case study

Industry: Healthcare

CT Scan Throughput

FOCUS: Improve the daily throughput of patients on two CT scanners used by North Shore-Long Island Jewish Health System.


The turnaround time (TAT) for the hospital’s radiology CT department was in excess of what the customers felt it should be. Averaging 20.7 hours with variation from 8 hours to 34 hours the physicians, case management registered nurses, and hospital leadership all expected an average TAT of 16 hours.


Once the team was formed a baseline was conducted to determine the current capability. Additional Voice-of-Customer was obtained. A Kaizen was planned, the project scoped, and the charter initiated. During the first day a measurement system analysis was conducted on the baseline data. TAT was defined as the time from CT order until the test was performed. A defect was defined as any CT that took over 16 hours. Data showed that 4 out of 10 scans exceeded 16 hours. After a value stream map was developed, steps were classified as value added, business non-value added, and non-value added. Search for waste began. A cause-and-effect diagram was used to identify the key drivers that influenced the CT throughput rate: workspace, workflow, and scheduling. On the second day Lean Six Sigma tools were used along with 5S to improve the workspace. A spaghetti diagram was used to help improve the workflow. Several modifications to the scheduling portion of the process were made. The team expanded the visibility of the schedule both inside and outside the CT department. In addition, “pull” scheduling was implemented. On the third day, equipment was moved and some construction took place. The mix of outpatients and inpatients scheduled was adjusted to create more even flow. Lastly, optimal patient flow was achieved by designating one of the scanners for complex procedures and the other for more routine type procedures. On the last day of the Kaizen, the improvements were tested and then strategies were developed for implementation. The team developed a follow-up action list with deliverable dates specified.


Average TAT decreased from 20.7 hours to 11.6 hours with the defect rate decreasing by over 60%. The increased capacity generated $375,000 in additional revenue.

* For additional information see iSixSigma Magazine, Jan/Feb 2007, pgs 43-50, “CT Scan Throughput” by Nancy B. Riebling, Angelo Pellicone, Antz Joseph, and Charles Winterfeldt.