Introduction: The incidence rate of lung cancer has been steadily increasing during the recent years domestically and worldwide. Amongst the five most prevalent cancers in Slovenia, lung cancer has the worst prognosis. Lung cancer patients, both male and female, have an average five years survival rate of 14.6 %, with the number increasing annually. Radiotheraphy is the preferred method of treatment for certain types of lung cancer. Treatment planning has been done on positron emission tomography with compudet tomography machine via the established classic protocol and radiotheraphy planning protocol. These two methods mainly differ in technical parameters, which results in different radiation dose for the patients. Purpose: We intended to establish the difference between the classic positron emission tomography and compudet tomography protocol for lung cancer screening and treatment planning positron emission tomography with compudet tomography protocol, compare computed tomography radiation doses on patients and try to find an optimized approach to both. Methods: A descriptive method to explain the basic concepts of positron emission tomography with compudet tomography planning and parameters involved was used. Statistical analysis has been implemented to compare radiation dose data between the two methods, as well as the dose before and after an improved iterative reconstruction SAFIRE has been used. The results were presented in a qualitative and quantitative manner with a commentary on efficiency and viability of methods used. Results: It was established that there are statistically significant differences between radiation doses that patients receive in the classic positron emission tomography with compudet tomography protocol for lung cancer screening and treatment planning positron emission tomography with compudet tomography protocol (p < 〖10〗^(-3)). Statistically significant differences were also found in radiation dose on patients before and after the improvement of iterative reconstruction method (p=0.001). Discussion and conclusion: We observed a 67.7 % lower radiation dose on patients when the iterative reconstruction was used on a classic positron emission tomography with compudet tomography protocol, while the dose was further lowered by additional 34.2 % when the improved iterative reconstruction method SAFIR was implemented. Our results and the studied sources suggest that iterative reconstruction may becoming increasingly viable in radiotheraphy treatment planning procedures. It would be prudent to further research the effect of lower patient dose on selecting and defining target volumes for radiation treatment.
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