Modulacija anodnega toka glede na anatomske strukture pri CT slikanju glave : magistrsko delo

Korošec, Vita (author), Škrk, Damijan (mentor), Mekiš, Nejc (reviewer)

Uvod: Računalniška tomografija je pomembna diagnostična metoda, vendar je povezana z visoko sevalno obremenitvijo, zlasti za radioobčutljive organe, kot je očesna leča. Zato je optimizacija slikanja ključnega pomena. Ena izmed tehnik je modulacija anodnega toka glede na anatomske strukture, ki zmanjšuje izpostavljenost anteriorno ležečih organov z znižanjem toka v anteriornem delu rotacije. Namen: Z raziskavo želimo ovrednotiti vpliv OBTCM tehnike proizvajalca Siemens (X-CARE) na dozno obremenitev in kakovost slik pri CT preiskavah glave. Metode dela: Meritve so bile izvedene v treh delih. Najprej smo z antropomorfnim fantomom glave analizirali vstopno kožno dozo na šestih točkah glave, ter opazovali ali se doza, skladno s teoretičnim delovanjem X-CARE zmanjša na anteriornem in poveča na posteriornem delu glave. V drugem delu smo s CTDI fantomom opazovali vpliv X-CARE na porazdelitev CTDIvol znotraj fantoma. V tretjem delu smo na podlagi retrospektivne analize CT slik pediatričnih preiskovancev na objektiven način s pomočjo računalniškega programa primerjali kakovost slik med rutinskim in X-CARE protokolom ter ocenili vpliv modulacije na šum, razmerje med signalom in šumom (SNR) in razmerje med kontrastom in šumom (CNR). Dodatno smo pri teh preiskovancih analizirali tudi CTDIvol in DLP za primerjavo med protokoloma v kliničnem okolju. Rezultati: Uporaba X-CARE je pri meritvah vstopne kožne doze na antropomorfnem fantomu glave povzročila izrazito zmanjšanje doze na anteriornem delu glave, največ na področju glabele in očesne leče (do 69 %), medtem ko se je doza na posteriornem delu glave povečala (22 %). Tudi pri meritvah v stranskem položaju fantoma se je modulacija prilagodila položaju in zmanjšala dozo na anteriorni del glave za približno 60 %. Tudi dodatne meritve s CTDI fantomom so pokazale zmanjšanje doze (CTDIvol in DLP) na anteriornem delu fantoma ter povečanje doze na posteriornih in lateralnih delih, kar potrjuje pričakovani način delovanja modulacije X-CARE. Analiza kakovosti slik pri 60 pediatričnih CT preiskavah glave ni pokazala statistično značilnih razlik v standardnem odklonu CT števil, SNR in CNR med primerjanima protokoloma (p > 0,05). Kakovost slik je bila pri obeh protokolih primerljiva. Primerjava CTDIvol in DLP pri pediatričnih preiskovancih je pokazala statistično značilno višje vrednosti CTDIvol in DLP pri preiskavah, izvedenih z uporabo X-CARE (p < 0,001). Razprava in zaključek: Rezultati kažejo, da uporaba tehnike X-CARE omogoča učinkovito zmanjšanje doze anteriorno ležečih struktur, kot je očesna leča, brez statistično značilnega vpliva na kakovost slik.

• Language: Slovenian
• Keywords: magistrska dela, radiološka tehnologija, VKD, kakovost slike, doza na očesno lečo, optimizacija protokolov, X-CARE
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [V. Korošec]
• Year: 2026
• Number of pages: 71 str., [14] str. pril.
• PID: 20.500.12556/RUL-188187
• UDC: 616-07
• COBISS.SI-ID: 291934723
• Publication date in RUL: 19.09.2026

Secondary language

• Language: English
• Title: Organ based tube current modulation in head CT imaging : master thesis

Abstract

Introduction: Computed tomography is an important diagnostic tool, but is associated with relatively high radiation exposure, especially to radiosensitive organs such as the eye lens. Therefore, optimization of imaging is essential. One of the techniques is organ-based tube current modulation, which reduces exposure of anteriorly located organs by lowering the tube current during the anterior part of the rotation. Purpose: The aim of this thesis is to analyze the impact of organ-based tube current modulation by Siemens (X-CARE) on radiation dose and image quality in head CT examinations. Methods: The measurements were performed in three parts. First, we analyzed the enstrance skin dose at six points with the anthropomorphic head phantom, and observed whether the dose, in accordance with the theoretical operation of X-CARE, decreases in the anterior and increases in the posterior part of the head. In the second part, we observed the effect of X-CARE on the distribution of CTDIvol within the phantom using a CTDI phantom. In the third part, based on a retrospective analysis of CT images of pediatric subjects, we objectively compared the image quality between the routine and X-CARE protocol using computer software and evaluated the impact of modulation on noise, signal to noise ratio (SNR) and contrast to noise ratio (CNR). In addition, we also analyzed CTDIvol and DLP in these subjects to compare the protocols in a clinical setting. Results: The use of X-CARE in measurements of the entrance skin dose on an anthropomorphic head phantom resulted in a significant reduction in dose to the anterior part of the head, most notably in the glabella and lens (up to 69%), while the dose to the posterior part of the head increased (22%). Also in measurements in the lateral position of the phantom, the modulation adapted to the position and reduced the dose to the anterior part of the head by approximately 60%. Additional measurements with the CTDI phantom also showed a reduction in dose (CTDIvol and DLP) to the anterior part of the phantom and an increase in dose to the posterior and lateral parts, confirming the expected mode of action of the X-CARE modulation. Image quality analysis of 60 pediatric head CT examinations showed no statistically significant differences in the standard deviation of CT numbers, SNR or CNR between the compared protocols (p > 0.05). Image quality was comparable for both protocols. Comparison of CTDIvol and DLP in pediatric subjects showed statistically significantly higher CTDIvol and DLP values in examinations performed using X-CARE (p< 0.001) Discussion and conclusion: The results show that the use of the X-CARE technique allows for dose reduction of anterior structures, such as the lens of the eye, without a statistically significant impact on image quality.

• Keywords: master's theses, radiologic technology, ESD, image quality, lens dose, protocol optimization, X-CARE