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  • 1
    In: Radiation Oncology, Springer Science and Business Media LLC, Vol. 14, No. 1 ( 2019-12)
    Abstract: Accurate and standardized descriptions of organs at risk (OARs) are essential in radiation therapy for treatment planning and evaluation. Traditionally, physicians have contoured patient images manually, which, is time-consuming and subject to inter-observer variability. This study aims to a) investigate whether customized, deep-learning-based auto-segmentation could overcome the limitations of manual contouring and b) compare its performance against a typical, atlas-based auto-segmentation method organ structures in liver cancer. Methods On - contrast computer tomography image sets of 70 liver cancer patients were used, and four OARs (heart, liver, kidney, and stomach) were manually delineated by three experienced physicians as reference structures. Atlas and deep learning auto-segmentations were respectively performed with MIM Maestro 6.5 (MIM Software Inc., Cleveland, OH) and, with a deep convolution neural network (DCNN). The Hausdorff distance (HD) and, dice similarity coefficient (DSC), volume overlap error (VOE), and relative volume difference (RVD) were used to quantitatively evaluate the four different methods in the case of the reference set of the four OAR structures. Results The atlas-based method yielded the following average DSC and standard deviation values (SD) for the heart, liver, right kidney, left kidney, and stomach: 0.92 ± 0.04 (DSC ± SD), 0.93 ± 0.02, 0.86 ± 0.07, 0.85 ± 0.11, and 0.60 ± 0.13 respectively. The deep-learning-based method yielded corresponding values for the OARs of 0.94 ± 0.01, 0.93 ± 0.01, 0.88 ± 0.03, 0.86 ± 0.03, and 0.73 ± 0.09. The segmentation results show that the deep learning framework is superior to the atlas-based framwork except in the case of the liver. Specifically, in the case of the stomach, the DSC, VOE, and RVD showed a maximum difference of 21.67, 25.11, 28.80% respectively. Conclusions In this study, we demonstrated that a deep learning framework could be used more effectively and efficiently compared to atlas-based auto-segmentation for most OARs in human liver cancer. Extended use of the deep-learning-based framework is anticipated for auto-segmentations of other body sites.
    Type of Medium: Online Resource
    ISSN: 1748-717X
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2019
    detail.hit.zdb_id: 2224965-5
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  • 2
    In: Frontiers in Oncology, Frontiers Media SA, Vol. 11 ( 2021-9-14)
    Abstract: To automatically identify optimal beam angles for proton therapy configured with the double-scattering delivery technique, a beam angle optimization method based on a convolutional neural network (BAODS-Net) is proposed. Fifty liver plans were used for training in BAODS-Net. To generate a sequence of input data, 25 rays on the eye view of the beam were determined per angle. Each ray collects nine features, including the normalized Hounsfield unit and the position information of eight structures per 2° of gantry angle. The outputs are a set of beam angle ranking scores ( S beam ) ranging from 0° to 359°, with a step size of 1°. Based on these input and output designs, BAODS-Net consists of eight convolution layers and four fully connected layers. To evaluate the plan qualities of deep-learning, equi-spaced, and clinical plans, we compared the performances of three types of loss functions and performed K -fold cross-validation ( K = 5). For statistical analysis, the volumes V 27Gy and V 30Gy as well as the mean, minimum, and maximum doses were calculated for organs-at-risk by using a paired-samples t -test. As a result, smooth-L1 loss showed the best optimization performance. At the end of the training procedure, the mean squared errors between the reference and predicted S beam were 0.031, 0.011, and 0.004 for L1, L2, and smooth-L1 loss, respectively. In terms of the plan quality, statistically, Plan BAO has no significant difference from Plan Clinic ( P & gt;.05). In our test, a deep-learning based beam angle optimization method for proton double-scattering treatments was developed and verified. Using Eclipse API and BAODS-Net, a plan with clinically acceptable quality was created within 5 min.
