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

Brivio, Davide; Naumann, Louise; Albert, Steffen; Sajo, Erno; Zygmanski, Piotr

doi:10.1002/mp.13841

Cited by 3 publications

(4 citation statements)

References 20 publications

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“…In 2019, FDM 3D printing was used to produce a planar ionization chamber array using conductive polylactic acid (cPLA) and insulating components made of acrylonitrile butadiene styrene (ABS). 6 The array possessed a spatial resolution of 5 × 7 mm 2 and had a detector volume of 96 mm 3 . The rectangular array elements delivered comparable performance (within 2%) to a PTW diode detector under reference conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Even when using commercially designed dual‐material FDM 3D printers the quality and consistency of multi‐material prints are not guaranteed. Problems with material‐material adhesion, material mixing, and clogging of the print nozzles often result in poor print quality, low print success rates, and reduced dimensional accuracy 4–7 . This is particularly the case when printing with thermoplastic filaments doped with additional materials such as metal, wood, glass, and carbon fiber.…”

Section: Introductionmentioning

confidence: 99%

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

2023

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Purpose and objective: To describe a methodology for the dual-material fused deposition modeling (FDM) 3D printing of plastic scintillator arrays, to characterize their light output under irradiation using an sCMOS camera, and to establish a methodology for the dosimetric calibration of planar array geometries. Materials and methods:We have published an investigation into the fabrication and characterization of single element FDM printed scintillators intending to produce customizable dosimeters for radiation therapy applications. 1 This work builds on previous investigations by extending the concept to the production of a high-resolution (scintillating element size 3 × 3 × 3 mm 3 ) planar scintillator array. The array was fabricated using a BCN3D Epsilon W27 3D printer and composed of polylactic acid (PLA) filament and BCF-10 plastic scintillator. The array's response was initially characterized using a 20 × 20 cm 2 6 MV photon field with a source-to-surface (SSD) distance of 100 cm and the beam incident on the top of the array. The light signals emitted under irradiation were imaged using 200 ms exposures from a sCMOS camera positioned at the foot of the treatment couch (210 cm from the array). The collected images were then processed using a purpose-built software to correct known optical artefacts and determine the light output for each scintillating element. The light output was then corrected for element sensitivity and calibrated to dose using Monte Carlo simulations of the array and irradiation geometry based on the array's digital 3D print model. To assess the accuracy of the array calibration both a 3D beam and a clinical VMAT plan were delivered. Dose measurements using the calibrated array were then compared to EBT3 GAFChromic film and OSLD measurements, as well as Monte Carlo simulations and TPS calculations. Results: Our results establish the feasibility of dual-material 3D printing for the fabrication of custom plastic scintillator arrays. Assessment of the 3D printed scintillators response across each row of the array demonstrated a nonuniform response with an average percentage deviation from the mean of 2.1% ± 2.8%. This remains consistent with our previous work on individual 3D printed scintillators which showed an average difference of 2.3% and a maximum of 4.0% between identically printed scintillators. 1 Array dose measurements performed following calibration indicate difficulty in differentiating the scintillator response from ambient background light contamination at low doses (<20-25 cGy) and dose rates (≤100 MU/min). However, when analysis was restricted to exclude dose values less than 10% of the Monte Carlo simulated max dose the average absolute percentage dose difference between Monte Carlo simulation and array measurement was 5.3% ± 4.8% for the fixed beam delivery and 5.4% ± 5.2% for the VMAT delivery 1824

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

2023

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“…The simplicity of this design makes the array easy to fabricate and potentially low-cost. These features make REA an attractive candidate for integration into the accelerator beamline as a transmission detector for beam monitoring (Brivio et al 2019a, Albert et al 2020. Commercial detector arrays presently used in radiotherapy, such as pixelated ion chamber arrays or diode arrays, typically consist of thicker detector panels with a backbone layer for wiring of each detector element.…”

Section: Introductionmentioning

confidence: 99%

“…However, in REA the discrimination of radiation fields is achieved not via segmentation or angling (differential sensitivity to x-rays) but rather via the finite resistance of the collecting electrode. Localization of the readouts at the edges of REA outside of the irradiation beam is more like localization of readouts in ion chamber strip arrays (Brivio et al 2019a, Albert et al 2020 and in a segmented ion chamber detector (Han et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Resistive electrode array (REA) for radiotherapy beam monitoring and quality assurance

Zygmanski¹,

Lima²,

Liles³

et al. 2022

Phys. Med. Biol.

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We have developed a new type of detector array for monitoring of radiation beams in radiotherapy. The detector has parallel-plane architecture with multiple large-area uniform thin-film electrodes. At least one of the electrodes is resistive and has multiple signal readouts spread out along its perimeter. The integral dose deposited in the detector gives rise to multiple signals that depend on the distribution of radiation with respect to resistive electrode array (REA) geometry. The purpose of the present study was to experimentally determine basic detector response to MLC collimated x-ray fields. Two detector arrays have been characterized: circular and rectangular. The current and electrostatic potential distribution within the resistive electrode are governed by the Laplace and continuity equations with boundary conditions at the border with the readouts. Measurements for pencil beams showed that signal strength depends primarily on the distances between the location of the pencil beam and the readouts. Measurements for larger irregular MLC showed that signals as a function of time are quasi-linear with respect to MLC position and are proportional to the MLC area. Derivation of clinically relevant radiation beam parameters from REA signals, such as MLC position, MLC gap size and Monitor Unit per MLC segment relies on the detector response model with empirical model parameters. An approximate analytical detector response model was proposed and used to fit experiment data.

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