Hypofractionated Proton Therapy for Benign Intracranial Brain Tumors, the HiPPI Study

Inclusion Criteria: * Pathologically or radiographically diagnosed benign intracranial or nerve sheath tumor, including meningiomas, pituitary adenomas, schwannomas. World Health Organization (WHO) grade 2-3 meningiomas are also allowed * Recommended to receive proton or photon fractionated radiation therapy * Signed informed consent Exclusion Criteria: * Pregnant females are excluded. Female of child-bearing potential (FCBP) must have a negative serum or urine pregnancy test prior to starting therapy. FCBP must agree to use adequate contraception (at least one highly effective method and one additional method of birth control at the same time or complete abstinence) prior to study entry, for the duration of study. Should a woman become pregnant or suspect she is pregnant while she is participating in this study, she should inform her treating physician immediately. * A female of childbearing potential (FCBP) is a sexually mature woman who: has not undergone a hysterectomy or bilateral oophorectomy; or has not been naturally postmenopausal for at least 12 consecutive months (if age \>= 55 years); if the female subject is \< 55 years and she has been naturally postmenopausal for \>= 1 year her reproductive status has to be verified by additional laboratory (lab) tests (\< 20 estradiol OR estradiol \< 40 with follicle stimulating hormone \[FSH\] \> 40 in women not on estrogen replacement therapy) * Prior radiation therapy that would overlap with current target volume * Inability to undergo magnetic resonance imaging (MRI)