The Proton Experience

Now that I'm in the middle of my treatment I get questions from friends about it. Specifically the daily ritual. I often say, "it's nothing" or, "piece of cake". I wonder if they think I just don't want to discuss it, but the truth is that it is so mundane and non-invasive that there is really very little to discuss. I'll give it a shot.


First I guess I should explain why I chose Proton radiation. Prostate cancer, unlike many other diseases has several treatment options. You can make strong arguments about the effectiveness and side effects of each. The fact that a disease has a half-dozen treatment options probably means that none of them are great. Most people choose surgery. Within the surgery category, you have two choices: conventional "open" surgery or (in theory) less-invasive robotic surgery. And right there you could have a heated discussion about the pros and cons of each surgery type. No surprise, but the best surgical outcomes seem to be directly tied to the (significant) experience of the surgeon. It is a extremely challenging procedure. The urethra is clipped - as it runs right through the prostate - and then sewed back to the bladder. The nerves that allow for erections run along both sides of the prostate. If either of these nerve bundles cannot be saved or is damaged in surgery the patient will almost certainly experience ED issues. Some people are not even candidates for surgery. If it is determined through tests that the cancer has escaped the prostate capsule surgery is not usually recommended (what's the point?) Most of those guys are treated with a combination of hormone therapy and radiation.



Many men chose radiation. Conventional radiation. Guided radiation techniques are improving, but I did not seriously consider this option because a lot of the radiation is spent entering the body and in exiting the tumor area. Some men have radioactive seeds implanted in the prostrate (usually about 100 seeds, each the size of a grain of rice) This is Brachytherapy. A very few choose "freezing" or Cyrosurgery. The latest "new" technique is HIFU. High Intensity Focused Ultrasound. It is not approved yet in the USA, but is available in Europe, Japan, Canada and Mexico. I really think there is a lot of promise for HIFU as a high-success, low side effect treatment. I wouldn't be surprised if it became the preferred standard in 10-15 years. But for now there are two competing machines being evaluated and doctors are still perfecting their skills with HIFU. I read of a couple guys who had the procedure in Canada with less than wonderful outcomes.



I chose Proton therapy because it seems to offer cure rates on par with surgery and it seems to have fewer side effects. I liked the physics behind it. With protons, the technicians can deliver the majority of the energy directly to the prostate. (I won't even try to explain it here... Google: "proton Bragg Peak" for more). I was pretty sure that my small and modestly-aggressive tumor would be killed by the radiation. Surgery just seemed so medieval. Not all insurance pays for Proton radiation, but mine will. And being temporarily unemployed I had the time to travel to one of the 5 proton centers for treatment. I also chose a clinical trial where I receive a larger daily dose of radiation and have fewer total sessions. This will make my stay in California one month shorter and (in theory) get me back on someone's payroll a month sooner.

Loma Linda has three proton treatment gantrys (the 30' rotating "cone") You are assigned a gantry and always are treated in the same one. This leads to affectionate referrals to being a "gantry 3" graduate just as someone might refer to the "class of 1995" or "Pi Kappa Alpha". Prior to beginning treatment your "pod" (what I'm laying in above) is crafted especially for you. Liquid mold is poured into the pod shell while you lie still. This way your body is always in the same position for each treatment. Also prior to the first treatment a CT scan is taken and the doctors use that to design unique apertures for each patient. These apertures guide the proton beam even more directly to the precise area. Patients receive radiation each weekday. You're supposed to drink 2-4 glasses of water 30 minutes before each treatment. This helps to lift the bladder up and out of the way of the radiation beam. I'm not sure some guys always drink the water but I was lectured that it was especially important for the clinical study, so I am very faithful with my water intake. I cannot tell you how many times my bladder has been ready to burst toward the end of a session, but it is a minor inconvenience. Patients are called into a changing room and we don our hospital gowns...no reason to tie them closed...we all just flap open in the back. When the guy in front of you is done, he comes back to the dressing room and sends you in. You climb into your pod and the first thing you do is turn on to your left side for your "balloon". It's the necessary evil of Proton treatment. A technician inserts a condom-like balloon into your rectum and inflates it with 2 ounces of water. The balloon remains inserted for the next 10-20 minutes of treatment. The purpose of the balloon is to protect the rectum from the radiation. The pod is then positioned exactly using laser beams. The patient-specific aperture is loaded, the technicians leave the gantry for the safety of the control room and the radiation is delivered. And now through the magic of copy and paste, here is how it happens:

