Author: Nema Bassiri, Kristen A. Duke, Neil A. Kirby, Thomas Wilson Klender, Christien Kluwe, Niko Papanikolaou, Holly Paschal, Karl H. Rasmussen, Daniel L. Saenz, Michelle de Oliveira 👨🔬
Affiliation: Miami Cancer Institute, University of Texas HSC San Antonio, UT Health San Antonio 🌍
Purpose: Determine the practical usability for three phantoms to be used with the ExacTrac Dynamic thermal imaging system. Thermal-guided imaging can be used for inter and intra motion management, patient safety, and treatment accuracy by tracking real-time temperature changes, however traditional phantoms may not be appropriate, as they are typically used for radiographic imaging.
Methods: QA recommendations were informed by NIST Technical Note 1630, which evaluates thermal imaging quality based on metrics like thermal sensitivity, spatial resolution, and field of view. A 3D-printed anthropomorphic phantom, ceramic phantom, and traditional solid-water anthropomorphic phantom were heated to 145 degrees Fahrenheit in a blanket warmer to determine baseline measurement evaluations. Each phantom's thermal retention was tested with imaging data analyzed using ExacTrac Dynamic Thermal Imaging system.
Results: Initial findings revealed variable thermal retention in phantoms and challenges with reflective surfaces. The hollow ceramic phantom exhibited the fastest cooling time, maintaining a reasonable temperature for patient setup for 10 minutes. In contrast, the 3D-printed anthropomorphic phantom retained a usable temperature for 60 minutes following a 30-minute cooldown on the treatment table. The solid-water anthropomorphic phantom retained a usable temperature for 30 minutes after a 20-minute cool down period. However, its performance highlighted the need to increase camera sensitivity to darker tone, as dead space along surfaces not directly perpendicular to the thermal camera’s view rendered it unusable. Preliminary results also emphasized the importance of determining color gradients for temperature correlation, system limits, and improved phantom setups that better mimic clinical conditions.
Conclusion: This project highlights that some QA equipment may be more suited for thermal camera measurements than traditional devices. Thermal imaging brings a new set of challenges that are historically not seen in radiation therapy. New equipment and methods need to be developed to ensure accuracy and patient safety.