Errors during radiotherapy treatment can cause severe, and potentially fatal, patient harm. The final check immediately prior to treatment delivery, whereby two radiographers ensure that the dose about to be delivered corresponds with the prescription, is the last defence against error. The aim of this research was to increase understanding of this final treatment check and factors affecting error detection, in order to improve the safety of radiotherapy treatment delivery. The research adopted a mixed methods approach, combining qualitative and experimental studies to investigate the interaction of factors affecting accuracy during the final treatment checks. The qualitative interviews and task analysis pointed to difficulties maintaining attention and variation in how these checks are conducted. The interface used to conduct the final treatment check was also recognised to have usability issues. The laboratory-based experimental studies results indicated that a structured form of double checking, called challenge-response, is most effective at error detection, when compared to single or unstructured double checking. Furthermore, it was found that alternating the roles of challenger and responder, and the order parameters are checked in, significantly increases accuracy during repeated treatment checks. The original contribution of this research was a detailed investigation of a previously understudied aspect of radiotherapy treatment. The results informed the design of an original, evidence and theoretical based two-person checking protocol for use during the final treatment check. Qualitative evaluation indicates that it would be well received as a standardised method of treatment checking. Furthermore, an alternative interface design has been proposed, specifically for use during the final treatment check. This was comparatively tested against the most frequently used software package within the UK and found to have a significant positive impact upon user’s accuracy. An additional output is a series of practice based recommendations to improve accuracy during repeated treatment checking. This research has concluded that implementation of the practice recommendations, checking protocol and interface design should help maintain radiographers’ attention during repeated final treatment checks, thereby preventing errors passing undetected. Future research into the radiotherapy interface design and implementation of the standardised final treatment check protocol have been identified.

M.Sc. (Chemistry) / Secondary cancer tumour formation, often called metastasis, remains one of the great scientific challenges in public health. Patients with skeletal metastases have a low survival rate, with great discomforts experienced by the sufferers. Pain, decreased mobility, pathologic bone fractures are some of the effects that these patients have to live with. Significant inroads have been made in using radio pharmaceuticals as a pain palliation treatment for bone metastases. They comprise of a bone seeking phosphonate ligand and a radionuclide. The structural variation of the phosphonate affects to a great extend the effectiveness of the radiopharmaceutical with the greatest shortfall being myelosuppression at high doses. In this study an attempt is made at synthesizing novel bisphosphonates, APDDAM and APDDPE. After several synthetic steps from the protected β-alanine tert butyl ester, the free acid precursor was achieved (as shown in the NMR and elemental analysis) in good yields. Unfortunately the final reaction step to form the bisphosphonate ligand was unsuccessful, with the free acid precursor dissociating in the acidic conditions to form salts. A polymer ligand poly-HEDP was synthesized from its free acid form in relatively low yields. The ligand was used in potentiometric studies with the metal ions Ca(II), Mg(II), Cu(II), Zn(II), Sn(II) and Sn(IV) to evaluate its potential as radiopharmaceutical candidate. The ESTA model formation constants obtained were used in the ECCLES blood plasma model to evaluate the competitive stability of the complexes against biological metal ions and ligands. The Sn(IV)-poly-HEDP complex was shown to be unstable, with a 100 % dissociation. On the other hand the Sn(II)-poly-HEDP showed much improved stability with 100 % of the metal ion remaining bound to the ligand.

