Improved Dose Estimates for Fluoroscopically Guided Lumbar Epidural Injections

Steve D Mann; Anand Joshi; Megan Shonyo; Jered R Wells; Jocelyn Hoye; Greeshma Agasthya; Robert Reiman; Ehsan Samei

doi:10.1093/pm/pny172

Improved Dose Estimates for Fluoroscopically Guided Lumbar Epidural Injections

Pain Med. 2019 May 1;20(5):971-978. doi: 10.1093/pm/pny172.

Authors

Steve D Mann^{1

2

3}, Anand Joshi^{4

5}, Megan Shonyo³, Jered R Wells^{1

2

3

6}, Jocelyn Hoye^{2

3

6}, Greeshma Agasthya, Robert Reiman^{6

7

8}, Ehsan Samei^{1

2

3

6}

Affiliations

¹ Clinical Imaging Physics Group, Duke University Health System, Durham, North Carolina, USA.
² Carl E. Ravin Advanced Imaging Laboratories, Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
³ Department of Radiology, Duke University Medical Center, Durham, North Carolina, USA.
⁴ School of Medicine, Duke University, Durham, North Carolina, USA.
⁵ Department of Orthopaedic Surgery, Duke University Medical Center, Durham, North Carolina, USA.
⁶ Medical Physics Graduate Program, Duke University, Durham, North Carolina, USA.
⁷ Department of Imaging Science and Innovation, Geisinger, Danville, PA, USA.
⁸ Radiation Safety Division, Occupational and Environmental Safety Office, Duke University Health System, Durham, North Carolina, USA.

PMID: 30215781
DOI: 10.1093/pm/pny172

Abstract

Objective: The goal of the study was to determine the potential impact of system inaccuracies and table attenuation on fluoroscope-reported dose values.

Design: An Institutional Review Board-approved study was conducted to collect detailed acquisition and patient exposure data for fluoroscopy-guided lumbar epidural injections.

Background: System-reported dosimetry values, especially the air Kinetic Energy Released per unit MAss and dose-area product metrics, are routinely used for estimating the radiation burden to patients undergoing fluoroscopy-guided procedures. However, these metrics do not account for other factors, such as acquisition geometry, where the table may attenuate a substantial fraction of the x-ray intensity, and system dosimetry inaccuracies, which are only required to be accurate within ±35%.

Methods: Acquisition data from 46 patients undergoing fluoroscopy-guided lumbar epidural injections were collected to better estimate the true incident dose-area product. Gantry angles, x-ray technique factors, and field sizes were collected to characterize each procedure. Additionally, the fluoroscope dosimetry accuracy and table attenuation properties were evaluated as a function of kVp to generate the correction factors necessary for accurate dosimetry estimates.

Results: The system-reported values overestimated the total patient entrance dose-area product by an average of 34% (13-44%). Errors may be substantially higher for systems with less accurate fluoroscopes or more anterior-posterior projections. Correcting system-reported dosimetry values for systematic inaccuracies and variability can substantially improve fluoroscopic dose values.

Conclusions: Including corrections for system output inaccuracies and acquisition factors such as table attenuation is necessary for any reliable assessment of radiation burden to patients associated with fluoroscopy-guided procedures.

Keywords: DAP; Dose; Epidural; Fluoroscopy; Low Back Pain; Radiation.

MeSH terms

Adrenal Cortex Hormones / administration & dosage
Fluoroscopy / methods
Humans
Injections, Epidural / methods*
Lumbosacral Region
Radiation Dosage*
Radiography, Interventional / methods*
Radiometry / methods*

Substances

Adrenal Cortex Hormones