Safety · ARRT Radiography
Radiation Protection
Occupational dose limits, TLD vs OSL dosimeters, apron lead equivalents, fluoroscopy dose rules, and why routine gonadal shielding is no longer recommended by AAPM and NCRP and is not named on the ARRT outline.
Overview
Radiation Protection is the most number-heavy chapter in the guide, and the numbers are the work. The occupational limits printed in Bushong and Sherer from NCRP lead: 50 mSv effective dose per year whole body, 150 mSv for the lens of the eye, 500 mSv for skin, hands and feet (Bushong also lists thyroid; Sherer's NCRP table does not), and a cumulative limit of 10 mSv times age in years. The lens figure needs a caveat: 150 mSv is NCRP Report 116 and the federal figure in 10 CFR 20.1201, but NCRP has since recommended lowering its limit to an absorbed dose of 50 mGy per year (Commentary 26). Ask your program which figure it teaches. A declared pregnancy adds 5 mSv for the whole gestation with 0.5 mSv in any single month, and the public limit for frequent exposure is 1 mSv per year.
Dosimetry sorts by sensor and stimulus. The TLD pairs lithium fluoride with heat; the OSL pairs aluminum oxide with laser light and reads down to 10 µSv; direct ion storage is new on the 2027 specifications. During fluoroscopy the badge goes on the collar outside the apron, and the books disagree on estimating effective dose from the collar reading: Bushong multiplies by 0.1, Bontrager by 0.3. Use the factor your program or the question gives.
Occupational protection is time, distance, and shielding, and doubling your distance cuts intensity to a quarter. In fluoroscopy, apparel minimums run 0.5 mm lead equivalent for aprons and thyroid shields, 0.35 for glasses and 0.25 for gloves; the general apron floor is 0.25 mm. Fluoroscopy and mobile work account for at least 95 percent of a technologist's occupational dose, and Bushong (2017) says the CDRH treats any skin dose over 15 Gy as a sentinel event that must be reported; follow your facility's current policy. Patient dose falls with high kVp and low mAs, tight collimation, and leaving out the grid on body parts under 10 cm, a request of the Image Gently campaign.
The headline change is a deletion: routine patient gonadal and fetal shielding has been moved away from through the AAPM's 2019 statement, NCRP Statement 13 in 2021 and the FDA's 2023 rule change, and neither the 2022 nor the 2027 content specifications lists it. Adoption varies by state and institution, and ARRT says students should still be taught about shielding. Shields obscure anatomy and can fool the AEC into raising dose. Occupational shielding is untouched, and Image Gently for children and Image Wisely for adults still set the culture.
What you’ll learn in this chapter
The 21 study slides and 18 quiz questions in this chapter break down as follows. 3 chapters are free in full with a free account. The others come with a paid plan, and paid plans open soon.
Radiation Safety
- Radiation Protection
Dose limits
- Occupational Dose Limits
- Quiz
- Where the Limits Came From
- Quiz
- The Pregnant Radiographer
Dosimetry
- The Dosimeters
- Quiz
- Where the Badge Goes
- Reading the Report
- Quiz
Protection
- The Cardinal Rules
- Quiz
- The Inverse Square Law
- Quiz
Shielding
- Protective Apparel
- Quiz
- The Fluoroscopy Room
- Quiz
- Protective Barriers
- Quiz
Population dose
- Where the Dose Comes From
Patient dose
- Technical Factors
- Quiz
- Beam Restriction and Filtration
- Grids, Receptors and the Repeat
Fluoroscopy
- Dose Reduction in Fluoroscopy
- Quiz
- Measuring and Recording the Dose
- Quiz
The shielding change
- Gonadal Shielding Has Been Removed
- Quiz
Campaigns
- Image Wisely and Image Gently
Recap
- What to Carry Out of This Chapter
- Quiz
- Quiz
- Quiz
- Quiz
- Quiz
Key terms in this chapter
These are 8 key terms from this chapter. Use them as a flashcard pre-quiz.
