Medical Physicist, Swedish Cancer Institute
Previous implementations of this technique have used ultrasound imaging with a breast probe to localize the post-lumpectomy target on treatment day. We have modified this protocol to use linac based CBCT to localize the target based on post-surgical clips. Patient positioning is aided through the use of a surface mapping system (Catalyst-HDTM) to help position the arms and head of the patient. Finally, the MLCs of the linac are used to project the treatment planning outline of the target volume on the patient’s surface. The target volume is then accurately drawn on the patient’s skin before transferring the patient to the OR for interstitial implant. Compared to the original method of drawing the target on the skin based on ultrasound imaging, this method positions the patient within a millimeter and uses localization techniques that radiation therapy staff are more familiar with.
This talk will describe both the permanent LDR breast brachytherapy method and the localization techniques using CBCT and Catalyst surface mapping.