Radiation Protection

A study of the performance of five commercial radiotherapy treatment planning systems (TPSs) for common treatment sites regarding their ability to model heterogeneities and scattered photons has been performed. The comparison was based on CT information for prostate, head and neck, breast and lung cancer cases. The TPSs were installed locally at different institutions and commissioned for clinical use based on local procedures. For the evaluation, beam qualities as identical as possible were used: low energy (6 MV) and high energy (15 or 18 MV) x-rays. All relevant anatomical structures were outlined and simple treatment plans were set up. Images, structures and plans were exported, anonymized and distributed to the participating institutions using the DICOM protocol. The plans were then re-calculated locally and exported back for evaluation. The TPSs cover dose calculation techniques from correction-based equivalent path length algorithms to modelbased algorithms. These were divided into two groups based on how changes in electron transport are accounted for ((a) not considered and (b) considered). Increasing the complexity from the relatively homogeneous pelvic region to the very inhomogeneous lung region resulted in less accurate dose distributions. Improvements in the calculated dose have been shown when models consider volume scatter and changes in electron transport, especially when the extension of the irradiated volume was limited and when low densities were present in or adjacent to the fields. A Monte Carlo calculated algorithm input data set and a benchmark set for a virtual linear accelerator have been produced which have facilitated the analysis and interpretation of the results. The more sophisticated

Over the last decade, there has been considerable progress in the development of countermeasures for preventing or reducing contamination of animal products by radioisotopes of iodine, caesium and strontium. In this paper, recent significant technical improvements are summarised and the current availability of countermeasures and their usefulness in the event of a nuclear accident reviewed. An improved understanding of factors controlling the metabolism of radioiodine and radiostrontium has enabled previously suggested countermeasures to be either optimised or dismissed. For radiocaesium in particular, experience since the Chernobyl accident has enabled effective and feasible countermeasures to be identified and successfully implemented in different situations. It has also been more widely understood that countermeasure effectiveness, although important, is not the only criterion which needs to be determined. In addition, cost and practical considerations such as availability, technical feasibility, acceptability and side-effects need to be taken into account. Evaluation of these factors has shown that some previously recommended countermeasures are unlikely to be feasible. #

このレポートでは、過去5年間に東京電力福島第
一原発事故の影響を受けた地域で実施された多数
の調査の結果に基づき、2011年3月に起きた同
事故の結果として現在生じている生態学的状況を
明らかにする。これは福島県の森林、河川、氾濫
原、河口域の放射能汚染に関して現時点で判明し
ていることを記録にとどめようとする試みであ
る。福島県と全国の環境に放出された放射性核種
の半減期の長さを考えれば、それが生態系に与え
る影響を理解することは不可欠である。
また、このレポートでは、日本の今後数年、数十
年間について予測されることに関する洞察を提供
するために、キシュテムとチェルノブイリの放射
能事故で深刻な汚染を受けた森林・水生生態系の
研究を参考にした。

Radon isotopes (222, 220, 219) are radioactive gases produced by the disintegration of radium isotopes 226, 224 and 223, which are decay products of uranium238, thorium232 and uranium235 respectively. All are found in the earth's crust. Solid elements, also radioactive, are produced by radon disintegration. Radon is classed as a rare gas in the periodic table of elements, along with helium, argon, neon, krypton and xenon. When disintegrating, radon emits alpha particles and generates solid decay products, which are also radioactive (polonium, bismuth, lead etc.). The potential danger of radon lies in its solid decay products rather than the gas itself. Whether or not they are attached aerosols, radon decay products can be inhaled and deposited in the bronchopulmonary tree to varying depths according to their size. Radon today is considered to be the main source of human exposure to natural radiation. At the international level, radon accounts for 52% of global average exposure t...

Non-linear phenomena in biological findings of the residents of high background radiation areas of Ramsar background dose rates among the highest known in the world. As the biological effects of low doses of radiation are not fully understood (2, 3) , the current radiation protection recommendations are based on the predictions of an assumption on the linear non-threshold hypothesis (LNT) relationship between radiation dose and its carcinogenic effects (4, 5). Considering the LNT hypothesis as a scienti ic fact, there is a general belief that even low levels of radiation as well as exposures to natural

