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(searched for: doi:10.4103/0973-1482.199451)
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, Rania Hashem, Abdullah AlMohamad, Amina Weber, Hanadi Habibullah, Ghassan Abdulmoula, Mohamed G. Mohiuddin, Reem Ujaimi
Published: 25 October 2022
Advances in Radiation Oncology, Volume 8;

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Guoya Dong, Chenglong Zhang, Lei Deng, Yulin Zhu, Jingjing Dai, Liming Song, Ruoyan Meng, , , Yaoqin Xie
Published: 7 March 2022
Physics in Medicine & Biology, Volume 67;

Objective. Four-dimensional cone-beam computed tomography (4D CBCT) has unique advantages in moving target localization, tracking and therapeutic dose accumulation in adaptive radiotherapy. However, the severe fringe artifacts and noise degradation caused by 4D CBCT reconstruction restrict its clinical application. We propose a novel deep unsupervised learning model to generate the high-quality 4D CBCT from the poor-quality 4D CBCT. Approach. The proposed model uses a contrastive loss function to preserve the anatomical structure in the corrected image. To preserve the relationship between the input and output image, we use a multilayer, patch-based method rather than operate on entire images. Furthermore, we draw negatives from within the input 4D CBCT rather than from the rest of the dataset. Main results. The results showed that the streak and motion artifacts were significantly suppressed. The spatial resolution of the pulmonary vessels and microstructure were also improved. To demonstrate the results in the different directions, we make the animation to show the different views of the predicted correction image in the supplementary animation. Significance. The proposed method can be integrated into any 4D CBCT reconstruction method and maybe a practical way to enhance the image quality of the 4D CBCT.
Shuxue Zhao, Xianfa Lu, Jiasen Zou, Zhouying Xu, Siyu Wei, Liping Li, Qingguo Fu
Published: 11 November 2021
Journal of Healthcare Engineering, Volume 2021, pp 1-8;

Objective. To investigate the influence of cold weather on setup errors of patients with chest and pelvic disease in radiotherapy. Methods. The image-guided data of the patients were collected from the Radiotherapy Center of Cancer Hospital Affiliated to Guangxi Medical University from October 2020 to February 2021. During this period, the cold weather days were December 15, 16, and 17, 2020, and January 7 and 8, 2021. For body fixation in radiotherapy, an integrated plate and a thermoplastic mold were employed in 18 patients with chest disease, while an integrated plate and a vacuum pad were applied in 19 patients with pelvic disease. All patients underwent cone beam computed tomography (CBCT) scans in the first five treatments and once a week thereafter. The obtained data were registered to the planning CT image to get the setup errors of the patient in the translational direction including X, Y, and Z axes and rotational direction including RX, RY, and RZ. Then, the Mann–Whitney U test was performed. The expansion boundary values of the chest and pelvis were calculated according to the formula M PTV = 2.5 ∑ + 0.7 δ . Results. A total of 286 eligible results of CBCT scans were collected. There were 138 chest CBCT scans, including 26 taken in cold weather and 112 in usual weather, and 148 pelvic CBCT scans, including 33 taken in cold weather and 115 in usual weather. The X-, Y-, and Z-axis translational setup errors of patients with chest disease in the cold weather group were 0.16 (0.06, 0.32) cm, 0.25 (0.17, 0.52) cm, and 0.35 (0.21, 0.47) cm, respectively, and those in the usual weather group were 0.14 (0.08, 0.29) cm, 0.23 (0.13, 0.37) cm, and 0.18 (0.1, 0.35) cm, respectively. The results indicated that there was a statistical difference in the Z-axis translational error between the cold weather group and the usual weather group (U = 935.5; p = 0.005 < 0.05 ), while there was no statistical difference in the rotational error between the two groups. The external boundary values of X, Y, and Z axes in the cold weather group were 0.57 cm, 0.92 cm, and 0.99 cm, respectively, and those in the usual weather group were 0.57 cm, 0.78 cm, and 0.68 cm, respectively. There was no significant difference in the translational and rotational errors of patients with pelvic disease between the cold weather group and the usual weather group ( p < 0.05 ). The external boundary values of X, Y, and Z axes were 0.63 cm, 0.79 cm, and 0.68 cm in the cold weather group and 0.61 cm, 0.79 cm, and 0.61 cm in the usual weather group, respectively. Conclusion. The setup error of patients undergoing radiotherapy with their bodies fixed by an integrated plate and a thermoplastic mold was greater in cold weather than in usual weather, especially in the ventrodorsal direction.
Xu Li, Lizhen Wang, Zhen Cui, Yukun Li, Pei Liu, Yungang Wang, Jinhong Zhu, Jianmin Zhu, ,
Published: 17 September 2021
Radiation Oncology, Volume 16, pp 1-7;

