Radiologic Physics, Equipment, Biology, Protection
20%of exam
Image Production and Evaluation
20%of exam
Radiographic Positioning and Radiologic Procedures
20%of exam
Patient Care and Management
20%of exam
Radiological Sciences
20%of exam
CT & MRI PhysicsUltrasound, Nuclear Med & TherapyContrast, Renal Labs & ExtravasationPharmacology & Venipuncture
Quick Facts
- Official Exam Items
- 500 across five 100-item subjects
- Subject Weight
- 20% each
- 2026 Exam Dates
- December 10–11
- Session Time
- 150 minutes per subject
- Total Session Time
- 12.5 hours; breaks excluded
- Passing Ratings
- Average ≥75%; each subject ≥60%
- Complete Exam Fee
- P900
- Removal Exam Fee
- P450
- Educational Route
- Recognized BSRT degree
Photoelectric and Compton Interactions
Photoelectric
- Incident photon absorbed
- Bound electron ejected
- Strong atomic-number dependence
Compton
- Photon retains part of energy
- Photon changes direction
- Scatter can reduce image contrast
Absorption differs from partial-energy scattering
X-Ray Physics & Generators
- Tungsten Target
- Atomic number 74; K-binding ≈69.5 keV
- Bremsstrahlung
- Electron braking; continuous photon spectrum
- Characteristic Emission
- Shell vacancy filled; discrete photon energy
- Photoelectric Effect
- Photon absorbed; bound electron ejected
- Compton Scatter
- Photon redirected; some energy transferred
- Anode Heel Effect
- Cathode-side intensity generally greater
- HVL
- Specified absorber halves narrow-beam air kerma
- Added Filtration
- Harder beam; lower output
- Generator Ripple
- Lower ripple generally increases output
Tissue Reactions and Stochastic Effects
Tissue Reactions
- Endpoint-dependent threshold
- Severity generally rises with dose
- Example: sufficiently severe skin injury
Stochastic Effects
- Probability is the protection concern
- Severity not predicted by dose
- Low-dose risk uses protective models
Threshold injury differs from probabilistic risk
Radiobiology & Dose Limits
- Radiosensitivity
- Cell type, endpoint and dose matter
- Lymphocytes
- Apoptosis challenges simple division-rate rule
- Tissue Reactions
- Threshold depends on endpoint and conditions
- Stochastic Effects
- Probability modeled; severity not dose-scaled
- Fetal Exposure
- Assess dose and developmental stage
- PNRI Adult Effective Dose
- 20mSv/year averaged over five years
- PNRI Adult Lens Dose
- 20mSv/year averaged over five years
- PNRI Single-Year Maximum
- 50 mSv effective and lens doses
- PNRI Skin and Extremities
- 500 mSv/year adult occupational limit
- PNRI Scope
- Radioactive-material practices; excludes DOH-FDA X-rays
Quality Assurance & Informatics
- QA
- Organized process for reliable imaging
- QC
- Measurements checking equipment and process performance
- DICOM
- Image information and communication standard
- PACS
- Image storage, retrieval and distribution system
- Image Privacy
- Check pixels and identifying metadata
- Repeat Analysis
- Identify causes; improve acquisition process
- Dose Indicators
- Interpret with image quality and context
Exposure Calculation Checks
Units → Assumptions → Formula → Result
Use consistent distance unitsGrid factor must be supplied15% rule is approximateDI describes index versus target
CR and Direct DR Signal Conversion
CR
- Storage phosphor latent signal
- Laser readout releases light
- Plate requires appropriate erasure
Direct DR
- Photoconductor creates charge
- Electronic detector readout
- No scintillator light-conversion stage
Conversion pathway cannot guarantee image superiority
Technique & Grid Picker
- Higher kVp proposed→Apply validated technique; assess contrast(15% rule is approximate)
- Grid factor explicitly supplied→Multiply original mAs by factor(Ratio alone does not specify factor)
