Evaluation of radiation exposure to operators of portable hand-held dental X-ray units.

The use of hand-held dental X-ray units is increasing within Australia since their portability is advantageous in applications such as aged care. However, proximity of the operator to the X-ray unit raises radiation safety concerns. The aim of this study was to evaluate operator radiation exposure and methods of dose reduction for the Rextar X camera-style hand-held dental X-ray unit. Leakage and scattered radiation were measured using a solid state detector. Scatter was generated using a Perspex head phantom. Measurements of scattered radiation dose as a function of distance were made with and without a lead acrylic scatter shield (0.6 mm Pb equivalence at 100 kVp) attached to the X-ray unit. Without the scatter shield, doses to the operator from a single adult maxillary molar X-ray exposure were 0.69, 0.78 and 0.47 µGy at the left hand, right hand and eyes respectively. With the scatter shield attached, doses were reduced to 0.25, 0.12 and 0.15 µGy respectively, corresponding to a dose reduction of 64, 85 and 68%. The contribution from leakage radiation was insignificant in comparison. It is highly unlikely that an operator would reach occupational dose limits when using the Rextar X hand-held dental X-ray unit, even without the scatter shield in place. Nevertheless, it is strongly recommended that the scatter shield is attached to keep operator doses as low as reasonably achievable. Use of the scatter shield additionally ensures compliance with the Australian legislative requirement for a protective barrier and is considered a preferable alternative to X-ray protective clothing.