scholarly journals Estimation of cell response in fractionation radiotherapy using different methods derived from linear quadratic model

2015 ◽  
Vol 49 (4) ◽  
pp. 347-356 ◽  
Author(s):  
Safoora Nikzad ◽  
Bijan Hashemi ◽  
Golshan Mahmoudi ◽  
Milad Baradaran-Ghahfarokhi
Keyword(s):  
Cell Response ◽  
Treatment Time ◽  
Theoretical Models ◽  
Accurate Method ◽  
Quadratic Model ◽  
Breast Adenocarcinoma ◽  
Linear Quadratic ◽  
Overall Treatment Time ◽  
Simple Method ◽  
Theoretical Methods

Abstract Background. The aim of this study was to use various theoretical methods derived from the Linear Quadratic (LQ) model to calculate the effects of number of subfractions, time intervals between subfractions, dose per subfraction, and overall fraction time on the cells’ survival. Comparison of the results with experimental outcomes of melanoma and breast adenocarcinoma cells was also performed. Finally, the best matched method with experimental outcomes is introduced as the most accurate method in predicting the cell response. Materials and methods. The most widely used theoretical methods in the literature, presented by Keall et al., Brenner, and Mu et al., were used to calculate the cells’ survival following radiotherapy with different treatment schemes. The overall treatment times were ranged from 15 to 240 minutes. To investigate the effects of number of subfractions and dose per subfraction, the cells’ survival after different treatment delivery scenarios were calculated through fixed overall treatment times of 30, 60 and 240 minutes. The experimental tests were done for dose of 4 Gy. The results were compared with those of the theoretical outcomes. Results. The most affective parameter on the cells’ survival was the overall treatment time. However, the number of subfractions per fractions was another effecting parameter in the theoretical models. This parameter showed no significant effect on the cells’ survival in experimental schemes. The variations in number of subfractions per each fraction showed different results on the cells’ survival, calculated by Keall et al. and Brenner methods (P<0.05). Conclusions. Mu et al. method can predict the cells’ survival following fractionation radiotherapy more accurately than the other models. Using Mu et al. method, as an accurate and simple method to predict the cell response after fractionation radiotherapy, is suggested for clinical applications.

The application of the linear quadratic model to compensate the effects of prolonged fraction delivery time on a Balb/C breast adenocarcinoma tumor: Anin vivostudy

2015 ◽  
Vol 92 (2) ◽  
pp. 80-86 ◽  
Author(s):  
Safoora Nikzad ◽  
Bijan Hashemi ◽  
Zuhair Saraf Hasan ◽  
Hossein Mozdarani ◽  
Milad Baradaran-Ghahfarokhi ◽  
...  
Keyword(s):  
Quadratic Model ◽  
Breast Adenocarcinoma ◽  
Delivery Time ◽  
Linear Quadratic ◽  
Linear Quadratic Model

scholarly journals Applications of Nonlinear Programming to the Optimization of Fractionated Protocols in Cancer Radiotherapy

Information ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 313
Author(s):  
Alessandro Bertuzzi ◽  
Federica Conte ◽  
Federico Papa ◽  
Carmela Sinisgalli
Keyword(s):  
Nonlinear Programming ◽  
Treatment Time ◽  
External Beam Radiotherapy ◽  
Dose Fractionation ◽  
Quadratic Model ◽  
Analytical Determination ◽  
Model Parameters ◽  
Linear Quadratic ◽  
Quadratic Constraints

The present work of review collects and evidences the main results of our previous papers on the optimization of fractionated radiotherapy protocols. The problem under investigation is presented here in a unitary framework as a nonlinear programming application that aims to determine the optimal schemes of dose fractionation commonly used in external beam radiotherapy. The radiation responses of tumor and normal tissues are described by means of the linear quadratic model. We formulate a nonlinear, non-convex optimization problem including two quadratic constraints to limit the collateral normal tissue damages and linear box constraints on the fractional dose sizes. The general problem is decomposed into two subproblems: (1) analytical determination of the optimal fraction dose sizes as a function of the model parameters for arbitrarily fixed treatment lengths; and (2) numerical determination of the optimal fraction number, and of the optimal treatment time, in different parameter settings. After establishing the boundedness of the optimal number of fractions, we investigate by numerical simulation the optimal solution behavior for experimentally meaningful parameter ranges, recognizing the crucial role of some parameters, such as the radiosensitivity ratio, in determining the optimality of hypo- or equi-fractionated treatments. Our results agree with findings of the theoretical and clinical literature.

