Lessons from past radiation accidents: Critical review of methods addressed to individual dose assessment of potentially exposed people and integration with medical assessment.

The experiences of the Chernobyl and Fukushima nuclear accidents showed that dosimetry was the essential tool in the emergency situation for decision making processes, such as evacuation and application of protective measures. However, at the consequent post-accidental phases, it was crucial also for medical health surveillance and in further adaptation to changed conditions with regards to radiation protection of the affected populations. This review provides an analysis of the experiences related to the role of dosimetry (dose measurements, assessment and reconstruction) regarding health preventive measures in the post-accidental periods on the examples of the major past nuclear accidents such as Chernobyl and Fukushima.

Development of a dosimetric model for in vitro labelled cells with β emitters in PET tracking studies.

Positron emission tomography (PET) offers an effective method for tracking β emitters-labeled cells in vivo. However, in vitro high labelling activities used may cause cell damage or death. Our understanding of the impact of such procedure remains limited by the fact that the biological effects are usually linked to the activity per cell rather than the absorbed dose.

Monitoring and Dose Assessment for Children Following a Radiation Emergency-Part II: Calibration Factors for Thyroid Monitoring.

Past radiological and nuclear accidents have demonstrated that monitoring a large number of children following a radiological and nuclear emergency can be challenging, in accommodating their needs as well as adapting monitoring protocols and applying age-specific biokinetics to account for various ages and body sizes. This paper presents the derived calibration factors for thyroid monitoring of children of all ages recommended by the International Commission on Radiological Protection using four selected detectors at given times following a short-term (acute) intake of I by inhalation. These calibration factors were derived by Monte Carlo simulations using the models of various detectors and pediatric voxel phantoms.

Ra-dichloride therapy of bone metastasis: optimization of SPECT images for quantification.

Background: Ra imaging is crucial to evaluate the successfulness of the therapy of bone metastasis of castration-resistant prostate cancer (CRPC). The goals of this study were to establish a quantitative tomographic Ra imaging protocol with clinically achievable conditions, as well as to investigate its usefulness and limitations. We performed several experiments using the Infinia Hawkeye 4 gamma camera (GE) and physical phantoms in order to assess the optimal image acquisition and reconstruction parameters, such as the windows setting, as well as the iteration number and filter of the reconstruction algorithm.

INITIAL EVALUATION OF INDIVIDUAL DOSES IN THE EARLY PHASE OF A NUCLEAR REACTOR ACCIDENT BASED ON IN-VIVO MONITORING DATA AND SIMULATED RADIOLOGICAL CONSEQUENCES.

In the early phase of a nuclear reactor accident, in-vivo monitoring of impacted population would be highly useful to detect potential contamination during the passage of the cloud and to estimate the dose from inhalation of measured radionuclides. However, it would be important to take into account other exposure components: (1) inhalation of unmeasured radionuclides and (2) external irradiation from the plume and from the radionuclides deposited on the soil. This article presents a methodology to calculate coefficients used to convert in-vivo measurement results directly into doses, not only from the measured radionuclides but from all sources of exposure according to model-based projected doses.

Is exposure to ionising radiation associated with childhood cardiac arrhythmia in the Russian territories contaminated by the Chernobyl fallout? A cross-sectional population-based study.

Objective: To investigate childhood cardiac arrhythmia and chronic exposure to caesium-137 (Cs) resulting from the Chernobyl accident.

Design: Prospective cross-sectional study using exposed/unexposed design conducted in the Bryansk region from May 2009 to May 2013 on children selected on the basis of Cs soil deposition: control territories ([Cs]<37 kBq per square metre, where children were considered as unexposed) and contaminated territories ([Cs]>555 kBq per square metre, where children were considered as exposed).

Setting: Russian territories affected by the Chernobyl fallout (Bryansk region).

A systematic experimental study of parameters influencing 131-iodine in vivo spectroscopic measurements using age-specific thyroid phantoms.