- Focused-grid peripheral cutoff→Check orientation, centering, level and SID(Do not merely raise exposure)
- Exposure index differs from target→Assess segmentation, technique and image quality(Not automatic repeat)
- Film control strip has shifted→Investigate processing against QC baseline(Do not compensate through patient exposure)
Exposure Math & Grids
- Inverse Square
- I₂ = I₁ × (d₁/d₂)²
- Point-Source Example
- 160µGy at 1m → 40µGy/2m
- Approximate 15% Rule
- 80kVp/20mAs → 92kVp/10mAs
- Distance Compensation
- mAs₂ = mAs₁ × (SID₂/SID₁)²
- SID Example
- 10mAs/100cm → 32.4mAs/180cm
- Specified Bucky Factor 5
- 5mAs without grid → 25mAs
- Magnification
- SID ÷ SOD
- Geometric Unsharpness
- Focal-spot size × OID/SOD
- Focused Grid Cutoff
- Check orientation, alignment and focal range
Film, CR, DR & Displays
- Film Development
- Exposed crystals become metallic silver
- Film Fixation
- Removes remaining unexposed silver halide
- Film QC
- Compare sensitometry with established baseline
- CR
- Laser stimulates stored phosphor signal
- Indirect DR
- Scintillator light → electrical charge
- Direct DR
- Photoconductor converts X-rays to charge
- Nyquist Frequency
- 1 ÷ (2 × sampling pitch)
- 100µm Pitch
- Nyquist 5lp/mm; not measured resolution
- IEC Deviation Index
- 10 log₁₀(EI/EIₜ)
- DI +3
- Exposure index approximately twice target
- Window Width
- Adjusts displayed intensity range
- Window Level
- Adjusts displayed range centre
Towne Baseline Relationship
OML thirty; IOML thirty-seven
Angles relative to named baselineAbout seven degrees differenceDo not force injured neck
Cervical and Lumbar Oblique Targets
Cervical
- Intervertebral foramina emphasized
- Rotation changes demonstrated side
- Avoid routine rotation in uncleared trauma
Lumbar
- Zygapophyseal joints emphasized
- Obliquity changes joint demonstration
- Use only when clinically indicated
Different targets require different positioning logic
Positioning & Trauma Picker
- Decubitus fluid demonstration indicated→Place fluid side dependent if safe(Horizontal beam)
- Decubitus pneumothorax demonstration indicated→Place affected side elevated if safe(Horizontal beam)
- Free-air study; cannot safely stand→Use prescribed safe decubitus adaptation(No forced waiting in instability)
- Suspected neck or hip fracture→Preserve precautions; adapt or escalate imaging(No forced rotation)
- Suspected GI perforation→Radiologist selects appropriate initial water-soluble agent(Consider aspiration risk)
Skull, Sinus & Spine Views
- Towne with OML
- 30° caudal to OML
- Towne with IOML
- 37° caudal to IOML
- Caldwell Routine Geometry
- 15° caudal PA axial projection
- Waters Routine Geometry
- OML about 37° to detector
- Sinus Fluid Levels
- Use appropriate horizontal-beam geometry
- Suspected Cervical Injury
- Preserve precautions; avoid forced movement
- Cervical Obliques
- Foramina; unsafe routine rotation in trauma
- Lumbar Obliques
- Zygapophyseal joints; assess clinical indication
Chest, Abdomen & Extremities
- PA Chest
- Less heart magnification than comparable AP
- Decubitus Pleural Fluid
- Dependent side demonstrates layering fluid
- Decubitus Pneumothorax
- Elevated affected side demonstrates free gas
- Left Decubitus Abdomen
- Free gas adjacent to liver
- Grashey
- Open glenohumeral joint space
- Scapular Y
- Profile scapula; assess humeral-head relationship
- Gaynor-Hart
- Tangential carpal canal; avoid forced extension
- Judet Iliac Oblique
- Posterior column and anterior wall
- Judet Obturator Oblique
- Anterior column and posterior wall
- Ankle Mortise
- Approximate 15–20° internal limb rotation
Mammography & Contrast Procedures
- CC and MLO
- Complementary breast tissue demonstration
- Compression
- Reduce thickness and motion; individualized technique
- US MQSA Phantom Dose
- ≤3mGy per standard-phantom CC exposure
