Proton radiography and proton computed tomography based on time-resolved dose measurements

Area of Science:

• Medical Physics
• Radiological Imaging
• Radiation Oncology

Background:

• Current proton therapy requires accurate range verification for effective treatment and reduced side effects.
• Real-time imaging of moving tumors is crucial for adaptive radiation therapy, but challenging with conventional methods.
• Proton computed tomography (pCT) offers potential advantages over X-ray CT for proton therapy planning.

Purpose of the Study:

• To demonstrate a proof-of-principle for proton radiography and pCT using time-resolved dose measurements.
• To evaluate the technique's accuracy for static phantom imaging and potential for real-time imaging of moving targets.
• To assess the feasibility of pCT reconstruction for improved proton stopping power mapping.

Main Methods:

• Utilized a prototype 2D diode-array detector for fast, time-resolved dose rate measurements.
• Acquired proton radiographic images directly in water equivalent path length (WEPL) by analyzing time-dose patterns.
• Reconstructed pCT images from 2D WEPL distributions behind phantoms.

Main Results:

• Demonstrated accurate WEPL determination for static phantoms, relevant for medulloblastoma brain field range verification.
• Showcased potential for real-time imaging of moving phantoms (~100 ms acquisition time) without interplay effects.
• Successfully reconstructed pCT images of phantoms with varying materials, yielding reasonable results with the prototype detector.

Conclusions:

• Time-resolved dose measurements offer a novel, rapid, and low-dose method for proton radiography and pCT.
• The technique shows promise for accurate beam range verification and real-time tumor tracking in proton therapy.
• Further development of detector resolution and accuracy could lead to advanced clinical imaging capabilities.