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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

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.

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.

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.

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.

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.

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.

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.

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.

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.

Background: Hysterosalpingography (HSG) is an indispensable tool for diagnosing infertility in females. The procedure exposes female reproductive organs to ionizing radiation as the genitals are irradiated during the process. Investigating patient absorbed dose during the procedures is essential for effective radiological protection of the patient. Objective: This study aims to investigate the radiation dose received by patient during HSG examination in the study environment in order to enhance optimization of procedures and the associated dose, thereby minimizing radiation risks. Material and Methods: The prospective pilot study, was conducted in four tertiary healthcare institutions in Southwest Nigeria. Thermoluminescence dosimeter (TLD 100) was used to determine the Entrance Surface Dose (ESD) of 80 patients presented for HSG investigation. The corresponding effective dose, ovary, uterus and urinary bladder doses were evaluated using PCXMC software. Results: The mean entrance surface doses (ESD) obtained from the four centers were 18.58±6.31 mGy, 15.18±2.27 mGy, 17.44±3.43 mGy and 34.24±11.98 mGy for SW1, SW2, SW3 and SW4 centers, respectively. The corresponding mean of effective doses were 1.54±0.63 mSv, 1.24±0.28 mSv, 1.41±0.30 mSv and 2.53±0.94 mSv for SW1, SW2, SW3 and SW4 centers, respectively. The resulting mean doses to the ovary, urinary bladder and uterus were also presented. Conclusion: The results obtained in general are comparable with international standards. It was, however, recommended that study centers with high doses should conduct dose audit in order to enhance patient safety.

Metal implants not only deteriorate image quality, but also increase radiation exposure. The purpose of this study was to evaluate the effect of metal hip prosthesis on absorbed radiation dose and assess the efficacy of organ dose modulation (ODM) and metal artifact reduction (MAR) protocols on dose reduction. An anthropomorphic phantom was scanned with and without bilateral metal hip prostheses, and surface and deep level radiation doses were measured at the abdomen and pelvis. Finally, the absorbed radiation doses at pelvic and abdominal cavities in the reference, ODM, and two MAR scans (Gemstone spectral imaging, GE) were compared. The Mann Whitney-U test and Kruskal-Wallis test were performed to compare the volume CT dose index (CTDIvol) and mean absorbed radiation doses. Unilateral and bilateral metal hip prostheses increased CTDIVOL by 14.4% and 30.5%, respectively. MAR protocols decreased absorbed radiation doses in the pelvis. MAR showed the most significant dose reduction in the deep pelvic cavity followed by ODM. However, MAR protocols increased absorbed radiation doses in the upper abdomen. ODM significantly reduced absorbed radiation in the pelvis and abdomen. In conclusion, metal hip implants increased radiation doses in abdominopelvic CT scans. MAR and ODM techniques reduced absorbed radiation dose in abdominopelvic CT scans with metal hip prostheses.

Computed Tomography Perfusion (CTP) imaging is a cost-effective and fast approach to provide diagnostic images for acute stroke treatment. Its cine scanning mode allows the visualization of anatomic brain structures and blood flow; however, it requires contrast agent injection and continuous CT scanning over an extended time. In fact, the accumulative radiation dose to patients will increase health risks such as skin irritation, hair loss, cataract formation, and even cancer. Solutions for reducing radiation exposure include reducing the tube current and/or shortening the X-ray radiation exposure time. However, images scanned at lower tube currents are usually accompanied by higher levels of noise and artifacts. On the other hand, shorter X-ray radiation exposure time with longer scanning intervals will lead to image information that is insufficient to capture the blood flow dynamics between frames. Thus, it is critical for us to seek a solution that can preserve the image quality when the tube current and the temporal frequency are both low. We propose STIR-Net in this paper, an end-to-end spatial-temporal convolutional neural network structure, which exploits multi-directional automatic feature extraction and image reconstruction schema to recover high-quality CT slices effectively. With the inputs of low-dose and low-resolution patches at different cross-sections of the spatio-temporal data, STIR-Net blends the features from both spatial and temporal domains to reconstruct high-quality CT volumes. In this study, we finalize extensive experiments to appraise the image restoration performance at different levels of tube current and spatial and temporal resolution scales.The results demonstrate the capability of our STIR-Net to restore high-quality scans at as low as 11% of absorbed radiation dose of the current imaging protocol, yielding an average of 10% improvement for perfusion maps compared to the patch-based log likelihood method.

