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Logo of bmcmiBioMed Centralsearchsubmit a manuscriptregisterthis articleBMC Medical Imaging
 
BMC Med Imaging. 2012; 12: 20.
Published online Jul 24, 2012. doi:  10.1186/1471-2342-12-20
PMCID: PMC3414789
Low tube voltage CT for improved detection of pancreatic cancer: detection threshold for small, simulated lesions
Jon Holm,corresponding author#1,2 Louiza Loizou,#2,3 Nils Albiin,2,3 Nikolaos Kartalis,2,3 Bertil Leidner,2,3 and Anders Sundin4,5
1Division of Medical Physics, Karolinska University Hospital, Huddinge, Stockholm 14186, Sweden
2Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, 17177 Stockholm, Sweden
3Department of Radiology, Karolinska University Hospital, Huddinge, 14186 Stockholm, Sweden
4Department of Radiology, Karolinska University Hospital, Solna, 17176 Stockholm, Sweden
5Department of Molecular Medicine and Surgery, Karolinska Institutet, Stockholm 17176, Sweden
corresponding authorCorresponding author.
#Contributed equally.
Jon Holm: jon.holm/at/gmail.com; Louiza Loizou: louiza.loizou/at/gmail.com; Nils Albiin: albiin/at/me.com; Nikolaos Kartalis: nikolaos.kartalis/at/karolinska.se; Bertil Leidner: bertil.leidner/at/karolinska.se; Anders Sundin: anders.sundin/at/ki.se
Received March 19, 2012; Accepted July 24, 2012.
Abstract
Background
Pancreatic ductal adenocarcinoma is associated with dismal prognosis. The detection of small pancreatic tumors which are still resectable is still a challenging problem.
The aim of this study was to investigate the effect of decreasing the tube voltage from 120 to 80 kV on the detection of pancreatic tumors.
Methods
Three scanning protocols was used; one using the standard tube voltage (120 kV) and current (160 mA) and two using 80 kV but with different tube currents (500 and 675 mA) to achieve equivalent dose (15 mGy) and noise (15 HU) as that of the standard protocol.
Tumors were simulated into collected CT phantom images. The attenuation in normal parenchyma at 120 kV was set at 130 HU, as measured previously in clinical examinations, and the tumor attenuation was assumed to differ 20 HU and was set at 110HU. By scanning and measuring of iodine solution with different concentrations the corresponding tumor and parenchyma attenuation at 80 kV was found to be 185 and 219 HU, respectively.
To objectively evaluate the differences between the three protocols, a multi-reader multi-case receiver operating characteristic study was conducted, using three readers and 100 cases, each containing 0–3 lesions.
Results
The highest reader averaged figure-of-merit (FOM) was achieved for 80 kV and 675 mA (FOM = 0,850), and the lowest for 120 kV (FOM = 0,709). There was a significant difference between the three protocols (p < 0,0001), when making an analysis of variance (ANOVA). Post-hoc analysis (students t-test) shows that there was a significant difference between 120 and 80 kV, but not between the two levels of tube currents at 80 kV.
Conclusion
We conclude that when decreasing the tube voltage there is a significant improvement in tumor conspicuity.
Keywords: Pancreatic adenocarcinoma, CT, Low tube voltage, Phantom
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