The investigators hypothesize software-based fusion/navigation will be accurate to within 3 mm of the reference standard of EM fusion. The investigators aim to evaluate the accuracy of prostate US/MRI software-based fusion/navigation technology.

Inclusion Criteria:

• scheduled for ultrasound-guided gold seeds prostate fiducial placement prior to radiotherapy

Exclusion Criteria:

• eGFR < 45 mL/min/1.73m2
• recent (within 4 weeks) kidney or liver transplant
• contraindication to prostate MRI
• patient with cardiac pacemaker

This will be single center study. Subjects will be recruited from those referred to interventional radiology for ultrasound-guided prostate fiducial placement, or those planing to undergo ultrasound-guided prostate fiducial placement in radiotherapy clinic.