Interview with Jennifer O'Daniel, Ph.D
At the American College of Radiation Oncology (ACRO) Meeting lunch symposium, we had the pleasure to listen to speaker Jennifer O'Daniel, Ph.D., DABR, Assistant Professor of Radiation Physics in the Department of Radiation Oncology of Duke University Medical Center, talking about "Advances in Radiotherapy Quality Assurance Techniques". Following the lunch, we asked her some questions about At Treatment Verification and we hope you may find her responses insightful.
Q: In your presentation, you talked about gamma index vs 3D dose. What should a radiation oncologist look for and why?
A: I recommend that the radiation oncologist and the qualified medical physicist communicate to reach a common understanding on (1) what quality assurance measurements are being done for complex plans, in a general sense at least, and (2) how accurately those results predict what is happening to the patient. QA techniques using 3D dose distributions are typically more representative of what dose is actually being delivered to the patient than are gamma index techniques.
Q: How can this help to improve cancer treatments?
A: Just because a computer can model a beautiful dose distribution does not mean that (1) the dose model is correct and (2) the radiation device is capable of delivering the plan. The more complex the treatment delivery, the more likely problems are to occur. Delivery techniques are only getting more complex as technology progresses. We need accurate QA techniques to keep up with this complexity. If we cannot deliver the plans as the computer tells us, our patients' clinical responses will suffer.
Q: You also mentioned Adaptive Radiation Therapy. Can you explain how it works and in your opinion, what role a daily dose measurement could play in this type of therapy?
A: In traditional radiation therapy, we use a single snapshot of the patient, typically their planning CT scan, to determine the radiation plan for the entire treatment. Adaptive Radiation Therapy uses additional information to adapt the treatment. This can be as simple as daily 2D planar imaging to improve alignment, or as complex as taking a daily cone-beam CT scan, modifying the plan based on that day's anatomy, and immediately delivering it. Performing QA for quickly changing plans is a challenge. In-vivo transmission detectors would allow for an easy yet thorough daily check of a complex adaptive plan.
Q: What does a daily dose measurement mean for the patient, clinic and radiation oncologist? How can it help you to "give as high a dose as possible to the tumor while giving as little as possible to the surrounding organs"?
A: A daily dose measurement provides additional independent assurance that the linear accelerator is functioning properly, as well as further data to track down and quickly resolve any issues that occur. For example, output is measured once in the morning before treatment delivery starts. If it drifts over the course of the day, daily dose monitoring would catch the change. Anything that improves the accuracy of machine performance will improve the overall radiotherapy treatment.