A new approach to feedback control of radiofrequency ablation systems for large coagulation zones
Notice bibliographique
Résumé
Aim: The aim of this study was to investigate the feasibility of achieving relatively large coagulation zones (i.e. ≥3 cm in diameter) with radiofrequency ablation (RFA) by using a broad control system.Materials and methods: A broad control system consists of information such as (i) the area of the tumour tissue for feedback control, (ii) the set-point temperature and (iii) the control law. The proposed approach has advanced knowledge in (i) and (ii) in particular. RFA is known to be limited by tissue dehydration that occurs around the electrode, which results in impedance such that no further energy can be delivered to the tissues. We proposed the notion of “energy gate”, an area on the electrode, which is not covered by the dehydrated tissue and through which energy can still be delivered to the surrounding tissues. Given a specific size of energy gate, both (i) the area of the tissue in which the temperature is monitored and (ii) the set-point temperature were determined. A reliable finite element model or simulator for a commercially available electrode was used and the tissue surrounding the RFA electrode was divided into three areas for a comprehensive study of the issues (i) and (ii). Porcine liver tissue (30 specimens in total) and a custom-made RFA device with a RF power generator (100 W and 460 ± 30 kHz) and a Covidien cool-tip electrode (17 gauge and 30 mm exposure) were used to validate the findings regarding the area of the tissue for feedback control and the set-point temperature.Results: The size of coagulation zone achieved was maximised when the area of tissue surrounding the middle part of the active tip (i.e. Point 7) was used for feedback control and when the set-point temperature was set to 90 ^ C (this temperature is determined based on the energy gate through a trial-and-error procedure). At both 80 and 90 ^ C, the coagulation zones generated using Area II were significantly larger than that generated using Area I (p = 0.0028 and 0.0003, respectively) and Area III (P = 0.0010 and < 0.0001, respectively). A similar finding regarding the control area and set-point temperature was confirmed by the in-vitro experiment. When compared with Point a (p < 0.0001) and Point c (p < 0.0001), the largest coagulation zone (1066.7 ± 36.1 mm2) was achieved by controlling the temperature of the tissue area surrounding the middle part of the active tip (i.e. Point b) at 90 ^ C.Conclusion: The judicious selection of the control area within the biological tissue for temperature monitoring and the set-point temperature for feedback control is critical in increasing the size of the coagulation zone in the treatment of RFA.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».