Jacobs Journal of Radiation Oncology

Observational study of cone beam CT based Inter-fractional urinary bladder filling variation during IGRT in pelvic malignancies

*Manjari Shah
Department Of Radiation Oncology, India

*Corresponding Author:
Manjari Shah
Department Of Radiation Oncology, India
Email:manjarishah29@gmail.com

Published on: 2018-12-17

Abstract

Organ motion is an important factor that limits the precision of radiation treatment. Bladder filling variation has significant impact on the position of target volumes in pelvic malignancies. This study was an effort to maintain a consistent urinary bladder volume after following a bladder protocol, which was then analysed by in room CBCT imaging. The bladder volumes and bladder wall dimension were analysed comprehensively thus adding considerable understanding to the bladder wall motions. A total number of 26 patients/ 300 scans were analyzed. This study has reached the conclusion that bladder filling protocol is necessary to maintain the consistent bladder volume but it is too preliminary to state that it will translate into reduction of margin.

Keywords

Introduction

With advancement, comes limitations. Similarly, in radiotherapy advanced machines and treatment techniques had several associated factors that limits its precision. Organ motion is one of the important factors limiting the precision of advanced radiation techniques, especially for pelvic malignancies. Bladder filling variation has significant impact on the position of target volumes in pelvic malignancies. The inter- and intra- fractional movement of the bladder wall can be as much as 3 cm due to changes in volume of bladder and rectum [1]. If the bladder wall motion is not taken into consideration while planning the treatment, target miss is likely to occur, resulting in reduced local tumour control. Thus, to compensate this the treatment margins were increased for the uncertainty of the bladder wall motion. Increasing the irradiated margins also increases the possibility a critical structure to be irradiated beyond tolerance leading to unacceptable complications. Another approach to reduce the bladder motion influence on the target location is by controlling the bladder volume, a protocol instructing the patient to drink a certain amount of water before starting the treatment, but studies showed that even with detailed instruction, patient were unable to maintain consistent bladder volumes. This study was an effort to maintain a consistent urinary bladder volume after following a strict bladder protocol, which was then analysed by in room CBCT imaging. The bladder volumes and bladder wall dimension in all the three directions were analysed comprehensively thus adding considerable understanding to the bladder wall motions.