Ch 15

• Radiographers are at an increased risk of exposure to scatter radiation during certain procedures.

Procedures Increasing Radiographer Risk

• General fluoroscopy involves continuous x-rays, raising exposure risk
• Interventional procedures use high-level control fluoroscopy also known as HLCF
• Mobile and C-arm fluoroscopy increases the radiation risk

Dose-Reduction Methods and Techniques

• Avoid repeat imaging to limit radiation exposure
• The patient is the main source of scattered radiation.
• Stand at a 90-degree angle to the primary x-ray beam at 1m distance to reduce exposure
• The scattered x-ray intensity at this position is approximately 1/1000 of the primary x-ray beam intensity
• Protective apparel is a vital radiation protection step.
• Personnel should be protected from secondary radiation, like scatter and leakage
• Always use devices or techniques that lessen the amount of scattered radiation

Protective Apparel

• Minimum lead equivalent for standard radiography is 0.25 mm
• Recommended lead equivalent for standard radiography is 0.5 mm
• Minimum lead equivalent for fluoroscopy is 0.5 mm, with a recommendation for thicker material
• Use appropriate technical exposure factors to reduce extra exposure
• Never stand in the primary beam to restrain a patient during a radiographic exposure
• Use mechanical restraining devices whenever possible
• Pregnant women should never assist in holding a patient during an exposure.

Protection for Pregnant Personnel

• Pregnant personnel can continue working if following radiation safety practices
• Facilities should have policies in place for protecting pregnant personnel from radiation
• There should be a voluntary declaration of pregnancy
• Healthcare facilities should officially recognize the pregnancy
• Facilities must provide counseling and an additional fetal monitor through its RSO.

Maternity Protective Apparel

• Maternity apparel should have 0.5-mm lead equivalent over the entire length and width
• The apparel must include an extra 1-mm lead equivalent protective panel running transversely across the apron's width

Protective Structural Shielding in X-Ray Rooms

• Walls and doors are designed to shield personnel and the public from radiation
• Common barrier materials are lead and concrete
• Protection requirements are ascertained by a qualified medical physicist.

Primary Protective Barrier

• A primary barrier is used to prevent direct, or unscattered radiation from reaching other areas
• A primary barrier is typically positioned perpendicular to the undeflected line of travel of the x-ray beam
• It consists of 1.6 mm (1/16 inch) of lead
• It extends 2.1 m (7 feet) upward from the floor of the x-ray room

Secondary Protective Barrier

• It protects against secondary radiation, including leakage and scatter radiation
• Any wall or barrier not directly struck by the primary x-ray beam constitutes a secondary protective barrier
• Secondary radiation can hit primary barriers as well
• It should overlap the primary protective barrier by approximately 1.27 cm (1/2 inch)
• It consists of 0.8 mm (1/32-inch) of lead
• Examples include the door of the x-ray room and the control booth barrier

Control-Booth Barrier

• Protects the radiographer from secondary radiation such as leakage and scatter
• Found in x-ray rooms housing permanent or nonportable radiographic equipment
• Must extend 2.1 m upward from the floor and be permanently secured
• Diagnostic x-rays should scatter at least two times before reaching any area behind this barrier
• Include a lead glass window, typically with 1.5 mm (1/16-inch) lead equivalent

Clear Lead-Acrylic Secondary Protective Barrier

• Composed of clear lead-acrylic material containing approximately 30% lead by weight
• Allows a panoramic view, aiding diagnostic imaging personnel in observing the patient more completely

Modular X-Ray Barriers

• Shatter resistant
• Can extend 2.1 m (7 feet) upward from the floor for adequate protection
• Comes in lead equivalencies from 0.3 to 2 mm

Accessory Protective Devices and Lead Thickness

• Aprons have a lead thickness of:
  • Minimum: 0.25 mm
  • Recommended: 0.5 mm
  • Fluoroscopy: 0.5 mm
• Thyroid shields have a lead thickness of 0.5 mm
• Protective eyeglasses have a lead thickness of 0.35 mm
• Gloves have a lead thickness of 0.25 mm

Diagnostic X-Ray Suite Protection Design Considerations

• Factors must be considered in the design of x-ray suites to ensure radiation protection
• Workload (W) refers to the radiation output-weighted time the unit delivers radiation during the week.
• Inverse Square Law refers to the intensity of an x-ray beam lessening as the distance from its source increases.
• Use factor (U), aka beam direction factor, the proportion of beam-on time that the x-ray beam is directed at a primary barrier during the week
• Occupancy factor (T) involves how many people should be occupying the space or room behind the barrier.

Controlled and Uncontrolled Areas

• Controlled area is used only by occupationally exposed personnel, next to an x-ray room wall
• The weekly maximum permitted equivalent dose (MPED) is 1000 µSv or 1 mSv
• An uncontrolled area is open to the general public, like a hallway or corridor
• The weekly maximum permitted equivalent dose (MPED) is 20 µSv.

Radiation Caution Signs

• Radiation caution signs are essential for safety in radiology departments
• Include a beam-on indicator sign and general postings.