Image guidance based on prostate position for prostate cancer proton therapy

Area of Science:

• Radiation Oncology
• Medical Physics
• Prostate Cancer Treatment

Background:

• Proton therapy offers precise radiation delivery for prostate cancer.
• Accurate patient positioning is crucial for effective proton therapy.
• Image guidance and daily adjustments are essential to account for anatomical variations.

Purpose of the Study:

• To evaluate the impact of image guidance and daily pre-beam reorientation on target coverage in proton therapy for prostate cancer.
• To quantify the improvements in clinical target volume (CTV) coverage and dose delivery accuracy.

Main Methods:

• Analysis of 207 prostate positions from 9 prostate cancer patients undergoing proton therapy.
• Definition of planning target volume (PTV) including prostate and margins.
• Simulated prostate repositioning with 5-mm and 10-mm shifts and multidimensional movements.
• Beam realignment after simulated prostate shifts.

Main Results:

• Realignment improved CTV coverage and minimal dose for small (<=5 mm) and large (10 mm) prostate shifts.
• Significant dose improvements observed for anterior, posterior, inferior, and superior shifts.
• Compounded multidimensional shifts showed substantial gains in CTV V(78) (11.8%) and minimal dose (23.6 GE) after realignment.
• Post-realignment, CTV minimal dose exceeded 98% of the prescribed 78 GE for all analyzed points.

Conclusions:

• Proton beam realignment after target shifts enhances CTV coverage in prostate cancer patients.
• Daily pre-beam reorientation is a valuable tool for optimizing dose delivery in proton therapy.
• This technique improves treatment accuracy and potentially patient outcomes.