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Purpose: In radiation biology, rats are often irradiated, but the precise dose distributions are often lacking, particularly in areas that receive scatter radiation. We used a non-dedicated set of resources to calculate detailed dose distributions, including doses to peripheral organs well outside of the primary field, in common rat exposure settings. Materials and methods: We conducted a detailed dose reconstruction in a rat through an analog to the conventional human treatment planning process. The process consisted of: (i) Characterizing source properties of an X-ray irradiator system, (ii) acquiring a computed tomography (CT) scan of a rat model, and (iii) using a Monte Carlo (MC) dose calculation engine to generate the dose distribution within the rat model. We considered cranial and liver irradiation scenarios where the rest of the body was protected by a lead shield. Organs of interest were the brain, liver and gonads. The study also included paired scenarios where the dose to adjacent, shielded rats was determined as a potential control for analysis of bystander effects. Results: We established the precise doses and dose distributions delivered to the peripheral organs in single and paired rats. Mean doses to non-targeted organs in irradiated rats ranged from 0.03-0.1% of the reference platform dose. Mean doses to the adjacent rat peripheral organs were consistent to within 10% those of the directly irradiated rat. Conclusions: This work provided details of dose distributions in rat models under common irradiation conditions and established an effective scenario for delivering only scattered radiation consistent with that in a directly irradiated rat. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations are increasingly used to reconstruct dose distributions in radiotherapy research studies. Many studies have used the MCNPX Monte Carlo code with a mesh tally for dose reconstructions. However, when the number of voxels in the simulated patient anatomy is large, the computation time for a mesh tally can become prohibitively long. The purpose of this work was to test the feasibility of using lattice tally instead of mesh tally for whole-body dose reconstructions. We did this by comparing the dosimetric accuracy and computation time of lattice tallies with those of mesh tallies for craniospinal proton irradiation. The two tally methods generated nearly identical dosimetric results, within 1% in dose and within 1 mm distance-to-agreement for 99% of the voxels. For a typical craniospinal proton treatment field, simulation speed was 4 to 17 times faster using the lattice tally than using the mesh tally, depending on the numbers of proton histories and voxels. We conclude that the lattice tally is an acceptable substitute for the mesh tally in dose reconstruction, making it a suitable potential candidate for clinical treatment planning. [ABSTRACT FROM AUTHOR]

Linac parameters such as the multi-leaf collimator (MLC) position and jaw position, cumulative monitor units (MUs), and the corresponding gantry angle were recorded during the clinical delivery of volumetric modulated arc therapy for prostate, lung, and head/neck cancer patients. Then, linac parameters were converted into the beam-data format used in the treatment planning system, and the dose distribution was reconstructed. The dose-volume histogram and the dose difference (DD) were compared with the corresponding values in the treatment plan. A reproducible error of in-treatment linac parameters was observed when a sudden change of beam intensity or MLC/jaw speed occurred. The maximum cumulative MU error was more than 4 MU for lung cancer cases, and the maximum MLC position exceeded 5 mm for prostate and head/neck cancer patients. However, these errors were quickly compensated for at the next control point. All treatments analyzed in the present study were delivered within 0.4 % accuracy at the planning target volume. The cumulative dose agreed with that of the plan within 3 % of the prescribed dose. The 1 % DD was 93.9, 99.9, and 93.4 % of the prescription dose for prostate, lung, and head/neck cancer patients, respectively. [ABSTRACT FROM AUTHOR]

This paper analyses the recent legislation and administration of United States nuclear worker compensation – the Energy Employees Occupational Illness Compensation Programme Act (EEOICPA) – in order to show the domestic impacts of war and the social order that has been established to respond to the Cold War legacy of occupational exposures, illness, and death. Examining the epistemological politics and material effects of compensation, an insufficiently analysed aspect of the Cold War, I argue that the system designed to redress the occupational exposures of nuclear workers accomplishes something else: obscuring the ethical problem of misinformation and missing data from the Cold War era; mobilising an industry of knowledge and market–economic opportunities in the arena of biomedical exposure assessment and dose reconstruction for parts of the former US nuclear complex; and, lastly, dematerialising and depoliticising geographies of the Cold War and its differential impacts through an individualistic epidemiological reprocessing of radiation exposures. The paper shows how the general claims procedure, combined with two methods mandated by EEOICPA – dose reconstruction and the probability of causation – effectively de-link workers from each other, and worksites from homes, pin compensation to a cost–benefit logic, implicate genuine scientific complexity and uncertainty in an ongoing denial of the toxic legacies of war, and ethically undermine the social justice aims of the legislation. The article ends by considering some of the ways that US nuclear workers have responded to living as the remains ofbothUS bomb production and the compensation system. [ABSTRACT FROM PUBLISHER]

