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The bronchial tolerance to high doses of radiation is not fully understood. However, in the event of a radiological accident with unintended exposure of the central airways to high doses of radiation it would be important to be able to anticipate the clinical consequences given the magnitude of the absorbed dose to different parts of the bronchial tree. Stereotactic body radiation therapy (SBRT) is a radiation treatment technique involving a few large fractions of photon external-beam radiation delivered to a well-defined target in the body. Despite generally favourable results, with high local tumour control and low-toxicity profile, its utility for tumours located close to central thoracic structures has been questioned, considering reports of severe toxic symptoms such as haemoptysis (bleedings from the airways), bronchial necrosis, bronchial stenosis, fistulas and pneumonitis. In conjunction with patient- and tumour-related risk factors, recent studies have analysed the absorbed radiation dose to different thoracic structures of normal tissue to better understand their tolerance to these high doses per fraction. Although the specific mechanisms behind the toxicity are still partly unknown, dose to the proximal bronchial tree has been shown to correlate with high-grade radiation side effects. Still, there is no clear consensus on the tolerance dose of the different bronchial structures. Recent data indicate that a too high dose to a main bronchus may result in more severe clinical side effects as compared to a smaller sized bronchus. This review analyses the current knowledge on the clinical consequences of bronchial exposure to high dose hypofractionated radiation delivered with the SBRT technique, and the tolerance doses of the bronchi. It presents the current literature regarding types of high-grade clinical side effects, data on dose response and comments on other risk factors for high-grade toxic effects.

PURPOSE The dicentric chromosome assay (DCA), the gold standard for radiation biodosimetry, evaluates an individual absorbed radiation dose by the analysis of DNA damage in human lymphocytes. The conventional (C-DCA) and QuickScan (QS-DCA) scoring methods are sensitive for estimating radiation dose. The Biodosimetry Laboratory at Institute of Nuclear Energy Research (INER), Taiwan, participated in intercomparison exercises conducted by Health Canada (HC) in 2014, 2015 and 2018 to validate the laboratory's accuracy and performance. MATERIAL AND METHODS Blood samples for the conventional dose response curve for Taiwan were irradiated with 0, 0.25, 0.5, 1, 2, 3, 4 and 5 Gy. Ten blind blood samples were provided by HC. Either or both of two methods of conventional (C) or QuickScan (QS) scoring could be chosen for the HC's intercomparison. For C-DCA triage scoring, only cells with 46 centromeres were counted and each scorer recorded the number of dicentrics in the first 50 metaphases or stopped scoring when 30 dicentrics were reached. Scorers also recorded how much time it took to analyze 10, 20, and 50 cells. Subsequently, the data were entered into the Dose Estimate software (DoseEstimate_v5.1) and dose estimates were calculated. With QS-DCA scoring, a minimum of 50 metaphase cells (or 30 dicentrics) were scored in apparently complete metaphases without verification of exactly 46 centromeres. RESULTS For the blinded blood samples irradiated at HC and shipped to INER, the mean absolute deviation (MAD) derived after scoring 50 cells for C-DCA and QS-DCA was

Background Currently there is an ever increasing interest in Lu-177 targeted radionuclide therapies, which target neuro-endocrine and prostate tumours. For a patient-specific treatment, an individual dosimetry based on SPECT/CT imaging is necessary. The aim of this study is to introduce a dosimetry method, where dose voxel kernels (DVK) are predicted by a neural network. Methods Kidneys are considered one of the most critical organs in any radionuclide therapy. Hence we chose kidneys of 26 patients, who underwent Lu-177-DOTATOC or PSMA therapy, as target organs for our dosimetric method. First of all, density kernels with a size of 9 × 9 × 9 voxels were considered, and the corresponding DVKs were calculated by Monte Carlo simulations. These kernels were used to train a neural network (NN), which received a density kernel as input and predicted a DVK at the output. To predict the dose distribution of an entire kidney, the organ had to be partitioned into a large number of density kernels. Afterwards the DVKs were predicted by a trained NN, and employed to reconstruct the whole-organ dose distribution by convolution with the activity distribution. This method was compared to the standard method where the activity distribution is convolved with a DVK based on a homogeneous soft tissue kernel. Results The number of training kernels amounted to 52,274 density kernels with corresponding MC-derived DVKs. The results serve as proof of principle of the newly proposed method and showed that the NN approach yielded superior results compared to the standard method with no additional computational effort. Conclusion The NN approach is an accurate and highly competitive dosimetric method to precisely estimate absorbed radiation dose in critical organs like kidneys in clinical routine. To further improve the results, a larger number of DVKs needs to be computed by Monte Carlo simulations. An extension of the method to other organs is easily conceivable.

Numerous processing techniques have been developed to control food spoilage and raise food safety. The traditional methods of preservation include: pasteurization, canning, freezing, refrigeration and use of chemical preservatives. Food irradiation is non-thermal food preservation process. It is a treatment of food exposition on an amount of energy in the form of speed particles or rays. Depending on absorbed radiation dose, various effects can be achieved, resulting in reduced storage losses, extended shelf life, improved microbiological and parasitological safety of foods. The potential application of ionizing radiation in food processing is based mainly on the fact that ionizing radiations damage very effectively the DNA molecules. The application is very diverse, from inhibition of sprouting of tubers and bulbs, to production of commercially sterile food products. At the same time, irradiation-induced chemical changes in food are minimal. Irradiation does not cause any significant loss of macronutrients. Proteins, fats and carbohydrates undergo minimal modifications in nutritional value, which are less significant compared with traditional methods of food preservation. Irradiation offers a potential to enhance microbiological safety and quality of food through extension of its shelf life. The aim of this review paper is to give an overview of the effects of ionizing radiation on microbial contaminants and nutritional characteristics of food. In the paper, the basic concepts of food irradiation, mode of action on microbes and the effects of ionizing radiation on nutritional quality of irradiated food are summarized.

To study the correlation between absorbed perfused liver dose using Y90 radioembolization and degree of hepatocellular carcinoma (HCC) necrosis in liver explants in a multicenter cohort analysis A retrospective analysis of 45 HCC patients treated between 2014 and 2017 is presented. Inclusion criteria were treatment-naive solitary HCC ≤ 8 cm and Child-Pugh A liver status using the radiation segmentectomy approach. All patients underwent liver resection or transplantation (LT). Liver explants were examined per institutional routine protocols to assess histopathological viability of HCC. Tumor pathological necrosis was classified into complete (100% necrosis), extensive (> 50% and ≤ 99%) necrosis, and partial ( 190 Gy achieved CPN, while 11/17 (65%) who had 400 Gy exhibited CPN. Radiation segmentectomy for early HCC with ablative dosing > 400 Gy results in CPN. This represents the new standard target dose for radiation segmentectomy.

