Simple calculation using anatomical features on pre-treatment verification CT for bladder volume estimation during radiation therapy for rectal cancer

Table 2 Comparison between bladder volumes estimated using bladder scan and using anatomic references on planning computed tomography

Estimation tool	Number of data sets	Mean percent difference	95% CI	SD of percent difference	P
V_scan	462	42.7	39.4–45.9	35.5	< 0.001
V_ratio	462	26.3	24.6–28.1	19.6

Abbreviations: CI confidence interval, SD standard deviation, V_scan bladder volume measurement using bladder scan, V_ratio bladder volume measurement using ratio of anatomical features

ISSN: 1471-2407