Biomedical subjects

Atsuya Takeda

Publications and source records attributed to Atsuya Takeda.

11 recordsLinked to original sources

PubMed2006

Radiation therapy after breast-conserving surgery.

The authors critically reviewed previous articles concerning the significance of breast irradiation following breast-conserving surgery in terms of the following subject items: indications for breast-conserving therapy, the significance and complications of breast irradiation, the timing of the start of breast irradiation, the significance of boost irradiation, the potential improvement of survival with systemic therapy plus breast irradiation, the significance of axillary dissection, indications and the significance of regional nodal irradiation, accelerated hypofractionated radiotherapy, omission of breast irradiation in low-risk patients, and future directions. In addition, our previously reported results of breast irradiation following breast-conserving surgery at the Keio University Hospital are outlined. Our newly developed tangential irradiation technique directed to the axilla and a recently introduced three-dimensional simulation technique for radiotherapy treatment planning are also presented.

Breast↗

PubMed2006

Rotational and translational reproducibility of newly developed Leksell frame-based relocatable fixation system.

PURPOSE: The aim of this study was to evaluate three-dimensional movement of the cranium in a relocatable frame using positions of anatomical landmarks obtained from repeated quality-assurance (QA) computed tomography (CT) studies. MATERIALS AND METHODS: We analyzed 17 series of QA-CT data representing five patients who underwent stereotactic radiotherapy for treatment of acoustic neurinoma. Helical-CT scans with 1-mm collimation were obtained at the time of treatment planning and during the course of treatment. The right and left short processes of the incus and the top of the crista galli were used as the three anatomical reference points. RESULTS: Fluctuations in distance among the reference points were all <1 mm. The translational displacements for these points were <2 mm, with standard deviations (SD) of <2 mm. A plane that included all three reference points was defined as the reference plane. To investigate the direction of cranial rotation for each QA-CT scan, unit normal vectors of the reference plane were obtained. Three-dimensional analyses indicated that cranial rotation was greatest along the X-axis, followed by the Y-axis, with the least rotation along the Z-axis. CONCLUSION: The result suggested that movement of the craniocaudal axis in the sagittal plane was a major factor behind displacement of the cranium.

Adult↗

PubMed2005

Small lung tumors: long-scan-time CT for planning of hypofractionated stereotactic radiation therapy--initial findings.

PURPOSE: To prospectively use long-scan-time computed tomography (CT) to visualize the trajectory of tumor movements or the internal target volume. MATERIALS AND METHODS: The study was approved by the institutional review board. Written informed consent was obtained from participants after the study and the role of procedures were explained fully. During the planning of stereotactic radiation therapy for 10 patients (nine men, one woman; mean age, 77 years; range, 69-89 years) with small lung tumors (mean volume, 9.0 cm3; range, 3.6-24.9 cm3), fluoroscopic imaging, long-scan-time CT, and thin-section CT were performed. The tumor and the partial-volume-averaging effects that resulted from tumor movement were delineated on each section at long-scan-time CT performed during the patient's steady breathing with scan time of 8 seconds per image. Visualized internal target volume was defined by integrating the sections. A simple model was examined for estimating internal target volume on the basis of respiratory motion and gross target volume delineated on thin-section CT images. Visualized internal target volume and estimated internal target volume were compared quantitatively and graphically. The Mann-Whitney test was used to analyze the relation between gross target volume delineated on thin-section CT images and the ratio of visualized internal target volume to the defined gross target volume. RESULTS: The correlation coefficient between visualized internal target volume and estimated internal target volume was r = 0.98 (P < .001). The mean relative error +/- standard deviation was 1.9% +/- 19.0 (range, -11.0% to 56.4%). Excluding one case with an irregularly shaped tumor (56.4%), the mean relative error was -4.1% +/- 4.1. In patients with small tumors (defined gross target volume, < or = 10 cm3), the ratio of the visualized internal target volume to the defined gross tumor volume was significantly larger than that in patients with larger tumors (1.2-2.0 vs 1.0-1.2; P < .05). In some cases in which marginal spiculation depicted on thin-section CT images was blurred on long-scan-time CT images, the blurred area was erroneously excluded from the target volume. CONCLUSION: In most cases, values for visualized internal target volume and estimated internal target volume were similar and long-scan-time CT depicted virtually the entire tumor trajectory.

