Clark Catharine H, Bidmead A Margaret, Mubata Cephas D, Harrington Kevin J, Nutting Christopher M
Joint Department of Physics, The Royal Marsden NHS Trust, Fulham Road, London SW3 6JJ, UK.
Radiother Oncol. 2004 Feb;70(2):189-98. doi: 10.1016/j.radonc.2003.10.012.
An investigation has been carried out into the potential of intensity-modulated radiotherapy (IMRT) to improve the coverage of the targets and the sparing of the spinal cord (SC) in radiotherapy treatment of the larynx and bilateral cervical lymph nodes, in patients with advanced larynx cancer.
Conventional radiotherapy (CRT) and IMRT plans were produced for six patients to treat the larynx (PTV1) and lymph nodes (PTV2) to 50 Gy (phase 1). A second plan was created to treat the PTV1 to 65 Gy and PTV2 to 50 Gy (phases 1 and 2). The potential to escalate the dose to both the larynx (to 67 Gy) and the nodes (to 56 Gy) was investigated for the IMRT plans.
The phase 1 treatment gave average minimum doses (dose received by 99% volume) of 38.1 (+/-8.2) and 48.5 (+/-0.2)Gy for PTV1, treated by CRT and IMRT, respectively, and 35.9 (+/-2.9) and 46.2 (+/-1.8)Gy for PTV2. For the two phase treatment the average minimum doses to PTV1 were 51.6 (+/-8.2) (CRT) and 62.1 (+/-0.7)Gy (IMRT) (p=0.028) and for PTV2 were 36.2 (+/-2.9) (CRT) and 46.8 (+/-0.5)Gy (IMRT) (P=0.0004). The average maximum doses (dose received by 1% volume) to the SC were 42.5 (+/-1.9) (CRT) and 37.9 (+/-1.4)Gy (IMRT) (P=0.01). For the dose escalated IMRT plans the minimum dose to PTV1 was 64.6 (+/-0.5) and 50.8 (+/-1.8)Gy to PTV2. The average SC maximum was 41.5 (+/-1.6)Gy.
IMRT offers improved target homogeneity and reduces irradiation of the SC. This sparing of normal tissue structures is sufficient that significant dose escalation of both the larynx and lymph nodes may be possible.
对调强放射治疗（IMRT）在晚期喉癌患者喉及双侧颈部淋巴结放射治疗中提高靶区覆盖率和脊髓（SC）保护方面的潜力进行了研究。
为6例患者制定了常规放射治疗（CRT）和IMRT计划，用于将喉（PTV1）和淋巴结（PTV2）照射至50 Gy（第1阶段）。制定了第二个计划，将PTV1照射至65 Gy，PTV2照射至50 Gy（第1和第2阶段）。研究了IMRT计划中对喉（至67 Gy）和淋巴结（至56 Gy）增加剂量的潜力。
第1阶段治疗中，CRT和IMRT治疗PTV1的平均最小剂量（99%体积所接受的剂量）分别为38.1（±8.2）和48.5（±0.2）Gy，PTV2分别为35.9（±2.9）和46.2（±1.8）Gy。对于两阶段治疗，PTV1的平均最小剂量，CRT为51.6（±8.2）Gy，IMRT为62.1（±0.7）Gy（p = 0.028）；PTV2的平均最小剂量，CRT为36.2（±2.9）Gy，IMRT为46.8（±0.5）Gy（P = 0.0004）。脊髓的平均最大剂量（1%体积所接受的剂量），CRT为42.5（±1.9）Gy，IMRT为37.9（±1.4）Gy（P = 0.01）。对于增加剂量的IMRT计划，PTV1的最小剂量为64.6（±0.5）Gy，PTV2为50.8（±1.8）Gy。脊髓的平均最大剂量为41.5（±1.6）Gy。
IMRT可提高靶区均匀性并减少脊髓照射。对正常组织结构的这种保护足以使喉和淋巴结显著增加剂量成为可能。
