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Titre : | Impact du rayonnement émanant d'un radio-pharmaceutique technétié sur les mesures ostéodensitométriques par DEXA |
Auteurs : | Jawad Ben Aïssa, Auteur ; Pauline Demarbaix, Promoteur |
Type de document : | Travail de fin d'études |
Editeur : | Bruxelles : Institut Paul Lambin, 2020 |
Langues: | Français |
Index. décimale : | TFE - Imagerie médicale |
Résumé : |
Objectives:
The aim of this work is to assess the impact of radiation from the 99mTc-labeled tracer on the measurement of bone densitometry realized with a DEXA HOLOGIC - HORIZON and to make a comparison with the errors due to changes in operators or the inaccurate reproducibility of patient positioning Methods: Usually, a patient who undergoes a skeletal scintigraphy (bone scan) must wait 3 to 4 hours between the injection of the tracer and the late images. The first step of the experiment consists in measuring dose rate measurements were performed on a sample of 15 patients who had an appointment for a bone scan. The aim will then be to reproduce these activity rates in phantoms which will be used in the DEXA device. The DEXA exam will therefore not be performed on patients. For each patient, 2 measurements were made. One a few minutes after the injection of the tracer and a second measurement 3 to 4 hours after the injection, when the patient returned for the late images. Then, 2 means were calculated. So, two experiments will be carried out, one experiment with the average dose rate of the "morning" and another experiment that will be carried out in the same way as the first one but with the average dose rate of the "return". For DEXA experiments, a patient was simulated for the densitometric measurements using a spine phantom and a flood phantom. For each of the experiments, an activity corresponding to the average dose rates calculated previously will be injected into the "flood phantom". Then 10 densitometric measurements will be performed. And finally, a percentage of error has been calculated for both experiments thanks to the reference values on the "spine phantom". For the comparison with the percentage of error due to operator changes, 6 TIMs have each performed 3 positioning and 3 measurements of the spine phantom itself positioned in the same way as for the two previous experiments, on the flood phantom. Results: Random and systematic error percentages of Bone Mineral Density (BMD) and Bone Mineral Content (BMC) are calculated for each experiment. For inter-operator variability, the random error for the BMC is 0.367% and for the BMD is 0.2555%, the systematic error is -3.977% for the BMC and 1.959% for the BMD. For the experiment with the activity of the morning, the random error for the BMC is 0.425% and for the BMD is 0.458%, the systematic error is -4.578% for the BMC and 2.103% for the BMD. And finally, for the experiment with the activity of the return, the random error for the BMC is 0.332% and for the BMD 0.178%, the systematic error is -4.015% for the BMC and 1.516% for the BMD. Comparing the T-score and Z-score of each experiment, there is a small difference in the results. For inter-operator variability, we have a T-score of -1.06 SD and a Z-score of 0.38 SD. For the experiment with activity of the morning, the T-score is -1.02 SD and the Z-score is 0.39 SD. And to finish the experiment with the activity of the return, the T-score is -1.1 SD and the Z-score is 0.3 SD. Conclusion: Contrary to popular belief, it appears that DEXA measurements are not significantly affected by a prior injection of 99mTc, either within minutes or several hours afterwards. This may have an impact on the organization of appointment schedules. Measurements in real life (in vivo), with real patients injected, will still have to be carried out. This will need to be authorised by an ethics committee, possibly for future end-of-study work. |
Accès : | Identifiez-vous avant d'accéder au document électronique |
Disponible en ligne : | Oui |
Lieu du stage : | Chirec Delta |
Département : | Imagerie médicale |
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