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1.
Int J Comput Assist Radiol Surg ; 19(8): 1477-1487, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38809319

RESUMO

PURPOSE: This work presents the implementation of an RGB-D camera as a surrogate signal for liver respiratory-induced motion estimation. This study aims to validate the feasibility of RGB-D cameras as a surrogate in a human subject experiment and to compare the performance of different correspondence models. METHODS: The proposed approach uses an RGB-D camera to compute an abdominal surface reconstruction and estimate the liver respiratory-induced motion. Two sets of validation experiments were conducted, first, using a robotic liver phantom and, secondly, performing a clinical study with human subjects. In the clinical study, three correspondence models were created changing the conditions of the learning-based model. RESULTS: The motion model for the robotic liver phantom displayed an error below 3 mm with a coefficient of determination above 90% for the different directions of motion. The clinical study presented errors of 4.5, 2.5, and 2.9 mm for the three different motion models with a coefficient of determination above 80% for all three cases. CONCLUSION: RGB-D cameras are a promising method to accurately estimate the liver respiratory-induced motion. The internal motion can be estimated in a non-contact, noninvasive and flexible approach. Additionally, three training conditions for the correspondence model are studied to potentially mitigate intra- and inter-fraction motion.


Assuntos
Fígado , Imagens de Fantasmas , Respiração , Robótica , Humanos , Fígado/diagnóstico por imagem , Robótica/instrumentação , Robótica/métodos , Movimentos dos Órgãos , Abdome
2.
Clin Oncol (R Coll Radiol) ; 36(7): 420-429, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38649309

RESUMO

AIMS: Delineation variations and organ motion produce difficult-to-quantify uncertainties in planned radiation doses to targets and organs at risk. Similar to manual contouring, most automatic segmentation tools generate single delineations per structure; however, this does not indicate the range of clinically acceptable delineations. This study develops a method to generate a range of automatic cardiac structure segmentations, incorporating motion and delineation uncertainty, and evaluates the dosimetric impact in lung cancer. MATERIALS AND METHODS: Eighteen cardiac structures were delineated using a locally developed auto-segmentation tool. It was applied to lung cancer planning CTs for 27 curative (planned dose ≥50 Gy) cases, and delineation variations were estimated by using ten mapping-atlases to provide separate substructure segmentations. Motion-related cardiac segmentation variations were estimated by auto-contouring structures on ten respiratory phases for 9/27 cases that had 4D-planning CTs. Dose volume histograms (DVHs) incorporating these variations were generated for comparison. RESULTS: Variations in mean doses (Dmean), defined as the range in values across ten feasible auto-segmentations, were calculated for each cardiac substructure. Over the study cohort the median variations for delineation uncertainty and motion were 2.20-11.09 Gy and 0.72-4.06 Gy, respectively. As relative values, variations in Dmean were between 18.7%-65.3% and 7.8%-32.5% for delineation uncertainty and motion, respectively. Doses vary depending on the individual planned dose distribution, not simply on segmentation differences, with larger dose variations to cardiac structures lying within areas of steep dose gradient. CONCLUSION: Radiotherapy dose uncertainties from delineation variations and respiratory-related heart motion were quantified using a cardiac substructure automatic segmentation tool. This predicts the 'dose range' where doses to structures are most likely to fall, rather than single DVH curves. This enables consideration of these uncertainties in cardiotoxicity research and for future plan optimisation. The tool was designed for cardiac structures, but similar methods are potentially applicable to other OARs.


Assuntos
Coração , Neoplasias Pulmonares , Órgãos em Risco , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador , Humanos , Neoplasias Pulmonares/radioterapia , Coração/efeitos da radiação , Planejamento da Radioterapia Assistida por Computador/métodos , Incerteza , Órgãos em Risco/efeitos da radiação , Tomografia Computadorizada Quadridimensional/métodos , Movimentos dos Órgãos , Radiometria/métodos
3.
Strahlenther Onkol ; 200(5): 418-424, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38488899

RESUMO

PURPOSE: This study aimed to assess the margin for the planning target volume (PTV) using the Van Herk formula. We then validated the proposed margin by real-time magnetic resonance imaging (MRI). METHODS: An analysis of cone-beam computed tomography (CBCT) data from early glottic cancer patients was performed to evaluate organ motion. Deformed clinical target volumes (CTV) after rigid registration were acquired using the Velocity program (Varian Medical Systems, Palo Alto, CA, USA). Systematic (Σ) and random errors (σ) were evaluated. The margin for the PTV was defined as 2.5 Σ + 0.7 σ according to the Van Herk formula. To validate this margin, we accrued healthy volunteers. Sagittal real-time cine MRI was conducted using the ViewRay system (ViewRay Inc., Oakwood Village, OH, USA). Within the obtained sagittal images, the vocal cord was delineated. The movement of the vocal cord was summed up and considered as the internal target volume (ITV). We then assessed the degree of overlap between the ITV and the PTV (vocal cord plus margins) by calculating the volume overlap ratio, represented as (ITV∩PTV)/ITV. RESULTS: CBCTs of 17 early glottic patients were analyzed. Σ and σ were 0.55 and 0.57 for left-right (LR), 0.70 and 0.60 for anterior-posterior (AP), and 1.84 and 1.04 for superior-inferior (SI), respectively. The calculated margin was 1.8 mm (LR), 2.2 mm (AP), and 5.3 mm (SI). Four healthy volunteers participated for validation. A margin of 3 mm (AP) and 5 mm (SI) was applied to the vocal cord as the PTV. The average volume overlap ratio between ITV and PTV was 0.92 (range 0.85-0.99) without swallowing and 0.77 (range 0.70-0.88) with swallowing. CONCLUSION: By evaluating organ motion by using CBCT, the margin was 1.8 (LR), 2.2 (AP), and 5.3 mm (SI). The margin acquired using CBCT fitted well in real-time cine MRI. Given that swallowing during radiotherapy can result in a substantial displacement, it is crucial to consider strategies aimed at minimizing swallowing and related motion.


