UC San Diego

To achieve most effective cervical cancer breachytherapy treatment quality with image guided brachytherapy (IGBT), we propose a directional intensity modulate-available applicator. The direction modulate brachytherapy (DMBT) cervical cancer tandem applicator was designed to create non-isotropic dose distribution using tungsten alloy shielding in a tandem for an isotropic 192-Ir HDR radiation source. Conventional tandem has 6 mm in outer diameter with 1 channel, however, the DMBT tandem has 6 channels, which is 1.3 mm in diameter, on a surface of the tungsten alloy shield. Prototypes of the DMBT tandem was manufactured to prove of compatibilities with conventional clinical treatment systems such as MR image test, 192-Ir afterloader source delivering test, and so on. The Monte Calro code was used to calculate the non-isotropic 192-Ir dose distributions and in-house developed brachytherapy planning platform were used for plan re-optimizaiton. To evaluate a potential of the DMBT tandem, 3 different clinical treated patients group were re-optimized with DMBT tandem. The conventional tandem was replaced to the DMBT tandem for comparing differences while the ovoid or ring was kept in the same position. For comparing plan quality, HRCTV coverage was matched to each the clinical treated plans. The D2cc to OARs such as bladder, rectum, and sigmoid was recorded and compared. The first group was 75 clinical cases, which treated with the conventional tandem and ovoids (T&O) applicator. In the second group, a patient case with 5 brachytherapy fractions course was evaluated. From the 3rd to 5th fraction, supplementary free loaded needles were used. To evaluate the DMBT tandem potential of covering irregular HRCTV growth patters, the clinical plans were compared with DMBT and ovoid (without supplement needles) plans. The last group was clinical treated patient cases treated with T&R with combined intracavitary- interstitial applicator with PDR brachytherapy afterloader. The free loaded needles and the attached to ring applicator needles were modified to investigate the DMBT tandem covering availability of an irregular growth pattern of the HRCTV