Bone marrow dosimetry for 141 Ce-EDTMP as a potential bone pain palliation complex: A Monte Carlo study.

Due to favorable physical properties of ¹⁴¹ Ce radionuclide [E _βmax  = 434.6 keV (70.5%) and 580.0 keV (29.5%), E _γ  = 145.4 keV, and physical half-life = 32.5 day], a complex including this radionuclide could be a good candidate for palliative therapy of metastatic bone patients and an alternative to 89SrCl2 as a FDA-approved radiopharmaceutical. Because the bone marrow absorbed dose is a limiting factor in the palliative therapy of bone metastases, this study conducted to calculate the bone marrow absorbed dose of ¹⁴¹ Ce-EDTMP complex and compare it with the 89SrCl2 using Monte Carlo simulation. In this study, the GATE Monte Carlo toolkit and two human bone models including vertebra and femur bones were used for simulations. The vertebra and femur bone marrow absorbed dose from ¹⁴¹ Ce-EDTMP were 29.1 and 4.3 mGy/MBq, respectively. Moreover, the vertebra and femur bone marrow absorbed dose from ⁸⁹ SrCl ₂ were 109.2 and 16.3 mGy/MBq, respectively. Bone-to-bone marrow absorbed dose ratio in the vertebra for ¹⁴¹ Ce-EDTMP and ⁸⁹ SrCl ₂ was 34.2 and 11.6, respectively, whereas, this ratio in the femur was 23.8 and 7.5, respectively. Owing to the high bone-to-bone marrow absorbed dose ratio and lower bone marrow absorbed dose than ⁸⁹ SrCl ₂ , ¹⁴¹ Ce-EDTMP could be a promising new complex for palliative therapy of patients with bone metastasis.
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