[Examination of Dosage Optimization Based on Body Weight Index in Resting Myocardial Blood Flow Scintigraphy Using 99mTc].

Purpose: The purpose of this study was to optimize radiopharmaceutical dosage in single-photon emission computed tomography (SPECT) nuclear medicine. Therefore, we examined a variable dose (VD) method using body weight as an index in resting myocardial scintigraphy using a ^99mTechnetium (^99mTc) preparation.

Methods: In this study, we compared the VD method with the fixed dose (FD) method without a variable by body weight. There were 50 patients using the VD method and 50 patients using the FD method. For the VD method, we set the target average count (counts/pixel) per SPECT view. Using the myocardial average count of the FD method, and the estimated intracorporeal radioactivity at the start of the examination, the dose of the VD method, which varies appropriately depending on the body weight, was calculated.

Results: The VD method had less variation in myocardial counting and was closer to the target count than the FD method, and the median dosage decreased.

Conclusion: The VD method suggested the possibility of obtaining a count independent of physique and stable image quality, reducing medical and occupational radiation exposure in resting myocardial blood flow scintigraphy.