By Ramesh T Kumar
Brief History:
Radiation therapy has been utilized for over a century in the treatment of cancer. Traditional radiation treatments involve machines called Linear Accelerators which produce intense, high energy x-ray beams which when aimed to any part of the body will destroy tumors. Since, there is a significant dose of radiation that is spilled over into surrounding normal tissue causing side effects, these treatments are generally given once a day (rarely twice a day), 5 days a week over several weeks ranging from two weeks to eight weeks. Delivering such small amounts of radiation allow a relatively greater control of side effects. Essentially, the dose of radiation to the surrounding normal tissue, in several instances limits our ability to deliver higher amounts of radiation to destroy cancerous tumors. Thus, we have the results that were somewhat mediocre in several instances where we could have done better.
A new field of Radiation therapy was born several years ago called Radio surgery. Unlike, traditional radiation therapy, this form of radiation delivered by specialized machines allowed massive amounts of radiation to be delivered to the target area from multiple different directions that any of the surrounding normal tissue received a relatively meager amounts of radiation thereby limiting the degree of side effects that patients would experience. This also allowed these high doses of radiation to be delivered in one to five sessions instead of the several weeks that was involved with traditional radiation treatment.
Radio surgery implies that there is some form of surgery that is involved. This is not the case. The term indicates that huge amounts of radiation is directed to the target area from the outside in and has such a destructive effect on the cancer, that it is as good as actually going in and removing the tumor surgically. The other advantage of Radio surgery is the fact that this form of radiation can be directed safely to tumors located in areas of the body where any surgeon would fear to tread!
Types of Radio surgery Systems
The Old Guard:
Gamma knife radio surgery system was the first form of radio surgery that was put into clinical practice. The machine uses what is called gamma radiation that is produced by radioactive cobalt sources located within the machine. The main disadvantage of this technology is the fact that this can be used in selected patients with brain problems only and it is incapable of treating targets outside the cranial area. The procedure also involves placement of a halo which is basically screwed into the skull bone which has to be done to ensure accurate delivery of treatment. The procedure involves several hours and generally is used for one session.
Linear Accelerators Re-Invented:
Heavy duty computers that began rolling out at the turn of this century, allowed a major leap forward for Radio surgery technology. With the enormous computing powers that were made available, Linear accelerators were modified to perform this procedure. Unlike Gamma knife, radiation physicians now had the ability to perform Radio surgery on targets anywhere in the body and not be restricted to the skull area only. Linear Accelerator based systems include the Novalis TX and Varian Trilogy unit.
The New Kid on the Block:
The pinnacle of a true and dedicated Radio surgery machine had to wait till the introduction of Cyber knife Robotic Radio surgery system. Even though the word includes "knife", as discussed above, it basically indicates an ablative amount of radiation that equates to actually going in and cutting the tumor out. The technology is unique and different from the gamma knife system and the Linear Accelerator based systems, in the fact that this is the only Radio surgery system that can achieve what is called "realtime tracking of the tumor". What this means is that the Cyber knife system uses imaging technology that actually "sees" the target and tracks its movement very similar to the way our eyes move when watching a moving object. The position of the tumor at any given point in time is relayed to the radiation arm of the machine which radiates the tumor no matter where it moves about within the body. This is very similar to the way a boxer watches and follows the movement of his opponent while continuously jabbing away thereby knocking the daylights out of him!
What kind of patients are helped by Linear Accelerator based Radio Surgery Systems?
Several selected patients with both malignant and non-malignant situations are candidates for Radio Surgery. The following are examples of situations where Radio surgery has been found to be both safe and effective.
Among the most common non-malignant situations would be those patients with a condition called Trigeminal Neuralgia. Others include benign brain tumors such as pituitary tumors and tumors of the acoustic nerve.
In the Malignant category, patients with small cancers of the brain including solitary or few brain metastasis can be helped with just one session of Radio Surgery.
Patients with tumors involving the spine, can be treated effectively with very little effect on the adjoining spinal cord.
Small lung cancers that are isolated and with no evidence of spread can be treated effectively with 3 sessions of Radio Surgery treatment. An article that was published in the Journal of the American Medical Association Patients with inoperable non-small cell lung cancer who received stereotactic body radiation therapy had a survival rate of 55.8% at 3 years, high rates of local tumor control, and moderate treatment-related morbidity. 3 year survival rates for such patients treated with traditional radiation over several weeks was only 20 to 35%. The difference seen is huge and gives new hope for such patients.
Prostate cancer: Selected patients with early stage prostate cancer can elect to be treated with Radio surgery either as the only method of treatment or added to a short course of traditional radiation for about 5 weeks and subsequently undergoing Radio Surgery as a "boost" dose to knock the tumor located in the prostate.
Radio surgery as a sub-specialty of Radiation Oncology is a young and rapidly evolving field and is allowing more effective, safe and non-invasive ways of treating cancer patients, enabling better cancer control rates without disabling surgery and without all the risks associated with it. This has given new hope for patients with cancer as well as their families.
