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Interest in the problem of radon and thoron is due to the great danger resulting from exposure to these isotopes through the alpha particles they emit. Exposure to radon and thoron gases is considered a serious health problem, as previous studies have proven the relationship between exposure to alpha particle emitters and cases of lung cancer. In this paper, the concentrations of thoron, radon and their daughters in air of some buildings in Al-Rabiea neighborhood in Baghdad Governorate were measured using the technology of nuclear track detectors LR-115, which is characterized by its ability to detect low concentrations. The average value of Radon and Thoron concentration was 265.5 and 115.5 Bq/m3 respectively. The average value of annual effective dose from the resulting radon and thoron intensity that measured in different dwellings was 9.78 mSv/y that is within the acceptable ICRP 3 - 10 mSv/y. [ABSTRACT FROM AUTHOR]

Background: Hyperthermia treatment quality is usually evaluated by thermal (dose) parameters, though hyperthermic radiosensitization effects are also influenced by the time interval between the two modalities. This work applies biological modelling for clinical treatment evaluation of cervical cancer patients treated with radiotherapy plus hyperthermia by calculating the equivalent radiation dose (EQDRT, i.e., the dose needed for the same effect with radiation alone). Subsequent analyses evaluate the impact of logistics. Methods: Biological treatment evaluation was performed for 58 patients treated with 23–28 fractions of 1.8–2 Gy plus 4–5 weekly hyperthermia sessions. Measured temperatures (T50) and recorded time intervals between the radiotherapy and hyperthermia sessions were used to calculate the EQDRT using an extended linear quadratic (LQ) model with hyperthermic LQ parameters based on extensive experimental data. Next, the impact of a 30-min time interval (optimized logistics) as well as a 4‑h time interval (suboptimal logistics) was evaluated. Results: Median average measured T50 and recorded time intervals were 41.2 °C (range 39.7–42.5 °C) and 79 min (range 34–125 min), respectively, resulting in a median total dose enhancement (D50) of 5.5 Gy (interquartile range [IQR] 4.0–6.6 Gy). For 30-min time intervals, the enhancement would increase by ~30% to 7.1 Gy (IQR 5.5–8.1 Gy; p < 0.001). In case of 4‑h time intervals, an ~ 40% decrease in dose enhancement could be expected: 3.2 Gy (IQR 2.3–3.8 Gy; p < 0.001). Normal tissue enhancement was negligible (< 0.3 Gy), even for short time intervals. Conclusion: Biological treatment evaluation is a useful addition to standard thermal (dose) evaluation of hyperthermia treatments. Optimizing logistics to shorten time intervals seems worthwhile to improve treatment efficacy. [ABSTRACT FROM AUTHOR]

Abstract Background Musculoskeletal cone-beam computed tomography (CBCT) is an imaging technique for wrist assessment. In this study, we compared image quality and patient satisfaction between CBCT and multidetector computed tomography (MDCT) in traumatic wrist patients in a dose-matched setting. Methods We prospectively enrolled traumatic patients who were scheduled for CT of the wrist. Patients were randomly assigned to CBCT or MDCT. Radiation dose was kept identical between both modalities. Subsequently, patients were asked to complete a questionnaire regarding the examination. Measurements of contrast-to-noise ratio (CNR) were performed. Three blinded readers independently rated image quality on Likert scales. Results A total of 125 patients (mean age 35 years [standard deviation 16]; 91 men) were included. A total of 108 patients returned the questionnaire. With equivalent dose, CNRs were higher in CBCT compared to MDCT (p

Background: Musculoskeletal cone-beam computed tomography (CBCT) is an imaging technique for wrist assessment. In this study, we compared image quality and patient satisfaction between CBCT and multidetector computed tomography (MDCT) in traumatic wrist patients in a dose-matched setting. Methods: We prospectively enrolled traumatic patients who were scheduled for CT of the wrist. Patients were randomly assigned to CBCT or MDCT. Radiation dose was kept identical between both modalities. Subsequently, patients were asked to complete a questionnaire regarding the examination. Measurements of contrast-to-noise ratio (CNR) were performed. Three blinded readers independently rated image quality on Likert scales. Results: A total of 125 patients (mean age 35 years [standard deviation 16]; 91 men) were included. A total of 108 patients returned the questionnaire. With equivalent dose, CNRs were higher in CBCT compared to MDCT (p < 0.001) and the median ratings of image quality were better for CBCT compared to MDCT (p ≤ 0.04). Patients only rated positioning in CBCT as more comfortable than in MDCT (p < 0.001), while there were no further differences regarding satisfaction with both modalities. Conclusions: At equivalent dose settings to MDCT, CBCT showed a high image quality for the depiction of bony structures, soft tissue and artifacts in wrist examinations of trauma patients. Overall, patients were equally satisfied with both methods. Altogether, CBCT might be a promising alternative for wrist imaging. However, further studies with more different devices are needed. [ABSTRACT FROM AUTHOR]

Terrestrial gamma radiation is one of the major outdoor radiation exposures to the general public that varies substantially based on the type and geological properties of the soil. The objective of this study is to evaluate the naturally occurring radioactive materials (NORMs) distribution and assess the hazard parameters in the riverbank soil within various industrial zones in the densely populated Dhaka and Chattogram cities of Bangladesh. The mean activities of 226Ra (37 ± 3), 232Th (58 ± 4), and 40K (1129 ± 18) Bqkg−1 in the assessed soil samples were found to be slightly higher than the world average values 32, 35, and 420 Bqkg−1, respectively. The mean radium equivalent activity (207.49 Bqkg−1) and the external and internal hazard indices were within the recommended limits of 370 Bqkg−1 and <1, respectively. The mean absorbed dose rate (99.47 nGyhr−1), annual effective dose (0.12 mSva−1), ELCR (4.27 × 10−4), and gamma level index (1.58) exceeded the world average values 59 nGyhr−1, 0.07 mSva−1, 2.9 × 10−4, and 1 respectively. However, the studied areas are safe from a radiological viewpoint with no radiation health hazard to the people. The results of this study can be utilized to produce factual baseline data for future studies. [ABSTRACT FROM AUTHOR]

Objective: In psychiatry, polypharmacy or high psychotropic drug doses increase adverse drug event (ADE) prevalence. However, the full relationship between polypharmacy and ADEs is unclear, and few studies have evaluated dose equivalents for psychotropic drugs for ADEs. Thus, we conducted a retrospective analysis to clarify the effects of polypharmacy and chlorpromazine (CP)‐, diazepam (DAP)‐, and imipramine‐ equivalent doses on all ADEs in inpatients. Methods: Psychiatric inpatients in a Japanese hospital from April 1, 2016 to March 31, 2018, were enrolled. ADE severity and causality were assessed. Multiple logistic regression analyses were performed to evaluate ADE risk factors. Results: Among 462 patients analyzed, out of 471 patients enrolled, 145 (31.4%) experienced ADEs. The causality assessment determined that "possible" was 96.5%. The most common ADEs were nervous system disorders (35%). Multiple logistic regression analyses indicated an increase in ADE prevalence with the number of drugs used (≥5; p = 0.026); CP‐equivalent dose (p = 0.048); and endocrine, nutritional, and metabolic disorders (p = 0.045). DAP‐equivalent dose; infectious and parasitic diseases; and injury, poisoning, and consequences of other external causes decreased ADE prevalence (p = 0.047, 0.022, and 0.021, respectively). Conclusions: Avoiding polypharmacy in psychiatric inpatients and adjusting drug regimens to safe equivalent doses could reduce ADEs during hospitalization. [ABSTRACT FROM AUTHOR]

