Measuring Radiation for Safe Exposure and Medical Use
Text Reading: Giancoli, Physics - Principles with Applications, Chapter 31: Sections 5 to 9
- 31: 6 Radiation therapy is the use of radiation to kill selected cells, usually cancers. Radiation guns move constantly but target a single area, reducing exposure to the intervening tissues.
- 31: 7 Short-lived radioactive isotopes in benign dosages may also be used as radioactive tracers.
- 31: 8 PET (photon emission tomography) allows medical technicians to explore soft tissue damage that cannot be traced using X-ray technologies. Radioactive isotopes are administered intravenously in substances that collect in specific tissues, highlighting distortions.
- 31: 9 NMR and MRI technologies add to soft tissue mapping capabilities. At safe dosage levels, these techniques provide doctors with diagnostic information that could otherwise only be obtained through exploratory surgery.
All of these methods highlight the fact that human vision is limited to a very small part of the electromagnetic spectrum, and that while some substances may be opaque in that range, the same substances may be transparent to other parts of the spectrum, allowing us to see through walls...and soft tissue.
Units used in radiation measurements:
- 1 Gray = 1 Joule/kg = 100 rad
- effective dose in "rad equivalents for a man" or rem units = dose * RBE of particle
- effective dose in Sv (sievert) units = dose in GY * RBE
- 1 Sv = 100 rem
Read the following weblecture before chat: Radioactive Tracers
Chat Preparation Activities
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