Chapter 9

Identify the sources of ionizing radiation

Natural (background), human made (artificial)

List units used to measure radiation exposure and their correct use

1. Rad (gray)
2. Siervert (rem)
3. Air Kerma
4. Curie (becquerel)
5. Roentgen (R)

Roentgen

a measure of radiation in air

Rad/ Gray (Gy)

used to measure the absorbed amount of energy

Rem (Sievert)

Unit of dose equivalent

Air Kerma

kinetic energy released in matter

Curie (Bacquerel)

Rate at which a radionuclide decays (activity)

Explain ways ionizing radiation interacts with matter

1. Classic coherent scattering
2. Photoelectric interaction
3. Compton scattering
4. Pair production
5. Photodisintegration

Classic Coherent Scattering

interaction with matter in which a low-energy photon (below 10 kiloelectron volts) strikes atom and is absorbed and released with its same energy, frequency, and wavelength but with a change of direction

Photoelectric Interaction

interaction with matter in which a photon strikes an inner shell electron, causing its ejection from orbit with the complete absorption of the photon's energy

Compton scattering

Interaction with matter in which a higher energy photon strikes a loosely bound outer electron, removing it from its shell, and the remaining energy is released as a scattered photon in different direction

Pair production

interaction between matter and a photon possessing a minimum of 1.02 million electron volts of energy approaches the nucleus of an atom, producing two oppositely charged particles, a positron and a negatron

Photodisintegration

direct interaction with the nucleus of the atom, causing a state of excitement within the nucleus, followed by the emission of a nuclear fragment

List the permissible limits of exposure for occupational exposure and the general public

Occupational: 50 msv (5 rem) annually
10 msv (1 rem) x age cumulative
General public: 5 msv (0.5 rem)

Explain the reason for the varying sensitivity of human cells to ionizing radiation

Cells are most sensitive in active division
Basal cells of skin
Crypt cells of small intestine
Germ cells

Cells resistant to radiation

nerve, muscle, and brain cells

Describe the ways in which the entire body responds to varying amounts of radiation

Cells- cell death, delayed mitosis, altered mitotic rate
Whole body- acute radiation syndrome- total body response defined by the system most affected

Discuss various practices used to protect the patient from excessive radiation

ALARA- as low as reasonably achievable
Time- minimize
Distance- maximize
Shielding
Filtration
X-ray beam restriction

Discuss the various approaches used to protect an occupational worker from excess radiation

Time- spend least amount of time in room while radiation active
Distance-double distance between you and source of radiation
Shielding

Describe several devices used to detect and measure exposure to ionizing radiation

Dosimeters