Application of infrared positioning system in the placement and verification of radiotherapy for prostate cancer

QIU Teng; ZHAO Di; SONG Wei; QIN Liang; ZANG Yueru; WANG Pei; YU Dahai

doi:10.3969/j.issn.1009-0460.2018.03.013

Abstract：Objective To explore whether the infrared positioning system (OPS) can be used to monitor and calibrate the daily placement of radiotherapy for prostate cancer. Methods Twenty patients with prostate cancer were divided into two groups. OPS was used in the experimental group, and OPS was not used in the control group. The images of the radiotherapy target were obtained by kilovoltage cone-beam computed tomography (CBCT), and the error of X (left-right), Y (superior-inferior) and Z (anterior-posterior) were obtained by matching the image with the planned image. Then the data of two groups were compared, and acute radiation adverse reactions were recorded. Results The set-up errors in the three directions of X, Y and Z in the experimental group were (1.1±0.9) mm, (2.9±1.2) mm, and (1.1±0.8) mm, respectively, which were smaller than mm, (6.4±2.3) mm, (2.8±1.5) mm in the control group, and the difference was statistically significant (P＜0.05). The proportion of grade acute intestinal mucosal reaction and urinary system reaction in the experimental group was 40.0％ (4/10) and 30.0％ (3/10), respectively, which was significantly less than 70.0％ (7/10) and 60.0％ (6/10) in the control group. The values of PTV margin (MPTV) of the experimental group in X, Y and Z were 4.3 mm, 5.3 mm and 3.9 mm, respectively. The MPTV values of the control group in X, Y and Z were 6.1 mm, 9.1 mm and 6.4 mm, respectively. Conclusion The introduction of infrared fixed ball can increase the accuracy of placement and reduce the placement error in radiotherapy, so as to improve the accuracy of radiotherapy for prostate cancer patients and improve the clinical efficacy of radiotherapy.