Improved radiotherapy (RT) outcomes may be facilitated through monitoring of physiological processes implicated in radio-resistance such as proliferation. To this end, we studied 16 patients with non-small cell lung cancer with dynamic 3'-deoxy-3'-fluorothymidine (FLT) PET-CT before and after a week of radical RT. In absence of changes in primary tumour volume manually delineated on CT, RT induced a significant, moderately variable decrease in maximum and mean standard uptake values (SUVmax and SUVmean) of the order of 25%. Metastatic nodes showed a larger relative decrease in uptake approximating 40% associated with volumetric regression and only partially accountable by partial volume effect. Implementation of different segmentation approaches including manual delineation by a second operator and PET-based semi-automatic algorithms [two fixed thresholds, 2/3-cluster Fuzzy C-means (FCM-2, FCM-3) and 2/3-cluster fuzzy locally adaptive Bayesian algorithm (FLAB-2, FLAB-3)] yielded substantially different volumes and SUVs but consistent SUV responses. Reproducibility comparison favoured manual delineation, while thresholding delivered poor volumetric robustness and no apparent SUV reproducibility advantage over SUVmax or SUVpeak. FCM-2/FLAB-2 demonstrated intermediate reproducibility. In contrast to anatomical volumes, metabolic volumes exhibited significant increases with treatment, which for FLAB-2 correlated with changes of intratumoural uptake heterogeneity quantified by the coefficient of variation. Normal tissue analysis revealed an anterior-posterior gradient of lung uptake and an association of baseline marrow SUV with type/timing of neo-adjuvant chemotherapy. RT induced a dramatic (≈-76%), sharply demarcated marrow SUV decline in response to a minimum of 5Gy and a small (≈-20%), consistent decline in normal lung SUV. Kinetic analysis revealed a significant increase in the tumour delivery constant K1 (+32%) and a decrease in Ki/K1, larger (-36%) and more variable than the Ki (-26%) and SUV responses. Furthermore, despite baseline independence, we found a strong negative correlation between Ki/K1 and K1 at the response level. Kinetic analysis of the most uptake-avid tumour cluster extracted with FCM-3 yielded similar results with attenuated changes in delivery and retention. Overall, we found that RT induces early measurable changes in lung tumour FLT uptake. Spatial analysis indicated a variable dissociation of anatomical and metabolic volumes, while temporal analysis showed a variable antagonistic effect on delivery and phosphorylation, indicating that SUV analysis may misrepresent the magnitude and variability of RT anti-proliferative effect.

Background: Pelvic radiotherapy is a well-established treatment for pelvic malignancies, with 30,000 patients per year in the UK receiving radical pelvic radiotherapy either alone or in combination with other oncological treatments. 80% develop acute gastrointestinal (GI) symptoms and 50% develop chronic GI symptoms and in parallel to improvements in survival, increasing numbers of patients are living to develop the long term consequences of treatment. Despite this, less than 20% of patients who develop chronic GI symptoms are ever referred to a gastroenterologist. Aims: 1. To determine the current practice of clinical oncologists and gastroenterologists with respect to management of chronic GI symptoms following pelvic radiotherapy in 2 parallel national surveys. 2. To determine whether specialist gastroenterological management of chronic GI symptoms following pelvic radiotherapy based on a structured algorithmic approach identifies GI diagnoses and improves outcomes. 3. To determine whether a GI care bundle comprising nutritional assessment and intervention and investigation of GI symptoms and subsequent treatment of diagnoses found is feasible and acceptable to patients. Findings: There is no formal robust screening for GI symptoms, low referral rates, patchy services, use of ineffective treatments and inadequate expertise. Oncologists underestimate the problem and under refer. Gastroenterologists are seeing low numbers of patients and lack expertise. Both groups state that a regional multidisciplinary service for patients with GI symptoms following pelvic radiotherapy would be desirable. Patients who develop GI symptoms following pelvic radiotherapy present with multiple symptoms (median 8) and thorough structured evaluation identified multiple potentially treatable diagnoses, with 28 patients (55%) having ≥2 causes for their GI symptoms. Half of diagnoses were unrelated to previous cancer treatment. Common diagnoses included radiation proctopathy, bile acid malabsorption, diverticulosis and colonic polyps. A clinically and statistically significant improvement in GI symptoms was found in parallel to GI intervention using inflammatory bowel disease questionnaire (IBDQ) (p=0.014), Vaizey incontinence questionnaire (VIQ) (p<0.0005) and the Common Terminology Criteria for Adverse Events (CTCAE) pelvic symptom questionnaire rectum-bowel subset (p=0.001). Initial data show that GI and nutritional intervention during pelvic chemoradiotherapy is both feasible and acceptable to patients. Conclusions: There is inadequate care and services for this patient group in the UK. GI intervention using a structured algorithmic approach is of benefit in terms of identifying potentially treatable diagnoses and improving symptoms. GI intervention during pelvic radiotherapy is feasible and acceptable to patients and ongoing work will determine the benefit of this intervention in terms of symptom control in the short and long term and cost benefit. A programme of mechanistic and clinical research is required to improve the understanding of this scenario.

