What do you want to measure by using Rando phantom?

If u want to measure the organ dose, you can order customized rando phantom with TLD placement inside.

However, if your phantom is still original, you can still chip off to make a hole inside for TLD placement, the air gap will not interference your measurement. It's better rather than you just put in between of slices, since the air gap is bigger and scattered dose occurred is higher than previous method.

Cheers,

MY

 yes to measure the organ dose 

and we have here oready the rando phantom but the problem is how i fit the tld inside the hole ?

another thing , i want to measure the chest ,abdomen and head , how meny chips i need for each one ? could you suggest to me ? 

Dear Ahmad,

As I mentioned earlier, you can chip off or make a small hole for your TLD placement. It will not create such big air gap for your organ dose measurement.

Regarding to the TLD placement for measuring your organs. You should think also about the interference between your TLD, if you insert your TLD too much, it will add another dose to your organ due to photon scattering due to TLD interference. 

I suggest you to see how many slices of each organs you want to measure and the size of each organs then you can estimate the amount of TLDs that you really need.

Herewith I attach some references for your consideration during estimate the amount of TLD needed.

MAIL, N., YUSUF, M., ALOTHMANY, N., KINSARA, A. A., ABDULKHALIQ, F., GHAMDI, S. M. & SAOUDI, A. 2016. A methodology for on-board CBCT imaging dose using optically stimulated luminescence detectors. Journal of Applied Clinical Medical Physics, 17.

YUSUF, M. & KINSARA, A. A. 2015. Preliminary Study in In Vivo CT Dosimetry Using Optically Stimulated Luminescence Detector (OSLD). Journal of King Abdulaziz University, 26, 85.

YUSUF, M., SAOUDI, A., ALOTHMANY, N., ALOTHMANY, D., NATTO, S., NATTO, H., MOLLA, N. I., MAIL, N., HUSSAIN, A. & KINSARA, A. A. 2014. Characterization of the optically stimulated luminescence nanoDot for CT dosimetry. Life Sci. J, 11, 445-450.

Hopefully it will help you.

Cheers,

MY

thank you 

do you have  any idea  for using small ion chamber to do CT scan dosemitry ( a new method instead of using pencil chamber ) 

or you know someone 

i need to contact wth any one who involve in this filed regarding to my project 

Dear Ahmad,

Well you can try to ask Dr. Abdelhameed Saoudi.

https://www.researchgate.net/profile/Abdelhamid_Saoudi

I think you know him so well.

Cheers,

MY

thank you

A short tip to tld in randso. Drill small cylindrical holes, enough to put a small cylindrical pmma tube with a central hole for cylindrical tlds. You will get commercial hints by PTW in germany Freiburg.

thank you

By calibration with a source with known dose rate. I will send you a chapter of my textbooks if you are able to translate. Let me know it. My books are written in german.

Kindly deliver 1 gray dose to 5 TLDs substruct background say reading of 5 other unexposed TLDs. Hopefully all 10 TLDs were annealed previously. Read all under similar conditions same parameters. If 1 gray gives 1 Nano coulomb assuming linear region 2 gray will be 2 nc and 5 gray will be 5 nc. In tl always maintain calibration. 

Refer standard book on TL for calibration procedures. There are lots of book and large number of papers.

i will explain more 

i have put the pencil chamber under the x ray mobile and i do it 4 times then i got the average which was 4.26 mGy

then at the same condition and input i have put the 22 tld chips , when i read it in the reader the unit was  nc 

on of the tld ships was 926 nc and the average of 22 chips was 946 nc 

so i want to convert  each tld chip from nc to mGy to compare it to pencil chamber

so how i convert 926 nc to mGy or Gy?

Here u must have unexposed tld chips say 3 or 5 or so. Read them. Get instrument background etc. Subtract from 926 nc. Take other 10 chips. Expose 7 to known dose with calibration lab use xays or other source. Read all and Subtract background. Assume l now dose was 10 mgray and u got 1800 nc net signal. Then 1800 nc is 10 mGy so for ur reader 180 nc correspond to 1 mGy. It's better to calibrate with standard source. 

Both the devices will give same answer within errors provided calibration is proper.

i got it 

but if you can give me example on my measurement to be clear more 

as i told you i exposed pencil chamber and it is 4.26 mgy

now i have 10 tld ships and i want to make sure the each tld ships receive the same amount of 4.26 mgy 

first i take 3  unexposed tld and i take the average from them

then i expose the 10 tld and i read it then  i subtract each one from the average unexposed

if we assume one of them is 800 nc 

so you mean the 800 nc is 4.26  

and if we assume another tld was 750 nc 

so 750 nc is 4.26 

??????( i think we have to take the average )

i think   take the average from the 10 tld after the subtract them from the unexposed tld. then the result will be is 4.26 mgy

is this right?

and is this a good way to calibrate TLD in radiation diagnostic  ?

U are right. Average exposed reading minus average unexposed reading will be equal to delivered dose. Rest is same as u mentioned. But note that

. This delivered dose should be preferably using some standard source or machine whose dose reproducibility is within 3 to 4 percent. Since ur tld readout lif based or so. They practically exhibit energy independent response so u can use xays or Cs source for standard calibration. If you r sure of chamber then this can crudely work. Establishing independent calibration will prove that tld and chamber independently give correct answer otherwise u r only trusting chamber reading whether right or wring. 

you can find it in my article

Dear Ahmad,

Just to add a concern about your calibration technique using pencil chamber. To get the precision value of dose, you need to know the active length and dose profile from your pencil chamber. Otherwise you will get the deviation dose which is smaller than the peak dose.

Cheers,

MY

Great question with useful answers.