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Fig. 6 | Radiation Oncology

Fig. 6

From: Per-fraction positional and dosimetric performance of prone breast tangential radiotherapy on Halcyon™ linear accelerator assessed with daily rapid kilo-voltage cone beam computed tomography: a single-institution pilot study

Fig. 6

Robust parallel slopes model residual (σ) plots and examination of model outliers. a Residual normal probability plot and residual versus fitted values plot. Residuals did not necessarily follow a normal distribution, for example for PTV ΔV90% [%] and BODY ΔV105% [cc]. Residuals were homoscedastic. b Representative outlier cases where PTV ΔV95% [%] was exceptionally low. Dose map ranges from 95% of prescription dose (blue) to respective maximum dose (red). PTV under-coverage occurred mostly at the chest wall. The beams were also very close to the contralateral (CL) breast and in one of the cases (patient 5, fraction 2) were irradiated outright above 95% of the prescription dose. c Representative outlier cases where BODY ΔV105% was exceptionally high. In the top case (patient 4, fraction 7), an area outside of the PTV contour was discovered that unexpectedly increased the BODY ΔV105%. In the bottom case (patient 5, fraction 15), the breast was highly deformed compared to the previous fraction (orange)

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