Assuntos
Tomografia Computadorizada de Feixe Cônico , Glote , Neoplasias Laríngeas , Imagem Cinética por Ressonância Magnética , Humanos , Tomografia Computadorizada de Feixe Cônico/métodos , Imagem Cinética por Ressonância Magnética/métodos , Glote/diagnóstico por imagem , Masculino , Neoplasias Laríngeas/diagnóstico por imagem , Neoplasias Laríngeas/radioterapia , Pessoa de Meia-Idade , Feminino , Adulto , Idoso , Movimentos dos Órgãos , Sistemas Computacionais , Planejamento da Radioterapia Assistida por Computador/métodos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
4.
J Appl Clin Med Phys ; 25(5): e14333, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38493500

RESUMO

PURPOSE: Left ventricle (LV) regional myocardial displacement due to cardiac motion was assessed using cardiovascular magnetic resonance (CMR) cine images to establish region-specific margins for cardiac radioablation treatments. METHODS: CMR breath-hold cine images and LV myocardial tissue contour points were analyzed for 200 subjects, including controls (n = 50) and heart failure (HF) patients with preserved ejection fraction (HFpEF, n = 50), mid-range ejection fraction (HFmrEF, n = 50), and reduced ejection fraction (HFrEF, n = 50). Contour points were divided into segments according to the 17-segment model. For each patient, contour point displacements were determined for the long-axis (all 17 segments) and short-axis (segments 1-12) directions. Mean overall, tangential (longitudinal or circumferential), and normal (radial) displacements were calculated for the 17 segments and for each segment level. RESULTS: The greatest overall motion was observed in the control group-long axis: 4.5 ± 1.2 mm (segment 13 [apical anterior] epicardium) to 13.8 ± 3.0 mm (segment 6 [basal anterolateral] endocardium), short axis: 4.3 ± 0.8 mm (segment 9 [mid inferoseptal] epicardium) to 11.5 ± 2.3 mm (segment 1 [basal anterior] endocardium). HF patients exhibited lesser motion, with the smallest overall displacements observed in the HFrEF group-long axis: 4.3 ± 1.7 mm (segment 13 [apical anterior] epicardium) to 10.6 ± 3.4 mm (segment 6 [basal anterolateral] endocardium), short axis: 3.9 ± 1.3 mm (segment 8 [mid anteroseptal] epicardium) to 7.4 ± 2.8 mm (segment 1 [basal anterior] endocardium). CONCLUSIONS: This analysis provides an estimate of epicardial and endocardial displacement for the 17 segments of the LV for patients with normal and impaired LV function. This reference data can be used to establish treatment planning margin guidelines for cardiac radioablation. Smaller margins may be used for patients with higher degree of impaired heart function, depending on the LV segment.


Assuntos
Procedimentos Cirúrgicos Cardíacos , Ventrículos do Coração , Miocárdio , Movimentos dos Órgãos , Ablação por Radiofrequência , Taquicardia Ventricular , Ventrículos do Coração/diagnóstico por imagem , Ventrículos do Coração/cirurgia , Imageamento por Ressonância Magnética , Taquicardia Ventricular/cirurgia , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Idoso
5.
Int J Comput Assist Radiol Surg ; 19(1): 1-9, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37249749

RESUMO

PURPOSE: Accuracy of image-guided liver surgery is challenged by deformation of the liver during the procedure. This study aims at improving navigation accuracy by using intraoperative deep learning segmentation and nonrigid registration of hepatic vasculature from ultrasound (US) images to compensate for changes in liver position and deformation. METHODS: This was a single-center prospective study of patients with liver metastases from any origin. Electromagnetic tracking was used to follow US and liver movement. A preoperative 3D model of the liver, including liver lesions, and hepatic and portal vasculature, was registered with the intraoperative organ position. Hepatic vasculature was segmented using a reduced 3D U-Net and registered to preoperative imaging after initial alignment followed by nonrigid registration. Accuracy was assessed as Euclidean distance between the tumor center imaged in the intraoperative US and the registered preoperative image. RESULTS: Median target registration error (TRE) after initial alignment was 11.6 mm in 25 procedures and improved to 6.9 mm after nonrigid registration (p = 0.0076). The number of TREs above 10 mm halved from 16 to 8 after nonrigid registration. In 9 cases, registration was performed twice after failure of the first attempt. The first registration cycle was completed in median 11 min (8:00-18:45 min) and a second in 5 min (2:30-10:20 min). CONCLUSION: This novel registration workflow using automatic vascular detection and nonrigid registration allows to accurately localize liver lesions. Further automation in the workflow is required in initial alignment and classification accuracy.


