Publications by authors named "Takahiro Nakamoto"

20 Publications

  • Page 1 of 1

[Improvement in Image Quality of CBCT during Treatment by Cycle Generative Adversarial Network].

Nihon Hoshasen Gijutsu Gakkai Zasshi 2020 ;76(11):1173-1184

Department of Radiology, University of Tokyo Hospital.

Purpose: Volumetric modulated arc therapy (VMAT) can acquire projection images during rotational irradiation, and cone-beam computed tomography (CBCT) images during VMAT delivery can be reconstructed. The poor quality of CBCT images prevents accurate recognition of organ position during the treatment. The purpose of this study was to improve the image quality of CBCT during the treatment by cycle generative adversarial network (CycleGAN).

Method: Twenty patients with clinically localized prostate cancer were treated with VMAT, and projection images for intra-treatment CBCT (iCBCT) were acquired. Synthesis of PCT (SynPCT) with improved image quality by CycleGAN requires only unpaired and unaligned iCBCT and planning CT (PCT) images for training. We performed visual and quantitative evaluation to compare iCBCT, SynPCT and PCT deformable image registration (DIR) to confirm the clinical usefulness.

Result: We demonstrated suitable CycleGAN networks and hyperparameters for SynPCT. The image quality of SynPCT improved visually and quantitatively while preserving anatomical structures of the original iCBCT. The undesirable deformation of PCT was reduced when SynPCT was used as its reference instead of iCBCT.

Conclusion: We have performed image synthesis with preservation of organ position by CycleGAN for iCBCT and confirmed the clinical usefulness.
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http://dx.doi.org/10.6009/jjrt.2020_JSRT_76.11.1173DOI Listing
November 2020

Fast Statistical Iterative Reconstruction for Mega-voltage Computed Tomography.

J Med Invest 2020 ;67(1.2):30-39

Department of Radiology, The University of Tokyo Hospital, Japan.

Statistical iterative reconstruction is expected to improve the image quality of computed tomography (CT). However, one of the challenges of iterative reconstruction is its large computational cost. The purpose of this review is to summarize a fast iterative reconstruction algorithm by optimizing reconstruction parameters. Megavolt projection data was acquired from a TomoTherapy system and reconstructed using in-house statistical iterative reconstruction algorithm. Total variation was used as the regularization term and the weight of the regularization term was determined by evaluating signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and visual assessment of spatial resolution using Gammex and Cheese phantoms. Gradient decent with an adaptive convergence parameter, ordered subset expectation maximization (OSEM), and CPU/GPU parallelization were applied in order to accelerate the present reconstruction algorithm. The SNR and CNR of the iterative reconstruction were several times better than that of filtered back projection (FBP). The GPU parallelization code combined with the OSEM algorithm reconstructed an image several hundred times faster than a CPU calculation. With 500 iterations, which provided good convergence, our method produced a 512 × 512 pixel image within a few seconds. The image quality of the present algorithm was much better than that of FBP for patient data. J. Med. Invest. 67 : 30-39, February, 2020.
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http://dx.doi.org/10.2152/jmi.67.30DOI Listing
June 2021

Publisher Correction: Prediction of malignant glioma grades using contrast-enhanced T1-weighted and T2-weighted magnetic resonance images based on a radiomic analysis.

Sci Rep 2020 Feb 17;10(1):3073. Epub 2020 Feb 17.

Department of Radiology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-020-60086-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026034PMC
February 2020

Prediction of malignant glioma grades using contrast-enhanced T1-weighted and T2-weighted magnetic resonance images based on a radiomic analysis.

Sci Rep 2019 12 19;9(1):19411. Epub 2019 Dec 19.

