[Assessment of radiation exposure caused by transmission scans in SPECT: an anthropomorphic dosimetry study]

Transmission measurements are performed in SPECT to correct for attenuation of the gamma quanta in the body. In this study, we measured the additional radiation dose caused by transmission scans using a field of collimated 153Gd rod sources. Two measurement series were performed with an anthropomorphic phantom and thermoluminescence dosimeters. For a typical SPECT study, we found a mean dose rate of 2.2 +/- 0.8 micro Sievert per hour (range: 1.2-3.9 micro Sievert per hour). For a measurement time of 20 min, this corresponds to a mean equivalent patient radiation dose of 0.73 micro Sievert. Thus, the radiation exposure caused by transmission scans can be neglected compared to the radiopharmaceutical dose and may not be considered as a limiting factor for the clinical application of attenuation correction in SPECT.