[Head and neck adaptive radiotherapy: A tool for the detection of patients requiring adaptive radiotherapy].
OBJECTIVE
The purpose of this work was to implement a simple dosimetric alert tool in a retrospective study for six patients suffering from head and neck cancer to detect when a patient might require an adaptive radiotherapy.


METHODS
The dosimetric tool generates a 3D cartography of two dosimetric complementary information: a dose variation tolerance map and a dose differential map. The tolerance map is calculated on the initial scanner (CTinit) using the planned dose distribution. It shows for each voxel of each delineated volume the availability for local dose variations during the course of radiotherapy without exceeding the dose threshold. The differential dose map is generated on the tomographic image CBCT (CBCTtreatment). It shows dose variations between the planned and the actual delivered dose distribution for each voxel. By comparing both maps, when a voxel presents a value superior to the corresponding dose variation tolerance, an alert is generated and the anatomical areas concerned are visually indicated to the physician.


RESULTS
The application of the dosimetric tool on six patients with head and neck cancers reveals the ability of the tool to detect cases requiring a new treatment plan. Two patients whose the tumour shrinkage produced an increase of the delivered dose to the spinal cord beyond 45 Gy have been detected.


CONCLUSIONS
The development of the dosimetric tool allows the automatic detection, with no delineation needs, of patients suffering from head and neck cancers requiring an adaptive strategy.
Institut de cancérologie de Lorraine Alexis-Vautrin, avenue de Bourgogne, CS 30519, 54519 Vandœuvre-lès-Nancy, France. Electronic address: s.huger@nancy.unicancer.fr.
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Huger
Institut universitaire du cancer Toulouse-Oncopole, 1, avenue Irène-Joliot-Curie, 31059 Toulouse cedex 9, France.
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Graff
Institut de cancérologie de Lorraine Alexis-Vautrin, avenue de Bourgogne, CS 30519, 54519 Vandœuvre-lès-Nancy, France.
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Marchesi
Institut de cancérologie de Lorraine Alexis-Vautrin, avenue de Bourgogne, CS 30519, 54519 Vandœuvre-lès-Nancy, France; UMR 7365, IMoPA, université de Lorraine, 9, avenue de la Forêt-de-Haye, CS 50184, 54505 Vandœuvre-lès-Nancy, France.
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Vogin
Institut de cancérologie de Lorraine Alexis-Vautrin, avenue de Bourgogne, CS 30519, 54519 Vandœuvre-lès-Nancy, France.
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Guinement
Institut de cancérologie de Lorraine Alexis-Vautrin, avenue de Bourgogne, CS 30519, 54519 Vandœuvre-lès-Nancy, France.
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Serre
Institut de cancérologie de Lorraine Alexis-Vautrin, avenue de Bourgogne, CS 30519, 54519 Vandœuvre-lès-Nancy, France.
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Peiffert
D005260:Female; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010039:Otorhinolaryngologic Neoplasms / Q000532:radiotherapy; D018579:Patient Selection; D011880:Radiotherapy Planning, Computer-Assisted; D012189:Retrospective Studies
Adaptive radiotherapy; CBCT; Dosimetric alert tool; Head and neck; ORL; Outil d’alerte dosimétrique; Radiothérapie adaptative; Tomographie conique