The ARRT dose limits cheat sheet
Dose limits are pure memorization. No formula rebuilds them for you on exam day. Here is every one the exam expects, and the patterns that make them stick.
Occupational: the radiographer
The numbers for you, wearing the badge.
Public and students
One number, two groups, and that overlap is a favorite distractor. Answer 1 mSv unless the question says infrequent.
Pregnancy: declared
Two numbers, one pregnancy: the monthly limit and the total.
Equipment and regulatory numbers
Not limits on a person, but the same memorize-cold species of number, tested from the same chapters.
| Total beam filtration (above 70 kVp) | ≥ 2.5 mm Al |
| Protective apparel | 0.25 mm Pb minimum · 0.5 mm typical for fluoro |
| Fluoroscopy timer alarm | 5 minutes cumulative |
| Minimum fluoro source-to-skin distance | 38 cm stationary · 30 cm mobile |
| Fluoroscopy tabletop exposure limit | 100 mGy/min · 200 mGy/min with high-level control |
| Standard SIDs | 40 in (100 cm) routine · 72 in (180 cm) chest · 60–72 in lateral C-spine |
| Control booth | a secondary barrier, because the useful beam never points at it |
How to make them stick
- The ladder is 1 → 5 → 50: public 1 mSv, fetus 5 mSv for the pregnancy, occupational 50 mSv for the year.
- The extremity/organ limit is 10× the whole-body limit: 500 vs 50 mSv.
- The fetal monthly limit is a tenth of the fetal total: 0.5 vs 5 mSv.
- A student under 18 is limited like the public (1 mSv), not like staff. Being enrolled does not buy occupational limits.
- 5 mSv is never one limit. It is the fetal total for a whole pregnancy, the public limit for INFREQUENT exposure, and 10% of the adult occupational limit for a minor who is occupationally exposed. Read which one is being asked. If a public question does not say infrequent, the answer is 1 mSv.
Every value verified against the textbooks radiography programs teach from. Updated 20 August 2026.
Questions students ask about dose limits
What is the annual occupational dose limit for radiographers?+
50 mSv (5 rem) effective dose per year, with a cumulative lifetime limit of 10 mSv multiplied by age in years. Equivalent dose to the thyroid, skin, hands, and feet is limited separately at 500 mSv per year.
What is the dose limit for a pregnant radiographer?+
Once a pregnancy is declared, the limit for the embryo/fetus is 0.5 mSv per month and 5 mSv for the entire pregnancy. The monthly limit exists so the total isn't received in one early burst, when radiosensitivity is highest.
What is the public dose limit?+
1 mSv per year of effective dose, one fiftieth of the occupational limit. That is the figure to give unless a question specifically says the exposure is infrequent, in which case the recommended limit is 5 mSv per year. The same 1 mSv figure applies to students under 18, which exams like to test because it means a 17-year-old student does not get occupational limits.
Why does 5 mSv keep showing up?+
Because three unrelated limits happen to share the number: the total for the embryo/fetus across an entire declared pregnancy, the annual public limit for infrequent exposure, and the occupational limit for a minor, which is 10% of the adult limit. Nothing links them. Read which one the question is asking for. If it says the general public and does not say infrequent, the answer is 1 mSv.
Are dose limits in mSv or mrem on the ARRT exam?+
Learn them in millisieverts, since SI units are the primary units on the exam, but be able to convert: 1 mSv is 100 mrem, 1 Sv is 100 rem. The classic pair to have cold: 50 mSv = 5 rem, and 1 mSv = 0.1 rem (100 mrem).
Why is there no lens-of-eye dose limit on this sheet?+
Deliberately. National guidance lowered the lens limit after most current textbook editions went to print, so any single number printed here would be one you would later have to unlearn. Everything on this page is a value you can rely on under exam pressure.
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