Treatment Planning

The Carol G. Simon Cancer Center is outfitted with the most technologically advanced radiation equipment.

Message from the Chairperson

The Radiation Oncology Department has distinguished itself as the foremost provider of advanced cancer care in the tri-state region over the last decade. We are very proud and honored to share with you that all five abstracts submitted for presentation for this upcoming ASTRO have been accepted. General speaking, to put this achievement in perspective, note that only 10% of the abstracts submitted to the ASTRO conference are accepted for presentation.

The abstracts present various superior aspects of our CT-on-rail machine. Even though we are a very small department compared to other academic centers, we probably have one of the highest number of abstract presentations on image guided radiation therapy this year. And 100% acceptance rate is something that all of us should be proud of. We would like to take this opportunity to summarize the team’s work.

Abstract #1, Dosimetric Analysis of TX Plan Degradation-ASTRO

Scott Merrick and the physics team introduced a new concept focused on a very important question. Is IGRT enough to correct the changes we saw in the daily tumor shifts? Scott’s abstract introduced a new concept entitled “isodose degradation”. Our department has been using image guided radiation therapy since year 2000. The premise of image guided radiation therapy is that the tumor or target being treated by radiation may not be stationary and, as such, can take a different position each day. By scanning the patient just prior to the delivery of radiation therapy, if we find that the tumor has changed position. We can then adjust the radiation beam. However, we now find that if the target or tumor had changed position significantly, mere readjustment of the radiation beam pathway may not be sufficient. This is because other critical normal tissue may now be in its pathway. Only our system can allow the radiation oncologists to change the radiation intensity or beam configuration because of the superior images that we acquire in real time—hence real time treatment planning. Without such real time treatment planning, the readjusted radiation beam is not perfect—hence “isodose degradation”.

Abstract #2, Validity of Accuracy of Tumor Targeting Using Bony Landmark Fusion

Jeff Gao and the physics team compared several image guided radiation therapy methods. About 90% of currently used IGRT methods in the US employed either bony localization or fiducial markers. Jeff compared our CT on rails with these two other methods. The team found that because the CT images allow us to see the target and normal tissue in total, it is superior to fiducial markers or bony localization. In fact, we found that tumor or target rotation; change in shape or form of the tumor/target is not easily detected by the fiducial markers, but can be seen readily by our CT images.

Abstract #3 – Subcutaneous Adipose-Tissue Thickness

James Wong and the physics team tackled a large problem in radiation oncology. By large, we mean the size of the patients. How does patient size affect the accuracy of radiation deliveries? We found that size alone is not the most important factor. It is what is under the skin—ie, the thickness of the adipose tissue at the center of the oncoming beam that is most important variable. Of course, we would not be able to see what is underneath the surface without the clear insight provided by the CT scanner. True to form—sometimes you have to go underneath the surface to find the truth.

Abstract # 4 – Prostate Motion Prediction

Chee-Wai Cheng and the physics team use mathematical calculations to predict the degree of target and tumor movements. Our model was confirmed by what we see in the CT images acquired daily. This has important implications for centers that have not been able to implement IGRT for various reasons.

Abstract #5, Plan Degradation in Head and Neck Cancers

Peter Chen (our intern for several months) and the team examined the importance of daily CT images and the dosimetric changes throughout the course of radiation treatment for head and neck cancers. During treatment of head and neck cancers, the patients usually lose weight, and the tumor and lymph node regress quickly. Our CT images allow us to follow these changes throughout the course of radiation, allowing us to modify or adjust the radiation treatment. We showed that without such modifications, it is possible to overdose critical normal tissues such as the spinal cord or larynx (defeating the purpose of larynx preservations).

Lastly, I would like to emphasize that without your dedication, hard work and efforts, it would not have been possible for the team to collect, analyze and present this significant data to the radiation oncology community.

James R. Wong, M.D.
Chairman, Radiation Oncology