Medical physicists at Thomas Jefferson University and Jefferson's Kimmel Cancer Center have invented a new type of tracking technique to use with radiotherapy so that only diseased tissue is destroyed.
With standard radiotherapy, a large amount of tissue is targeted and sometimes as much as 50% of it is actually healthy. This is because respiratory and cardiac motions displace tumors and make it difficult for doctors to pinpoint exactly where the tumors are. Whether or not they are cancerous, the radiotherapy is forced to target all surrounding tissues. This means that critical organs adjacent to the tumors are irradiated, causing side effects for the patient – sometimes long-term and serious ones.
Now Jefferson researchers have developed a new 4D robotic technique that better predicts and continuously tracks tumors during radiotherapy, preventing unnecessary radiation being administered in areas it is not needed.
"The advantage of this novel approach in radiation therapy is that the system is able to predict and track tumor motion in three-dimensional space," said Dr. Buzurovic, Director of Medical Physics at Thomas Jefferson University. “The technique can compensate both tumor motion and residual errors during patient treatment."
"The proposed robotic system needs 2 seconds to start tracking with the high precision level. The tracking error was less than 0.5 mm for regular breathing patterns and less than 1 mm for highly irregular respiration, prediction algorithms were developed to predict tumor motion and to compensate errors due to delay in the system response," Buzurovic said.
Study co-author, Dr.Yu, thinks that the new technique will lead to reduced doses of radiation to healthy tissue, reducing the possibility of side effects and the severity of those effects.
Due to the fact that less radiation will be used overall, doctors hypothesize that they could then use more concentrated doses in the cancerous areas which may increase the likelihood of success.
Source: Thomas Jefferson University Press Release, 1st February 2011.