Tehran University of Medical Sciences Frontiers in Biomedical Technologies 2345-5837 12 2 2025 03 01 309 319 EN Anahita Jafari Medical Imaging Research Centre, Shiraz University of Medical Sciences, Shiraz , Iran Fariba Zarei Medical Imaging Research Centre, Shiraz University of Medical Sciences, Shiraz 7193635899, Iran Hamidreza Masjedi Medical Imaging Research Centre, Shiraz University of Medical Sciences, Shiraz 7193635899, Iran Samira Moshiri Medical Imaging Research Centre, Shiraz University of Medical Sciences, Shiraz 7193635899, Iran Vyas Akondi Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Berhampur, Berhampur, Odisha 760010, India Sabyasachi Chatterjee Retired Scientist from Indian Institute of Astrophysics, Present Affiliation: Ongile, 79 D3, Sivaya Nagar, Reddiyur Alagapuram, Salem 636004. India Rezvan Ravanfar Haghighi Medical Imaging Research Centre, Shiraz University of Medical Sciences, Shiraz , Iran 2024 02 18 2024 05 30 Purpose: The purpose of this study is to test the linearity of the CT system and ascertain the relationship between Hounsfield Unit ( ) values and weight/weight concentrations of iodine ( ) in mixtures. This aims to determine the iodine concentration thresholds for achieving effective contrasts with minimal iodine usage. Materials and Methods: Aqueous solutions of Iopaque, with 300mgI/mL of iodine, were prepared for different weight/weight ( ) iodine concentrations and filled in a water-pool phantom, and the  observations were taken at different kVps for 10 different CT machines. The variation of  with  was analyzed as, . From this, the  necessary for getting a required  value is estimated. Results: It is found that HU(V) varies linearly with  for low wi values, although the coefficients  and  vary widely between machines. For optimal HU enhancement, it was found that a 0.01% weight/weight concentration of iodine is adequate to produce an  value of 450 at 80 kVp, while the corresponding concentration should be 0.025% weight/weight at 120 kVp. Conclusion: Linear dependence of HU on wi helps to reduce the contrast media volume by estimating the iodine concentration, necessary for obtaining a required HU. It also revealed that lower kVps could yield adequate HU enhancement with a reduced contrast agent, thus potentially minimizing patient exposure to radiation and contrast media. https://fbt.tums.ac.ir/index.php/fbt/article/view/940 https://fbt.tums.ac.ir/index.php/fbt/article/download/940/496