Medical radiation is vital in acquiring a patient diagnosis, but some clinicians are concerned with the perceived risks associated with ionizing radiation. This risk is heightened when incorporating in utero exposures due to the risk to the developing foetus. Although other organ systems have been studied, there is a paucity of data on the effects to the respiratory system from in utero exposures. The aim of this thesis was to understand the long-term effects on the respiratory system from in utero exposures, but as a first step, it was important to determine what levels patients receive whilst admitted to hospital. Two polar populations were chosen based on their predicted exposure levels during hospitalisation; one with high levels, intensive care unit (ICU) patients, and one with low levels, pregnant patients. Most patients cumulatively received < 1mSv with median exposures of 0.99 mSv (ICU patients) and 0.02 mSv (pregnant patients). However, both cohorts had patients that surpassed 10 mSv. To assess the effects from in utero exposures on the respiratory system, two animal models were conducted both exposed during late gestation, one healthy model and one acute lung injury model. In the health animal model, cardiovascular outcomes were also measured, however, ionizing radiation (50, 300, 1000 mGy) did not appear to influence these two organ systems from the outcomes measured. In the acute lung injury model, lipopolysaccharide (3mg/Kg) stimulated an acute lung inflammatory response, however, there was also no overt effect of radiation from the outcomes measured (10, 100, 1000 mGy). In both models, ionizing radiation did cause growth restriction up to 16 weeks of age, but this was only observed from doses above 100 mGy. Overall, the levels of ionizing radiation patients receive is low and from diagnostic exposures during pregnancy, there does not appear to be any strong effects on the developing foetus. / Thesis / Doctor of Philosophy (PhD) / Radiation is necessary in medicine to observe the internal structures of the body, but it can sometimes cause unwanted biological changes within the body. This risk is heightened when considering exposure to developing baby because of the dynamic changing it is naturally going through and possible lifetime left to experience effects. This thesis aimed to understand what levels of radiation patients receive in hospital, observing one population predicted to receive high levels (Intensive care patients) and one predicted to receive low levels (pregnant patients). Overall, the majority of patients in the two cohorts received less than the recommended yearly public limit of 1 millisievert (mSv). The second aim was to observe the effects on the growth, lungs and hearts of the babies in an animal model when they are exposed during pregnancy. Radiation had no overall effect on the lungs or heart but can reduce body weight at moderate (100 milligrays (mGy) and high (1000 mGy) exposures.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/25462 |
| Date | January 2020 |
| Creators | McEvoy, James Hugh |
| Contributors | Wilson, Joanna, Biology |
| Source Sets | McMaster University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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