Greek dose reference levels in pediatric pelvis computed tomography examinations.

The fact that children do undergo computed tomography (CT) examinations similar to those for adults adults has been a research issue, especially since the former are exposed to greater risk levels (developing stochastic late effects, such as cancer) due to their increased radiosensitivity compared to the latter. In a previous research paper (), the values of dose levels were recorded, analyzed, and compared with the reference values for groups of 0, 1, 5 and 10 y-old children for the regions of head, chest, and abdomen. In this paper, the same age group has been considered for measuring dose levels of the pelvic region. Scanning the pelvic region has been one of the most important CT examination procedures, in which unfortunately part of the lower abdomen region is included without adapting any pediatric protocols. Furthermore, the study determines whether the adjustment of the scanning parameters results in any possible reduction in the radiation dose levels to which the patient is being exposed during the examination. The present work also includes the Greek reference levels for the pelvic CT examination for the 5- and 10-y-old children that have been used for comparison against the European ones.

Dose perturbation in the radiotherapy of breast cancer patients implanted with the Magna-Site: a Monte Carlo study.

External beam radiation therapy (RT) is often offered to breast cancer patients after surgical mastectomy followed by breast reconstruction with silicone implants. In some cases, the RT is administered while the patient is still implanted with a temporary tissue expander including a high-density metallic port, which is expected to affect the planned dose distribution. This work uses Monte Carlo (MC) simulation in order to evaluate the aforementioned effect when the McGhan Style 133 Tissue Expander with the Magna-Site injection port is used. Simulations have been performed on a patient model built using the actual CT images of the patient for two irradiation schemes, involving two tangential photon beams of 6 MV and 18 MV respectively. MC results show that the presence of the Magna-Site within the two irradiation fields leads to an overall reduction of absorbed dose for points lying in the shadow of the metallic port (relative to each of the opposing beams). The relative reduction compared to dose results without the expander in place ranges from 7% to 13% for the 6 MV beam and is around 6% for the 18 MV photon beam. However, in the close vicinity of the metallic port, increased absorbed doses are observed, due to the increase of secondary electrons emerging from the metallic part of the insert.