Design of an anthropomorphic PET phantom with elastic lungs and respiration modeling

Abstract

Purpose Respiratory motion during positron emission tomography (PET) scans can be a major detriment to image quality in oncological imaging. The impact of motion on lesion quantification and detectability can be assessed using phantoms with realistic anatomy representation and motion modeling. In this work, we develop an anthropomorphic phantom for PET imaging that combines anatomic fidelity and a realistic breathing mechanism with deformable lungs. Methods We start from a previously developed anatomically accurate but static phantom of a human torso, and add elastic lungs with a highly controllable actuation mechanism which replicates the physics of breathing. The space outside the lungs is filled with a radioactive water solution. To maintain anatomical accuracy and realistic gamma ray attenuation in the torso, all motion mechanisms and actuators are positioned outside of the phantom compartment. The actuation mechanism can produce custom respiratory waveforms with breathing rates up to 25 breaths per minute and tidal volumes up to 1200 mL. Results Several tests were performed to validate the performance of the phantom assembly, in which the phantom was filled with water and given respiratory waveforms to execute. All parts demonstrated expected performance. Force requirements were not exceeded and no leaks were detected, although continued use of the phantom is required to evaluate wear. The motion of the lungs was determined to be within a reasonable realistic range. Conclusions The full mechanical design is described in this paper, as well as a software application with graphical user interface which was developed to plan and visualize respiratory patterns. Both are available online as open source files. The developed phantom will facilitate future work in evaluating the impact of respiratory motion on lesion quantification and detectability in clinical practice.

Robotic system for magnetic resonance imaging‐guided focused ultrasound treatment of thyroid nodules

“…However, the ABS material that was employed for the development of the air‐filled trachea is an extremely rigid material that does not reflect the mechanical strength of the human trachea. As evidenced in the literature, resin 3D‐printed with polyjet technology, 85,86 silicone tubes, 87 polymethylmethacrylate material, 88 breathing tubes, 89 and various flexible 3D‐printed resin materials 90 have been formerly employed for mimicking the trachea in previously developed phantoms dedicated to certain applications. In this regard, in future studies, the trachea component of the composite thyroid phantom could be replaced with one of the aforementioned materials, with silicone tubes 87 and flexible 3D‐printed resin materials 90 being the most excellent candidates for mimicking the mechanical strength of the human trachea 87,90 .…”

Technical note: Low‐cost MR‐compatible pneumatic respiratory organ motion simulator for the development of MR‐guided thermal therapy

“…The respiratory motion simulator was designed based on the fabrication methods and components used in earlier approaches. 9,13,17,18 Our design improves on them by offering a low-cost and simple fabrication process. As shown in Figure 1, the respiratory motion simulator consists of two main parts: (1) motion actuator placed outside the MRI scanner; (2) motion phantom placed inside the MRI scanner.…”

“…Several custom-made respiratory phantoms have been developed to evaluate motion compensation in MRI techniques. 9,13,17,18 For instance, Maier-Hein et al developed a respiratory liver motion simulator for validating image-guided tumor biopsy procedures. 17 The simulator provided a human torso model, and an artificial diaphragm was mounted, and it simulated the liver movement by using a lung ventilator.…”

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.…”

“…Motion artefacts are common in molecular imaging of the thorax due to respiratory motion, and decrease the detectability and hamper quantification. Black et al [ 71 ] developed a functional anthropomorphic lung phantom using 3D-printed molds. At the time of writing, there is no information available on the resulting images and quantification.…”