Professional, Communicator, Collaborator
5-10%of exam
Care Provider
10-20%of exam
RTR.1 Safe Work Principles
9-14%of exam
RTR.2 Imaging Systems
5-10%of exam
RTR.3-5 Procedures + Substances
27-32%of exam
RTR.6 Image + Data Quality
27-32%of exam
Quick Facts
- Exam
- CAMRT RTR certification
- Body
- CAMRT, delivered by Yardstick
- Questions
- 185 single-best-answer MCQ
- Time
- 4 hours
- Taxonomy
- Min 80% application
- Pass
- Modified Angoff, Pass/Fail
- Sittings
- 3 per year
- Attempts
- 4 within 5 years
- Fee
- $980 CAD + seat fee
- Results
- 20 business days
- Languages
- English and French
- Blueprint
- May 2024 (2020 profile)
Observe vs Diagnose
MRT may
- Note urgent findings
- Alert the radiologist
- Repeat for image quality
MRT may not
- Give a diagnosis
- Interpret for the patient
- Change the order alone
Escalate, never interpret
Blueprint Question Counts
- Professional, Communicator, Collaborator
- 5-10%, 9-19 questions
- Care Provider
- 10-20%, 19-37 questions
- RTR.1 Safe work
- 9-14%, 17-26 questions
- RTR.2 Imaging systems
- 5-10%, 9-19 questions
- RTR.3-5 Procedures
- 27-32%, 50-59 questions
- RTR.6 Image quality
- 27-32%, 50-59 questions
- Clinical Expert total
- 70-85%, 129-157 questionsBiggest
- Leader, Scholarly Practitioner
- 0%, not examined
- Taxonomy split
- Min 80% application items
- High secondary weight
- Respiratory and skeletal
- Low secondary weight
- Mammography, BMD, interventional
Scope, Consent, Privacy
- MRT scope
- No image interpretation
- Urgent finding
- Alert radiologist immediately
- Informed consent
- Ongoing, withdrawable anytime
- Consent withdrawn
- Stop, make safe, notify
- PACS lookup
- Only patients you serve
- Registration body
- Provincial college, not CAMRT
- Quebec candidates
- OTIMROEPMQ exam instead
- Transfer of care
- Identity, contrast, lines, limits
- Documentation
- Accurate, timely, complete
Exam Day Logistics
- Delivery
- Yardstick centre or remote
- ID required
- Name, DOB, photo, signature
- Results
- Within 20 business days
- Score released
- Pass/Fail only
- Failed attempt
- Performance profile, 5 days
- Cut score setters
- 8-10 member committee
- Accommodations
- Before registration deadline
- Official practice exam
- $75, about 100 questions
- Certificate mailing
- Within 6 weeks
Fire Response
RACE the fire, then PASS the extinguisher
Rescue, Alarm, Confine, ExtinguishPull, Aim, Squeeze, SweepCode Red means fire
Routine vs Additional Precautions
Routine practices
- Every patient
- Risk assessment first
- Hand hygiene and PPE
Additional precautions
- Specific suspected organism
- Contact, droplet, airborne
- Layered on top
Baseline vs layered
Precaution Picker
- Any patient, any exam→Routine practices
- Before every interaction→Point-of-care risk assessment
- Draining wound, resistant organism→Contact precautions
- Influenza or pertussis→Droplet precautions
- Tuberculosis or measles→Airborne, fit-tested N95
- Clostridioides difficile→Soap and water(Not alcohol rub)
- Used needle in hand→Sharps container, no recap
- Severely immunocompromised patient→Protective measures, clean equipment
Patient Identity + Transfer
- Identifiers
- Two person-specific, patient-stated
- Not identifiers
- Room, bed, chart label
- Pregnancy screen
- Ask, document, then justify
- Requisition conflict
- Resolve before any exposure
- Transfer prep
- Lock wheels, lower rails
