Background. Patient positioning errors in pelvic radiotherapy at Department of Oncology and Radiotherapy in Osijek are explored in order to establish the offline setup correction protocol and determine the safety margins. Material and methods. Film portal imaging is used during the whole treatment in order to find patient positioning errors. Eleven patients are included in the study and 420 images are analyzed. Setup errors are found by measuring distances between the center of the field and bony landmarks. Systematic and random errors are analyzed. Results. Safety margins that should be employed at our department are 11 mm, 13 mm and 14 mm in mediolateral, craniocaudal and anteroposterior direction, respectively. Time trend is found only in an aged, obese patient with a hip problem. No action level offline setup protocol was employed by taking and averaging first four images in mediolateral and craniocaudal and 5 images in anteroposterior direction. Conclusions. Since time trend is found only in a patient who was hard to position because of his age, obesity and the hip problem, we decided that such patients are to be positioned without a bellyboard and in supine position. Time trends are not found in all of the other patients so we employed the offline setup error protocol by averaging setup errors from the first few consecutive images. Safety margins that will ensure 90% probability of depositing at least 95% of the prescribed dose in the target are calculated. Safety margins and number of images that should be taken showed that the most inaccurate positioning was in the anteroposterior direction.

This paper aims to describe the photon beam characteristics in terms of energy and angular distribution during breast megavoltage photon radiotherapy of pregnant patients. Photon beam characteristics are investigated at treatment volume (breast) and the position of the fetus in the Tena phantom using Monte Carlo simulation. Photon beam energy spectra are compared across various materials used as substitutes for constructing physical and computational phantoms. Mean energies calculated in substitute materials developed by our group and used to build the Tena phantom, differ up to 10 % from the calculated ones in ICRU reference tissue materials. It was found acceptable since this is less than the differences between ICRP and ICRU materials. Then, the photon beam characteristics are investigated in the anthropomorphic phantom, Tena. Photon beam mean energy in the fetal region of the phantom (out-of-field) is significantly lower (more than 1 MeV) than at the breast position (in-field). The angular distribution of the photon beam at the breast position predominantly shows a forward direction, whereas, at the fetus position, the distribution is more scattered. When selecting a detector, it is crucial to consider the differences in photon energy and angular distributions between in-field and out-of-field measurement points to reduce measurement uncertainties and ensure reliable data.

The diagnosis of emergent conditions during pregnancy can be delayed due to insufficient knowledge of fetal radiation doses in different imaging modalities. The aim of this article is to investigate the ranges of fetal doses in most common diagnostic and interventional radiology procedures. Procedures were carried out on an anthropomorphic phantom, Tena, representing a pregnant woman in the 18th week of pregnancy with the fetus in breech position. Different clinical scenarios using computer tomography (CT), radiography, fluoroscopy and digital subtraction angiography were selected in three teaching hospitals. Measurements were performed using radiophotoluminescent glass dosimeters placed in dedicated holes in the fetal head and fetal body. Measured fetal doses were below 1 mGy when the fetus was not in the primary beam. The highest fetal doses, up to 47 mGy, were measured after a CT scan for polytrauma and up to 24 mGy after a CT scan of the abdomen and pelvis. Significant variability in fetal doses for the same procedure was found between different hospitals but within the same hospital also. All obtained results are below the threshold for deterministic effects given by the International Commission for Radiation Protection but can be reached with two or more imaging procedures employed. The variability in fetal doses for the same procedures highlights the need for the improved optimization of imaging protocols.

This study aimed to identify the methods currently used to evaluate fetal dose in pregnant patients undergoing radiotherapy, the strategies implemented to optimize fetal exposure, and the fetal dose ranges reported in the literature. A systematic review was conducted and complemented by a survey. Data related to fetal-dose assessment, optimization approaches, and reported fetal-dose levels were extracted and analyzed. Seventy-eight studies were included in the systematic review, and twelve clinical cases were collected through the survey. In the literature, fetal-dose evaluation most frequently relied on measurements performed in anthropomorphic phantoms using passive dosimeters and ionization chambers. Among published clinical case reports, in-vivo dosimetry was commonly implemented to monitor fetal exposure. Several strategies were found to substantially reduce fetal dose, including the use of shielding blocks, flattening-filter-free beam modes instead of flattened beams, and collimator-angle optimization. Overall, most estimated fetal doses were well below 100 mGy, regardless of tumor site or treatment technique. The lowest fetal doses were reported with proton pencil beam scanning, while optimized IMRT and VMAT plans achieved fetal exposures comparable to those obtained with 3DCRT. This systematic review and survey provide a comprehensive overview of current fetal-dose assessment methods and optimization strategies in radiotherapy. The lack of up-to-date recommendations adapted to modern radiotherapy highlight the need for practical guidance. As part of the SONORA project, the development of a dedicated leaflet will support medical physicists by providing structured, practical recommendations to ensure safer and more consistent management of radiotherapy during pregnancy.