The aim of this study was to determine ovarian dose, effective dose and associated radiogenic risks from hysterosalpingography (HSG), and to provide data for the estimation of radiogenic risks related to HSG studies performed in any laboratory. The fluoroscopy time, number of radiographs taken and entrance surface dose were measured in a series of 78 consecutive patients undergoing HSG as part of their infertility work-up. Organ-dose values per radiograph and per minute of fluoroscopy were separately determined using an anthropomorphic phantom and thermoluminescence dosimetry. The radiogenic risk for deleterious effects on a possible future embryo and the radiogenic risk for cancer induction on the patient undergoing HSG were estimated. The average HSG procedure in our laboratory involves a mean fluoroscopic time of 0.3 min and a mean number of radio-graphs of 3.2. The dose to female gonads from an average HSG procedure was 2.7 mGy and the patient effective dose was 1.2 mSv. The risk for radiogenic anomalies in a future embryo of the woman undergoing an average HSG procedure and the risk for radiogenic fatal cancer induction in the exposed woman were estimated to be less than 10-3 of the correspondent nominal risks. Radiation risks from a typical HSG are low, but they may be elevated if fluoroscopic and/or radiographic exposures are prolonged for any reason. Present data allow the estimation of radiogenic risks associated with HSG procedures performed in other laboratories with use of different equipment, screening time and number of radiographs taken.

The purpose of optimising the acquisition parameters in positron emission tomography is to improve the quality of the diagnostic images. Optimisation can be done by maximising the noise equivalent count rate (NECR) that in turn depends on the coincidence rate. For each bed position the scanner records coincidences and singles rates. For each patient, the true, random and scattered coincidences as functions of the single count rate(s) are determined by fitting the NEMA (National Electrical Manufacturers Association) 70 cm phantom count rate curves to measured clinical points. This enables analytical calculation of the personalised PNECR [ pseudo NECR(s)] curve, linked to the NECR curve. For central bed positions, missing activity of 70% is estimated to get maximum PNECR (PNECR max), but the improvement in terms of signal-toznoise ratio would be 15%. The correlation between patient weight and PNECR max is also estimated to determine the optimal scan duration of a single bed position as a function of patient weight at the same PNEC. Normalising the counts at PNECR max for the 70 kg patient, the bed duration for a 90 kg patient should be 230 s, which is 30% longer. Although the analysis indicates that the fast scanner electronics allow using higher administered activities, this would involve poor improvement in terms of NECR. Instead, attending to higher bed duration for heavier patients may be more useful.

We have measured charged nuclear fragments produced by 1 GeV/nucleon 56 Fe ions interacting with aluminium, polyethylene and lead. These materials are relevant for assessment of radiation risk for manned space flight. The data will be presented in a form suitable for comparison with models of nuclear fragmentation and transport, including linear energy transfer (LET) spectrum, fluence for iron and fragments, event-tack-and event-dose-averaged LET, total dose and iron contribution to dose. Ó 2005 Published by Elsevier Ltd on behalf of COSPAR.

With 5-7 month long duration missions at 51.6°inclination in Low Earth Orbit, the ionizing radiation levels to which International Space Station (ISS) crewmembers are exposed will be the highest planned occupational exposures in the world. Even with the expectation that regulatory dose limits will not be exceeded during a single tour of duty aboard the ISS, the ''as low as reasonably achievable'' (ALARA) precept requires that radiological risks be minimized when possible through a dose optimization process. Judicious placement of efficient shielding materials in locations where crewmembers sleep, rest, or work is an important means for implementing ALARA for spaceflight. Polyethylene (C n H n ) is a relatively inexpensive, stable, and, with a low atomic number, an effective shielding material that has been certified for use aboard the ISS. Several designs for placement of slabs or walls of polyethylene have been evaluated for radiation exposure reduction in the Crew Quarters (CQ) of the Zvezda (Star) Service Module. Optimization of shield designs relies on accurate characterization of the expected primary and secondary particle environment and modeling of the predicted radiobiological responses of critical organs and tissues. Results of the studies shown herein indicate that 20% or more reduction in equivalent dose to the CQ occupant is achievable. These results suggest that shielding design and risk analysis are necessary measures for reducing long-term radiological risks to ISS inhabitants and for meeting legal ALARA requirements. Verification of shield concepts requires results from specific designs to be compared with onboard dosimetry.