Purpose/objective(s): The purpose of the study was to assess the uterus motions and bladder volume changes of fractional movements in cervical sites throughout the external beam radiotherapy (EBRT) treatment. Materials/methods: A prospective online MR imaging tracking study was conducted in EBRT 43 patients with at least 4 scans during each treatment (before: ultrasound scan, MRI scan, CBCT scan, after: MRI scan) were included. In order to improve the treatment repeatability, each patient was instructed to empty the bladder and drink 500 ml water 1 h before CT simulation and each treatment. If the ultrasound scan result reached the CT simulation volume of bladder, the treatment began. Bladder was outlined on the T2 weighted axial sequence and CBCT image by the two observers to avoid the influence of contouring. The data of bladder volume and scanning time were accurately recorded. The bladder volumes, filling rates and uterus motion were retrospectively analyzed by MIM software. Results: Inter-fraction variation of the bladder volume was significant (p < 0.0001). Intra-fraction mean increase of the bladder volume was modest (30 cc) but significant (p < 0.001). Both inter- and intra-fraction of the uterus motion were significant. The average time between the pre-and post-fraction MRI scans was 27.82 ± 7.12 min (range 10–55 min) for IMRT plans and 24.14 ± 5.86 min (range7-38 min) for VMAT plan. Average bladder filling rate was 3.43 ml/min. The bladder filling rate did not change significantly with the course of treatment, but the bladder was more intolerant. Conclusion: This is the most detailed assessment of intra-fraction and inter-fraction motion during EBRT for cervical cancer. Finally, this study will inform appropriate treatment margins for online adaptive radiotherapy. We suggest that at least one image scan is needed before the EBRT. The portable US scanner provides a quick but unreliable measurement of the bladder volume. There is a significant statistical difference between the results of ultrasonic scanning and that of image scanning.
, L.H. Barraclough, C.L. Nelder, S.J. Otter, A.J. Stewart
Published: 9 July 2021
Clinical Oncology, Volume 33, pp 579-590;

The complex and varied motion of the cervix–uterus target during external beam radiotherapy (EBRT) underscores the clinical benefits afforded by adaptive radiotherapy (ART) techniques. These gains have already been realised in the implementation of image-guided adaptive brachytherapy, where adapting to anatomy at each fraction has seen improvements in clinical outcomes and a reduction in treatment toxicity. With regards to EBRT, multiple adaptive strategies have been implemented, including a personalised internal target volume, offline replanning and a plan of the day approach. With technological advances, there is now the ability for real-time online ART using both magnetic resonance imaging and computed tomography-guided imaging. However, multiple challenges remain in the widespread dissemination of ART. This review investigates the ART strategies and their clinical implementation in EBRT delivery for cervical cancer.
Journal of Medical Imaging and Radiation Sciences, Volume 52, pp 238-247;

