Structural shielding design for medical X-Ray imaging facilities
Suggested occupancy factorsa (for use as a guide in planning shielding where other occupancy data are not available).
| LOCATION | OCCUPANCY FACTOR (T) |
|---|---|
| Administrative or clerical offices, laboratories, pharmacies and other work areas fully occupied by an individual; receptionist areas, attended waiting rooms; childrens’s indoor play areas, adjacent x-ray rooms, film reading areas, nurse’s stations, x-ray control rooms | 1 |
| Rooms used for patient examinations and treatments | 1/2 |
| Corridors, patient rooms, employee lounges, staff rest rooms | 1/5 |
| Corridor doorsb | 1/8 |
| Public toilets, unattended vending areas, storage rooms, outdoor areas with seating, unattended waitng rooms, patient holding areas | 1/20 |
| Outdoor areas with only transient pedestrian or vehicular traffic, unattended parking lots, vehicular drop off areas (unattended), attics, stairways, unattended elevators, janitor’s closets | 1/40 |
aWhen using a low occupancy factor for a room immediately adjacent to an x-ray room, care should be taken to also consider the areas further removed from the x-ray room. These areas may have significantly higher occupancy factors than the adjacent room and may therefore be more important in shielding design despite the larger distances involved.
bThe occupancy factor for the area just outside a corridor door can often be reasonably assumed to be lower than the occupancy factor for the corridor.
Primary beam use factors (U) for a general radiographic room determined from the survey of clinical sites (Simpkin, 1996a).a
| BARRIER | Use Factor (U)b | APPLY TO WORKLOAD DISTRIBUTION |
|---|---|---|
| Floor | 0.89 | Rad Room (floor or other barriers) |
| Cross-table wall | 0.09 | Rad Room (floor or other barriers) |
| Wall No. 3c | 0.02 | Rad Room (floor or other barriers) |
| Chest image receptor | 1.00 | Rad Room (chest bucky) |
aNote that the Rad Room (all barriers) workload distribution is not listed in this Table because it is only used for secondary barrier calculations.
bThe values for U represent the fraction of the workload from the particular distribution that is directed at individual barriers.reasonably assumed to be lower than the occupancy factor for the corridor.
cWall No. 3 is an unspecified wall other than the cross-table wall or the wall holding the upright image receptor (chest bucky).
Tabelle ottenute da: NCRP REPORT No.147 – Structural shielding design for medical X-Ray imaging facilities