CT parameter change and radiation dose effect for metastatic patients treated with palliative radiotherapy

Objective: The aim of the present study was to determine the methods to reduce the radiation dose during imaging carried out for patients with bone or other organ metastases who were treated with palliative radiotherapy. In planning stages of treatment for these patients, tomographic imaging with computed tomography (CT) is performed on affected area using three-dimensional (3D) conformal radiotherapy. To what level the radiation dose could be lowered in imaging was investigated via changing the parameters used in CT scanning. Method: Twenty seven patients with metastases treated in the Radiation Oncology department (16M, 11F, mean age 65.2 ± 11.9 years) were included in the study. These patients underwent a total of 30 palliative radiotherapy treatments. Standard CT dose of 72 milli-ampere-second (mAs) and 130 peak kilo voltage (kVp) in CT 1 scanning carried out for radiotherapy planning was lowered to 30mAs and 130kVp in CT 2 scanning. Results: Radiation dose was reduced by 62.68% ± 0.02 percent as a result of changes made in planning CT scan (p<0.0001). Analysis of the images obtained revealed that despite the minimal reduction in image quality, results had no effect on treatment planning. Conclusions: It was concluded that the radiation dose could be reduced via making changes in the parameters of CT scanning during palliative radiotherapy planning stage