Assuntos
Aprendizado Profundo , Neoplasias Hepáticas , Humanos , Movimentos dos Órgãos , Estudos Prospectivos , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Hepáticas/cirurgia , Imageamento Tridimensional/métodos
6.
Surg Endosc ; 38(3): 1379-1389, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38148403

RESUMO

BACKGROUND: Image-guidance promises to make complex situations in liver interventions safer. Clinical success is limited by intraoperative organ motion due to ventilation and surgical manipulation. The aim was to assess influence of different ventilatory and operative states on liver motion in an experimental model. METHODS: Liver motion due to ventilation (expiration, middle, and full inspiration) and operative state (native, laparotomy, and pneumoperitoneum) was assessed in a live porcine model (n = 10). Computed tomography (CT)-scans were taken for each pig for each possible combination of factors. Liver motion was measured by the vectors between predefined landmarks along the hepatic vein tree between CT scans after image segmentation. RESULTS: Liver position changed significantly with ventilation. Peripheral regions of the liver showed significantly higher motion (maximal Euclidean motion 17.9 ± 2.7 mm) than central regions (maximal Euclidean motion 12.6 ± 2.1 mm, p < 0.001) across all operative states. The total average motion measured 11.6 ± 0.7 mm (p < 0.001). Between the operative states, the position of the liver changed the most from native state to pneumoperitoneum (14.6 ± 0.9 mm, p < 0.001). From native state to laparotomy comparatively, the displacement averaged 9.8 ± 1.2 mm (p < 0.001). With pneumoperitoneum, the breath-dependent liver motion was significantly reduced when compared to other modalities. Liver motion due to ventilation was 7.7 ± 0.6 mm during pneumoperitoneum, 13.9 ± 1.1 mm with laparotomy, and 13.5 ± 1.4 mm in the native state (p < 0.001 in all cases). CONCLUSIONS: Ventilation and application of pneumoperitoneum caused significant changes in liver position. Liver motion was reduced but clearly measurable during pneumoperitoneum. Intraoperative guidance/navigation systems should therefore account for ventilation and intraoperative changes of liver position and peripheral deformation.


Assuntos
Movimentos dos Órgãos , Pneumoperitônio , Suínos , Animais , Pneumoperitônio/diagnóstico por imagem , Pneumoperitônio/etiologia , Laparotomia , Fígado/diagnóstico por imagem , Fígado/cirurgia , Respiração
7.
Phys Med Biol ; 68(24)2023 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-37918022

RESUMO

Objective. Carbon ion radiotherapy is a promising radiation technique for malignancies like pancreatic cancer. However, organs' motion imposes challenges for achieving homogeneous dose delivery. In this study, an anthropomorphicPancreasPhantom forIon-beamTherapy (PPIeT) was developed to simulate breathing and gastrointestinal motion during radiotherapy.Approach. The developed phantom contains a pancreas, two kidneys, a duodenum, a spine and a spinal cord. The shell of the organs was 3D printed and filled with agarose-based mixtures. Hounsfield Units (HU) of PPIeTs' organs were measured by CT. The pancreas motion amplitude in cranial-caudal (CC) direction was evaluated from patients' 4D CT data. Motions within the obtained range were simulated and analyzed in PPIeT using MRI. Additionally, GI motion was mimicked by changing the volume of the duodenum and quantified by MRI. A patient-like treatment plan was calculated for carbon ions, and the phantom was irradiated in a static and moving condition. Dose measurements in the organs were performed using an ionization chamber and dosimetric films.Main results. PPIeT presented tissue equivalent HU and reproducible breathing-induced CC displacements of the pancreas between (3.98 ± 0.36) mm and a maximum of (18.19 ± 0.44) mm. The observed maximum change in distance of (14.28 ± 0.12) mm between pancreas and duodenum was consistent with findings in patients. Carbon ion irradiation revealed homogenous coverage of the virtual tumor at the pancreas in static condition with a 1% deviation from the treatment plan. Instead, the dose delivery during motion with the maximum amplitude yielded an underdosage of 21% at the target and an increased uncertainty by two orders of magnitude.Significance. A dedicated phantom was designed and developed for breathing motion assessment of dose deposition during carbon ion radiotherapy. PPIeT is a unique tool for dose verification in the pancreas and its organs at risk during end-to-end tests.


