PP06  Presentation Time: 10:45 AM: “Honeycomb” Direction Modulated Brachytherapy Tandem Applicator

Purpose The intracavitary brachytherapy is an integral part of the treatment of cervical cancer. However, the coverage of non-uniform targets is very challenging for this modality when dealing with the lateral extension of tumor and requires development of interstitial-intercavitary state-of-the-art applicators. In this study we aim to introduce a novel tandem applicator design in alignment with the direction modulated brachytherapy (DMBT) concept, called “honeycomb”, to address this important issue. Materials and Methods The novel “honeycomb” tandem applicator was designed using GEANT4 Monte Carlo simulations to consist of a base with 19 channels, in a honeycomb arrangement, and a sheath of plastic to cover the base. The design also incorporated 18 iridium wires that can actively enter the channels to provide intensity/directional modulation. Three different MR compatible materials were studied for the base part, including the PEEK plastic, tungsten alloy, and iridium. A dosimetry study was then performed with different configurations of the HDR source and up to 18 iridium wires inside the bases. The previous innovation, namely DMBT six-groove tandem, was also reproduced and compared to the honeycomb design. Results The honeycomb design could produce a variety of directional dose distributions with different degree of extended lateral coverage. However, the MR compatible tungsten alloy found to be the optimal base material, in terms of radiation leakage and desired intensity/direction modulations while improving the lateral coverage. In addition, the honeycomb design showed superiority over the DMBT six-groove tandem in terms of back spillage and beam directionality, with more flexibility for dosimetric coverage at different directions around the tandem. Conclusion The results indicated that the honeycomb DMBT tandem design, as a noninvasive intracavitary approach, could be a promising solution for covering targets with lateral asymmetry/extension. The future study may include manufacturing of a prototype, the development of a dedicated treatment planning algorithm, and the required software/hardware for its treatment delivery. The intracavitary brachytherapy is an integral part of the treatment of cervical cancer. However, the coverage of non-uniform targets is very challenging for this modality when dealing with the lateral extension of tumor and requires development of interstitial-intercavitary state-of-the-art applicators. In this study we aim to introduce a novel tandem applicator design in alignment with the direction modulated brachytherapy (DMBT) concept, called “honeycomb”, to address this important issue. The novel “honeycomb” tandem applicator was designed using GEANT4 Monte Carlo simulations to consist of a base with 19 channels, in a honeycomb arrangement, and a sheath of plastic to cover the base. The design also incorporated 18 iridium wires that can actively enter the channels to provide intensity/directional modulation. Three different MR compatible materials were studied for the base part, including the PEEK plastic, tungsten alloy, and iridium. A dosimetry study was then performed with different configurations of the HDR source and up to 18 iridium wires inside the bases. The previous innovation, namely DMBT six-groove tandem, was also reproduced and compared to the honeycomb design. The honeycomb design could produce a variety of directional dose distributions with different degree of extended lateral coverage. However, the MR compatible tungsten alloy found to be the optimal base material, in terms of radiation leakage and desired intensity/direction modulations while improving the lateral coverage. In addition, the honeycomb design showed superiority over the DMBT six-groove tandem in terms of back spillage and beam directionality, with more flexibility for dosimetric coverage at different directions around the tandem. The results indicated that the honeycomb DMBT tandem design, as a noninvasive intracavitary approach, could be a promising solution for covering targets with lateral asymmetry/extension. The future study may include manufacturing of a prototype, the development of a dedicated treatment planning algorithm, and the required software/hardware for its treatment delivery.