BackgroundGamma source irradiation is the most commonly used way at present for the equivalent dose (DE) determination of fossil samples in electron spin resonance (ESR) dating. However, it is facility-limited and time-consuming in many cases.PurposeThis study aims to establish the standardised growth curves (SGCs) of fossil enamel samples for determining the DE by ESR without gamma irradiation.MethodsFirst of all, we analyzed 20 tooth samples from the Late Pleistocene sites, and they exhibited similar dose response characteristics. Then, based on our preliminary work, we attempted to establish the SGCs of these Late Pleistocene fossil teeth using three different methods: (1) a simple method (fitting the natural dose points of fossil samples from Middle to Upper Pleistocene sites with exponential functions), (2) an average method (fitting the dose points with averaged ESR signal intensities), and (3) a representative sample method (establishing a SGC by using a representative sample). Finally, dose values obtained by each method were compared with those determined by the additive dose method (ADM).ResultsThe results of DE determined by the simple and average methods are close, with a deviation of less than 32% from the ADM results. The dose values obtained by SGC using the representative sample method generally agree with those of the ADM, with a deviation within 26%, which is the smallest among the three methods.ConclusionAlthough the uncertainties of the dose values obtained for the SGCs are not very close to those obtained using the ADM, it indicates the potential to quickly determine a more reasonable Dmax for irradiation, identify the possible intrusion of fossil samples, and analyze small or precious fossil samples.

Background: Although re‐irradiation is increasingly used in clinical practice, almost no dedicated planning software exists. Purpose: Standard dose‐based optimization functions were adjusted for re‐irradiation planning using accumulated equivalent dose in 2‐Gy fractions (EQD2) with rigid or deformable dose mapping, tissue‐specific α/β, treatment‐specific recovery coefficients, and voxelwise adjusted EQD2 penalization levels based on the estimated previously delivered EQD2 (EQD2deliv). Methods: To demonstrate proof‐of‐concept, 35 Gy in 5 fractions was planned to a fictitious spherical relapse planning target volume (PTV) in three separate locations following previous prostate treatment on a virtual human phantom. The PTV locations represented one repeated irradiation scenario and two re‐irradiation scenarios. For each scenario, three re‐planning strategies with identical PTV dose‐functions but various organ at risk (OAR) EQD2‐functions was used: 1)reRTregular: Regular functions with fixed EQD2 penalization levels larger than EQD2deliv for all OAR voxels.2)reRTreduce: As reRTregular, but with lower fixed EQD2 penalization levels aiming to reduce OAR EQD2.3)reRTvoxelwise: As reRTregular and reRTreduce, but with voxelwise adjusted EQD2 penalization levels based on EQD2deliv. PTV near‐minimum and near‐maximum dose (D98%/D2%), homogeneity index (HI), conformity index (CI) and accumulated OAR EQD2 (α/β = 3 Gy) were evaluated. Results: For the repeated irradiation scenario, all strategies resulted in similar dose distributions. For the re‐irradiation scenarios, reRTreduce and reRTvoxelwise reduced accumulated average and near‐maximum EQD2 by ˜1–10 Gy for all relevant OARs compared to reRTregular. The reduced OAR doses for reRTreduce came at the cost of distorted dose distributions with D98% = 92.3%, HI = 12.0%, CI = 73.7% and normal tissue hot spots ≥150% for the most complex scenario, while reRTregular (D98% = 98.1%, HI = 3.2%, CI = 94.2%) and reRTvoxelwise (D98% = 96.9%, HI = 6.1%, CI = 93.7%) fulfilled PTV coverage without hot spots. Conclusions: The proposed re‐irradiation‐specific EQD2‐based optimization functions introduce novel planning possibilities with flexible options to guide the trade‐off between target coverage and OAR sparing with voxelwise adapted penalization levels based on EQD2deliv. [ABSTRACT FROM AUTHOR]

Quartz, which is one of the most abundant minerals in nature, can be found in magmatic and metamorphic forms, as well as the usual components of granite and sedimentary formations. Quartz minerals, which are also known as the main component of quartzites, are also known as gangue minerals in many mineralizations. Quartz samples from two different sampling levels, namely the Kaletepe lower and the Kaletepe upper region, used in the study were prepared. Thermoluminescence (TL) glow curves of the samples exposed to radiation with a 90Sr/90Y β source were recorded with a TLD reader. While peaks were obtained at approximately 270 °C from the glow curves of the Kaletepe lower samples irradiated with β source, peaks were obtained at approximately 270 °C and 350 °C from the Kaletepe upper samples. When the annual average dose and age values of the lower and upper Kaletepe samples are examined, it can be said that it was formed in a time period of ~8000 years between two areas with a height difference of 130m. [ABSTRACT FROM AUTHOR]

Abstract Background The use of lutetium-177 (177Lu)-based radiopharmaceuticals in peptide receptor nuclear therapy is increasing, but so is the number of nuclear medicine workers exposed to higher levels of radiation. In recent years, [177Lu]Lu-DOTA-TATE has begun to be widely used for the treatment of neuroendocrine tumours. However, there are few studies evaluating the occupational radiation exposure during its administration, and there are still some challenges that can result in higher doses to the staff, such as a lack of trained personnel or fully standardised procedures. In response, this study aims to provide a comprehensive analysis of occupational doses to the staff involved in the administration of [177Lu]Lu-DOTA-TATE. Results A total of 32 administrations of [177Lu]Lu-DOTA-TATE (7.4 GBq/session) carried out by a physician and a nurse, were studied. In total, two physicians and four nurses were independently monitored with cumulative (passive) and/or real-time (active) dosemeters. Extremity, eye lens and whole-body doses were evaluated in terms of the dosimetric quantities Hp(0.07), Hp(3) and Hp(10), respectively. It was obtained that lead aprons reduced dose rates and whole-body doses by 71% and 69% for the physicians, respectively, and by 56% and 68% for the nurses. On average, normalised Hp(10) values of 0.65 ± 0.18 µSv/GBq were obtained with active dosimetry, which is generally consistent with passive dosemeters. For physicians, the median of the maximum normalised Hp(0.07) values was 41.5 µSv/GBq on the non-dominant hand and 45.2 µSv/GBq on the dominant hand. For nurses 15.4 µSv/GBq on the non-dominant and 13.9 µSv/GBq on the dominant hand. The ratio or correction factor between the maximum dose measured on the hand and the dose measured on the base of the middle/ring finger of the non-dominant hand resulted in a factor of 5/6 for the physicians and 3/4 for the nurses. Finally, maximum normalised Hp(3) doses resulted in 2.02 µSv/GBq for physicians and 1.76 µSv/GBq for nurses. Conclusions If appropriate safety measures are taken, the administration of [177Lu]Lu-DOTA-TATE is a safe procedure for workers. However, regular monitoring is recommended to ensure that the annual dose limits are not exceeded.

