| dc.description.abstract | Computed Tomography (CT) plays a crucial role in radiotherapy treatment planning. The
optimization of radiation dose to patient during CT simulation is not a matter of concern
so far in most of the countries but it cannot be since even after the primary cancer is
treated, patient may have a long-life expectancy. The additional imaging doses should be
as low as reasonably achievable. Therefore, this study aimed to evaluate radiation dose to
patients during CT simulation for radiotherapy treatment planning. A total of 350 patient
data were collected from October 2022 to November 2022 with the Toshiba Aquilion
large bore CT scanner at Apeksha Hospital, Maharagama, Sri Lanka. The study focused
on commonly performed simulations for di erent protocols (abdomen, chest, head and
pelvis) and used Computed Tomography Dose Index (CTDI) and Dose-Length Product
(DLP) parameters to establish Diagnostic Reference Levels (DRLs). Analysing the data
for descriptive statistics and the 25th, 50th, and 75th quartiles of the dose metrics were
calculated using SPSS software. According to the recommendation of the International
Commission on Radiological Protection (ICRP), the DRL values are de ned as the median
(50th percentile) of the CTDI volume and DLP values. The established typical values of
CTDI volume and DLP respectively are 7.4 mGy, 394 mGy.cm for abdomen; 15.5 mGy, 455
mGy.cm for chest; 58.2 mGy, 2632 mGy.cm for head; 9.3 mGy, 339 mGy.cm for pelvis.
The developed DRL values were relatively lower for most anatomical regions compared to
other countries and institutions, except for the chest region where the values were higher.
Further evaluation is needed to assess the appropriateness of these lower DRL values in
ensuring patient safety and minimizing radiation exposure during CT simulation procedures
for radiotherapy. The study emphasizes the importance of optimizing radiation
dose to patients, considering their potential long-term life expectancy even after primary
cancer treatment. | en_US |
