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1.
Medicine (Baltimore) ; 99(34): e21800, 2020 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-32846816

RESUMO

Delineation of organs at risk (OARs) is important but time consuming for radiotherapy planning. Automatic segmentation of OARs based on convolutional neural network (CNN) has been established for lung cancer patients at our institution. The aim of this study is to compare automatic segmentation based on CNN (AS-CNN) with automatic segmentation based on atlas (AS-Atlas) in terms of the efficiency and accuracy of OARs contouring.The OARs, including the lungs, esophagus, heart, liver, and spinal cord, of 19 non-small cell lung cancer patients were delineated using three methods: AS-CNN, AS-Atlas in the Pinnacle-software, and manual delineation (MD) by a senior radiation oncologist. MD was used as the ground-truth reference, and the segmentation efficiency was evaluated by the time spent per patient. The accuracy was evaluated using the Mean surface distance (MSD) and Dice similarity coefficient (DSC). The paired t-test or Wilcoxon signed-rank test was used to compare these indexes between the 2 automatic segmentation models.In the 19 testing cases, both AS-CNN and AS-Atlas saved substantial time compared with MD. AS-CNN was more efficient than AS-Atlas (1.6 min vs 2.4 min, P < .001). In terms of the accuracy, AS-CNN performed well in the esophagus, with a DSC of 73.2%. AS-CNN was better than AS-Atlas in segmenting the left lung (DSC: 94.8% vs 93.2%, P = .01; MSD: 1.10 cm vs 1.73 cm, P < .001) and heart (DSC: 89.3% vs 85.8%, P = .05; MSD: 1.65 cm vs 3.66 cm, P < .001). Furthermore, AS-CNN exhibited superior performance in segmenting the liver (DSC: 93.7% vs 93.6%, P = .81; MSD: 2.03 cm VS 2.11 cm, P = .66). The results obtained from AS-CNN and AS-Atlas were similar in segmenting the right lung. However, the performance of AS-CNN in the spinal cord was inferior to that of AS-Atlas (DSC: 82.1% vs 86.8%, P = .01; MSD: 0.87 cm vs 0.66 cm, P = .01).Our study demonstrated that AS-CNN significantly reduced the contouring time and outperformed AS-Atlas in most cases. AS-CNN can potentially be used for OARs segmentation in patients with pathological N2 (pN2) non-small cell lung cancer.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/radioterapia , Neoplasias Pulmonares/radioterapia , Redes Neurais de Computação , Órgãos em Risco , Planejamento da Radioterapia Assistida por Computador/métodos , Esôfago , Coração , Humanos , Fígado , Pulmão , Reprodutibilidade dos Testes , Estudos Retrospectivos , Medula Espinal , Fatores de Tempo
2.
Anticancer Res ; 40(8): 4237-4244, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32727750

RESUMO

BACKGROUND/AIM: To study the changes of glioblastoma multiforme during chemoradiotherapy (CRT) and to evaluate the impact of changes on dosimetry and clinical outcomes. PATIENTS AND METHODS: Forty-three patients underwent volumetric imaging-based replanning. Prognostic factors and gross tumor volume changes in relation to overall survival and the effect of adaptive replanning were statistically analyzed. RESULTS: Patients with total tumor removal, with shorter time to CRT (<27 days), with methylated O-6 methylguanine DNA methyltransferase and good performance status (>60%) had better survival. Tumor shrinkage in 24 patients resulted in improved survival compared to 19 in whom tumor was unchanged or progressed (25.3 vs. 11.1 months, p=0.04). Adapted planning target volume allowed a reduction in irradiated volume, while increasing survival (12.06 vs. 28.98 months, p=0.026). CONCLUSION: Tumor response during CRT has significant impact on the outcome. Adaptation of the planning target volume to the tumor changes proved to be beneficial and warrants further investigation.


Assuntos
Neoplasias Encefálicas/radioterapia , Glioblastoma/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias Encefálicas/tratamento farmacológico , Quimiorradioterapia/métodos , Criança , Pré-Escolar , Feminino , Glioblastoma/tratamento farmacológico , Humanos , Masculino , Pessoa de Meia-Idade , Resultado do Tratamento , Adulto Jovem
3.
J Cancer Res Ther ; 16(3): 485-493, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32719255

