Cone beam computed tomography image guidance within a magnetic resonance imaging-only planning workflow

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiotherapy Planning

Background:

• Magnetic Resonance Imaging (MRI)-only workflows present image guidance challenges.
• Developing effective image guidance strategies is crucial for MRI-only treatment planning.

Purpose of the Study:

• To evaluate the feasibility of MRI to Cone Beam Computed Tomography (CBCT) image guidance within MRI-only planning workflows.
• To assess the impact of focused training on radiation therapists' ability to perform MRI-CBCT matching.

Main Methods:

• A training package was developed and administered to ten radiation therapists.
• Image matching was performed on four anatomical regions (prostate gold seed, prostate soft tissue, rectum/anal canal, gynaecological) using CBCT data compared to CT and MRI.
• Inter-observer variation in matching was recorded for each region.

Main Results:

• Median inter-observer variation for both MRI-CBCT and CT-CBCT matching was within 2 mm and 1 degree across all regions.
• No significant association was found between radiation therapist experience levels (clinical image guidance or MRI) and inter-observer variation, except for specific regions.
• Significant differences in inter-observer variation were noted for prostate gold seed and rectum match regions based on MRI experience.

Conclusions:

• The study supports the successful implementation of MRI to CBCT image guidance in clinical settings.
• Focused training is a key factor in achieving reliable image guidance for MRI-only radiotherapy planning.
• This approach enhances the viability of MRI-only workflows for improved treatment accuracy.