Vpliv razdalje objekt—slikovni sprejemnik na dozno obremenitev : diplomsko delo

Budin, Kaja (author), Medič, Mojca (mentor)

Uvod: V okviru diplomskega dela smo ugotavljali, kako sprememba razdalje gorišče-slikovni sprejemnik vpliva na dozno obremenitev pacientov z ionizirajočim sevanjem. Spreminjali smo razdaljo objekt—slikovni sprejemnik in gorišče slikovni sprejemnik in prilagodili ekspozicijske pogoje tako, da je bila doza na slikovni sprejemnik enaka, ter preverili z naknadnim merjenjem ekspozicijskega indeksa, da bi ohranili enako kontrastno ločljivost radiograma. Namen: Namen diplomskega dela je bil ugotoviti, kako razdalja objekt?slikovni sprejemnik vpliva na dozno obremenitev preiskovanca. Ekspozicijske pogoje smo uravnavali tako, da je bil ekspozicijski indeks enak, ker smo želeli, da na kontrastnost slike ne bi vplivalo nižje razmerje signal-šum. Metode dela: V okviru diplomskega dela smo izvajali več meritev. Najprej smo spreminjali razdaljo objekt-slikovni sprejemnik v razponu od 10 cm do 50 cm za 5 cm, najprej pri razdalji gorišče-slikovni sprejemnik 100 cm, nato pa smo jo postopoma večali do vrednosti 140 cm. Pri vsaki meritvi smo izmerili vstopno kožno dozo. Potem smo uravnavali ekspozicijske pogoje tako, da smo se približali osnovnemu ekspozicijskemu indeksu 260 najprej pri spremembi razdalje objekt-slikovni sprejemnik, nato pa še pri spremenjenih obeh razdaljah. Prav tako smo pri vsaki meritvi izmerili vstopno kožno dozo. Rezultati: Ugotovili smo, da se vstopna kožna doza linearno povečuje, če povečujemo razdaljo objekt?slikovni sprejemnik, razdaljo gorišče–slikovni sprejemnik pa pustimo nespremenjeno. Pri spremembi obeh razdalj objekt?slikovni sprejemnik in gorišče–slikovni sprejemnik pa se povečujeta eksponentno. Kadar spreminjamo obe razdalji moramo ekspozicijske pogoje bolj povečevati za ohranitev podobnega ekspozicijskega indeksa, kot pa takrat, ko spreminjamo samo razdaljo objekt–slikovni sprejemnik. Razprava in zaključek: Z večanjem razdalje objekt?slikovni sprejemnik se povečuje vstopna kožna doza oziroma dozna obremenitev preiskovanca. Z istimi meritvami smo prav tako dokazali, da vstopna kožna doza ostaja konstanta in se ne povečuje kadar sta povečani obe razdalji hkrati.

• Language: Slovenian
• Keywords: razdalja objekt-slikovni sprejemnik, razdalja gorišče-slikovni sprejemnik, radiološka fizika, vstopna kožna doza
• Work type: Bachelor thesis/paper
• Organization: ZF - Faculty of Health Sciences
• Year: 2019
• PID: 20.500.12556/RUL-110425
• COBISS.SI-ID: 5686379
• Publication date in RUL: 14.09.2019

Secondary language

• Language: English
• Title: The impact of object to image receptor distance on patient dose : diploma work

Abstract

Introduction: In the course of the thesis, we investigated how the object to image receptor distance influenced on the dose load of patients. We were changing the object to image receptor distance and the source to image receptor distance by adjusting the exposition conditions so that the dose on image receptor distance remained equal. We checked this by measuring the exposure index to preserve the contrast resolution of the radiogram. Purpose: The purpose of the diploma work was to find out how the object to image receptor distance influenced on the dose load of a patient. We regulated the exposition conditions in a way that the exposure index remained the same, in order to stop the influence of the lower signal noise ratio on the contrast resolution of the radiogram. Methods: In the course of the thesis we performed several measurements. First, we were changing the object to image receptor distance in the range from 10 to 50 cm for 5 cm, initially at the source to image receptor distance 100 cm and afterwards we gradually raised it to 140 cm. In each assessment we measured the entrance skin dose. Then we regulated the exposition conditions so that we got closer to the basic exposition index 260, first when we changed the object to image receptor distance and later again when both distances were changed. We also measured the entrance skin dose at each assessment. Results: We got to a conclusion that the entrance skin dose increases linearly if we increase the object to image receptor distance and leave the source to image receptor distance unchanged. However, as both distances change, the object to image receptor and the source to image receptor increase exponentially. When changing both distances, the exposition conditions need to be increased more in order to maintain a similar exposure index than when only the object to image receptor distance is changed. Discussion and conclusion: By increasing the distance between the object and image receptor the entrance skin dose or the dose load of the subject increases as well. With the same measurements, we also proved that the entrance skin dose remains constant and does not increase when both distances are increased at the same time.

• Keywords: object to image receptor distance, source to image receptor distance, radiology physics, entrance skin dose