Measured bladder volume for radiotherapy of the prostate using the hand-held BladderScan® BVI 3000

Abstract

Purpose: It is known that the volume of the bladder can influence the position of the prostate or prostatic bed and the amount of small bowel in external beam radiotherapy treatment for prostate cancer. Therefore reducing the variation of the bladder volume between planning and treatment, should improve the accuracy of treatment. Patients at our radiotherapy centre are instructed to have a comfortably full bladder for treatment. A hand-held BladderScan® (Diagnostic Ultrasound Europe B.V, IJsselstein, Netherlands) three-dimensional (3D) ultrasound device was tested for correlation between volumes measured using the BladderScan® and volumes contoured using computed tomography (CT) data. The device was used to assess if patients can judge the comfortably full state of their bladder. In addition it was investigated whether the residual volume of the bladder changed over the course of radiotherapy. Methods: For 11 radical prostate patients measurements of bladder volume using the BladderScan® were taken at CT planning and at each treatment of the full bladder volume prior to the procedure and then with an empty bladder post procedure. Results: We found that there is a good correlation (r = 0.85) between the measured bladder volume and a contoured volume, validating the use of the BladderScan®. Patients could judge the comfortably full state of their bladder at 76.5% of fractions. Over the course of radiotherapy there was equal distribution of positive and negative trends of residual bladder volumes. Conclusion: We conclude that the BladderScan® is a reliable device for assessing bladder volume, and patients can correctly judge their comfortably full bladder in most cases.