There are substantial uncertainties with contemporary seed placement techniques in prostate brachytherapy, particularly with the impact of seed movement after an implant due to edema and migration of seeds in the prostate and peri-prostatic tissues. This study will accrue 20 patients undergoing prostate brachytherapy implants and perform serial CT and MRI scans at specified intervals (pre-operatively, day 0, day 3, day 10 and day 28) to characterize these phenomena.

Prostate brachytherapy is an effective treatment option for men with localized prostate cancer with excellent cure rates and a favorable toxicity profile. Having a more detailed understanding of seed movement after an implant will provide clinicians with details about the clinical impact of these phenomena on implants and provide the detailed understanding of these phenomena that are necessary for more sophisticated brachytherapy implants that are envisioned in the future.

Inclusion Criteria:

• treated with prostate brachytherapy
• low risk or intermediate risk prostate cancer
• ambulatory
• stable medical condition
• 18 years of age or older
• capable of informed consent

Exclusion Criteria:

• no use of any hormonal therapy
• unable to have MRI scans (ie. presence of metallic foreign object, aneurysm clip, cardiac pacemaker, internal wires, implanted pump, implanted cardiac device, claustrophobia, etc.

Patients seen at an academic institution (tertiary centre ...Cross Cancer Institute) for consideration of prostate brachytherapy