    Type of Medium: Online Resource
    ISSN: 2234-943X
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2649216-7
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  • 3
    In: Japanese Journal of Clinical Oncology, Oxford University Press (OUP), Vol. 52, No. 3 ( 2022-03-03), p. 266-273
    Abstract: To propose and evaluate an active method for sparing the small bowel in the treatment field of cervical cancer brachytherapy by prone position procedure. Methods The prone position procedure consists of five steps: making bladder empty, prone-positioning a patient on belly board, making the small bowel move to abdomen, filling the bladder with Foley catheter and finally turning the patient into the supine position. The proposed method was applied for the treatment of seven cervical cancer patients. Its effectiveness was evaluated and a correlation between the patient characteristics and the volumetric dose reduction of small bowel was also investigated. Brachytherapy treatment plans were built before and after the proposed method, and their dose-volume histograms were compared for targets and organs-at-risk. In this comparison, all plans were normalized to satisfy the same D90% for high-risk clinical target volume. Results For the enrolled patients, the average dose of small bowel was significantly reduced from 75.2 ± 4.9 Gy before to 60.2 ± 4.0 Gy after the prone position procedure, while minor dosimetric changes were observed in rectum, sigmoid and bladder. The linear correlation to body mass index, thickness and width of abdominopelvic cavity and bladder volume were 76.2, 69.7, 28.8 and −36.3%, respectively. Conclusions The application of prone position procedure could effectively lower the volumetric dose of the small bowel. The dose reduction in the small bowel had a strong correlation with the patient’s obesity and abdominal thickness. This means the patients for whom the proposed method would be beneficial can be judiciously selected for safe brachytherapy.
    Type of Medium: Online Resource
    ISSN: 1465-3621
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2022
    detail.hit.zdb_id: 1494610-5
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  • 4
    In: Cancers, MDPI AG, Vol. 14, No. 12 ( 2022-06-11), p. 2888-
    Abstract: The feasibility of proton minibeam radiation therapy (pMBRT) using a multislit collimator (MSC) and a scattering device was evaluated for clinical use at a clinical proton therapy facility. We fabricated, through Monte Carlo (MC) simulations, not only an MSC with a high peak-to-valley dose ratio (PVDR) at the entrance of the proton beam, to prevent radiation toxicity, but also a scattering device to modulate the PVDR in depth. The slit width and center-to-center distance of the diverging MSC were 2.5 mm and 5.0 mm at the large end, respectively, and its thickness and available field size were 100 mm and 76 × 77.5 mm2, respectively. Spatially fractionated dose distributions were measured at various depths using radiochromic EBT3 films and also tested on bacterial cells. MC simulation showed that the thicker the MSC, the higher the PVDR at the phantom surface. Dosimetric evaluations showed that lateral dose profiles varied according to the scatterer’s thickness, and the depths satisfying PVDR = 1.1 moved toward the surface as their thickness increased. The response of the bacterial cells to the proton minibeams’ depth was also established, in a manner similar to the dosimetric pattern. Conclusively, these results strongly suggest that pMBRT can be implemented in clinical centers by using MSC and scatterers.
    Type of Medium: Online Resource
    ISSN: 2072-6694
    Language: English
    Publisher: MDPI AG
    Publication Date: 2022
    detail.hit.zdb_id: 2527080-1
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  • 5
    Online Resource
    Online Resource
    Korean Society of Medical Physics ; 2022
    In:  Progress in Medical Physics Vol. 33, No. 4 ( 2022-12-31), p. 80-87
    In: Progress in Medical Physics, Korean Society of Medical Physics, Vol. 33, No. 4 ( 2022-12-31), p. 80-87
    Type of Medium: Online Resource
    ISSN: 2508-4445 , 2508-4453
    Language: English
    Publisher: Korean Society of Medical Physics
    Publication Date: 2022
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  • 6
    Online Resource
    Online Resource
    Korean Society of Medical Physics ; 2022
    In:  Progress in Medical Physics Vol. 33, No. 4 ( 2022-12-31), p. 108-113
    In: Progress in Medical Physics, Korean Society of Medical Physics, Vol. 33, No. 4 ( 2022-12-31), p. 108-113
    Type of Medium: Online Resource
    ISSN: 2508-4445 , 2508-4453
    Language: English
    Publisher: Korean Society of Medical Physics
    Publication Date: 2022
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  • 7
    In: Radiotherapy and Oncology, Elsevier BV, Vol. 120, No. 2 ( 2016-08), p. 327-332
    Type of Medium: Online Resource
    ISSN: 0167-8140
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2016
    detail.hit.zdb_id: 1500707-8
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  • 8
    In: Journal of Applied Clinical Medical Physics, Wiley, Vol. 22, No. 6 ( 2021-06), p. 104-118
    Abstract: The present study verified and evaluated the dosimetric effects of protons scattered from a snout and an aperture in clinical practice, when a range compensator was included. The dose distribution calculated by a treatment planning system (TPS) was compared with the measured dose distribution and the dose distribution calculated by Monte Carlo simulation at several depths. The difference between the measured and calculated results was analyzed using Monte Carlo simulation with filtration of scattering in the snout and aperture. The dependence of the effects of scattered protons on snout size, beam range, and minimum thickness of the range compensator was also investigated using the Monte Carlo simulation. The simulated and measured results showed that the additional dose compared with the results calculated by the TPS at shallow depths was mainly due to protons scattered by the snout and aperture. This additional dose was filtered by the structure of the range compensator so that it was observed under the thin region of the range compensator. The maximum difference was measured at a depth of 16 mm (8.25%), with the difference decreasing with depth. Analysis of protons contributing to the additional dose showed that the contribution of protons scattered from the snout was greater than that of protons scattered from the aperture when a narrow snout was used. In the Monte Carlo simulation, this effect of scattered protons was reduced when wider snouts and longer‐range proton beams were used. This effect was also reduced when thicker range compensator bases were used, even with a narrow snout. This study verified the effect of scattered protons even when a range compensator was included and emphasized the importance of snout‐scattered protons when a narrow snout is used for small fields. It indicated that this additional dose can be reduced by wider snouts, longer range proton beams, and thicker range compensator bases. These results provide a better understanding of the additional dose from scattered protons in clinical practice.
