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1.
Radiat Oncol ; 15(1): 73, 2020 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-32252792

RESUMO

PURPOSE: To compare CTVHR and OAR dimensions and inter-rater agreement between magnetic resonance (MR) and trans-rectal ultrasound (TRUS) images in IB cervical cancer patients. METHODS: IB cervical cancer patients treated with (chemo)radiotherapy plus MR-guided brachytherapy (BT) were prospectively enrolled in this study. Radiation oncologists contoured CTVHR and OARs in pre-BT MR images (MRI) and intra-operative TRUS images. These contours were subsequently compared in regard to volume and dimension. Contour inter-rater agreement analysis was also investigated using kappa index (KI). Stata 15.0 was used for statistical analysis and a p-value < 0.05 was considered statistically significant. RESULTS: TRUS CTVHR volumes were statistically smaller than the respective MRI contoured volumes. TRUS CTVHR thickness was found to be consistently smaller than MRI contours in all patients. No statistical difference was seen in width and height between the two different imaging modalities. MRI contours had a median KI of 0.66 (range: 0.56-0.77) while TRUS-based contours had a median KI of 0.64 (range: 0.47-0.77). Bladder and rectum had very satisfactory KI in both imaging modalities. Vaginal contours had moderate agreement in MR (0.52) and in TRUS images (0.58). CONCLUSION: TRUS images allow good visualization of CTVHR and OARs in IB cervical cancer patients. Inter-rater contour variability was comparable between TRUS and MR images. TRUS is a promising modality on its own for image-guided BT.


Assuntos
Órgãos em Risco , Neoplasias do Colo do Útero/diagnóstico por imagem , Feminino , Humanos , Imagem por Ressonância Magnética , Estadiamento de Neoplasias , Ultrassonografia
2.
Cancer Radiother ; 24(2): 128-134, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32224107

RESUMO

PURPOSE: Shielding disks play an important role in intraoperative electron radiation therapy, and different designs are currently used in clinical practice. This paper investigates the dosimetric impact of the shielding disk used during intraoperative electron radiation therapy (IOERT). MATERIALS AND METHODS: This paper focuses on the study of four shielding disks types that have been used in our clinic: Aluminum (Al)/Lead (Pb), PMMA/Copper(Cu)/PMMA, Aluminum (Al)/Copper (Cu) and Aluminum (Al)/Steel with their specific thicknesses. The theoretical study was conducted with the EGSnrc Monte Carlo (MC) code. On the other hand, the measurements were carried out with gafchromic films for the four shielding disks for the same setup inside the water phantom. Finally, a comparison of the simulated and measured PDD curves was performed for the four material combinations. RESULTS: MC simulation and gafchromic measurements illustrated that dose values under the four shielding disks types were close to 0, whereas the backscattering enhancement of the disks were 103% with Al/Pb shielding disk, 102% with Al/Steel shielding disk, 102% with Al/Cu shielding disk, 95% with PMMA/Cu/PMMA shielding disk. The PDDs values of the gafchromic films in front of the disks were: 107%, 105%, 104%, and 94% for the Al/Pb, Al/Steel, Al/Cu, and PMMA/Cu/PMMA disks respectively. CONCLUSIONS: The dose values above and under the shielding disks were acceptable for the four studied shielding types. Demonstrated it is possible to use any of them clinically, while the best shielding disk was the Al/Pb since it has minimum thickness and a small backscatter enhancement.


Assuntos
Elétrons/uso terapêutico , Cuidados Intraoperatórios/instrumentação , Método de Monte Carlo , Órgãos em Risco , Proteção Radiológica/instrumentação , Ligas , Alumínio , Neoplasias da Mama/radioterapia , Cobre , Desenho de Equipamento , Feminino , Coração , Humanos , Cuidados Intraoperatórios/métodos , Pulmão , Aceleradores de Partículas , Imagens de Fantasmas , Dosagem Radioterapêutica , Costelas , Espalhamento de Radiação , Aço
3.
4.
Cancer Radiother ; 24(2): 88-92, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32156457

RESUMO

PURPOSE: The optimal dose in esophageal cancer patients treated with definitive chemoradiation (CRT) remains debated. We herein report on the dosimetric results, treatment-related toxicities and long-term outcomes of escalated dose up to 60Gy delivered with intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: All consecutive patients that received a definitive CRT>50Gy for an unresectable esophageal carcinoma between 2010 and 2015 were retrospectively evaluated for this study. Methodology included data base search, delayed toxicity grading, statistical testing including frequency analysis and survival analysis. RESULTS: A total of 51 patients were irradiated for a squamous cell carcinoma (86.3%) or an adenocarcinoma (13.7%). The median age at diagnosis was 62 years. Seven patients were simultaneously irradiated for another synchronous primary tumor. Forty-six patients (90.2%) received concurrent platin-based chemotherapy. The median prescribed doses were 60Gy (54-66) and 48Gy (44.8-56) delivered in 30 (27-35) fractions to the high and the low risks PTV respectively. The mean dose delivered to the lungs was 11.4Gy (IC 95%: 4.8-19.8), the median volumes receiving up to 20Gy (V20) and 30Gy (V30) were 13.5% (3.0-46.0) and 4.6% (0.7-19.8) respectively. The mean dose delivered to the heart was 13.9Gy (IC 95%:0.3-31.3) with a median V40 of 3.3% (0.0-25.0). One treatment-related death occurred within days after RT completion (neutropenic aplasia). After a median follow-up of 2.7 years (95% CI: 1.9-4.3), the 2-year overall survival, disease free survival and loco-regional control rates were 53.6%, 42.0% and 72.8% respectively. Delayed treatment related-toxicities ≤grade 3 occurred among 25 patients (62.5%) mostly esophageal stricture (79.2%). CONCLUSION: We demonstrated in this study that dose escalation using IMRT in combination with platin-based chemotherapy as a definitive treatment for esophageal carcinoma is safe and results in higher loco-regional and control survival when compared to previously reported data.


