Thermochromic phantoms and paint to characterize and model image-guided thermal ablation and ablation devices: a review

Abstract

Heat-based local ablation techniques are effective treatments for specific oligometastatic and localized cancers and are being studied for their potential to induce immunogenic cell death and augment systemic immune responses to immunotherapies. The diverse technologies associated with thermal therapy have an unmet need for method development to enable device-specific experimentation, optimization, calibration and refinement of the parameter space to optimize therapeutic intent while minimizing side effects or risk to the patient. Quality assurance, training, or comparing thermal dose among different modalities or techniques using animal models is time and resource intensive. Therefore, the application and use of tissue mimicking thermosensitive, thermochromic liquid crystal and thermochromic paint phantom models may reduce costs and hurdles associated with animal use. Further, their homogenous composition may enable more precise assessment of ablative techniques. This review utilized SciFinder, Web of Science, PubMed and EMBASE to systematically evaluate the literature describing the background and applications of thermochromic liquid crystal, thermochromic paint and tissue-mimicking thermochromic phantoms used to characterize the thermal effects of ablation devices with a focus on facilitating their use across the medical device development life cycle. Graphical Abstract

Assessment of thermochromic phantoms for characterizing microwave ablation devices

“…The measurement mechanism of the system consists of a heating and a cooling phase. During the heating phase, one of the two needles is heated at a defined temperature T 0 for about 30 •m -3 ) displayed by the system are the output parameters that minimize the difference between T f and T 0 according to the least square method.…”

“…The thermochromic ink irreversibly changes color when exposed to temperatures in the range ~55 -70 °C for a few seconds/minutes, thus providing a means to evaluate the extent of ablation profiles after an ablative exposure. These thermo-chromic phantoms could provide a suitable tool for validation of applicator performance during translation of medical devices from academic/early-stage innovation labs to quality manufacturing systems, quality assurance of clinical devices, and for training of clinicians [26]. These phantoms have been employed for evaluating ablation profiles of focused ultrasound [27] , radiofrequency [28], and microwave ablation [29] systems.…”