Gamma knife radiosurgery

In the name of God

by:E. GhasemloyZ. Mansouri

Z.DoorandishE.Maroofzade

Shahid beheshti university of medical science

Gamma Knife radiosurgery

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Gamma knife today the first Gamma Knife in 1968

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Gamma knife statistics

• 120 gamma knife worldwide• Over 20000 patients treated annually

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introduction

• Gamma Knife radiosurgery, also called stereotactic radiosurgery.

• Even though it is called surgery; a Gamma Knife procedure does not involve actual surgery, nor is the Gamma Knife really a knife at all.

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Technical overview

• There are five current versions of the Leksell Gamma Knife :

• U• B• C• 4C• perfexion

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• . Each system consists of six components:• the radiation unit• the beam-focusing technology • the patient couch• an electric bed system• the control console• the planning computer system.

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Device details

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prefextionFigure : Diagrams of the PERFEXION Gamma Knife radiation unit and collimator system. A) Cross section of the Leksell Gamma Knife PERFEXION radiation unit. B) Each sector holds 24 60Co sources and can be moved independently on other sectors to the desired position to define collimator size or block groups of beams. C) Sector position in 4 mm collimator. D) Sector position in 8 mm collimator. E) Sector position in 16 mm collimator.

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• 201 cobalt gamma ray beam sources are arrayed in a hemisphere and aimed through a collimator to a common focal point.

• The patient’s head is positioned within the Gamma Knife so that the tumor is in the focal point of the gamma rays.

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Gk treatment clinical process

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Advantages

• Precision• Safety• Effectiveness• Technologically advanced• …

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The Leksell Gamma Knife Perfexion offers a non-invasive, two to four hour procedure that often allows the patient to leave the center the same day.

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What disorders can the Gamma Knife treat?

• Malignant tumors • Arteriovenous malformations (AVM)• Acoustic Neuroma• Parkinson's disease• Familiar tremor• Trigeminal neuralgia

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preparing

• Frame fitting• Imaging• Dose planning

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How is Gamma Knife Surgery performed?

• Step 1: A stereotactic head frame is attached to the head with local anesthesia

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• Step 2: The head is imaged using a MRI or CT scanner while the patient wears the stereotactic frame.

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Step 3: A treatment plan is developed using the images. Key point: very accurate delivery possible.

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Step 4: The patient lies on the treatment table of the Gamma Knife while the frame is affixed to the appropriate collimator.

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STEP 5: THE DOOR TO THE TREATMENT UNIT OPENS. THE PATIENT IS ADVANCED INTO THE SHIELDED TREATMENT VAULT. THE AREA WHERE ALL OF THE BEAMS INTERSECT IS TREATED WITH A HIGH DOSE OF RADIATION.

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Control room

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Treatment Planning

• Through an iterative approach we determine:– the number of shots– the shot sizes– the shot locations– the shot weights

• The quality of the plan is dependent upon the patience and experience of the user

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target

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1 shot

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2 shots

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3 shots

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4 shots

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5 shots

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What are the risks?

• Swelling of the brain• Headache• Nausea• Numbness

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…The risks

• Hair loss near treated area (generally temporary)

• Seizures• Weakness• Loss of balance• Vision problems

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