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Dosimetric comparison of hippocampal avoidance wholebrain radiotherapy with flattening filter and flattening filter-free modes / 中国辐射卫生
Chinese Journal of Radiological Health ; (6): 740-745, 2022.
Article in Chinese | WPRIM | ID: wpr-965554
ABSTRACT
@#<b>Objective</b> To compare the dosimetric differences of volumetric modulated arc therapy (VMAT) with flattening filter(FF) and flattening filter-free(FFF) modes in hippocampal avoidance whole brain radiotherapy. <b>Methods</b> We included 15 patients with hippocampal-sparing whole brain radiotherapy, and designed two radiotherapy plans of FF-VMAT and FFF-VMAT for each patient. On the premise of meeting clinical dose requirements, the two plans’ dosimetry, total number of monitor units, and beam-on time were compared. <b>Results</b> There were no significant differences in the target coverage, conformity index, and dose gradient of the FF-VMAT and FFF-VMAT plans (<i>P</i> > 0.05). The <i>D</i><sub>max</sub>, <i>D</i><sub>100%</sub>, and <i>D</i><sub>mean</sub><sub> </sub>to the hippocampal tissue were significantly lower with FFF-VMAT [(15.13 ± 0.38) Gy, (7.12 ± 0.34) Gy, and (9.76 ± 0.43) Gy, respectively)] than with FF-VMAT (16.46 ± 0.56) Gy, (7.72 ± 0.28) Gy, and (10.54 ± 0.48) Gy, respectively)] (<i>P</i> < 0.05). The <i>D</i><sub>max</sub><sub> </sub>to the left and right lenses and the <i>D</i><sub>mean</sub><sub> </sub>to the left and right eyeballs with FFF-VMAT were (7.26 ± 0.43) Gy, (6.29 ± 1.13) Gy, (11.01 ± 0.94) Gy, and (9.78 ± 1.13) Gy, respectively, which were significantly lower than FF-VMAT’s corresponding doses of (8.09 ± 0.66) Gy, (7.80 ± 0.74) Gy, (11.38 ± 1.09) Gy, and (11.05 ± 0.90) Gy, respectively (<i>P</i> < 0.05). The doses to other organs at risk including the optic nerve and optic chiasm were all controlled within the safe dosage ranges, with no significant differences between the two plans (<i>P</i> > 0.05). The FFF-VMAT plan had a significantly greater number of monitor units and a significantly shorter beam-on time than the FF-VMAT plan (<i>P</i> < 0.05). <b>Conclusion</b> Both FF-VMAT and FFF-VMAT can meet the clinical requirements, with FFF-VMAT having better hippocampus and lens protection, shorter beam-on time, and higher treatment efficiency.

Full text: Available Index: WPRIM (Western Pacific) Language: Chinese Journal: Chinese Journal of Radiological Health Year: 2022 Type: Article

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Full text: Available Index: WPRIM (Western Pacific) Language: Chinese Journal: Chinese Journal of Radiological Health Year: 2022 Type: Article