CMD Medical Dosimetry Exam Prep

Week 1 — Part 1: Radiation Physics for Dosimetry

Difficulty: Heavy

What it covers: Part 1 establishes the physics foundation every dosimetric calculation depends on — atomic structure and radioactive decay modes, X-ray production via bremsstrahlung and characteristic radiation, the three photon interactions (photoelectric, Compton, pair production), electron beam depth-dose behavior, proton and heavy-particle physics, brachytherapy source physics and the TG-43 formalism, radiation measurement units and detectors, and the inverse square, attenuation, and HVL relationships you will use to solve clinical dosimetry problems.

Print: 1 Mind Map, 3 Comparison Charts, 2 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations (formulas, units, beam properties, anything you calculate) Green: Equipment & Delivery Technology (machines, sources, devices, measurement tools) Purple: Treatment Planning (anything about building, shaping, or evaluating a plan) Yellow: Image Guidance & Motion Management (locating, verifying, or tracking the target) Red: Clinical Oncology & Site-Specific Planning (specific cancers, sites, disease-driven choices) Orange: QA, Safety & Professional Practice (error prevention, dose limits, scope, regulations)

☐ Master the three photon interactions before anything else in this Part. Photoelectric dominates below about 100 keV and scales with Z³, which is why it produces diagnostic contrast but rarely matters at therapy energies. Compton dominates from roughly 100 keV to 10 MeV, depends on electron density (not Z), and is the governing interaction for every megavoltage treatment you will plan. Pair production has a hard threshold at 1.022 MeV and becomes significant above about 10 MeV, contributing annihilation photons that add dose beyond the target. Every beam-physics question on the CMD traces back to one of these three.

☐ Commit the electron beam rules cold. Practical range in cm ≈ E(MeV) / 2. Therapeutic range R90 in cm ≈ E(MeV) / 3.3. Surface dose is 70–95% depending on energy. d_max in cm ≈ E(MeV) / 4. These four relationships let you select a clinical electron energy from the target depth alone — and the CMD will ask you to do exactly that.

☐ Memorize the core reference values: Co-60 gamma energies (1.17 and 1.33 MeV, average 1.25), half-life 5.26 years; Ir-192 half-life 73.83 days with average photon energy approximately 0.38 MeV; photon d_max at 1.5 cm (6 MV), 2.5 cm (10 MV), 3.5 cm (18 MV); pair production threshold 1.022 MeV; radiation weighting factors (photons and electrons = 1, protons = 2, alphas = 20, neutrons = 5–20); HVL = 0.693/µ; proton RBE = 1.1 by international convention.

☐ Practice the TG-43 brachytherapy formalism before the quiz bank. Every HDR dose calculation uses five inputs: air-kerma strength (S_k), dose rate constant (Λ), geometry function G(r,θ), radial dose function g(r), and anisotropy function F(r,θ). The reference point is r₀ = 1 cm, θ₀ = 90° (transverse axis) — every tabulated value you look up is normalized to that point. If the exam hands you a brachytherapy calculation, you are using TG-43.

☐ Complete the Practice Questions for Part 1 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Radiation Physics for Dosimetry. Main branches: Atomic Structure & Radioactive Decay → X-ray Production (bremsstrahlung, characteristic) → Photon Interactions with Matter (photoelectric, Compton, pair production) → Particle Beam Physics (electrons, protons, heavy ions, Bragg peak) → Brachytherapy Source Physics & TG-43 → Radiation Measurement Units (Gy, Sv, C/kg, Bq) → Radiation Detectors (ion chambers, TLDs, OSLDs, diodes, film) → Beam Quality & Energy Specification (PDD, TPR, HVL) → Fundamental Dosimetry Relationships (inverse square, attenuation, decay).

Comparison Charts:

☐ Chart 1 — Photoelectric Effect vs. Compton Scattering vs. Pair Production: Energy range of dominance, Z-dependence, interaction mechanism, clinical relevance in therapy, and scattered radiation produced.

☐ Chart 2 — Photon Beams vs. Electron Beams vs. Proton Beams: Depth-dose pattern, skin sparing behavior, penumbra, typical clinical use, and beam generation mechanism for each modality.

☐ Chart 3 — Ionization Chambers vs. Diode Detectors vs. TLDs: Detection mechanism, energy dependence, spatial resolution, common clinical use, and operational limitations for each dosimeter type.

Cornell Notes:

☐ Page 1 — Cue questions: What are the three dominant photon interactions, and what energy range and Z-dependence characterizes each? Why does Compton dominate in soft tissue at megavoltage energies, and what does that mean for treating bone next to lung? What is the full TG-51 calibration chain from raw electrometer reading to absorbed dose to water, and what tolerance does the protocol require?

☐ Page 2 — Cue questions: What are the electron range rules (Rp, R90, d_max, surface dose) as a function of energy in MeV, and how do you use them to pick an energy for a 2 cm deep chest wall target? What are the five TG-43 factors required for every brachytherapy dose calculation, and what is the reference point (r₀, θ₀) that all tabulated data are normalized to?

Week 2 — Part 2: Radiation Equipment & Technology

Difficulty: Moderate–Heavy

What it covers: Part 2 walks through every piece of hardware that generates, shapes, measures, and delivers a therapy beam. You will learn the linear accelerator from electron gun through waveguide, bending magnets, target, and collimation; multileaf collimator design and leaf sequencing; beam-modifying devices (physical wedges, dynamic wedges, virtual wedges, bolus, compensators); Co-60 teletherapy and orthovoltage units; CT, MRI, and PET simulation workflows with image registration and fusion; HDR and LDR brachytherapy applicators and afterloading systems; and the design principles of proton therapy delivery and robotic radiosurgery platforms.

