Name: Vacuuming and Pouring of the Phantom Material Samples into the Mold
Uploaded: 2023-06-16T12:20:00
Duration: 1 min 38 s
Description: Watch this Scientific Journal Video about Vacuuming and Pouring of the Phantom Material Samples into the Mold at JoVE.com

vacuuming and pouring of the phantom material samples into the mold

制造稳定的、具有生物相关性的体模材料

Establishing the precision and accuracy of novel optical imaging biomarkers through technical validation1,2 is paramount to ensuring their successful implementation in clinical practice. To achieve this, technical validation studies frequently employ durable physical phantoms, which facilitate inter-instrument performance assessment and routine quality control. For widespread use of a phantom material in research and clinical translation, a simple, highly reproducible fabrication protocol is required. An ideal biophotonic phantom material should include the following properties3: (1) independently tunable properties within biologically relevant ranges; (2) mechanical robustness; (3) long-term stability; (4) flexibility in geometry and architecture; (5) safe handling; (6) widely available ingredients that can be purchased from standard scientific suppliers; and (7) low cost. At present, biophotonic applications lack a standardized protocol for a widely accepted phantom material that fulfils the outlined requirements and also includes tunable acoustic properties for hybrid applications, such as photoacoustic imaging (PAI).
Biologically relevant phantom materials targeted for combined optical and acoustic applications include hydrogels4,5, polyvinyl alcohol (PVA)6,7,8,9, and polyvinyl chloride plastisol (PVCP)10,11,12,13,14,15,16. However, these materials are characterized by certain limitations that restrict their application as a stable phantom material. Hydrogels, for example, are prone to dehydration, mechanical damage, and bacterial ingrowth, limiting their shelf life17,18,19. The addition of chemicals can increase the longevity, but common preservatives, such as formaldehyde20 or benzalkonium chloride21, are hazardous and require cautionary measures during handling. Additionally, targets containing water-soluble dyes can diffuse within the base material if not encapsulated. PVA cryogels are characterized by a higher longevity and structural robustness, but their preparation process involves long freeze-thaw cycles22. This can limit the independent tunability of acoustic and optical parameters23 and-if slightly varied-can lead to inhomogeneities6, thereby compromising reproducibility. Moreover, the diffusion of dyes from inclusions has been observed after 1 year13. PVCP has a complex fabrication process that includes high temperatures of up to 180-220 &#176;C13,14,24,25. PVCP also suffers from a lack of a supply chain with scientific suppliers26 and can contain plasticizers based on phthalates, which may cause reproductive and developmental harm27, making them controlled substances in some countries.
Copolymer-in-oil compositions, such as gel wax28,29,30,31 or blends based on thermoplastic styrenic elastomers32,33,34,35,36, exhibit good longitudinal stability and feature tissue-like acoustic and optical properties31,35,36,37, thereby having high potential as a durable phantom candidate in multimodal applications. Additionally, this class of material is cost-effective, non-water absorbing, non-toxic, and biologically inert35,38. The speed of sound c(f) and acoustic attenuation coefficient &#945;(f) can be tuned in a biologically relevant range (Table 1) by variation of the polymer concentration33,35,39, whilst optical absorption &#181;a(&#955;) and reduced scattering &#181;s&#39;(&#955;) coefficients can be primarily varied by the addition of oil-soluble dyes or titanium dioxide (TiO2)39, respectively.
Here, a simple, easy-to-follow protocol is presented for the creation of durable copolymer-in-oil phantoms suitable for use in optical, ultrasound, or photoacoustic device calibration. All ingredients have defined Chemical Abstract Service (CAS) numbers and are readily available from standard scientific suppliers. Potential difficulties in the fabrication procedure are highlighted and ways to overcome them are presented. Whilst the protocol allows the fabrication of materials with a range of acoustic and optical properties, the presented protocol yields a material with a speed of sound of ~1,481 m&#183;s-1, aligning with the speed of sound of water at room temperature (20 &#176;C)40. This value was selected as a neutral standard for representing the wide range of existing tissue properties (Table 1), allowing the establishment of a consistent and reliable reference point for comparison. By providing this detailed protocol, we aim to broaden the uptake and manufacturing reproducibility of this promising phantom material type, thereby facilitating biophotonic, acoustic, and photoacoustic validation studies and supporting routine quality control in preclinical and clinical imaging applications.

作者聚焦：用于光学和声学成像的稳定 Phantom 材料  

用于光学和声学成像的稳定幻影材料

Our research is focused on developing new imaging modalities for early cancer detection. In this study in particular, we focused on developing a stable test object, or also called phantom, to validate imaging modalities based on light and/or sound. Different resources have been proposed to develop tissue mimicking materials in the acoustic optical regimen.For example, PVA, hydrogels, polyurethane, or PVCP. This study focuses on a promising new material type based on core polyman oil composition, which overcomes many of the tunability and stability challenges. The field of biomedical optics covers a wide range of imaging modalities that can be applied to some of the key challenges facing medicine today.Many of the all optical imaging modalities are relatively depth limited, but we can also couple light with sound through the photoacoustic effect to take advantage of some of the depth penetration benefits of ultrasound. Photoacoustic imaging has shown promise in a wide range of clinical trials, from imaging inflammation to cancer diagnosis. However, quantitative performance assessment remains challenging due to a lack of available phantom materials that can accurately mimic the optical and acoustic properties of tissue and remain stable over time.Many new optical and photoacoustic imaging systems are being developed, but we lack a standardized reference phantom to validate those systems and to compare their performance. Our material is a promising candidate to fill this gap and support further development and translation of these exciting new techniques into the clinic. In the future, we would like to focus on creating more anatomically realistic phantom designs and architectures that are suitable to evaluate the performance of different system configurations.For example, microscopic, mesoscopic and macroscopic systems, which have different geometries and spatial resolutions.

Watch this Scientific Journal Video about Vacuuming and Pouring of the Phantom Material Samples into the Mold at JoVE.com

Vacuuming and Pouring of the Phantom Material Samples into the Mold  

抽真空并将虚拟材料样品倒入模具中

首先，将装有均匀混合、光滑且均匀的幻影材料溶液的热烧杯放入真空室中。在最低真空设置下抽真空样品两到三分钟。使用金属刮刀清除表面上积聚的任何气泡。如果气泡仍然存在，请重新加热混合物并重复抽真空步骤，直到完全去除气泡。对于形状复杂的模具，在浇注前在模具上涂上一层薄薄的油。戴上耐热手套，使用足够的防护设备，并小心地将溶液倒入合适的模具中，不要引入任何气泡。倒入后，使用金属刮刀快速去除样品顶部的任何气泡。让溶液在室温下凝固过夜。为光声成像创建了三种具有代表性的模型材料设计，针对具有不同光学照明和声学检测几何形状的不同系统设计。成功的程序实现了平稳、均匀的模型材料制备，没有气泡、杂质或伪影。气泡去除不充分和基础组分的不均匀混合导致所得光声图像的不均匀性。

Research

JoVE Journal

Medicine

Vacuuming and Pouring of the Phantom Material Samples into the Mold

A Stable Phantom Material for Optical and Acoustic Imaging

Establishing tissue-mimicking biophotonic phantom materials that provide long-term stability are imperative to enable the comparison of biomedical imaging ...