INTERNAL DOSE CALCULATION FOR 99MTC.

作者：E M Smith · 发表于：PubMed · 年份：1965 · 被引用次数：83 · 研究领域：Radiopharmaceutical Chemistry and Applications、Advanced Radiotherapy Techniques、Radiation Dose and Imaging

Summary The total local energy deposited per distintegration, Ēβ for 99mTc is 14 kev per disintegration. The specific gamma-ray constant, Γ, for 99mTc is 0.72 R-cm2/mc-hr; however, 29 per cent of this value is due to Kα and Kβ x-rays which make up only 1.2 per cent of the total photon energy emitted by 99mTc. Standard methods of calculating the gamma component of the absorbed dose for 99mTc using the geometrical factor and Γ yield results which underestimate the absorbed dose by 16 to 30 per cent compared to calculations based on Monte Carlo techniques which take into account the energy dependence of μair and the inflated value of Γ. The Monte Carlo technique was used in making the absorbed dose estimates in this paper. Absorbed dose estimates were made for 99mTc as (a) TcO4− for brain scanning, as compared to 131I labeled serum albumin and 203Hg and 97Hg labeled Neohydrin; (b) 99mTc labeled serum albumin for placental scanning, as compared to 131I labeled serum albumin; and (c) the 99mTc sulfur colloid for liver and bone marrow scanning as compared to colloidal 198Au, colloidal 199Au and 131I aggregated albumin. Some of the biological problems encountered in calculating the absorbed dose are discussed.