Optimizacija CT protokola za presejalni program zgodnjega odkrivanja raka pljuč brez uporabe dodatnega filtriranja : magistrsko delo

Klančar, Kaja (avtor), Mekiš, Nejc (mentor), Požek, Igor (komentor), Škrk, Damijan (recenzent)

Uvod: Pljučni rak je glede na pogostost rakavih obolenj po svetu na drugem mestu in predstavlja vodilni vzrok smrti zaradi raka. Računalniška tomografija z nižjo sevalno obremenitvijo (LDCT) je edina metoda za zgodnje odkrivanje pljučnega raka, ki dokazano zmanjšuje umrljivost. Sprejemljiva povprečna efektivna doza za presajanje pljučnega raka s CT preiskavo je približno 1,5 mSv, pri standardni CT preiskavi pa pacienti prejmejo tudi do 7 mSv. Namen: Namen raziskave je ugotoviti, kako se pri CT slikanju prsnih organov s spreminjanjem tokovnega sunka (mAs) ob fiksni nastavitvi anodne napetosti (kV) spremenita prejeta doza in kakovost slik. Pridobiti želimo optimiziran protokol brez uporabe dodatne filtracije, primeren za presejanje pljučnega raka in kontrolna slikanja. Metode dela: Raziskavo smo izvedli v dveh delih. V prvem delu smo meritve izvajali na fantomu. Opravili smo 57 slikanj, 3 s standardnim protokolom, 27 z uporabo ročne ekspozicije in 27 z avtomatskim nadzorom ekspozicije (AEC). V drugem delu smo meritve izvedli na 152 pacientih, ki so prišli na kontrolno slikanje. Pri slikanju smo uporabljali fiksno napetost in dve različni nastavitvi tokovnega sunka. S prvim protokolom smo slikali 76 pacientov z indeksom telesne mase (ITM) manjšim od 30, z drugim pa 76 pacientov z ITM enakim ali večjim od 30. Pri vseh pacientih smo beležili višino, maso, DLP, CTDIvol, referenčne in efektivne tokovne sunke. Pridobili smo tudi subjektivno in objektivno oceno slik. Rezultati: V prvem delu smo z meritvami na fantomu pridobili najbolj primerna protokola za slikanje pacientov. V drugem delu smo ugotovili, da obstajajo statistično značilne razlike med novim in standardnim protokolom v referenčnih in efektivnih vrednostih tokovnega sunka (p<0,001), DLP (p<0,001), CTDIvol (p<0,001), CNR (p<0,001) in SNR (p<0,001). Pri subjektivnem ocenjevanju kakovosti slik smo ugotovili, da med optimiziranima protokoloma obstajajo statistično značilne razlike pri vseh ocenjevalnih kriterijih razen pri splošni kakovosti slik (p=0,073). Skupna ocena slik je bila višja pri protokolu za paciente z visokim ITM (p=0,009). Razprava in zaključek: Z uporabo visokih fiksnih napetosti in nizkih tokovnih sunkov znižamo prejeto dozo za 40–60 %. Kakovost slike se z optimizacijo poslabša, vendar je kljub temu še vedno ustrezna za diagnostične namene. Z raziskavo smo pridobili optimiziran protokol, primeren za uporabo v presejalnem programu raka pljuč in kontrolna slikanja.

• Jezik: Slovenski jezik
• Ključne besede: magistrska dela, radiološka tehnologija, rak pljuč, presejalni program, računalniška tomografija, zmanjšanje doze, dozna obremenitev, kakovost slike
• Vrsta gradiva: Magistrsko delo/naloga
• Tipologija: 2.09 - Magistrsko delo
• Organizacija: ZF - Zdravstvena fakulteta
• Kraj izida: Ljubljana
• Založnik: [K. Klančar]
• Leto izida: 2025
• Št. strani: 97 str., [6] str. pril.
• PID: 20.500.12556/RUL-169579
• UDK: 616-07
• COBISS.SI-ID: 238367235
• Datum objave v RUL: 05.06.2025

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Optimization of a CT protocol for lung cancer screening program without the use of additional filtration : master thesis

Izvleček

Introduction: Lung cancer is the second most common cancer worldwide and the leading cause of cancer-related deaths. Low-dose computed tomography (LDCT) is the only method for early detection of lung cancer that has been shown to reduce mortality. The acceptable average effective dose for lung cancer screening with CT is approximately 1.5 mSv, while patients may receive up to 7 mSv with a standard chest CT. Purpose: The purpose of this study is to determine how varying the tube current (mAs) at a fixed tube voltage (kV) affects the radiation dose and image quality in chest CT imaging. We aim to obtain an optimized protocol without the use of additional filtration, suitable for lung cancer screening and follow-up imaging. Methods: The study was divided into two parts. In the first part, we used a phantom for measurements. We performed 57 CT scans: 3 using the standard protocol, 27 with manual exposure, and 27 with automatic exposure control (AEC). The second part was performed on 152 patients referred for follow-up chest CT imaging. A fixed tube voltage and two different tube current settings were used for imaging. With the first protocol, we scanned 76 patients with a body mass index (BMI) below 30, while the second protocol was used for 76 patients with a BMI of 30 or higher. In all patients, height, weight, DLP, CTDIvol, and both reference and effective tube currents were recorded. Additionally, both subjective and objective image quality assessments were obtained. Results: In the first part, we used measurements on a phantom to determine the most suitable protocols for imaging patients. In the second part, we found that there are statistically significant differences between the new and standard protocol in reference and effective tube currents (p<0.001), DLP (p<0.001), CTDIvol (p<0.001), CNR (p<0.001), and SNR (p<0.001). In the subjective assessment of image quality, we found statistically significant differences between the optimized protocols for all evaluation criteria, except for overall image quality (p=0.073). The total image score was higher with the protocol for patients with a high BMI (p=0.009). Discussion and conclusion: The use of high fixed tube voltage and low tube current reduces the radiation dose by 40–60 %. Image quality degrades with optimization, but it is still adequate for diagnostic purposes. We obtained an optimized protocol suitable for use in a lung cancer screening program and follow-up imaging.

• Ključne besede: master's theses, radiologic technology, lung cancer, screening program, computed tomography, dose reduction, radiation dose, image quality