Print: 1 Mind Map, 3 Comparison Charts, 2 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ Trace the electron path through the linac end to end before you attempt the quiz bank — electron gun → accelerating waveguide (fed by magnetron or klystron microwave source) → bending magnet → target (for photons) or scattering foil (for electrons) → flattening filter → primary collimator → monitor ion chambers → jaws → MLC → patient. Every linac-component question on the CMD maps to one step in this chain, and most distractors target the order or the function of a single piece.

☐ Wedge selection is a recurring test topic. Physical wedges use a metal filter that hardens the beam (higher effective energy), reduce output substantially (wedge factor 0.25–0.75), and come in fixed angles (15°, 30°, 45°, 60°). Dynamic wedges move a single jaw at constant dose rate across the field — no physical filter, no beam hardening, continuously variable angles up to 60°. Virtual (omni) wedges modulate dose rate during jaw motion to achieve the same effect. Know which one is physically in the beam (only the physical wedge) and which one changes the beam's effective energy (only the physical wedge).

☐ Commit the commissioning and daily-QA reference values: linac mechanical isocenter within a 1 mm radius sphere for standard treatments and 0.5 mm for stereotactic, MLC leaf widths typically 5 mm at central isocenter (2.5 mm micro-MLC available), TG-142 daily output constancy tolerance ±3%, laser-to-radiation-isocenter agreement within ±2 mm for conventional and ±1 mm for SRS/SBRT. Co-60 specific activity approximately 1,130 Ci/g producing a larger penumbra than linac beams.

☐ Brachytherapy delivery has its own language. HDR uses a single high-activity Ir-192 source that dwells at programmed positions in a remote afterloader — 24-hour QA, room survey after every treatment, source accountability at every step. LDR uses multiple lower-activity sources (Cs-137, I-125, Pd-103 seeds) placed permanently or temporarily. Applicators vary by site: tandem-and-ovoid for cervix, interstitial needles for soft tissue, intraluminal catheters for bronchus or esophagus.

☐ Complete the Practice Questions for Part 2 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Radiation Equipment & Technology. Main branches: Linear Accelerator Components (electron gun → waveguide → bending magnet → target → flattening filter → collimators → MLC) → Multileaf Collimators (leaf width, tongue-and-groove, leakage) → Beam-Modifying Devices (physical/dynamic/virtual wedges, bolus, compensators) → Co-60 & Orthovoltage Units → CT / MRI / PET Simulation → Image Registration & Fusion (rigid vs. deformable) → Brachytherapy Equipment (HDR afterloaders, LDR sources, applicators) → Proton Therapy Delivery (cyclotron/synchrotron, passive scattering, pencil beam scanning) → Robotic Radiosurgery & Specialty Systems (CyberKnife, Gamma Knife, MR-linac).

Comparison Charts:

☐ Chart 1 — Physical Wedge vs. Dynamic Wedge vs. Virtual (Omni) Wedge: Mechanism, wedge angles available, beam hardening behavior, wedge factor impact on MU, and clinical limitations of each.

☐ Chart 2 — CT Simulation vs. MRI Simulation vs. PET Simulation: Primary dataset use, soft tissue contrast, electron density availability, typical clinical indication for fusion, and key limitation of each modality.

☐ Chart 3 — Passive Scattering Proton Delivery vs. Pencil Beam Scanning: Beam shaping method, dose conformity, neutron contamination, treatment efficiency, and current clinical adoption for each.

Cornell Notes:

☐ Page 1 — Cue questions: What is the full electron path through a linac from gun to patient, and at what component is bremsstrahlung produced for a photon beam? What is the difference between a magnetron and a klystron, and where does each sit in the linac chain? What are the TG-142 daily tolerance values for output, laser alignment, and light/radiation field coincidence?

☐ Page 2 — Cue questions: What are the mechanistic and dosimetric differences between physical, dynamic, and virtual wedges, and which one hardens the beam? What are the five quality checks you should perform on any image fusion dataset before contouring (fiducials, uniformity, soft-tissue agreement, edge artifacts, documentation)?

Week 3 — Part 3: Dosimetry Principles & Calculations

Difficulty: Heavy — High Yield

What it covers: Part 3 is the computational core of the CMD exam. You will work through percentage depth dose, tissue-air ratio, tissue-phantom ratio, and scatter-air ratio; full monitor unit calculations for photons and electrons under both SSD and SAD setups; output factors, equivalent square, Mayneord F-factor, wedge factor, tray factor, and off-axis ratio; bolus thickness calculations for electron beams; heterogeneity corrections and their algorithm dependence; the convolution/superposition, Monte Carlo, and pencil beam dose calculation algorithms; the full TG-43 brachytherapy formalism; and the special calculation considerations for TBI, TSET, stereotactic treatments, and proton therapy.

Print: 1 Mind Map, 4 Comparison Charts, 3 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ You cannot pass the CMD without automatic MU calculations — so build the muscle memory this week. Run the full chain dozens of times until it flows without notes: prescribed dose → choose SSD or SAD geometry → correct for depth (PDD for SSD, TPR for SAD) → apply inverse square if the treatment SSD differs from calibration → layer in output factor (S_c × S_p using the equivalent square) → apply wedge factor, tray factor, off-axis ratio → final MU. The AAPM TG-114 independent check must agree within ±2% (or ±2 MU for low-MU fields).

☐ Lock in the equivalent square formula: side = 4A/P. For an a × b rectangular field the shortcut is 2ab/(a+b). For blocked fields you use the area of the open field shape. This one formula unlocks output factor lookup, PDD lookup, TPR lookup, and wedge factor lookup — the CMD will test it indirectly in almost every MU calculation question.

