CMD Cheat Sheet 2026

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

1. Which principle of radiation protection requires that doses be kept as low as reasonably achievable? → ALARA
2. Which radiation monitoring device provides the most accurate measurement of cumulative whole-body dose for regulatory compliance purposes? → Optically stimulated luminescence (OSL) dosimeter
3. For lung cancer radiotherapy, what is a key pulmonary dose-volume constraint used to predict radiation pneumonitis risk? → Mean lung dose (MLD) ≤ 20 Gy
4. Which of the following is a component of quality assurance in radiation therapy? → Routine maintenance and calibration of equipment
5. Which quality improvement method is most applicable to quality assurance & performance improvement in Certified Medical Dosimetrist? → Plan-Do-Check-Act (PDCA) continuous improvement cycle
6. Which staging system is most commonly used for lung cancer to define target volumes in radiation therapy planning? → AJCC TNM staging
7. When using respiratory gating for lung SBRT, the treatment beam is delivered during: → A defined phase or amplitude range of the respiratory cycle
8. What is the unit of absorbed dose in the SI system used in radiation therapy dosimetry? → Gray (Gy)
9. In IMRT planning, what is the primary purpose of using a dose-volume histogram (DVH)? → To summarize dose distribution statistics for structures
10. Which contouring structure type is used in treatment planning to expand a target volume to account for subclinical disease extension? → Clinical Target Volume (CTV)
11. A patient has a Pd-103 prostate seed implant. When should radiation precautions for family members typically be lifted based on residual activity? → After the activity decays to < 1.11 MBq (30 μCi) per the NRC release criteria
12. What is the primary purpose of a dosimeter in radiation safety? → To measure radiation dose received by personnel
13. Which QA procedure verifies that a treatment plan correctly accounts for tissue heterogeneity in the presence of lung tissue? → End-to-end test using an anthropomorphic heterogeneous phantom
14. Which physical process is dominant for photon interactions in tissue at megavoltage energies used in radiation therapy? → Compton scattering
15. What is the design goal (P) for uncontrolled areas used in NCRP 151 shielding calculations? → 1 mSv/week
16. In the linear-quadratic (LQ) model, the α/β ratio for late-responding normal tissues is typically: → 2–3 Gy
17. How does continuing education relate to evidence-based practice & research methods for CMD certified professionals? → It ensures professionals stay current with evolving standards and best practices
18. How does continuing education relate to professional ethics & legal compliance for CMD certified professionals? → It ensures professionals stay current with evolving standards and best practices
19. Tissue weighting factors (wT) in radiation protection are used to calculate: → Effective dose
20. What is the lens of the eye annual dose equivalent limit for radiation workers per NRC regulations? → 150 mSv
21. What is the primary purpose of communication & interprofessional collaboration in the context of Certified Medical Dosimetrist? → To ensure consistent quality and professional accountability
22. In brachytherapy, the term 'dose rate constant' (Λ) for a source is defined as the dose rate at: → 1 cm in water per unit air kerma strength at 1 cm in air
23. A dosimetrist observes that a patient's performance status has visibly declined since the last simulation visit. The appropriate action is to: → Alert the radiation oncologist and document the observation in the patient's record
24. Why is patient confidentiality critical in radiation therapy? → To maintain patient trust and meet legal requirements
25. Which imaging modality is most commonly used for radiation therapy simulation and treatment planning due to its electron density information? → CT (Computed Tomography)
26. In a linac vault, which component is primarily responsible for generating neutrons during high-energy photon treatments? → Photonuclear reactions in the target and collimators
27. What ethical consideration is most relevant to evidence-based practice & research methods in CMD practice? → Maintaining confidentiality and acting in the best interest of stakeholders
28. Why are a patient's arms positioned above the head during CT simulation for breast cancer treatment? → To move the arms and shoulders out of the planned tangential beam paths
29. How should a CMD professional handle a situation where quality assurance & performance improvement protocols conflict with practical constraints? → Document the conflict and seek guidance from appropriate authorities
30. Which parameter is measured by the 'garden fence' or 'picket fence' test and what tolerance is typically applied? → MLC leaf positional accuracy; tolerance of 1 mm per leaf