Radiation protection dosimetry最新文献

Radiation dosimetry and cancer risk estimations are central to virtually all radiation safety applications, optimization, and research. These estimates relate to various exposure situations including planned, existing, and emergency situations. The International Commission on Radiological Protection (ICRP) has developed a new methodology to handle the dosimetry of an acute/single intake of radionuclides. To expand this to a chronic exposure over a lifetime or during shorter periods, Oak Ridge National Laboratory (ORNL) applies a methodology based on the ICRP primary data with additional lifetime population-based radiogenic cancer risk estimations involving age- and gender-specific intake rates and organ specific cancer risk models. The releases of unwanted artificial radionuclides in the environment could have a big impact on society, both locally and globally. Such an exposure may occur over an extended time period, and the derived cancer risk coefficients should reflect that possibility. In the present study, cancer risk coefficients are calculated for the Swedish population for 14C, 137Cs, 90Sr, 131I, and 60Co, for internal exposure through air, food, and water and external exposure from air, water, surface, and soil.

Late radiation-induced kidney toxicity limits molecular radionuclide therapy using radiopharmaceuticals such as 177Lu-octreotate and 177Lu-octreotide. Better kidney protection would allow higher amounts of radiopharmaceutical to be administered. Coadministration of recombinant human alpha-1-microglobulin (rA1M) has been suggested to protect kidneys from exposure from 177Lu-octreotate. Furthermore, early responding biomarkers are needed that identify patients that should or should not receive higher radiopharmaceutical activity. The aim of this study was to evaluate effects of different administration schedules of rA1M in combination with 177Lu-octreotide on urinary levels of retinol-binding protein 4 (RBP4) and creatinine (Cr). Mice received 60 MBq 177Lu-octreotide intravenously, plus none, one, or several rA1M injections. Urinary RBP4 and Cr concentrations were measured after 6-10 weeks. Urinary RBP4 was similar in all groups, but with large individual variations in some groups. RBP4/Cr may be a useful early-responding biomarker. Further investigations are needed to determine effects of long-term kidney protection by rA1M schedules.

131I (iodide) accumulates in the thyroid and may affect thyroid tissue. Mechanisms behind such effects are not known. The aim was to investigate early changes in protein expression in thyroid and plasma from mice injected with 131I as iodide. Female Balb/c nude mice were i.v. injected with 0 or 490 kBq 131I and killed after 24 h. Thyroid and blood samples were collected from each animal. Protein levels were determined by mass spectrometry. Data are available via ProteomeXchange with identifier PXD062861. Altogether, 17 and 20 proteins showed statistically significant altered levels in thyroid gland and plasma, respectively, after 131I exposure. Most of these proteins had decreased and increased levels in thyroid and plasma, respectively. Few of them were previously proposed radiation responsive proteins. Functional annotation suggests impact on haematopoiesis, reduced oxygen levels, and hypothyroidism. The role of CHIA and PGAM2 in radiation-induced response should be further examined, together with identification and validation of biomarkers of 131I exposure.

High energy prices recently have moved nuclear power back into the limelight. The biggest risk of nuclear industry has been large-scale accidents that give rise to ground deposition of long-lived fission products such as 137Cs, notably Chernobyl in 1986 (Ukraine) and Fukushima in 2011 (Japan). In Japan, extensive land remediation of residential areas was carried out at an estimated direct cost between 16 and 41 billion Euros. We have studied a hypothetical radioactive fallout scenario in Sweden and then applied a cost-benefit analysis on remediation of urban land and resettlement of evacuees. Direct costs for remediation of amounts to ⁓100 million Euro/km2 (2020 price levels). For an average city in Sweden the costs related to evacuation and decontamination greatly exceed the potential monetary benefits from averting radiation induced cancers. Thus, based solely on financial factors, it is concluded that an exhaustive evacuation and resettlement is not monetary cost-effective.

The antioxidant α1-microglobulin (A1M) has been suggested as kidney protector during 177Lu-octreotate treatment. The aim of this work was to evaluate apoptotic-related transcript expression in kidney cortex and medulla following injection of 177Lu-octreotate and/or A1M. Mice were injected with 177Lu-octreotate, A1M, or 177Lu-octreotate + A1M. Control groups received PBS or vehicle solution. Animals were killed after 24 hours or 7 d. mRNA was isolated from kidney medulla and cortex. Expression of 84 apoptosis-related genes was assessed by q-PCR. Gene expression profiles in kidney cortex were generally similar in the 177Lu-octreotate and 177Lu-octreotate + A1M groups. This was also seen in kidney medulla at 24 hours, but at 7 d anti-apoptotic response of A1M was observed. Altogether, 177Lu-octreotate exposure induced pro-apoptotic response (e.g. Apaf1, Bax, and Tnfrsf10b genes) in kidney medulla and cortex. A1M co-administration did not inhibit pro-apoptotic response in kidney cortex, while A1M initiated pro-survival mechanisms in kidney medulla.

