Effective dose to patient measurements for flat-detector computed tomography protocols in acute stroke care

Abstract

Objectives

The aim was to measure the effective dose of flat-detector CT (FDCT) whole-brain imaging, biphasic FDCT angiography (FDCT-A), and FDCT perfusion (FDCT-P) protocols and compare it to previously reported effective dose values of multidetector CT (MDCT) applications.

Materials

We measured effective dose according to the IRCP 103 using an anthropomorphic phantom equipped with thermoluminescent dosimeters (TLDs). Placement was according to anatomical positions of each organ. In total, 60 TLDs (≥ 4 TLDs/organ) were placed into and onto the phantom to account for all relevant organs. Organs within the primary beam were covered with more TLDs. Additionally, we measured dose to the eye lens with two TLDs per eye. Protocols which we routinely use in clinical practice were measured on a biplane angiography system.

Results

The effective dose of the 20-s protocol/7-s protocol for whole-brain imaging was 2.6 mSv/2.4 mSv. The radiation dose to the eye lens was 24/23 mGy. For the biphasic high-/low-dose FDCT-A protocol, the effective dose was 8.9/2.8 mSv respectively. The eye lens dose was 60/14 mGy. The contribution of bolus tracking to the effective dose was 0.66 mSv (assuming average duration of 14 s). The multisweep FDCT-P protocol had an effective dose of 5.9 mSv and an eye lens dose of 46 mGy.

Conclusion

Except for the high-dose biphasic FDCT-A protocol, FDCT applications used in neuroradiology have effective doses, which do not deviate more than 1 mSv from previously reported values for MDCT applications. However, the effective dose to the eye lens in commonly used stroke paradigms exceeds the recommended annual dose twofold.

Key Points

• Flat-detector computed tomography (FDCT) can be used for acute and periinterventional imaging of acute stroke patients and in neurointerventions.

• Except for the high-dose FDCT angiography protocol, the effective doses do not deviate more than 1 mSv from previously reported values for multidetector CT applications.

• Strategies to decrease the effective lens dose especially in younger patients should be evaluated in the future.

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Abbreviations

FDCT:

Flatpanel-detector CT

FDCT-A:

FDCT angiography

FDCT-P:

FDCT perfusion

MDCT:

Multidetector CT

TLD:

Thermoluminescent dosimeter

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Funding

No funding was received for this specific study.

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Correspondence to Alex Brehm.

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The scientific guarantor of this publication is Marios-Nikos Psychogios.

Conflict of interest

Grant: Siemens. Comments: research grant with the Department of Neuroradiology (University Medical Center Göttingen); money paid to the institution

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No complex statistical methods were necessary for this paper.

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No informed consent was necessary, because no patients or probands have been included in this study.

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Institutional Review Board approval was not required because it was a phantom study, not including any patients or animals.

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Brehm, A., Stamm, G., Lüpke, M. et al. Effective dose to patient measurements for flat-detector computed tomography protocols in acute stroke care. Eur Radiol 30, 5082–5088 (2020). https://doi.org/10.1007/s00330-020-06891-w

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Keywords

  • Cone-beam computed tomography
  • Stroke
  • Radiation dosage
  • Perfusion
  • Angiography