High-grade gliomas (HGGs) are the most common type of brain cancer in adults. Life expectancy for patients with HGGs is low. Radiotherapy aims to cure the tumour, but this is hard because HGGs are resistant to treatment. Among the possible causes of resistance may be tumour cells with low-oxygen levels (hypoxia). The investigators know that hypoxia reduces tumour sensitivity to radiotherapy. Using a special imaging technique called oxygen-enhanced MRI (OE-MRI), the investigators can try to identify areas of the tumour with hypoxia. The investigators could then give those areas a higher dose of radiotherapy. This might improve tumour control. This study aims to see if OE-MRI can find low-oxygen areas in HGGs. The study will also assess whether higher radiotherapy doses can be simulated in these regions.

Project summary:

1. Set up the OE-MRI process at Leeds Cancer Centre (LCC). OE-MRI settings will be tested on healthy volunteer participants to ensure the images are as good as possible.
2. Participant Imaging. Patient participants with HGG will be recruited to take part. OE-MRI will be used to image participants during their treatment and track low-oxygen areas before treatment, halfway through treatment and 3 months after treatment has finished.
3. Dose Escalation Assessment. Computer programs will be used to design radiotherapy treatments to test if higher radiation doses to the tumour's low-oxygen areas can better control the cancer. This will help understand if this targeted approach has potential benefits. This is modelling and will not alter routine clinical patient participant management.

Inclusion Criteria:

• ≥18yrs.
• Participants able to communicate with staff and safely comply with the study procedures.
• Participants to provide informed written consent.

Exclusion Criteria:

• Participants with any MRI contraindications including inability to lie flat in MRI scanner, claustrophobia and no foreign bodies, medical devices or other items which are considered an MRI contraindication.
• Geographically remote patients unable to agree to imaging schedule.
• Participants with illness or condition which means they cannot understand the requirements of the study.
• Participants with cardiac or pulmonary disease that are unable to tolerate the flow of oxygen delivered via a mask.
• Participants who have previously been treated with bleomycin (a chemotherapy used to treat some cancers including Hodgkin lymphoma and germ cell tumours).
• Participants with contraindications to gadolinium-based contrast agent