Assuntos
Radioterapia com Íons Pesados , Neoplasias Pancreáticas , Humanos , Movimentos dos Órgãos , Planejamento da Radioterapia Assistida por Computador/métodos , Movimento (Física) , Neoplasias Pancreáticas/diagnóstico por imagem , Neoplasias Pancreáticas/radioterapia , Carbono , Imagens de Fantasmas , Dosagem Radioterapêutica
8.
Radiat Oncol ; 18(1): 119, 2023 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-37443017

RESUMO

BACKGROUND: For accurate thoracic and abdominal radiotherapy, inter- and intrafractional geometrical uncertainties need to be considered to enable accurate margin sizes. We aim to quantify interfractional diaphragm and abdominal organ position variations, and intrafractional diaphragm motion in a large multicenter cohort of pediatric cancer patients (< 18 years). We investigated the correlation of interfractional position variations and intrafractional motion with age, and with general anesthesia (GA). METHODS: In 189 children (mean age 8.1; range 0.4-17.9 years) from six institutes, interfractional position variation of both hemidiaphragms, spleen, liver, left and right kidneys was quantified using a two-step registration. CBCTs were registered to the reference CT relative to the bony anatomy, followed by organ registration. We calculated the group mean, systematic and random errors (standard deviations Σ and σ, respectively) in cranial-caudal (CC), left-right and anterior-posterior directions. Intrafractional right hemidiaphragm motion was quantified using CBCTs on which the breathing amplitude, defined as the difference between end-inspiration and end-expiration peaks, was assessed (N = 79). We investigated correlations with age (Spearman's ρ), and differences in motion between patients treated with and without GA (N = 75; all < 5.5 years). RESULTS: Interfractional group means were largest in CC direction and varied widely between patients, with largest variations in the right hemidiaphragm (range -13.0-17.5 mm). Interfractional group mean of the left kidney showed a borderline significant correlation with age (p = 0.047; ρ = 0.17). Intrafractional right hemidiaphragm motion in patients ≥ 5.5 years (mean 10.3 mm) was significantly larger compared to patients < 5.5 years treated without GA (mean 8.3 mm) (p = 0.02), with smaller Σ and σ values. We found a significant correlation between breathing amplitude and age (p < 0.001; ρ = 0.43). Interfractional right hemidiaphragm position variations were significantly smaller in patients < 5.5 years treated with GA than without GA (p = 0.004), but intrafractional motion showed no significant difference. CONCLUSION: In this large multicenter cohort of children undergoing thoracic and abdominal radiotherapy, we found that interfractional position variation does not depend on age, but the use of GA in patients < 5.5 years showed smaller systematic and random errors. Furthermore, our results showed that breathing amplitude increases with age. Moreover, variations between patients advocate the need for a patient-specific margin approach.


Assuntos
Diafragma , Neoplasias , Humanos , Criança , Pré-Escolar , Movimentos dos Órgãos , Planejamento da Radioterapia Assistida por Computador/métodos , Abdome , Neoplasias/radioterapia , Movimento (Física)
9.
Med Phys ; 50(6): 3299-3310, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37009641

RESUMO

BACKGROUND: Respiratory motion presents a challenge in radiotherapy of thoracic and upper abdominal tumors. Techniques to account for respiratory motion include tracking. Using magnetic resonance imaging (MRI) guided radiotherapy systems, tumors can be tracked continuously. Using conventional linear accelerators, tracking of lung tumors is possible by determining tumor motion on kilo voltage (kV) imaging. But tracking of abdominal tumors with kV imaging is hampered by limited contrast. Therefore, surrogates for the tumor are used. One of the possible surrogates is the diaphragm. However, there is no universal method for establishing the error when using a surrogate and there are particular challenges in establishing such errors during free breathing (FB). Prolonged breath-holding might address these challenges. PURPOSE: The aim of this study was to quantify the error when using the right hemidiaphragm top (RHT) as surrogate for abdominal organ motion during prolonged breath-holds (PBH) for possible application in radiation treatments. METHODS: Fifteen healthy volunteers were trained to perform PBHs in two subsequent MRI sessions (PBH-MRI1 and PBH-MRI2). From each MRI acquisition, we selected seven images (dynamics) to determine organ displacement during PBH by using deformable image registration (DIR). On the first dynamic, the RHT, right and left hemidiaphragm, liver, spleen and right and left kidney were segmented. We used the deformation vector fields (DVF), generated by DIR, to determine the displacement of each organ between two dynamics in inferior-superior (IS), anterior-posterior (AP), left-right (LR) direction and we calculated the 3D vector magnitude (|d|). The displacements of the RHT, both hemidiaphragms and the abdominal organs were compared using a linear fit to determine the correlation (R2 of the fit) and the displacement ratio (DR, slope of the fit) between displacements of the RHT and each organ. We quantified the median difference between the DRs of PBH-MRI1 and PBH-MRI2 for each organ. Additionally, we estimated organ displacement in the second PBH by applying the DR from the first PBH to the displacement of the RHT measured during the second PBH. We compared the estimated organ displacement to the measured organ displacement during the second PBH. The difference between the two values was defined as the estimation error of using the RHT as a surrogate and assuming a constant DR over MRI sessions. RESULTS: The linear relationships were confirmed by the high R2 values of the linear fit between the displacements of the RHT and the abdominal organs (R2 > 0.96) in the IS and AP direction and |d|, and high to moderate correlations in the LR direction (0.93 > R2 > 0.64). The median DR difference between PBH-MRI1 and PBH-MRI2 varied between 0.13 and 0.31 for all organs. The median estimation error of the RHT as a surrogate varied between 0.4 and 0.8 mm/min for all organs. CONCLUSION: The RHT could serve as an accurate surrogate for abdominal organ motion during radiation treatments, for example, in tracking, provided the error of the RHT as motion surrogate is taken into account in the margins. TRIAL REGISTRATION: The study was registered in the Netherlands Trial Register (NL7603).


