Use of a prospective cohort study in the development of a bladder scanning protocol to assist in bladder filling consistency for prostate cancer patients receiving radiation therapy

Abstract

IntroductionEvidence of variations in bladder filling effecting prostate stability and therefore treatment and side‐effects is well established with intensity modulated radiation therapy (IMRT). This study aimed to increase bladder volume reproducibility for prostate radiation therapy by implementing a bladder scanning (BS) protocol that could assist patients' bladder filling at computed tomography (CT) simulation and treatment.MethodsBased on a retrospective review of 524 prostate cancer patients, a bladder volume of 250–350 mL was adopted as ‘ideal’ for achieving planning dose constraints. A prospective cohort study was conducted to assess the clinical utility of measuring patients' bladder volumes at CT simulation using an ultrasound bladder scanner (Verathon 9400 BladderScan®). A revised bladder preparation protocol was utilised by a bladder scan group (BS) and a non‐BS group followed the standard departmental bladder preparation protocol. Time and volume data for the BS group (n = 17) were compared with the non‐BS group (n = 17).ResultsThe BS cohort had a CT bladder volume range of 221–588 mL; mean 379 mL, SD 125 mL. The non‐BS group had a larger range: 184–757 mL; mean 373 mL, SD 160 mL (P = 0.9171). There was a positive correlation between CT volume and BS volume in the BS group (r = 0.797; P = 0.0002) although BS volumes were smaller: range 160–420 mL; mean 251 mL; SD 91 mL; P < 0.0001). The maximum bladder volume receiving 50 Gy (V50) from the BS group was 46.4%, mean 24.5%. The maximum bladder V50 from the non‐BS group was 50.9%, mean 27.3% (P = 0.5178). Treatment data from weekly cone beam CT scans were also compared over 6 weeks. They were assessed as being a pass if bladder and bowel requirements were acceptable. The BS group proceeded to treatment on the basis of a pass 92.7% of the time, whereas the pass rate for non‐BS group was 75%; difference 17.7% (P < 0.0001).ConclusionThe BS is a useful tool for achieving consistent, appropriately sized bladder volumes in prostate cancer patients.

WITHDRAWN: A study of bladder filling consistency before and during the radiotherapy for pelvic cancer

“…Generally, when calculating the distribution probability, the normal or near-normal distribution data can be used (mean ± 2SD) to specify the probability range [14]. There have been different understandings and de nitions of the consistency of BV, but they have not proved whether it is suitable for most patients with pelvic cancer [8,11]. Judgment consistency cannot blindly expand the reference range, it should be judged according to the actual situation of the patient.…”

“…Fujioka et al believed that the mean relative bladder volume (RBV) was at least 70%, and based on the results of the mean values of BV receiving more than 70 Gy(V 70Gy ) and 50 Gy(V 50Gy ) in each subgroup, the cutoff value (mean + 2standard deviations [SD]) at the upper bounds of the 95% con dence interval was determined [8]. Cramp et al believed that the BV was reasonable when it was 250-350 mL, and the RBV > 50% was considered to be up to standard [11]. Hong In Yoon et al thought that when the bladder volume of patients ranged from 80-120% of that of the simulation CT scan, patients were instructed to keep the same pattern of bladder lling the following day [12].…”

A Feasibility Study on the Role of Ultrasound Imaging of Bladder Volume as a Method to Improve Concordance of Bladder Filling Status on Treatment with Simulation

“…Their study underlined the importance of more objective bladder filling protocols and using an ultrasound bladder scanner as a screening tool to identify patients with large bladder filling variations during treatment. More recently, Cramp et al (2015) conducted a feasibility study that used an ultrasound bladder scanner before CT simulation and compared it with a retrospective study of 524 bladder volumes analyzed from prostate planning [25]. Patients were planned when they demonstrated a 250-350 mL bladder volume, which was adopted as being ''ideal'' for achieving planning dose constraints.…”

Overview of patient preparation strategies to manage internal organ motion during radiotherapy in the pelvis

“…This could be especially useful for treatments requiring a high degree of conformality such as SABR or boosting of dominant intra-prostatic lesions. A retrospective study of electromagnetic transponders in 236 patients undergoing prostate radiotherapy observed that changes in intra-fractional prostate position were more likely the longer the treatment delivery time [38]. Variations of >3 mm were seen for 12 % of the time taken to deliver fixed-field IMRT delivered within 10 minutes, compared to only 4 % for more rapidly-delivered volumetric modulated arc therapy (VMAT) treatments completed within 5 minutes.…”