- Phantom Dose Benchmark
- Not universal patient-dose ceiling
- Suspected GI Leak
- Usually begin appropriate water-soluble study
- Aspiration Risk
- Avoid unsuitable hyperosmolar enteric agents
- Negative Initial Leak Study
- Radiologist selects further imaging if needed
- Dental Paralleling Principle
- Receptor parallel to tooth; beam perpendicular
RA 7431 Board Composition
Three technologists; one radiologist; one physicist
Five members totalChair among three technologistsProfessional qualifications also required
Radiologic and X-Ray Technology Routes
Radiologic Technologist
- Recognized BSRT educational route
- Separate professional registration
- Five-subject enhanced RTLE blueprint
X-Ray Technologist
- Recognized associate-diploma educational route
- Separate professional registration
- Different examination and result cohort
Keep qualifications and pass rates separate
R.A. 7431 Law & Jurisprudence
- RTLE Degree
- Recognized Bachelor of Radiologic Technology
- Professional Practice
- Degree alone does not confer registration
- Board Composition
- Three technologists; radiologist; medical physicist
- Board Minimum Age
- 30 years at appointment
- Passing Average
- At least 75% weighted average
- Subject Minimum
- No subject below 60%
- Conditioned Reexamination
- Qualifying candidates repeat deficient subjects
- Removal Rating
- At least 75% each repeated subject
- Privacy
- Lawful purpose; proportionate information sharing
Vasovagal and Allergic-Like Clues
Vasovagal Pattern
- Hypotension with bradycardia may occur
- Pallor and sweating may occur
- Assess overall presentation and evolution
Allergic-Like Pattern
- Airway or skin signs may occur
- Hypotension can be severe
- Heart rate alone cannot exclude
Emergency assessment overrides a pulse mnemonic
Patient Care & Emergencies
- Patient Identity
- Reconcile identifiers, order, anatomy and side
- Unclear Examination Request
- Clarify before exposure
- Transfer Safety
- Assess mobility, precautions, lines and assistance
- Standard Precautions
- Apply to all patients
- Airborne Precautions
- Additional controls for pulmonary tuberculosis
- Reaction Assessment
- Airway, breathing and circulation; summon help
- Adult CPR Rate
- 100–120 compressions per minute
- Adult CPR Depth
- At least 5cm; avoid >6cm
- Conventional Adult CPR
- 30 compressions : 2 breaths
Four Radiotherapy Rs
Repair; Redistribution; Reoxygenation; Repopulation
Repair of sublethal damageRedistribution through cell cycleReoxygenation of hypoxic tumor cellsTumor repopulation can oppose control
Conventional Spin-Echo T1 and T2
T1 Weighting
- Relatively short TR and TE
- Longitudinal relaxation contrast
- Simple fluid usually relatively dark
T2 Weighting
- Relatively long TR and TE
- Transverse relaxation contrast
- Simple fluid usually relatively bright
Sequence modifications can change signal appearance
Contrast & Emergency Picker
- Severe symptoms during contrast injection→Stop; summon response; assess ABC(Follow trained emergency protocol)
- Extravasation suspected→Stop injection; obtain clinical examination(Assess perfusion, sensation and movement)
- Severe/progressive extravasation symptoms→Obtain urgent surgical assessment(Do not use volume alone)
- IV contrast; no AKI; eGFR≥30→ACR: metformin need not stop(Local policy/label may differ)
- AKI/eGFR<30 or renal-embolic arterial study→Hold metformin; reassess after 48h(Authorized restart decision)
- Potential penetrating orbital ferromagnetic injury→Radiograph or review suitable prior CT(Metalworking alone is not indication)
CT & MRI Physics
- Helical Pitch
- Travel/rotation ÷ nominal beam width
- Pitch-Dose Relationship
- Inverse only with other settings fixed
- Water CT Number
- Approximately 0 HU
- Air CT Number
- Approximately −1000 HU
