Alva Ram Charith, Koushik A S Kirthi, Sweta B, Janaki M G, Ponni T R Arul, Kumar Mohan, Yuvaraj B, Revath T
Department of Radiation Oncology, Ramaiah Medical College, Bangalore, India.
Physicist in the Department of Radiation Oncology, Ramaiah Medical College, Bangalore, India.
Indian J Surg Oncol. 2020 Sep;11(3):406-411. doi: 10.1007/s13193-020-01075-w. Epub 2020 Apr 30.
Head and neck cancer treatment includes a multidisciplinary approach involving all specialties. Surgery and radiotherapy are equally effective in controlling small tumors. Intensity-modulated radiotherapy (IMRT) and interstitial brachytherapy (ISBT) play an important role in the treatment of head and neck cancers. Both are proved to be highly conformal techniques of radiotherapy. Our aim is to compare dosimetric aspects of ISBT alone, IMRT alone, and IMRT combined with ISBT in early stage node negative oral cavity cancer. Ten cases of histopathologically proven early stage node negative oral cavity cancer were treated with external beam therapy followed by interstitial brachytherapy boost or ISBT alone. All these patients had undergone computerized tomography (CT) planning for brachytherapy. Retrospectively, these images were utilized, and three sets of plans were done for each patient's CT image set. Group A was IMRT alone plans, groups B had combined IMRT with ISBT boost, and group C was ISBT alone plans. Dosimetric details such as target coverage, dose to critical organs, and conformity index were compared between the three sets of plans. The mean values of the doses to the critical organs with IMRT alone and IMRT with ISBT boost were brainstem 10.40 Gy and 9.20 Gy, spinal cord 19.20 Gy and 16.10 Gy, mandible 62.99 Gy and 66.50 Gy, and I/L and C/L parotids were 6.03 Gy and 5.50 Gy and 5.70 Gy and 5.10 Gy where as in ISBT alone plans mean values were brainstem 1.30 Gy, spinal cord 1.40 Gy, mandible 36.50 Gy, I/L, and C/L parotids were 1.60 Gy and 1.00 Gy. Conformity index (CI) between IMRT and ISBT plans were 0.8580 and 0.7140 respectively. With comparable CI values, doses to critical organs appear to be in favor of ISBT plans as opposed to IMRT, and this was found to be statistically significant. Brachytherapy shows a dosimetric advantage over IMRT in this setting and could be translated to a benefit in terms of toxicities, organ preservation, and cosmesis in the actual clinical scenario. However, whether this would translate to significant benefit in terms of clinical outcome needs to be still verified.
头颈癌治疗采用多学科方法，涉及所有专业领域。手术和放射治疗在控制小肿瘤方面同样有效。调强放射治疗（IMRT）和组织间近距离放射治疗（ISBT）在头颈癌治疗中发挥着重要作用。两者均被证明是高度适形的放射治疗技术。我们的目的是比较单纯ISBT、单纯IMRT以及IMRT联合ISBT在早期无淋巴结转移口腔癌中的剂量学情况。10例经组织病理学证实的早期无淋巴结转移口腔癌患者接受了外照射治疗，随后进行组织间近距离放射治疗加强或单纯ISBT治疗。所有这些患者均接受了用于近距离放射治疗的计算机断层扫描（CT）规划。回顾性地利用这些图像，为每位患者的CT图像集制定了三组计划。A组为单纯IMRT计划，B组为IMRT联合ISBT加强，C组为单纯ISBT计划。比较了三组计划之间的剂量学细节，如靶区覆盖、关键器官剂量和适形指数。单纯IMRT和IMRT联合ISBT加强时关键器官的平均剂量值分别为：脑干10.40 Gy和9.20 Gy，脊髓19.20 Gy和16.10 Gy，下颌骨62.99 Gy和66.50 Gy，双侧腮腺分别为6.03 Gy和5.50 Gy以及5.70 Gy和5.10 Gy；而单纯ISBT计划的平均剂量值分别为：脑干1.30 Gy，脊髓1.40 Gy，下颌骨36.50 Gy，双侧腮腺分别为1.60 Gy和1.00 Gy。IMRT和ISBT计划的适形指数（CI）分别为0.8580和0.7140。在CI值相当的情况下，关键器官的剂量似乎有利于ISBT计划而非IMRT计划，且这具有统计学意义。在这种情况下，近距离放射治疗在剂量学上显示出优于IMRT的优势，并且在实际临床场景中，在毒性、器官保留和美容方面可能会带来益处。然而，这是否会在临床结果方面带来显著益处仍有待验证。
