Computed tomography is an important diagnostic tool in emergency conditions in pregnant women; however, its use is associated with fetal exposure to ionizing radiation, as the fetus exhibits heightened radiosensitivity. In the Russian Federation, the introduction of SanPiN 2.6.4115 ‑ 25 mandates that medical institutions maintain records of individual patient radiation doses, including pregnant women. Nevertheless, the requirement for mandatory assessment of fetal absorbed doses remains a matter of debate. Furthermore, there are no clear methodological guidelines for calculating such doses, and available data indicate substantial variation in scanning protocols even within the same institution. Therefore, the evaluation of fetal absorbed doses from computed tomography is a relevant task in radiation protection and clinical practice. Aim is to assess fetal absorbed doses from computed tomography examinations performed in pregnant women in a large medical center. Materials and Methods: A retrospective analysis of 40 computed tomography examinations performed on 35 pregnant patients between 2021 and 2025 was conducted. Fetal absorbed doses were calculated using the Fetal Dose Calculation online tool. Results and Discussion: Fetal absorbed doses ranged from 0 to 8.1 mGy. The lowest values (0–0.09 mGy) were observed for head and paranasal sinus; the maximum fetal absorbed dose (8.1 mGy) was found in a two-phase abdominal computed tomography performed in the third trimester. Elevated fetal doses (2.3–7.1 mGy) were associated with multiphase protocols and scanning of combined anatomical regions. In no case did the dose exceed the threshold values of 30, 50, or 100 mGy. Conclusion: Fetal absorbed doses from clinically indicated computed tomography examinations remained well below the established thresholds. The main dose-determining factors are scan region, scan length, number of phases, and gestational trimester. The results support the feasibility of performing computed tomography at any stage of pregnancy without exceeding the threshold for deterministic effects; however, further studies with larger sample sizes are required.
Publication 134 of the International Commission on Radiological Protection introduces an updated biokinetic model for internal exposure to tritium, which highlights the need to transition to individualized dose assessment based on this model in dosimetric monitoring. The aim of the study was to validate ICRP Publication 134 for estimating inhalation intakes of tritium based on measurements of tritium activity concentration in urine and tritiated water concentration in workplace air. Materials and Methods. Five participants were involved in the study and stayed twice in a tritium work area at a 13-day interval; each stay lasted 6 h. The air temperature and humidity were measured, air condensate samples were collected using a Peltier element, and urine samples were obtained. Urine sampling continued on subsequent days after the exposure. The model validation was performed by comparing model-derived estimates with experimental values of tritium activity concentration in urine and condensate samples under identical HTO intake scenarios. Results and Discussion. The ICRP Publication 134 model provides estimates of HTO inhalation intake comparable to those obtained with the ICRP Publication 56 model; however, within the first 12 h after prolonged tritium intake, Publication 134 more accurately reflects the dynamics of uptake and elimination. For more accurate assessment of tritium intake based on urine samples collected one week or later after exposure, correction for the tritium effective half-life is required. It is easier to perform the correction using the Publication 56 model. The breathing rates assumed in the study for sedentary work (0.54 and 0.39 m[3] /h for men and women, respectively) led to underestimation of intake compared with estimates based on urine data, whereas breathing rates corresponding to light work resulted in intake estimates exceeding those derived from urine measurements. Conclusion: The validation results for the new ICRP tritium model showed that the new model has advantages over the old one only when interpreting urine concentration measurement results obtained in the first 12 hours after the onset of intake, which is extremely important for monitoring accidental intake.
