Study of variation in dose calculation accuracy between kV cone-beam computed tomography and kV fan-Beam computed tomography

Venkatesan Kaliyaperumal, C Jomon Raphael, K Mathew Varghese, Paul Gopu, S Sivakumar, Minu Boban, N Arunai Nambi Raj, K Senthilnathan, P Ramesh BabuJournal of Medical Physics 2017 42(3):171-180 Cone-beam computed tomography (CBCT) images are presently used for geometric verification for daily patient positioning. In this work, we have compared the images of CBCT with the images of conventional fan beam CT (FBCT) in terms of image quality and Hounsfield units (HUs). We also compared the dose calculated using CBCT with that of FBCT. Homogenous RW3 plates and Catphan phantom were scanned by FBCT and CBCT. In RW3 and Catphan phantom, percentage depth dose (PDD), profiles, isodose distributions (for intensity modulated radiotherapy plans), and calculated dose volume histograms were compared. The HU difference was within ± 20 HU (central region) and ± 30 HU (peripheral region) for homogeneous RW3 plates. In the Catphan phantom, the difference in HU was ± 20 HU in the central area and peripheral areas. The HU differences were within ± 30 HU for all HU ranges starting from −1000 to 990 in phantom and patient images. In treatment plans done with simple symmetric and asymmetric fields, dose difference (DD) between CBCT plan and FBCT plan was within 1.2% for both phantoms. In intensity modulated radiotherapy (IMRT) treatment plans, for different target volumes, the difference was <2%. This fea...
Source: Journal of Medical Physics - Category: Physics Authors: Source Type: research