Background: The use of lutetium-177 (177Lu)-based radiopharmaceuticals in peptide receptor nuclear therapy is increasing, but so is the number of nuclear medicine workers exposed to higher levels of radiation. In recent years, [177Lu]Lu-DOTA-TATE has begun to be widely used for the treatment of neuroendocrine tumours. However, there are few studies evaluating the occupational radiation exposure during its administration, and there are still some challenges that can result in higher doses to the staff, such as a lack of trained personnel or fully standardised procedures. In response, this study aims to provide a comprehensive analysis of occupational doses to the staff involved in the administration of [177Lu]Lu-DOTA-TATE. Results: A total of 32 administrations of [177Lu]Lu-DOTA-TATE (7.4 GBq/session) carried out by a physician and a nurse, were studied. In total, two physicians and four nurses were independently monitored with cumulative (passive) and/or real-time (active) dosemeters. Extremity, eye lens and whole-body doses were evaluated in terms of the dosimetric quantities Hp(0.07), Hp(3) and Hp(10), respectively. It was obtained that lead aprons reduced dose rates and whole-body doses by 71% and 69% for the physicians, respectively, and by 56% and 68% for the nurses. On average, normalised Hp(10) values of 0.65 ± 0.18 µSv/GBq were obtained with active dosimetry, which is generally consistent with passive dosemeters. For physicians, the median of the maximum normalised Hp(0.07) values was 41.5 µSv/GBq on the non-dominant hand and 45.2 µSv/GBq on the dominant hand. For nurses 15.4 µSv/GBq on the non-dominant and 13.9 µSv/GBq on the dominant hand. The ratio or correction factor between the maximum dose measured on the hand and the dose measured on the base of the middle/ring finger of the non-dominant hand resulted in a factor of 5/6 for the physicians and 3/4 for the nurses. Finally, maximum normalised Hp(3) doses resulted in 2.02 µSv/GBq for physicians and 1.76 µSv/GBq for nurses. Conclusions: If appropriate safety measures are taken, the administration of [177Lu]Lu-DOTA-TATE is a safe procedure for workers. However, regular monitoring is recommended to ensure that the annual dose limits are not exceeded. [ABSTRACT FROM AUTHOR]

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Background and Aim: We measured radiation emission from the patients undergoing myocardial perfusion scan after leaving nuclear medicine department to demonstrate how much radiation hospital staff or patients’ companions, in the vicinity of the patients would receive. We also evaluated the relationship of age, sex, and body mass index with the emitted radiation rate. Material and Methods: In this study 60 patients (41 females and 19 males) after undergoing 99mTc-sestamibi myocardial perfusion scan with a dose of 925±185 MBq, were selected randomly. The equivalent dose rate at distances of 0.25 m, 1 m and 2 m from the patients were measured by a survey meter before leaving nuclear medicine department and after 12 & 24 hours. Data were analyzed by T-test, Pearson correlation coefficient and ANOVA. Results: The mean equivalent dose rates in unit of microsievert per hour at distances of 0.25 m, 1 m and 2 m from the patients were (120.6 ± 24.1, 19.4 ± 3.8, 8.4 ± 1.3) at leaving time, (29.1 ± 8.7, 5.3 ± 1.2, 2.1 ± 0.8) after 12 hours and (4.3 ± 1.5, 0.8 ± 0.6, 0.3 ± 0.1) after 24 hours, respectively. The mean equivalent dose rate showed no relationship with gender and age, but it was inversely correlated with body mass index (P-value

Simple Summary: Repeat radiotherapy to a part of the body that has previously been treated with radiotherapy is challenging. It is difficult to determine where the dose previously went and how to safely deliver the best possible radiotherapy re-treatment. A tool designed to create better re-treatment plans is developed. In this work, we evaluate the safety of the new tools, which is an essential step before using it to make changes to patient treatments. (1) Background: The STRIDeR (Support Tool for Re-Irradiation Decisions guided by Radiobiology) planning pathway aims to facilitate anatomically appropriate and radiobiologically meaningful re-irradiation (reRT). This work evaluated the STRIDeR pathway for robustness compared to a more conservative manual pathway. (2) Methods: For ten high-grade glioma reRT patient cases, uncertainties were applied and cumulative doses re-summed. Geometric uncertainties of 3, 6 and 9 mm were applied to the background dose, and LQ model robustness was tested using α/β variations (values 1, 2 and 5 Gy) and the linear quadratic linear (LQL) model δ variations (values 0.1 and 0.2). STRIDeR robust optimised plans, incorporating the geometric and α/β uncertainties during optimisation, were also generated. (3) Results: The STRIDeR and manual pathways both achieved clinically acceptable plans in 8/10 cases but with statistically significant improvements in the PTV D98% (p < 0.01) for STRIDeR. Geometric and LQ robustness tests showed comparable robustness within both pathways. STRIDeR plans generated to incorporate uncertainties during optimisation resulted in a superior plan robustness with a minimal impact on PTV dose benefits. (4) Conclusions: Our results indicate that STRIDeR pathway plans achieved a similar robustness to manual pathways with improved PTV doses. Geometric and LQ model uncertainties can be incorporated into the STRIDeR pathway to facilitate robust optimisation. [ABSTRACT FROM AUTHOR]

To achieve surgical anesthesia in animal experimentation, it is important to select the appropriate anesthetic dose. However, few studies have investigated the reasonable anesthetic dose in tree shrew (Tupaia belangeri). The aim of the study was to review the literature to determine the most commonly used anesthetic dose in tree shrew and to calculate the reasonable equivalent dose between tree shrew and rat based on the body surface area conversion. Two groups of 10 adult tree shrews each were anesthetized with 1% sodium pentobarbital through intraperitoneal injection separately at doses of 62 mg/kg (equivalent dose) and 40 mg/kg (reported dose). Anesthetic depth and times were assessed in addition to vital signs. The results showed that the dosage was quite different across studies, ranging from 15 mg/kg to 80 mg/kg, with 40 mg/kg being the most frequently reported dose. However, the group of tree shrews anesthetized with the commonly reported dose were unable to meet the requirements of surgery. In contrast, the equivalent dose (62 mg/kg, intraperitoneal injection with sodium pentobarbital) calculated by body surface area conversion could achieve an anesthetic time of 44.28 ± 3.95 min with no serious or fatal effects. During anesthetic monitoring, we found that sodium pentobarbital had an inhibitory effect on the blood pressure, pulse rate, respiratory rate and rectal temperature in tree shrews, especially on the respiratory rate. Thus, our study indicated that the use of the equivalent dose of sodium pentobarbital was effective in anesthetizing tree shrews. [ABSTRACT FROM AUTHOR]

Biological modeling for anti-cancer treatments using mathematical models can be very supportive in gaining more insight into dynamic processes responsible for cellular response to treatment, and predicting, evaluating and optimizing therapeutic effects of treatment. This review presents an overview of the current status of biological modeling for hyperthermia in combination with radiotherapy (thermoradiotherapy). Various distinct models have been proposed in the literature, with varying complexity; initially aiming to model the effect of hyperthermia alone, and later on to predict the effect of the combined thermoradiotherapy treatment. Most commonly used models are based on an extension of the linear-quadratic (LQ)-model enabling an easy translation to radiotherapy where the LQ model is widely used. Basic predictions of cell survival have further progressed toward 3 D equivalent dose predictions, i.e., the radiation dose that would be needed without hyperthermia to achieve the same biological effect as the combined thermoradiotherapy treatment. This approach, with the use of temperature-dependent model parameters, allows theoretical evaluation of the effectiveness of different treatment strategies in individual patients, as well as in patient cohorts. This review discusses the significant progress that has been made in biological modeling for hyperthermia combined with radiotherapy. In the future, when adequate temperature-dependent LQ-parameters will be available for a large number of tumor sites and normal tissues, biological modeling can be expected to be of great clinical importance to further optimize combined treatments, optimize clinical protocols and guide further clinical studies.

