Vpliv dodatne filtracije in pospeševalne napetosti na dozo za pacienta pri slikanju medenice : diplomsko delo

Grah, Jan (author), Ščančar, Tami (author), Škrk, Damijan (mentor), Mekiš, Nejc (comentor), Medič, Mojca (reviewer)

Uvod: Rentgenska svetloba je elektromagnetno valovanje z visoko frekvenco in majhno valovno dolžino. Snop rentgenskih fotonov, ki izhaja iz rentgenske cevi ima širok energijski spekter. Ko sevanje prehaja skozi objekt, se večina fotonov z nizko energijo absorbira v prvih nekaj centimetrih tkiva, le tisti z visoko energijo lahko prehajajo skozi objekt in dosežejo slikovni sprejemnik. Pri preiskavi se izvaja kompromis med najmanjšo dozo, ki jo radiološki inženirji omogočijo za nastanek radiograma in optimalno kakovostjo le tega – ALARA princip. Namen: Namen diplomske naloge je ugotoviti kakšen vpliv ima dodatna filtracija ter pospeševalna napetost na dozo, ki jo prejme pacient pri slikanju medenice. Metode dela: Prvi del diplomske naloge obsega predvsem pregled literature. V nadaljevanju pa sledi eksperimentalna metoda. Preverila sva kakšen je vpliv dodatne filtracije in pospeševalne napetosti na dozo pacienta pri slikanju medenice v AP projekciji. Najprej sva izvedla slikanje z lastno filtracijo, nato pa sva postopoma dodajala dodatne filtre iz aluminija in bakra. Merili smo DAP, razdaljo med goriščem in objektom. Izračunali smo efektivno dozo in dozo na določene organe, s programom PCXMC 2.0. Rezultati: Rezultati so pokazali, da se DAP povečuje s povečevanjem anodne napetosti. To lahko pojasnimo s tem, da se ob večanju anodne napetosti povečuje povprečna energija rentgenskih fotonov. Produkt toka in časa se povečuje pri povečevanju debeline dodatnih filtrov Al in Cu. Pri uporabi debelejših filtrov se DAP zniža. Dokazala sva tudi, da se efektivna doza ob povečanju debeline dodatnih filtrov ne zmanjšuje. Zanimalo naju je tudi, če se ob nižanju DAP-a niža tudi doza na organe. Iz podatkov meritev, je mogoče zaključiti, da se ob večanju debeline filtrov DAP zmanjša, doza na organe pa se poveča. Razprava in zaključek: Ugotovila sva, da je v praksi smiselno uporabljati dodatno filtracijo takrat, ko uporabljamo filtracijo 0,3 mm bakra, saj z njo znižamo dozo na večino organov. Naloga radiološkega inženirja je, da skrbi za čim nižjo dozo in ob optimalni kvaliteti rentgenograma.

• Language: Slovenian
• Keywords: diplomska dela, radiološka tehnologija, magnetna resonanca, računalniška tomografija, ALARA princip, produkt doze in površine slikovnega polja, vstopna kožna doza, aluminij, baker, anodni tok
• Work type: Bachelor thesis/paper
• Typology: 2.11 - Undergraduate Thesis
• Organization: ZF - Faculty of Health Sciences
• Place of publishing: Ljubljana
• Publisher: [J. Grah, T. Ščančar]
• Year: 2022
• Number of pages: 39 str.
• PID: 20.500.12556/RUL-142026
• UDC: 616-07
• COBISS.SI-ID: 126394115
• Publication date in RUL: 17.10.2022

GRAH, Jan and ŠČANČAR, Tami, 2022, Vpliv dodatne filtracije in pospeševalne napetosti na dozo za pacienta pri slikanju medenice : diplomsko delo [online]. Bachelor’s thesis. Ljubljana : J. Grah, T. Ščančar. [Accessed 26 April 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=142026

Secondary language

• Language: English
• Title: Effect of added filtration and tube voltage on patient dose in pelvis radiography : diploma work

Abstract

Introduction: X-rays are electromagnetic waves of high frequency and short wavelength. The beam of X-ray photons coming out of the X-ray tube has a broad energy spectrum - polychromatic radiation. When the radiation passes through an object, most of the low-energy photons are absorbed in the first few centimetres of tissue, leaving only the high-energy photons to pass through the object and reach the imaging receiver. The examination involves a trade-off between the minimum dose that radiological engineers can deliver to produce a radiograph and the optimum quality of the radiograph - the ALARA principle. Purpose: The purpose of this thesis is to determine the effect of additional filtration and accelerating voltage on the dose received by the patient during pelvic imaging. Methods. We have investigated the effect of additional filtration and accelerating voltage on the patient dose when imaging the pelvis in AP projection. First, we performed the imaging with self-filtration, and then we gradually added additional filters made of aluminium and copper. We measured the DAP, the object focal distance, from which we then calculated the VKD. We also calculated the effective dose and the dose to specific organs, using the PCXMC 2.0 software. This programme uses Monte Carlo simulation. The method is based on the calculation of photon transport, which depends on stochastic mathematical simulations of the interactions between photons and matter. Results. This can be related to the fact that the average energy of the X-ray photons increases with increasing anodic voltage. Also, the mAs increases with increasing thickness of the additional Al and Cu filters. We have also shown that the effective dose does not decrease with increasing thickness of the additional filters. We were interested to see if, as DAP decreases, the dose to the organs also decreases. From the measurement data obtained, it can be said that as the thickness of the filters increases, the DAP decreases, but the dose to the organs increases. The final finding was that when using larger filter thicknesses, the DAP decreases. Discussion and conclusion: We concluded that in practice it makes sense to use additional filtration as it reduces the dose to the patient. It is the task of the radiological engineer to keep the dose as low as possible and to optimise the quality of the radiograph.

• Keywords: diploma theses, radiologic technology, magnetic resonance imaging, computed tomography, ALARA principle, dose area product, entrance skin dose, aluminium, copper, milliamperage