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Cyberknife vs. Gamma Knife Radiation Treatment

RI Hospital: Neurosurgery Midlevel Meeting 21 June 2011

Presenter: Michaela McGuire

Cyberknife • LOCATION OF TREATMENT • no restrictions • can even treat areas that move with respiration • malignant or benign tumors • ACCURACY • within < 0.5 mm • STABILIZATION • frameless • position of anatomy determined by CT and real-time x-ray imaging • great for treating very young patients, or those with fragile skulls due to prior surgeries • RETREATING • possible if necessary up to five times with no repeat preparations • allows a few days for surrounding, normal, healthy tissue to heal before next round of radiation. Advantages include preservation of and less damage to adjacent tissue. • COLLIMATORS • fixed tungsten collimators (a.k.a. “cones”) • circular radiation fields varying sizes (5, 7.5, 10, 12.5, 15, 20, 25, 30, 35, 40, 50, & 60 mm) – 12 sizes in total • wide range of sizes mean no limitation to lesion size • single high-energy photon beam attached to robot • HOW IT WORKS • beam moved to the most effective angles/in relation to any movement according to real-time x-rays. • beam is moved by robot arm • in areas where bone anatomy cannot serve as the primary landmark, fiducial markers (gold seeds or metal screws implanted around a soft tissue as landmarks) are put in place by interventional radiologist or neurosurgeon. • if the lesion in question is a soft tissue tumor, fiducial markers must go in place a few days before planning images can be acquired

Gamma Knife • LOCATION OF TREATMENT • restricted to the brain • cannot treat regions of the body that move • malignant or benign tumors • ACCURACY • within 0.5 mm • STABILIZATION • frame must be surgically stabilized to the skull with screws • frame is fixed to table to prevent movement of the head during treatment • RETREATING • generally only 1 dose used because of the nature of the frame • COLLIMATORS • circular collimators of sizes 4, 8, 14, & 18 mm – 4 sizes in total • limits lesion size • multiple beams • HOW IT WORKS • MRI and CT scan must be done of the cranial regions a few days prior to radiation to make the correct calculations for precision of the converging beams • CT scan of the head confirms position of tumor • beams converge at isocenter(s) with a high dosage of radiation while surrounding tissues have a significantly lower dose • beams target either a single isocenter (spherical lesions) or multiple isocenters (irregular shaped lesions)

Treatment Type Description

Conventional Radiation Therapy

CyberKnife® Radiosurgery

Conventional radiation therapy CyberKnife Radiosurgery administers a broad beam of delivers radiation beams that low dose radiation from only a can be targeted from virtually few directions, thus limiting any direction with subhow closely the tumor can be millimeter accuracy, while covered with radiation. In order limiting the damage to to prevent the normal surrounding healthy tissue. As surrounding tissues from a result a higher and more receiving too much daily effective dose of radiation can radiation, many low doses of be delivered to the tumor in radiation must be administered fewer treatment sessions, over a longer period of time. which increases patient convenience.

Treatment Time

Usually 30 to 45 treatments over a period of six to eight weeks–each lasting 15 to 30 minutes in duration.

Each treatment generally lasts between one to three hours, ad the treatment course is typically completed in one to five visits.

Side Effects

May include fatigue, malaise, mouth and throat pain, nausea, diarrhea and skin irritation, depending on the site of treatment.

Fewer side effects when compared to conventional radiation techniques. (Your doctor can advise you of possible side effects based on your type of tumor and specific treatment pain.) In addition, no invasive head or body frame is required, which enhances patient comfort.


For Further Information Youtube: Cyberknife. User: abmedica. Youtube: Accuray Cyberknife. User: peusdeus.

Resources Cyberknife. Wikipedia. Retrieved June 18, 2011, from Cyberknife vs. gamma knife. (2008). Retrieved from Gamma Knife. Wikipedia. Retrieved June 18, 2011, from Hoffelt, MD, S. Christopher. (2006). Gamma knife vs. cyberknife. Oncology Issues, 21(5), Retrieved from Picture from:

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Cyberknife vs. Gamma Knife