The long-term biokinetics and dosimetry of carbon-14 were studied in nine adults and eight children undergoing carbon-14 urea breath test for Helicobacter pylori (HP) infection. The elimination of 14 C via exhaled air and urine was measured with the liquid scintillation counting technique and with accelerator mass spectrometry. After the subjects had been given 110 kBq 14 C-urea (children: 55 kBq) orally, samples of exhaled air were taken up to 180 days after administration and samples of urine were collected up to 40 days. Sixteen of the subjects were found to be HP-negative. In these subjects a total of 91.1%±3.9% (mean of adults and children ± standard error of the mean) of the administered 14 C activity was recovered. The majority of the administered activity, 88.3%±6.2% in adults and 87.7%±5.0% in children, was excreted via the urine within 72 h after administration. A smaller fraction was exhaled. In adults 4.6%±0.6% of the activity was exhaled within 20 days and in children 2.6%±0.3%. Uncertainties in the biokinetic results are mainly due to assumptions concerning endogenous CO 2 production and urinary excretion rate and are estimated to be less than 30%. The absorbed dose to various organs and the effective dose were calculated using the ICRP model for urea and CO 2 . The urinary bladder received the highest absorbed dose: in adults, 0.15±0.01 mGy/MBq and in children of various ages (7-14 years), 0.14-0.36 mGy/MBq. The findings indicate that an investigation with 14 C-urea gives an effective dose to adults of 2.1±0.1 µSv (for 110 kBq) and to children of 0.9-2.5 µSv (for 55 kBq). From a radiation protection point of view, there is thus no reason for restrictions on even repeated screening investigations with 14 C-urea in whole families, including children.

Diagnostic reference levels (DRLs) were established for 21 indication-based CT examinations for adults in Switzerland. One hundred and seventy-nine of 225 computed tomography (CT) scanners operated in hospitals and private radiology institutes were audited on-site and patient doses were collected. For each CT scanner, a correction factor was calculated expressing the deviation of the measured weighted computed tomography dose index (CTDI) to the nominal weighted CTDI as displayed on the workstation. Patient doses were corrected by this factor providing a realistic basis for establishing national DRLs. Results showed large variations in doses between different radiology departments in Switzerland, especially for examinations of the petrous bone, pelvis, lower limbs and heart. This indicates that the concept of DRLs has not yet been correctly applied for CT examinations in clinical routine. A close collaboration of all stakeholders is mandatory to assure an effective radiation protection of patients. On-site audits will be intensified to further establish the concept of DRLs in Switzerland.

The Canadian Panel of the International Society for Clinical Densitometry has developed standards in order to establish the minimum level of acceptable performance for the practice of bone densitometry in Canada. Previously, this group addressed the performance of densitometry in postmenopausal women. This report addresses the use of densitometry in men, premenopausal women, and children with a focus on dual-energy X-ray absorptiometry.

We analysed the dose-volume distribution in normal brain in eight patients undergoing localized external beam radiotherapy for brain tumours. The results have been represented as integral dose-volume histograms and show that large volumes of normal brain receive clinically significant doses of radiation. A mean of 43% (range 24%-57 %) of normal brain volume received more than 50% and a mean of 22% (range 9%-38%) received more than 85% of the maximum tumour dose. The amount of normal brain irradiated increased with enlarging target volume. With the use of customized shielding blocks the mean volume reduction of normal brain receiving more than 50% and 85% maximum tumour dose was 178 ml (median 183 ml; range 89-244 ml) and 110 ml (median 110 ml; 40-179 ml) respectively. This represents an average reduction of 13% and 8% of normal brain volume. Although clinically important this may not be sufficient for a significant improvement in therapeutic ratio.

Purpose: Conformal radiotherapy of the prostate is an increasingly common technique in the treatment of prostate cancer. When using 3D conformal radiotherapy (CFRT) methods, it is desirable to protect the vital structures such as bladder, rectum, and femur. In this study, our aim was to compare the femur head doses resulting from co-planar beam arrangements in four-field (4F), five-field (5F), six-field (6F) and seven-field (7F) treatment plans, in a dose-escalated CFRT schedule.

In a working group of the Belgian Hospital Physicists Association (BHPA), a new protocol has been developed for comprehensive testing of computed tomography scanners. The tests were selected to verify if the scanner is technically adequate, if preprogrammed patient protocols are up-to-date, and if exposure values displayed at the console are sufficiently correct. In addition, they will ensure that the participating medical physics expert (MPE) gets a full understanding of the system to enable him/her to guide optimization processes and allow automated patient dosimetry. Several new test procedures had to be developed. The tests go beyond the criteria identified in the EC guidance document radiation protection (RP) 91 and its successor RP 162. The results of the tests of the BHPA protocol are discussed in the light of the acceptability criteria in RP 91 and RP 162. It is concluded that the ensemble of tests in the BHPA protocol and in RP 162 provide very useful information on the sca...

