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MeSH: radioterapie s modulovanou intenzitou-normy

8 záznamů v Články Filtry

Článek

DETERMINATION OF TOLERANCE LEVELS IN RADIOTHERAPY DOSIMETRY BASED ON STATISTICAL INTERFERENCE

Koniarová, Irena
Autor Koniarová, Irena National Radiation Protection Institute, Bartoškova 28, 14000 Prague, Czech Republic
Kotík, Lukáš
Autor Kotík, Lukáš National Radiation Protection Institute, Bartoškova 28, 14000 Prague, Czech Republic

Radiation protection dosimetry. 2019 ; 186 (2-3) : 367-372. [pub] 2019Dec31

Radiat Prot Dosimetry
ISSN 1742-3406
Medvik
Zdroj

The most important dosimetry quantity that is determined at radiotherapy centers is the absorbed dose to water for external beams. Fixed tolerances for absorbed doses measured under reference conditions with an ionization chamber for high-energy photon and electron beams are usually 2 and 3%, respectively, regardless of uncertainties of the input variables and other conditions during evaluation. In reality, this agreement should be evaluated considering the uncertainties of the input variables because they affect the size of the random deviations of the measurements from their true values. The aim of this work was to develop a new approach to evaluate the agreement between measured and reported values based on statistical interference rather than to use fixed tolerance levels. The proposed method considers different scenarios that can occur during the evaluation of agreement. Because the method is described in general, it can be used in all similar situations when partial uncertainties can be established.

MeSH
celková dávka radioterapie MeSH
kalibrace MeSH
lidé MeSH
nádory radioterapie MeSH
nejistota MeSH
plánování radioterapie pomocí počítače metody normy MeSH
radioterapie s modulovanou intenzitou metody normy MeSH
statistické modely * MeSH
vysokoenergetická radioterapie normy MeSH
Check Tag
lidé MeSH
Publikační typ
časopisecké články MeSH

Článek

Testing the methodology for a dosimetric end-to-end audit of IMRT/VMAT: results of IAEA multicentre and national studies

Acta oncologica. 2019 ; 58 (12) : 1731-1739. [pub] 20190819

Acta Oncol
ISSN 1651-226X
Medvik
Zdroj

Introduction: Within an International Atomic Energy Agency (IAEA) co-ordinated research project (CRP), a remote end-to-end dosimetric quality audit for intensity modulated radiation therapy (IMRT)/ volumetric arc therapy (VMAT) was developed to verify the radiotherapy chain including imaging, treatment planning and dose delivery. The methodology as well as the results obtained in a multicentre pilot study and national trial runs conducted in close cooperation with dosimetry audit networks (DANs) of IAEA Member States are presented.Material and methods: A solid polystyrene phantom containing a dosimetry insert with an irregular solid water planning target volume (PTV) and organ at risk (OAR) was designed for this audit. The insert can be preloaded with radiochromic film and four thermoluminescent dosimeters (TLDs). For the audit, radiotherapy centres were asked to scan the phantom, contour the structures, create an IMRT/VMAT treatment plan and irradiate the phantom. The dose prescription was to deliver 4 Gy to the PTV in two fractions and to limit the OAR dose to a maximum of 2.8 Gy. The TLD measured doses and film measured dose distributions were compared with the TPS calculations.Results: Sixteen hospitals from 13 countries and 64 hospitals from 6 countries participated in the multicenter pilot study and in the national runs, respectively. The TLD results for the PTV were all within ±5% acceptance limit for the multicentre pilot study, whereas for national runs, 17 participants failed to meet this criterion. All measured doses in the OAR were below the treatment planning constraint. The film analysis identified seven plans in national runs below the 90% passing rate gamma criteria.Conclusion: The results proved that the methodology of the IMRT/VMAT dosimetric end-to-end audit was feasible for its intended purpose, i.e., the phantom design and materials were suitable; the phantom was easy to use and it was robust enough for shipment. Most importantly the audit methodology was capable of identifying suboptimal IMRT/VMAT delivery.