Department of Radiology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

We conducted a feasibility study to predict malignant glioma grades via radiomic analysis using contrast-enhanced T1-weighted magnetic resonance images (CE-T1WIs) and T2-weighted magnetic resonance images (T2WIs). We proposed a framework and applied it to CE-T1WIs and T2WIs (with tumor region data) acquired preoperatively from 157 patients with malignant glioma (grade III: 55, grade IV: 102) as the primary dataset and 67 patients with malignant glioma (grade III: 22, grade IV: 45) as the validation dataset. Radiomic features such as size/shape, intensity, histogram, and texture features were extracted from the tumor regions on the CE-T1WIs and T2WIs. The Wilcoxon-Mann-Whitney (WMW) test and least absolute shrinkage and selection operator logistic regression (LASSO-LR) were employed to select the radiomic features. Various machine learning (ML) algorithms were used to construct prediction models for the malignant glioma grades using the selected radiomic features. Leave-one-out cross-validation (LOOCV) was implemented to evaluate the performance of the prediction models in the primary dataset. The selected radiomic features for all folds in the LOOCV of the primary dataset were used to perform an independent validation. As evaluation indices, accuracies, sensitivities, specificities, and values for the area under receiver operating characteristic curve (or simply the area under the curve (AUC)) for all prediction models were calculated. The mean AUC value for all prediction models constructed by the ML algorithms in the LOOCV of the primary dataset was 0.902 ± 0.024 (95% CI (confidence interval), 0.873-0.932). In the independent validation, the mean AUC value for all prediction models was 0.747 ± 0.034 (95% CI, 0.705-0.790). The results of this study suggest that the malignant glioma grades could be sufficiently and easily predicted by preparing the CE-T1WIs, T2WIs, and tumor delineations for each patient. Our proposed framework may be an effective tool for preoperatively grading malignant gliomas.
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http://dx.doi.org/10.1038/s41598-019-55922-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6923390PMC
December 2019

Visual enhancement of Cone-beam CT by use of CycleGAN.

Med Phys 2020 Mar 3;47(3):998-1010. Epub 2020 Jan 3.

Department of Radiology, University of Tokyo Hospital, Tokyo, 113-8655, Japan.

Purpose: Cone-beam computed tomography (CBCT) offers advantages over conventional fan-beam CT in that it requires a shorter time and less exposure to obtain images. However, CBCT images suffer from low soft-tissue contrast, noise, and artifacts compared to conventional fan-beam CT images. Therefore, it is essential to improve the image quality of CBCT.

Methods: In this paper, we propose a synthetic approach to translate CBCT images with deep neural networks. Our method requires only unpaired and unaligned CBCT images and planning fan-beam CT (PlanCT) images for training. The CBCT images and PlanCT images may be obtained from other patients as long as they are acquired with the same scanner settings. Once trained, three-dimensionally reconstructed CBCT images can be directly translated into high-quality PlanCT-like images.

Results: We demonstrate the effectiveness of our method with images obtained from 20 prostate patients, and provide a statistical and visual comparison. The image quality of the translated images shows substantial improvement in voxel values, spatial uniformity, and artifact suppression compared to those of the original CBCT. The anatomical structures of the original CBCT images were also well preserved in the translated images.

Conclusions: Our method produces visually PlanCT-like images from CBCT images while preserving anatomical structures.
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http://dx.doi.org/10.1002/mp.13963DOI Listing
March 2020

Radiomics Analysis for Glioma Malignancy Evaluation Using Diffusion Kurtosis and Tensor Imaging.

Int J Radiat Oncol Biol Phys 2019 11 22;105(4):784-791. Epub 2019 Jul 22.

Department of Neurosurgery, University of Tokyo, Tokyo.

Purpose: A noninvasive diagnostic method to predict the degree of malignancy accurately would be of great help in glioma management. This study aimed to create a highly accurate machine learning model to perform glioma grading.

