5.3 Personal Dosimetry & Protective Apparel

5.3 Personal Dosimetry & Protective Apparel

Quick Answer: Wear your dosimeter correctly every shift, use lead-equivalent apparel matched to the work (apron, thyroid collar, glasses), wear your personal dosimeter under the apron whenever an apron is worn (Safety Code 35), adding an outside-collar badge only where facility policy uses one for lens/thyroid estimates, and QC lead for cracks—retire damaged gear. Dosimetry proves control of occupational dose; apparel and barriers reduce the dose you receive.

RTR.1 links three practical competencies: use protective devices, monitor your own exposure, and verify that apparel still works. On the exam, vignettes often test badge placement during fluoroscopy, apron lead equivalence, or what to do when an apron fails inspection.

Protective Devices and Apparel (RTR.1.1)

Protective apparel attenuates scatter (and accidental primary beam interception). It does not make standing in the useful beam acceptable.

Common devices

Lead equivalence

Protective garments are rated by lead equivalence (mm Pb), the thickness of pure lead that would provide the same attenuation at a specified beam quality. Typical teaching values used in departments:

Higher equivalence means more attenuation and usually more weight. Select apparel that meets facility minimums for the modality. Lightweight “lead-free” composite aprons can meet the same lead-equivalence rating—judge by rated mm Pb equivalence and integrity, not by the word “lead” alone.

Proper use habits

• Wear aprons before entering the scatter field; secure side fasteners so coverage is continuous.
• For fluoro, combine apron + thyroid collar + structural/hanging shields + distance.
• Do not use aprons as “patient blankets” for warmth; use designated patient shields when appropriate.
• After use, hang aprons on racks designed to prevent sharp folds. Folding and creasing crack lead/composite sheets over time.
• Never sit on aprons or pile heavy objects on them.

Monitoring Personal Exposure (RTR.1.7)

Occupational dose is tracked with personal dosimeters so that readings can be compared with regulatory limits and investigated if elevated.

Badge technologies (conceptual)

You do not need to design a dosimetry service for the exam, but you must wear the assigned badge correctly, exchange it on schedule, and report lost or contaminated badges immediately.

Wear rules (high-yield)

1. One person, one badge — never share.
2. Wear whenever occupational exposure is reasonably possible — including mobiles, fluoro, OR, and CT when policy requires (e.g., remaining in room).
3. Store properly off-duty — control board or designated area away from radiation rooms and heat sources; do not leave the badge on an apron hanging in the x-ray room (it will record room scatter and inflate or distort your occupational reading).
4. Do not intentionally expose the badge to the primary beam to “test” it.
5. Report unusual readings and participate in investigation (technique, apron use, badge left on tube head, etc.).
6. Declared pregnancy: follow policy for fetal dosimeter (often waist level under the apron) in addition to the standard badge.

Badge placement: under the apron, plus any extra badges (fluoro)

Health Canada Safety Code 35, section A.2.1 item 7: when a protective apron is worn, the personal dosimeter must be worn under the apron. Additional dosimeters may be worn — for extremities, or at the collar for lens/thyroid estimates — but they supplement the under-apron dosimeter rather than replace it.

Exam favourite: During fluoroscopy, the personal dosimeter goes under the apron. Safety Code 35 wants it to record the dose your body received behind the shielding, not the unattenuated scatter outside it. A collar badge worn outside the apron, where a facility uses one, is an additional dosimeter for lens/thyroid estimates, and a fetal badge belongs under the apron at the waist.

If a vignette says the technologist left the OSL on the portable machine overnight in the ED x-ray bay, the reading is invalid for personal dose—report and replace per policy.

Assessing Integrity of Protective Apparel (RTR.1.9)

Lead and lead-composite garments crack with age, folding, and mechanical stress. Cracks create radiation leak paths that defeat the rated equivalence.

Inspection program elements

1. Visual/tactile check before use: look for tears, sagging, separated seams, damaged belts, and contamination with contrast or body fluids (infection control + integrity).
2. Periodic imaging or fluoroscopic inspection per facility schedule (often annually or as policy states): lay apron flat and image or fluoro-scan for radiolucent crack lines.
3. Acceptance criteria: any crack pattern in critical coverage areas, thinning, or damage that compromises attenuation → remove from service, label defective, and send for repair or disposal per policy.
4. Documentation: inventory ID, inspection date, pass/fail, inspector—part of department QC culture.
5. Thyroid collars and skirts get the same scrutiny; small collars are easy to crease.

What cracks look like conceptually

On a fluoro check, intact lead looks relatively uniform; cracks appear as bright (radiolucent) lines or branching patterns. A few pinholes at edges may be assessed against policy thresholds, but significant central cracks over the torso are fail conditions.

Daily technologist responsibilities

You may not personally run the annual fluoro QC, but you are expected to:

• Notice and report a damaged apron immediately.
• Not use tape as a permanent “fix” for a cracked lead sheet.
• Choose an intact loaner apron rather than a known defective one “just for one case.”
• Hang and transport apparel correctly to prevent new damage.

Integrating Apparel + Dosimetry in Workflow

Mobile radiography

• Wear apron if you must remain near the patient; maximize distance when exposure is made.
• Ensure accompanying staff who stay also wear protection or leave the area.
• Badge on your body (correct position), not clipped to the portable column.

Fluoroscopy / interventional

• Wraparound apron + thyroid collar + eye protection as policy.
• Position ceiling and table shields before beam-on.
• Personal dosimeter under the apron; add an outside-collar badge for lens/thyroid estimates and a fetal badge if policy requires.
• Step back during DSA runs; use pulsed fluoro and collimation (links to 5.1).

CT

• Usually operate from the control room; if you must enter during beam-on (rare, policy-limited), full PPE and monitoring rules apply.
• Do not hold patients in the gantry primary beam.

General radiography rooms

• Expose from behind the barrier; apron still used when you must be in-room (pediatrics, trauma support).
• Keep public and non-essential staff outside; provide aprons if they must stay (e.g., parent with policy exception and training).

Common Failures and Exam Traps

Bottom Line for RTR.1.1 / 1.7 / 1.9

Protective apparel reduces scatter dose when rated, intact, and worn correctly. Personal dosimetry documents occupational exposure and depends entirely on correct wear and storage. Integrity checks close the loop: a cracked 0.5 mm Pb apron is no longer a 0.5 mm Pb apron. On CAMRT items, pick the option that places the badge correctly for the scenario, retires damaged lead, and never confuses patient contact shields with staff PPE duties.