- Occupational Dose Limits
- As printed in Bushong and Sherer from NCRP: 50 mSv effective dose per year whole body, 150 mSv for the lens, 500 mSv for skin and extremities (Bushong adds thyroid), with a cumulative limit of 10 mSv times age in years. NCRP has since recommended lowering the lens limit to 50 mGy per year (Commentary 26), while 10 CFR 20.1201 still says 150 mSv.
- ALARA
- As Low As Reasonably Achievable. Because the linear nonthreshold model assumes no dose is free of risk, exposure is minimized rather than merely kept under a ceiling.
- Optically Stimulated Luminescence (OSL) Dosimeter
- An aluminum oxide sensor read out with laser light. It detects down to 10 µSv, can be re-analyzed to confirm a dose, and may be worn up to a year.
- Inverse Square Law
- Radiation intensity falls with the square of the distance from a point source. Doubling your distance cuts intensity to one quarter.
- Lead Equivalents
- For fluoroscopy, protective aprons and thyroid shields require at least 0.5 mm Pb equivalent, lead glasses 0.35 mm, and lead gloves 0.25 mm. Outside fluoroscopy an apron needs at least 0.25 mm.
- Secondary Protective Barrier
- A barrier against scatter and leakage only, which needs less lead or concrete than a primary barrier. The control booth is one, because the useful beam is never aimed at it.
- Declared Pregnancy
- A voluntary written declaration that triggers a fetal limit of 5 mSv for the gestation and 0.5 mSv in any month, plus a second monitor worn at the waist under the apron.
- Image Gently and Image Wisely
- Education campaigns, not regulations. Image Gently (developed 2007) targets pediatric dose with child-sized technique; Image Wisely (2010) targets adult imaging optimization.
Sample practice question: Radiation Protection
One free sample question from the Radiation Protection subcategory, like those in its 317-question bank. Several chapters share each sample, so it may not match this chapter's topic. See the format, the rationale style, and the difficulty before you sign up.
A radiographer is performing a portable chest x-ray. The patient cannot be moved from the bed. What is the minimum distance the radiographer should stand from the x-ray tube during exposure?
Show answer and rationale
A, Incorrect: 3 feet is too close. Intensity falls with the square of distance, so short distances cost the most.
B, Correct: Correct. Bushong says the exposure switch of a mobile unit must let the operator remain at least 2 m from the x-ray tube, and Sherer says 2 m from the patient, the tube and the useful beam. Bontrager gives a minimum of 6 feet (2 m) from the tube for C-arm work. 6 feet is slightly under 2 m, so use 2 m. Keep the useful beam directed away from you.
C, Incorrect: An apron should be assigned to each mobile unit, but it does not replace distance.
D, Incorrect: More distance is safer, but the minimum Bushong and Sherer state is 2 m.
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Frequently asked questions
What does the Radiation Protection chapter cover?
Radiation Protection is the most number-heavy chapter in the guide, and the numbers are the work. The occupational limits printed in Bushong and Sherer from NCRP lead: 50 mSv effective dose per year whole body, 150 mSv for the lens of the eye, 500 mSv for skin, hands and feet (Bushong also lists thyroid; Sherer's NCRP table does not), and a cumulative limit of 10 mSv times age in years. The lens figure needs a caveat: 150 mSv is NCRP Report 116 and the federal figure in 10 CFR 20.1201, but NCRP has since recommended lowering its limit to an absorbed dose of 50 mGy per year (Commentary 26). Ask your program which figure it teaches. A declared pregnancy adds 5 mSv for the whole gestation with 0.5 mSv in any single month, and the public limit for frequent exposure is 1 mSv per year.
How many study slides are in the Radiation Protection chapter?
This chapter has 21 study slides and 18 quiz questions across 11 sections. The full chapter comes with a paid plan, and paid plans open soon. The free tier includes 3 complete chapters.
Is this chapter aligned with the current ARRT Content Specifications?
Every chapter on this site is mapped to the ARRT Radiography Content Specifications, but our line-by-line check against ARRT's outline isn't finished, so keep ARRT's outline beside it. Nothing here follows your exam date, so check which version applies to you. This chapter falls under the Safety domain of the official ARRT exam blueprint.