Respiratory motion management for external radiotherapy treatment.

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).

Estimating 3-dimensional liver motion using deep learning and 2-dimensional ultrasound images.

PURPOSE: The main purpose of this study is to construct a system to track the tumor position during radiofrequency ablation (RFA) treatment. Existing tumor tracking systems are designed to track a tumor in a two-dimensional (2D) ultrasound (US) image. As a result, the three-dimensional (3D) motion of the organs cannot be accommodated and the ablation area may be lost. In this study, we propose a method for estimating the 3D movement of the liver as a preliminary system for tumor tracking. Additionally, in current 3D movement estimation systems, the motion of different structures during RFA could reduce the tumor visibility in US images. Therefore, we also aim to improve the estimation of the 3D movement of the liver by improving the liver segmentation. We propose a novel approach to estimate the relative 6-axial movement (x, y, z, roll, pitch, and yaw) between the liver and the US probe in order to estimate the overall movement of the liver. METHOD: We used a convolutional neural network (CNN) to estimate the 3D displacement from two-dimensional US images. In addition, to improve the accuracy of the estimation, we introduced a segmentation map of the liver region as the input for the regression network. Specifically, we improved the extraction accuracy of the liver region by using a bi-directional convolutional LSTM U-Net with densely connected convolutions (BCDU-Net). RESULTS: By using BCDU-Net, the accuracy of the segmentation was dramatically improved, and as a result, the accuracy of the movement estimation was also improved. The mean absolute error for the out-of-plane direction was 0.0645 mm/frame. CONCLUSION: The experimental results show the effectiveness of our novel method to identify the movement of the liver by BCDU-Net and CNN. Precise segmentation of the liver by BCDU-Net also contributes to enhancing the performance of the liver movement estimation.

respiTrack: Patient-specific real-time respiratory tumor motion prediction using magnetic tracking.

PURPOSE: An intraoperative real-time respiratory tumor motion prediction system with magnetic tracking technology is presented. Based on respiratory movements in different body regions, it provides patient and single/multiple tumor-specific prediction that facilitates the guiding of treatments. METHODS: A custom-built phantom patient model replicates the respiratory cycles similar to a human body, while the custom-built sensor holder concept is applied on the patient's surface to find optimum sensor number and their best possible placement locations to use in real-time surgical navigation and motion prediction of internal tumors. Automatic marker localization applied to patient's 4D-CT data, feature selection and Gaussian process regression algorithms enable off-line prediction in the preoperative phase to increase the accuracy of real-time prediction. RESULTS: Two evaluation methods with three different registration patterns (at fully/half inhaled and fully exhaled positions) were used quantitatively at all internal target positions in phantom: The statical method evaluates the accuracy by stopping simulated breathing and dynamic with continued breathing patterns. The overall root mean square error (RMS) for both methods was between [Formula: see text] and [Formula: see text]. The overall registration RMS error was [Formula: see text]. The best prediction errors were observed by registrations at half inhaled positions with minimum [Formula: see text], maximum [Formula: see text]. The resulting accuracy satisfies most radiotherapy treatments or surgeries, e.g., for lung, liver, prostate and spine. CONCLUSION: The built system is proposed to predict respiratory motions of internal structures in the body while the patient is breathing freely during treatment. The custom-built sensor holders are compatible with magnetic tracking. Our presented approach reduces known technological and human limitations of commonly used methods for physicians and patients.

A statistical weighted sparse-based local lung motion modelling approach for model-driven lung biopsy.

PURPOSE: Lung biopsy is currently the most effective procedure for cancer diagnosis. However, respiration-induced location uncertainty presents a challenge in precise lung biopsy. To reduce the medical image requirements for motion modelling, in this study, local lung motion information in the region of interest (ROI) is extracted from whole chest computed tomography (CT) and CT-fluoroscopy scans to predict the motion of potentially cancerous tissue and important vessels during the model-driven lung biopsy process. METHODS: The motion prior of the ROI was generated via a sparse linear combination of a subset of motion information from a respiratory motion repository, and a weighted sparse-based statistical model was used to preserve the local respiratory motion details. We also employed a motion prior-based registration method to improve the motion estimation accuracy in the ROI and designed adaptive variable coefficients to interactively weigh the relative influence of the prior knowledge and image intensity information during the registration process. RESULTS: The proposed method was applied to ten test subjects for the estimation of the respiratory motion field. The quantitative analysis resulted in a mean target registration error of 1.5 (0.8) mm and an average symmetric surface distance of 1.4 (0.6) mm. CONCLUSIONS: The proposed method shows remarkable advantages over traditional methods in preserving local motion details and reducing the estimation error in the ROI. These results also provide a benchmark for lung respiratory motion modelling in the literature.

