scholarly journals Normal tissue tolerance dose for cervical radiotherapy to the NTCP model using a method of least square fit

2020 ◽  
Vol 12 (1) ◽  
pp. 215-220
Author(s):  
E. Onuh ◽  
A.S. Ajuji ◽  
N. Rabiu ◽  
M.S. Anas ◽  
M. Jada
Keyword(s):  
Normal Tissue ◽  
Normal Tissue Complication Probability ◽  
Least Square ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Normal Tissue Tolerance ◽  
Tolerance Dose ◽  
Method Of Least Square ◽  
Least Square Fit

The purpose of this study is to evaluate the impact of Normal Tissue Complication Probability (NTCP) models on radiation treatment plans. We estimated NTCP parameters for the organs at risk (OARs) for cervical cancer radiotherapy. We pooled individual patient data from fifty patients who were treated with External Beam Radiotherapy technique between March 2012 and November 2013 in a part of Northern Nigeria with the exclusion of patients who had other gynaecological malignancies. Three basic methods were followed during the radiotherapy planning of these patients which included the pre-planning stage, planning radiotherapy treatment stage and treatment delivery. Various tests were carried out on these patients which helped to confirm the diagnosis after which they were treated using the linear accelerator, computed tomography simulator and the treatment planning system. We calculated the normal tissue tolerance doses for partial volumes of the organs using the values of the above –said parameters for published data on normal tissue tolerance doses. This article shows a graphical representation of the computed NTCP for left femur, right femur and skin presented and a fairly good correspondence is found between the curves for head of femurs and skin. Keywords: Normal Tissue Tolerance Dose, Normal Tissue Complication Probability, Method of Least Square Fit, Cervical Radiotherapy

The effect of the carbon fibre insert for the Varian Exact™ couch on the attenuation and build-up of high energy photon beams

2010 ◽  
Vol 10 (2) ◽  
pp. 77-83 ◽  
Author(s):  
ML Wilson ◽  
WP Colley ◽  
AW Beavis
Keyword(s):  
Carbon Fibre ◽  
External Beam Radiotherapy ◽  
High Energy ◽  
Planning System ◽  
Treatment Planning System ◽  
Skin Dose ◽  
Angle Of Incidence ◽  
Photon Beams ◽  
Radiation Beam ◽  
Tolerance Dose

AbstractCarbon fibre couch inserts are widely used in external beam radiotherapy to provide rigid and lightweight patient support. Carbon fibre is often perceived to be essentially radiotranslucent implying that it does not interfere with the radiation beam. However, there is evidence in the literature which suggests that this perception may not be appropriate, particularly at oblique angles of incidence. Furthermore, there is evidence indicating that the use of carbon fibre significantly reduces the skin sparing effect. In this study, the radiation attenuation and surface dose enhancement characteristics of the carbon fibre insert for the Varian ExactTM couch have been investigated. It was found that attenuation increased significantly with increasing angle of incidence, resulting in in-phantom dose reductions of up to 6% at 6 MV and 4% at 15 MV. It has been shown that it is possible to model couch attenuation on a commercial treatment planning system (Elekta CMS XiO) by including the carbon fibre insert in the planning computed tomography (CT) dataset. Finally, the carbon fibre insert was found to significantly increase skin dose to the patient. The skin dose was approximately three times as large when the couch insert was added to 6 and 15 MV photon beams. However, even with this substantial increase it is highly unlikely that the skin tolerance dose will be exceeded.

A hybrid approach for head and neck cancer using online image guidance and offline adaptive radiotherapy planning

2019 ◽  
Vol 18 (03) ◽  
pp. 271-275 ◽  
Author(s):  
Roopam Srivastava ◽  
P.K. Sharma ◽  
K.J. Maria Das ◽  
Jayanand Manjhi
Keyword(s):  
Computed Tomography ◽  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Dose Distribution ◽  
Treatment Plan ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Medical Systems