MeSH
celková dávka radioterapie MeSH
fantomy radiodiagnostické * MeSH
jaderná energie MeSH
kritické orgány * MeSH
lidé MeSH
mezinárodní agentury MeSH
pilotní projekty MeSH
plánování radioterapie pomocí počítače metody MeSH
počítačová rentgenová tomografie MeSH
radiometrie metody normy MeSH
radioterapie s modulovanou intenzitou metody normy MeSH
revize kvality lékařské péče metody normy MeSH
studie proveditelnosti MeSH
zajištění kvality zdravotní péče MeSH
Check Tag
lidé MeSH
Publikační typ
časopisecké články MeSH
multicentrická studie MeSH

Článek

Mezioborová spolupráce při léčbě karcinomu močového měchýře

Acta medicinae. 2018 ; 6 (5-6) : 27-33.

ISSN 1805-398X
Medvik
Zdroj

Článek

Highly Efficient Training, Refinement, and Validation of a Knowledge-based Planning Quality-Control System for Radiation Therapy Clinical Trials

International journal of radiation oncology, biology, physics. 2017 ; 97 (1) : 164-172. [pub] 20161013

Int J Radiat Oncol Biol Phys
ISSN 1879-355X
Medvik
Zdroj

PURPOSE: To demonstrate an efficient method for training and validation of a knowledge-based planning (KBP) system as a radiation therapy clinical trial plan quality-control system. METHODS AND MATERIALS: We analyzed 86 patients with stage IB through IVA cervical cancer treated with intensity modulated radiation therapy at 2 institutions according to the standards of the INTERTECC (International Evaluation of Radiotherapy Technology Effectiveness in Cervical Cancer, National Clinical Trials Network identifier: 01554397) protocol. The protocol used a planning target volume and 2 primary organs at risk: pelvic bone marrow (PBM) and bowel. Secondary organs at risk were rectum and bladder. Initial unfiltered dose-volume histogram (DVH) estimation models were trained using all 86 plans. Refined training sets were created by removing sub-optimal plans from the unfiltered sample, and DVH estimation models… and DVH estimation models were constructed by identifying 30 of 86 plans emphasizing PBM sparing (comparing protocol-specified dosimetric cutpoints V10 (percentage volume of PBM receiving at least 10 Gy dose) and V20 (percentage volume of PBM receiving at least 20 Gy dose) with unfiltered predictions) and another 30 of 86 plans emphasizing bowel sparing (comparing V40 (absolute volume of bowel receiving at least 40 Gy dose) and V45 (absolute volume of bowel receiving at least 45 Gy dose), 9 in common with the PBM set). To obtain deliverable KBP plans, refined models must inform patient-specific optimization objectives and/or priorities (an auto-planning "routine"). Four candidate routines emphasizing different tradeoffs were composed, and a script was developed to automatically re-plan multiple patients with each routine. After selection of the routine that best met protocol objectives in the 51-patient training sample (KBPFINAL), protocol-specific DVH metrics and normal tissue complication probability were compared for original versus KBPFINAL plans across the 35-patient validation set. Paired t tests were used to test differences between planning sets. RESULTS: KBPFINAL plans outperformed manual planning across the validation set in all protocol-specific DVH cutpoints. The mean normal tissue complication probability for gastrointestinal toxicity was lower for KBPFINAL versus validation-set plans (48.7% vs 53.8%, P<.001). Similarly, the estimated mean white blood cell count nadir was higher (2.77 vs 2.49 k/mL, P<.001) with KBPFINAL plans, indicating lowered probability of hematologic toxicity. CONCLUSIONS: This work demonstrates that a KBP system can be efficiently trained and refined for use in radiation therapy clinical trials with minimal effort. This patient-specific plan quality control resulted in improvements on protocol-specific dosimetric endpoints.