Permanent skin tattoos have been part of standard care for breast cancer patients undergoing radiation therapy. We recently commissioned a commercial 3D optical surface imaging system to be potentially used for surface-guided breast radiation therapy.
Due to respiratory motion, lung tumor can move up to several centimeters. If respiratory motion is
not carefully considered during the radiation treatment planning, the highly conformal dose
distribution with steep gradients could miss the target. To address this issue, the common strategy is
to add a population-derived safety margin to the gross tumor volume (GTV). However, during a free
breathing CT simulation, the images could be acquired at any phase of a breathing cycle. With such a
generalized uniform margin, the planning target volume (PTV) may either include more normal lung
tissue than required or miss the GTV at certain phases of a breathing cycle. Recently, respiration
correlated CT (4DCT) has been developed and implemented. With 4DCT, it is now possible to trace
the tumor 3D trajectories during a breathing cycle and to define the tumor volume as the union of
these 3D trajectories. The tumor volume defined in this way is called the internal target volume
(ITV). In this study, we introduced a novel parameter, the phase impact factor (PIF), to determine the
optimal CT phase for intensity modulated radiation therapy (IMRT) treatment planning for lung
cancer. A minimum PIF yields a minimum probability for the GTV to move out of the ITV during
the course of an IMRT treatment, providing a minimum probability of a geometric miss. Once the
CT images with the optimal phase were determined, an IMRT plan with three to five co-planner
beams was computed and optimized using the inverse treatment planning technique.
Prostate cancer is the most common tumor site treated with intensity modulated radiation therapy
(IMRT). However, due to patient and organ motions, treatment-induced physiological changes, and
different daily filling in the bladder and rectum, the position of the prostate in relation to the fixed
pelvic bone can change significantly. Without a reliable guiding technique, this could result in
underdosing the target and overdosing the critical organs. Therefore, image-guided localization of
the prostate must be performed prior to each treatment, which led to the development of a new
radiation treatment modality, the image-guided radiation therapy (IGRT). One form of IGRT is to
implant three gold seed markers into the prostate gland to serve as a fixed reference system. Daily
patient setup verification is performed by using the gold seed markers-based image registration
rather than the commonly used bony landmarks-based approach. In this paper, we present an
efficient and automated method for registering digitally reconstructed radiographs (DRR) and kV X-ray
images of the prostate with high accuracy using a hybrid method. Our technique relies on both
internal fiducial markers (i.e. gold seed markers) implanted into the prostate and a robust, hybrid 2D
registration method using a salient-region based image registration technique. The registration
procedure consists of several novel steps. Validation experiments were performed to register DRR
and kV X-ray images in anterior-posterior (AP) or lateral views and the results were reviewed by
experienced radiation oncology physicists.
Conference Committee Involvement (1)
IEEE 2006 International Conference of Engineering in Medicine and Biology Society
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