RESUMO

Purpose: In this study, it is aimed to compare three different radiotherapy treatment planning techniques in terms of critical organ scoring index (COSI), two different conformity index (CI), tumor control probability (TCP), and normal tissue complication probability (NTCP) calculations in early (T1) glottic larynx carcinoma (T1GL). Furthermore, it is aimed to investigate these parameters compliance with dose-volume histograms (DVH) parameters. Materials and Methods: Ten T1GL patients were immobilized in a supine position with a head and neck thermoplastic mask. Treatment plans were created with opposed lateral fields (OLAFs) and intensity-modulated radiation therapy (IMRT) techniques with a total dose of 66 Gy in 33 fraction with 2 Gy/day. IMRT fields were selected as five fields (5IMRT) and seven fields (7IMRT). Dosimetric evaluation of three different treatment plans for T1GL carcinoma was performed in two consequential steps. First step was the assessment of planning target volume (PTV), all organs at risks (OARs), and normal tissue (NT) dose calculations according to given dose constraint directions and comparing the plans via DVH. In the second step, for PTV, the compatibility of DVH data with CIs-TCP was investigated where COSI-NTCP was compared with DVH for OARs. The DVH data were considered as reference in all evaluations. Results: The CIRTOG mean values were significantly closer to 1 with IMRT plans when compared to OLAF plans (P = 0.005). The CIPADDICK mean values revealed that OLAF plans were significantly worse than IMRT plans (P = 0.005). No statistically significant difference was found between all three plans in terms of homogeneity index mean values (P = 0.076). The calculated mean TCP values were significantly better for 7IMRT plans when compared to OLAF and 5IMRT plans (P = 0.007 and P = 0.017, respectively). Both NTCP and COSI evaluations, which is compatible with DVH, significantly favored OLAF plan for spinal cord and 7IMRT for thyroid gland. The COSI evaluations, which are compatible with DVH, significantly favored 7IMRT plan for carotid arteries and 5IMRT plan for NT. Conclusion: Our results demonstrated that CIPADDICK-TCP calculations for PTV and COSI-NTCP calculations for OARs were compatible with DVH in T1 GL plans. Therefore, we suggest such parameters as valuable tools for choosing the feasible one among multiple plans and even with different treatment machines.


Assuntos
Algoritmos , Glote/efeitos da radiação , Neoplasias Laríngeas/radioterapia , Laringe/efeitos da radiação , Órgãos em Risco/efeitos da radiação , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Glote/patologia , Humanos , Neoplasias Laríngeas/patologia , Laringe/patologia , Radiometria/métodos , Dosagem Radioterapêutica
4.
J Cancer Res Ther ; 16(3): 508-512, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32719258

RESUMO

Purpose: The study aimed to compare the radiobiological and dosimetric parameters between sequential boost (SEQB) and simultaneous integrated boost (SIB) treatment regimen using intensity-modulated arc therapy technique in locally advanced head-and-neck cancer (LAHNC) patients. Materials and Methods: A total of 24 previously untreated LAHNC patients were randomized into SIB (n= 11) and SEQB (n = 13) arms. The planning computed tomography data set was transferred to the treatment planning system. All the target volumes and organ at risk volumes were delineated. Single plan for SIB group and three plans (three phases) were generated for SEQB group of patients. Radiobiological and dosimetric parameters were compared. Results: The BED10(planned) value for high-risk (HR) planning target volume (PTV) was same in both groups, whereas for intermediate-risk (IR) PTV and low-risk (LR) PTV, the values were higher in SEQB arm than SIB arm. The V95 values were 100% for all the target volumes in both arms of patients. The average D100 value for gross target volume, HR PTV, and IR PTV was higher in SEQB arm than that in the SIB arm. The average D100 value for LR PTV was higher in the SIB arm compared to that of the SEQB arm. The BED10(achieved) was calculated using D100 values of target volumes. The difference of BED10(achieved) values between SEQB arm and SIB arm further increased than the BED10(planned) values for all target volumes. The maximum doses for spinal cord, spinal cord planning risk volume, and brain stem were within the tolerance dose in both groups of patients. The left and right parotid glands sparing was comparable in both groups of patients. Average integral dose was higher in the SIB group than SEQB group. The average total monitor unit per fraction was higher in the SEQB arm than that in the SIB arm. Conclusion: SIB regimen may be considered as more logical and efficient over SEQB regimen in the treatment of LAHNC with comparable radiobiological and dosimetric parameters.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Recidiva Local de Neoplasia/radioterapia , Planejamento de Assistência ao Paciente/normas , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos , Tomografia Computadorizada por Raios X/métodos , Terapia Combinada , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/diagnóstico por imagem , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Radiometria/métodos , Dosagem Radioterapêutica , Eficiência Biológica Relativa , Resultado do Tratamento
5.
J Cancer Res Ther ; 16(3): 530-533, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32719262