Abstract Background Since it was first approved in Europe in 2016, the gallium-68 (68Ga) radiopharmaceutical [68Ga]Ga-DOTA-TOC has been widely used for imaging of somatostatin receptor (SSTR) positive tumours using positron emission tomography–computed tomography (PET/CT). Significant patient benefits have been reported, so its use is rapidly increasing. However, few studies have been published regarding occupational doses to nuclear medicine personnel handling this radiopharmaceutical, despite its manual usage at low distances from the skin and the beta-emission decay scheme, which may result in an increased absorbed dose to their hands. In this context, this study aims to analyse the occupational exposure during the administration of [68Ga]Ga-DOTA-TOC for PET/CT imaging. For this purpose, extremity, eye lens and whole-body dosimetry in terms of Hp(0.07), Hp(3) and Hp(10), respectively, was conducted on six workers with both thermoluminescent dosimeters, and personal electronic dosimeters. Results The non-dominant hand is more exposed to radiation than the dominant hand, with the thumb and the index fingertip being the most exposed sites on this hand. Qualitative analysis showed that when no shielding is used during injection, doses increase significantly more in the dominant than in the non-dominant hand, so the use of shielding is strongly recommended. While wrist dosimeters may significantly underestimate doses to the hands, placing a ring dosimeter at the base of the ring or middle finger of the non-dominant hand may give a valuable estimation of maximum doses to the hands if at least a correction factor of 5 is applied. Personal equivalent doses for the eyes did not result in measurable values (i.e., above the lowest detection limit) for almost all workers. The extrapolated annual dose estimations showed that there is compliance with the annual dose limits during management of [68Ga]Ga-DOTA-TOC for diagnostics with PET in the hospital included in this study. Conclusions Imaging with [68Ga]Ga-DOTA-TOC is a safe process for the workers performing the administration of the radiopharmaceutical, including intravenous injection to the patient and the pre- and post-activity control, as it is highly unlikely that annual dose limits will be exceeded if good working practices and shielding are used.

Objectives While working with cyclotrons used for the production of radiopharmaceuticals, workers can experience significant exposure to the adverse effects of ionizing radiation. The aim of this paper was to determine the typical level of such exposure received by such personnel while servicing cyclotrons. Material and Methods Exposure was assessed using TLD detectors placed in an anthropomorphic phantom, as well as dose meter to determine whole body and eye lens exposure. The phantom was placed in locations receiving the greatest exposure to ionizing radiation during service activities. The time spent by employees during servicing was assessed based on routine visits by service technicians. The obtained results were compared with readings of detectors worn by employees during service activities. Results The highest equivalent doses in the thoracic area were found to be received by the lungs (211.16 μSv/year). In the head and neck area, the highest dose was measured in the eye lens (3410 μSv/year). The effective dose for the whole body was found to be 1154.4 μSv/year, based on the phantom, and 149 μSv per service visit (1192 μSv/year), based on the dose meters carried by the workers. Conclusions Service workers are exposed to significant doses of ionizing radiation, representing a clear radiological protection issue. To reduce exposure to eye lenses, it is recommended to use protective goggles when working with highly-radioactive elements. Int J Occup Med Environ Health. 2022;35(6):753–60

One important issue in Boron Neutron Capture Therapy is the delivered dose to the tissues outside the tumor. An international standard for light ion beam systems sets two recommended limits for out-of-field dose based on distance from the field edge: maximum absorbed dose from all radiation types shall not exceed 0.5 % of the maximum dose at distances 15 cm to 50 cm from the field edge. At distances > 50 cm from the field edge, the maximum absorbed dose shall not exceed 0.1 %. This paper is a continuation of our previous works focused on the design of an accelerator-based neutron source for BNCT. We already designed a novel Beam Shape Assembly which meets the IAEA criteria for BNCT treatments. Using this BSA, in the present work, we characterize by Monte Carlo simulations the dose outside the neutron field. The out-of-field dose has been assessed via estimates using the ambient and equivalent dose. Also the boron uptake in healthy tissues has been analyzed for the equivalent dose computation. It is concluded that our design for a future accelerator-based source for BNCT meets reasonably well the criteria defined from other forms of radiotherapy on both equivalent and effective dose outside the field. • The criteria on out-of-field dose for the design of beams in Boron Neutron Capture Therapy are implemented based on those of other beam therapies. • Various types of dose estimates are discussed, including ambient dose and effective dose. • The out-of-field dose of the NeMeSis neutron beam fulfills the criteria. • The minimum boron uptake and T/N ratios are found safely below the requirements. [ABSTRACT FROM AUTHOR]

ESR (electron spin resonance) spectra of quartz samples irradiated with varying gamma (γ) dose were measured at different microwave power levels (0–200 mW). The microwave power saturation characteristics of Al and E ′ centers were systematically investigated, and the mechanisms by which the power saturation characteristics affected equivalent dose (D e) fitting results in ESR dating were revealed. The experimental results demonstrated that irradiation reduces the spin-lattice relaxation time, resulting in the inability to intrinsically characterize the number of spins in a series of aliquots when the ESR intensity exhibits significant saturation. The simulation results indicated that changes in spin-lattice relaxation characteristics can cause distortion in the dose response curve (DRC) at high power levels, leading to deviations in D e values. A method that uses the slope of the approximate linear regime of the power saturation curve (PSC) as an intrinsic metric of ESR intensity is proposed; this method has been preliminarily validated in both experiments and simulations. • ESR intensity varies with the number of spins, microwave power, and relaxation time. • Equivalent dose depends on ESR's intrinsic representation of the number of spins. • Irradiation alters relaxation, deviating ESR intensity's characterization of the number of spins. • Equivalent dose measured within the linear regime of the power saturation curve is intrinsic. [ABSTRACT FROM AUTHOR]

