A Novel Approach for Position Verification and Dose Calculation through Local MVCT Reconstruction

Area of Science:

• Medical Physics
• Radiotherapy Technology
• Image Reconstruction

Background:

• Cone-beam computed tomography (CBCT) for radiotherapy patient positioning can introduce errors due to isocenter misalignment.
• Accurate patient positioning is critical for effective radiation delivery and minimizing off-target dose.

Purpose of the Study:

• To introduce an innovative method for precise patient positioning verification in radiotherapy.
• To overcome the limitations of traditional CBCT by utilizing the treatment radiation source.

Main Methods:

• Acquisition of 10 electronic portal imaging device (EPID) transmission images from distinct angles.
• Sparse reconstruction of local megavoltage computed tomography (MVCT) using the ART-TV algorithm.
• 3D mutual information registration of reconstructed MVCT with planning CT for error detection and correction.

Main Results:

• Reconstructed MVCT images meet the requirements for accurate registration.
• The registration algorithm effectively identifies patient positioning discrepancies.
• The method allows for precise adjustments to the treatment setup and accurate absorbed dose calculation.

Conclusions:

• The developed method provides accurate 3D patient positioning verification in radiotherapy.
• Utilizing the treatment beam source eliminates errors associated with CBCT isocenter misalignment.
• This technique enhances treatment accuracy and patient safety by enabling precise positional corrections.