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Uvod: Med najpogostejše preiskave, ki jih opravljamo tako v ambulantni kot bolnišnični dejavnosti, štejemo CT preiskave področja trebušnih in medeničnih organov. Glede na pogostost ponavljanja tovrstnih preiskav in množično kontrolo ob naključnih najdbah, bi bilo smotrno poiskati načine zmanjševanja prejete doze ionizirajočega sevanja in količine kontrastnega sredstva. To lahko dosežemo z različnimi tehnikami slikanja pri računalniški tomografiji. Dvo-energijski CT (ang. Dual-Energy CT) nam v nasprotju s konvencionalno CT metodo (ang. Single-energy CT) omogoča boljšo kontrastno ločljivost slik za biološko oceno mehkih tkiv. Namen: Namen je bil ugotoviti ali lahko s pomočjo tehnike DECT slikanja trebušnih organov zmanjšamo dozo sevanja in količino kontrastnega sredstva ter ohranimo diagnostično kakovost slike, primerljivo s SECT metodo slikanja. Metode dela: Raziskavo smo izvedli na CT aparatu Siemens SOMATOM Drive pri 100 pacientih napotenih na CT preiskavo trebušnih in medeničnih organov (50 z DECT metodo in 50 s SECT metodo). Področje trebušnih organov smo s SECT slikali v dveh fazah – nativna in venska, medtem ko smo z DECT zajeli samo vensko fazo (iz te smo pridobili virtualno nekontrastne slike – VNC). Zbirali smo podatke o pacientovih premerih v AP smeri na transverzalnih rezih v višini zgornjega pola leve ledvice. Za vsakega pacienta smo beležili tudi več dozimetričnih parametrov – CTDIvol, DLP in efektivna doza. Meritve objektivne kakovosti slik smo opravljali z merama SNR in CNR. Podatke o kvaliteti slik smo izmerili na transverzalnih rezih nativnih in venskih faz, področja vene porte in parenhima jeter. Rezultati: Razlika v meritvah AP diametrov na CT aparatu Siemens SOMATOM Drive je med SECT in DECT znašala 1,1 cm (4,2 %) in ni pokazala statistično značilne razlike (p=0,300). Meritve CTDIvol vrednosti venskih faz med metodama SECT in DECT so pokazale statistično značilno razliko – 3,1 % (p=0,033). Skupni DLP je bil pri DECT nižji za 46,8 % od SECT in je bil statistično značilno različen (p

Introduction Pelvic radiography is one of the most frequent general radiography imaging procedures. Pelvic radiography is usually performed in the supine position, but in some cases erect imaging is performed. The aim of this study was to determine whether radiation dose and image quality differ between two different erect pelvic radiographic procedures in overweight and obese patients, with and without displacement of anterior adipose tissue. Methods This research was a two-part study. The first part of the study was to determine a suitable fat displacement band that would not produce artifacts on the resulting radiograph when fat tissue was displaced. The second part of the study was performed in a clinical setting on 60 overweight or obese patients (BMI ≥25) referred for erect pelvic imaging. Patients were randomly divided into two equal groups, half of which displaced adipose tissue from the region of interest and the other group did not. Waist and hip circumference, height, weight, dose-area- product (DAP), primary field size, source-to-skin distance, mAs, and kV were measured. Body Mass Index (BMI), entrance surface dose (ESD), and effective dose (ED) were then calculated. The resulting images were evaluated by three radiologists. Results It was found that a thin cotton triangular bandage produced no visible radiographic artefacts. In the group of patients using the fat displacement protocol, a statistically significant reduction in waist circumference (4.7%), DAP (38.5%), ESD (44%) and ED (38.7%) were observed (p < 0.05). In addition, a significant (p < 0.05) increase was found for all the observed image quality criteria and overall total image score with exception of sacroiliac joint, iliac crest and pubic/ischial rami. Conclusion Based on the results, the use of the adipose tissue displacement protocol for radiography of the pelvis and hip in the erect position in overweight and obese patients is recommended. Implications for practice The use of cotton bands to remove adipose tissue during pelvic imaging in obese and overweight patients results in a reduction of radiation dose received by the patient and improves image quality. This technique is quick, easy, and inexpensive.

Introduction According to the guidelines, the mammograms obtained in a screening program must be evaluated to ensure that the quality of the images obtained is above 75% of score 1 (perfect and good) and less than 3% of score 3 (inadequate). This is performed by a person (usually a radiographer), so subjectivity may influence the final evaluation of the images. The aim of this study was to evaluate the impact of subjectivity on breast positioning assessments on resultant screening mammograms. Materials and methods Five radiographers evaluated a total of 1000 mammograms. One radiographer was an expert in assessing mammography images, while the other four evaluators had varying levels of experience. All images were anonymized, and the ViewDEX software was used for visual grading analysis. The evaluators were divided into two groups, each with two evaluators. Each group evaluated 600 images, with 200 images identical between the two groups. All images had already been evaluated by the expert radiographer. All scores were compared using the Fleiss' and Cohen's kappa coefficient and accuracy score. Results The results from Fleiss' kappa showed fair agreement in the mediolateral oblique (MLO) projection in the first group of evaluators whereas the other results showed poor agreement. When comparing the results from Cohen's kappa a maximum value of agreement between the evaluators was moderate 0.433 [95% CI 0.264–0.587] for the craniocaudal (CC) projection and 0.374 [95% CI 0.212–0.538] for the MLO projection. Conclusions Based on our results, we can conclude that the agreement between all five raters was poor for both CC (κ = 0.165) and MLO (κ = 0.135) projections, based on the results of Fleiss' kappa statistic. The results show that the influence of subjectivity has a great impact on the evaluation of the quality of mammography images. Implications for practice Thus, the images are evaluated by a person, which has a high impact on subjectivity in the assessment of positioning in mammography. To achieve a more objective assessment of the images and the resulting agreement between the evaluators, we would propose to change the method of assessment. The images could be evaluated by two persons, and in the event of a discrepancy, the images would be evaluated by a third person. A computer programme could also be developed that would allow a more objective evaluation based on the geometric characteristics of the image (angle and length of the pectoral muscle, symmetry, etc.)

