1.Planning evaluation of stereotactic magnetic resonance–guided online adaptive radiosurgery for kidney tumors close to the organ at risk: is it valuable to wait for good timing to perform stereotactic radiosurgery?
Takaya YAMAMOTO ; Shohei TANAKA ; Noriyoshi TAKAHASHI ; Rei UMEZAWA ; Yu SUZUKI ; Keita KISHIDA ; So OMATA ; Kazuya TAKEDA ; Hinako HARADA ; Kiyokazu SATO ; Yoshiyuki KATSUTA ; Noriyuki KADOYA ; Keiichi JINGU
Radiation Oncology Journal 2025;43(1):40-48
Purpose:
This study aimed to investigate changes in target coverage using magnetic resonance–guided online adaptive radiotherapy (MRgoART) for kidney tumors and to evaluate the suitable timing of treatment.
Materials and Methods:
Among patients treated with 3-fraction MRgoART for kidney cancer, 18 tumors located within 1 cm of the gastrointestinal tract were selected. Stereotactic radiosurgery planning with a prescription dose of 26 Gy was performed using pretreatment simulation and three MRgoART timings with an adapt-to-shape method. The best MRgoART plan was defined as the plan achieving the highest percentage of planning target volume (PTV) coverage of 26 Gy. In clinical scenario simulation, MRgoART plans were evaluated in the order of actual treatment. Waiting for the next timing was done when the PTV coverage of 26 Gy did not achieve 95%–99% or did not increase by 5% or more compared to the pretreatment plan.
Results:
The median percentages of PTV receiving 26 Gy in pretreatment and the first, second, and third MRgoART were 82% (range, 19%), 63% (range, 7% to 99%), 88% (range, 31% to 99%), and 95% (range, 3% to 99%), respectively. Comparing pretreatment simulation plans with the best MRgoART plans showed a significant difference (p = 0.025). In the clinical scenario simulation, 16 of the 18 planning series, including nine plans with 95%–99% PTV coverage of 26 Gy and seven plans with increased PTV coverage by 5% or more, would be irradiated at a good timing.
Conclusion
MRgoART revealed dose coverage differences at each MRgoART timing. Waiting for optimal irradiation timing could be an option in case of suboptimal timing.
2.Planning evaluation of stereotactic magnetic resonance–guided online adaptive radiosurgery for kidney tumors close to the organ at risk: is it valuable to wait for good timing to perform stereotactic radiosurgery?
Takaya YAMAMOTO ; Shohei TANAKA ; Noriyoshi TAKAHASHI ; Rei UMEZAWA ; Yu SUZUKI ; Keita KISHIDA ; So OMATA ; Kazuya TAKEDA ; Hinako HARADA ; Kiyokazu SATO ; Yoshiyuki KATSUTA ; Noriyuki KADOYA ; Keiichi JINGU
Radiation Oncology Journal 2025;43(1):40-48
Purpose:
This study aimed to investigate changes in target coverage using magnetic resonance–guided online adaptive radiotherapy (MRgoART) for kidney tumors and to evaluate the suitable timing of treatment.
Materials and Methods:
Among patients treated with 3-fraction MRgoART for kidney cancer, 18 tumors located within 1 cm of the gastrointestinal tract were selected. Stereotactic radiosurgery planning with a prescription dose of 26 Gy was performed using pretreatment simulation and three MRgoART timings with an adapt-to-shape method. The best MRgoART plan was defined as the plan achieving the highest percentage of planning target volume (PTV) coverage of 26 Gy. In clinical scenario simulation, MRgoART plans were evaluated in the order of actual treatment. Waiting for the next timing was done when the PTV coverage of 26 Gy did not achieve 95%–99% or did not increase by 5% or more compared to the pretreatment plan.
