SU-E-J-195: Dosimetric Consequences of Metal Prosthesis in Prostate 3D CRT by Using Monte Carlo Dose Calculation...

Area of Science:

• Medical Physics
• Radiotherapy Oncology
• Image Processing

Background:

• Patient-specific metal prostheses introduce artifacts in CT imaging.
• These artifacts complicate accurate target volume delineation in radiotherapy planning.
• Understanding dosimetric consequences is vital for optimizing treatment delivery.

Purpose of the Study:

• To evaluate the dosimetric impact of metal artifacts in prostate radiotherapy.
• To assess the effectiveness of artifact correction and ultrasound-guided delineation.
• To analyze the influence of daily patient setup variations.

Main Methods:

• Simulated CT and 3D ultrasound images from three patients with metal prostheses.
• Treatment plans generated using artifact-degraded (PTVa) and artifact-corrected (PTVc) CT, and ultrasound-guided (PTVus) delineations.
• Dose calculations incorporating daily setup corrections using XVMC simulations.

Main Results:

• Artifact-corrected plans (PTVc) showed improved DVH curves and dose metrics compared to uncorrected plans (PTVa).
• Prostate planning target volume (PTV) volume increased by up to 5.2% with uncorrected CT.
• Rectum and bladder doses increased by up to 41.6% with artifact correction.

Conclusions:

• Metal artifacts significantly affect prostate radiotherapy planning and dose calculation accuracy.
• Artifact correction in CT imaging is necessary for precise dose delivery in cases with severe artifacts.
• Ultrasound-guided delineation offers negligible clinical benefit for target volume definition in this context.