The gamma knife and cyber knife systems in Moscow are represented in several public and private medical centers. The gamma and cyber knife technologies were widely advertised and indeed showed impressive results during their introduction. However, now most major medical centers in Europe and the United States are installing the latest EDGE system, which, according to experts, has unlimited indications for use.
The gamma knife is used in the treatment of intracranial (located in the cranial cavity) neoplasms. The radiation source in this device is radioactive cobalt. When using a gamma knife, the position of the source, collimators, and isocenter of the installation is fixed in space. The only object capable of changing its position is the couch on which the patient lies, whose head is invasively fixed with bolts of a stereotactic frame.
The CyberKnife system allows irradiation of targets located not only intracranially, but also extracranially (outside the cranial cavity). A treatment session usually takes from 30 minutes to 2 hours. Radiation exposure on the cyber knife is carried out by spherical fields up to 60 mm in diameter, which makes it difficult to plan radiation therapy for irregularly shaped and/or large tumors. During treatment, the focus position is monitored by taking X-rays several times during one session.
EDGE, the latest generation linear accelerator (LU) manufactured by Varian, is the most versatile and advanced system for radiation therapy today. LU EDGE surpasses the gamma knife and cyber knife systems in accuracy and speed of dose reduction. This device allows for both radiosurgical treatment ("surgery without a knife") and "classical" radiation therapy
for oncological diseases.
The possibility of radiation therapy in one session (radiosurgery) allows you to help patients even in cases that were previously considered hopeless. There are almost no restrictions in the use of this technology. The tumor is removed in one session. Hospitalization is not required, and there are practically no radiation complications with this type of treatment.
The Cone Beam CT (CBCT) imaging system installed on the EDGE device allows you to obtain a three-dimensional image of the patient's anatomical structures, just as when using CT directly during treatment. The obtained images are compared with the obtained images during topometry, and, if necessary, the patient's position is adjusted. The device's software allows you to automatically determine the amount of necessary styling correction. This significantly improves the quality of the patient's placement and the accuracy of applying the dose to the tumor.
The EDGE system has state–of-the-art functions, such as Respiratory Gating, a respiratory monitoring function,
HyperArc – treatment of multiple metastases in one session iCBCT is an iterative CBCT with improved image quality. These technologies can be used in the treatment of all types of cancer, including complex cancers of the lung, breast, prostate, brain, rectum, head, neck and other tumors, including in children.
Before treatment, the patient undergoes CT topometry, during which a laser navigation system is applied to the patient's skin or a stacking device that allows the patient to reproduce the patient's styling during treatment.
In the future, the resulting CT scan is used first by doctors to outline the tumor and the nearest organs at risk, and then by medical physicists to plan radiation therapy and set the accelerator motion program, which is selected individually for each patient.
Radiation therapy planning is performed on the Eclipse planning system from Varian Medical Systems, USA. This system allows the doctor to automatically combine various diagnostic images (CT, MRI, PET-CT, angiography), as well as perform automatic or manual contouring of critical organs and the lesion itself. The medical physicist selects the optimal dosage from the point of view of efficiency and safety, calculates dose loads and adjusts various beam parameters, optimizing the treatment plan, as well as verifies the plan.
The duration of therapy on the EDGE device is only 10-20 minutes. During therapy, the patient is placed on the treatment table in the "back" or "stomach" position, depending on the location of the tumor. Taking into account the localization of the neoplasm, various immobilizing devices are used, such as a thermoplastic mask, a vacuum mattress, which ensure perfect reproducibility of the installation due to competent fixation of the patient during the entire course of treatment.
The advantage of the EDGE laser over the gamma and cyber knives during radiosurgery is due to the possibility of irradiating larger tumors. Unlike the gamma knife, which is used only for radiosurgery of brain tumors, the EDGE system allows for high-precision radiation therapy of tumors of any location and shape with an accuracy of hitting the target to fractions of a millimeter.
There are currently only a few such devices in the world. Thanks to the opening of the EMC Institute of Oncology in Moscow, high-tech and effective treatment of malignant tumors using the EDGE linear accelerator has become a reality.
Comparison of EDGE, Gamma, and Cyber knife characteristics
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EDGE
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Gamma knife
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Cyber knife
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Continuous breathing tracking function
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Yes
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No
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Not always
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It can be used in the treatment of tumors of various sizes.
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Yes
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No
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No
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The main directions of treatment (localization)
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Tumors of any localization
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The brain
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Brain, spine, lungs
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Duration of treatment
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10-20 min
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30 min – 3 hours
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40 min – 2 hours
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