Results:
The median percentages of PTV receiving 26 Gy in pretreatment and the first, second, and third MRgoART were 82% (range, 19%), 63% (range, 7% to 99%), 88% (range, 31% to 99%), and 95% (range, 3% to 99%), respectively. Comparing pretreatment simulation plans with the best MRgoART plans showed a significant difference (p = 0.025). In the clinical scenario simulation, 16 of the 18 planning series, including nine plans with 95%–99% PTV coverage of 26 Gy and seven plans with increased PTV coverage by 5% or more, would be irradiated at a good timing.
Conclusion
MRgoART revealed dose coverage differences at each MRgoART timing. Waiting for optimal irradiation timing could be an option in case of suboptimal timing.
3.Planning evaluation of stereotactic magnetic resonance–guided online adaptive radiosurgery for kidney tumors close to the organ at risk: is it valuable to wait for good timing to perform stereotactic radiosurgery?
Takaya YAMAMOTO ; Shohei TANAKA ; Noriyoshi TAKAHASHI ; Rei UMEZAWA ; Yu SUZUKI ; Keita KISHIDA ; So OMATA ; Kazuya TAKEDA ; Hinako HARADA ; Kiyokazu SATO ; Yoshiyuki KATSUTA ; Noriyuki KADOYA ; Keiichi JINGU
Radiation Oncology Journal 2025;43(1):40-48
Purpose:
This study aimed to investigate changes in target coverage using magnetic resonance–guided online adaptive radiotherapy (MRgoART) for kidney tumors and to evaluate the suitable timing of treatment.
Materials and Methods:
Among patients treated with 3-fraction MRgoART for kidney cancer, 18 tumors located within 1 cm of the gastrointestinal tract were selected. Stereotactic radiosurgery planning with a prescription dose of 26 Gy was performed using pretreatment simulation and three MRgoART timings with an adapt-to-shape method. The best MRgoART plan was defined as the plan achieving the highest percentage of planning target volume (PTV) coverage of 26 Gy. In clinical scenario simulation, MRgoART plans were evaluated in the order of actual treatment. Waiting for the next timing was done when the PTV coverage of 26 Gy did not achieve 95%–99% or did not increase by 5% or more compared to the pretreatment plan.
Results:
The median percentages of PTV receiving 26 Gy in pretreatment and the first, second, and third MRgoART were 82% (range, 19%), 63% (range, 7% to 99%), 88% (range, 31% to 99%), and 95% (range, 3% to 99%), respectively. Comparing pretreatment simulation plans with the best MRgoART plans showed a significant difference (p = 0.025). In the clinical scenario simulation, 16 of the 18 planning series, including nine plans with 95%–99% PTV coverage of 26 Gy and seven plans with increased PTV coverage by 5% or more, would be irradiated at a good timing.
Conclusion
MRgoART revealed dose coverage differences at each MRgoART timing. Waiting for optimal irradiation timing could be an option in case of suboptimal timing.
4.Planning evaluation of stereotactic magnetic resonance–guided online adaptive radiosurgery for kidney tumors close to the organ at risk: is it valuable to wait for good timing to perform stereotactic radiosurgery?
Takaya YAMAMOTO ; Shohei TANAKA ; Noriyoshi TAKAHASHI ; Rei UMEZAWA ; Yu SUZUKI ; Keita KISHIDA ; So OMATA ; Kazuya TAKEDA ; Hinako HARADA ; Kiyokazu SATO ; Yoshiyuki KATSUTA ; Noriyuki KADOYA ; Keiichi JINGU
Radiation Oncology Journal 2025;43(1):40-48
Purpose:
This study aimed to investigate changes in target coverage using magnetic resonance–guided online adaptive radiotherapy (MRgoART) for kidney tumors and to evaluate the suitable timing of treatment.