Assuntos
Adenocarcinoma/terapia , Carcinoma de Células Escamosas/terapia , Quimiorradioterapia/métodos , Neoplasias Esofágicas/terapia , Tolerância a Radiação , Radioterapia de Intensidade Modulada/métodos , Adenocarcinoma/mortalidade , Adenocarcinoma/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Carcinoma de Células Escamosas/mortalidade , Carcinoma de Células Escamosas/patologia , Quimiorradioterapia/efeitos adversos , Intervalo Livre de Doença , Fracionamento da Dose de Radiação , Neoplasias Esofágicas/mortalidade , Neoplasias Esofágicas/patologia , Estenose Esofágica/etiologia , Feminino , Fluoruracila/administração & dosagem , Coração/efeitos da radiação , Humanos , Leucovorina/administração & dosagem , Pulmão/efeitos da radiação , Masculino , Pessoa de Meia-Idade , Compostos Organoplatínicos/administração & dosagem , Órgãos em Risco/efeitos da radiação , Radioterapia de Intensidade Modulada/efeitos adversos , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento
5.
Cancer Radiother ; 24(1): 28-37, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32007370

RESUMO

PURPOSE: To guide parotid gland (PG) sparing at the dose planning step, a specific model based on overlap between PTV and organ at risk (Moore et al.) was developed and evaluated for VMAT in head-and-neck (H&N) cancer radiotherapy. MATERIALS AND METHODS: One hundred and sixty patients treated for locally advanced H&N cancer were included. A model optimization was first performed (20 patients) before a model evaluation (110 patients). Thirty cases were planned with and without the model to quantify the PG dose sparing. The inter-operator variability was evaluated on one case, planned by 12 operators with and without the model. The endpoints were PG mean dose (Dmean), PTV homogeneity and number of monitor units (MU). RESULTS: The PG Dmean predicted by the model was reached in 89% of cases. Using the model significantly reduced the PG Dmean: -6.1±4.3Gy. Plans with the model showed lower PTV dose homogeneity and more MUs (+10.5% on average). For the inter-operator variability, PG dose volume histograms without the optimized model were significantly different compared to those with the model; the Dmean standard deviation for the ipsilateral PG decreased from 2.2Gy to 1.2Gy. For the contralateral PG, this value decreased from 2.9Gy to 0.8Gy. CONCLUSION: During the H&N inverse planning, the optimized model guides to the lowest PG achievable mean dose, allowing a significant PG mean dose reduction of -6.1Gy. Integrating this method at the treatment-planning step significantly reduced the inter-patient and inter-operator variabilities.


Assuntos
Neoplasias de Cabeça e Pescoço/radioterapia , Órgãos em Risco , Glândula Parótida , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/métodos , Carcinoma de Células Escamosas/radioterapia , Humanos , Glândula Parótida/efeitos da radiação , Planejamento da Radioterapia Assistida por Computador/métodos
6.
Sheng Wu Yi Xue Gong Cheng Xue Za Zhi ; 37(1): 136-141, 2020 Feb 25.
Artigo em Chinês | MEDLINE | ID: mdl-32096387

RESUMO

The segmentation of organs at risk is an important part of radiotherapy. The current method of manual segmentation depends on the knowledge and experience of physicians, which is very time-consuming and difficult to ensure the accuracy, consistency and repeatability. Therefore, a deep convolutional neural network (DCNN) is proposed for the automatic and accurate segmentation of head and neck organs at risk. The data of 496 patients with nasopharyngeal carcinoma were reviewed. Among them, 376 cases were randomly selected for training set, 60 cases for validation set and 60 cases for test set. Using the three-dimensional (3D) U-NET DCNN, combined with two loss functions of Dice Loss and Generalized Dice Loss, the automatic segmentation neural network model for the head and neck organs at risk was trained. The evaluation parameters are Dice similarity coefficient and Jaccard distance. The average Dice Similarity coefficient of the 19 organs at risk was 0.91, and the Jaccard distance was 0.15. The results demonstrate that 3D U-NET DCNN combined with Dice Loss function can be better applied to automatic segmentation of head and neck organs at risk.


