According to the definition, CTDIvol is obtained by dividing CTDIw by pitch factor.
The use of tube current modulation results in different CTDIw values for every rotation. Even though CTDIw is not constant during the whole scanning, the CT scanner displays a CTDIvol value at the end of the examination. How is this value calculated? I'm especially interested in how Siemens Somatom machines calculate it (in case different CT producers have different methods).
Maybe these links will help you:
https://www.aapm.org/meetings/2011CTS/documents/McNitt-GrayAssessingRadiationdoseFINAL.pdf
https://www.aapm.org/meetings/2013CTS/documents/FRI_02McNitt-Gray.ARS.pptx
https://www.aapm.org/meetings/2013CTS/documents/Fri_10SupanichTCMFinal.pdf
http://static.healthcare.siemens.com/siemens_hwem-hwem_ssxa_websites-context-root/wcm/idc/groups/public/@us/@imaging/documents/download/mdaw/ndq2/~edisp/low_dose_session_27_v2-00308413.pdf
Best regards
Dear Falk Tillner,
Thank you very much for the links.
Best regards
Albertina
Dear Albertina,
You must know that the CDTIvol is not the reflect of the dose to the organ but is a tool to compare the effective dose between different Imaging technics. for example, for a brain CT the dose is almost received by the brain, the eyes and thyroid, so the dose to this organs is higher than the ED calculated from the PDL or CDTIvol value. For more explanations, i recommand the IRSN publication ( in french) IRSN rapport drhp/ser n° 2010-12
Dear Fabienne,
Sorry if my question was not precise enough. My question was not about the meaning of CTDIvol or doses to organs or how to calculate effective dose using CTDIvol or DLP. What I'm interested in is the method the CT machine is using to calculate CTDIvol when the scanning protocol implies use of tube current modulation (the formula).
Best regards,
Albertina
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