Primerjava protokola računalniške tomografije prsnega koša na različnih aparatih: vpliv na dozo in diagnostično uporabnost slik

• Main Author: Ožbolt, Petra
• Other Authors: Žibert, Janez
• Format: Master Thesis
• Language: Slovenian
• Published: 2019
• Subjects: računalniška tomografija; absorbirana doza; kakovost slike; optimizacija; computed tomography; absorbed dose; image quality; optimisaton; sami
• Online Access: https://repozitorij.uni-lj.si/IzpisGradiva.php?id=113234; https://repozitorij.uni-lj.si/Dokument.php?id=125281&dn=; https://plus.si.cobiss.net/opac7/bib/5757035?lang=sl

Uvod: CT naprave se med seboj razlikujejo po svojih tehničnih lastnostih, različne indikacije pa zahtevajo uporabo edinstvenih protokolov za posamezno preiskavo. Vzpostavitev protokolov poveča diagnostično učinkovitost ob hkratnem zmanjšanju morebitne povzročene škode pacientu. Zaradi tveganj povezanih z radiološkim slikanjem je potrebno upoštevati načela zaščite pred sevanjem, kot tudi načine zmanjševanja dozne obremenitve pacientov in zagotavljanja dobre kakovost slike. Namen: Namen magistrskega dela je bil ugotoviti, kakšna je razlika v kakovosti slik na vseh petih CT aparatih Onkološkega inštituta Ljubljana, ugotovitve pa predstaviti v povezavi s podatki o celokupni dozi, ki jo prejmejo pacienti pri diagnostičnem slikanju prsnega koša z računalniško tomografijo. Metode dela: Poslikali smo skupaj 19 osnovnih in dodatnih protokolov z uporabo standardnega CT protokola prsnega koša in trebuha, ki se uporablja na Oddelku za radiologijo. Le-ta je bil izhodišče skenirnih parametrov, na podlagi katerih smo na ostalih napravah prilagodili protokole z namenom pridobitve istih pogojev slikanja. Nadaljevali smo z lastno izbranim protokolom, za katerega smo sami določili parametre slikanja in ga uporabili na vseh napravah. 5 zdravnikov specialistov radiologije je pridobljene slike ocenjevalo po Evropskih smernicah o merilih kakovosti za računalniško tomografijo. Rezultati: Rezultati kažejo, da z izjemo enega para zdravnikov obstaja podobnost ocenjevanja. Več kot polovica primerjav ujemanj je bilo statistično značilnih, torej sta ta ocenjevalca dajala enake ocene. Protokol št. 7 Philips naprave je najboljše ocenjeni protokol s strani zdravnikov (3,97), protokol št. 19 GE SPECT-CT pa najslabše (1,89). Prvi protokol Siemens AS+ naprave je imel najnižje dozne vrednosti (DLP 67 mGy cm, CTDI 1,86 mGy). Philips protokol št. 10 povzroča največjo dozno obremenitev (DLP 568,9 mGy cm, CTDI-ja 16,23 mGy). Razprava in zaključek: Dokazali smo, da na kakovost slike vpliva izbira posameznega protokola, predvsem zaradi avtomatskega nadzora ekspozicije, iterativne rekonstrukcije in izbire napetosti. Protokol št. 1 Siemens AS+ je najmanj sevalno obremenjujoč za paciente. Ko zaradi skoraj 6x višje doze zanemarimo Philips protokol št. 7, ki ima minimalno boljše ocenjeno kakovost slike s strani zdravnikov radiologov, lahko rečemo, da Siemens AS+ proizvaja tudi slike z najboljšo kakovostjo. Z raziskavo smo pokazali katere naprave so primerljive med seboj in s kakšnimi nastavitvami jih lahko uporabljamo za enako kakovost slike in čim manjšo sevalno dozo. Introduction: Computed tomography devices differ in their technical characteristics. Different indications require the use of unique protocols for each examination. Establishing protocols increases diagnostic efficacy while reducing potential harm to the patient. Due to the risks associated with radiological imaging, the principles of radiation protection must be observed, as well as the ways to reduce patient dose and ensure good image quality. Purpose: The purpose was to determine the difference in image quality on all five CT devices of the Ljubljana Institute of Oncology and to present the findings in connection to the difference in dose of ionizing radiation received by patients in computed tomography diagnostic imaging of the chest. Methods: We have imaged a total of 19 primary and addition protocols using the standard chest and abdomen CT protocol used in the Department of radiology. It was the starting point of scanning parameters on the basis of which we adjusted protocols on other devices in order to obtain the same imaging conditions. We continued scanning with a protocol of our own, for which we determined the imaging parameters ourselves and used it on other devices. 5 radiology specialists evaluated the obtained images according to the European guidelines on qualty criteria for computed tomography. Results: The results show that with the exception of one pair of physicians, there is a similarity of assessment. More than half of the comparisons were statistically significant, meaning that these physicians gave the same estimates. The Philips device protocol no. 7 is the best-rated physician protocol (3.97), and the GE SPECT-CT protocol no. 19 is the worst-rated (1.89). The first protocol of the Siemens AS + device had the lowest dose values (DLP 67 mGy cm, CTDI 1.86 mGy). Philips protocol no. 10 causes the highest dose rate (DLP 568.9 mGy cm, CTDI 16.23 mGy). Discussion and conclusion: We have shown that image quality is influenced by the choice of a single protocol, mainly due to automatic exposure control, iterative reconstruction and voltage selection. Protocol no. 1 Siemens AS + device causes the lowest dose for patients. When we, due to the almost 6x higher dose, ignore the Philips protocol no. 7 which has slightly better image quality, we can say that Siemens AS + also produces the best quality images. The research showed which devices are comparable to each other and with what settings they can be used to obtain the same image quality with the lowest possible radiation dose.