Reduction of intra-fraction prostate motion - Determining optimal bladder volume and filling for prostate radiotherapy using daily 4D TPUS and CBCT

Eric Pei Ping Pang; Kellie Knight; Ashik Hussain; Qiao Fan; Marilyn Baird; Sheena Xue Fei Tan; Wing-Ho Mui; Ronnie Wing-Kin Leung; Irene Kai Ling Seah; Zubin Master; Jeffrey Kit Loong Tuan

doi:10.1016/j.tipsro.2018.01.003

Reduction of intra-fraction prostate motion - Determining optimal bladder volume and filling for prostate radiotherapy using daily 4D TPUS and CBCT

Tech Innov Patient Support Radiat Oncol. 2018 Feb 15:5:9-15. doi: 10.1016/j.tipsro.2018.01.003. eCollection 2018 Mar.

Authors

Affiliations

¹ Faculty of Medicine, Nursing and Health Sciences, Department of Medical Imaging & Radiation Sciences, Monash University, Wellington Road, Clayton, VIC 3800, Australia.
² Division of Radiation Oncology, National Cancer Centre Singapore, 11 Hospital Drive, Singapore 169610, Singapore.
³ Centre for Quantitative Medicine, Duke-NUS Medical School, Singapore, 8 College Road, Singapore 169857, Singapore.
⁴ Tuen Mun Hospital, Hong Kong, 23 Tsing Chung Koon Road, Tuen Mun, New Territories, Hong Kong.
⁵ Duke-NUS Graduate Medical School, Singapore, 8 College Road, Singapore 169857, Singapore.

Abstract

Background and purpose: Inconsistent bladder and rectal volumes have been associated with motion uncertainties during prostate radiotherapy. This study investigates the impact of these volumes to determine the optimal bladder volume.

Materials and methods: 60 patients from two Asian hospitals were recruited prospectively. 1887 daily cone-beam computed tomography (CBCT) images were analysed. Intra-fraction motion of the prostate was monitored real-time using a four-dimension transperineal ultrasound (4D TPUS) Clarity® system. The impact of planned bladder volume, adequacy of daily bladder filling, and rectum volume on mean intra-fraction motion of the prostate was analysed. Patients' ability to comply with the full bladder hydration protocol and level of frustration was assessed using a questionaire. Acute side effects were assessed using the Common Terminology Criteria for Adverse Events (CTCAE) version 3.0 and quality of life (QoL) assessed using the International Prostate Symptom Score (IPSS).

Results: The mean (SD) bladder and rectum volumes achieved during daily treatment were 139.7 cm³ (82.4 cm³) and 53.3 cm³ (18 cm³) respectively. Mean (SD) percentage change from planned CT volumes in bladder volume was reduced by 8.2% (48.7%) and rectum volume was increased by 12.4% (42.2%). Linear Mixed effect model analysis revealed a reduction in intra-fraction motion in both the Sup/Inf (p = 0.008) and Ant/Post (p = 0.0001) directions when the daily bladder was filled between 82 and 113% (3rd Quartiles) of the planned CT volumes. A reduction in intra-fraction motion of the prostate in the Ant/Post direction (z-plane) (p = 0.03) was observed when the planned bladder volume was greater than 200 ml. Patients complied well with the hydration protocol with minimal frustration (mean (SD) scores of 2.1 (1.4) and 1.8 (1.2) respectively). There was a moderate positive correlation (0.496) between mean bladder volume and IPSS reported post-treatment urinary straining (p = 0.001).

Conclusions: A planned bladder volume >200 cm³ and daily filling between 82 and 113%, reduced intra-fraction motion of the prostate. The hydration protocol was well tolerated.

Keywords: 4D TPUS clarity; Full bladder hydration protocol; Intra-fraction motion; Prostate radiotherapy; Real-time tracking.