Conformal dose escalated radiotherapy was adopted as the standard treatment technique at PMH for intermediate risk patients with localised disease in 1997. This technique provides a much smaller margin of error for treatment set-up and delivery than with conventional techniques. One way to ensure the accuracy of treatment delivery is to image the prostate position daily, prior to therapy, to allow for appropriate set-up corrections. To do so, imaging markers are implanted into the prostate under guided ultrasound (a standard procedure at PMH). However, there are disadvantages in using imaging markers which include added time to the treatment planning process, and an invasive procedure with a potential for discomfort, bleeding and infection. This study will investigate and compare X-ray volume imaging to the gold standard imaging markers.

Inclusion Criteria:

• Diagnosis of adenocarcinoma of the prostate
• Patient undergoing escalated dose conformal external beam radiotherapy.
• Patient has low or intermediate risk prognostic factors: all of PSA <21, Gleason score <8, clinical T category \