The purpose of the present work is to analyze the long-term yearly average volumetric activity in the surface air and the yearly absorbed dose of β- and γ-radiation in the spread zone of continuous emissions from NPP. The particulars of the spreading of the emission radionuclides and the associated yearly absorbed radiation dose are determined. It is shown that the atmospheric volumetric activity of radionuclides due to continuous emissions is 105 times lower than the NRB-99/2009 standards and the yearly absorbed dose is 1000 times lower than the level of the natural radiation background.

Following a large-scale radiological incident, there is a need for FDA-approved biodosimetry devices and biomarkers with the ability to rapidly determine past radiation exposure with sufficient accuracy for early population triage and medical management. Towards this goal, we have developed FAST-DOSE (Fluorescent Automated Screening Tool for Dosimetry), an immunofluorescent, biomarker-based system designed to reconstruct absorbed radiation dose in peripheral blood samples collected from potentially exposed individuals. The objective of this study was to examine the performance of the FAST-DOSE assay system to quantify intracellular protein changes in blood leukocytes for early biodosimetry triage from humanized NOD-scid-gamma (Hu-NSG) mice and non-human primates (NHPs) exposed to ionizing radiation up to 8 days after radiation exposure. In the Hu-NSG mice studies, the FAST-DOSE biomarker panel was able to generate delivered dose estimates at days 1, 2 and 3 post exposure, whereas in the NHP studies, the biomarker panel was able to successfully classify samples by dose categories below or above 2 Gy up to 8 days after total body exposure. These results suggest that the FAST-DOSE bioassay has large potential as a useful diagnostic tool for rapid and reliable screening of potentially exposed individuals to aid early triage decisions within the first week post-exposure.

188Re and 186Re are two applicable rhenium medical radioisotopes with complementary features that make them beneficial for different sizes of tumours. The aim of this study is to investigate 188/186Re-HEDP efficacy as a cocktail by calculating absorbed radiation dose in human organs based on biodistribution data obtained by injecting it to normal rats. Three rats were sacrificed at different time intervals and the percentage of injected dose per gram of each organ was measured by direct counting from rat data. By calculating accumulated activities in each organ and extrapolating rat data to human data by the radiation dose assessment resource method and by using OLINDA/EXM software, the injected dose in various human organs was obtained. The calculated absorbed dose showed that the 188/186Re-HEDP has noticeable properties that can be more helpful in comparison with using each of the rhenium radioisotopes separately.

Accurate quantification of absorbed radiation dose is important for safe and effective delivery of radiation therapy. An important aspect to this is reference dosimetry, which is performed under reference conditions specified by international codes of practice. Such measurements are usually performed in a water phantom. In the Sun Nuclear Corporation (SNC) three‐dimensional (3D) scanner water tank system the detector holder is fixed to a horizontal metallic drive rail (MDR) which is in close proximity to the active volume of the detector. In this project, the dosimetric effects of the MDR on reference dosimetry were investigated for MV photons, MeV electrons, and kV photons by comparing reference dosimetry measurements in the SNC 3D scanner against similar measurements in a Standard Imaging (SI) one‐dimensional (1D) tank and against measurements in the SNC 3D scanner with an additional, custom‐made spacer placed beneath the chamber holder to increase the chamber ‐ MDR separation. A second experiment investigated the difference in chamber reading dependent on chamber to MDR separation by fixing the chamber in the tank independently of the MDR and successively moving the MDR vertically to alter the separation. The results showed that measurements in the SNC 3D scanner agree with both SI 1D tank and SNC 3D scanner with spacer to within ±0.3% for MV photons, ±0.1% for electrons and ±1.2% for kV photons within the calculated setup uncertainty. The second experiment showed that the contribution of backscatter from the MDR was significant if the distance between MDR and chamber was reduced below the chamber's designed position in the SNC 3D scanner. The exception was for kV photons where the contribution of backscatter from the MDR was measured to be 0.5% at the designed distance. Further investigation would be useful for kV photons, where the experiment showed relatively large measurement uncertainties.

To quantify the effects of absorbed radiation dose on healthy liver parenchyma following radioembolisation (RE) using [99mTc]TcMebrofenin to analyse both global and regional liver function. Patients having RE to treat hepatic disease underwent a [99mTc]TcMebrofenin hepatobilliary scintigraphy (HBS) study at both baseline and 8 weeks following treatment. Changes in global liver uptake rate were compared with healthy liver absorbed dose measures derived from the post-treatment 90Y PET/CT, including average dose, minimum dose to 70% of the volume (D70) and volume receiving at least 50 Gy (V50). Changes in functional burden associated with treatment and spared liver volumes in patients receiving lobar RE were also assessed, as were changes experienced by regional volumes corresponding to various dose ranges. Standard liver function pathology tests (LFTs) (bilirubin, albumin, ALP, AST, ALT and GGT) were examined for changes between baseline and post-treatment. Thirty-five patients were included in the study, of which, 9 had lobar treatment. A significant linear correlation was found between both baseline global liver uptake rate (negative) and D70 with change in global liver uptake rate. Patients undergoing lobar treatments demonstrated a shift in functional burden, and a significant difference was seen between the mean dose corresponding to liver volumes that increased their functional burden (9 Gy) and those that decreased their functional burden (35 Gy). No baseline LFTs predicted a decrease in global liver function; however, D70 demonstrated a linear correlation with changes in bilirubin and GGT. Given the significant negative relationship between baseline and change in global liver uptake rate, baseline HBS studies should not be used alone to disqualify patients considered for RE. In terms of treatment planning and evaluation, D70 may be the most appropriate metric of dose, with values greater than 15 Gy indicative of a likely drop in global liver function. The evidence of increasing functional burden in spared liver volumes suggests that patients at risk of complications could benefit from a lobar approach to treatment.

