Umezawa Rei, Takanami Kentaro, Kadoya Noriyuki, Nakajima Yujiro, Saito Masahide, Ota Hideki, Matsushita Haruo, Sugawara Toshiyuki, Kubozono Masaki, Yamamoto Takaya, Ishikawa Yojiro, Takeda Ken, Taki Yasuyuki, Takase Kei, Jingu Keiichi
Department of Radiation Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Department of Diagnostic Radiology, Tohoku University Graduate School of Medicine, Sendai, Japan.
Radiat Oncol. 2015 Apr 21;10:96. doi: 10.1186/s13014-015-0410-z.
To evaluate the dose-effect relations for myocardial metabolic disorders after mediastinal radiotherapy (RT) by performing iodine-123 β-methyl-iodophenyl pentadecanoic acid (I-123 BMIPP) scintigraphy.
Between 2011 and 2012, we performed I-123 BMIPP scintigraphy for patients with esophageal cancer before and six months after curative mediastinal RT. Single photon emission computed tomography (SPECT) images of pre-RT and post-RT were registered into RT dose distributions. The myocardium was contoured, and the regional RT dose was calculated. Normalization is required to compare pre- and post-RT SPECT images because the uptake pattern is changed due to the breathing level. Normalization was applied on the mean of SPECT counts in regions of the myocardium receiving less than 5 Gy. Relative values in each dose region (interval of 5 Gy) were calculated on the basis of this normalization for each patient. The reduction in the percent of relative values was calculated.
Five patients were enrolled in this study. None of the patients had a past history of cardiac disease. The left ventricle was partially involved in RT fields in all patients. The patients received RT with median total doses of 60-66 Gy for the primary tumor and metastatic lymph nodes. Concomitant chemotherapy consisting of cisplatin or nedaplatin and 5-fluorouracil with RT was performed in 4 patients. All patients had reduced uptake corresponding to RT fields. Dose-effect relations for reduced uptake tended to be observed at 6 months after RT with mean decreases of 8.96% in regions at 10-15 Gy, 12.6% in regions at 20-25 Gy, 15.6% in regions at 30-35 Gy, 19.0% in regions at 40-45 Gy and 16.0% in regions at 50-55 Gy.
Dose-effect relations for myocardial metabolic disorders tended to be observed. We may need to make an effort to reduce high-dose mediastinal RT to the myocardium in RT planning.
通过进行碘-123β-甲基碘代苯基十五烷酸（I-123 BMIPP）闪烁扫描，评估纵隔放疗（RT）后心肌代谢紊乱的剂量效应关系。
2011年至2012年间，我们对食管癌患者在根治性纵隔放疗前及放疗后6个月进行I-123 BMIPP闪烁扫描。放疗前和放疗后的单光子发射计算机断层扫描（SPECT）图像被配准到放疗剂量分布中。勾勒出心肌轮廓，并计算局部放疗剂量。由于呼吸水平会改变摄取模式，因此比较放疗前和放疗后的SPECT图像需要进行归一化处理。对心肌中接受剂量小于5 Gy区域的SPECT计数平均值进行归一化处理。根据该归一化处理，为每位患者计算每个剂量区域（5 Gy间隔）的相对值。计算相对值百分比的降低情况。
本研究纳入5例患者。所有患者均无心脏病病史。所有患者的左心室均部分位于放疗野内。患者对原发肿瘤和转移淋巴结接受的放疗总剂量中位数为60 - 66 Gy。4例患者在放疗时联合使用顺铂或奈达铂及5-氟尿嘧啶进行化疗。所有患者对应放疗野的摄取均降低。放疗后6个月时，在10 - 15 Gy区域平均降低8.96%，在20 - 25 Gy区域平均降低12.6%，在30 - 35 Gy区域平均降低15.6%，在40 - 45 Gy区域平均降低19.0%，在50 - 55 Gy区域平均降低16.0%，呈现出摄取降低的剂量效应关系。
观察到心肌代谢紊乱的剂量效应关系。在放疗计划中，我们可能需要努力减少对心肌的高剂量纵隔放疗。
