Ciernik I Frank, Dizendorf Elena, Baumert Brigitta G, Reiner Beatrice, Burger Cyrill, Davis J Bernard, Lütolf Urs M, Steinert Hans C, Von Schulthess Gustav K
Department of Radiation Oncology Zurich University Hospital, Zurich, Switzerland.
Int J Radiat Oncol Biol Phys. 2003 Nov 1;57(3):853-63. doi: 10.1016/s0360-3016(03)00346-8.
To investigate the usefulness of hardware coregistered PET/CT images for target volume definition.
Thirty-nine patients presenting with various solid tumors were investigated. CT and a FDG-PET were obtained in treatment position in an integrated PET/CT scanner, and coregistered images were used for treatment planning. First, volume delineation was performed on the CT data. In a second step, the corresponding PET data were used as an overlay to the CT data to define the target volume. Delineation was done independently by two investigators.
Coregistered PET/CT showed good fusion accuracy. The GTV increased by 25% or more because of PET in 17% of cases with head-and-neck (2/12) and lung cancer (1/6), and in 33% (7/21) in cancer of the pelvis. The GTV was reduced > or =25% in 33% of patients with head-and-neck cancer (4/12), in 67% with lung cancer (4/6), and 19% with cancer of the pelvis (4/21). Overall, in 56% (22/39) of cases, GTV delineation was changed significantly if information from metabolic imaging was used in the planning process. The modification of the GTV translated into altered PTV changes exceeding >20% in 46% (18/39) of cases. With PET, volume delineation variability between two independent oncologists decreased from a mean volume difference of 25.7 cm(3) to 9.2 cm(3) associated with a reduction of the standard deviation from 38.3 cm(3) to 13.3 cm(3) (p = 0.02). In 16% of cases, PET/CT revealed distant metastasies, changing the treatment strategy from curative to palliative.
Integrated PET/CT for treatment planning for three-dimensional conformal radiation therapy improves the standardization of volume delineation compared with that of CT alone. PET/CT has the potential for reducing the risk for geographic misses, to minimize the dose of ionizing radiation applied to non-target organs, and to change the current practice to three-dimensional conformal radiation therapy planning by taking into account the metabolic and biologic features of cancer. The impact on treatment outcome remains to be demonstrated.
探讨硬件配准的PET/CT图像在靶区定义中的应用价值。
对39例患有各种实体瘤的患者进行研究。在一体化PET/CT扫描仪中于治疗体位获取CT和FDG-PET图像，并将配准图像用于治疗计划。首先，在CT数据上进行体积勾画。第二步，将相应的PET数据作为CT数据的叠加层以定义靶区。由两名研究人员独立进行勾画。
配准后的PET/CT显示出良好的融合精度。在17%的头颈癌（2/12）和肺癌（1/6）病例以及33%（7/21）的盆腔癌病例中，由于PET的原因，大体肿瘤体积（GTV）增加了25%或更多。在33%的头颈癌患者（4/12）、67%的肺癌患者（4/6）和19%的盆腔癌患者（4/21）中，GTV减少了≥25%。总体而言，在56%（22/39）的病例中，如果在计划过程中使用代谢成像信息，GTV勾画会有显著变化。在46%（18/39）的病例中，GTV的改变转化为计划靶体积（PTV）变化超过20%。使用PET时，两名独立肿瘤学家之间的体积勾画变异性从平均体积差异25.7 cm³降至9.2 cm³，标准差从38.3 cm³降至13.3 cm³（p = 0.02）。在16%的病例中，PET/CT显示远处转移，从而将治疗策略从根治性转变为姑息性。
与单独使用CT相比，用于三维适形放射治疗计划的一体化PET/CT提高了体积勾画的标准化程度。PET/CT有潜力降低遗漏肿瘤区域的风险，使施加到非靶器官的电离辐射剂量最小化，并通过考虑癌症的代谢和生物学特征将当前做法转变为三维适形放射治疗计划。其对治疗结果的影响仍有待证实。