Each proton begins its journey at an injector located within an electric field. In the field, hydrogen atoms are separated into negatively charged electrons and positively charged protons. The protons are then sent through a vacuum tube within a pre-accelerator. This process boosts their energy to two million electron volts. The protons continue in the vacuum tube and begin their high-speed journey in the synchrotron. They travel around the synchrotron about 10 million times per second. Each time they circulate, a radiofrequency cavity within the ring delivers a boost of energy. This increases the protons' energy to between 70 and 250 million electron volts. The voltage achieved is enough to place them at any depth within the patient's body. After leaving the synchrotron, the protons move through a beam transport system, continuing in the vacuum tube through a series of steering and focusing magnets that guide them to the four treatment rooms. (A fifth room, used for beam calibration and basic research, contains three additional beam lines.) One treatment room has a stationary beam with two branches. One branch is for irradiating eye tumors and the other branch is for central nervous system tumors and tumors of the head and neck. The other three treatment rooms have gantries. Gantries are wheels 35 feet in diameter and weighing approximately 90 tons, which revolve around the patient to direct the beam precisely to where it is needed. From the patient's perspective, however, all that is visible is a revolving, cone-shaped aiming device. Each treatment room has a guidance system to direct the beam that treats the patient. The guidance system monitors the beam until it enters the patient and positions the Bragg peak to conform to the size and shape of the tumor and the immediate volume at risk for tumor spread, according to a plan designed by the physician. Field sizes to accommodate regional spread of tumors can be as large as 40 by 40 centimeters. The beam delivery system, or nozzle, is the last device the protons travel through before entering the patient's body. The nozzle shapes and spreads out the proton beam in three dimensions. When calculating the number of protons to be delivered to the designated volume and the velocity and shape of the proton beam, radiation oncologists take into account the location and shape of the target and the tissue density and depth through which the protons must travel to reach their target. After leaving the nozzle, the protons enter the patient's body. The entire proton facility is controlled by computers that are equipped with safety measures to ensure that patients receive proton radiation treatments as prescribed. Three host computers control the accelerator and beam transport system. A second set of computers, located in each treatment room, controls the beam guidance system and all other treatment room systems. These computers verify patient identification, set operational parameters for each patient's treatment plan, and direct the host computers to deliver a specified beam.

The actual delivery of the proton radiation takes about a minute. As a patient you feel nothing. There is a flywheel that you hear once the beam is into your gantry...this is followed by a smoke-alarm (though not as harsh) type beeping...it's just the radiation detector in the gantry. Usually there is a CD in the boombox...something soft like Jack Johnson, John Mayer, Sheryl Crow or James Taylor. Since I'm in the clinical trial I get radiation on both sides each day. So the gantry rotates 180 degrees and the process is repeated for me. It adds 5-10 minutes to each session for me...but I'll be done five weeks sooner than patients in the standard protocol. I roll back over, my balloon is removed and I'm on a beeline for the dressing room bathroom.

That's it...kind of boring, but not much to it. Certainly nothing like the chemotherapy my wife suffered through three years ago. Possible side effects during treatment include fatigue, urinary frequency/urgency and some urinary difficulties. I'm not experiencing any fatigue, but I'm noticing some of the plumbing issues. The long-term side effects of Proton radiation could possibly include rectal bleeding and a degree of erectile dysfunction. Long-term proton side effects usually do not appear for 6-12 months post treatment - if at all. Of course I hope to be in the "if at all" category.