Choonsik Lee

National Cancer Institute, National institutes of Health

Investigator

NLST (Learn more about this study)

201209-0031

Aug 9, 2012

Establishment of CTDI library for a CT organ dose calculation tool, NCICT

I have developed an graphical user interface-based organ dose calculation tool, called NCICT software, for CT patients since 2009. A set of organ dose database was established by modeling a reference CT scanner (Siemens SOMATOM Sensation 16) coupled with a series of hybrid computational phantoms. An algorithm was developed to convert the organ doses for the reference scanner to the values of different CT scanners by using the weighted Computed Tomography Dose Index (CTDI), called CTDIw. Using the algorithm and a library of CTDIw values for many different scanners, one can estimate organ doses for different type of scanners from different manufacturers without measuring one’s own CTDIw which is impossible sometimes for retrospective dose reconstructions. I have collected CTDIw values from the following sources: CT survey in United Kingdom, German survey of CT factors, and United States NEXT survey. The CTDI library currently covers more than 200 scanner models from major manufacturers. Now I would like to expand/supplement the CTDI library by using the values measured and collected by the NLST study. From the previous articles from the study (e.g. Larke et al. AJR 20110). I understand the CTDIw values for CTDI body phantom for around 100 CT scanners are available as part of the equipment quality control data collected by the medcial physicists during the NLST. Once the NLST-specific CTDIw values are incorporated into the NCICT, the software tool will be also utilized to calculate the organ doses of the individual patient within the study of “CT Individual Patient Dose Project” (CPF-201110-0020) which is currently under way.