Published online by Cambridge University Press: 08 May 2017
Achieving daily consistent bladder volume is acknowledged as challenging for patients undergoing radiotherapy to the cervix or endometrium. We investigated if use of an ultrasound bladder volume scanner (BioCon-700) improves bladder reproducibility when used during an active volume correction protocol.
During our method-comparison study, prospectively recruited patients (n=20) followed a fluid-loading protocol to achieve acceptable bladder volume. Bladder ultrasound was performed daily to verify planned volume, with patients actively correcting volumes outside a planned range up to a maximum of three times. Using the Bland–Altman method, we compared mean ultrasound readings (USMean) with mean cone-beam computed tomography (CBCT) volumes (CBCTMean). We also conducted staff focus groups exploring issues encountered during implementation of bladder scanning.
Comparing USMean with CBCTMean produced a mean of the differences −10±49·92 mL (1 SD), demonstrating that bladder volume scanning is equivalent to our standard measure for the stated confidence levels. The cohort mean bladder volume decrease from week 1 to 5 was only 8·4%. Mean USMean was 323 mL, mean CBCTMean was 313 mL. Staff experience with the scanner overall was positive.
The BioCon-700 is suitable for the purpose of daily pre-treatment volume verification, facilitating daily assessment and modification of bladder volume, resulting in reproducible treatment volumes.