Risk Management of Clinical Reference Dosimetry of a Large Hospital Network Using Statistical Process Control

Area of Science:

• Medical Physics
• Radiation Oncology
• Quality Assurance

Background:

• Managing TG-51 reference dosimetry across a large hospital network presents significant challenges.
• Ensuring consistent and accurate dosimetry is critical for patient safety and effective radiation therapy.

Purpose of the Study:

• To evaluate the efficacy of Statistical Process Control (SPC) in managing TG-51 workflow within a large hospital network.
• To establish a standardized method for monitoring and controlling reference dosimetry processes across multiple facilities.

Main Methods:

• Annual reference dosimetry in water according to TG-51 was performed at all network sites.
• Ion chambers were cross-calibrated in plastic phantoms for monthly QA output measurements.
• An energy-specific dimensionless beam quality cross-calibration factor was derived and analyzed using SPC, including mean, standard deviation, Upper Control Limit (UCL), and Lower Control Limit (LCL).

Main Results:

• Control limits (±3σ) ranged from 1.7%-2.6% for the main campus and 3.3%-4.2% for satellite sites.
• Wider control limits at satellite sites were linked to workflow variations.
• Standardizing workflow effectively narrowed control limits.

Conclusions:

• Statistical Process Control (SPC) is a highly effective tool for managing TG-51 reference dosimetry in large, multi-site hospital networks.
• SPC successfully identifies and helps mitigate workflow variations, leading to improved consistency and accuracy in dosimetry QA.
• Standardization of dosimetry procedures is crucial for optimizing SPC effectiveness and reducing variability across network facilities.