Abstract: A UV model is proposed to reconstruct the biologically weighted doses at the ground-level, erythemal, vitamin D3, and antipsoriatic effective doses, based on the space data from the Ozone Monitoring Instrument on board of NASA EOS Aura spacecraft for the period 2005–2011. The model is training using the results of spectral UV measurements carried out at Belsk, Poland. The model outcome is verified using the UV spectra measured at Hradec Kralove, Czech Republic. The model uncertainty is almost the same for all examined action spectra and comparable to that found in earlier studies on differences between the satellite overpasses and ground-based erythemal data. Antipsoriatic doses, taken during 2h exposure periods near local noon, are reconstructed for selected sites in Poland to find if heliotherapy would be an alternative to standard treatment of psoriasis by tube irradiation in medical cabinets. Mountain-resort in the southern Poland, Zakopane, and rural-site in Central Poland, Belsk, are among the best location of potential heliotherapy centers in Poland for late spring/summer season. Łeba, resort on the Baltic Sea coast, is a potential heliotherapy center in June and July. The methodology to disclose possible heliotherapy periods over the territory of Poland could be extended to any region. It would help to prepare an optimal schedule of antipsoriatic heliotherapy that accounts for local weather conditions and medical standards of using UV cabinets. [Copyright &y& Elsevier]

BACKGROUND: Di(2-ethylhexyl) phthalate (DEHP), used primarily as a plasticizer for polyvinyl chloride, is found in a variety of products. Previous studies have quantified human exposure by back calculating intakes based on DEHP metabolite concentrations in urine and by determining concentrations of DEHP in exposure media (e.g., air, food, dust). OBJECTIVES: To better understand the timing and extent of DEHP exposure, we used a simple pharmacokinetic model to "reconstruct" the DEHP dose responsible for the presence of DEHP metabolites in urine. METHODS: We analyzed urine samples from eight adults for four DEHP metabolites [mono(2-ethyl-hexyl) phthalate, mono(2-ethyl-5-hydroxyhexyl) phthalate, mono(2-ethyl-5-oxohexyl) phthalate, and mono(2-ethyl-5-carboxypentyl) phthalate]. Participants provided full volumes of all voids over 1 week and recorded the time of each void and information on diet, driving, and outdoor activities. Using a model previously calibrated on a single person self-dosed with DEHP in conjunction with the eight participants' data, we used a simple trial-and-error method to determine times and doses of DEHP that resulted in a best fit of predicted and observed urinary concentrations of the metabolites. RESULTS: The average daily mean and median reconstructed DEHP doses were 10.9 and 5.0 Φg/kg-day, respectively. The highest single modeled dose of 60 Μg/kg occurred when one study participant reported consuming coffee and a bagel with egg and sausage that was purchased at a gas station. About two-thirds of all modeled intake events occurred near the time of reported food or beverage consumption. Twenty percent of the modeled DEHP exposure occurred between 2200 hours and 0500 hours. CONCLUSIONS: Dose reconstruction using pharmacokinetic models -- in conjunction with biomonitoring data, diary information, and other related data -- can provide a powerful means to define timing, magnitude, and possible sources of exposure to a given contaminant. [ABSTRACT FROM AUTHOR]

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Abstract: Aim: To assess target volume coverage during prostate image-guided radiotherapy based on bony anatomy alignment and to assess possibility of safety margin reduction. Background: Implementation of IGRT should influence safety margins. Utilization of cone-beam CT provides current 3D anatomic information directly in irradiation position. Such information enables reconstruction of the actual dose distribution. Materials and methods: Seventeen prostate patients were treated with daily bony anatomy image-guidance. Cone-beam CT (CBCT) scans were acquired once a week immediately after bony anatomy alignment. After the prostate, seminal vesicles, rectum and bladder were contoured, the delivered dose distribution was reconstructed. Target dose coverage was evaluated by the proportion of the CTV encompassed by the 95% isodose. Original plans employed a 1cm safety margin. Alternative plans assuming a smaller 7mm margin between CTV and PTV were evaluated in the same way. Rectal and bladder volumes were compared with the initial ones. Rectal and bladder volumes irradiated with doses higher than 75Gy, 70Gy, 60Gy, 50Gy and 40Gy were analyzed. Results: In 12% of reconstructed plans the prostate coverage was not sufficient. The prostate underdosage was observed in 5 patients. Coverage of seminal vesicles was not satisfactory in 3% of plans. Most of the target underdosage corresponded to excessive rectal or bladder filling. Evaluation of alternative plans assuming a smaller 7mm margin revealed 22% and 11% of plans where prostate and seminal vesicles coverage, respectively, was compromised. These were distributed over 8 and 7 patients, respectively. Conclusion: Sufficient dose coverage of target volumes was not achieved for all patients. Reducing of safety margin is not acceptable. Initial rectal and bladder volumes cannot be considered representative for subsequent treatment. [Copyright &y& Elsevier]

