Photoacoustic-based thermal image formation and optimization using an evolutionary genetic algorithm

Abstract

For improved efficiency and security in heat application during hyperthermia, it is important to monitor tissue temperature during treatments. Photoacoustic (PA) pressure wave amplitude has a temperature dependence given by the Gruenesein parameter. Consequently, changes in PA signal amplitude carry information about temperature variation in tissue. Therefore, PA has been proposed as an imaging technique to monitor temperature during hyperthermia. However, no studies have compared the performance of different algorithms to generate PA-based thermal images. Methods: Here, four methods to estimate variations in PA signal amplitude for thermal image formation were investigated: peak-to-peak, integral of the modulus, autocorrelation of the maximum value, and energy of the signal. Changes in PA signal amplitude were evaluated using a 1-D window moving across the entire image. PA images were acquired for temperatures ranging from 36 o C to 41 o C using a phantom immersed in a temperature controlled thermal bath. Results: The results demonstrated that imaging processing parameters and methods involved in tracking variations in PA signal amplitude drastically affected the sensitivity and accuracy of thermal images formation. The sensitivity fluctuated more than 20% across the different methods and parameters used. After optimizing the parameters to generate the thermal images using an evolutionary genetic algorithm (GA), the percentage of pixels within the acceptable error was improved, in average, by 7.5%. Conclusion: Optimization of processing parameters using GA could increase the accuracy of measurement for this experimental setup and improve quality of PA-based thermal images.

Application of Binary Genetic Algorithm for Holographic Vascular Mimicking Phantom Reconstruction

“…The PA images of the tissuemimicking phantom, which are fabricated with a gelatin/agar powder and submerged in a water tank, are used to perform the experiments. They notified that the usage of an evolutionary GA to optimize the parameters of thermal images is improved the error on average by 7.5% [32]. Although Uliana et al obtained phantom images with PA, the system used is quite more complex than the LSDHM system.…”

Multiangle Long-Axis Lateral Illumination Photoacoustic Imaging Using Linear Array Transducer

“…Formaldehyde in a weight concentration of 0.5% of gelatin mass was added to increase stiffness and melting temperature. The phantom was manufactured according to the description in [ 55 , 56 ].…”

Magnetic particles in motion: magneto-motive imaging and sensing

“…After verifying accumulation of photomagnetic nanoparticles at the tumor via MPA, hyperthermic cell death can be induced with light, magnets, or a combination of both. Thermal ultrasound or thermal PA imaging can provide temperature maps to assure the tumor reaches the desired treatment temperature 176 , 177 . Following initial treatment, MM-UE can monitor cell death or tissue ablation based on changes in elastic properties.…”