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Attenuation factors for certain tissues when the body is irradiated omnidirectionally
Physics in Medicine and Biology
|September 1, 1979
Summary
This study quantifies radiation attenuation in human tissues using gamma rays. A mean attenuation factor of 0.7 is proposed for bone marrow from natural background radiation.
Area of Science:
- Medical Physics
- Radiation Dosimetry
- Biophysics
Background:
- Accurate estimation of absorbed radiation dose in human tissues is crucial for radiation protection.
- Understanding radiation attenuation factors is essential for correlating external exposure to internal absorbed dose.
- Previous studies have established the need for tissue-specific attenuation data.
Purpose of the Study:
- To experimentally determine mean attenuation factors for various human tissues.
- To establish relationships between absorbed dose in tissues and air dose/exposure for specific gamma-ray sources.
- To account for radiation scatter and photoelectron effects in dose calculations.
Main Methods:
- Irradiation of an anthropomorphic phantom with omnidirectional gamma rays from sodium-24, radium-226, iodine-131, and xenon-133.
- Measurement of experimental values for mean attenuation factors in different tissues.
- Correlation of absorbed dose in whole body, bone marrow, gonads, and skin with air dose and air exposure.
Main Results:
- Experimental attenuation factors were determined for specific tissues.
- Relationships were established between tissue absorbed dose and air dose/exposure.
- A mean attenuation factor of 0.7 was proposed for bone marrow from natural background gamma rays.
- The rad/R factor was determined to be 0.67 for bone marrow.
- The effective mean depth of bone marrow was estimated at 5.0–5.5 cm.
Conclusions:
- The study provides valuable experimental data for radiation dose assessment in human tissues.
- The proposed attenuation factor and rad/R factor offer practical tools for estimating bone marrow dose from natural background radiation.
- The findings contribute to a better understanding of radiation interactions within the human body.
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