Investigation of dosimetric impact of organ motion in static and dynamic conditions for three stereotactic ablative body radiotherapy techniques: 3D conformal radiotherapy, intensity modulated radiation therapy, and volumetric modulated arc therapy by using presage 3D dosimeters.

AIM: To investigate the use of PRESAGE 3D dosimeters to quantify the dosimetric variation between the static and dynamic conditions of three stereotactic ablative body radiotherapy techniques. MATERIALS AND METHODS: An in-house custom-designed thorax dynamic phantom was designed to simulate the tumor motion in two directions (i.e., superior/inferior (Z-axis) and anterior/posterior (Y-axis)). The PRESAGE dosimeter was attached to the moving arm of the phantom and irradiated in two scenarios (static and dynamic) using three stereotactic ablative body radiotherapy (SABR) techniques: 3D conformal radiotherapy (3D CRT), intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT). RESULTS: The highest differences in the mean volume measurements between the two conditions were noticed in IMRT (0.14 cm3) and 3D CRT (0.13 cm3). The mean volume measurements of the VMAT showed the lowest difference between the static and dynamic conditions of 0.10 cm3. The gamma analysis for 3%, 3-mm criterion showed passing rates of < 1 for 3D CRT, IMRT, and VMAT. CONCLUSION: This study quantify the dosimetric variations which are caused by the tumor motion in lung cases. In the SABR of the lung for QA purposes, this could help in identifying the prescription dose coverage due to tumor movement and correlate with the planned dose using 3D dosimeters like PRESAGE.

Effect of continuous positive airway pressure administration during lung stereotactic ablative radiotherapy: a comparative planning study.

PURPOSE: By increasing lung volume and decreasing respiration-induced tumour motion amplitude, administration of continuous positive airway pressure (CPAP) during stereotactic ablative radiotherapy (SABR) could allow for better sparing of the lungs and heart. In this study, we evaluated the effect of CPAP on lung volume, tumour motion amplitude and baseline shift, as well as the dosimetric impact of the strategy. METHODS: Twenty patients with lung tumours referred for SABR underwent 4D-computed tomography (CT) scans with and without CPAP (CPAP/noCPAP) at two timepoints (T0/T1). First, CPAP and noCPAP scans were compared for lung volume, tumour motion amplitude, and baseline shift. Next, CPAP and noCPAP treatment plans were computed and compared for lung dose parameters (mean lung dose (MLD), lung volume receiving 20 Gy (V20Gy), 13 Gy (V13Gy), and 5 Gy (V5Gy)) and mean heart dose (MHD). RESULTS: On average, CPAP increased lung volume by 8.0% (p < 0.001) and 6.3% (p < 0.001) at T0 and T1, respectively, but did not change tumour motion amplitude or baseline shift. As a result, CPAP administration led to an absolute decrease in MLD, lung V20Gy, V13Gy and V5Gy of 0.1 Gy (p = 0.1), 0.4% (p = 0.03), 0.5% (p = 0.04) and 0.5% (p = 0.2), respectively, while having no significant influence on MHD. CONCLUSIONS: In patients referred for SABR for lung tumours, CPAP increased lung volume without modifying tumour motion or baseline shift. As a result, CPAP allowed for a slight decrease in radiation dose to the lungs, which is unlikely to be clinically significant.

Under-reported dosimetry errors due to interplay effects during VMAT dose delivery in extreme hypofractionated stereotactic radiotherapy.

BACKGROUND AND PURPOSE: Radiotherapy of extracranial metastases changed from normofractioned 3D CRT to extreme hypofractionated stereotactic treatment using VMAT beam techniques. Random interaction between tumour motion and dynamically changing beam parameters might result in underdosage of the CTV even for an appropriately dimensioned ITV (interplay effect). This study presents a clinical scenario of extreme hypofractionated stereotactic treatment and analyses the impact of interplay effects on CTV dose coverage. METHODS: For a thoracic/abdominal phantom with an integrated high-resolution detector array placed on a 4D motion platform, dual-arc treatment plans with homogenous target coverage were created using a common VMAT technique and delivered in a single fraction. CTV underdosage through interplay effects was investigated by comparing dose measurements with and without tumour motion during plan delivery. RESULTS: Our study agrees with previous works that pointed out insignificant interplay effects on target coverage for very regular tumour motion patterns like simple sinusoidal motion. However, we identified and illustrated scenarios that are likely to result in a clinically relevant CTV underdosage. For tumour motion with abnormal variability, target coverage quantified by the CTV area receiving more than 98% of the prescribed dose decreased to 78% compared to 100% at static dose measurement. CONCLUSION: This study is further proof of considerable influence of interplay effects on VMAT dose delivery in stereotactic radiotherapy. For selected conditions of an exemplary scenario, interplay effects and related motion-induced target underdosage primarily occurred in tumour motion pattern with increased motion variability and VMAT plan delivery using complex MLC dose modulation.

