Mutic Sasa, Malyapa Robert S, Grigsby Perry W, Dehdashti Farrokh, Miller Tom R, Zoberi Imran, Bosch Walter R, Esthappan Jacqueline, Low Daniel A
Department of Radiation Oncology, Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Int J Radiat Oncol Biol Phys. 2003 Jan 1;55(1):28-35. doi: 10.1016/s0360-3016(02)03804-x.
To evaluate a treatment planning method for dose escalation to the para-aortic lymph nodes (PALNs) based on positron emission tomography (PET) with intensity-modulated radiotherapy (IMRT) for cervical cancer patients with PALN involvement. One goal of this process was not to modify the traditional treatment of the pelvic region.
PET images for 4 cervical cancer patents with PALN involvement were registered with their corresponding CT scans. Positive PALNs were identified on PET images, and the surrounding critical structures were delineated on CT images. The treatment machine central axis (CAX) was placed at the level of the L4-L5 vertebral body interspace. There were two distinct treatment regions: the para-aortic bed superior to the CAX and the whole pelvis region inferior to the CAX. IMRT was used for treatment planning of PALN bed irradiation. The positive PALNs identified on PET images were defined as the gross target volume, and the para-aortic bed was defined as the clinical target volume. The radiation doses were escalated from the conventional 45 Gy to 59.4 Gy for the gross target volume and 50.4 Gy for the clinical target volume in 33 fractions. The pelvis area was treated with conventional treatment methods, AP-PA beams to 50.4 Gy in 28 fractions with a brachytherapy implant boost. The placement of the CAX allowed the two treatment regions to be abutted using the treatment machine's independent jaws.
Dose escalation to positive PALNs, as identified on PET images, and the PALN bed is feasible with IMRT. Treatment plans for 4 patients revealed that escalated prescription doses could be delivered to target volumes while maintaining acceptable doses to the surrounding critical structures. Strategic placement of the treatment isocenter allows the IMRT region (PALN bed) and whole pelvis fields to be treated with a relatively uniform dose distribution in the abutment region.
This study indicates that PET-guided IMRT could be used in a clinical trial in an attempt to escalate doses delivered to patients with cervical cancer who have positive PALNs.
评估一种基于正电子发射断层扫描（PET）的剂量递增治疗计划方法，该方法用于对伴有腹主动脉旁淋巴结（PALN）转移的宫颈癌患者进行调强放射治疗（IMRT），此过程的一个目标是不改变盆腔区域的传统治疗方式。
对4例伴有PALN转移的宫颈癌患者的PET图像与相应的CT扫描图像进行配准。在PET图像上识别出阳性PALN，并在CT图像上勾勒出周围的关键结构。治疗机器中心轴（CAX）置于L4-L5椎体间隙水平。有两个不同的治疗区域：CAX上方的腹主动脉旁区和CAX下方的整个盆腔区域。IMRT用于腹主动脉旁淋巴结床照射的治疗计划。在PET图像上识别出的阳性PALN被定义为大体靶体积，腹主动脉旁区被定义为临床靶体积。大体靶体积的放射剂量从常规的45 Gy递增至59.4 Gy，分33次给予，临床靶体积的放射剂量为50.4 Gy。盆腔区域采用传统治疗方法，前后野照射至50.4 Gy，分28次给予，并加近距离放疗植入物增敏。CAX的放置使得两个治疗区域可以使用治疗机器的独立准直器进行对接。
对于PET图像上识别出的阳性PALN及其淋巴结床进行剂量递增的IMRT治疗是可行的。4例患者的治疗计划显示，在保持周围关键结构可接受剂量的同时，可以将递增的处方剂量给予靶体积。治疗等中心的策略性放置使得IMRT区域（腹主动脉旁淋巴结床）和整个盆腔野在对接区域能够以相对均匀的剂量分布进行治疗。
本研究表明，PET引导下的IMRT可用于临床试验，尝试对伴有阳性PALN的宫颈癌患者递增剂量。
