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Dosimetry of some accelerator produced radioactive gases
162
Abstracts
factor of greatest importance, and simple models of lung gas turnover can be used as a basis for dosimetry calculations. since the greatest radiation dose is given by beta and conversion electron energy deposition in tissue surfaces, a knowledge of the geometry and histology of airways and blood vessels is required. Considerations of radiation dose to pulmonary tissues, and its subsequent radiobiological end result, should be made in the context of the overall risk of administering a radiopharmaceutical to a patient.
Dosimetry of some Accelerator Produced Radioactive Gases, by P. J. KENNY, D. D. WATSON,W. R. JANOWITZ, R. D. FINN, and A. J. GILSON. Baumritter Institute of Nuclear Medicine, Mount Sinai Medical Center, 4300 Alton Road, Miami Beach, Florida 33140, U.S.A. DATA and results of calculations on absorbed radiation dose to the lungs, whole body, testes and ovaries from inhaled C”0, are presented, based on measured lung clearance rates on 100 subjects comprising normal volunteers and patients ranging in age from 6 to 78 yr. Values for lung clearance rates and total body retention for “CO, following inhalation are presented, based on measurements on four normal volunteers. Basic considerations related to the use of labeled inert and metabolizable gases are discussed.
Dose Commitment to VaSoos Organs and Tissues from Inhalation of ‘““Xe, by S. R. BERNARD and W. S. SNYDER.Health Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, U.S.A. THE metabolic model of Bernard and Snyder for a single inhalation of ‘33Xe, together with the computer code in use at this laboratory were employed for estimating dose commitments to various organs and tissues in the adult human body. The code uses the Monte Carlo data of Snyder et al. for photons and assumes complete absorption of the energy from the emitted electrons in organs and tissues. For bone, the model of Spiers was used to estimate dose to red and yellow marrow and to endosteal cells of both trabecular and cortical bone. For a single inhalation of 1 mCi of ‘33Xe, the 50 yr dose to gonads was about 0.4mrad. The dose to lungs from ‘33Xe dissolved in tissues is about the same,
but the dose to the lungs from ‘.“Xe in air spaces was about 1 mrad. There have been a number of studies on the retention of “‘Kr under near-equilibrium conclitions, but there seems to be little information available on retention and distribution after a single intake of a noble gas with a fairly short radioactive half-life such as “‘Xe. The retention model for Xe is essentially that developed by Bernard and Snyder and is based on the analysis of data on radon inhalation in a human subject. The main features of the model will be indicated briefly here. The data on radon exhalation after exposure to the gas for a period of more than 8 hr was analyzed and fitted with a formula of five exponential terms by those authors. This formula has been deconvoluted to arrive at retention of a brief intake of radon, with corrections for radioactive decay. The distribution of radon in the compartments has been established by a method given by Bernard and by further analysis in terms of the body organs and tissues. The organs and tissues of the body are grouped into three classes: one with a high Ostwald coefficient, one with a low Ostwald coefficient, and an intermediate class. (The Ostwald solubility coefficient, L, is the ratio of the concentration (weight per unit volume) in the medium (or tissue) to the concentration in air.) Here the data of Nussbaum on the distribution of radon in rats and his extrapolation to the distribution to be expected in man have been followed.
Bureau of Drugs Requirements for Radiation Dosimetry of Radiopharmaceutical Drug Products, by BERGENE KAWIN and G. RICHARD GROVE. U.S. Food and Drug Administration, 5600 Fishers Lane, Rockville, Maryland 20852, U.S.A. THE chief concern of the Bureau of Drugs of the Food and Drug Administration inthe field of radiation dosimetry is to ensure that radiopharmaceutical drug products are safe and effective for the uses for which they are indicated. In order to bring this about, it is required that the sponsor who plans studies of a radiopharmaceutical drug must provide information that clearly describes the drug’s physical characteristics and purity, including both chemical and radiochemical purity. In addition to substances that are added to prepare the finished drug product, the detailed composition of the drug should include all significant radioactive contaminants. The presence of radioactive contaminants may give rise to sizeable increments in the radiation absorbed dose values beyond those that are due
Abstracts
factor of greatest importance, and simple models of lung gas turnover can be used as a basis for dosimetry calculations. since the greatest radiation dose is given by beta and conversion electron energy deposition in tissue surfaces, a knowledge of the geometry and histology of airways and blood vessels is required. Considerations of radiation dose to pulmonary tissues, and its subsequent radiobiological end result, should be made in the context of the overall risk of administering a radiopharmaceutical to a patient.
