I Wayan Ari Makmur
Jurusan Fisika, Fakultas Sains dan Matematika, Universitas Diponegoro, Semarang, Jawa Tengah

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Evaluasi Ketebalan Irisan (Slice Thickness) pada Pesawat CT-Scan Single Slice Makmur, I Wayan Ari; Setiabudi, Wahyu; Anam, Choirul
JURNAL SAINS DAN MATEMATIKA Volume 21 Issue 2 Year 2013
Publisher : JURNAL SAINS DAN MATEMATIKA

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (3895.227 KB)

Abstract

An evaluation of the value of the slice thickness due to changes in tube voltage and tube current on the CT scan have been performed. The evaluation is done by making images using CT performance test phantom. Testing is done by performing three scanning on each slice. Exposure factors used were 120 kVp-60 mA, 160 mA 120-kVp, 140-kVp 60 mA, and 140 kVp 160 mA. Nominal beam width were 2 mm, 3 mm, 5 mm, 7 mm, and 10 mm. Once the axial image was obtained (on the area for slice thickness determination),  then calculated the average CT number on the region of interest (ROI). After it was made graphs to determine the value of FWHM which indicates the magnitude of the thickness of the slice. From the test results obtained that changes in tube voltage and tube current does not affect the value of the thickness of the slice. Also found that the value of slice thickness for each thickness, greater than the nominal beam width.   Keywords: Phantom CT Performance Test, Slice Thickness, CT-Scan    Telah dilakukan evaluasi terhadap nilai slice thickness terhadap perubahan tegangan tabung dan arus tabung pada pesawat CT scan. Pengujian dilakukan dengan membuat citra menggunakan fantom CT performance test. Pengujian dilakukan dengan melakukan eksposi sebanyak tiga kali pada tiap-tiap slice. Faktor eksposi yang digunakan yaitu 120 kVp-60 mA, 120 kVp-160 mA, 140 kVp-60 mA, dan 140 kVp-160 mA. Slice thickness yang diuji adalah ketebalan 2 mm, 3 mm, 5 mm, 7 mm, dan 10 mm. Setelah didapatkan citra aksial pada bagian daerah uji slice thickness, maka diambil beberapa lokasi ROI dan dihitung rerata CT Number, kemudian nilai tersebut dibuat grafik dan ditentukan nilai FWHM yang menunjukkan besarnya slice thickness. Dari hasil pengujian diketahui perubahan tegangan tabung dan arus tabung tidak berpengaruh terhadap nilai slice thickness. Hasil pengukuran diketahui bahwa nilai slice thickness untuk masing-masing ketebalan, lebih besar dibanding nominal beam width. Kata kunci : Simulasi Monte Carlo, Percentage Depht Dose (PDD), Dose Profile, Inhomogenitas Jaringan.
Optimizing bladder volume to minimize OAR dose in cervical cancer HDR intracavitary brachytherapy: an experimental and analytical dosimetric investigation Ariani, Tami Oktavia; Wirawan, Rahadi; Marzuki, Marzuki; Subroto, Rinarto; Makmur, I Wayan Ari; Qomariyah, Nurul
ORBITA: Jurnal Pendidikan dan Ilmu Fisika Vol 11, No 2 (2025): November
Publisher : Universitas Muhammadiyah Mataram

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.31764/orbita.v11i2.35552

Abstract

This study aims to determine the optimal bladder volume that can balance the dose distribution to the organs-at-risk (OARs), specifically the bladder and rectum, and to analyze the relationship between variations in bladder volume and the dose received by these two organs during high-dose-rate (HDR) brachytherapy. Six bladder volume variations, namely empty, 100 cc, 150 cc, 200 cc, 250 cc, and 300 cc, were used to analyze the correlation between bladder volume and the radiation dose received by the bladder and rectum. An experimental approach was employed by observing the dose point distribution and the D2cc dose to both organs based on calculations from the Treatment Planning System (TPS), which were then compared with analytical calculations using a quadratic polynomial regression model via the Ordinary Least Squares (OLS) method. In general, the bladder point dose and D2cc dose increased with increasing bladder volume; however, the rectal dose demonstrated very high stability (90-100 cGy). Based on the variations in bladder volume, the optimal volume was 100 cc, as it protects the bladder by minimizing dose distribution and stabilizes the dose to the rectum. The statistical analysis results showed that the quadratic regression model had a high goodness-of-fit to the experimental data, with a coefficient of determination (R²) value of 0.92.