Dose of TEP/TDM to patients as part of the care of lymphomas

Abstract

Introduction Last years, the patient dose has increased with the evolution of diagnostic practices. Hybrid imaging technology and in particular PET/CT (positron emission tomography/X-ray computed tomography) is one of diagnostic exam in oncology field. In this aim, we studied dosimetric impact of accumulated diagnostic exams for lymphomas patients. Treatment This exam is performed during the staging, during, the treatment, for an early therapeutic evaluation and finally during a post treatment observation. The frequency of the CT exams type injected TAP (thoraco-abdomino- pelvic) in addition to PET/CT lead to an increase of the patient dose. Equipment and methods An additional exam is performed in the liver for the TAP, that's why we consider dose calculation of the organ in CT with the help of CT EXPO dosimetric program and calculation of the total effective dose (E) received by the patients affected by lymphomas by the analytical method based on the conversion factor to obtain the effective dose for 30 patients per year. Equivalent dose calculation with analytical method will be possibly performed with Oedipe dosimetry program. Results The accumulated effective doses (E) of patients is very high as part of the monitoring of pathologies such as lymphomas. Example for one patient followed a year who had 4 TEP/TDM + TDM injected and one TEP/TDM: – PET per year E = 16.5 mSv. – PET/CT (low dose) per year E = 88 mSv. – PET/CT + injected scanner (CT exam in liver and injected TAP) per year E = 215 mSv. This same procedure has been performed for 30 patients. Conclusion To decrease the dose for the patients with lymphomas two solutions are in study: – Justification of the additional CT exam in the liver for injected CT. – The optimization of the acquisition parameters on CT. These two themes will be communicated during the oral presentation.