Stereotactic Radiotherapy or sometimes known as Stereotactic Radiosurgery is a type of radiation therapy which is different from general radiotherapy. It has high precision by using beams of various intensities from different angles in a way that the target gets maximum exposure, whereas the surrounding tissues and organs get the least exposure. This is best for small area of treatment with precise margin or in patients at high risk for invasive surgery.
The radiation may be done with a single dose, called the Stereotactic Radiosurgery (SRS) where no invasive surgery is involved and this may be done at several targets at once.
The radiation may be done many times for disease found in the brain, called Stereotactic Radiotherapy (SRT) where number of doses will be prescribed according to each patient.
The radiation for target outside the brain is called Stereotactic Body Radiation Therapy (SBRT) or Stereotactic Ablative Radiotherapy (SABR), where mostly radiation is given about 5 – 10 times.
Radiosurgery Center of Ramathibodi Hospital was established in the year 1997 to service patient with X-Knife® (1997 – 2015) which can perform Stereotactic radiotherapy only in the brain, base skull and upper neck. Later in the year 2009, the CyberKnife® was installed and can be used in every part throughout the body. This medical equipment has a special feature of small linear accelerator to create high energy photon X-ray which is located on an automated robotic handle that can be moved freely. The precision used with this X-ray to follow the target location results in an effective stereotactic radiotherapy, and reduces target deviation. Target with unclear location with X-ray image will be treated with small gold beads to help locating the target precisely. Apart from these, the target tracker can also take radiological images along with breathing movement in the chest or abdomen to find the correlation of target movement and breathing of the patient and monitor the robot motion to move along it throughout the radiation process.
Recently in the year 2016, the EDGE® radiosurgery system has been installed and opened for service, which is the linear accelerator that creates high energy photon X-ray that was designed for stereotactic radiotherapy of the whole body. It has special Multileaf Collimators which is meticulously very small and has various target locators with movement detector while performing therapeutic treatment process for the patient appropriately due to the followings:
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Real-time 3D surface imaging which helps in treatment precision, as well as detecting movement of the patient while treatment and stops the treatment immediately if any incorrect dimension occurs.
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X-ray with CBCT (Cone beam computed tomography) that shows similar image of the CT scan on the platform.
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Radiofrequency tracking by embedding a small equipment into the body to track the target movement throughout the treatment process.
All of these are to help increasing the treatment precision and reduce incorrect measures for stereotactic radiation therapy.
Examples of diseases for such treatments are:
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Cancer metastasis into the brain
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Cerebral arteriovenous malformation (AVM)
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Skull base tumor & Spinal tumor
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Meningeal tumor
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Brain cancer
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Vestibular Schwannoma
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Pituitary tumor
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Cancer in lung, liver, pancreas, etc.
The patient undertaking the treatment will receive appropriate fixation equipment to be able to stay still in one posture comfortably throughout the treatment, CT scan will be performed which may include diagnosis with MRI, 4DCT or other additional diagnosis for best target location and use these results to plan the treatment in the computer most appropriately for each patient, where patient’s admission to stay overnight at the hospital is not required throughout the process.