Date of Award


Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

First Advisor

Howard Forman


The purpose of this study is to quantify computed tomography (CT) scanner utilization and productivity in an academic hospital setting and determine the primary causes of idle time. Two CT scanners were observed for a total of 202 scanner-hours. Scanner time was divided into two primary components: "active" and "idle." Active time was further divided into preparation, scan, and take-down times. Independent variables recorded include in- vs. outpatient, IV contrast (IVC) vs. non-IVC, and scanner type. Primary contributors to idle time were identified in six main categories: preventative maintenance (PM), technical failure, upgrades, calibration, understaffing, and poor flow management. 275 CT scans and 10 CT guided procedures performed on 235 patients were observed. Total active time was 62:09:00 (30.75%). Average hourly weekday utilization was 20:56 min/hour (34.89%). Scanner utilization peaked from 4-5 pm at 34:35/hr (57.65%), and reached a minimum value of 3:10/hr (5.27%) between 11 pm and midnight. Total weekday idle time was 115:59:30 categorized as follows: poor flow management - 90:45:18 (78.24%), understaffing - 10:54:17 (9.40%), technical failure - 10:12:40 (8.80%), calibration - 2:15:00 (1.94%), PM - 1:01:15 (0.88%), and upgrades - 0:51:00 (0.73%). Average total exam time was 12:38 (n=218, SD 7:16) compared to a standard appointment block of 30 minutes. Average component times were preparation - 4:58 (n=218, SD 3:53), scan - 5:08 (n=224, SD 3:33), and take-down - 2:36 (n=225, SD 1:47). Contrast exams took longer than non-contrast exams with average total exam times of 17:05 (n=104, SD 7:21) and 8:34 (n=114, SD 4:09) respectively. Scanner type and in/outpatient status of the examinee did not significantly effect total study times, all four of these groups having average total exam times of 12-13 minutes. There is considerable under-utilization associated with the present operation of the CT scanners, primarily resulting from poor patient flow management. Implementing new scheduling processes, modifying appointment block lengths, and more effectively managing inpatient flow and scanner idle time, has the potential to significantly increase patient throughput.