Hi, can you please concretise your question: (1) do you need information on the elemental composition of heart and spinal cord or (2) do need help with code programming / implementation in pegs4?

As I'm not firm with pegs4/dosxynrc, I cannot tell you something on point (2). But I can try to give you some hints on point (1):

The NIST databases "STAR" and "XRayCoef" include elemental composition of human body tissues, defined, for example, by ICRU or ICRP.  You will find this information at:

http://physics.nist.gov/cgi-bin/Star/compos.pl

http://physics.nist.gov/PhysRefData/XrayMassCoef/tab2.html

http://www.pnnl.gov/main/publications/external/technical_reports/pnnl-15870rev1.pdf

Unfortunately, you will find no records for "heart" or "spinal cord". Therefore, I would suggest some approximation:

- for "heart" you can use a mixture of "muscle, striated" and "blood". According to the following link, the mean heart volume is about 500 - 800 ml, while the blood volume inside the heart is about 40 - 80 ml (70 - 130 ml during sportive activities) both depending on the gender (maybe you find another quotable publication). This would result in a mixing ratio of about 10 : 1.

http://vmrz0100.vm.ruhr-uni-bochum.de/spomedial/content/e866/e2442/e9012/e9017/e9295/e9336/index_ger.html

- for "spinal cord"you can maybe use "brain" but i fear, that "brain" contains a considerable proportion of liquor, which is not suitable for nerve tissue / spinal cord itself. Instead, there are some very old publications dealing with chemical composition of nerve tissue, maybe there you can find something helpful:

https://www.jstor.org/stable/i283495 (supplement)

http://www.ncbi.nlm.nih.gov/pubmed/13389642

One additional comment: To make a more realistic thorax phantom, you should consider also including other tissues, such as types of soft tissue (skeletal muscles, breast tissue, adipose tissue) and  bones (spine, rips,). But, this depends on your studie's aim.

Best regards

Hi 

thank you so much to your answer.

I suggest that you contact either of Prof.'s Hirayama, Richard Hugtenburg orAlex Bielajew. They usually have good databases and always respond.

hello dr gilani

thank you so much for your anwer.

You are very welcome Milad. Did you work?