[Quality assurance program for intensity-modulated radiotherapy (IMRT) treatments of head and neck carcinomas]

A new technique such as intensity-modulated radiotherapy needs a quality assurance program. A French cooperative group joined to define a common program for the use of this technique in the case of head and neck carcinomas. Specific controls are necessary and even mandatory, for example: leaves position, speed of the leaves and the linearity of the dose with the monitor unit number. Measurements in homogeneous phantoms will validate calculated treatment plans. Absolute and relative measurements need ionisation chambers and films. Measurements for each beam, gantry at 0 degrees, are basic measurements. If those are impossible due to the treatment planning software, they can be performed with the treatment angles, films of course positioned perpendicularly to the beam axis. A consensus must be established between members to reduce the frequency and the number of measurements. Nevertheless, it currently seems mandatory to maintain measurements for each beam. Moreover, incidents that happen during this kind of treatment have to be recorded and new verifications will have to be realised then. This program is a unique possibility to match the application of a new technique whatever the type of equipment.