Tejpal Gupta, Jaiprakash Agarwal, Susovan Bannerjee, Ghosh-Laskar Sarbani, Murthy Vedang, Budrukkar Ashwini
Department of Radiation Oncology, Tata Memorial Centre, Mumbai, 410 210 India.
Indian J Surg Oncol. 2010 Apr;1(2):166-85. doi: 10.1007/s13193-010-0030-x. Epub 2010 Nov 21.
Intensity-modulated radiation therapy (IMRT) is a revolutionary new paradigm that aims at improving the therapeutic ratio by increasing the dosegradient between target tissues and surrounding normal structures thereby offering probability of better loco-regional control with decreased risk of complications. IMRT is relatively intolerant to set-up uncertainties, warranting periodic image-guidance, making Image-Guided Radiation Therapy (IGRT) a natural corollary to IMRT. There are several challenges associated with the planning, delivery, and quality assurance of the IMRT and IGRT processes that must be addressed to realize the full potential of such exciting and promising technology. Given the complexities involved, it is quite intuitive to understand that IMRT and IGRT are resource-intensive, demanding increased labor, rigour, and expenses too. Other disadvantages associated with high-precision techniques include potentially increased risk of marginal failures, decreased dose homogeneity, and an increase in total body dose with increased risk of secondary carcinogenesis. The aim of this review is to define the role of IMRT and IGRT in contemporary head and neck oncologic practice through a critical appraisal of pertinent literature. Despite relatively short follow-up and limited clinical outcomes data, the weight of evidence suggests that loco-regional control is not inferior (either comparable or even better) and toxicity lesser with IMRT resulting in potentially improved quality-of-life, prompting the widespread adoption of such technology in community practice. Ongoing clinical trials in head and neck IMRT are currently addressing issues to optimize the IMRT process, adopting functional imaging for dose-painting, and incorporating adaptive re-planning strategies to further improve outcomes.
调强放射治疗（IMRT）是一种革命性的新范例，旨在通过增加靶组织与周围正常结构之间的剂量梯度来提高治疗比，从而提供更好的局部区域控制概率，同时降低并发症风险。IMRT对摆位不确定性相对不耐受，需要定期进行图像引导，这使得图像引导放射治疗（IGRT）成为IMRT的自然延伸。与IMRT和IGRT过程的计划、实施和质量保证相关存在若干挑战，必须加以解决才能充分发挥这种令人兴奋且前景广阔的技术的潜力。鉴于其中涉及的复杂性，可以很直观地理解，IMRT和IGRT资源密集，需要更多的人力、严谨性和费用。与高精度技术相关的其他缺点包括边缘失败风险可能增加、剂量均匀性降低以及全身剂量增加，继发致癌风险升高。本综述的目的是通过对相关文献的批判性评估来界定IMRT和IGRT在当代头颈肿瘤学实践中的作用。尽管随访时间相对较短且临床结果数据有限，但证据表明，IMRT在局部区域控制方面并不逊色（相当或甚至更好），毒性更小，从而可能改善生活质量，促使该技术在社区实践中广泛应用。目前正在进行的头颈IMRT临床试验正在解决优化IMRT过程的问题，采用功能成像进行剂量描绘，并纳入自适应重新计划策略以进一步改善结果。
