【摘要】 目的 研究两种不同的衰减系数转换方法对正电子发射计算机断层显像/计算机体层扫描（PET/CT） 标准摄取值（SUV）测量值的影响。 方法 2009年11-12月，从经过PET/CT氟代脱氧葡萄糖（FDG）显像患者中选取20例，其口腔中均有金属假牙。以四段转换法和二段转换法重建全身衰减校正断层图像。分别选取3种高密度区域和7种低密度区域，测量其最大SUV和平均SUV，比较两种转换方法SUV测量值。 结果 平均SUV：二段转换法的3种高密度区域SUV降低，在7种低密度区域中，1种区域增高，1种区域降低（P值均lt;0.05）。最大SUV：二段转换法的2种高密度区域的SUV降低，在7种低密度区域中，1种区域增高，2种靠近高密度组织的区域降低（P值均lt;0.05）。 结论 二段转换法能降低高密度区域的SUV，可用于减小体内金属植入物和CT对比剂造成的过度校正。【Abstract】 Objective To explore the effect of two attenuation correction algorithms on PET/CT SUV measurement. Methods From November to December 2009, the PET Slice of 20 patients with metallic dental implant were reconstructed with four-and two-section algorithms respectively. Mean SUV and maximum SUV were measured in three high-density areas and 7 low-density areas. Paired t test were performed to compare the differences. Results Mean SUV: two-section algorithm produced significantly lower SUV in all the three high-density areas; in the 7 low-density areas, SUV increased obviously in one area and decreased apparently in one area (Plt;0.05). Maximum SUV: two-section algorithm produced significantly lower SUV in two high-density areas, SUV increased obviously in one area and decreased apparently in two areas which was adjacent to the high density areas (Plt;0.05). Conclusion Two-section algorithm produces lower SUV measurement value than the four-section algorithm does, and it is useful in PET/CT studies for patients with metallic dental implant and when CT contrast is used.
ObjectiveTo estimate the radiation dose (RD) to the general public and nuclear medicine technicians from patients undergoing 99mTc-methoxy isobutyl isonitrile (MIBI) myocardial perfusion imaging. MethodsFrom January to June 2015, 55 patients including 30 males and 25 females aged between 25 and 87 years[averaging (63.6±15.1)years] ready to undergo myocardial perfusion scintigraphy with 99mTc-MIBI were prospectively recruited in this study. Approximately at hour 1.5 after injection of 99mTc-MIBI, whole-body dose-equivalent rate was measured with a radiation-survey meter at 0.3 meter and 1.0 meter from the patients. On the basis of human 99mTc-MIBI metabolic rate proposed by the International Commission of Radiological Protection and human social contact model proposed by the National Council on Radiation Protection and Measurements, the RDs to the general public from patients who had completed 99mTc-MIBI myocardial perfusion imaging and left nuclear medicine department were calculated. On the assumption that a nuclear medicine technician typically spent 5 minutes at a distance of 0.3 meter for positioning the patient, the technician's RD was also estimated. ResultsThe RD to a family member sleeping with the patient at night was predicted to be 42.88-160.55 μSv, to a family member contacting the patient at daytime 7.50-29.38 μSv, to a colleague 9.89-38.78 μSv and to a nearby passenger 124.48-466.06 μSv. The RD to a technician per 99mTc-MIBI myocardial perfusion imaging procedure was predicted to be 1.72-6.44 μSv. ConclusionThe predicted RDs to the general public and technicians from exposure of patients undergoing 99mTc-MIBI myocardial perfusion imaging are significantly lower than the regulatory dose limits.
ObjectiveUtilizing PDCA circulation to enhance the quality of single photon emission computed tomography (SPECT) in whole body bone scan (WBS). MethodsBased on a retrospective analysis of the quality of WBS in the first half of year 2012, advices and measurements to improve the quality were implemented by the technologists. In the following half year of 2012, monthly evaluation of the WBS quality were carried out to further improve the quality by focusing on fine details of the patient positioning, radiopharmaceuticals injection and image processing, etc. ResultsBy utilization of PDCA circulation, WBS quality in the latter half year of 2012 constantly improved. Further more, effective and improved technical procedures were extracted from scattered individual experience, which was expected to improve the WBS quality effectively in the long run. ConclusionApplication of PDCA circulation in SPECT in whole body bone scan improves the image quality, because it not only brings better communication and understanding between patients and physicians/technologists, but also enables better patient preparations and individualized procedures based on standard protocols.