AbstractBackgroundThis is a prospective study to evaluate the dosimetric benefits of treatment plan adaptation for patients who had undergone repeat computed tomography (ReCT)and re-planning due to treatment-induced anatomical changes during radiotherapy.Materials and MethodsThis study involved five head and neck cancer patients who had their treatment plan modified, based on weekly thrice imaging protocol. Impact of mid-course imaging was assessed in patients using ReCT and cone beam computed tomography (CBCT)-based dose verification. Patients were imaged, apart from their initial CT, during the course of their radiation therapy with a ReCT and on board imager CBCT (Varian Medical Systems Inc., Palo Alto, CA, USA). Each CBCT/CT series was rigidly registered to the initial CT in the treatment planning system Eclipse (Varian Medical Systems Inc.) using bony landmarks. The structures were copied to the current CBCT/CT series and, where needed, manually edited slicewise. The dose distribution from the treatment plan was viewed as of the current anatomy by applying the treatment plan the CBCT/CT series, and studying the corresponding dose–volume histograms for organs at risk doses.ResultsThe reduction of parotid volumes due to weight loss was observed in all patients, which means an increase in predicted mean doses of parotid when initial CT plan was re-calculated on ReCT and CBCT (Table 1). This explains the necessity of adaptive planning. The predicted mean dose of parotid glands was increased and constraints to spinal cord and skin were exceeded, so re-planning was performed.ConclusionsThe CBCT is a useful tool to view anatomic changes in patients and get an estimate of their impact on dose distribution. Re-planning based on imaging in head and neck patients during the course of radiotherapy is mandatory to reduce side effects.

Development of a New Monte-Carlo Treatment Planning System for Boron Neutron Capture Therapy

2009 ◽  
Author(s):  
Hiroaki Kumada ◽  
Takemi Nakamura ◽  
Akira Matsumura ◽  
Koji Ono
Keyword(s):  
Monte Carlo ◽  
Treatment Planning ◽  
Boron Neutron Capture Therapy ◽  
Neutron Capture ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Neutron Capture Therapy ◽  
Particle Radiotherapy ◽  
Boron Neutron Capture

To improve treatment planning in boron neutron capture therapy (BNCT), a new Monte-Carlo radiotherapy planning system is under development at Japan Atomic Energy Agency (JAEA). This system (developing code: JCDS-FX) builds on fundamental technologies of JCDS (JAEA Computation Dosimetry System) which has been applied to actual BNCT trials at Japan Research Reactor No.4 (JRR-4). Basic technologies of JCDS have been taken over to JCDS-FX, and some new functions have been built into the system. One of features of the JCDS-FX is that PHITS as a multi-purpose particle Monte-Carlo transport code has been applied to particle transport calculation. Application of PHITS enables to evaluate doses for neutrons and photons as well as protons and heavy ions. Therefore, the JCDS-FX with PHITS can perform treatment planning for not only BNCT but also particle radiotherapy. To verify calculation accuracy of the JCDS-FX with PHITS, dose evaluations for neutron irradiation of a cylindrical water phantom and for an actual clinical trial conducted at JRR-4 were performed. The verification results indicated that JCDS-FX is applicable to BNCT treatment planning in practical use. Further verifications of the system are being performed to achieve practical application of the system in the future. And in addition to the BNCT, investigations for application of the system to any other particle radiotherapy like proton therapy are carried forward.

scholarly journals Comparison of 3DCRT Dose Distribution in Radiotherapy for Lung Cancer Patient by Using AAA and PBC Algorithms

2016 ◽  
Vol 68 ◽  
pp. 54-60
Author(s):  
Muhammad Masud Rana ◽  
S.M. Azharul Islam ◽  
M. Moinul Islam ◽  
Md. Shakilur Rahman ◽  
Sarwar Alam ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Treatment Planning ◽  
Dose Distribution ◽  
Radiation Treatment ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Medical Systems ◽  
Calculation Algorithm ◽  
Conformal Radiation Therapy

The Pencil Beam Convolution (PBC) algorithm in radiation treatment planning system is widely used to calculate the radiation dose distribution in radiotherapy planning. A new photon dose calculation algorithm known as Anisotropic Analytical Algorithm (AAA) by Varian Medical Systems is applied to investigate the difference of dose distribution by using AAA and PBC algorithms for the lung cancer with an inhomogeneity of its low density. In the present work, radiotherapy treatment planning of 10 lung cancer patients are designed with 6 MV photon beam using three-dimensional conformal radiation therapy (3DCRT) and dose distribution was calculated by the AAA and the PBC Algorithms. The dose distribution performance is evaluated by dose profile curve along transversal slice of PTV and Dose Volume Histogram (DVH) covered by the 95% isodose of PTV. The mean dose of organ at risks did not changed significantly but the volume of the PTV covered by the 95% isodose curve was decreased by 6% with inhomogeneity due to the algorithms. The dose distribution and the accuracy in calculating the absorbed dose of the AAA algorithm of the Varian Eclipse treatment planning system is analyzed and discussed.