- Transfer aid
- Slider board, enough staff
- Restless patient
- Immobilization devices first
- Holder rules
- Apron, gloves, out of beam
- Never routine
- Same person holding repeatedly
Infection Prevention (Canada)
- Routine practices
- Every patient, every time
- PCRA
- Point-of-care risk assessment
- Additional precautions
- Contact, droplet, airborne
- Hand hygiene
- Four Moments framework
- Alcohol rub
- 60-90% alcohol content
- C. difficile
- Soap and water only
- Airborne
- Fit-tested N95 respirator
- Sharps
- Never recap, dispose immediately
- Cleaning order
- Clean before disinfecting
Emergency Code Colours
- Code Red
- FireOHA set
- Code Blue
- Adult cardiac arrest
- Code Pink
- Infant or child arrest
- Code White
- Violent behaviour
- Code Yellow
- Missing person
- Code Amber
- Abducted child
- Code Orange
- External disaster
- Code Brown
- In-facility hazardous spill
- Code Grey
- Infrastructure loss
- Code Black
- Bomb threat
- Code Green
- Evacuation
- Code Silver
- Person with a weapon
Adult Vital Sign Ranges
- Heart rate
- 60-100 beats per minute
- Respiratory rate
- 12-20 per minute
- Oxygen saturation
- 95-100% on air
- Blood pressure
- About 120/80 mmHg
- Temperature
- 36.5-37.5 degrees Celsius
- Glasgow Coma Scale
- 3 lowest, 15 normal
- Hypoglycemia
- Below 4.0 mmol/L
- Stroke screen
- Face, arms, speech, time
Cardinal Rules
Time down, distance up, shielding on
Time: shortest exposureDistance: inverse squareShielding: apron, thyroidDistance wins in fluoroscopy
Deterministic vs Stochastic
Deterministic
- Has a threshold
- Severity rises with dose
- Erythema, epilation, cataract
- Long fluoroscopy risk
Stochastic
- No threshold assumed
- Probability rises with dose
- Cancer, heritable effects
- Reason for ALARA
Severity vs probability
Radiation Safety Picker
- Cut your fluoroscopy dose→Step back from the patient(Inverse square)
- Must stay beside table→Apron and thyroid shield
- Patient cannot hold still→Immobilization devices first
- Someone must hold→Aproned escort, never staff
- Wearing a single dosimeter→Trunk, under the apron
- Adding a second badge→Collar, outside thyroid shield
- Patient declares pregnancy→Justify, optimize, inform
- Staff declares pregnancy→Notify employer, review duties
- Apron may be damaged→Radiographic integrity check
- Repeats keep rising→Reject analysis review
Safety Code 35 Dose Limits
- Worker whole body
- 20 mSv/yr, 5-year averageSC35 2024
- Five-year total
- 100 mSv maximum
- Single-year cap
- 50 mSv
- Worker lens
- 20 mSv averaged, 50 cap
- Worker skin
- 500 mSv equivalent dose
- Worker hands, feet
- 500 mSv equivalent dose
- Public whole body
- 1 mSv effective dose
- Public lens
- 15 mSv
- Public skin
- 50 mSv
- Monitoring trigger
- 1/20th of worker limit
- Pregnant worker
- Employer adjusts assigned duties
Dose Limit Numbers
20 average, 50 cap, 1 public
20 mSv/yr, 5-year average100 mSv over 5 years50 mSv single-year capPublic: 1 mSv yearly
Absorbed vs Effective Dose
Absorbed dose
- Gray
- Energy per mass
- No weighting applied
Effective dose
- Sievert
- Tissue weighted
- Compares exam risk
Physics vs risk
Dose Quantities + Units
- Absorbed dose
- Gray, energy per mass
- Equivalent dose
- Sievert, radiation weighted
- Effective dose
- Sievert, tissue weighted
- Weighting factor, x-rays
- Equals one
- Air kerma
- Gray, beam output
- KAP or DAP
