When a decision is made to move forward with proton therapy and insurance is approved, we begin the treatment planning process. While many people may have the same disease type, no two cancers are the same. Indiana University Health Proton Therapy Center will customize your treatment specifically for you.

Treatment planning can take anywhere from two to four weeks and is dependent on the complexity and/or urgency of your treatment plan. While your plan is being created, this is a good time for you to explore your housing options, make travel arrangements, and get personal matters in order before starting treatment.

Preliminary Scans

For some treatment areas (primarily neurologically based or complex cases), a preliminary set of CT scans and MRIs may be ordered prior to treatment planning.

Fiducial Markers

Depending on the treatment site, radiographic positioning fiducial markers may be surgically implanted. Fiducials are needed in certain cases to help visualize tumors and to aide in accurately positioning the patient for treatment. For example, the prostate cannot be visualized with imaging X-rays in the treatment room. We can reference the fiducial to know where to direct the proton beam and deliver precision treatment.

This is generally an outpatient procedure that is not performed at Indiana University Health Proton Therapy Center; however, our staff members schedule and coordinate these appointments.

• For dental, skull, and spine fiducials, appointments are scheduled with one of the following groups
  • Neurosurgical Clinic of Bloomington (procedure performed at  Bloomington Hospital)
  • Riley Hospital for Children in Indianapolis
  • Indianapolis Neurosurgical Group in Indianapolis
  • Alejandra, Haddad, DDS in Bloomington
• For prostate seed markers, we commonly use the Indiana University School of Medicine, Department of Urology in Indianapolis
• For some head and neck patients, we may need dental bite blocks, which will be determined after physician’s review. We typically order one of the following:
  • A dentist bite block (created by an outside provider and selection is based on tumor type and location).
  • A bite block (created on site).
  • A commercially-made bite block.

Immobilization Devices

We also commonly make custom devices for positioning purposes which immobilizes patients for treatment. Immobilization devices minimize movement and to help provide fast reproducible positioning. These include masks (used when treating head and neck area), body molds (used for treating the prostate), and mouth pieces which are typically made onsite at Indiana University Health Proton Therapy Center.

Planning CT Scan

Once fiducial markers are in place and your immobilization device(s) are made, we will perform a planning CT scan. Typically previous CT scans cannot be used for planning because they were neither completed in the proposed treatment position nor with proton treatment devices. It is imperative that your CT scan matches your daily treatment position. Indiana University Health Proton Therapy Center treatment planning staff members will use the scan data to create your custom treatment plan. This scan will help define the treatment area, the location of implanted markers, and other anatomical structures.

Most CT scans will be completed at our facility; however, there are times when a CT may be scheduled at an outside facility.

For prostate patients, a rectal balloon will be inserted prior to scanning. The rectal balloon pushes the rectal wall down and pushes the bladder up, thus supporting the prostate in position to reduce movement. This process helps us reduce the dose to surrounding organs.

Developing Your Treatment Prescription and Plan

Using computer software, your scans will be used to plan your treatment area. Your physician will outline the area to be treated and denote important structures to avoid. The physician will write a dose prescription for the treatment volume with limiting doses for other structures. For the majority of our prostate patients, the prescription is 44 treatments. For all other conditions, the number of treatments you will receive is dependent on your individual case. 

A member of our dosimetry team will begin the planning phase. The dosimetrist creates a custom plan to deliver the proton beams from different directions in an effort to maximize dose to the treatment area and minimize dose to important structures. A custom computer-generated treatment plan will be produced based on the physician’s prescription.

We will then determine how many fields (number of angles/positions) that the proton beam will be directed. Prostate patients tend to have plans for two fields (one treatment from the left side and one from the right side). For all other treatment plans, fields can vary anywhere from one to six fields – or perhaps more – depending on the case.

Finally, your plan is reviewed and approved by your radiation oncologist.

Developing Beam-Shaping Devices

Once your plan is ready, custom shielding devices used to shape the beam to the precise treatment area and to block the proton beam from treating normal tissue are made at the IU Cyclotron Facility.

• The aperture is a heavy, solid brass cylinder with a specially designed opening to match the profile of the proposed treatment area. It is contoured to the exact shape of the target volume. The aperture shapes the proton beam up and down and left to right (X and Y axes). The beam cannot penetrate through the solid part of the brass and is only directed through the opening.
• The compensator is a custom LuciteTM that modifies the shape of the beam and contours the depth (Z axis) of the treatment area. The compensator’s center is carved out to match the prescribed dosage for proton delivery.

Custom apertures and compensators are developed for each field.

Verification Simulation (V-Sim)

The final step before beginning treatment is your V-Sim appointment. This is a “dry run” of your treatment to confirm planning, positioning, and treatment devices before delivering treatment. Typically you will have your V-Sim a day or two before starting treatment.

A radiation therapist (staff members who administer the treatments) or a therapy assistant will bring you into the treatment room and position you in your CT-scanned position. We verify your positioning of the treatment in relation to the proton beam, confirm sizes of the beam-shaping devices; and make sure that you are as comfortable as possible in your immobilization device. We mock up every step in your treatment, with the exception of beam delivery.

A V-Sim appointment typically lasts 30 to 60 minutes. If all goes well, you will be scheduled to start treatments, typically within two days. If modifications need to be made, your actual start date will be determined based on the proposed changes.