Effect of bladder filling status on positioning errors in post-hysterectomy cervical cancer radiotherapy

Figures & data

Figure 1. Flow chart of study design.

Figure 2. Schematic diagram of measuring the length, width and height of the bladder (three axial lengths).

Figure 3. Linear correlation between bladder filling and positioning. The X-axis is the pendulum error value, and the Y-axis indicates the number of cases corresponding to a certain error. Three lines are shown, respectively: green Rt-Lt is the horizontal direction (Right-Left); red Sup-Inf is the longitudinal direction (Superior-Inferior); and blue Ant-Post is the vertical (Anterior-Posterior) direction.

Table 1. Positioning error under different bladder filling deviations (x- ± s, cm).

	X (Rt–Lt)	Y (Sup–Inf)	Z (Ant–Post)
Group A1	0.15 ± 0.11	0.26 ± 0.22	0.16 ± 0.12
Group B1	0.19 ± 0.14	0.50 ± 0.34	0.22 ± 0.17
t	−2.106	−6.012	−3.055
P	0.37	<0.001	<0.001

Rt–Lt: right–left; Sup–Inf: Superior-Inferior; Ant–Post: Anterior–Posterior.

Table 2. Bladder filling deviation with different positioning errors (x- ± s, %).

	Bladder filling deviation
Group A2	25.6 ± 22.7
Group B2	54.1 ± 54.4
t	−4.729
P	<0.001

Table 3. Different positioning states with different bladder filling deviations.

		Positioning state (%)		Total
		Excellent	Poor
Bladder filling state	Suitable	65 (73.03)	24 (26.97)	89
	Subpar	35 (33.02)	71 (66.98)	106
Total		100 (51.28)	95 (48.72)	195
χ^2		31.006
p		<0.001

Table 4. The positioning error of patients with inferior positioning status in different directions.

		Positioning state (%)		Total
		Excellent	Poor
	Rt–Lt	83 (87.37)	12 (12.63)	95
Positioning errors direction	Sup–Inf	16 (16.84)	79 (83.16)	95
	Ant–Post	75 (78.95)	20 (21.05)	95
Total		174 (61.05)	111 (38.95)	285
χ^2		118.551
p		<0.001

Rt–Lt: right–left; Sup–Inf: Superior–Inferior; Ant–Post: Anterior–Posterior.

Data availability statement

The data supporting the findings of this study are available within the article.