Uvod: Filtracija je proces oblikovanja jakosti izhodnega snopa rentgenskih fotonov pri kateri je namen, da se poveča delež fotonov, ki so uporabni za nastanek rentgenske slike in zmanjša delež fotonov, ki povečujejo dozo na pacienta. V radiologiji je snop filtriran na dveh nivojih in sicer z lastno in dodatno filtracijo. Namen: Namen diplomskega dela je bil raziskati namen uporabe filtracije in različnih filtrov ter njihov vpliv na rentgenske žarke. Metode dela: Za pisanje diplomskega dela smo uporabili deskriptivno metodo dela s sistematičnim pregledom literature. Navedene članke smo iskali v slovenskem in angleškem jeziku v različnih podatkovnih bazah v časovnem obdobju od novembra 2021 do marca 2022. Rezultati: Predstavili smo ugotovitve člankov, ki smo jih uporabili pri sistematičnem pregledu literature. Poudarek je bil na vrstah filtracije in njen vpliv na rentgenske žarke ter na dozno obremenitev pacienta, kot tudi vpliv na kakovost slike. Kot zanimivost omenimo grafit kot možen filter rentgenskih žarkov. Razprava in zaključek: Ugotovili smo, da dosledna uporaba filtracije zniža pacientovo dozo brez, da znatno poslabša kakovost slike, zato je uporaba filtracije v radiologiji pomembna. Iz literature smo razbrali, da je najboljša filtracija kombinacija obeh filtrov, aluminija in bakra. Introduction: Filtration is a process of shaping the strength of the output beam of X-rays in which the purpose is to increase the proportion of photons that are useful fot the formation of X-ray images and reduce the proportion of photons that increase the patients dose. In radiology the beam is filtered on two levels, with its own and with additional filtration. Purpose: The purpose of the thesis was to investigate the use of filtration and various filters and their impact on X-rays. Methods: A descriptive method of work with a systematic review of the literature was used to write the diploma thesis. We searched for the mentioned articles in Slovenian and English language on various databases in the period from November 2021 to March 2022. Results: We presented the findings of the articles we used in a systematic review of the literature. The emphasis was on the types of filtration and its impact on X-rays and on the dose for the patient, as well as the impact on image quality. As a curiosity we mention a posibility of graphite being a possible X-ray beam filter. Discussion and conclusion: We have found out that consistent use of filtration lowers the patient’s dose without significantly impairing image quality, so the use of filtration in radiology is important. We have learned from the literature that the best filtration is a combination of both filters, aluminum and copper.

Uvod: Ekspozicijski pogoji in pravilna izbira le teh, je zelo pomembna za kakovostno izvedbo ekspozicije. Ekspozicijski pogoji so napetost, anodni tok in ekspozicijski čas. V primeru, da se radiološki inženir odloči spremeniti ekspozicijske pogoje, mora vedeti, da bo le ta sprememba vplivala na kakovost slike in dozno obremenitev pacienta. Namen: Namen diplomskega dela je bil predstaviti ekspozicijske pogoje v klinični praksi in primerjati le te z mednarodnimi priporočili. S pomočjo ankete sem skušal ugotoviti razlike med samimi ekspozicijskimi pogoji v različnih zdravstvenih ustanovah in primerjati ekspozicijske parametre z mednarodnimi priporočili. Metode dela: Izdelava diplomske naloge je zajemala deskriptivno in raziskovalno metodo. Deskriptivna metoda oziroma opisna metoda je zajemala preglede tuje in domače literature. Raziskovalna metoda pa je zajemala izdelavo anketnega vprašalnika, ki je temeljila na vprašanjih o ekspozicijskih pogojih, ki jih uporabljajo zdravstvene ustanove v praksi. Rezultati: Anketni vprašalnik je bil poslan 21 zdravstvenim ustanovam v Sloveniji. Le tega je izpolnilo je izpolnilo 10 zdravstvenih ustanov, kar pomeni 48 % vseh zdravstvenih ustanov. Pri slikanju glave v AP/PA, ustrezno velikost gorišča uporablja 56 % anketiranih zdravstvenih ustanov. Pri slikanju zgornjega uda zdravstvene ustanove upoštevajo priporočene vrednosti pospeševalne napetosti v 65 %. Mednarodna priporočila glede ustrezne uporabe pospeševalne napetosti se najmanj upoštevajo pri slikanju goleni AP in stransko. V mednarodnih priporočilih je navedeno, da se slikanje nadlahti AP in stransko izvaja z avtomatskim nadzorom ekspozicije. Torej, kar 30 % zdravstvenih ustanov pri tem rentgenskem slikanju uporablja elektronski nadzor ekspozicije. Razprava in zaključek: V osrednji Sloveniji, kjer uporabljajo nižje pospeševalne napetosti v primerjavi z drugima dvema regijama bo pri istem slikanju višja dozna obremenitev in boljša kontrastna ločljivost rentgenograma. Več kot polovica zdravstvenih ustanov uporabljajo pospeševalne napetosti, ki so v skladu z mednarodnimi priporočili. Zdravstvene ustanove, ki ne upoštevajo mednarodnih priporočil napetosti, jih večina uporablja nižje vrednosti od mednarodnih priporočil. Zaradi uporabe nizkih energij je pri teh rentgenskih slikanjih prisotna boljša kontrastna ločljivost slike, a hkrati tudi večja dozna obremenitev pacienta. Pri pravilni izbire nadzora ekspozicije glede na mednarodna priporočila, večina zdravstvenih ustanov to priporočilo upošteva. Introduction: Exposure conditions and their proper selection are very important for the quality of exposure. Exposure conditions are voltage, anode current and exposure time. In case the radiological engineer decides to modify the exposure conditions, he needs to know, that this change will impact the image quality and dose load of the patient. Purpose: The purpose of the graduation thesis was to present the exposure conditions in clinical practice and compare them with international recommendations. With the help of a survey, I tried to identify the differences between exposure conditions in different health care institutions and compare the exposure parameters with international recommendations. Methods: The graduation thesis was written using the descriptive and research method. The descriptive method consisted of the review of foreign and domestic literature. The research method consisted of the preparation of the survey questionnaire, which included questions about exposure conditions, used by health care institutions in practice. Results: The survey questionnaire was sent to 21 health care institutions in Slovenia. It was completed by 10 health care institutions, which represent 48% of all health care institutions. In case of head imaging in AP/PA, appropriate focal size is used by 56% of the questioned health care institutions. In case of upper limb imaging, health care institutions follow the recommended values of acceleration voltages in 65%. International recommendations regarding proper usage of acceleration voltages are the least followed in AP and side imaging of the shin. International recommendations state that AP and side imaging of the upper arm are performed with automatic exposure control. This means that 30 % of health care institutions use electronic exposure control for this type of x-ray imaging. Discussion and conclusion: In central Slovenia, where they use slower acceleration voltages compared to the other two regions, there will be greater dose load and better contrast resolution of the radiograph by performing the same imaging. More than half of health care institutions use acceleration voltages, which are in compliance with international recommendations. Health care institutions, which do not comply with international recommendations for voltage, mostly use lower values than recommended. Because of the use of lower energies, this x-ray imaging shows better contrast quality of the image and higher dose load of the patients. In the appropriate selection of exposure duration control according to international recommendations, the majority of health care institutions complies with this recommendation.

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's 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.

Uvod: Najpogosteje uporabljena radiografska projekcija pri slikanju medenice in kolkov je AP projekcija v ležečem položaju, vendar nekateri menijo, da bi bilo bolje izvajati slikanje medenice stoje, saj bi s tem dobili diagnostično bolj uporabne informacije. V predhodni študiji, kjer so primerjali AP slikanje medenice stoje in leže pa so poročali o višji dozi in slabši kakovosti rentgenogramov pri slikanju medenice stoje. Namen: Namen raziskave je bil ugotoviti, ali se kakovost rentgenogramov in prejeta doza razlikujeta pri dveh različnih načinih slikanja medenice stoje - z odmikom in brez odmika mehkega tkiva. Metode dela: Meritve so bile razdeljene na dva dela. Prvi del je obsegal študijo na fantomu, kjer smo izbrali trak, ki ni povzročal vidnih artefaktov na rentgenogramu. S tem trakom so si pacienti v drugem delu študije umaknili tkivo s področja slikanja. Drugi del študije je bil izveden na 60-ih pacientih, ki so bili napoteni na rentgensko slikanje medenice stoje. Bili so naključno razdeljeni v dve skupini z enakim številom. Polovica jih je umaknila tkivo s področja slikanja, druga polovica pa ne. Pri vseh smo izmerili obseg pasu in bokov, telesno višino in maso, DAP, velikost polja, razdaljo med goriščem in objektom slikanja, tokovni sunek (mAs) in napetost (kV). Naknadno smo iz meritev še izračunali indeks telesne mase, vstopno kožno dozo in efektivno dozo. Dobljene slike so ocenili trije radiologi. Rezultati: V prvem delu raziskave smo ugotovili, da tanka trikotna ruta ne povzroča artefaktov na rentgenogramu. Opazili smo statistično značilne razlike v obsegu pasu pred in po umiku mehkega tkiva (p

