The B-Mode Acquisition and Targeting system (BAT), which is generally used in combination with advanced external beam radiation treatments such as intensity-modulated radiation therapy (IMRT), is a sophisticated three-dimensional tracking system that helps to precisely localize tumors that move in between treatments. BAT involves the acquisition of ultrasound images on a daily basis at the time of treatment to identify any change in the location of the target. Afterwards, the newly acquired images are compared to the initial treatment planning images. Tiny adjustments may be made in each of the three dimensions to compensate for any deviation. This ability to pinpoint the specific position of the tumor on a daily basis enables delivery of higher doses of radiation to the tumor while minimizing exposure of adjacent, healthy structures. Highly accurate tumor targeting helps increase tumor control, improving disease-free survival while significantly reducing side effects.
BAT is most commonly employed in the treatment of prostate cancers.The prostate moves within the body due to factors such as the fullness of the bladder and rectum. The change in location differs from day to day and may vary by as much as 1-3.5 cm. In the absence of accurate localization, larger radiation fields are required to compensate for these changes, thereby increasing the exposure of the surrounding structures. With BAT, tracking the tumor in real time allows correction for this movement, resulting in delivery of a higher radiation dose to the prostate and a reduction in treatment-related side effects such as erectile dysfunction and rectal and bladder related complications.