- Gy-cm2, total beam energy
- Peak skin dose
- Deterministic injury marker
- ICRP principles
- Justify, optimize, limit
Occupational Protection
- Cardinal rules
- Time, distance, shielding
- Best fluoroscopy control
- Distance, by inverse square
- Dosimeter placement
- Trunk, under the apron
- Optional second badge
- Collar, outside thyroid shield
- Apron storage
- Hang it, never fold
- Apron testing
- Visual plus radiographic check
- Scatter at one metre
- About 0.1% of primary
- Lead curtains
- Not an apron substitute
- Receptor holding
- Never hand-held during exposure
- Energized tube
- Never left unattended
- Deliberate training exposure
- Never permitted
Grid vs No Grid
Grid
- Absorbs scatter
- Higher contrast
- More mAs needed
- Cutoff risk
No grid
- Parts under 10 cm
- Lower patient dose
- More scatter fog
- Air gap alternative
Contrast costs dose
X-ray Production + Interactions
- Bremsstrahlung
- Braking, most of beam
- Characteristic
- K-shell, needs 69.5 kVp
- Photoelectric
- Absorbed, creates subject contrast
- Compton
- Scatter, fogs the image
- Raising kVp
- More penetration, less dose
- Cost of kVp
- Lower contrast, more scatter
- Anode heel effect
- Cathode side more intense
- Heel effect use
- Thick end under cathode
- Line focus principle
- Steeper angle, smaller focus
- Filtration
- Removes low-energy photons
Beam Quality + QC
- HVL at 60 kV
- 1.9 mm aluminum minimumSC35 2024
- HVL at 80 kV
- 2.4 mm aluminum minimum
- HVL at 100 kV
- 3.0 mm aluminum minimum
- HVL at 120 kV
- 3.8 mm aluminum minimum
- Reject analysis
- Service quality, not discipline
- Top reject cause
- Positioning errors
- Automatic intensity control
- Double phantom, double output
- PACS duty
- Verify data complete, accurate
Grids, Collimation, AEC
- Grid ratio
- Strip height over spacing
- Grid needed
- Part over 10 cm
- Grid also above
- About 70 kVp
- 5:1 grid factor
- About 2x the mAs
- 8:1 grid factor
- About 4x the mAs
- 12:1 grid factor
- About 5x the mAs
- Grid cutoff causes
- Off-level, off-centre, off-focus
- Inverted focused grid
- Dense edges, clear centre
- Air gap technique
- 10-15 cm OID alternative
- Collimation
- Less scatter, less dose
- AEC controls
- Exposure time only
- AEC cannot fix
- Poor centring over chambers
- Backup timer
- Caps a runaway exposure
Decubitus Side Rule
Fluid falls down, free air rises up
Effusion: affected side downPneumothorax: affected side upFree air: left lateral decubitusHorizontal beam always
PA vs AP Chest
PA erect
- Heart near receptor
- 180 cm SID
- True heart size
- Scapulae off lungs
AP supine
- Heart magnified
- Shorter SID
- Mediastinum widened
- Air-fluid levels lost
Erect PA preferred
Projection Picker
- Suspected small pneumothorax→Erect PA, add expiration
- Suspected small effusion→Decubitus, affected side down
- Suspected free abdominal air→Erect chest or left decubitus
- Suspected hip fracture→AP as-lies, cross-table lateral(No rotation)
- Snuffbox tenderness→PA with ulnar deviation(Scaphoid)
- Cervical spine trauma→Cross-table lateral first(Show C7-T1)
- Shoulders hide C7-T1→Swimmer's lateral
- Glenohumeral joint space→Grashey AP oblique(35-45 degrees)
- Intercondylar fossa→Camp Coventry or Holmblad
- Suspected spondylolysis→45-degree lumbar oblique(Scottie dog)
- Radial head, limited flexion→Coyle axiolateral method
Chest + Thorax Routine
- Chest SID
- 180 cm (72 inches)
