A novel 3D printing method for accurate anatomy replication in patient‐specific phantoms

Okkalidis, Nikiforos

doi:10.1002/mp.13154

Cited by 47 publications

(82 citation statements)

References 19 publications

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“…An in‐house developed software was used to control the 3D printer and send commands for the fabrication of the phantom. By controlling the filament extrusion rate it was possible to replicate a patient’s HU in a phantom as demonstrated in our previous work 7 . The calibration procedure comprised the 3D printing of a series of cubes with dimensions of 20 × 20 × 20 mm corresponding to a variety of extruded filament length values.…”

Section: Methodsmentioning

confidence: 99%

“…The calibration procedure comprised the 3D printing of a series of cubes with dimensions of 20 × 20 × 20 mm corresponding to a variety of extruded filament length values. The HU corresponding to that amount of filament were retrieved defining a 150 mm 2 region of interest (ROI) on the CT images of the cubes 7 . This calibration procedure was repeated for both filament materials with both extruders.…”

Section: Methodsmentioning

confidence: 99%

“…In our previous work, an improved method for the manufacturing of patient‐specific phantoms was presented, which involved controlling the filament extrusion rate of a fused deposition modeling (FDM) printer 7,8 . Using this technique, there was no need for manual contouring and exporting 3D models of a patient's anatomy, and consequently it minimized the preprocessing time and bypassed the need for skilled personnel.…”

Section: Introductionmentioning

confidence: 99%

“…The present study employed the FDM technology with commercially available soft tissue and bone equivelent materials and a new variable extrusion rate method 7,8 in combination with a non‐regular and non‐uniform printing pattern. The aim was the fabrication of an accurate patient‐specific skull phantom and was expected to adequately replicate soft and bone tissue both in HU range and in texture.…”

Section: Introductionmentioning

confidence: 99%

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Technical Note: Accurate replication of soft and bone tissues with 3D printing

Okkalidis

Marinakis²

2020

Medical Physics

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Purpose: The fabrication of a realistic patient-specific skull phantom employing for the first time a new filament extrusion rate method, for the accurate replication of soft and bone tissues both in Hounsfield Units (HU) range and in texture. Methods: An in-house developed software was used for the fabrication of the phantom taking into account all the HU of a patient's Computed Tomography (CT) images, replicating the organs voxelby-voxel without the need of a uniform three-dimensional printing pattern. Two commercially available materials were used; the polylactic acid (PLA) filament for the soft tissues, and a mixture of 50% of PLA and 50% of gravimetric powdered stone for the bone tissues. Additionally, a layer of small amounts of PLA were also extruded on the fabricated bones. Results: The replicated anatomy of the phantom was very close to the patient's one, achieving a similar range of HU without creating any air gaps and variations on the replicated HU, which are the main artifacts observed when a standard infill density and pattern is employed. The maximum measured HU values of the replicated bone tissues were at about 900. Conclusions: The results indicated an accurate replication of the soft tissues HU, and a significant improvement of the bone tissue HU replication. Further investigation on materials of high density in conjunction with the filament extrusion rate method may provide custom-made realistic phantoms for diagnostic and lower energy radiation such as in superficial, orthovoltage, and electron beam radiotherapy.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Technical Note: Accurate replication of soft and bone tissues with 3D printing

Okkalidis

Marinakis²

2020

Medical Physics

Self Cite

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“…In the latter, 3D printing has been used for fabrication of parts, fixtures, phantoms and sensors. [4][5][6][7][8][9][10][11] For instance, 3D printing was used to fabricate Magnetic Resonance Imaging (MRI) compatible components, 4 electroencephalogram (EEG) electrodes, 5 patient-specific phantoms for quality assurance (QA) including phantoms with variable radiological properties, [6][7][8][9][10] as well as immobilization devices 11 and patient-specific applicator holders for skin brachytherapy. 12,13 Modeling of tissues by 3D printing is growing, 1 although the radiological properties of 3D printing materials must be critically evaluated for QA or dosimetry applications in radiology or radiation oncology.…”

Section: Introductionmentioning

confidence: 99%

3D printing for rapid prototyping of low‐Z/density ionization chamber arrays

et al. 2019

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Purpose To explore 3D printing for rapid development of prototype thin slab low‐Z/density ionization chamber arrays viable for custom needs in radiotherapy dosimetry and quality assurance (QA). Materials and methods We designed and fabricated parallel plate ionization chambers and ionization chamber arrays using an off‐the‐shelf 3D printing equipment. Conductive components of the detectors were made of conductive polylactic acid (cPLA) and insulating components were made of acrylonitrile butadiene styrene (ABS). We characterized the detector responses using a Varian TrueBeam linac at 95 cm SSD in slab solid water phantom at 5 cm depth. We measured the current‐voltage (IV) curves, the response to different energy beam lines (2.5 MV, 6 MV, 6 MV FFF) for various dose rates and compared them to responses of a commercial Exradin A12 ionization chamber. We measured off‐axis ratio (OAR) for several small field static multi‐leaf collimators field sizes (0.5–3 cm) and compared them to OAR data obtained for commissioning of stereotactic radiotherapy. Results We identified the printing capability and the limitations of a low‐cost off‐the‐shelf 3D printer for rapid prototyping of detector arrays. The design of the array with sub‐millimeter size features conformed to the 3D printing capabilities. IV‐curve for the array showed a strong polarity effect (8%) due to the design. Results for the parallel plate and the array compared well with A12 chamber: monitor unit (MU) dependence for the array was within a few % and the response to different energy beam lines was within 1%. Off‐axis dose profiles measured with the array were comparable to dose profiles obtained in water tank and stereotactic diode after accounting for the size of the chambers. Dose error was within 2% at the center of the profile and slightly larger at the penumbra. Conclusions Rapid prototyping of ion chambers by means of low‐cost 3D printing is feasible with certain limitations in the design and spatial accuracy of the printed details.

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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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A novel 3D printing method for accurate anatomy replication in patient‐specific phantoms

Cited by 47 publications

References 19 publications

Technical Note: Accurate replication of soft and bone tissues with 3D printing

Technical Note: Accurate replication of soft and bone tissues with 3D printing

3D printing for rapid prototyping of low‐Z/density ionization chamber arrays

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

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