Aged↗

PubMed2005

Differences in pulmonary function before vs. 1 year after hypofractionated stereotactic radiotherapy for small peripheral lung tumors.

PURPOSE: To evaluate long-term pulmonary toxicity of stereotactic radiotherapy (SRT) by pulmonary function tests (PFTs) performed before and after SRT for small peripheral lung tumors. METHODS AND MATERIALS: A total of 17 lesions in 15 patients with small peripheral lung tumors, who underwent SRT between February 2000 and April 2003, were included in this study. Twelve patients had primary lung cancer, and 3 patients had metastatic lung cancer. Primary lung cancer was T1-2N0M0 in all cases. Smoking history was assessed by the Brinkman index (number of cigarettes smoked per day multiplied by number of years of smoking). Prescribed radiation doses at the 80% isodose line were 40-60 Gy in 5-8 fractions. PFTs were performed immediately before SRT and 1 year after SRT. Test parameters included total lung capacity (TLC), vital capacity (VC), forced expiratory volume in 1 s (FEV1.0), and diffusing capacity of lung for carbon monoxide (DLCO). PFT changes were evaluated in relation to patient- and treatment-related factors, including age, the Brinkman index, internal target volume, the percentages of lung volume irradiated with >15, 20, 25, and 30 Gy (V15, V20, V25, and V30, respectively), and mean lung dose. RESULTS: There were no significant changes in TLC, VC, or FEV1.0 before vs. after SRT. The mean percent change from baseline in DLCO was significantly increased by 128.2%. Univariate and multivariate analyses revealed a correlation between DLCO and the Brinkman index. CONCLUSIONS: One year after SRT as compared with before SRT, there were no declines in TLC, VC, and FEV1.0. DLCO improved in patients who had been heavy smokers before SRT, suggesting a correlation between DLCO and smoking cessation. SRT seems to be tolerable in view of long-term lung function.

Aged↗

PubMed2004

Treatment of breast carcinoma in patients with clinically negative axillary lymph nodes using radiotherapy versus axillary dissection.

BACKGROUND: The role of axillary lymph node dissection (AxD) for patients with breast carcinoma who have clinically negative lymph nodes (cN0) and undergo breast-conserving therapy has been controversial. If patients do not undergo AxD, then it is uncertain whether specific lymph node irradiation should be given. The authors compared the results obtained from patients w ho underwent AxD with the results from patients who received axillary irradiation (AxR) using one of two radiotherapy techniques. METHODS: Patients with T1-T2cN0 breast carcinoma were treated from 1983 to 2002 with either AxD (80 patients) or AxR (1134 patients received tangential-field [2-field] irradiation, and 303 patients received 3-field irradiation). The median follow-up was 161 months for the AxD group and 66 months for the AxR group (55 months for patients who received tangential-field irradiation, and 122 months for patients who received 3-field irradiation). RESULTS: One patient in the AxD group and 35 patients in the AxR group had axillary recurrences. The 10-year cumulative axillary recurrence rates were 1.3% and 4.6% for the AxD group and the AxR group, respectively (P = 0.21). For patients with T1 tumors, the 10-year overall survival rates for the two groups were 94.7% and 92.7%, respectively (P = 0.34); and, for patients with T2 tumors, the 10-year overall survival rates were 92.5% and 89.1%, respectively (P = 0.34). In the AxR group, the 5-year axillary recurrence rates were 2.5% for patients who received tangential-field irradiation and 1.7% for patients who received 3-field irradiation (P = 0.18), and the 5-year regional recurrence rates for the two groups were 4.8% and 2.4%, respectively (P = 0.048). On multivariate analysis, positive lymphovascular invasion, outer tumor location, and larger tumor size were significant risk factors for regional failure. CONCLUSIONS: For patients with cN0 breast carcinoma, AxD and AxR yielded the same overall survival rates. Most patients can be treated safely with tangential-field irradiation alone. Patients who are at increased risk of regional failure may benefit from three-field irradiation.

Adult↗

PubMed2004

Stereotactic hypofractionated high-dose irradiation for stage I nonsmall cell lung carcinoma: clinical outcomes in 245 subjects in a Japanese multiinstitutional study.

