Claire Lucchetta MD, Presenter: Nothing to Disclose

Aissam Labani MD, Abstract Co-Author: Nothing to Disclose

Mi-Young Jeung MD, Abstract Co-Author: Nothing to Disclose

Marysa Schaal MD, Abstract Co-Author: Nothing to Disclose

Karim Haioun, Abstract Co-Author: Employe, Toshiba Corporation

Catherine Roy MD, Abstract Co-Author: Nothing to Disclose

Mickael Ohana MD, MSc, Abstract Co-Author: Nothing to Disclose

To qualitatively and quantitatively compare ultra-low-dose (ULD) chest CT acquired at 80 and 135kV.

30 patients (68% men, 55yo ±14) referred for a clinically indicated unenhanced chest CT were prospectively included. Participants underwent a triple acquisition on a second-generation 320-row scanner: a standard "full dose" acquisition (120kV, automated tube current modulation) and two ULD acquisition (80kV with 40mA and 135kV with 10mA), all reconstructed with mediastinal and lung kernels using an iterative algorithm (AIDR 3D). ULD acquisition parameters were chosen to achieve the same level of radiation dose between 80 and 135kV. Image quality of both ULD acquisitions was independently and blindly assessed by two chest radiologists, each reader having to designate for every patient which kV provided the best diagnostic and image quality. Image noise was measured within the trachea and compared between both ULD acquisitions with a paired Student t test. A p<0.05 was considered significant.  

Radiation dose was similar between 135kV and 80kV ULD acquisitions, with a mean DLP of 17.2mGy.cm ±1.6 and 16.2mGy.cm ±1.5 respectively. DLP of the standard 120kV acquisition was 210mGy.cm ±87. The 135kV ULD acquisition was found to be better in 100% of patients for reader 1 and in 97% of patients for reader 2. The agreement between the two readers was almost perfect with a Cohen’s κ of 0.98. The noise was significantly lower at 135kV than at 80kV (61.5 ±5.7 vs 81.4 ±11.8, p<0.01). Reference noise for standard 120kV acquisition was 44.7 ±6.5.  

For ULD chest CT, acquisitions made at 135kV are qualitatively and quantitatively better than those made at 80kV.

Ultra-low-dose unenhanced chest CT must be acquired with a high kV/low mA technique.

Lucchetta, C, Labani, A, Jeung, M, Schaal, M, Haioun, K, Roy, C, Ohana, M, Ultra-low-dose Chest CT: Should we Acquire it at 80 or 135 kV? A Qualitative and Quantitative Prospective Study on 30 Patients.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045486.html