Vanetti Eugenio, Clivio Alessandro, Nicolini Giorgia, Fogliata Antonella, Ghosh-Laskar Sarbani, Agarwal Jai Prakash, Upreti Ritu Raj, Budrukkar Ashwini, Murthy Vedang, Deshpande Deepak Dattatray, Shrivastava Shyam Kishore, Dinshaw Ketayun Ardeshir, Cozzi Luca
Oncology Institute of Southern Switzerland, Radiation Oncology Department, Bellinzona, Switzerland.
Radiother Oncol. 2009 Jul;92(1):111-7. doi: 10.1016/j.radonc.2008.12.008. Epub 2009 Jan 20.
A planning study was performed to evaluate the performance of volumetric modulated arc radiotherapy on head and neck cancer patients. Conventional fixed field IMRT was used as a benchmark.
CT datasets of 29 patients with squamous cell carcinoma of the oro-pharynx, hypo-pharynx and larynx were included. Plans for fixed beam IMRT, single (RA1) and double (RA2) modulated arcs with the RapidArc technique were optimised. Dose prescription was set to 66 Gy to the primary tumour (at 2.2 Gy/fraction), 60 Gy to intermediate-risk nodes and 54 Gy to low-risk nodal levels. The planning objectives for PTV were minimum dose >95%, and maximum dose <107%. Maximum dose to spinal cord was limited to 46 Gy, maximum to brain stem to 50 Gy. For parotids, mean dose <26 Gy (or median <30 Gy) was assumed as the objective. The MU and delivery time were scored to measure expected treatment efficiency.
Target coverage and homogeneity results improved with RA2 plans compared to both RA1 and IMRT. All the techniques fulfilled the objectives on maximum dose, while small deviations were observed on minimum dose for PTV. The conformity index (CI(95%)) was 1.7+/-0.2 for all the three techniques. RA2 allowed a reduction of D(2%) to spinal cord of approximately 3 Gy compared to IMRT (RA1 D(2%) increased it of approximately 1 Gy). On brain stem, D(2%) was reduced from 12 Gy (RA1 vs. IMRT) to 13.5 Gy (RA2 vs. IMRT). The mean dose to ipsi-lateral parotids was reduced from 40 Gy (IMRT) to 36.2 Gy (RA1) and 34.4 Gy (RA2). The mean dose to the contra-lateral gland ranged from 32.6 Gy (IMRT) to 30.9 Gy (RA1) and 28.2 Gy (RA2).
RapidArc was investigated for head and neck cancer. RA1 and RA2 showed some improvements in organs at risk and healthy tissue sparing, while only RA2 offered improved target coverage with respect to conventional IMRT.
开展一项规划研究，以评估容积调强弧形放疗对头颈部癌患者的治疗效果。将传统的固定野调强放疗作为对照。
纳入29例口咽、下咽和喉鳞状细胞癌患者的CT数据集。对固定野调强放疗、采用RapidArc技术的单弧（RA1）和双弧（RA2）调强弧形放疗计划进行优化。处方剂量设定为：原发肿瘤66 Gy（2.2 Gy/分次），中危淋巴结60 Gy，低危淋巴结水平54 Gy。计划靶区（PTV）的规划目标为最小剂量>95%，最大剂量<107%。脊髓的最大剂量限制为46 Gy，脑干的最大剂量限制为50 Gy。对于腮腺，目标设定为平均剂量<26 Gy（或中位数<30 Gy）。记录机器跳数（MU）和照射时间，以评估预期的治疗效率。
与RA1和调强放疗相比，RA2计划的靶区覆盖和均匀性结果有所改善。所有技术均满足最大剂量目标，而PTV的最小剂量存在小偏差。三种技术的适形指数（CI(95%)）均为1.7±0.2。与调强放疗相比，RA2使脊髓的D(2%)降低约3 Gy（RA1使脊髓的D(2%)增加约1 Gy）。对于脑干，D(2%)从12 Gy（RA1与调强放疗相比）降至13.5 Gy（RA2与调强放疗相比）。患侧腮腺的平均剂量从40 Gy（调强放疗）降至36.2 Gy（RA1）和34.4 Gy（RA2）。对侧腮腺的平均剂量范围为32.6 Gy（调强放疗）至30.9 Gy（RA1）和28.2 Gy（RA2）。
对头颈部癌进行了RapidArc技术研究。RA1和RA2在危及器官和保护健康组织方面有一定改善，而只有RA2相对于传统调强放疗能改善靶区覆盖。
