Saudi Cultural Missions Theses & Dissertations
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Item Restricted Lung Density and Algorithm Choice in Radiotherapy: Implications for Accurate Lung Cancer Treatment Planning(Saudi Digital Library, 2025-06-01) Alhamdan, Hesham; Brad, ObornAccurate dose calculation is crucial for effective lung cancer radiotherapy, particularly in heterogeneous media where density variations can result in significant deviations between planning algorithms. This study systematically compared the fast collapsed cone convolution (CCC) algorithm against a high-accuracy Monte Carlo (MC) dose engine within the RayStation treatment planning system. Two main investigations were conducted: (1) a controlled phantom study consisting of a water block with lung-equivalent inserts of varying densities (1.0, 0.4, 0.3, 0.2 g/cm3 ) irradiated by 6 MV and 10 MV photon beams across four field sizes (2×2, 3×3, 5×5, 10×10 cm2), and (2) a clinical patient study involving three anonymised VMAT plans for small, medium, and large lung tumours. In the phantom study, PDD, lateral profiles, and sagittal dose slices revealed that CCC overestimates superficial (skin) dose and in-lung dose relative to MC. These effects intensified with smaller field sizes, lower lung densities, and higher beam energy due to lateral electronic disequilibrium. Quantitative ROI analyses showed that, although out-of-field differences were notable, they were statistically indistinguishable when accounting for MC noise. CCC’s deviations in lung-insert dose became significant for small fields (≤ 3×3 cm2) in low-density media. In the patient study, CCC overestimated entrance skin dose yet underestimated tumour and organs at risk coverage by up to 5.9 % of the clinical goal. These findings align with prior literature on lateral scatter limitations in CCC. Clinically, our results affirm that CCC plans should be verified by MC, especially for small-field, low-density lung targets, to ensure accurate tumour coverage and normal tissue sparing.13 0Item Restricted PREDICTORS OF HEALTH-RELATED QUALITY OF LIFE AFTER LUNG CANCER SURGERY(University of Birmingham, 2024) Algaeed, Saffana Khalid; Naidu, Babu; Thickett, DavidGlobally, lung cancer is the leading cause of death. Surgical removal of a primary non-small cell lung cancer (NSCLC) tumour offers a significant chance of cure for those suffering. Additionally, it is anticipated that the introduction of screening programs for lung cancer will result in an increase in survival rates. Therefore, health-related quality of life (HRQOL) following surgery has become an important consideration for these patients. However, a considerable number of lung cancer patients who have undergone surgery have not experienced improvement in their breathing afterwards, a condition that can persist for several months following surgery. Computed Tomography (CT) scans of lung cancer patients often demonstrate concurrent emphysema with low attenuation areas (LAAs), the significance of which is unclear. Moreover, sarcopenia is observed in about half of lung cancer patients and is linked to impaired health outcomes and lower survival rates. Identifying the predictors of postoperative HRQOL decline is vital; however, little information is available regarding the relationship between baseline HRQOL, quantitative computed tomography (QCT) of emphysema, or CT-based body composition with postoperative dyspnoea and global health. This thesis aims to examine the predictors of HRQOL of dyspnoea and global health six months following lung cancer surgery. This is a prospective observational study. The European Organisation for Research and Treatment of Cancer (EORTC QLQ-C30) questionnaire and lung cancer module LC13 were introduced at baseline pre-surgery, eight weeks, and six months after lung surgery. Using the CT scans, lung density measurements using %LAA at thresholds of -950 Hounsfield Units (HU) and -910 HU for the assessment of emphysema were quantified and the cross-sectional area of thoracic and abdominal muscles, specifically pectoralis (PM), erector spinae (ESM), psoas (PSM), and skeletal muscles (SM), were analysed using an open-access software. Univariate and multivariate linear, ordinal and multinational regression analyses were performed to find out the predictive value of preoperative HRQOL and CT scan density measurements. Comparative analyses, as well as intra-class correlation coefficients and Bland Altman plots, have also been employed. A total of 1064 patients were recruited over 10 years, and 906 consented patients were included in the study. A significant increase in dyspnoea scores was observed beyond the minimal clinical difference, with values at baseline, eight weeks, and six months were 20.5 ± 22.6, 39.6 ± 24.5, and 33.2 ± 24.7, respectively. In an eight-week period, global health scores dropped from 73.2 ± 20.5 to 63.3 ± 20.5, with only a minimal improvement observed at six months (66.6 ± 22.2). In the multivariate regression analyses, we have demonstrated that baseline dyspnoea is a strong predictor for patients’ postoperative HRQOL after lung cancer surgery (OR = 3.07 – 12.3, p = 0.00). Additionally, baseline global health significantly predicts postoperative HRQOL (coefficient = 0.45 – 0.5, p = 0.00). The data demonstrate that %LAA-950 is a significant predictor of postoperative dyspnoea and global health (OR = 1.2-1.3, p = 0.00), while %LAA-910 is not consistently a strong predictor after adjusting for clinical and perioperative factors. AI-based and semi-automated software showed strong consistency in measuring %LAA-950 and whole lung volume, 15th percentile, and mean lung density. However, there was a lower degree of agreement between the two programs in lobar measurements. Finally, no statistically significant differences were observed in the changes in HRQOL following lung surgery among the small number of patients with sarcopenia9 0