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SU-E-T-562: Reducing the Arc Span for CSA VMAT Delivery.
P Myers1,2, S Stathakis1,2, A Gutierrez1,2
1Cancer Therapy and Research Center at UT Health Science Center, San Antonio, TX.
Medical Physics
|May 19, 2017
Summary
Using multiple, shorter, sub-arc deliveries for cranio-spinal axis (CSA) irradiation significantly reduces normal tissue doses compared to full arc treatments. This approach ensures adequate target coverage while potentially improving patient outcomes in radiation therapy.
Area of Science:
- Radiation Oncology
- Medical Physics
Background:
- Cranio-spinal axis (CSA) irradiation is a complex radiotherapy technique.
- Optimizing dose delivery while minimizing toxicity is crucial for CSA treatments.
Purpose of the Study:
- To compare the dosimetric advantages and disadvantages of using multiple, shorter, sub-arc deliveries versus traditional full arc deliveries for CSA irradiation.
Main Methods:
- Five CSA patients were replanned using both full arc and split sub-arc techniques.
- Dose distributions were evaluated for planning target volume (PTV) coverage and normal structure sparing.
- Conformity number, homogeneity index, maximum doses, and mean doses were assessed.
Main Results:
- Sub-arc plans showed slightly lower PTV conformity but improved homogeneity compared to full arc plans.
- Nearly all evaluated normal structures received lower maximum and mean doses with sub-arc deliveries.
- Beam on times were comparable, with sub-arc plans having lower monitor units.
Conclusions:
- Sub-arc treatment deliveries offer dosimetric benefits for CSA irradiation by reducing normal tissue toxicity.
- This technique provides adequate PTV coverage and presents a favorable alternative to full arc deliveries.
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