Arc CHECK在乳腺癌螺旋断层放疗计划剂量验证中的应用

Irradiation Dose Verification by Arc CHECK on Breast Therapy Cancer Tomotherapy

目的:探讨Arc CHECK旋转调强剂量验证系统在乳腺癌螺旋断层放疗(Helical Tomotherapy,HT)计划剂量验证中的应用可行性。方法:将20例乳腺癌HT计划移植到Arc CHECK系统进行调强放射治疗(Intensity Modulated Radiotherapy,IMRT)计划剂量验证,得到的验证结果与HT计划在其模体中计算获得的平面剂量分布进行比较。剂量验证结果分析采用Gamma分析法,并采用多种标准进行评估。结果:20例乳腺癌病例在阈值水平(Threshold,TH)为10%,3%/3 mm、3%/4 mm、3%/5 mm的γ通过率超过90%的病例数分别占总例数的40%、55%、80%;TH水平为15%,3%/3 mm、3%/4 mm、3%/5 mm的γ通过率超过90%的比例分别为40%、55%、85%,TH水平为20%,3%/3 mm、3%/4mm、3%/5 mm的γ通过率超过90%的比例分别为40%、60%、85%。当评估标准为5%/5 mm时,γ通过率超过90%的比例为100%。靶区剂量均匀性指数(HI),瘤床的同步追量,靶区边界内缩至皮缘下及淋巴结情况对γ通过率无影响(P>0.05)。模体中心偏离x负方向大于4 cm的11例病例中,仅有2例验证结果达到3%/3 mm(TH=10),比例为18%;模体中心偏离x正方向大于4 cm的9例病例中,有6例验证结果达到3%/3 mm(TH=10),比例为66.7%。结论:Arc CHECK旋转调强验证系统可用于乳腺癌HT计划剂量验证,有效地简化了HT剂量验证的流程,但验证模体中心与机器等中心偏移关系对验证通过率的影响仍需配合第三方验证系统作进一步研究。

Objective To discuss the clinical application of Arc CHECK on the breast irradiation dose verification using Helical TomoTherapy. Methods A total of 20 patients with breast tumor were selected, whose irradiation plan were transplant to the Arc check phantom for the IMRT dose verification. The measured dose distributed on the corresponding plans were compared with those calculated by the treatment planning system （TPS）. Based on several different Gamma criteria, the Gamma analysis method was utilized to evaluate the dose verification. Results The γ pass rate of 20 breast irradiation dose verification with Arc check in threshold level （threshold, TH） of 10%, the 7 pass rate with criteria 3%/3 mm, 3%/4 mm, 3%/5 mm were 40% （case of the total number）, 55%, 80%, respectively. Threshold level （threshold, TH） of 15%, the 7 pass rate with criteria 3%/3 mm, 3%/4 mm, 3%/5 mm were 40%（case of the total number） ,55% ,85%, respectively. Threshold level of 10%, the γ pass rate with crite- ria 3%/3mm, 3%/4 mm, 3%/5 mm were 40%, 60%, 85%, respectively. Threshold level of 10%, the γ pass rate with criteria 5% /5 mm, all plans were reached 90%. Target dose homogeneity index （HI）, synchronous integrated boost （SIB）, target area with- in the boundaries to skin edge and lymph nodes has no effect on V rate （P〉0.05）. Phantom center deviates from the negative di- rection is greater than 4 cm in 11 cases, only two cases to verify the results reached 3%/3 mm（TH=10）, the proportion was 18%; phantom center deviation is greater than the positive direction 4 cm in 9 cases, there are six cases of the verification result reach 3%/3 mm （TH=10）, the ratio was 66.7%. Conclusion Arc check rotating intensity-modulated authentication system can be used for breast cancer HT planned dose verification and effectively simplify the procedure of HT dose verification, but the phantom center and the machine center offset to the influence of the pass rate still need to cooperate with the third party authentication system for further study.