RESUMO

Context: An objective conformal radiotherapy treatment planning criteria that can predict severity of early effects of radiotherapy would be quite useful in reducing the side effects of radiotherapy thereby improving quality of life for head and neck cancer patients. Aim of Study: Retrospective study aimed at correlating the maximum dose in planning target volume (PTV) with early effects of radiation. Materials and Methods: Patients with squamous cell carcinoma of H and N region who received radical radiotherapy and concomitant chemotherapy were retrospectively analyzed for maximum dose in PTV and the requirement of gap during radiotherapy or else hospitalization for supportive care during or up to 1 month after completion of radical radiotherapy. Results: Of a total of 23 patients, 8 patients (34.7%) required a gap of 2-14 days during their treatment. Twelve patients (52.1%) required hospitalization for 1-4 days and 4 patients (17.3%) required hospitalization for supportive care after completion of radiotherapy. The maximum dose in PTV ranged from 105.1% to 132.8% with an average of 112.68%. Subgroup analysis revealed a nonsignificant highest maximum dose of 114.72% in subset of patients requiring gap during radiotherapy (n= 8). Conclusion: It was concluded that maximum dose in PTV is a useful predictor of need for inhospital supportive care.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Determinação de Necessidades de Cuidados de Saúde/estatística & dados numéricos , Cuidados Paliativos/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Radioterapia de Intensidade Modulada/métodos , Carcinoma de Células Escamosas de Cabeça e Pescoço/radioterapia , Adulto , Idoso , Feminino , Neoplasias de Cabeça e Pescoço/patologia , Humanos , Masculino , Pessoa de Meia-Idade , Planejamento de Assistência ao Paciente , Segurança do Paciente , Qualidade de Vida , Dosagem Radioterapêutica , Estudos Retrospectivos , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Resultado do Tratamento
6.
Br J Radiol ; 93(1112): 20200197, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32614607

RESUMO

OBJECTIVE: This study presents a methodology for voxel-based evaluation of two phase sequential radiotherapy treatment plans having conventional dose scheme in the first phase and subsequent hypofractionation dose scheme in the second phase based upon different priority [planning target volume (PTV), clinical target volume (CTV) and organs at risk (OAR)] of display modes. METHODS: A case of carcinoma prostate was selected for demonstration. Varian Eclipse treatment planning system (TPS) was used for contouring and planning. In the first phase, a dose of 52 Gy in 26 fractions to the PTV and in the second phase, a dose of 19.5 Gy in 3 fractions to the PTV Boost was planned on the same CT data set. Both the plans (Phase 1 and Phase 2) were exported and processed using "Voxel-based radiobiology display (VRb) tool". Plan Sum for Biologically effective dose (BED)-Cube and equivalent dose of 2Gy (EQD2)-Cube was reconstructed using a combination of linear quadratic (LQ) and linear quadratic-linear (LQ-L) radiobiological models. Tumor control probability (TCP) and normal tissue complication probability (NTCP) for different target volumes and organs were also calculated using EQD2-volume histograms of the Plan Sum. RESULTS: An in-house graphical user interface (GUI) is developed to present the qualitative and quantitative evaluation of the multiphase treatment plans with different display modes and dose regimens. The voxel based TCP obtained for the combined target volume was 90.56%. NTCP for the bladder and rectum was calculated from the Plan Sum histograms and found to be 0.33% and ~0.0% respectively. CONCLUSION: The proposed methodology using the VRb tool offers superior plan evaluation for multiphase sequential radiotherapy treatment plans over the existing methods. ADVANCES IN KNOWLEDGE: PTV, CTV and OAR priority based display modes in VRb tool offers better understanding of radiobiological evaluation of sequential radiotherapy treatment plans.


Assuntos
Fracionamento da Dose de Radiação , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Masculino , Modelos Estatísticos , Próstata/patologia , Neoplasias da Próstata/patologia , Neoplasias da Próstata/radioterapia
7.
Br J Radiol ; 93(1112): 20200122, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32667848

RESUMO

OBJECTIVE: Dose-averaged linear energy transfer (LETD) is one of the factors which determines relative biological effectiveness (RBE) for treatment planning in proton therapy. It is usually determined from Monte Carlo (MC) simulation. However, no standard simulation protocols were established for sampling of LETD. Simulation parameters like maximum step length and range cut will affect secondary electrons production and have an impact on the accuracy of dose distribution and LETD. We aim to show how different combinations of step length and range cut in GEANT4 will affect the result in sampling of LETD using different MC scoring methods. METHODS: In this work, different step length and range cut value in a clinically relevant voxel geometry were used for comparison. Different LETD scoring methods were established and the concept of covariance between energy deposition per step and step length is used to explain the differences between them. RESULTS: We recommend a maximum step length of 0.05 mm and a range cut of 0.01 mm in MC simulation as this yields the most consistent LETD value across different scoring methods. Different LETD scoring methods are also compared and variation up to 200% can be observed at the plateau of 80 MeV proton beam. Scoring Method one has one of the lowest percentage differences compared across all simulation parameters. CONCLUSION: We have determined a set of maximum step length and range cut parameters to be used for LETD scoring in a 1 mm voxelized geometry. LETD scoring method should also be clearly defined and standardized to facilitate cross-institutional studies. ADVANCES IN KNOWLEDGE: Establishing a standard simulation protocol for sampling LETD would reduce the discrepancy when comparing data across different centres, and this can improve the calculation for RBE.


