Program Information
Feasibility of Using the Automated Beam Gating Interface with the Active Breathing Coordinate for Hypofractionated Radiation Therapy
S Lee1*, Y Zheng2 , T Podder3 , J Sohn4 , (1) University Hospitals Cleveland Medical Center, Cleveland Heights, OH, (2) University Hospitals Cleveland Medical Center, Cleveland, OH, (3) University Hospitals Cleveland Medical Center, Cleveland, OH, (4) University Hospitals Cleveland Medical Center, Case Western University, Cleveland, OH
Presentations
PO-BPC-Exhibit Hall-24 (Saturday, March 18, 2017) Room: Exhibit Hall
Purpose: Automated beam gating using active breathing coordinate (ABC) improves efficiency of radiation delivery to target, reducing lung and heart toxicity associated with lung or breast radiation therapy (RT). The current Response gating interface (Elekta) for deep inspiration breath-hold (DIBH) technique requires attention when automated beam gating is used for SBRT. We assessed the lung volume confined by the ABC with respect to the induced air flow rate from patients during the course of radiation therapy.
Methods: The patients’ breathing recorded by the ABC device during breast RT were retrospectively analyzed. The flow rate was estimated from the lung volume at the time of breath-hold, which is recorded by the ABC. The lung volumes over flow rate was quantified at every treatment and evaluated with respect to the reference volume obtained in CT simulation during the course of treatment. The precision of the air volume configured in ABC was assessed at 3.0 liter of nominal volume with varying air flow rate.
Results: Overall, the flow rates were ranged from 0.28 to 1.84 liter/sec for patients at the breath-holding thresholds set to 1.1- 1.8 liter. For the patients showed the 8% and 50% of increases in the mean lung volume and mean flow rate, respectively throughout the entire treatment. The increase in flow rate from 0.62 to 1.84 liter/sec resulted in the 25% of increase in lung volume, which can cause the difference in lung volumes up to 25%. The air volume configured by ABC shows the increased uncertainty as flow rate increases within 1% over the nominal volume.
Conclusion: The clinical use of the automated beam gating interface with ABC equipped requires high attention for high-precision radiation therapy.
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