Introduction: In this study, organ radiation doses were calculated for the renal agent 99mTc-DTPA in children. Bio-kinetic energy of 99mTc-DTPA was evaluated by scintigraphy and estimates for absorbed radiation dose were provided using standard medical internal radiation dosimetry (MIRD) techniques. Material and Methods: In this applied research, fourteen children patients (6 males and 8 females) were imaged using a series of planar and SPECT images after injecting with technetium-99m diethylenetriaminepentaacetic acid (99mTc-DTPA). A hybrid planar/SPECT method was used to plot time-activity curves to obtain the residence time of the source organs and also MIRDOSE software was used to calculate the absorbed dose of every organ. P-values were calculated using t-tests in order to make a comparison between the adsorbed doses of male and female groups. Results: Mean absorbed doses (µGy/MBq) for urinary bladder wall, kidneys, gonads, liver and adrenals were 213.5±47.8, 12.97±6.23, 12.0±2.5, 4.29±1.47, and 3.31±0.96, respectively. Furthermore, the mean effective dose was 17.5±3.7 µSv/ MBq. There was not any significant difference in the mean absorbed dose of the two groups. Conclusion: Bladder cumulated activity was the most contribution in the effective dose of patients scanned with 99mTc-DTPA. Using a hybrid planar/SPECT method can cause an increase in accumulated activity accuracy for the region of interest. Moreover, patient-specified internal dosimetry is recommended. Citation: Ebrahimnejad Gorji K, Abedi Firouzjah R, Khanzadeh F, Abdi-Goushbolagh N, Banaei A, Ataei Gh. Estimating the Absorbed Dose of Organs in Pediatric Imaging of 99mTc-DTPA Radiopharmaceutical using MIRDOSE Software. J Biomed Phys Eng. 2019;9(3):285-294. https://doi.org/10.31661/jbpe.v0i0.984.

This study assessed the in vivo distribution of 11C-nicotine and the absorbed radiation dose from whole-body 11C-nicotine PET imaging of 11 healthy (5 male and 6 female) subjects. Methods: After an initial CT attenuation scan, 11C-nicotine was administered via intravenous injection. A dynamic PET scan was acquired for 90 s with the brain in the field of view, followed by a series of 13 whole-body PET scans acquired over a 90-min period. Regions of interest were drawn over organs visible in the reconstructed PET images. Time-activity curves were generated, and the residence times were calculated. The absorbed radiation dose for the whole body was calculated by entering the residence time in OLINDA/EXM 1.0 software to model the equivalent organ dose and the effective dose for a 70-kg man. Results: The mean residence times for 11C-nicotine in the liver, red marrow, brain, and lungs were 0.048 ± 0.010, 0.031 ± 0.005, 0.021 ± 0.004, and 0.020 ± 0.005 h, respectively. The mean effective dose for 11C-nicotine was 5.44 ± 0.67 μSv/MBq. The organs receiving the highest absorbed dose from the 11C-nicotine injection were the urinary bladder wall (14.68 ± 8.70 μSv/MBq), kidneys (9.56 ± 2.46 μSv/MBq), liver (8.94 ± 1.67 μSv/MBq), and spleen (9.49 ± 3.89 μSv/MBq). The renal and hepatobiliary systems were the major clearance and excretion routes for radioactivity. Conclusion: The estimated radiation dose from 11C-nicotine administration is relatively modest and would allow for multiple PET examinations on the same subject.

