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Title: DNA damage and biological effectiveness of antiprotons in relation to carbon-ions and protons
Author: Kavanagh, Joy Naomi
ISNI:       0000 0004 2741 9573
Awarding Body: Queen's University Belfast
Current Institution: Queen's University Belfast
Date of Award: 2012
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Antiprotons have been proposed for use in radiotherapy due to their similar energy deposition in water to protons except for an increased dose near the Bragg peak due to antiproton annihilation at rest. There has been skepticism about the use of antiprotons for therapy therefore radiobiological investigations are required to gain a better understanding of the biological effectiveness of antiprotons along the beam path and in the out-of-field regions. Antiproton induced DNA damage in AG01522 fibroblast cells has been investigated using the yH2AX assay. DNA damage and repair have been correlated with cell killing and sub lethal damage. Analogous experiments were conducted with proton and carbon-ion beams that are already used for radiotherapy. DNA damage in cells in the middle of the spread-out Bragg peak persisted longer than that caused by X-rays, plateau anti protons or protons but were repaired quicker than those caused by carbon-ions. Antiproton induced foci appear also larger than those induced by the other radiation modalities investigated. The persistence of foci has been related to LET and is correlated with increased biological effectiveness for cell killing and micronucleus/chromosome aberration formation. The effects outside radiation fields have also been investigated. This study suggests that radiation induced bystander effects in the AG01522 cell line may be LET dependent and appear at late time points after radiation. Investigation into the impact of antiproton annihilation secondary particles outside the primary beam revealed a dose dependent increase in DNA damage at 26 h after exposure in cells that also shared media with cells in the beam at the time of irradiation. This was only significant however for a single dose point. Cells that did not share media with the cells in the beam during the irradiation had low levels of DNA damage that was only significant for 5.56 and 6 Gy doses.
Supervisor: Not available Sponsor: Engineering and Physical Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available