Onkológia 5/2013
Stereotactic radiotherapy lung cancer
Extracranial stereotactic radiotherapy, generally known as SBRT is an emerging treatment that is appropriate therapeutic option for patients with early non-small cell lung cancer (NSCLC) who are unable or unwilling to undergo surgery. Stereotactic radiotherapy is highly conformal radiotherapy hypofractionated technique. It uses advances in technology to deliver high doses of radiation with high conformity radiation in a small number of doses. Is used much higher dose per fraction than in the conventional radiotherapy. Apply biologically effective dose (BED) greater than 100 Gy. These characteristics make SBRT much more effective than conventional radiotherapy in the treatment of tumor tissue, but are also potentially much more damaging to normal tissue. High accuracy is therefore necessary. Multiple irradiation beams are directed to the target volume in different planes. In the place of intersection is reached required high dose while saving the surrounding healthy tissue. This method with contemporary technical equipment allows you to accurately locate and calculate the dose in the target volume site. By delivering high doses of radiation in a small number of fractions to a small target volume site while saving surrounding tissues is reached maximum lethal effect. For SBRT lung lesions are mostly used devices based on linear accelerator. Normally it is a linear accelerator, which must be equipped with multileaf ev. micromultileaf collimator device and IGRT (image guided radiotherapy). Another option is a robotic accelerator (CyberKnife), which accurate focus on the use of gold grains introduced invasive way to close the bearing. Compared to conventional radiotherapy SBRT provides considerably higher radiation dose in the tumor area and thereby occurs to increase of the local control, which is more than 80%. Since SBRT has a high dose gradient in the periphery, it is simultaneously protects healthy tissue. Toxicity is usually not serious, and depends on the total dose, fractionation, target volume size, radiosensitivity organs of risk. SBRT is generally well tolerated even in patients older and comorbid. Lower overall survival relates mainly with the associated diseases.
Keywords: stereotactic radiotherapy, lung tumors, IGRT – image guided radiotherapy, target volumes, toxicity.
