适形调强放射治疗在头颈肿瘤中的临床应用

Experiences of Intensity Modulated Radiation Therapy（IMRT）for Head an d Neck Tumors

目的:介绍适形调强放射治疗在头颈肿瘤中临床使用的方法和初步结果。方法:2001年1月至2月我院用适形调强放射治疗头颈肿瘤15例,其中初治鼻咽癌4例,未控或复发鼻咽癌8例,第6颈椎神经鞘瘤,脑膜瘤,肺癌脑转移瘤各1例。照射靶区和敏感器官按ICRU50号文标准勾划。用孔雀系统的CORVUS做逆向治疗计划设计,用MIMiC作共面旋转照射。照射野每5°变换一次,从105°～255°旋转照射。常规外照射+后程IMRT6例,全程IMRT9例。全部病例按常规分割照射,200cGy/次,每周5次。常规外照射剂量20～70Gy。IMRT处方剂量:全程IMRT60～76Gy,后程IMRT30～50Gy。结果:尽管全部病例肿瘤体积的目标剂量是10～76Gy,但最后靶区的平均剂量可达到11.42～78.04Gy。敏感器官照射的平均剂量为,晶体3.26Gy0.30c.c视神经19.13Gy0.90c.c颞颌关节20.55Gy5.54c.c腮腺19.07Gy13.32c.c垂体21.98Gy0.76c.c脑干20.60Gy21.21c.c脊髓19.14Gy9.28c.c。结论:孔雀系统对头颈肿瘤的适形调强放疗能较好地适形照射肿瘤体积和有效地保护邻近敏感器官。

Objectives：To introduce the procedures and the p rimary r esults with IMRT for head and neck tumors．Methods ：Fiveteen patients with head and neck tumors were included in this study fr om Jan．to Feb．２００１at Cance r Center，Sun Yat－sen University of Medical Sciences，Guangzhou，China．Of them ，４were primary treatment of nasophary ngeal carcinoma （NPC）；８were NPC of u ncontrolled or recurrence of local－region in nasopharynx，retropharyngeal carot id sheath region，oropharynx and upper neck region；and the other ３were the s i xth cervical vertebra neurolemmom a，meningioma and brain metastasis with lung c ancer each．Target and critic al structures were contoured accord ing to ICRU ５ ０guideline．The inverse planning IMRT were created with CORVUS ３．０planni ng system（Peacock，NOMOS）and treated with segmental tomotherapy techniq ues（MIMi C）．The gantry rotation arc was １０５°～２５５°and beamlet changed every ５ °．Six patients were treated with IMRT f ollowed by conventional radiotherapy， and ９patients with IM RT alone．All patients were delivered by conventional fra ction s at ２Gy ／fraction ／day，５days ／week．The total dose delivered with c onventional radiotherapy were ２０－７０Gy．Prescription dose with full course I MRT was ６０－７６Gy and boost dose ３０－５０Gy for IMRT．Results：Although the goal was to deliver a pre scribed dose of １０－７６Gy to the GTV，the average mean d ose delivered was １１．４２～７８．０４Gy to t he GTV in this s tudy．The average mean dose and volume sparing critical str uctures were lens ３ ．２６Gy （０．３０c．c），optic nerves １９．１３Gy （０．９０c．c），temporal mandible joints ２０．５５Gy （５．５４c．c），parotid gland １９．０７Gy （１３ ．３２c．c），pituitary ２１．９５Gy （０．７６c．c），brain stem２０．６０Gy （ ２１．２１c．c），spinal cord １９．１４Gy （９．２８c．c）．Conclusion：The tre atment of head and neck tumors with Peacock system IMRT can have more con formal dose distribution to target v olume and effectively sparing critical structures ．