation on the human body at ultralow doses. The present state of radiological risk regulation is examined in the light of the problems which Sakharov touched upon. The need for improving the normative-legal foundation of radiological safety and protection in connection with the publication of new ICRP recommendations and the development of new safety standards started under IAEA aegis is discussed.

Effective dose in dental radiography based on the 2007 ICRP Recommendations

Effective dose in dental radiography based on the 2007 ICRP Recommendations

Radiological criteria for the remediation of sites for spent fuel and radioactive waste storagein the Russian Northwest

In the 1960s, two technical bases of the Northern Fleet were created in NorthwestRussia, at Andreeva Bay in the Kola Peninsula and Gremikha village on thecoast of the Barents Sea. They maintained nuclear submarines, performing receiptand storage of radioactive waste and spent nuclear fuel, and are now designatedsites of temporary storage (STSs). An analysis of the radiation situation at thesesites demonstrates that substantial long-term remediation work will be requiredafter the removal of the waste and spent nuclear fuel. Regulatory guidance isunder development to support this work. Having in mind modern approaches toguaranteeing radiation safety, the primary regulatory focus is on a justification of doseconstraints for determining acceptable residual contamination which might lead toexposure to workers and the public. For these sites, four principal options forremediation have been considered—renovation, conversion, conservation and liquidation.This paper describes a system of recommended dose constraints and derived control levelsformulated for each option. The unconditional guarantee of long-term radioecologicalprotection provides the basis for criteria development. Non-exceedance of these doseconstraints and control levels implies compliance with radiological protection objectivesrelated to the residual contamination. Dose reduction below proposed dose constraintvalues must also be carried out according to the optimisation principle. The developedcriteria relate to the condition of the facilities and the STS areas after the termination ofremediation activities.The proposed criteria for renovation, conversion, conservation and liquidation are entirelywithin the dose limits adopted in Russia for the management of man-made radiationsources, and are consistent with ICRP recommendations and national practice inother countries. The proposed criteria for STS remediation and new industrial(non-radiation-hazardous) facilities and buildings on the remedied sites had, until now, noanalogues in the Russian system of regulation of radiation-hygienic standardisation. Theproposals made here may serve as a basis for corresponding standards at othersites.