Characterization of novel 3D printed plastic scintillation dosimeters

Abstract

We propose a new methodology for the fabrication and evaluation of scintillating detector elements using a consumer grade fusion deposition modeling (FDM) 3D printer. In this study we performed a comprehensive investigation into both the effects of the 3D printing process on the scintillation light output of 3D printed plastic scintillation dosimeters (PSDs) and their associated dosimetric properties. Fabrication properties including print variability, layer thickness, anisotropy and extrusion temperature were assessed for 1 cm3 printed samples. We then examined the stability, dose linearity, dose rate proportionality, energy dependence and reproducibility of the 3D printed PSDs compared to benchmarks set by commercially available products. Experimental results indicate that the shape of the emission spectrum of the 3D printed PSDs do not show significant spectral differences when compared to the emission spectrum of the commercial sample. However, the magnitude of scintillation light output was found to be strongly dependent on the parameters of the fabrication process. Dosimetric testing indicates that the 3D printed PSDs share many desirable properties with current commercially available PSDs such as dose linearity, dose rate independence, energy independence in the MV range, repeatability, and stability. These results demonstrate that not only does 3D printing offer a new avenue for the production and manufacturing of PSDs but also allows for further investigation into the application of 3D printing in dosimetry. Such investigations could include options for 3D printed, patient-specific scintillating dosimeters that may be used as standalone dosimeters or incorporated into existing 3D printed patient devices (e.g. bolus or immobilization) used during the delivery of radiation therapy.

Camera‐based radiotherapy dosimetry using dual‐material 3D printed scintillator arrays

“…For comparison, our previous work also showed an average difference of 2.3% and a maximum of 4.0% between scintillators printed with identical print parameters. 1 However, identically designed arrays printed using the same print parameters demonstrate a similar distribution of element sensitivities. This suggests that there is potential for improvements to the printing process.…”

“…11 Recently our group has published the first example of characterizing an FDM 3D printed scintillator produced using a commercially available scintillating fiber. 1 We demonstrated that these 3D printed scintillators shared many desirable properties with their commercial counterparts such as dose linearity, dose rate independence, energy independence in the MV range, repeatability, and stability. This work builds on the previous publication by integrating techniques learned from 3D printing individual scintillating elements into the production of multi-element scintillating arrays and their wireless measurement using an sCMOS camera.…”

“…Material parameters for both the PLA and scintillating filaments were informed by our previous work and iterative testing. 1 Arrays were printed using a nozzle size of 0.4mm, layer thickness of 0.1mm, 100% infill density and a build plate temperature of 65 • C. The PLA was printed using a print temperature of 195 • C, linebased infill pattern and a print speed of 35mm/s with retractions enabled.…”

“…We hypothesized that thermal degradation of the polymer was responsible. 1 Printing vertically prevents the scintillators from being in contact with the heated build plate for the duration of the printing process limiting prolonged heating of the scintillators and potential reduction in light output.…”

“…Prior work with individual 3D printed scintillators demonstrates a directional dependence of light output. 1 The amount of light produced in each region of the active volume is uncertain, as it may be scattered or absorbed prior to exiting the surface aligned with the direction of the camera.As the array has no backing, this effect may be further complicated in the case of in-vivo measurements on patients. Natural differences in skin color between patients or changes in a given patient's skin pigmentation over the course of treatment (such as in the case of erythema) may result in different optical reflections into the scintillator.…”