Radiation Shielding Information and Guidance

1. Radiation Shielding Information and Guidance Don Parry, Health Physicist Michigan Department of Consumer & Industry Services Radiation Safety Section dparry@michigan.gov

2. Radiation Shielding Information • Plan Reviews • Plans should be submitted prior to construction! • Rule 331(2) of the Ionizing Radiation Rules states that shielding is subject to design approval by the department • Most medical x-ray rooms should normally be provided with 1/8 inch thick lead for primary barriers (including floors) and 1/16 inch thick lead for secondary barriers (including doors) • Construction of an x-ray room without an approved plan may cause shielding modifications to be done after the room is constructed Radiation Safety Section

3. Radiation Shielding Information • Form BHS/HFS 852 – Information Required for a Radiation Shielding Plan Review • Available on Web site • Be sure to include all requested information including: • Plans or blueprints of rooms and adjacent areas to scale with compass directions. (1/4” = 1 foot preferred) • Location of x-ray equipment, x-ray table,wall bucky, exposure switch, viewing window and control panel • Description of occupancy of adjoining areas including above or below • Description of floor and ceiling construction including minimum concrete thickness and density. Radiation Safety Section

4. Radiation Shielding Information • Form BHS/HFS 852 (Continued) • Be sure to include all requested information including: • Location,type, thickness and height of proposed shielding • Indicate thickness and density of concrete and masonry materials • Limits of travel of table, tube and image receptor • Maximum kVp, mA and estimated workload in mAmin/wk • For CT scanners, include a copy of the iso-exposure curves normally provided by the manufacturer • Name and address of facility • Name and address to send response letter Radiation Safety Section

5. Radiation Shielding Information • Shielding Guidance • Barriers should be designed for weekly radiation dose limits of 10 millirem per week for controlled area and 0.5 millirem per week for uncontrolled areas • Vertical barriers must extend from the floor to a minimum height of 7 feet. • If it is necessary to add additional shielding to the ceiling of the room, then the shielding in the walls must be extended above the 7-foot height to overlap the ceiling shielding. Radiation Safety Section

6. Radiation Shielding Information • Shielding Guidance • If there are multi story buildings in close proximity of the x-ray room, which have occupied spaces that could be exposed to scatter radiation that is not attenuated by the 7-foot high wall shielding, additional shielding may be necessary to protect those areas • Outside walls and, particularly, windows may require shielding to protect distant areas even if the nearest occupied area is not immediately adjacent Radiation Safety Section

7. Radiation Shielding Information • Operator Booth Shielding Guidance • The lead glass viewing window should have an area of at least 1 square foot • At least 1 square foot of the viewing window should be centered no less than 2 feet from the open edge of the booth and be centered 5 feet from the floor. • The operator should be allotted not less than 7.5 square feet of unobstructed floor space in the booth Radiation Safety Section

8. Radiation Shielding Information • Operator Booth Shielding Guidance • The operator’s booth should have no dimension less than 2 feet. • The exposure switch needs to be permanently fastened behind the operator’s barrier so that the operator is protected from primary, first-scattered, and leakage radiation, even at arm’s length from the switch. • The booth shall be located or constructed such that unattenuated direct scatter radiation originating on the examination table or at the wall-mounted image receptor will not reach the operator's position in the booth. • Additional guidance available on web site Radiation Safety Section

9. Radiation Shielding Information • Certificate of Need • Equipment that requires a CON will not be registered until plans have been reviewed by the Radiation Safety Section. • At least 1/16 inch lead normally is required for the walls of a CT room. CT rooms with high workloads and adjacent uncontrolled occupied areas may need shielding that is thicker than 1/16 inch lead. • Facilities with CT x-ray equipment may want to enlist the services of a qualified medical physicist for shielding advice. Plans would still need to be submitted to RSS for review. Radiation Safety Section

10. Radiation Shielding Information • Dental Cephalometric and Tomographic Equipment. • Dental cephalometric equipment requires shielding of the primary beam with 1/16 inch thick lead • Dental Tomographic equipment requires primary beam shielding along with a fixed operator’s barrier with an exposure switch in a location at least arms length from the line of scatter. • Dental extra oral facilities should submit plans for review and approval to the RSS Radiation Safety Section

11. Radiation Shielding Information Floors Need to use minimum thickness of concrete floor in shielding calculations Need to know density of concrete (147 lbs/ft3 standard) Radiation Safety Section

12. Radiation Shielding Information • Examples • No Occupancy above or below • On Slab • Shielding should be floor to 7’ • 1/16 inch thick secondary, 1/8 inch thick primary 1/8 inch lead (blue) Leakage Scatter 1/16 inch lead (red) Radiation Safety Section

13. Radiation Shielding Information Examples Occupied space below Need 1/16 inch thick lead on floor with 1/8 thick lead under table Floor shielding should overlap wall shielding Radiation Safety Section

14. Radiation Shielding Information Examples Crawl space Occupied space above Need lead in floor under table to prevent scatter under vertical barriers Wall shielding needs to overlap ceiling shielding Radiation Safety Section

15. Radiation Shielding Information Examples CT with adjacent Multi Story Building May need additional shielding on outside wall Occupied uncontrolled space in adjacent building Adjacent Multi Story Building Radiation Safety Section

16. Radiation Shielding Information Examples Exposure switch location Switch needs to be arms length from first scattered and leakage radiation Switch Location Adjacent Multi Story Building Radiation Safety Section

17. Radiation Shielding Information • Summary • Submit shielding plans to the Radiation Safety Section for design approval prior to construction! • Dental extraoral equipment such as cephalometric and tomographic units should also have shielding plans approved. • Include all information requested on form BHS/HFS 852. • Equipment that requires a Certificate of Need will not be registered until a plan is reviewed • Most rooms will be adequately shielded with 1/8 inch thick lead for primary barriers and 1/16 inch thick lead for secondary barriers. • Be sure to consider areas above and below the x-ray room when designing shielding. Radiation Safety Section

18. Contact Information Headquarters:Radiation Safety SectionMichigan Department of Consumer & Industry ServicesP.O. Box 30664Lansing, Michigan 48909 Phone: (517) 241-1989Fax: (517) 241-1981 Visitor/delivery address:5th Floor, G. Mennen Williams Building525 W. Ottawa StreetLansing, Michigan 48933 District Office:Our district office, formerly in Pontiac, has moved to: Radiation Safety SectionMichigan Department of Consumer & Industry Services38600 Van Dyke, Suite 375Sterling Heights, Michigan 48312 Phone: (586) 446-0200Fax: (586) 446-0227 Radiation Safety Section