An evaluation of patient dose from cone beam computed tomography system in radiotherapy

This study was carried out at the Akdeniz University School of Medicine by using the Department of Radiation Oncology X-ray Volumetric imager model cone beam computed tomography. The dose determination was done for planar, fluoroscopic and volumetric imaging techniques. Ionization chambers, thermoluminescent dosimeter (TLD) and semi-conductor diodes were used for the measurements in clinical protocols. Computurized tomography dose index (CTDIair) and peak dose were measured in air and also for calculating weighted Computurized tomography dose index (CTDIw) in phantom dose mesurements were performed by different ionization chambers for volumetric imaging technique. For the same techniques, the dose profiles in air were obtained with 2-dimensional ionization chamber assembly and TLDs. The dose measurements by ion chamber and TLDs in an air were compared with each other. Ion chamber measured doses in phantom was compared with the dose values given by the manufacturer's and other studies. The parameters which have an effect on dose values were examined for the kV-CBCT system. This study may be used to determine and manage the patient dose received with kV-CBCT system that is being used in clinics for image-guided radiotherapy (IGRT).