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LAR( PER 100,000)

30 25 20 15 10 5 0

( i) All solid

Fig. 2. Continued.

durations typically lead to higher dose( Karim MKA et al., 2017). The imaging protocol and patient’ s characteristics has been identified as major contributing factor in optimization of CT dose( Harun et al., 2020).

According to ICRP Publication 106, PET / CT examinations conducted in this study are deemed safe, as the E to A ratio does not exceed 1.9 10 �2 mSv / MBq( ICRP, 2008). However, the E to A ratio depends on the radiopharmaceutical, imaging procedure, and patient characteristics. Factors such as patient age at exposure, body weight, and imaging protocols also play crucial roles in determining the effective dose. It is therefore essential to assess the ratio of effective dose to administered activity across different nuclear medicine procedures to maintain patient radiation safety.

The stochastic risks associated with PET examinations involving the injection of radionuclides into a patient’ s body generally involve the potential development of cancer and genetic effects that could be seen in those who have been exposed to radiation( ICRP, 2022). However, the radiation dose in PET examinations is generally lower than in other imaging techniques like CT or nuclear medicine therapy( Andersson et al., 2017b; ICRP, 2015; Murat et al., 2023). In this study, we calculated the LAR of cancer incidence and analyzed how different organs contribute to this risk. Organ

dose for PET examinations can be estimated by using IDAC- Dose 2.1 by utilizing equation( 1) and biokinetics data from ICRP Publication 128 and summarized in results section Table 2. Table 4 present the b coefficient used to calculate LAR, as outlined in equation( 4) derived from a 3 rd order polynomial generated from the data in the BEIR VII phase II report( ICRP, 2015; National Research Council, 2006). In addition to the radiation dose, estimating LAR involves taking into account factors such as cancer baseline rates from population data, risk models, and survival functions( ICRP, 2022; National Research Council, 2006). In our analysis, we have utilized the BEIR VII phase II report cancer baseline rates as the foundation for estimating LAR associated with radiation exposure. These American cancer baseline rates are derived from extensive epidemiological data collected and maintained by reputable institutions, providing a thorough understanding of cancer incidence across diverse demographics( Kessara et al., 2023; National Research Council, 2006). This makes them a valuable benchmark for risk assessment in this study. However, incorporating local cancer baseline rates such as Asian population, into radiation risk assessment models could provide a more tailored approach to understanding the LAR of the Malaysian population( Halid et al., 2018; Karim MKA et al., 2016).