Objectives To quantify the impact of image optimization on absorbed radiation dose and associated risk in children undergoing cardiac catheterization. Background Various imaging and fluoroscopy system technical parameters including camera magnification, source-to-image distance, collimation, antiscatter grids, beam quality, and pulse rates, all affect radiation dose but have not been well studied in younger children. Methods We used anthropomorphic phantoms (ages: newborn and 5 years old) to measure surface radiation exposure from various imaging approaches and estimated absorbed organ doses and effective doses (ED) using Monte Carlo simulations. Models developed in the National Academies' Biological Effects of Ionizing Radiation VII report were used to compare an imaging protocol optimized for dose reduction versus suboptimal imaging (+20 cm source-to-image-distance, +1 magnification setting, no collimation) on lifetime attributable risk (LAR) of cancer. Results For the newborn and 5-year-old phantoms, respectively ED changes were as follows: +157% and +232% for an increase from 6-inch to 10-inch camera magnification; +61% and +59% for a 20 cm increase in source-to-image-distance; −42% and −48% with addition of 1-inch periphery collimation; −31% and −46% with removal of the antiscatter grid. Compared with an optimized protocol, suboptimal imaging increased ED by 2.75-fold (newborn) and fourfold (5 years old). Estimated cancer LAR from 30-min of posteroanterior fluoroscopy using optimized versus suboptimal imaging, respectively was 0.42% versus 1.23% (newborn female), 0.20% versus 0.53% (newborn male), 0.47% versus 1.70% (5-year-old female) and 0.16% versus 0.69% (5-year-old male). Conclusions Radiation-related risks to children undergoing cardiac catheterization can be substantial but are markedly reduced with an optimized imaging approach. © 2016 Wiley Periodicals, Inc.

Background: 177Lu-octreotate is an effective treatment modality for patients with metastatic neuroendocrine tumors. The kidney is a critical dose-limiting organ in that modality. We investigated the absorbed doses in the kidney and compared whole kidney volume (WKV) and small (4 cm3) volume of the kidney (SV) methods. We also evaluated a new calculation method that was based on two single photon emission computed tomography/computed tomography (SPECT/CT) scans.Methods: Absorbed radiation doses in the kidneys were calculated for 24 patients with neuroendocrine tumors. All patients received four cycles of 177Lu-octreotate given at eight-week intervals with a mean activity of 7.1 GBq (range 3.28–8.79 GBq). Absorbed doses and half-lives were calculated by the WKV and SV methods. Dosimetry was determined for the cortex and medulla in the first treatment cycle.Results: The mean absorbed radiation dose was 0.44 ± 0.15 Gy/GBq for the WKV method and, 0.74 ± 0.28 Gy/GBq for the SV method. Three patients had...

Thoron (220 Rn) is a natural radioactive gas, tasteless, odourless, colourless, undetectable without proper equipment. This gas is carcinogenic, just like radon (222 Rn) but due to the short half-life (55.6s) and a small amount in the environment, its share in the absorbed radiation dose is often neglected. However, in areas rich in thorium (232Th), the radiation dose from the thoron can be much larger and quite significant. The problem is to measure the concentration of the thoron due to its short decay time as well as the fact that it is alpha-emitting as radon. An even greater challenge is to determine the emanation coefficient for the thoron. The method used in this experiment was developed by S.D. Kanse based on the work of D.J Greeman and adapted to the equipment used in Laboratory of Radiometric Expertise IFJ PAN. In the technique used to determine the thoron emanation coefficient, a closed loop system is used in which thoron is pushed out by means of a flow system from the sample and measured by a AlphaGuad DF2000 detector that is adapted to determine concentration of this gas. A sample of the material is placed between 2 filters in the geometry of the sandwich. This arrangement ensures that the thickness of the powder sample is significantly less than the length of the thoron diffusion, thus avoiding significant loss of the thoron due to intergranular absorption and facilitates the complete removal of this gas escaping from the powder. Using this technique, it is important to determine the concentration of 226Ra and the 232Th, since for the AlphaGuard detector, the ratio between thoron and radon should not exceed 5:1 for proper determination of the thoron concentration. Measurements of 226Ra and 232Th activity were carried out using gamma spectroscopy (HPGe detector). It was examined how the type of filter and grain size of sample affects the obtained results.