A treatment planning system with new paradigms in the effectiveness and side-effect evaluation sections

2021 ◽  
Author(s):  
Terman Frometa-Castillo ◽  
Anil Pyakuryal ◽  
Ganesh Narayanasamy ◽  
Asghar Mesbahi
Keyword(s):  
Treatment Planning ◽  
Side Effect ◽  
Normal Tissue ◽  
External Beam Radiotherapy ◽  
Planning System ◽  
Treatment Planning System ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Computational Simulations ◽  
Linear Quadratic

Abstract Aim Academic dissemination of the “SMp treatment planning system (TPS)” for external beam radiotherapy, which has been developed as a software function that could meet the definition of a device with an entirely new intended use. This system will have new paradigms in the effectiveness and side-effect (S-E) evaluation sections, where tumor control probability (TCP) is calculated with computational simulations instead of current analytical TCP models; and S-E is evaluated with the normal tissue non-complication probability (NTCP0) methodology instead of standard NTCP one. Methods Use of probabilistic foundations in the NTCP0 methodologies; and computational simulations of the interactions of ionizing radiation with the tumor tissues in the radiation oncology treatments for the TCP calculations. Results The "TCPsim" and “NTCP0cal” calculation modules of the SMp TPS, which calculate respectively TCP and NTCP0. Conclusions While the "NTCP0cal" application has unquestionable probabilistic foundations associated to normal tissue complications as a stochastic process with more than one outcome; the "TCPsim" is based on proper approaches that are result of the computational simulations that follow logic-probabilistic procedures, and probabilistic aspects, like the relationship between TCP and linear-quadratic cell survival model for a fraction with dose d.

Effect of translational couch shifts in volumetric modulated arc therapy (VMAT) plans and predicting its impact on daily dose delivery

2017 ◽  
Vol 17 (2) ◽  
pp. 230-243
Author(s):  
Noufal M. Padannayil ◽  
Kallikuzhiyil K. Abdullah ◽  
Pallimanhayil A. R. Subha ◽  
Sanudev Sadanadan
Keyword(s):  
Volumetric Modulated Arc Therapy ◽  
Target Volume ◽  
Normal Tissue Complication Probability ◽  
Planning System ◽  
Treatment Planning System ◽  
Equivalent Uniform Dose ◽  
Tumour Control ◽  
Matlab Code ◽  
Arc Therapy ◽  
The Impact

AbstractAimTo evaluate the impact of couch translational shifts on dose–volume histogram (DVH) and radiobiological parameters [tumour control probability (TCP), equivalent uniform dose (EUD) and normal tissue complication probability (NTCP)] of volumetric modulated arc therapy (VMAT) plans and to develop a simple and swift method to predict the same online, on a daily basis.MethodsIn total, ten prostate patients treated with VMAT technology were selected for this study. The plans were generated using Eclipse TPS and delivered using Clinac ix LINAC equipped with a Millennium 120 multileaf collimator. In order to find the effect of systematic translational couch shifts on the DVH and radiobiological parameters, errors were introduced in the clinically accepted base plan with an increment of 1 mm and up to 5 mm from the iso-centre in both positive and negative directions of each of the three axis, x [right–left (R-L)], y [superior–inferior (S-I)] and z [anterior–posterior (A-P)]. The percentages of difference in these parameters (∆D, ∆TCP, ∆EUD and ∆NTCP) were analyzed between the base plan and the error introduced plans. DVHs of the base plan and the error plans were imported into the MATLAB software (R2013a) and an in-house MATLAB code was generated to find the best curve fitted polynomial functions for each point on the DVH, there by generating predicted DVH for planning target volume (PTV), clinical target volume (CTV) and organs at risks (OARs). Functions f(x, vj), f(y, vj) and f(z, vj) were found to represent the variation in the dose when there are couch translation shifts in R-L, S-I and A-P directions, respectively. The validation of this method was done by introducing daily couch shifts and comparing the treatment planning system (TPS) generated DVHs and radiobiological parameters with MATLAB code predicted parameters.ResultsIt was noted that the variations in the dose to the CTV, due to both systematic and random shifts, were very small. For CTV and PTV, the maximum variations in both DVH and radiobiological parameters were observed in the S-I direction than in the A-P or R-L directions. ∆V70 Gy and ∆V60 Gy of the bladder varied more due to S-I shift whereas, ∆V40 Gy, ∆EUD and ∆NTCP varied due to A-P shifts. All the parameters in rectum were most affected by the A-P shifts than the shifts in other two directions. The maximum percentage of deviation between the TPS calculated and MATLAB predicted DVHs of plans were calculated for targets and OARs and were found to be less than 0·5%.ConclusionThe variations in the parameters depend upon the direction and magnitude of the shift. The DVH curves generated by the TPS and predicted by the MATLAB showed good correlation.

