The Effect of Radiotherapy on Cancerous Tumors (Brain Tumors) Using the Linear Accelerator Device

Abstract

MRI findings after stereotaxic radiosurgery using the Gamma Knife. To evaluate the temporal evolution and appearance of a radiosurgical lesion at magnetic resonance (MR) imaging and the clinical response in patients undergoing stereotactic radiosurgical pallidotomy or thalamotomy with the gamma knife. A wide variety of intracranial diseases are treated with the Gamma Knife; These include movement disorders, trigeminal neuralgia, tumors, and arteriovenous malformations. MRI is invaluable in studying treatment outcomes, because pathological data are limited on this minimally invasive technique. Examinations may be performed to check lesion status, determine the effects of the radiation dose on target tissues, and detect complications related to treatment.

CONCLUSION: Findings in this pilot study suggest that radiosurgical thalamotomy is a promising treatment for medically refractory tremor. Three- month follow-up MR studies show a ring-enhancing lesion surrounded by a variable amount of vasogenic edema. Visualization of the radiosurgical lesion and the clinical response are delayed compared to that with radio-frequency procedures. Successful treatment with the gamma knife may result in growth arrest, regression, or obliteration of the neoplastic lesion. Growth arrest has been reported in approximately 90% of benign neoplasms at the skull base and 85% of solitary metastases .Tumor regression is uncommonly seen earlier than 3 months posttreatment and may take years to fully evolve. For example, the median time for regression of vestibular schwannomas is approximately 1 year, with a range of 3-33 months [5, 7] Tumor regression occurs more rapidly in malignant neoplasms .Fibroblasts and myofibroblasts aid in tumor retraction.