Background The aim of this study was to evaluate radiation exposure to the eye and thyroid in pain physicians during the fluoroscopy-guided cervical epidural block (CEB). Methods Two pain physicians (a fellow and a professor) who regularly performed C-arm fluoroscopy-guided CEBs were included. Seven dosimeters were used to measure radiation exposure, five of which were placed on the physician (forehead, inside and outside of the thyroid protector, and inside and outside of the lead apron) and two were used as controls. Patient age, sex, height, and weight were noted, as were radiation exposure time, absorbed radiation dose, and distance from the X-ray field center to the physician. Results One hundred CEB procedures using C-arm fluoroscopy were performed on comparable patients. Only the distance from the X-ray field center to the physician was significantly different between the two physicians (fellow: 37.5 ± 2.1 cm, professor: 41.2 ± 3.6 cm, P = 0.03). The use of lead-based protection effectively decreased the absorbed radiation dose by up to 35%. Conclusions Although there was no difference in radiation exposure between the professor and the fellow, there was a difference in the distance from the X-ray field during the CEBs. Further, radiation exposure can be minimized if proper protection (thyroid protector, leaded apron, and eyewear) is used, even if the distance between the X-ray beam and the pain physician is small. Damage from frequent, low-dose radiation exposure is not yet fully understood. Therefore, safety measures, including lead-based protection, should always be enforced.

Calculation of radiation dosimetry in targeted nuclear medicine therapies is traditionally resource-intensive, requiring multiple posttherapy SPECT acquisitions. An alternative approach is to take advantage of existing pharmacokinetic data from these smaller cohorts to enable dose computation from a single posttreatment scan in a manner that may be applied to a much broader patient population. Methods: In this work, a technical description of simplified dose estimation is presented and applied to the assessment of 177Lu-prostate-specific membrane antigen (PSMA)-617 therapy for metastatic prostate cancer. By normalizing existing time-activity curves to a single measurement time, it is possible to calculate a mean and range of time-integrated activity values that relate to absorbed radiation dose. To assist with accurate pharmacokinetic modeling of the training cohort, a method for contour-guided image registration was developed. Results: Tissue-specific dose conversion factors for common posttreatment imaging times are reported along with a characterization of added uncertainty in comparison to a traditional serial imaging protocol. Single-time-point dose factors for tumor were determined to be 11.0, 12.1, 13.6, and 15.2 Gy per MBq/mL at image times of 24, 48, 72, and 96 h, respectively. For normal tissues, parotid gland factors were 6.7, 9.4, 13.3, and 19.3 Gy per MBq/mL at those times, and kidneys were 7.1, 10.3, 15.0, and 22.0 Gy per MBq/mL. Tumor dose estimates were most accurate using delayed scanning at times beyond 72 h. Dose to healthy tissues is best characterized by scanning patients in the first 2 d of treatment because of the larger degree of tracer clearance in this early phase. Conclusion: This work demonstrates a means for efficient dose estimation in 177Lu-PSMA-617 therapy. By providing methods to simplify and potentially automate radiation dosimetry, we hope to accelerate the understanding of radiobiology and development of dose-response models in this unique therapeutic context.

The kinetics of the formation of radiation-induced defects in silicon and silicon carbide as a function of the absorbed energy is analyzed. The dependence of the concentration of conduction electrons n-Si and n-SiC on the irradiation dose is studied experimentally under conditions of irradiation with electrons with an energy of 0.9 MeV and protons with an energy of 15 MeV. The advantages and disadvantages of using the integral flux (fluence) and absorbed energy as kinetic parameters are discussed. It is established in the performed studies that the visual representation of the kinetics of radiation-induced defect formation as a function of the fluence of irradiating particles is clearer for tabulating the requirements imposed to equipment stability under suitable conditions. To study the physical processes underlying the formation of radiation-induced defects in semiconductors, it is more convenient to use the dependences of the effects observed under radiation exposure as functions of the absorbed energy.

Background Cesium-137 (137Cs) is one of the major and most clinically relevant radionuclides of concern in a radiological dispersal device, “dirty bomb” scenario as well as in nuclear accidents and detonations. In this exposure scenario, a significant amount of soluble radionuclide(s) may be dispersed into the atmosphere as a component of fallout. The objectives of the present study were to investigate the effect of protracted 137Cs radionuclide exposures on DNA damage in mouse blood and spleen mononuclear cells (MNCs) in vivo using the γ-H2AX biomarker, and to develop a mathematical formalism for these processes. Results C57BL/6 mice were injected with a range of 137CsCl activities (5.74, 6.66, 7.65 and 9.28 MBq) to achieve total-body committed doses of ~ 4 Gy at Days 3, 5, 7, and 14. Close to 50% of 137Cs was excreted by day 5, leading to a slower rate of decay for the remaining time of the study; 137Cs excretion kinetics were independent of activity level within the tested range, and the absorbed radiation dose was determined by injected activity and time after injection. Measurements of γ-H2AX fluorescence in blood and spleen MNCs at each time point were used to develop a new biodosimetric mathematical formalism to estimate injected activity based on γ-H2AX fluorescence and time after injection. The formalism performed reasonably well on blood data at 2–5 days after injection: Pearson and Spearman’s correlation coefficients between actual and predicted activity values were 0.857 (p = 0.00659) and 0.929 (p = 0.00223), respectively. Conclusions Despite the complicated nature of the studied biological system and the time-dependent changes in radiation dose and dose rate due to radionuclide excretion and other processes, we have used the γ-H2AX repair kinetics to develop a mathematical formalism, which can relatively accurately predict injected 137Cs activity 2–5 days after initial exposure. To determine the assay’s usefulness to predict retrospective absorbed dose for medical triage, further studies are required to validate the sensitivity and accuracy of the γ-H2AX response after protracted exposures. Electronic supplementary material The online version of this article (10.1186/s12860-019-0195-2) contains supplementary material, which is available to authorized users.

Dicentric chromosome assay (DCA) is most frequently used for estimating the absorbed radiation dose in the peripheral blood lymphocytes of humans after occupational or incidental radiation exposure. DCA is considered to be the "gold standard" for estimating the absorbed radiation dose because the dicentric chromosome formation is fairly specific to ionizing radiation exposure and its baseline frequency is extremely low in non-exposed humans. However, performance of DCA for biodosimetry is labor intensive and time-consuming making its application impractical for radiological/nuclear mass casualty incidents. Realizing the critical need for rapid dose estimation particularly after radiological/nuclear disaster events, several laboratories have initiated efforts to automate some of the procedural steps involved in DCA. Although metaphase image capture and dicentric chromosome analysis have been automated using commercially available platforms, lack or an insufficient number of these platforms may pose a serious bottleneck when hundreds and thousands of samples need to be analyzed for rapid dose estimation. To circumvent this problem, a web-based approach for telescoring was initiated by our laboratory, which enabled the cytogeneticists around the globe to analyze and score digital images. To further increase the surge capacity of dicentric scorers, we recently initiated a dicentric training and scoring exercise involving a total of 50 volunteers at all academic levels without any prerequisite for experience in radiation cytogenetics. Out of the 50 volunteers enrolled thus far, only one outlier was found who overestimated the absorbed radiation dose. Our approach of training the civilians in dicentric chromosome analysis holds great promise for increasing the surge capacity of dicentric chromosome scorers for a rapid biodosimetry in the case of mass casualty scenarios.