☐ PDD depth behavior is driven by four factors — distance (SSD), energy, field size, and heterogeneity. Higher SSD raises PDD at depth (less divergence loss). Higher energy raises PDD at depth and shifts d_max deeper (1.5 cm at 6 MV, 2.5 cm at 10 MV, 3.5 cm at 18 MV). Larger field size raises PDD at depth due to increased scatter. Low-density tissue (lung, density 0.25–0.4 g/cm³) raises PDD beyond it. When the CMD asks you to predict how a PDD changes, decide which of these four is shifting.

☐ Know the heterogeneity correction algorithm hierarchy by accuracy. Effective path length (simplest, scales depth by relative density) — fast but misses lateral scatter changes. Ratio of TAR — slightly better, still 1D. Pencil beam — fast, but well known to overestimate dose in lung by 5–15%. Convolution/superposition — handles lateral scatter well, current clinical standard. Monte Carlo — most accurate, handles every interaction stochastically, computationally expensive. Expect a question asking which algorithm you would pick for a lung SBRT plan: Monte Carlo or convolution/superposition, never pencil beam.

☐ Electron MU differs from photon MU. Bolus adds 1 cm of range reduction per 1 cm of bolus. SSD correction changes output about 1% per cm of SSD change. Narrow fields (smaller than Rp) lose lateral scatter equilibrium and both PDD and output drop — verify with measurement before treating. When you select an electron energy, use R90 ≈ E(MeV)/3.3 for target coverage, not Rp/2.

☐ Complete the Practice Questions for Part 3 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Dosimetry Principles & Calculations. Main branches: Dose Metrics (PDD, TAR, TPR, SAR) → Monitor Unit Calculations (SSD setup, SAD setup, photon, electron) → Output & Correction Factors (Sc, Sp, wedge factor, tray factor, off-axis ratio, Mayneord F) → Equivalent Square & Field Size → Bolus for Electron Beams → Heterogeneity Corrections (effective path length, pencil beam, convolution/superposition, Monte Carlo) → Dose Calculation Algorithms → TG-43 Brachytherapy Formalism → Special Calculations (TBI, TSET, stereotactic, proton) → Independent MU Verification (TG-114).

Comparison Charts:

☐ Chart 1 — SSD Setup vs. SAD Setup for Photon MU Calculations: Setup geometry, primary dosimetric quantity used (PDD vs. TPR), inverse square correction requirement, field size definition (surface vs. isocenter), and clinical scenario each is best suited for.

☐ Chart 2 — Photon PDD vs. Electron PDD: Surface dose, d_max behavior with energy, beyond-d_max pattern, field size dependence, and clinical implication for each.

☐ Chart 3 — Pencil Beam vs. Convolution/Superposition vs. Monte Carlo Algorithms: Physical accuracy, lung/air cavity handling, computational demand, typical clinical use, and known limitation for each algorithm.

☐ Chart 4 — TG-43 Formalism Parameters: The five factors (S_k, Λ, G(r,θ), g(r), F(r,θ)), what each physically represents, how each is obtained (measurement vs. calculation), and the reference point (r₀ = 1 cm, θ₀ = 90°) all values normalize to.

Cornell Notes:

☐ Page 1 — Cue questions: What is the full step-by-step MU calculation for a photon treatment with a wedge under SAD setup, and how does the chain change under SSD setup? What is the equivalent square formula, and how do you apply it to an 8 × 20 cm rectangular field? What tolerance must an independent MU check agree to per TG-114?

☐ Page 2 — Cue questions: Which heterogeneity correction algorithm would you choose for a lung SBRT plan and why, and which algorithm is well known to overestimate lung dose? What is the Mayneord F-factor and when is it applied? What electron bolus thickness would you add to a 12 MeV beam to bring the 90% isodose to 3 cm depth?

☐ Page 3 — Cue questions: What are the five TG-43 factors needed for any brachytherapy calculation, and what is the physical meaning of each? What is the reference point (r₀, θ₀) that all TG-43 tabulated data are normalized to? What is the proton RBE convention used in treatment planning, and how is it applied across the SOBP?

Week 4 — Part 4: Treatment Planning — Fundamentals

Difficulty: Heavy — High Yield

What it covers: Part 4 is where dosimetry becomes treatment planning. You will learn the complete simulation-to-approval workflow; ICRU 50, 62, and 83 target volume definitions (GTV, CTV, ITV, PTV, PRV); serial versus parallel OAR architecture and the QUANTEC dose constraints that flow from it; DVH interpretation with conformity, homogeneity, and gradient indices; beam arrangement principles (gantry angle selection, couch rotations, field weighting, isocenter placement); field matching and junction strategies for abutting photon and electron fields; plan normalization and ICRU dose reporting; and the treatment planning system commissioning process.

Print: 1 Mind Map, 4 Comparison Charts, 3 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ The ICRU target volumes are tested directly and repeatedly — draw the nested-volume relationship from memory before the quiz bank. GTV is visible or palpable disease. CTV is GTV plus a biological margin for microscopic extension. ITV is CTV plus an internal-motion margin (the "I" is for Internal — physiological organ motion, not setup). PTV is CTV/ITV plus a geometric setup-uncertainty margin. PRV is the OAR equivalent of PTV — the OAR plus a margin for setup uncertainty. The van Herk recipe for PTV margin is 2.5Σ + 0.7σ, where Σ is systematic and σ is random error standard deviation.

☐ Classify every OAR as serial or parallel before you write dose constraints — the structural architecture dictates the metric you care about. Serial organs (spinal cord, brainstem, optic nerves, optic chiasm, esophagus, small bowel loops) fail catastrophically with any high-dose hotspot, so you constrain D_max or D_0.03cc. Parallel organs (lung, liver, kidneys, parotid) tolerate partial-volume damage because undamaged subunits compensate, so you constrain mean dose and volume-at-dose (V20, V30). Confusing the two guarantees a planning mistake.

