Dose‐mean lineal energy values for electrons by different Monte Carlo codes: Consequences for estimates of radiation quality in photon beams

2021 ◽  
Author(s):  
Lennart Lindborg ◽  
Jan Lillhök ◽  
Ioanna Kyriakou ◽  
Dimitris Emfietzoglou
2011 ◽  
Vol 10 (4) ◽  
pp. 261-271 ◽  
Author(s):  
James C.L. Chow ◽  
Amir M. Owrangi

AbstractWe study how mucosal dose in the oral or nasal cavity depends on the irradiated small segmental photon fields varying with beam energy, beam angle and mucosa thickness. Dose ratio (mucosal dose with bone underneath to dose at the same point without bone) reflecting the dose enhancement due to the bone backscatter was determined by Monte Carlo simulation (EGSnrc-based code), validated by measurements. Phase space files based on the 6 and 18 MV photon beams with small field size of 1 × 1 cm2, produced by a Varian 21 EX linear accelerator, were generated using the BEAMnrc Monte Carlo code. Mucosa phantoms (mucosa thickness = 1, 2 and 3 mm) with and without a bone under the mucosa were irradiated by photon beams with gantry angles varying from 0 to 30°. Doses along the central beam axis in the mucosa and the dose ratio were calculated with different mucosa thicknesses. For the 6 MV photon beams, the dose at the mucosa-bone interface increased by 44.9–41.7%, when the mucosa thickness increased from 1 to 3 mm for the beam angle ranging from 0 to 30°. These values were lower than those (58.8–53.6%) for the 18 MV photon beams with the same beam angle range. For both the 6 and 18 MV photon beams, depth doses in the mucosa were found to increase with an increase of the beam angle. Moreover, the dose gradient in the mucosa was greater for the 18 MV photon beams compared to the 6 MV. For the dose ratio, it was found that the dose enhancement due to the bone backscatter increased with a decrease of mucosa thickness, and was more significant at both the air-mucosa and mucosa-bone interface. Mucosal dose with bone was investigated by Monte Carlo simulations with different experimental configurations, and was found vary with the beam energy, beam angle and mucosa thickness for a small segmental photon field. The dosimetric information in this study should be considered when searching for an optimized treatment strategy to minimize the mucosal complications in the head-and-neck intensity-modulated radiation therapy.


2011 ◽  
Vol 99 ◽  
pp. S515 ◽  
Author(s):  
D. Lazaro-Ponthus ◽  
L. Guérin ◽  
A. Batalla ◽  
T. Frisson ◽  
D. Sarrut
Keyword(s):  

2012 ◽  
Vol 47 (7) ◽  
pp. 501-503 ◽  
Author(s):  
Xuetao Wang ◽  
Jinhan Zhu ◽  
Shaowen Chen ◽  
Qiang Tang ◽  
Xiaowei Liu

2009 ◽  
Vol 93 (3) ◽  
pp. 645-653 ◽  
Author(s):  
Irina Fotina ◽  
Peter Winkler ◽  
Thomas Künzler ◽  
Jochen Reiterer ◽  
Isabell Simmat ◽  
...  

Author(s):  
Sumalee Yabsantia ◽  
Sivalee Suriyapee ◽  
Nakorn Phaisangittisakul ◽  
Sornjarod Oonsiri ◽  
Taweap Sanghangthum ◽  
...  

Abstract Introduction: This study aims to experimentally determine field output factors using the methodologies suggested by the IAEA-AAPM TRS-483 for small field dosimetry and compare with the calculation from Monte Carlo (MC) simulation. Methods: The IBA-CC01, Sun Nuclear EDGE and IBA-SFD detectors were employed to determine the uncorrected and the corrected field output factors for 6 MV photon beams. Measurements were performed at 100 cm source to axis distance, 10 cm depth in water, and the field sizes ranged from 1 × 1 to 10 × 10 cm2. The use of field output correction factors proposed by the TRS-483 was utilised to determine field output factors. The measured field output factors were compared to that calculated using the egs_chamber user code. Results: The decrease in the percentage standard deviation of the measured three detectors was observed after applying the field output correction factors. Measured field output factors using CC01 and EDGE detectors agreed with MC values within 3% for field sizes down to 1 × 1 cm2, except the SFD detector. Conclusions: The corrected field output factors agree with the calculation from MC, except the SFD detector. CC01 and EDGE are suitable for determining field output factors, while the SFD may need more implementation of the intermediate field method.


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