Table 1: Distribution of Variables (n=130).

Continuous variables are presented as median (interquartile range) and categorical variables are presented as count (percentage).

Variable		Value
Patient-level
Biometric	Sex
	Male	73 (56%)
	Female	57 (44%)
	Race
	White	120 (92%)
	Other	10 (8%)
Comorbidities	Hypertension
	Yes	37 (28%)
	No	93 (72%)
	Diabetes
	Yes	9 (7%)
	No	121 (93%)
Brain characteristics	Whole ventricular volume (cc)	27.10 (20.36-37.10)
Tumor-level
Tumor characteristics	Type
	H&N	60 (46%)
	CNS	65 (50%)
	BOS	5 (6%)
	Location
	Extracranial	60 (46%)
	Intracranial	70 (54%)
	Bilateral radiation target
	Yes	33 (25%)
	No	97 (75%)
	Clinical target volume (cc)	118.16 (60.06-266.49)
Tumor location variables	Cerebral lobe at risk
	Frontal	54 (42%)
	Temporal	54 (42%)
	Other	22 (17%)
	Distance from maximum dose to ventricles (mm)	62 (37-95)
	Maximum dose in white matter
	Yes	13 (10%)
	No	117 (90%)
Treatment-level
Other therapies	Prior surgery
	Gross total resection	36 (28%)
	Near total resection	18 (14%)
	Subtotal resection	38 (29%)
	None	38 (29%)
	Concurrent chemotherapy
	Yes	61 (47%)
	No	69 (53%)
Radiotherapy variables	Radiotherapy indication
	Definitive	77 (59%)
	Adjuvant	53 (41%)
	Mean brain dose (Gy)	5.4 (3.3-10.6)
	Maximum brain dose (Gy)	67.1 (63.5-72.1)
Radiation Necrosis
Overall		50 (38%)
Central Nervous System		19 out of 65
	Glioma	14 out of 42
	Meningioma	5 out of 19
	Ependymomas	0 out of 1
	Hemangiopericytomas	0 out of 2
	Other	0 out of 1
Head and Neck		30 out of 60
	Nasopharyngeal carcinomas	21 out of 47
	Salivary gland tumors	6 out of 10
	Other 3 out of 3
Base of Skull		1 out of 5
	Chordomas	0 out of 5
	Chondrosarcomas	1 out of 2
	Other	0 out of 1