☐ Memorize the QUANTEC/QUANTEC-adjacent constraints cold: spinal cord D_max < 45–50 Gy (myelopathy risk < 0.2%); brainstem D_max < 54 Gy; optic nerves and chiasm D_max < 54 Gy; at least one parotid mean < 26 Gy; lung V20 < 30–35% and mean < 20 Gy (pneumonitis risk < 20%); kidneys V20 < 32% bilaterally and mean < 18 Gy each; rectum V70 < 25%; bladder V70 < 35%; femoral heads V50 < 5%. Expect DVH interpretation questions that ask whether a specific plan meets these thresholds.

☐ Read every DVH with the same three questions. (1) Target coverage: V100% ≥ 95% of the PTV — does the prescription isodose cover the target? (2) Conformity and homogeneity: CI = V_Rx / V_PTV ideally near 1.0 (≤ 1.2); HI = (D2% – D98%) / D50% ideally 0.10–0.15 for conventional fractionation (SRS/SBRT plans accept higher HI intentionally). (3) OAR constraints: each OAR below its QUANTEC threshold. ICRU 83 requires you to report D98% (near-minimum), D50% (median), and D2% (near-maximum) for IMRT plans.

☐ Field matching is a high-yield planning skill. The skin gap for abutting diverging fields is gap = (L₁/2)·(d/SSD₁) + (L₂/2)·(d/SSD₂). Feathering the junction (shifting it 1 cm daily) spreads any residual dose inhomogeneity across multiple treatments. Collimator rotation or couch rotation aligns divergent edges. Half-beam blocks eliminate divergence on one side at the cost of some output.

☐ Complete the Practice Questions for Part 4 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Treatment Planning — Fundamentals. Main branches: Simulation Workflow (CT-sim, immobilization, contrast, 4DCT) → ICRU Target Volumes (GTV, CTV, ITV, PTV, PRV) → van Herk PTV Margin Recipe → OAR Structural Types (Serial vs. Parallel) → QUANTEC Dose Constraints → Beam Arrangement Principles (gantry angles, couch rotation, field weighting, isocenter placement) → Field Matching & Junction Strategies → DVH Analysis (D95%, V100%, conformity index, homogeneity index, gradient index) → ICRU Dose Reporting (50/62 vs. 83) → TPS Commissioning (TG-53 tolerance ±2% / ±2 mm).

Comparison Charts:

☐ Chart 1 — GTV vs. CTV vs. ITV vs. PTV vs. PRV: What each volume represents, the type of uncertainty it accounts for (biological vs. motion vs. setup), how the margin is derived, and which structures are contoured versus mathematically expanded.

☐ Chart 2 — Serial OARs vs. Parallel OARs: Functional architecture, dose-limiting metric (D_max vs. mean/Vxx), representative organs, tolerance behavior, and planning strategy for each type.

☐ Chart 3 — Conformity Index vs. Homogeneity Index vs. Gradient Index: Formula, ideal value, what plan quality attribute each measures, and which technique (3DCRT, IMRT, VMAT, SRS/SBRT) it is typically applied to.

☐ Chart 4 — Field Junction Strategies (Feathering, Collimator Rotation, Couch Rotation, Half-Beam Blocks): How each manages divergence, residual hot/cold spot risk, typical clinical application, and dosimetric cost of each approach.

Cornell Notes:

☐ Page 1 — Cue questions: What is the ICRU-recommended nested relationship between GTV, CTV, ITV, PTV, and PRV, and what kind of uncertainty does each expansion account for? What is the van Herk PTV margin recipe, and what does it guarantee dosimetrically? What conditions would make you shrink or expand the PTV margin from the institutional default?

☐ Page 2 — Cue questions: What are the standard QUANTEC constraints for spinal cord, brainstem, parotid (mean), lung (V20, mean), kidney (V20, mean), rectum (V70), and bladder (V70)? How do you read a DVH to verify PTV V100% ≥ 95% and confirm every OAR is below its tolerance? What is the difference between ICRU 50/62 reporting and ICRU 83 reporting for an IMRT plan?

☐ Page 3 — Cue questions: What is the full skin-gap formula for abutting divergent photon fields, and why does it depend on SSD? What does "feathering" a junction accomplish dosimetrically, and how often do you move the junction? What are the TG-53 commissioning tolerances for calculated vs. measured dose in low-gradient and high-gradient regions?

Week 5 — Part 5: Treatment Planning — Advanced Techniques

Difficulty: Heavy — High Yield

What it covers: Part 5 covers every advanced delivery technique tested on the CMD — 3DCRT, IMRT (fixed-field), and VMAT planning; SRS and SBRT planning with their hypofractionated dose constraints and plan quality metrics (Paddick CI, gradient index, R50%, D2cm); intracavitary, interstitial, and prostate brachytherapy planning with HDR and LDR workflows and the GEC-ESTRO targets; TBI planning with extended SSD techniques and lung compensators; proton treatment planning with range uncertainty margins and robust optimization; adaptive radiation therapy triggers and workflows; and the special planning considerations for re-irradiation and pediatric patients.

Print: 1 Mind Map, 4 Comparison Charts, 3 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter. ☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ IMRT, VMAT, SRS, and SBRT are not interchangeable — each solves a different clinical problem. Fixed-field IMRT uses 5–9 static gantry angles with step-and-shoot or sliding-window MLC modulation; treatment time 10–20 minutes beam-on; preferred when specific beam avoidance is critical. VMAT delivers the same modulation across 1–3 continuous arcs; 2–5 minutes beam-on per arc; 10–30% fewer total MU than equivalent IMRT; current standard for most modulated plans. SRS delivers a high single dose to an intracranial target with submillimeter precision. SBRT extends the same high-dose hypofractionated approach to extracranial sites — lung (early NSCLC), liver, spine, prostate in some protocols. Know the delivery technique that best fits each clinical scenario.

