Validation of an external ultrasound device for bladder volume measurements in prostate conformal radiotherapy

Abstract 

Purpose

The objective of this study was to assess the feasibility and accuracy of an external ultrasound device – BladderScan™ 6100 instrument (BVI) – for the measurement of bladder volume for prostate conformal radiotherapy patients.

Materials and methods

The bladder volume delineated on the planning CT scan was compared with the volume measurements obtained from a non-invasive BVI, for 50 prostate conformal radiotherapy patients, using a paired t-test at 5% significance level. The BVI repeatability was calculated using the within-patient standard deviation of the BVI replicate measurements.

Results

This study demonstrates that bladder volume measurements obtained using the BVI are not significantly different from the volumes delineated on the planning CT scan, mean difference=−9.65ml, p=0.351. The magnitude of the difference between the CT and BVI measurements was found to be unrelated to the magnitude of the bladder volume. The repeatability of the BVI measurements was not influenced by the magnitude of the bladder volume.

Conclusion

The results confirm the validity of using the BVI to instantly, objectively and non-invasively measure a patient's bladder volume for prostate conformal radiotherapy. The validation of this instrument will permit further research to be conducted with regards to developing evidence-based bladder filling instructions for radiotherapy patients.

Keywords: Bladder volume, Prostate radiotherapy, Full bladder