Background: Radiotherapy is used in the treatment of over 50% of cancer patients and bar surgery, is the most effective cancer intervention. However, in the clinic secondary malignancies have been observed following radiotherapy and in vitro increased cell migration and invasion have been seen following radiation. The Src/FAK signalling pathway is known to play an important role in the metastatic phenotype through its involvement in cell adhesion, migration and invasion and we have previously demonstrated that radiotherapy can activate this pathway along with the phosphoinositide 3-kinase (PI3K) pathway, also associated with tumour metastases and an aggressive phenotype. Using pharmacological inhibitors, we have investigated combination approaches to evaluate whether Src and PI3K targeting is beneficial in a radiotherapy context, especially focusing on metastatic phenotype. We wished to relate pathway activation to cellular phenotype and increase understanding of the metastatic cascade, the processes involved and the signalling pathways taking the lead. Method: Using thyroid carcinoma cell lines FTC133 and 8505c the effects of Src inhibition using AZD0530, FAK inhibition using FAKi and PI3K inhibition using GDC-0941 were studied. The effects of radiotherapy alone, and in combination with the above inhibitors, were also studied. In vitro MTT, apoptosis and clonogenic assays were used to assess cell proliferation and cell survival and scratch assays, cell adhesion and cell spreading assays were used to assess the effects of the drugs on metastatic characteristics. In vivo tumour growth, survival and ex vivo clonogenics were used to measure the effects of AZD0530 and GDC-0941. Western blotting, immunofluorescence and immunohistochemistry was used to observe the effects on pathway activation and protein localisation. Results: Src and FAK inhibition reduced metastatic characteristics of thyroid carcinoma cell lines in vitro such as cell spreading and migration. FAK inhibition showed a greater effect on cell survival by MTT, clonogenic and apoptosis. In the thyroid carcinoma cell lines radiotherapy enhanced the metastatic phenotype. This was seen by enhanced activation of the Src and PI3K pathways, increased migration and invasion in vitro and enhanced tumour metastasis in vivo. By combining Src inhibition with radiation a reduction in metastatic characteristics was observed and by combining PI3K inhibition with radiotherapy radiosensitivity could be improved. With the triple combination of Src and PI3K inhibition with radiotherapy a significant reduction in cell survival was demonstrated in vitro compared to radiation alone and either inhibitor combined with radiation, with a corresponding significant reduction in tumour growth being observed in vivo. With the combination of Src and PI3K inhibition significant reductions in metastatic characteristics were also observed both in vitro and in vivo seen by a reduction in cell migration and tumour metastasis. Finally combined inhibition of the Src and PI3K pathway reduced the radiation enhanced activation of several pathways in vivo including Src and PI3K.Conclusions: Together these results suggest that the Src and PI3K pathways play a role in radiation enhanced metastatic characteristics in thyroid carcinoma and through combined inhibition of the pathway the negative effects of radiation, enhanced migration and invasion, can be inhibited and the cells can be made more radiosensitive. Full characterisation of the pathways involved in radiation induced motility and radioresistance will provide further rationale for combination therapies and provide potential for application of these therapies in the clinic.