☐ Master BED and EQD2 before the quiz bank — they appear on the CMD repeatedly. BED = nd(1 + d/(α/β)). EQD2 = D(d + α/β) / (2 + α/β). Use α/β = 10 Gy for most tumors and acute-responding tissues; α/β = 3 Gy for late-responding tissues (spinal cord, lung fibrosis, brachial plexus); α/β = 1.5–3 Gy for prostate specifically. Anchor benchmarks: 60 Gy / 30 fx = BED₁₀ 72 Gy; 70 Gy / 35 fx = BED₁₀ 84 Gy (definitive H&N level); 50 Gy / 25 fx = BED₁₀ 60 Gy (preop sarcoma, cervix EBRT); 8 Gy × 1 = BED₁₀ 14.4 Gy (single-fraction bone palliation); 54 Gy / 3 fx = BED₁₀ 151.2 Gy (lung SBRT ablative dose).

☐ SBRT spinal cord limits are fraction-number dependent and heavily tested. Single fraction: D_max < 14 Gy. Three fractions: D_max < 21–22 Gy. Five fractions: D_max < 25–30 Gy (protocol-dependent). Paddick CI ≥ 0.85, gradient index < 4.0, R50% within protocol, D2cm within protocol. Patient-specific QA passing rate for SBRT ≥ 90% at 3%/2 mm gamma criteria.

☐ Prostate brachytherapy prescriptions are memorizable numbers: I-125 monotherapy 145 Gy to prescription isodose; Pd-103 monotherapy 125 Gy; post-EBRT boost I-125 110 Gy or Pd-103 100 Gy. For cervical HDR combined with EBRT, HR-CTV D90 ≥ 87 Gy EQD2 (GEC-ESTRO); bladder D2cc < 90 Gy EQD2; rectum D2cc < 75 Gy EQD2; sigmoid D2cc < 75 Gy EQD2. Report everything in EQD2 when courses combine across fractionation.

☐ Proton planning lives and dies by range uncertainty. Proximal/distal range margins are typically 2.5–3.5% of the range plus 1–3 mm. Robust optimization evaluates the plan against ±3–5 mm setup shifts and ±3.5% range uncertainty simultaneously — you are not finished until the plan holds up under worst-case scenarios. Pediatric cases favor protons specifically because the integral dose is 50–60% lower than IMRT, cutting the lifetime secondary malignancy risk. ☐ Complete the Practice Questions for Part 5 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Treatment Planning — Advanced Techniques. Main branches: 3DCRT → IMRT (Fixed-Field, step-and-shoot vs. sliding window) → VMAT (single/multi-arc) → SRS (intracranial, single fraction) → SBRT (extracranial, 1–5 fraction) → Brachytherapy Planning (HDR, LDR, intracavitary, interstitial, prostate) → GEC-ESTRO Cervix Targets → TBI (extended SSD, lung compensators) → Proton Planning (range margin, robust optimization) → Adaptive RT Triggers → Re-Irradiation & Pediatric Planning → BED/EQD2 Math.

Comparison Charts:

☐ Chart 1 — IMRT (Fixed-Field) vs. VMAT: Delivery mechanism, treatment time, total MU, plan quality tradeoffs, and typical clinical scenario where each is preferred.

☐ Chart 2 — SRS vs. SBRT: Anatomical target, fraction-number definition, typical dose per fraction, immobilization, image guidance, and principal clinical indication for each.

☐ Chart 3 — HDR Brachytherapy vs. LDR Brachytherapy: Dose rate definition, typical isotope (Ir-192 vs. I-125/Pd-103/Cs-137), delivery system (afterloader vs. permanent seeds), treatment duration, and representative clinical use. ☐ Chart 4 — Forward Planning vs. Inverse Planning: Who sets beam parameters, how the dose distribution is generated, optimization method, computational demand, and which techniques each supports.

Cornell Notes:

☐ Page 1 — Cue questions: What are the BED and EQD2 formulas, and what α/β ratio do you use for a lung tumor vs. the spinal cord vs. prostate cancer? What is BED₁₀ for 60 Gy / 30 fx, 70 Gy / 35 fx, 8 Gy × 1, and 54 Gy / 3 fx, and which clinical scenarios do those benchmarks represent?

☐ Page 2 — Cue questions: What are the single-fraction, three-fraction, and five-fraction SBRT spinal cord D_max limits? What are the Paddick CI, gradient index, and gamma passing rate thresholds required for an SBRT plan? What is the monotherapy prescription dose for I-125 prostate brachytherapy vs. Pd-103, and what is the post-EBRT boost dose?

☐ Page 3 — Cue questions: What is the GEC-ESTRO HR-CTV D90 target for cervical HDR combined with EBRT, and what are the D2cc limits for bladder, rectum, and sigmoid? What range and setup uncertainties does robust optimization for protons evaluate against, and why is proton therapy preferred for pediatric CNS cases?

Week 6 — Part 6: Image Guidance & Motion Management

Difficulty: Moderate–Heavy

What it covers: Part 6 covers every imaging and motion-management tool the modern dosimetrist relies on — 2D kV/MV portal imaging, kV-CBCT, MV-CBCT, MR-linac imaging, and surface-guided radiation therapy (SGRT); 4DCT simulation with phase sorting, ITV generation, and MIP/MinIP reconstruction; respiratory gating (phase-based and amplitude-based), breath-hold techniques (DIBH, ABC), abdominal compression, and real-time tumor tracking; rigid and deformable image registration with quality metrics; and online, offline, and plan-of-the-day adaptive replanning workflows.

Print: 1 Mind Map, 3 Comparison Charts, 2 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ Understand the kV vs. MV imaging tradeoff before anything else in this Part. kV-CBCT uses 80–140 kVp photons with a separate kV source mounted orthogonally to the treatment head — superior soft-tissue contrast (photoelectric dominates at diagnostic energies), per-scan dose typically 1–25 mGy, and the standard for daily soft-tissue matching. MV-CBCT uses the treatment beam itself (2.5–6 MV), Compton-dominated, excellent for bony anatomy and for cases where kV artifacts from metal implants make soft-tissue matching impossible, at higher per-scan dose. Pick kV when you are matching to soft tissue; pick MV when metal implants corrupt the kV image.