Assuntos
Transferência Linear de Energia , Doses de Radiação , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Modelos Estatísticos , Método de Monte Carlo , Eficiência Biológica Relativa
8.
PLoS One ; 15(7): e0236585, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32722692

RESUMO

The aim of this work is to build a framework that comprehends inverse planning procedure and plan optimization algorithm tailored to a novel directional beam intensity-modulated brachytherapy (IMBT) of cervical cancer using a rotatable, single-channel radiation shield. Inverse planning is required for finding optimal beam emitting direction, source dwell position and dwell time, which begin with creating a kernel matrix for each structure based on Monte-Carlo simulated dose distribution in the rotatable shield. For efficient beam delivery and less transit dose, the number of source dwell positions and angles needs to be minimized. It can be solved by L0-norm regularization for fewest possible dwell points, and by group sparsity constraint in L2,p-norm (0≤p<1) besides L0-norm for fewest active applicator rotating angles. The dose distributions from our proposed algorithms were compared to those of conventional tandem-based intracavitary brachytherapy (ICR) plans for six cervical cancer patients. The algorithmic performance was evaluated in delivery efficiency and plan quality relative to the unconstrained algorithm. The proposed framework yielded substantially enhanced plan quality over the conventional ICR plans. The L0-norm and (group sparsity+L0-norm) constrained algorithms reduced the number of source dwell points by 60 and 70% and saved 5 and 8 rotational angles on average (7 and 11 angles for highly modulated cases), relative to the unconstrained algorithm, respectively. Though both algorithms reduced the optimal source dwell positions and angles, the group sparsity constrained optimization with L0-norm was more effective than the L0-norm constraint only, mainly because of considering physical constraints of the new IMBT applicator. With much fewer dwell points compared to the unconstrained, the proposed algorithms led to statistically similar plan quality in dose volume histograms and iso-dose lines. It also demonstrated that the plan optimized by rotating the applicator resulted in much better plan quality than that of conventional applicator-based plans.


Assuntos
Braquiterapia/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/instrumentação , Rotação , Neoplasias do Colo do Útero/radioterapia , Algoritmos , Feminino , Humanos
9.
Cancer Radiother ; 24(5): 411-417, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32517893

RESUMO

Improved computer resources in radiation oncology department have greatly facilitated the integration of multimodal imaging into the workflow of radiation therapy. Nowadays, physicians have highly informative imaging modalities of the anatomical region to be treated. These images contribute to the targeting accuracy with the current treatment device, impacting both segmentation or patient's positioning. Additionally, in a constant effort to deliver personalized care, many teams seek to confirm the benefits of adaptive radiotherapy. The published works highlight the importance of registration algorithms, particularly those of elastic or deformable registration necessary to take into account the anatomical evolutions of the patients during the course of their therapy. These algorithms, often considered as "black boxes", tend to be better controlled and understood by physicists and physicians thanks to the generalization of evaluation and validation methods. Given the still significant development of medical imaging techniques, it is foreseeable that multimodal registration needs require more efficient algorithms well integrated within the flow of data.


Assuntos
Algoritmos , Imagem Multimodal/métodos , Posicionamento do Paciente/métodos , Radioterapia Guiada por Imagem/métodos , Fracionamento da Dose de Radiação , Feminino , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/radioterapia , Humanos , Imagem por Ressonância Magnética , Imagem Multimodal/normas , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/radioterapia , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Controle de Qualidade , Planejamento da Radioterapia Assistida por Computador/métodos , Planejamento da Radioterapia Assistida por Computador/normas , Radioterapia Guiada por Imagem/normas , Tomografia Computadorizada por Raios X , Neoplasias do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/radioterapia
10.
J Cancer Res Clin Oncol ; 146(9): 2267-2276, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32514629

RESUMO

BACKGROUND: To investigate the role of intensity-modulated proton therapy (IMPT) compared to volumetric modulated arc therapy (VMAT) for the radiation treatment of thymoma cancer. METHODS: Twenty patients were retrospectively planned for IMPT [with (IMPT_R1 or IMPT_R2 according to the approach adopted) and without robust optimization] and VMAT. The results were compared according to dose-volume metrics on the clinical and planning target volumes (CTV and PTV) and the main organs at risk (heart, breasts, lungs, spinal cord and oesophagus). Estimates of the excess absolute risk (EAR) of secondary cancer induction were determined for the oesophagus, the breasts and the composite lungs. For the heart, the relative risk (RR) of chronic heart failure (CHF) was assessed. RESULTS: IMPT and VMAT plans resulted equivalent in terms of target coverage for both the CTV and the PTV. The CTV homogeneity index resulted in 0.03 ± 0.01 and 0.04 ± 0.01 for VMAT and all IMPT plans, respectively. The conformality index resulted in 1.1 ± 0.1 and 1.2 ± 0.1 for VMAT and all IMPT plans. The mean dose to the breasts resulted in 10.5 ± 5.0, 4.5 ± 3.4, 4.7 ± 3.5 and 4.6 ± 3.4 Gy for VMAT, IMPT, IMPT_R1 and IMPT_R2. For the lungs, the mean dose was 9.6 ± 2.3, 3.5 ± 1.5, 3.6 ± 1.6 and 3.8 ± 1.4 Gy; for the heart: 8.7 ± 4.4, 4.3 ± 1.9, 4.5 ± 2.0 and 4.4 ± 2.4 Gy and for the oesophagus 8.2 ± 3.5, 2.2 ± 3.4, 2.4 ± 3.6 and 2.5 ± 3.5 Gy. The RR for CHF was 1.6 ± 0.3 for VMAT and 1.3 ± 0.2 for IMPT (R1 or R2). The EAR was 3.6 ± 0.v vs 1.0 ± 0.6 or 1.2 ± 0.6 (excess cases/10,000 patients year) for the oesophagus; 17.4 ± 6.5 vs 5.7 ± 3.2 or 6.1 ± 3.8 for the breasts and 24.8 ± 4.3 vs 8.1 ± 2.7 or 8.7 ± 2.3 for the composite lungs for VMAT and IMPT_R, respectively. CONCLUSION: The data from this in-silico study suggest that intensity-modulated proton therapy could be significantly advantageous in the treatment of thymoma patients with particular emphasis to a substantial reduction of the risk of cardiac failure and secondary cancer induction. Robust planning is a technical pre-requisite for the safety of the delivery.