Assuntos
Processamento de Imagem Assistida por Computador , Carcinoma Nasofaríngeo/patologia , Redes Neurais de Computação , Órgãos em Risco , Cabeça , Humanos , Pescoço , Tomografia Computadorizada por Raios X
7.
Br J Radiol ; 93(1109): 20190767, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32026724

RESUMO

OBJECTIVE: Due to the influence of gravity, inertia and friction, there will be deviation between the position of multileaf collimator (MLC) in the delivered field and the initial intensity modulated radiotherapy (IMRT) plan. This study explores the effects of the fragmentation level of subfield sequences on this deviation and seeks ways to improve the accuracy of field delivery in IMRT for nasopharyngeal carcinoma (NPC). METHODS: 30 patients with NPC were selected, and two groups (groups A and B) of IMRT plans were made in Pinnacle planning system. Different planning parameters were used for optimization so that the subfield sequence fragmentation level of Group B was significantly lower than that of Group A. With the MapCheck2, verification plan was implemented in two ways: 0o gantry angle and the actual treatment angle, then the differences between the two verification results of each group plan were analyzed. RESULTS: The γ-passing rate verified at the actual treatment angle was lower than that of 0o gantry angle for each group plan, whereas the Group B plan shows small reduction. Mean change value (Δ) was decreased from 1.01% (Group A) to 0.40% (Group B) with 3%/3 mm criteria and 2.88% (Group A) to 1.52% (Group B) with 2%/2 mm criteria, respectively. The smaller the difference (Δ), the actual output dose of the field is more consistent with the original plan. There was no significant correlation between this change and the angle of the field. CONCLUSION: Appropriately reducing the fragmentation level of subfield sequence can reduce the effect of field angle on MLC position and improve the delivery accuracy of IMRT plan. ADVANCES IN KNOWLEDGE: The fragmentation level of the subfield sequence may have an impact on the accuracy of the delivery of the plan. This study demonstrates this assumption by comparing the differences between 0° and actual angle verification. Mean change value (Δ) was decreased from Group A to Group B. The smaller the difference (Δ), the actual output dose of the field is more consistent with the original plan. The result of this study may help us to understand that appropriately increasing the subfield area and reducing the fragmentation level of the subfield sequence can reduce the difference between the two verification results, which can further improve the accuracy of the plan delivery in IMRT and tumor treatment.


Assuntos
Carcinoma Nasofaríngeo/radioterapia , Neoplasias Nasofaríngeas/radioterapia , Radioterapia de Intensidade Modulada/normas , Desenho de Equipamento , Humanos , Tratamentos com Preservação do Órgão/métodos , Órgãos em Risco , Planejamento de Assistência ao Paciente , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada/instrumentação , Radioterapia de Intensidade Modulada/métodos , Sensibilidade e Especificidade
8.
Br J Radiol ; 93(1107): 20190807, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32003574

RESUMO

After years of lethargy, studies on two non-conventional microstructures in time and space of the beams used in radiation therapy are enjoying a huge revival. The first effect called "FLASH" is based on very high dose-rate irradiation (pulse amplitude ≥106 Gy/s), short beam-on times (≤100 ms) and large single doses (≥10 Gy) as experimental parameters established so far to give biological and potential clinical effects. The second effect relies on the use of arrays of minibeams (e.g., 0.5-1 mm, spaced 1-3.5 mm). Both approaches have been shown to protect healthy tissues as an endpoint that must be clearly specified and could be combined with each other (e.g., minibeams under FLASH conditions). FLASH depends on the presence of oxygen and could proceed from the chemistry of peroxyradicals and a reduced incidence on DNA and membrane damage. Minibeams action could be based on abscopal effects, cell signalling and/or migration of cells between "valleys and hills" present in the non-uniform irradiation field as well as faster repair of vascular damage. Both effects are expected to maintain intact the tumour control probability and might even preserve antitumoural immunological reactions. FLASH in vivo experiments involving Zebrafish, mice, pig and cats have been done with electron beams, while minibeams are an intermediate approach between X-GRID and synchrotron X-ray microbeams radiation. Both have an excellent rationale to converge and be applied with proton beams, combining focusing properties and high dose rates in the beam path of pencil beams, and the inherent advantage of a controlled limited range. A first treatment with electron FLASH (cutaneous lymphoma) has recently been achieved, but clinical trials have neither been presented for FLASH with protons, nor under the minibeam conditions. Better understanding of physical, chemical and biological mechanisms of both effects is essential to optimize the technical developments and devise clinical trials.


Assuntos
Tratamentos com Preservação do Órgão/métodos , Terapia com Prótons/métodos , Animais , Gatos , Proliferação de Células , Dano ao DNA , Reparo do DNA , Fracionamento da Dose de Radiação , Linfoma Cutâneo de Células T/radioterapia , Camundongos , Órgãos em Risco/efeitos da radiação , Oxigênio , Consumo de Oxigênio , Lesões por Radiação/prevenção & controle , Tolerância a Radiação , Radiometria/métodos , Neoplasias Cutâneas/radioterapia , Análise Espaço-Temporal , Suínos , Peixe-Zebra
9.
Radiol Clin North Am ; 58(2): 199-213, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32044002

RESUMO

This article discusses the 4 main imaging modalities used to evaluate reproductive-aged women: ultrasound, magnetic resonance imaging, computed tomography, and fluoroscopy. For each modality, major clinical indications are described, along with important technical considerations unique to imaging reproductive-aged women. Finally, key safety issues are discussed, particularly with regard to imaging pregnant patients.