Brief History:
Radiation therapy has been utilized for over a century in the treatment of cancer. Traditional radiation treatments involve machines called Linear Accelerators which produce intense, high energy x-ray beams which when aimed to any part of the body will destroy tumors. Since, there is a significant dose of radiation that is spilled over into surrounding normal tissue causing side effects, these treatments are generally given once a day (rarely twice a day), 5 days a week over several weeks ranging from two weeks to eight weeks. Delivering such small amounts of radiation allow a relatively greater control of side effects. Essentially, the dose of radiation to the surrounding normal tissue, in several instances limits our ability to deliver higher amounts of radiation to destroy cancerous tumors. Thus, we have the results that were somewhat mediocre in several instances where we could have done better.
A new field of Radiation therapy was born several years ago called Radio surgery. Unlike, traditional radiation therapy, this form of radiation delivered by specialized machines allowed massive amounts of radiation to be delivered to the target area from multiple different directions that any of the surrounding normal tissue received a relatively meager amounts of radiation thereby limiting the degree of side effects that patients would experience. This also allowed these high doses of radiation to be delivered in one to five sessions instead of the several weeks that was involved with traditional radiation treatment.
Radio surgery implies that there is some form of surgery that is involved. This is not the case. The term indicates that huge amounts of radiation is directed to the target area from the outside in and has such a destructive effect on the cancer, that it is as good as actually going in and removing the tumor surgically. The other advantage of Radio surgery is the fact that this form of radiation can be directed safely to tumors located in areas of the body where any surgeon would fear to tread!
Types of Radio surgery Systems
The Old Guard:
Gamma knife radio surgery system was the first form of radio surgery that was put into clinical practice. The machine uses what is called gamma radiation that is produced by radioactive cobalt sources located within the machine. The main disadvantage of this technology is the fact that this can be used in selected patients with brain problems only and it is incapable of treating targets outside the cranial area. The procedure also involves placement of a halo which is basically screwed into the skull bone which has to be done to ensure accurate delivery of treatment. The procedure involves several hours and generally is used for one session.
Linear Accelerators Re-Invented:
Heavy duty computers that began rolling out at the turn of this century, allowed a major leap forward for Radio surgery technology. With the enormous computing powers that were made available, Linear accelerators were modified to perform this procedure. Unlike Gamma knife, radiation physicians now had the ability to perform Radio surgery on targets anywhere in the body and not be restricted to the skull area only. Linear Accelerator based systems include the Novalis TX and Varian Trilogy unit.
The New Kid on the Block:
The pinnacle of a true and dedicated Radio surgery machine had to wait till the introduction of Cyber knife Robotic Radio surgery system. Even though the word includes "knife", as discussed above, it basically indicates an ablative amount of radiation that equates to actually going in and cutting the tumor out. The technology is unique and different from the gamma knife system and the Linear Accelerator based systems, in the fact that this is the only Radio surgery system that can achieve what is called "realtime tracking of the tumor". What this means is that the Cyber knife system uses imaging technology that actually "sees" the target and tracks its movement very similar to the way our eyes move when watching a moving object. The position of the tumor at any given point in time is relayed to the radiation arm of the machine which radiates the tumor no matter where it moves about within the body. This is very similar to the way a boxer watches and follows the movement of his opponent while continuously jabbing away thereby knocking the daylights out of him!
What kind of patients are helped by Linear Accelerator based Radio Surgery Systems?
Several selected patients with both malignant and non-malignant situations are candidates for Radio Surgery. The following are examples of situations where Radio surgery has been found to be both safe and effective.
Among the most common non-malignant situations would be those patients with a condition called Trigeminal Neuralgia. Others include benign brain tumors such as pituitary tumors and tumors of the acoustic nerve.
In the Malignant category, patients with small cancers of the brain including solitary or few brain metastasis can be helped with just one session of Radio Surgery.
Patients with tumors involving the spine, can be treated effectively with very little effect on the adjoining spinal cord.
Small lung cancers that are isolated and with no evidence of spread can be treated effectively with 3 sessions of Radio Surgery treatment. An article that was published in the Journal of the American Medical Association Patients with inoperable non-small cell lung cancer who received stereotactic body radiation therapy had a survival rate of 55.8% at 3 years, high rates of local tumor control, and moderate treatment-related morbidity. 3 year survival rates for such patients treated with traditional radiation over several weeks was only 20 to 35%. The difference seen is huge and gives new hope for such patients.
Prostate cancer: Selected patients with early stage prostate cancer can elect to be treated with Radio surgery either as the only method of treatment or added to a short course of traditional radiation for about 5 weeks and subsequently undergoing Radio Surgery as a "boost" dose to knock the tumor located in the prostate.
Radio surgery as a sub-specialty of Radiation Oncology is a young and rapidly evolving field and is allowing more effective, safe and non-invasive ways of treating cancer patients, enabling better cancer control rates without disabling surgery and without all the risks associated with it. This has given new hope for patients with cancer as well as their families.
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