Sophisticated techniques employed in radiotherapy for irradiation of tumours require comprehensive dosimetry allowing for precise, high resolution measurements of radiation dose distribution in three dimensions and verification of treatment planning systems. Polymer gel dosimetry has been shown to be a unique technique for three-dimensional high resolution measurements of absorbed radiation dose distributions. If exposed to ionizing radiation, radical polymerisation and crosslinking of monomeric components take place in a 3D polymer gel dosimeter, leading to the formation of large polymeric structures that scatter visible light. This feature allows for optical observation of the effects of the absorbed dose and its distribution. Presently, magnetic resonance imaging is employed the most often for analysis of 3D polymer gel dosimeters. However, much attention is also being given to the development of optical computed tomography since this technique is hoped to serve as a substitute for expensive and not easily available magnetic resonance imaging. The optical scanner presented in this work consists of a laser diode, a scanning system and a signal detector. A 3D polymer gel dosimeter is measured in an immersion liquid in order to reduce deflection of the light from the dosimeter phantom. The very first results were obtained with the newly constructed scanner for PABIGnx 3D polymer gel dosimeter, which was inhomogeneously irradiated with 192Ir brachytherapy source. The results have been contrasted with those for magnetic resonance imaging and are presented in this work together with the description of the optical scanner. Currently, optimization of the optical scanner is performed.

Use of ionizing radiation (IR) in various industrial, medical and other applications can potentially increase the risk of medical, occupational or accidental human exposure. Additionally, in the event of a radiological or nuclear (R/N) incident, several tens of hundreds and thousands of people are likely to be exposed to IR. IR causes serious health effects including mortality from acute radiation syndrome and therefore it is imperative to determine the absorbed radiation dose, which will enable physicians in making an appropriate clinical 'life-saving' decision. The 'Dicentric Chromosome Assay (DCA)' is the gold standard for estimating the absorbed radiation dose but its performance is time consuming and laborious. Further, timely evaluation of dicentric chromosomes (DCs) for dose estimation in a large number of samples provides a bottleneck because of a limited number of trained personnel and a prolonged time for manual analysis. To circumvent some of these technical issues, we developed and optimized a miniaturized high throughput version of DCA (mini-DCA) in a 96-microtube matrix with bar-coded 1.4 ml tubes to enable the processing of a large number of samples. To increase the speed of DC analysis for radiation dose estimation, a semi-automated scoring was optimized using the Metafer DCScore algorithm. The accuracy of mini-DCA in dose estimation was verified and validated though comparison with conventional DCA performed in 15 ml conical tubes. The mini-DCA considerably reduced the sample processing time by a factor of 4 when compared to the conventional DCA. Further, the radiation doses estimated by mini-DCA using the triage mode of scoring (50 cells or 30 DCs) were similar to that of conventional DCA using 300-500 cells. The mini-DCA coupled with semi-automated DC scoring not only reduced the sample processing and analysis times by a factor of 4 but also enabled the processing of a large number of samples at once. Our mini-DCA method, once automated for high throughput robotic platforms, will be an effective radiological triage tool for mass casualty incidents.

