Department of Oncology, Lund University and Lund University Hospital, Lund, Sweden.
Cancer. 2010 Feb 15;116(4 Suppl):1084-92. doi: 10.1002/cncr.24796.
(177)Lu-(DOTA0,Tyr3) octreotate is a new treatment modality for disseminated neuroendocrine tumors. According to a consensus protocol, the calculated maximally tolerated absorbed dose to the kidney should not exceed 27 Gy. In commonly used dosimetry methods, planar imaging is used for determination of the residence time, whereas the kidney mass is determined from a computed tomography (CT) scan.
Three different quantification methods were used to evaluate the absorbed dose to the kidneys. The first method involved common planar activity imaging, and the absorbed dose was calculated using the medical internal radiation dose (MIRD) formalism, using CT scan-based kidney masses. For this method, 2 region of interest locations for the background correction were investigated. The second method also included single-photon emission computed tomography (SPECT) data, which were used to scale the amplitude of the time-activity curve obtained from planar images. The absorbed dose was calculated as in the planar method. The third method used quantitative SPECT images converted to absorbed dose rate images, where the median absorbed dose rate in the kidneys was calculated in a volume of interest defined over the renal cortex.
For some patients, the results showed a large difference in calculated kidney-absorbed doses, depending on the dosimetry method. The 2 SPECT-based methods generally gave consistent values, although the calculations were based on different assumptions. Dosimetry using the baseline planar method gave higher absorbed doses in all patients. The values obtained from planar imaging with a background region of interest placed adjacent to the kidneys were more consistent with dosimetry also including SPECT. For the accumulated tumor absorbed dose, the first 2 of the 4 planned therapy cycles made the major contribution.
The results suggested that patients evaluated according to the conventional planar-based dosimetry method may have been undertreated compared with the other methods. Hematology and creatinine did not indicate any restriction for a more aggressive approach, which would be especially useful in patients with more aggressive tumors where there is not time for more protracted therapy.
（177）Lu-（DOTA0，Tyr3）奥曲肽是一种新的治疗弥散性神经内分泌肿瘤的方法。根据共识方案，肾脏的最大耐受吸收剂量不应超过 27Gy。在常用的剂量测定方法中，平面成像用于确定停留时间，而肾脏质量则来自计算机断层扫描（CT）扫描。
使用三种不同的定量方法来评估肾脏的吸收剂量。第一种方法涉及常见的平面活性成像，吸收剂量使用基于 CT 扫描的肾脏质量的医学内部辐射剂量（MIRD）公式进行计算。对于这种方法，研究了 2 个用于背景校正的感兴趣区域位置。第二种方法还包括单光子发射计算机断层扫描（SPECT）数据，用于对从平面图像获得的时间-活性曲线的幅度进行缩放。吸收剂量按平面方法计算。第三种方法使用转换为吸收剂量率图像的定量 SPECT 图像，其中在定义在肾皮质上的感兴趣体积中计算肾脏的中位数吸收剂量率。
对于一些患者，根据剂量测定方法，计算出的肾脏吸收剂量存在很大差异。两种基于 SPECT 的方法通常给出一致的值，尽管计算基于不同的假设。在所有患者中，使用基线平面方法进行的剂量测定给出了更高的吸收剂量。将感兴趣区域置于肾脏附近的背景区域放置在平面成像中获得的值与也包括 SPECT 的剂量测定更一致。对于累积肿瘤吸收剂量，前 4 个计划治疗周期中的前 2 个周期做出了主要贡献。
结果表明，与其他方法相比，根据常规基于平面的剂量测定方法评估的患者可能治疗不足。血液学和肌酐没有表明更积极的方法有任何限制，对于更具侵袭性的肿瘤患者，这种方法特别有用，因为没有时间进行更漫长的治疗。
