Patients having radiotherapy to their head and neck wear an immobilisation shell to prevent patient movement and improve treatment accuracy. These shells tend to cover the face and have the potential to cause anxiety and distress in patients, particularly if they suffer with claustrophobia or a similar fear. The study will use an 'open-face' shell that does not cover the face and compare this with the investigators' current 'closed-face' shell. The investigators will obtain treatment verification x-ray images to assess the daily set-up errors and compare these between the two shell type, and ask both patients and radiographers of their experiences from using the shells.

Hypothesis: Open-face immobilisation shells offer equivalent accuracy and efficiency of radiotherapy delivery and are better accepted by patients and radiographers as compared to closed-face immobilisation shells for cranial radiotherapy.

Patients will be randomised into one of two groups, with group A acting as the control group using the investigators' standard 3--point closed--face shell, and group B using the 3--point open--face shell (experimental group). Each procedure is discussed with the patient before commencement. Patients will be positioned into the optimal treatment position and the shell will be fabricated as per manufacturer instructions by pre-treatment radiographers. This is followed by the patient having a planning CT scan of their head while wearing their shell to allows radiographers and doctors to localise and plan the treatment. At the end of this appointment, the patient will be asked to complete the first of three questionnaires regarding their experience of wearing the shell. Radiographers will be asked to complete a questionnaire of their experience of using the shell, and complete timing data for the procedures.

On the first day of treatment, radiographers will discuss the treatment process and side effects of treatment with the patient, and treatment will be delivered under current department protocols using linear accelerators (linacs). During the course of the treatment, radiographers will obtain 5 sets of verification images for the study, and these will be assessed for set-up errors as per current department policy. Where possible, treatment fields will be used to verify patient position to keep radiation doses from verification imaging as low as reasonably practicable (ALARP). Patients will be asked to complete two more questionnaires on their experience, one on their first day and one on their last day of treatment. Radiographers will also complete questionnaires on these days. Timing data will be obtained for all treatment fractions.

The patient's perspective of the planning and treatment processes will be almost identical to that of patients having cranial radiotherapy that are not in the trial. The only differences that will be observed will be the use of an open-face shell (for patients in group B), completion of three questionnaires, and additional verification imaging.

Inclusion Criteria:

• patients prescribed cranial radiotherapy using virtually simulated parallel opposed fields with:
• 5 or more fractions of virtually simulated cranial radiotherapy
• treatment for Primary Central Nervous System Lymphoma (PCNSL), prophylactic cranial irradiation (PCI), or primary or secondary cerebral or bony lesions

Exclusion Criteria:

• patients unable to give informed consent
• patients requiring conformal or inverse-planned radiotherapy
• patients requiring stereotactic radiotherapy
• patients who have previously had cranial or head and neck radiotherapy

All IPD that underlie results in publication

Starting 6 months after publication for a period of one year.

Requests via corresponding author for interested parties working in the field of Radiation Oncology. Information will be shared by corresponding author.