The purpose of this study is to better understand a new type of radiology test called positron emission tomography (PET) with carbon 11 methionine to determine which patients have a beneficial effect from anti-cancer therapy with the drug docetaxel.

In the week before the patients first dose of chemotherapy they will receive a C11 methionine PET scan which takes about 90 minutes. C11 methionine is a radioactively labeled amino acid that is given to the patient intravenously.

Eighteen to twenty days after the patients first dose of docetaxel chemotherapy, they will have another C11 methionine PET scan which is identical to the first scan.

At the end of three cycles of docetaxel chemotherapy (about 2 and 1/2 months on study) another C11 methionine PET scan will be done.

The PET scans will show how well the tumor is taking up methionine.

Inclusion Criteria:

• Metastatic hormone-refractory prostate cancer patients who are planned to begin every 3-week docetaxel chemotherapy
• Progression after androgen deprivation therapy
• Serum testosterone < 50ng/ml
• 18 years of age or older

Exclusion Criteria:

• Prior taxane therapy