Also refer to this web page taking about different amounts of radiation on different structures of body.More information can be provided,if you need it as a personal interest.If you do not understand certain terminology or calculations,I can help you to clear your further doubts.
As your radiation history suggests a very long time difference and lapse between two simultaneous scans,so there is nothing to be worried about.Please comment.
http://www.cancer.org/treatment/understandingyourdiagnosis/examsandtestdescriptions/imagingradiologytests/imaging-radiology-tests-rad-risk
Though frequent radiation exposure may be lead to radiation sickness but it has some limitations on the amount of radiation you have been exposed to in a given time.The standards are as following-
1.In radiation terminology,rad is a unit of absorbed dose and a rem is a unit of any radiation dose to body tissue in terms to its biological effect.Roentgen(R) refers to amount of radiation dose delivered to the body.
2.Routine chest X-rays delivers 0.1-0.2 rem per exposure and final limitation is 1.5 rem per week and 5 rem per year.
3.Substantially radiation may have effects on the body based on the area of the body exposed for investigative purposes during routine Medical investigation of a disease.
4.Most of the severe problems of radiation exposure are due to hematopoitic failure,gastrointestinal damage like ulcers,CNS,secondary infection,pneumonitis.These damages are caused due to over exposure in the corresponding areas of body but not general as a whole body damage like the forums say.
5.You are not over exposed to radiation by frequent examinations for a 2 weeks duration.There is nothing to be worried about.