RADIATION DOSIMETRY A THEORY RADIATION DOSES non-SI units (relationship between units) Dose Formula SI units ΔΕ D = Δm AE is the energy lost from the radiation beam, and Am is the mass of the material J/kg = Gray (Gy) Absorbed Dose, rad 1 Gy = 100 rad into which the energy is absorbed. Exposure dose, х ΔQ C/kg Roentgen (R) 1R = 2,58 ·104 C/kg Δm where AQ is the electric charge freed by such radiation in a specified volume of air divided by the mass Am of that air. Relationship between absorbed dose and exposure dose D = f ·X D is adsorbed dose , f is a coefficient depending on the kind of tissue being irradiated. H = Q · D where H is dose equivalent, Q is relative biological effectiveness of a particular kind of radiation, D is adsorbed dose. Equivalent Dose, Sievert rem Н (Sv) 1 Sy =100 rem Effective Sievert HE ΣΗΤ where H- = WT · H, is the tissue-weighted dose equivalent to an organ or tissue, H; is the dose equivalent to the organ or tissue and the WT applicable to that organ or rem Equivalent Dose , Нef (Sv) 1 Sy =100 rem tissue. Table 1 – Quality factors for different kinds of radiation Table 2 – Dimensionless weighting factors (Wr) Tissue W- Type of Radiation Gonads 0.25 Breast 0.15 х-гаys Red bone marrow 0.12 Lungs Thyroid Bone surfaces 0.12 0.03 20 0.03 Neutrons (fast) 10 Remainder 0.30 Protons 10 Total body 1.00 DOSE RATES 1. Adsorbed dose rate: Np =? Table 3 – Exposure constants Radionuclides k, (µGy-m³/GBq-h at 1 m)" 2. Dose equivalent rate: Nµ = - 137CS 88.11 99mTc 201TI 15.95 х 3. Exposure rate: Nỵ = 12.16 Exposure rate at a distance r from the source of "Mo 67G 1231 where is ky is exposure constant for a "In 39.46 radiation can be found as 20.54 ky'A 41.89 Nx = "Y r2 55.41 given radioisotope, A is activity of the radioactive source, r is distance from the source of the radiation. 37.03 SICO 15.16 1311 58.65 18Fb 154.05
RADIATION DOSIMETRY A THEORY RADIATION DOSES non-SI units (relationship between units) Dose Formula SI units ΔΕ D = Δm AE is the energy lost from the radiation beam, and Am is the mass of the material J/kg = Gray (Gy) Absorbed Dose, rad 1 Gy = 100 rad into which the energy is absorbed. Exposure dose, х ΔQ C/kg Roentgen (R) 1R = 2,58 ·104 C/kg Δm where AQ is the electric charge freed by such radiation in a specified volume of air divided by the mass Am of that air. Relationship between absorbed dose and exposure dose D = f ·X D is adsorbed dose , f is a coefficient depending on the kind of tissue being irradiated. H = Q · D where H is dose equivalent, Q is relative biological effectiveness of a particular kind of radiation, D is adsorbed dose. Equivalent Dose, Sievert rem Н (Sv) 1 Sy =100 rem Effective Sievert HE ΣΗΤ where H- = WT · H, is the tissue-weighted dose equivalent to an organ or tissue, H; is the dose equivalent to the organ or tissue and the WT applicable to that organ or rem Equivalent Dose , Нef (Sv) 1 Sy =100 rem tissue. Table 1 – Quality factors for different kinds of radiation Table 2 – Dimensionless weighting factors (Wr) Tissue W- Type of Radiation Gonads 0.25 Breast 0.15 х-гаys Red bone marrow 0.12 Lungs Thyroid Bone surfaces 0.12 0.03 20 0.03 Neutrons (fast) 10 Remainder 0.30 Protons 10 Total body 1.00 DOSE RATES 1. Adsorbed dose rate: Np =? Table 3 – Exposure constants Radionuclides k, (µGy-m³/GBq-h at 1 m)" 2. Dose equivalent rate: Nµ = - 137CS 88.11 99mTc 201TI 15.95 х 3. Exposure rate: Nỵ = 12.16 Exposure rate at a distance r from the source of "Mo 67G 1231 where is ky is exposure constant for a "In 39.46 radiation can be found as 20.54 ky'A 41.89 Nx = "Y r2 55.41 given radioisotope, A is activity of the radioactive source, r is distance from the source of the radiation. 37.03 SICO 15.16 1311 58.65 18Fb 154.05
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- A 14 g ovarian tumor is treated using a sodium phosphate solution in which the phosphorus atoms are the radioactive 32P isotope with a half life of 14.3 days and which decays via beta emission with an energy of 1.71MEV. Half of the sodium phosphate solution is absorbed by the tumor and deposits 9.00 J of energy into it. The other half of the solution is dispersed throughout the patients tissues, also depositing 9 J of energy into the 50.0 kg of body tissues. (a) What is the dose (in Gy and rem) that the tumor receives? (b) What is the dose (in Gy and rem) that the rest of the patient receives
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