Methods And Materials: Preoperative magnetic resonance imaging acquired for cases of glioma operated on at our institution from October 2014 through January 2018 were obtained retrospectively. Six types of magnetic resonance imaging sequences (T-weighted image, diffusion-weighted image, apparent diffusion coefficient [ADC], fractional anisotropy, and mean kurtosis [MK]) were chosen for analysis; 476 features were extracted semiautomatically for each sequence (2856 features in total). Recursive feature elimination was used to select significant features for a machine learning model that distinguishes glioblastoma from lower-grade glioma (grades 2 and 3).

Results: Fifty-five data sets from 54 cases were obtained (14 grade 2 gliomas, 12 grade 3 gliomas, and 29 glioblastomas), of which 44 and 11 data sets were used for machine learning and independent testing, respectively. We detected 504 features with significant differences (false discovery rate <0.05) between glioblastoma and lower-grade glioma. The most accurate machine learning model was created using 6 features extracted from the ADC and MK images. In the logistic regression, the area under the curve was 0.90 ± 0.05, and the accuracy of the test data set was 0.91 (10 out of 11); using a support vector machine, they were 0.93 ± 0.03 and 0.91 (10 out of 11), respectively (kernel, radial basis function; c = 1.0).

Conclusions: Our machine learning model accurately predicted glioma tumor grade. The ADC and MK sequences produced particularly useful features.
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http://dx.doi.org/10.1016/j.ijrobp.2019.07.011DOI Listing
November 2019

[An Introduction to Radiomics: Toward a New Era of Precision Medicine].

Igaku Butsuri 2018;38(3):129-134

The University of Tokyo Hospital.

Recently, in a medical field, quantitative data mining is a hot topic for performing a precision (or personalized) medicine. Although a molecular biological data has been mainly utilized for data mining in this field, medical images are also important minable data. Radiomics is a comprehensive analysis methodology for describing tumor phenotypes or molecular biological expressions (e.g. genotypes) using minable feature extracted from a large number of medical images. In this review paper, we introduce to a framework of the radiomics.
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http://dx.doi.org/10.11323/jjmp.38.3_129DOI Listing
April 2019

Cone Beam Computed Tomography Image Quality Improvement Using a Deep Convolutional Neural Network.

Cureus 2018 Apr 29;10(4):e2548. Epub 2018 Apr 29.

Radiology, The University of Tokyo Hospital.

Introduction Cone beam computed tomography (CBCT) plays an important role in image-guided radiation therapy (IGRT), while having disadvantages of severe shading artifact caused by the reconstruction using scatter contaminated and truncated projections. The purpose of this study is to develop a deep convolutional neural network (DCNN) method for improving CBCT image quality. Methods CBCT and planning computed tomography (pCT) image pairs from 20 prostate cancer patients were selected. Subsequently, each pCT volume was pre-aligned to the corresponding CBCT volume by image registration, thereby leading to registered pCT data (pCT). Next, a 39-layer DCNN model was trained to learn a direct mapping from the CBCT to the corresponding pCTimages. The trained model was applied to a new CBCT data set to obtain improved CBCT (i-CBCT) images. The resulting i-CBCT images were compared to pCT using the spatial non-uniformity (SNU), the peak-signal-to-noise ratio (PSNR) and the structural similarity index measure (SSIM). Results The image quality of the i-CBCT has shown a substantial improvement on spatial uniformity compared to that of the original CBCT, and a significant improvement on the PSNR and the SSIM compared to that of the original CBCT and the enhanced CBCT by the existing pCT-based correction method. Conclusion We have developed a DCNN method for improving CBCT image quality. The proposed method may be directly applicable to CBCT images acquired by any commercial CBCT scanner.
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http://dx.doi.org/10.7759/cureus.2548DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6021187PMC
April 2018

Volumetric and dosimetric comparison of organs at risk between the prone and supine positions in postoperative radiotherapy for prostate cancer.

Radiat Oncol 2018 Apr 17;13(1):70. Epub 2018 Apr 17.

Departments of Radiology, University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan.