scholarly journals Cranial organs at risk delineation: heterogenous practices in radiotherapy planning

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Guillaume Vogin ◽  
Liza Hettal ◽  
Clarisse Bartau ◽  
Juliette Thariat ◽  
Marie-Virginie Claeys ◽  
...  
Keyword(s):  
At Risk ◽  
Treatment Planning ◽  
Organs At Risk ◽  
Brain Structures ◽  
Individual Variability ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Kappa Index ◽  
Contrast Enhanced Ct

Abstract Background Segmentation is a crucial step in treatment planning that directly impacts dose distribution and optimization. The aim of this study was to evaluate the inter-individual variability of common cranial organs at risk (OAR) delineation in neurooncology practice. Methods Anonymized simulation contrast-enhanced CT and MR scans of one patient with a solitary brain metastasis was used for delineation and analysis. Expert professionals from 16 radiotherapy centers involved in brain structures delineation were asked to segment 9 OAR on their own treatment planning system. As reference, two experts in neurooncology, produced a unique consensual contour set according to guidelines. Overlap ratio, Kappa index (KI), volumetric ratio, Commonly Contoured Volume, Supplementary Contoured Volume were evaluated using Artiview™ v 2.8.2—according to occupation, seniority and level of expertise of all participants. Results For the most frequently delineated and largest OAR, the mean KI are often good (0.8 for the parotid and the brainstem); however, for the smaller OAR, KI degrade (0.3 for the optic chiasm, 0.5% for the cochlea), with a significant discrimination (p < 0.01). The radiation oncologists, members of Association des Neuro-Oncologue d’Expression Française society performed better in all indicators compared to non-members (p < 0.01). Our exercise was effective in separating the different participating centers with 3 of the reported indicators (p < 0.01). Conclusion Our study illustrates the heterogeneity in normal structures contouring between professionals. We emphasize the need for cerebral OAR delineation harmonization—that is a major determinant of therapeutic ratio and clinical trials evaluation.

scholarly journals Computerized tomography based evaluation of level I and II axillary lymph nodes by high conventional tangential fields in carcinoma breast

2020 ◽  
Vol 8 (2) ◽  
pp. 474
Author(s):  
Lalit Chandrakant ◽  
Shabnum Thakur ◽  
Manoj Gupta ◽  
Rajeev K. Seam ◽  
Manish Gupta ◽  
...  
Keyword(s):  
Lymph Nodes ◽  
Planning System ◽  
Radiotherapy Planning ◽  
Treatment Planning System ◽  
Axillary Lymph Nodes ◽  
Axillary Lymph ◽  
Axillary Nodes ◽  
Level Ii ◽  
Tangential Field ◽  
Level I

Background: Axillary radiation and surgery have provided equivalent local control in early breast cancer patients. It is believed that tangential field (TF) radiation that was used to treat the breast coincidently delivered radiation treatment to the lower axilla and eradicated the disease. In the era of CT-based three dimensional- (3D) radiotherapy planning, however concerns have been raised about the adequacy of coverage of the axillary levels in the tangential fields. In this study, author evaluated the coverage of the axillary nodal levels I and II using high conventional tangential fields in patients with or without axillary dissection.Methods: A prospective study was conducted which included 18 cases for a period of one year, radiation therapy was planned to the chest wall or whole breast by using the high conventional tangential field using 2D radiation portals. Central lung distance (CLD) and the distance of superior border was measured form the head of the humerus and were recorded. CECT chest was done in the same position alike during conventional simulation. All the images were shifted to the treatment planning system. The Contouring of Axillary lymph nodes level I and II was done on Oncentra contouring software.Results: The coverage of the axillary nodes was not related to central lung distance (CLD). However, some with CLD of 1cm had more coverage of the level I nodes than with CLD of 2 cm and the maximum CLD in the field was 2.5 cm. Of the 18 patients in the study, 13 patients had <2 cm distance from the humeral head and all the axillary level II LN covered in the field. Whereas 5 patients having distance >2 cm did not have adequate coverage of level II axillary LN’s.Conclusions: The distance of the cranial border of the tangent portal from the head of the humerus shows a relationship with coverage of level II nodes cranially. As the distance decreases the coverage of level II nodes cranially keeps increasing. In majority of the patients a distance of 2 cm or less than 2 cm ensured good coverage of level II nodes cranially. Similarly, no correlation was found between volumetric coverage of the axillary nodes with central lung distance.

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