Uvod: Primarni rentgenski snop omejimo z zaslonko, ki je vgrajena pod ohišje rentgenske cevi. Uporaba zaslonke je pomembna zaradi dveh stvari, in sicer zaradi zmanjšanja izpostavljenosti nepotrebnemu sevanju in zmanjšanja vpliva sipanega sevanja. Namen: Želeli smo prikazati, kako dosledno radiološki inženirji uporabljajo zaslonko in kdaj so manj pozorni oz. je ne uporabljajo in kako poznajo njen namen uporabe. Metode dela: V teoretičnem delu smo uporabili deskriptivno metodo in pregledali domačo in tujo strokovno literaturo. V praktičnem delu pa smo v času klinične prakse opazovali, kako dosledno radiološki inženirji uporabljajo zaslonko. Po koncu prakse smo še izvedli anketiranje inženirjev. Rezultati: Pri opazovanju smo ugotovili, da so radiološki inženirji v 81 % ustrezno dodatno zaslonili polje, v 15 % so pustili polje v velikosti slikovnega sprejemnika in le v 4 % so pustili polje odprto večje od velikosti slikovnega sprejemnika. Z rezultati anketnega vprašalnika smo ugotovili, da 62 % radioloških inženirjev pozna namen uporabe zaslonke, hkrati pa smo ugotovili, da moški bolje poznajo vpliv zaslonke in kdaj je zaslanjanje optimalno. Razprava in zaključek: Ugotovili smo, da radiološki inženirji v večini (81 %) dosledno uporabljajo zaslonko, da so v 69 % manj pozorni na uporabo zaslonke na urgentni diagnostiki, v 38 % pri starejših in v 31 % v naglici. Vsi inženirji pa so bolj pozorni pri slikanju otrok in manj pozorni pri slikanju starejših. Introduction: X-ray beams are limited by using a collimator which is built in underneath the housing of the x-ray pipe. Using the collimator is important for two things. It lowers the dose on the patient as well as lowers the effect of scattered radiation. Purpose: We were trying to show how often do radiologic technologists use the collimator or when they don't and if they know the purpose of using it. Methods: In the theoretical part we used a descriptive method where we looked through domestic and foreign literature. Then we observed if radiologic tecnologist use a collimator at their work in a hospital. After the observaiton we included them in a survey. Results: With our observation we noticed that in 81% the radiologic technologist use the collimator accordingly, in 15% the field of collimation is left opened to the size of the detector and in 4% they left the field opened more than the size of the detector. With the survey we found out that men know more about the purpose and when the collimation is optimal than women. Discussion and conclusion: With the research we found out that most of the radiologic technologist (81%) use the collimator accordingly. That in 69% they pay less attention to the collimator in the emergency room, in 38% with the older population and in 32% when they are in a hurry. All of the radiologic technologist pay more attention to collimation when examining children and less when examining the elderly.

Uvod: Slikanje ledvene hrbtenice sodi med radiološke preiskave z največjo dozno obremenitvijo v splošni radiografiji, saj bolnik prejme relativno visoko dozo ionizirajočega sevanja. Učinkovit način za zmanjšanje prejete doze pri slikanju ledvene hrbtenice je uporaba dodatne bakrene filtracije. Namen: Namen je ugotoviti, koliko se z uporabo dodatnih Cu filtrov spremeni doza sevanja pri rentgenskem slikanju ledvene hrbtenice in ali se spremeni kakovost rentgenogramov. Metode dela: Raziskavo smo izvedli v dveh delih na Siemens Multix (DR) in Siemens Vertix/Multix (CR). V prvem delu raziskave smo merili dozo (DAP) na fantomu, kjer smo naredili 5 slik v AP in 5 slik v LAT projekciji z 0 mm, 0,1 mm in 0,2 mm Cu filtracije na obeh rentgenskih aparatih. Drugi del raziskave smo izvedli na 120 pacientih, ki so bili naključno razdeljeni v 6 skupin po 20. 20 pacientov smo slikali z 0 mm, 20 pacientov z 0,1 mm in 20 pacientov z 0,2 mm Cu filtracije v AP in LAT projekciji. Pri vseh pacientih smo beležili maso in višino za izračun indeksa telesne mase (ITM), hkrati pa smo primerjali tudi DAP in efektivno dozo. Vse rentgenograme so na koncu neodvisno ocenili trije specialisti radiologi s pomočjo programa ViewDEX. Pred raziskavo smo pridobili dovoljenje Komisije Republike Slovenije za medicinsko etiko. Rezultati in razprava: Raziskava na pacientih je pokazala, da se DAP vrednosti znižajo z uporabo dodatne filtracije 0,1 mm Cu in 0,2 mm Cu pri DR in CR tehnologiji. Vrednosti efektivnih doz se pri DR tehnologiji v AP in LAT znižajo, vendar je najbolj učinkovita uporaba 0,1 mm Cu filtracije, medtem ko je pri CR tehnologiji v AP projekciji najbolj učinkovita uporaba 0,2 mm Cu, pri LAT projekciji pa so se vrednosti efektivne doze pri uporabi Cu filtrov celo zvišale. Zaključek: Na podlagi pridobljenih rezultatov lahko zaključimo, da v kolikor se uporablja dodatna filtracija bakra pri slikanju ledvene hrbtenice je ta smiselna samo za vrednost 0,1 mm Cu pri DR tehnologiji. Za bolj podkrepljene zaključke pa predlagamo še dodatne raziskave pri čemer bi imeli večji nabor pacientov s primerljivim ITM, ter da bi upoštevali dejanski spekter rtg svetlobe iz različnih naprav. Introduction: Radiography of the lumbar spine is one of the radiological examinations with the highest dose in classical radiography. The effective way to reduce the radiation dose is an application of additional Cu filters. Purpose: The purpose is to determine how radiation dose in X-ray examination of the lumbar spine is changed when using additional Cu filters and if the image quality changes. Methods: The research was carried out in two parts on Siemens Multix MT (DR) and Siemens Vertix/Multix (CR). In the first part of the study, we measured the dose on the phantom, where we made five images in the AP and five images in the LAT projection with 0 mm, 0,1 mm, and 0,2 mm Cu filter on each X-ray. The second part of the study was carried out on 120 patients, randomly divided into six groups of 20. We took images of 3 groups in the AP and LAT projection, where we examined 20 patients with 0 mm, 20 patients with 0,1 mm, and 20 patients with 0,2 mm Cu filter. We recorded the mass and height for the body mass index (BMI) for all the patients and compared DAP and effective dose. In the end, all radiographs were evaluated independently by three radiologists with the use of ViewDEX imaging software. Prior to the study, the National medical Ethics committee approval was obtained. Results and discussion: Research has shown that DAP values are reduced with the use of additional filtration 0.1 mm Cu and 0,2 mm Cu in DR and CR technology. Regarding the values of effective doses, no additional filtration led to a significant decrease somewhere, the absolute values were even increased (without statistical characteristics). Effective dose is reduced in DR technology in AP and LAT projection, but the most efficient is the use of 0,1 mm Cu filtration. In CR technology in AP projection the most efficient is the use of 0,2 mm Cu filtration, while the use of additional Cu filtration in LAT projection even increased the effective dose. Conclusion: Based on the obtained results, we can conclude that the additional copper filtration of 0.1 mm is appropriate for the lumbar spine imaging. For more substantiated conclusions, we suggest further research.

