Lei Zhang BS, Presenter: Nothing to Disclose

Christy Inscoe MS, BS, Abstract Co-Author: Nothing to Disclose

Hong Yuan PhD, Abstract Co-Author: Nothing to Disclose

Laurel Burk, Abstract Co-Author: Nothing to Disclose

Yueh Z. Lee MD, PhD, Abstract Co-Author: Research Grant, Carestream Health, Inc

Jianping Lu, Abstract Co-Author: Research Grant, Carestream Health, Inc

Sha X. Chang, Abstract Co-Author: Nothing to Disclose

Otto Zhou PhD, Abstract Co-Author: Board of Directors, XinRay Systems Inc Research Grant, Carestream Health, Inc

Microbeam radiation therapy (MRT) is a promising experimental cancer treatment method that has shown strong preferential tumor ablation and normal tissue sparing in small animal studies at synchrotron facilities. Significant research is needed to understand MRT working mechanism before potential clinical use. Our lab developed a table-top microbeam irradiator with image-guidance using a carbon nanotube (CNT) field emission X-ray source array. This study investigates the possibility of targeted delivering microbeams in various configurations using the CNT-based MRT system and of achieving tumor local control in U87 glioma-bearing mice.

Nineteen young adult athymic nude mice were inoculated with U87MG human glioma tumor cells three to four weeks before irradiation. A novel combined MRI/X-ray radiography guidance was provided prior to MRT for tumor localization and treatment planning. Two animals received 10Gy whole-brain broadbeam radiation, and three were set as sham control. The remaining fourteen animals were divided into three groups. Two groups received two unidirectional microbeams of 72 or 100Gy per microbeam. The other group received two cross-firing arrays of four microbeams with 50Gy/microbeam. All microbeams were 300μm wide and were separated by 900μm, delivered at a dose rate of 1.5Gy/min.         

The image-guidance accuracy was confirmed histologically to be up to 450μm in delivering the microbeams to tumor target. MRI tumor volume follow-up showed that all animals treated by MRT showed a much reduced tumor growth rate compared to the sham group. Unidirectional MRT achieved similar tumor local control to the broadbeam group. The higher the peak entrance dose the more growth suppression was observed. Animals received high-dose crossbeam MRT showed the best tumor control.  

Tumor growth suppression in human glioma-bearing mice has been demonstrated using an image-guided microbeam radiation system. This treatment technique could potentially spare normal tissue and meanwhile achieve similar tumor suppression compared to conventional RT. Higher dose and tumor coverage are desired to achieve better tumor control.

The first compact image-guided microbeam irradiation system has been developed, to facilitate widespread laboratory research on MRT’s therapeutic mechanism and expediate its clinical translation.

Zhang, L, Inscoe, C, Yuan, H, Burk, L, Lee, Y, Lu, J, Chang, S, Zhou, O, Carbon Nanotube based Image-guided Microbeam Irradiation Suppressed Brain Tumor Growth in Mice.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045615.html