Background: The aim of this study was to evaluate the effects of patient positioning on the volume of organs at risk (OARs) in or near the planning target volume (PTV) and the dose distribution in adjuvant or salvage radiotherapy for prostate cancer after prostatectomy.

Methods: Seventeen patients who received intensity-modulated radiation therapy (66 Gy in 33 fractions) as adjuvant or salvage therapy after prostatectomy were evaluated. All patients underwent CT scans in both the prone (on a belly board) and supine positions. The target volumes and OARs were delineated on each CT series. The planning target volume (PTV) was extended in every direction to generate the PTV + 0.5 cm, PTV + 1 cm, PTV + 2 cm, PTV + 3 cm, and PTV + 4 cm values. The volumes of the OARs overlapping with the PTV and the extended target volumes in the prone and supine position were compared using the Wilcoxon signed-rank test. Dose-volume histogram (DVH) parameters in the prone and supine position were compared using the paired t-test.

Results: The mean overlapping volumes of the small intestine for each of the PTV values were as follows (prone position vs. supine position [mean ± SD]): PTV, 1.5 ± 5.5 cm vs. 7.9 ± 15.7 cm (P = 0.028); PTV + 0.5 cm, 2.6 ± 8.9 cm vs. 12.1 ± 22.6 cm (P = 0.028); PTV + 1 cm, 3.5 ± 11.4 cm vs. 17.1 ± 29.8 cm (P = 0.028); PTV + 2 cm, 5.6 ± 14.5 cm vs. 26.8 ± 46.9 cm (P = 0.028); and PTV + 3 cm, 9.0 ± 17.4 cm vs. 36.5 ± 63.2 cm (P = 0.019), respectively. Some of the overlapping volumes of the rectum and bladder were significantly smaller in the prone position. On the other hand, when the target volume was extended by ≥2 cm, the overlapping volumes of the femurs were significantly larger in the prone position. V15 of the rectum and mean dose and V65 of the bladder were significantly lower in the prone position.

Conclusions: This study indicated that the volumes of the small intestine, rectum, and bladder in or near the PTV decreased when the patient was placed in the prone position on a belly board in postoperative radiotherapy for prostate cancer. The dose distribution seemed superior in the prone position to the supine position.
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http://dx.doi.org/10.1186/s13014-018-1023-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5905127PMC
April 2018

Exploration of temporal stability and prognostic power of radiomic features based on electronic portal imaging device images.

Phys Med 2018 Feb 19;46:32-44. Epub 2018 Jan 19.

Faculty of Medical Sciences, Kyushu University 3-1-1, Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.

Purpose: We aimed to explore the temporal stability of radiomic features in the presence of tumor motion and the prognostic powers of temporally stable features.

Methods: We selected single fraction dynamic electronic portal imaging device (EPID) (n = 275 frames) and static digitally reconstructed radiographs (DRRs) of 11 lung cancer patients, who received stereotactic body radiation therapy (SBRT) under free breathing. Forty-seven statistical radiomic features, which consisted of 14 histogram-based features and 33 texture features derived from the graylevel co-occurrence and graylevel run-length matrices, were computed. The temporal stability was assessed by using a multiplication of the intra-class correlation coefficients (ICCs) between features derived from the EPID and DRR images at three quantization levels. The prognostic powers of the features were investigated using a different database of lung cancer patients (n = 221) based on a Kaplan-Meier survival analysis.

Results: Fifteen radiomic features were found to be temporally stable for various quantization levels. Among these features, seven features have shown potentials for prognostic prediction in lung cancer patients.

Conclusions: This study suggests a novel approach to select temporally stable radiomic features, which could hold prognostic powers in lung cancer patients.
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http://dx.doi.org/10.1016/j.ejmp.2017.11.037DOI Listing
February 2018

Utility of F-18 FDG PET/CT for Detection of Bone Marrow Metastases in Prostate Cancer Patients Treated with Radium-223.

