Significance: A new concept of a biotissue phantom for terahertz (THz) biomedical applications is needed for reliable and long-term usage. Aim: We aimed to develop a new type of biotissue phantom without water content and with controllable THz optical properties by applying graphite powders into a polyvinyl chloride plastisol (PVCP) matrix and to give a numerical description to the THz optical properties of the phantoms using the Bruggeman model (BM) of the effective medium theory (EMT). Approach: The THz optical properties of graphite and the PVCP matrix were measured using THz time-domain spectroscopy, which works in the frequency range from 0.1 to 1 THz. Two phantoms with 10% and 12.5% graphite were fabricated to evaluate the feasibility of describing phantoms using the EMT. The EMT then was used to determine the concentration of graphite required to mimic the THz optical properties of human cancerous and healthy oral tissue. Results: The phantom with 16.7% of graphite has the similar THz optical properties as human cancerous oral tissue in the frequency range of 0.2 to 0.7 THz. The THz optical properties of the phantom with 21.9% of graphite are close to those of human healthy oral tissue in the bandwidth from 0.6 to 0.8 THz. Both the refractive index and absorption coefficient of the samples increase with an increase of graphite concentration. The BM of the EMT was used as the numerical model to describe the THz optical properties of the phantoms. The relative error of the BM for the refractive index estimation and the absorption coefficient is up to 4% and 8%, respectively. Conclusions: A water-free biotissue phantom that mimics the THz optical properties of human cancerous oral tissue was developed. With 21.9% of graphite, the phantom also mimics human healthy oral tissue in a narrow frequency range. The BM proved to be a suitable numerical model of the phantom.

中文翻译：

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基于聚氯乙烯塑料溶胶和石墨的太赫兹频率口腔癌组织模拟体模的研制

意义：可靠和长期使用需要用于太赫兹 (THz) 生物医学应用的生物组织体模的新概念。目的：我们旨在通过将石墨粉应用到聚氯乙烯塑料溶胶 (PVCP) 基质中，开发一种新型的无水和具有可控太赫兹光学特性的生物组织体模，并使用以下方法对体模的太赫兹光学特性进行数值描述有效介质理论（EMT）的布鲁格曼模型（BM）。方法：使用太赫兹时域光谱测量石墨和 PVCP 基体的太赫兹光学特性，该光谱在 0.1 至 1 THz 的频率范围内工作。制作了两个具有 10% 和 12.5% 石墨的幻影，以评估使用 EMT 描述幻影的可行性。然后使用 EMT 来确定模拟人类癌变和健康口腔组织的太赫兹光学特性所需的石墨浓度。结果：含有 16.7% 石墨的体模在 0.2 至 0.7 THz 的频率范围内具有与人类口腔癌组织相似的 THz 光学特性。在 0.6 至 0.8 THz 的带宽内，具有 21.9% 石墨的体模的太赫兹光学特性接近于人类健康口腔组织的太赫兹光学特性。样品的折射率和吸收系数都随着石墨浓度的增加而增加。EMT 的 BM 被用作数值模型来描述体模的太赫兹光学特性。BM 的折射率估计和吸收系数的相对误差分别高达 4% 和 8%。结论：开发了一种模拟人类口腔癌组织的太赫兹光学特性的无水生物组织体模。该体模含有 21.9% 的石墨，还能在较窄的频率范围内模拟人类健康的口腔组织。BM 被证明是一种合适的体模数值模型。