VirtualDose: a software for reporting organ doses from CT for adult and pediatric patients

Abstract

This paper describes the development and testing of VirtualDose--a software for reporting organ doses for adult and pediatric patients who undergo x-ray computed tomography (CT) examinations. The software is based on a comprehensive database of organ doses derived from Monte Carlo (MC) simulations involving a library of 25 anatomically realistic phantoms that represent patients of different ages, body sizes, body masses, and pregnant stages. Models of GE Lightspeed Pro 16 and Siemens SOMATOM Sensation 16 scanners were carefully validated for use in MC dose calculations. The software framework is designed with the 'software as a service (SaaS)' delivery concept under which multiple clients can access the web-based interface simultaneously from any computer without having to install software locally. The RESTful web service API also allows a third-party picture archiving and communication system software package to seamlessly integrate with VirtualDose's functions. Software testing showed that VirtualDose was compatible with numerous operating systems including Windows, Linux, Apple OS X, and mobile and portable devices. The organ doses from VirtualDose were compared against those reported by CT-Expo and ImPACT-two dosimetry tools that were based on the stylized pediatric and adult patient models that were known to be anatomically simple. The organ doses reported by VirtualDose differed from those reported by CT-Expo and ImPACT by as much as 300% in some of the patient models. These results confirm the conclusion from past studies that differences in anatomical realism offered by stylized and voxel phantoms have caused significant discrepancies in CT dose estimations.

Accuracy of patient specific organ-dose estimates obtained using an automated image segmentation algorithm

“…31 Additional studies are needed to compare the accuracy of the proposed patient-specific organ dose estimation method with previously proposed methods that are not patient specific 9,10,17,20,21 including commercial software packages that estimate organ dose to phantom models. 20 This pilot study modeled a CT acquisition with 8-cm detector thickness and a helical pitch of one, as CT scanners are trending toward larger volume coverage. Different acquisition geometries and pitch settings may increase the variation of the dose maps within small organs, causing higher sensitivity to segmentation errors.…”

A comparison of pediatric and adult CT organ dose estimation methods

“…Size-specific dose estimates (SSDE) were introduced in 2011 to adjust the CTDI vol to address the effect of the patient sizes on the average radiation dose, especially for small-size pediatric patients and large-size overweight patients [26]. Methods and recommendations of the calculations and usage of SSDE were updated in a later publication [27], but the quantity itself remained a poor estimate for individual organ dose that did not account for the tissue differences or the geometric location of the organ [22, 23, 28]. …”

“…However, they require great amounts of time, equipment, and skilled staff to perform [19, 29–35]. A practical method of accurate organ dose estimation is to use Monte Carlo (MC) methods and anatomically realistic computational anthropomorphic phantoms to simulate the CT scans and to calculate the organ doses [18, 20, 21, 23, 36, 37]. Sophisticated computation codes such as MCNPX incorporate the Monte Carlo method and can be used to model the CT scanner and simulate the transport of ionizing radiation in anthropomorphic phantoms [38–40].…”

“…A few newly developed dose calculators utilize anatomically realistic phantoms and provide better patient-matching options for organ dose calculation. VirtualDose is the first online organ dose and effective dose calculator that incorporates anatomically realistic phantoms for patients of various ages (including pediatric ages 0 through 15), gender, pregnancy stages, or body sizes [23]. …”

Monte Carlo calculations for reporting patient organ doses from interventional radiology

“…VirtualDose is a cloud-based software tool for assessing and reporting patient organ doses from radiological imaging procedures [1][2][3][4][5][6][7] . VirtualDose was designed to improve the patient dose estimation with considering the latest ICRP (International Commission on Radiological Protection) tissue weighting factors, several validated CT scanner models, scanner-specific correction factors, and a family of anatomically realistic phantoms which include female and male adults, children with different ages, pregnant females at different gestational stages and obese people of different body weights [8][9][10][11][12][13] .…”