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Radiosurgery, Stereotactic Radiotherapy
Like a baton to a symphony conductor, or a paintbrush to an artist, or a pen to a writer, a scalpel to a surgeon is an extension of his or her talent and skills. It is a conduit to an infinite number of promising medical possibilities. And the rewards are even more remarkable than glorious music, a work of art or a bestseller.
A surgeon's masterpiece can help save a life.
But it is only through a combination of the finest scalpels and technology in the hands of the most highly trained and experienced physicians that extraordinary outcomes can be achieved. It takes an instrument with exceptional capabilities and a physician with remarkable talent to pre-cisely and accurately maneuver into and around delicate structures to eliminate disease.
At the Allegheny Cancer Center, we have both.
Our renowned neurosurgeons and radiation oncologists are trained and experienced to utilize an innovative knife that attains extraordinary exactness all without making an incision. The XKnife is the knife that doesn't cut, yet effectively eliminates benign and malignant tumors of the brain, head, neck, throat and upper lung, as well as treats a variety of neurological disorders. As a major evolution in the practice of stereotactic radiosurgery and radiotherapy the XKnife utilizes sophisticated computer treatment- planning software and a unique radiation delivery system to dispense pinpoint doses of high-energy radiation to tumors without harming surrounding structures of the brain.
Unlike its predecessor, the Gamma Knife --which is limited to delivering high-dose radiation to only brain lesions -- the XKnife administers well-defined radiation beams that can conform in both shape and volume to the precise dimensions of a tumor. The XKnife can also effectively deliver fractionated doses of radiation over several sessions in order to treat very complex neurological lesions with minimal risk to the patient. In addition, the technology has the ability to expand its capabilities to regions of the chest and abdomen in the near future.
At the Allegheny Cancer Center, the collaborative effort among our radiation oncologists, neurosurgeons, physicists, dosimetrists and nurses -- as well as physicians from a variety of other disciplines within Allegheny General Hospital -- presents patients with a comprehensive approach to treatment, providing the best chance for the most successful outcomes. We work closely with referring physicians to ensure they are active partners in each stage of their patients' treatment plans -- from diagnosis to post-treatment, when we return the patient to the referring physician's care.
It is with this elaborate combination of the finest technology, highly skilled physicians and multidisciplinary approach that the Allegheny Cancer Center can confidently present the highest quality stereotactic care available.
Stereotactic Radiosurgery
The practice of radiosurgery has evolved tremendously since Professor Lars Leskell of Sweden first conceived the idea in 1951. After experimenting with various forms of radiation energy, he concluded that highly focused cobalt energy could be used to destroy lesions and other types of neoplasms. However, the cost of such a unit -- known as the Gamma Knife --was a major limiting factor in its widespread use. Since then, researchers have been able to build upon the foundation established by the Gamma Knife to develop an equally effective and more refined technology -- the XKnife.
Radiosurgery at the Allegheny Cancer Center involves a one-day outpatient procedure that delivers a single, focused high dose of radiation to a tumor. The treatment planning begins when our clinical team uses the XKnife system's sophisticated computer software to fuse a com-puted tomography (CT) scan with a magnetic resonance image (MRI). The incorporation of the two scans provides a three-dimensional anatomical reconstruction of a brain lesion and the surrounding brain anatomy.
 The neurosurgeon, radiation oncologist and physicist collaborate to determine radiation doses, target volumes and beam arrangements. In some cases, the clinical team is able to utilize intensity-modulated radiation therapy (IMRT) with a mini-multileaf collimator to shape the beams with millimeter accuracy It also allows us to deliver more than 100 mini-beams to the treatment area, resulting in maximum radiation coverage of irregularly shaped and otherwise difficult-to-treat tumors.
A virtual treatment simulation is then performed, which traces the path of each individual radiation beam through the tumor area. While a head ring is affixed to the patient's head, a dedicated linear accelerator with a multileaf collimator rotates around the patient and administers highly conformed, separately controlled radiation beams to the exact dimensions of the tumor. The patient's planning and treatment with the XKnife are completed in one day, and the actual dose administration takes approximately 30 minutes.
This precise dosing and targeting system allows us to irradiate not only round and defined tumors but also tumors of irregular shapes and sizes. The procedure has proven to successfully control brain metastases, as well as primary brain tumors, such as meningiomas, and obliterate arteriovenous malformations with minimal or lesser morbidity and mortality In addition, the procedure is minimally invasive, and the patient generally experiences few side effects.
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We employ the most sophisticated computer technology to determine precise target volumes and beam arrangements for treating benign and malignant tumors of the brain, head, neck, throat and upper lung, and for treating an array of neurological disorders.
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Allegheny General's radiation oncologists and neurosurgeons utilize image fusion to obtain a comprehensive representation of the tumor area for treat-ment planning and follow-up care. The sophisticated software aligns CT scans and MRIs volumetrically, allowing clinicians to have both the spatial accuracy of the CT scan and the superior tissue definition of the MRI.
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Fractionated Stereotactic Radiotherapy
Radiotherapy entails delivering lower levels of focused radiation over a series of treatment sessions, minimizing radiation exposure to surrounding normal brain structures. This fractionated procedure is an exceptional therapy for cases where the tumor is adjacent to critical structures, such as the brain stem and eyes or optical nerves.
The XKnife helps minimize neurosurgeons greatest challenge of the thin margin of error that exists when operating within the brain. The multiple treatments or fractions help physicians prevent potential damage to sensitive structures of the brain during the course of treatment, preserving, for instance, a person's vision, speech or motor abilities.
A non-invasive procedure, fractionated stereotactic radiotherapy does not require the direct attachment of a head ring as with radiosurgery, but instead, a unique relocatable head frame is used. With this procedure, positioning and stabilization of the patient's head is based on the patient's bite pattern, ensuring precision in delivering radiation over several days of separate sessions. As with radiosurgery, radiotherapy utilizes the same sophisticated planning treatment soft-ware and linear accelerator technology and is also an outpatient procedure that yields minimal side effects.
XKnife's Clinical Indications
At the Allegheny Cancer Center, the departments of neurosurgery and radiation oncology collaborate closely to ensure that patients undergoing either stereotactic radiosurgery or radiotherapy obtain the best possible outcomes. Superior results have been achieved by utilizing the XKnife for the following clinical indications:
- Arteriovenous malformations (AVMs)
- Brain metastases
- Gliomas
- Acoustic neuromas
- Cavernous angiomas
- Intractable seizures
- Recurrent brain tumors
- Pituitary adenomas
- Meningiomas
- Craniopharyngiomas
- Low-grade astrocytomas
- Oligodendrogliomas
- Certain functional brain disorders
- Movement and spasticity disorders
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Using a mini-multileaf collimator to shape more than 100 radiation beams with millimeter accuracy we are able to maximally cover even irregularly shaped and otherwise difficult-to-treat tumors.
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With stereotactic radiosurgery, patients are ensured precise radiation treatment through the use of a head ring, which serves as an effective fixation device.
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