Proton Therapy Comparative Planning

Background

 

 

Radiotherapy plays an important part in the management of cancer in Australia. Half of all cancer patients will require radiotherapy as part of their disease management. This is most commonly delivered with X-Rays, which have been used therapeutically since the late 19th century. X-ray beams are effective in delivering high doses to the tumour cells they target, but unfortunately also give some of the dose to all healthy tissues in their path.

In the 1950s, proton beams emerged as a new option for radiotherapy. Protons are heavy charged particles and have a unique way of depositing their energy. Rather than causing damage through their whole path, they deposit most of their energy at a distinct depth before stopping completely. When protons are used for radiation therapy this effect allows the largest dose to be delivered where it is needed – in the tumour – with minimal dose and damage to the surrounding healthy tissues.

Early clinical use of proton therapy has focused on paediatric tumours, where damage to healthy tissues can result in long term side effects and growth problems, and adult tumours of the head and neck and central nervous system areas, where tumours are adjacent to organs with distinct radiation tolerances. A comparison of radiotherapy treatment plans created with X-ray intensity modulated radiotherapy (IMRT) and intensity modulated proton therapy (IMPT) for a paediatric tumour of the spinal cord is shown in Figure 1. The reduction of dose delivered to healthy tissues made possible with proton therapy is demonstrated.

X-ray intensity modulated radiotherapy (IMRT) and intensity modulated proton therapy (IMPT) for a paediatric tumour of the spinal cord
Figure 1. Radiotherapy treatment plans created with IMRT (left), IMPT (middle) and the difference between IMRT and IMPT (right). The red region in the image on the right signifies more dose being delivered with IMRT.

While proton therapy has experienced expansion in the United States, Europe and Eastern Asia in the past two decades, there is no clinical facility operating in the Southern Hemisphere. RANZCR has endorsed that particle therapy must be available to patients in Australia and New Zealand, however at this point in time patients who will benefit from proton therapy have to travel overseas to gain access. Funding is available through the Australian Medical Treatment Overseas Programme, following referral from the RANZCR Particle Therapy Referral Committee. Comparative planning of proton and photon treatment will help ensure that the referral decision is evidence based and objective.

The Royal Adelaide Hospital (RAH) team have been working on proton planning with multiple treatment planning systems since 2014. The team is happy to be able to offer a national comparative planning service to assist in the decision making and referral of patients overseas for proton therapy treatment.

Aims

  1. Produce photon and proton plans for comparative purposes, for patients where a clinical benefit may be predicted from protons.
  2. Inform the decision making process for referral of patients overseas for proton therapy.
  3. Provide evidence to support the application for government funding for overseas treatment.
  4. Build proton planning experience among RAH team and collect local comparative data.

Planning Process

Contact RAH team via email to inform of incoming patient (see “Contacts”).

A member of the RAH proton team will email a request form. Please return ASAP with the patient history and relevant imaging reports, correspondence etc (can be sent via email).

The DICOM files for the planning CT and other scans used for contouring (e.g. MRI) should be obtained by the referring institution. Instructions will be provided on how to encrypt these files and upload them to a secure server.

The file transfer process uses the same ports as web browsing, so it will not be blocked by local hospital network firewalls.

Standard turnaround time is 2 weeks from receipt of request form and DICOM data. Shorter planning time can be negotiated at initial request if clinically necessary.
RAH will complete photon and proton plans as per request form. Comparison can be made with a photon plan from the referring institution, if DICOM plan and dose data is also sent on disk.
Plan comparison will be returned as a PDF via email, with the following:

  • Spreadsheet/PlanIQ comparison of dose volume statistics
  • Screenshots of Pinnacle dosimetry, DVH and accumulated dose images
  • Planning report

Ethics, Ownership of Data & Intellectual Property

Ethics approval for this project has been obtained from the Human Research Ethics Committee of the RAH.

The patients’ original radiotherapy planning data will remain the property of the requesting institution, however the RAH will retain de-identified copies in a database that may be used for research and publication purposes. The referring Radiation Oncologist is responsible for ensuring the patient’s consent.

The intellectual property created during the comparative planning process will be owned by the RAH and the requesting institution according to the relevant policies and/or procedures of these institutions.

Comparative plans are produced by the RAH to help guide clinical decision making by the radiation oncology staff of the referring institution. Plans are produced in a research environment and are not to be used for treatment. The RAH accepts no responsibility for clinical decisions or outcomes.

Contacts

Radiation Oncologists: Hien Le
Joe Chang
Radiotherapy Planning: Ray Dalfsen
Medical Physics: Scott Penfold