[Investigation of a Bladder Filling Protocol for Stabilizing Bladder Volume in Radiation Therapy for Prostate Cancer].

PURPOSE: At our institution, the method previously used for bladder filling in prostate cancer radiation therapy involved drinking 500 ml of water and voiding 30 minutes prior to treatment. However, achieving consistent bladder volume had been challenging. We therefore developed and evaluated a new protocol.

METHODS

The new method involves drinking 200 ml of water 2 hours before treatment, followed by voiding, and then drinking another 200 ml of water 1 hour prior. Bladder volumes during treatment planning computed tomography (CT) and during treatment were measured using an ultrasound device and compared between the method previously used at our institution and the new method. Ten patients were evaluated for each protocol.

RESULTS

The mean bladder volumes at the time of planning CT and during treatment were 247.4±99.6 ml and 315.7±158.2 ml, respectively, with the method previously used at our institution, and 201.5±33.0 ml and 192.6±37.2 ml, respectively, with the new method. The new protocol resulted in more consistent bladder volumes.

CONCLUSION

The newly developed protocol achieved bladder volumes within the range of 100-250 ml, improved reproducibility at the time of treatment, and is expected to enhance workflow efficiency.