Scarfone Christopher, Lavely William C, Cmelak Anthony J, Delbeke Dominique, Martin William H, Billheimer Dean, Hallahan Dennis E
Department of Radiation Oncology, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
J Nucl Med. 2004 Apr;45(4):543-52.
The aim of this investigation was to evaluate the influence and accuracy of (18)F-FDG PET in target volume definition as a complementary modality to CT for patients with head and neck cancer (HNC) using dedicated PET and CT scanners.
Six HNC patients were custom fitted with head and neck and upper body immobilization devices, and conventional radiotherapy CT simulation was performed together with (18)F-FDG PET imaging. Gross target volume (GTV) and pathologic nodal volumes were first defined in the conventional manner based on CT. A segmentation and surface-rendering registration technique was then used to coregister the (18)F-FDG PET and CT planning image datasets. (18)F-FDG PET GTVs were determined and displayed simultaneously with the CT contours. CT GTVs were then modified based on the PET data to form final PET/CT treatment volumes. Five-field intensity-modulated radiation therapy (IMRT) was then used to demonstrate dose targeting to the CT GTV or the PET/CT GTV.
One patient was PET-negative after induction chemotherapy. The CT GTV was modified in all remaining patients based on (18)F-FDG PET data. The resulting PET/CT GTV was larger than the original CT volume by an average of 15%. In 5 cases, (18)F-FDG PET identified active lymph nodes that corresponded to lymph nodes contoured on CT. The pathologically enlarged CT lymph nodes were modified to create final lymph node volumes in 3 of 5 cases. In 1 of 6 patients, (18)F-FDG-avid lymph nodes were not identified as pathologic on CT. In 2 of 6 patients, registration of the independently acquired PET and CT data using segmentation and surface rendering resulted in a suboptimal alignment and, therefore, had to be repeated. Radiotherapy planning using IMRT demonstrated the capability of this technique to target anatomic or anatomic/physiologic target volumes. In this manner, metabolically active sites can be intensified to greater daily doses.
Inclusion of (18)F-FDG PET data resulted in modified target volumes in radiotherapy planning for HNC. PET and CT data acquired on separate, dedicated scanners may be coregistered for therapy planning; however, dual-acquisition PET/CT systems may be considered to reduce the need for reregistrations. It is possible to use IMRT to target dose to metabolically active sites based on coregistered PET/CT data.
本研究的目的是评估使用专用PET和CT扫描仪时，（18）F-FDG PET在头颈部癌（HNC）患者靶区定义中作为CT补充手段的影响和准确性。
6名头颈部癌患者定制了头颈部及上身固定装置，进行了常规放疗CT模拟以及（18）F-FDG PET成像。首先基于CT以传统方式定义大体肿瘤靶区（GTV）和病理淋巴结体积。然后使用分割和表面渲染配准技术将（18）F-FDG PET和CT计划图像数据集进行配准。确定（18）F-FDG PET GTV并与CT轮廓同时显示。然后根据PET数据修改CT GTV以形成最终的PET/CT治疗体积。然后使用五野调强放射治疗（IMRT）来展示对CT GTV或PET/CT GTV的剂量靶向。
1例患者诱导化疗后PET呈阴性。其余所有患者的CT GTV均根据（18）F-FDG PET数据进行了修改。最终的PET/CT GTV比原始CT体积平均大15%。在5例中，（18）F-FDG PET识别出与CT上勾画的淋巴结相对应的活性淋巴结。5例中有3例对病理上增大的CT淋巴结进行了修改以创建最终淋巴结体积。6例患者中有1例，（18）F-FDG摄取阳性的淋巴结在CT上未被判定为病理性。6例患者中有2例，使用分割和表面渲染对独立采集的PET和CT数据进行配准导致对齐不理想，因此必须重复操作。使用IMRT进行放疗计划证明了该技术靶向解剖或解剖/生理靶区的能力。通过这种方式，代谢活跃部位可被强化至更高的每日剂量。
纳入（18）F-FDG PET数据导致头颈部癌放疗计划中的靶区体积发生改变。在单独的专用扫描仪上采集的PET和CT数据可进行配准用于治疗计划；然而，可考虑使用双采集PET/CT系统以减少重新配准的需求。基于配准的PET/CT数据，使用IMRT将剂量靶向代谢活跃部位是可行的。
