Scatter and Zone of Occupancy for a Handheld X-Ray Device

Objectives: Scatter radiation (SR) from the patient could be of concern for the operator when using a handheld x-ray device. It is claimed that the KaVo NOMAD Pro-2 (KaVo Kerr) external shielding device (backscatter shield) creates a safety occupancy zone (OZ) that eliminates SR. The objective of this study was to test and verify this claim.
Methods: The scatter radiation of the KaVo NOMAD Pro-2 was tested in an operatory room evaluating the horizontal and vertical OZs. The SR was measured using a solid-state TNT 12000 Dosimeter detector and ion chamber. In the center of the room, the operator was located at the “0” degree coordinate point. From the “0” degree coordinate point, concentric circular tracings were made every 30 degrees on the floor. The exposures using the NOMAD Pro-2 were made at intervals of 10 seconds from a 0 to 140 cm distance in 35 cm increments, at 30-degree intervals, vertically and horizontally. The ion chamber was placed in each location, and a total of 88 exposures were made covering horizontal and vertical OZ.
Results: The highest SR at a horizontal OZ was reported at 180-degrees/35cm (0.79860µGy/hr). The highest SR measured at the vertical OZ was at 180 and 150-degrees at a distance of 35 cm (0.71986 and 0.56380µGy/hr).
Conclusions: The results of this study demonstrated that the SR exposure dose from the NOMAD Pro-2 was determined as being below the annual dose recommended limit (5.7µGy/hr-occupational limit). The study demonstrated that when the handheld device is used according to the manufacturer’s specifications, the operator will not be exposed to an increased risk of radiation, even in the worst case scenario where there is not an object to attenuate the direct path of the primary x-ray beam.