Upotreba kompjuterizovane tomografije (CT) je veoma frekventna, kako u humanoj, tako i u veterinarskoj medicini. Imajući u vidu činjenicu da su doze zračenja koje pacijent primi prilikom CT pregleda višestruko veće od doza koje primi tokom konvencionalne rendgenografije, velika paţnja se posvećuje proceni opravdanosti ove vrste dijagnostičkog postupka i njegovoj optimizaciji, uz minimalno izlaganje pacijenata radijacionom opterećenju. Shodno tome, osnovni cilj ovog istraţivanja je podrazumevao ispitivanje korelacije izmeĎu apsorbovanih doza zračenja i stepena aktivnosti antioksidativnih enzima u pojedinim organima kunića nakon CT pregleda obavljenog pri različitim vrednosti napona i jačine struje u rendgenskoj cevi. Eksperiment je izvršen na 66 polno zrelih muţjaka novozelandskog belog kunića, rasporeĎenih u 11 eksperimentalnih grupa, sa po šest ţivotinja u svakoj. Kontrolne grupe kunića nisu izlagane zračenju već su ţrtvovane odmah (grupa NT), odnosno dva sata (grupa A1) i sedam dana (grupa A2) nakon primene anestezije koja je postignuta upotrebom ketamina i ksilazina. Ţivotinje iz preostalih osam grupa su, pre izlaganja x-zračenju, najpre anestezirane, kako bi se obezbedilo njihovo mirovanje tokom CT pregleda. Sva snimanja su izvršena pod sledećim uslovima: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17,9 mGy (I1 i I2 grupa); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25,2 mGy (II1 i II2 grupa); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29,8 mGy (III1 i III2 grupa) i U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42,1 mGy (IV1 i IV2 grupa). Ţivotinje iz I1, II1, III1 i IV1 grupe su bile ţrtvovane dva sata nakon snimanja, dok su kunići iz I2, II2, III2 i IV2 grupe ţrtvovani nakon sedam dana. Neposredno po ţrtvovanju obavljenom metodom dekapitacije, od svih ţivotinja je prikupljan biološki materijal (uzorci krvi eritrocita, mozga, pluća, srca, jetre, slezine, bubrega, tankog creva i semenika) u kojima je odreĎivana aktivnost sledećih antioksidativnih enzima: superoksid dismutaze (SOD), mangan superoksid dismutaze (MnSOD), bakar-cink superoksid dismutaze (CuZnSOD), katalaze (CAT), glutation peroksidaze (GSH-Px) i glutation reduktaze (GR). Izmerene aktivnosti antioksidativnih enzima u ispitivanim uzorcima su komparirane sa vrednostima asporbovanih doza koje su izračunate na predhodno konstruisanom voksel fantomu reprezentativnog kunića. S obzirom na činjenicu da eritrocite i tanko crevo nije moguće prikazati u voksel geometriji, stepen oksidativnih promena u ovim strukturama je poreĎen sa CTDIw vrednostima... Usage of computed tomography (CT) is very frequent, both in human and veterinary medicine. Bearing in mind that the radiation dose, that patient receive during CT examination, is several times higher than during conventional radiography, much attention is devoted to evaluate necessity of this diagnostic procedure and its optimization, along with the minimal exposure of patients to the radiation load. According to this, the main goal of these investigations was to explore a correlation between absorbed radiation doses and the degree of activity of antioxidant enzymes in rabbit organs following CT examination performed by different tube voltage and amperage values. Experiment was conducted on 66 mature male New Zealand rabbits divided in 11 groups, consisting of six animals each. Animals from the control groups (NT) were not irradiated and were sacrificed immediately after two hours (group A1) and seven days (group A2) following anesthesia induced by ketamine and xylasine. Animals from the remaining eight groups were anesthetized, prior to irradiation, to ensure still positioning during CT examination. All examinations were performed under the following conditions: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17.9 mGy (groups I1 and I2); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25.2 mGy (groups II1 and II2); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29.8 mGy (groups III1 and III2) and U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42.1 mGy (groups IV1 and IV2). Animals from the groups I1, II1, III1 and IV1 were sacrificed two hours following irradiation, while rabbits from the groups I2, II2, III2 and IV2 were sacrificed after seven days. Immediately after sacrifice, performed by decapitation method, organ samples were taken (blood – erythrocytes, brain, lungs, heart, liver, spleen, kidney, small intestine and testicles) for estimation of the following antioxidant enzyme activity: superoxide dismutase (SOD), Mn superoxide dismutase (MnSOD), Copper-Zinc superoxide dismutase CuZnSOD, catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR). Values, of the antioxidant enzyme activities in investigated samples, were then compared with values of the absorbed doses calculated on the previously constructed voxel phantom of the representative rabbit. According to the fact, that erythrocytes and small intestine can't be presented in voxel geometry, the degree of oxidative changes in these structures was compared to CTDIw values...

