Gamma knife

Radiation therapy is the treatment of choice for most patients with brain metastases. Most patients receive whole-brain radiation because the majority of brain metastases are multifocal. Another method known as stereotactic radiosurgery provides intense focal radiation, typically using a linear accelerator or gamma knife, in patients who cannot tolerate surgery or have lesions that are surgically inaccessible (e.g., in the brain stem). 

Gamma knife A device that uses multiple converging beams of gamma radiation from cobalt-60 to highly focus radiation on small tumors within the brain. 

Psychosurgery. Nnmerous brain procednres, which can now be performed in a mnch less invasive manner via techniqnes snch as the gamma knife, can be beneficial for patients who are resistant to all other forms of treatment. 

From a technical point of view, intensity-modulated radiation therapy (IMRT) optimizes several parameters selection of multiple beams and, for each beam, optimization of dose, dose rate, size and shape, etc. Tomotherapy optimizes the dose distribution by IMRT in successive sections with immediate verification gamma knife, cyberknife, and radiosurgery concentrate high radiation doses in well-defined small volumes. 

Powerful irradiation techniques are now available or under development for photons intensity-modulated radiation therapy (IMRT), tomotherapy, gamma knife, cyberknife, radiosurgery, etc. These techniques make it possible to irradiate any volume of any complex shape with minimum irradiation of critical normal structures. 

When making this comparison, one must remain aware of the modern developments in photon therapy such as conformal therapy (3DCRT), IMRT, tomotherapy, gamma knife, stereotactic x-ray techniques, iodine-125 (and palladium-103) seeds and plaques, etc. 

Lars Leksell Center for Gamma Knife Surgery. http //www.healthsystem.virginia. edu/internet/gammaknife/overview.cfm, accessed October 2, 2008. 

Chernov M, Hayashi M, Izawa M, Ochiai T, Usukura M, Abe K, Orio Y, Muragaki Y, Kubo O, Hori T, Takakura K (2005) Differenda-dori of die radiadon-induced necrosis and tumor recurrence after gamma knife radiosurgery for brain metastases Importance of muld-voxel proton MRS. Minim Invasive Neurosurg 48 228—234. 

Gan7, J.C. Gamma Knife Radiosurgery and its Possible Relationship to malignancy a Review. J Neurosurg. 2002 Dec 97(5 Suppl) 644-52. 

Cobalt-60. A typical teletherapy Cobalt-60 source is a cylinder of diameter ranging from 1.0 to 2.0 cm and is positioned in the cobalt unit with its circular end facing the patient. The sourcehead houses the source. The Gamma Knife is another type of Cobalt-60 that contains hundreds of sources in the collimator helmet. Each radiation source is composed of Cobalt-60 pellets that are contained in double stainless steel capsules with welded closures. 

Gamma knife irradiation has not been used in combination with PDT. 

Radioisotope thermoelectric generators (RTGs) Irradiators Teletherapy sources Fixed, multi-beam teletherapy (gamma knife) sources AID > 1000... 

Kim MS, Pyo SY, Jeong YG, Lee SI, Jung YT, Sim JH (2005) Gamma knife surgery for intracranial cavernous hemangioma. J Neurosurg 102(Suppl) 102-106... 

Liscak R, Vladyka V, Simonova G, Vymazal J, Novotny J Jr (2005) Gamma knife surgery of brain cavernous hemangiomas. J Neurosurg 102(Suppl) 207-213... 

Aoki Y, Nakasawa K, Tago M et al. (1996) Clinical evaluation of Gamma knife radiosurgery for intracranial arteriovenous malformations. Radiat Med 14 265-268 Aoki S, Sasaki Y, Machida T et al. (1998) 3D-CT angiography of cerebral arteriovenous malformations. Radiat Med 16 263-271... 

Karlsson B, Lax I, Soderman M et al. (1996) Prediction of results following Gamma-Knife surgery for brain stem and other centrally located arterio-venous malformations relation to natural course. Stereotact Funct Neurosurg 66(Suppl l) 260-268... 

Kwon Y, Ryong S, Hoon J et al. (2000) Analysis of the causes of treatment failure in gamma knife radiosurgery for intracranial arteriovenous malformations. J Neurosurg 93 104-106... 

Soderman M, Edner G, Ericson K et al (2006) Gamma knife radiosurgery for dural arteriovenous shunts 25 years of experience. J Neurosurg 10 867-875... 

Calculating the Dosimetry Distribution of Leksell Gamma Knife in Phantom Zubal... 

Keywords— Leksell Gamma Knife, Gamma Plan, dose distribution, Zubal head phantom, MCNP. 

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