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.

Uvod: Računalniškotomografske (CT) preiskave srca in njegovega žilja z visoko pitch vrednostjo predstavljajo velik napredek pri kardioloških preiskavah zaradi dveh prednosti, krajšega časa izvedbe ter možnosti zmanjšane dozne obremenitve za preiskovanca. Z uporabo veliko višje pitch vrednosti in prospektivnega načina slikanja omogočimo zajem podatkov celotnega srca v samo eni fazi njegovega cikla. Namen: Namen naloge je ovrednotiti, katere so prednosti in slabosti tehnike z visoko pitch vrednostjo pri CT slikanju v kardiologiji na področju dozne obremenitve in kakovosti slike, ter poiskati morebitne razlike med drugo in tretjo generacijo CT sistema z dvema izvoroma. Ugotoviti želimo, kateri dejavniki pri tehniki z visoko pitch vrednostjo vplivajo na dozno obremenitev in kakovost slike, ter kakšne so posledice spreminjanja le teh. Metode dela: V diplomskem delu sva uporabili deskriptivno metodo s sistematičnim pregledom literature, ki je bila iskana v slovenskem in angleškem jeziku. Primerjali sva rezultate raziskav, izvedenih v zadnjih 10 letih, na področju tehnike z visoko pitch vrednostjo. Rezultati: Raziskave sva med seboj primerjali glede na dozno obremenitev in kakovost slike, pri čemer so rezultati razdeljeni glede na uporabljeno generacijo CT sistema z dvema izvoroma. Pri prvem podpoglavju sva se osredotočali na produkt doze in dolžine polja, CT dozni indeks ter efektivno dozo. V drugem sva omenjali razlike med kvantitativnimi in kvalitativnimi ocenami, kjer sva se poglobili tudi v pogostost pojava artefaktov. Najnižja izračunana povprečna efektivna doza je znašala 0,2 ± 0,0 mSv. Pri večini raziskav so kvalitativne rezultate tehnike z visoko pitch vrednostjo ocenili kot odlične, zelo malo pa je bilo prisotnih koronarnih segmentov z nezadovoljivo diagnostično kvaliteto. Razlike v kvantitativni oceni slik so bile med posameznimi avtorji zelo majhne. Uporaba tehnike z visoko pitch vrednostjo je avtorjem omogočala izvedbo preiskav z zelo nizkim odstotkom pojava artefaktov gibanja. Razprava in zaključek: Glede na dobljene rezultate najine raziskave lahko sklepamo, da ima tehnika z visoko pitch vrednostjo pomembno vlogo pri zniževanju dozne obremenitve pacienta in hkrati ohranjanju zadovoljive kakovosti slike. Raziskava je lahko podlaga za nadaljnje preučevanje prednosti omenjene tehnike z izvedbo meritev na fantomu, pri čemer bi lahko dobili objektivne rezultate kakovosti slik in hkrati merili dozno obremenitev. Introduction: Computed tomography (CT) examinations of heart and its vascular system with high pitch value represent great progress in cardiologic examinations because of two advantages, short scan time and the possibility of lower radiation exposure for the patient. With the use of high pitch values and prospective scanning technique we can scan the entire heart in just one phase of its cycle. Purpose: The purpose of our study was to evaluate the andvantages and disadvantages of high pitch scanning technique in cardiologic CT in the field of radiation exposure and image quality and find the differences between second and third generation of dual source CT systems. Our focus was on the factors of high pitch technique which may have the impact on radiation exposure and image quality and see if their change has any consequences. Methods: In our diploma work we used descriptive method of work with systematic literature review. The literature was searched in Slovenian and English language. We compared the results of the studies made in the last 10 years in the field of CT protocols with high pitch values. Results: The results of different studies were compared in the field of radiation exposure and image quality and separated based on the used generation of dual source CT system. In the first part our focus was on dose-lenght product, CT dose index and effective dose values. Afterwards we looked for differences in quantitative and qualitative evaluation and tried to estimate the frequency of artefact occurrence. The lowest mean value of effective dose was 0,2 ± 0,0 mSv. The results of high pitch protocols in most of the studies were graded as excellent and very few as unevaluable. The difference in quantitative evaluation was very small between the studies. The use of high pitch values enables examinations with very low percentage of moving artefact occurrence. Discussion and conclusion: Based on our results it is possible to conclude that high pitch technique has a great role in lowering the radiation dose while keeping the sufficient image quality. Our study can be a base for further research of mentioned technique and its advantages with the measurments made on CT phantom which could give us objective results of image quality and radiation exposure at the same time.