FLUKA is an integrated particle transport code that has enhanced multigroup low-energy neutron transport capability similar to the well-known MORSE transport code. Gammas are produced in groups but many important individual lines are speciÿcally included, and subsequently transported by the main FLUKA routines which use a modiÿed version of EGS4 for electromagnetic (EM) transport. Recoil protons are also transported by the primary FLUKA transport simulation. The neutron cross-section libraries employed within FLUKA were supplied by Giancarlo Panini (ENEA, Italy) based upon the most recent data from JEF-1, JEF-2.2, ENDF=B-VI, JENDL-3, etc. More than 60 di erent materials are included in the FLUKA databases with temperature ranges including down to cryogenic temperatures. This code has been used extensively to model the neutron environments near high-energy physics experiment shielding. A simulation of the Space Shuttle based upon a spherical aluminum equivalent shielding distribution has been performed with reasonable results. There are good prospects for extending this calculation to a more realistic 3-D geometrical representation of the Shuttle including an accurate representation of its composition, which is an essential ingredient for the improvement of the predictions. A proposed project to develop a combined analysis and simulation package based upon FLUKA and the analysis infrastructure provided by the ROOT software is under active consideration. The code to be developed for this project will be of direct application to the problem of simulating the neutron environment in space, including the albedo e ects.

Background: Analyse through a multi-choice anonymous questionnaire the knowledge's level in paediatric residents and fellows in two different main Italian hospital, looking mainly to the information to patients and relatives related to risks of ionizing radiation used in common radiological investigations in children. Methods: 65 multi choice questionnaires were distributed to paediatric residents and fellows of two different hospitals, an University Hospital (A.O.U.P. "P. Giaccone"-University of Palermo) and a national reference centre for paediatrics (Ospedale Pediatrico Bambino Gesù -Rome). The questionnaire included twelve multiple-choice questions with the aim of analyzing the knowledge about ionizing radiation related risks in infants and children who undergo common diagnostic radiology investigations. The data obtained were processed using software Stata/MP version 11.2. In order to measure the level of expertise of each interviewee a binary indicator was built. The value 1 was assigned if the percentage of correct answers exceeds the median of the distribution and 0 for values not exceeding the median. The association between the level of competence and demographic characteristics (gender, age) and training experience was measured by means of α 2 test. Results: 51/65 questionnaires were completed, returned and analysed (87.7%). Only 18 surveyed (35%), (95% IC = [22%-48%]) can be defined as competent in radiation risk knowledge for common radiological investigations, considering the percentage of correct answers at least of 50% (sufficient knowledge was given with a minimum score of 8 correct answers out of 12).

A significant metric in federal mammography quality standards is the phantom image quality assessment. The present work seeks to demonstrate that automated image analyses for American College of Radiology ͑ACR͒ mammographic accreditation phantom ͑MAP͒ images may be performed by a computer with objectivity, once a human acceptance level has been established. Twelve MAP images were generated with different x-ray techniques and digitized. Nineteen medical physicists in diagnostic roles ͑five of which were specially trained in mammography͒ viewed the original film images under similar conditions and provided individual scores for each test object ͑fibrils, microcalcifications, and nodules͒. Fourier domain template matching, used for low-level processing, combined with derivative filters, for intermediate-level processing, provided translation and rotation-independent localization of the test objects in the MAP images. The visibility classification decision was modeled by a Bayesian classifer using threshold contrast. The 50% visibility contrast thresholds established by the trained observers' responses were: fibrils 1.010, microcalcifications 1.156, and nodules 1.016. Using these values as an estimate of human observer performance and given the automated localization of test objects, six images were graded with the computer algorithm. In all but one instance, the algorithm scored the images the same as the diagnostic physicists. In the case where it did not, the margin of disagreement was 10% due to the fact that the human scoring did not allow for half-visible fibrils ͑agreement occurred for the other test objects͒. The implication from this is that an operator-independent, machine-based scoring of MAP images is feasible and could be used as a tool to help eliminate the effect of observer variability within the current system, given proper, consistent digitization is performed. © 1997 American Association of Physicists in Medicine. ͓S0094-2405͑97͒00205-8͔