In case of nuclear accident, the internal exposure monitoring of the population will preferably focus on the detection of I in the thyroid by in vivo monitoring. In most cases, the calibration of in vivo monitoring is performed with an adult thyroid phantom, which raises doubts regarding the relevance of child exposure assessment. In this study, the influence on the calibration of the thyroid volume, the counting distance and the positioning variations are studied experimentally in a systematic way.

THYROID PHANTOM MEASUREMENTS IN JOINT EURADOS-LLNL INTERCOMPARISON EXERCISE.

The European Radiation Dosimetry Group (EURADOS), in collaboration with Lawrence Livermore National Laboratory's (LLNL's) Thyroid Intercomparison Program (TRIP), conducted an intercomparison exercise consistent with the goals of EURADOS. In total, 35 in vivo radiobioassay facilities from 18 countries participated to evaluate the differences between the neck and thyroid phantoms specified in two standards issued by the American National Standards Institute. Radioiodine (125I and 131I) measurement results were compared to the traceable standard activity levels added to each phantom.

Development and test of sets of 3D printed age-specific thyroid phantoms for I measurements.

In the case of a nuclear reactor accident the release contains a high proportion of iodine-131 that can be inhaled or ingested by members of the public. Iodine-131 is naturally retained in the thyroid and increases the thyroid cancer risk. Since the radiation induced thyroid cancer risk is greater for children than for adults, the thyroid dose to children should be assessed as accurately as possible.

Optimization of Routine Monitoring of Workers Exposed to Plutonium Aerosols.

In case of incidental confinement failure, mixed oxide (MOX) fuel preparation may expose workers to plutonium aerosols. Due to its potential toxicity, occupational exposure to plutonium compounds should be kept as low as reasonably achievable. To ensure the absence of significant intake of radionuclides, workers at risk of internal contamination are monitored by periodic bioassay planned in a routine monitoring programme.

Influence of DTPA Treatment on Internal Dose Estimates.

In case of internal contamination with plutonium materials, a treatment with diethylene triamine pentaacetic acid (DTPA) can be administered in order to reduce plutonium body burden and consequently avoid some radiation dose. DTPA intravenous injections or inhalation can start almost immediately after intake, in parallel with urinary and fecal bioassay sampling for dosimetric follow-up. However, urine and feces excretion will be significantly enhanced by the DTPA treatment.

Coronary stenosis risk analysis following Hodgkin lymphoma radiotherapy: A study based on patient specific artery segments dose calculation.

Background And Purpose: The dose effect-effect relationship for cardiac diseases following radiotherapy suffers from uncertainties. Three dimensional coronary artery (CA) dose calculation after mediastinal Hodgkin lymphoma radiotherapy was performed, using the patient's coronary CT angiography (CCTA), and the relationship between the coronary arteries' radiation doses and the risk of stenosis was estimated.

Materials And Methods: Radiotherapy simulation CT scans and CCTAs of patients treated for a mediastinal Hodgkin lymphoma were used to merge thoracic and detailed cardiovascular anatomies.

Evaluation of Functionalized Polysaccharide Microparticles Dosimetry for SPECT Imaging Based on Biodistribution Data of Rats.

Purpose: Technetium-99 m (Tc-99 m)-labelled microparticles, functionalized with fucoidan to present a high affinity for P-Selectin, or [(99m)Tc] MP-fucoidan, were developed as a novel SPECT radiotracer for abdominal aortic aneurysm (AAA). As a prerequisite step forwards a clinical trial, the biodistribution and dosimetry of these [(99m)Tc] MP-fucoidan microparticles were performed in rats in order to estimate the absorbed and effective dose in humans.

Procedures: Microparticles with a maximum hydrodynamic diameter of 4 μm were obtained by crosslinking polysaccharides dextran and pullulan.

Cellular dosimetry calculations for Strontium-90 using Monte Carlo code PENELOPE.

Purpose: To improve risk assessments associated with chronic exposure to Strontium-90 (Sr-90), for both the environment and human health, it is necessary to know the energy distribution in specific cells or tissue. Monte Carlo (MC) simulation codes are extremely useful tools for calculating deposition energy. The present work was focused on the validation of the MC code PENetration and Energy LOss of Positrons and Electrons (PENELOPE) and the assessment of dose distribution to bone marrow cells from punctual Sr-90 source localized within the cortical bone part.