For some time, dual energy computed tomography (DECT) has been an established method used in a vast array of clinical applications, including lung nodule assessment. The aim of this study was to analyze (using monochromatic DECT images) how the X-ray absorption of solitary pulmonary nodules (SPNs) depends on the iodine contrast agent and when X-ray absorption is no longer dependent on the accumulated contrast agent. Sixty-six patients with diagnosed solid lung tumors underwent DECT scans in the late arterial phase (AP) and venous phase (VP) between January 2017 and June 2018. Statistically significant correlations (p ≤ 0.001) of the iodine contrast concentration were found in the energy range of 40–90 keV in the AP phase and in the range of 40–80 keV in the VP phase. The strongest correlation was found between the concentrations of the contrast agent and the scanning energy of 40 keV. At the higher scanning energy, no significant correlations were found. We concluded that it is most useful to evaluate lung lesions in DECT virtual monochromatic images (VMIs) in the energy range of 40–80 keV. We recommend assessing SPNs in only one phase of contrast enhancement to reduce the absorbed radiation dose.

177Lu-DOTAGA-(l-y)fk(Sub-KuE) a.k.a. 177Lu-PSMA I&T is currently used for radioligand therapy (RLT) of metastatic castration-resistant prostate cancer (mCRPC) in several centers in Europe. Background: Dosimetry is mandatory according to EU guidelines, although routine methods for dosimetry, i.e., absorbed radiation dose calculations for radiopharmaceuticals, are missing. Methods: We created a model of dosimetric analysis utilizing voxel-based dosimetry and intra-lesion radiomics to assess their practicality in routine dosimetry. Results: As an example for the model, our patient with mCRPC had excellent therapy response; quantitatively more than 97% of the metastatic tumor burden in local and distant lymph nodes and skeleton was destroyed by four cycles of RLT. The absorbed radiation doses in metastases decreased towards later cycles of RLT. Besides the change of prostate-specific membrane antigen (PSMA) concentration and absorbed doses in the tumor, further response to RLT could be predicted from biomarker changes, such as LDH and PSA. Conclusions: Individual dosimetry is needed to understand large variations in tumor doses and mixed responses; for that purpose, routine tools should be developed. The Dosimetry Research Tool (DRT) fluently performed automated organ delineation and absorbed radiation dose calculations in normal organs, and the results in our patient were in good concordance with the published studies on 177Lu-PSMA dosimetry. At the same time, we experienced considerable challenges in voxel-based dosimetry of tumor lesions. Measurements of 177Lu-PSMA activity concentrations instead of absorbed radiation dose calculations could make routine dosimetry more flexible. The first cycle of RLT seems to have quantitatively the biggest impact on the therapy effect. Radiomics analyses could probably aid in the treatment optimization, but it should be tested in large patient populations.

An experimental platform was designed to study the effects of laser accelerated protons (LAPs) on mammalian cells. The protons, in the MeV energy range, originate from the rear side of a thin 5 µm Ti foil target following the interaction with a high power laser pulse and are accelerated by the target normal sheath mechanism. A tape Ti foil target was developed, allowing a shot repetition rate of up to 5 Hz, which corresponds to the rate of the laser system. A dipole magnet arrangement was used for energy dispersion and to separate the proton burst from electrons and x rays. The absorbed radiation dose at the cell port was measured with CR39 plastic detectors and calibrated imaging plates. An epifluorescence microscope with compact open-beam optics was developed to image live cells and their spatiotemporal properties during and after irradiation. To demonstrate the functionality of all components of the platform, biological proof of concept experiments were carried out using two suspension (Jurkat and Ramos) and two adherent (HeLa and A-549) cell lines. A multitude of biological procedures and analytical techniques were established on-site or in laboratories nearby. For example, we analyzed DNA double-strand break (DSB) induction and repair by detecting the γH2A.X signal by fluorescence microscopy and flow cytometry. The observed dose-dependent increase in DSB induction confirms that DNA damage is induced in cells after exposure to LAPs. CA extern

Molecular radiotherapy, or targeted radionuclide therapy, uses systemically administered drugs bearing a suitable radioactive isotope, typically a beta emitter. These are delivered via metabolic or other physiological pathways to cancer cells in greater concentrations than to normal tissues. The absorbed radiation dose in tumour deposits causes chromosomal damage and cell death. A partner radiopharmaceutical, most commonly the same vector labelled with a different radioactive atom, with emissions suitable for gamma camera or positron emission tomography imaging, is used to select patients for treatment and to assess response. The use of these pairs of radio-labelled drugs, one optimised for therapy, the other for diagnostic purposes, is referred to as theragnostics. Theragnostics is increasingly moving away from a fixed number of defined activity administrations, to a much more individualised or personalised approach, with the aim of improving treatment outcomes, and minimising toxicity. There is, however, still significant scope for further progress in that direction. The main tools for personalisation are the following: imaging biomarkers for better patient selection; predictive and post-therapy dosimetry to maximise the radiation dose to the tumour while keeping organs at risk within tolerance limits; imaging for assessment of treatment response; individualised decision making and communication about radiation protection, adjustments for toxicity, inpatient and outpatient care.

