Fig 1.
Radiation dose and course information.
Radiation courses are represented by individual bars, where bar height indicates prescription radiation dose. Maximum voxel EQD2 for each patient is listed at the top of each bar. Distinct PTVs are color-coded. For example, patient 1 was irradiated at three distinct PTVs, while patient 3 received four courses of radiation to 2 distinct PTVs. #Patient 3, Course 3: this volume was in the Course 2 volume but not in the Course 1 volume. *Patient 3, Course 4: this course consisted of 3 separate PTVs: 1 overlapped with the original Course 1 volume; the other 2 were distinct. Abbreviations: EQD2, equivalent total dose in 2 Gy fractions.
Table 1.
Patient, tumor, and treatment characteristics.
Fig 2.
Appearance of BRIA in a 65-year-old male two months after starting bevacizumab for recurrent right parietal glioblastoma on a) FLAIR, b) T1 post-contrast, c) DWI, and d) ADC. Abbreviations: FLAIR, fluid-attenuated inversion recovery; DWI, diffusion-weighted imaging; ADC, apparent diffusion coefficient.
Table 2.
BRIA characteristics.
Fig 3.
NTCP model of the relationship between radiation dose and probability of BRIA development.
The relationship between cumulative voxel EQD2 (Gy) and the relative probability of BRIA as observed in this cohort (blue curve) and as calculated by the logistic regression NTCP model (green curve). The blue and green shaded regions represent the upper and lower bounds of the 95% confidence intervals for the observed probability of BRIA and the logistic model from bootstrapping, respectively. The figure insert shows EQD2 values for 10, 20, and 50% probability of BRIA derived from the model. Abbreviations: EQD2, equivalent total dose in 2 Gy fractions; γ, normalized slope of the dose-response curve; EQD2x, radiation dose corresponding to an x% relative probability of BRIA development.
Fig 4.
Agreement of the logistic model with the radiation dose map and observed BRIA ROI for two representative patients.
Voxel EQD2 is represented by the blue to red scale. Panel A displays the cumulative voxel EQD2 map alongside the estimated probability of BRIA as predicted by the logistic regression model (green to pink scale) in a representative patient. Panel B demonstrates the cumulative voxel EQD2 map overlaid with the PTV (white) and the observed BRIA ROI (black) for the same patient. Panel C illustrates PTVs (white) and observed BRIA ROIs (black) in a second patient. The patient developed BRIA in one of three PTVs. Abbreviations: ROI, region of interest; EQD2, equivalent total dose in 2 Gy fractions; PTV, planning target volume.