Simplification of Activity Measurement during Quantitative Value Estimation in Bone SPECT

Abstract

To calculate the quantitative values in bone single-photon emission computed tomography, it is necessary to measure the amount of syringe radiation before and after the administration of a radiopharmaceutical. We proposed a method to omit the measurement of radioactivity. In this study, we clarified the effects of adopting this method and calculated its influence on quantitative values in a clinical setting. We derived a relational expression of the administration time and dose of radioactivity from the measured value and the administration time of the syringe dose before and after the administration in each patient. Next, we determined the differences for radioactivity calculated from this relational expression (estimated dose) and actual administered radioactivity (actual dose). Furthermore, we calculated the differences in the quantitative values of a normal region (the fourth lumbar vertebra) on adopting these data. No significant differences between the estimated dose and actual dose were noted. Additionally, no significant differences in the quantitative values were observed. Our findings suggest that adoption of the estimated dose does not affect the quantitative value. When the estimated dose is adopted, it can be administered with an accuracy of 0.80%. Thus, it is possible to omit the actual measurement of radioactivity by using our proposed method.