Sresty N V N Madhusudhana, Ramanjappa Thogata, Raju Alluri Krishnam, Muralidhar K R, Sudarshan Gambhir
Department of Radiotherapy, Indo American Cancer Institute and Research Centre, Hyderabad, India.
Brachytherapy. 2010 Jul-Sep;9(3):235-8. doi: 10.1016/j.brachy.2009.05.006. Epub 2010 Jan 29.
Intensity-modulated radiotherapy (IMRT) technique in external beam radiotherapy and interstitial implant brachytherapy (ISBT) play important role in the treatment of head and neck cancers. Both are proved to be highly conformal techniques of radiotherapy. In this study, we investigated whether ISBT can give treatment planning results similar to those of IMRT.
Fifteen patients with tongue cancer treated with interstitial high-dose-rate brachytherapy were replanned. They were evaluated with the IMRT planning system. Contouring of target volume, including all critical structures was done on the IMRT treatment planning system to closely match implant brachytherapy planning system. Treatment plans were generated after specifying the goals in the prescription. Conformity index and dose to critical organ were calculated and compared between IMRT and ISBT. Planning time was also recorded for both the techniques in all the cases.
Very good dose conformity was observed in ISBT, which was almost the same as that in IMRT. Dose to the critical structure was lower in ISBT in all the cases. Planner time was also less in ISBT for more number of cases.
Results show that ISBT treatment modality produces equal or superior planning results when compared with IMRT with our optimization techniques. These results encourage us to continue ISBT practice.
调强放射治疗（IMRT）技术在外照射放疗和组织间插植近距离放疗（ISBT）中对头颈部癌的治疗起着重要作用。两者均被证明是高度适形的放疗技术。在本研究中，我们调查了ISBT能否给出与IMRT相似的治疗计划结果。
对15例接受组织间高剂量率近距离放疗的舌癌患者重新进行计划。使用IMRT计划系统对他们进行评估。在IMRT治疗计划系统上对靶区体积（包括所有关键结构）进行轮廓勾画，以与插植近距离放疗计划系统紧密匹配。在规定处方目标后生成治疗计划。计算并比较IMRT和ISBT之间的适形指数和关键器官剂量。还记录了所有病例中两种技术的计划时间。
ISBT观察到非常好的剂量适形性，几乎与IMRT相同。在所有病例中，ISBT对关键结构的剂量更低。在更多病例中，ISBT的计划时间也更少。
结果表明，与IMRT相比，采用我们的优化技术时，ISBT治疗方式能产生同等或更好的计划结果。这些结果鼓励我们继续开展ISBT实践。