Assuntos
Neoplasias Abdominais , Neoplasias Pulmonares , Humanos , Diafragma/diagnóstico por imagem , Movimentos dos Órgãos , Movimento (Física) , Imageamento por Ressonância Magnética/métodos , Neoplasias Abdominais/diagnóstico por imagem , Neoplasias Abdominais/radioterapia
10.
Bratisl Lek Listy ; 124(4): 280-284, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36598322

RESUMO

OBJECTIVE: To investigate interfractional motion of the mesorectum and bladder and to assess dosimetric changes using cone-beam computed tomography (CBCT) during neoadjuvant radiotherapy for locally advanced rectal cancer patients. METHODS: Twenty-one patients who underwent volumetric arc therapy with CBCT imaging protocol were retrieved. The mesorectum and bladder were delineated on every CBCT image, and treatment plans were recalculated for all CBCTs. The organ motion was analyzed as a mean shift on the X-Y-Z axes. The volume changes were evaluated using the DICE index. Mann-Whitney U test was used in pairwise comparison analysis and ANOVA was used to compare shifts in each direction. RESULTS: A total of 105 CBCTs were evaluated retrospectively. The movement of the total mesorectum was found to be 1.5 mm, 4 mm, and 5 mm on the X-Y-Z-axes, respectively. In the subgroup analysis, the movement of the 1/3 upper mesorectum on the Y-axis was significantly higher (mean movement 8 mm, p = 0.005). Mean bladder displacements were 2 mm, 4 mm, and 8 mm on the X-Y-Z-axes, respectively. In the D2, D95, and D98 doses, there was no statistically significant change depending on the motion. CONCLUSION: During radiotherapy planning, the mesorectal movement should not be forgotten and PTV margins should be determined accordingly (Tab. 6, Ref. 22). Text in PDF www.elis.sk Keywords: cone-beam computed tomography, rectal cancer, mesorectum, interfractional organ motion, neoadjuvant radiotherapy.


Assuntos
Movimentos dos Órgãos , Neoplasias Retais , Humanos , Terapia Neoadjuvante , Estudos Retrospectivos , Planejamento da Radioterapia Assistida por Computador/métodos , Neoplasias Retais/diagnóstico por imagem , Neoplasias Retais/radioterapia , Tomografia Computadorizada de Feixe Cônico/métodos , Dosagem Radioterapêutica
11.
Radiother Oncol ; 176: 208-214, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36228759

RESUMO

BACKGROUND AND PURPOSE: To investigate the impact of organ motion on hypoxia-guided proton therapy treatments for non-small cell lung cancer (NSCLC) patients. MATERIALS AND METHODS: Hypoxia PET and 4D imaging data of six NSCLC patients were used to simulate hypoxia-guided proton therapy with different motion mitigation strategies including rescanning, breath-hold, respiratory gating and tumour tracking. Motion-induced dose degradation was estimated for treatment plans with dose painting of hypoxic tumour sub-volumes at escalated dose levels. Tumour control probability (TCP) and dosimetry indices were assessed to weigh the clinical benefit of dose escalation and motion mitigation. In addition, the difference in normal tissue complication probability (NTCP) between escalated proton and photon VMAT treatments has been assessed. RESULTS: Motion-induced dose degradation was found for target coverage (CTV V95% up to -4%) and quality of the dose-escalation-by-contour (QRMS up to 6%) as a function of motion amplitude and amount of dose escalation. The TCP benefit coming from dose escalation (+4-13%) outweighs the motion-induced losses (<2%). Significant average NTCP reductions of dose-escalated proton plans were found for lungs (-14%), oesophagus (-10%) and heart (-16%) compared to conventional VMAT plans. The best plan dosimetry was obtained with breath hold and respiratory gating with rescanning. CONCLUSION: NSCLC affected by hypoxia appears to be a prime target for proton therapy which, by dose-escalation, allows to mitigate hypoxia-induced radio-resistance despite the sensitivity to organ motion. Furthermore, substantial reduction in normal tissue toxicity can be expected compared to conventional VMAT. Accessibility and standardization of hypoxia imaging and clinical trials are necessary to confirm these findings in a clinical setting.


Assuntos
Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Terapia com Prótons , Radioterapia de Intensidade Modulada , Humanos , Carcinoma Pulmonar de Células não Pequenas/diagnóstico por imagem , Carcinoma Pulmonar de Células não Pequenas/radioterapia , Hipóxia , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/patologia , Movimentos dos Órgãos , Terapia com Prótons/métodos , Prótons , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos
12.
Nano Lett ; 22(21): 8695-8703, 2022 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-36301734

RESUMO

Mechanical harvesters have attracted tremendous attention as self-powered strain sensors; previous harvesters required high stress to stretch the fiber because of their high Young's modulus and low elasticity. We report on a mechano-electrochemical harvesting (MECH) fiber based on the new buckle structure, which has a low Young's modulus (2 MPa) with high elasticity (up to 100%) in a similar physiological fluid. MECH converts mechanical energy into electrical energy by changing the capacitance due to changing the surface area caused by the microbuckle on the surface. The damage to the cells can be minimized by their softness; the fiber was stitched on the tissue of the pig stomach while maintaining the performance like a suture fiber. Additionally, the fiber successfully operated in an organ-similar system, which is composed of the stomach or bladder of a pig. The fiber has a high potential to be applied in wearable energy sources and self-powered strain sensors.