Assuntos
Imagem por Ressonância Magnética/métodos , Pelve/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Ultrassonografia/métodos , Adulto , Feminino , Fluoroscopia/efeitos adversos , Fluoroscopia/métodos , Humanos , Imagem por Ressonância Magnética/efeitos adversos , Órgãos em Risco , Tomografia Computadorizada por Raios X/efeitos adversos , Ultrassonografia/efeitos adversos
10.
Int J Radiat Oncol Biol Phys ; 106(3): 604-611, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32014151

RESUMO

PURPOSE: Steep dose falloff outside of tumors is a hallmark of stereotactic radiosurgery (SRS) and radiation therapy (SRT). Dose gradient index (DGI) quantifies the dose drop off. Tables of DGIs versus target volumes have been published for body sites, but none is available for brain. This study recommends guidelines for DGIs for brain SRS/SRT treatments based on clinical CyberKnife (CK) cases. METHODS AND MATERIALS: Four hundred ninety-five plans for patients with central nervous system tumors treated with CK at our institution between March 2015 and May 2018 were analyzed. The CK treatment planning system MultiPlan was used for planning. SRS/SRT plans were stratified into 6 groups by tumor size (Group I [0-1 cm3], II [1.0-3.0 cm3], III [3.0-5.0 cm3], IV [5.0-10.0 cm3], V [10.0-15.0 cm3], and VI [15.0-40.0 cm3]). Ideal and minimally acceptable DGIs were determined for each size group. To evaluate the effect of target shape on DGI criteria, the plans were divided into 4 target shape groups: (1) homogeneous shape (circular), (2) adjacent to radiosensitive organs at risk (adjacent), (3) irregularly shaped (irregular), and (4) multiple target plans (multilesion). The mean for each target size group was defined as the ideal DGI. Minimally acceptable DGI criteria are specified to reject the lowest 10% of cases. RESULTS: The minimal acceptable DGIs were 83 (Group I), 72 (II), 65 (III), 58 (IV), 52 (V), and 35 (VI). The ideal DGI is designated to evaluate SRS/SRT plans for homogeneous circular lesions, whereas minimal DGI is chosen to assess the plans for irregular, adjacent to organs at risk, and multilesions. SRS/SRT plans with higher DGI values are correlated with lower irradiated normal tissue volumes. CONCLUSIONS: This study provides a table of DGIs for brain SRS/SRT treatments as a tool for assessing the quality of intracranial SRS/SRT plans. DGI guidelines support SRS/SRT planning that results in lower risk of radionecrosis.


Assuntos
Neoplasias Encefálicas/radioterapia , Órgãos em Risco/efeitos da radiação , Radiocirurgia/métodos , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Conformacional/métodos , Neoplasias Encefálicas/diagnóstico por imagem , Guias como Assunto , Humanos , Órgãos em Risco/diagnóstico por imagem , Tolerância a Radiação , Radiocirurgia/efeitos adversos , Dosagem Radioterapêutica , Radioterapia Conformacional/efeitos adversos , Espalhamento de Radiação
11.
Cancer Radiother ; 24(1): 1-10, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31992516

RESUMO

PURPOSE: The purpose of this prospective dosimetric study was to assess the dose distribution regarding the brain areas implied in cognitive functions using two approaches: volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT). PATIENTS AND METHODS: Thirty-seven patients were treated using a dual-arc VMAT approach for supratentorial glioblastoma between 2016 and 2018. The total dose of 60Gy in 30 daily fractions was administered to the planning target volume (PTV). The brain structures that play an important role in cognitive physiology, such as the hippocampi, corpus callosum, cerebellum, subventricular zones (SVZ), were delineated. For each patient, a new treatment plan in HT was determined by a second medical physicist in a blindly fashion according to the same dose constraints and priorities. Statistical analyses were performed using the Wilcoxon-signed rank test. RESULTS: Conformity indexes remained similar with both techniques. The mean values were 0.96 (0.19-1.00) for VMAT and 0.98 (range, 0.84-1.00) for HT, respectively (P=0.73). Significant D50% reductions were observed with VMAT compared to HT: 14.6Gy (3.8-28.0) versus 17.4Gy (12.1-25.0) for the normal brain (P=0.014); 32.5Gy (10.3-60.0) versus 35.6Gy (17.1-58.0) for the corpus callosum (P=0.038); 8.1Gy (0.4-34.0) versus 12.8Gy (0.8-27.0) for the cerebellum (P<0.001), respectively. CONCLUSION: The VMAT approach seemed to improve the sparing of the key brain areas implied in cognitive functions without jeopardizing PTV coverage.