In positron emission tomographic (PET) scanning, transmission measurements for attenuation correction are commonly performed by using external germanium-68 rod sources. Recently, combined PET and computed tomographic (CT) scanners have been developed in which the CT data can be used for both anatomicalmetabolic image formation and attenuation correction of the PET data. The purpose of this study was to evaluate the difference between germanium-and CT-based transmission scanning in terms of their radiation doses by using the same measurement technique and to compare the doses that patients receive during brain, cardiac and whole-body scans. Measurement of absorbed doses to organs was conducted by using a Rando Alderson phantom with thermoluminescent dosimeters. Effective doses were calculated according to the guidelines in the International Commission on Radiation Protection Publication Number 60. Compared with radionuclide doses used in routine 2-[fluorine-18]-fluoro-2-deoxy-D-glucose PET imaging, doses absorbed during germanium-based transmission scans were almost negligible. On the other hand, absorbed doses from CT-based transmission scans were significantly higher, particularly with a whole-body scanning protocol. Effective doses were 8.81 mSv in the high-speed mode and 18.97 mSv in the high-quality mode for whole-body CT-based transmission scans. These measurements revealed that the doses received by a patient during CT-based transmission scanning are more than those received in a typical PET examination. Therefore, the radiation doses represent a limitation to the generalised use of CT-based transmission measurements with current PET/CT scanner systems.

Interventional cardiology (IC) is a rapidly growing field of medical specialisation. Such procedures are complex and may subject patients and operators to higher levels of risk than those encountered in general radiology. Acceptance testing and quality assurance (QA) of radiological equipment, including IC equipment, is a requirement of the EU Medical Exposures Directive (MED) (97/43/EURATOM). In addition, the MED identifies interventional radiology as an area of special concern. This study presents the results of a survey of 17 IC systems (including several flat panel detector systems) in Irish hospitals. The results of the survey indicate large differences in patient doses between manufacturers for equivalent levels of measured image quality. In addition, all systems were found to have failed one or more acceptance tests, with 60% of systems demonstrating significant problems at acceptance testing. The results of the survey demonstrate the importance of acceptance testing and QA in IC. The results also provide baseline data, which may be used in the development of future QA guidelines.

Radiation assessment and protection in space is the Wrst step in planning future missions to the Moon and Mars, where mission and number of space travelers will increase and the protection of the geomagnetic shielding against the cosmic radiation will be absent. In this framework, the shielding eVectiveness of two Xexible materials, Kevlar and Nextel, were tested, which are largely used in the construction of spacecrafts. Accelerator-based tests clearly demonstrated that Kevlar is an excellent shield for heavy ions, close to polyethylene, whereas Nextel shows poor shielding characteristics. Measurements on Xight performed onboard of the International Space Station and of the Foton-M3 capsule have been carried out with special attention to the neutron component; shielded and unshielded detectors (thermoluminescence dosemeters, bubble detectors) were exposed to a real radiation environment to test the shielding properties of the materials under study. The results indicate no signiWcant eVects of shielding, suggesting that thin shields in low-Earth Orbit have little eVect on absorbed dose. This manuscript is based on a contribution given at the Heavy Ions in Therapy and Space Symposium

The RADPAD is a lead-free surgical drape containing bismuth and barium that has been demonstrated to reduce scatter radiation exposure to primary operators during fluoroscopic procedures. It is not known to what degree the RADPAD reduces radiation exposure in operators who perform highly complex percutaneous coronary intervention (PCI) requiring prolonged fluoroscopic screening times. Sixty consecutive patients due to undergo elective complex PCI involving rotational atherectomy, multivessel PCI, or chronic total occlusions were randomized in a 1:1 pattern to have their procedures performed with and without the RADPAD drape in situ. Dosimetry was performed on the left arm of the primary operator. There were 40 cases of chronic total occlusion, including 28 with contralateral injections; 15 cases involving rotational atherectomy; and 5 cases of multivessel PCI. There was no significant difference in screening times or dose-area products between the 2 patient groups. Primary operator radiation dose relative to screening time (RADPAD: slope ‫؍‬ 1.44, R 2 ‫؍‬ 0.25; no RADPAD: slope ‫؍‬ 4.60, R 2 ‫؍‬ 0.26; analysis of covariance F ‫؍‬ 4.81, p ‫؍‬ 0.032) and dose-area product (RADPAD: slope ‫؍‬ 0.003, R 2 ‫؍‬ 0.26; no RADPAD: slope ‫؍‬ 0.011, R 2 ‫؍‬ 0.52; analysis of covariance F ‫؍‬ 12.54, p ‫؍‬ 0.008) was significantly smaller in the RADPAD cohort compared to the no-RADPAD group. In conclusion, the RADPAD significantly reduces radiation exposure to primary operators during prolonged, complex PCI cases.