We wished to measure the absorbed radiation dose during fluoroscopically controlled vertebroplasty and to assess the possibility of deterministic radiation effects to the operator. The dose was measured in 11 consecutive procedures using thermoluminescent ring dosimeters on the hand of the operator and electronic dosimeters inside and outside of the operator's lead apron. We found doses of 0.022-3.256 mGy outside and 0.01-0.47 mGy inside the lead apron. Doses on the hand were higher, 0.5-8.5 mGy. This preliminary study indicates greater exposure to the operator's hands than expected from traditional apron measurements.

Usage of computed tomography (CT) is very frequent, both in human and veterinary medicine. Bearing in mind that the radiation dose, that patient receive during CT examination, is several times higher than during conventional radiography, much attention is devoted to evaluate necessity of this diagnostic procedure and its optimization, along with the minimal exposure of patients to the radiation load. According to this, the main goal of these investigations was to explore a correlation between absorbed radiation doses and the degree of activity of antioxidant enzymes in rabbit organs following CT examination performed by different tube voltage and amperage values. Experiment was conducted on 66 mature male New Zealand rabbits divided in 11 groups, consisting of six animals each. Animals from the control groups (NT) were not irradiated and were sacrificed immediately after two hours (group A1) and seven days (group A2) following anesthesia induced by ketamine and xylasine. Animals from the remaining eight groups were anesthetized, prior to irradiation, to ensure still positioning during CT examination. All examinations were performed under the following conditions: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17.9 mGy (groups I1 and I2); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25.2 mGy (groups II1 and II2); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29.8 mGy (groups III1 and III2) and U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42.1 mGy (groups IV1 and IV2). Animals from the groups I1, II1, III1 and IV1 were sacrificed two hours following irradiation, while rabbits from the groups I2, II2, III2 and IV2 were sacrificed after seven days. Immediately after sacrifice, performed by decapitation method, organ samples were taken (blood – erythrocytes, brain, lungs, heart, liver, spleen, kidney, small intestine and testicles) for estimation of the following antioxidant enzyme activity: superoxide dismutase (SOD), Mn superoxide dismutase (MnSOD), Copper-Zinc superoxide dismutase CuZnSOD, catalase (CAT), glutathione peroxidase (GSH-Px) and glutathione reductase (GR). Values, of the antioxidant enzyme activities in investigated samples, were then compared with values of the absorbed doses calculated on the previously constructed voxel phantom of the representative rabbit. According to the fact, that erythrocytes and small intestine can't be presented in voxel geometry, the degree of oxidative changes in these structures was compared to CTDIw values... Upotreba kompjuterizovane tomografije (CT) je veoma frekventna, kako u humanoj, tako i u veterinarskoj medicini. Imajući u vidu činjenicu da su doze zračenja koje pacijent primi prilikom CT pregleda višestruko veće od doza koje primi tokom konvencionalne rendgenografije, velika paţnja se posvećuje proceni opravdanosti ove vrste dijagnostičkog postupka i njegovoj optimizaciji, uz minimalno izlaganje pacijenata radijacionom opterećenju. Shodno tome, osnovni cilj ovog istraţivanja je podrazumevao ispitivanje korelacije izmeĎu apsorbovanih doza zračenja i stepena aktivnosti antioksidativnih enzima u pojedinim organima kunića nakon CT pregleda obavljenog pri različitim vrednosti napona i jačine struje u rendgenskoj cevi. Eksperiment je izvršen na 66 polno zrelih muţjaka novozelandskog belog kunića, rasporeĎenih u 11 eksperimentalnih grupa, sa po šest ţivotinja u svakoj. Kontrolne grupe kunića nisu izlagane zračenju već su ţrtvovane odmah (grupa NT), odnosno dva sata (grupa A1) i sedam dana (grupa A2) nakon primene anestezije koja je postignuta upotrebom ketamina i ksilazina. Ţivotinje iz preostalih osam grupa su, pre izlaganja x-zračenju, najpre anestezirane, kako bi se obezbedilo njihovo mirovanje tokom CT pregleda. Sva snimanja su izvršena pod sledećim uslovima: U 110 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 17,9 mGy (I1 i I2 grupa); U 130 kV, I 63 mA, te 1 s, T 10 mm, CTDIw 25,2 mGy (II1 i II2 grupa); U 110 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 29,8 mGy (III1 i III2 grupa) i U 130 kV, I 105 mA, te 1 s, T 10 mm, CTDIw 42,1 mGy (IV1 i IV2 grupa). Ţivotinje iz I1, II1, III1 i IV1 grupe su bile ţrtvovane dva sata nakon snimanja, dok su kunići iz I2, II2, III2 i IV2 grupe ţrtvovani nakon sedam dana. Neposredno po ţrtvovanju obavljenom metodom dekapitacije, od svih ţivotinja je prikupljan biološki materijal (uzorci krvi eritrocita, mozga, pluća, srca, jetre, slezine, bubrega, tankog creva i semenika) u kojima je odreĎivana aktivnost sledećih antioksidativnih enzima: superoksid dismutaze (SOD), mangan superoksid dismutaze (MnSOD), bakar-cink superoksid dismutaze (CuZnSOD), katalaze (CAT), glutation peroksidaze (GSH-Px) i glutation reduktaze (GR). Izmerene aktivnosti antioksidativnih enzima u ispitivanim uzorcima su komparirane sa vrednostima asporbovanih doza koje su izračunate na predhodno konstruisanom voksel fantomu reprezentativnog kunića. S obzirom na činjenicu da eritrocite i tanko crevo nije moguće prikazati u voksel geometriji, stepen oksidativnih promena u ovim strukturama je poreĎen sa CTDIw vrednostima...

