Program Information
Decision Opportunities in Radiation Therapy Treatments
W.T. Watkins and J.V. Siebers, University of Virginia Health System, Charlottesville, VA
Presentations
SU-D-BRD-5 Sunday 2:05PM - 3:00PM Room: Ballroom DPurpose: A method to reveal tradeoffs in radiation therapy treatments is introduced in order to aid in clinical, patient-specific decision making.
Methods: A clinically acceptable treatment plan was varied for two patients, a stereotactic body radiation therapy (SBRT) lung cancer case and a pituitary case, in order to reveal decision opportunities. Plans were optimized such that non-zero dose-volume objectives were defined for all organs at risk (OARS). At fixed planning target volume (PTV) dose, a single OAR is sacrificed, i.e. the weight of the dose volume objective is deceased, and potential dosimetric benefits in other regions of interest are identified. If tradeoffs are identified, plans are stored and presented as decision opportunities.
Results: Clinically relevant tradeoffs were revealed by sacrificing individual OARs. The SBRT lung case was planned according to the Radiotherapy-Oncology Group (RTOG) 0813 protocol, but by violating the high-dose protocol objective (>2 cm from the PTV) in the patient's lung, mean heart dose was reduced by 1.7 Gy and the great vessel V20 was reduced from 42% to 2%. Tradeoffs in dose to the chestwall and heart were also revealed, an increase of 6 Gy in chestwall-Dmax reduces heart mean dose by 0.9 Gy and mean dose to the great vessels by 2.6 Gy. For the pituitary tumor, sacrificing the right parotid gland (increasing mean dose from 7.8 Gy to 14.1 Gy) spares the temporal lobes bilaterally (V20 is reduced by 4%) and left parotid mean dose is reduced from 6.4 Gy to 5.2 Gy.
Conclusion: Clinical tradeoffs in radiation therapy treatment planning are revealed by sacrificing individual OARS. By revealing these tradeoffs, decision making in plan selection is simplified and can be considered in the context of patient-specific quality of life.
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