The purpose of this study is to assess how accurately SmartTarget can direct high intensity focused ultrasound (HIFU) to a pre-defined area (cancer) in the prostate.

The current standard methods for treating prostate cancer are directed to the whole gland - either surgery to remove it or radiotherapy. An alternative method is focal therapy. This is surgery that uses an energy source to ablate the cancer whilst preserving the normal healthy tissue.

Prior to surgery prostate cancer can often be localised using MRI imaging and detailed prostate biopsy techniques. The difficulty is that during surgery it is very difficult to accurately locate the cancer on the live ultrasound images - to compensate surgeons will treat half or a quarter of the prostate to ensure that the cancer is treated. This may cause higher rates of side-effects.

SmartTarget is an MRI to ultrasound fusion device that maps the pre-treatment MRI onto the live ultrasound during surgery. It then provides a target for the surgeons to treat during the operation.

The results will measure if the area intended to treat was covered and if how accurate the treatment was by comparing the pre-treatment MRI with a 1 week post treatment scan

Inclusion Criteria:

1. Histological diagnosis of prostate cancer (PSA </=15ng/ml, Gleason score </=4+3, and radiological stage </=T3aNoMo)
2. Prostate biopsy concordant with mpMRI lesion (template transperineal or MRI-targeted biopsy only)
3. Discrete lesion on mpMRI scoring 3, 4 or 5 on radiological scale of suspicion
4. mpMRI carried out according to European Society of Uro-Radiology guidelines at 1.5T or 3T
5. An understanding of the English language sufficient to understand written and verbal information about the trial and consent process
6. Signed informed consent

Exclusion Criteria:

1. No lesion on mpMRI
2. Bilateral lesions on mpMRI
3. mpMRI undertaken over 6 months prior to visit 1
4. Contralateral Gleason >/=3+4 and/or Maximum Cancer Core Length Involvement >/=6mm
5. Men who have taken any form of hormones (except 5-alpha reductase inhibitors) within the last 6 months
6. Prior immunosuppression or predefined immunosuppressed state
7. An irreversible coagulopathy predisposing to bleeding
8. Unable to undergo transrectal ultrasonography
9. Previous radiation therapy to the pelvis
10. Previous HIFU, cryosurgery, thermal, irreversible electroporation, radiofrequency or microwave therapy to the prostate.
11. Men with evidence of metastatic disease or nodal disease outside the prostate on bone scan or cross-sectional imaging
12. Men not fit for major surgery as assessed by a consultant anaesthetist
13. Men who are unable to give informed consent