Gamma Knife Radiosurgery

Gamma Knife Radiosurgery is a modality that was discovered by Lars Leksell, a Swiss Neurosurgeon, and gifted to the community of medicine. Although initial developmental efforts date back to 1950s, the Gamma Knife device was first used for treatment in 1968. The first Gamma Knife therapy was performed in 1997 in our country. Gamma Knife Radiosurgery has gradually evolved and now, it offers strikingly successful outcomes in selected patients.

How Does Gamma Knife Radiosurgery Differ From Radiotherapy?

In Gamma Knife Radiosurgery, head of the patient is immobilized with a metallic frame, called stereotactic frame, and the focused radiotherapy is delivered to the intended part of the brain inside the cranium.

Considering its difference from radiotherapy, radiation beams are delivered to a larger area in several sessions in conventional radiotherapy, while Gamma Knife focuses the radiation to the target zone in a single session. Since the nearby healthy tissues are irradiated in radiotherapy, doses are divided into fractions to prevent the damage to healthy tissues. In radiosurgery, the device allows for focusing the radiation beams on the target zone and therefore, the radiation exposure to nearby healthy tissues is minimized.

Another question about Gamma Knife Radiosurgery is about whether it can be repeated for metastases. For example, a tumor can be treated for the second time 6 months after the tumor is managed with radiosurgery, if a lung cancer spreads to the brain.

How Does Gamma Knife Radiosurgery Differ From Radiotherapy?

  • It can be used for certain vascular disorders of the brain. The primary example is congenital arteriovenous malformation (AVM). The condition should be treated, as it may lead to cerebral hemorrhage and epilepsy episodes, and Gamma Knife can be used for the treatment. There is another type of arteriovenous malformation, called cavernoma. It can also be used for this condition. The intended use also covers certain vascular fistula.
  • It is also a therapeutic option for various benign brain tumors. Other examples include meningioma – a tumor that originates from meninx – and Vestibular Schwannoma that implies tumors of vestibular nerve, which is responsible for hearing and balance. 
  • It may also be used for treatment of malignant tumors. Primary ones are metastases that originate from another body part and spreads to the brain.
  • It may also be considered for Trigeminal Neuralgia (sudden-onset facial pain) or tremor, both called functional disorder.

Stages Of Gamma Knife Therapy

A Gamma Knife team consists of a neurosurgeon, a radiation oncologist, a medical physicist, a technician and a nurse. First, the stereotactic frame is attached to the head under local anesthesia in order to stabilize the cranium. In case of a child, the procedure is carried out under sedation.

MRI is scanned, after the frame is attached, and angiography can also be performed in case of an AVM. A computer software is used to plan the treatment, identify the target and determine the dose of the radiation. After the treatment plan is finalized, the procedure is started in another section, namely the treatment unit.

The procedure takes 10 minutes to 3-4 hours. The duration is dictated by the volume of the lesion and the dose of the radiation. Although Gamma Knife surgery alone (or in other words, it is not combined with other treatment modalities) treats the condition in some patients, a surgery is a must in others, followed by Gamma Knife radiosurgery for postoperative residual tumor.

Stages Of Gamma Knife Therapy

The patient is periodically followed up after Gamma Knife Radiosurgery. The tumor is checked on once every 2 to 4 months, if Gamma Knife Radiosurgery is performed to manage metastasis. Patients are asked to have an MRI scan once a year in case of benign tumors. Thus, it is possible to check growth of the tumor. A certain period of time is required to witness effects of the therapy, as the radiation needs some time to exert its effects. It may take 2 to 3 months to see those effects for metastases, while it may take several years for a slowly growing benign tumor. Gamma Knife intends to stop the growth of tumor. However, it is necessary to make the abnormal tangle of blood vessels disappear, if Gamma Knife is performed to treat an arteriovenous malformation (AVM). It may be necessary to wait for 2 to 3 years to get this effect.

Advantages Of Gamma Knife Therapy

  • General anesthesia is not required.
  • Patients can be discharged in the same day following the Gamma Knife Radiosurgery.
  • Haircut is not necessary for the treatment.

Gamma Knife Icon offers the option of treatment with a face mask similar to a stereotactic frame or radiotherapy.

Frequently Asked Questions

Prof. Dr. Selçuk Peker answered frequently asked questions.

Gamma Knife is not a knife in traditional sense. This treatment modality uses a sophisticated technology rather than a knife and delivers gamma rays very precisely to the target zone of the cranium in a single session.

The gamma rays destroy the diseased area in a safe and effective manner similar to a scalpel used in a surgical procedure. However, there are no surgery-related problems, such as bleeding, infection and stay in intensive care unit.

