Image Guided Radiotherapy (IGRT) Comparison between Cone Beam CT and Ultrasound System for Prostate Cancer

The aim of this study is to evaluate two different Image Guided RadioTherapy (IGRT) methods during 38 fractions of one prostate cancer patient's treatment. Prostate cancer patient was scanned 3.0mm width by Siemens Biograph mCT and Elekta Clarity® Ultrasound system with transabdominal probe. Critical organs and targets were determined from fusion of these images on the CT data set. Volumetric modulated arc therapy (VMAT) planning were performed by using Monaco 5.1® treatment planning system. Reference images of CT scan and ultrasound images were sent to Elekta Versa HD® linear accelerator's treatment system. Before the prostate cancer patient's treatment, we had scanned prostate localization by Elekta Clarity® Ultrasound system. Then we compared ultrasound images with reference images and we adjusted position of couch. For checking the localization of prostate, we scanned patient by XVI 4.5 Cone Beam CT system and we determined the difference between Ultrasound scan and Cone Beam CT scan an average 2.8±1.6mm lateral direction, 2.9±1.1mm longitudinal direction and 2.6±1.4mm vertical direction during 38 fractions of treatment. The results show that comparison between Clarity® Ultrasound system and Cone Beam CT system less than 3.0mm in three directions. Therefore, we are treating prostate cancer patient with ultrasound IGRT method instead of Cone Beam CT scan method in our clinic.