M.Tech. (Biomedical Technology) / Collagen Type I (Col- I) as well as collagen types III and V, form most of the connective tissues, smooth muscle cells and, endothelial cells in wound healing (Stuart and Leaper, 2008). Col-I is also the main extracellular matrix (ECM) protein (Ricard-Blum and Ruggiero, 2005). Low intensity laser irradiation (LILI) is a non-invasive, photobiomodulatory therapy. Huang et al., (2009a) have shown LILI to be involved in Col-I production both in vitro and in vivo. Enhanced collagen production in human skin fibroblasts is common shortly after irradiation (Illsley et al., 2000). However, its synthesis in wounded fibroblasts has not been well established in an in vitro model. Healing is impaired in chronic diabetic wounds which exhibit reduced proliferation rate and collagen synthesis (Beldon, 2010; Falanga, 2005). Studies have shown that LILI using a wavelength of 632.8 nm was not the only wavelength biostimulated in cultured cells: biological responses were also generated from various wavelengths within the visible to Near Infrared (NIR) spectral region (Hawkins and Abrahamse, 2005; Karu and Kolyakov, 2005). This study aimed to establish if LILI influenced collagen production and related cellular responses at a wavelength of 660 or 830 nm, with a fluence of 5 J/cm2 in an in vitro normal and wounded fibroblasts model. The study also evaluated the expression profiling of genes related to the ECM and adhesion. This study was performed on isolated human skin fibroblasts collected from a consenting adult undergoing abdominoplasty. Cells were routinely cultured according to standard techniques (Houreld and Abrahamse, 2010; Hawkins and Abrahamse, 2007a; Hawkins and Abrahamse, 2006a; Hawkins and Abrahamse, 2005).

Orientador: Francisco Carlos Groppo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T06:46:43Z (GMT). No. of bitstreams: 1 Alencar_PhillipeNogueiraBarbosa_M.pdf: 1861524 bytes, checksum: 99b4aeb86d33c5851061af86242547cb (MD5) Previous issue date: 2013 / Resumo: O presente trabalho teve como proposta avaliar o efeito radioprotetor de uma solução homeopática sobre a função salivar e a morfologia de glândulas parótidas de ratos irradiados. A amostra foi composta por 150 animais que foram divididos, aleatoriamente, em 6 grupos de 25 animais: G1 ( grupo controle) - recebeu solução salina v.o., mas não foi irradiado; G2 (controle Irradiado) - tratamento idêntico ao G1 e recebeu dose única de irradiação de 15 Gy; G3 (álcool) - recebeu solução hidroalcoólica dinamizada em 15 CH v.o.; G4 (álcool irradiado) - tratamento idêntico ao G3 e recebeu irradiação; G5 (homeopatia) - recebeu 0,25 ml (aproximadamente 1ml/kg) da solução hidroalcoólica irradiada com 15 Gy e dinamizada em 15 CH v.o.; G6 (homeopatia irradiado) tratamento idêntico ao G5 e foi submetido à irradiação. Decorridos os tempos de 12 horas, 3, 10, 17 e 24 dias após a administração dos fármacos, todos os animais foram induzidos à salivação. Analisando a função salivar, foram observadas diferenças estatisticamente significantes somente para o período de 17 dias, no qual os animais irradiados e tratados com a formulação homeopática mostraram maior salivação dos que os demais grupos na mesma condição. Na análise morfométrica foi medido o número de ácinos em função do tempo, considerando cada grupo separadamente. A análise dos resultados mostrou que houve diferença estatisticamente significante somente para o grupo de animais que recebeu álcool e foi irradiado. Esses animais apresentaram uma tendência de diminuição do número de ácinos ao longo do tempo. Já os animais que receberam homeopatia ou o controle e foram irradiados, não mostraram diferenças estatisticamente significantes ao longo do tempo, sugerindo que o tratamento homeopático pode ter diminuído o efeito do álcool sobre o número de ácinos. Concluiu-se, por meio da função salivar, que houve um efeito radioprotetor tardio da solução homeopática. Pode-se concluir também, por meio da análise da morfologia da glândula parótida, que houve um efeito radioprotetor da solução homeopática / Abstract: The aim of the present study was to evaluate the radioprotective effect of a homeopathic solution in the salivary function and in the parotid gland morphology in irradiated rats. The