BACKGROUND: Stereotactic irradiation (STI) has been actively performed using various methods to achieve better local control of Stage I nonsmall cell lung carcinoma (NSCLC) in Japan. The authors retrospectively evaluated results from a Japanese multiinstitutional study. METHODS: Patients with Stage I NSCLC (n = 245; median age, 76 years; T1N0M0, n = 155; T2N0M0, n = 90) were treated with hypofractionated high-dose STI in 13 institutions. Stereotactic three-dimensional treatment was performed using noncoplanar dynamic arcs or multiple static ports. A total dose of 18-75 gray (Gy) at the isocenter was administered in 1-22 fractions. The median calculated biologic effective dose (BED) was 108 Gy (range, 57-180 Gy). RESULTS: During follow-up (median, 24 months; range, 7-78 months), pulmonary complications of National Cancer Institute-Common Toxicity Criteria Grade > 2 were observed in only 6 patients (2.4%). Local progression occurred in 33 patients (14.5%), and the local recurrence rate was 8.1% for BED > or = 100 Gy compared with 26.4% for < 100 Gy (P < 0.05). The 3-year overall survival rate of medically operable patients was 88.4% for BED > or = 100 Gy compared with 69.4% for < 100 Gy (P < 0.05). CONCLUSIONS: Hypofractionated high-dose STI with BED < 150 Gy was feasible and beneficial for curative treatment of patients with Stage I NSCLC. For all treatment methods and schedules, local control and survival rates were better with BED > or = 100 Gy compared with < 100 Gy. Survival rates in selected patients (medically operable, BED > or = 100 Gy) were excellent, and were potentially comparable to those of surgery.

Adult↗

PubMed2004

Evaluation of novel modified tangential irradiation technique for breast cancer patients using dose-volume histograms.

PURPOSE: We have previously reported that entire axillary lymph node regions could be irradiated by the modified tangential irradiation technique (MTIT). In this study, MTIT was compared with a conventional irradiation technique (CTIT) using dose-volume histograms to verify how adequately MTIT covers the breast and axillary lymph node region and the extent to which it involves the lung and heart. METHODS AND MATERIALS: Forty-four patients with early-stage breast cancer were treated by lumpectomy, axillary dissection, and postoperative radiotherapy. Twenty-two patients were treated with MTIT and 22 with CTIT. In 25 patients, the breast tumor was on the left and in 19 on the right. During axillary dissection, surgical clips were left as markers at the border of the axillary lymph node region. MTIT was planned by setting the dorsal edge of the radiation field on a lateral-view simulator film at the dorsal edge of the humeral head and the cranial edge of the radiation field at the caudal edge of the humeral head. CTIT was planned to ensure radiation of the breast tissue without considering the axillary region. In this study, all patients underwent computed tomography, and the CT data were transmitted on-line to a radiotherapy planning system, in which the dose-distribution computed tomography images and dose-volume histograms were calculated by defining the breast, axillary region (levels I, II, and III), lung, and heart region. RESULTS: Dose-volume histogram analysis demonstrated that breast tissue was radiated with an 86.5-100% volume (median 96.5%) by MTIT and an 83-100% volume (median, 95%) by CTIT at >95% of the isocenter dose. The axillary lymph node regions at Levels I, II, and III were irradiated with 84-100% (median, 94.5%), 59-100% (median, 89%), and 70-100% (median, 89.5%) volumes, respectively, by MTIT and with 2-84% (median, 38%), 0-53% (median, 15%), and 0-31% (median, 0%) volumes, respectively, by CTIT at >70% of the isocenter dose. The ipsilateral lung was irradiated with a 5-22% volume (median, 11.5%) by MTIT and 5-15% volume (median 9%) by CTIT at >90% of the isocenter dose. In all 25 left-sided breast cancer patients, the volumes irradiated with an 80% isocenter dose were <30 cm(3). CONCLUSION: The results of our study demonstrated that the breast tissue was sufficiently irradiated with both CTIT and MTIT planning, the axillary lymph node areas irradiated by MTIT were much wider than those irradiated by CTIT at all levels, and the lung and heart volumes irradiated by MTIT were small.

Adult↗

PubMed2004

Measurement of beam-axis displacement from the isocenter during three-dimensional conformal radiosurgery with a micro-multileaf collimator.

We describe the displacement of the beam-axis from the planning isocenter in clinical situations during three-dimensional conformal radiosurgery using an Acculeaf bi-directional micro-multileaf collimator. The displacements were recorded for 64 ports using a video imaging system and a stereotactic arc. The mean displacement was 0.41+/-0.25 mm.