Abstract Background Re-irradiation (re-RT) is a technically challenging task for which few standardized approaches exist. This is in part due to the lack of a common platform to assess dose tolerance in relation to toxicity in the re-RT setting. To better address this knowledge gap and provide new tools for studying and developing thresholds for re-RT, we developed a novel algorithm that allows for anatomically accurate three-dimensional mapping of composite biological effective dose (BED) distributions from nominal doses (Gy). Methods The algorithm was designed to automatically convert nominal dose from prior treatment plans to corresponding BED value maps (voxel size 2.5 mm3 and α/β of 3 for normal tissue, BED3). Following the conversion of each plan to a BED3 dose distribution, deformable registration was used to create a summed composite re-irradiation BED3 plan for each patient who received two treatments. A proof-of-principle analysis was performed on 38 re-irradiation cases of initial stereotactic ablative radiotherapy (SABR) followed by either re-SABR or chemoradiation for isolated locoregional recurrence of early-stage non-small cell lung cancer. Results Evaluation of the algorithm-generated maps revealed appropriate conversion of physical dose to BED at each voxel. Of 14 patients receiving repeat SABR, there was one case each of grade 3 chest wall pain (7%), pneumonitis (7%), and dyspnea (7%). Of 24 patients undergoing repeat fractionated radiotherapy, grade 3 events were limited to two cases each of pneumonitis and dyspnea (8%). Composite BED3 dosimetry for each patient who experienced grade 2–3 events is provided and may help guide development of precise cumulative dose thresholds for organs at risk in the re-RT setting. Conclusions This novel algorithm successfully created a voxel-by-voxel composite treatment plan using BED values. This approach may be used to more precisely examine dosimetric predictors of toxicities and to establish more accurate normal tissue constraints for re-irradiation.

The paper presents the results of a calculation aimed to study the influence of ionizing, bremsstrahlung radiation on the operation of a nanosatellite obtained during the implementation of the project 0777-2020-0018 in 2020. A comparative analysis of the results of calculating the specific ionization and radiation energy losses of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), as well as their path lengths in aluminum according to the formulas of various authors and the database of materials of the National Institute of Standards and Technologies is presented. Based on the analysis results, the annual dose in the aluminum structure of the SamSat ION nanosatellite in a circular sun-synchronous orbit (SSO) is calculated. All calculations are based on the data of the energy spectra of protons and electrons of the SSO given in the Information system Spenvis of the European Space Agency. The results of calculating the integral fluxes in aluminum under the action of protons and electrons of a circular SSO for different thicknesses are obtained, and the fraction of passed particles is shown in the approximation of a single-layer stack. The radiation resistance of the electronic elements ISL70321SEH, ISL73321SEH and Virtex-4QV, Virtex-5QV included in the SamSat ION avionics and its ability to operate during a year was assessed.

The Metropolitan Region of Recife, the capital of the state of Pernambuco in northeastern Brazil, has a high demographic density and developed under a region of marine phosphorus with high concentrations of phosphate that naturally contains uranium ore, producing ionizing radiation from descendants of the radioisotope 238U where 226Ra and 210Pb are of great importance in verifying the probable harmful effects on human health due to environmental radioactivity. The supply of drinking water is the responsibility of the state-owned company COMPESA which uses wells of great depth to complete the supply of drinking water for the entire population. COMPESA and the RAE Group of the Federal University of Pernambuco developed a joint project to assess the concentrations of 226Ra and 210Pb and estimate the equivalent and effective doses caused by ingesting these radiation sources. According to the above, this research aimed to evaluate concentrations of 226Ra and 210Pb in drinking water samples from 110 deep wells in Recife. The activities of 226Ra and 210Pb ranged from 1.4 ± 0.3 to 119.3 ± 12.9 and from 25.6 ± 3.3 to 563.2 ± 45.6 mBq.L−1, with arithmetic means of 48.1 ± 3.8 and 231.1 ± 20 mBq.L−1, respectively. The equivalent doses average in bone tissue due to 226Ra and 210Pb were 0.45 ± 0.04 and 3.9 ± 0.37 mSv.y−1, and the annual average effective doses were 0.01 ± 0.00 and 0.13 ± 0.01 mSv.y−1, respectively. [ABSTRACT FROM AUTHOR]

Background: Since it was first approved in Europe in 2016, the gallium-68 (68Ga) radiopharmaceutical [68Ga]Ga-DOTA-TOC has been widely used for imaging of somatostatin receptor (SSTR) positive tumours using positron emission tomography–computed tomography (PET/CT). Significant patient benefits have been reported, so its use is rapidly increasing. However, few studies have been published regarding occupational doses to nuclear medicine personnel handling this radiopharmaceutical, despite its manual usage at low distances from the skin and the beta-emission decay scheme, which may result in an increased absorbed dose to their hands. In this context, this study aims to analyse the occupational exposure during the administration of [68Ga]Ga-DOTA-TOC for PET/CT imaging. For this purpose, extremity, eye lens and whole-body dosimetry in terms of Hp(0.07), Hp(3) and Hp(10), respectively, was conducted on six workers with both thermoluminescent dosimeters, and personal electronic dosimeters. Results: The non-dominant hand is more exposed to radiation than the dominant hand, with the thumb and the index fingertip being the most exposed sites on this hand. Qualitative analysis showed that when no shielding is used during injection, doses increase significantly more in the dominant than in the non-dominant hand, so the use of shielding is strongly recommended. While wrist dosimeters may significantly underestimate doses to the hands, placing a ring dosimeter at the base of the ring or middle finger of the non-dominant hand may give a valuable estimation of maximum doses to the hands if at least a correction factor of 5 is applied. Personal equivalent doses for the eyes did not result in measurable values (i.e., above the lowest detection limit) for almost all workers. The extrapolated annual dose estimations showed that there is compliance with the annual dose limits during management of [68Ga]Ga-DOTA-TOC for diagnostics with PET in the hospital included in this study. Conclusions: Imaging with [68Ga]Ga-DOTA-TOC is a safe process for the workers performing the administration of the radiopharmaceutical, including intravenous injection to the patient and the pre- and post-activity control, as it is highly unlikely that annual dose limits will be exceeded if good working practices and shielding are used. [ABSTRACT FROM AUTHOR]

Introduction: While ionizing radiation benefits the general population, its stochastic and nonstochastic effects necessitate the protection of patients against possible injuries. This study evaluated X-ray equivalent dose at radiology centers in Zahedan in 2017. Methods: This descriptive cross-sectional study was conducted in radiology and dentistry departments and waiting rooms. The census method was used for sampling. Six radiology centers, four public hospitals, and thirteen dental offices were chosen for this study. X-ray equivalent dose was measured in μSv/h using MKS-05 ―TERRA dosimeter radiometer. The collected data were analyzed through SPSS version 22. Results: The highest and lowest mean equivalent doses were, respectively, related to machine operators in public hospitals (0.36 ± 0.06 µsv/hr) and dental department staff (0.06 ± 0.01 µsv/hr), which were lower than the permissible level. On the other hand, exposure rate of the radiology staff of some departments was found to be 0.55 μSv/h, which is above the permissible level. Also, the operators' highest amount of radiation exposure was related to dental, chest, and lumbosacral radiographies. Conclusion: Given that the radiology staff is indirectly but constantly subjected to ionizing radiation above the standard dose, it is recommended to take preventive measures such as observing an appropriate distance from the radiology room, reinspection of shields, applying protective devices, and monitoring the exposure dose for this group. [ABSTRACT FROM AUTHOR]

