Quasi-simultaneous 3D printing of muscle-, lung- and bone-equivalent media: a proof-of-concept study

Kairn, Tanya; Zahrani, Mohammed; Cassim, Naasiha; Livingstone, Alex; Charles, Paul; Crowe, Scott

doi:10.1007/s13246-020-00864-5

Cited by 37 publications

(48 citation statements)

References 33 publications

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“…The ρ determined by measurement of mass and volume was 1.08 g/ cm 3 , which was similarly close to unity and similar to water, and which also confirmed that the bone-like density identified in the kV CT images resulted from photoelectric enhancement in the small proportion of radiopacifier in the sample (see Table 1) and did not accurately reflect the true ρ of the sample.…”

Section: Radiological Characterisationmentioning

confidence: 59%

“…Elemental composition as percentage by mass (%wt) were determined using molecular formula and molecular weight. The bone cement was added to the material definition file required by EGSnrc using this elemental composition and a default density of 1.08 g/cm 3 , directly calculated from the measured mass and apparent volume in CT image of the physical sample.…”

Section: Monte Carlo Simulationsmentioning

confidence: 99%

“…The radiopacifiers can therefore cause potential issues for radiotherapy treatment planning, delivery and quality assurance, because radiopacified materials that appear as dense as bone in kV images actually behave as though closer to unit density when irradiated using MV treatment beams. The impact of barium sulfate contrast agents on dose calculations has been discussed with respect to 3D printed radiotherapy quality assurance phantoms [3], contrasted bolus [4] and intravenous CT contrast agents [5], but has not previously been addressed in regard to bone cements used in cranioplasty.…”

Section: Introductionmentioning

confidence: 99%

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Impact of radiopacified bone cement on radiotherapy dose calculation

Crowe

Bennett

Lathouras

et al. 2020

Physics and Imaging in Radiation Oncology

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Background and purpose: Radiopacifiers are introduced to bone cements to provide the appearance of bone in kilovoltage (kV) radiographic images. For higher energy megavoltage (MV) radiotherapy treatment beams, however, these radiopacifiers do not cause a bone-like perturbation of dose. This study therefore aimed to determine the impact of the barium-contrasted plastic-based cement materials on radiotherapy dose calculations. Materials and methods: The radiological properties of a physical sample of bone cement were characterised by computed tomography (CT) imaging and transmission measurements. Monte Carlo simulations of percentage depth-dose profiles were performed to determine the possible dose error for MV treatment beams. Dose differences were then investigated for clinical volumetric modulated radiotherapy treatment plans, with and without density overrides applied. Results: Differences of up to 7% were observed at the downstream interface of a 0.6 cm thick bone cement layer, compared to bone. Differences in planning target volume dose-volume metrics varied between −0.5% and 2.0%. Conclusion: Before planning radiotherapy treatments for patients who have undergone cranioplasty, every effort should be made to identify whether a radiopacified bone cement has been implanted. Density overrides should be applied to minimise dose calculation errors, whenever bone cement is used.

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Section: Radiological Characterisationmentioning

confidence: 59%

Section: Monte Carlo Simulationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Impact of radiopacified bone cement on radiotherapy dose calculation

Crowe

Bennett

Lathouras

et al. 2020

Physics and Imaging in Radiation Oncology

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“…These methods have allowed muscle and lower density tissues such as lung to be replicated, however, until recently the ability to replicate bone, or high‐density tissues, has proven difficult 6,7 . In addition, earlier studies have often demonstrated the development of individual components of a phantom, often using multiple materials and techniques, before combining them to produce a final phantom 6,9‐11 …”

Section: Introductionmentioning

confidence: 99%

Investigation of the effects of spinal surgical implants on radiotherapy dosimetry: A study of 3D printed phantoms