Uvod: Radiografija ledvene in torakalne hrbtenice sta področji, ki sta v samem vrhu preiskav, ki povzročajo največje sevalne obremenitve v splošni radiograifiji. Z ustrezno uporabo zaslonke po navodilih podanih v literaturi lahko močno vplivamo na zmanjšanje dozne obremenitve pacientov. Namen: Namen naloge je preveriti vpliv optimalne uporabe radiografske zaslonke na obsevanost pacientov in kakovost rentgenogramov. Metode dela: V raziskavi je sodelovalo 110 pacientov napotenih na rentgensko preiskavo ledvene in 84 pacientov napotenih na rentgensko preiskavo torakalne hrbtenice. V prvem delu raziskave je polovica pacientov slikana glede na trenutni protokol zaslanjanja, ki se uporablja v Splošni bolnišnici Dubrovnik. V drugem delu raziskave je druga polovica pacientov slikana glede na smernice za optimalno zaslanjanje primarnega polja, ki so podane v strokovni literaturi. Pri vseh pacientih smo beležili maso in višino (za izračun indeksa telesne mase), ekspozicijske pogoje, DAP in velikost primarnega polja. Iz pridobljenih podatkov pa smo z uporabo programa PCXMC izračunali efektivno dozo in absorbirano dozo na posamezne organe. Na koncu sta kakovost rentgenogramov ocenila dva zdravnika radiologa in en radiološki inženir. Rezultati in razprava: Ugotovili smo, da se z optimalno uporabo zaslonke velikost primarnega polja pri slikanju ledvene hrbtenice v AP projekciji zmanjša za 35,5 % in v stranski projekciji za 40,3 %. Kot posledica tega je bilo zmanjšanje DAP vrednosti v AP projekciji za 45,7 % ter zmanjšanje efektivne doze za 47,7 %. Pri STR projekciji nismo našli statistično značilnih razlik med skupinami pri meritvah DAP–a in efektivne doze, kar je bila posledica napačne postavitve centralnega žarka pred optimizacijo zaslanjanja. Absorbirana doza na izbrane radiosenzitivne organe se je v AP projekciji zmanjšala za povprečno 40,9 % v stranski projekciji pa za 9,5 %. Z optimalno uporabo zaslonke smo pri slikanju torakalne hrbtenice ugotovili, da je velikost primarnega polja v AP projekciji manjša za 45,4 %, v stranski projekciji pa za 40,7 %. Dokazali smo tudi nižje vrednosti DAP-a pri AP projekciji za 33,5 % in pri STR za 23,3 %. Efektivno dozo smo pri AP projekciji znižali za 53,8 % ter pri STR projekciji za 29,2 %. Povprečna absorbirana doza na izbrane organe se je v AP projekciji zmanjšala za 25,7 % in v stranski projekciji za 28,4 %. Poleg tega smo pri vseh projekcijah razen pri slikanju ledvene hrbtenice v AP projekciji ugotovili, da se z optimalno uporabo zaslonke izboljša tudi kakovost rentgenograma. Zaključek: Z izvedbo raziskave smo dokazali, da z optimalno uporabo zaslonke pri slikanju ledvene in torakalne hrbtenice vplivamo na izpostavljenost pacientov. Na ta način lahko vplivamo tudi na kakovost rentgenogramov, ki jo ne samo ohranimo, ampak še izboljšamo. Introduction: Radiography of lumbar and thoracic spine are classified as examinations which cause the greatest radiation burden in classical radiography. By the optimal usage of collimator according to the instructions given in the professional literature it's possible to greatly influence the reduction of the patients dose load. Purpose: The purpose of the research is to determine the influence of the optimal usage of collimator on patient irradiation and the image quality. Methods: The study was performed on 110 patients that were referred to the lumbar spine radiography and 84 patients that were referred to the thoracic spine radiography. For the first part of the study, half of the patients were imaged with the current collimation protocol used in the General Hospital Dubrovnik. For the second part of the study, the other half of the patients were imaged with the collimation protocol mentioned in the professional literature. For each patient DAP, image field size, exposure condtions, weight and height (for calculating the body mass index) were measured. From that data using the PCXMC program the effective dose and the absorbed organ doses were calculated. At the end, the image quality was evaluated by two radiologist and one radiologic technologist. Results and discussion: With the optimal use of the collimatior for the lumbal spine radiography we found out that the size of the primary field for the AP projection was reduced by 35,5 % and the LAT projection by 40,3 %. As a consequence, DAP value was reduced by 45,7 % and the effective dose by 47,7 % for AP projection. Regarding the LAT projection we did not find statistically different results between the groups in the DAP and the effective dose measurements which was caused by the incorrect positioning of the central beam before the optimization of collimation. The absorbed dose to selected radiosensitive organs decreased in the AP projection by an average of 40,9 % and in the LAT projection by 9,5 %. With the optimal usage of collimator in the imaging of the thoracic spine we found that the size of the primary field in the AP projection was reduced by 45,4 % and in the LAT projection by 40,7 %. The study also showed reduced values of DAP for AP projection by 33,5 % and for LAT projection by 23,3 %. The effective dose was reduced by 53,8 % for AP projection and 29,2 % for LAT projection. The mean absorbed dose to the selected organs decreased by 25,7 % in the AP projection and 28,4 % in the LAT projection. In addition, in all projections, except for the AP projection of the lumbar spine, it was found that the optimal usage of collimator improves the image quality. Conclusion: By carrying out the research we have demonstrated that optimal usage of collimator in lumbar and thoracic spine imaging has an influence on patient exposure to radiation. It also affects the image quality, which is not only preseved but rather improved.

Uvod: T2 poudarjena pulzna zaporedja so nepogrešljiva metoda pri MR slikanju trebuha. Na sliki pogosto prihaja do popačenj povezanih s premikanjem, bodisi zaradi premikanja preiskovanca ali premikanja struktur v trebuhu zaradi dihanja, peristaltike črevesja in pulziranja žil. Da se izognemo popačenjem premikanja, je bilo razvitih več različnih tehnik, ki le-ta zmanjšajo ali povsem izničijo. Namen: Ugotoviti s katerim od treh T2 TSE pulznih zaporedij z različnim načinom zajema podatkov dobimo tehnično najboljšo sliko. Primerjati in oceniti želimo kakovost slike T2 TSE pulznih zaporedij s prostim dihanjem preiskovancev. V primerjavo je vključeno T2 TSE pulzno zaporedje z uporabo dihalnega sprožilca in enaki pulzni zaporedji z uporabo PACE in BLADE tehnike slikanja. Metode dela: V raziskavo je bilo vključenih 29 pediatričnih preiskovancev. Poleg standardnega T2 TSE pulznega zaporedja z uporabo dihalnega sprožilca v transverzalni ravnini, smo v protokol dodali še T2 TSE pulzno zaporedje s PACE in BLADE tehniko slikanja. Pridobljene slike sta ocenjevala 2 neodvisna ocenjevalca. Ocenjevali smo 7 parametrov po sistemu 4-stopenjske lestvice, ki smo jo sestavili v ta namen in podali skupno oceno. Rezultati: Najboljše ocenjeno pulzno zaporedje pri večni ocenjevalnih parametrov je bilo pulzno zaporedje z uporabo dihalnega sprožilca, kar potrdi tudi skupna ocena vseh ocenjevalnih parametrov. Statistična primerjava ni pokazala značilnih razlik med tehniko z dihalnim sprožilcem in PACE tehniko, medtem ko primerjava tehnike dihalnega sprožilca in BLADE tehnike, kot tudi primerjava PACE in BLADE tehnike razkrije statistično značilne razlike med njimi. Upoštevajoč čas trajanja pulznega zaporedja, se je za najkrajšo izkazala tehnika z dihalnim sprožilcem, za najdaljšo pa PACE tehnika. Razprava in zaključek: Zaradi enostavnega zaznavanja dihalnega cikla se je tehnika dihalnega sprožilca izkazala za zelo uspešno in hitro metodo pri slikanju trebuha v otroškem obdobju. Pri PACE tehniki je na račun natančnega sledenja preponi v kombinaciji z neenakomernim dihanjem, prisotnih malce več popačenj, statistično daljši je tudi čas pulznega zaporedja. BLADE tehnika brez uskladitve z dihalnim ciklom preiskovanca se ni izkazala za uporabno pri MR slikanju trebuha otrok. Upoštevajoč ocene in čas trajanja pulznega zaporedja smo ugotovili, da je za klinično uporabo najbolj primerno pulzno zaporedje z uporabo dihalnega sprožilca. Introduction: T2 weighted pulse sequences are an essential part of MR imaging of the abdomen. Motion artefacts on MR images are caused by patient’s movements, or movement of abdominal structures due to respiration, vascular pulsation and bowel peristalsis. Several different techniques which reduce or completely eliminate such artefacts have been developed. Purpose: The purpose is to determine which of the three T2 TSE pulse sequences with different techniques of data acquisition can produce technically the best image. Three T2 TSE free-breathing pulse sequences with respiratory gating, with PACE and BLADE techniques were compared and picture quality was evaluated. Methods: 29 paediatric patients with a mean age of 7,8 years were included in the research. Besides standard pulse sequences, which includes T2 TSE pulse sequence with respiratory gating in transverse plane, also two other sequences with PACE and BLADE techniques were added. Obtained images were evaluated by 2 independent radiologists according to the 4-point scale evaluating 7 different parameters and overall score of image. Results: Best rated pulse sequence in most of the evaluation parameters, was sequence with respiratory gating, which is also confirmed by overall grade of all evaluation parameters. Statistical comparison did not show any significant differences between the technique with respiratory gating and PACE technique, while the comparison of respiratory gating and BLADE technique, as well as PACE and BLADE technique, reveals statistically significant differences between them. Considering the time of acquisitions, respiratory gated sequence was measured as shortest and PACE technique was measured as longest. Discussion and conclusion: Because of simple detection of the respiratory cycle, the respiratory gated technique has been proved to be very useful and quick technique in abdominal imaging in childhood. Since the accuracy of the diaphragmatic motion gating is combined with irregular breathing, more artefacts on PACE sequence were shown. For the same reason, acquisition time was extended. BLADE technique without synchronized breathing cycle was not suitable in children abdominal MR imaging. Taking into consideration the grades and acquisition time, the pulse sequence with respiratory gating is proven to be the most optimal in clinical use.

