There is one marked difference between proton beam radiation and cyberknife.

men with prostate cancer are understandably concerned over which treatment modality will be most effective.

“Both protons and cyberknife involve precision delivery of radiation therapy,” says Sean Cavanaugh, MD, Chief of Radiation Oncology, Cancer Treatment Centers of America at Southeastern Regional Medical Center.

“In general, radiation therapy involves delivering the desired target dose to the tumor as well as undesired entrance and exit dose across healthy tissue,” continues Dr. Cavanaugh.

In other words, more conventional radiation causes a so-called collateral damage. Think of a bomb being set off in a little town to get rid of dangerous criminals … but the good guys will get blasted too.

Entrance and Exit Dose Defined

• Entrance dose: The dose of radiation that inadvertently makes contact with normal cells before it reaches the cancerous tissue.

• Exit dose: Imagine the radiation hitting the tumor, but then continuing on beyond it, taking out normal cells in its path.

“The primary difference between proton therapy and Cyberknife is that protons do not have an exit dose,” says Dr. Cavanaugh. “Both modalities deliver entrance and target dose.

“Many insurers have been unimpressed with the differences in outcomes with proton therapy and have declined to pay.

“For many patients I prefer HDR brachytherapy [diagram below] to both proton and Cyberknife therapy.” HDR stands for high dose rate.

HDR Brachytherapy: What It Is

This technology does away with entrance and exit doses because the radiation is released after a pellet is placed inside of, or very near to, the prostate cancer mass. This is why this form of treatment is often called “seed.”

HDR brachytherapy is “tightly focused on tumors to minimize serious side effects,” says the CTCA site.

Exposure of radiation to the surrounding benign tissue is minimized, while the maximum dose is delivered to malignant cells.

The “Seeds”

“Tiny, hollow catheters are temporarily inserted directly into a tumor,” explains the CTCA site.

Prior to each treatment, the surgeon will check the position of these catheters right down to the last millimeter.

The next step is radioactive pellets are inserted into each of the catheters.

• With the help of a computer, the surgeon is guided as to how far the pellet should go into the catheter; you’ll want precision by the millimeter for targeting the tumor.

• The computer also helps indicate for how long the pellet is to remain in the catheter while it releases the radiation.

• Treatment sessions take only minutes but may be combined with other treatments.

For additional information on brachytherapy, proton beam or cyberknife treatment for prostate cancer, contact CTCA at (855) 993-3381. 
Dr. Cavanaugh has chaired the hospital’s Prostate Center for Advanced Oncology and Prostate steering committee. He regularly performs high-dose and low-dose rate brachytherapy, plus all aspects of highly conformal external beam radiation therapy.
Lorra Garrick has been covering medical, fitness and cybersecurity topics for many years, having written thousands of articles for print magazines and websites, including as a ghostwriter. She’s also a former ACE-certified personal trainer.  

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Top image: Shutterstock/Chinnapong
Source: cancercenter.com/treatments/high-dose-rate-brachytherapy/ Proton beam vs. cyberknife