Doses to skin during dynamic perfusion computed tomography of the liver

Abstract

Many new computed tomography (CT) techniques have been introduced during the recent years, one of them being CT-assisted dynamic perfusion imaging (perfusion CT, PCT). Many concerns were raised when first cases of deterministic radiation effects were reported. This paper shows how radiochromic films can be utilised as passive dosemeters for use in PCT. Radiochromic dosemeters undergo a colour change directly and do not require chemical processing. Prior to their use, they need to be calibrated. Films are placed on top and on the right side of the patient and exposed during the procedure. Readout is performed using a densitometer. Results show that average local skin doses are 0.51±0.07 and 0.42±0.04 Gy on top and on the lateral side of the patient, respectively. Results of the patient dosimetry (local skin doses) are consistent. This is due to the fact that each patient had the same CT protocol used for imaging (120 kV, 60 mA and C(vol) of 247.75 mGy). Radiochromic films designed for interventional radiology can be effectively used for local skin dose measurements in perfusion CT. Dose values obtained are below the threshold needed for deterministic effects (erythema, hair loss, etc.). These effects might happen if inappropriate CT protocol is used; one that is usually used for routine imaging.

Basis and current state of computed tomography perfusion imaging: a review

“…Zhang et al reported that the peak skin dose ranged from 87 to 326 mGy in the Monte Carlo simulation in the CCTP imaing study (Zhang et al 2012). Beganovic et al reported that the skin doses were 510 ± 70 and 420 ± 40 mGy for top and lateral of patient in the dynamic CTP image acquisition (Beganovic et al 2013). Arandjic et al presented that the skin doses ranged from 340 to 800 mGy in the CCTP imaging study (Arandjic et al 2013).…”

CT Dynamics: The Shift from Morphology to Function

“…Liver perfusion with CT can help assess chronic liver diseases such as chronic hepatitis, liver fibrosis, and cirrhosis as well as detect primary hepatic carcinomas [55,56]. Other recent studies have looked at reproducibility [57], assessing and lowering the radiation dose [58,59], comparing to arterial spin labeling with MR [60], and have examined different analysis methods [61]. Miles et al [62] first described the use of perfusion CT in the pancreas in 1995, but widespread application of the technique has been limited by the inability of conventional CT to cover the entire organ and the respiratory motion that can shift the organ out of the field of view.…”