Magnetic resonance image-based tomotherapy planning for prostate cancer

Area of Science:

• Radiation Oncology
• Medical Imaging
• Radiotherapy Physics

Background:

• Helical tomotherapy is a precise radiotherapy technique for prostate cancer.
• Accurate dose calculation requires reliable patient imaging.
• CT-based imaging is standard but involves ionizing radiation.

Purpose of the Study:

• To compare the feasibility of MR image-based planning using synthetic CT (sCT) versus conventional CT (pCT) for helical tomotherapy in prostate cancer.
• To evaluate the accuracy of dose distribution calculations using sCT compared to pCT.

Main Methods:

• Retrospective analysis of 16 prostate cancer patients treated with helical tomotherapy.
• Acquisition of MR images using a dedicated therapy sequence.
• Generation of sCT images using MRCAT and recalculation of dose distributions.

Main Results:

• Mean planning target volume doses calculated by sCT and pCT differed by 0.65% ± 1.11% (p = 0.03).
• Three-dimensional gamma analysis (2%/2 mm) showed a high pass rate of 0.976.

Conclusions:

• MR-only simulations provide dose distributions in good agreement with CT-based simulations for tomotherapy in prostate cancer.
• Mean dose differences for target volumes and organs at risk are less than 1%.