Dynamic experiments cannot be observed easy on patients for determination of dosimetry in human PET studies dosimeter studies. In this study, it is aimed to estimate dose amount absorbed by some critical organs (e.g. bladder, lung, thyroid and ovary) by using a developed phantom. The phantom was improved as an original anthropomorphic whole body phantom which has been arranged with dynamic system. Therefore, organ absorbed doses by applying of fluorine-18-fluorodeoxyglucose in PET studies and was observed by using the phantom, while TLD dosimeters were used for determination of internal absorbed doses. In medical physics, the accuracy of absorbed dose resulting from radiopharmaceutical application was determined by the medical internal radiation dose method that depends theoretically on the cumulated activity of the source organs and their mass. The MIRD calculation was also used for the study and comparatively evaluated with the experimental results which were collected by using improved phantom.