- CTDIvol
- Standardized phantom-based scanner-output index
- DLP Example
- 10mGy × 30cm = 300mGy·cm
- Proton Frequency
- 42.58 MHz/T × field strength
- 1.5T / 3T Protons
- Approximately 63.87 / 127.74 MHz
- MR Zone III
- Controlled access under Level-2 MR supervision
- ACR 2026 B₀ Hazard Area
- Within 9-gauss line; mapped spatially
- Orbital Trauma Concern
- Evaluate suspected penetrating ferromagnetic foreign body
Modality Physics Picker
- GBCA needed; CKD4/5→Use group II; avoid group I(Supervising clinician assesses benefit and risk)
- Bolus specified in therapy plan→Verify material, position and planned use(No independent treatment alteration)
- C-arm geometry can be optimized→Under-table tube; close receptor where feasible(Use shielding and appropriate exposure settings)
- 5Gy reference air kerma reached→Activate local follow-up process(Not measured peak skin dose)
- Tc-99m generator eluate prepared→Check radionuclidic and chemical purity(Use product limits and administration time)
Ultrasound, Nuclear Med & Therapy
- Ultrasound Assumed Speed
- 1540 m/s in soft tissue
- Ultrasound Output
- ALARA; indication-specific mode and duration
- Tc-99m Photon
- Approximately 140 keV
- Tc-99m Half-Life
- Approximately six hours
- TECHNELITE Mo-99 Limit
- ≤0.15 µCi/mCi Tc-99m at administration
- TECHNELITE Aluminum Limit
- ≤10 µg/mL before administration
- PET Annihilation
- Approximately 511keV paired photons
- 20% Window at 140keV
- 126–154keV: ±10% about centre
- Therapy Fractionation
- Repair, redistribution, reoxygenation, repopulation
- Tumor Repopulation
- Can oppose treatment control
- Bolus
- Use only as specified in plan
- Fluoroscopy Follow-Up Triggers
- 3Gy skin; 5Gy reference air kerma
Contrast, Renal Labs & Extravasation
- Metformin: IV, No AKI, eGFR≥30
- ACR: no routine interruption
- Metformin: AKI or eGFR<30
- Withhold; 48h; reassess before restarting
- Arterial Renal Embolic Risk
- ACR metformin withholding also applies
- Gadolinium: CKD4/5
- Avoid group I; use group II
- Known or Suspected AKI
- Group II preferred when GBCA needed
- Extravasation
- Stop injection; obtain clinical assessment
- Initial Limb Care
- Elevate; initially apply cold compresses
- Surgical Referral
- Severe/progressive symptoms; not volume alone
- Routine Extravasation Aspiration
- Not recommended by ACR
- Contrast Warming
- Not routinely supported for lower-viscosity agents
Common Traps
Dose Metric
Reference air kerma ≠ Peak skin absorbed dose
Rating Versus Raw Count
Official weighted rating ≠ Unvalidated number-correct conversion
Grid Specification
Grid geometric ratio ≠ Exposure multiplication factor
Detector Versus Patient
Detector exposure index ≠ Patient organ absorbed dose
Renal Contrast Groups
Group I gadolinium agents ≠ Group II gadolinium agents
MR Safety Geometry
Mapped magnetic-field contour ≠ Scanner-room physical wall
Warming Evidence
Lower-viscosity contrast agents ≠ Higher-viscosity contrast agents
Film and Digital Appearance
Film optical density ≠ Processed digital display brightness
Last Minute
- 1.500 items; five equally weighted subjects
- 2.Five sessions ×150min =750min
- 3.Pass average ≥75%; subjects ≥60%
- 4.Board has five specified professionals
- 5.Current PNRI lens: 20mSv five-year average
- 6.PNRI excludes DOH-FDA X-ray sources
- 7.Formula assumptions precede numerical substitution
- 8.Focused grids require correct geometry
- 9.Do not force injured joint movement
- 10.Metformin decision includes AKI and route
- 11.Gadolinium decision includes agent group
- 12.Extravasation referral follows clinical severity
- 13.MR safety includes implants and fields
- 14.Mammography phantom limit is not patient-limit
- 15.Follow-up trigger is not confirmed injury
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