In radiation dosimetry, achieving electronic equilibrium is vital for accurate dose measurements in radioprotection. This study investigates the effect of Poly Methyl Methacrylate (PMMA) layers, known by its chemical formula C 5 H 8 O 2 and a density of 1.19 g/cm³ (PNNL, 2011), on electronic equilibrium for the calibration of radiation protection instruments, focusing on photon beams of varying energies. Using DOSIMEX 2.0 simulation software, we modeled the influence of PMMA thickness on calibration factors across different X-ray and gamma-ray beam energies. Experimental validation with Cs-137 and Co-60 sources confirmed the reliability of the simulation. Our results highlight that while PMMA layers have a minimal impact on calibration for higher-energy beams, their role becomes significant for energies below 40 keV. For X-ray beams (From 30 to 140 kV), the results show minimal calibration factor deviation (<1.6%), whereas radionuclide beams exhibit more significant variations (4.1%), necessitating customized calibration approaches. This study underscores the importance of adhering to ISO 4037-3 standards in radioprotection, particularly in low-energy scenarios, to ensure the precision of calibration procedures and optimize radiation protection practices. Furthermore, based on the results obtained, the absence of PMMA does not have a dramatic effect on the calibration of X-ray radiation instruments, whereas for gamma-ray beams, it has a significant impact., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Operational dosimetry solves the problem of implementing the principle of optimizing radiation safety, which is closely related to regulation and justification and implies a realistic achievable reduction in the dose load on a person when using ionizing radiation sources by reducing operating time, increasing the distance to radioactive material and shielding for attenuation of ionization flux. The article describes two ways of determining the thickness of shielding under necessity of making operational decision to protect a person from radionuclide source of known activity or the dose rate created by it. Based on the required multiplicity of its attenuation, which allows determining the number of half attenuation layers in the shield or its thickness, is also dependent on the energy of radiation, emitted by the source.

• A strong correlation between eye lens dose, Hp(3), and surface dose, Hp(0,07). • The personal dosimeter can be used to monitor the eye lens dose. • Consistent results between three interventionalist groups Early 2018, the new eye lens dose limit of 20 mSv per year for occupational exposure to ionising radiation was implemented in the European Union. Dutch guidelines state that monitoring is compulsory above an expected eye lens dose of 15 mSv/year. In this study we propose a method to investigate whether the eye lens dose of interventionalists would exceed 15 mSv/year and to determine if the eye lens dose can be derived from the regular personal dosimeter measurements. The eye lens dose, Hp(3), of interventional radiologists (n = 2), cardiologists (n = 2) and vascular surgeons (n = 3) in the Máxima Medical Centre, The Netherlands, was measured during six months, using thermoluminescence dosimeters on the forehead. Simultaneously, the surface dose, Hp(0,07), and whole body dose, Hp(10), were measured using regular dosimeters outside the lead skirt at chest level. The dosimeters were simultaneously refreshed every four weeks. The eye lens dose was compared to both the body-worn dosimeter values. Measurements were performed in the angiography suite, Cath lab and hybrid OR. A clear relation was observed between the two dosimeters: Hp(3) ≈ 0,25 Hp(0,07). The extrapolated year dose for the eye lens did not exceed 15 mSv for any of the interventionalists (average 3 to 10 studies/month). The eye lens dose can be monitored indirectly through the regular dosimeter at chest level. Additionally, based on the measurements we conclude that all monitored interventionalists remain below the dose limit and compulsory monitoring limit for the eye lens dose. [ABSTRACT FROM AUTHOR]

Proton therapy is a rapidly progressing modality with a significant impact on lung cancer treatment. However, there are concerns about the subsequent effects of secondary radiation in out-of-field organs. Thus, the present study aimed to evaluate the risk of subsequent secondary cancers within non-target organs during proton therapy for lung cancer. A Monte Carlo model of the International Commission on Radiological Protection (ICRP) 110 male phantom was employed to calculate the absorbed dose associated with secondary photons and neutrons within out-of-field organs for different tumor locations. The risk of induced secondary cancers was then estimated using the Biological Effects of Ionizing Radiation Committee (BEIR) VII and National Council on Radiation Protection and Measurements (NCRP) 116 risk models. Organs close to the tumor, such as the heart, esophagus, thymus, and liver, received the highest equivalent doses. The calculated equivalent doses increased as the tumor depth increased from 4–8 cm to 12–16 cm. The contribution of neutrons to the total equivalent dose was dominant (up to 90%) in most of the organs studied. The calculated risks of secondary cancers were higher in the liver and esophagus compared with other organs when using the BEIR risk model. The maximum risk value was obtained for the left lung when the NCRP 116 risk model was used. Furthermore, the estimated risks of secondary malignancies increased with the tumor depth using both risk models. The calculated risks of radiation-induced secondary cancers were relatively lower than the baseline cancer risks. However, extra attention is warranted to minimize subsequent secondary cancers after proton therapy for lung cancer. • Secondary cancer risks related to proton therapy for lung cancer were assessed. • Absorbed doses and secondary cancer risks obtained using Monte Carlo simulations. • BEIR and NCRP risk models also used to assess the risks of developing secondary cancers. • Neutron dose made the dominant contribution in most organs considered. • Risk values obtained for secondary cancers increased as the tumor depth increased. [ABSTRACT FROM AUTHOR]

The coupled ESR and U-series (ESR/U-series) method has been increasingly utilized for dating fossil teeth from Early to Middle Pleistocene hominid sites. One significant advantage of this method is its ability to directly analyze fossil animal or human teeth. However, compared with other radiometric methods such as 14C charcoal dating, U-series carbonate dating, and OSL sediment dating, this dating method is rarely employed for Late Pleistocene or younger sites. In this study, we present an ESR/U-series dating investigation conducted at the Naminan site, a Paleolithic-Neolithic transition (P–N transition) site situated on the Sino-Myanmar border. The ESR/U-series analysis of eleven dental samples yields an age range of 18.1–13.2 ka for the fossils. These obtained ages are generally consistent with the 14C chronology of the site. When dealing with young fossil samples, it was observed that due to relatively low uranium concentration in dental tissues, internal dose rate plays a less significant role compared to external beta and gamma dose rates in the total dose rate of the fossil samples. Consequently, evaluating the dose rate of surrounding sediment becomes a primary source of uncertainty. Additionally, in this study we attempted to employ the standardized growth curve (SGC) and representative dose response curve method for determining Equivalent Dose (D E), which was then compared with values obtained using additive dose method (ADM). Although the precision of D E estimated by two methods are comparatively lower than that of ADM, it demonstrates the potential to efficiently determine a more rational D max for irradiation, identify samples with stratigraphic disturbances, and analyze small or valuable fossil specimens. • Coupled ESR/U-series method was first applied to a P–N transition site in China. • SGC were tested to determine the D E of Late Pleistocene fossil samples. • The fossil ages calculation was independent with different U-models. [ABSTRACT FROM AUTHOR]

