Design and Production of Two-Piece Thyroid-Neck Phantom by the Concurrent Use of Epoxy Resin and Poly(Methyl Methacrylate) Soft Tissue Equivalent Materials

Abstract

The aim of this report is to present a new two-piece thyroid-neck phantom produced by the concurrent use of epoxy resin and poly(methyl methacrylate) (PMMA: plexiglass) soft tissue equivalent materials. Accordingly, mass attenuation coefficients of the epoxy resin and the plexiglass compounds were obtained from simulation (NIST XCOM 3.1) and measurements (practical dosimetry) and compared to those related to human soft tissue (ICRU 44). The thyroid-neck phantom and thyroid gland dimensions were derived from scientific references and the atlas of human anatomy, respectively. The thyroid phantom was designed by CATIA V5R16 software and produced by the epoxy resin compound by three-dimensional printer. Other organs were designed by ProNest software and made by the plexiglass sheets by CNC laser cutting machine. The mass attenuation coefficients for the epoxy resin (50 keV- 20 MeV) and the plexiglass (0-20 MeV) were comparable to human soft tissue (ICRU 44), all with standard relative deviation beneath 5%. In addition, the SPECT images indicated the similarity between human thyroid tissue and its phantom. In conclusion, this study proves the feasibility and reliability of epoxy resin application in the production of two-piece thyroid-neck phantom. This phantom can be applied in the calibration of gamma camera systems, dosimetry and gamma spectrometry in the nuclear medicine field.

A Neck-Thyroid Phantom with Small Sizes of Thyroid Remnants for Postsurgical I-123 and I-131 SPECT/CT Imaging

“…In previous studies, either water containers with hollow inserts down to 5 mL were used to simulate remnants [8][9][10] or neck-thyroid phantoms with hollow thyroid glands with or without other anatomical structures [12][13][14][15] were used in Tc-99m and I-131 SPECT studies. In this study, a neck-thyroid phantom with different sizes of small (0.5-10 mL) thyroid remnants at clinically relevant positions, including all relevant anatomical structures, and able to simulate different background-to-remnant activity ratios, was developed to specifically study postsurgical thyroid-remnant SPECT/CT imaging procedures.…”

“…Physical phantoms with thyroid glands have been developed and evaluated in previous studies [12][13][14][15]. In particular, solid cylindrical phantoms, with and without other structures such as the trachea, esophagus and cylindrical cervical spine, and a detachable section of the thyroid gland have been developed and evaluated using Tc-99m or I-131 SPECT images [14,15].…”

3D printing of fillable individual thyroid replicas based on nuclear medicine DICOM data used as phantoms for gamma probe calibration

“…Common calibration methods comprise point sources (1 mL fillable spheres) or small filled bottles in a neck phantom (Biodex Medical Systems, Shirley, NY, USA) [8,26]. However, since these means are only partially close to the anatomical characteristics of the individual patients, there is a clear need for the development of organ-specific anthropomorphic replicas [7,27]. Prospectively advanced 3D printers, which became available very recently, may enable considerable improvement by the use of several materials of different absorption properties, which allows the fabrication of more complex replicas [28,29].…”

“…However, standardized definitions for thyroid gamma probes calibration procedures are lacking and there can be large differences between the single facilities in clinical routine. Besides commonly used point sources (small capsules or spheres, usually 1 mL in volume), organ-specifically shaped phantoms gain in importance [7]. It may be beneficial that the shape of the calibration reference is as close as possible to the actual organ structure [8].…”