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FMEA occurrence values for four failure modes occurring using look-up tables for dose calculations
Geoff Nelson1, Adam Paxton1, Jeremy Kunz1
1Department of Radiation Oncology, University of Utah, Salt Lake City, UT, USA.
Journal of Applied Clinical Medical Physics
|November 16, 2020
Summary
Manual dose calculations for treatments like Total Body Irradiation (TBI) are prone to errors. Reviewing five years of TBI calculations revealed frequent discrepancies, particularly in data lookup and rounding, highlighting the need for automated solutions.
Area of Science:
- Medical Physics
- Radiation Oncology
- Radiotherapy Dosimetry
Background:
- Institutions commonly use databook tables for radiotherapy dose calculations, such as Total Body Irradiation (TBI).
- Manual data lookup and transcription from tables introduce potential for calculation errors.
- Understanding the frequency and types of these errors is crucial for developing safer workflows.
Purpose of the Study:
- To analyze the frequency and nature of discrepancies in manual Total Body Irradiation (TBI) dose calculations.
- To identify common sources of error in TBI calculations performed using databook tables.
- To inform the development of protocols aimed at reducing calculation errors in radiotherapy.
Main Methods:
- A retrospective review of five years of Total Body Irradiation (TBI) calculations was conducted.
- Each calculation was re-performed and compared against the original calculation and its second check.
- Discrepancies were categorized by source (e.g., table lookup, typo, rounding) and tallied.
Main Results:
- All identified discrepancies resulted in a monitor unit (MU) calculation difference of less than 1.7%.
- Rounding or avoiding interpolation was the most frequent discrepancy type (53.1%), followed by typos (10.4%).
- Errors in table lookup (6.3%) and skipping steps (4.2%) also contributed to discrepancies.
Conclusions:
- Despite small overall impact on MU (<1.7%), various calculation discrepancies occur frequently.
- Manual data lookup and rounding are significant sources of potential error in TBI calculations.
- Automated calculation forms are recommended to minimize human interaction and reduce transcription errors.
Keywords:
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