The marked increase in radiation exposure from medical imaging, especially in children, has caused considerable alarm and spurred efforts to preserve the benefits but reduce the risks of imaging. Applying the principles of the Image Gently campaign, data-driven process and quality improvement techniques such as process mapping and flowcharting, cause-and-effect diagrams, Pareto analysis, statistical process control (control charts), failure mode and effects analysis, "lean" or Six Sigma methodology, and closed feedback loops led to a multiyear program that has reduced overall computed tomographic (CT) examination volume by more than fourfold and concurrently decreased radiation exposure per CT study without compromising diagnostic utility. This systematic approach involving education, streamlining access to magnetic resonance imaging and ultrasonography, auditing with comparison with benchmarks, applying modern CT technology, and revising CT protocols has led to a more tha...

Computational models of human anatomy are mathematical representations of human anatomy designed to be used in dosimetry calculations. They have been used in dosimetry calculations for radiography, radiotherapy, nuclear medicine, radiation protection and to investigate the effects of low frequency electromagnetic fields. Tomographic medical imaging techniques have allowed the construction of digital three-dimensional computational models based on the actual anatomy of individual humans. These are called voxel models, tomographic models or phantoms. Their usefulness lies in their faithful representation of human anatomy and the flexibility they afford by being able to be scaled in size to match the required human dimensions. Segmenting medical images in order to make voxel models is very time-consuming so semi-automatic segmentation techniques are being developed. Some 21 whole or partial body models currently exist and more are being prepared. These models are listed and discussed.

High-protection sunscreens have been suspected to prompt people to increase sun exposure, and thus to increase skin cancer risk. We tested the influence of both the actual protection (sun protection factor [SPF]) and the information about protection (label) on sun-exposure behavior. Design: Randomized controlled trial. Setting: Four French seaside resorts during summer 2001. Participants: A total of 367 healthy subjects during their 1-week holiday. Outcome was assessable in 98% of them. Intervention: Subjects were offered free sunscreens, with randomization into the following study arms: (1) SPF 40 labeled as "high protection"; (2) SPF 40 labeled as "basic protection"; and (3) SPF 12 labeled as "basic protection." Arm 4, ie, SPF 12 labeled as "high protection," was not implemented for ethical reasons. Subjects were not aware of the real target of the study and were blinded to the SPF value. Main Outcome Measure: Duration of sunbathing exposure during 1 week. Secondary outcomes were occurrence of sunburns and amount of sunscreen used. Influences of SPF and label were assessed separately. Results: Compared with the low-SPF group, the high-SPF group did not have longer sunbathing exposure (12.9±7.2 h/wk for high SPF vs 14.6±6.7 h/wk for low SPF; P=.06), experienced fewer sunburns (14% vs 24%; P=.049), and used less sunscreen (median, 30 g vs 109 g; PϽ.001). The label "high protection" or "basic protection" had no influence on these end points. Conclusions: In this adult population, higher SPF had no influence on duration of sun exposure and offered better protection against sunburns. Although higher SPF may increase sun exposure duration in specific populations, this effect cannot be viewed as a universal side effect of high-SPF sunscreens.

Der Aufsatz vergleicht die Strahlenschutzregime im Uranbergbau der DDR und der Bundesrepublik Deutschland nach dem Zweiten Weltkrieg bis in die achtziger Jahre. In beiden Systemen stellte sich das Problem, den Schutz der Beschäftigten mit einer möglichst effizienten Förderung von Uranerz im Kontext des Kalten Krieges zu vereinbaren. Unterschiede existierten im gesellschaftlichen und politischen Kontext des Bergbaus, weniger in der verwendeten Technik und in den zugrunde gelegten Strahlenschutznormen. Hinsichtlich letzterer orientierten sich die Ende der fünfziger Jahre einsetzenden Strahlenschutzmaßnahmen an Empfehlungen der Internationalen Strahlenschutzkommission (ICRP). Allerdings zeichnete sich der sächsisch-thüringische Uranbergbau nicht nur durch sein größeres Ausmaß (und entsprechend größeres Gefährdungspotential) aus, sondern auch durch quasi-militärische Geheimhaltung.

Prolonged exposure to radon, the largest source (69%) of natural radioactivity, may cause lung cancer and bronchial tissue damage. So monitoring of radon at places of high radioactivity and in underground mines is important to assess the radiological hazards to occupational workers. For these reasons radon measurements were carried out in some coal mines of Baluchistan, Pakistan. The measurements were based upon passive detection of radon using CN-85 track detectors in Box Type Dosimeters. The radon concentration varied from 121 to 408 Bq m−3 in the mines under study. The computed radon dose varied from 1.38 to 4.67 mSv yr−1 with an average of 2.19±0.5 mSv yr−1. These coal mines have been found to be safe from radon-related health hazards.

