Quality and operations of portable X-ray examination procedures in the emergency room: queuing theory at work

The objective of this study was to evaluate the operation of the portable X-ray machine in relation to examinations ordered by the Emergency Department at the University of Medicine and Dentistry of New Jersey, as well as to identify any bottlenecks hindering the performance of the aforementioned system. To do so, the activity of the portable X-ray was monitored in the period from 8 June 2004 to 24 June 2004, as well as from 6 July 2004 to 12 July 2004, yielding 11 days of data and 116 individual X-ray examinations. During observation times was noted for various checkpoints in the procedure. Using the data gathered, the average input, output, processing times, and variance were calculated. In turn, these values were used to calculate the response times for the Ordering Phase (5.502 min), traveling (2.483 min), Examination Phase (4.453 min), returning (3.855 min), Order Processing Phase (2.962 min), and the Development Phase (3.437 min). These phases were combined for a total of 22.721 min from the time the examination was placed to the time the X-ray films were uploaded to the PACS computer network. Based on these calculations, the Ordering Phase was determined to be the single largest bottleneck in the portable X-ray system. The Examination Phase also represented the second largest bottleneck for a combined total of 44% of the total response time.