This is the first study undertaken towards development of mixed-matrix membranes (MMMs) with enhanced radiation resistant attributes by reinforcement of nanostructured Gd2Zr2O7 (GZO) within polysulfone (Psf) host-matrix. The study describes synthesis and characterization of GZO in disordered, defect-fluorite structure, having average crystallite size of 31(±3) nm. Membranes prepared with different loading of GZO (up to 2 w/w% of Psf) are exposed to γ-radiation up to a dose of 1000 kGy in aqueous environment. The effect of radiation on the structural, mechanical, and thermo-oxidative properties of MMMs has been compared with that of radiation-sensitive Psf membrane. The ultrafiltration performance of the (un)irradiated Psf and MMMs reveal that an optimum reinforcement of GZO at 1 (w/wPsf)% offers ~10 times radiation resistant MMM, compared to that of Psf membrane. The MMM with 1 (w/wPsf)% GZO was rolled into 2512 spiral configuration and a highly-compact device was developed for treatment of radioactive effluent. Based on the flux decline behaviour over 18 months duration, the fouling behaviour of the MMM module was modelled. The life-span of the MMM was predicted based on the absorbed radiation dose, GZO leaching study, and fouling behaviour. It is proposed that GZO mitigates a fraction of the impinged γ-energy in swapping of the Gd3+ and Zr4+ sites, which protects the polymeric host-matrix in-situ from radiation induced degradation. The abundance of Gd3+ and Zr4+ associated with polar O2− over the impregnated GZO further stabilizes MMMs through scavenging of the oxidizing and reducing radiolysed products of water. Thus, we report a smart approach to develop novel MMM with greater life-expectancy against high-energy radiation and further fabricate a membrane-based device for management of liquid radioactive waste.

In this study, Gas chromatographic/mass spectrometric study indicated that carbazole (CARB) is formed in oxygen free ɤ- irradiation of aniline / chlorobenzene mixtures. It seems that ɤ-radiation induces the formation of CARB in these mixtures via intramolecular dehydrocyclization of diphenylamine (DPA). The yield of CARB estimated via gas chromatography (GC), was found to be dependent on aniline – chlorobenzene molar ratio. Where, the maximum CARB yield was found at 1:1 molar ratio of aniline – chlorobenzene. At this reactants molar ratio, the effect of absorbed radiation dose and dose rate on the yield of carbazole was studied. The yield of CARB increases, linearly, as the absorbed dose is increased up to about 50 kGy. The G-value (5.8μM/J) of CARB was determined. It was found that, the yield of CARB increase as the absorbed dose rate increases (0.226 -0.904kGy/h). So, it can be concluded that CARB is formed, mainly, in the spurs. The mechanism of the CARB formation was discussed.

During interventional cardiological procedures, operators are exposed to patients’ scatter radiation. Therefore, we measured the radiation exposure of the operator’s eyeball, thyroid, and chest wall during angiography. We used the optically stimulated luminescence dosimeter in the anthropomorphic phantom and developed Monte Carlo simulations using the Korean human voxel phantom. At 15 frames/s, the radiation dose of the operator’s right eyeball (RE), left eyeball (LE), thyroid (T), and chest wall (CW) at the femoral artery puncture position (FAPP) with protective equipment (PE) was 0.015, 0.16, 0.012, and 0.014 mGy, respectively. At 7.5 frames/sec, the radiation dose of the operator’s RE, LE, T, and CW at FAPP with PE was 33.33%, 18.75%, 52.94%, and 45.00% lower than that of those at the radial artery puncture position (RAPP), respectively. At 15 frames/s, the radiation dose of the operator’s RE, LE, T, and CW at RAPP without PE was 1.76 times, 2.23 times, 2.76 times, and 2.05 times higher than that of those with PE. Per the simulation results, the absorbed radiation dose of the eye ball, thyroid gland, and myocardium of the heart at FAPP with and without PE under 15 frame/s was 9.68%, 13.04%, 8.33% and 9.98%, 6.00%, 8.82% lower than at RAPP under similar conditions. Effective measures for occupational radiological protection are lower frame rate exposure, increased distance from the X-ray source, and PE use. Radiologist protection in interventional cardiology cannot be handled independently of patient protection, owing to several correlations; thus, reducing the patient dose will reduce the operator dose.

Introduction Intracranial aneurysm coil embolisation is a fluoroscopically guided procedure associated with high radiation dose. The increase in the number of coil embolisation procedures raises concern for the amount of radiation and the associated radiation risks to the patients. This research study was conducted to determine the average radiation dose to patients’ thyroid glands and local skin during intracranial aneurysm coil embolisation and to establish preliminary local diagnostic reference levels for this procedure. In this paper, local skin dose refers to the absorbed radiation dose on the areas of the skin exposed to radiation during intracranial aneurysm coil embolisation, namely neck, face and scalp. Methods This study employed air-kerma area product meters to determine the local skin dose and diagnostic reference levels during intracranial aneurysm coil embolisation. In addition, thyroid radiation doses were measured using thermo-luminescent dosimeters on a phantom during simulation of embolisation procedures. Results The local skin doses as determined by air-kerma area product ranged between 33 and 125 Gy.cm2. The mean thyroid dose was 9.87 mGy. The established local diagnostic reference level was 52.1 Gy cm2, 17.8 min’ fluoroscopy time and 503 image frames. Conclusion The average air-kerma area product values and the proposed diagnostic reference levels were lower than most published values for intracranial aneurysm coil embolisation. Implications for practice The established local diagnostic reference levels are recommended for use as radiation dose optimisation tool at the research site. The findings of this study cannot be generalised or applied to other hospitals. The complexity of the embolisation procedures was not classified for this study. Further research on diagnostic reference levels for intracranial aneurysm coil embolisation, taking into account the complexity of the procedures, is recommended.

The purpose of this study was to establish the dose-response relationship of selective internal radiation therapy (SIRT) in patients with metastatic colorectal cancer (mCRC), when informed by radiobiological sensitivity parameters derived from mCRC cell lines exposed to yttrium-90 (90Y). Methods: 23 mCRC patients with liver metastases refractory to chemotherapy were included. 90Y bremsstrahlung SPECT images were transformed into dose maps assuming the local dose deposition method. Baseline and follow-up CT scans were segmented to derive liver and tumor volumes. Mean, median, and D70 (minimum dose to 70% of tumor volume) values determined from dose maps were correlated with change in tumor volume and vRECIST response using linear and logistic regression, respectively. Radiosensitivity parameters determined by clonogenic assays of mCRC cell lines HT-29 and DLD-1 after exposure to 90Y or external beam radiotherapy (EBRT; 6MV photons) were used in biological effective dose (BED) calculations. Results: Mean administered radioactivity was 1469±428 MBq (847-2185 MBq), achieving a mean radiation absorbed tumor dose of 35.5±9.4 Gy and mean normal liver dose of 26.4±6.8 Gy. A 1.0 Gy increase in mean, median, and D70 absorbed dose was associated with reduction in tumor volume of 1.8%, 1.8%, and 1.5%, respectively, and increased probability of vRECIST response (odds ratio: 1.09, 1.09, and 1.10 respectively). Threshold mean, median and D70 doses for response were 48.3, 48.8, and 41.8 Gy respectively. EBRT-equivalent BEDs for 90Y are up to 50% smaller than those calculated by applying protraction-corrected radiobiological parameters derived from EBRT alone. Conclusion: Dosimetric studies have assumed equivalence between 90Y SIRT and EBRT, leading to inflation of BED for SIRT and possible under-treatment. Radiobiological parameters for 90Y were applied to a BED model, providing a calculation method that has the potential to improve assessment of tumor control.