et al. 2021

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Purpose The use of three‐dimensional (3D) printing to develop custom phantoms for dosimetric studies in radiotherapy is increasing. The process allows production of phantoms designed to evaluated specific geometries, patients, or patient groups with a defining feature. The ability to print bone‐equivalent phantoms has, however, proved challenging. The purpose of this work was to 3D print a series of three similar spine phantoms containing no surgical implants, implants made of titanium, and implants made of carbon fiber, for future dosimetric and imaging studies. Phantoms were evaluated for (a) tissue and bone equivalence, (b) geometric accuracy compared to design, and (c) similarity to one another. Methods Sample blocks of PLA, HIPS, and StoneFil PLA‐concrete with different infill densities were printed to evaluate tissue and bone equivalence. The samples were used to develop CT to physical (PD) and effective relative electron density (REDeff) conversion curves and define the settings for printing the phantoms. CT scans of the printed phantoms were obtained to assess the geometry and densities achieved. Mean distance to agreement (MDA) and DICE coefficient (DSC) values were calculated between contours defining the different materials, obtained from design and like phantom modules. HU values were used to determine PD and REDeff and subsequently evaluate tissue and bone equivalence. Results Sample objects showed linear relationships between HU and both PD and REDeff for both PLA and StoneFil. The PD and REDeff of the objects calculated using clinical CT conversion curves were not accurate and custom conversion curves were required. PLA printed with 90% infill density was found to have a PD of 1.11 ± 0.03 g.cm−3 and REDeff of 1.04 ± 0.02 and selected for tissue‐ equivalent phantom elements. StoneFil printed with 100% infill density showed a PD of 1.35 ± 0.03 g.cm−3 and REDeff of 1.24 ± 0.04 and was selected for bone‐equivalent elements. Upon evaluation of the final phantoms, the PLA elements displayed PD in the range of 1.10 ± 0.03 g.cm−3–1.13 ± 0.03 g.cm−3 and REDeff in the range of 1.02 ± 0.03–1.06 ± 0.03. The StoneFil elements showed PD in the range of 1.43 ± 0.04 g.cm−3–1.46 ± 0.04 g.cm−3 and REDeff in the range of 1.31 ± 0.04–1.33 ± 0.04. The PLA phantom elements were shown to have MDA of ≤1.00 mm and DSC of ≥0.95 compared to design, and ≤0.48 mm and ≥0.91 compared like modules. The StoneFil elements displayed MDA values of ≤0.44 mm and DSC of ≥0.98 compared to design and ≤0.43 mm and ≥0.92 compared like modules. Conclusions Phantoms which were radiologically equivalent to tissue and bone were produced with a high level of similarity to design and even higher level of similarity of one another. When used in conjunction with the derived CT to PD or REDeff conversion curves they are suitable for evaluating the effects of spinal surgical implants of varying material of construction.

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“…Thus, we are enabling a cost-effective manufacturing process that generates realistic models of human lungs without sacrificing spatial and contrast resolution.Over the last decade, several approaches have been proposed to produce clinically applicable CT phantoms. Kairn et al introduced a method to generate a patient-based lung phantom20 . They segmented CT images of the lung into three different regions and produced a tissue equivalent lung phantom.…”

mentioning

confidence: 99%

Three-dimensional printing of patient-specific lung phantoms for CT imaging: emulating lung tissue with accurate attenuation profiles and textures

Mei

Geagan

Roshkovan

et al. 2021

Preprint

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Purpose: Phantoms are a basic tool for assessing and verifying performance in CT research and clinical practice. Patient-based realistic lung phantoms accurately representing textures and densities are essential in developing and evaluating novel CT hardware and software. This study introduces PixelPrint, a 3D printing solution to create patient-based lung phantoms with accurate attenuation profiles and textures. Methods: PixelPrint, a software tool, was developed to convert Patient DICOM images directly into printer instructions (G-code). The density was modeled as the ratio of filament to voxel volume to emulate attenuation profiles for each voxel. A calibration phantom was designed to determine the mapping between filament line width and Hounsfield Units (HU) within the range of human lungs. For evaluation of PixelPrint, a phantom based on a human lung slice was manufactured and scanned with the same CT scanner and protocol used for the patient scan. Density and geometrical accuracy between phantom and patient CT data was evaluated for various anatomical features in the lung. Results: For the calibration phantom, measured mean Hounsfield units show a very high level of linear correlation with respect to the utilized filament line widths, (r > 0.999). Qualitatively, the CT image of the patient-based phantom closely resembles the original CT image both in texture and contrast levels, with clearly visible vascular and parenchymal structures. Regions-of-interest (ROIs) comparing attenuation illustrated differences below 15 HU. Manual size measurements performed by an experienced thoracic radiologist reveal a high degree of geometrical correlation of details between identical patient and phantom features, with differences smaller than the intrinsic spatial resolution of the scans. Conclusion: The present study demonstrates the feasibility of 3D printed patient-based lung phantoms with accurate organ geometry, image texture, and attenuation profiles. PixelPrint will enable applications in the research and development of CT technology, including further development in radiomics.

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Quasi-simultaneous 3D printing of muscle-, lung- and bone-equivalent media: a proof-of-concept study

Cited by 37 publications

References 33 publications

Impact of radiopacified bone cement on radiotherapy dose calculation

Impact of radiopacified bone cement on radiotherapy dose calculation

Investigation of the effects of spinal surgical implants on radiotherapy dosimetry: A study of 3D printed phantoms

Three-dimensional printing of patient-specific lung phantoms for CT imaging: emulating lung tissue with accurate attenuation profiles and textures

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