20.500.12556/RUL-161232 Izračun doze konvergentnega rentgenskega žarka Dose calculation of converging X-ray beam Konvergentna rentgenska leča je nov pristop v radioterapiji, kjer namesto visokoenergijskih žarkov z energijo nekaj MeV uporabljamo nizkoenergijske žarke z energijo nekaj deset keV, ki jih z lečo primerne sestave usmerimo v gorišče globine deset in več cm v tkivu. Porazdelitev doze v tumorju izračunamo z metodo Monte Carlo, ki je sicer zelo točna, a zamudna, zato si računanje olajšamo z uporabo približkov. V nalogi smo preverili uporabnost metode CCC za računanje doze konvergentnega rentgenskega žarka. Metoda vsebuje prosti parameter, ki mu pravimo model žarka in določa porazdelitev vrednosti TERMA. S poenostavljeno konvolucijo vrednosti TERMA in točkovnega doznega jedra dobimo dozo. Model žarka smo umerili, da se izračunana doza čim bolj prilegala Monte Carlo simulirani dozi. Izračunano dozo smo validirali s pomočjo funkcije gama s parametri $\Delta D = 1\%$ in $\Delta d = 1$ mm. Račun z metodo CCC je zanesljiv in 200-krat hitrejši od simulacije Monte Carlo. Preverili smo tudi robustnost doze na postavitvene napake. Ker je doza v okolici doze razpotegnjena vzdolž globine, bodo odstopanja v smer žarka imela manjši vpliv kot tista pravokotno na smer žarka. The convergent X-ray lens is a new approach in radiotherapy, where instead of high-energy beams with an energy of a few MeV, we use low-energy beams with an energy of a few tens of keV, which are directed with a lens of an appropriate composition to a focal point tens of centimeters or more deep in the tissue. The dose distribution in the tumour can be calculated by a Monte Carlo simulation, which is accurate but time-consuming, so the calculation is simplified with approximations. In this thesis, we have tested the applicability of the CCC method to calculate the dose of a convergent X-ray beam. The method contains a free parameter, called the beam model, which determines the TERMA distribution. A convolution of the TERMA and the dose point kernel yields the dose. We have calibrated the beam model to fit the calculated dose to the Monte Carlo simulated dose. The calculated dose was validated using a gamma function with parameters $\Delta D = 1\%$ and $\Delta d = 1$ mm. The CCC calculation is reliable and 200-times faster than the Monte Carlo simulation. The robustness of the dose to positional errors has also been verified. Since the focused dose is elongated along the depth, errors along the beam direction are less severe than those in the direction perpendicular to the beam. radioterapija konvergentna rentgenska leča TERMA funkcija gama algoritem CCC optimizacija model žarka robustnost plana radiotherapy convergent X-ray lens TERMA gamma function CCC algorithm optimization beam model plan robustness true false false Slovenski jezik Angleški jezik Magistrsko delo/naloga 2024-09-08 08:15:04 2024-09-08 08:15:16 2025-08-08 13:41:37 0000-00-00 00:00:00 2024 0 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 142692 206777603 12834.pdf 12834.pdf 1 038B033989FE72452999F671953261E3 a7eba3c665a5cc2dabcd4c42966716ed337facf8318a4dc6c0d5c5158a58de0b b022088d-6da9-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=190119 Fakulteta za matematiko in fiziko 0 0 0