Assuntos
Timoma/radioterapia , Neoplasias do Timo/radioterapia , Esôfago/efeitos da radiação , Feminino , Humanos , Pulmão/efeitos da radiação , Masculino , Terapia com Prótons/métodos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada , Estudos Retrospectivos
11.
Technol Cancer Res Treat ; 19: 1533033820905826, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32484037

RESUMO

BACKGROUND: To evaluate the patterns of failure in patients treated for head and neck carcinoma of unknown primary and to discuss treatment practices concerning radiotherapy target volumes definition and dose prescription. METHODS: Eleven patients presenting a locoregional recurrence after head and neck carcinoma of unknown primary treatment with curative-intent radiochemotherapy performed between 2007 and 2017 in the departments of radiation oncology of 2 French cancer institutes. Images of the computed tomography scan or the magnetic resonance imaging performed at the time of the recurrence were fused with those of the simulation computed tomography scan to delimit a volume corresponding to the recurrence and to define the area of relapse compared to the volumes treated. RESULTS: Irradiation was unilateral in 6 cases and bilateral in 5 cases. The median time to onset of recurrence was 7.24 months (extreme 3-67.7 months). Six patients had only a neck node recurrence, 3 had a neck node and subsequent primary recurrence, and 1 had only a median subsequent primary recurrence. Only 1 patient had synchronous distance progression to local recurrence. All neck node recurrences were solitary and ipsilateral. The subsequent primary recurrences were in the oropharynx in 3 cases and in the contralateral oral cavity in one case. All neck node recurrences were into the irradiated volume. The subsequent primary recurrences were either within or in border of the irradiated volumes. The median of the mean dose, received by neck node recurrences, was 69.9 Gy and that of the mean dose, minimum dose, maximum dose, and dose received by 95% of the volume of recurrence was 66.7 Gy. For the primary relapses, the median of the mean dose was 52.1 Gy and that of the mean dose, minimum dose, maximum dose, and dose received by 95% of the volume of recurrence was 39.9 Gy. CONCLUSIONS: All local nodal recurrences occurred at sites that received high radiotherapy doses and doses received by sites of eventual failure did not vary significantly from sites that remain in control.


Assuntos
Quimiorradioterapia/métodos , Recidiva Local de Neoplasia/terapia , Neoplasias Primárias Desconhecidas/patologia , Neoplasias Primárias Desconhecidas/terapia , Dosagem Radioterapêutica/normas , Carcinoma de Células Escamosas de Cabeça e Pescoço/patologia , Carcinoma de Células Escamosas de Cabeça e Pescoço/cirurgia , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Neoplasias de Cabeça e Pescoço/patologia , Neoplasias de Cabeça e Pescoço/terapia , Humanos , Masculino , Pessoa de Meia-Idade , Pescoço/patologia , Recidiva Local de Neoplasia/patologia , Estadiamento de Neoplasias , Planejamento da Radioterapia Assistida por Computador/métodos , Estudos Retrospectivos , Resultado do Tratamento
12.
Anticancer Res ; 40(5): 2567-2572, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32366401

RESUMO

BACKGROUND/AIM: To evaluate the utility of high spatial resolution digital positron emission tomography images with the source-to-background ratio (SBR) algorithm for gross tumour volume (GTV) delineation. MATERIALS AND METHODS: The bowl and spheres (10-37 mm) were filled with fluoro-2-deoxy-D-glucose to achieve 4-16 times background radioactivity. The images were reconstructed using three isotropic voxel sizes. The SBR and percentage threshold (TH) to SUVmax were calculated. The plots between SBR and TH were fitted using a regression equation. The contoured volumes (CVs) of the spheres were calculated by applying TH. RESULTS: TH was 38.6+75.0/SBR for 4 mm voxel size; 39.6+37.0/SBR for 2 mm; and 38.8+35.2/SBR for 1 mm. The mean relative errors between CV and true volume for 4, 2, and 1 mm voxel sizes were 15%, 7%, and 7%, respectively. CONCLUSION: The present technique is useful for GTV delineation with reduced contouring error.


