Radiation biology and protection practice

67 Gulf Prometric Radiographer (DHA, DOH, MOH, SCFHS, QCHP) practice questions on Radiation biology and protection practice, part of Radiation Protection. The first 25 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

1. Question 1 · Medium

   The ICRP nominal risk coefficient for radiation-induced cancer and heritable effects (detriment) is about:

   1. A50% per sievert
   2. B5% per sievert
   3. C0.5% per sievert
   4. D0.05% per sievert

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   Answer: B · 5% per sievert

   The ICRP 103 nominal detriment-adjusted risk is about 5.7% per sievert for a whole population and about 4.2% for adult workers, usually rounded to 5% per Sv. It is applied to populations and not to a single person.

   • A: 50% per sievert is ten times too high.
   • C: 0.5% per sievert is ten times too low.
   • D: 0.05% per sievert is a hundred times too low.

   Remember this

   The nominal risk is about 5% per sievert.

2. Question 2 · Medium

   Which technique change best applies optimisation to a paediatric chest radiograph?

   1. AA grid with a high mAs to improve contrast
   2. BA large field to include the abdomen
   3. CA short exposure time with tight collimation and no grid
   4. DA long exposure time to cut kVp

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   Answer: C · A short exposure time with tight collimation and no grid

   Children have small bodies and produce little scatter, so a grid is not needed and would only increase dose. A short exposure prevents motion blur, and tight collimation limits the volume irradiated and the dose to sensitive organs.

   • A: A grid with a high mAs would raise dose, with little benefit in a small patient.
   • B: A large field irradiates organs that are not of interest.
   • D: A long exposure causes motion blur, which risks a repeat.

   Remember this

   Paediatric optimisation uses short exposures, tight collimation and usually no grid.

3. Question 3 · Hard

   Scatter around a fluoroscopy table is 0.8 mSv per hour at 1 m from the patient. A nurse stands 2 m away for 45 minutes. Using the inverse square law, her dose is:

   1. A0.075 mSv
   2. B0.15 mSv
   3. C0.3 mSv
   4. D0.6 mSv

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   Answer: B · 0.15 mSv

   At 2 m the rate is 0.8 x (1/2)^2 = 0.2 mSv per hour. For 45 minutes (0.75 h) the dose is 0.2 x 0.75 = 0.15 mSv. Doubling the distance and shortening the time both help.

   • A: 0.075 mSv wrongly assumes the rate at 2 m is 0.1 mSv per hour.
   • C: 0.3 mSv results from halving the rate instead of quartering it.
   • D: 0.6 mSv ignores the distance correction.

   Remember this

   Dose equals dose rate times time, with the rate corrected by the inverse square of distance.

4. Question 4 · Hard

   A radiographer declares pregnancy and six months of pregnancy remain. Her abdominal badge (under the apron) has read 0.2 mSv per month. The department applies a limit of 1 mSv to the fetus for the rest of the pregnancy. The best action is to:

   1. AStop her badge, since she is no longer exposed
   2. BWait until the badge shows 1 mSv, then act
   3. CContinue unchanged, as 0.2 mSv per month is below the 20 mSv annual limit
   4. DReassign her to lower-dose duties, since the projected 1.2 mSv exceeds the limit

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   Answer: D · Reassign her to lower-dose duties, since the projected 1.2 mSv exceeds the limit

   Six months at 0.2 mSv per month projects to 1.2 mSv, which is above the 1 mSv aim for the fetus. Duties should therefore be changed early, for example away from fluoroscopy and mobile work, so the limit is not reached. The general 20 mSv limit does not apply to the fetus.

   • A: Monitoring must continue through the pregnancy.
   • B: Acting only after the limit is reached defeats the purpose of protection.
   • C: The 20 mSv average applies to the worker, not the fetus.

   Remember this

   Project the fetal dose from monthly readings and change duties before the limit is reached.

5. Question 5 · Hard

   An accidental exposure takes place about one week after conception. The expected outcome from the radiation is:

   1. AA high chance of major malformations in the newborn baby
   2. BSevere intellectual disability in most of the surviving babies
   3. CA certain childhood cancer developing in the baby later on
   4. DAn all-or-nothing effect, embryo loss or normal development

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   Answer: D · An all-or-nothing effect, embryo loss or normal development

   Before implantation, each embryonic cell is still able to replace its neighbours. Damage that is large enough kills the embryo and the pregnancy ends, while an embryo that survives usually develops normally. Malformations are the concern later, during organogenesis.

   • A: Malformations occur mainly after implantation, during organogenesis.
   • B: Intellectual disability is linked to exposure at 8 to 15 weeks.
   • C: Cancer is a possible stochastic effect but is not certain.

   Remember this

   Exposure in the first two weeks has an all-or-nothing effect.

6. Question 6 · Easy

   What must be displayed at the entrance of a room where x-ray examinations are performed?

   1. AThe exposure factors used for the day's work
   2. BA list of the patients waiting for examination
   3. CA radiation warning sign (trefoil)
   4. DThe tube manufacturer's name and serial number

   Answer and explanation in LearnFree account

7. Question 7 · Medium

   How should lead aprons be stored to avoid cracks in the shielding material?

