To validate and implement Monte Carlo simulation using PRIMO code as a tool for checking the credibility of measurements in LINAC initial commissioning and routine Quality Assurance (QA). Relative and absolute doses of 6 MV photon beam from TrueBeam STx Varian Linear Accelerator (LINAC) were simulated and validated with experimental measurement, Analytical Anisotropic Algorithm (AAA) calculation, and golden beam. Varian phase-space files were imported to the PRIMO code and four blocks of jaws were simulated to determine the field size of the photon beam. Water phantom was modeled in the PRIMO code with water equivalent density. Golden beam data, experimental measurement, and AAA calculation results were imported to PRIMO code for gamma comparison. PRIMO simulations of Percentage Depth Dose (PDD) and in-plane beam profiles had good agreement with experimental measurements, AAA calculations and golden beam. However, PRIMO simulations of cross-plane beam profiles have a better agreement with AAA calculation and golden beam than the experimental measurement. Furthermore, PRIMO simulations of absolute dose agreed well with experimental results with ±0.8% uncertainty. The PRIMO code has good accuracy and is appropriate for use as a tool to check the credibility of beam scanning and output measurement in initial commissioning and routine QA.

Brain–computer interfaces (BCIs) are essential in assistive technologies to restore mobility in individuals with motor impairments. Although electroencephalography (EEG)-based brain-controlled wheelchairs have been extensively studied, most tongue-controlled systems rely on physical tongue movements, intraoral devices, or limited offline commands, which reduces the usability and comfort. This study introduces an EEG-based tongue motor imagery (MI) BCI for intuitive and entirely mental wheelchair control. By leveraging preserved motor function and the cortical representation of the tongue, the system enables natural four-directional control through imagined tongue movements. Six imagined tongue actions—touching the left and right mouth corners, the upper and lower lips, and producing left and right cheek bulges—were designed to elicit alpha-band event-related desynchronization (ERD) patterns over the tongue motor cortex. EEG data were collected from 15 healthy participants using a 14-channel consumer-grade EMOTIV EPOC X headset. Alpha-band ERD features were extracted and classified using linear discriminant analysis, support vector machine, naïve Bayes, and artificial neural networks (ANNs). Simpler command sets yielded the highest accuracy: two-class tasks achieved 76.19%, while the performance decreased with increasing task complexity. The ANN achieved superior results in multi-class scenarios. The proposed tongue MI method offers initial support for developing a BCI control strategy for assistive technology; however, further improvements in classification techniques, user training, and real-time validation are needed to improve the robustness and practical usability.

Penelitian ini bertujuan membandingkan hasil simulasi Monte Carlo menggunakan perangkat lunak PRIMO dengan hasil pengukuran eksperimen pada proses QA berkas foton Linear Accelerator (LINAC) Varian Clinac CX energi 6 MV berdasarkan parameter Percentage Depth Dose (PDD), dose profile, dan indeks gamma. Pengukuran distribusi dosis dilakukan menggunakan fantom air pada konfigurasi Source to Surface Distance (SSD) 100 cm dengan ukuran lapangan (4×4) cm², (10×10) cm², dan (40×40) cm². Simulasi Monte Carlo dilakukan menggunakan perangkat lunak PRIMO dengan memodelkan geometri kepala LINAC Varian Clinac CX serta fantom air sesuai dengan kondisi eksperimen. Hasil simulasi dan pengukuran dianalisis melalui kurva PDD, dose profile, serta evaluasi kuantitatif menggunakan indeks gamma dengan kriteria toleransi 2%/2 mm. Hasil penelitian menunjukkan bahwa kurva PDD hasil simulasi memiliki kesesuaian yang baik terhadap hasil pengukuran. Nilai Gamma Passing Rate (GPR) diperoleh sebesar 97,98% untuk lapangan (4×4) cm², 97,43% untuk lapangan 10×10 cm², dan 87% untuk lapangan (40×40) cm². Penurunan kesesuaian pada lapangan (40×40) cm2 dipengaruhi oleh peningkatan kontribusi hamburan lateral. Hasil analisis dose profile diperoleh kesesuaian di daerah tengah lapangan sedangkan perbedaan lebih besar terjadi pada daerah penumbra dan kedalaman dangkal akibat gradien dosis yang curam serta keterbatasan resolusi detektor. Simulasi Monte Carlo berbasis PRIMO dapat diandalkan sebagai instrumen verifikasi independen dalam pelaksanaan QA rutin berkas foton LINAC Varian Clinac CX energi 6 MV.

The mean ionization potential (I-value) is a primary determinant of the position of the heavy ion Bragg peak. To minimize their impact on beam range errors and quantify their uncertainties, the currently used I-values in Geant4 material database are revisited. The study aims at comparing set of I-values in different Geant4 versions and cross validation with PHITS Monte Carlo (MC) code. The Bragg curves of mono-energetic 290 MeV/u carbon ion beams in a Polymethyl Methacrylate (PMMA) phantom were simulated using Geant4 versions 10.6.2 and 11.2.1. Similar beam energies were replicated using the PHITS code. The Bragg curves showed good agreement between the two versions of Geant4 MC code for an I-value of 74 eV, corresponding to G4_PLEXIGLASS in the material database. When the I-value was lowered to 65 eV and 48 eV, the Bragg curves from Geant4 version 11.2.1 shifted to shallower depths. This research provides insights for evaluating the Geant4 physics model.