Shielding

Radiation Services Inc. offers assistance to facilities constructing or modifying diagnostic imaging rooms using ionizing radiation. Almost all rooms in which x-ray producing equipment is operated require shielding to protect individuals outside the room or in the Control Booth operating the equipment.

While anything with mass attenuates x-rays or gammas rays, common building materials that provide some shielding (concrete block, filled concrete block, poured concrete) often do not substantially contribute to radiation protection and additional shielding is required.

The most common shielding materials are lead lined sheets of dry wall or plywood. Shielding material for windows is commonly leaded glass or leaded acrylic. Lead lined doors and door frames are also available to shield openings into the rooms. It is important to remember that all joints in the shield be protected with backing strips and that all penetrations to the shielding barrier be back shielded as well.

Some equipment such as mammography units (including screening, diagnostic, tomosynthesis and stereotactic breast biopsy) as well as DEXA units (bone densitometry or Dual Energy X-Ray Absorptiometry) seldom require more shielding than that provided by normal drywall construction.

In determining the thickness of lead required in walls or other barriers, it is necessary to know several aspects of the equipment use.

1. The type of unit producing the radiation and its output
2. The Workload: how many patients of what exam types will be imaged each week
3. The Use Factor: if the system can change the orientation of the x-ray tube, what options are possible and what portion of the Workload will be delivered at these positions (i.e. lateral exams in a radiographic room)
4. Blueprint or schematic indicating the room dimensions, the location of the x-ray unit and image receptors, dimensions of adjacent or surrounding areas.
   • For a multi-story facility, the construction of the intervening (above and/or below) floors including the structural composition (usually poured concrete) and the minimum thickness of those floors.
   • The distance from the floor of the diagnostic imaging room to the floor of the occupied areas above and/or below.
5. Occupancy Factor: information about the use of areas adjoining the diagnostic imaging room (e.g. hallway, toilet, another x-ray room, office, etc.)

Radiation Services’ board certified physicists will work with you to obtain all necessary data. Then, using recognized calculation procedures, a shielding design plan will be generated indicating the minimum lead required to be installed in all barriers surrounding the radiation emitting device. We incorporate all regulatory requirements and published guidance into our shielding calculations.

• The Florida Control of Radiation Hazard Regulations (Chapter 64E-5, F.A.C.)
• NCRP Report No. 147: Structural Shielding Design for Medical X-Ray Imaging Facilities
• Report No. 177 – Radiation Protection in Dentistry and Oral & Maxillofacial Imaging (2019) (Supersedes Report No. 145)
• AAPM Task Group 108: PET and PET/CT Shielding Requirements.
• TJC Prepublication Requirements Revised Requirements for Diagnostic Imaging Services Issued January 9, 2015 EC.02.06.05 A4.

Please contact us today to learn more about how Radiation Services, Inc. can help you.