- PA erect
- Heart nearest the receptor
- Lateral side
- Left against the receptor
- Breathing
- Second full inspiration
- Adequate inspiration
- 10 posterior ribs visible
- Rotation check
- SC joints equidistant
- Arm position
- Shoulders rolled forward, down
- Effusion decubitus
- Affected side down
- Pneumothorax decubitus
- Affected side up
- Free abdominal air
- Erect chest, five minutes
Chest Image Check
Ten ribs, no rotation, scapulae clear
10 posterior ribs visibleSC joints equidistant180 cm SIDSecond full inspiration
Barium vs Water-Soluble
Barium sulfate
- Best mucosal coating
- Routine GI studies
- Never if perforated
- Chemical peritonitis risk
Water-soluble
- Suspected leak or surgery
- Absorbed if it escapes
- Poorer coating
- Non-ionic if aspiration
Perforation means iodinated
Contrast Reaction Response
- Warmth, flush, metallic taste→Reassure and continue(Physiologic)
- A few scattered hives→Observe, notify radiologist(Mild)
- Diffuse hives, mild wheeze→Stop, oxygen, call help(Moderate)
- Stridor or facial swelling→Epinephrine per protocol(Airway)
- Hypotension with tachycardia→Legs up, IV fluids(Anaphylactoid)
- Hypotension with bradycardia→Fluids, consider atropine(Vasovagal)
- Swelling at injection site→Stop, elevate, cold compress
- Suspected bowel perforation→Water-soluble, never barium
- eGFR 30 or under→Hold metformin, consult radiologist
Upper Extremity Keys
- Scaphoid
- PA with ulnar deviation
- Stecher method
- CR 20 degrees proximal
- Carpal tunnel
- Gaynor-Hart tangential projection
- True lateral elbow
- Epicondyles superimposed, three arcs
- Medial (internal) oblique
- Coronoid process free
- Lateral (external) oblique
- Radial head, capitulum free
- Coyle radial head
- Elbow 90, CR 45 shoulder
- Grashey method
- 35-45 degrees, glenoid open
- AC joints
- Bilateral erect, weighted comparison
- Rheumatoid survey
- Norgaard ball-catcher projection
Scottie Dog Parts
Eye pedicle, nose transverse, neck pars
Ear: superior articular processFront leg: inferior articularCollar on neck: spondylolysis45-degree lumbar oblique
Lower Limb + Pelvis
- Ankle mortise
- Rotate leg 15-20 degrees
- AP foot
- CR 10 degrees toward heel
- Calcaneus axial
- CR 40 degrees cephalad
- AP pelvis
- Feet rotated 15-20 internally
- Why rotate feet
- Overcome femoral neck anteversion
- Suspected hip fracture
- No rotation, cross-table lateral
- Danelius-Miller
- Axiolateral hip, horizontal beam
- Intercondylar fossa
- Camp Coventry or Holmblad
- Settegast patella
- Avoid until fracture excluded
- Acetabulum
- Judet obliques, 45 degrees
Spine + Skull Angles
- C-spine trauma first
- Cross-table lateral, unmoved patient
- Lateral must show
- C7 and C7-T1 junction
- Shoulders obscure junction
- Add swimmer's lateral
- C1 and C2
- AP open-mouth projection
- Cervical obliques
- 45 degrees, intervertebral foramina
- Posterior cervical oblique
- Foramina farthest, CR cephalad
- Lumbar obliques
- 45 degrees, Scottie dog
- Scottie dog neck
- Pars interarticularis
- Towne (AP axial)
- 30 degrees caudad to OML
- Caldwell
- 15 degrees caudad to OML
- Waters
- OML 37 degrees to receptor
Contrast Media Selection
- Barium sulfate
- Best coating, routine GI
- Suspected perforation
- Water-soluble iodinated only
- Aspiration risk
- Non-ionic low-osmolar agent
- Ionic high-osmolar
- More reactions, older agent
- Non-ionic low-osmolar
