The most accurate way to deliver radiation, upgrading a century-old treatment.
Just about everyone knows that radiation is a standard form of treatment for cancer. It’s been used since 1896 in the form of x-rays. As you would imagine, in the last 120 years it’s been substantially improved and is now provided in different forms, with x-rays still one of them.
The objective in all forms of radiation therapy is to alter the DNA of the cancer cells so they do not reproduce and lose fluids. That causes the tumor to shrink at the rate of the cancer cells’ growth.
The different forms of radiation and delivery are all aimed at accomplishing the same objective. But that’s approached differently according to the cancer type, stage and other variables.
One radiation treatment option is stereotactic radiosurgery (SRS). Anova Cancer Care uses the CyberKnife robotic surgical system to perform SRS. Even though it has “surgery” in its name, stereotactic radiosurgery is not surgery at all. It got that name because the effects in the targeted zone are so dramatic they are referred to as “surgical.” CyberKnife and all methods of SRS discussed below apply radiation.
Some basics on radiation therapy
Cancer treatments utilize ionizing radiation that creates ions in cells it passes through. The ions, electrically charged particles, can kill cancer cells and stop their growth. The two types of ionizing radiation are photon (uses x-rays or gamma rays) and particle (uses electrons, neutrons, protons, alpha particles and others).
High-energy photon beam, the same as used in an x-ray machine, is the most commonly used in radiation therapy for cancer. Photon beams affect all cells they pass through before exiting the body.
Proton beam is a type of particle radiation. Proton beam releases its energy only after travelling to its target, causing little damage to the tissues the beams pass through.
Both photon beams and proton beams can be produced by a linear accelerator. CyberKnife is a specialized type of linear accelerator and is one way to perform stereotactic radiosurgery (SRS). It also produces electron and particle beams used to treat skin cancers and tumors close to the skin.
The three forms of SRS are linear accelerator (CyberKnife), proton beam and Cobalt-60 based using photons. Each type uses different technology, instruments and sources of radiation. And each are appropriate for delivering high-energy radiation to treat certain cancers.
All forms of SRS differ from traditional radiation therapy, which delivers radiation to a wide tissue field and damages more of the healthy tissue. SRS more accurately targets the cancer tissues specifically. The difference is in how they do that.
Comparing stereotactic radiosurgery methods
Stereotactic radiosurgery merges 3-D computer-assisted delivery of radiation with a high degree of accuracy to target only the cancerous cells and not surrounding healthy cells. That accuracy used to be achieved by limiting treatment to areas of the head and neck that could be immobilized by placing the patient’s head in a form, or screwing a plate into the skull. That’s now changed.
Linear accelerator SRS (CyberKnife)
The CyberKnife Robotic Radiosurgery System is the specific type of linear accelerator Anova Cancer Care uses. Other manufacturers produce linear accelerators, such as the Novalis Tx machine. Linear accelerators have benefits over the other types of SRS.
- One of the main advantages of the linear accelerator is that it can treat larger volume tumors by doing it over several sessions.
- Treating over time like this is called fractionated stereotactic radiotherapy, and it allows a flexibility unmatched by other machines providing SRS.
- Can be used on the head, neck and throughout the body.
- Linear accelerators move around the patient, eliminating the need for restraining devices.
- Delivering one large radiation beam that is split into many different arcs lessens the damage to healthy tissue.
Advantages of CyberKnife
In addition to the linear accelerator benefits above, CyberKnife has other specific advantages.
- Uses proprietary software that adjusts for patient movement – even breathing – during radiation beam delivery. This real-time, 3-D respiratory motion adjustment is key to CyberKnife’s reduced damage to healthy tissue.
- Image guidance compensates for the shifting of tumors during treatment and automatically adjusts to the location without pausing treatment. Tiny gold markers can be placed around the tumor to aid in this.
- CyberKnife can move in 360-degrees on multiple planes, where most other SRS delivery systems are limited to clockwise and counter-clockwise directions. CyberKnife’s flexibility delivers the beam of radiation in hundreds of different angles to target the precise margins of the tumor.
- Treatments can be completed in 1-5 days.
- No pain, no anesthesia, no pain medications, no recovery time or rehabilitation needed.
- Patient can go home right after treatment.
With rising PSA and a prostate cancer diagnosis, Gary now recommends CyberKnife to others
Particle/proton beam SRS
The radiation oncologist directs the high energy of the proton beams in a 3-D pattern from each beam. The protons release their maximum energy when they reach the designated target. The major limitation of proton beam SRS is that there are only a few facilities in the nation, as each facility costs upwards of $100 million.
Cobalt-60 SRS (Gamma Knife)
Cobalt-60 is a synthetic isotope of cobalt that produces gamma rays when it decays. It has been used to deliver radiation for the treatment of brain cancer since 1950, and that is still the cancer it is most often used on. The most well-known machine for delivering cobalt-60 is the Gamma Knife.
Gamma Knife doesn’t move during treatment so it can deliver high-energy radiation in a precise area of the brain. These machines are generally only located in dedicated neuroscience centers, and they are limited to treating brain cancers and some other smaller tumors.
CyberKnife is a specially advanced type of linear accelerator that has the versatility to effectively treat a wide range of cancers while greatly minimizing side effects commonly associated with radiation therapy.