Uvod: Sprememba velikosti slikovnega polja vpliva na dozo, ki jo prejme pacient, hkrati pa vpliva na količino sipanega sevanja, ki nastane v pacientu in doseže slikovni receptor. Pri spreminjanju velikosti slikovnega polja je potrebno spreminjati tudi ekspozicijske pogoje, če želimo, da ostaja razmerje signal-šum na sliki enako. V primeru manjšega slikovnega polja moramo produkt toka in časa povečati. Pri tem si lahko pomagamo s faktorji spremembe ekspozicijskih pogojev pri spremembe velikosti slikovnega polja. Namen Namen diplomskega dela je ugotoviti, kako sprememba velikosti slikovnega polja vpliva na ekspozicijski indeks in dozo na pacienta ter pridobiti faktorje spremembe ekspozicijskih pogojev pri spremembi velikosti slikovnega polja za sistem računalniške radiografije. Metode dela: V diplomski nalogi smo uporabili dve metodi dela. Pri prvi metodi smo pridobili teoretične podatke s preučevanjem različne domače in tuje strokovne literature. Druga metoda dela je bila raziskava s pomočjo meritev, kjer smo spreminjali velikost slikovnega polja in merili vpliv spremembe na ekspozicijski indeks ter dozo. S pomočjo formule smo izračunali teoretične faktorje povečave ekspozicijskih pogojev. Rezultati: Pri zmanjševanju slikovnega polja se zniža ekspozicijski indeks, ko pa ekspozicijske pogoje povečamo za določen faktor, ekspozicijski indeks naraste, s tem pa se veča tudi doza. Na podlagi naših meritev moramo produkt toka in časa pri spremembi velikosti slikovnega polja z 35 × 43 cm na 24 × 30 cm izračunano povečati za faktor 1,52 (52 %), da ohranimo enak ekspozicijski indeks. Pri spremembi velikosti slikovnega polja z 24 × 30 cm na 18 × 24 cm pa moramo produkt toka in časa teoretično povečati za faktor 1,41 oziroma 41 %. Razprava in zaključek: Ko želimo izmeriti dozo, ki jo prejme pacient, je za prikaz doze bolj kot ekspozicijski indeks primeren produkt med dozo in površino. Z zmanjševanjem polja se površina obsevanega telesa zmanjšuje, zato se zmanjša tudi doza. To smo ugotovili tudi v diplomski nalogi, kadar nismo spremljali produkta toka in časa. Ugotovili smo, da se je ob enakih ekspozicijskih pogojih doza zmanjšala za približno 50 %, pri zmanjšani površini za 50 %. Introduction: Changing the size of the x-ray field affects the dose received by the patient, while at the same time influences the amount of scattered radiation that occurs in the patient and reaches the image receptor. When changing the size of the x-ray field, it is also necessary to change the exposure conditions if we want the signal-to-noise ratio in the image to remain the same. In the case of a smaller image field, the mAs must be increased. In order to do so, we can use the factors of changing the exposure conditions when resizing the x-ray field. Purpose: The purpose of this bachelor thesis is to determine how the change in the size of the x-ray field influences the exposure index and the dose received by the patient, as well as to obtain factors of changing the exposure conditions when resizing the x-ray field for the computer radiography system. Methods: Two methods were used to carry out the research. With the first method, we obtained theoretical data by studying diverse domestic and foreign professional literature. The second method of work was the measurement survey where we changed the size of the x-ray field and measured the effect of the change on the exposure index and dose. Using the formula, we calculated the theoretical factors for increasing the exposure conditions. Results: By reducing the x-ray field, the exposure index is lowered, but when the exposure conditions increase by a certain factor, the exposure index increases, thereby increasing the dose. Based on our measurements, the mAs should theoretically be increased by a factor of 1.52 (52 %) when changing the size of the x-ray field from 35 × 43 cm to 24 × 30 cm in order to maintain the same exposure index. When changing the size of the x-ray field from 24 × 30 cm to 18 × 24 cm, the mAs should theoretically be increased by a factor of 1.41 or 41%. Discussion and conclusion: When we want to measure the dose received by the patient, the product between the dose and the surface is more appropriate than the exposure index. By reducing the x-ray field, the surface of the irradiated body decreases, and therefore the dose also decreases. This is also what we found out within the framework of the present thesis when we didn't change the mAs. It was established that under the same conditions of exposure, the dose was reduced by about 50%, with a reduced area of 50%.

