On Target - The Scale of Cancer Treatment
The Scale of Cancer Treatment
Date: December 1, 2009
Meet John Wai-Chiu Wong, Ph.D., director of the Division of Medical Physics
and professor of radiation oncology in the Department of Radiation Oncology and Molecular Radiation Sciences at Johns Hopkins. Dr. Wong manages the physics and the dosimetry services
of the department to ensure the delivery of state-of-the-art methods of radiation treatment
to each patient.
Theodore L. DeWeese, M.D., department chairman, recruited Dr. Wong for Johns Hopkins because of his work in applied medical physics. With colleagues at the William Beaumont Hospital in Michigan, Dr. Wong developed the technology that gives radiation oncologists the ability to create CT images at the same time the patient receives radiation.
This novel radiotherapy device, the patented Elekta Synergy® machine was first produced in 2004 and is now used worldwide. With the invention of Synergy®, Dr. Wong played a leading role in ushering in the era of image-guided radiation therapy (IGRT).
What makes the Synergy® revolutionary is the utilization of a cone-shaped beam of X-rays to create a 3-D view of the target area. The system captures the images in a single, one-minute revolution. Soft tissue tumors can be identified without the need for implanting markers, eliminating the need for needle insertion. Because the imaging component of the Synergy® operates in real time and is integrated with the radiation component, medical specialists can position the beam more accurately on the target area, making adjustments as they proceed, creating tighter margins, and preserving more healthy tissue, with a minimal time lag between the imaging of the cancer and the delivery of the
radiation to destroy it.
Dr. Wong also invented the Active Breathing Coordinator™ (ABC™), a device which assists the patient in holding a volume of breath, at a simple and repeatable threshold, during preliminary imaging examinations and during treatment. By facilitating the patient’s breath hold, images can be taken and radiation delivered at the precise moment of this pause in breathing. More accurate images and less healthy tissue irradiated are just two of the many benefits of the ABC™ for patients.
Like the Synergy® machine, the ABC™ is used worldwide by radiation oncologists. In the spirit of cooperative teamwork at Johns Hopkins, Dr. Wong’s colleague,Richard C. Zellars, M.D., is currently engaged in a study, described in this issue, to prove that the ABC™ prevents heart damage during left breast radiation treatment.
Dr. Wong came here in 2004, where he proceeded to make a scaled-down version of Synergy® that could be used to treat mice. Dr. Wong created the small animal radiation research platform (SARRP) because he realized that, in order to increase the efficacy and usefulness of animal studies, the crucial bridge between theoretical research and clinical trials involving people, better technology needed to be developed for animal work. While the technology for humans was becoming more and more sophisticated, in large part thanks to his own contributions to the field, machines used for animal work had not changed in more than 25 years.
SARRP was built by a Johns Hopkins multidisciplinary team, including members of the
robotics engineering group of the Homewood campus computer science department.
They built the machine and moved it to the Department of Radiation Oncology and
Molecular Radiation Sciences in 2007, where seven different projects are currently under
way. Each member of the department has the opportunity to operate the machine and learn how the system works.
Like Synergy®, the SARRP has cone-shaped beam X-ray capabilities, again allowing for
3-D imaging of the target area, and a flatpanel detector. Unlike Synergy®, robotics are
used to rotate the stationary animal between the X-ray source and the detector. The X-ray source is mounted on a gantry. The sophisticated image-guidance system produces high resolution images.
The SARRP is a powerful tool for the Johns Hopkins cancer research scientists, enabling
them to study focal radiation of the tumor and organ system of the laboratory animal.
Computer-controlled targeting allows the researchers to study mice organs, such as the
lungs, or, a small region of the brain, which harbors stem cells.
Experiments are designed to evaluate the effectiveness of novel treatments and treatment-related toxicity in the small animal model. The Radiation Oncology and Molecular Radiation Sciences team now has the tool to treat cancer in mice that greatly improves
the translation of novel treatment methods from the laboratory to the clinic.
About his work in the Department of Radiation Oncology and Molecular Radiation
Sciences at Johns Hopkins, Dr. Wong asserts: “We can learn so much more about each
individual patient, such that the treatment can be transformed from a traditional treatment
strategy that fits the larger patient appellation to one that is specifically customized for each patient.”