A point dose method for in vivo range verification in proton therapy.

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Range uncertainty in proton therapy poses a challenge, sometimes necessitating suboptimal beam angles.
• Current in vivo dosimetry methods for photon/electron therapy do not verify proton beam range.
• Existing proton therapy techniques may limit treatment benefits due to range uncertainty concerns.

Purpose of the Study:

• To develop and evaluate a novel in vivo dosimetry method for verifying proton beam range.
• To address the limitations of current dosimetry techniques in proton therapy.
• To reduce range uncertainty in proton therapy for improved treatment precision.

Main Methods:

• Proton fields were split into two separate fields, each delivering a 'sloped' depth-dose distribution.
• The two fields were directed oppositely to maintain a constant dose plateau over the target volume.
• A ratio of doses measured from both fields was calculated to determine water-equivalent path length.

Main Results:

• The proposed method allows for in vivo verification of the water-equivalent path length to the dosimeter.
• This technique effectively limits range uncertainty to the remaining beam path beyond the dosimeter.
• Phantom measurements demonstrated the feasibility of this approach for in vivo range verification.

Conclusions:

• This novel dosimetry approach offers a viable solution for in vivo proton beam range verification.
• The method enhances the accuracy of proton therapy by mitigating range uncertainties.
• Further application in clinical settings could significantly improve treatment efficacy and patient safety.