It's a form of brain surgery without any incisions. Patients with brain tumors, both benign and malignant; vascular formations; and trigeminal neuralgia, a chronic condition that affects the nerve that carries sensation from your face to your brain often are candidates for a noninvasive procedure called gamma knife stereotactic radiosurgery. It pinpoints high doses of radiation at the tumor with little impact to surrounding healthy tissue. https://mayocl.in/36bS3hk | Mayo Clinic

Proving the Gamma probability density function (pdf) is indeed a valid pdf