Head and neck immobilization masks: comparative between two different manufacturers
PO-2284
Abstract
Head and neck immobilization masks: comparative between two different manufacturers
Authors: DAVID HERNANDEZ1, Pablo Castro1, María Roch1, Pablo Chamorro1, Sergio Honorato2, Maria Sol Talaya3, Rosario Rubiato3, Aranzazu Valiente3, Sara Carroceda3, Miriam Escobar3
1H.U. La Princesa, Medical Physics, Madrid, Spain; 2H.U. La Princesa, Medical Physics, madrid, Spain; 3H.U. La Princesa, Radiation Oncology, madrid, Spain
Show Affiliations
Hide Affiliations
Purpose or Objective
A good immobilization in radiotherapy treatments allows delivering the dose as accurately as posible each day of treatment.
Currently, there are many comercial solutions for cranial immobilization.
This study aims to analyze the reproducibility of the treatments achieved with two different head and neck immobilization devices.
Material and Methods
Forty patients have been analyzed, 30 of them have been treated with shoulder thermoplastic devices manufactured by A (MA) and 10 patients have been treated with head and neck immobilization manufactured by B (MB). Eighteen patients have been treated in a TrueBeam, with the Varian Perfect Pitch 6 degrees of freedom (6DoF) and 26 patients have received their treatment in a Clinac 2300-iX, with the VARIAN Exact IGRT couch 4 degrees of freedom (4DoF). All of them have been immobilized with shoulder thermoplastic mask.
The offset applied in the longitudinal, lateral, vertical and rotation have been analyzed. Patients treated in the TrueBeam, have also been studied the pitch and roll displacements.
All images have been examined in the Eclipse offline review.
Results
Patients treated with the thermoplastic mask MA presented offsets in the vertical, longitudinal and lateral axis very similar to the patients treated with MB device. Theses offsets are less than 0.1 cm.
Analysing devices by machines, in the Clinac 2300-iX it can be seen how rotational displacements are much higher with the MA device than MB immobilizer (image1)
In the TrueBeam it is observed that the offsets in pitch and rotation axes are also more than doubled with MA immobilizer than MB thermoplastic mask.
The analysis of all patients, independent of the machine, is shown in image2.
It is observed that the displacements in all axes are higher in MA than MB, except in the roll axis.
The registration of the images has also been analysed visually. It has been found that the position of the shoulders is much more reproducible with the MB masks.
Conclusion
Whenever a new radiotherapy immobilization mask is implemented, a study must be carried out to analyze the impact on patients.
The head and neck masks provided by the manufactured B achieved a better reproducibility of the patient`s position, reducing the offset to be made prior to treatment.