Oncology: Radiation

In general, no. If you are being treated with brachytherapy (radiation source placed inside of the body) or with the Gamma Knife (stereotactic radiosurgery), radioactive substances are used for these procedures. For all other radiation treatments, we produce our own radiation which stops as soon as the machine is turned off at the end of your treatment session.

Our treatment machines are linear accelerators which use a lot of electricity to accelerate electrons and aim them into a target made of a heavy metal (Tungsten). The interaction of electrons with a large atom such as Tungsten produces gamma rays which are precisely aimed for treatment to the area of interest.

You will be in our department for approximately 30 minutes on a daily basis (Monday-Friday). You will be lying on the table on the treatment machine for about 15 minutes and the machine will be delivering radiation for about 2-3 minutes. Some types of treatment may take longer, but most radiation treatments are scheduled in 12-15 minute time slots.

It turns out that our body’s normal cells have a good mechanism for radiation repair from exposure from ultraviolet radiation from space and ionizing radiation from the earth. Most cancer cells are putting all of their energy into cell division and are generally not good at repairing damage to DNA from radiation. Therefore, radiation preferentially affects cancer cells instead of the body’s normal cells.

The radiation therapists will monitor you by closed-circuit camera with audio during the duration of your treatment (typically less than five minutes). Treatment can be interrupted if needed and the therapists will inform you of how to let them know that you need their attention. The therapists cannot be in the room with you during treatment because of the risk of radiation exposure.

Nearly all treatments are delivered five days a week (Monday-Friday). There are some situations where treatment is not delivered on a daily basis, but this is not common. Typical treatment courses last between two and eight weeks, however some situations may require as few as one treatment. Your doctor will provide you with information regarding the best treatment schedule based on your specific situation.

Most patients have a CT before starting radiation treatments as part of the simulation procedure. The scan utilizes a low radiation dose protocol and often does not involve contrast in the bloodstream. Another scan is obtained as the body’s position for radiation treatment is different than the position for diagnostic scans. Also, the radiation oncologist is present during this procedure to assist with your positioning and any other procedures necessary for planning your course of radiation.

The side effects of radiation depend on the treatment site. In most cases, the side effects will be limited to the area of the body receiving treatment. Most patients can expect mild to moderate fatigue which resolves within 4-6 weeks of completing treatment. Skin reaction consists of redness, itching, and dry peeling in many cases with the chance of a radiation burn (blistering or moist peeling of the skin) of less than 15% in most cases. Your doctor will describe expected side effects in your case based on your treatment type and area of the body receiving radiation treatments.

In most cases, there is not an interaction between most drugs or supplements and radiation therapy. Chemotherapy agents are an important exception and your radiation oncologist will work closely with your chemotherapy doctor in cases where chemotherapy and radiation are given at the same time.  Your doctor will need to have a complete list of all of your medications and supplements so you can be informed of any potential interactions. If you start or stop a medication or supplement during treatment, please let your radiation oncologist or nurse know so that we can keep your medication record up to date and provide you with advice if needed.

Cone beam CT is a type of image guidance where the radiation machine will spin around you one to two times before your treatment is delivered. Images (similar to CT images) are produced and reviewed by your doctor at the control panel just before treatment is delivered. This allows for fine tuning of the aim of the radiation beams for your treatment on a daily basis by the physician and results in more accurate delivery when additional precision is necessary in some treatment cases (typically used for head and neck and prostate cancer treatment).

There is excellent, comprehensive, easy to understand information available from The American Cancer Society (www.cancer.org), The National Cancer Institute (www.cancer.gov), and The American Society of Clinical Oncology (www.cancer.net). Detailed information and videos about radiation therapy can be found from the American Society for Radiation Oncology (www.rtanswers.org). Your radiation oncologist can be helpful with any questions or by helping you research specific topics as well.