"I have been waiting 3 weeks for results"

I have no complaints about my MRI scan at Bolton Diagnostic Unit. Only a query, can you explain to me why it takes 2-3 weeks to get results? When one is worried about a complaint, it will approximately be six weeks since I first consulted a doctor to get treatment. These cases make the patient stressed and feel more ill. I would like a reply with an explanation. I will understand if it is due to research on the scan, but would hope that if there is a serious problem the doctor would inform the patient less than 2-3 weeks. This is not explained on leaving the unit.