Study on attenuation of 3D printing commercial filaments on standard X-ray beams for dosimetry and tissue equivalence

Objective To measure the monoenergetic x-ray linear attenuation coefficient, μ, of fused deposition modeling (FDM) colored 3D printing materials (ABS, PLAwhite, PLAorange, PET and NYLON), used as adipose, glandular or skin tissue substitutes for manufacturing physical breast phantoms. Approach Attenuation data (at 14, 18, 20, 24, 28, 30 and 36 keV) were acquired at Elettra synchrotron radiation facility, with step-wedge objects, using the Lambert-Beer law and a CCD imaging detector. Test objects were 3D printed using the Ultimaker 3 FDM printer. PMMA, Nylon-6 and high-density polyethylene step objects were also investigated for the validation of the proposed methodology. Printing uniformity was assessed via monoenergetic and polyenergetic imaging (32 kV, W/Rh). Main results Maximum absolute deviation of μ for PMMA, Nylon-6 and HD-PE was 5.0%, with reference to literature data. For ABS and NYLON, μ differed by less than 6.1% and 7.1% from that of adipose tissue, respectively; for PET and PLAorange the difference was less than 11.3% and 6.3% from glandular tissue, respectively. PLAorange is a good substitute of skin (differences from -9.4% to +1.2%). Hence, ABS and NYLON filaments are suitable adipose tissue substitutes, while PET and PLAorange mimick the glandular tissue. PLAwhite could be printed at less than 100% infill density for matching the attenuation of glandular tissue, using the measured density calibration curve. The printing mesh was observed for sample thicknesses less than 60 mm, imaged in the direction normal to the printing layers. Printing dimensional repeatability and reproducibility was less 1%. Significance For the first time was provided a first experimental determination of common 3D printing filament material for estimating μ at all energies in the range 14–36 keV, for their use in mammography, breast tomosynthesis and breast computed tomography investigations.

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Attenuation coefficient in the energy range 14–36 keV of 3D printing materials for physical breast phantoms

Mettivier

Sarno²,

Varallo³

et al. 2022

“…The conventional phantoms used in radiology are made with acrylic or ceramic materials providing results of limited accuracy and being an expensive solution. With the emergence of 3D printing technology, it has been shown that phantoms can obtain realistic features by first replicating adequately the human's morphology and the shape of organs (Shuh-Ping and Ching-Jung, 2004, Court et al 2010, Ehler et al 2014, Gear et al 2016, Robinson et al 2016, Woliner-van der Weg et al 2016, and further emulating appropriate hounsfield units (HU), attenuation coefficients and electron densities of various tissues (Filippou and Tsoumpas, 2018, Ivanov et al 2018, Tino et al 2019, McGarry et al 2020, Ma et al 2021, Savi et al 2021. However, there are still several areas of the current 3D printing technologies and associated materials that should be further investigated.…”

Section: Introductionmentioning

confidence: 99%

“…Τhe radiological replication of human anatomy using a 3D printing technology is inseparably associated with the nature of the employed materials, which affect the x-ray characteristics of the replicated tissues (Filippou and Tsoumpas, 2018, Ivanov et al 2018, McGarry et al 2020, O'Reilly et al 2020, Ma et al 2021, Savi et al 2021. For instance, the materials used for photo-curing technologies are restricted by their own nature, i.e.…”

