Pengaruh Variasi Pitch Dan Ketebalan Irisan Untuk Evaluasi Kualitas Citra Pada Protokol CT-Scan: Studi Fantom Toraks Pediatrik

Fatonah, Nurul (2025) Pengaruh Variasi Pitch Dan Ketebalan Irisan Untuk Evaluasi Kualitas Citra Pada Protokol CT-Scan: Studi Fantom Toraks Pediatrik. Other thesis, Institut Teknologi Sepuluh Nopember.

Text 5001211073-Undergraduate_Thesis.pdf - Accepted Version Restricted to Repository staff only Download (5MB) | Request a copy

Abstract

Computed Tomography (CT) berperan penting dalam pencitraan medis, khususnya pada pasien pediatrik yang lebih sensitif terhadap radiasi pengion dibandingkan pasien dewasa. Oleh karena itu, diperlukan optimasi dosis dan kualitas citra secara simultan, yang umumnya menggunakan fantom. Akan tetapi, fantom yang saat ini tersedia belum merepresentasikan karakteristik jaringan pediatrik secara akurat. Dengan demikian, dikembangkan fantom toraks pediatrik usia 4 tahun berbasis data DICOM pasien, dilengkapi modul dosis organ, linearitas, low-contrast, resolusi spasial, dan caliper tool. Pemindaian dilakukan pada variasi pitch (0,516 – 1,531) dan ketebalan irisan (0,625 – 3,75 mm) dengan parameter tetap berdasarkan AAPM Pediatric Routine Chest 2017 (120 kV, 70 mA, FOV 250 mm, rotasi 50 ms, dan ASiR-V 50%). Penelitian ini mengevaluasi dosis organ pada paru-paru, jaringan lunak, tulang belakang, dan jantung menggunakan film Gafchromic LD-V1, serta menganalisis parameter kualitas citra yang meliputi linearitas, Contrast-to-Noise Ratio (CNR), Noise Power Spectrum (NPS), Modulation Transfer Function (MTF), dan akurasi sudut serta jarak. Hasil validasi angka CT fantom menunjukkan kesesuaian yang baik dengan DICOM pasien untuk jaringan lunak, tulang, dan paru-paru. CTDIvol menghasilkan penurunan nilai seiring peningkatan pitch, dengan seluruh nilai memenuhi standar AAPM kecuali pitch 0,516, dan umumnya lebih rendah dibandingkan dosis organ. Selanjutnya, kualitas citra menunjukkan linearitas yang baik. Noise dan NPS meningkat sebanding dengan pitch dan menurun saat irisan lebih tebal, sedangkan nilai CNR berfluktuasi antar protokol. Analisis resolusi spasial melalui MTF10 menunjukkan edge MTF (1,3–1,9 /mm) lebih efektif untuk in-plane resolution, diperkuat dengan z-MTF (0,6 /mm), khususnya dalam mengatasi artefak beam hardening dari kawat nichrome. Akurasi sudut dan jarak menghasilkan standar deviasi masing-masing 0,59° dan 0,32 mm. Berdasarkan hasil tersebut, protokol yang direkomendasikan untuk pencitraan toraks pediatrik usia 4 tahun adalah pitch 1,375 dan ketebalan irisan 1,25 mm untuk optimasi kualitas citra dan dosis radiasi.
================================================================================================================================
Computed tomography (CT) plays a crucial role in medical imaging, particularly in pediatric patients, who are more sensitive to ionizing radiation than adults. Therefore, simultaneous dose and image quality optimization, typically using a phantom, is necessary. However, currently available phantoms do not accurately represent the characteristics of pediatric tissues. Therefore, a 4-year-old pediatric chest phantom was developed based on patient DICOM data and equipped with organ dose, linearity, low-contrast, spatial resolution, and caliper tool modules. Scanning was performed at varying pitches (0.516–1.531) and slice thicknesses (0.625–3.75 mm) with fixed parameters based on the AAPM Pediatric Routine Chest 2017 protocol (120 kV, 70 mA, 250 mm FOV, 50 ms rotation, and 50% ASiR-V). This study evaluated the organ dose to the lungs, soft tissues, spine, and heart using Gafchromic LDV1 film and analyzed image quality parameters, including linearity, Contrast-to-Noise Ratio (CNR), Noise Power Spectrum (NPS), Modulation Transfer Function (MTF), and angular and distance accuracy. The CT phantom number validation results showed good agreement with the DICOM data for the soft tissues, bones, and lungs. The CTDIvol decreased with increasing pitch, with all values meeting the AAPM standards, except for a pitch of 0.516, and was generally lower than the organ dose. Furthermore, the image quality exhibited good linearity. Noise and NPS increased proportionally with pitch and decreased with thicker slices, whereas CNR values fluctuated between protocols. Spatial resolution analysis using MTF10 showed that edge MTF (1.3–1.9/mm) was more effective for in-plane resolution, reinforced by z-MTF (0.6/mm), particularly in overcoming beam-hardening artifacts from nichrome wire. The angular and distance accuracies yielded standard deviations of 0.59° and 0.32 mm, respectively. Based on these results, the recommended protocol for pediatric thoracic imaging in 4-year-olds is a 1.375° pitch and 1.25 mm slice thickness to optimize image quality and radiation dose

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Fantom toraks pediatrik, Ketebalan irisan, Kualitas citra, dan Pitch, Image quality, Pediatric thoracic phantom, Pitch, and Slice thickness
Subjects:	Q Science > QC Physics
Divisions:	Faculty of Science and Data Analytics (SCIENTICS) > Physics > 45201-(S1) Undergraduate Thesis
Depositing User:	Nurul Fatonah
Date Deposited:	23 Jul 2025 03:44
Last Modified:	23 Jul 2025 03:44
URI:	http://repository.its.ac.id/id/eprint/120723

Actions (login required)

View Item