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Compatibility of interventional x‐ray and magnetic resonance imaging: Feasibility of a closed bore XMR (CBXMR) system
Author(s) -
Brzozowski Lukasz,
Ganguly Arundhuti,
Pop Mihaela,
Wen Zhifei,
Bennett Robert,
Fahrig Rebecca,
Rowlands J. A.
Publication year - 2006
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2219328
Subject(s) - perpendicular , x ray tube , optics , detector , physics , anode , rotation (mathematics) , materials science , nuclear magnetic resonance , flat panel detector , magnetic resonance imaging , cathode ray , x ray , cathode , electron , radiology , electrical engineering , computer science , nuclear physics , medicine , electrode , geometry , mathematics , quantum mechanics , artificial intelligence , engineering
A next‐generation interventional guidance system is proposed that will enable intraprocedural access to both x‐ray and magnetic resonance imaging (MRI) modalities. This closed bore XMR (CBXMR) system is comprised of a conventional radiographic rotating anode x‐ray tube and a direct conversion flat panel detector on a rotating gantry positioned adjacent to the bore of a 1.5 T MRI. To assess the feasibility of such a system, we have investigated the degree of compatibility between the x‐ray components and the MRI. For∣ B ⃗ ext ∣ < 200 G the effect on the radiographic tube motor was negligible regardless of the orientation ofB ⃗ ext with respect to the motor axis of rotation—the frequency of anode rotation remained within 6% of the 3400 rpm frequency measured at 0 G . For∣ B ⃗ ext ∣ > 2400 G the anode slowed down to below 2400 rpm at all orientations. At intermediateB ⃗ ext , the frequency of rotation varied between 2400 and 3200 rpm , showing a strong dependence on orientation, withB ⃗ ext perpendicular to the tube axis having a much stronger effect on the rotation frequency thanB ⃗ ext parallel to the tube axis. In contrast to the effect ofB ⃗ ext on the induction motor, parallelB ⃗ ext had a stronger detrimental effect on the cathode‐anode electron beam, whose path was at 16° to the tube axis, than the perpendicularB ⃗ ext . ParallelB ⃗ ext of several hundred Gauss had a defocusing effect on the x‐ray focal spot.B ⃗ ext perpendicular to the electron beam shifted the beam without significant defocusing. We have determined that the direct conversion flat panel detector (FPD) technology is not intrinsically sensitive toB ⃗ ext , and that the modifications required to make the proposed FPDs MRI compatible are minimal. The homogeneity of the MRI signal in the normal field of view was not significantly degraded by the presence of these x‐ray components in the vicinity of the MRI bore entrance.