Pictorial Overview of the Proton Therapy Treatment Process

Author: OncoLink Team
Last Reviewed: January 22, 2020

The following explains the steps generally followed when a patient is going to undergo proton radiation therapy. These may differ slightly depending on the protocol at your treatment facility or if your treatment is being done on an urgent basis, but many of the steps are the same across treatment facilities.

Initial Consultation

Whenever radiation therapy (proton or x-ray based) is being considered as part of your treatment plan, a consultation visit will be arranged for you with a radiation oncologist. A radiation oncologist is a physician specially trained in using radiation therapy for treating your type of cancer. The purpose of this visit is to discuss the role of radiation therapy in your treatment, to determine the type of radiation therapy that will be used, the plan for your treatment, and to answer any questions you may have. The consultation will take an hour or more, depending on your particular situation. Please bring with you all X-rays, laboratory studies, pathology slides and other tests that have been performed so that they can be reviewed by the radiation oncologist.

During the visit, your provider will perform a detailed history and physical examination. Your physician will also discuss their findings with other members of the multidisciplinary treatment team so that all treatments, such as surgery and chemotherapy, will be planned to ensure that you can receive the best possible care. At the end of the visit, your physician will review and recommend the role of radiation therapy in your care. If radiation therapy is not recommended, the physician will also discuss the reasons for this.

Informed Consent Process

If radiation therapy is recommended as a part of your treatment, your provider will review in detail the proposed treatment, the reasons for recommending the treatment, and the potential risks and side effects of such treatment. Ample time will be provided so that you have a full understanding of the treatment and related issues. All of your questions and concerns will be answered in full. It is encouraged that you bring a family member, a loved one, or friend with you, as they may be able to help you during the process and have their own questions answered.

Once you feel that you have a full understanding of the proposed treatment, risks, side effects, and other possible treatment options, you will be asked to sign a consent form. Before you sign the consent form, you need to make sure that you are comfortable with the explanation that you have received. Even after you have signed the consent, your care team is always available to answer new questions or to provide additional information. You can withdraw your consent at any time for any reason.

CT Simulation

Before radiation treatments begin, you will go through a treatment planning process called "simulation.” Simulation confirms the exact location that the treatment machine will treat. A CT scan of the location to be treated is done. Information from the CT scan is used to precisely locate the treatment fields and to create a "map" for the physician to design the treatment to fit your specific case. The CT scanner is specially designed to work with the other equipment in the department and is not a replacement for other diagnostic scans you may have received. The entire simulation takes about an hour, though the actual time may vary. Since you will be lying on a hard table for most of this time, you may have some pain or discomfort. Should this occur, tell the provider. Keep in mind that the time needed to deliver the actual radiation therapy treatments is only minutes, not nearly as long as the time needed for the simulation. In certain cases, an MRI or a PET/CT scan will also be done the same day as the CT simulation. The information provided by these scans is also used to plan your treatment.

CT Simulator

MRI used for simulation

Tattoos & Immobilization Devices

Tattoos

At the end of the simulation visit, it may be necessary to put marks on you to outline the treatment field(s). These marks are in the form of very small tattoos, which are dots, the size of a pinpoint or freckle, made using India ink. The process of tattooing causes some temporary discomfort. Generally, between 4 and 8 tattoo marks are placed, but sometimes more or less are necessary. In some treatment plans, a second set of tattoos may be necessary. While the tattoos are permanent, because of their very small size, they are not very noticeable. By using the tattoos, you will be able to bathe or shower on a daily basis without worrying about removing these important marks that show where the radiation treatments will be delivered. Also, if any additional radiation therapy is needed in the future, the tattoos serve as a permanent record of previous treatments. 

Steps of the tattoo process

While on the CT simulation machine, laser beams are used to mark the treatment area with a marker.

Supplies for tattooing.

A drop of India ink is placed on the mark.

A needle is used to puncture the top layers of the skin, getting the ink under the skin and creating the tattoo.

The small bluish dot in the center of this image is the tattoo.

Immobilization Devices

Immobilization devices are made for each patient who needs one. Whether or not you need one depends on the area of the body being treated and the treatment plan. These devices can be in the form of a mask that holds the head in position, or "molds" made out of a foam product that hardens and is molded to hold a particular body part in position. These assure that you are in the exact same position for every treatment. You will be fitted for an immobilization device, if needed, at your simulation visit.