A Wedge is well known as one of medical equipment to homogenize the dose distribution received by the target during treatment process. This project aims to analyze the effect of wedge angle dependence on absorb irradiation dose received by the Planning Target Volume (PTV) utilizing Dose Volume Histogram (DVH) result. The variations of wedge angle are 15°, 30°, 45° and 60°. This study involved 3 data on breast cancer patients with prescribe dose 25x2 Gy. The radiation dose of PTV was evaluated at D5% and D95%. The average D5% of PTV at a wedge angle of 15° was (53.80±0.02) Gy, wedge 30° was (57.01±0.02) Gy, wedge 45° was (60.54±0.02) Gy, and wedge 60° for (63.88±0.02) Gy. The D95% of PTV at a wedge angle of 15° was (35.00±0.02) Gy, wedge 30° was (36.15±0.02) Gy, wedge 45° was (37.54±0.02) Gy, and wedge 60° for (41.49±0.02) Gy. The average comparison value of Homogeneity Index (HI) with wedge variation is (1.53±0.05) for wedge 15°, for wedge 30° for (1.57±0.05), for wedge 45° for (1.61±0.06), and for a 60° wedge (1.54±0.01). Statistical test results showed that the HI values on wedges 15°, 30°, 45°, and 60° were not significantly different (P = 0.34). However, the HI value which was close to ideal was equal to 1 and could give a homogeneous and optimal dose distribution to PTV. Therefore, wedge angle 15° could give a more homogeneous and optimal dose distribution.

Dicentric chromosome assay (DCA) is routinely used for estimating the absorbed radiation dose in exposed humans. Optimal lymphocyte viability is crucial for reliable dose estimation and most cytogenetic laboratories prefer the receipt of blood samples within 24 to 36 hours after collection. Delays in the shipment/receipt of samples can occur sometimes under certain unforeseen circumstances: (1) Adverse weather conditions, (2) distant location of blood collection sites, and (3) shipping and handling of a large number of samples after radiological/nuclear mass casualty incident(s). To circumvent some of these limitations, we evaluated the suitability of ex vivo irradiated blood samples stored in the presence of phytohemagglutinin (PHA) for 7 days at ambient temperature (22-24°C) for radiation biodosimetry. Blood samples stored in the presence of PHA for up to 7 days showed a higher mitotic index than blood samples stored without PHA. To verify the use of stored blood samples for DCA, frequencies of X-rays induced dicentric chromosomes were analyzed in the blood samples that were cultured either 24 hours after exposure or 7 days later after storage. Our results indicate that storage of ex vivo irradiated blood samples in the presence of PHA at ambient temperature was found optimal for DCA and that the radiation doses estimated by dicentric chromosome frequencies were grossly similar between the fresh and stored blood samples. Our study suggests that reliable and accurate biodosimetry results can be obtained for triage using blood samples stored for up to a week at ambient temperature in the presence of PHA.

We conducted the present phase I/IIa positron emission tomography (PET) imaging study with 89Zr conjugated with desferroxamine-IAB2M (89Zr-Df-IAB2M), an anti-prostate-specific membrane-antigen minibody, to assess its safety and feasibility in patients with urological cancer. 89Zr-Df-IAB2M was synthetized by IBA Molecular (Somerset, NJ, USA) and transported by air to Tsukuba Molecular Imaging Center (Tsukuba, Ibaraki, Japan).17 patients received 74 MBq (2 mCi) of 89Zr-Df-IAB2M at total mass doses of 10 mg. Whole-body and plasma clearance, normal-organ and lesion uptake, and radiation absorbed dose were estimated. We also preliminarily tested the performance of 89Zr-immuno-PET imaging for 13 patients with prostate cancer and 4 patients with other urological cancer. The administration of 89Zr-Df-IAB2M was well-tolerated, and no infusion-related reactions were observed in any patient. No adverse events were noted in the laboratory parameters, vital signs, or other parameters. The plasma clearance was biphasic, with an initial rapid phase (t 1/2 fast: 10.1 ± 3.4 h) followed by a slow phase (t 1/2 slow: 49.0 ± 22.7 h). The half-life of radioactivity in the whole body (WB t1/2) was 237 ± 9 h. The highest absorbed radiation dose was 1.67 mGy/MBq, observed in the liver and kidney. The effective dose was 0.68 ± 0.08 mSv/MBq. The radiation dose rate at 0.5 m distance from the patient was 8.67 µSv/h on day 1, and decreased to 2.26 µSv/h at 5 days after injection. Both bone and lymph node metastases were detected with 89Zr-Df-IAB2M by 24 or 48 h imaging. Administration of 89Zr-Df-IAB2M was well-tolerated and safe in terms of adverse events and radiation exposure and protection. 89Zr-Df-IAB2M is feasible for usage by long-distance transportation. Further studies are warranted for analysis of its use for tumor lesion detection (UMIN000015356).

