93 research outputs found
A method to quantify and assess the dosimetric and clinical impact resulting from the heterogeneity correction in radiotherapy for lung cancer
Get PDFPurpose: The aim of this study was to propose a method to quantify and assess the differences in dose computations using heterogeneity correction algorithms for the planning target volumes and organs at risk.Methods: Six patients with lung cancer treated with 3-dimensional conformal radiation therapy were included and analysed. Dose calculations were performed using the pencil beam convolution (PBC) algorithm without heterogeneity correction and the Modified Batho method (PBC-MB) with heterogeneity correction. For each patient, 3 treatment plans were generated using exactly the same beam configuration. In plan 1, the dose was calculated using the PBC algorithm. In plan 2, the dose was calculated using the PBC-MB. In plan 3, the dose was calculated using the PBC-MB method but with the same number of monitor units obtained from plan 1. To evaluate the treatment plans computed by the PBC and PBC-MB, the monitor units, dose at the isocenter, spatial isodose distribution, dose volume histograms, conformity index, homogeneity index, planning target volumes conformity index, and geometrical index were compared. A statistical analysis was carried out using Wilcoxon signed rank test. Results: The PBC-MB method in plan 2 produced a lower number of monitor units than in plan 1 using PBC algorithm (p < 0.001). Dosimetric parameters derived from the dose volume histograms were higher for the planning target volumes and organs at risks using PBC-MB method for plans 2 and 3 when compared to plan 1. There was no significant difference for all the quality indices between plan 1 and plan 2, (p > 0.05), but a significant difference for the geometric index between plans 2 and 3 (p = 0.002) was observed.Conclusion: The risks related to the modification from the homogeneity plan to the heterogeneity plan were the reduction of delivered dose in monitor units for the planning target volumes and the increment of the dose to the organs at risk. We suggest the adaption in the dose prescriptions when switching the dose calculation algorithm from the PBC to PBC-MB.------------------------------------------------------Cite this article as: Chaikh A, Giraud J, Balosso J. A method to quantify and assess the dosimetric and clinical impact resulting from the heterogeneity correction in radiotherapy for lung cancer. Int J Cancer Ther Oncol 2014; 2(1):020110.DOI: http://dx.doi.org/10.14319/ijcto.0201.1
Developing a classroom science enrichment programme for gifted primary school boys in Saudi Arabia
No full textEnrichment is one of the important educational facilities that are provided for gifted students. However, the research on gifted enrichment programmes still requires further exploration in order to meet the diversity of gifted students. The purpose of this study was to determine the important components of an enrichment programme in science for gifted boys in the 6th grade of primary schools in Saudi Arabia. The current study has critiqued the components that are recommended in the literature pertaining to gifted programmes that include the Renzulli Model, VanTass- Baska Model, and Oasis Enrichment Model. Gifted programmes discussed are then discussed in relation to those that are provided to gifted students in schools and Universities in Saudi Arabia. Mixed methods were used in this descriptive study. Three methods have been used, documentary analysis, questionnaire, and interview. The documentary analyses of selected science textbook in 6th grade used mixed (qualitative and quantitative) approaches. The participants included 220 gifted students in primary schools in 6th grade from Dammam, Riyadh, and Jeddah city in Saudi Arabia, and 10 teachers and 10 supervisors of gifted education in science. Gifted students responded to questionnaires in order to ascertain their opinions about the current science textbook in 6th grade and what they would like to find in the Proposed Enrichment Programme (PEP). Interviews were conducted with teachers and supervisors of gifted education to examine in depth their IV perception about the current 6th grade science textbook and the Proposed Enrichment Programme in order to meet the needs of Saudi gifted students in 6th grade. The data from questionnaires were analysed in two phases. Firstly, the data were analysed and presented item by item for both the current science textbook ( ST questionnaire) and the proposed enrichment programme ( PEP questionnaire). All the items were examined by Chi square test to calculate whether there are any significant differences among each item in both questionnaires. Secondly, comparisons were made among the themes that emerged from the ST and PEP questionnaires. The responses of the interviewees were assigned to one of the content themes (attitudes to science, thinking skills, and contents and activities). Analysis of the words from respondents and counting frequencies of occurrence of ideas, themes, pieces of data, words (Cohen et al., 2007). The questionnaire data showed that the most important theme in the PEP for the gifted students is the “content of knowledge”. This reflects the students? views of the inadequacy of knowledge in the ST and their desire to further the development of content knowledge in the PEP. All the data from students and teachers and supervisors indicated that the ST needs to be improved to meet the needs of gifted students in two main areas: the level of thinking skills (e.g. evaluating and creating), and that the topics should be close to students? daily life and their environment. The findings of this research study showed agreement across all data collection instruments regarding the weakness of the activities in the 6th grade science textbook. This study considers that in order to enable gifted students to fulfil their potential in science in the regular classroom, it is necessary to provide further content and activities that require high levels of thinking, as provided by the PEP. The findings in this study clearly showed that there is a need for more challenge to stimulate gifted learners to learn which should be included in the PE
