目的:本研究的目的是比较不同光子束能量和弧数对宫颈癌治疗的剂量学影响。
背景:宫颈癌是全球女性常见的癌症,发病率高。放射疗法用于治疗此类肿瘤。体积调制电弧治疗(VMAT)被认为优于具有多个电弧和能量的其他技术。
方法:在我们研究所进行的一项前瞻性观察研究中,20例宫颈癌患者接受了放疗。6MV的体积调制弧形计划,使用单弧(SA)和双弧(DA)产生10MV和15MV光子能量。规划目标体积(PTV)的几个物理指标,如V95%、V100%,V110%,D98%,D50%,比较D2%和MU总数。分析正常组织完整剂量(NTID)和对壳结构PHY2.5和PHY5.0的剂量。
结果:对于所有的能量和弧,观察到与PTV相当的剂量覆盖。DA6MV的CI(1.095)优于SA6MV(1.127),SA10MV(1.116)和SA15MV(1.116)。评估的参数显示OAR剂量显著减少。DA6MV的平均膀胱剂量(41.90Gy)优于SA6MV(42.48Gy),SA10MV(42.08Gy)和SA15MV(41.93Gy)。同样,计算的平均直肠剂量的p值为0.001(SA6vs15),0.013(DA6vs10)和0.003(DA6vs15),随后偏爱DA6MV。NTID的差异非常小。
结论:研究表明,高能量没有更大的优势,具有6MV光子能量的DAVMAT计划是宫颈癌治疗的不错选择,因为它提供了高度均匀和适形的计划,具有出色的目标覆盖率和更好的OAR保留。
OBJECTIVE: Aim of the present
study was to compare the dosimetric impact of different photon beam energies and number of arcs in the treatment of carcinoma cervix.
BACKGROUND: Carcinoma cervix is a common cancer in women worldwide with a high morbidity rate. Radiotherapy is used to treat such tumours. Volumetric Modulated Arc Therapy (VMAT) is considered superior to other techniques with multiple arcs and energies.
METHODS: Twenty patients with carcinoma cervix underwent radiotherapy in a prospective observation
study conducted at our institute. Volumetric modulated arc plans with 6 MV, 10 MV and 15 MV photon energies using single arc (SA) and dual arc (DA) were generated. Several physical indices for planning target volume (PTV) like V95%, V100%, V110%, D98%, D50%, D2% and total number of MUs were compared. Normal Tissue Integral Dose (NTID) and dose to a shell structure PHY2.5 and PHY5.0 were analyzed.
RESULTS: Comparable dose coverage to PTV was observed for all the energies and arcs. CI for DA6MV (1.095) was better than SA6MV (1.127), SA10MV (1.116) and SA15MV (1.116). Evaluated parameters showed significant reduction in OAR doses. Mean bladder dose for DA6MV (41.90 Gy) was better than SA6MV (42.48 Gy), SA10MV (42.08 Gy) and SA15MV (41.93 Gy). Similarly, p-value for the mean rectal dose calculated was 0.001 (SA6 vs 15), 0.013 (DA6 vs 10) and 0.003 (DA6 vs 15) and subsequently favoured DA6MV. Difference in NTID was very small.
CONCLUSIONS: The
study showed no greater advantage of higher energy, and DA VMAT plan with 6 MV photon energy was a good choice of treatment for carcinoma cervix as it delivered a highly homogeneous and conformal plan with superior target coverage and better OAR sparing.