[Radiation exposure of the patient caused by transmission measurement for myocardial perfusion SPECT].

AIM: The aim was the determination of the radiation exposure to the patient caused by the transmission measurement for myocardial perfusion SPECT.

METHOD AND MATERIAL: Beside the emission measurement (Tc-99m-MIBI, A = 500 MBq) the myocardial perfusion SPECT simultaneously includes a transmission measurement using a Am-241-line source (A = 5550 MBq). During a simulation of the myocardial perfusion SPECT (without Tc-99m-MIBI) dose measurements with thermoluminescent dosimeters were carried out using a thorax phantom.

RESULTS

For an acquisition time of 20 min the absorbed doses amounted to: surface (xyphoid) 30 microGy, heart 25 microGy, lung 14 microGy, second thoracic vertebra 16 microGy, upper anterior mediastinum 16 microGy, liver 0 microGy. An estimation of the ratio of the effective doses caused by the transmission and the emission measurement of 3.6 x 10(-3) and 4.1 mSv, respectively, resulted in a value of 9 x 10(-4).

CONCLUSION

The radiation exposure of the patient caused by the transmission measurement can be neglected, and is therefore not a limiting factor regarding the general application of transmission measurement for clinical myocardial perfusion SPECT.