SU-E-T-280: Optimal Angle for a Dual-Field Stanford Technique for TSET

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Techniques

Background:

• Total Skin Electron Therapy (TSET) is crucial for treating widespread skin conditions.
• Optimizing beam angles is essential for achieving dose uniformity in TSET.
• Extended source-to-surface distances (SSD) present unique challenges in TSET planning.

Purpose of the Study:

• To determine the optimal gantry angles for a dual-field Stanford technique in TSET at extended SSDs (1-5 m).
• To develop a predictive algorithm for optimal TSET angles applicable to any extended SSD.
• To simplify the physics commissioning process for TSET using the dual-field Stanford technique.

Main Methods:

• Utilized a diode array detector to measure dose profiles at various SSDs (1-5 m).
• Employed a dual-field Stanford technique with gantry angles ranging from 70°-78° and 110°-102°.
• Analyzed flatness profiles to identify optimal angle pairs for each SSD, leading to algorithm development.

Main Results:

• The optimal angle for TSET varies with SSD, with specific angle groups identified for each distance.
• At an SSD of 5 m, an optimal angle of 106° yielded the best vertical axis flatness.
• At an SSD of 4 m, an optimal angle of 18° was found to be optimal.

Conclusions:

• An algorithm for optimal dual-field Stanford TSET angles can be derived from the study's findings.
• This algorithm simplifies the physics commissioning process for radiation oncology centers.
• The developed technique facilitates accurate dose delivery in TSET at extended SSDs.