Objectives To assess setup reproducibility of low kneefix with feetfix (LKF-FF) system and its operator-reported convenience by reference to low dual leg positioner (LDLP), among patients treated with pelvic radiotherapy. Methods A retrospective controlled trial was carried out at the radiotherapy unit. It included patients who underwent radical radiotherapy to the pelvis using VMAT, and who benefitted from LDLP (N = 30) or LKF-FF (N = 30) immobilization system. Average absolute shifts (AAS) and total vector errors (TVE) were computed and compared between the two systems, using translational (lateral, longitudinal and vertical) and rotational (X, Y and Z planes) directions. Accuracy rates were computed on pooled data including 1529 VMAT images, 819 in LDLP and 710 in LKF-FF groups, using different cutoffs. Radiotherapists' subjective assessment of the device's ease of setup, handling, cleaning, and storage, and patient comfort was carried out comparatively between the two devices. Results No statistically significant difference was observed between the two systems in systematic settings, while LKF-FF outperformed LDLP in random settings; notably in vertical translation and X and Z rotational shifts. Analysis of TVEs showed significant decrease in rotational TVE in LKF-FF group (mean=1.38° versus 2.38, p = 0.003) by reference to LDLP, respectively; however, both systems had comparable translational TVE (p = 0.590). In pooled analysis, LKF-FF enabled an overall increase in setup accuracy rates in rotational directions by up to 15% and 19% at ±1° and ±2° accuracy levels, respectively (p<0.05). Subjective assessments showed that the two immobilization systems were comparable regarding all investigated dimensions; however, the overall radiotherapists' preference leaned toward LDLP. Conclusion The newly implemented LKF-FF system outperformed LDLP in terms of setup reproducibility, notably in rotational directions, where it enhanced setup accuracy rates by up to 19%. Long-term use of LKF-FF may improve the users' satisfaction. Résumé Objectifs Évaluer la reproductibilité de la configuration du système Low Kneefix avec Feetfix (LKF-FF) et sa commodité déclarée par l'opérateur en se référant au positionneur bas à deux jambes (LDLP), chez les patients traités par radiothérapie pelvienne Méthodes Un essai contrôlé rétrospectif-prospectif a été réalisé à l'unité de radiothérapie. Il comprenait des patients ayant subi une radiothérapie radicale du bassin par VMAT, et qui bénéficiaient d'un système d'immobilisation LDLP (N = 30) ou LKF-FF (N = 30). Les décalages absolus moyens (AAS) et les erreurs vectorielles totales (EVT) ont été calculés et comparés entre les deux systèmes, en respectant les directions translationnelle (latérale, longitudinale et verticale) et rotationnelle (plans X, Y et Z). Les taux de précision ont été calculés sur des données regroupées comprenant 1529 images VMAT, 819 dans LDLP et 710 dans des groupes LKF-FF, en utilisant différents seuils. L'évaluation subjective par le radiothérapeute de la facilité d'installation, de manipulation, de nettoyage et de stockage et du confort du patient a été effectuée comparativement entre les deux appareils. Résultats Aucune différence statistiquement significative n'a été observée entre les deux systèmes dans des contextes systématiques, tandis que le LKF-FF a surpassé le LDLP dans des contextes aléatoires, notamment en translation verticale et en décalages de rotation X et Z. L'analyse des EVT a montré une diminution significative de la EVT rotationnelle dans le groupe LKF-FF (moyenne = 1,38 ° contre 2,38, p = 0,003) par référence au LDLP, respectivement; cependant, les deux systèmes avaient une EVT traductionnelle comparable (p = 0,590). Dans l'analyse groupée, LKF-FF a permis une augmentation globale des taux de précision de configuration dans les directions de rotation jusqu'à 15% et 19% à des niveaux de précision de ± 1 ° et ± 2 °, respectivement (p <0,05). Des évaluations subjectives ont montré que les deux systèmes d'immobilisation étaient comparables en ce qui concerne toutes les dimensions étudiées; cependant, la préférence générale des radiothérapeutes penchait vers le LDLP. Conclusion Le système LKF-FF nouvellement mis en œuvre a surpassé le LDLP en termes de reproductibilité de la configuration, notamment dans les sens de rotation, où il a amélioré les taux de précision de configuration jusqu'à 19%. L'utilisation à long terme de LKF-FF peut améliorer la satisfaction des utilisateurs.
Y Mo, J Liu, Q Li, J Ma, H Zhang
Published: 25 February 2021
Journal of Southern Medical University, Volume 41, pp 243-249

To propose a motion compensation reconstruction method based on robust principal component analysis (RPCA) to reduce the influence of streak artifacts on accurate estimation of interphase motion deformation fields. We propose a RPCA motion compensation reconstruction algorithm to improve the estimation of motion deformation fields based on the traditional MC-FDK algorithm. RPCA was used to decompose the cone-beam computed tomography (CBCT) images into low-rank and sparse components, and the motion deformation fields between different phase images were then estimated using Horn and Schunck optical flow method from the low-rank images to reduce the influence of striping artifacts on the accuracy of estimation of interphase motion deformation fields. The performance of the algorithm was evaluated using simulation data and real data. The simulation phantom data was obtained by back-projection of 4D-CT images acquired from Philips 16-slice spiral CT using MATLAB software programming according to the scanning geometry of Varian Edge accelerator. The real patient data were obtained using the Elekta Synergy system of CBCT scanning system with half-fan mode CB projection data from lung cancer patients. Compared with images reconstructed using the traditional MC-FDK algorithm, the reconstructed image using the proposed method had clearer tissue boundaries with reduced motion artifact was reduced. The results of phantom data reconstruction showed that compared with the MC- FDK algorithm, the proposed algorithms resulted in improvements of PSNR by 25.4% and SSIM by 7.6%; compared with the FDK algorithm, PSNR was improved by 37.9% and SSIM by 17.6%. The proposed algorithm can achieve accurate estimation of inter-phase motion deformation fields and improve the quality of the reconstructed CBCT images.
, Lars U. Fokdal, Marianne S. Assenholt, Nina B.K. Jensen, Jørgen B.B. Petersen, Lars Nyvang, , Jacob C. Lindegaard, Kari Tanderup
Published: 1 July 2019
Physics and Imaging in Radiation Oncology, Volume 11, pp 9-15;