sample size was 150 rats randomly divided in 6 groups with 25 animals each. The groups were named based on the medication: G1 (Control) - animals received saline solution, p.o., but they were not irradiated; G2 (Irradiated Control) - received the same treatment on G1 and a single dose of 15 Gy of irradiation; G3 (Alcohol) - received a hydroalcoholic solution dynamized at 15 CH, p.o.; G4 (Irradiated Alcohol) - received the same treatment on G3 and a single dose of irradiation; G5 (Homeopathy) - received 0.25 ml (~1mL/kg) of the hydroalcoholic solution irradiated at 15 Gy and dynamized at 15 CH, p.o.; G6 (irradiated homeopathy) - received the same treatment on G5 and a single dose of irradiation. Each group was subdivided in 5 different groups, based on the time point of the euthanasia: 12 hours, 3, 10, 17, and 24 days. The medication was applied for 7 days before and 7 days after the radiation treatment. The irradiated groups received only one dose of 15Gy and after the determined times salivation were induced. The salivary function analysis showed that only the G6 group that was euthanized on the day 17 had a statistical significant difference when compared to the others irradiated groups showing a higher salivation flow rate. In the morphometric analysis, the number of acini present over the time in the parotid gland was observed. The only group that showed a statistical significant difference was the Alcohol Irradiated. This group showed a tendency of reduction in the number of acini over the time. Data from the irradiated homeopathy and irradiated control group were not statistical significant. This suggests that the homeopathic treatment might have reduced the alcohol effect on the number of acini. The homeopathy had a late radioprotective effect of the homeopathic solution based on the salivary function. In addition, it also had a radioprotective effect of the homeopathic solution based on the morphology analysis of the parotid gland / Mestrado / Radiologia Odontologica / Mestre em Radiologia Odontológica

Orientadores: Andre Deeke Sasse, Carmen Silvia Passos Lima / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-24T04:20:53Z (GMT). No. of bitstreams: 1 Santos_LucasVieirados_M.pdf: 843952 bytes, checksum: bd8daf1913e68951fafe63ae91e9b070 (MD5) Previous issue date: 2013 / Resumo: Introdução: O linfoma não-Hodgkin é o sexto grupo de neoplasias em mortalidade no mundo. Quando em estágio precoce, o linfoma não-Hodgkin pode ser curado com quimioterapia. A radioterapia tem sido utilizada para se reduzir a recorrência local, entretanto o seu impacto nos desfechos de sobrevivência é desconhecido. Vários estudos tentaram responder a esta questão, mas com resultados conflitantes. Frente a resultados controversos derivados de estudos randomizados, uma revisão sistemática da literatura faz-se necessária para determinar se a radioterapia, acrescentada ao tratamento sistêmico, traz ganhos reais para o paciente. Objetivos: Comparar os desfechos do paciente com linfoma não-Hodgkin agressivo e localizado tratado com quimioterapia seguido de radioterapia, com os da quimioterapia isoladamente. Métodos: Revisão sistemática da literatura com meta-análise. Estudos clínicos randomizados no tratamento do linfoma não-Hodgkin foram identificados, através de busca nas bases de dados Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, e LILACS. Referências de artigos encontrados, Resumos de apresentações em congressos e bases de dados de estudos em andamento também foram utilizados para localizar estudos pertinentes. Critérios de inclusão: estudos controlados randomizados que compararam radioterapia adicionada ao tratamento sistêmico com tratamento sistêmico isoladamente em pacientes com linfoma não-Hodgkin agressivo e localizado. Dois revisores extraíram independentemente os dados dos artigos utilizando formulários de extração de 10 dados. Quando possível, para cada desfecho clínico foi feita meta-análise com os dados extraídos, com o fim de calcular o efeito dos tratamentos entre os estudos. Os resultados da meta-análise são expressos como Risco Relativo (RR), e Hazard Ratio (HR), com o correspondente intervalo de confiança (IC) de 95%. Os desfechos clínicos avaliados foram sobrevida global, sobrevida livre de