Evaluation of patient doses for the establishment of diagnostic reference levels should be performed using dedicated dose surveys. Objective. To assess patient doses from common radiographic procedures in medical facilities in St-Petersburg and the Leningrad Region. Materials and Methods: Data on standard radiographic protocols were collected from 33 medical facilities in St-Petersburg and 18 medical facilities in the Leningrad Region, covering 137 digital X-ray units in St-Petersburg and 53 digital and 62 analogue X-ray units in the Leningrad Region in 2023-2025 and 2019-2021, respectively. Data were collected for radiography of the skull, chest, cervical, thoracic and lumbosacral spine, abdomen and pelvis in frontal and lateral projections. Effective dose, entrance surface dose and calculated dose-area product were determined for each protocol. Results and Discussion: For all radiographic procedures, differences between minimum and maximum patient doses were pronounced and reached up to two orders of magnitude. Statistically significant differences between regional patient-dose samples were observed only for individual procedures; no differences in effective dose were found between digital X-ray units in St-Petersburg and the Leningrad Region. When digital and analogue X-ray units in the Leningrad Region were compared, a significant difference was observed only for entrance surface dose in posteroanterior chest radiography. Standard patient doses in the present study differed significantly from the results of previous dose surveys, both upwards and downwards, indicating the need for detailed systematic assessment of patient doses. The data obtained may be used to justify numerical values of regional diagnostic reference levels. Conclusion: The study results showed that diagnostic reference levels should be established at the regional level, while pooling samples for digital and analogue X-ray units is acceptable.
Reliable data on embryo/fetus exposure from the most common radiographic procedures are required to substantiate the justification and optimization of radiation protection of pregnant patients. The aim of the study was to estimate fetal absorbed doses and the corresponding radiation risks to the unborn child based on typical radiographic protocols used in medical facilities of St. Petersburg and the Leningrad Region. Materials and Methods: Fetal absorbed doses were modelled using the COnceptus Dose Estimation (CODE) software for standard chest, cervical spine, thoracic spine, lumbosacral spine, pelvic, and abdominal radiographic procedures in frontal and lateral projections. Input data were collected in 33 medical facilities in St. Petersburg and 18 in the Leningrad Region. Radiation risks were estimated based on the median fetal absorbed doses for each procedure and trimester. Results and Discussion: The highest median fetal absorbed doses were in the range of 1–3 mGy per single projection and corresponded to abdominal, pelvic, and lumbosacral spine radiography, i.e. procedures with uterus wholly or partly included in the irradiation field. Differences between minimum and maximum values reached up to two to three orders of magnitude, indicating considerable potential for optimization of radiation protection of pregnant patients. There were no scenarios with the fetal absorbed dose approaching 50 or 100 mGy. Radiation risks for chest and thoracic spine radiography were within the negligible-to-very-low range; for abdominal, lumbosacral spine, and pelvic radiography, risks were higher and corresponded to the low-risk category. Conclusion: The results of the study may be used to support justification of radiographic procedures for pregnant patients, for risk communication with patients and relatives, and for update of the national clinical guidelines.
Bone-seeking[89] Sr ingested to the body of Techa river residents and accumulated in bone tissue. It’s led to active red bone marrow exposure. The aim of this study: to calculate the dose coefficients converting activity from oral intake to the cumulative absorbed dose in red bone marrow for adult men and women. Materials and Methods: The Sr-AG biokinetic model was used to estimate the isotope concentration in the source tissue. After that, the absorbed dose rates in the target tissue were evaluated using dosimetric phantoms described the geometry of media in which radiation transfer is simulated. The result of this modeling is the dose factors converting the specific activity of[89] Sr in bone to the absorbed dose rate in red bone marrow. The phantoms are made according to the original method of stochastic parametric skeleton dosimetry modeling. Their parameters are based on a large number of published measurement results of the characteristics of skeletal bones. The perturbation of these parameters makes it possible to simulate the individual variability of bone morphology to calculate the corresponding uncertainties. Results and Discussion: The dose factors for strontium incorporated in the trabecular bone was 2.33 × 10[-7] and 2.23 × 10[ -7] G/s per Bq/kg for male and female respectively. For the cortical bone dose factors were 0.74 and 0.78 ( × 10[ -7] G/s per Bq/kg) for male and female, respectively. The estimated dose coefficients range from 1.81-4.38 ( × 10[ -9] Gy/Bq) for male and 2.30-5.55 ( × 10[ -9] Gy/Bq) for female. The relative standard dose coefficients uncertainties did not exceed 40 %. Conclusion: The values calculated in the framework of this work can be used to reconstruct doses in order to improve radiogenic risk assessments for the exposed population of the Ural region, as well as the risks associated with the use of radiopharmaceuticals such as strontium chloride.