Assuntos
Neoplasias Encefálicas/radioterapia , Encéfalo/efeitos da radiação , Glioblastoma/radioterapia , Dosagem Radioterapêutica , Radioterapia de Intensidade Modulada , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tratamentos com Preservação do Órgão , Órgãos em Risco , Estudos Prospectivos
12.
Cancer Radiother ; 24(1): 38-43, 2020 Feb.
Artigo em Francês | MEDLINE | ID: mdl-31992518

RESUMO

PURPOSE: The aim of this work is to evaluate the anatomical changes of the glandular structures during the NPC IMRT and to study their dosimetric impacts. PATIENTS AND METHODS: Twenty patients receiving IMRT for NPC were included. For each patient, a second dosimetric CT was performed at a dose of 38Gy, which was fused with the initial planning dosimetric CT. We calculated the volume percent change, the positional and dosimetric variation between the 2 scanners for the glandular structures (parotid, submaxillary, thyroid and pituitary). RESULTS: We observed a decrease in the volume of right and left parotids (-27.9% and -27.54%). It was correlated with the initial dose planned at its level. For the sub maxillary glands, the decrease was -36.1% on the right and -27.28% on the left. The value of reduction of the thyroid gland was -18.01%. A medial supra-millimeter migration of 2 and 1.15mm was found for right and left parotid glands respectively, correlated with GTV N reduction volume. We found a significant increase in mean doses for the parotid glands. It was 1.8±2.3Gy for the right and 1.5±2.7Gy for the left. For the right sub maxillary gland, the increase was about 0.35±2Gy and 3.79±5.2Gy for the thyroid. CONCLUSION: The modifications observed for glandular structures during NPC IMRT can explain the different toxicities caused by radiation. It seems also that a careful adaptation of the treatment plan should be considered during therapy.


Assuntos
Neoplasias Nasofaríngeas/radioterapia , Órgãos em Risco , Radioterapia de Intensidade Modulada , Carcinoma/diagnóstico por imagem , Carcinoma/radioterapia , Humanos , Neoplasias Nasofaríngeas/diagnóstico por imagem , Glândula Parótida/efeitos da radiação , Hipófise/efeitos da radiação , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Glândula Submandibular/efeitos da radiação , Glândula Tireoide/efeitos da radiação , Tomografia Computadorizada por Raios X
13.
Br J Radiol ; 93(1107): 20190332, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31944824

RESUMO

Proton minibeam therapy (PMBT) is a form of spatially fractionated radiotherapy wherein broad beam radiation is replaced with segmented minibeams-either parallel, planar minibeam arrays generated by a multislit collimator or scanned pencil beams that converge laterally at depth to create a uniform dose layer at the tumor. By doing so, the spatial pattern of entrance dose is considerably modified while still maintaining tumor dose and efficacy. Recent studies using computational modeling, phantom experiments, in vitro and in vivo preclinical models, and early clinical feasibility assessments suggest that unique physical and biological attributes of PMBT can be exploited for future clinical benefit. We outline some of the guiding principle of PMBT in this concise overview of this emerging area of preclinical and clinical research inquiry.


Assuntos
Criatividade , Neoplasias/radioterapia , Terapia com Prótons/métodos , Absorção de Radiação , Algoritmos , Fracionamento da Dose de Radiação , Estudos de Viabilidade , Humanos , Método de Monte Carlo , Tratamentos com Preservação do Órgão , Órgãos em Risco , Radiobiologia , Radiometria
14.
Int J Radiat Oncol Biol Phys ; 106(4): 743-753, 2020 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-31953061

RESUMO

PURPOSE: The purpose of our study was to provide a guide for identification and contouring of upper abdominal organs-at-risk (OARs) in the setting of online magnetic resonance imaging (MRI)-guided radiation treatment planning and delivery. METHODS AND MATERIALS: After a needs assessment survey, it was determined that an upper abdominal MRI-based atlas of normal OARs would be of benefit to radiation oncologists and radiation therapists. An anonymized diagnostic 1.5T MRI from a patient with typical upper abdominal anatomy was used for atlas development. Two MRI sequences were selected for contouring, a T1-weighted gadoxetic acid contrast-enhanced MRI acquired in the hepatobiliary phase and axial fast imaging with balanced steady-state precession. Two additional clinical MRI sequences from commercial online MRI-guided radiation therapy systems were selected for contouring and were included in the final atlas. Contours from each data set were completed and reviewed by radiation oncologists, along with a radiologist who specializes in upper abdominal imaging, to generate a consensus upper abdominal MRI-based OAR atlas. RESULTS: A normal OAR atlas was developed, including recommendations for contouring. The atlas and contouring guidance are described, and high-resolution MRI images and contours are displayed. OARs, such as the bile duct and biliary tree, which may be better seen on MRI than on computed tomography, are highlighted. The full DICOM/DICOM-RT MRI images from both the diagnostic and clinical online MRI-guided radiation therapy systems data sets have been made freely available, for educational purposes, at econtour.org. CONCLUSIONS: This MRI contouring atlas for upper abdominal OARs should provide a useful reference for contouring and education. Its routine use may help to improve uniformity in contouring in radiation oncology planning and OAR dose calculation. Full DICOM/DICOM-RT images are available online and provide a valuable educational resource for upper abdominal MRI-based radiation therapy planning and delivery.


