Polymer gel dosimetry due that X-ray CT has been used to measure dose response and dose distributions in 3D the resulting images, which are reconstructed

from linear attenuation data, have Hounsfield units (HU) which are directly proportional to physical density changes of the polymer gel dosimeters....only that you need a anthropomorphic phantom or a simple water phantom and its holder.

Hi Daryoush, 

If the organ you are interested in calculating the dose is in the fully present in the image, you can approximate the measured CTDi to organ dose. As I mentioned, the organ has tone fully within the image. CTDi is easy to calculate with a ion chamber and simple phantom. 

If the organ is not within the scan range, I would suggest monte carlo for calculating not measuring the dose and as you mentioned TLDs for measuring. Just remember that TLDs have one simple limitation of not being able to record very small doses.

Hope that helps,

Thiago

There are numerous published tabulated conversion factors to relate recorded dose length product (DLP) or CTDI to organ doses or effective dose, for example Lee et al, Med. Phys. 39 (4), April 2012. These need to be patient size and beam energy specific. You could try an existing CT dose calculation tool such as CT-Expo (Stamm and Nagel 2011) or imPACT (http://www.impactscan.org/ctdosimetry.htm). 

Dose-length product (DLP) is the most representative measure if you are looking for measuring dose over a volume not just a single slice.

You might want to look at the method developed by Walter Huda and me.  Using the free-in-air isocenter kerma, we measured the ratio to organ doses in multiple anthropomorphic phantoms.  Very easy approach to organ dose:

https://www.researchgate.net/publication/51712835_In-patient_to_isocenter_KERMA_ratios_in_CT

https://www.researchgate.net/publication/221723131_KERMA_ratios_in_pediatric_CT_dosimetry

Article In-patient to isocenter KERMA ratios in CT

Article KERMA ratios in pediatric CT dosimetry

I add two matching papers from Zankl et al about dose conversion coefficients for adults and child with tube current modulation published in IOP Science.