Purpose: We have developed a megavoltage CT (MVCT)-based dose reconstruction strategy for total body irradiation (TBI) with helical TomoTherapy (HT) using a deformable registration model to account for the patient’s interfraction changes. The proposed technique serves as an efficient tool for delivered dose verification and, potentially, plan adaptation. Methods and Materials: Four patients with acute myelogenous leukemia treated with TBI using HT were selected for this study. The prescription was 12 Gy, 2 Gy/fraction, twice per day, given at least 6 h apart. The original plan achieved coverage of 80% of the clinical target volume (CTV) by the 12 Gy isodose surface. MVCTs were acquired prior to each treatment. Regions of interest were contoured on each MVCT. The dose for each fraction was calculated based on the MVCT using the HT planned adaptive station. B-spline deformable registration was conducted to establish voxel-to-voxel correspondence between the MVCT and the planning CT. The resultant deformation vector was employed to map the reconstructed dose from each fraction to the same point as the plan dose, and a voxel-to-voxel summed dose from all six fractions was obtained. The reconstructed dose distribution and its dosimetric parameters were compared with those of the original treatment plan. Results: While changes in CTV contours occurred in all patients, the reconstructed dose distribution showed that the dose-volume histogram for CTV coverage was close (<1.5%) to that of the original plan. For sensitive structures, the differences between the reconstructed and the planned doses were less than 3.0%. Conclusion: Voxel-based dose reconstruction strategy that takes into account interfraction anatomical changes using MVCTs is a powerful tool for treatment verification of the delivered doses. This proposed technique can also be applied to adaptive TBI therapy using HT. [ABSTRACT FROM AUTHOR]

Abstract: Background and purpose: IMRT QA is commonly performed in a phantom geometry but the clinical interpretation of the results in a 2D phantom plane is difficult. The main objective of our work is to move from film measurement based QA to 3D dose reconstruction in a patient CT scan. In principle, this could be achieved using a dose reconstruction method from 2D detector array measurements as available in the COMPASS system (IBA Dosimetry). The first step in the clinical introduction of this system instead of the currently used film QA procedures is to test the reliability of the dose reconstruction. In this paper we investigated the validation of the method in a homogeneous phantom with the film QA procedure as a reference. We tested whether COMPASS QA results correctly identified treatment plans that did or did not fulfil QA requirements in head and neck (H&N) IMRT. Materials and methods: A total number of 24 treatments were selected from an existing database with more than 100 film based H&N IMRT QA results. The QA results were classified as either good, just acceptable or clinically rejected (mean gamma index <0.4, 0.4–0.5 or >0.5, respectively with 3%/3mm criteria). Film QA was repeated and compared to COMPASS QA with a MatriXX detector measurement performed on the same day. Results: Good agreement was found between COMPASS reconstructed dose and film measured dose in a phantom (mean gamma 0.83±0.09, 1SD with 1%/1mm criteria, 0.33±0.04 with 3%/3mm criteria). COMPASS QA results correlated well with film QA, identifying the same patients with less good QA results. Repeated measurements with film and COMPASS showed changes in delivery after a modified MLC calibration, also visible in a standard MLC check in COMPASS. The time required for QA reduced by half by using COMPASS instead of film. Conclusions: Agreement of COMPASS QA results with film based QA supports its clinical introduction for a phantom geometry. A standard MLC calibration check is sensitive to <1mm changes that could be significant in H&N IMRT. These findings offer opportunities to further investigate the method based on a 2D detector array to 3D dose reconstruction in a patient anatomy. [Copyright &y& Elsevier]

Abstract: The nuclear workers of the Mayak Production Association had regular check-ups including medical diagnostic X-ray examinations since start of the production lines in 1948. Doses from diagnostic examinations need to be considered in reconstruction of occupational doses of the workers with electron paramagnetic resonance (EPR) of tooth enamel. The numbers and types of examinations of an individual worker can be assessed from the Mayak PA archives but no information was available on doses delivered to teeth by a single specific examination. Of the twenty one applied examination procedures only three affected the teeth, these being X-ray examinations of teeth, skull and cervical spine. For these three kinds of examinations operational procedures and operating modes of X-ray units were compiled from the archive and photon spectra were obtained from a catalog of spectral data for diagnostic X-rays. Entrance doses in air kerma were calculated using the fluence of photon spectra and absorbed dose in tooth enamel for various tooth positions and exposure geometry was then calculated using dose conversion coefficients obtained from Monte Carlo simulations. Doses were calculated for examinations in 1948–2000. Except for examination of the skull, absorbed doses in enamel of incisors were found to be about twice as large as in enamel of molars. In the period before 1970 the largest mean absorbed doses in tooth enamel were due to X-ray examination of teeth, with 64 mGy and 34 mGy calculated for incisors and molars, respectively. In the same period the lowest mean doses were due to X-ray examination of the skull, with 11 mGy and 12 mGy calculated for incisors and molars, respectively. In the period from 1970 to 2000, largest mean doses in enamel were due to X-ray examination of cervical spine, with 23 mGy and 12 mGy calculated for incisors and molars, respectively. [Copyright &y& Elsevier]

Our purpose was to present the clinical feasibility of TBI with helical tomotherapy (HT) in four patients with AML. Treatment planning, delivery, dose verification and summation, toxicity and patient outcomes for each patient are presented. TBI prescription was set in such a manner that 80% of the clinical target volume received 12 Gy in six fractions, at two fractions per day. Dose reconstruction was carried out by recontouring the regions of interest in the daily pretreatment megavoltage computed tomography of each individual fraction and calculating its corresponding dose. A deformable registration model was used for dose summation of all individual fractions. Differences between planned and delivered doses were calculated. Average planned and delivered doses to the regions of interest differed by up to 2.7%. TBI toxicity was limited to radiotherapy oncology group grade 1 dermatitis in all patients and grade 1 headache in one patient. Two patients are alive with no evidence of disease and no GVHD. Two patients died of GVHD, but there was no evidence of disease at the time of death. We conclude that HT simplifies the process of TBI. Dose verification is possible with HT showing small differences between plan and delivered doses. [ABSTRACT FROM AUTHOR]

