Tissue-mimicking phantoms for photoacoustic and ultrasonic imaging

In both photoacoustic (PA) and ultrasonic (US) imaging, overall image quality is influenced by the optical and acoustical properties of the medium. Consequently, with the increased use of combined PA and US (PAUS) imaging in preclinical and clinical applications, the ability to provide phantoms that are capable of mimicking desired properties of soft tissues is critical. To this end, gelatin-based phantoms were constructed with various additives to provide realistic acoustic and optical properties. Forty-micron, spherical silica particles were used to induce acoustic scattering, Intralipid® 20% IV fat emulsion was employed to enhance optical scattering and ultrasonic attenuation, while India Ink, Direct Red 81, and Evans blue dyes were utilized to achieve optical absorption typical of soft tissues. The following parameters were then measured in each phantom formulation: speed of sound, acoustic attenuation (from 6 to 22 MHz), acoustic backscatter coefficient (from 6 to 22 MHz), optical absorption (from 400 nm to 1300 nm), and optical scattering (from 400 nm to 1300 nm). Results from these measurements were then compared to similar measurements, which are offered by the literature, for various soft tissue types. Based on these comparisons, it was shown that a reasonably accurate tissue-mimicking phantom could be constructed using a gelatin base with the aforementioned additives. Thus, it is possible to construct a phantom that mimics specific tissue acoustical and/or optical properties for the purpose of PAUS imaging studies

Review of tissue simulating phantoms with controllable optical, mechanical and structural properties for use in optical coherence tomography

We review the development of phantoms for optical coherence tomography (OCT) designed to replicate the optical, mechanical and structural properties of a range of tissues. Such phantoms are a key requirement for the continued development of OCT techniques and applications. We focus on phantoms based on silicone, fibrin and poly(vinyl alcohol) cryogels (PVA-C), as we believe these materials hold the most promise for durable and accurate replication of tissue properties

Efeito de diferentes formas de aplicação de crioterapia no resfriamento superficial da pele de idosos: ensaio clínico randomizado cruzado

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Campus Araranguá, Programa de Pós-Graduação em Ciências da Reabilitação, Araranguá, 2022.Introdução: A crioterapia é um tratamento acessível e popular, utilizado para o tratamento de lesões dos tecidos moles, reduzindo a inflamação e dor e prevenindo edemas. Os estudos disponíveis, tratam especificamente adultos jovens e atletas, não estendendo seus achados à população idosa. Devido as alterações decorrentes da idade, muitos profissionais se preocupam em utilizar o gelo diretamente na pele, e alguns estudos já mostraram a ocorrência de lesões ou queimaduras de pele devido a aplicação incorreta de modalidades crioterápicas. Faz-se necessário, adequar os recursos terapêuticos para a população idosa, respeitando as diferenças fisiológicas e mantendo a efetividade dos recursos. Objetivo: Avaliar a crioterapia mais eficaz e de menor risco para a aplicação na pele de pessoas idosas. Desenho: ensaio clínico randomizado cruzado cego. Participantes: 18 mulheres idosas. Intervenção: As participantes foram submetidas às 3 modalidades crioterapêuticas: gelo puro, gelo envolto por toalha úmida e bolsa de gel, aplicadas na coxa direita. A temperatura superficial da pele foi aferida por um termômetro de infravermelho.de mira a laser. Desfecho: o desfecho primário foi a temperatura superficial da pele após as modalidades crioterapêuticas. O desfecho secundário foi a presença de lesões causadas pela crioterapia. Métodos: Na comparação entre os diferentes tipos de aplicação e tempos foi utilizada a análise de variância (ANOVA) para medidas repetidas. .Resultados: Na comparação entre as modalidades crioterapêuticas, o gelo envolto por toalha apresentou menor redução de temperatura quando comparada às modalidades gelo (p=0,08) e gel (p=0,07), já o gelo e gel não apresentaram diferenças significativas entre si (p=0,32). A bolsa de gel obteve maior resfriamento, entretanto 3 pacientes apresentaram lesão de pele causada pelo resfriamento. Os efeitos adversos da crioterapia foram observados somente na utilização do gel crioterápico em 3 das 18 pacientes. Conclusão: Podemos observar que o gelo e o gel foram mais eficazes para o resfriamento da pele. Mas, a bolsa de gel causou efeito adverso em alguns participantes do estudo. Assim a partir dos resultados do estudo é sugerido o uso do gelo para a aplicação da crioterapia em idosos.Abstract: Introduction: Cryotherapy is an affordable and popular treatment, used for treating soft tissue injuries, reducing inflammation and pain, and also preventing edema. Available studies specifically address young adults and athletes not extending their findings to the elderly population. Due to age-related changes, many professionals are concerned about using ice directly to the skin, and some studies have already shown the occurence of skin injuries or burns due to incorrect application of cryotherapy techniques. It is necessary to adapt the therapeutic resources for the elderly population, taking into account physiological differences in order to mantain the effectiveness of the treatment. Objective: To evaluate the most effective and lowest risk cryotherapy modality for application to the skin of elderly people. Design: blinded crossover randomized clinical trial. Participants: 18 elderly women. Ice interventions were launched in 3 cryotherapy modalities: pure ice, ice wrapped in a wet towel and a gel bag applied to the right thigh. The surface temperature of the skin was measured using an infrared thermometer. Outcome: The primary outcome was the measurement of skin surface temperature after each of the treatments. The secondary outcome was the finding of skin injuries caused by the cryotherapy. Methods: In the comparison between the different types of applications and times, analysis of variance (ANOVA) was used for repeated measures. Results: In the comparison between the cryotherapy modalities, the ice wrapped in a towel showed less temperature reduction when compared to the pure ice (p=0.08) and gel bag (p=0.07) treatments. On the other hand, pure ice and gel bag did not show significant differences between them (p=0.32). The gel bag caused greater cooling, however, 3 patients presented skin injuries caused by the treatment. Adverse effects of cryotherapy were observed only when using cryotherapy gel bag in 3 of the 18 patients. Conclusion: We can observe that gel bags were more effective for cooling the skin. Meantime, the study's gel bags did have an adverse effect on some participants. Thus, from the results of the study, the use of ice is indicated for the application of cryotherapy in the elderly