Methodology to assess the clinical and dosimetric impacts resulting from the change of a calculation algorithm in radiotherapy : Radiological Medical Physics
No full textIntroduction et objectif : La prescription des traitements en radiothérapie est basée sur l'analyse de la répartition de dose calculée par le TPS. Un changement d'algorithme de calcul doit être précédé d'une analyse dosimétrique complète, afin que les impacts cliniques soient maitrisés. Nous présentons une méthodologie de mise en œuvre d'un nouveau TPS. Matériel et méthodologie : Nous avons utilisé 5 algorithmes de calcul de dose. Nous avons comparé 6 plans de traitement avec des configurations identiques : patient, énergie, balistique. Nous avons comparé 12 localisations tumorales : 5 poumons, 1 œsophage, 1 sein, 3 ORL, 1 encéphales et 1 prostate. Le principe de méthodologie est basé sur deux critères d'analyse : 1.Critère d'analyse dosimétrique : nous avons classé les outils d'analyse en 3 catégories : analyse liée à la dose de traitement, analyse liée à la distribution de dose et analyse liée à la répartition de la dose 2.Critère d'analyse statistique : nous avons considéré que nous avons 5 séries de mesure liée à 5 algorithmes. Nous avons considéré les valeurs dosimétriques calculées par l'ancien algorithme comme valeurs de référence. Le test de comparaison statistique utilisé était un Wilcoxon pour série apparié avec un seuil de signification de 5% et un intervalle de confiance à 95%. Résultats et discussion : Nous avons trouvé des écarts pour tous les paramètres comparés dans cette étude. Ces écarts dépendent de la localisation de la tumeur et de l'algorithme de calcul. La maîtrise statistique des résultats nous permet, d'une part de diagnostiquer et interpréter les écarts dosimétriques observés et d'autre part, de déterminer si les écarts sont significatifs. Conclusion : Nous proposons une méthodologie qui permet de quantifier d'éventuels écarts dosimétriques lors d'un changement d'algorithme. L'analyse statistique permet de s'assurer que les résultats sont significatifs.Background and purpose The validation of a treatment plan is based on the analysis of dose distributions. The dose distributions are calculated by algorithms implanted in TPS. So, the changing of an algorithm must be preceded by a complete dosimetric analysis in order to provide a method for controlling the clinical impact of this change. We present in this study the methodology used for implementing a new TPS in our clinic. Materials and methods We used five algorithms for dose calculation: Clarkson, PBC, Batho Power Law, modified Batho and EqTAR. We compared six treatment plans with identical configurations: 2 plans without heterogeneity correction and 4 with density correction. We have compared nine tumours locations: 5 lungs, 1 oesophagus, 1 breast, 3head and neck, 1 brain and 1 prostate. We compared the following parameters: monitors units, HDV, isodoses, covering index, index of homogeneity, conformity index, geometric index and gamma index for 2D and 3D. We analyzed the results using a statistical evaluation and the method plot box. Results and discussion The gamma index 3D and histogram gamma generated for a CT slice can be used to compare various algorithms and radiotherapy plans. We found a difference in all parameters compared when the algorithm is changed. For example, we found a 5% difference in monitors units and 7% in dose for the pulmonary cancer case, when we change from PBC to EqTAR .This may leads to an increased of 30% in the complication rate. The statistical evaluation serves as a rapid interpretation and diagnostic of dosimetric differences and allows the determination of the significance of these differences. Conclusion We proposed a methodology that allows the quantification of dosimetric variation during the change of calculation algorithm in radiotherapy. This methodology provides a valuable technique for quantitative comparison of various algorithms and radiotherapy plan
Méthodologie d'évaluation des impacts cliniques et dosimétriques d'un changement de procédure en radiothérapie : Aspect - Radio physique et médical
No full textBackground and purpose The validation of a treatment plan is based on the analysis of dose distributions. The dose distributions are calculated by algorithms implanted in TPS. So, the changing of an algorithm must be preceded by a complete dosimetric analysis in order to provide a method for controlling the clinical impact of this change. We present in this study the methodology used for implementing a new TPS in our clinic. Materials and methods We used five algorithms for dose calculation: Clarkson, PBC, Batho Power Law, modified Batho and EqTAR. We compared six treatment plans with identical configurations: 2 plans without heterogeneity correction and 4 with density correction. We have compared nine tumours locations: 5 lungs, 1 oesophagus, 1 breast, 3head and neck, 1 brain and 1 prostate. We compared the following parameters: monitors units, HDV, isodoses, covering index, index of homogeneity, conformity index, geometric index and gamma index for 2D and 3D. We analyzed the results using a statistical evaluation and the method plot box. Results and discussion The gamma index 3D and histogram gamma generated for a CT slice can be used to compare various algorithms and radiotherapy plans. We