☐ Motion management strategy follows from 4DCT motion amplitude, not preference. If peak-to-peak tumor motion is < 5 mm, an ITV approach (from 4DCT phase bins) is often sufficient with no active motion management. 5–10 mm motion — consider respiratory gating or abdominal compression. > 10 mm motion — breath hold (DIBH for cooperative patients, especially left breast for cardiac sparing, or liver and lung), active breathing control, or real-time tracking (CyberKnife for lung/liver, dynamic MLC tracking on advanced linacs). Always match the strategy to both the tumor motion and 

the patient's ability to comply.

☐ 4DCT phase-sorting quality checks are tested. Verify all 10 phase bins are correctly sorted with smooth motion between consecutive phases. Check for hysteresis (residual motion differences between inhalation and exhalation at the same amplitude). Look for duplicate structures, blurring, or missing anatomy that signal irregular breathing. Measure peak-to-peak tumor displacement in all three axes before you build the ITV. If the trace is irregular, coach the patient and rescan — a bad 4DCT makes a bad plan.

☐ Know when adaptive replanning is triggered. Anatomy shift — visible tumor shrinkage or OAR displacement on CBCT. Dose deviation — accumulated dose diverging from the planned distribution. Atelectasis or effusion — new or resolved fluid/collapse changing tissue density. Patient habitus — weight loss or gain changing body contour and beam path. Timeline — standard checkpoints are one-third and two-thirds through treatment. Online adaptive (ART) creates a new plan at the machine using same-day imaging (ideal for bladder/rectum/cervix); offline adaptive reviews accumulated data between fractions; plan-of-the-day selects the best pre-made plan from a library.

☐ Complete the Practice Questions for Part 6 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Image Guidance & Motion Management. Main branches: 2D kV/MV Portal Imaging → kV-CBCT vs. MV-CBCT → MR-Linac Imaging → Surface-Guided Radiation Therapy (SGRT) → 4DCT Simulation (phase sorting, ITV generation, MIP/MinIP) → Respiratory Motion Management (gating, breath hold, compression, tracking) → Rigid vs. Deformable Image Registration → Adaptive Radiation Therapy (online, offline, plan-of-the-day) → Fiducial Markers & Implanted Surrogates.

Comparison Charts:

☐ Chart 1 — kV-CBCT vs. MV-CBCT: Imaging energy, soft-tissue contrast mechanism (photoelectric vs. Compton), per-scan dose, artifact behavior (scatter, metal streaking), and preferred clinical use for each.

☐ Chart 2 — Motion Management Strategies (Breath Hold vs. Respiratory Gating vs. Abdominal Compression vs. Real-Time Tracking): Motion amplitude range each handles best, patient cooperation requirement, equipment needed, dosimetric benefit, and representative clinical scenario.

☐ Chart 3 — Online Adaptive vs. Offline Adaptive vs. Plan-of-the-Day: Trigger, replanning timing (same-day vs. between fractions vs. pre-selected library), clinical sites that benefit most, workflow efficiency, and QA considerations for each.

Cornell Notes:

☐ Page 1 — Cue questions: What are the differences in imaging energy, soft-tissue contrast, and per-scan dose between kV-CBCT and MV-CBCT, and when would you choose one over the other? What are the five 4DCT quality checks you perform before using the dataset for planning?

☐ Page 2 — Cue questions: How do you select a motion-management strategy based on peak-to-peak tumor motion amplitude, and which strategy is the standard choice for a left-sided breast patient? What are the five clinical triggers for adaptive replanning, and what is the difference between online, offline, and plan-of-the-day adaptive approaches?

Week 7 — Part 7: Clinical Oncology for Dosimetrists

Difficulty: Heavy — High Yield

What it covers: Part 7 ties cancer biology, staging, and site-specific planning together into the clinical knowledge the CMD tests most heavily. You will work through the cell cycle and radiation-induced cell death, the Four Rs of radiobiology, the oxygen enhancement ratio, α/β ratios and the Linear Quadratic Model, BED and EQD2 calculations for fractionation comparison, TNM staging, curative versus palliative intent, and the site-specific dose prescriptions, critical OAR constraints, and standard beam arrangements for brain, head and neck, breast, lung, GI, prostate, gynecologic, lymphoma, bone metastases, pediatric, and sarcoma treatment sites.

Print: 1 Mind Map, 4 Comparison Charts, 3 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ Lock in the Four Rs of radiobiology before you touch a clinical question — Repair (normal cells repair sublethal damage between fractions more efficiently than tumor cells; the core justification for fractionation), Reassortment (tumor cells redistribute into radiosensitive G2/M phases between fractions), Repopulation (tumor and normal tissue proliferate between fractions; prolonging treatment time helps normal tissue recovery but lets tumors repopulate — about 0.6 Gy of effect per extra day of treatment break in H&N after week 4), and Reoxygenation (hypoxic tumor cells gain oxygen access between fractions, raising radiosensitivity). Every fractionation decision maps to one of these four.

☐ Memorize the α/β anchor values — they control every BED conversion. Most tumors and acute-responding tissues: α/β ≈ 10 Gy. Late-responding tissues (spinal cord, lung fibrosis, brachial plexus, most normal tissues you care about for late toxicity): α/β ≈ 3 Gy. Prostate cancer: α/β ≈ 1.5–3 Gy (the unusual low α/β that makes hypofractionation attractive). Breast cancer: α/β ≈ 3.5–4 Gy. OER for photons ≈ 2.5–3.0 (hypoxic cells need 2.5–3× the dose of well-oxygenated cells for equivalent kill).

