Radiation dose reduction without degradation of low-contrast detectability at abdominal multisection CT with a low-tube voltage technique: phantom study.

PURPOSE To reduce radiation dose from abdominal computed tomography (CT) without degradation of low-contrast detectability by using a technique with low tube voltage (90 kV). MATERIALS AND METHODS The institutional review board approved the participation of the radiologists in the observer performance test, and informed consent was obtained from all participating radiologists. A phantom for measurement of the radiation dose and a phantom containing low-contrast objects were scanned with a 16-detector row CT scanner at 120 kV and 90 kV. For determination of the radiation dose at both 90 kV and 120 kV, the tube current-time product settings were 100-560 mAs, and the doses at the center and periphery of the phantom were measured. To assess low-contrast detectability, we used a 300-mAs setting at 120 kV and 250-560-mAs settings at 90 kV. Five observers participated in the receiver operating characteristic analysis. Area under the receiver operating characteristic curve (A(z)) values were calculated in each observer. A(z) values obtained with each of the scanning techniques were recorded, and differences were examined for significance by using the Dunnet method. RESULTS The mean A(z) value was 0.951 at 120 kV and 300 mAs. A(z) values were 0.927-0.973 at 90 kV and 450-560 mAs, and the differences between those values and values obtained at 120 kV and 300 mAs were not significant (P = .937-.952). A value of 100% was assigned to the radiation dose delivered to the center of the phantom at 120 kV and 300 mAs. The relative dose delivered at 90 kV ranged from 65% at 450 mAs to 79% at 560 mAs. CONCLUSION A reduction from 120 kV to 90 kV led to as much as a 35% reduction in the radiation dose, without sacrifice of low-contrast detectability, at CT.

[1]  T. Iwasaki,et al.  Application of a newly developed photoluminescence glass dosimeter for measuring the absorbed dose in individual mice exposed to low-dose rate 137Cs gamma-rays. , 2000, Journal of radiation research.

[2]  D. Brenner,et al.  Estimated risks of radiation-induced fatal cancer from pediatric CT. , 2001, AJR. American journal of roentgenology.

[3]  Takeshi Nakaura,et al.  Abdominal CT with low tube voltage: preliminary observations about radiation dose, contrast enhancement, image quality, and noise. , 2005, Radiology.

[4]  Amy Berrington de González,et al.  Risk of cancer from diagnostic X-rays: estimates for the UK and 14 other countries , 2004, The Lancet.

[5]  Thomas L Toth,et al.  Detection and characterization of lesions on low-radiation-dose abdominal CT images postprocessed with noise reduction filters. , 2004, Radiology.

[6]  H. Kubo,et al.  Measurements of Gamma-Knife helmet output factors using a radiophotoluminescent glass rod dosimeter and a diode detector. , 2003, Medical physics.

[7]  W A Kalender,et al.  New low-contrast resolution phantoms for computed tomography. , 1999, Medical physics.

[8]  M Takahashi,et al.  Small hepatocellular carcinoma in patients with chronic liver damage: prospective comparison of detection with dynamic MR imaging and helical CT of the whole liver. , 1996, Radiology.

[9]  W Huda,et al.  Technique factors and image quality as functions of patient weight at abdominal CT. , 2000, Radiology.

[10]  Francis R Verdun,et al.  Detection of low-contrast objects: experimental comparison of single- and multi-detector row CT with a phantom. , 2002, Radiology.

[11]  James H Thrall,et al.  Multi-detector row CT: radiation dose characteristics. , 2003, Radiology.

[12]  T. Murakami,et al.  Hypervascular hepatocellular carcinoma: detection with double arterial phase multi-detector row helical CT. , 2001, Radiology.

[13]  G Allan Johnson,et al.  Optimization of eight-element multi-detector row helical CT technology for evaluation of the abdomen. , 2003, Radiology.

[14]  Jiang Hsieh,et al.  Computer-simulated radiation dose reduction for abdominal multidetector CT of pediatric patients. , 2002, AJR. American journal of roentgenology.

[15]  N. Obuchowski Receiver operating characteristic curves and their use in radiology. , 2003, Radiology.

[16]  J. Paul,et al.  Low-kilovoltage multi-detector row chest CT in adults: feasibility and effect on image quality and iodine dose. , 2004, Radiology.

[17]  Walter Hruby,et al.  Diagnostic performance of liquid crystal and cathode-ray-tube monitors in brain computed tomography , 2003, European Radiology.

[18]  John M Boone,et al.  Dose reduction in pediatric CT: a rational approach. , 2003, Radiology.

[19]  W. Foley,et al.  Multiphase hepatic CT with a multirow detector CT scanner. , 2000, AJR. American journal of roentgenology.

[20]  Kazuo Awai,et al.  Aortic and hepatic enhancement and tumor-to-liver contrast: analysis of the effect of different concentrations of contrast material at multi-detector row helical CT. , 2002, Radiology.

[21]  R. Baron,et al.  Understanding and optimizing use of contrast material for CT of the liver. , 1994, AJR. American journal of roentgenology.

[22]  E. Nickoloff,et al.  Influence of phantom diameter, kVp and scan mode upon computed tomography dose index. , 2003, Medical physics.

[23]  Takamichi Murakami,et al.  Small hypervascular hepatocellular carcinoma revealed by double arterial phase CT performed with single breath-hold scanning and automatic bolus tracking. , 2002, AJR. American journal of roentgenology.