Influence of risk-organ–based tube current modulation on CT-induced DNA double-strand breaks in a biological phantom model

Abstract

Techniques for dose reduction in computed tomography (CT) are receiving increasing attention. Lowering the tube current in front of the patient, known as risk-organ–based tube current modulation (RTM), represents a new approach. Physical dose parameters can determine the exposure but are not able to assess the biological–X-ray interactions. The purpose of this study was to establish a biological phantom model to evaluate the effect of RTM on X-ray–induced DNA double-strand breaks (DSBs). In breast phantoms and in the location of the spine in an Alderson phantom, isolated human blood lymphocytes were irradiated using a 128-slice CT scanner. A standard thoracic CT protocol (120 kV, 110 ref. mAs, anatomy-based tube current modulation, pitch 0.6, scan length 30 cm) with and without RTM was used. X-ray–induced DSBs were quantified in isolated blood lymphocytes using immunofluorescence microscopy after staining for the phosphorylated histone variant γ-H2AX. Using RTM, the resulting DNA damage reduction was 41% in superficial breast locations (P = 0.0001), 28% in middle breast locations (P = 0.0003) and 29% in lower breast locations (P = 0.0001), but we found a DNA damage increase of 36% in superficial spine locations (P = 0.0001) and of 26% in deep spine locations (P = 0.0001). In summary, we established a biological phantom model that is suitable for detecting DNA damage in distinct organs. In addition, we were able to show that, using RTM, X-ray–induced DNA damage in the breast can be significantly reduced; however, there is a significant increase in DSBs in the location of the spine.

Practical advices for optimal CT scanner dose in children

“…Iterative reconstruction techniques have demonstrated the potential for improving image quality thus allowing a reduction in radiation dose (Khawajo et al, 2014;Brand et al, 2018).…”

The impact of vertical off-centering on image noise and breast dose in chest CT with organ-based tube current modulation: A phantom study

“…Previous studies have shown OBTCM to significantly reduce breast dose in chest CT [6,15,36,37,39,42,47]. However, the real anatomy of patients' breasts in supine position can be very different from what has been seen in the phantom studies or when patient is in a standing or sitting position.…”

“…Moreover, Siemens approach compensates anteriorly reduced tube current by increasing the current during the posterior projections, whereas GE and Canon approaches do not [6,15,[36][37][38]. In chest CT, the overall dose-reduction percentages yielded by the OBTCM methods for the breasts have been reported to be between 5% and 48% compared to chest CT scan protocols utilizing normal TCM [6,15,[36][37][38][39][40][41][42][43]. However, it has also been warned that the dose may increase in some parts of the breast tissue outside the reduced dose zone [12,37,38,40,41].…”