Computed Tomography Dose Index in Computed Tomography (CT), Positron Emission Tomography (PET) and Single Photon Emission Computed Tomography (SPECT)

More deaths occurred without proper diagnosis and medication in the early days. Thus, proper diagnosis is necessary to overcome the issues faced in the early days. The identification of the nature of an illness or other problem by symptom examination is diagnosis. Significant advancements were made in the 20th century in combating disease by uncovering its causes and understanding how it spreads. This process of identification is performed through advanced technologies in the medical field. (i) Computed Tomography (CT), (ii) Positron Emission Tomography (PET), along with (iii) Single-Photon Emission Computed Tomography (SPECT), are some of the advanced technologies. The combination of CT with PET and SPECT has revolutionized the imaging capabilities in clinical diagnostics, providing detailed anatomical and functional information.  Concerns about radiation exposure, especially the Radiation Dose (RD) linked to CT scanning, are raised by the use of CT in these hybrid imaging modalities. Thus, by utilizing the aforementioned advanced technologies, this study focuses on the crucial field of analysis of the Computed Tomography Dose Index (CTDI). An indicator of the RD is the CTDI, which is primarily used to measure the radiation dosage absorbed during a CT scan. Thus, the overview of CT, the importance of CT-PET and SPECT, and the significance of CTDI and their Dose Indexes (DI) are explored in this review.