In situ gamma-ray spectrometry determines the quantities of radionuclides in some medium with a portable detector. The main limitation of in situ gamma-ray spectrometry lies in determining the depth distribution of radionuclides. This limitation is addressed by developing an improved in situ method for determining the depth distributions of gamma-ray emitting radionuclides in large area sources. This paper implements a unique collimator design with conventional radiation detection equipment. Cylindrically symmetric collimators were fabricated to allow only those gamma-rays emitted from a selected range of polar angles (measured off the detector axis) to be detected. Positioned with its axis normal to surface of the media, each collimator enables the detection of gamma-rays emitted from a different range of polar angles and preferential depths. Previous in situ methods require a priori knowledge of the depth distribution shape. However, the absolute method presented in this paper determines the depth distribution as a histogram and does not rely on such assumptions. Other advantages over previous in situ methods are that this method only requires a single gamma-ray emission, provides more detailed depth information, and offers a superior ability for characterizing complex depth distributions. Collimated spectrometer measurements of buried area sources demonstrated the ability of the method to yield accurate depth information. Based on the results of actual measurements, this method increases the potential of in situ gamma-ray spectrometry as an independent characterization tool in situations with unknown radionuclide depth distributions. #

A methodological approach for a comparative assessment of ionising radiation effects on man and non-human species, based on the use of Radiation Impact Factor (RIF) -ratios of actual exposure doses to biota species and man to critical dose is described. As such doses, radiation safety standards limiting radiation exposure of man and doses at which radiobiological effects in non-human species were not observed after the Chernobyl accident, were employed. For the study area within the 30 km ChNPP zone dose burdens to 10 reference biota groups and the population (with and without evacuation) and the corresponding RIFs were calculated. It has been found that in 1986 (early period after the accident) the emergency radiation standards for man do not guarantee adequate protection of the environment, some species of which could be affected more than man. In 1991 RIFs for man were considerably (by factor of 20.0-1.1 ! 10 5 ) higher compared with those for selected non-human species. Thus, for the long term after the accident radiation safety standards for man are shown to ensure radiation safety for biota as well.

Shielding is the only practical countermeasure for the exposure to cosmic radiation during space travel. It is well known that light, hydrogenated materials, such as water and polyethylene, provide the best shielding against space radiation. Kevlar and Nextel are two materials of great interest for spacecraft shielding because of their known ability to protect human space infrastructures from meteoroids and debris. We measured the response to simulated heavy-ion cosmic radiation of these shielding materials and compared it to polyethylene, Lucite (PMMA), and aluminum. As proxy to galactic nuclei we used 1 GeV n ؊1 iron or titanium ions. Both physics and biology tests were performed. The results show that Kevlar, which is rich in carbon atoms (about 50% in number), is an excellent space radiation shielding material. Physics tests show that its effectiveness is close (80 -90%) to that of polyethylene, and biology data suggest that it can reduce the chromosomal damage more efficiently than PMMA. Nextel is less efficient as a radiation shield, and the expected reduction on dose is roughly half that provided by the same mass of polyethylene. Both Kevlar and Nextel are more effective than aluminum in the attenuation of heavy-ion dose. Health Phys. 94(3):242-247; 2008

Aim
Data was collected to establish local Diagnostic Reference Levels (DRLs) for the CT component of our most common SPECT/CT studies.

Methods
432 SPECT/CT scans were analysed from Dec 2014 - Dec 2015. CT dose values of CTDIVol (mGy) and DLP (mGycm) were recorded as well as patient’s weight and the anatomical area, for different scan procedures.
Octreotide, MIBG and Lutetium scans, were grouped together as neuro-endocrine tumour (NET) studies.
DRLs for CTDIVol and DLP were calculated as the 75th percentile, from patients weighing 50-90kg following IPEM Report 88.

Results
CTDIVol and DLP DRLs are given below for:
• Hepato-Biliary scans: 2.2mGy and 93mGycm
• I131 post-ablative scans: 2.4mGy and 98mGycm
• Parathyroid scans: 2.6mGy and 107mGycm (with 2 SPECT/CT scans giving a total study DLP of 215mGycm)
• NET studies: 2.2mGy and 171mGycm (ranging from 2.0mGy and 84mGYcm for an Abdo, Pelvis to 2.43mGy and 279mGycm for Head, Chest, Abdo, Pelvis)
• All Bone scans: 11.8mGy and 461mGycm (ranging from 2.2mGy and 91mGycm for low-dose localisation CT of the torso to 16.0mGy and 574mGycm for diagnostic non-contrast CT of the lumbar spine)

Conclusion
Local DRLs were created and can be compared with initial data released by the IPEM working party on Hybrid CT DRLs.