Asia Ocean J Nucl Med Biol 2018 ;6(1):61-67

Departments of Radiology, Kansai Medical University, Japan.

A 76-year-old man with symptomatic bone metastases from castration-resistant prostate cancer underwent Radium-223-dichloride (Ra-223) therapy. Before Ra-223 therapy, he had normal peripheral blood cell counts. Ra-223 therapy relieved his shoulder and low back pain. The elevation of the serum prostate-specific antigen (PSA), doubling every month during Ra-223 therapy, suggested a PSA flare or relapse. Some lesions showed decrease and some lesions showed increase on Tc-99m hydroxymethylene diphosphonate bone scintigraphy at two weeks after the third injection of Ra-223 therapy. Ra-223 therapy was discontinued due to thrombocytopenia that was getting worse rapidly. After treatment discontinuation, namely four weeks after the third injection of Ra-223, F-18 fluorodeoxyglucose (FDG) Positron Emission Tomography (PET)/CT and a biopsy were performed to evaluate for metastases, and bone marrow metastases were found. Ra-223 was effective for osteoblastic lesions, but not for bone marrow metastases. FDG PET/CT, but not a Tc-99m based bone scan, detected diffuse bone marrow involvement by cancer. This case report is the first to clarify the utility of FDG PET for the detection of bone marrow metastases confirmed by pathological examination in Ra-223 therapy for progressive castration-resistant prostate cancer.
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http://dx.doi.org/10.22038/aojnmb.2017.9896DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5765335PMC
January 2018

Investigation of interfractional shape variations based on statistical point distribution model for prostate cancer radiation therapy.

Med Phys 2017 May 20;44(5):1837-1845. Epub 2017 Apr 20.

Faculty of Medical Sciences, Kyushu University, 3-1-1, Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan.

Purpose: The setup errors and organ motion errors pertaining to clinical target volume (CTV) have been considered as two major causes of uncertainties in the determination of the CTV-to-planning target volume (PTV) margins for prostate cancer radiation treatment planning. We based our study on the assumption that interfractional target shape variations are not negligible as another source of uncertainty for the determination of precise CTV-to-PTV margins. Thus, we investigated the interfractional shape variations of CTVs based on a point distribution model (PDM) for prostate cancer radiation therapy.

Materials And Methods: To quantitate the shape variations of CTVs, the PDM was applied for the contours of 4 types of CTV regions (low-risk, intermediate- risk, high-risk CTVs, and prostate plus entire seminal vesicles), which were delineated by considering prostate cancer risk groups on planning computed tomography (CT) and cone beam CT (CBCT) images of 73 fractions of 10 patients. The standard deviations (SDs) of the interfractional random errors for shape variations were obtained from covariance matrices based on the PDMs, which were generated from vertices of triangulated CTV surfaces. The correspondences between CTV surface vertices were determined based on a thin-plate spline robust point matching algorithm. The systematic error for shape variations was defined as the average deviation between surfaces of an average CTV and planning CTVs, and the random error as the average deviation of CTV surface vertices for fractions from an average CTV surface.

Results: The means of the SDs of the systematic errors for the four types of CTVs ranged from 1.0 to 2.0 mm along the anterior direction, 1.2 to 2.6 mm along the posterior direction, 1.0 to 2.5 mm along the superior direction, 0.9 to 1.9 mm along the inferior direction, 0.9 to 2.6 mm along the right direction, and 1.0 to 3.0 mm along the left direction. Concerning the random errors, the means of the SDs ranged from 0.9 to 1.2 mm along the anterior direction, 1.0 to 1.4 mm along the posterior direction, 0.9 to 1.3 mm along the superior direction, 0.8 to 1.0 mm along the inferior direction, 0.8 to 0.9 mm along the right direction, and 0.8 to 1.0 mm along the left direction.

