This is a pilot study of radiotherapy using Hypofractionated image - guided helical tomotherapy after hyperbaric oxygen HBO therapy for treatment of recurrent malignant High-grade gliomas. HBO therapy will be perform in conjunction with each RT session.

The treatment scheme is:

Hyperbaric oxygenation therapy (the maximum period of time from completion of decompression to RT is 60 min) followed by tomotherapy (3-5 consecutive sessions- one fraction per day , 5 Gy / die ).

The trial will enroll 24 patients in 24 months with a follow-up period of 1 year.

This is a pilot study to evaluate the efficacy of hypofractionated image- guided helical tomotherapy after hyperbaric oxygen therapy (HBO) for treatment of recurrent malignant high - grade gliomas The primary objective of this study is to evaluate the disease control rate (DCR) of treated patients.

The secondary Objectives are:

• Safety assessment (acute and late toxicity).
• Overall Survival (OS),
• Progression Free Survival (PFS).
• Evaluation of predictive score of disease, radionecrosis and pseudoprogression using perfusion DSC and DCE MRI

Patients will receive fractionated stereotactic radiotherapy using tomotherapy combined with hyperbaric oxygen (HBO) therapy.

Hyperbaric oxygenation therapy (the maximum period of time from completion of decompression to RT is 60 min) followed by tomotherapy (3-5 consecutive sessions- one fraction per day, 5 Gy / die).

The overall duration of treatment will be max 5 days.

Inclusion Criteria:

1. Male or Female, aged >18 years.
2. Karnofsky Performance Scale (KPS)> 60
3. Imaging confirmation of first tumor progression o regrowth as defined by Response Assessment in Neuro-Oncology Criteria (RANO) criteria at least 12 weeks after completion of radiotherapy, unless the recurrence is outside the radiation field or has been histologically documented
4. Recurrence after adjuvant treatment( surgery followed by radiotherapy and chemotherapy) in patients who could receive further therapeutic interventions
5. No more than one prior line of chemotherapy (one line of chemotherapy after concurrent and adjuvant Temozolomide (TMZ) - based chemotherapy or procarbazine/lomustine/vincristine (PCV) - Radiotherapy (RT)
6. Patients who have undergone recent surgery for recurrent o progressive high grade gliomas are eligible provided that : surgery must have confirmed the recurrence ; a minimum of 28 days must have elapsed from the days of surgery to study . For core or needle biopsy a minimum of 7 days must have elapsed prior to study .
7. If female and of child bearing potential , have a negative result on a pregnancy test performed a maximum of 7 days before initiation .
8. Female participants of child bearing potential and male participants whose partner is of child bearing potential must be willing to ensure that they or their partner use effective contraception during the study and for 4 months thereafter
9. Have adequate bone marrow function , liver function , and renal function , as measured by following laboratory assessments conducted within 7 days prior to the initiation of study treatment .
10. Hemoglobin >9.0 g/dl
11. Absolute neutrophil count (ANC) >1500/mm3 without transfusions or granulocyte colony stimulating factor and other hematopoietic growth factors
12. Platelet count ≥90,000/μl
13. White Blood Cell (WBC) >3.0 x 109/L
14. Total bilirubin <1.5 times the upper limit of normal
15. Serum creatinine <1.5 x upper limit of normal
16. Participant is willing and able to give informed consent for participation in the study.

Exclusion Criteria:

1. Radiotherapy within 12 weeks prior to the diagnosis of progression, if the lesion is in the radiation field.
2. Patients with cardiopulmonary diseases (heart failure, bolus emphysema, pneumothorax, chronic obstructive pulmonary disease (COPD) with hypercapnia sinusitis )
3. Closed angle-glaucoma with pressure ocular superior to 24 mmHg