Presentation on theme: "Everything You Need to Know About Radiation Protection Kelli Haynes, MSRS, RT(R) Program Director & Associate Professor."— Presentation transcript:
Everything You Need to Know About Radiation Protection Kelli Haynes, MSRS, RT(R) Program Director & Associate Professor
Radiation Protection 45 questions of the 200 will be radiation protection (22.5%) 10 -Biological Aspects of Radiation 15-Minimizing Patient Exposure 11-Personnel Protection 9-Radiation Exposure and Monitoring
Biological Aspects of Radiation 10 Questions
Cell Radiosensitivity Cells and tissues vary in their degree of radiosensitivity Immature cells are nonspecialized- rapid cell division Mature cells are specialized-divide slower if at all DNA-most radiosensitive part of cell
Dose Response Relationships Graphic representation of the relationship between the amount of radiation absorbed (dose) and the amount of damage (response) Linear or nonlinear Threshold or nonthreshold
Response Dose Linear NonThreshold Linear Threshold
Relative Biologic Effectiveness Measures biologic effectiveness of radiations having different LET’s Influenced by radiation type, cell or tissue type, physiologic condition, and biologic result
Oxygen Enhancement Ratio Response to radiation is greater when irradiated in the oxygenated state Radiation dose required to cause response w/o O2 OER= Radiation dose required to cause response w/ O2
Cell Survival and Recovery LD 50/30 Adults-3-4 Gy ( rad) Recovery may occur
Somatic Effects Biologic damage sustained by living organisms as a consequence of exposure to ionizing radiation Classified as either early (acute) or late
Short-term vs. Long-term Nausea Fatigue Redness of skin Loss of hair Intestinal disorders Fever Blood disorders Shedding skin Cancer Embryologic effects (birth defects) Formation of cataracts
Carcinogenesis The production or origin of cancer Experiments have shown that radiation induces cancer
Cataractogenesis Cataracts-opacity of the eye lens 2 Gy results in partial or complete vision loss Threshold, nonlinear dose-response relationship
Sterility Female sterility based on age of the subject-more radiosensitive when younger Temporary sterility-2 Gray (200rad) Permanent sterility-5 Gray (50 rad)
ACUTE RADIATION SYNDROMES
Hematopoietic Syndrome Whole-body doses ranging from 1 to 10 Gy (100 to 1000 rad) Reduction of blood cells in circulation results in a loss of the body’s ability to clot blood and fight infection
Gastrointestinal Syndrome Appears at a threshold dose of approx. 6 Gy (600 rad) and peaks after a dose of 10 Gy (1000 rad) Without treatment, a dose of 6-10 Gy may cause death in 3-10 days
Cerebrovascular Syndrome Doses of 50 Gray (5000rad) Death within 2 hours or up to 2 days
Embryonic and Fetal Risks Fetus is very sensitive Fetal radiosensitivity decreases as gestation progresses
Genetic Effects GSD-used to assess the impact of gonadal dose Dose equivalent to the reproductive organs that would bring genetic injury to the total population
PHOTON INTERACTIONS WITH MATTER
Coherent Scattering Photon of low energy interacts with atom. No net energy has been absorbed by the atom. Low-energy photons,1-50 kVp Contributes to fog
Compton Scattering Moderate energy x- rays, kVp Interaction with outer shell electron Electron ejected, Atom is ionized Photon loses energy and recombines with an atom Fog and Scatter
Compton Scattering FIGURE 2-6 Compton scattering is responsible for most of the scattered radiation produced during a radiologic procedure. (From Radiobiology and radiation protection: Mosby’s radiographic instructional series, St. Louis, 1999, Mosby.)
Photoelectric Absorption Most important interaction between x-ray photons and the atoms of the pt’s body for producing useful images Higher energy x-rays ( kVp), more likely to penetrate & not interact Interaction b/t photon and inner shell electron X-ray is absorbed Electron ejected
Attenuation Process that decreases the intensity of the beam Refers to both absorption and scatter processes Thickness of body part (mass density) Type of tissue (atomic number)
Minimizing Patient Exposure 15 Questions
Exposure Factors kVp mAs
Shielding Protects gonads when w/i 5 cm of collimated beam Females receive more exposure due to location of organs
Types of Shields Flat contact shields Shadow shields Shaped contact shields Clear lead
NCRP Report #102 Fluoroscopy Exposure Rates General Purpose: 10 R per minute Non-image Intensified: 5 R per minute High Level Control: 20 R per minute Exposure Switch Guidelines Switch must be of the dead-man type
Radiation Exposure and Monitoring 9 Questions
Units of Measurement
Film Badge Economical Parts Monitors x and gamma rays Temperature and humidity can cause fog
Pocket Ionization Chambers Most sensitive Must be charged to zero Accurate from mR
OSL Dosimeter Aluminum oxide detector Optically stimulated luminosity occurs when struck by laser light Accurate reading as low as 1mrem
TLD’s Look similar to film badge Lithium fluoride Ionization causes crystal to change
NCRP #116 Annual occupational effective dose- 50 mSv (5rem) Public Exposure- 1 mSv Embryo/fetus exposure- 50 mSv/month Dosimetry records
NCRP #160 Typical effective dose per exam; varies from 0.1 mSv for a chest xray to 1.5 for a lumbar spine Interventional- ~3mSv CT- range from 2mSv for a head to 10 mSv for a spine
That’s All Folks!
Review Questions What is the most radiosensitive part of the cell? Which is more radiosensitive, immature or mature cells?
This is a picture of what?
Review Questions What is LET? What is LD 50/30? What is an example of an early somatic effect? Late somatic effect? What is carcinogenesis?
Review Questions What is the threshold dose for cataracts? What is the threshold dose for temporary sterility? What is the threshold dose for permanent sterility? What is the threshold dose for cerebrovascular syndrome?
Review Questions What is the threshold dose for hematopoietic syndrome? What is the threshold dose for gastrointestinal syndrome? What are some types of shields? What is filtration? What does NCRP Report # 102 state?
Review Questions Why do we use a grid? What are the 3 sources of radiation exposure? What is the SI unit of measurement for exposure? What is the SI unit of measurement for absorbed dose?
Review Questions What is the traditional unit of measurement for dose equivalent? What is the sensing material in an OSL dosimeter? What is the sensing material in a TLD dosimeter? What does NCRP # 116 state?