A calibration CT mini‐lung‐phantom created by 3‐D printing and subtractive manufacturing

Abstract

We describe the creation and characterization of a calibration CT mini‐lung‐phantom incorporating simulated airways and ground‐glass densities. Ten duplicate mini‐lung‐phantoms with Three‐Dimensional (3‐D) printed tubes simulating airways and gradated density polyurethane foam blocks were designed and built. Dimensional accuracy and CT numbers were measured using micro‐CT and clinical CT scanners. Micro‐CT images of airway tubes demonstrated an average dimensional variation of 0.038 mm from nominal values. The five different densities of incorporated foam blocks, simulating ground‐glass, showed mean CT numbers (±standard deviation) of −897.0 ± 1.5, −844.1 ± 1.5, −774.1 ± 2.6, −695.3 ± 1.6, and −351.0 ± 3.7 HU, respectively. Three‐Dimensional printing and subtractive manufacturing enabled rapid, cost‐effective production of ground‐truth calibration mini‐lung‐phantoms with low inter‐sample variation that can be scanned simultaneously with the patient undergoing lung quantitative CT.

Methodology for computed tomography characterization of commercially available 3D printing materials for use in radiology/radiation oncology

“…Increased knowledge of material types can aid in these applications and create designs using materials that are more suitable for the need than a standard PLA filament. In radiotherapy, additive manufacturing has already been used to create compensators, phantoms, shielding, and other innovative solutions to improve standard practices 5,23 . In phantom production, the need to become more tissue equivalent is being explored and this examination of commercially available materials will allow for radiological properties to be replicated more thoroughly 21 .…”

“…In radiotherapy, additive manufacturing has already been used to create compensators, phantoms, shielding, and other innovative solutions to improve standard practices. 5 , 23 In phantom production, the need to become more tissue equivalent is being explored and this examination of commercially available materials will allow for radiological properties to be replicated more thoroughly. 21 The replication of tissues for use in dosimetry has been successfully used in rapid prototyping within radiotherapy.…”

“…4 Moreover, phantoms have been created using a combination of 3D printing and traditional subtractive manufacturing. 5 The combination of materials within a phantom also expands the options for mimicking areas of patients in a more accurate way for use in image calibration and dosimetry. In addition to phantoms, additive manufacturing can improve many other aspects of radiotherapy.3D-printed forms for shielding have shown to be useful in protecting organs at risk in both patient-specific ways as well as generic prints that can be made as needed in-house.…”

“…For example, with additive manufacturing tissue‐ and bone‐equivalent material have been used in a single phantom 4 . Moreover, phantoms have been created using a combination of 3D printing and traditional subtractive manufacturing 5 . The combination of materials within a phantom also expands the options for mimicking areas of patients in a more accurate way for use in image calibration and dosimetry.…”

High Resolution Propagation-based Lung Imaging at Clinically Relevant X-Ray Dose Levels

“…To date computed tomography (CT) is the primary modality for the imaging of the lung parenchyma by exploiting the intrinsic differences in the x-ray absorption between gas filled alveolar spaces and the pulmonary parenchymal tissue. The individual microstructures of lung parenchyma, such as pulmonary alveoli, interalveolar septa, alveolar ducts or acini lie beyond the spatial resolution capabilities of absorption-based CT, when clinically acceptable radiation dose levels in the range of few mGy are used 1 . In absorption-based CT an increase in resolution demands an enhancement of the applied x-ray dose.…”