• Journal of radiological science and technology
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• v.47 no.2
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• pp.117-123
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• 2024

This study was to assessment of quality assurance (QA) and noise characteristics of Noise Power Spectrum (NPS) according to the time of by using electronic portal imaging device (EPID) for LINAC (Linear Accelerator). LINAC device was (Varian Clinac^R iX LINAC, USA) used and the were 40 × 30 cm² of detector size were 1024 × 768 photo-electric diode array size. Signal could be obtained the K-space image of white noise images for NPS and we used to Overlap, Non-Overlap, Out of Penumbra, Flatness, Symmetry, Symmetry Rt, Lt methods. The 2013s NPS image Out of Penumbra quantitatively value more than 2013s NPS image Symmetry Rt, Lt methods quantitatively NPS based on the frequency of 1.0 mm^-1. Thus, the 2022s NPS image Out of Penumbra quantitatively value more than 2022s NPS image Symmetry Rt, Lt methods quantitatively NPS based on the frequency of 1.0 mm^-1. The assessment of comparison of white noise for NPS image noise and intensity of this study were to that should be used efficiently of the LINAC EPID detector system for Overlap method for International Electro-technical Commission (IEC).

• Progress in Medical Physics
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• v.9 no.2
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• pp.105-113
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• 1998

Accurate radiation dosimetric characters is very important to determine of dose to a radiotherapeutic patient. Medical linear accelerators have been developed not only its new quality of convenient operation but also electric moderation. It is reliable to measure more detail physical parameter that linac's internal ability. Typically, radiation dosimetric tool is classified ionization chamber, film, thermoluminescence dosimeter, etc. Nowaday, Electronic Portal Imaging Device is smeared in radiation field to verification of treatment region. EPID's image was focused that using both on-line image verification and absolutely minimum absorbed dose during radiotherapy. So, Electronic Portal Imaging was tested for quality evaluation of medical linear accelerator had its pure conditional flash. This study has performed symmetry, Light/Radiation field congruence, and energy check, geometry difference on wedge filter using a liquid filled ion chamber (EPID). Prior to irradiated on EPID, high energy photon beam is checked with ion chamber. Using these results more convenient dosimetric method is accomplished by EPID that taken digital image. Medical image is acquired with EPID too. Therefore, EPID can be analyzed by numerical information for what want to see or get more knowledge for natural human condition.

• Progress in Medical Physics
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• v.35 no.2
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• pp.45-51
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• 2024

Purpose: Accurate operation of the multi-leaf collimator (MLC), a key technology in intensity modulated radiation therapy (IMRT), is essential for safe and optimal radiation treatment. The Halcyon^TM linear accelerator has a collimator with low leakage and radiation transmission, making it suitable for IMRT. The limitations of the existing Halcyon^TM MLC quality assurance (QA) method were supplemented with a mathematical method, and the results were analyzed. Methods: Electric portal imaging device (EPID) images obtained by performing the MLC QA plan on the Halcyon^TM was analyzed using Python. The picket fence tests were performed and compared using the maximum pixel value and mathematical methods. Dose rate, gantry speed, and leaf speed variation plan were performed for dose transmission comparison. Results: For the maximum pixel value, the minimum distance between leaf junctions was 13.86 mm, and the maximum was 16.06 mm. However, for the mathematical method, the minimum and maximum were 14.54 mm and 15.68 mm, respectively. This suggests that setting the peak value to the highest value may cause an error in interpretation due to the limitations of the pixels of the EPID image. Performing QA on the remaining items confirmed that the measured values were within 3% of tolerance. Conclusions: The presented analysis method applied to the MLC QA can derive more reasonable and valid values than existing methods, which will help with MLC monitoring by reducing errors in excessive interpretation.