I am conducting a study on different image reconstruction algorithms for computed tomography (CT). My aim is to investigate which of the image reconstruction algorithms that have the highest signal-to-noise ratio (SNR). My dataset is 100 patients who underwent a CT brain scan. Each CT scan will be reconstructed with 4 different image reconstruction algorithms. Then I will measure the SNR for each algorithm and patient and compare the different reconstruction algorithms with regard to the SNR. So, we scan the patient's head and then the computer at once provides four different image reconstruction algorithms of the scan (4 different image sets) and then we measure the SNR of each image set and compare it to the other reconstruction algorithms (other image sets). Or, if it makes it easier for you to think. Consider the following corresponding scenario: You take a blood sample (corresponding to "CT scan") from the patient and measure the glucose level with 4 different apparatus (corresponding to the 4 different image reconstruction algorithms). And then you compare the blood glucose level (corresponding to "the SNR") between the four different apparatus. So, my question is if I should use a repeated measures ANOVA or just an ordinary one-way ANOVA.
Since you have repeated measures within subjects it is necessary to control for the non-independence of observations within subjects. That is, observations within one subject are likely to be more similar than observations in other subjects.
So in this case you will need to use a repeated measures ANOVA