Uvod: Rentgensko slikanje medenice postavljamo v sam vrh najpogosteje sevalno obremenjujočih preiskav. Glede na majhno število predhodnih raziskav, bi se morali osredotočiti na zmanjšanje doz v povezavi z namestitvijo pacienta glede na položaj ionizacijskih celic AEC sistema digitalne radiografije. Namen: Namen je ugotoviti, kako se spreminja DAP, efektivna doza, absorbirana doza na organe in vpliv na kakovost slike glede na kranialno ali kavdalno namestitev pacienta pri rentgenskem slikanju medenice. Metode dela: Raziskavo smo izvedli v dveh delih na dveh digitalnih rentgenskih aparatih. V prvem delu smo merili doze na fantomu, kjer smo 10 slik posneli v HT in 10 slik v HA postavitvi. Drugi del raziskave pa smo izvedli na 200 pacientih (po sto na vsakem aparatu), ki so bili napoteni na rentgensko slikanje medenice. Merili smo DAP, velikost polja, višino in maso iz katerega smo izračunali ITM. Na podlagi predhodnih raziskav smo izračunali tudi efektivno dozo in absorbirano dozo na izbrane organe. Rentgenograme so neodvisno ocenili trije specialisti radiologi. Rezultati: Raziskava na fantomu in pacientih pri obeh rentgenskih aparatih ni pokazala statistično značilnih razlik v velikosti polja in ITM-u. DAP na Siemens Ysio pokaže 9,5% (p=0,032) razliko na fantomu in 37,3 % (p=0,002) razliko pri pacientih v prid kavdalne nastavitve. Efektivna doza je na Siemens Ysio v kavdalnem položaju nižja za 35,7% in je statistično značilno različna (p=0,002). Pri primerjanju absorbiranih doz na izbrane organe smo statistično značilno razliko izmerili pri slikanju pacientov na Siemens Ysio in sicer pri: mehurju (36,5 %), koži (35 %), spodnjemu debelemu črevesju (35 %), skeletu medenice (33 %), maternici (32,8 %), jajčnikih (32,4 %) in debelem črevesju (28,8 %). Ocene radiologov so bile za 5,4 % višje v kavdalni nastavitvi pri Siemens Ysio, drugače pa statistično značilnih razlik na fantomu ali pacientih nismo odkrili. Pri Siemens Luminus ne najdemo statistično značilnih razlik. Razprava: Zaradi položaja ionizacijskih celic se rezultati med Siemens Luminus in Ysio razlikujeta. Statistično značilne razlike v DAP-u, efektivni dozi, absorbirani dozi na izbrane organe pri zamenjavi položaja pacienta najdemo pri Siemens Ysio. Zaključek: Ob ohranitvi kakovosti slike smo pri kavdalni namestitvi na Siemens Ysio znižali DAP za 37,7 %, povprečno efektivno dozo za 35,7 % in povprečno absorbirano dozo na izbrane organe za 33,4 %. Zaključimo, da je slikanje v kavdalni namestitvi glede na ionizacijske celice priporočljiva metoda. Introduction: X-ray imaging of the pelvis is placed at the very top of the most frequent radiation-burdening investigations. According to a minority of previous studies, a reduction in doses should be concentrated in conjunction with the patient's positioning according to the position of the ionizing cells of the AEC digital radiography system. Purpose: The purpose is to determine how DAP, effective dose, doses to specific organs and image quality are changing according to cranially or caudally orientated position in the X-ray of the pelvis. Methods: The research was carried out in two parts. In the first part of the study we measured doses on the phantom, where 10 images were taken in HT and 10 in the HA layout. The second part of the study was expanded to 200 patiens, one hundred per each x-ray mashine. We measured DAP, field size, height and mass from which we calculated ITM. Then we calculated effective dose and absorbed dose for individual organs accordingly. The radiographs were independently evaluated by three radiologists. Results: The research on the phantom and patients on both x-ray machines did not show statistically significant differences in field size and ITM. DAP on Siemens Ysio shows a 9,5 % (p = 0.032) difference on the phantom and 37,3 % (p = 0.002) the difference in patients in favor of a cavalous setting. The Efective dose on Siemens Ysio is lower by 35,7 % in the HA position and is statistically significantly different (p = 0.002). In the measurement of effective doses on individual organs, the statistically significant difference was measured in patients imaging on Siemens Ysio: bladder (36.5 %), skin (35 %), lower colon (35 %), pelvis pelvis (33 %), the uterus (32,8 %), the ovaries (32,4 %) and the large intestine (28,8 %). We did not find significant differences at Siemens Luminus. Radiologists estimates were 5, 4% higher in caudally orientated position at Siemens Ysio, but otherwise statistically significant differences were not detected on the phantom or patients. Discussion: Due to the position of ionization cells, the results between Siemens Luminus and Ysio differ. Statistically significant differences in DAP, effective dose, absorbed dose to selected organs in the replacement of the patient's position can be found at Siemens Ysio.Conclusion: While preserving the image quality, using the caudally orientated position at Siemens Ysio reduced the DAP by 37,7 % and the average effective dose by 35,7 %. The mean absorbed dose to selective organs is 33,4 %. We conclude that positioning patiens caudally orientated according to ionizing cells is a method of selection.

Uvod: V okviru diplomskega dela smo ugotavljali, kako sprememba razdalje gorišče–slikovni sprejemnik vpliva na dozno obremenitev pacientov z ionizirajočim sevanjem, ne da bi ob tem spremenili ekspozicijski indeks in spremenili kakovost slike – razmerje signal-šum in posledično kontrastno ločljivost slike. Želeli smo potrditi veljavnost pravila, ki pravi, da jakost sevanja pada s kvadratom razdalje in da formula po kateri smo uravnavali ekspozicijske pogoje pripomore pri izbiri optimalnih ekspozicijskih pogojev. Namen Želeli smo ugotoviti, kako sprememba razdalje gorišče-slikovni sprejemnik vpliva na dozno obremenitev pacientov in ekspozicijski indeks, ki posledično vpliva na kakovost slike. Zaradi diagnostične uporabnosti rentgenograma, je potrebno tudi pri spremembi razdalje goriščeslikovni sprejemnik ohranjati enak ekspozicijski indeks slike, zato je namen naloge tudi, da poiščemo optimalno jakost snopa, ki pade na slikovni sprejemnik. Metode dela: V diplomskem delu smo najprej uporabili deskriptivno ali opisno metoda dela s pregledom domače in tuje strokovne ter znanstvene literature. Iskanje literature je potekalo preko bibliografske baze COBIB.SI, v knjižnici Zdravstvene fakultete Univerze v Ljubljani in splošnih knjižnicah. Podatke za praktični del smo pridobili z meritvami v radiološkem laboratoriju Zdravstvene fakultete Univerze v Ljubljani. Meritve smo opravljali na rentgenskem aparatu Multix/Vertix znamke Siemens, na fantomu roke in kolka. Ker na kakovost slike in ekspozicijski indeks posledično vpliva tudi velikost slikovnega polja, smo velikost polja omejevali ročno. Ta je bila vedno enako, in sicer pri fantomu roke in pri fantomu kolka 24 × 30 cm. Razdaljo goriščeslikovni sprejemnik smo spreminjali od osnovne vrednosti za 10 cm. Končni cilj spremembe razdalje je bil pri slikanju roke 50 cm oziroma 180 cm pri povečanju razdalje. Končni cilj spremembe razdalje pri slikanju kolka pa 65 cm oziroma 195 cm pri povečanju razdalje pri vsaki spremembi razdalje smo prilagodili tudi ekspozicijske pogoje tako, da je bila jakost sevanja, ki je padla na slikovni sprejemnik enaka. Ob vsaki vrednosti smo izmerili produkt doze in površine obsevanega predela ter odčitali ekspozicijski indeks slike. Rezultati: Rezultati so sestavljeni iz dveh delov. V prvem delu prikazujemo, kako razdalja goriščeslikovni sprejemnik vpliva na dozno obremenitev pacienta, v drugem delu pa kako prilagoditev ekspozicijskih pogojev na določeno razdaljo gorišče–slikovni sprejemnik vpliva na ekspozicijski indeks. Ugotovili smo, da z večanjem oziroma zmanjševanjem razdalje gorišče–slikovni sprejemnik doza pada oziroma narašča pri neprilagojeni ekspoziciji, pri prilagojeni pa je približno enaka. Prilagajanje ekspozicijskih pogojev po formuli kvadratnega pravila ekspozicijski indeks ohranja okoli idealnega (±6 %). Razprava in sklep: Z vidika dozne obremenitve pacienta je zelo pomembno, da prilagajamo ekspozicijske pogoje. Kot smo ugotovili, je fantom prejel ob razdalji gorišče- slikovni sprejemnik 50 cm pri nespremenjenih ekspozicijskih pogojih kar štirikrat večjo dozo, kot jo sicer prejme pri prilagojenih ekspozicijskih pogojih. Temu dejstvu je potrebno posebno pozornost posvečati v mobilni radiologiji, kjer se ekspozicijski pogoji prilagajajo tudi zmožnostim aparata in prostora, kjer se slika. Jakost sevanja na površino pada s kvadratom razdalje. To spremembo lahko izračunamo in sicer z direktnim kvadratnim pravilom, ki je bilo izpeljano iz inverznega z namenom, da radiološkim inženirjem omogoči lažji izračun sprememb ekspozicijskih pogojev ob spremembah razdalje gorišče–slikovni sprejemnik, za ohranjanje enakega razmerja signal-šum. Introduction: In the course of the thesis, we investigated how the change in the distance between the focal point and the image receiver influenced the dose load of patients without changing the exposure index and without changing the image quality - the signal to noise ratio. We wanted to confirm the validity of the rule, which states that the intensity of radiation falls with the square of the distance, and that the formula under which we were regulating the conditions of exposure contributes to the choice of optimum exposition conditions. Purpose: We wanted to find out how the change in the distance of the focal point-image receiver affects the patient's dose load and the exposure index, which consequently affects the quality of the image. Due to the diagnostic usefulness of the X-ray, it is also necessary to maintain the same signal-to-noise ratio in the change in the distance between the focal point and the image receiver, so the purpose of thesis was also to find the optimum beam intensity that falls on the image receiver. Methods: First, we used a descriptive method of work with a review of professional and scientific literature. The search for the literature was made in the data base COBIB.SI. Data for the practical part were obtained by measurements in the radiological laboratory of the Faculty of Health Sciences of the University of Ljubljana. The measurements were performed on the Siemens Multix / Vertix X-ray machine on the phantom of the arm and the hip. Because of the fact that the size of the image field affects image quality and the signal-to-noise ratio, we limited it manually to the size of 24 × 30 cm. The distance focal point - image receiver was changed from the basic value by 10 cm. The ultimate goal of the distance change when imaging the arm was 50 cm and 180 cm when increasing the distance. The final goal of the distance change when imaging the hip was 65 cm and 195 cm when increasing the distance. At each change in the distance, the exposure conditions were adjusted so that the intensity of the radiation that fell to the image receiver was the same. Each time we measured product between dose and irradiated surface and EI. Results: The results are composed of two parts. In the first section, we show how the distance of the focal point-image receiver affects the patient's dose, while the second part shows how the adjustment of the exposure conditions to a certain distance of the focal point-image receiver influences the exposure index. We found that by increasing or decreasing the distance of the focal point-image receiver the dose decreases or increases, if we do not adjust exposure. If the exposure is adjusted, than dose is mainly the same. Adjusting the exposition conditions according to the square law formula exposes the exposure index around the ideal (± 6%). Discussion and conclusion: From the point of view of the patient's dosage load, it is very important to adjust the exposure conditions. The phantom imaged at distance of 50 cm from the focal point with unadjusted exposition conditions received as four times the dose as it is received with adjusted exposition conditions. This fact requires special attention in mobile radiology, where the exposure conditions are adjusted to the capabilities of the apparatus and the space where imaging. The amount of radiation on the surface changes with the square of the distance. This change can be calculated by square law and allows radiology technicians to calculate new exposure conditions at distance change and to maintain the same signal-to-noise ratio.

