AHPC Licensure Examination — Medical Physics

Sample Medical Physics practice questions

Try these 12 questions from different topics. Open "Show answer" to check yourself and read the explanation.

1. Question 1 · Dosimetry & Radiation Quantities

   Which SI unit measures absorbed dose?

   1. A.Sievert per hour only
   2. B.Becquerel
   3. C.Gray
   4. D.Coulomb per kilogram only
   Show answer

   Answer: C. Gray

   The gray is the SI unit of energy deposited per unit mass and is used for absorbed dose.

2. Question 2 · Commissioning & Quality Assurance

   A new radiotherapy treatment unit has been installed. What must occur before clinical treatments begin?

   1. A.Treat the first patient as the test
   2. B.Copy beam data from another model
   3. C.Skip baseline measurements if the unit powers on
   4. D.Acceptance testing, commissioning and documented quality assurance by qualified personnel
   Show answer

   Answer: D. Acceptance testing, commissioning and documented quality assurance by qualified personnel

   Commissioning establishes the clinical beam data, safety and performance baseline required for accurate treatment.

3. Question 3 · Radiation Protection

   Which combination reflects the basic practical methods for reducing occupational external exposure?

   1. A.Reduce time, increase distance and use appropriate shielding
   2. B.Increase time, reduce distance and remove shielding
   3. C.Use shielding only after an incident
   4. D.Rely on warning labels alone
   Show answer

   Answer: A. Reduce time, increase distance and use appropriate shielding

   Time, distance and shielding are core practical controls for external radiation exposure.

4. Question 4 · Atomic & Nuclear Physics

   Isotopes of an element have the same number of:

   1. A.Neutrons but a different number of protons in the nucleus
   2. B.Protons but different numbers of neutrons
   3. C.Electrons and neutrons but different protons
   4. D.Nucleons in total
   Show answer

   Answer: B. Protons but different numbers of neutrons

   The atomic number (Z) defines the element; mass number (A) = protons + neutrons.

5. Question 5 · Interactions of Radiation with Matter

   The photoelectric effect is most likely when:

   1. A.Photon energy is very high and the absorber has a low atomic number
   2. B.The absorber is water at megavoltage energies
   3. C.Photon energy is low and the absorber has a high atomic number
   4. D.Photons exceed 1.022 MeV
   Show answer

   Answer: C. Photon energy is low and the absorber has a high atomic number

   Probability ∝ Z³/E³, which is why it dominates diagnostic contrast between bone and soft tissue.

6. Question 6 · Radiobiology

   The "4 Rs" of radiobiology are repair, repopulation, redistribution and:

   1. A.Resistance, which increases with each fraction delivered
   2. B.Recovery
   3. C.Regression
   4. D.Reoxygenation
   Show answer

   Answer: D. Reoxygenation

   A fifth R, intrinsic radiosensitivity, is often added.

7. Question 7 · Linear Accelerators & Treatment Machines

   In a medical linear accelerator, the magnetron's role is to:

   1. A.Generate microwave power for the waveguide
   2. B.Bend the electron beam through 270° before it hits the target
   3. C.Flatten the photon beam profile
   4. D.Shape the field with leaves
   Show answer

   Answer: A. Generate microwave power for the waveguide

   A klystron does the same job by amplifying microwaves from a low-power driver.

8. Question 8 · Treatment Planning & Dose Calculation

   The internal target volume (ITV) accounts for:

   1. A.Microscopic spread of disease beyond the visible tumour
   2. B.Movement of the CTV due to breathing and organ motion
   3. C.Set-up errors only
   4. D.Dose to organs at risk
   Show answer

   Answer: B. Movement of the CTV due to breathing and organ motion

   ICRU 62 introduced the ITV; the PTV adds set-up margins.

9. Question 9 · Brachytherapy

   Remote afterloading in brachytherapy mainly reduces:

   1. A.The dose delivered to the tumour compared with external beam treatment
   2. B.The treatment time to under one second
   3. C.The need for applicators
   4. D.Radiation exposure to staff
   Show answer

   Answer: D. Radiation exposure to staff

   Sources are moved from a shielded safe into applicators only when staff have left the room.

10. Question 10 · Treatment Delivery & Verification

    A systematic set-up error is one that:

    1. A.Varies randomly from one fraction to the next and averages out
    2. B.Only occurs on the first day
    3. C.Is the same in every fraction
    4. D.Is always smaller than 1 mm
    Show answer

    Answer: C. Is the same in every fraction

    Systematic errors shift the whole dose distribution and need correction.

11. Question 11 · Radiotherapy Side Effects & Patient Care

    Acute skin reactions from radiotherapy usually begin:

    1. A.On the first day of treatment, immediately after the first fraction
    2. B.About 2–3 weeks into treatment
    3. C.Only months after treatment ends
    4. D.Never with megavoltage beams
    Show answer

    Answer: B. About 2–3 weeks into treatment

    Reactions peak towards the end of treatment and in the following 1–2 weeks.

12. Question 12 · Cancer Sites & Techniques

    The standard curative treatment for locally advanced cervical cancer is:

    1. A.Surgery alone followed by observation without any further treatment
    2. B.Chemotherapy alone
    3. C.Chemoradiotherapy followed by brachytherapy
    4. D.Brachytherapy alone
    Show answer

    Answer: C. Chemoradiotherapy followed by brachytherapy

    Cervical cancer is one of the commonest cancers treated in Ghana's radiotherapy centres.