A feasibility study of using a 3D-printed tumor model scintillator to verify the energy absorbed to a tumor

The authors developed a volumetric dosimetry detector system using in-house 3D-printable plastic scintillator resins. Three tumor model scintillators (TMSs) were developed using magnetic resonance images of a tumor. The detector system consisted of a TMS, an optical fiber, a photomultiplier tube, and an electrometer. The background signal, including the Cherenkov lights generated in the optical fiber, was subtracted from the output signal. The system showed 2.1% instability when the TMS was reassembled. The system efficiencies in collecting lights for a given absorbed energy were determined by calibration at a secondary standard dosimetry laboratory (k(SSDL)) or by calibration using Monte Carlo simulations (k(sim)). The TMSs were irradiated in a Gamma Knife (R) Icon (TM) (Elekta AB, Stockholm, Sweden) following a treatment plan. The energies absorbed to the TMSs were measured and compared with a calculated value. While the measured energy determined with k(SSDL) was (5.84 +/- 3.56) % lower than the calculated value, the energy with k(sim) was (2.00 +/- 0.76) % higher. Although the TMS detector system worked reasonably well in measuring the absorbed energy to a tumor, further improvements in the calibration procedure and system stability are needed for the system to be accepted as a quality assurance tool. (C) 2021 Korean Nuclear Society, Published by Elsevier Korea LLC.