What is different between CountsAccumulated(from dicominfo) and summation for the whole images??

Dear All,

I have image as attached. the type is int16. have 45 frame, size 128x128. This is SPECT images.

When I wrote the script as below

[spect map]=dicomread('SPECTCTLD_EM_IRNCRR001_DS.dcm');
info = dicominfo('SPECTCTLD_EM_IRNCRR001_DS.dcm');

I got the CountsAccumulated (as picture attached) is 9363226. This information from dicominfo.

When I wrote the script as below

sum(sum(sum(spect)));

The answer is 14981059

Anyone can explain the CountsAccumulated is represent what?

and

summation spect is repsresent what?

Why this two value is not same??

What I understand is the CountsAccumulated represent the total pixel value for the whole image

Answer 1

[Ramtej]

Hi Akmal,

The "CountsAccumulated" value that you get from the "dicominfo" function is a piece of metadata stored within the DICOM file. It represents a specific value that is meaningful within the context of the SPECT image acquisition, and it's likely to be the total number of detected events or counts accumulated by the gamma camera during the image acquisition process. This value is determined by the imaging hardware and the acquisition protocol and is stored directly in the DICOM file by the machine that performed the scan.

On the other hand, when you execute the command "sum(sum(sum(spect)))" in MATLAB, you are calculating the sum of all pixel values within the 3D array "spect" that contains the SPECT image data. This value is a computational result obtained by adding up all the individual pixel intensity values across all frames of the image.

Hope this makes the differences clearer!