My colleague at Deakin university Australia Peter Riley can likely answer your question

peter.riley$deakin.edu.au  or advise futher best wishes Paul Yielder

The easiest way of estimating effective dose form Cardiac CT scans is to use an E/DLP factor. However, keep in mind that allthough several studies use the chest factor of 0,014 mSv/mGycm, a typical Cardiac CT scan is more concentrated around the breasts, which is more radiosensitive. Huda et al. published an excellent article on the subject. Their factor is about 0,026 mSv/mGycm. A factor of 0,028 mSv/mGycm also comes to mind, but I cannot remember the origin of this factor at the moment.

A more accurate way would be to measure CTDI, or use the CTDI or DLP from the dose report as an input into the CT Dosimetry or CT Expo spreadsheets, if you are familiar with those.

Article Computing effective dose in cardiac CT

To physically measure the dose (rather than modelling), you can use a RANDO or ATOM phantom and use either TLDs or MOSFETs, this is measuring the organ doses directly, from which you can calculate E. This is more accurate than any modelling method, however it is significantly more time consuming, so it would depend on the reason that you are calculating E.

As well as the method of using the E/DLP factor, there is also the IMPACT Excel spreadsheet, which uses the SR250 montecarlo dataset to calculate E from the selected parameters and the CTDI values, the SR250 MC dataset is £50, but the spreadsheet is free.

http://www.impactscan.org/ctdosimetry.htm

If you are interested, I have attached an article from one of my PhD students on the variety of ways to calculate and measure E.

Article An overview of measuring and modelling dose and risk from io...

Yes. You can buy here samba data CTDI with the phantom 32 cm. It to get their data itself.

You can use the CT Dosimetry spreadsheet to calculate the effective dose values feeding the spreadsheet with your data or using the existing data in the worksheet.

If your CT is not listed in CT dosimetry spreadsheet you can calculate a correspondence factor and use a machine model that is on the list.

If the CT exists in CTDosimetry spreadsheet, you can calculate the effective dose in this way. Without the need to acquire data itself.

Now, if the CT is not in the spreadsheet you need to perform measurements with ionization chamber and phantom to acquire your data and so find a correlation factor. The british group ImpaCTscan calls this factor: ImpactFactor

Yes, measurement with the CTDI phantom is a good place to start.

The following paper might be of interest. Let me know if you are unable to access it

Assessment of patient dose and image quality for cardiac CT with breast shields.

Radiat Prot Dosimetry. 2012 Sep;151(3):463-8.

http://www.ncbi.nlm.nih.gov/pubmed/22492837

The best answer to this question may be obtained from the e-mail address [email protected]

Dear Khoramian,

CTDI is a metric for estimating ouput dose, and not for estimating patient dose. If you want to estimate the patient dose, you can use the new metric of size-specific dose estimate. We can download the report of AAPM 204 and also 220 about SSDE. My article gives the automatic technique to compute SSDE. Please review it. Thank you very much....