UJF-Grenoble 1/CNRS/TIMC-IMAG UMR 5525, Grenoble, France.
Med Phys. 2012 Apr;39(4):2031-41. doi: 10.1118/1.3692179.
Phantoms are a vital step for the preliminary validation of new image-guided procedures. In this paper, the authors present a deformable prostate phantom for use with multimodal imaging (end-fire or side-fire ultrasound, CT and MRI) and more specifically for transperineal or transrectal needle-insertion procedures. It is made of soft polyvinyl chloride (PVC) plastic and includes a prostate, a perineum, a rectum, a soft periprostatic surrounding and embedded targets for image registration and needle-targeting. Its main particularity is its realistic deformability upon manipulation.
After a detailed manufacturing description, the imaging and mechanical characteristics of the phantom are described and evaluated. First, the speed of sound and stress-strain relationship of the PVC material used in the phantom are described, followed by an analysis of its storage, imaging, needle-insertion force, and deformability characteristics.
The average speed of sound in the phantom was measured to be 1380 ± 20 m/s, while the stress-strain relationship was found to be viscoelastic and in the range of typical prostatic tissues. The mechanical and imaging characteristics of the phantom were found to remain stable at cooler storage temperatures. The phantom had clearly distinguishable morphology in all three imaging modalities, with embedded targets that could be precisely segmented, resulting in an average US-CT rigid registration error of 0.66 mm. The mobility of the phantom prostate upon needle insertion was between 2 and 4 mm, with rotations between 0° and 2°, about the US probe head.
The phantom's characteristics compare favorably with in vitro and in vivo measurements found in the literature. The authors believe that this realistic phantom could be of use to researchers studying new needle-based prostate diagnosis and therapy techniques.
体模是新的图像引导程序初步验证的重要步骤。本文作者介绍了一种可用于多模态成像（端射或侧射超声、CT 和 MRI）的可变形前列腺体模，特别是用于经会阴或经直肠针插入程序。它由软聚氯乙烯（PVC）塑料制成，包括前列腺、会阴、直肠、前列腺周围软组织和用于图像配准和针靶向的嵌入式目标。其主要特点是在操作时具有逼真的可变形性。
在详细描述制造过程后，描述并评估了体模的成像和机械特性。首先，描述了体模中使用的 PVC 材料的声速和应力-应变关系，然后分析了其存储、成像、针插入力和变形特性。
测量体模中的平均声速为 1380±20 m/s，而应力-应变关系被发现是粘弹性的，处于典型前列腺组织的范围内。体模的机械和成像特性在较冷的存储温度下保持稳定。体模在所有三种成像模式下都具有明显可分辨的形态，嵌入的目标可以精确分割，导致 US-CT 刚性配准误差的平均值为 0.66 mm。在插入针时，体模前列腺的移动性在 2 到 4 毫米之间，围绕 US 探头的旋转角度在 0°到 2°之间。
体模的特性与文献中发现的体外和体内测量值相当。作者认为，这种逼真的体模可以为研究新的基于针的前列腺诊断和治疗技术的研究人员提供帮助。