Materials and Methods:
Among patients treated with 3-fraction MRgoART for kidney cancer, 18 tumors located within 1 cm of the gastrointestinal tract were selected. Stereotactic radiosurgery planning with a prescription dose of 26 Gy was performed using pretreatment simulation and three MRgoART timings with an adapt-to-shape method. The best MRgoART plan was defined as the plan achieving the highest percentage of planning target volume (PTV) coverage of 26 Gy. In clinical scenario simulation, MRgoART plans were evaluated in the order of actual treatment. Waiting for the next timing was done when the PTV coverage of 26 Gy did not achieve 95%–99% or did not increase by 5% or more compared to the pretreatment plan.
Results:
The median percentages of PTV receiving 26 Gy in pretreatment and the first, second, and third MRgoART were 82% (range, 19%), 63% (range, 7% to 99%), 88% (range, 31% to 99%), and 95% (range, 3% to 99%), respectively. Comparing pretreatment simulation plans with the best MRgoART plans showed a significant difference (p = 0.025). In the clinical scenario simulation, 16 of the 18 planning series, including nine plans with 95%–99% PTV coverage of 26 Gy and seven plans with increased PTV coverage by 5% or more, would be irradiated at a good timing.
Conclusion
MRgoART revealed dose coverage differences at each MRgoART timing. Waiting for optimal irradiation timing could be an option in case of suboptimal timing.
5.Planning evaluation of stereotactic magnetic resonance–guided online adaptive radiosurgery for kidney tumors close to the organ at risk: is it valuable to wait for good timing to perform stereotactic radiosurgery?
Takaya YAMAMOTO ; Shohei TANAKA ; Noriyoshi TAKAHASHI ; Rei UMEZAWA ; Yu SUZUKI ; Keita KISHIDA ; So OMATA ; Kazuya TAKEDA ; Hinako HARADA ; Kiyokazu SATO ; Yoshiyuki KATSUTA ; Noriyuki KADOYA ; Keiichi JINGU
Radiation Oncology Journal 2025;43(1):40-48
Purpose:
This study aimed to investigate changes in target coverage using magnetic resonance–guided online adaptive radiotherapy (MRgoART) for kidney tumors and to evaluate the suitable timing of treatment.
Materials and Methods:
Among patients treated with 3-fraction MRgoART for kidney cancer, 18 tumors located within 1 cm of the gastrointestinal tract were selected. Stereotactic radiosurgery planning with a prescription dose of 26 Gy was performed using pretreatment simulation and three MRgoART timings with an adapt-to-shape method. The best MRgoART plan was defined as the plan achieving the highest percentage of planning target volume (PTV) coverage of 26 Gy. In clinical scenario simulation, MRgoART plans were evaluated in the order of actual treatment. Waiting for the next timing was done when the PTV coverage of 26 Gy did not achieve 95%–99% or did not increase by 5% or more compared to the pretreatment plan.
Results:
The median percentages of PTV receiving 26 Gy in pretreatment and the first, second, and third MRgoART were 82% (range, 19%), 63% (range, 7% to 99%), 88% (range, 31% to 99%), and 95% (range, 3% to 99%), respectively. Comparing pretreatment simulation plans with the best MRgoART plans showed a significant difference (p = 0.025). In the clinical scenario simulation, 16 of the 18 planning series, including nine plans with 95%–99% PTV coverage of 26 Gy and seven plans with increased PTV coverage by 5% or more, would be irradiated at a good timing.
Conclusion
MRgoART revealed dose coverage differences at each MRgoART timing. Waiting for optimal irradiation timing could be an option in case of suboptimal timing.