Aims: To determine variation in the actual doses delivered to the organs at risk and the target in patients treated for localized carcinoma of the prostate using image-guided radiotherapy. Materials and Methods: Ten patients treated with helical TomoTherapy underwent daily target localization with megavoltage CT, on which the prostate, rectum and bladder were recontoured. The planned adaptive module was used for dose recalculation. The study endpoints were to analyse the variations in certain dose-volume parameters of the rectum and bladder (BD2cc, RD2cc, BV100%, BV70%, RV100%, RV70%), the maximum anteroposterior (AP) and lateral rectal diameters, the volume of the CTV receiving 100% of the prescription dose (CTV V100%) and the dose to 100% of the CTV (CTV D100%). Results: The difference between the planned and delivered target doses (CTV V100% and CTV D100%) was small and clinically insignificant indicating adequate target coverage during treatment. There was a large variation in the AP and lateral rectal diameters, with no particular trend or correlation to dose parameters being noted during the course of treatment. The mean AP diameter during treatment was significantly less than the planned diameter (P < 0.05). The percentage of fractions where the delivered BV100%, BV70%, RV100%, and RV70% was more than the planned values were 42.8%, 17.1%, 45.4%, and 44.4%, respectively. The delivered BD2cc and RD2cc were similar to their planned values. Conclusions: This study demonstrates the usefulness of daily soft tissue image guidance in negating the effects of physiological variation of the rectum and bladder on the dose delivered to the prostate. [ABSTRACT FROM AUTHOR]

Abstract: Optically stimulated luminescence (OSL) dosimetry is applied to quartz extracted from bricks from a mill in a contaminated village (Muslyumovo) of the Techa River valley, Southern Urals, Russia, for the purpose of dose reconstruction. Previous works [. First international intercomparison of luminescence techniques using samples from the Techa river valley. Health Phys. 82, 94–101] have shown that the expected dose due to man-made sources of radiation in the bricks is in the same range as the background dose due to natural sources of radiation, therefore a precise estimate of the cumulative and background dose is of utmost importance. Cumulative doses could be assessed with OSL with a precision of around 4% and lie between 450 and 600mGy. The background dose was carefully determined by a combination of laboratory measurements, in-situ gamma spectrometry and Monte Carlo modelling. The results show that the gamma-dose rate of the soil was overestimated and the fractional brick gamma-dose rate underestimated in previous studies, but that the overall gamma-dose rate was nearly correct, due to mutual compensation. The obtained anthropogenic doses in brick measured with OSL lie between 200 and 300mGy, show variability between adjacent bricks within error limits for one spot but a significant difference for two samples is observed for another spot. A distinct dependency of measured dose upon sample height is observed, which is an indication of a source distribution, which extends over a large area and up to a certain depth into the soil and in which higher contaminated areas are located at a greater distance to the mill than lower contaminated areas. A measured dose–depth profile is compared with previously published Monte Carlo calculations to verify the source energy. [Copyright &y& Elsevier]

Abstract: Treatment of food with ionising radiations in order to increase its shelf-life is largely employed in many countries. Because of restrictions issued by different governments on the use of this technique, in addition to the identification of irradiated foodstuffs, it may be important to determine the radiation dose administered to the foodstuffs. An EPR based protocol to reconstruct the administered dose from samples of irradiated meats (rabbit, pork and duck) within an uncertainty of ±25% is reported. [Copyright &y& Elsevier]