Very tiny beams of gamma ray can be focused on very small areas thanks to the advanced imaging and planning techniques of the Gamma Knife Radiosurgery.

The radiation beams, generated by 192 gamma ray sources, are focused on the diseased area and thus, the nearby health brain tissue is exposed to negligible radiation, while a high dose of radiation is generated at the target. All these procedures are completed within several hours and the patient can be discharged to home on the same day.

The term “Radiosurgery” is named after Lars Leksell, a Swiss Neurosurgeon.

It implies focusing numerous low-energy (which, therefore, does not cause damage to the brain tissue it passes through) radiation beams on the diseased part of the brain and creating a change in the tissue by generating high energy only at the target.

Gamma Knife device was first used in 1968. Although it was available only in a few centers around the world in the preliminary evolution phase, it gained a wide field of use, after curative benefits were proven. Today, it is used in more than 330 centers worldwide. According to the figures of 2016, more than one million patients with various brain diseases have been treated with Gamma Knife.

Although LINAC systems, such as X-Knife and CyberKnife, are also used to irradiate brain pathologies, there is no device yet that has reached the precision of Gamma Knife. Moreover, other devices also drop behind in terms of case experience.

The basic principle of Gamma Knife surgery is to determine the diseased area digitally (using a software) after the head is stabilized with a stereotactic frame and to deliver many (192-201) gamma rays generated by Cobalt source to the target. Healthy brain tissues are not damaged, as the radiation beams emitted by each source have low energy; on the other hand, a potent radiation effect is observed at the location, where all beams are focused.

Gamma Knife can be used for AVMs, brain tumors and functional diseases. It provides the patients with an option of blood- and scalpel-free treatment. The intensive care need is eliminated and the treatment takes only several hours. Most patients can resume routine activities of daily life in the next day after the treatment.
Today, most of patients look for relatively simple treatments to get rid of their diseases. Medical investigations are intensely conducted to meet this request. Gamma Knife fulfills this need, as it is a non-invasive treatment modality.

Gamma Knife Radiosurgery is particularly recommended for patients with such health problems or age-related higher potential for surgery-related complications. Gamma Knife Radiosurgery offers a tremendous advantage for patients who have contraindications for general anesthesia.

You may return to your daily life immediately after the treatment. The pre-treatment restrictions, if any, do apply without any modification. Gamma Knife Radiosurgery does not require a specific restriction.

No. Haircut is not required for this procedure.

The effects of Gamma Knife Radiosurgery can be seen in varying intervals, ranging from several months to several years. This interval varies in each disease. Patients should have certain examinations, such as MRI and Angiography, at intervals recommended by their doctors in the follow-up. Gamma Knife Radiosurgery intends to control growth of the tumor – no increase in size of tumor or shrinkage of the tumor.

You may feel a very mild pain while the stereotactic frame is attached to your head. Local anesthetic agents are used to minimize this condition. Attachment of the frame causes a feeling of pressure, but it disappears in several minutes. Patients do not feel any pain during the treatment. It is not possible to see or feel the radiation.

Yes, patients are awake in this procedure. However, sedative agents can be considered for excited patients. Your doctor may talk to you through a speaker and microphone during your treatment.

Gamma Knife Radiosurgery is a non-invasive neurosurgical method that affects the diseased tissue very accurately with gamma rays. It is not associated with potential complications of open surgeries, such as bleeding and infection. Since hospitalization is not required, resultant problems are not faced. The risk of reaction in the healthy tissue secondary to the radiation energy is about 1 to 2 percent. Most of them are also transient.

  • Please prefer an experienced team that has already treated too many patients. Your requirements will be better understood and the necessary treatment protocol will be safely performed by a team that has used Gamma Knife Radiosurgery in numerous patients with various diseases. The Gamma Knife Radiosurgery team of the Koç University Hospital has a substantial experience, based on thousands of patients treated to date, not only in our country but also at global scale.
  • Prefer a team that carries out investigations and authors scientific papers about Gamma Knife Radiosurgery. Undoubtedly, a team that carries out investigations and writes scientific papers monitors all advancements very closely. It is advantageous for patients to be treated in an organization that has mastered all recent advancements. The Gamma Knife Radiosurgery team of the Koç University Hospital monitors the scientific advancements very closely through scientific papers presented in local and international congresses.
  • Prefer a center that uses state-of-the-art equipment. Gamma Knife Radiosurgery Center uses the most new-generation computer software and equipment. MRI scanners with strong magnetic field and digital angiography devices are used in pioneering Gamma Knife Radiosurgery centers. All these factors ensure highly efficient and safe treatment for patients. The latest generation “ICON” device is available in the Gamma Knife Radiosurgery Unit of the Koç University Hospital.

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