6.Neural crest stem cells can be induced in vitro from human-induced pluripotent stem cells using a novel protocol free of feeder cells
Rei ABE ; Kazuyo YAMAUCHI ; Kazuki KUNIYOSHI ; Takane SUZUKI ; Yusuke MATSUURA ; Seiji OHTORI ; Kazuhisa TAKAHASHI
Journal of Rural Medicine 2021;16(3):143-147
Objective: Our knowledge of human neural crest stem cells (NCSCs) is expanding, owing to recent advances in technologies utilizing human-induced pluripotent stem cells (hiPSCs) that generate NCSCs. However, the clinical application of these technologies requires the reduction of xeno-materials. To overcome this significant impediment, this study aimed to devise a novel method to induce NCSCs from hiPSCs without using a feeder cell layer.Materials and Methods: hiPSCs were cultured in feeder-free maintenance media containing the Rho-associated coiled-coil forming kinase inhibitor Y-27632. When the cells reached 50–70% confluence, differentiation was initiated by replacing the medium with knockout serum replacement (KSR) medium containing Noggin and SB431542. The KSR medium was then gradually replaced with increasing concentrations of Neurobasal medium from day 5 to 11.Results: Immunocytochemistry and flow cytometry were performed 12 days after induction of differentiation and revealed that the cells generated from hiPSCs expressed the NCSC markers p75 and HNK-1, but not the hiPSC marker SOX2.Conclusion: These findings demonstrate that hiPSCs were induced to differentiate into NCSCs in the absence of feeder cells.
7.Hyperfractionated radiotherapy for re-irradiation of recurrent esophageal cancer
Kazuya TAKEDA ; Haruo MATSUSHITA ; Rei UMEZAWA ; Takaya YAMAMOTO ; Yojiro ISHIKAWA ; Noriyoshi TAKAHASHI ; Yu SUZUKI ; Keiichi JINGU
Radiation Oncology Journal 2021;39(4):265-269
Purpose:
Re-irradiation is a treatment option for recurrent esophageal cancer patients with a history of radiotherapy, but there is a risk of severe late adverse effects. This study focused on the efficacy and safety of re-irradiation using hyperfractionated radiotherapy.
Materials and Methods:
Twenty-six patients who underwent re-irradiation by the hyperfraction technique using twice-daily irradiation of 1.2 Gy per fraction for recurrent esophageal cancer were retrospectively included in this study. The overall survival period after the start of secondary radiotherapy and the occurrence of late adverse effects were investigated.
Results:
Of 26 patients, 21 (81%) received re-irradiation with definitive intention and 21 (81%) underwent concurrent chemotherapy. The median re-irradiation dose was 60 Gy in 50 fractions in 25 treatment days, and the median accumulated irradiation dose in equivalent dose in 2 Gy per fraction was 85.4 Gy with an α/β value of 3. The median interval between two courses of radiotherapy was 21.0 months. The median overall survival period was 15.8 months and the 1-year and 3-year overall survival rates were 64.3% and 28.3%, respectively. Higher dose of re-irradiation and concurrent chemotherapy significantly improved survival (p < 0.001 and p = 0.019, respectively). Severe late adverse effects with the Common Terminology Criteria for Adverse Events grade 3 or higher were observed in 5 (19.2%) patients, and 2 (7.7%) of them developed a grade 5 late adverse effect.
Conclusion
High-dose re-irradiation using a hyperfractionated schedule with concurrent chemotherapy might be related to good prognosis, while the rate of late severe adverse effects is not high compared with the rates in past reports.
8.Closed Wedge Distal Femoral Osteotomy with a Polyaxial Locking Plate Designed for the Proximal Tibia: Minimum 5-Year Outcomes
Ryuichi NAKAMURA ; Kenji FUJITA ; Rei OMI ; Kazunari KURODA ; Masaki TAKAHASHI ; Kazumi IKEBUCHI ; Hitoshi NISHIMURA ; Yasuo KATSUKI
The Journal of Korean Knee Society 2017;29(3):232-236
Since distal femoral varus osteotomy (DFO)
Asian Continental Ancestry Group
;
Humans
;
Japan
;
Knee
;
Osteoarthritis
;
Osteotomy
;
Tibia
;
Weight-Bearing
9.CENTRAL AND PERIPHERAL FATIGUE DURING SUSTAINED MAXIMAL VOLUNTARY CONTRACTIONS IN TRAINED AND UNTRAINED HUMAN SUBJECTS
TAKASHI ENDOH ; MASASHI MITAMURA ; TSUYOSHI NAKAJIMA ; REI TAKAHASHI ; TOMOYOSHI KOMIYAMA
Japanese Journal of Physical Fitness and Sports Medicine 2004;53(2):211-220
The present study investigated how resistance training affects behaviors related to central and peripheral fatigue during a sustained maximal voluntary contraction (MVC) . The subjects were well-trained (TR, n=8) and sedentary untrained (UT, n=6) males. The subjects were asked to repetitively perform 3 sets of MVC (elbow flexion) for 1 min with a rest interval of 1 min. Transcranial magnetic stimulation (TMS) was delivered to the contralateral motor cortex to evoke the motor evoked potential (MEP) and electromyographic (EMG) silent period (SP) after the MEP. Ratio of root mean square (RMS) of the EMG and elbow flexion force (RMS/F) was also calculated.