Assuntos
Algoritmos , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Tomografia por Emissão de Pósitrons , Planejamento da Radioterapia Assistida por Computador , Humanos , Neoplasias/diagnóstico por imagem , Neoplasias/patologia , Tomografia Computadorizada com Tomografia por Emissão de Pósitrons , Tomografia por Emissão de Pósitrons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos
13.
Cancer Radiother ; 24(4): 316-322, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32467083

RESUMO

PURPOSE: Gantry collision is a concern in linac-based stereotactic radiosurgery (SRS). Without collision screening, the planner may compromise optimal planning, unnecessary re-planning delays can occur, and incomplete treatments may be delivered. To address these concerns, we developed a software for collision prediction based on simple machine measurements. MATERIALS AND METHODS: Three types of collision were identified; gantry-couch mount, gantry-couch and gantry-patient. Trigonometric formulas to calculate the distance from each potential point of collision to the gantry rotation axis were generated. For each point, collision occurs when that distance is greater than the gantry head to gantry rotational axis distance. The colliding arc for each point is calculated. A computer code incorporating these formulas was generated. The inputs required are the couch coordinates relative to the isocenter, the patient dimensions, and the presence or absence of a circular SRS collimator. The software outputs the collision-free gantry angles, and for each point, the shortest distance to the gantry or the colliding sector when collision is identified. The software was tested for accuracy on a TrueBEAM® machine equipped with BrainLab® accessories for 80 virtual isocenter-couch angle configurations with and without a circular collimator and a parallelepiped phantom. RESULTS: The software predicted the absence of collision for 19 configurations. The mean absolute error between the measured and predicted gantry angle of collision for the remaining 61 cases was 0.86 (0.01-2.49). CONCLUSION: This tool accurately predicted collisions for linac-based intracranial SRS and is easy to implement in any radiotherapy facility.


Assuntos
Acidentes , Irradiação Craniana/instrumentação , Radiocirurgia/instrumentação , Planejamento da Radioterapia Assistida por Computador/métodos , Rotação , Software , Tamanho Corporal , Desenho de Equipamento , Humanos , Matemática
14.
J Cancer Res Clin Oncol ; 146(9): 2379-2397, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32372146

RESUMO

BACKGROUND: We present preliminary data of the first older cancer patients treated with Hybrid Linac for stereotactic body radiotherapy (SBRT) consisting of 1.5 T MRI-guided and daily-adapted treatment. The aim was to assess feasibility, safety and the role of G8 and Charlson Comorbidity Index (CCI) questionnaires in predicting patients' QoL, evaluated by patient-reported outcome measures (PROMs). METHODS: Two groups of patients with localized prostate cancer or abdominal-pelvic oligometastases were analyzed. SBRT schedule consisted of 35 Gy delivered in 5 fractions. The primary endpoint was to measure the impact of G8 and CCI on PROMs. Both G8 and the CCI were performed at baseline, while the EORTC Quality of Life Questionnaire-Core 30 (EORTC QLQ-C30) for PROMs assessment was prospectively performed at baseline and after SBRT. RESULTS: Forty older patients were analyzed. The median age was 73 years (range 65-85). For the entire population, the median G8 score was 15 (10-17) and the median CCI score was 6 (4-11). Concerning the PROMS, the EORTC-QLQ C30 questionnaire reported no difference between the pre- and post-SBRT evaluation in all patients, except for the fatigue item that declined after SBRT, especially in the group of patients with a G8 score < 15 and with age < 75 years (p = 0.049). No grade 3 or higher acute toxicity occurred. CONCLUSION: This is the first report documenting for older cancer patients that 1.5 T MRI-guided daily-adapted SBRT is feasible, safe and does not impact on the QoL at the end of treatment. Longer follow-up is advocated to report long-term outcomes. TRIAL REGISTRATION: Date of approval April 2019 and numbered MRI/LINAC no. 23748.


Assuntos
Abdome/patologia , Abdome/efeitos da radiação , Pelve/patologia , Pelve/efeitos da radiação , Neoplasias da Próstata/patologia , Neoplasias da Próstata/radioterapia , Idoso , Idoso de 80 Anos ou mais , Fracionamento da Dose de Radiação , Estudos de Viabilidade , Feminino , Avaliação Geriátrica/métodos , Humanos , Imagem por Ressonância Magnética/métodos , Masculino , Medidas de Resultados Relatados pelo Paciente , Estudos Prospectivos , Qualidade de Vida , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Inquéritos e Questionários
15.
Cancer Radiother ; 24(5): 429-436, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32247687