The main objectives of this study were to investigate the distribution features of the 210Po in abiotic (water and bottom sediments) and biotic (zooplankton, mollusks, fish) components of the North Crimean Canal (NCC) aquatic ecosystem and adjacent irrigated soils as well as assessment of the doses received by water organisms from α-radiation of absorbed 210Po. The samples were processed using standard radiochemical methods accepted in international practice. The activity of 210Po in the samples was measured using the alpha-spectrometric OCTETE Plus complex (ORTEC-AMETEK, USA). The measurement error did not exceed 20%. Activity concentration of 210Po in the studied objects decreased in the following rank: suspended matter (73.6 Bq/kg d.w.) > soils (32.5 Bq/kg d.w.) ≈ bottom sediments (32.1 Bq/kg d.w.) > mollusks (23.4 Bq/kg w.w.) > fish (6.4 Bq/kg w.w.). The 210Po distribution coefficient (Kd) values in water between suspended matter and its dissolved parts varied within the 1.4 × 104–1.4 × 105 L/kg range. The concentration factors (CF) of 210Po for hydrobionts of the NCC were in the range 103–104 L/kg. The calculated absorbed radiation doses from 210Po alpha radiation for the hydrobionts of the North Crimean Canal were significantly below the recommended dose limits. [ABSTRACT FROM AUTHOR]

Radionuclide therapy with 223Ra-dichloride is used to treat bone metastases and to improve the quality of life of patients with metastatic castration-resistant prostate cancer. At the present time there is no reliable data on the biodistribution of the 223Ra-dichloride in the patient body. The aim of this study was to assess absorbed, equivalent doses in radiosensitive organs and tissues and effective dose from internal exposure for patients with metastatic castration-resistant prostate cancer treated with 223Ra-dichloride. Internal doses from 223Ra-dichloride were calculated for a chamber model specific for patients with metastatic castration-resistant prostate cancer. This model consists of 8 chambers (blood plasma, two chambers describing bone tissue, small intestine, upper large intestine, lower large intestine, feces and the rest of the body). Time-integrated activities were calculated using the SAAM II v2.3 software. The IDAC-Dose 2.1 software was used to calculate the absorbed doses. The highest absorbed doses in organs and equivalent doses were determined for the bone surface and red bone marrow. The absorbed dose from a-radiation in the bone surface for a set of six therapeutic procedures with 223Ra-dichloride was estimated as 1 Gy; in the red bone marrow — 0.14 Gy. However, the approach used does not specifically consider accumulation of the radiopharmaceutical in metastases, which can lead to a significant overestimation of the absorbed dose in the healthy part of the bone surface and red bone marrow.

Most important quality attributes of any radiopharmaceutical (RPh) are its radiochemical purity (RCP) or content of radiochemical impurities (RCIs) that have to comply with respective norms and limits. However, at present, there is no unified approach to validation of analytical methods in the context of highly radioactive samples.The aim of the study was to develop an approach to validation of methods for determination of RCI content in RPhs.Materials and methods: the authors determined the content of RCIs in a radiopharmaceutical formulation containing a complex of technetium-99m and methylenediphosphonic acid by the radiometric method after isolation of impurities from the main compound by thin-layer chromatography using silica gel and methyl ethyl ketone (for sodium pertechnetate determination) and silica gel and 13.6% sodium acetate solution (for determination of hydrolysed reduced technetium-99m). The radioactivity was registered by a chromatogram scanner with a detector of gamma-rays with energies from 0.05 to 1.5 MeV.Results: the paper analyses existing official approaches to validation of analytical procedures and compares them with the results of experimental studies described in available publications. It assesses the validation parameters for compliance with the acceptance criteria set forth in the current regulations and substantiates selectivity of chromatographic determination of impurities under the selected test conditions. Coefficients of variation for repeatability, reproducibility, and accuracy did not exceed 4.5, 2.8, and 8.9%, respectively, given the relative error of not more than 10.5%. The study demonstrated signal linearity for the 10-fold dilution of the standardised sodium pertechnetate solution, it also demonstrated correspondence between the applied and detected radioactivity when performing the test in the impurity content range of 0.5–5%. The validation procedure was associated with significant radiation burden for the personnel of the quality control laboratory.Conclusions: the authors suggested a methodological approach to validation of methods for determination of RCI content in technetium-99m-based RPhs. This approach may be used in the development of a guideline on validation of analytical methods for RCP/RCI determination in RPhs, or for introduction of relevant sections into existing documents.

For the first time in a wide range of energies of protons (from 0.1 to 400 MeV) and electrons (from 0.04 to 7 MeV), using the Spenvis database and software of the European Space Agency, proton and electron fluxes have been calculated in accordance with the operating conditions of the SamSat–ION nanosatellite in a sun-synchronous orbit (SSO). In accordance with the spectral energy characteristics of these fluxes, the ionization and radiation losses have been calculated for radiation shielding glass K-208 and SiO2 and, in addition, the annual absorbed dose has been determined using empirical formulas. The results of computation of the integral fluxes in the radiation shielding glass K-208 and SiO2 of various thicknesses irradiated with protons and electrons in a circular SSO are presented, and the proportion of the particles passed through in the single-layer stack approximation is shown. [ABSTRACT FROM AUTHOR]

Background: Re-irradiation (re-RT) is a technically challenging task for which few standardized approaches exist. This is in part due to the lack of a common platform to assess dose tolerance in relation to toxicity in the re-RT setting. To better address this knowledge gap and provide new tools for studying and developing thresholds for re-RT, we developed a novel algorithm that allows for anatomically accurate three-dimensional mapping of composite biological effective dose (BED) distributions from nominal doses (Gy).Methods: The algorithm was designed to automatically convert nominal dose from prior treatment plans to corresponding BED value maps (voxel size 2.5 mm3 and α/β of 3 for normal tissue, BED3). Following the conversion of each plan to a BED3 dose distribution, deformable registration was used to create a summed composite re-irradiation BED3 plan for each patient who received two treatments. A proof-of-principle analysis was performed on 38 re-irradiation cases of initial stereotactic ablative radiotherapy (SABR) followed by either re-SABR or chemoradiation for isolated locoregional recurrence of early-stage non-small cell lung cancer.Results: Evaluation of the algorithm-generated maps revealed appropriate conversion of physical dose to BED at each voxel. Of 14 patients receiving repeat SABR, there was one case each of grade 3 chest wall pain (7%), pneumonitis (7%), and dyspnea (7%). Of 24 patients undergoing repeat fractionated radiotherapy, grade 3 events were limited to two cases each of pneumonitis and dyspnea (8%). Composite BED3 dosimetry for each patient who experienced grade 2-3 events is provided and may help guide development of precise cumulative dose thresholds for organs at risk in the re-RT setting.Conclusions: This novel algorithm successfully created a voxel-by-voxel composite treatment plan using BED values. This approach may be used to more precisely examine dosimetric predictors of toxicities and to establish more accurate normal tissue constraints for re-irradiation. [ABSTRACT FROM AUTHOR]

