Radiation Therapy and Nuclear Medicine: An Assessment on the Importance of F18 FDG PET/CT in Dosimetry Planning

Objectives: Computed Tomography (CT) when paired with Positron Emission Tomography (PET) has advanced radiation planning by utilizing fused anatomical and functional images to provide the necessary information for cancer tumor biology and staging. It has been found to be dramatically successful when imaging head and neck cancers, lymphomas, and non-small cell lung cancer. Considering the radiopharmaceuticals used in PET/CT studies today, Fluorine-18 Fluorodeoxyglucose (¹⁸F-FDG) PET studies have enhanced the ability to provide the distinctions between cancer tumors and malignancy. ¹⁸F-FDG, as a glucose analog, is an efficient way to image the metabolism of cancer tumors and structurally differentiate between the targets of interest and neighboring normal tissue. In some cases, this has given oncology enough information to observe previously undiagnosed diseases. The use of this modality has been a monumental addition to imaging departments and it continues to have an important role in the improvement and accuracy of dosimetry planning for cancer patients. The purpose of this study is to demonstrate the value of utilizing ¹⁸F- FDG PET/CT studies to create successful radiation planning paths for head and neck cancer patients.

Methods: Retrospectively, ¹⁸F-FDG PET/CT dosimetry studies of limited area head and neck were reviewed from the previous eight months. One patient case was selected for the purpose of this study. The patient case selected received repeated limited area head and neck ¹⁸F-FDG PET/CT dosimetry planning imaging. The patient’s images, physician’s notes, and radiation oncology notes were referenced. The medical college library was also used for supporting articles and sources.

Results: This paper evaluation of the chosen case study showed that ¹⁸F- FDG PET dosimetry planning has a positive effect on the patient receiving such studies. Evidence of significant response of the patient’s primary malignancy to treatment correlates with two subsequent PET/CT ¹⁸F- FDG studies. Both studies demonstrate significant decreases in ¹⁸F-FDG avidity and size of malignant tissues.

Conclusions: Highly specific and accurate scans suggest that the implementation of PET ¹⁸F-FDG has had a positive effect on the planning process for patients undergoing cancer treatments. Follow-up imaging has shown the value of proper physiological imaging and its use in radiation treatment planning. Mckay MJ, Taubman KL, Foroudi F, Lee ST, Scott AM. Molecular Imaging Using PET/CT for Radiation Therapy Planning for Adult Cancers: Current Status and Expanding Applications. International Journal of Radiation Oncology, Biology, Physics. 2018;102(4):783-791. Andersson C, Roing M, Tiblom Ehrsson Y, Johansson B. It’s a question of endurance - Patients with head and neck cancer experiences of 18F-FDG PET/CT in a fixation mask. European Journal Of Oncology Nursing: The official Journal of European Oncology Nursing Society. 2017;29-85-90. Brunetti J, Caggiano A, Vialotti C. Functional anatomic imaging in radiation therapy planning. Cancer Journal (Sudbury, Mass). 2004;10(4):214-220.