2D linear array device as a quality assurance tool in brachytherapy applications

Background: External beam radiotherapy and brachytherapy plays a vital role in the management of cancer cervix.  High dose rate brachytherapy is being presently used worldwide for the brachytherapy applications. At present, 2-Dimensional linear array detectors   are the most common QA tool used for pretreatment patient specific quality assurance in external beam radiotherapy alone and till date no dedicated brachytherapy tool is available. An attempt has been made to explore the feasibility of using 2 dimensional linear array, Imatrixx as a QA tool for brachytherapy. Materials and Methods: Reference treatment plans are generated by Plato treatment planning system using the images of Imatrix acquired with Siemens CT simulator. The efficacy of Imatrixx as a QA tool for intracavitary treatment plan verification, dwell position and dwell time accuracy verification are studied. Results: The length and the widths  along with the area of the  reference isodose curves of the intracavitary treatment plans generated by  Plato Planning system  and measured with Imatrixx is compared. The difference in area of the reference isodose curve is found to vary from -0.59 cm2 to 4.59 cm2. The estimated user correction factor for Iridium-192 energy, 0.38 MeV is 1.090 with a standard deviation of ±0.0211.  Machine related QA such as dwell position and dwell time were measured with Imatrixx with an accuracy of 0.5 mm and 0.02 s respectively. Conclusion: Results shows that the 2-Dimensional linear array, Imatrixx can be used with accepted accuracy for both machine and patient specific quality assurance in brachytherapy treatments.