• Reproducability of DW-MRI [ Time Frame: 7 months ]
  Apparent diffusion coefficient (ADC)
• Reproducibility of DCE-MRI [ Time Frame: 7 months ]
  Using volume transfer constant
• Reproducibility of DCE-MRI [ Time Frame: 7 months ]
  Using leakage space as a percentage of unit volume
• Reproducibility of DCE-MRI [ Time Frame: 7 months ]
  Using rate constant
• MP-MRI Response Correlation [ Time Frame: 7 months ]
  Developing methods to identify and delineate areas of tumour according to their response to radiotherapy treatment by correlating MP-MRI kinetic parameters with anatomical T2 MRI images
• Assessment of adapted dosimetry [ Time Frame: After week 3 of radiotherapy ]
  Amount of acceptable radiotherapeutic dose

• Reproducability of MRI [ Time Frame: 4.5 months ]
  Including the apparent diffusion coefficient (ADC) for DCE MRI
• MP-MRI Measurability [ Time Frame: at 3 weeks of RT ]
  MP-MRI sequence measurement within the dominant tumour nodule
• MP-MRI Response Correlation [ Time Frame: 7 months ]
  Developing methods to identify and delineate areas of tumour according to their response to radiotherapy treatment by correlating parameters such as ADC, Ktrans, ve and kep with the anatomical T2 MRI images
• Evaluating dosimetry [ Time Frame: 7 months ]
  Amount of acceptable radiotherapeautic dose

• Assessment of cell kill [ Time Frame: 3 months ]
  Proportion of cells killed at given dose following androgen deprivation therapy
• Tumour response prediction [ Time Frame: 7 months ]
  Assess which proportion of tumours demonstrate areas of poor response that could benefit from adaptive radiotherapy

Mount Vernon Cancer Centre at East and North Hertfordshire NHS Trust offers patients with certain cancers a treatment called adaptive radiotherapy. The aim of adaptive radiotherapy is to respond to physical changes that occur during treatment to ensure the radiation continues to be directed at the cancer and to minimise the amount of healthy tissue treated. For example, if tumour shrinkage or weight loss occurs during head and neck radiotherapy the patient may have a repeat CT scan and a new radiotherapy treatment plan after a few weeks of treatment. For patients with cancer of the bladder or cervix changes in bladder and uterus size and position can be predicted allowing the prospective creation of three radiotherapy treatment plans, each day the best fitting plan, i.e. the one that closely covers the tumour whilst giving minimal dose to normal tissues, is selected and used for treatment, this is known as plan-of-the-day adaptive radiotherapy.

Small changes in shape and position of the prostate occur but are generally the result of rectal changes which cannot be predicted, consequently adaptive radiotherapy based on physical change is not possible for prostate cancer treatments. However, recent literature suggests that magnetic resonance imaging (MRI) can detect changes within the prostate in response to radiotherapy, some studies have seen changes as early as the second week of radiotherapy treatment. A feasibility study to investigate if these changes can support radiotherapy treatment plan adaption for prostate cancer treatments is proposed, whether the plan can be adapted to give a higher treatment dose to any areas of the prostate that show poor response to radiotherapy without increasing bowel and bladder dose is of particular interest. The treatment for patients who participate in the study would not be changed but the results may help to personalise and improve the treatment of future patients.

Inclusion Criteria:

1. New diagnosis of high-risk prostate cancer: any of:

   1. Gleason score of 8, 9 or 10
   2. PSA > 20
   3. T3/4
2. Patient due to receive androgen deprivation therapy (ADT)
3. Prescribed 78Gy/39# external beam radiotherapy
4. Measurable dominant intraprostatic tumour on diagnostic imaging of at least 10mm diameter
5. ≥18 years of age
6. ECOG performance status of 0-1
7. Informed, written and witnessed consent to participate is required.

Exclusion Criteria:

1. Patients who are not due to receive androgen deprivation therapy (ADT)
2. Any contraindication to MRI scanning including contraindication to MRI contrast agents
3. Previous radiotherapy to the pelvis
4. Any physical or social reasons that would make attendance for additional visits impossible.
5. Any patient with or planned for prostate fiducial markers.
6. Unable to give informed consent.
7. Patients currently enrolled in an interventional clinical trial.