Doses to skin during dynamic perfusion computed tomography of the liver

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.