RESUMO

Imaging is critical to each step of precision radiation therapy, i.e. planning, setup, delivery and assessment of response. Hadrontherapy can be considered to deliver more precise dose distribution that may better spare normal tissues from intermediate low doses of radiation. In addition, hadrontherapy using high linear energy transfer ions may also be used for dose escalation on biological target volumes defined by functional imaging. However, the physical characteristics of hadrontherapy also make it more demanding in terms of imaging accuracy and image-based dose calculation. Some of the developments needed in imaging are specific to hadrontherapy. The current review addresses current status of imaging in proton therapy and the drawbacks of photon-based imaging for hadrons. It also addresses requirements in hadrontherapy planning with respect to multimodal imaging for proper target and organ at risk definition as well as to target putative radioresistant areas such as hypoxic ones, and with respect to dose calculation using dual energy CT, MR-proton therapy, proton radiography. Imaging modalities, such as those used in photon-based radiotherapy (intensity modulated and stereotactic radiotherapy), are somewhat already implemented or should be reaching "routine" hadrontherapy (at least proton therapy) practice in planning, repositioning and response evaluation optimizable within the next five years. Online monitoring imaging by PET, as currently developed for hadrontherapy, is already available. Its spatiotemporal limits restrict its use but similar to prompt gamma detection, represents an area of active research for the next 5 to 10 years. Because of the more demanding and specific dose deposit characteristics, developments image-guided hadrontherapy, such as specific proton imaging using tomography or ionoacoustics, as well as delivery with MR-proton therapy, may take another 10 years to reach the clinics in specific applications. Other aspects are briefly described such as range monitoring. Finally, the potential of imaging normal tissue changes and challenges to assess tumour response are discussed.


Assuntos
Radioterapia com Íons Pesados/métodos , Imagem Multimodal/métodos , Neoplasias/radioterapia , Órgãos em Risco/diagnóstico por imagem , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Transferência Linear de Energia , Neoplasias/diagnóstico por imagem , Órgãos em Risco/efeitos da radiação , Radioterapia/métodos , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Tomografia Computadorizada por Raios X/métodos
16.
Cancer Radiother ; 24(5): 398-402, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32247688

RESUMO

Computed tomography (CT) in the treatment position is currently indispensable for planning radiation therapy. Other imaging modalities, such as magnetic resonance imaging (MRI) and positron emission-tomography (PET), can be used to improve the definition of the tumour and/or healthy tissue but also to provide functional data of the target volume. Accurate image registration is essential for treatment planning, so MRI and PET scans should be registered at the planning CT scan. Hybrid PET/MRI scans with a hard plane can be used but pose the problem of the absence of CT scans. Finally, techniques for moving the patient on a rigid air-cushioned table allow PET/CT/MRI scans to be performed in the treatment position while limiting the patient's movements exist. At the same time, the advent of MRI-linear accelerator systems allows to redefine image-guided radiotherapy and to propose treatments with daily recalculation of the dose. The place of PET during treatment remains more confidential and currently only in research and prototype status. The same development of imaging during radiotherapy is underway in proton therapy.


Assuntos
Imagem por Ressonância Magnética/métodos , Imagem Multimodal/métodos , Neoplasias/diagnóstico por imagem , Neoplasias/radioterapia , Tomografia por Emissão de Pósitrons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Humanos , Imagem por Ressonância Magnética/instrumentação , Imagem Multimodal/instrumentação , Tomografia por Emissão de Pósitrons/instrumentação , Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/instrumentação
17.
Cancer Radiother ; 24(5): 403-410, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32265157

RESUMO

PURPOSE: Radiomics are a set of methods used to leverage medical imaging and extract quantitative features that can characterize a patient's phenotype. All modalities can be used with several different software packages. Specific informatics methods can then be used to create meaningful predictive models. In this review, we will explain the major steps of a radiomics analysis pipeline and then present the studies published in the context of radiation therapy. METHODS: A literature review was performed on Medline using the search engine PubMed. The search strategy included the search terms "radiotherapy", "radiation oncology" and "radiomics". The search was conducted in July 2019 and reference lists of selected articles were hand searched for relevance to this review. RESULTS: A typical radiomics workflow always includes five steps: imaging and segmenting, data curation and preparation, feature extraction, exploration and selection and finally modeling. In radiation oncology, radiomics studies have been published to explore different clinical outcome in lung (n=5), head and neck (n=5), esophageal (n=3), rectal (n=3), pancreatic (n=2) cancer and brain metastases (n=2). The quality of these retrospective studies is heterogeneous and their results have not been translated to the clinic. CONCLUSION: Radiomics has a great potential to predict clinical outcome and better personalize treatment. But the field is still young and constantly evolving. Improvement in bias reduction techniques and multicenter studies will hopefully allow more robust and generalizable models.


Assuntos
Diagnóstico por Imagem/métodos , Neoplasias/diagnóstico por imagem , Neoplasias/radioterapia , Radio-Oncologistas , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/secundário , Análise de Dados , Curadoria de Dados/métodos , Aprendizado Profundo , Neoplasias Esofágicas/diagnóstico por imagem , Neoplasias de Cabeça e Pescoço/diagnóstico por imagem , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Fenótipo , Radioterapia/métodos , Neoplasias Retais/diagnóstico por imagem , Reprodutibilidade dos Testes , Estudos Retrospectivos
18.
Phys Med Biol ; 65(11): 115002, 2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32235075