Exposure reconstruction for substances of interest to human health is a process that has been used, with various levels of sophistication, as far back as the 1930s. The importance of robust and high-quality exposure reconstruction has been recognized by many researchers. It has been noted that misclassification of reconstructed exposures is relatively common and can result in potentially significant effects on the conclusions of a human health risk assessment or epidemiology study. In this analysis, a review of the key exposure reconstruction approaches described in over 400 papers in the peer-reviewed literature is presented. These approaches have been critically evaluated and classified according to quantitative, semiquantitative, and qualitative approaches. Our analysis indicates that much can still be done to improve the overall quality and consistency of exposure reconstructions and that a systematic framework would help to standardize the exposure reconstruction process in the future. The seven recommended steps in the exposure reconstruction process include identifying the goals of the reconstruction, organizing and ranking the available data, identifying key data gaps, selecting the best information sources and methodology for the reconstruction, incorporating probabilistic methods into the reconstruction, conducting an uncertainty analysis, and validating the results of the reconstruction. Influential emerging techniques, such as Bayesian data analysis, are highlighted. Important issues that will likely influence the conduct of exposure reconstruction into the future include improving statistical analysis methods, addressing the issue of chemical mixtures, evaluating aggregate exposures, and ensuring transparency with respect to variability and uncertainty in the reconstruction effort. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: High geometrical and dosimetrical accuracies are required for radiotherapy treatments where IMRT is applied in combination with narrow treatment margins in order to minimize dose delivery to normal tissues. As an overall check, we implemented a method for reconstruction of the actually delivered 3D dose distribution to the patient during a treatment fraction, i.e., the ‘dose of the day’. In this article results on the clinical evaluation of this concept for a group of IMRT prostate cancer patients are presented. Materials and methods: The actual IMRT fluence maps delivered to a patient were derived from measured EPID-images acquired during treatment using a previously described iterative method. In addition, the patient geometry was obtained from in-room acquired cone-beam CT images. For dose calculation, a mapping of the Hounsfield Units from the planning CT was applied. With the fluence maps and the modified cone-beam CT the ‘dose of the day’ was calculated. The method was validated using phantom measurements and evaluated clinically for 10 prostate cancer patients in 4 or 5 fractions. Results: The phantom measurements showed that the delivered dose could be reconstructed within 3%/3mm accuracy. For prostate cancer patients, the isocenter dose agreed within −0.4±1.0% (1 SD) with the planned value, while for on average 98.1% of the pixels within the 50% isodose surface the actually delivered dose agreed within 3% or 3mm with the planned dose. For most fractions, the dose coverage of the prostate volume was slightly deteriorated which was caused by small prostate rotations and small inaccuracies in fluence delivery. The dose that was delivered to the rectum remained within the constraints used during planning. However, for two patients a large degrading of the dose delivery was observed in two fractions. For one patient this was related to changes in rectum filling with respect to the planning CT and for the other to large intra-fraction motion during treatment delivery, resulting in mean underdosages of 16% in the prostate volume. Conclusions: A method to accurately assess the ‘dose of the day’ was evaluated for prostate cancer patients treated with IMRT. To correct for observed dose deviations off-line dose-adaptive strategies will be developed. [Copyright &y& Elsevier]

The article focuseson a study which reconstructed radiation doses in patients with thyroid cancer after the Chernobyl accident. The researchers conducted a population-based case-control study of people with such medical condition in the regions of Russia as well as Belarus. They found that the subjects' consumption of milk produced locally was the most essential pathway of their thyroid exposure after the accident.

Purpose: Improved radiotherapy dose delivery techniques over the past decade have increased the necessity for accurate, independent verification of delivered dose. Compton camera imaging (CCI) systems may have the potential to quantitatively reconstruct three-dimensional dose delivered to the patient with little or no a priori information. Methods: In this work, the adequacy of a Compton camera imaging system for application to radiotherapy dose reconstruction is explored using analytical models of system spatial and dosimetric resolution. The effects of scatter and absorption detector energy resolution, initial photon energy, and detector separation distance on system performance were calculated with the goal of determining whether current detector technology is adequate for such an application. Results: Results indicate that the energy and spatial resolutions associated with current Si and Ge double-sided strip detectors in a planar configuration is sufficient to determine dose deposition to within an average of 1.9 mm and 2.5%. Minimum values of less than 0.5 mm and 1% are achievable under certain conditions. As the energy of the photon incident on the patient increases from 1.0 to 10 MeV, system performance improves at the expense of the range of patient and detector scattering angles over which the system is capable of reconstructing dose deposition to within the acceptable upper limits of 5 mm and 5%. System performance also improves with increasing distance between the scatter and absorption detectors, but is acceptable throughout the range of values likely to be associated with a gantry-mounted system (2–20 cm). Conclusions: The results indicate that Compton camera imaging systems based on current solid-state detector technology have the potential to provide independent verification of dose delivered to a patient during radiation therapy. Further consideration must be given to detector efficiency and image reconstruction algorithms for this application of CCI systems. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: To correct megavoltage cone-beam CT (MVCBCT) images of the thorax and abdomen for cupping and truncation artefacts to reconstruct the 3D-delivered dose distribution for treatment evaluation. Materials and methods: MVCBCT scans of three phantoms, three lung and two rectal cancer patients were acquired. The cone-beam projection images were iteratively corrected for cupping and truncation artefacts and the resulting primary transmission was used for cone-beam reconstruction. The reconstructed scans were merged into the planning CT scan (MVCBCT+). Dose distributions of clinical IMRT, stereotactic and conformal treatment plans were recalculated on the uncorrected and corrected MVCBCT+ scans using the treatment planning system and compared to the planned dose distribution. Results: The dose distributions on the corrected MVCBCT+ of the phantoms were accurate for 99% of the voxels within 2% or 2mm. Using this method the errors in mean GTV dose reduced from about 10% to 1% for the patients. Conclusions: The method corrects cupping and truncation artefacts in cone-beam scans of the thorax and abdomen in addition to head-and-neck (demonstrated previously). The corrected scans can be used to calculate the influence of anatomical changes on the 3D-delivered dose distribution. [Copyright &y& Elsevier]