The time course of the decrease in elbow flexion force that was standardized with respect to the maximal value obtained at the beginning of the first MVC was almost identical in both TR and UT. At the end of the task, the elbow flexion force decreased to around 30 % of the initial value in both groups. Decrease in voluntary activation (VA) estimated by the increment of the force after TMS was significantly larger in UT (77.3%) than in TR (88.2%) at the end of the task. Although the increase in MEP during the first set was significantly greater in UT than in TR, elongation of SP was significantly larger in UT than in TR. Increase in RMS/F, which is a manifestation of peripheral fatigue, was significantly larger in TR than in UT.
These results suggest that decrease in MVC in UT and in TR is respectively more attributable to central and peripheral fatigue, and that inhibitory inputs to motor cortex were larger in UT than in TR. It is concluded that expression of central and peripheral fatigue is affected by resistance training.
10.CHANGES IN THE MOTOR EVOKED POTENTIALS DURING REPETITIVE MAXIMUM PEDALING WITH DIFFERENT LOADS
MASASHI MITAMURA ; TAKASHI ENDOH ; REI TAKAHASHI ; TOMOYOSHI KOMIYAMA
Japanese Journal of Physical Fitness and Sports Medicine 2003;52(5):555-563
Eleven healthy subjects repetitively performed maximal cycling movement for 10 s with 20 s rest intervals. The load of the cycling was respectively set to 30% (high frequency task, lIF' task) and 80% (high power task, TIP task) of the optimal load for exerting maximum anaerobic power. Each task was finished when the exerted maximal power was decreased to 80% of the initial value. While performing each task, transcranial magnetic stimulation (TMS) was delivered to the motor cortex which was effectively able to evoke motor evoked potential (MEP) from the thigh muscles. Elec-tromyographic (EMG) activity of the left rectos femoris (RF), vastus lateralis (VL) and the MEP was analyzed.
The maximal power exerted was decreased to 80.6±1.58 % in the HF task, and 77.3±0.77 % in the HP task. The number of repeated sets in each task was 10.1 ± 1.45 (HF task) and 4.1±0.25 sets (HP task) . The MEP area of the RF and VL was not changed significantly in the HF task, though it was significantly increased in the latter half of the HP task. A two-way ANOVA showed that the time course of the changes in the MEP area was significant in the VL (p<0.01), but not in the RF. In both tasks, the duration of the MEP was progressively prolonged in each 10 sec pedaling, and the prolongation was evident in the latter half of the tasks. However, the magnitude of the prolongation was significantly larger during the HP task. The ratio of the integrated amplitude of the EMG and the exerted power at the initial 5 bouts of cycling (EMG/Power ratio) was significantly increased in both the RF and VL, suggesting that peripheral muscular fatigue was induced during at the latter half of each task. Furthermore, the EMG/Power ratio in the VL was significantly higher during the HP task than the HF task.
These results suggest that central fatigue plays a significant role in decreasing the maximum power output, and that it takes place in a muscle-dependent fashion. It was also suggested that during low load, but relatively higher cadence frequency, central fatigue other than that involving the motor cortex accounts for the decreased power output.


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