    Type of Medium: Online Resource
    ISSN: 1526-9914 , 1526-9914
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 2010347-5
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  • 9
    In: Journal of Applied Clinical Medical Physics, Wiley, Vol. 21, No. 8 ( 2020-08), p. 191-199
    Abstract: Imaging, breath‐holding/gating, and fixation devices have been developed to minimize setup errors so that the prescribed dose can be exactly delivered to the target volume in radiotherapy. Despite these efforts, additional patient monitoring devices have been installed in the treatment room to view patients’ whole‐body movement. We developed a facial expression recognition system using deep learning with a convolutional neural network (CNN) to predict patients’ advanced movement, enhancing the stability of the radiation treatment by giving warning signs to radiation therapists. Materials and methods Convolutional neural network model and extended Cohn‐Kanade datasets with 447 facial expressions of source images for training were used. Additionally, a user interface that can be used in the treatment control room was developed to monitor real‐time patient's facial expression in the treatment room, and the entire system was constructed by installing a camera in the treatment room. To predict the possibility of patients' sudden movement, we categorized facial expressions into two groups: (a) uncomfortable expressions and (b) comfortable expressions. We assumed that the warning sign about the sudden movement was given when the uncomfortable expression was recognized. Results We have constructed the facial expression monitoring system, and the training and test accuracy were 100% and 85.6%, respectively. In 10 patients, their emotions were recognized based on their comfortable and uncomfortable expressions with 100% detection rate. The detected various emotions were represented by a heatmap and motion prediction accuracy was analyzed for each patient. Conclusion We developed a system that monitors the patient's facial expressions and predicts patient's advanced movement during the treatment. It was confirmed that our patient monitoring system can be complementarily used with the existing monitoring system. This system will help in maintaining the initial setup and improving the accuracy of radiotherapy for the patients using deep learning in radiotherapy.
    Type of Medium: Online Resource
    ISSN: 1526-9914 , 1526-9914
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 2010347-5
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  • 10
    In: Medical Physics, Wiley, Vol. 50, No. 1 ( 2023-01), p. 557-569
    Abstract: A real‐time solar cell based in vivo dosimetry system (SC‐IVD) was developed using a flexible thin film solar cell and scintillating powder. The present study evaluated the clinical feasibility of the SC‐IVD in electron beam therapy. Methods A thin film solar cell was coated with 100 mg of scintillating powder using an optical adhesive to enhance the sensitivity of the SC‐IVD. Calibration factors were obtained by dividing the dose, measured at a reference depth for 6–20 MeV electron beam energy, by the signal obtained using the SC‐IVD. Dosimetric characteristics of SC‐IVDs containing variable quantities of scintillating powder (0–500 mg) were evaluated, including energy, dose rate, and beam angle dependencies, as well as dose linearity. To determine the extent to which the SC‐IVD affected the dose to the medium, doses at R90 were compared depending on whether the SC‐IVD was on the surface. Finally, the accuracy of surface doses measured using the SC‐IVD was evaluated by comparison with surface doses measured using a Markus chamber. Results Charge measured using the SC‐IVD increased linearly with dose and was within 1% of the average signal according to the dose rate. The signal generated by the SC‐IVD increased as the beam angle increased. The presence of the SC‐IVD on the surface of a phantom resulted in a 0.5%–2.2% reduction in dose at R90 for 6–20 MeV electron beams compared with the bare phantom. Surface doses measured using the SC‐IVD system and Markus chamber differed by less than 5%. Conclusions The dosimetric characteristics of the SC‐IVD were evaluated in this study. The results showed that it accurately measured the surface dose without a significant difference of dose in the medium when compared with the Markus chamber. The flexibility of the SC‐IVD allows it to be attached to a patient's skin, enabling real‐time and cost‐effective measurement.
    Type of Medium: Online Resource
    ISSN: 0094-2405 , 2473-4209
    URL: Issue
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 1466421-5
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