Assuntos
Movimentos dos Órgãos , Dispositivos Eletrônicos Vestíveis , Animais , Suínos , Elasticidade , Módulo de Elasticidade , Eletricidade
13.
Med Dosim ; 47(3): 264-272, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35618563

RESUMO

Compare the robustness of wide tangents (WT) and volumetric modulated arc therapy (VMAT) using different skin flash approaches in breast and nodal radiotherapy. Ten patients treated with WT using 2-cm flash were replanned with VMAT using no flash (NF), manual 2-cm flash (MF), and robust optimization (RO). Plan robustness was assessed for target coverage and organs at risk (OAR) by recalculating on 5 deformed CT scans (SOM1-5), daily cone beam (CBCT), and by shifting the isocenter 5 mm. VMAT NF gave poor coverage of CTVp with its smallest change of -3.2% for V38Gy on CBCT. VMAT RO plans showed the least variations in target coverage loss compared to WT and VMAT MF which dropped as anatomical swelling increased. CTVp D0.5cc decreased on CBCT and increased most for VMAT MF plans (case max increase +3.3 Gy), whereas VMAT RO plans were relatively stable (case max increase +1.2 Gy). OAR dose changed little with anatomical changes (isocenter shifts more important with medial, posterior, and inferior increasing dose). Nodal coverage was superior for VMAT which led to the WT being less robust for coverage toward both geometric and anatomical uncertainties. All techniques except NF plans gave high levels of coverage under minor uncertainties. VMAT RO was highly robust for target coverage for anatomical changes. Manually editing control points on VMAT plans was time-consuming and less predictable. CBCT anatomical changes were modest resulting in small delivered dose changes. OAR dose changes were small with no significant differences between techniques.


Assuntos
Radioterapia de Intensidade Modulada , Humanos , Movimentos dos Órgãos , Órgãos em Risco , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia de Intensidade Modulada/métodos
14.
Med Phys ; 49(7): 4365-4371, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35635215

RESUMO

BACKGROUND: In magnetic resonance (MR)-guided thermal therapy, respiratory motion can cause a significant temperature error in MR thermometry and reduce the efficiency of the treatment. A respiratory motion simulator is necessary for the development of new MR imaging (MRI) and motion compensation techniques. PURPOSE: The purpose of this study is to develop a low-cost and simple MR-compatible respiratory motion simulator to support proof-of-concept studies of MR monitoring approaches with respiratory-induced abdominal organ motion. METHODS: The phantom motion system integrates pneumatic control via an actuator subsystem located outside the MRI and coupled via plastic tubing to a compressible bag for distention and retraction within the MRI safe motion subsystem and phantom positioned within the MRI scanner. Performance of the respiratory motion simulator was evaluated with a real-time gradient echo MRI pulse sequence. RESULTS: The motion simulator can produce respiratory rates in the range of 8-16 breaths/min. Our experiments showed the consistent periodic motion of the phantom during MRI acquisition in the range of 3.7-9 mm with 16 breaths/min. The operation of the simulator did not cause interference with MRI acquisition. CONCLUSIONS: In this study, we have demonstrated the ability of the motion simulator to generate controlled respiratory motion of a phantom. The low-cost MR-compatible respiratory motion simulator can be easily constructed from off-the-shelf and 3D-printed parts based on open-source 3D models and instructions. This could lower the barriers to the development of new MRI techniques with motion compensation.


Assuntos
Imageamento por Ressonância Magnética , Movimentos dos Órgãos , Imageamento por Ressonância Magnética/métodos , Espectroscopia de Ressonância Magnética , Movimento (Física) , Imagens de Fantasmas
15.
Radiother Oncol ; 173: 134-145, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35640771

RESUMO

For radiotherapy of thoracic and abdominal tumors safety margins are applied to address geometrical uncertainties caused by e.g. set-up errors, organ motion and delineation variability. For pediatric patients no standardized margins are defined. Moreover, studies on these geometrical uncertainties are relatively scarce. Therefore, this systematic review presents an overview of organ motion, applied margin sizes and delineation variability in patients <18 years. A search from January 2000 to March 2021 in Medline, Embase, Web of Science, ClinicalTrials.gov and the International Trials Registry Platform resulted in the inclusion of 117 studies reporting on organ motion, margin sizes and/or delineation variability. Studies were heterogeneous concerning age, tumor types, the use of general anesthesia, imaging modalities; image guidance techniques were reported in 39% of the studies. Inter- and intrafractional motion as reported for different organs was largest in cranio-caudal direction and ranged from -9.1 to 10.0 mm and -4.4 to 19.5 mm, respectively. Motion quantification methodologies differed between studies regarding measures of displacement and definitions of motion direction. Reported CTV-PTV margins varied from 3 to 20 mm for both thoracic and abdominal targets, and for spinal and pelvic from 3to 15 mm and 3 to 10 mm, respectively. Studies reported wide variation in interobserver variability of target volume delineation, which may affect dose distributions to both target volumes and organs at risk. Results of this review indicate possible reduction of margin sizes for children, however, wide variation in organ motion and delineation variability caused by differences in methodologies and outcomes hamper the use of standardized margins.