found a difference in all parameters compared when the algorithm is changed. For example, we found a 5% difference in monitors units and 7% in dose for the pulmonary cancer case, when we change from PBC to EqTAR .This may leads to an increased of 30% in the complication rate. The statistical evaluation serves as a rapid interpretation and diagnostic of dosimetric differences and allows the determination of the significance of these differences. Conclusion We proposed a methodology that allows the quantification of dosimetric variation during the change of calculation algorithm in radiotherapy. This methodology provides a valuable technique for quantitative comparison of various algorithms and radiotherapy plansIntroduction et objectif : La prescription des traitements en radiothérapie est basée sur l'analyse de la répartition de dose calculée par le TPS. Un changement d'algorithme de calcul doit être précédé d'une analyse dosimétrique complète, afin que les impacts cliniques soient maitrisés. Nous présentons une méthodologie de mise en œuvre d'un nouveau TPS. Matériel et méthodologie : Nous avons utilisé 5 algorithmes de calcul de dose. Nous avons comparé 6 plans de traitement avec des configurations identiques : patient, énergie, balistique. Nous avons comparé 12 localisations tumorales : 5 poumons, 1 œsophage, 1 sein, 3 ORL, 1 encéphales et 1 prostate. Le principe de méthodologie est basé sur deux critères d'analyse : 1.Critère d'analyse dosimétrique : nous avons classé les outils d'analyse en 3 catégories : analyse liée à la dose de traitement, analyse liée à la distribution de dose et analyse liée à la répartition de la dose 2.Critère d'analyse statistique : nous avons considéré que nous avons 5 séries de mesure liée à 5 algorithmes. Nous avons considéré les valeurs dosimétriques calculées par l'ancien algorithme comme valeurs de référence. Le test de comparaison statistique utilisé était un Wilcoxon pour série apparié avec un seuil de signification de 5% et un intervalle de confiance à 95%. Résultats et discussion : Nous avons trouvé des écarts pour tous les paramètres comparés dans cette étude. Ces écarts dépendent de la localisation de la tumeur et de l'algorithme de calcul. La maîtrise statistique des résultats nous permet, d'une part de diagnostiquer et interpréter les écarts dosimétriques observés et d'autre part, de déterminer si les écarts sont significatifs. Conclusion : Nous proposons une méthodologie qui permet de quantifier d'éventuels écarts dosimétriques lors d'un changement d'algorithme. L'analyse statistique permet de s'assurer que les résultats sont significatifs
Characterization of nanodosimeter for real time measurements in radiotherapy and medical physics
No full textInternational audiencePurpose: The available implantable dosimeters in radiotherapy,i.e. semiconductor, MOSFET, radio luminescence of gallium nitride,etc, are imperfect and need a correction factors. In this study,we probos by simulation the size limit for a new generation of dosimetersat micro/nano scale for real time measurements in routine radiotherapy.Materials & Methods: Monte-Carlo simulations were carried out to study the influence of nanodosimeter size on the accuracy indose measurements using a water volume irradiated with 60Co photons. The mean specific energy (), characterizing the actualdeposited dose, was calculated for variousdose values and various radii of cylindrical targets placed within the irradiated volume.Then, the probability that a measurement yields a value outside the intervals [-γ ; +γ] with γ equal to 3%, 5% and10% was calculated.Results & Discussion: The distributions for the smallest target show a very high dispersion of specific energy values, while those forthe largest target tend to become gaussian and narrower, with increasing dose. An excessively small radius renders the measurementschaotic and not statistically-reproducible, even for a dose as high as 10 Gy. On the other hand, a target radius of 10 μm may allow fora better reproducibility of the measurements in a wider range of doses.Conclusion: The ability of the nano dosimeter to yield measurements dependent on its size and on the deposited dose.Nano dosimetershould be large enough to produce a statistically-reproducible measurement in the intended range around the irradiation dose value.BiographyAbdulhamid Chaikh, has completed his PhD at Grenoble-Alpes University, France. He was qualified for Assistant Professor position in French University. He is working as scientist for Medical Physics & Radiation Oncology and teaching in master degree at the medical school of Grenoble-Alpes University. He has published more than 15 papers in international journals and participated to over 15 national and international conferences. He is carrying out peer reviewed articles and serving as an Editorial Board Member of the Journal of Case Reports in Oncology and Therapy. He is a member of American Association of Physicists in Medicine
Agreement between gamma passing rates using computed tomography in radiotherapy and secondary cancer risk prediction from more advanced dose calculated models
No full textStatistical control process to compare and rank treatment plans in radiation oncology: impact of heterogeneity correction on treatment planning in lung cancer
No full textAssessing the shift of radiobiological metrics in lung radiotherapy plans using 2D gamma index
No full textThe use of TCP based EUD to rank and compare lung radiotherapy plans: in-silico study to evaluate the correlation between TCP with physical quality indices
No full textStatistic and dosimetric criteria to assess the shift of the prescribed dose for lung radiotherapy plans when integrating point kernel models in medical physics: are we ready?
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