progressão, resposta radiológica e toxicidade. O modelo de efeito fixo foi usado para se calcular as variáveis de interesse. Resultados: De um total de 7020 estudos identificados por meio da estratégia de busca, cinco foram selecionados. Destes, um estudo foi excluído. Quatro estudos, compreendendo 1796 pacientes foram incluídos na meta-análise. A adição de radioterapia trouxe incremento na sobrevivência livre de progressão [HR 0,81; IC95% 0,67-0,98; p=0,03], sem, entretanto trazer impacto na taxa de resposta ou em sobrevivência global. As diferenças em como os dados foram reportados não permitiu que os dados de segurança fossem combinados. Conclusão: Até o presente momento, não há evidência de que a radioterapia traga ganhos em sobrevivência global em pacientes com linfoma não-Hodgkin agressivo e localizado. Investigações adicionais, com a incorporação dos agentes biológicos à quimioterapia, são necessárias / Abstract: Background: Non-Hodgkin lymphoma is the sixth group of neoplasms in mortality in the world. Aggressive and localized non-Hodgkin lymphoma can be cured by chemotherapy. Radiotherapy has been used to reduce local recurrence, however its impact on survival outcomes is unknown. Several studies have attempted to answer this question, but with conflicting results. Thus, a systematic literature review is needed to determine whether radiation therapy added to systemic treatment enhances the efficacy in non-Hodgkin lymphoma treatment. Objectives: To compare outcomes of patients with aggressive and localized non- Hodgkin lymphoma treated with chemotherapy followed by radiotherapy with chemotherapy alone. Methods: This is a systematic review with meta-analysis. Randomized clinical trials were identified the following databases: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and LILACS. Inclusion criteria: randomized controlled trials that compared the addition of radiotherapy to systemic therapy versus systemic therapy alone in patients with aggressive and localized lymphoma. Two reviewers independently extracted data from articles using data extraction forms. When possible, for each clinical outcome was performed meta-analysis of the extracted data in order to calculate the effect of treatments across studies. The results of the meta-analysis are expressed as relative risk (RR) and hazard ratio (HR) with corresponding confidence interval (CI) of 95%. The main outcomes were overall 12 survival, progression-free survival, radiologic response and toxicity. The fixed-effect model was used to estimate the effect size. Results: A total of 7,020 studies identified through the search strategy, five were selected. Of these, one study was excluded. Four studies comprising 1,796 patients were included in the meta-analysis. The addition of radiotherapy increased the progression-free survival [HR 0.81, 95% CI 0.67 to 0.98, p = 0.03]. There were no differences in response rate or overall survival. The differences in how data was reported did not allow us to combine toxicity data Conclusion: To date, there is no evidence that radiotherapy will increase overall survival in patients with aggressive and localized non-Hodgkin lymphoma. Further investigations, with the incorporation of biologic agents to chemotherapy, are needed / Mestrado / Clinica Medica / Mestre em Clinica Medica

Philosophiae Doctor - PhD / Epidemiological studies have highlighted that leukaemia can be considered as the most prominent malignancy after radiation exposure during childhood. The lifetime risk on radiation-induced leukaemia for a given dose is 3 – 5 times higher for children compared to adults. The high risk at a young age is related to the elevated sensitivity of the red bone marrow where haematopoietic stem and progenitor cells (HSPCs) are located. HSPCs self-renewal capacity and long-life span increase their susceptibility to DNA damage accumulation, making them a major target of radiation-induced carcinogenesis. Proton beam therapy (PBT) is increasingly used to treat paediatric brain tumours due to its dose sparing properties compared to conventional X-ray based radiotherapy. However, concerns regarding the carcinogenic potential of secondary neutrons produced during PBT, especially in terms of their effect on HSPCs harboured in the cranial