[Comparison of Bladder Volume Measurement Accuracy between Portable Ultrasound Diagnostic Equipment and CBCT for Pelvic Prostate Radiotherapy].

Purpose: We evaluated the measurement accuracy of the CubeScan BioCon-900 (here after BioCon-900), a portable ultrasound imaging diagnostic device capable of measuring bladder volume, to determine if it can accurately assess bladder volume before intensity-modulated radiation therapy (IMRT) for prostate cancer.

Methods: Bladder volume was measured from kV-Cone Beam computed tomography (CBCT) images obtained immediately before the administration of IMRT for prostate cancer using Halcyon. The bladder volume measured from kV-CBCT images (23 patients, total number of scans: 139) immediately before the IMRT procedure was used as the reference value. The difference between the bladder volume measured by the BioCon-900 was then calculated.

Results: The bladder volume measured from kV-CBCT images was 117.5±49.4 cc. In contrast, the bladder volume obtained with BioCon-900 was 104.1±48.6 ml, resulting in an absolute mean difference of 18.4% and a correlation coefficient of 0.881. The measurements by BioCon-900 tended to be, on average, 11% smaller than the bladder volume measured by kV-CBCT imaging.

Conclusion: kV-CBCT images demonstrated a strong positive correlation between bladder volume and bladder urine output obtained with BioCon-900. BioCon-900 can be used before kV-CBCT imaging to accurately and conveniently assess bladder volume.