Preoperative Preradiotherapy TTFields

Inclusion Criteria: * Patient is aged \>35 years (age range of more likely to suffer from an IDHwt World Health Organisation (WHO) grade 4 astrocytoma)\* * Patient is male or female. * Patient has a new radiological diagnosis of glioblastoma. * Patient has a performance status judged by WHO, Eastern Cooperative Oncology Group (ECOG) score = 0-1. * Patient has been reviewed by Neuro-oncology multidisciplinary team (MDT - neurosurgeon, clinical oncologist, radiologist and pathologist); MDT consensus that offering study entry is clinically appropriate and safe i.e. patient unlikely to come to harm (e.g. hydrocephalus) from delayed surgery and pre-operative Optune based on available clinical information and imaging. * PI has confirmed at the first clinic visit that study entry is clinically appropriate and safe (e.g. lack of severe and debilitating symptoms of raised intracranial pressure). * There is intention to treat the patient with surgical resection and postoperative adjuvant therapy as per current standard of care (40Gy/15 fr or 60Gy/30fr). * Patient has adequate haematological and biochemical parameters for surgery and contrast agent administration (full blood count and coagulation profile deemed acceptable by clinical team, eGFR \>30ml/min). * Patient has mental capacity to consent for treatment. * Patient is able and willing to give informed consent Criteria specific to the experimental arm: * Patient is able and willing to comply with study protocol requirements to continuously shave their head * Patient is able and willing to comply with study protocol requirements to wear Optune equipment for the required duration. Exclusion Criteria: * Patients with uncontrolled seizures. * Patients are due to undergo a planned biopsy procedure only. * Patients have a suspicion of other tumour on CT body scan or known malignancy except non-melanoma skin cancer, completely resected or prostate cancer (with Prostate Specific Antigen of less than or equal to 0.1 ng/ml) within the past three years. * Patients have contraindications to contrast-enhanced MRI scanning (e.g. claustrophobia, gadolinium allergy).