Conclusions: Since the shape variations were not negligible for intermediate and high-risk CTVs, they should be taken into account for the determination of the CTV-to-PTV margins in radiation treatment planning of prostate cancer.
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http://dx.doi.org/10.1002/mp.12217DOI Listing
May 2017

Comparison of Nephroscope-assisted "Pulling Thread" Technique and Conventional Open Placement of Peritoneal Dialysis Catheters in Patients With End-stage Renal Disease.

Urology 2016 Nov 7;97:261-265. Epub 2016 Jul 7.

Department of Urology and Andrology, Kansai Medical University Hospital, Osaka, Japan; Kidney Center, Kansai Medical University Hospital, Osaka, Japan. Electronic address:

Objective: To compare the clinical outcomes between nephroscope-assisted "pulling thread" technique (NPT) and conventional open placement (OP) of catheters in peritoneal dialysis patients.

Materials And Methods: We retrospectively reviewed 97 consecutive patients undergoing either NPT (n = 57) or OP (n = 40) for peritoneal dialysis catheter placement from March 2007 to May 2015. The operation-related data, early catheter-related complications, and long-term catheter survival were analyzed.

Results: The overall early catheter-related complication rate was lower in NPT compared with OP (P = .0035). Furthermore, OP had a significantly higher rate of catheter migration than NPT (15.0% vs 3.5%, respectively, P = .042). Patients undergoing NPT had better catheter survival than those undergoing OP, with 1-year survival rates of 93.5% and 81.1%, and 2-year survival rates of 83.0% and 63.3%, respectively (P = .007).

Conclusion: NPT exhibited superiority to OP in terms of the postoperative early complication rate and catheter survival. This novel technique would thus be ideal for peritoneal dialysis catheter placement.
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http://dx.doi.org/10.1016/j.urology.2016.06.019DOI Listing
November 2016

[LOWER URINARY TRACT SYMPTOMS AND FUNCTIONS AFTER RENAL TRANSPLANTATION AT OUR HOSPITAL].

Nihon Hinyokika Gakkai Zasshi 2015 Oct;106(4):249-54

Objective: We investigated lower urinary tract symptoms (LUTS) and function in patients who had undergone renal transplantation (RTx).

Methods: Fifty patients (34 males and 16 females; age 16-68 years) undergoing RTx at our hospital were included in this study. Average follow-up after RTx was 6.1 years (range 0.5-28). The pre-transplant dialysis period averaged 2.5 years (range preemptive-18.6 years). We conducted the evaluation of lower urinary tract symptoms (LUTS) and function using uroflowmetry (UFM) , residual urine measurement, 24h bladder diary, International Prostate Symptom Score (IPSS), QOL score, Overactive Bladder Symptom Score (OABSS) and Core Lower Urinary Tract Symptom Score (CLSS).

Results: Average first desire to void and maximum desire to void were 89.9 mL and 185 mL respectively in cystometry before RTx. Atrophy of the bladder before RTx showed a correlation with the dialysis period. UFM of post-RTx was maximum urinary flow rate of 21.8 mL/s and a voided volume of 287.6 mL. Severe cases of IPSS, QOL, OABSS and CLSS were not observed. Average 24h voided volume, urination times and nocturia were 2,329 mL, 8.2 times and 0.9 times respectively. Polyuria after RTx was observed in 21 patients (42%). Aging and vascular lesions such as diabetes and cardiovascular disease were the most important factor of LUTS.

Conclusions: After RTx, LUTS were present in a number of cases after RTx. Patients undergoing RTx has been aging, it is considered necessary to perform the evaluation of LUTS before RTx.
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http://dx.doi.org/10.5980/jpnjurol.106.249DOI Listing
October 2015

Applications of Machine Learning for Radiation Therapy.

Igaku Butsuri 2016 ;36(1):35-38

Division of Medical Quantum Science, Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University.