Background and purpose Image-Guidance decreases set-up uncertainties, which may allow for Planning Target Volume (PTV) margins reduction. This study evaluates the robustness of the elective lymph node target coverage to translational and rotational set-up errors in combination with shrinking PTV margins and determines the gain for the Organs At Risk (OARs). Material and methods Ten cervix cancer patients who underwent external beam radiotherapy with 45 Gy/25Fx were analysed. Daily Image-Guidance was based on bony registration of Cone Beam CT (CBCT) to planning CT (pCT) and daily couch correction (translation and yaw). On each pCT, four Volumetric Modulated Arc Therapy dose-plans were generated with PTV margins of 0, 3, 5 and 8 mm. The elective clinical target volume (CTV-E) was propagated from daily CBCTs to the pCT to evaluate daily CTV-E dose. Additional systematic translational isocenter shifts of 2 mm were simulated. D98% (dose received by 98% of the volume of interest) and D99.9% were extracted from each CTV-E for all dose-plans and scenarios. Total dose was accumulated by Dose-Volume Histogram addition. The dosimetric impact of PTV margin reduction on the OARs was evaluated through V30Gy (volume included within the 30 Gy isodose), V40Gy and body V43Gy. Results When decreasing the PTV margin from 5 to 0 mm, bowel V30Gy was decreased by 13% (from 247 cm3 to 214 cm3), body V43Gy by 19% (from 1462 cm3 to 1188 cm3) and PTV by 39% (from 1416 to 870 cm3). The dosimetric impact of combined systematic shifts and residual rotations on the elective target with a 0 mm PTV margin was a decrease of D98% (mean ± SD) from 44.1 Gy ± 0.4 Gy to 43.7 Gy ± 0.8 Gy and a minimum of 42.4 Gy. Conclusion PTV margin reduction from 5 to 0 mm induced significant OARs dosimetric gains while elective target coverage remained robust to positioning uncertainties.
Meiling Chen, Yi Huang, Wufan Chen, Xin Chen, Hua Zhang
Published: 28 February 2019
by 10.12122
Journal of Southern Medical University, Volume 39, pp 201-206;

Four-dimensional cone beam CT (4D-CBCT) imaging can provide accurate location information of real-time breathing for imaging-guided radiotherapy. How to improve the accuracy of 4D-CBCT reconstruction image is a hot topic in current studies. PICCS algorithm performs remarkably in all 4D-CBCT reconstruction algorithms based on CS theory. The improved PICCS algorithm proposed in this paper improves the prior image on the basis of the traditional PICCS algorithm. According to the location information of each phase, the corresponding prior image is constructed, which completely eliminates the motion blur of the reconstructed image caused by the mismatch of the projection data. Meanwhile, the data fidelity model of the proposed method is consistent with the traditional PICCS algorithm. The experimental results showed that the reconstructed image using the proposed method had a clearer organization boundary compared with that of images reconstructed using the traditional PICCS algorithm. This proposed method significantly reduced the motion artifact and improved the image resolution.
, Shashank Bansal, Apurba Kumar Kalita, Moirangthem Nara Singh, Rubu Sunku, Partha Pratim Medhi, Ghritashee Bora
Published: 1 January 2019
Journal of Medical Physics, Volume 44, pp 65-67;

Context: In advanced radiotherapy techniques such as three-dimensional conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT), geometrical uncertainties are very crucial as they may lead to under dosing of tumor and over dosing of the nearby critical structures and hence, it is important to determine planning target volume (PTV) margins which are specific for every center. Aims: The aim of this study is to determine adequate clinical target volume (CTV) to PTV margins specific to our radiotherapy center. Settings and Design: To calculate CTV to PTV margins for rectal cancer patients in prone position using kV cone beam CBCT data sets. Materials and Methods: With the Patient immobilized in prone position using thermoplastic mask, a CT simulation was done and a comprehensive 3DCRT plan was generated. Daily kV CBCT was done to check the patient setup error. Daily setup errors were recorded and evaluated retrospectively. Results: CTV-PTV margin calculated for pelvis in the prone position was calculated using van Herk Formula and were found to be 0.5, 1.8, 0.7 cm in the lateral, longitudinal, and vertical directions, respectively. Conclusions: Image guidance is an effective method to evaluate patient setup errors. Good quality immobilization devices and stringent patient setup policies can help to reduce PTV margins further.
Iván Ríos, Ilse Vásquez, Elsa Cuervo, Óscar Garzón, Johnny Burbano
Reports of Practical Oncology and Radiotherapy, Volume 23, pp 517-527;