scholarly journals Intermolar Mandibular Distraction Osteogenesis—A Preliminary Report

2021 ◽  
Vol 11 (9) ◽  
pp. 4118
Author(s):  
Suen A. N. Lie ◽  
Britt H. B. T. Engelen ◽  
Veronique C. M. L. Timmer ◽  
Nico M. P. Vrijens ◽  
Paolo Asperio ◽  
...  
Keyword(s):  
Distraction Osteogenesis ◽  
Treatment Time ◽  
Average Length ◽  
Case Series ◽  
Growth Spurt ◽  
Overall Treatment Time ◽  
Mandibular Distraction ◽  
Mandibular Distraction Osteogenesis ◽  
Root Fractures

Background: Dental Class II is the most common indication for combined orthodontic-orthognathic treatment. Intermolar mandibular distraction osteogenesis (IMDO) treatment was performed during the growth spurt, to avoid surgery at a later age. The aim of this study is to present our first experience with IMDO. Methods: This is a retrospective case series of patients who underwent an IMDO. All patients showed mandibular retrognathism, and orthodontic treatment with functional appliances was not successful. Results: In total, 20 patients (mean age of 14.8 years (SD = 0.9 ys) were included. All patients achieved a Class I occlusion. An average length gain of 9.6 mm (SD = 3.7 mm) was reached. In one patient an abscess occurred. Nine patients presented with root fractures of the second molar; three were lost, one treated endodontically. The average time between insertion and removal of the distractors was 4.6 months (SD = 1.5 mths). In one case a premature consolidation was seen. Conclusion: We achieved satisfactory results with IMDO, although undesirable effects occurred. An advantage is the manageable overall treatment time. Open questions concern the occurrence of root fractures. Furthermore, the question of long-term stability is open. The question of dynamic distraction treatment in relation to temporomandibular joint changes can only be answered in the long term.

Primary Human Liver Cells as Source for Modular Extracorporeal Liver Support - a Preliminary Report

2002 ◽  
Vol 25 (10) ◽  
pp. 1001-1005 ◽  
Author(s):  
I.M. Sauer ◽  
K. Zeilinger ◽  
N. Obermayer ◽  
G. Pless ◽  
A. Grünwald ◽  
...  
Keyword(s):  
Human Liver ◽  
Treatment Time ◽  
Liver Perfusion ◽  
Cell Mass ◽  
Liver Weight ◽  
Liver Cells ◽  
Liver Support ◽  
Overall Treatment Time ◽  
Human Liver Cells ◽  
Extracorporeal Liver Support

Cell-based extracorporeal liver support is an option to assist or replace the failing organ until regeneration or until transplantation can be performed. The use of porcine cells or tumor cell lines is controversial. Primary human liver cells, obtained from explanted organs found to be unsuitable for transplantation, are a desirable cell source as they perform human metabolism and regulation. The Modular Extracorporeal Liver Support (MELS) concept combines different extracorporeal therapy units, tailored to suit the individual and intra-individual clinical needs of the patient. A multi-compartment bioreactor (CellModule) is loaded with human liver cells obtained by 5-step collagenase liver perfusion. A cell mass of 400 g – 600 g enables the clinical application of a liver lobe equivalent hybrid organ. A detoxification module enables single pass albumin-dialysis via a standard high-flux dialysis filter, and continuous venovenuous hemodiafiltration may be included if required. Cells from 54 human livers have been isolated (donor age: 56 ± 13 years, liver weight: 1862 ± 556 g resulting in a viability of 55.0 ± 15.9%). These grafts were not suitable for LTx, due to steatosis (54%), cirrhosis (15%), fibrosis (9%), and other reasons (22%). Out of 36 prepared bioreactors, 10 were clinically used to treat 8 patients with liver failure. The overall treatment time was 7–144 hours. No adverse events were observed. Initial clinical applications of the bioreactor evidenced the technical feasibility and safety of the system.

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