10
2.2 Studies and Data on Leakage and Scatter
Besides direct beam, potential exposure from X-ray devices has only two other possibilities:
1) leakage radiation and
2) scatter radiation from the patient/
subject in the direct beam.
Leakage
Unique internal shielding of NOMAD
Pro 2 encases the X-ray tube, practically
eliminating leakage radiation. This makes
it safe to use Pro 2 as a handheld device
during exposures. As demonstrated by
Chart 1, NOMAD Pro 2 hand and extremity
annual levels are less than 0.1% of the
annual occupational dose limit.
CHART 1: Comparative Data for Hand and Extremity Exposure (Annual)
500mSv
Occupational Dose Limit
1
50mSv Occupational Dose Limit Requiring Dosimetry
1
0.43mSv Average Exposure Using NOMAD with D-Speed Film
2
0.22mSv Average Exposure Using NOMAD with F-Speed Film or Digital Sensor
2
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) “Radiation Exposure with the NOMAD Portable X-ray System,” Goren AD et al, Dentomaxillofacial Radiology, 37
(2008), S.109-12; normalized average (includes leakage and backscatter radiation) 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.
FDA regulations specify that leakage radiation from X-ray devices not exceed 0.88mGy/hr,
while IEC regulations stipulate that devices stay below 0.25mGy/hr, an even tighter limit.
In response to these regulations, Aribex will only ship product that tests below 0.02mGy/hr for
leakage, a self-imposed requirement 44 times more stringent than FDA regulations and
12.5 times more stringent than IEC regulations.
In order to verify compliance with this leakage requirement, each individual device is
tested with a calibrated survey meter at 12 points on the device housing, as shown in the
following diagram. The highest measurement out of these 12 points is reported on the
device Certificate of Conformance (which is shipped with every device) and must be lower
than 0.02mGy/hr in order for the device to successfully pass product release testing.
X-ray Source
Focal Spot
Primary Protective
Shielding
Backscatter
Radiation
Shielding
Fixed Beam
Limiting Device
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