Metered Usage of Fluoroscopic C-arm in Non-lead Lined Operating Theatres to Meet Regulatory Limits of Scatter Radiation

Abstract Description

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Authors (including presenting author) :

Li KW(1), Lo SK(1), Mak YT(1)

Affiliation :

(1)Medical Physics Unit, Department of Clinical Oncology, Tuen Mun Hospital

Introduction :

Not all operating theatres (OTs) in Pok Oi Hospital (POH) are built with lead-lining walls and doors. From radiation protection point of view, changing those OTs to lead-lined is recommended, especially for the increasing radiation workload in the future. However, modifying the material of the current already-in-use OTs is very tedious.

Objectives :

To recommend the permissible mobile C-arm usage in terms of dose area product (DAP) in non-lead lined OT.

Methodology :

A radiochromic film dosimetry system, including Gafchromic films, film analysis software and Epson Perfection V700 flatbed scanner, was developed for dose measurement in kilovoltage x-ray beams. A calibration curve was obtained using a solid-state detector as reference. A Gafchromic XR-QA2 film was placed on each side of the internal walls of three OTs. DAP of each exam was recorded for the three routinely used mobile C-arms, which were GE OEC 9900 Elite, Philips BV Pulsera 12 inch image intensifier (II) and 9 inch II.

Result & Outcome :

From July 2018 to December 2018, cumulative DAP (CDAP) in each OT was calculated and absorbed dose of each film was measured. The CDAP in OT 1 (size: 7.6 m x 6.2 m), 7 (size: 8 m x 6.5 m) and 8 (size: 7.4 m x 7.1 m) were 171.5 mGym2, 88.6 mGym2 and 69.6 mGym2 respectively. The cumulative dose of each film was lower than 1 mGy. The film doses would be monitored in a regular interval for a year. Monthly maximum permissible C-arm usage in terms of DAP could then be estimated to fulfil the public dose limit of 1 mSv/year in Hong Kong radiation ordinance.