Impact of Advanced Technologies on the Rate of Deviations in Radiation Treatment Delivery

Article Outline

• Purpose/Objective(s)
• Materials/Methods
• Results
• Conclusions
• Copyright

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Purpose/Objective(s) 

External radiation therapy (RT) is a human endeavor, and thus, may not be delivered as intended. Newer RT delivery technologies, (e.g. intensity-modulated RT [IMRT] using multileaf collimators [MLC] and image guidance) are being adopted, in part, to improve accuracy of RT. This study examines the impact of new technologies on the treatment deviation rate.

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Materials/Methods 

RT treatment deviation rates were prospectively monitored during a time of technology upgrade. In Jan 2003, we had 3 linacs (ages 11–22 yrs), all with “low” technology (e.g. without MLC). In 2003–4, we upgraded to 5 new linacs, all controlled with record-and-verify; 4 were “high” technology (defined as those with MLC). The deviation rates among patients treated on “high” vs “low” tech linacs (i.e. with vs without MLC) were compared over time with a 2-tailed Fisher's exact test.

Hypotheses:

1) Safeguards inherent to “high tech” yield fewer deviations than “low tech” methods. 2) Deviation rates on “high tech” will decline with time, reflecting increased experience with new technologies.

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Results 

In 2003, the deviation rates on the “high” and “low” tech units were similar (p = 0.45), contrary to hypothesis #1. However, by 2005–6, the deviation rate was lower on the “high” vs. “low tech” units (p < 0.001), consistent with hypothesis #1. The lower deviation rate seen with “high” vs “low” tech in 2005–6 was due to

By 2006, the deviation rate on “high tech” was lower than our 2003, pre-upgrade, “low tech” deviation rate (p = 0.01). As treatment complexity is greater with “high tech” units (e.g. IMRT), the reduced deviation rate suggests safeguards inherent with “high tech” approaches are effective. None of the deviations resulted from technical malfunctions, but rather typically involved human factors: e.g. data entry, documentation, and patient set-up (Table 1).

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Conclusions 

Advanced RT delivery systems appear to reduce the rate of treatment deviations. Deviation rates on “high tech” linacs decline over time, suggesting a “learning curve” after the introduction of new technologies. The increase in deviations with “low tech” approaches was unexpected and may reflect a growing over-reliance on the tools inherent to “high tech” machines. As new technologies are introduced, continued diligence is needed to assure that staff remains proficient with “low tech” approaches. We have instituted additional procedures to reduce deviation rates for patients treated with “low” and “high” technologies.

Summary of Results: Deviation Rates, % (# of deviations/total # of treatments)

Note: No deviations were considered clinically-meaningful, nor resulted in patient injury.