   1. AHung on a proper rack or hanger, not folded
   2. BLeft on the floor of the control room
   3. CCrumpled in a locker
   4. DFolded in half on a shelf

   Answer and explanation in LearnFree account

8. Question 8 · Medium

   The stage of pregnancy in which radiation is most likely to cause major malformations is:

   1. AThe first days before implantation
   2. BAll stages equally
   3. CThe last weeks before delivery
   4. DOrganogenesis in early pregnancy

   Answer and explanation in LearnFree account

9. Question 9 · Medium

   A physician in Dubai requests a skull radiograph for a patient with a minor head injury, although current clinical guidelines do not support imaging. The radiographer's best action is to:

   1. ARefuse and tell the patient to go home at once
   2. BPerform the examination without comment or query
   3. CDiscuss the indication with the referrer or a radiologist
   4. DHalve the mAs to cut the dose, then go ahead and expose as asked

   Answer and explanation in LearnFree account

10. Question 10 · Medium

    Compared with x-rays, alpha particles have:

    1. AHigher linear energy transfer and a higher relative biological effectiveness
    2. BGreater penetration in tissue and a lower weighting factor
    3. CLower linear energy transfer and lower relative biological effectiveness
    4. DThe same linear energy transfer but greater penetration

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11. Question 11 · Medium

    On radiation grounds alone, termination of pregnancy is not justified at fetal doses below:

    1. A10 mGy
    2. B1 mGy
    3. C100 mGy
    4. D500 mGy

    Answer and explanation in LearnFree account

12. Question 12 · Medium

    During a long interventional procedure a patient receives about 3 Gy to one area of skin. Redness appears over the next days. This is best described as a:

    1. AStochastic effect, with no threshold
    2. BLate effect unrelated to the dose
    3. CDeterministic effect, which occurs above a threshold of about 2 Gy
    4. DHereditary effect passed to later generations

    Answer and explanation in LearnFree account

13. Question 13 · Hard

    A pregnant trauma patient at 10 weeks needs a CT of the abdomen. The estimated fetal dose is 15 mGy. The best course is to:

    1. APerform the CT, since benefit outweighs the small risk below 100 mGy
    2. BRecommend termination of pregnancy on radiation grounds alone
    3. CRefuse the CT and offer a plain radiograph that cannot answer it
    4. DDelay the CT until after delivery, whatever the mother's condition may be

    Answer and explanation in LearnFree account

14. Question 14 · Medium

    The legal limit for leakage radiation from a diagnostic x-ray tube housing, measured at 1 m from the focus, is:

    1. A1 mGy per minute
    2. B0.1 mGy per hour
    3. C10 mGy per hour
    4. D1 mGy per hour

    Answer and explanation in LearnFree account

15. Question 15 · Medium

    A ceiling-suspended lead acrylic shield is placed between the operator and the patient during an interventional procedure. It mainly protects the operator's:

    1. AEyes and head, which the apron leaves uncovered
    2. BHands, which are in the primary beam during work
    3. CDosimeter badge only, with no benefit to the wearer
    4. DLegs below the knee, which are close to the floor

    Answer and explanation in LearnFree account

16. Question 16 · Easy

    The three fundamental principles of radiation protection in ICRP recommendations are:

    1. ADetection, monitoring and recording
    2. BJustification, optimisation and dose limitation
    3. CJustification, collimation and filtration
    4. DTime, distance and shielding

    Answer and explanation in LearnFree account

17. Question 17 · Medium

    The linear no-threshold (LNT) model, used in radiation protection for stochastic effects, assumes that:

    1. ARisk is zero below 100 mSv
    2. BRisk rises in proportion to dose, with no dose that is completely safe
    3. CRisk falls as the dose is spread over a longer time
    4. DRisk rises only above a threshold dose

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18. Question 18 · Medium

    In radiation protection, a controlled area is typically designated where:

    1. AOnly visitors and patients' relatives are allowed to enter
    2. BAnnual doses are expected to stay below 0.1 mSv for all staff
    3. CNo radiation workers are permitted to enter at any time of day
    4. DDoses could exceed about 6 mSv a year, so access is restricted

    Answer and explanation in LearnFree account

19. Question 19 · Medium

    The operator stands at the control panel of a radiographic room. A correct arrangement is that the radiographer:

    1. AStays beside the patient during the exposure
    2. BStands behind a protective screen and can see and hear the patient
    3. CStands in the doorway with the door open
    4. DStands in the beam path to hold the patient

    Answer and explanation in LearnFree account

20. Question 20 · Hard

    Using a nominal risk of 5% per sievert, the added lifetime risk of fatal cancer and heritable effects from a dose of 20 mSv is about:

    1. A1%, or 1 in 100
    2. B10%, or 1 in 10
    3. C0.1%, or 1 in 1,000
    4. D0.01%, or 1 in 10,000

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21. Question 21 · Easy

    Before an abdominal or pelvic radiograph on a woman of childbearing age, the radiographer should first:

    1. AGive a lead apron to the patient to wear in place of the questions
    2. BRaise the kVp to shorten the exposure
    3. CAsk about the possibility of pregnancy and the date of the last menstrual period
    4. DTake the radiograph and ask later

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22. Question 22 · Medium

    The approximate effective dose from a PA chest radiograph is:

    1. A0.1 mSv or less
    2. B10 mSv
    3. C100 mSv
    4. D1 mSv

    Answer and explanation in LearnFree account

23. Question 23 · Medium

    The ICRP annual equivalent dose limit for the skin and the hands and feet of a radiation worker is:

    1. A20 mSv
    2. B500 mSv
    3. C50 mSv
    4. D150 mSv

    Answer and explanation in LearnFree account

24. Question 24 · Easy

    What does the abbreviation ALARA require of a radiographer's practice?

    1. ADoses are kept as low as radiographers allow
    2. BDoses are kept below the natural background level
    3. CDoses are kept as low as reasonably achievable
    4. DDoses are kept at the annual dose limit

    Answer and explanation in LearnFree account

25. Question 25 · Easy

    A frightened toddler needs a chest radiograph and must be held. The best person to hold the child is:

    1. AA pregnant nurse from the paediatric ward
    2. BA parent or carer wearing a lead apron
    3. CA student radiographer on placement
    4. DThe radiographer performing the examination

    Answer and explanation in LearnFree account