The most frequently used and the best established method of biological dosimetry at present is the dicentric chromosome assay, which is poorly suitable for a mass casualties scenario. This gives rise to the need for the development of new, high-throughput assays for rapid identification of the subjects exposed to ionizing radiation. In the present study, we tested the usefulness of gene expression analysis in blood cells for biological dosimetry. Human peripheral blood from three healthy donors was X-irradiated with doses of 0 (control), 0.6, and 2 Gy. The mRNA level of 16 genes (ATF3, BAX, BBC3, BCL2, CDKN1A, DDB2, FDXR, GADD45A, GDF15, MDM2, PLK3, SERPINE1, SESN2, TNFRSF10B, TNFSF4, and VWCE) was assessed by reverse transcription quantitative PCR 6, 12, 24, and 48 h after exposure with ITFG1 and DPM1 used as a reference genes. The panel of radiation-responsive genes was selected comprising GADD45A, CDKN1A, BAX, BBC3, DDB2, TNFSF4, GDF15, and FDXR. Cluster analysis showed that ΔCt values of the selected genes contained sufficient information to allow discrimination between irradiated and non-irradiated blood samples. The samples were clearly grouped according to the absorbed doses of radiation and not to the time interval after irradiation or to the blood donor. Electronic supplementary material The online version of this article (doi:10.1007/s00411-015-0603-8) contains supplementary material, which is available to authorized users.

