Development of a semi-automatic alignment tool for accelerated localization of the prostate

Area of Science:

• Radiation Oncology
• Medical Imaging
• Prostate Cancer Treatment

Background:

• External beam radiation therapy for prostate cancer requires precise targeting to maximize tumor control.
• Accurate prostate localization is crucial to avoid missing the target and damaging surrounding tissues.
• Reducing planning target volume (PTV) margins can decrease rectal toxicity.

Purpose of the Study:

• To present a rapid computed tomography (CT)-based online prostate localization method.
• To enable precise daily localization of the prostate before external beam radiation therapy.
• To facilitate safe dose escalation and reduce toxicity by minimizing PTV margins.

Main Methods:

• Patients undergo daily CT scans in the treatment position immediately before each session.
• Prostate extents are manually identified on axial CT slices.
• Prostate displacements are calculated by fitting identified extents to a planning CT template.
• The method was evaluated retrospectively on 106 CT scans from 8 prostate cancer patients.

Main Results:

• Five axial CT slices provided reliable prostate position correction, comparable to physician-drawn contours.
• The daily CT extent-fitting method achieved 97% PTV coverage of the posterior prostate gland.
• This method significantly outperformed daily (74%) and weekly (65%) bony matching on portal images.

Conclusions:

• Daily CT extent fitting offers precise and rapid prostate localization.
• The method is less time-consuming than extensive daily contouring.
• It is clinically feasible for accelerated daily prostate localization, improving treatment accuracy and safety.