COMMISSIONING A VIENNA APPLICATOR FOR INTERSTITIAL GYNECOLOGICAL BRACHYTHERAPY

Cervical cancer is the 4th most prevalent cancer in women worldwide. Brachytherapy alone, or combined with teletherapy is a standard treatment modality for this kind of cancer. Several gynecological applicators, such as ring and intrauterine tube, can be used for treatment delivery, resulting in a pear-shaped dose distribution. Although this distribution is generally used, its radial symmetry in the most distal part of the applicator becomes inadequate when treating a lateralized lesion, due to the fact that increasing the dose in any direction results in greater bladder and rectal irradiation. To overcome this limitation, intracavitary brachytherapy with needle insertion is used. The Vienna Applicator is a modified ring applicator that allows combined intracavitary and interstitial treatment of gynecological tumors. The applicators ring is serves as a template for needle insertion, which are inserted parallel to the intrauterine tube. The present work aims to commission a Vienna applicator for interstitial brachytherapy of gynecological tumors. As most medical devices, to use an applicator, tests must be performed to ensure the accuracy of the patient‘s treatment. These tests are called commissioning tests and have been grouped into the following categories: Visual and integrity, safety, and source positioning tests. Visual and integrity tests include radiography and computed tomography of each component intended to detect signs of mechanical shock, rupture, cracking, deterioration or other signs of impairment; Safety tests include verifying the connection between the applicator and transfer tubes, plus checking for the absence of obstructions in the source passage; The source positioning tests includes verification of source placement with autoradiographs to minimize dosimetric errors, as differences in duel positions imply differences between planned and delivered dose. No signs of mechanical damage were detected in the visual tests or images of each applicator component. In addition, the applicator when assembled is robust enough to withstand vaginal canal pressure and has a good connection to the guide tubes. Furthermore, we conclude that source positioning is accurate and corresponds to the programmed position in the planning as well, so all tests are within the expected tolerances.