Positron Emission Tomography or PET Scan (TEP in French) is used in the exploration of the different stages of cancer particularly in the extended examination.

The PET is a functional medical imaging examination which allows for measurements to be taken in 3D showing the metabolic evolution of tissues. The scintigraph is undertaken after the intra-veineuse injection of a mild radioactive tracer - FDG18F. The tracer, similar to glucose, fixes itself to tissues temporarily and the rays detected are drawn by a tomograph for positron emission. At the same time readings are taken by a classic X ray showing the 2 iconographies by superposition.

Use in Medicine
The PET produces a funtional image by opposing two anatomical images that have been taken by MDT or MRI. The PET shows pre-dysmorphic lesions situated in the interior of zones which do not allow for simple structural analysis.

The systematic restradification MNT after PET allows for an improved diagnostics and allows for an improved theraputic plan in 53% of cases.

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Radio Protection
During tomography by emission of positrons the patient receives a dose of 10mSv which corresponds to the dose received duing a abdominal-thoracic scanner, almost negligable. The injected particles vary according to the weight and age of the patient, but the period or activity of the product is divided par 2 and the 18F is in the order of 110 minutes, therefore, within 12 hours the quasi-totality of the radioactivity has disappeared.

The PET Centre Roger PEREZ in Sarcelles adheres to the radioprotection normes in place for its patients and personnel. The centre is controlled yearly by the Nuclear Security Authority.


Patients should faste 6 to 8 hours before the examination, water may be taken in large quantity. The patient should avoid physical exercise the day before the examination to avoid the stimulation of glucose which would be consummed by the muscle fibres.

Delays between examinations must be respected : chemotherapy - 3 weeks, radiotherapy - 3 to 4 months, surgery - approximately 1 month and after an injection of factors for hematopoietic growth - 1 week before the PET examination - these treatments could modify the dispersion of the tracer.

Diabetes is treated normally. A glycemia inferior to 1.5mg/10l
The examination itself will last, in general, half and hour, the patient should plan to stay in the centre 2 to 3 hours to complete the procedure. The patient can drive a vehicle and return home alone after the treatment. A light restorative snack is suggested after the examination.