Collective dosimetry to distinguish occupational exposure to natural uranium from alimentary uranium background in bioassay measurements.

Purpose: To assess occupational exposure from uranium bioassay results which are low and impacted by dietary intakes.

Material And Methods: First, the bioassay results of a group of workers exposed to UO2 were compiled along with results of a control group. A Bayesian approach was developed to account for dietary intakes in the calculation of the committed effective dose from occupational exposure of a group of workers.

Dependence of coronary 3-dimensional dose maps on coronary topologies and beam set in breast radiation therapy: a study based on CT angiographies.

Purpose: In left-side breast radiation therapy (RT), doses to the left main (LM) and left anterior descending (LAD) coronary arteries are usually assessed after delineation by prior anatomic knowledge on the treatment planning computed tomography (CT) scan. In this study, dose sensitivity due to interindividual coronary topology variation was assessed, and hot spots were located.

Methods And Materials: Twenty-two detailed heart models, created from heart computed tomography angiographies, were fitted into a single representative female thorax.

Three-dimensional personalized Monte Carlo dosimetry in 90Y resin microspheres therapy of hepatic metastases: nontumoral liver and lungs radiation protection considerations and treatment planning optimization.

Unlabelled: In the last decades, selective internal radiation therapy (SIRT) has become a real alternative in the treatment of unresectable hepatic cancers. In practice, the activity prescription is limited by the irradiation of organs at risk (OAR), such as the lungs and nontumoral liver (NTL). Its clinical implementation is therefore highly dependent on dosimetry.

Potential of hybrid computational phantoms for retrospective heart dosimetry after breast radiation therapy: a feasibility study.

Purpose: Current retrospective cardiovascular dosimetry studies are based on a representative patient or simple mathematic phantoms. Here, a process of patient modeling was developed to personalize the anatomy of the thorax and to include a heart model with coronary arteries.

Methods And Materials: The patient models were hybrid computational phantoms (HCPs) with an inserted detailed heart model.

Comparison of two leg phantoms containing (241)Am in bone.

Three facilities (CIEMAT, HMGU and HML) have used their in vivo counters to compare two leg phantoms. One was commercially produced with (241)Am activity artificially added to the bone inserts. The other, the United States Transuranium and Uranium Registries' (USTUR) leg phantom, was manufactured from (241)Am-contaminated bones resulting from an intake.

National and international interlaboratories comparisons: a tool for the validation of in vitro and in vivo methods.

The metrological evaluation is indispensable to objectively prove the capability of the medical laboratory to perform analysis. The comparison of analytical performances regarding the accuracy and the reproducibility of the available methods is a real interest of international comparison exercises, especially as the participation to comparison exercises is becoming a requirement for accredited laboratories. Interlaboratory tests are a means of assessing the analytical coherence of medical laboratories.

Creation and use of adjustable 3D phantoms: application for the lung monitoring of female workers.

In vivo counting measurements, used for the monitoring of workers with internal contamination risks, are based on the use of calibration physical phantoms. However, such phantoms do not exist for female subjects. Computational calibration using numerical representations, Mesh and non-uniform rational basis spline (NURBS) geometries, was thus considered.

Study of the influence of radionuclide biokinetics on the efficiency of in vivo counting using Monte Carlo simulation.

To improve calibration methods of in vivo counting, our laboratory has developed a computer tool to model internal contamination and assess in vivo activity and corresponding organ absorbed doses. The aim of the recent work was to define a more realistic source based on biokinetic models. The influence of the biokinetic parameters on the in vivo counting was studied through the simulation of an acute inhalation intake of (241)Am.

Application of Monte Carlo calculation and OEDIPE software for virtual calibration of an in vivo counting system.

OEDIPE (a French acronym standing for 'Tool for Personalized Internal Dose Assessment'), developed by IRSN, is used to perform virtual calibration of a real in vivo counting system. The system, installed recently at Le Vésinet, consists of four Broad Energy germanium detectors. CT images of Livermore torso phantom are used to create a voxel phantom after segmentation using Dosigray software.