1. Introduction

    Interventional radiology (IR) involves minimally invasive procedures and therapies performed by radiologists, especially in patients at high medical risk. Major IR therapies include angiography, embolization of blood vessels such as arteriovenous malformations or for epistaxis, delivery of chemical or physical vascular occlusive devices, removal of thrombi, ablation of aneurysms, and angioplasty of blood vessels with stent placement.

    Gamma radiation is used for radiotherapy and radiosurgery. The gamma radiation is introduced to the patient by the use of either a Gamma Knife or a CyberKnife. The CyberKnife therapy delivers a sequence of many hundreds of gamma beams to the cancerous tumor from many different directions. Gamma Knife therapy delivers gamma radiation to the cancerous tumor simultaneously in a single dose.

    Interventional neuroradiology (INR) is used for diagnosis and treatment of central nervous system (CNS) diseases endovascularly to deliver therapeutic medications or devices. Digital subtraction angiography first uses an original angiograph of the blood vessels to be studied. Then a contrast medium is injected into the same blood vessels, and opaque structures such as bone and tissues can be digitally subtracted or removed from the angiographic image, leaving a clear picture of the blood vessels.

    Improvements in vascular access techniques, new thin and flexible catheters and guidewires, and the development of innovative coils and therapeutic medications have made new treatments possible. Conditions that once required extensive surgery with accompanying patient morbidity and mortality can now be performed less invasively. Some major procedures performed with INR are mechanical or chemical removal of emboli or thrombi that cause stroke, the physical occlusion of malformed vascular structures such as an arteriovenous malformations with chemicals or flow-directed balloons, dilation of stenotic blood vessels, and embolization (blocking blood flow) of cerebrovascular aneurysms using catheter-deployed coils.