Assuntos
Abdome/diagnóstico por imagem , Abdome/efeitos da radiação , Imagem por Ressonância Magnética , Órgãos em Risco/diagnóstico por imagem , Órgãos em Risco/efeitos da radiação , Radioterapia (Especialidade)/normas , Humanos , Planejamento da Radioterapia Assistida por Computador , Padrões de Referência
15.
Br J Radiol ; 93(1107): 20190845, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31904261

RESUMO

OBJECTIVES: The purpose of this study is to investigate the dosimetric effect and clinical impact of delivering a focal radiotherapy boost dose to multiparametric MRI (mp-MRI)-defined dominant intraprostatic lesions (DILs) in prostate cancer using proton therapy. METHODS: We retrospectively investigated 36 patients with pre-treatment mp-MRI and CT images who were treated using pencil beam scanning (PBS) proton radiation therapy to the whole prostate. DILs were contoured on co-registered mp-MRIs. Simultaneous integrated boost (SIB) plans using intensity-modulated proton therapy (IMPT) were created based on conventional whole-prostate-irradiation for each patient and optimized with additional DIL coverage goals and urethral constraints. DIL dose coverage and organ-at-risk (OAR) sparing were compared between conventional and SIB plans. Tumor control probability (TCP) and normal tissue complication probability (NTCP) were estimated to evaluate the clinical impact of the SIB plans. RESULTS: Optimized SIB plans significantly escalated the dose to DILs while meeting OAR constraints. SIB plans were able to achieve 125, 150 and 175% of prescription dose coverage in 74, 54 and 17% of 36 patients, respectively. This was modeled to result in an increase in DIL TCP by 7.3-13.3% depending on α/ß and DIL risk level. CONCLUSION: The proposed mp-MRI-guided DIL boost using proton radiation therapy is feasible without violating OAR constraints and demonstrates a potential clinical benefit by improving DIL TCP. This retrospective study suggested the use of IMPT-based DIL SIB may represent a strategy to improve tumor control. ADVANCES IN KNOWLEDGE: This study investigated the planning of mp-MRI-guided DIL boost in prostate proton radiation therapy and estimated its clinical impact with respect to TCP and NTCP.


Assuntos
Imageamento por Ressonância Magnética Multiparamétrica , Neoplasias da Próstata/diagnóstico por imagem , Neoplasias da Próstata/radioterapia , Terapia com Prótons/métodos , Reirradiação/métodos , Idoso , Idoso de 80 Anos ou mais , Fracionamento da Dose de Radiação , Humanos , Masculino , Pessoa de Meia-Idade , Tratamentos com Preservação do Órgão/métodos , Órgãos em Risco/diagnóstico por imagem , Órgãos em Risco/efeitos da radiação , Próstata/diagnóstico por imagem , Próstata/efeitos da radiação , Neoplasias da Próstata/patologia , Lesões por Radiação/prevenção & controle , Dosagem Radioterapêutica , Estudos Retrospectivos , Tomografia Computadorizada por Raios X , Uretra/diagnóstico por imagem
16.
Br J Radiol ; 93(1107): 20190955, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31971818

RESUMO

Patients with squamous cell carcinoma of the oropharynx are generally treated with (chemo) radiation. Patients with oropharyngeal cancer have better survival than patients with squamous cell carcinoma of other head and neck subsites, especially when related to human papillomavirus. However, radiotherapy results in a substantial percentage of survivors suffering from significant treatment-related side-effects. Late radiation-induced side-effects are mostly irreversible and may even be progressive, and particularly xerostomia and dysphagia affect health-related quality of life. As the risk of radiation-induced side-effects highly depends on dose to healthy normal tissues, prevention of radiation-induced xerostomia and dysphagia and subsequent improvement of health-relatedquality of life can be obtained by applying proton therapy, which offers the opportunity to reduce the dose to both the salivary glands and anatomic structures involved in swallowing.This review describes the results of the first cohort studies demonstrating that proton therapy results in lower dose levels in multiple organs at risk, which translates into reduced acute toxicity (i.e. up to 3 months after radiotherapy), while preserving tumour control. Next to reducing mucositis, tube feeding, xerostomia and distortion of the sense of taste, protons can improve general well-being by decreasing fatigue and nausea. Proton therapy results in decreased rates of tube feeding dependency and severe weight loss up to 1 year after radiotherapy, and may decrease the risk of radionecrosis of the mandible. Also, the model-based approach for selecting patients for proton therapy in the Netherlands is described in this review and future perspectives are discussed.


Assuntos
Carcinoma de Células Escamosas/radioterapia , Transtornos de Deglutição/prevenção & controle , Neoplasias Orofaríngeas/radioterapia , Terapia com Prótons/métodos , Lesões por Radiação/prevenção & controle , Xerostomia/prevenção & controle , Idoso , Transtornos de Deglutição/etiologia , Nutrição Enteral/estatística & dados numéricos , Humanos , Mandíbula/efeitos da radiação , Pessoa de Meia-Idade , Países Baixos , Órgãos em Risco/efeitos da radiação , Qualidade de Vida , Glândulas Salivares/efeitos da radiação , Xerostomia/etiologia
17.
Br J Radiol ; 93(1108): 20190792, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31939310