Radiation therapy has been highly advanced as image guided radiation therapy (IGRT) by making advantage of image engineering technologies. Recently, novel frameworks based on image engineering technologies as well as machine learning technologies have been studied for sophisticating the radiation therapy. In this review paper, the author introduces several researches of applications of machine learning for radiation therapy. For examples, a method to determine the threshold values for standardized uptake value (SUV) for estimation of gross tumor volume (GTV) in positron emission tomography (PET) images, an approach to estimate the multileaf collimator (MLC) position errors between treatment plans and radiation delivery time, and prediction frameworks for esophageal stenosis and radiation pneumonitis risk after radiation therapy are described. Finally, the author introduces seven issues that one should consider when applying machine learning models to radiation therapy.
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http://dx.doi.org/10.11323/jjmp.36.1_35DOI Listing
May 2017

Successful Treatment of Transplant Renal Artery Thrombosis With Systemic Infusion of Recombinant-Tissue-Plasminogen Activator After Renal Transplant.

Exp Clin Transplant 2017 Oct 31;15(5):571-573. Epub 2015 Aug 31.

From the Department of Urology and Andrology, Kansai Medical University, Hirakata Hospital, Osaka, Japan.

A 24-year-old man with end-stage renal disease secondary to congenital renal hypoplasia under-went a preemptive renal transplant. Although a vascular complication occurred during surgery, the operation was completed satisfactorily. However, postoperative Doppler ultrasound showed no perfusion of the renal artery, vein, and parenchyma, indicating a transplant renal artery thrombosis. A reoperation was promptly performed, with systemic infusion of recombinant-tissue-plasminogen activator during graft nephrectomy, followed by a reimplant that resulted in a salvage allograft. Immediate thrombolysis using systemically infused recombinant-tissue-plasminogen activator may be an effective treatment option for transplant renal artery thrombosis after renal transplant.
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http://dx.doi.org/10.6002/ect.2015.0099DOI Listing
October 2017

Laparoscopic upper-pole heminephrectomy for duplicated renal collecting system with superselective artery clamping using virtual partial nephrectomy analysis of Synapse Vincent: A case report.

Int J Urol 2015 Nov 24;22(11):1075-7. Epub 2015 Aug 24.

Department of Urology and Andrology, Kansai Medical University, Hirakata, Osaka, Japan.

A 22-year-old woman was diagnosed with a duplicated renal collecting system with hydronephrosis and parenchymal loss in the upper pole of the left kidney. She underwent laparoscopic left upper-pole nephrectomy. Although a complex hilar vascular anatomy was identified during the operation, preoperative three-dimensional computed tomographic reconstruction using a three-dimensional image analysis device (Synapse Vincent; Fuji Medical Systems, Tokyo, Japan) greatly helped to accurately identify the anatomical renal hilum. For further detail, virtual partial nephrectomy analysis using a Voronoi decomposition was used to visualize the area supplied by a selected arterial branch including the atrophic cleavage line. We controlled the bleeding with selective clamping and safely carried out upper-pole heminephrectomy according to the preoperative plan.
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http://dx.doi.org/10.1111/iju.12897DOI Listing
November 2015

Conservative Treatment for Benign Prostatic Hyperplasia in Patients With Bladder Stones.

Urology 2015 Sep 30;86(3):450-3. Epub 2015 Jul 30.

Department of Urology and Andrology, Kansai Medical University, Hirakata Hospital, Hirakata, Japan.

Objective: To determine whether conservative management of benign prostatic hyperplasia (BPH) is an appropriate option for patients with bladder stones.

Methods: The study cohort comprised 34 men who underwent endoscopic bladder stone removal with subsequent conservative management of BPH, including watchful waiting and medical therapy (alpha-blocker ± dutasteride), between April 2006 and January 2014. We recorded BPH-related complications after stone removal and compared International Prostate Symptom Scores, quality of life scores, and postvoid residual urine volume before and after treatment. Cumulative BPH-related complication-free survival and the preoperative parameters associated with the occurrence of BPH-related complications were also analyzed.

