New Era of Radiosurgery and Compare with Modern Radiation Oncology
|作者: 陳光耀 (03-22 20:07)
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Clinical radiosurgery was born forty years ago when the first intracranial lesion was treated by gammaknife in 1967 by Dr. Lars Leksell with a metallic flame fixed to skull for localization and focal irradiation with gamma rays of 60Co. Intracranial radiosurgery was further developed in 1980s with supravoltage X-rays of medical linear accelerator by multiple non-coplanar focal irradiation and flame fixation. Advancement of computer technology and imaging systems such as CT scan, MR, angiograms, PET and CT/ PET further improve the 3D reconstructed images of target and surrounding tissues allowing optimization of treatment planning. Thousands of cases had been treated and demonstrated that single fraction large dose irradiation is effective for intracranial benign and malignant lesions.
Radiosurgery enters a new era in 2001 when 6 MV X-rays are produced by a mini-linear accelerator which is manipulated precisely by robotic system called CyberKnife. It does not require flame fixation yet is able to treat lesions of any part of the body. If the tumor is too large or next to the sensitive tissues, the lesion can be treated safely by 2-5 fractions.
CT scan is the bases for patient positioning and treatment planning of CyberKnife. A pairs of ceiling mounted diagnostic X-ray facilities 45°diagonally project toward the treatment target can detect 3D linear and 3D rotating deviations of the skeletal or fiducial markers instantly allowing accurate repositioning of the patient by 6D adjustment of the couch automatically. Overlay the real time positioning images with the same 45°reconstructed CT images during the process of irradiation for the first time in medical history that the treatment beams can frequently adjust for patient movement. Multiple X-ray exposures of target markers in a respiratory cycle renders CyberKnife to perform 4D imaging , with 4D planning it can deliver 4D irradiation for moving tumors in natural respiration, therefore, primary and metastatic tumors of the lung, liver, pancreas, and prostate are common tumors to be treated by CyberKnife.
There are a number of modern radiation oncology machines available, some of them may be used for radiosurgery. However, CyberKnife is the only facility truly dedicates to radiosurgery with real time image-guided automatic patient positioning and image-guided readjust beam direction frequently to compensate patient movement during irradiation, the total clinical accuracy is submillimeter. CyberKnife is also the only facility to treat moving tumors in natural respiration with high precision. CyberKnife can treat intracranial and extracranial lesions including benign and malignant tumors, arteriovenous malformation and trigeminal neuralgia in 1 to 5 fractions of 6 MV X-rays. CyberKnife is the most least invasive and non-invasive surgery, it opens a new era for radiosurgery.