Estimating the Absorbed Doses from 99mTc-MDP in Patients Following Bone Scan

In nuclear medicine, reliable estimation of radiation doses from the diagnostic or therapeutic radiopharmaceuticals is essential to evaluate the risks and benefits of their use. The general Medical Internal Radiation Dose (MIRD) method is used in analysis to estimate the internal emitter whole organ absorbed dose. This study aimed to estimate the absorbed doses from 99mTc-methylene diphosphonate (99mTc-MDP) in patients following bone scan.

22 patients referred to the Nuclear Medicine Department of Shahid Chamran Hospital, Isfahan, Iran, for investigation bone metastases were enrolled. Whole-body images were acquired at 10, 60, 90 and 180 minutes after the injection of 99mTc-MDP. Organ activities were calculated via the conjugate view method, using conventional background correction method. Finally, the absorbed dose was calculated using the MIRD technique.

The absorbed doses of 99mTc-MDP in bone, bladder and kidneys, using the conventional background correction method, were 0.13 ± 0.04, 0.08 ± 0.01 and 0.02 ± 0.00 rad/mCi, respectively.

The results of this study showed that the calculation of absorbed dose, using conventional background correction method, was in good agreement with MIRD report No. 13.