A low radiation computed tomography protocol for monitoring shunted hydrocephalus.

Abstract

Background:Computed tomography (CT) requires highest radiation doses in radiology. The collective dose from the use of radiation in medicine is rising, partly due to increase in CT use as well as the growing popularity of multislice scanners. There is growing concern from multiple studies that radiation from repeated CT scans could induce malignancies later in life. Patients with hydrocephalus are unique in that they are often subjected to repeated CT imaging throughout their lives to monitor whether their hydrocephalus is under control. We designed a study to see whether a low dose radiation CT protocol could provide effective information for monitoring hydrocephalus.Methods:A pilot study was done with 10 patients with hydrocephalus who needed CT scanning to monitor their hydrocephalus. The CT protocol was altered for each patient to sequentially bring down the radiation dose to the minimum level, which would provide sufficient diagnostic information. Based on the pilot study, a new low dose CT scanning protocol was devised and tested on 25 shunted patients who needed monitoring of their hydrocephalus. All images were carefully scrutinized by a consultant neuroradiologist and consultant neurosurgeon to ensure that the following diagnostic information could be analyzed: 1. ventricular size, 2. cisterns, 3. sulcii, and 4. cathet er positionResults:All low-dose CT images were diagnostically acceptable and provided sufficient information to the requesting clinician. None of the subjects required repeat imaging. The effective radiation dose was reduced from 2.2 mSv using a conventional CT protocol to 0.29 mSv with the new low dose CT protocol. The new CT protocol provides 87% less effective radiation dose compared with conventional scans.Conclusions:We propose a new low dose CT protocol which can be used for monitoring shunted hydrocephalus. The radiation to the patient with this protocol is comparable to that of a skull X-ray. However, this protocol should only be requested by a clinician who is aware of its limitations.