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Updated: Jun 3, 2026
Use of MRI-ultrasound Fusion to Achieve Targeted Prostate Biopsy
Published on: April 9, 2019
Daily online bony correction is required for prostate patients without fiducial markers or soft-tissue imaging
M L Johnston1, P Vial, K L Wiltshire
1Northern Sydney Cancer Centre, Royal North Shore Hospital, Sydney, NSW, Australia.
Aim:
To compare online position verification strategies with offline correction protocols for patients undergoing definitive prostate radiotherapy.
Materials And Methods:
We analysed 50 patients with implanted fiducial markers undergoing curative prostate radiation treatment, all of whom underwent daily kilovoltage imaging using an on-board imager. For each treatment, patients were set-up initially with skin tattoos and in-room lasers. Orthogonal on-board imager images were acquired and the couch shift to match both bony anatomy and the fiducial markers recorded. The set-up error using skin tattoos and offline bone correction was compared with online bone correction. The fiducial markers were used as the reference.
Results:
Data from 1923 fractions were analysed. The systematic error was ≤1 mm for all protocols. The average random error was 2-3mm for online bony correction and 3-5mm for skin tattoos or offline-bone. Online-bone showed a significant improvement compared with offline-bone in the number of patients with >5mm set-up errors for >10% (P<0.001) and >20% (P<0.003) of their fractions.
Conclusions:
Online correction to bony anatomy reduces both systematic and random set-up error in patients undergoing prostate radiotherapy, and is superior to offline correction methods for those patients not suitable for fiducial markers or daily soft-tissue imaging.