Brain Neoplasms↗

PubMed2004

Radiation injury after hypofractionated stereotactic radiotherapy for peripheral small lung tumors: serial changes on CT.

OBJECTIVE: We studied the serial changes and CT manifestations of pulmonary radiation injury after hypofractionated stereotactic radiation therapy for peripheral small lung tumors. SUBJECTS AND METHODS. Hypofractionated stereotactic radiation therapy was applied to 20 patients with proven primary (n = 11) or metastatic (n = 9) lung cancer, for a total of 22 lesions of 3 cm or less in diameter located within 3 cm from the parietal pleural surface. Follow-up CT was scheduled at 1 and 3 months, and every 3 months thereafter. RESULTS: Ground-glass opacities were observed around four (18%) of 22 lesions at 3-6 months. The opacities nearly corresponded to the planned target volume, but half of them were unevenly distributed. Ground-glass opacities gradually disappeared or evolved into dense consolidation while shrinking. Dense consolidations developed in 16 (73%) of 22 lesions, including seven in the center of the planned target volume and nine in the periphery of the planned target volume. Dense consolidations moved in six of these 16 lesions and gradually shrank, becoming fixed as solid or linear opacities approximately 12 months later. CONCLUSION: The pulmonary opacities observed after hypofractionated stereotactic radiation therapy for peripheral small lung tumors may not precisely correspond to the planned target volume (unlike those with conventional radiation therapy) and may change in shape and location dynamically during the first year. Knowledge of these findings is necessary to avoid misunderstandings concerning tumor regrowth or new tumors.

Aged↗

PubMed2002

Intra-arterial CT-angiography for cerebral arteriovenous malformation--initial experiences for treatment planning of radiosurgery.

PURPOSE: To clarify the feasibility and effectiveness of intra-arterial CT angiography (IACTA) for treatment planning of arteriovenous malformation radiosurgery. METHODS AND MATERIALS: A CT scanner installed in an angiographic examination room was used. Helical IACTA was performed in 22 patients during continuous intra-arterial infusion of contrast medium via the internal carotid or vertebral artery, and dynamic IACTA was performed in 20 of these patients with reconstruction at 0.2-s intervals. The dynamic IACTA was repeated for each 3- or 5-mm increment to encompass the nidus. Subtractions were performed in postembolization cases. A retrospective review of IACTA was performed to assess the effectiveness of dynamic scans. RESULTS: No complications related to the angiographic procedure or CT imaging were detected. High contrast enhancement was obtained for both helical and dynamic IACTA. In 18 of the 20 cases (90%), draining veins were separated from the nidus by using the enhancement patterns, and in 13 cases (65%), feeding arteries were separated. CONCLUSION: Dynamic IACTA added important information for target-volume determinations. Conventional CT and MRI could be omitted from the protocol, and the period that patients wore the frame was substantially shortened. We conclude that IACTA is a practical and useful method for radiosurgical treatment planning of arteriovenous malformations.

Adolescent↗

PubMedDate not supplied

Successful pregnancy and normal delivery after whole craniospinal irradiation in two patients.

BACKGROUND: Two cases of normal pregnancies and deliveries after whole craniospinal irradiation (WCSI) are described, and whether the ovaries can be left out of the WCSI field by identifying ovarian position using magnetic resonance imaging (MRI) is determined. MATERIALS AND METHODS: The distance between the upper edge of the pubic symphysis and the central part of the ovary was measured on MRI in 17 women. RESULTS: The right ovary was located 20.3-68.4 mm to the right of and 33.7-113.5 mm above the upper edge of the pubic symphysis; the left ovary was located 26.2-72.5 mm to the left and 25.8-106.6 mm above this edge. The lower border of the spinal field in WCSI should be the caudal border of the thecal sac, i.e., S2-S4. The line of this location, which nearly approximates normal ovarian position, should be employed in radiotherapy planning to avoid irradiating at least one ovary with its thecal sac. Omitting this area from the WCSI field in women of childbearing age with a good long-term prognosis, preserves potential fertility. CONCLUSION: It appears that the ovaries might be excluded from the WCSI field, using appropriate techniques, so as to preserve female fertility.

Adolescent↗