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Implementation of QA Procedures and Their Effect On the Radiation Treatment Delivery Error Rate Over a 12 Year Period

S Wasserman*, V Feygelman, E Moros, H. Lee Moffitt Cancer Center, Tampa, FL

SU-E-T-239 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Treatment deviations have been tracked from 2000 to the present covering over 23,000 treatment courses and 420,000 fractions. During this period multiple error reduction actions were taken including implementation of an electronic record and verify system (ERVS), a departmental weekly QA meeting, a time out procedure, a dosimetry boarding pass and ACR accreditation preparation. This study will examine error rates before and after these actions to estimate the effect on the overall and categorical error rates.

Methods: A treatment deviation was defined as any error in radiation treatment delivery that reached the patient. Deviations were catalogued by type of error, detection method, number of fractions delivered prior to detection, and percentage of treatment course affected by the deviation.

Results: The use of ERVS was incrementally applied to linacs from 1999 until 2006 by which time all linac treatments were electronically verified. In 2006 a weekly QA meeting and a requirement for a patient specific dosimetry boarding pass were started. A treatment timeout procedure was initiated in 2007. Standards were modified to meet ACR standards during 2007-08 resulting in accreditation. From 2000- 2002 the overall error rate averaged 5.4 per 1000 treatments (0.0054) and decreased to 0.0024 for the 2005-2007 period with 2004 being an outlier due to a single upstream error affecting multiple patients. The rate continued to decline to 0.0019 for 2008-09 and to 0.0010 for 2010-12.

Conclusion: Simultaneous technology and procedural changes make it difficult to correlate the effect of individual changes directly to the error rate. Nevertheless, the data clearly shows a progressive error rate reduction as QA procedures were implemented. Reduction in some classes of errors can more easily be tied to specific changes. We believe the combined implementation strongly contributed to an overall culture of safety resulting in a reduced error rate.

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