• Tumour Diagnosis: Newly diagnosed non-disseminated treatment naïve DIPG by classic clinical AND radiographic finding.

• Age: Patient must be 3 to 18 years of age at the time of diagnosis.

• Performance Score: KPS \> 12 y/o \>/= 50 or LPS for \< 12y \>/= 50 assessed at enrollment.

• Participants must have normal organ and marrow function as defined below within two weeks prior to enrollment:

‣ Hematological: Absolute neutrophil count \> 1,000/mcL, Platelets\> 100,000/mcL (transfusion independent), HB \> 8gm/dL (can be transfused)

⁃ Hepatic: Total bilirubin \< 1.5 times the upper limit of normal; alanine aminotransferase \[SGPT (ALT)\] and aspartate aminotransferase \[SGOT (AST)\] \< 5 times the institutional upper limit of normal.

⁃ Renal: Serum creatinine which is less than 1.5x the upper limit of institutional normal for age or Glomerular Filtration Rate (GFR) \> 70 ml/min/1.73m2.; The absence of clinically significant proteinuria as defined by a screening early morning urine (first sample) dipstick urinalysis of \< 2.

⁃ Normal coagulation profile

• Post-Biopsy patients allowed, but should not have evidence of haemorrhage greater than 0.5cm intracranially and should satisfy this criterion within two to four weeks of biopsy to start treatment in Arm 1 if designated as per perfusion study along with satisfying other criteria as applicable. For arm 2, there will be no restriction other than the usual criteria.

• No contra-indication for GA for MRI

• Would not need GA for RT in the hypofractionated subgroup (due to logistics).

• Ability to understand and the willingness to sign a written informed consent document by the parent or guardian and assent by the child as applicable and as per institutional policy.