RESUMO

Respiratory-gated radiotherapy treatments of lung tumors reduce the irradiated normal tissue volume and potentially lower the risk of side effects. However, in clinical routine, the gating signal is usually derived from external markers or other surrogate signals and may not always correlate well with the actual tumor position. This study uses the kV-imaging system of a LINAC in combination with a multiple template matching algorithm for markerless real-time detection of the tumor position in a dynamic anthropomorphic porcine lung phantom. The tumor was realized by a small container filled with polymer dosimetry gel, the so-called gel tumor. A full end-to-end test for a gated treatment was performed and the geometric and dosimetric accuracy was validated. The accuracy of the tumor detection algorithm in SI- direction was found to be [Formula: see text] mm and the gel tumor was automatically detected in 98 out of 100 images. The measured 3D dose distribution showed a uniform coverage of the gel tumor and comparison with the treatment plan revealed a high 3D [Formula: see text]-passing rate of [Formula: see text] ([Formula: see text]). The simulated treatment confirmed the employed margin sizes for residual motion within the gating window and serves as an end-to-end test for a gated treatment based on a markerless fluoroscopic real-time tumor detection.


Assuntos
Fluoroscopia/métodos , Neoplasias Pulmonares/radioterapia , Planejamento da Radioterapia Assistida por Computador/métodos , Estudos de Viabilidade , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Movimento (Física) , Aceleradores de Partículas , Imagens de Fantasmas , Radiometria/métodos
19.
Phys Med Biol ; 65(11): 115003, 2020 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-32235080

RESUMO

The ion recombination is examined in parallel-plate ionization chambers in scanning proton beams at the Danish Centre for Particle Therapy and the Skandion Clinic. The recombination correction factor k s is investigated for clinically relevant energies between 70 MeV and 244 MeV for dose rates below 400 Gy min-1 in air. The Boutillon formalism is used to separate the initial and general recombination. The general recombination is compared to predictions from the numerical recombination code IonTracks and the initial recombination to the Jaffé theory. k s is furthermore calculated with the two-voltage method (TVM) and extrapolation approaches, in particular the recently proposed three-voltage (3VL) method. The TVM is in agreement with the Boutillon method and IonTracks for dose rates above 100 Gy min-1. However, the TVM calculated k s is closer related to the Jaffé theory for initial recombination for lower dose rate, indicating a limited application in scanning light ion beams. The 3VL is in turn found to generally be in agreement with Boutillon's method. The recombination is mapped as a function of the dose rate and proton energy at the two centres using the Boutillon formalism: the initial recombination parameter was found to be A = (0.10 ± 0.01) V at DCPT and A = (0.22 ± 0.13) V at Skandion, which is in better agreement with the Jaffé theory for initial recombination than previously reported values. The general recombination parameter was estimated to [Formula: see text] and [Formula: see text]. Furthermore, the numerical algorithm IonTracks is demonstrated to correctly predict the initial recombination at low dose rates and the general recombination at high dose rates.


Assuntos
Terapia com Prótons/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Algoritmos , Radiometria/métodos , Cintilografia/métodos
20.
Phys Med Biol ; 65(12): 125001, 2020 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-32330923

RESUMO

Magnetic resonance imaging (MRI) is gaining popularity in guiding radiation treatment for intrahepatic cancers due to its superior soft tissue contrast and potential of monitoring individual motion and liver function. This study investigates a deep learning-based method that generates synthetic CT volumes from T1-weighted MR Dixon images in support of MRI-based intrahepatic radiotherapy treatment planning. Training deep neutral networks for this purpose has been challenged by mismatches between CT and MR images due to motion and different organ filling status. This work proposes to resolve such challenge by generating 'semi-synthetic' CT images from rigidly aligned CT and MR image pairs. Contrasts within skeletal elements of the 'semi-synthetic' CT images were determined from CT images, while contrasts of soft tissue and air volumes were determined from voxel-wise intensity classification results on MR images. The resulting 'semi-synthetic' CT images were paired with their corresponding MR images and used to train a simple U-net model without adversarial components. MR and CT scans of 46 patients were investigated and the proposed method was evaluated for 31 patients with clinical radiotherapy plans, using 3-fold cross validation. The averaged mean absolute errors between synthetic CT and CT images across patients were 24.10 HU for liver, 28.62 HU for spleen, 47.05 HU for kidneys, 29.79 HU for spinal cord, 105.68 HU for lungs and 110.09 HU for vertebral bodies. VMAT and IMRT plans were optimized using CT-derived electron densities, and doses were recalculated using corresponding synthetic CT-derived density grids. Resulting dose differences to planning target volumes and various organs at risk were small, with the average difference less than 0.15 Gy for all dose metrics evaluated. The similarities in both image intensity and radiation dose distributions between CT and synthetic CT volumes demonstrate the accuracy of the method and its potential in supporting MRI-only radiotherapy treatment planning.


Assuntos
Neoplasias Hepáticas/radioterapia , Imagem por Ressonância Magnética/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Tomografia Computadorizada por Raios X/métodos , Abdome/diagnóstico por imagem , Humanos , Dosagem Radioterapêutica
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