- Lower osmolality, safer
- Negative contrast
- Air or carbon dioxide
- Gadolinium
- MRI only, not radiography
- Double contrast
- Barium plus gas, mucosa
- Preparing agents
- Verify name, strength, expiry
Venipuncture + Reactions
- Avoid that arm
- Fistula, mastectomy, cast, infection
- Needle entry
- Bevel up, shallow angle
- Tourniquet
- Release before withdrawing needle
- Physiologic effects
- Warmth, flush, metallic taste
- Mild reaction
- Limited hives, mild nausea
- Anaphylactoid signs
- Stridor, wheeze, facial swelling
- First action
- Stop injection, keep access
- Adult epinephrine
- 0.3-0.5 mg IM, 1:1000
- Vasovagal clue
- Hypotension with bradycardia
- Extravasation
- Stop, elevate, cold compress
Contrast + Kidney Rules
- Screening
- Questionnaire, never delay emergenciesCAR
- Prophylaxis threshold
- eGFR under 30
- Metformin, eGFR over 30
- Do not stop it
- Metformin, eGFR 30 or under
- Hold at injection time
- Metformin restart
- After 48 hours, stable
- Stability threshold
- Under 25% creatinine rise
- ACE inhibitors, diuretics
- Do not routinely stop
- Post-contrast creatinine
- Not routinely required
Deviation Index Scale
-3 half, 0 target, +3 double
DI 0: on targetDI +1: 26% overDI -1: 20% underOne unit: one mAs step
kVp vs mAs
kVp
- Beam quality
- Penetration
- Subject contrast
- 15% rule
mAs
- Beam quantity
- Receptor exposure
- Noise control
- Direct proportion
Quality vs quantity
Exposure Correction Picker
- DI strongly positive→Reduce mAs(Dose creep)
- DI strongly negative→Increase mAs(Mottle risk)
- Grainy, noisy image→Increase mAs(Quantum mottle)
- Thick part under-penetrated→Raise kVp 15%(Halve mAs)
- Low contrast, heavy fog→Collimate, add grid(Scatter)
- Motion blur present→Higher mA, shorter time(Same mAs)
- SID increased→Raise mAs by distance squared
- Pleural effusion, ascites→Increase technique(Additive)
- Emphysema, osteoporosis→Decrease technique(Destructive)
- Anatomy collimated off→Repeat the image(Not recoverable)
Exposure Factor Relationships
- mAs controls
- Receptor exposure, directly proportional
- kVp controls
- Penetration and subject contrast
- 15% rule
- +15% kVp, halve mAs
- Reciprocity
- mA times time equals mAs
- Inverse square law
- Intensity falls with distance squared
- Double the distance
- Quarter the intensity
- Direct square law
- mAs scales with distance squared
- Standard SID
- Chest 180 cm, table 100
- Motion control
- High mA, shortest time
- Additive pathology
- Increase technique
- Destructive pathology
- Decrease technique
Image Critique Order
Anatomy, alignment, exposure, markers, artifacts
Anatomy: all includedAlignment: rotation, tiltExposure: check the DIMarkers: in beamArtifacts: removable
DI High vs DI Low
DI positive
- Overexposed
- Dose creep
- Still looks fine
- Lower the mAs
DI negative
- Underexposed
- Quantum mottle
- Grainy image
- Raise the mAs
Dose creep vs mottle
Exposure Index + DI
- EI
- Detector exposure indicatorIEC 62494
- Target EI
- Exam-specific reference value
- DI formula
- 10 log10 (EI/target EI)
- DI zero
- Exposure on target
- DI +1
- About 26% overexposed
- DI -1
- About 20% underexposed
- DI +3
- About double the target
- DI -3
- About half the target
- One DI unit
- About one mAs step
- Action limits
- Site-derived, per AAPM TG-232
- Dose creep
- Drifting positive DI values
Resolution + Distortion
- Small focal spot
