Methods: One operator exposed 180 projections simulating 10 Full Mouth Series (FMX) per study on a RANDO phantom (The Phantom Laboratory, Salem, NY). Seven total studies were completed using either handheld or wall-mounted x-ray sources. F-speed film settings for an average adult were used. The wall-mounted source incorporated a 7cm diameter open cone while the hand-held device utilizes a 6cm open cone. Optical Stimulated Luminescence (OSL) dosimetry was utilized to record operator and phantom dose (Nanodot, Landauer Inc., Glenwood, IL). Three dosimeters per area were attached to thyroid, waist and trigger hand areas of the operator prior to each study. Dosimeters were placed within the phantom in twenty-four predetermined anatomic locations (Ludlow et al 2008). Dosimeters were read with a MicroStar reader (Landauer Inc., Glenwood, IL). Effective dose was derived using the 2007 ICRP calculation. Operator exposures and phantom doses were evaluated separately using Analysis of Variance (ANOVA).
Results: Mean (SD) FMX dose was significantly less for the Nomad Pro 36µSv (8.4) than for wall-mount 98µSv (14.3) (p=0.0217). Mean operator exposures were indistinguishable from ambient background levels (<2 µGy/study) and were not different for handheld and wall mounted sources (p=0.2624) or dosimeter location (p=0.6815).
Conclusions: Operator dose was indistinguishable from background dose and not different for wall-mounted and Nomad Pro sources during FMX imaging simulation. Patient dose was reduced by 63% using the hand-held device. Patient dose reduction may be attributed to the reduced diameter of the Nomad Pro cone. The Nomad Pro is as safe to use for operators and safer to use for patients in comparing doses with conventional wall-mounted sources using round-cones.
Keywords: Dosimetry and Radiology