Dosimetric study in intensity-modulated radiotherapy with dissimilar position for cervical cancer / 肿瘤研究与临床

ABSTRACT

Objective To analyze the difference of irradiation dose and volume of organs at risk (OAR) particularly in small intestine between supine position and prone position on intensity-roodulated radiotherapy(IMRT) for cervical cancer. Methods 11 patients with Ⅱ_B-Ⅲ_B cervical cancer were scanned with supine position and prone position by CT.The CT images were transported to TPS,then target volumes were delineated and the IMRT plans were designed respectively.The prescribed dose was 95%PTV receiving 45 Gy in 23 fractions of 2 Gy.The exposure volumes of the OAR at different position and different dose levels in the dose volume histograms (DVH) were compared and analyzed.Results When tlle dose di8tributions met to the clinic request,the exposure volumes of small intestine at prone position were redueed than that at supine position in dose range 46-30 Gy(P<0.05),but this phenomenon Was not distinct in low dose range(< 20 Gy)(P>0.05).The exposure volumes of bladder, rectum, femur head and spine cord were no obviously differences at dissimilar position. Conclusion IMRT of cervical cancer should adopt prone position.because their small intestine will be protected better.