The following four clinical cases demonstrate how CyberKnife's superior conformality and accuracy enable treatment of lesions that previously were either untreatable or difficult to treat by other radiosurgery systems. These lesions include ones adjacent to radiosensitive structures, complex-shaped lesions, previously irradiated lesions precluding further external beam irradiation, recurrent surgical lesions, lesions requiring difficult surgical approaches, and patients who are too frail or refuse surgery.

Benign L1-L2 Schwannoma:
This patient had a complex medical history and presented with persistent, worsening groin pain. The pain did not respond to oral medications, and nerve blocks provided only transient relief. CyberKnife treatment of 20 Gy to the 87% line in 5 fractions was prescribed. CyberKnife delivered excellent homogeneity and tumor coverage of 98%. Furthermore, the patient experienced full resolution of groin pain within one week of treatment completion!

Optic Nerve Meningioma:
Vision preservation was a primary clinical objective for this patient. The patient had a history of progressive loss of visual acuity and peripheral vision. Due to the high risk of recurrence, the neurosurgeon referred the patient for adjunctive radiosurgery treatment in addition to surgical resection. Since staged/fractionated radiosurgery has demonstrated improved vision preservation of perioptic lesions, CyberKnife was chosen as the treatment modality. 25 Gy to the 75% line over 5 fractions with CyberKnife was prescribed. CyberKnife delivered a highly conformal dose distribution with a conformality index of 1.30 and tumor coverage of 95.7%.

Pancreatic Adenocarcinoma:
Like many pancreatic cancer patients, this patient's pancreatic lesion was unresectable. He experienced epigastric pain, daytime nausea, and loss of appetite. CyberKnife treatment was chosen because CyberKnife has demonstrated rapid palliation for patients with unresectable pancreatic cancer. CyberKnife treatment of 20 Gy to the 86% line over 2 fractions was prescribed. CyberKnife delivered an extremely homogenous and conformal dose, with conformality index of 1.75 and excellent coverage of 97%.

Prostate:
Patient originally received 45 Gy to the prostate and seminal vesicles from external beam radiation therapy. This patient was referred to CyberKnife for a boost. Sparing the urethra was paramount. 20 Gy to the 84% line over 2 fractions was prescribed. CyberKnife delivered an impressive conformality of 1.25 and tumor coverage of 96.