- Narrower penumbra, sharper edges
- Reduce OID
- Less magnification and blur
- Magnification factor
- SID divided by SOD
- Detector element size
- Limits DR spatial resolution
- Elongation
- Tube or receptor angled
- Foreshortening
- Part angled to receptor
- Shape distortion
- Alignment problem
- Size distortion
- OID problem
- Commonest unsharpness
- Patient motion
Artifacts + Image Critique
- Quantum mottle
- Too few photons, low mAs
- Moire artifact
- Grid lines alias with scan
- Grid cutoff look
- Edge or overall density loss
- Dead pixels
- Fixed detector defects
- Ghosting or lag
- Previous image retained
- Lead marker
- In beam at exposure
- Annotation later
- Last resort, error prone
- Post-processing limit
- Cannot restore lost data
- Repeat criterion
- Cannot answer clinical question
- Not a repeat
- Slight rotation, still diagnostic
High-Weight Pathology Signs
- Pneumothorax, erect
- Fine apical pleural line
- Pneumothorax, supine
- Deep sulcus sign
- Pleural effusion
- Blunted costophrenic angle
- Free intraperitoneal air
- Crescent under the hemidiaphragm
- Pneumonia
- Consolidation, air bronchograms
- Emphysema
- Hyperlucent, flattened diaphragms
- Acute fracture line
- Sharp, lucent, no cortex
- Accessory ossicle
- Smooth, corticated, often bilateral
- Scaphoid fracture risk
- Avascular necrosis, non-union
- Spondylolysis
- Collar across Scottie neck
Common Traps
Pass mark vs percentage
Modified Angoff sets it ≠ No fixed 70% pass
Results vs feedback
Pass or Fail only ≠ Profile only after failing
Dosimeter placement
Worn under the apron ≠ Not on top of it
Declared pregnancy limit
No separate fetal limit published ≠ Duties matched to Appendix I
Patient shielding updated
Gonadal weighting factor reduced ≠ Collimation is the control
Bright image vs correct dose
Digital rescales brightness ≠ Only DI reveals overexposure
Noise fix vs penetration fix
mAs fixes quantum mottle ≠ kVp cannot add signal
Metformin rule changed
No routine 48-hour hold ≠ Hold only eGFR 30 or under
Barium vs iodinated
Perforation means water-soluble ≠ Barium causes chemical peritonitis
Reject analysis purpose
Improves department quality ≠ Not technologist discipline
Repeat threshold
Repeat only if non-diagnostic ≠ Not for slight rotation
Scope of practice
Alert radiologist to findings ≠ Never give the diagnosis
Mortise rotation
Rotate the whole leg ≠ Not the foot alone
Code colours vary
This set is Ontario ≠ Confirm your provincial list
Post-processing limits
Windowing changes display only ≠ Cannot recover lost anatomy
Last Minute
- 1.185 questions, 4 hours, Pass/Fail
- 2.Biggest bands: procedures, image quality
- 3.Leader and Scholarly Practitioner: 0%
- 4.Minimum 80% application questions
- 5.mAs = exposure; kVp = penetration
- 6.15% more kVp = half mAs
- 7.DI 0 on target; +3 double
- 8.Grainy image means low mAs
- 9.Dosimeter goes under the apron
- 10.Worker 20 mSv; public 1 mSv
- 11.Distance beats shielding in fluoroscopy
- 12.Fluid down, air up on decubitus
- 13.Chest: 180 cm, left lateral
- 14.Perforation suspected: iodinated, never barium
- 15.eGFR over 30: keep metformin
- 16.Rotate the leg for ankle mortise
- 17.Hip trauma: no rotation, cross-table
- 18.Marker in beam, not annotated later
- 19.Escalate urgent findings; never diagnose
- 20.Routine practices for every patient
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