Abstract: Purpose: To implement a 3D dose verification procedure, based on in-room cone-beam CT imaging and portal dosimetry, for lung cancer patients treated with stereotactic body radiotherapy (SBRT). Materials and methods: MV cone-beam CT scans were made for patient positioning and calibrated for dose calculation purposes. Prior to treatment, the treatment fields were captured using a calibrated electronic portal imaging device (EPID). A Monte Carlo dose reconstruction model was used to estimate the 3D dose delivered to the patient inside the cone-beam CT images. The planned and delivered dose distributions were compared for 4 patients and 10 treatment fractions using dose–volume histograms and gamma analysis. Results: The gamma analysis showed a good agreement between the planned and delivered dose distributions for patients without changes in anatomy. The delivered mean dose per fraction inside the target volume deviated on average 1.1±1.4% from the planned dose. For the critical organs, only minor differences were observed between the reconstructed and planned dose. Conclusions: A method was presented that allows verification of the dose delivered in 3D for lung cancer patients treated with SBRT. The procedure is independent of the treatment planning system and uses in-room MV cone-beam CT imaging and portal dosimetry. [Copyright &y& Elsevier]

The article presents a study on a method for calculating the accumulated dose (AD) in electron spin resonance (ESR) dating and retrospective dosimetry. The study proposes the use of a new method to correct the spectrum before the measurement of the signal intensity. It used fossil teeth from Stegomastodon and Hippidion from the southern Brazilian megafauna irradiated up to 2,500 gray (Gy) with a Cobalt γ-ray source to determine AD. One of the samples presents a dose-independent signal in the region with g-factor 2.0025.

The article presents a study of the neutron dose conversion coefficients calculation in human tooth enamel in an anthropomorphic phantom. To model the human body, the study used the hermaphrodite adult mathematical model designed by Cristy and Eckerman, as well as a geometric model of the human dental region inserted in the Monte Carlo N-Particle (MCNP) code. The study demonstrates the dependence of tooth enamel-absorbed dose on both the incident neutron energy and irradiation geometry.

The article describes Simulation of External Source Accident with MEdical images (SESAME), a tool specific to dosimetric reconstruction of radiological accidents through numerical simulations which combine voxel geometry and the radiation-material interaction MCNP(X) Monte Carlo computer code with a user-friendly Graphical User Interface. It explores the experimental validation of the tool using a photon field. Information is given on the application of the tool to an accident which occurred in Chile in December 2005.

Abstract: The studies undertaken by the 131I Working Group, part of the International Atomic Energy Agency''s EMRAS (Environmental Modelling for Radiation Safety) programme, were focused primarily on evaluating the predictive capability of environmental models. Particular emphasis was placed on applying models to evaluate the effectiveness of countermeasures. [Copyright &y& Elsevier]

For intensity modulated radiation treatment (IMRT) dose reconstruction, multileaf collimator (MLC) log files have been shown applicable for deriving delivered fluence maps. However, MLC log files are dependent on the accuracy of leaf calibration and only available from one linear accelerator manufacturer. This paper presents a proof of feasibility and principles in (1) using an amorphous silicon electronic portal imaging device (aSi-EPID) to capture the MLC segments during an IMRT delivery and (2) reconstituting a leaf sequence (LS) file based on the leaf end positions calculated from the MLC segments and their associated fractional monitor units. These EPID-measured LS files are then used to derive delivered fluence maps for dose reconstruction. The developed approach was tested on a pelvic phantom treated with a typical prostate IMRT plan. The delivered fluence maps, which were derived from the EPID-measured LS files, showed slight differences in the intensity levels compared with the corresponding planned ones. The dose distribution calculated with the delivered fluence maps showed a discernible difference in the high dose region when compared to that calculated with the planned fluence maps. The maximum dose in the former distribution was also 2.5% less than that in the latter one. The EPID-measured LS file can serve the same purpose as a MLC log files does for the derivation of the delivered fluence map and yet is independent of the leaf calibration. The approach also allows users who do not have access to MLC log files to probe the actual IMRT delivery and translate the information gained for dose reconstruction in adaptive radiation therapy. [ABSTRACT FROM AUTHOR]

The article discusses a study which investigated the application of a comprehensive probabilistic uncertainty analysis to estimate the intake and doses of depleted uranium (DU) in urine. The investigation considered the Parametric uncertainties in the International Commission on Radiological Protection (ICRP) Human Respiratory Tract Model (HRTM) and ICRP systemic model for uranium. It only focused on DU exposure through inhalation. The parameters that determine lung deposition are also described. It was discovered that the overall uncertainty on dose was about a factor of 50 to 10 days after inhalation.

The article presents a study of a tritium dose reconstruction from the Livermore site of Lawrence Livermore National Laboratory (LLNL) in California from 1953 through 2005. Tritium has been released to the atmosphere from facilities at the site as part of routine operations after the establishment of the laboratory. The laboratory has always reported releases and calculated doses in compliance with regulatory requirements. However, annual doses of tritium were not calculated prior to 1973. Acute exposures to tritium through inhalation, ingestion and dermal pathways are unlikely to result to adverse health effects.

The article discusses how the technical aspects of the Energy Employees Occupational Illness Compensation Program Act of 2000 (EEOICPA) that favor the claimants are being implemented in the U.S. It states that there are many claimant, favorable factors inherent in both the reconstruction of radiation dose and the calculation of probability of causation under Part B of the EEOICPA in the U.S. These factors, according to the authors, result in an approximate 30% compensation rate for claims filed under EEOICPA, which is roughly an order of magnitude greater than the likely incidence of increased cancers as predicted by epidemiology studies and risk models.