Radionuclide therapy with low-energy auger electron emitters may provide high antitumor efficacy while keeping the toxicity to normal organs low. Here we evaluated the usefulness of an auger electron emitter and compared it with that of a beta emitter for tumor treatment in in vitro models and conducted a dosimetry simulation using radioiodine-labeled metaiodobenzylguanidine (MIBG) as a model compound. We evaluated the cellular uptake of 125I-MIBG and the therapeutic effects of 125I- and 131I-MIBG in 2D and 3D PC-12 cell culture models. We used a Monte Carlo simulation code (PHITS) to calculate the absorbed radiation dose of 125I or 131I in computer simulation models for 2D and 3D cell cultures. In the dosimetry calculation for the 3D model, several distribution patterns of radionuclide were applied. A higher cumulative dose was observed in the 3D model due to the prolonged retention of MIBG compared to the 2D model. However, 125I-MIBG showed a greater therapeutic effect in the 2D model compared to the 3D model (respective EC50 values in the 2D and 3D models: 86.9 and 303.9 MBq/cell), whereas 131I-MIBG showed the opposite result (respective EC50 values in the 2D and 3D models: 49.4 and 30.2 MBq/cell). The therapeutic effect of 125I-MIBG was lower than that of 131I-MIBG in both models, but the radionuclide-derived difference was smaller in the 2D model. The dosimetry simulation with PHITS revealed the influence of the radiation quality, the crossfire effect, radionuclide distribution, and tumor shape on the absorbed dose. Application of the heterogeneous distribution series dramatically changed the radiation dose distribution of 125I-MIBG, and mitigated the difference between the estimated and measured therapeutic effects of 125I-MIBG. The therapeutic effect of 125I-MIBG was comparable to that of 131I-MIBG in the 2D model, but the efficacy was inferior to that of 131I-MIBG in the 3D model, since the crossfire effect is negligible and the homogeneous distribution of radionuclides was insufficient. Thus, auger electrons would be suitable for treating small-sized tumors. The design of radiopharmaceuticals with auger electron emitters requires particularly careful consideration of achieving a homogeneous distribution of the compound in the tumor.

Thermal dose and absorbed radiation dose have historically been difficult to compare because different biological mechanisms are at work. Thermal dose denatures proteins and the radiation dose causes DNA damage in order to achieve ablation. The purpose of this paper is to use the proportion of cell survival as a potential common unit by which to measure the biological effect of each procedure. Survival curves for both thermal and radiation doses have been extracted from previously published data for three different cell types. Fits of these curves were used to convert both thermal and radiation dose into the same quantified biological effect: fraction of surviving cells. They have also been used to generate and compare survival profiles from the only indication for which clinical data are available for both focused ultrasound (FUS) thermal ablation and radiation ablation: essential tremor thalamotomy. All cell types could be fitted with coefficients of determination greater than 0.992. As an illustration, survival profiles of clinical thalamotomies performed by radiosurgery and FUS are plotted on a same graph for the same metric: fraction of surviving cells. FUS and Gamma Knife have the potential to be used in combination to deliver a more effective treatment (for example, FUS may be used to debulk the main tumour mass, and radiation to treat the surrounding tumour bed). In this case, a model which compares thermal and radiation treatments is valuable in order to adjust the dose between the two.

The effect of three different acrylate group monomers, namely n-butyl acrylate, methacrylic acid and tripropylene glycol diacrylate of radiation induced grafting onto waste rubber was studied. The electron beam accelerator operated at voltage of 2MeV was used to irradiate the waste rubber at 10 kGy and 100 kGy absorbed radiation dose, respectively. The formation of grafting was observed from the increase in the grafting yield and confirmed by Transformed Infra-Red Spectroscopy results. According to the result obtained, only tripropylene glycol diacrylate was selected to graft onto waste rubber. The carbonyl bond from acrylate groups was seen at 1726 cm -1 band which confirmed the presence of TPGDA in the polymer matrix. This indicates the successful preparation of the TPGDA-grafted waste rubber via radiation induced grafting techniques.