Credential: CMD via MDCB | Format: ~155 questions (MCQ + some performance-based / contouring), scaled score 600/800 to pass
This is the “can you be trusted with planning real cancer treatments?” exam.
Think in the way you actually work:
External beam dose calculation & algorithms
Pencil beam vs convolution–superposition vs Monte Carlo: when they’re used and limits.
Heterogeneity corrections, SSD/SAD, tissue–air ratios, MU calcs logic (you don’t need to be a TG-51 robot, but you need to know what changes dose and why).
Beam modifying devices & field design
Wedges, bolus, compensators, blocks, MLC shaping.
How these change depth dose, surface dose, and hot/cold spots.
Treatment planning for common sites
Breast, prostate, lung, H&N, pelvis, CNS, palliative fields.
3D-CRT vs IMRT/VMAT vs electrons: which, when, and what trade-offs.
OAR constraints, PTV coverage, common dose/fractionation patterns.
Imaging, contouring, and registration
CT simulation basics, image fusion with MR/PET.
GTV/CTV/PTV concepts; contouring pitfalls (e.g., missing slices, including immobilisation devices).
Plan evaluation & QA
DVH interpretation, homogeneity & conformity indices.
Plan checking checklists, secondary MU checks, chart rounds.
Radiation protection & regulations
Basics of shielding, workload concepts, patient ID, timeout procedures, documentation.
The MDCB explicitly mentions that the exam blueprint is built around these competency areas, and that performance-based (PBT) questions include both complex multiple choice and contouring items.
Thinking like a calculator instead of a planner — the exam wants decisions and trade-offs, not just numbers.
Over-focusing on rare techniques and under-preparing bread-and-butter sites and VMAT/IMRT patterns.
Under-estimating the performance-based questions: you need to recognise good vs unsafe choice of fields/contours.
Forgetting documentation: timeouts, sign-offs, what must be in the record.
CMD exam: ~155 questions, including performance-based items, in a single session; scaled score required ≥600/800 to pass.
Practical pacing:
Aim for ~1–1.25 minutes per question, allowing a bit more time on PBT/contour-style items.
Two mixed blocks of 60–70 questions each day, including PBT-style practice if available.
For each major disease site you see in clinic, jot:
Typical dose/fractionation.
Key OARs + priority constraints.
Usual field / beam arrangement logic and IMRT/VMAT “red flag” patterns.
Quick visual review:
10–15 plans/DVHs:
Ask: “What’s good here?” and “What would I flag in chart rounds?”
On every scenario:
What is being treated and with what intent? (curative vs palliative; what stage/site).
What is the main clinical risk in this plan? (underdosing target, overdosing cord, heart, lung, bowel, kidney, etc.).
What is my lever? (change beam arrangement, modulation, weighting, energy, bolus, margins).
How would I explain this to the oncologist?
“This change improves PTV coverage but pushes bowel from 35 Gy to 42 Gy; here’s the DVH.”
On multiple choice, kill any option that:
Clearly violates standard OAR limits (where the stem told you they’re a concern).
Makes a plan more complex without an obvious dosimetric benefit.
For contour/plan-evaluation style items:
Look first for gross errors (missed target, wrong laterality, OAR obviously overdosed), then refine.
When two options seem safe, ask:
“Which one respects both coverage and practicality?” — clinic-real answers beat academic tricks.
Short warm-up: 10–15 plan snippets / DVH screenshots with rapid “safe/not safe” calls.
In exam:
Tag questions that require working through a full scenario; don’t drown early.
Protect the last 10–15 minutes for reviewing flagged items and calculation-heavy questions.
Headline in your mind:
“Would I sign my name to this plan if it were a real patient?”
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