Thyroid dose estimations after nuclear power plant (NPP) accidents are traditionally based on internal uptake of radioiodine, mainly 131I, either by instrumental measurements of thyroid uptake or by ecological estimations based on geographical dispersion of the radioiodine cloud, demographics, and food habits. However, it has been shown that 134Cs and 137Cs in some cases can be the dominant contributors to the thyroid dose over long time following NPP accidents. Based on an ecological model using Swedish-specific parameters of the radioactive fallout from the Chernobyl accident in 1986, estimations of the protracted (30 years) thyroid absorbed dose were made for the population in northern Sweden (2.2 million inhabitants in 1986). The internal dose contribution was estimated from both the short-lived nuclides-mainly 131I (T½,phys = 8.1 d) in dairy milk and from inhalation-and nuclides with longer half-lives-134Cs (T½,phys = 2.06 y) and 137Cs from aggregate ecological transfer of radiocesium in foodstuff (T½,phys = 30.2 y). The external radiation dose to the thyroid was based on air-borne measurements of the ground deposition of 137Cs, combined with absorbed dose contribution of short-lived radionuclides and with correction for shielding from residential buildings and snow cover. The total thyroid absorbed dose from 1986 to 2015 ranged from 0.06 to 15.5 mGy (mean 2.0 mGy) among subjects in the study population. The calculated mean thyroid absorbed dose the first year was 0.7 mGy, where radioiodine accounted for ~0.3 mGy. The protracted thyroid absorbed dose after 30 years was 0.3 mGy (15%) from 131I, and 1.7 mGy (85%) from internal and external 134Cs and 137Cs taken together. Hence, the estimated mean absorbed dose contribution from radiocesium was higher than for radioiodine (131I) both in the first year and in the consecutive 30 years. Furthermore, the 30-year external absorbed dose (1.2 mGy) dominates over the internal absorbed dose (0.8 mGy) to the thyroid. This finding is of relevance for low-dose exposure epidemiological studies of thyroid cancer which previously have focused solely on radioiodine.

Internal dosimetry of diagnostic nuclear medicine requires biokinetic and anatomical models to estimate the radiation exposure from a radiopharmaceutical. Biokinetic models predict the uptake, turnover, and retention of the radionuclide in organs and tissues, while anatomical models estimate energy absorption from decay using computational phantoms. To make more accurate predictions of biokinetic transfer, the International Commission on Radiological Protection (ICRP) has introduced a new compartmental framework, based on a systemic blood model, which can be used to estimate the transfer of the administered radionuclides between organs and tissues. The ICRP Task Group 36 (TG-36) is developing the biokinetic models and dosimetric calculations for radiopharmaceuticals for the ICRP. IDAC-BioDose integrates compartmental modeling and IDAC-Dose2.2. For the biokinetic predictions, transfer rates are generated through empirical data by curve fitting. IDAC-BioDose is benchmarked with SAAMII and DCAL and is used by ICRP TG-36 to revise the biokinetics and dosimetry for ICRP Publ. 128. This comprehensive software expedites absorbed dose and effective dose assessments in the field of diagnostic nuclear medicine.

This study assessed the radiological risk of wood fuels and their ashes in Austria, including wood chips, logs, pellets, and briquettes. Commercially purchased wood fuels are often of unknown origin and may have been imported. 137Cs activity concentrations were measured in wood fuels (69 samples) and their ashes (27 samples) using gamma-ray spectrometers with high-purity germanium detectors. 90Sr analyses were performed on 12 ash samples after chemical separation using PerkinElmer 1220 Quantulus™ liquid scintillation counters. Results showed 137Cs activity concentrations ranging from 0.327 to 8.36 Bq kg-1 in wood fuels (average 2.1 Bq kg-1) and from 11.80 to 867 Bq kg-1 in ashes (average 310 Bq kg-1). The 90Sr activity concentrations in ashes ranged from 363 to 1200 Bq kg-1 (average 655 Bq kg-1). Summarizing, this study suggests that wood fuels currently available in Austria do not pose a significant radiological risk from their ashes, negating the need for import regulations.

In this study, NaCl pellets read with optically stimulated luminescence were evaluated for their potential use as a point dosemeter in breast x-ray imaging. Dosimetry with NaCl pellets has previously been applied to various environmental and medical settings. NaCl pellets have potential in clinical breast dosimetry because they can enable multiple point measurements to be simultaneously conducted in a cost- and time-efficient manner. Using two digital mammography imaging systems, the air kerma response of the NaCl pellets for a standard breast setup was investigated. The air kerma response was observed to be linear, and mathematical fits were successfully used to estimate the cumulative incident air kerma during digital breast tomosynthesis. Deviations from a reference digital dosemeter were 6% and 8% for the two mammography systems, respectively. Measurements conducted at different angles of exposure showed that the NaCl pellets had no angular dependency in the range ± 15°. Finally, the uniformity of the beams was confirmed to avoid possible errors due to the uncertainty of the dosemeters' positions in the exposure field.