Document Details

Document Type : Thesis 
Document Title :
Individualisation of radiotherapy dose fractionation based on the patient’s treatment plan
توزيع جرعات العلاج الإشعاعي للمرضى بشكل انفرادي بناء على التخطيط العلاجي للمريض
 
Subject : Faculty of Science 
Document Language : Arabic 
Abstract : Recent clinical trials demonstrate that hypofractionation can yield excellent tumour control with acceptable normal-tissue complications, especially for highly conformal treatments. However, the optimal fractionation regimen will never be derived from trials as this would require vast numbers of them. Radiobiological modelling can optimize a dose-fractionation schedule for an individual patient based on their treatment plan. The Hoffmann-Nahum (α/β)eff, which accounts for dose heterogeneity and degree of NT ‘seriality’, has been used in the ‘Withers’ iso-effect formula (WIF) to derive the tumour dose that is truly iso-effective i.e. iso-NTCP for the most critical organ at risk (OAR), for different numbers of fractions. TCP vs fraction number yielded the optimal fractionation regimen for each patient. The study was applied to 21 patients with NSCLS lung tumours with prescription doses between 55 and 60 Gy delivered in 30 fractions. (α/β)eff was calculated using the patient’s normal-tissue DVHs for the most critical OAR . This (α/β)eff was used in the WIF to determine the NT-iso-effective total tumour doses from (N=1) to (N = 30). Iso-effectiveness of the different regimens was confirmed by verifying that NTCP was constant and equal to that of the reference regimen. The TCP was computed (using the LQ Poisson ‘‘Marsden’’ model) for each N. The optimal fractionation regimen was chosen as a trade-off between maximizing the TCP and economic and social considerations. This process starts by determining N yielding maximum TCP and then searching for the smallest fraction number that keeps TCP within 2% of its maximum value. The result shows the benefit of hypofractionation for all patients in term of increased TCP than the standard fractionation (at constant NTCP) and in decreased overall treatment cost. The Patients tolerance for hypofractionation is different, being related to (α/β)eff. The patients with high (α/β)eff can be treated with fewer number of fraction , while the patients with low (α/β)eff should be treated with a larger number of fractions. The optimal number of fractions ranged from 3 to 15 fractions. 
Supervisor : Dr. Hussain Albarakaty 
Thesis Type : Master Thesis 
Publishing Year : 1440 AH
2019 AD 
Added Date : Monday, April 1, 2019 

Researchers

Researcher Name (Arabic)Researcher Name (English)Researcher TypeDr GradeEmail
وئام محمد النجيديAlnajidi, Weaam MohammedResearcherMaster 

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