肺灌注显像观察肺癌三维适形放疗对患者近期肺功能的影响

背景与目的:对胸部肿瘤进行放射治疗时,正常肺组织会受到部分照射,出现不同程度的放射性肺损伤。临床上常用肺功能测试(pulmonaryfunctiontests,PFTs)来评估放疗后全肺功能变化,往往不够准确。核素肺灌注扫描与其它影像学方法相比能更好地反映肺的局部生理功能,而三维适形放疗计划系统能定量计算肿瘤和周围肺组织的照射剂量。本研究目的是利用肺灌注显像来初步观察肺癌患者三维适形放疗前后的局部肺功能早期变化。方法:19例行三维适形放疗的肺癌患者,放疗前及照射40～50Gy时行肺灌注显像检查,并将结果与同期的X片或CT检查比较。将放疗前肺灌注图像与同期的X片、CT片相比较,按缺损区与肿瘤病灶的大小分为:0级,无灌注受损;1级,肿瘤及其周围局部肺灌注受损;2级,达1叶肺灌注受损;3级,超过1叶肺灌注受损。在肺灌注的断层图像上将照射剂量大于20Gy以上范围在断层图像上勾画感兴趣区(regionofinterest,ROI),以ROI内的放射性计数占同层面双肺放射性总计数的比值来比较照射前后肺灌注的变化,并用配对t检验来进行统计学分析。结果:(1)19例患者均有不同程度的肺动脉血流灌注受损,其中1级9例,2级5例,3级5例。(2)肺灌注的定量分析:19例行放疗前及放疗中肺灌注检查的患者,放疗前ROI的放射性比值平均为(53.67±29.81)%,

Utility of SPECT lung perfusion scans in assessing early changes in pulmonary function of patients with lung cancer after radiotherapy

BACKGROUND & OBJECTIVE: Radiation-induced lung injury is commonly following radiotherapy (RT)for tumors in,and around the thorax. Lung function is usually assessed by pulmonary function tests (PFTs), but RT-induced regional changes of pulmonary function cannot be accurately evaluated by PFTs. Lung perfusion scintigraphy compared with other radiographic methods can well assess the regional pulmonary physiological function,and 3-dimension conformal radiotherapy (3D-CRT) planning system can quantitatively calculate irradiation dosage. This study was to assess early changes in the pulmonary function of patients with lung cancer receiving thoracic 3D-CRT by lung perfusion scintigraphy. METHODS: Nineteen patients receiving thoracic 3D-CRT for lung cancer were studied. Single photon emission computed tomography (SPECT) lung perfusion scan,and X-ray or CT scan before RT, and after 40-50 Gy radiation were performed. Pre-RT SPECT lung perfusion images were classified by comparing lung perfusion defect with area of radiological abnormality before RT. Grade 0: no lung perfusion defect in the area of radiological abnormality. Grade 1: the size of radiological abnormality is similar to the area of lung perfusion defect. Grade 2: the area of lung perfusion defect is bigger than that of radiological abnormality,and extend to 1 pulmonary lobe. Grade 3: the area of lung perfusion defect exceed 1 pulmonary lobe. The radiation field with more than 20 Gy was drawn as a region of interest (ROI). The proportion of radioactive count within this ROI to total lung count in one slice was calculated to assess changes in pulmonary function after RT. Student's t test was used for statistical analyses. RESULTS: All patients had lung perfusion defect, 9 patients with grade 1 damage, 5 patients with grade 2 damage, and 5 patients with grade 3 damage. All tumors in the 19 patients were reduced with variant degree after 40-50 Gy radiation in CT or X-ray images. The mean radioactive proportions of ROI in 19 patients were (53.7+/-29.8)% before radiation,and (57.6+/-22.6)% during RT, the difference wasn't significant (P=0.280). The relatively decreased post-RT lung perfusion was observed in 6 patients, whereas the relatively increased post-RT lung perfusion was observed in 13 patients. CONCLUSION: SPECT lung perfusion scans is a simple, convenient, and useful method for assessing pre-RT regional lung function,and monitoring the changes in regional lung function after irradiation.