Program Information
Protocol Optimization and Dosimetry of 3D Rotational Angiography in Pediatric Neuroangiographic Procedures
N Shkumat*, P Muthusami , M Shroff , The Hospital for Sick Children, Toronto, ON
Presentations
SU-E-201-3 (Sunday, July 30, 2017) 1:00 PM - 1:55 PM Room: 201
Purpose: 3-dimensional rotational angiography (3DRA) is often employed for volumetric reformation of pediatric intracranial vascular lesions. This work evaluates the dosimetric considerations for 3DRA-CT compared to the current standard of biplane DSA acquisition, while further estimating the effective dose for unique, customized acquisition protocols.
Methods: This study evaluated 35 3DRA-CT studies over a period of 13 months. Acquisitions (subtracted or unsubtracted) that had been performed depending on the clinical indication were stratified into three quality levels, yielding six unique technical protocol variants. Quantitative radiation dose surrogates (Kₐ,ᵣ and PKA) were extracted from structured reports and raw image data. Effective doses were calculated through Monte Carlo simulation (PCXMC (STUK, Radiation and Nuclear Safety Authority, Helsinki, Finland)) for reference phantoms corresponding to patient age, corrected for radiation output, acquisition parameters, beam quality, irradiation geometry, table, pad, etc.
Results: The unsubtracted 3DRA protocols delivered a mean effective dose of 0.06, 0.07 and 0.3 mSv, whereas the subtracted protocols delivered an average of 0.05, 0.1 and 0.5 mSv. The radiation burden with customized high-kVp, high-filtration, low-dose per frame techniques was minimal, delivering a mean relative dose of 6.3% (3.3-8.4%) when compared to the associated 2D biplane DSA acquisition for the same vessel. In contrast, for the conventional subtracted protocol, each 3DRA delivered a mean relative dose of 113% (52-261%) when compared to DSA.
Conclusion: With high spatial resolution and multiplanar reformatting capability, 3DRA-CT is a useful tool that can assist in the evaluation of small, complex lesions. With appropriate modifications of technical acquisition protocols, the dose penalty often associated with this technique can be minimal when compared to standard biplane DSA, and can potentially alleviate the need for multiple DSA acquisitions at varied angles. These dose estimates of customized protocols could serve to alleviate radiation concerns that currently make 3DRA prohibitive to some interventionalists.
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