Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Povzetek: Radiochromic films have many applications in radiology and radiation therapy. Generally, the dosim-etry system for radiochromic film dosimetry is composed of radiochromic films, flatbed scanner, and film analysis soft-ware. The purpose of this work is to present the effectiveness of a protocol for accurate radiochromic film dosimetry using Radiochromic.com as software for film analysis.Materials and methods. Procedures for image acquisition, lot calibration, and dose calculation are explained and analyzed. Radiochromic.com enables state-of-the-art models and corrections for radiochromic film dosimetry, such as the Multigaussian model for multichannel film dosimetry, and lateral, inter-scan, and re-calibration corrections of the response.Results. The protocol presented here provides accurate dose results by mitigating the sources of uncertainty that affect radiochromic film dosimetry. Conclusions. Appropriate procedures for film and scanner handling in combination with Radiochromic.com as software for film analysis make easy and accurate radiochromic film dosimetry feasible.
Ključne besede: radiochromic film, dosimetry, protocol
Objavljeno v DiRROS: 22.07.2024; Ogledov: 144; Prenosov: 76
Celotno besedilo (1,85 MB)
Gradivo ima več datotek! Več...

Povzetek: In radiotherapy, field sizes are defined in terms of the dimensions of the irradiation area. However, geometric square fields result in irradiation areas with rounded corners, which become almost elliptical for small fields. Superellipses are a family of curves encompassing shapes lying between ellipses and rectangles. The purpose of this work was to analyze the advantages and disadvantages of a novel approach that describes small-field sizes with superellipses. Square fields with nominal side lengths ranging from 0.5 to 10 cm were irradiated with two different linacs using 6 and 10 MV photon beams with and without flattening filters. Field size dimensions and output factors were measured by employing radiochromic films and the Radiochromic.com software. An alternative definition of equivalent square small-field size based on the superellipse (Sse) was introduced. The degree n of the superellipse for 10 cm nominal fields measured between 14.8 % 1.0 to 27.7 % 1.9. However, it decreased with the field size, down to between 2.26 % 0.10 and 2.64 % 0.15 for 0.5 cm nominal side lengths. A relation between the degree n and the equivalent square small-field size (Sclin) as defined by Cranmer-Sargison et al. [%A methodological approach to reporting corrected small field relative outputs,% Radiotherapy and Oncology 109, 350%355 (2013)] was found. For nominal side lengths of 10 cm, Sse was between 0.34 % 0.04% and 0.10 % 0.01% smaller than Sclin, while for 0.5 cm nominal side length Sse was between 9.5 % 0.6% and 7.4 % 0.7% smaller than Sclin. There was no significant difference in the goodness of the regression between using Sse or Sclin to fit field output factors with the function proposed by Sauer and Wilbert. Small fields were found to be more accurately characterized with superellipses. The advantages and disadvantages of describing field sizes with superellipses were examined. Field output factors can be derived with equivalent square small-field sizes based on the superellipse approach.
Ključne besede: superellipsa, small fields, dosimetry, radiotherapy
Objavljeno v DiRROS: 07.09.2022; Ogledov: 552; Prenosov: 344
Celotno besedilo (2,84 MB)
Gradivo ima več datotek! Več...