Patient position verification with oblique radiation beams

Area of Science:

• Radiation oncology
• Medical imaging
• Cancer treatment

Background:

• Accurate patient positioning is crucial in radiotherapy for head and neck cancers.
• Current verification methods often involve additional anterior-posterior (AP) and lateral beams, increasing treatment time and complexity.

Purpose of the Study:

• To evaluate if patient positioning during radiotherapy for head and neck cancer can be accurately determined using portal images from oblique radiation beams.
• To assess the potential to eliminate the need for supplementary AP and lateral verification beams.

Main Methods:

• Patient position was determined using portal images from oblique radiation beams.
• These positions were compared to those determined from standard AP and lateral verification beams.
• Analysis included 751 portal images from 18 patients.

Main Results:

• Setup errors in ventrodorsal and craniocaudal directions were accurately determined from oblique beams, comparable to AP/lateral beams.
• An additional AP beam was required for equivalent accuracy in the lateral direction due to beam angles.
• Position verification was more accurate with AP and lateral beams for patients receiving both oblique gantry angles and isocentric table rotations.

Conclusions:

• Oblique radiation beams can be effectively used for position verification in head and neck cancer radiotherapy when only oblique gantry angles are employed.
• This approach may streamline radiotherapy procedures by potentially replacing conventional verification beams in specific techniques.