Premium
3D printing for rapid prototyping of low‐Z/density ionization chamber arrays
Author(s) -
Brivio Davide,
Naumann Louise,
Albert Steffen,
Sajo Erno,
Zygmanski Piotr
Publication year - 2019
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1002/mp.13841
Subject(s) - ionization chamber , truebeam , materials science , imaging phantom , dosimetry , detector , linear particle accelerator , optics , beam (structure) , dose profile , monitor unit , ionization , optoelectronics , nuclear medicine , physics , medicine , ion , quantum mechanics
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.