A Preclinical Study of Radiation-Induced Lung to xicity When Irradiating In A Strong Magnetic Field

<p>The purpose of this work was to evaluate the effect of a strong, transverse magnetic field on the severity of radiation-induced lung damage in mice. This data can be used to support the safe clinical implementation of MRI-guided radiation therapy systems.</p> <p>Monte Carlo simulations and EBT3 film measurements were used to determine an irradiator and magnetic field strength that would produce magnetic-field-induced dose perturbations in mice that were comparable to those seen in human simulations. We developed an irradiation scheme for C57L/J mice, which included irradiating mice to the whole thorax in a 3D-printed holder with parallel-opposed Co-60 beams. We developed non-invasive assays for evaluating the extent of radiation-induced lung injury, including a respiratory rate measurement technique and techniques for measuring lung damage on cone-beam CTs. We showed that these assays were correlated to survival, the ultimate predictor of radiation-induced lung injury.</p> <p>The mice were irradiated to 9.0, 10.0, 10.5, 11.0, 12.0, or 13.0 Gy between the poles of an electromagnet in a 1.5 T field (n=60) or 0 T field (n=60). Twenty control mice did not receive radiation. Survival, respiratory rate measurements, and free-breathing cone-beam CT measurements (lung density and healthy lung volume) were used to assess the severity of radiation-induced pneumonitis.</p> <p>Cox regression showed that dose was a much higher predictor of survival than magnetic field strength. The presence of a transverse 1.5 T field during irradiation had little to no effect on survival for each of the dose groups. The 1.5 T field did, however, have an effect on the severity of radiation-induced lung injury, as measured by respiratory rate, lung density, and lung volume.</p> <p>The results of these studies suggest that it is possible to reduce magnetic-field-induced dose perturbations by using parallel-opposed fields, and in this case the impact of a strong, transverse magnetic field on survival would be expected to be insignificant. However, our results also suggest that there could be some impact on the severity of radiation-induced lung damage, though that impact is likely small.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation (PhD)

Year dc:date.available

2017

Authors dc:creator

• Rubinstein, Ashley E
• <p>orcid.org/0000-0003-0221-4603</p>

Contributors dc:contributor

• Laurence E. Court
• David S. Followill
• Adam D. Melancon

• MRIgRT
• dose perturbations
• mice
• radiation-induced pneumonitis
• MCNP6
• magnetic-field-induced dose effects
• MRI-guided radiation therapy
• Biophysics
• Medical Biophysics
• Medicine and Health Sciences
• Other Physics

Repository record dc:identifier

https://digitalcommons.library.tmc.edu/utgsbs_dissertations/786

OAI identifier oai:identifier

oai:digitalcommons.library.tmc.edu:utgsbs_dissertations-1828