Comparison of diaphragmatic mobility between COPD patients with and without thoracic hyperkyphosis: a cross-sectional study / Comparação da mobilidade diafragmática em pacientes com DPOC com e sem hipercifose torácica: um estudo transversal

ABSTRACT Objective: To compare diaphragmatic mobility, lung function, and respiratory muscle strength between COPD patients with and without thoracic hyperkyphosis; to determine the relationship of thoracic kyphosis angle with diaphragmatic mobility, lung function, and respiratory muscle strength in COPD patients; and to compare diaphragmatic mobility and thoracic kyphosis between male and female patients with COPD. Methods: Participants underwent anthropometry, spirometry, thoracic kyphosis measurement, and evaluation of diaphragmatic mobility. Results: A total of 34 patients with COPD participated in the study. Diaphragmatic mobility was significantly lower in the group of COPD patients with thoracic hyperkyphosis than in that of those without it (p = 0.002). There were no statistically significant differences between the two groups of COPD patients regarding lung function or respiratory muscle strength variables. There was a significant negative correlation between thoracic kyphosis angle and diaphragmatic mobility (r = −0.47; p = 0.005). In the sample as a whole, there were statistically significant differences between males and females regarding body weight (p = 0.011), height (p < 0.001), and thoracic kyphosis angle (p = 0.036); however, there were no significant differences in diaphragmatic mobility between males and females (p = 0.210). Conclusions: Diaphragmatic mobility is lower in COPD patients with thoracic hyperkyphosis than in those without it. There is a negative correlation between thoracic kyphosis angle and diaphragmatic mobility. In comparison with male patients with COPD, female patients with COPD have a significantly increased thoracic kyphosis angle.

RESUMO Objetivo: Comparar a mobilidade diafragmática, a função pulmonar e a força muscular respiratória em pacientes que apresentam DPOC com e sem hipercifose torácica; verificar a relação do ângulo da curvatura torácica com a mobilidade diafragmática, variáveis da função pulmonar e de força muscular respiratória dos pacientes com DPOC; e comparar a mobilidade diafragmática e a cifose torácica entre os gêneros nesses pacientes. Métodos: Foram realizadas as seguintes avaliações: antropometria, espirometria, mensuração do ângulo da curvatura torácica e mobilidade diafragmática. Resultados: Participaram do estudo 34 pacientes com DPOC. No grupo de pacientes com DPOC e hipercifose torácica, a mobilidade diafragmática foi estatisticamente menor quando comparada à do grupo DPOC sem hipercifose torácica (p = 0,002). Não houve diferenças estatisticamente significantes entre esses grupos em relação a variáveis de função pulmonar e de força muscular respiratória. Houve uma correlação negativa significante entre o ângulo da curvatura torácica e a mobilidade diafragmática (r = −0,47; p = 0,005). Quando comparados homens e mulheres da amostra geral, houve diferenças estatisticamente significantes em relação à massa corpórea (p = 0,011), estatura (p < 0,001) e ângulo da curvatura da cifose torácica (p = 0,036), mas não em relação à mobilidade diafragmática (p = 0,210). Conclusões: Os pacientes com DPOC e hipercifose torácica apresentaram menor mobilidade diafragmática quando comparados com os pacientes com DPOC sem hipercifose torácica. O ângulo da curvatura torácica se correlacionou negativamente com a mobilidade diafragmática. O grupo feminino apresentou um aumento significante no ângulo da curvatura torácica quando comparado ao grupo masculino.

[Research progress on the etiology and treatment of patellofemoral pain syndrome].

Patellofemoral pain syndrome (PFPS) is one of the most common diseases that cause pain in the knee joint. At present, there is no specific diagnostic measure. The diagnosis of patellofemoral pain syndrome may be considered when imaging is performed without cartilage, ligament and soft tissue injuries. The etiology includes abnormalities of the patellar motion caused by various anatomical abnormalities, such as abnormal patellar position, increased Q angle, and excessive valgus foot. Dysfunction of the lower extremity muscles such as the imbalance of the four biceps and the dysfunction of the gluteal muscles also play an important role in the development of patellofemoral pain syndrome. At present, there are many treatments, and the exercises of four biceps exercises and hip abductor exercises are aimed at improving the dynamic stability of patella; The muscle patch and the patellar brace mainly reduce the pressure of the patellofemoral joint by improving the patellar trajectory; Foot orthopedic pads are used primarily in patients with valgus feet. After the conservative treatment is ineffective, the patellar lateral retinaculum can be loosened under arthroscopy. Because the patellofemoral pain syndrome is caused by the combined effects of various etiologies, a variety of treatments are helpful to improve the therapeutic effect.