Assuntos
Movimentos dos Órgãos , Radioterapia Guiada por Imagem , Criança , Fracionamento da Dose de Radiação , Humanos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Radioterapia Guiada por Imagem/métodos
16.
Biomed Phys Eng Express ; 8(2)2022 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-35108695

RESUMO

Introduction.Internal organ motion and deformations may cause dose degradations in proton therapy (PT) that are challenging to resolve using conventional image-guidance strategies. This study aimed to investigate the potential ofrange guidanceusing water-equivalent path length (WEPL) calculations to detect dose degradations occurring in PT.Materials and methods. Proton ranges were estimated using WEPL calculations. Field-specific isodose surfaces in the planning CT (pCT), from robustly optimised five-field proton plans (opposing lateral and three posterior/posterior oblique beams) for locally advanced prostate cancer patients, were used as starting points. WEPLs to each point on the field-specific isodoses in the pCT were calculated. The corresponding range for each point was found in the repeat CTs (rCTs). The spatial agreement between the resulting surfaces in the rCTs (hereafter referred to as iso-WEPLs) and the isodoses re-calculated in rCTs was evaluated for different dose levels and Hausdorff thresholds (2-5 mm). Finally, the sensitivity and specificity of detecting target dose degradation (V95% < 95%) using spatial agreement measures between the iso-WEPLs and isodoses in the pCT was evaluated.Results. The spatial agreement between the iso-WEPLs and isodoses in the rCTs depended on the Hausdorff threshold. The agreement was 65%-88% for a 2 mm threshold, 83%-96% for 3 mm, 90%-99% for 4 mm, and 94%-99% for 5 mm, across all fields and isodose levels. Minor differences were observed between the different isodose levels investigated. Target dose degradations were detected with 82%-100% sensitivity and 75%-80% specificity using a 2 mm Hausdorff threshold for the lateral fields.Conclusion. Iso-WEPLs were comparable to isodoses re-calculated in the rCTs. The proposed strategy could detect target dose degradations occurring in the rCTs and could be an alternative to a fully-fledged dose re-calculation to detect anatomical variations severely influencing the proton range.


Assuntos
Neoplasias da Próstata , Terapia com Prótons , Humanos , Masculino , Movimentos dos Órgãos , Neoplasias da Próstata/radioterapia , Terapia com Prótons/métodos , Prótons , Planejamento da Radioterapia Assistida por Computador/métodos
17.
Phys Med Biol ; 67(4)2022 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-35081516

RESUMO

Purpose. Improvements in image-guided radiotherapy (IGRT) enable accurate and precise treatment of moving tumors in the abdomen while simultaneously sparing healthy tissue. However, the lack of validation tools for newly developed MR-guided radiotherapy hybrid devices such as the MR-Linac is an open issue. This study presents a custom developed abdominal phantom with respiratory organ motion and multimodal imaging contrast to perform end-to-end tests for IGRT treatment planning scenarios.Methods. The abdominal phantom contains deformable and anatomically shaped liver and kidney models made of Ni-DTPA and KCl-doped agarose mixtures that can be reproducibly positioned within the phantom. Organ models are wrapped in foil to avoid ion exchange with the surrounding agarose and to provide stable T1 and T2 relaxation times as well as HU numbers. Breathing motion is realized by a diaphragm connected to an actuator that is hydraulically controlled via a programmable logic controller. With this system, artificial and patient-specific breathing patterns can be carried out. In 1.5 T magnetic resonance imaging (MRI), diaphragm, liver and kidney motion was measured and compared to the breathing motion of a healthy male volunteer for different breathing amplitudes including shallow, normal and deep breathing.Results. The constructed abdominal phantom demonstrated organ-equivalent intensity values in CT as well as in MRI. T1-weighted (T1w) and T2-weighted (T2w) relaxation times for 1.5 T and CT numbers were 552.9 ms, 48.2 ms and 48.8 HU (liver) as well as 950.42 ms, 79 ms and 28.2 HU (kidney), respectively. These values were stable for more than six months. Extracted breathing motion from a healthy volunteer revealed a liver to diaphragm motion ratio (LDMR) of 64.4% and a kidney to diaphragm motion ratio (KDMR) of 30.7%. Well-comparable values were obtained for the phantom (LDMR: 65.5%, KDMR: 27.5%).Conclusions. The abdominal phantom demonstrated anthropomorphic T1 and T2 relaxation times as well as HU numbers and physiological motion pattern in MRI and CT. This allows for wide use in the validation of IGRT including MRgRT.


