Učinki anodne napetosti (kV) in produkta anodnega toka in časa (mAs) na kakovost PET/CT slike: študija nema body fantoma : magistrsko delo

Čavlin, Milana (author), Rep, Sebastijan (mentor), Ležaič, Luka (comentor), Mekiš, Nejc (reviewer)

Uvod: PET/CT naprave imajo ključno vlogo v sodobni diagnostiki, saj omogočajo kvantifikacijo presnovnih aktivnosti in strukturno analizo tkiv. Kljub napredku ostaja izziv zmanjšanja doze sevanja pomemben, zlasti pri pacientih, ki potrebujejo ponavljajoča slikanja. Ta študija se osredotoča na optimizacijo CT parametrov z namenom zmanjšanja doze ob ohranjanju kakovosti slike. Namen: Namen raziskave je oceniti vpliv različnih vrednosti anodne napetosti (kV) in produkta anodnega toka in časa (mAs) na SUV ter parametre kakovosti slike (CNR in CRC) in na dozo sevanja (CTDIvol in DLP). Metode dela: Meritve so bile izvedene z NEMA fantomom, na napravi Siemens Biograph mCT v UKC Ljubljana pri različnih kombinacijah anodne napetosti (70–140 kV) in produkta anodnega toka in časa (30–130 mAs) ter razmerjih 1:10, 1:5 in 1:3. Spremljani so bili parametri: SUV, CNR, CRC, CTDIvol in DLP. Statistična analiza je bila izvedena v IBM SPSS Statistics, pri čemer smo ocenjevali povezanost parametrov sevanja, kakovosti slike in natančnosti SUV. Rezultati: Rezultati so prikazani za vsa razmerja (1:10, 1:5 in 1:3) in za vse analizirane sfere. Pearsonova analiza je pokazala zelo močno pozitivno korelacijo med koncentracijo radiofarmaka (kBq/ml) in vrednostmi SUV pri vseh razmerjih (r = 0,979; 0,945; 0,891; p < 0,001). ANOVA je pokazala, da variacije CT parametrov (kV, mAs) nimajo statistično pomembnega vpliva na SUV, prav tako ne na CNRmax, CNRmean in CRCmax. Analiza trenda SUV glede na CTDIvol in DLP ni pokazala statistično pomembnih sprememb povprečnih SUV vrednosti ob povečanju doze. Razprava in zaključek: Rezultati podpirajo začetne hipoteze in potrjujejo, da je optimizacija CT parametrov izvedljiva brez ogrožanja kakovosti slike. Spremembe CT parametrov omogočajo zmanjšanje doze sevanja za 52,63 % (CTDIvol) in 56,76 % (DLP) brez vpliva na SUV vrednosti (odstopanja do 1,74 %) ali kakovost slike (CNR, CRC). Primerjava s prejšnjimi raziskavami kaže, da zmanjšanje sevalnih parametrov omogoča zmanjšanje doze ob hkratni ohranitvi diagnostične vrednosti slike. To ima pomembne klinične implikacije, zlasti pri pacientih s pogostimi slikanji. Nadaljnje raziskave bi morale vključevati širši spekter pacientov za potrditev splošne uporabnosti ugotovitev.

• Language: Slovenian
• Keywords: magistrska dela, radiološka tehnologija, PET/CT, kvantifikacija SUV, optimizacija doze, kakovost slike, napetost, anodna struja, variacije parametrov
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [M. Čavlin]
• Year: 2025
• Number of pages: 55 str.
• PID: 20.500.12556/RUL-169516
• UDC: 616-07
• COBISS.SI-ID: 237882883
• Publication date in RUL: 01.06.2025

Secondary language

• Language: English
• Title: The effects of tube voltage (kV) and anode current (mAs) values for PET/CT image quality: a nema body phantom study : master thesis

Abstract

Introduction: PET/CT systems play a key role in modern diagnostics by enabling quantification of metabolic activity and structural tissue analysis. Despite technological advancements, reducing radiation dose remains a challenge—especially for patients requiring repeated imaging. This study focuses on optimizing CT parameters to lower radiation dose while maintaining image quality. Purpose: The aim of the study is to assess the impact of different tube voltage (kV) and tube current (mAs) values on SUV, image quality parameters (CNR and CRC), and radiation dose indicators (CTDIvol and DLP). Methods: Measurements were carried out using the NEMA phantom on a Siemens Biograph mCT system at the UMC Ljubljana. Various combinations of tube voltage (70–140 kV) and current (30–130 mAs) were tested at activity ratios of 1:10, 1:5, and 1:3. The monitored parameters included SUV, CNR, CRC, CTDIvol and DLP. Statistical analysis was performed using IBM SPSS Statistics to evaluate the correlation between radiation dose, image quality, and SUV quantification accuracy. Results: Results are presented for all background-to-sphere ratios (1:10, 1:5, 1:3) and all analyzed spheres. Pearson correlation analysis showed a very strong positive correlation between radiopharmaceutical concentration (kBq/ml) and SUV values at all ratios (r = 0.979; 0.945; 0.891; p < 0.001). ANOVA indicated that variations in CT parameters (kV, mAs) had no statistically significant effect on SUV or on CNRmax, CNRmean, or CRCmax. Trend analysis showed no significant changes in mean SUV values with increased dose (CTDIvol and DLP). Discussion and conclusion: The results confirm that CT parameter optimization is feasible without compromising image quality. Adjusting CT settings enabled dose reductions of 52.63% (CTDIvol) and 56.76% (DLP), without affecting SUV values (up to 1.74% deviation) or image quality (CNR, CRC). Comparison with previous studies shows that dose can be reduced while maintaining diagnostic image value. This has important clinical implications, especially for patients undergoing frequent scans. Further research should include a broader patient population to confirm these findings.

• Keywords: master's theses, radiologic technology, PET/CT, SUV quantification, dose optimization, image quality, voltage, tube current, parameter variation