The article describes models and methods that are incorporated in the Interactive RadioEpidemiological Program (IREP) to estimate cancer risks and the probability that a given cancer in a worker was induced by given exposures to ionizing radiation. IREP, a Web-based, interactive computer code, was developed by a Working Group of the National Cancer Institute in the U.S. An important characteristic of IREP is that it accounts for uncertainties in estimating cancer risks due to exposure to ionizing radiation and in evaluating causation of a given cancer in an employee.

The article discusses the challenges in reconstructing radiation doses from occupationally required medical ex-rays. Most nuclear weapons complex employees in the U.S. were required to undergo medical x-ray examinations as a condition of their employment. To ensure that their dose reconstructions are complete, it is important to include the contributions from these examinations. X-ray procedures that must be evaluated include: posterior-anterior and lateral radiography, and/or photofluorography, of the chest; anterior-posterior, lateral and oblique lumbar, cervical and thoracic radiography of the spine; and radiography of the pelvis. The article emphasizes the importance of the x-ray beam size for the purpose of dose reconstruction.

The article discusses the assessment of external dose reconstruction under Part B of the Energy Employees Occupational Illness Compensation Program Act in the U.S. External doses include not only those that were recorded by personal dosimeters, but also those that were not recorded. Recorded doses may require corrections to account for measurement bias in the dosimeters' capabilities. Unrecorded doses that have been reconstructed include: those missed due to limits of detection associated with personal dosimeters; external ambient doses that may have been omitted from the monitoring results; and those incurred as a result of medical x-ray examinations required by employers.

The article discusses methods used to calculate organ doses from internally deposited radionuclides under the Radiation Dose Reconstruction Program of the U.S. National Institute for Occupational Safety and Health (NIOSH). During the initial phases of the program, calculations were performed using the Integrated Modules for Bioassay Analysis program. However, limitations associated with this program created inefficiencies in the processing of claims. As a result, NIOSH created a suite of tools to expedite the process. The first of these was the Chronic Annual Dose Workbook program, which permits a dose reconstructor to calculate, in a single step, an organ dose that involves up to 255 separate intakes in any combination of radionuclides, intake modes, and absorption types.

The article highlights the evaluation of a Special Exposure Cohort petition filed on behalf of workers at the Rocky Flats Plant. As part of the evaluation, the U.S. National Institute for Occupational Safety and Health (NIOSH) was required to demonstrate that bounding values could be established for radiation doses due to the potential intake of all radionuclides present at the Rocky Flats. The main radioactive elements of interest at the facility were plutonium and uranium, but much smaller quantities of several other elements, including thorium. The results of NIOSH's investigation of the uses of thorium at Rocky Flats are presented.

The article discusses the reconstruction of internal doses under Part B of the Energy Employees Occupational Illness Compensation Program Act differs which differs ways from that used in a typical operational setting. Under the legislation, no limits at or above which doses must be assessed; all doses, including unmonitored or potentially undetected doses, must be reconstructed. Also, the primary dose of concern is that delivered to the organ in which the cancer originated, and only the dose delivered to that organ prior to the time the cancer was diagnosed is relevant. To address these problems, the U.S. National Institute for Occupational Safety and Health (NIOSH) adopted a set of default values that are favorable to the claimant when there is more than one plausible choice.

The article presents a summary of the development of the ambient environmental dose profile for the Savannah River Site (SRS) for specific time periods from 1951-2001. Dose profiles were developed under the Radiation Dose Reconstruction Program of the U.S. National Institute for Occupational Safety and Health (NIOSH). Internal doses were estimated based on the radionuclide concentrations in the atmosphere, while external doses were estimated on the basis of releases of noble gases and contributions from ambient background radiation.

The article discusses the development of site profiles for dose reconstruction used in worker compensation claims under the Radiation Dose Reconstruction Program of the U.S. National Institute for Occupational Safety and Health (NIOSH). The NIOSH developed site profiles for all the major U.S. Department of Energy (DOE) sites and Atomic Weapons Employer sites. Site profiles provide a brief, general overview of the site. These documents also identify the facilities on site with a brief description of the processes and radionuclides used in these processes.

The article discusses the collection, processing, validation, verification, formatting, filing, and storage of the data for the Radiation Dose Reconstruction Program of the U.S. National Institute for Occupational Safety and Health (NIOSH). It states that the quality and scientific validity of the reconstructed dose estimates are dependent on these aspects of the program. It is important that the data be filed not only in a readily accessible format, but also in one of that facilitates error-free retrievability.

The article discusses the responsibilities and activities of the Advisory Board on Radiation and Worker Health appointed by the president of the U.S. in October 2001. The activity of the Board is conducted with staff support provided by the U.S. National Institute for Occupational Safety and Health (NIOSH). The NIOSH establishes scientific guidelines for determining whether an employee's cancer is at least as likely as not related to occupational exposure to radiation. It is stated that during the first 5 years of operation, the Board has provided substantial input on the rulemaking activities of NIOSH.

