RAD Exposure Dose to Neonates , Operators and Attendants Using MobileDaRt Evolution

It is well known that chest X-ray imaging plays a very important role in the diagnosis of chest lesions in neonates 1) . However, concerns exist that the exposure of neonatal patients to increasing quantities of radiation through imaging will increase the future risk of cancer development. Additionally, the exposure dose received by the operator and attendants is also of concern, as they often stand very close to the neonatal patient when mobile X-ray system is used in an NICU (neonatal intensive care unit). As a result, in recent years there has been increased interest in the exposure dose received from chest X-ray imaging by neonates, operators and attendants. There is a demand for the precise assessment of exposure dose based on experimental measurements. The spread of digital X-ray system equipped with an FPD has increased remarkably, with an increasing use of mobile digital X-ray system in the NICU. There are many advantages to using digital X-ray system, including the reduced time to image display and increased image quality. Fig. 1 shows the MobileDaRt Evolution mobile digital X-ray system, made by Shimadzu and equipped with a Canon CXDI-60C flat panel detector (FPD). The MobileDaRt Evolution has been shown in reports to exhibit excellent performance in terms of operability and image quality 2) . In this study, we measured and evaluated quantitatively the exposure dose to neonatal patients and the surroundings (operators and attendants) during chest X-ray imagining with the MobileDaRt Evolution, and examined whether the exposure dose can be reduced. This article will give a brief explanation of this study that can be examined in more detail by referring to the original article 3) . Before measuring exposure dose, we investigated the basic characteristics (digital characteristics) of the FPD. After this, a patient skin dosimeter (PSD) was placed on a phantom that represented a neonate. The exposure dose to the neonatal patient was measured and the dependency of exposure dose on imaging conditions was investigated. Next, we recreated as far as possible the conditions present during the actual imaging of neonates when placed within an incubator (Incu i, Atom Medical Corporation) in an NICU and used a survey meter to measure exposure dose around the incubator during X-ray imaging and estimate the exposure dose to the operator. The system used during experimentation was a MobileDaRt Evolution (Shimadzu Corporation) equipped with an FPD (CXDI-60C, Canon). The MobileDaRt Evolution is capable of imaging in a tube voltage range of 40–133 kV and mAs parameter range of 0.32–320 mAs. The CXDI-60C FPD uses CsI as a scintillator, and has 1464 × 1776 pixels and a maximum image size of 23 cm × 28 cm. The study presented in this article was conducted as joint research with associate professor Hajime Monzen and others of the Medical Physics Group of Kyoto University during my tenure in the Graduate School of Medicine at Kyoto University.