In preclinical studies, 5-fluoro-2′-deoxycytidine (FdCyd), an inhibitor of DNA methyltransferase and DNA hypermethylation, has shown treatment efficacy against multiple malignancies by suppressing epigenetic hypermethylation in tumor cells. Several ongoing clinical trials are using FdCyd, and although some patients may respond to this drug, in most patients it is ineffective. Thus, establishing a noninvasive imaging modality to evaluate the distribution of the drug may provide insight into the variable responses. A novel experimental radiopharmaceutical, 18F-labeled FdCyd, was developed as a companion imaging agent to the nonradioactive form of the drug, FdCyd. We present the first-in-humans radiation dosimetry results and biodistribution of 18F-FdCyd, administered along with tetrahydrouridine, an inhibitor of cytidine/deoxycytidine deaminase, in patients with a variety of solid tumors undergoing FdCyd therapy. Methods: This phase 0 imaging trial examined the 18F-FdCyd biodistribution and radiation dosimetry in 5 human subjects enrolled in companion therapy trials. In each subject, 4 sequential PET scans were acquired to estimate whole-body and individual organ effective dose, using OLINDA/EXM, version 1.0. Tumor-to-background ratios were also calculated for the tumor sites visualized on PET/CT imaging. Results: The average whole-body effective dose for the experimental radiopharmaceutical 18F-FdCyd administered in conjunction with tetrahydrouridine was 2.12E−02 ± 4.15E−03 mSv/MBq. This is similar to the radiation dose estimates for 18F-FDG PET. The critical organ, with the highest absorbed radiation dose, was the urinary bladder wall at 7.96E−02 mSv/MBq. Other organ doses of note were the liver (6.02E−02mSv/MBq), kidneys (5.26E−02 mSv/MBq), and gallbladder (4.05E−02 mSv/MBq). Tumor target-to-background ratios ranged from 2.4 to 1.4, which potentially enable tumor visualization in static PET images. Conclusion: This phase 0 imaging clinical trial provides evidence that 18F-FdCyd administered in conjunction with tetrahydrouridine yields acceptable individual organ and whole-body effective doses, as well as modest tumor-to-background ratios that potentially enable tumor visualization. Dose estimates for 18F-FdCyd are comparable to those for other PET radiopharmaceuticals, such as 18F-FDG. Further studies with larger study populations are warranted to assess 18F-FdCyd imaging as a predictor of FdCyd treatment effectiveness.

The radiation resistance of a composite material filled with finely dispersed tungsten powder with a particle size of 200–500 nm is investigated. A new composite is intended to provide the radiation protection for electronic radio equipment. The sample with the material under study is irradiated by continuous-spectrum X-ray radiation to the absorbed dose of 3 MGy. The variation in the sample microhardness before and after X-ray irradiation serves as the radiation-resistance characteristic. The microstructure of the transverse sample cleavage after irradiation is investigated by scanning electron microscopy and the absence of visible structural defects is established. This result can be explained by uniform energy scattering from local stresses due to a high degree of composite filling with the tungsten powder possessing a high heat-conductivity coefficient. A 10% increase in microhardness of the irradiated sample is revealed during the investigation, which can be explained by the radiation strengthening effect, when the simultaneous rise in microhardness occurs with an increase in strength. It is established experimentally that this effect manifests itself with an increase in the absorbed radiation dose.

Accurate measurement of the absorbed dose and the effective dose is required in dental panoramic radiography involving relatively low energy with a rotational X-ray tube system using long exposures. To determine the effectiveness of measuring the irradiation by using passive dosimetry, we compared the entrance skin doses by using a radiophotoluminescent glass dosimeter (RPL) and an optically stimulated luminescence detector (OSL) in a phantom model consisting of nine and 31 transverse sections. The parameters of the panoramic device were set to 80 kV, 4 mA, and 12 s in the standard program mode. The X-ray spectrum was applied in the same manner as the panoramic dose by using the SpekCalc Software. The results indicated a mass attenuation coefficient of 0.008226 cm2/g, and an effective energy of 34 keV. The equivalent dose between the RPL and the OSL was calculated based on a product of the absorbed doses. The density of the aluminum attenuators was 2.699 g/cm3. During the panoramic examination, tissue absorption doses with regard to the RPL were a surface dose of 75.33 μGy and a depth dose of 71.77 μGy, those with regard to the OSL were surface dose of 9.2 μGy a depth dose of 70.39 μGy and a mean dose of 74.79 μGy. The effective dose based on the International Commission on Radiological Protection Publication 103 tissue weighting factor for the RPL were 0.742 μSv, 8.9 μSv, 2.96 μSv and those for the OSL were 0.754 μSv, 9.05 μSv, and 3.018 μSv in the parotid and sublingual glands, orbit, and thyroid gland, respectively. The RPL was more effective than the OSL for measuring the absorbed radiation dose in low-energy systems with a rotational X-ray tube.

Background [18F]Fluortriopride (FTP) was developed as a dopamine D3-selective radiotracer, thought to be important to neurobiological reward pathways and implicated in drug addiction, Parkinson’s disease, and schizophrenia. Preclinical radiation dosimetry studies found the gallbladder wall received the highest dose. A gallbladder dose reduction intervention was simulated using a novel reduction model for healthy adults following fatty-meal consumption. The goals of this study were to assess whole body FTP human dosimetry and determine the feasibility of reducing absorbed dose to the gallbladder wall. Results Effective dose without a fatty meal was 0.022 ± 0.002 mSv/MBq (± standard deviation) with highest organ dose of 0.436 ± 0.178 mSv/MBq to the gallbladder wall (n = 10). Predicted gallbladder dose reduction with fatty meal consumed was 67.4% (n = 10). Meal consumption by four repeat volunteers decreased average gallbladder dose by 71.3% (n = 4) compared to the original ten volunteers. Conclusions Observed effective doses were adequately low to continue studying FTP uptake in humans. Validated dosimetry simulations indicate up to a 71% reduction in gallbladder dose can be achieved by employing intrinsic physiology to contract the gallbladder via fatty meal ingestion. This methodology for predicting gallbladder absorbed dose reduction from fatty meal consumption can be applied to other radiopharmaceuticals and radiotherapies.

The performance characteristics of γ-rays dose measurements with EPR spectrometer and urotropine rods were analyzed, it were formulated as rods. The rods have significant signal that develops upon irradiation and the intensity of the signal increases with increasing absorbed radiation dose. It was observed that this material has a single EPR line. The detectable dose range was found to be 0 - 50 kGy. The dose response curves are linear up to 30 kGy. The influence of humidity, pre and post-irradiation storage under different conditions were investigated and determined.

