RT Cheat Sheet 2026

The 30 highest-yield RT facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which finding would most concern a therapist treating a patient with vertebral bone metastases? → New leg weakness and loss of bladder control
2. Which ethical principle is most directly applicable to documentation standards? → Beneficence — acting in the patient's best interest
3. Which data element must be updated in the daily treatment record after each fraction? → Cumulative dose delivered to the prescription point
4. An area where a person could receive more than 1 mSv (100 mrem) in one hour at 30 cm from the source must be posted as what? → High Radiation Area
5. What role does documentation play in clinical assessment methods? → It is a critical legal and clinical requirement
6. A radiation therapist declares her pregnancy in writing. What is the NRC dose limit to the embryo/fetus for the entire gestation period? → 5 mSv (0.5 rem)
7. For megavoltage photons, the dose to tissue just beyond a large section of lung is generally: → Higher than in a homogeneous water calculation
8. Which pair of identifiers meets the Joint Commission requirement for verifying a patient before treatment? → Full name and date of birth
9. Why is the use of patient positioning in radiation therapy important? → To ensure accurate delivery of radiation to the treatment area.
10. When a lead apron is worn, where should a single personnel dosimeter be placed? → At the collar outside the apron
11. How can radiation therapists ensure patient comfort during treatment? → By providing a comfortable position and explaining the procedure.
12. A beam is calibrated at 100 cm. Approximately what fraction of the dose rate is delivered at 110 cm, based on the inverse square law? → 0.826
13. In the linear-quadratic model S = e^(–αD – βD²), the αD (linear) component represents: → Single-hit (single-track) lethal cell killing
14. ICRU Report 50 recommends that the dose across the PTV stay within: → +7% and -5% of the prescribed dose
15. How often should patients be monitored during radiation therapy? → Before and after each treatment session.
16. What is the standard of care requirement for medical ethics and law in clinical practice? → The level of care a reasonably competent practitioner would provide
17. ICRU Report 83 recommends reporting which dose as the 'near-maximum' dose? → D2%
18. Which dosimetric quantity is most commonly used for monitor unit calculations in an isocentric (SAD) setup? → Tissue-maximum ratio (TMR)
19. When matching two adjacent fields on the skin, the gap is calculated to make the fields meet: → At a chosen depth inside the patient
20. Which ethical principle is most directly applicable to pharmacology basics? → Beneficence — acting in the patient's best interest
21. A patient misses three scheduled treatments because of hospitalization. How should this be documented? → Record the interruption, the dates missed, and the reason in the treatment record
22. Which phase of the cell cycle is considered MOST radiosensitive? → M phase (mitosis)
23. What is the equivalent square of a 10 cm x 20 cm rectangular field using the area/perimeter (4A/P) method? → 13.3 cm
24. How does radiation shielding contribute to safety in radiation therapy? → It reduces the radiation exposure to surrounding tissues.
25. What is the purpose of treatment planning in radiation therapy? → To ensure the radiation dose is sufficient but safe for the patient.
26. In linear accelerator vault design, which barrier is struck directly by the useful beam? → Primary barrier
27. Why is post-treatment care important in radiation therapy? → To support the healing process and manage side effects.
28. A diabetic patient becomes sweaty, shaky, and confused while waiting for treatment. The most likely cause is: → Hypoglycemia
29. Before the first treatment of a new plan, which verification is normally documented? → Physician review and approval of the initial setup verification images
30. Why is communication important between a radiation therapist and the patient? → To reassure and educate the patient about the treatment.