PMID- 25867655
OWN - NLM
STAT- MEDLINE
DCOM- 20160404
LR  - 20161125
IS  - 1536-0210 (Electronic)
IS  - 0020-9996 (Linking)
VI  - 50
IP  - 8
DP  - 2015 Aug
TI  - Collimation and Image Quality of C-Arm Computed Tomography: Potential of 
      Radiation Dose Reduction While Maintaining Equal Image Quality.
PG  - 514-21
LID - 10.1097/RLI.0000000000000158 [doi]
AB  - OBJECTIVES: The aim of this study was to assess the potential for radiation dose 
      reduction in collimated C-arm computed tomography (CACT) while maintaining the 
      image quality of the full field of view (FFOV) acquisition. MATERIAL AND METHODS: 
      A whole-body anthropomorphic phantom representing a 70-kg male was used in this 
      study. The upper abdomen of the phantom was imaged using an angiographic system 
      (Artis Zeego Q; Siemens Healthcare, Germany) with either the standard detector 
      radiation dose level (RDL; D100, 360 nGy) or 14 experimental reduced RDLs ranging 
      from 95% (D95, 342 nGy) to 30% D100 (D30, 108 nGy). Either the FFOV (craniocaudal 
      coverage, 18 cm) or a collimated field of view (CFOV; craniocaudal coverage, 6 
      cm) was applied. The organ dose was measured using thermoluminescence detector 
      dosimetry, and the mean effective dose was computed according to the 
      recommendations by the International Commission on Radiological Protection 
      Publication 103. To compare the CFOV and the FFOV data sets, image quality was 
      assessed in terms of high- and low-contrast resolution by calculating the 
      modulation transfer function using the wire method as well as the image noise, 
      signal-to-noise ratio, and contrast-to-noise ratio using a low-contrast insert 
      placed in the upper abdomen (Delta50 HU). RESULTS: Collimated imaging (CFOV) covering 
      33% of the FFOV led to an increase in the x-ray tube output of 152% for CFOV 
      (D100; FFOV, 95.5 mGy; CFOV, 147.7 mGy) to maintain the detector dose. The mean 
      effective dose of D100 was 6.0 mSv (male) and 6.2 mSv (female) for the FFOV and 
      3.7 mSv (male) and 4.1 mSv (female) for the CFOV. High-contrast resolution was 
      comparable for all acquisition protocols (mean 10% modulation transfer function +/- 
      95% confidence interval; FFOV, 8.8 +/- 0.1 line pairs/cm; CFOV, 8.8 +/- 0.1 line 
      pairs/cm). Low-contrast resolution was superior for the CFOV compared with that 
      for the FFOV for each RDL (D100; image noise: FFOV, 34 +/- 2 HU; CFOV, 22 +/- 1 HU; 
      contrast-to-noise ratio: FFOV, 1.3 +/- 0.2; CFOV, 1.8 +/- 0.3). Low-contrast 
      resolution of the standard (D100) FFOV acquisition was achieved for the CFOV at 
      84% D100 of the FFOV and 54% D100 of the CFOV. Therefore, collimation up to 33% 
      of the FFOV combined with the lower detector dose allows overall reduction of a 
      patient's radiation exposure to 33% x 84% = 28% compared with FFOV acquisition. 
      In the upper abdomen, this results in a nearly 50% reduction of the mean 
      effective radiation dose (male, 2.0 mSv; female, 2.2 mSv) without loss of image 
      quality compared with the standard FFOV acquisition. CONCLUSIONS: Craniocaudal 
      collimation in CACT should be used whenever possible to increase the image 
      quality and reduce the patient's overall radiation exposure. Therefore, new smart 
      acquisition protocols are required for collimated CACT to improve the trade-off 
      between radiation exposure and image quality requirements considering the 
      collimation used.
FAU - Werncke, Thomas
AU  - Werncke T
AD  - From the *Institute of Diagnostic and Interventional Radiology, Hannover Medical 
      School; and daggerUniversity of Veterinary Medicine, Hannover Institute for General 
      Radiology and Medical Physics, Hannover, Germany.
FAU - von Falck, Christian
AU  - von Falck C
FAU - Luepke, Matthias
AU  - Luepke M
FAU - Stamm, Georg
AU  - Stamm G
FAU - Wacker, Frank K
AU  - Wacker FK
FAU - Meyer, Bernhard Christian
AU  - Meyer BC
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Invest Radiol
JT  - Investigative radiology
JID - 0045377
SB  - IM
MH  - Arm/diagnostic imaging
MH  - Humans
MH  - *Image Processing, Computer-Assisted
MH  - *Phantoms, Imaging
MH  - *Radiation Dosage
MH  - *Radiographic Image Interpretation, Computer-Assisted
MH  - Signal-To-Noise Ratio
MH  - *Tomography, X-Ray Computed
EDAT- 2015/04/14 06:00
MHDA- 2016/04/05 06:00
CRDT- 2015/04/14 06:00
PHST- 2015/04/14 06:00 [entrez]
PHST- 2015/04/14 06:00 [pubmed]
PHST- 2016/04/05 06:00 [medline]
AID - 10.1097/RLI.0000000000000158 [doi]
PST - ppublish
SO  - Invest Radiol. 2015 Aug;50(8):514-21. doi: 10.1097/RLI.0000000000000158.