Design and implementation of a prototype head and neck phantom for the performance evaluation of gamma imaging systems

Abstract

BackgroundA prototype anthropomorphic head and neck phantom has been designed to simulate the adult head and neck anatomy including some internal organs and tissues of interest, such as thyroid gland and sentinel lymph nodes (SLNs). The design of the head and neck phantom includes an inner jig holding the simulated SLNs and thyroid gland. The thyroid gland structure was manufactured using three-dimensional (3D) printing taking into consideration the morphology and shape of a healthy adult thyroid gland.ResultThe head and neck phantom was employed to simulate a situation where there are four SLNs distributed at two different vertical levels and at two depths within the neck. Contrast to noise ratio (CNR) calculations were performed for the detected SLNs at an 80 mm distance between both pinhole collimators (0.5 and 1.0 mm diameters) and the surface of the head and neck phantom with a 100 s acquisition time. The recorded CNR values for the simulated SLNs are higher when the hybrid gamma camera (HGC) was fitted with the 1.0 mm diameter pinhole collimator. For instance, the recorded CNR values for the superficially simulated SLN (15 mm depth) containing 0.1 MBq of 99mTc using 0.5 and 1.0 mm diameter pinhole collimators are 6.48 and 16.42, respectively (~87% difference).Gamma and hybrid optical images were acquired using the HGC for the simulated thyroid gland. The count profiles through the middle of the simulated thyroid gland images provided by both pinhole collimators were obtained. The HGC could clearly differentiate the individual peaks of both thyroid lobes in the gamma image produced by the 0.5-mm pinhole collimator. In contrast, the recorded count profile for the acquired image using the 1.0-mm-diameter pinhole collimator showed broader peaks for both lobes, reflecting the degradation of the spatial resolution with increasing the diameter of the pinhole collimator.ConclusionsThis anthropomorphic head and neck phantom provides a valuable tool for assessing the imaging ability of gamma cameras used for imaging the head and neck region. The standardisation of test phantoms for SFOV gamma systems will provide an opportunity to collect data across various medical centres. The phantom described is cost effective, reproducible, flexible and anatomically representative.

Recent advances on the development of phantoms using 3D printing for imaging with CT, MRI, PET, SPECT, and ultrasound

“…Kasten et al Gallas et al and Niebuhr et al also created an opening on the phantom's compartments and filled it with a solution. Alqahatni et al poured water solution mixed with 99m Tc inside the printed thyroid gland, which had two syringe filling valves on top. Also, Tran‐Gia et al used a syringe to fill the radioactive solutions into the 3D‐printed kidney phantom via a small 3D‐printed tube.…”

Absolute Quantification in Diagnostic SPECT/CT: The Phantom Premise

“…This technology makes it possible to produce almost any shape conceivable with relative ease. Several studies using 3D-printed phantoms in nuclear medicine have recently been published Table 1 for applications in the following anatomical regions: the abdomen [ 60 , 61 , 62 ], pancreas and kidneys [ 63 ], kidneys [ 64 , 65 ], brain [ 66 , 67 , 68 ], head and neck [ 69 ], systolic and diastolic heart [ 70 ], lungs [ 71 ], and patient-derived lesion shapes [ 11 ]. With current technology, anthropomorphic phantoms can be 3D-printed with a precision in the µm-range, well beyond the sub-millimeter resolution of CT or MRI used to develop these anatomical models.…”

“…The head and neck region is very complex where tiny structures are densely packed, yet this region is often imaged in the context of sentinel lymph node (SLN) detection or thyroid disease. A phantom was designed and tested by Alqahtani et al [ 69 ]; however, the analysis was aimed at assessing the imaging ability of gamma cameras for distinguishing different SLNs and the thyroid, and no evaluation of the absolute quantification was performed.…”

Validation of Monte Carlo 131I radiopharmaceutical dosimetry workflow using a 3D‐printed anthropomorphic head and neck phantom

“…A prototype head and neck phantom was described by Alqahtani et al. in which the performance of gamma imaging systems was evaluated, but the study did not extend to dosimetry 43 . In these studies, results have generally indicated that anthropomorphic phantoms account for heterogeneities that are not present in traditional nuclear medicine phantoms and are often more accurate than non‐anthropomorphic phantoms.…”

“…A prototype head and neck phantom was described by Alqahtani et al in which the performance of gamma imaging systems was evaluated, but the study did not extend to dosimetry. 43 In these studies, results have generally indicated that anthropomorphic phantoms account for heterogeneities that are not present in traditional nuclear medicine phantoms and are often more accurate than non-anthropomorphic phantoms. 3D-printed anthropomorphic head and neck phantoms that account for the changing contour of the head and neck region and the heterogeneous material composition in the patient have not been investigated.…”