Supine/prone position fixation treatment in cervical cancer radiotherapy
ABSTRACT
Objective:
This study aimed to determine the correlation between bladder volume changes and set-up accuracy in cervical cancer patients undergoing radiotherapy.
Methods:
Forty patients who underwent intensity-modulated radiotherapy were divided into two groups based on their position during treatment: group A (supine) and group B (prone). Correlations between bladder volume changes and set-up accuracy were retrospectively analyzed using archived data and image files.
Results:
The rate of bladder volume change in group A (–3.99% [–24.51–31.53]) was significantly higher (Z = –2.724; P = 0.006) than that in group B (–14.95% [–41.63–7.64]). The set-up errors in the X (left-right), Y (cranial-caudal), and Z (anterior-posterior) directions were 0.05 ± 2.25 mm, 0.84 ± 2.63 mm, and 0.41 ± 2.35 mm, respectively, in group A and –0.31 ± 2.22 mm, –0.38 ± 2.88 mm, and 0.78 ± 3.41 mm, respectively, in group B. No significant differences in the X and Z directions were detected between the two groups; however, a significant difference was detected in the Y direction. The set-up error in the X direction was positively correlated with the rate of bladder volume change (r = 0.284; P = 0.010) in group A; no correlations were observed in the X, Y, and Z directions in group B.
Conclusion:
Patients in the prone position demonstrated better performance in the Y direction than those in the supine position. The set-up error in the X direction was positively correlated with the rate of bladder volume change among patients in the supine position.