bone marrow of paediatric patients, remain. In this study, the radiobiological differences between 60Co γ-rays and p(66)/Be(40) neutron exposure was investigated to resolve the underlying mechanisms for the high radiosensitivity of HSPCs (CD34+ cells) isolated from umbilical cord blood (UCB). For both radiation qualities, an apparent dose-dependent increase in the frequency of radiation-induced MN was observed in CD34+ cells. Furthermore, increased cytogenetic damage was observed with the CBMN assay after neutron irradiation, which highlights its leukaemogenic potential. In addition, no difference was observed in the nuclear division index of the CD34+ cells post-irradiation between both radiation qualities. The number of DNA DSBs was assessed by microscopic scoring of γ-H2AX foci, 2 and 18 hours after radiation exposure. A significant higher number of DNA DSBs were observed 2 hours after neutron irradiation with 0.5 Gy, but decreased to similar levels for both radiation qualities after 18 hours. Different stages of apoptosis in CD34+ cells were studied at 18 and 42 hours numerous time points post-irradiation by flow cytometry using the Annexin/PI assay. In contrast to the γ-H2AX foci results, a significant difference in late apoptosis was observed at 18 hours and 42 hours between the two radiation qualities. The results point towards a fast error-prone DNA repair in HSPCs after neutron irradiation, which might contribute to genomic instability and leukemogenesis. In the second phase of the PhD project, the impact of age on radiosensitivity was investigated by comparing newborn T-lymphocytes with adult peripheral blood (APB) T-lymphocytes. The major difference between UCB and APB T-lymphocytes, is their immunophenotypic profile. Since it is known that different T-lymphocyte subsets have a difference in radiosensitivity, the fraction of CD4+, CD8+, naïve (CD45RA+) and memory (CD45RO+) T-lymphocytes was determined via flow cytometry in the two groups. The cytokinesis-block micronucleus (CBMN) assay was used to determine the extent to which age influences the frequency of cytogenic damage in response to 60Co γ-rays radiation. For both APB and UCB, an outspoken dose-dependent increase in the frequency of radiation-induced MN was observed at 0.5, 1, 3 and 4 Gy. However, no significant difference was observed at 4 Gy when comparing MN yields of APB and UCB. An increased radiosensitivity of newborn to adult donors of 34%, 42%, 29%, 26% and 16% was observed based on the MN scoring at doses of 0.5, 1, 2, 3 and 4 Gy, respectively. The lowest radiosensitivity was identified at the highest dose, which might explain the non-significant difference at 4 Gy. In addition, there was a clear trend that females were more sensitive to 60Co γ-rays radiation than males in both adults and newborns, even though the difference was not significant. The immunophenotypic study revealed that that both the CD4+ and CD8+ T-lymphocytes of newborns are mainly naïve. This is illustrated by the co-expression of CD45RA+ on 90.70% (range: 80.80% – 98.40%) and 95.90% (range: 89.60% – 98.80%) of CD4+ and CD8+ cells respectively. The composition of adult T-lymphocytes, in contrast, is clearly different with a more equal distribution between CD45RA+ and CD45RO+ subpopulations. This finding demonstrates that there are differences in the radiosensitivity between newborn and adult T-lymphocytes which might be linked to the immunophenotypic change of T-lymphocytes with age.

Philosophiae Doctor - PhD / Epidemiological studies have highlighted that leukaemia can be considered as the most prominent malignancy after radiation exposure during childhood. The lifetime risk on radiation-induced leukaemia for a given dose is 3 – 5 times higher for children compared to adults. The high risk at a young age is related to the elevated sensitivity of the red bone marrow where haematopoietic stem and progenitor cells (HSPCs) are located. HSPCs self-renewal capacity and long-life span increase their susceptibility to DNA damage accumulation, making them a major target of radiation-induced carcinogenesis. Proton beam therapy (PBT) is increasingly used to treat paediatric brain tumours due to its dose sparing properties compared to conventional X-ray based radiotherapy.