The contribution of Image-guided Radiotherapy (IGRT) to modern radiotherapy is undeniable, being the way to bring into daily practice the dosimetric benefits of Intensity-Modulated Radiotherapy (IMRT). Organ and target motion is constant and unpredictable at the pelvis, thus posing a challenge to the safe execution of IMRT. There are potential benefits of IMRT in the radical treatment of cervical cancer patients, both in terms of dose escalation and decrease of toxicity. But it is essential to find IGRT solutions to control the aspects that can lead to geographic miss targeting or organs at risk (OAR) overdose. This review seeks to describe the problems and possible solutions in the clinical implementation of IMRT/IGRT protocols to treat intact cervical cancer patients.
, U. Schick, O. Pradier, S. Espenel, R. De Crevoisier, C. Chargari
Published: 17 August 2018
Cancer/radiothérapie, Volume 22, pp 608-616;

La radiothérapie conformationnelle avec modulation d’intensité (RCMI) permet une épargne significative en termes de dose aux organes à risque chez les patientes prises en charge pour un cancer gynécologique. Compte tenu des forts gradients de dose autour du volume cible prévisionnel, les variations anatomiques interne des organes pendant le traitement peuvent cependant entraîner un « sous-dosage » du volume cible anatomoclinique et un surdosage des organes à risque. Il est donc important de prendre en compte le mouvement et les déformations des organes pelviens et d’étudier les solutions potentielles apportées par la radiothérapie guidée par l’image. Une revue de la littérature a été effectuée en utilisant les bases de données suivantes : Medline, Embase, la bibliothèque Cochrane, Web of Science, Cinahl et Pubmed. Des stratégies de recherche appropriées aux bases de données ont été élaborées en fonction des termes relatifs à « uterine neoplasms, image-guided radiotherapy, adaptative radiotherapy, organ motion and target volume ». Ces études montrent que le mouvement utérin est principalement influencé par la réplétion vésicale, le mouvement cervical et de la voûte vaginale par la réplétion rectale. Les marges entre le volume cible anatomoclinique et le volume cible prévisionnel basées sur la population sont importantes, entraînant une inclusion inutile des organes à risque dans le volume cible prévisionnel, réduisant les avantages de la RCMI. Cependant, le mouvement des organes pelviens étant spécifique à chaque patiente, des marges de volume cible prévisionnel individualisées et des stratégies de radiothérapie adaptative semblent pouvoir assurer une couverture adéquate du volume cible tout en augmentant l’épargne des organes à risque. Dans cette étude, nous faisons une revue des différentes techniques de radiothérapie guidée par l’image utilisées et les perspectives concernant la radiothérapie adaptative.
Avinash H. Udayashankar, Shibina Noorjahan, Nirmala Srikantia, K. Ravindra Babu,
Reports of Practical Oncology and Radiotherapy, Volume 23, pp 233-241;

To identify the most reproducible technique of patient positioning and immobilization during pelvic radiotherapy. Radiotherapy plays an important role in the treatment of pelvic malignancies. Errors in positioning of patient are an integral component of treatment. The present study compares two methods of immobilization with no immobilization with an aim of identifying the most reproducible method. 65 consecutive patients receiving pelvic external beam radiotherapy were retrospectively analyzed. 30, 21 and 14 patients were treated with no-immobilization with a leg separator, whole body vacuum bag cushion (VBC) and six point aquaplast immobilization system, respectively. The systematic error, random error and the planning target volume (PTV) margins were calculated for all the three techniques and statistically analyzed. The systematic errors were the highest in the VBC and random errors were the highest in the aquaplast group. Both systematic and random errors were the lowest in patients treated with no-immobilization. 3D Systematic error (mm, mean ± 1SD) was 4.31 ± 3.84, 3.39 ± 1.71 and 2.42 ± 0.97 for VBC, aquaplast and no-immobilization, respectively. 3D random error (mm, 1SD) was 2.96, 3.59 and 1.39 for VBC, aquaplast and no-immobilization, respectively. The differences were statistically significant between all the three groups. The calculated PTV margins were the smallest for the no-immobilization technique with 4.56, 4.69 and 4.59 mm, respectively, in x, y and z axes, respectively. Among the three techniques, no-immobilization technique with leg separator was the most reproducible technique with the smallest PTV margins. For obvious reasons, this technique is the least time consuming and most economically viable in developing countries.
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