The article identifies the challenges in managing the Radiation Dose Reconstruction Project of the U.S. National Institute for Occupational Safety and Health (NIOSH). From the initial stages of the project, there were many technical and managerial challenges that required continuous planning, integration, and conflict resolution. The most complex challenge, according to the article, has been to complete defensible, individualized dose reconstructions that support timely compensation decisions at an acceptable production level. The lessons learned from the project are also discussed.

This article discusses a study which aimed to estimate the individual thyroid doses to the study subjects resulting from radioactive fallout from the atmospheric nuclear weapons tests conducted in French Polynesia. The authors conducted the study based on the available historical results of radiometric measurements and meteorological data. They found that the reconstructed doses are associated with high uncertainties arising from: the assumptions made and variability of parameters of dosimetric models; the procedures of interpolation and extrapolation applied reconstruct the environmental radiation field in locations where measurements were not performed; and uncertainties attached to the personal information from questionnaires.

Purpose: Head-and-neck (HN) cone-beam computed tomography (CBCT) can be exploited to probe the IMRT dose delivered to a patient taking into account the interfraction anatomic variation and any potential inaccuracy in the IMRT delivery. The aim of this work is to reconstruct the intensity-modulated radiation therapy dose delivered to an HN patient using the CBCT and multileaf collimator (MLC) log-files. Methods and Materials: A cylindrical CT phantom was used for calibrating the electron density and validating the procedures of the dose reconstruction. Five HN patients were chosen, and for each patient, CBCTs were performed on three separate fractions spaced every 2 weeks starting from the first fraction. The respective MLC log-files were retrieved and converted into fluence maps. The dose was then reconstructed on the corresponding CBCT with the regenerated fluence maps. The reconstructed dose distribution, dosimetric endpoints, and DVHs were compared with that of the treatment plan. Results: Phantom study showed that HN CBCT can be directly used for dose reconstruction. For most treatment sessions, the CBCT-based dose reconstructions yielded DVHs of the targets close (within 3%) to that of the original treatment plans. However, dosimetric changes (within 10%) due to anatomic variations caused by setup inaccuracy, organ deformation, tumour shrinkage, or weight loss (or a combination of these) were observed for the critical organs. Conclusions: The methodology we established affords an objective dosimetric basis for the clinical decision on whether a replanning is necessary during the course of treatment and provides a valuable platform for adaptive therapy in future. [Copyright &y& Elsevier]

Abstract: A model is proposed to explain that in previously irradiated calcite, the yield after additive irradiation tends to incline to the saturation yield of the radiation even if that yield is lower than the yield after the irradiation. However, the proposed model is not specific for calcite and in fact all calculations are done in a fictive material. The proposed model considers, in contrast to existing models, the track nature of and radiations and that these different types of radiations can be distinguished by the dose distribution inside their tracks. The determination of the dose distribution in the tracks for the different types of irradiations is quite complicated and instead we approximate the and tracks by type A and B tracks that have different but homogeneously distributed dose in their track volumes. The trapping of generated free charges in the track was calculated with a simple one electron–one hole trap model. To obtain the total dose response (the average concentration of occupied traps as a function of dose), the yield in one point was averaged over all possible configurations of track overlapping in that point. We determined the slope of the initial part of the response curve (low dose sensitivity) and the saturation yield as function of the track dose. It is observed that the low dose sensitivity and saturation yield both decrease with increasing track dose. Simulations of the response to sequential irradiation first by type A radiation with a 64Gy track dose and then followed by type B radiation with a track dose of 128Gy using our model show a similar effect as observed in calcite demonstrating that the track nature of radiation is a plausible cause for the observed effect. [Copyright &y& Elsevier]

This article discusses a historical analysis of employee safety from dose reconstruction of air exposure at nuclear processing facilities in the United States. According to the authors, the Atomic Energy Commission and its predecessors used a time weighted daily average to estimate concentrations of airborne thorium, uranium, radon, and radon decay products. The authors used Monte Carlo methods to determine the uncertainty and variability in these concentration estimates. They conclude that errors in recording and arithmetic are responsible for significant variability.

Abstract: Background and purpose: Verification of the actually delivered 3D dose distribution during each treatment fraction (“dose of the day”) is the most complete and clinical relevant “in-vivo” check of an IMRT treatment. To do this, during patient treatment portal dose images are routinely acquired with our electronic portal imaging device to derive the delivered fluence map for each treatment field. In addition, a conebeam CT scan is acquired just prior to treatment to derive the patient geometry at the time of treatment. However, the use of conebeam CT scans for dose calculation is hampered by inaccuracies in the conversion of CT values to electron densities due to an enlarged scatter contribution. Materials and methods: In this work, a method is described for mapping of Hounsfield Units of the planning CT to the conebeam CT scan, while accounting for non-rigidity in the anatomy, e.g. related to weight loss, in an approximate way. The method was validated for head and neck cancer patients by comparing dose distributions calculated using adjusted Hounsfield Units with a golden standard. Results and conclusions: The observed dose differences were less than 1% in the majority of points, and in at least 96% of the points a 3D γ analysis resulted in γ values of less than 1 when applying a 2%/2mm criterion, showing that this straightforward approach allows for an accurate dose calculation based on conebeam CT scans. [Copyright &y& Elsevier]