☐ Build a one-line site card for every major treatment site. Typical prescription, fractionation, standard technique, dose-limiting OARs, one site-specific planning wrinkle. Left breast — 40–50 Gy / 15–25 fx, tangent fields or VMAT, left-sided cases use DIBH for cardiac sparing (mean heart dose typically drops 30–50%). NSCLC definitive — 60 Gy / 30 fx with concurrent chemo, IMRT/VMAT with 4DCT and motion management, lung V20 < 30–35%. Prostate EBRT — 78–80 Gy / 39–40 fx standard or 60 Gy / 20 fx moderate hypofractionation, rectal V70 < 25%, bladder V70 < 35%, rectal balloon or spacer common. Definitive cervix — 45–50 Gy EBRT + HDR brachy boost to HR-CTV D90 ≥ 87 Gy EQD2 (GEC-ESTRO).

☐ Palliative regimens are a common CMD scenario. Bone metastases — 8 Gy × 1 (single fraction, simplest, for uncomplicated mets in patients with short life expectancy), 20 Gy / 5 fx, or 30 Gy / 10 fx all acceptable; efficacy is similar. Brain metastases whole-brain — 30 Gy / 10 fx or 20 Gy / 5 fx. Spinal cord compression emergency — 8 Gy × 1 or 20 Gy / 5 fx after neurosurgical evaluation. SBRT to oligometastatic sites uses ablative doses with the same planning rigor as definitive treatment.

☐ Pediatric planning priorities are not adult planning priorities. Growth plate sparing, neurocognitive sparing for CNS treatment, endocrine organ shielding (thyroid, gonads, pituitary), and minimizing the low-dose bath for secondary-malignancy risk all shift the tradeoff calculus. Proton therapy is preferred for pediatric CNS cases specifically because the integral (whole-body) dose is 50–60% lower than IMRT. Anesthesia for daily setup is routine for children under approximately 6 years.

☐ Complete the Practice Questions for Part 7 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Clinical Oncology for Dosimetrists. Main branches: Cancer Biology (cell cycle, radiation-induced cell death) → Four Rs of Radiobiology (Repair, Reassortment, Repopulation, Reoxygenation) → OER & α/β Ratios → BED & EQD2 Math → TNM Staging → Curative vs. Palliative Intent → Site-Specific Planning (Brain/CNS, Head & Neck, Breast, Lung NSCLC/SCLC, GI, Prostate, Gynecologic, Lymphoma, Bone Metastases, Pediatric, Sarcoma) → QUANTEC Constraints → Palliative Regimens (Bone Mets, Brain Mets, Cord Compression).

Comparison Charts:

☐ Chart 1 — Curative Intent vs. Palliative Intent Radiation: Total dose range, typical fractionation, technique complexity, daily image guidance requirement, and OAR management strategy for each.

☐ Chart 2 — The Four Rs of Radiobiology: Mechanism, time course between fractions, effect on tumor vs. normal tissue, and the clinical fractionation principle each one justifies. 

☐ Chart 3 — Left-Sided Breast vs. Right-Sided Breast Treatment: Cardiac dose risk, role of DIBH, prone vs. supine positioning tradeoffs, typical field arrangement, and nodal coverage considerations.

☐ Chart 4 — Pediatric vs. Adult Treatment Planning Priorities: Priority OARs (growth plates, brain, endocrine, developing tissues), typical modality preference, secondary malignancy consideration, anesthesia/immobilization needs, and fractionation adjustments for each population.

Cornell Notes:

☐ Page 1 — Cue questions: What are the Four Rs of radiobiology, and which one is the core justification for conventional fractionation? What α/β ratio applies to a lung tumor vs. the spinal cord vs. prostate cancer, and what is the OER for low-LET photons? Why does accelerated repopulation after week 4 of H&N treatment argue against treatment breaks?

☐ Page 2 — Cue questions: What is the standard definitive prescription and key OAR constraint for breast, NSCLC, prostate EBRT, and cervix EBRT + HDR boost? Why does a left-sided breast patient benefit from DIBH, and what cardiac dose reduction is typical? What are the three standard palliative regimens for bone metastases, and when would you choose single-fraction 8 Gy?

☐ Page 3 — Cue questions: What do T, N, and M represent in TNM staging, and how does stage influence definitive vs. adjuvant vs. palliative intent? What are the pediatric-specific planning priorities that do not dominate adult planning, and why is proton therapy preferred for pediatric CNS disease? What is the partial cord recovery estimate at 6 months for re-irradiation planning?

Week 8 — Part 8: Quality Assurance, Safety & Professional Practice

Difficulty: Moderate–Heavy

What it covers: Part 8 closes the book with the QA, safety, and professional framework that surrounds every plan you build. You will learn daily/monthly/annual machine QA (TG-142), pre-treatment chart rounds and plan review workflows, independent monitor unit verification (TG-114), patient-specific IMRT/VMAT QA (measurement-based vs. calculation-based, gamma analysis), incident learning systems and root cause analysis, radiation protection and ALARA, occupational and public dose limits and pregnant worker protocols, regulatory agencies (NRC, state agencies, Joint Commission), brachytherapy source accountability and medical event reporting, documentation standards, and the key AAPM Task Group reports (TG-43, TG-51, TG-53, TG-101, TG-114, TG-119, TG-142, TG-263).

Print: 1 Mind Map, 3 Comparison Charts, 2 Cornell Notes pages

Study Tasks

☐ Read the Study Guide first — complete the High-Yield Objectives, Key Terms and Definitions, and Concept Overview sections before opening the chapter.

