Module 11 - Facilities and Equipment Requirements Flashcards
What is the primary goal when designing an X-ray facility?
To minimize radiation exposure to workers, patients, and the public.
What are the three main stages of X-ray facility design?
Facility plan preparation, room layout planning, and shielding requirement determination.
What is the annual dose limit for radiation workers in controlled areas?
20 mSv.
What is the annual dose limit for the public in uncontrolled areas?
1 mSv.
What is the dose constraint for sensitive populations in uncontrolled areas (e.g., pediatric wards)?
0.3 mSv/year.
What must radiology rooms accessed from public areas include?
Self-closing doors and radiation warning signs.
What is the purpose of primary protective barriers?
To shield from the direct X-ray beam.
What is the purpose of secondary protective barriers?
To shield from scatter and leakage radiation.
Which factor measures how often the X-ray beam is directed at a barrier?
Use factor (U).
What does the occupancy factor (T) represent?
The fraction of time a space is occupied during X-ray use.
What is considered a primary barrier in a radiographic room?
The wall behind the upright bucky and the floor beneath the table.
Should the X-ray tube ever be directed at the control booth?
No.
What document outlines regulatory limits for X-ray shielding calculations?
NCRP Report 147 (or Report 49).
What is the regulation that governs medical X-ray equipment in Canada?
The Radiation Emitting Devices Act.
What must all X-ray operators and involved personnel use?
Protective devices and personal dosimeters.
What must be done if a radiation worker declares pregnancy?
Limit fetal dose to 4 mSv for the remainder of pregnancy.
How long must dosimetry records be kept?
For the lifetime of the facility.
What does the beam-limiting device ensure?
Field size doesn’t exceed 5 × 5 cm at 100 cm FID.
What does the automatic exposure control (AEC) do?
Regulates exposure to maintain consistent image quality.
What must all digital display devices undergo before clinical use?
Daily quality checks.
What is the purpose of PACS in a digital imaging system?
To store, retrieve, and manage diagnostic images efficiently.
What does a radiation protection survey assess?
Whether exposure levels are within regulatory limits.
When must a radiation protection survey be conducted?
Upon installation, after modifications, and periodically.
What must be done before disposing of X-ray equipment?
Perform a final survey and remove radiation-producing parts.
What is the maximum leakage radiation allowed from an X-ray tube housing at 1 meter?
1.0 mGy/hour.
What are the three steps in planning a medical X-ray facility?
Prepare facility plans, consider room design/layout, and determine shielding requirements.
What must a facility plan include for shielding assessment?
Room dimensions, equipment location, control booth, adjacent room use and occupancy, image processing areas, barrier types, materials, and door/window positions.
What is the difference between controlled and uncontrolled areas?
Controlled areas are for radiation workers (limit: 20 mSv/year); uncontrolled areas are for the general public (limit: 1 mSv/year).
What constraint dose applies in uncontrolled areas with sensitive populations?
0.3 mSv/year (e.g., pediatric or obstetric wards).
What features must a diagnostic room with stationary equipment accessed by the public have?
A self-closing door and warning signs with the X-ray symbol and ‘Unauthorized Entry Prohibited.’
Why should the X-ray beam be directed only toward shielded areas?
To prevent radiation exposure to adjacent rooms or areas.
What is the purpose of a control booth in X-ray room design?
To shield the operator, ensuring occupational exposure is ≤ 0.4 mSv/week.
What makes shielding ‘primary’ vs ‘secondary’?
Primary barriers intercept the direct beam; secondary barriers protect against scatter and leakage.
What three factors are used in shielding calculations?
Workload (W), Occupancy factor (T), and Use factor (U).
How is workload (W) defined in shielding design?
As the total mA·min per week; based on patient volume and X-ray procedures.
What does the occupancy factor (T) represent?
The proportion of time an area is occupied during X-ray operations.
What does a use factor (U) of 1 mean?
The X-ray beam is directed at the surface for 100% of the workload.
Why are shielding barriers made continuous and structurally sound?
To prevent radiation leaks; lead shielding must be supported to avoid ‘creeping.’
What law governs X-ray equipment in Canada?
The Radiation Emitting Devices Act.
What must be done before each X-ray exposure?
Ensure non-essential persons exit the room and the operator uses protective devices.
Who must wear personal dosimeters?
Declared radiation workers and anyone likely to receive over 1 mSv/year.
What happens if a radiation worker declares pregnancy?
Their dose must be limited to 4 mSv for the remainder of the pregnancy.
Can equipment be left on and unattended?
No—machines energized and ready to emit radiation must not be left unattended.
What is radiation output reproducibility?
Radiation output must vary less than 5% across 10 exposures under identical conditions.
What is the limit for current-time product per exposure?
600 mAs for tube voltage ≥ 50 kVp.
What does the AEC (automatic exposure control) do?
Regulates exposure based on patient size and composition to maintain consistent image density.
What is the acceptable variation in AEC exposure for digital systems?
Ratio of highest to lowest data values ≤ 1.2 or within manufacturer specs.
What does beam limiting equipment do?
Allows adjustment of field size; minimum field must be ≤ 5 cm × 5 cm at 100 cm FID.
How close must light and X-ray fields align?
Within 2% of the source-to-image distance.
What is the minimum focal spot-to-skin distance in fluoroscopy?
30 cm (mobile), 38 cm (stationary), 20 cm (special applications).
What is the maximum air kerma rate in fluoroscopy?
150 mGy/min with AIC and high-level control active.
What is the purpose of a last image hold?
Displays the last captured fluoroscopic image to avoid unnecessary re-exposure.
How often should CR imaging plates and cassettes be cleaned?
Regularly, at least monthly, and inspected for damage or contamination.
What must be done before using digital display devices?
Daily performance checks for distortion, luminance, and resolution.
What is the purpose of PACS in radiology?
To archive, retrieve, and manage diagnostic images efficiently.
When should radiation protection surveys be conducted?
At initial installation, after modifications, and periodically during use.
Who should perform shielding calculations and surveys?
Qualified personnel trained in structural shielding design, like a medical physicist.
What must be done before disposing of X-ray equipment?
Disable radiation-producing parts, conduct a final survey, and document the process.
What documentation is required during X-ray equipment disposal?
A record of removal, transfer, or destruction, and radiation survey results.