Assuntos
Movimentos dos Órgãos , Radioterapia Guiada por Imagem , Abdome/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Movimento (Física) , Imagem Multimodal , Imagens de Fantasmas , Sefarose
18.
Clin Oncol (R Coll Radiol) ; 34(3): 189-197, 2022 03.
Artigo em Inglês | MEDLINE | ID: mdl-34736842

RESUMO

AIMS: Uterocervical motions and organ filling during cervical cancer conformal radiotherapy is complex. This prospective, observational study investigated set-up margins (clinical target vo, ume [CTV] to planning target volume [PTV]) for pelvic nodal CTV and internal margin (CTV to internal target volume [ITV]) expansions for uterocervical movements during cervical cancer radiotherapy. MATERIALS AND METHODS: During cervical cancer radiotherapy, a daily kilovoltage, cone-beam computed tomography (CBCT) scan was acquired. Bony anatomy-based rigid co-registration and matching to vessels/pelvic nodal region was carried out to document shifts, errors (systematic and random) and to calculate CTV to PTV margins. Subsequently, soft-tissue matching was carried out at the mid-cervical region and uterine fundus to record shifts, errors and to calculate CTV to ITV margins. RESULTS: In 67 patients, 1380 CBCT scans were analysed. The mean (±standard deviation) couch shifts for CTV pelvic nodal region in all directions were within 4.5-5.3 mm, systematic and random errors 3.0-3.6 mm and set-up margins of within 10 mm (except anterior margin 10.3 mm). For the mid-cervical region, mean shifts were 4.5-5.5 mm, systematic and random errors 2-4 mm amounting to <10 mm internal margins (CTV-ITV for cervix) and for uterine fundus mean (±standard deviation) shifts were larger in the superior direction (12.1 mm) but 4.0-7.5 mm in other directions, systematic and random errors 2-7 mm amounting to anisotropic margins in various directions (10 mm in anterior-posterior and lateral directions, 12-20 mm in superior-inferior directions) (CTV-ITV for uterine fundus). CONCLUSION: Our study suggests anisotropic CTV to ITV and CTV to PTV margins for cervical cancer radiotherapy.


Assuntos
Radioterapia Guiada por Imagem , Neoplasias do Colo do Útero , Colo do Útero/diagnóstico por imagem , Tomografia Computadorizada de Feixe Cônico , Feminino , Humanos , Movimentos dos Órgãos , Estudos Prospectivos , Dosagem Radioterapêutica , Planejamento da Radioterapia Assistida por Computador/métodos , Erros de Configuração em Radioterapia , Radioterapia Guiada por Imagem/métodos , Neoplasias do Colo do Útero/diagnóstico por imagem , Neoplasias do Colo do Útero/radioterapia
19.
Cancer Radiother ; 26(1-2): 50-58, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34953689

RESUMO

We present the update of the recommendations of the French society of oncological radiotherapy on respiratory motion management for external radiotherapy treatment. Since twenty years and the report 62 of ICRU, motion management during the course of radiotherapy treatment has become an increasingly significant concern, particularly with the development of hypofractionated treatments under stereotactic conditions, using reduced safety margins. This article related orders of motion amplitudes for different organs as well as the definition of the margins in radiotherapy. An updated review of the various movement management strategies is presented as well as main technological solutions enabling them to be implemented: when acquiring anatomical data, during planning and when carrying out treatment. Finally, the management of these moving targets, such as it can be carried out in radiotherapy departments, will be detailed for a few concrete examples of localizations (abdominal, thoracic and hepatic).


Assuntos
Neoplasias Abdominais/radioterapia , Suspensão da Respiração , Movimentos dos Órgãos , Respiração , Espirometria/métodos , Neoplasias Torácicas/radioterapia , Neoplasias Abdominais/diagnóstico por imagem , Expiração , França , Humanos , Inalação , Imageamento por Ressonância Magnética , Movimentos dos Órgãos/fisiologia , Aceleradores de Partículas , Radioterapia (Especialidade) , Planejamento da Radioterapia Assistida por Computador , Sociedades Médicas , Neoplasias Torácicas/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos
20.
Cancer Radiother ; 26(1-2): 259-265, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34953706

RESUMO

We present the update of the recommendations of the French society of oncological radiotherapy on radiotherapy of pancreatic tumors. Currently, the use of radiation therapy for patients with pancreatic cancer is subject to discussion. In the adjuvant setting, the standard treatment is six months of chemotherapy with 5-fluorouracile, irinotecan and oxaliplatin. Chemoradiation may improve the survival of patients with incompletely resected tumours (R1). This remains to be confirmed by a prospective trial. Neoadjuvant chemoradiation is a promising treatment especially for patients with borderline resectable tumours. For patients with locally advanced tumours, there is no standard. An induction chemotherapy followed by chemoradiation for non progressive patients reduces the rate of local relapse. Whereas in the first trials of chemoradiation large fields were used, the treated volumes have been reduced to improve tolerance. Tumour movements induced by breathing should be taken in account. Intensity modulated radiation therapy allows a reduction of doses to the organs at risk. Whereas widely used, this technique has poor evidence-based recommendation. Stereotactic body radiation therapy is also being studied, as a neoadjuvant or exclusive treatment.


Assuntos
Neoplasias Pancreáticas/radioterapia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Quimiorradioterapia , Quimioterapia Adjuvante , Fluoruracila/uso terapêutico , França , Humanos , Quimioterapia de Indução/métodos , Irinotecano/uso terapêutico , Terapia Neoadjuvante , Movimentos dos Órgãos , Órgãos em Risco/efeitos da radiação , Oxaliplatina/uso terapêutico , Posicionamento do Paciente , Doses de Radiação , Radioterapia (Especialidade) , Radioterapia de Intensidade Modulada , Respiração
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