Masks used for immobilization of the head.

Immobilization forms (body molds) for limbs of the trunk.

Technical Planning Process

After simulation, details from your visit are sent to medical radiation dosimetrists and medical physicists. These professionals perform highly technical calculations that will be used to set the treatment machine (Proton machine or "gantry”). The dosimetrist and physicist work closely with your radiation oncologist to develop the treatment plan, a process that can take up to a week or more.

Physician planning a treatment.

Set-Up

Several days after the simulation, and after all calculations have been performed, your treatment can begin.

The treatment machines (Proton machine or "gantry") look like the simulator, but are larger. You will be placed on the treatment table in the same position as you were on the simulator. Proper positioning usually takes 10 to 15 minutes. Once in place on the treatment table, a set of X-ray films will be taken. These films will be matched with the simulation films to make sure the treatment will be delivered the same way as it was simulated. Sometimes the match is not optimal. In these cases, adjustments will be made and will be checked by your provider. In rare cases, more adjustments are needed and treatment may be postponed. Once the films and positioning are confirmed, a treatment will be delivered. While it seems like a lot of time to plan and set up, it is critical that the treatment is delivered as it was planned. This helps avoid unnecessary harm to healthy tissue and makes sure the correct amount of radiation hits the treatment area.

The actual administration of the radiation treatment typically takes about 5 to 10 minutes. Factors that affect the total length of the treatment include the complexity of your treatment, the particular machine on which you are being treated, and how quickly you can be positioned properly for treatment.

Confirmation

Often, your provider will be called to see you at the machine to make sure that your position is correct. This should not cause you any concern, as it is a standard part of practice to ensure the most accurate delivery of the radiation treatments.

Daily Treatments

Once the initial set-up is completed, daily treatments normally follow. Treatments are usually given once a day, Monday through Friday, for a number of weeks. Each treatment generally takes only 20 to 30 minutes, including set up time; however, you will likely be in the department for an hour or so each day. Sometimes, twice-daily radiation treatments will be recommended.

Each day, the technicians will position you on the treatment table, using the tattoos, immobilization devices and laser beams on the machine to get you in the exact same position. The radiation therapist will be in the room for your x-ray and alignment process. Once you are ready for treatment they will leave the room to avoid exposing themselves to radiation. They will be able to see and hear you from a control room just outside the treatment room. They can also give you instructions over a microphone as needed during the treatment. The radiation therapists will come in the room between treatment fields and possibly take x-rays to verify positioning once again. As you lie on the treatment table, the table and proton gantry may move to get the radiation beams in the correct location. Once your position is confirmed, the treatment is given. The treatment is not painful, nor will you feel anything when the treatment occurs.

Radiation technician monitoring the treatment of a patient from the control room.

Proton therapy treatment room and machine.

Another view of the proton therapy treatment room and machine.

Proton therapy treatment room with a "fixed beam" machine.

On-Treatment Examinations

At least once a week, repeat X-ray films will be taken to reconfirm proper positioning. These films will also be performed in most cases where there is a change in your treatment field or treatment plan. The X-rays taken during the course of radiation treatment are not used to help measure your progress or response to the radiation. Rather, they are only used to ensure that the position and treatment arrangement is appropriate.

Your provider will examine you at least once a week. These visits may also be referred to as on-treatment visits, or an “OTV.” The examination will take place just before or after your treatment is administered. These examinations are important because they give your provider the opportunity to evaluate your physical condition, answer any questions that you may have, and plan and coordinate future treatments.

If you are having a problem, you should not wait until your next on-treatment examination. Instead, you should call the radiation department or your provider's office. You should be given a list of phone numbers to use for these types of situations. Your nurse will review your problem or concern and if he/she cannot help, will contact your provider. If there are any problems at night or on weekends, call the number you have been given to reach "the radiation oncologist-on-call."

End-Of-Treatment Visit

Once your radiation treatments have been completed, or a day or two before your last treatment, you will have a final visit with your provider. During this visit, your doctor will perform an examination and discuss follow-up care.

Follow-Up Care

In general, follow-up appointments occur between 2 and 6 weeks after the completion of radiation therapy. After that, your provider will see you on a regular basis. It is understood that you may be seeing many other providers, but it is important for your radiation team to participate in this follow-up process so that any radiation-related problems can be identified early and treated. Your entire cancer treatment team will consult with each other regarding future treatments and concerns. 

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