6. Radiation Safety Flashcards
What is the primary source of natural background radiation?
Radon (73%), from uranium-238 in the earth’s crust.
What is the contribution of space radiation to natural exposure?
11%, primarily from high-energy particles from the sun and cosmic rays.
What are examples of terrestrial radiation sources?
Uranium-238, thorium-232, potassium-40 in soil.
What percentage of medical exposure comes from dental radiographs?
About 0.26%.
What is the Linear No-Threshold Hypothesis (LNT) in radiation?
Suggests even low doses may increase cancer risk; not scientifically proven.
What is the justification principle in radiation protection?
Radiographs should only be taken when benefits exceed risks.
What is the ALARA principle?
Keep radiation exposure ‘As Low As Reasonably Achievable.’
What is the purpose of dose limitation in radiation protection?
Prevents harmful occupational and public radiation exposure.
What are patient selection criteria for taking radiographs?
Clinical exams, caries risk, and previous radiographs.
Why use digital sensors and fast-speed films in radiography?
To reduce exposure by using less radiation-sensitive equipment.
How does collimation help reduce X-ray exposure?
Minimizes the exposed area and reduces scatter radiation.
What is the recommended source-to-skin distance for reducing exposure?
20-40 cm (8-16 inches).
What type of filter should be used for machines operating below 70 kVp?
1.5 mm aluminum filter.
What protective measures should personnel take during radiography?
Use aprons, thyroid collars, and film/sensor holders.
How should exposure times and settings be adjusted?
Based on patient size and area being radiographed.
