CBCT image guided radiation therapy clinical application / 中国医学装备

ABSTRACT

Objective:Study the effect about cone beam CT(CBCT) image guidance sytem to improve the positioning accuracy and reducing the set-up uncertainty in precise radiotherapy. Methods:Use CBCT system to scan head and neck tumors patients (30 cases) and chest tumor patients (40 cases), including head and neck tumor patients were scaned 90 times, chest tumor patients were scaned 113 times. Setup deviation statistics about anterior and posterior, head and feet, left and right direction. Results:The patients with head and neck cancer, the maximum error of anterior-posterior is 6mm, Three directions errors which greater than 3mm all less than 10%. Patients with chest tumor position error are in the head and foot direction, greater than 5 mm up to 21.51%. Before and after the direction of the error did not exceed 5mm. The left and right direction greater than 5 mm up to 4.53%. Conclusion:It greatly enhances the precision of radiotherapy, improved the curative effect of radiotherapy by using CBCT online image guidance system for the patient position correction. Compared with EPID, patients scaned with CBCT absorb smaller cumulative dose, the image resolution is higher, image matching is more accurate. But compared with the ordinary helical CT,the resolution and scanning range also need to improve.