PURPOSE: To record and compare the spectral transmission characteristics of foldable untinted and yellow-tinted intraocular lenses (IOLs) and evaluate the protective effects against retinal damage by sunlight. SETTING: Shimane University Faculty of Medicine, Izumo, Japan. METHODS: The study evaluated 3 untinted IOLs (SA60AT, VA-60BBR, AU6 K) and 3 yellow-tinted IOLs (SN60AT, YA-60BBR, AU6 N) of 3 lens powers (C10.0 diopters [D], C20.0 D, and C30.0 D).

Background: Photoinstability of sunscreens because of ultraviolet (UV) exposure is a well-known and common phenomenon. Recently, it was also shown that sunscreens with complex filter combinations are photoinactivated by UV exposures, which can easily be acquired by solar exposure over several hours. Objectives: To assess the change of the spectral transmission after UV exposure (UV-challenged protective performance) of 27 commercially available photoprotective lipsticks. Methods: Quartz slides were covered with a lipstick layer (area density 1.0 AE 0.1 mg/cm 2 ) and irradiated with increasing doses of solar-simulated radiation. The spectral transmission (T) was measured spectrophotometrically before and after 5, 12.5, 25, and 50 standard erythema doses (SED) of exposure. We calculated the change in transmission (photoinstability) as the difference between the spectral transmission before and after a defined UV exposure, DT, and the arithmetic mean, for both the UVA (DT A ) and UVB (DT B ) ranges. A product was labelled as photounstable if the mean photoinstability in the UVA, DT A , or UVB range, DT B , was higher than 5% for an UV exposure of 12.5 SED. Results: Eleven products showed a significant photoinstability in the UVA range (DT A between 6% and 27%), only one product in the UVB range (DT B 5 13%), and one product in both the UVA (DT A 5 31%) and UVB (DT B 5 9%) range. In one product photoinstability became significant in the UVA range at higher UV exposures. Conclusions: Out of 27 lipsticks only 13 products showed a photostable performance (DT A o5% and DT B o5% for 12.5 SED). We propose therefore that only products, which fulfil these UV photostability criteria should be marketed.

L'administration à un malade d'une activité d'iode 131 supérieure à 720 méga Becquerel (MBq) doit se faire dans un service de médecine nucléaire. Le patient peut retourner au contact du public dès que le débit de dose qu'il émet à 1 mètre est inférieur à 20 mSv/heure. S'il s'agit d'un patient hémodialysé, la première séance d'hémodialyse (HD) assure l'élimination de la majeure partie de la radioactivité. La réglementation française ne donne pas de recommandations pour cette dialyse. Elle demande cependant de stocker les déchets liquides et solides contaminés par des radioéléments. Il paraît donc nécessaire de conserver le dialysat et les déchets solides dans un local de décroissance radioactive. Le seul risque pour le personnel soignant est la contamination interne par ingestion accidentelle d'un liquide biologique du patient. Les protections vestimentaires habituelles de la séance d'HD sont suffisantes : masque, gants, surblouse, calot. Il n'y a aucun risque du fait de l'exposition externe aux radiations. La dose maximale théorique reçue par le soignant lors de la séance serait de 65 mSv, alors que la dose maximale annuelle autorisée pour le public exposé aux radiations est de 1000 mSv. Bien que le suivi dosimétrique du personnel de dialyse ne soit pas nécessaire réglementairement, le service de médecine nucléaire du centre hospitalier universitaire de Marseille a décidé de le faire dans un but d'information. La séance est réalisée en présence d'un technicien de radioprotection qui

Digital radiography systems based on flat-panel detectors have been introduced into clinical practice in the past few years. The high detective quantum efficiency of these detectors allows the radiation dose to be reduced while maintaining image quality, an issue particularly significant for pediatric radiography. Another important aspect for dose optimization and monitoring is the integration of the detector into a computer-controlled x-ray examination system. This enables full control and complete reporting of all dose-relevant exposure parameters, including the determination of the exposure indicator and the patient dose (kerma-area product). In this paper the implementation of these principles in the Philips Digital Diagnost DR system is described and their relevance for pediatric applications is discussed.