RESUMO

OBJECTIVES: To evaluate the feasibility and optimal restricted angle of the complete-directional-complete block (CDCB) technique in helical tomotherapy (HT) by including regional nodal irradiation (RNI) with the internal mammary node (IMN) in left-sided breast cancer. METHODS: Ten left-sided breast cancer patients treated with 50 Gy in 25 fractions were compared with five-field intensity-modulated radiation therapy (5F-IMRT) and six types of HT plans. In the HT plans, complete block (CB), organ-based directional block (OBDB) and CDCB with different restricted angles were used. RESULTS: The conformity index (CI) between the CDCB0,10,15,20 and 5F-IMRT groups was similar. Compared to CB, OBDB and 5F-IMRT, CDCB20 resulted in a decreased ipsilateral mean lung dose. The low-dose region (V5) of the ipsilateral lung in OBDB (84.0%) was the highest among all techniques (p < 0.001). The mean dose of the heart in CB was significantly reduced (by 11.5-22.4%) compared with other techniques. The V30 of the heart in CDCB20 (1.9%) was significantly lower than that of CB, OBDB and 5F-IMRT. Compared to the mean dose of the left anterior descending (LAD) artery of 5F-IMRT (27.0 Gy), CDCB0, CDCB10, CDCB15, CDCB20 and OBDB reduced the mean dose effectively by 31.7%, 38.3%, 39.6%, 42.0 and 56.2%, respectively. Considering the parameters of the organs-at-risk (OARs), CDCB10,15,20 had higher expectative values than the other techniques (p = 0.01). CONCLUSIONS: HT with the CDCB technique is feasible for treating left-sided breast cancer patients. The CDCB10-20 techniques not only achieved similar planning target volume coverage, homogeneity and dose conformity but also allowed better sparing of the heart and bilateral lungs. ADVANCES IN KNOWLEDGE: For left-sided breast cancer patients whose RNI field includes the IMN, heart avoidance is an important issue. The CDCB technique achieved good PTV coverage, homogeneity and dose conformity and allowed better sparing of the mean dose of the lung, the LAD artery, and the heart and reduced the V30 of the heart.


Assuntos
Coração/efeitos da radiação , Pulmão/efeitos da radiação , Irradiação Linfática/métodos , Órgãos em Risco/efeitos da radiação , Lesões por Radiação/prevenção & controle , Radioterapia de Intensidade Modulada/métodos , Neoplasias Unilaterais da Mama/radioterapia , Fracionamento da Dose de Radiação , Estudos de Viabilidade , Feminino , Humanos , Órgãos em Risco/diagnóstico por imagem , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias Unilaterais da Mama/diagnóstico por imagem
18.
Br J Radiol ; 93(1108): 20190577, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31944823

RESUMO

OBJECTIVE: It has been established that survival and toxicity outcomes in some cancer types could be influenced by haemoglobin (Hb) levels. This study aims to determine if pre-treatment Hb is associated with late toxicity or survival outcomes in prostate cancer. METHODS: Data from one Phase III randomised controlled trial and one single arm translational trial were analysed. Patients had localized prostate cancer and received ≥70 Gy radiotherapy and neo-adjuvant androgen deprivation between 1997 and 2013. RESULTS: 302 males were included. Median follow-up was 6.8 years for toxicity and 10.3 years for survival outcomes. Patients with Hb below the reference range were more likely to experience Grade 2-3 late gastrointestinal toxicity than patients with Hb within the range (p = 0.050). Neither late genitourinary toxicity, erectile function toxicity, prostate-specific antigen relapse free survival nor overall survival of patients were statistically significantly different between groups. CONCLUSION: Anaemia in prostate cancer is found in the minority of patients and is usually mild. Prostate cancer patients undergoing radiotherapy with low Hb were more likely to experience Grade 2-3 late gastrointestinal toxicity. ADVANCES IN KNOWLEDGE: This study is one of the first in the published literature to investigate the role of Hb in prostate cancer toxicity and survival. We have found an association between Hb below the reference range and late GI toxicity. Consideration should be given to further investigating patients with iron deficiency anaemia to guide management options and outrule underlying GI pathology before proceeding with radiotherapy treatment.


Assuntos
Anemia/sangue , Hemoglobina A/análise , Órgãos em Risco/efeitos da radiação , Neoplasias da Próstata/mortalidade , Neoplasias da Próstata/radioterapia , Idoso , Idoso de 80 Anos ou mais , Antagonistas de Androgênios/uso terapêutico , Trato Gastrointestinal/efeitos da radiação , Hormônio Liberador de Gonadotropina/agonistas , Humanos , Masculino , Pessoa de Meia-Idade , Terapia Neoadjuvante , Ereção Peniana , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/sangue , Neoplasias da Próstata/tratamento farmacológico , Valores de Referência , Estudos Retrospectivos
19.
Br J Radiol ; 93(1108): 20190789, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31971829