BACKGROUND Para-18F-fluorohippuric acid (18F-PFH) and ortho-124I-iodohippuric acid (124IOIH) were recently identified as potential radiotracers suitable for conducting renography using positron emission tomography (PET). The aim of this work was to estimate preliminary human-equivalent internal radiation dose of 18F-PFH and 124I-OIH using the biodistribution data reported in healthy rats. The results were compared with the absorbed dose data of technetium-99m-mercaptoacetyltriglycine (99mTc- MAG3) as documented in the International Commission on Radiological Protection (ICRP) publication 80. METHODS The medical internal radiation dose (MIRD) formula was applied to extrapolate data from rats to human and to project the absorbed radiation dose for various organs in humans. S factor was calculated by Monte-Carlo N-particle (MCNP) simulation. RESULTS Our dose prediction shows that an injection of 18F-PFH or 124I-OIH in humans would result in an estimated effective absorbed dose of 0.09 or 0.17 µSv/MBq respectively for whole body, which is about 135 or 73 times respectively lower than that obtained with an injection of 99mTc-MAG3. All organs except kidneys would receive an estimated effective absorbed dose of

Unsuitable storage conditions or accidents such as floods can present a serious threat for large quantities of book making them prone to attack by harmful microorganisms. The microbiological degradation of archives and book collections can be efficiently inhibited with irradiation processing. Application of EB irradiation to book and archive collections can also be a very effective alternative to the commonly used ethylene oxide treatment, which is toxic to the human and natural environment. In this study was evaluated the influence of EB irradiation used for microbiological decontamination process on paper-based objects. Three different kinds of paper (Whatman CHR 1, office paper and newsprint paper) were treated with 0.4, 1, 2, 5, 10 and 25 kGy electron beam irradiation. Optical and mechanical properties of different sorts of paper treated with e-beam, before and after the radiation process were studied. These results, which correlated with absorbed radiation doses effective for the elimination of Aspergillus niger (A. niger) allowed to determine that EB irradiation with absorbed radiation dose of 5 kGy ensures safe decontamination of different sorts of paper-based objects.

Paper description: There is no literature data on the influence of diagnostic doses of x-radiation during computed tomography (CT) on the oxidative status in testicles. Our results showed that CT provoked a response at the level of antioxidant enzymes in rabbit testicles which was time- and dose-dependent, with a dose threshold of about 29.2 mGy, and predominantly under the influence of the applied current. Our results present novel information about the influence of CT on the cellular antioxidant process. Abstract: In recent years, computed tomography (CT) has become very common in veterinary medicine. It is well known that testicles are organs with high radiosensitivity and their function can be impaired even after exposure to low radiation doses. In this work, we calculated the absorbed radiation doses after CT was performed with different voltage/current levels and correlated it with the activity of antioxidant enzymes in rabbit testicles. Two hours after CT, the activities of catalase (CAT) and glutathione peroxidase (GSH-Px) were increased in the testicles of animals that received an absorbed dose of 29.2 mGy. The same changes, along with elevated glutathione reductase (GR) activity, were observed after 7 days in animals that received the highest absorbed dose (46.3 mGy). It would appear that absorbed doses above 27.8 mGy provoked the antioxidant reaction but the time scale of the reaction was dose-dependent. Examination of the obtained results revealed that the main denominator of CT influence was a higher current. Our results suggest that CT influences the antioxidant status in rabbit testicles. The changes in antioxidant enzyme activities were dose- and time-dependent and influenced by the applied current. https://doi.org/10.2298/ABS180413029M Received: April 13, 2018; Revised: May 23, 2018; Accepted: June 12, 2018; Published online: June 15, 2018 How to cite this article: Mitrovic MB, Tatalovic NR, Nikolic-Kokic AL, Ciraj-Bjelac OF, Krstic NE, Orescanin-Dusic ZS, Krstic DŽ, Jovanovic ZM, Blagojevic DP, Lazarevic-Macanovic MV. Influence of absorbed radiation dose following computed tomography on the antioxidative status in rabbit testicles. Arch Biol Sci. 2018;70(4):675-80.

Un-irradiated carob powder exhibited a weak ESR singlet at g = 2.0041 ± 0.0006 with peak-to-peak linewidth (ΔH pp ) of 0.33 ± 0.01 mT. Irradiated carob powder exhibited an ESR spectrum consisting many resonance lines and similar to ESR spectrum of sugar in all aspects. A linear function of the absorbed radiation dose was found to describe best the dose-response curves of the ESR signal intensity I pp . It is concluded that due to the similarity of carob powder ESR spectrum to the irradiated sugar and the fact that it is widely consumed, carob powder has the potential to be used as a retrospective and/or accidental dosimetric material.

Silicates extracted from tobacco dust in cigarettes were investigated for their suitability as an emergency dosimeter in accidental situation using thermoluminescence technique. A typical glow curve (at a heating rate of 2 °C s −1 ) of irradiated dust silicates in the transmission window between 300 and 500 nm has two prominent peaks at about 83 °C and 137 °C and a weak one at about 181 °C which were all distinguishable from the natural thermoluminescence. The TL spectrum of highly irradiated dust samples showed the existence of three dominant emissions at 1.66 eV (745 nm), 2.2 eV (560 nm) and 2.81 eV (440 nm), which are similar to those reported for feldspar. Repeated irradiation and TL measurement did not affect the sensitivity of the 137 °C peak, if the glow curve is terminated at 300 °C. A linear dose response of the TL signal was observed for doses between 0.1 and 10 Gy. A preheat temperature of 110 °C was found to be optimal for the emptying of the low temperature peak which is not stable. The TL signal is not stable but fades with time since irradiation. Furthermore it can be bleached by daylight but the dust seemed to be sufficiently light shielded in intact cigarettes. Based on the experimental dosimetric properties, a measurement protocol for the detection of absorbed radiation dose was developed. The result of a dose recovery test showed a reasonable agreement between fading corrected dose and given dose.

Various approaches have been undertaken to enhance the delivery of therapeutic agents, including tissue-killing radionuclides, into solid tumors. Here, we describe the preparation of conical needles composed of Ti and Mo coated by pulsed laser deposition or chemical vapor deposition with elements (Ho and Re) that can readily yield radioactive isotopes following irradiation in a neutron flux. The radioactive needles, whose design were based on solid microneedle arrays used in transdermal drug delivery, can be produced with minimal handling of radioactivity and subsequently inserted into tumors as a means of internal radiation therapy. Ho and Re were specifically chosen because of their large neutron capture cross-sections as well as the desirable radiotherapeutic properties of the resultant radionuclides. Neutron-absorbing shields were also developed to prevent the production of unwanted radionuclides after neutron irradiation of the needle base materials. Neutron activation calculations showed that therapeutically significant amounts of radionuclides can be produced for treating solid tumors. Stability studies demonstrated that Re did not leach off the Mo needles. These coated neutron-activatable needles offer a new approach to internal radiation therapy of tumors that allows precise tailoring of the absorbed radiation dose delivered to the tumor by controlling the coating thickness and the irradiation time. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 3273-3280, 2017.