Influence of radiological technology on the signal-to-noise ratio of the radiograph (literature review)

Uvod: Cilj slikovnih diagnostičnih metod je, da radiolog na rentgenogramu prepozna posamezno stanje, zato mora biti rentgenogram dovolj kakovosten. Eden izmed kriterijev kakovosti je razmerje signal šum (RSŠ). Poznamo elektronski šum, strukturni šum, šum zaradi digitalizacije in kvantni šum, na katerega lahko radiološki inženirji najbolj vplivajo. Na RSŠ vpliva poleg ekspozicijskih pogojev tudi veliko ostalih dejavnikov. Za dovolj dobro RSŠ so odgovorni radiološki inženirji. Nepoznavanje teorije stroke in nestrokovno delo lahko skupaj z današnjo digitalno radiografijo prinesejo kakovostno sliko, vendar močno preseženo pacientovo absorbirano dozo. Namen: Namen diplomskega dela je bil s pomočjo sistematičnega pregleda literature predstaviti različne dejavnike, ki vplivajo na RSŠ, kako vplivajo na RSŠ in naknadno odstranjevanja le-tega iz digitalnega rentgenograma ter razpravljati o rezultatih raziskave s študijsko literaturo, ki jo uporabljamo na Zdravstveni fakulteti Univerze v Ljubljani. Cilj je bil, da se naučim izdelave diplomskega dela po vnaprej določenih pravilih. Metode dela: V diplomskem delu sem uporabil deskriptivno metodo s sistematičnim pregledom literature. Literaturo sem iskal oktobra 2020, aprila 2021, februarja in marca 2022. Poiskal sem jo v knjižnici Zdravstvene fakultete in na spletu. Rezultati: Ugotovil sem, da je pri uporabi besed boljše, manjše, večje in ostalih potrebno biti previden, ker so precej subjektivne. V določenih točkah so različne raziskave iste tematike prišle do različnih zaključkov. Razprava in zaključek: Zaradi nujnosti uporabe vključitvenih in izključitvenih kriterijev sem odstranil veliko strokovne literature, ki bi morda lahko bila uporabna. Na RSŠ vpliva več različnih dejavnikov in posameznih delov rentgenskega aparata. Za oceno RSŠ končnega rentgenograma moramo vključiti oceno DQE, ki upošteva prispevke šuma od vhoda do izhoda.Introduction: For a radiologist, diagnostic imaging methods aim to identify a specific state through a radiograph. Therefore, a radiograph needs to be of sufficient quality. One of the quality criteria is the signal-to-noise ratio (SNR). There are electronic and structural noises because of digitalization and quantum noise which radiological engineers can influence the most. Besides the exposure conditions, the effect on SNR has also many other factors. Radiological engineers are responsible for a good enough SNR. Together with today’s digital radiography, not knowing the theories of the profession and unprofessional work can result in a good quality image. However, the patient\u27s absorbed dose is greatly exceeded. Purpose: The purpose of the thesis was, with the help of a systematic review of the literature, to present the various factors influencing the SNR, how they affect the SNR and its subsequent removal from a digital radiograph, and to discuss the results of the research with the school literature used at the University of Ljubljana Faculty of Health Sciences. The aim was to learn how to write a thesis according to predefined rules. Methods: In the thesis, I used the descriptive method with a systematic overview of the literature. I searched for literature in October 2020, April 2021, February 2022, and March 2022. I found it in the library of the Faculty of Health Sciences and online. Results: I found out that one has to be careful when using the words better, smaller, bigger, and others because they are vastly subjective. At certain points, different research on the same topic has come to various conclusions. Discussion and Conclusion: Because of the necessity of using inclusion and exclusion criteria, I removed a lot of literature that might have been useful. The SNR is influenced by several different factors and individual parts of the X-ray machine. To evaluate the SNR of the final radiograph, we need to include a DQE evaluation that takes the noise contributions from input to output into account