Sökning: "dose--volume criteria"

Hittade 5 uppsatser innehållade orden dose--volume criteria.

  1. 1. COMPARISON OF MULTI-CRITERIA OPTIMIZATION IN TWO DIFFERENT TREATMENT PLANNING SYSTEMS

    Master-uppsats,

    Författare :Anna Lindström; [2021-05-10]
    Nyckelord :Medical physics; Multi-criteria optimization; Pareto front; volumetric modulated arc therapy; head and neck cancer; prostate cancer;

    Sammanfattning : Purpose: The purpose with this study was to compare multi-criteria optimization (MCO) for volumetric modulated arc therapy (VMAT) treatment plans in two different treatment planning systems. Theory: When performing treatment planning prior to radiation therapy it is important to prioritize between absorbed dose to target and absorbed dose to organs at risk (OAR). LÄS MER

  3. 2. Machine learning multicriteria optimization in radiation therapy treatment planning

    Master-uppsats, KTH/Matematisk statistik

    Författare :Tianfang Zhang; [2019]
    Nyckelord :Radiation therapy; automated planning; machine learning; multicriteria optimization; dose mimicking; dose--volume criteria; Gaussian mixture model; expectation--maximization; exponential tilting; Strålterapi; automatisk planering; maskininlärning; flermålsoptimering; dosåterskapande; dos--volym-kriterier; gaussisk blandningsmodell; förväntning--maximering; exponentiell lutning;

    Sammanfattning : In radiation therapy treatment planning, recent works have used machine learning based on historically delivered plans to automate the process of producing clinically acceptable plans. Compared to traditional approaches such as repeated weighted-sum optimization or multicriteria optimization (MCO), automated planning methods have, in general, the benefits of low computational times and minimal user interaction, but on the other hand lack the flexibility associated with general-purpose frameworks such as MCO. LÄS MER

  4. 3. Direct optimization of dose-volume histogram metrics in intensity modulated radiation therapy treatment planning

    Kandidat-uppsats, KTH/Skolan för teknikvetenskap (SCI)

    Författare :Tianfang Zhang; [2018]
    Nyckelord :Optimization; intensity-modulated radiation therapy; DVH functions; dose-at-volume; volume-at-dose; value-at-risk; smooth approximation; kernel density estimation; fluence map optimization; Optimering; intensitetsmodulerad strålterapi; DVH-funktioner; dose-at-volume; volumeat- dose; value-at-risk; slätapproximation; ickeparametrisk skattning; fluensoptimering;

    Sammanfattning : In optimization of intensity-modulated radiation therapy treatment plans, dose-volumehistogram (DVH) functions are often used as objective functions to minimize the violationof dose-volume criteria. Neither DVH functions nor dose-volume criteria, however,are ideal for gradient-based optimization as the former are not continuously differentiableand the latter are discontinuous functions of dose, apart from both beingnonconvex. LÄS MER

  5. 4. MRI only radiotherapy using synthetic CT images: Dosimetric accuracy and patient positioning strategies in an MRI only workflow

    Master-uppsats, Lunds universitet/Sjukhusfysikerutbildningen; Lunds universitet/Medicinsk strålningsfysik, Lund

    Författare :Emilia Persson; [2015]
    Nyckelord :Medicine and Health Sciences;

    Sammanfattning : Background and purpose: Magnetic resonance imaging (MRI) only radiotherapy has, due to superior soft tissue contrast of MRI and the possible reduction of systematic uncertainties, grown into a promising technique. The purpose of this work is to investigate parts of an MRI only workflow with synthetic computed tomography (sCT) images generated from MRI. LÄS MER

  7. 5. Evaluation of current quality assurance (QA) system for volumetric modulated arc therapy (VMAT) by studying the impact of introduced errors

    Master-uppsats, Lunds universitet/Sjukhusfysikerutbildningen

    Författare :Marcus Krantz; [2010]
    Nyckelord :Strålterapi; Medicine and Health Sciences;

    Sammanfattning : Introduction: Currently, patient specific dosimetric measurements on diode arrays such as Delta4® (ScandiDos AB) is a part of standard quality assurance (QA) for RapidArc® (RA) at Herlev University hospital. However, a standing issue is the interpretation of the results from dosimetric measurements into consequences in the delivered absorbed dose to the patient. LÄS MER