Cavitation Threshold Determination for Heavy-Ion Particle Therapy
Mentor 1
Sarah Patch
Location
Union 250
Start Date
5-4-2019 1:00 PM
Description
Particle therapy is the most technologically sophisticated method for cancer treatment in practice today. X-rays are more commonly used to irradiate malignant tissue, however photons deliver more energy closer to the source and gradually lose energy as they transverse through the body. Protons and heavy-ions offer distinct advantages over this, as they can deposit most of their energy into malignant tissue just before coming to rest, leaving healthy tissue in front of the target less irradiated than with X-rays and tissue behind the target unaffected. Microbubbles are gas filled bubbles surrounded by a protein or lipid shell on the order of 1 to 10 microns in diameter, typically used as imaging contrast agents. In recent years the possibility of using them to aid treatment of radiation-resistant cancer cells has been under investigation. The Argonne Tandem Linear Accelerator System (ATLAS) at Argonne National Laboratory was used to investigate response of air-filled and perflutren-filled microbubbles to a pulsed beam of 12C5+ carbon ions. Different concentrations of microbubbles in deionized water were passed through 508 micron ID Vention tubing using gravity driven flow. The tubing was immersed in a bath of deionized water and observed with both a USB camera and B-mode ultrasound imaging by a 128-channel linear array (ATL L7-4). The lowest possible voltage of 1.6 V was used to transmit 5.5 MHz pulse echoes. Multiple time structures and currents were used to catalog effects of various ion beam profiles. In many but not all cases, the beam induced visible cavitation in both the tubing and the surrounding water, an effect that would be disastrous if it occurred within healthy tissue. Next–generation particle accelerators are being designed to deliver intense pulses and must avoid cavitation in healthy tissue. Further research is required to define cavitation thresholds.
Cavitation Threshold Determination for Heavy-Ion Particle Therapy
Union 250
Particle therapy is the most technologically sophisticated method for cancer treatment in practice today. X-rays are more commonly used to irradiate malignant tissue, however photons deliver more energy closer to the source and gradually lose energy as they transverse through the body. Protons and heavy-ions offer distinct advantages over this, as they can deposit most of their energy into malignant tissue just before coming to rest, leaving healthy tissue in front of the target less irradiated than with X-rays and tissue behind the target unaffected. Microbubbles are gas filled bubbles surrounded by a protein or lipid shell on the order of 1 to 10 microns in diameter, typically used as imaging contrast agents. In recent years the possibility of using them to aid treatment of radiation-resistant cancer cells has been under investigation. The Argonne Tandem Linear Accelerator System (ATLAS) at Argonne National Laboratory was used to investigate response of air-filled and perflutren-filled microbubbles to a pulsed beam of 12C5+ carbon ions. Different concentrations of microbubbles in deionized water were passed through 508 micron ID Vention tubing using gravity driven flow. The tubing was immersed in a bath of deionized water and observed with both a USB camera and B-mode ultrasound imaging by a 128-channel linear array (ATL L7-4). The lowest possible voltage of 1.6 V was used to transmit 5.5 MHz pulse echoes. Multiple time structures and currents were used to catalog effects of various ion beam profiles. In many but not all cases, the beam induced visible cavitation in both the tubing and the surrounding water, an effect that would be disastrous if it occurred within healthy tissue. Next–generation particle accelerators are being designed to deliver intense pulses and must avoid cavitation in healthy tissue. Further research is required to define cavitation thresholds.