Section: Introductionmentioning

confidence: 99%

3D printing methods for radiological anthropomorphic phantoms

Okkalidis¹

2022

Three dimensional (3D) printing technology has been widely evaluated for the fabrication of various anthropomorphic phantoms during the last couple of decades. The demand for such high quality phantoms is constantly rising and gaining an ever-increasing interest. Although, in a short time 3D printing technology provided phantoms with more realistic features when compared to the previous conventional methods, there are still several aspects to be explored. One of these aspects is the further development of the current 3D printing methods and software devoted for radiological applications. The current 3D printing software and methods usually employ 3D models, while the direct association of medical images with the 3D printing process is needed in order to provide results of higher accuracy and closer to the actual tissues’ texture. Another aspect of high importance is the development of suitable printing materials. Ideally, those materials should be able to emulate the entire range of soft and bone tissues, while still matching the human’s anatomy. Five types of 3D printing methods have been mainly investigated so far: a) solidification of photo-curing materials; b) deposition of melted plastic materials; c) printing paper-based phantoms with radiopaque ink; d) melting or binding plastic powder; and e) bio-printing. From the first and second category, polymer jetting technology and Fused Filament Fabrication (FFF), also known as Fused Deposition Modelling (FDM), are the most promising technologies for the fulfilment of the requirements of realistic and radiologically equivalent anthropomorphic phantoms. Another interesting approach is the fabrication of radiopaque paper-based phantoms using inkjet printers. Although, this may provide phantoms of high accuracy, the utilized materials during the fabrication process are restricted to inks doped with various contrast materials. A similar condition applies to the polymer jetting technology, which despite being quite fast and very accurate, the utilized materials are restricted to those capable of polymerization. The situation is better for FFF/FDM 3D printers, since various compositions of plastic filaments with external substances can be produced conveniently. Although, the speed and accuracy of this 3D printing method is lower compared to the others, the relatively low-cost, constantly improving resolution, sufficient printing volume and plethora of materials are quite promising for the creation of human size heterogeneous phantoms and their adaptation to the treatment procedures of patients in the current health systems.

“…3D printing technologies, which have been already evaluated for the fabrication of anthropomorphic phantoms are: (a) solidifying resin by using photo-curing technology (Gear et al 2016), (b) melting powder with a strong source of light (Mayer et al 2015, Mainprize et al 2018, Mainprize et al 2020, (c) depositing melted amounts of filaments in layers, known as fused deposition modelling (FDM) or fused filament fabrication (Madamesila et al 2016) and (d) jetting technology, which includes paper and doped ink printing (Jahnke et al 2017, Ikejimba et al 2017a, Jahnke et al 2019. Among the printing technologies used for production of radiological phantoms, the FDM printing demonstrates advantage in respect to the lower budget for equipment and 3D materials as well as its rapid processes in setup and control the 3D printer (Craft and Howell 2017, Hamedani et al 2018, Bliznakova 2020, Savi et al 2020, Cano-Vicent et al 2021, Savi et al 2021. FDM technology was chosen for manufacturing of torso phantoms (Craft and Howell 2017), a finger phantom (Savi et al 2020) and dosimetry phantoms for evaluating the effects of newly produced implants (Goodall et al 2021), as well as pelvic phantoms for optimisation of preoperative CT scans (Hamedani et al 2018), and chest, neck, head phantoms (Kamomae et al 2017, Okkalidis 2018, Okkalidis and Marinakis 2020 and lung tissues (Mei et al 2022).…”

Section: Introductionmentioning

confidence: 99%

A voxel-by-voxel method for mixing two filaments during a 3D printing process for soft-tissue replication in an anthropomorphic breast phantom

Okkalidis¹,

Bliznakova²

2022

Objective: In this study, a novel voxel-by-voxel mixing method is presented, according to which two filaments of different material are combined during the 3D printing process. Approach: In our approach, two types of filaments were used for the replication of soft-tissues, a polylactic acid (PLA) filament and a polypropylene (PP) filament. A custom-made software was used, while a series of breast patient CT scan images were directly associated to the 3D printing process. Each phantom´s layer was printed twice, once with the PLA filament and a second time with the PP filament. For each material, the filament extrusion rate was controlled voxel-by-voxel and was based on the HU of the imported CT images. The phantom was scanned at clinical CT, breast tomosynthesis and Micro CT facilities, as the major processing was performed on data from the CT. A side by side comparison between patient´s and phantom´s CT slices by means of profile and histogram comparison was accomplished. Further, in case of profile comparison, the Pearson´s coefficients were calculated. Main results: The visual assessment of the distribution of the glandular tissue in the CT slices of the printed breast anatomy showed high degree of radiological similarity to the corresponding patient´s glandular distribution. The profile plots´ comparison showed that the Hounsfield Units (HU) of the replicated and original patient soft tissues match adequately. In overall, the Pearson´s coefficients were above 0.91, suggesting a close match of the CT images of the phantom with those of the patient. The overall HU were close in terms of HU ranges. The HU mean, median and standard deviation of the original and the phantom CT slices were -149, -167, ±65, and -121, -130, ±91, respectively. Significance: The results suggest that the proposed methodology is appropriate for manufacturing of anthropomorphic soft tissue phantoms for x-ray imaging and dosimetry purposes, since it may offer an accurate replication of these tissues.