Radiation exposure to personnel during examination of limbs of horses witha portable hand-held fluoroscopic unit

Objectives-To determine radiation exposure to personnel during fluoroscopic imaging of limbs of horses with a portable unit and to determine distance from the c-arm at which radioprotective clothing is not required. Design-Repeated-measures cohort study. Sample Population-Part 1, 1 forelimb and 1 hind limb from each of 5 equine cadavers; parts 2 and 3, personnel involved during imaging of limbs of 5 an d 9 horses, respectively. Procedure-Radiation exposure rates were mapped around the suspended c-arm o f a portable fluoroscopy unit during imaging of various joints of equine ca daver limbs. During similar examinations in live horses, exposure rates to the fluoroscopist and assistant were measured. Mean duration for fluoroscop y of various joints was determined by observing an experienced fluoroscopis t. Exposure to fluoroscopists and assistants per examination and per annum was estimated. Results-Radiation exposure rates were dependent on distance and direction r elative to the c-arm and consistently highest on the tube side of the unit. Exposure was significantly greater than background amounts until approxima tely 4.7 m from the c-arm. During examination of live horses, exposure was highest to the fluoroscopist's hand nearest the tube. Typically, exposure t o the fluoroscopist and assistant during carpal examination was 25 to 40 ti mes greater than that for comparable radiographic examination. Annual expos ure for fluoroscopists was more than twice the recommended maximum permissi ble dose. Conclusions and Clinical Relevance-Fluoroscopic imaging of limbs of horses represents a major source of radiation exposure. Annual maximum permissible doses of radiation will be rapidly exceeded if required radioprotective cl othing is not worn.