Dosimetry of some Accelerator Produced Radioactive Gases, by P. J. KENNY, D. D. WATSON,W. R. JANOWITZ, R. D. FINN, and A. J. GILSON. Baumritter Institute of Nuclear Medicine, Mount Sinai Medical Center, 4300 Alton Road, Miami Beach, Florida 33140, U.S.A. DATA and results of calculations on absorbed radiation dose to the lungs, whole body, testes and ovaries from inhaled C”0, are presented, based on measured lung clearance rates on 100 subjects comprising normal volunteers and patients ranging in age from 6 to 78 yr. Values for lung clearance rates and total body retention for “CO, following inhalation are presented, based on measurements on four normal volunteers. Basic considerations related to the use of labeled inert and metabolizable gases are discussed.
Dose Commitment to VaSoos Organs and Tissues from Inhalation of ‘““Xe, by S. R. BERNARD and W. S. SNYDER.Health Physics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, U.S.A. THE metabolic model of Bernard and Snyder for a single inhalation of ‘33Xe, together with the computer code in use at this laboratory were employed for estimating dose commitments to various organs and tissues in the adult human body. The code uses the Monte Carlo data of Snyder et al. for photons and assumes complete absorption of the energy from the emitted electrons in organs and tissues. For bone, the model of Spiers was used to estimate dose to red and yellow marrow and to endosteal cells of both trabecular and cortical bone. For a single inhalation of 1 mCi of ‘33Xe, the 50 yr dose to gonads was about 0.4mrad. The dose to lungs from ‘33Xe dissolved in tissues is about the same,
but the dose to the lungs from ‘.“Xe in air spaces was about 1 mrad. There have been a number of studies on the retention of “‘Kr under near-equilibrium conclitions, but there seems to be little information available on retention and distribution after a single intake of a noble gas with a fairly short radioactive half-life such as “‘Xe. The retention model for Xe is essentially that developed by Bernard and Snyder and is based on the analysis of data on radon inhalation in a human subject. The main features of the model will be indicated briefly here. The data on radon exhalation after exposure to the gas for a period of more than 8 hr was analyzed and fitted with a formula of five exponential terms by those authors. This formula has been deconvoluted to arrive at retention of a brief intake of radon, with corrections for radioactive decay. The distribution of radon in the compartments has been established by a method given by Bernard and by further analysis in terms of the body organs and tissues. The organs and tissues of the body are grouped into three classes: one with a high Ostwald coefficient, one with a low Ostwald coefficient, and an intermediate class. (The Ostwald solubility coefficient, L, is the ratio of the concentration (weight per unit volume) in the medium (or tissue) to the concentration in air.) Here the data of Nussbaum on the distribution of radon in rats and his extrapolation to the distribution to be expected in man have been followed.
Bureau of Drugs Requirements for Radiation Dosimetry of Radiopharmaceutical Drug Products, by BERGENE KAWIN and G. RICHARD GROVE. U.S. Food and Drug Administration, 5600 Fishers Lane, Rockville, Maryland 20852, U.S.A. THE chief concern of the Bureau of Drugs of the Food and Drug Administration inthe field of radiation dosimetry is to ensure that radiopharmaceutical drug products are safe and effective for the uses for which they are indicated. In order to bring this about, it is required that the sponsor who plans studies of a radiopharmaceutical drug must provide information that clearly describes the drug’s physical characteristics and purity, including both chemical and radiochemical purity. In addition to substances that are added to prepare the finished drug product, the detailed composition of the drug should include all significant radioactive contaminants. The presence of radioactive contaminants may give rise to sizeable increments in the radiation absorbed dose values beyond those that are due