Results: Twenty-six patients (76.5%) treated with conservative management had no BPH-related complications, during a mean follow-up of 52.6 ± 30.9 months. Mean International Prostate Symptom Scores fell from 13.5 ± 7.1 before treatment to 9.7 ± 6.3 after treatment (P = .025). One of the 34 patients (2.9%) experienced recurrent urinary infections, 2 (5.9%) had urinary retention, and 6 (17.6%) developed recurrent bladder stones. The cumulative BPH-related complication-free survival was 97.0% at 1 year, 81.8% at 3 years, and 70.5% at 5 years. Six of the men (17.6%) underwent invasive intervention for BPH after occurrence of these complications. Prostate volume was the only preoperative parameter associated with the occurrence of complications after stone removal (P = .035).

Conclusion: Conservative management of BPH can be an appropriate treatment option in men with bladder stones and concurrent mild-to-moderate lower urinary tract symptoms.
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http://dx.doi.org/10.1016/j.urology.2015.04.022DOI Listing
September 2015

Complete resolution of myoclonus-like involuntary movements under subarachnoid block after midazolam administration in a patient undergoing cesarean section: a case report.

Korean J Anesthesiol 2015 Apr 30;68(2):193-5. Epub 2015 Mar 30.

Department of Anesthesiology, Kansai Medical University, Hirakata, Japan.

Involuntary movement during and after neuraxial anesthesia, such as spinal and epidural anesthesia, is rarely observed. In this report, we describe a case of myoclonus-like involuntary movement of the upper extremities in a patient undergoing a planned repeat cesarean section under spinal anesthesia with bupivacaine that completely subsided after administration of 2 mg of midazolam. The myoclonus-like movement did not recur or cause any apparent neurological side effects.
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http://dx.doi.org/10.4097/kjae.2015.68.2.193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4384410PMC
April 2015

A computerized framework for monitoring four-dimensional dose distributions during stereotactic body radiation therapy using a portal dose image-based 2D/3D registration approach.

Comput Med Imaging Graph 2015 Mar 26;40:1-12. Epub 2014 Dec 26.

Division of Medical Quantum Science, Department of Health Sciences, Faculty of Medical Sciences, Kyushu University, Fukuoka, Japan.

A computerized framework for monitoring four-dimensional (4D) dose distributions during stereotactic body radiation therapy based on a portal dose image (PDI)-based 2D/3D registration approach has been proposed in this study. Using the PDI-based registration approach, simulated 4D "treatment" CT images were derived from the deformation of 3D planning CT images so that a 2D planning PDI could be similar to a 2D dynamic clinical PDI at a breathing phase. The planning PDI was calculated by applying a dose calculation algorithm (a pencil beam convolution algorithm) to the geometry of the planning CT image and a virtual water equivalent phantom. The dynamic clinical PDIs were estimated from electronic portal imaging device (EPID) dynamic images including breathing phase data obtained during a treatment. The parameters of the affine transformation matrix were optimized based on an objective function and a gamma pass rate using a Levenberg-Marquardt (LM) algorithm. The proposed framework was applied to the EPID dynamic images of ten lung cancer patients, which included 183 frames (mean: 18.3 per patient). The 4D dose distributions during the treatment time were successfully obtained by applying the dose calculation algorithm to the simulated 4D "treatment" CT images. The mean±standard deviation (SD) of the percentage errors between the prescribed dose and the estimated dose at an isocenter for all cases was 3.25±4.43%. The maximum error for the ten cases was 14.67% (prescribed dose: 1.50Gy, estimated dose: 1.72Gy), and the minimum error was 0.00%. The proposed framework could be feasible for monitoring the 4D dose distribution and dose errors within a patient's body during treatment.
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http://dx.doi.org/10.1016/j.compmedimag.2014.12.003DOI Listing
March 2015
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