Exploratory models comparing ethiodized oil-glue and gold fiducials for bladder radiotherapy image-guidance

Daryl Lim Joon; Alexandra Berlangieri; Benjamin Harris; Mark Tacey; Rachel O'Meara; Brent Pitt; Angela Viotto; Kerryn Brown; Michal Schneider; Nathan Lawrentschuk; Shomik Sengupta; Colleen Berry; Trish Jenkins; Michael Chao; Morikatsu Wada; Farshad Foroudi; Vincent Khoo

doi:10.1016/j.phro.2021.01.008

Exploratory models comparing ethiodized oil-glue and gold fiducials for bladder radiotherapy image-guidance

Phys Imaging Radiat Oncol. 2021 Feb 6:17:77-83. doi: 10.1016/j.phro.2021.01.008. eCollection 2021 Jan.

Authors

Daryl Lim Joon^{1

2}, Alexandra Berlangieri¹, Benjamin Harris¹, Mark Tacey¹, Rachel O'Meara¹, Brent Pitt¹, Angela Viotto¹, Kerryn Brown¹, Michal Schneider², Nathan Lawrentschuk¹, Shomik Sengupta¹, Colleen Berry¹, Trish Jenkins¹, Michael Chao¹, Morikatsu Wada¹, Farshad Foroudi¹, Vincent Khoo^{1

2

3}

Affiliations

¹ Olivia Newton John Cancer Center, Radiation Oncology, 145 Studley Rd, Heidelberg, Victoria 3084, Australia.
² Monash University, Department of Medical Imaging and Radiation Sciences, Faculty of Medicine, Nursing and Health Sciences, Wellington Rd, Clayton, Victoria 3800, Australia.
³ Royal Marsden NHS Foundation Trust, 203 Fulham Rd, Chelsea, London SW3 6JJ, United Kingdom.

Abstract

Background and purpose: Image-guidance with fiducials has been shown to improve pelvic radiotherapy outcome. However, bladder fiducials using ethiodized oil (EO) alone can disperse widely, and gold causes Computed Tomography scan (CT) metal artifacts. The study's purpose was to investigate the ability to deliver EO-tissue glue fiducials and compare them to gold for bladder radiotherapy image guidance.

Materials and methods: A fluid-filled porcine bladder model was used to assess the ability to cystoscopically inject visible EO glue fiducials into the submucosa. We then transferred the bladders into a porcine pelvis for imaging and compared them to gold fiducials using CT, Cone Beam CT (CBCT), and kilovoltage (KV) planar views. A tissue-equivalent phantom was utilized to analyze the CT number Hounsfield Unit (HU) characteristics and artifacts of the glue and gold fiducials. Percentile ranges and normal tissue voxel percentages of the subsequent CT number voxel histogram from a 2 cm sphere surrounding the fiducial was used to characterize the artifact.

Results: We successfully delivered all EO glue fiducials into the porcine bladders as discrete fiducials. They were well seen on CT, CBCT, and KV imaging. The glue fiducials had lower CT number values, but less CT number spread of the voxel percentile ranges consistent with the diminished contrast and less artifact than gold. The glue fiducial types had similar CT number characteristics.

Conclusion: This study has shown that EO glue fiducials can be delivered with online visualization qualities comparable to gold fiducials without metal-related artifacts.

Keywords: Bladder cancer; Glue fiducials; Image-guided radiotherapy; Liquid fiducials; Prostate cancer; Radiotherapy.