RESUMO

OBJECTIVE: Prostate stereotactic ablative radiotherapy (SABR) delivers large doses using a fast dose rate. This amplifies the effect geometric uncertainties have on normal tissue dose. The aim of this study was to determine whether the treatment dose-volume histogram (DVH) agrees with the planned dose to organs at risk (OAR). METHODS: 41 low-intermediate risk prostate cancer patients were treated with SABR using a linac based technique. Dose prescribed was 35 Gy in five fractions delivered on alternate days, planned using volumetric modulated arc therapy (VMAT) with 10X flattening filter free (FFF). On treatment, prostate was matched to fiducial markers on cone beam CT (CBCT). OAR were retrospectively delineated on 205 pre-treatment CBCT images. Daily CBCT contours were overlaid on the planning CT for dosimetric analysis. Verification plan used to evaluate the daily DVH for each structure. The daily doses received by OAR were recorded using the D%. RESULTS: The median rectum and bladder volumes at planning were 67.1 cm3 (interquartile range 56.4-78.2) and 164.4 cm3 (interquartile range 120.3-213.4) respectively. There was no statistically significant difference in median rectal volume at each of the five treatment scans compared to the planning scan (p = 0.99). This was also the case for median bladder volume (p = 0.79). The median dose received by rectum and bladder at each fraction was higher than planned, at the majority of dose levels. For rectum the increase ranged from 0.78-1.64Gy and for bladder 0.14-1.07Gy. The percentage of patients failing for rectum D35% < 18 Gy (p = 0.016), D10% < 28 Gy (p = 0.004), D5% < 32 Gy (p = 0.0001), D1% < 35 Gy (p = 0.0001) and bladder D1% < 35 Gy (p = 0.001) at treatment were all statistically significant. CONCLUSION: In this cohort of prostate SABR patients, we estimate the OAR treatment DVH was higher than planned. This was due to rectal and bladder organ variation. ADVANCES IN KNOWLEDGE: OAR variation in prostate SABR using a FFF technique, may cause the treatment DVH to be higher than planned.


Assuntos
Órgãos em Risco/efeitos da radiação , Neoplasias da Próstata/radioterapia , Radiocirurgia/métodos , Radioterapia de Intensidade Modulada/métodos , Reto/efeitos da radiação , Bexiga Urinária/efeitos da radiação , Idoso , Fracionamento da Dose de Radiação , Humanos , Masculino , Próstata , Radiometria , Planejamento da Radioterapia Assistida por Computador/métodos , Reto/diagnóstico por imagem , Estudos Retrospectivos , Bexiga Urinária/diagnóstico por imagem
20.
Int J Radiat Oncol Biol Phys ; 106(2): 440-448, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31928642

RESUMO

PURPOSE: Recent studies suggest that ultrahigh-dose-rate, "FLASH," electron radiation therapy (RT) decreases normal tissue damage while maintaining tumor response compared with conventional dose rate RT. Here, we describe a novel RT apparatus that delivers FLASH proton RT (PRT) using double scattered protons with computed tomography guidance and provide the first report of proton FLASH RT-mediated normal tissue radioprotection. METHODS AND MATERIALS: Absolute dose was measured at multiple depths in solid water and validated against an absolute integral charge measurement using a Faraday cup. Real-time dose rate was obtained using a NaI detector to measure prompt gamma rays. The effect of FLASH versus standard dose rate PRT on tumors and normal tissues was measured using pancreatic flank tumors (MH641905) derived from the KPC autochthonous PanCa model in syngeneic C57BL/6J mice with analysis of fibrosis and stem cell repopulation in small intestine after abdominal irradiation. RESULTS: The double scattering and collimation apparatus was dosimetrically validated with dose rates of 78 ± 9 Gy per second and 0.9 ± 0.08 Gy per second for the FLASH and standard PRT. Whole abdominal FLASH PRT at 15 Gy significantly reduced the loss of proliferating cells in intestinal crypts compared with standard PRT. Studies with local intestinal irradiation at 18 Gy revealed a reduction to near baseline levels of intestinal fibrosis for FLASH-PRT compared with standard PRT. Despite this difference, FLASH-PRT did not demonstrate tumor radioprotection in MH641905 pancreatic cancer flank tumors after 12 or 18 Gy irradiation. CONCLUSIONS: We have designed and dosimetrically validated a FLASH-PRT system with accurate control of beam flux on a millisecond time scale and online monitoring of the integral and dose delivery time structure. Using this system, we found that FLASH-PRT decreases acute cell loss and late fibrosis after whole-abdomen and focal intestinal RT, whereas tumor growth inhibition is preserved between the 2 modalities.


Assuntos
Órgãos em Risco/efeitos da radiação , Terapia com Prótons/instrumentação , Lesões Experimentais por Radiação/prevenção & controle , Proteção Radiológica/instrumentação , Radioterapia Guiada por Imagem/instrumentação , Abdome/efeitos da radiação , Animais , Proliferação de Células/efeitos da radiação , Desenho de Equipamento/métodos , Estudos de Viabilidade , Feminino , Fibrose , Raios gama , Intestino Delgado/patologia , Intestino Delgado/efeitos da radiação , Camundongos , Camundongos Endogâmicos C57BL , Tratamentos com Preservação do Órgão/instrumentação , Tratamentos com Preservação do Órgão/métodos , Órgãos em Risco/patologia , Neoplasias Pancreáticas/radioterapia , Terapia com Prótons/métodos , Proteção Radiológica/métodos , Radiometria/métodos , Radioterapia Guiada por Imagem/métodos , Espalhamento de Radiação , Células-Tronco/efeitos da radiação , Tomografia Computadorizada por Raios X
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