Biological modeling for anti-cancer treatments using mathematical models can be very supportive in gaining more insight into dynamic processes responsible for cellular response to treatment, and predicting, evaluating and optimizing therapeutic effects of treatment. This review presents an overview of the current status of biological modeling for hyperthermia in combination with radiotherapy (thermoradiotherapy). Various distinct models have been proposed in the literature, with varying complexity; initially aiming to model the effect of hyperthermia alone, and later on to predict the effect of the combined thermoradiotherapy treatment. Most commonly used models are based on an extension of the linear-quadratic (LQ)-model enabling an easy translation to radiotherapy where the LQ model is widely used. Basic predictions of cell survival have further progressed toward 3 D equivalent dose predictions, i.e., the radiation dose that would be needed without hyperthermia to achieve the same biological effect as the combined thermoradiotherapy treatment. This approach, with the use of temperature-dependent model parameters, allows theoretical evaluation of the effectiveness of different treatment strategies in individual patients, as well as in patient cohorts. This review discusses the significant progress that has been made in biological modeling for hyperthermia combined with radiotherapy. In the future, when adequate temperature-dependent LQ-parameters will be available for a large number of tumor sites and normal tissues, biological modeling can be expected to be of great clinical importance to further optimize combined treatments, optimize clinical protocols and guide further clinical studies. [ABSTRACT FROM AUTHOR]

Abstract Background Treating patients with combinations of drugs that have synergistic effects has become widespread practice in the clinic. Drugs work synergistically when the observed effect of a drug combination is larger than the effect predicted by the reference model. The reference model is a theoretical null model that returns the combined effect of given doses of drugs under the assumption that these drugs do not interact. There is ongoing debate on what it means for drugs to not interact. The controversy transcends mathematical punctuality, as different non-interaction principles result in different reference models. A famous reference model that has been in existence for already a long time is Loewe’s reference model. Loewe’s vision on non-interaction was purely intuitive: two drugs do not interact if all combinations of doses that result in a certain given effect lie on a straight line. Results We show that Loewe’s reference model can be obtained from much more fundamental principles. First, we introduce the new notion of complementary dose. Secondly, we reformulate the existing concept of equivalent dose, whereby our formulation is more general than existing ones. Finally, a very general non-interaction principle is put forward. The proposed non-interaction principle represents a certain interplay between complementary and equivalent doses: drugs are non-interacting if complementarity is preserved under equivalence. It is then shown that Loewe’s reference model naturally follows from these principles by an appropriate choice of complementarity. Conclusions The presented work increases insight into Loewe’s reference model for drug combinations, which is realized by the introduction of a very general non-interaction principle that does not refer to any specific dose-response curve, nor to any property of applicable dose-response curves.

Bu çalışmada arkeolojik kazıyla çıkarılmış polimineral içerikli bir seramik numunenin gömü boyunca çevreden soğurduğu radyasyon dozu (eşdeğer doz) bulunmuştur. Eşdeğer dozun belirlenmesi lüminesans yaş tayini araştırmalarında önemlidir. Kullanılan numune feldispat, kuvars gibi minerallere ayrıştırılmadan polimineral içerikli ve ince tanecik tekniğine uygun olarak hazırlanmıştır. Kullanılan numune için ön ısıtma sıcaklığı deneysel işlemler sonucunda belirlenmiştir. Hazırlanan numune 200 °C’de 12 dk. süreyle ön ısıtmaya tutulmuştur. Jeolojik veya arkeolojik numunelerde eşdeğer dozun belirlenmesi için sıklıkla kullanılan yöntemlerden farklı bir yöntem çalışmamızda ilk defa kullanılmıştır. Çalışmamızda bu yöntemin ayrıntılarından ve gözlenen avantajlarından bahsedilmiştir. Elde edilen eşdeğer doz değerleri 5.17±0.09 ile 7.06±0.29 Gy arasında değişmektedir.

Background: Nowadays ionizing radiation is widely used in medicine, research and industry. In medicine, ionizing radiation is used to diagnose diseases and in high doses to treat diseases such as cancer. Undoubtedly, most exposure to artificial sources is in the field of medical and diagnostic radiology. Therefore, practitioners in the field of diagnostic radiography and patients are exposed to ionizing radiation and its risks. On the other hand, despite the advantages and efficacy of diagnostic radiation in the medical field, overall less attention is paid to optimizing and controlling protection in medical radiation. Therefore, the aim of this study was to evaluate the background ionizing radiation in Ahwaz diagnostic radiography centers. Methods: Ionization radiation levels were measured in and out of each center using gamma spectroscopy (Radiation Alert Inspector-EXP 15109) at a, b, c, d and e radiographic centers within one meter above the Earthchr('39')s surface. Radiation levels within each center were measured at four locations (outside of center, secretary desk, and patient waiting room and behind the radiology room) both in X-ray machine operating and non-operating condition. The obtained data were analyzed by SPSS software. Results: The inside ionization radiation dose in a, b, c, d and e radiographic centers were 0.121, 0.119, 0.126, 0132 and 0.128 μSv/h respectively. The outside ionization radiation dose in a, b, c, d and e radiographic centers were 0.094, 0.092, 0.093, 0.112 and 0.101 μSv/h respectively. Equivalent annual dose within and outside selected radiology centers were lower than the threshold (1 mSv / year). Conclusion: The results show that the ionizing radiation dose of the X-ray equipment examined in the radiology centers of Ahwaz is lower than the global standard.

The standardised growth curves (SGCs) can compensate for the drawbacks of the single-aliquot regenerative-dose (SAR) procedure, such as low utilization of time and instrument in the optically stimulated luminescence (OSL) dating. In this study, 12 sedimentary samples of 6 lakes from the Mongolian Plateau were selected and 90–125 μm coarse-grains quartz was extracted to establish SGCs. The results show that the OSL signals are mainly composed of a fast component, which is applicable for SAR procedure. The difference in the shape of the dose response curves (DRCs) limits the application of the standardised growth curve (SGC) for which the growth curves among the aliquots corrected by the test dose are scattered. The equivalent dose (D e) estimated by the global standardised growth curve (gSGC) by the regenerative normalization (re-normalization) method is more consistent with the full SAR procedure, so the gSGC method is suitable for determining the D e values on the regional scale of Mongolian Plateau. For different lacustrine sedimentary samples, the D e values estimated by full SAR procedure and gSGC method are consistent for the doses of up to ~280 Gy. The discrepancy of growth curves may result from the sensibility changes of inter-cycle in SAR measurement and the recuperation, also we do not exclude the influence of feldspar inclusions. [ABSTRACT FROM AUTHOR]

The International Commission on Radiological Protection (ICRP) has published a report of ICRP Publication 147. This publication has consolidated and expanded the concept of effective dose developed by ICRP. Effective dose has been used as a valuable tool for use in the optimization of protection and retrospective demonstration of compliance for regulatory purpose. The use of equivalent dose should be discontinued to avoid confusion of the same unit of Sievert between effective dose and equivalent dose and to set the limits on organ/tissue doses to prevent tissue reactions. The ICRP has considered effective dose an approximate indicator of possible risk of stochastic effects at low doses below 100 mSv. The estimate of effective dose can be used for comparing medical exposures among different diagnostic modalities including computed tomography and nuclear medicine. However, it is emphasized that use of eflective dose is not substitute for the risk of a specific individual/organ since there is an uncertainty of the risk estimate due to low doses and simplified concept using tissue weighting factors that are averaged across all ages and both genders for hypothetical populations. The present article provides a brief summary and commentary of the key issues on the report. The concept of detriment behind calculation of tissue weighting factors in effective dose is reviewed. [ABSTRACT FROM AUTHOR]