To investigate the impact of combining image-guided radiotherapy (IGRT) with a bladder volume measurement device on reducing positional errors in patients with locally advanced cervical cancer, and to provide references for precise clinical radiotherapy implementation.

Forty patients with locally advanced cervical cancer were randomly divided into a study group (using a bladder volume measurement device) and a control group (self-regulated bladder filling). Both groups underwent pre-treatment CT simulation (pCT) and daily cone-beam CT (CBCT) scans. Bladder contours were delineated on all pCT and CBCT images to obtain volumetric data. The accuracy of the bladder volume measurement device was assessed by comparing its readings with bladder volumes derived from pCT and CBCT. Inter-fraction bladder filling consistency and positional correction errors were analyzed by comparing CBCT-derived bladder volumes with pCT baselines. Irradiated volumes of the eighth region and the vital organs were compared between the two groups.

No significant differences were observed between bladder volumes measured by the device and those from pCT or CBCT (P = 0.539, P = 0.343, respectively). In the study group, no significant difference existed between pCT and CBCT bladder volumes (P=0.097), whereas the control group showed significant discrepancies (P<0.05). Positional correction errors in the X, Y, and Z axes were significantly smaller in the study group compared to the control group (P<0.05). Significant differences in irradiated volumes of the bladder and small bowel were observed between groups (P<0.05), but not for the CTV, PTV, rectum, or femoral heads (P>0.05).

The bladder volume measurement device effectively ensures consistent bladder filling during radiotherapy, reduces positional errors, stabilizes target dose coverage, and lowers radiation risks to organs at risk (e.g., small bowel). This approach enhances precision in hypofractionated radiotherapy for cervical cancer.