☐ Highlight as you read — follow the Made Easy Highlighting System exactly: Blue: Physics & Calculations Green: Equipment & Delivery Technology Purple: Treatment Planning Yellow: Image Guidance & Motion Management Red: Clinical Oncology & Site-Specific Planning Orange: QA, Safety & Professional Practice

☐ Memorize the dose limits — the CMD tests specific numbers. Occupational TEDE: 5 rem (50 mSv) annual. Lens of the eye: 15 rem (150 mSv) annual. Skin and extremities: 50 rem (500 mSv) annual. Declared pregnant worker embryo/fetus: 0.5 rem (5 mSv) over the entire gestation with a monthly ceiling of approximately 0.05 rem (0.5 mSv). Public annual: 100 mrem (1 mSv). Unrestricted area dose rate: 2 mrem (0.02 mSv) in any single hour. Wipe test limit for sealed source contamination: 185 Bq (0.005 µCi). Every dose-limit question will map to one of these numbers.

☐ Know the medical event reporting triggers cold. Wrong patient, wrong site, wrong treatment site — immediate report. Prescribed total dose differing from the written directive by more than 20%. Any single fraction exceeding the prescribed fraction dose by more than 50%. Lost source, stuck HDR source, or leaking source. Timeline: telephone report to NRC within 24 hours, written report within 15 days. Distractors typically target the percentage thresholds or the reporting timeline — get both exact.

☐ Patient-specific IMRT/VMAT QA has two approaches. Measurement-based PSQA delivers the plan to a physical phantom with a detector array (MapCHECK, ArcCHECK, MatriXX, film, or EPID) and compares measured to TPS-calculated dose — gamma passing rate ≥ 90% at 3%/3 mm (or 3%/2 mm for SBRT). Calculation-based PSQA (increasingly common) uses an independent secondary dose calculation (often Monte Carlo) to verify the primary TPS. Measurement-based is considered the gold standard but time-consuming; calculation-based is faster and catches different failure modes.

☐ TG-114 independent MU verification is required on every plan and must agree with the primary calculation within institutional tolerance — typically ±3–5% for IMRT plans and ±2% (or ±2 MU for low-MU fields) for conventional 3D plans. The independent check is the single most effective safety net for catching upstream planning errors and is a standing CMD exam topic.

☐ Memorize the AAPM Task Group cheat sheet — TG-43: brachytherapy dose calculation formalism (source strength, dose rate constant, geometry function, radial dose function, anisotropy function). TG-51: AAPM protocol for clinical reference dosimetry of photon and electron beams (absorbed dose to water calibration using an ADCL-calibrated ion chamber). TG-53: TPS commissioning tolerances (±2% / ±2 mm). TG-101: SBRT guidelines. TG-114: independent MU verification. TG-119: IMRT commissioning with benchmark plans. TG-142: machine QA tolerances (daily ±3% output, laser ±2 mm). TG-263: standardized nomenclature for targets and OARs. Expect at least one question that asks you to match a task to the correct TG report.

☐ Complete the Practice Questions for Part 8 in your quiz bank. Review every rationale — correct and incorrect.

How to Use Your Templates

☐ Mind Map: Central node = Quality Assurance, Safety & Professional Practice. Main branches: Machine QA (TG-142 daily/monthly/annual) → Pre-Treatment Chart Rounds & Plan Review → Independent MU Verification (TG-114) → Patient-Specific QA (measurement-based, calculation-based, gamma analysis) → Incident Learning & Root Cause Analysis → ALARA & Radiation Protection → Occupational & Public Dose Limits → Pregnant Worker Protocols → Regulatory Agencies (NRC, State, Joint Commission) → Brachytherapy Source Accountability & Medical Event Reporting → Documentation & TG-263 Nomenclature → Key AAPM Task Groups.

Comparison Charts:

☐ Chart 1 — Measurement-Based PSQA vs. Calculation-Based PSQA: Method, detector or calculation type, advantages, limitations, and gamma-analysis passing criteria for each approach.

☐ Chart 2 — Daily vs. Monthly vs. Annual Machine QA (TG-142): Tests performed at each frequency, tolerance values, time commitment, and who typically performs each (therapist, dosimetrist, physicist).

☐ Chart 3 — Occupational Dose Limits vs. Public Dose Limits vs. Declared Pregnant Worker Limits: Annual/gestational limit, who each applies to, monitoring requirement (personal dosimetry vs. area monitoring), and how each is enforced in practice.

Cornell Notes:

☐ Page 1 — Cue questions: What are the annual occupational dose limits for whole body (TEDE), lens of the eye, skin/extremities, and the declared pregnant worker (gestational and monthly)? What is the annual public dose limit and unrestricted area dose rate? What is the brachytherapy wipe test contamination limit?

☐ Page 2 — Cue questions: What are the five medical-event reporting triggers, and what is the NRC timeline for telephone vs. written reporting? What is the gamma passing rate threshold for measurement-based IMRT PSQA, and what is the TG-114 tolerance for an independent MU check? Match each scenario to its task group: brachytherapy dose calc, linac calibration, TPS commissioning, SBRT guidelines, machine QA, standardized nomenclature.

Week 9 — Full Review & Exam Simulation

Your final week is not about learning new material — it is about consolidating everything you have built and proving it under exam conditions.

Review Tasks

☐ Re-draw one Mind Map from memory for each Part you feel least confident about. Check it against your original.

☐ Work through your Cornell Notes cue columns for every Part — cover the right-hand notes and answer from memory.

☐ Re-do any quiz bank questions you got wrong across all Parts. Focus on the rationales.

☐ Review the Common Mistakes, Rapid Review, and Self-Assessment Checklist sections for your two or three weakest Parts.

Exam Simulation

☐ Take the full-length CMD practice exam using the QR code in the back matter of this book. Complete it in one sitting, timed, as close to real exam conditions as possible.

☐ Review your emailed score report. Identify which Parts you missed most and spend your remaining time on those Parts' Rapid Review and clinical vignettes only.