目的探讨CBCT技术对放疗精度的影响及其应用价值。方法选取头颈部、胸部、腹盆部肿瘤患者,放疗前采用C BC T进行2次(在线校位、离线校位)图像采集,将C BC T扫描图像与C T平扫定位图像匹配,记录并分析匹配结果。结果头颈部摆位误差x(0.02...目的探讨CBCT技术对放疗精度的影响及其应用价值。方法选取头颈部、胸部、腹盆部肿瘤患者,放疗前采用C BC T进行2次(在线校位、离线校位)图像采集,将C BC T扫描图像与C T平扫定位图像匹配,记录并分析匹配结果。结果头颈部摆位误差x(0.02±0.09)cm,y(-0.03±0.08)cm,z(-0.01±0.14)cm,rot(-0.1±0.4)°;胸部摆位误差x(-0.01±0.12)cm,y(-0.02±0.07)cm,z(-0.10±0.20)cm,ro(t-0.1±0.7)°;腹盆部摆位误差x(0.01±0.13)cm,y(-0.03±0.11)cm,z(-0.14±0.34)cm,ro(t0.0±0.5)°.结论治疗前通过C BC T获得扫描图像可以减少分次治疗间的摆位误差,提高放疗摆位精度,实现精确放疗。展开更多
Objective: The purpose of this study was to investigate the impact of intensity modulated radiotherapy (IMRT) on surface doses for brain, abdomen and pelvis deep located tumors treated with 6 MV photon and to evaluate...Objective: The purpose of this study was to investigate the impact of intensity modulated radiotherapy (IMRT) on surface doses for brain, abdomen and pelvis deep located tumors treated with 6 MV photon and to evaluate the skin dose calculation accuracy of the XIO 4.04 treatment planning system. Methods: More investigations for the influences of IMRT on skin doses would increase its applications for many treatment sites. Measuring skin doses in real treatment situations would reduce the uncertainty of skin dose prediction. In this work a pediatric human phantom was covered by a layer of 1 mm bolus at three treatment sites and thermoluminescent dosimeter (TLD) chips were inserted into the bolus at each treatment site before CT scan. Two different treatment plans [three-dimensional conformal radiation therapy (3DCRT) and IMRT] for each treatment sites were performed on XIO 4.04 treatment planning system using superposition algorism. Results: The results showed that the surface doses for 3DCRT were higher than the surface doses in IMRT by 1.6%, 2.5% and 3.2% for brain, abdomen and pelvis sites respectively. There was good agreement between measured and calculated surface doses, where the calculated surface dose was 15.5% for brain tumor calculated with 3DCRT whereas the measured surface dose was 12.1%. For abdomen site the calculated surface dose for IMRT treatment plan was 16.5% whereas the measured surface dose was 12.6%. Conclusion: The skin dose in IMRT for deep seated tumors is lower than that in 3DCRT which is another advantage for the IMRT. The TLD readings showed that the difference between the calculated and measured point dose is negligible. The superposition calculation algorism of the XIO 4.04 treatment planning system modeled the superficial dose well.展开更多
文摘目的探讨CBCT技术对放疗精度的影响及其应用价值。方法选取头颈部、胸部、腹盆部肿瘤患者,放疗前采用C BC T进行2次(在线校位、离线校位)图像采集,将C BC T扫描图像与C T平扫定位图像匹配,记录并分析匹配结果。结果头颈部摆位误差x(0.02±0.09)cm,y(-0.03±0.08)cm,z(-0.01±0.14)cm,rot(-0.1±0.4)°;胸部摆位误差x(-0.01±0.12)cm,y(-0.02±0.07)cm,z(-0.10±0.20)cm,ro(t-0.1±0.7)°;腹盆部摆位误差x(0.01±0.13)cm,y(-0.03±0.11)cm,z(-0.14±0.34)cm,ro(t0.0±0.5)°.结论治疗前通过C BC T获得扫描图像可以减少分次治疗间的摆位误差,提高放疗摆位精度,实现精确放疗。
文摘Objective: The purpose of this study was to investigate the impact of intensity modulated radiotherapy (IMRT) on surface doses for brain, abdomen and pelvis deep located tumors treated with 6 MV photon and to evaluate the skin dose calculation accuracy of the XIO 4.04 treatment planning system. Methods: More investigations for the influences of IMRT on skin doses would increase its applications for many treatment sites. Measuring skin doses in real treatment situations would reduce the uncertainty of skin dose prediction. In this work a pediatric human phantom was covered by a layer of 1 mm bolus at three treatment sites and thermoluminescent dosimeter (TLD) chips were inserted into the bolus at each treatment site before CT scan. Two different treatment plans [three-dimensional conformal radiation therapy (3DCRT) and IMRT] for each treatment sites were performed on XIO 4.04 treatment planning system using superposition algorism. Results: The results showed that the surface doses for 3DCRT were higher than the surface doses in IMRT by 1.6%, 2.5% and 3.2% for brain, abdomen and pelvis sites respectively. There was good agreement between measured and calculated surface doses, where the calculated surface dose was 15.5% for brain tumor calculated with 3DCRT whereas the measured surface dose was 12.1%. For abdomen site the calculated surface dose for IMRT treatment plan was 16.5% whereas the measured surface dose was 12.6%. Conclusion: The skin dose in IMRT for deep seated tumors is lower than that in 3DCRT which is another advantage for the IMRT. The TLD readings showed that the difference between the calculated and measured point dose is negligible. The superposition calculation algorism of the XIO 4.04 treatment planning system modeled the superficial dose well.