Uvod: Slikanje ledvene hrbtenice je klasificirano kot preiskava z največjo dozno obremenitvijo v klasični radiografiji. Obstaja preprost, vendar učinkovit način za zmanjšanje doze sevanja in sicer zamenjava anteroposteriorne (AP) projekcije slikanja v posteroanteriorno (PA) projekcijo. Namen: Namen je ugotoviti, kako se pri uporabi PA projekcije spremeni doza ionizirajočega sevanja pri rentgenskem slikanju ledvenih vretenc ter ali PA projekcija vpliva in spremeni kakovost slike v primerjavi z AP projekcijo. Metode dela: Raziskavo smo izvedli v dveh delih. V prvem delu raziskave smo merili dozo (DAP) na fantomu, kjer smo naredili 5 slik v AP in 5 v PA projekciji. Drugi del raziskave smo izvedli na 100 pacientih, ki smo jih naključno razdelili v dve skupini po 50, nato pa slikali prvo skupino v AP in drugo v PA projekciji. Pri vseh pacientih smo beležili maso in višino za izračun indeksa telesne mase (ITM), hkrati pa smo primerjali tudi velikost polja, debelino trebuha, DAP in efektivno dozo. Vse rentgenograme so na koncu neodvisno ocenili trije specialisti radiologi. Rezultati in razprava: Raziskava na fantomu je pokazala, da je bilo polje pri PA projekciji večje za 62,6 cm2, ki pa ni statistično značilno (p = 0,310), pri AP projekciji je bil DAP manjši za 1,9 µGy m2 in tudi ni statistično značilno različen (p = 0,310), ocena rentgenogramov pa je bila boljša pri AP projekciji za 0,2, vendar tudi statistično neznačilna (p = 0,690). Meritev efektivne doze je bila pri PA projekciji manjša za 0,033 mSv, kjer smo ugotovili statistično značilne razlike (p = 0,008). Pri pacientih je bilo polje večje pri PA projekciji za 8 cm2, vendar ne statistično značilno (p = 0,391). Debelina trebuha se je pri PA projekciji statistično značilno zmanjšala za 2,4 cm (p < 10-3), prav tako tudi DAP za 16,3 µGy m2 (p = 0,009) in efektivna doza za 0,09 mSv (p < 10-3), razlike so bile statistično značilne. Ocena rentgenogramov je bila za 0,1 večja pri PA projekciji, vendar med ocenami ni bilo statistično značilnih razlik (p = 0,690). Zaključek: Rezultati so pokazali, da je uporaba PA projekcije pri slikanju ledvene hrbtenice zmanjšala DAP (26,7 %) in efektivno dozo (53,3 %) ob ohranitvi kakovosti slike, torej lahko zaključimo, da je slikanje ledvenih vretenc v PA projekciji priporočljiva metoda izbora. Introduction: Radiography of lumbar spine is classified as a relatively high dose examination in classical radiography. There is a simple but effective way to reduce the radiation dose, namely the replacement of the anteroposterior (AP) imaging projection into the posteroanterior (PA) projection. Purpose: The purpose is to determine how dose of radiation in X-ray examination of lumbar spine is changed when using the PA projection and does the PA projection have influence and change the image quality compared to the AP projection. Methods: The research was carried out in two parts. In the first part of the study we measured the dose (DAP) on the phantom, where we made 5 images in the AP and 5 images in the PA projection. The second part of the study was carried out on the 100 patients, randomly divided into two groups of 50. We took images of one group in the AP and the other in the PA projection. For all patients, we recorded the mass and height for the body mass index (BMI), and at the same time we compared the size of the field, the thickness of the abdomen, DAP and the effective dose. On the end, all radiographs were evaluated independently by three radiologists. Results and discussion: A study on the phantom showed that the field at the PA projection was 62,6 cm2 larger compared to average values of the AP projection (p = 0,310). The AP projection was even better with DAP by 1,9 μGy m2 (p = 0,310) and at the evaluation of radiographs by 0,2 (p = 0,690). The measurement of the effective dose was lower by 0,033 mSv for PA projection, where statistically significant differences were found (p = 0,008). Measurements on the patients showed that the field was larger with a PA projection by 8 cm2 (p = 0,391). The thickness of abdomen was reduced by 2,4 cm (p