Proton Therapy at Johns Hopkins: What to Expect

Our entire team of cancer specialists understands that facing a cancer diagnosis is difficult, and we want to make your treatment as stress-free as possible. Here is what to expect:

Initial Consultation

Your first visit will be a consultation with cancer specialists. You will meet with a team of cancer experts who will recommend a treatment plan. The plan may include:

  • Proton therapy alone
  • Proton therapy combined with other cancer treatments
  • Another treatment option that better addresses your unique situation

Our experts will discuss possible short-term and long-term side effects of each treatment so you can make an informed decision about your care.

At the end of this visit, you will be asked to read and sign a consent form to acknowledge that you were informed of your treatment options and potential side effects, and that you reviewed other important information with your doctor. This consent allows us to schedule a proton treatment simulation and to begin the radiation process if proton therapy is recommended.

If informed consent is not obtained at the time of consultation, an additional visit to obtain consent will be required before the simulation.

Simulation Appointment

Before your first treatment at the Johns Hopkins Proton Therapy Center, we will schedule a simulation appointment to help us plan. You will receive a computerized tomography (CT) scan while lying in the same position you will be in for treatment. In some cases, you may get a magnetic resonance imaging (MRI) or positron emission tomography (PET) scan on the same day.

The CT scan lasts less than 30 seconds. We take pictures of your treatment position and place several small, permanent marks on the skin to line you up for each treatment session. Your doctor or nurse will let you know if there are instructions you should follow before the simulation, such as fasting or drinking fluid or a contrast agent.

Before leaving your simulation appointment, you will get a date and time for your first treatment.


Your treatment will typically begin within 10 days of the initial consultation. Medical dosimetrists and physicists, directed by the treating physician, will use your CT images to develop a unique treatment plan for you.

During treatment, you will lie on a table in the exact position that was determined during the simulation. The radiation therapist will be in the next room controlling a 360-degree-rotating machine called a gantry, which will deliver proton radiation as prescribed in your treatment plan.

You may see lights pointed at you. These lights are safe — they help the therapist line you up to precisely target the tumor.

The treatments are broken down into short, daily sessions, typically lasting 30 minutes each. Most of this time is spent setting up for the predefined treatment position and conducting more imaging scans.

Once the treatment is underway, you will meet weekly with your doctor and a nurse who will review the treatment plan with you, address any treatment-related side effects and answer your questions. This appointment is part of your treatment plan — you do not need to schedule separate appointments for this weekly visit.

You may also receive additional weekly CT scans during the course of your proton treatment to ensure accuracy.

Arriving for Treatments

Please plan to arrive before the scheduled appointment time so that you can change clothes and be ready for the therapist. If you will be late or need to miss or change an appointment, please call your radiation therapist.

We always do our best to stay on schedule, but providing the best care is our first priority. Given the uncertainty of patient care in a busy department, please understand that unanticipated delays are likely.

Please expect to be in our department for as long as 1.5 hours on each day of treatment.

Appointment Hours

Appointments are normally available 7:30 a.m. to 3:30 p.m., but we are flexible if they need to be scheduled later.


Patients receiving radiation treatment are given a courtesy pass for spaces in the parking garage that are designated for our patients.

Follow-Up Care

Your treatment plan may include medications, dietary adjustments, family counseling and other components that our team will help coordinate. When the series of proton therapy sessions is completed, we will schedule regular follow-ups to monitor the treatment’s effectiveness and adjust our strategy to give you the best cancer therapy.