ARIBEX Nomad Pro 2 - Page 11

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Scatter
As discussed in
Section 2.1 Radiation Safety, the transparent shield on the NOMAD Pro 2
collimator, when properly oriented, acts as a barrier against backscatter radiation, making
it safe for the operator to stay in the room. As demonstrated by Chart 2, NOMAD Pro 2
whole body annual levels are less than 0.6% of the annual occupational dose limit.
CHART 2: Comparative Data for Whole Body Exposure (Annual)
50mSv
Occupational Dose Limit
1
5mSv Occupational Dose Limit Requiring Dosimetry
1
3.65mSv Average Natural Background Radiation
2
2.19mSv Average Occupational Radiation Exposure for Flight Crews
3
1.00mSv General Public Dose Limit
1
0.20-0.70mSv Range of Exposure for Dental Personnel Using Conventional X-rays
2
0.30mSv Average Exposure Using NOMAD with D-Speed Film
4
0.12mSv Average Exposure Using NOMAD with F-Speed Film or Digital Sensor
4
1) Standards for Protection against Radiation, 10 CFR 20 (US Federal Standards), 1994 (see also NCRP Report No.
116 and Suggested State Regulations for Control of Radiation D.1201).
2) NCRP Report No. 145 (National Council on Radiation Protection and Measurements), p7-9.
3) “Estimated Cosmic Radiation Doses for Flight Personnel,” Feng YJ et al, Space Medicine and Medical
Engineering, 15(4) 2002, p265-9.
4) Normalized average assumes 7,200 exposures per year, and the average length of exposure for D-speed =
0.50 seconds, F-speed = 0.25 seconds, digital sensor = 0.20 seconds.
The significant zone of occupancy for operators has been further verified by internal
testing. A NOMAD device was remotely fired into a water phantom repeatedly, with an
ion chamber recording radiation readings at 336 points in the room, first to establish the
vertical significant zone of occupancy and then to establish the horizontal significant zone
of occupancy. Each exposure was taken at 1.00 seconds in order to simulate “worse case
scenario” results. As seen in the following graphed information, the vertical significant
zone of occupancy measures 60 cm X 200 cm, while the horizontal significant zone of
occupancy is 60 cm X 60 cm.
Test points for product release testing
axis
axis