Biomedical subjects

Etsuo Kunieda

Publications and source records attributed to Etsuo Kunieda.

17 recordsLinked to original sources

PubMed2006

Dosimetric verification in participating institutions in a stereotactic body radiotherapy trial for stage I non-small cell lung cancer: Japan clinical oncology group trial (JCOG0403).

A multicentre phase II trial of stereotactic body radiotherapy for T1N0M0 non-small cell lung cancer was initiated in Japan as the Japan Clinical Oncology Group trial (JCOG0403). Before starting the trial, a decision was made to evaluate the treatment machine and treatment planning in participating institutions to minimize the variations of the prescription dose between the institutions. We visited the 16 participating institutions and examined the absolute dose at the centre of a simulated spherical tumour of 3.0 cm diameter in the lung using the radiation treatment planning systems in each institution. A lung phantom for stereotactic body radiotherapy (SBRT) was developed and used for the treatment planning and film dosimetry. In the JCOG radiotherapy study group, the no model-based calculation algorithm or the model-based calculation algorithm with a dose kernel unscaled for heterogeneities were selected for use in the initial SBRT trials started in 2004, and the model-based calculation algorithm with a dose kernel scaled for heterogeneities was selected for the coming trial. The findings of this study suggest that the clinical results of lung SBRT trials should be carefully evaluated in comparison with the actual dose given to patients.

Algorithms↗

PubMed2006

Stereotactic radiosurgery plus whole-brain radiation therapy vs stereotactic radiosurgery alone for treatment of brain metastases: a randomized controlled trial.

CONTEXT: In patients with brain metastases, it is unclear whether adding up-front whole-brain radiation therapy (WBRT) to stereotactic radiosurgery (SRS) has beneficial effects on mortality or neurologic function compared with SRS alone. OBJECTIVE: To determine if WBRT combined with SRS results in improvements in survival, brain tumor control, functional preservation rate, and frequency of neurologic death. DESIGN, SETTING, AND PATIENTS: Randomized controlled trial of 132 patients with 1 to 4 brain metastases, each less than 3 cm in diameter, enrolled at 11 hospitals in Japan between October 1999 and December 2003. INTERVENTIONS: Patients were randomly assigned to receive WBRT plus SRS (65 patients) or SRS alone (67 patients). MAIN OUTCOME MEASURES: The primary end point was overall survival; secondary end points were brain tumor recurrence, salvage brain treatment, functional preservation, toxic effects of radiation, and cause of death. RESULTS: The median survival time and the 1-year actuarial survival rate were 7.5 months and 38.5% (95% confidence interval, 26.7%-50.3%) in the WBRT + SRS group and 8.0 months and 28.4% (95% confidence interval, 17.6%-39.2%) for SRS alone (P = .42). The 12-month brain tumor recurrence rate was 46.8% in the WBRT + SRS group and 76.4% for SRS alone group (P<.001). Salvage brain treatment was less frequently required in the WBRT + SRS group (n = 10) than with SRS alone (n = 29) (P<.001). Death was attributed to neurologic causes in 22.8% of patients in the WBRT + SRS group and in 19.3% of those treated with SRS alone (P = .64). There were no significant differences in systemic and neurologic functional preservation and toxic effects of radiation. CONCLUSIONS: Compared with SRS alone, the use of WBRT plus SRS did not improve survival for patients with 1 to 4 brain metastases, but intracranial relapse occurred considerably more frequently in those who did not receive WBRT. Consequently, salvage treatment is frequently required when up-front WBRT is not used. TRIAL REGISTRATION: umin.ac.jp/ctr Identifier: C000000412.

Adult↗

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↗

PubMed2006

Value of CT thallium-201 SPECT fusion imaging over SPECT alone for detection and localization of nasopharyngeal and maxillary cancers.

OBJECTIVE: The purpose of this study was to investigate the incremental clinical utility of CT and high-resolution SPECT fusion imaging. MATERIALS AND METHODS: Eighteen patients with nasopharyngeal cancer or cancers around the maxilla were scanned with high-resolution SPECT at the time of initial diagnosis (18 studies) and during follow-up after chemoradiotherapy (23 studies). SPECT results were compared with histologic findings or the findings of other imaging techniques. In addition, automatic image registration without fiducial markers was performed from CT and SPECT data, and the effect of fusion imaging on the localization of abnormalities was evaluated. RESULTS: All of the original 18 untreated lesions showed high uptake. Recurrent tumors had a tendency to show high uptake (seven of nine patients), whereas little or no uptake generally represented no recurrence (12 of 14 patients) (chi-square test with Yates correction: chi2 = 6.80, p < 0.01). In two patients, physiologic uptake in the unilateral prevertebral muscle was revealed on image fusion. In four of the nine recurrent nasopharyngeal cancers (44%), SPECT alone could not determine abnormalities in uptake sites, whereas CT/SPECT fusion imaging clearly localized the sites and was helpful for treatment strategy. CONCLUSION: High-resolution thallium-201 (201Tl) SPECT has a very high detection rate in patients with nasopharyngeal cancer and cancers around the maxilla. However, the anatomic identification or localization of the uptake sites is sometimes difficult without CT/SPECT fusion imaging. This technique without external markers is practically feasible to generate clinically valid fusion images.

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

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

Development of realistic high-resolution whole-body voxel models of Japanese adult males and females of average height and weight, and application of models to radio-frequency electromagnetic-field dosimetry.

With advances in computer performance, the use of high-resolution voxel models of the entire human body has become more frequent in numerical dosimetries of electromagnetic waves. Using magnetic resonance imaging, we have developed realistic high-resolution whole-body voxel models for Japanese adult males and females of average height and weight. The developed models consist of cubic voxels of 2 mm on each side; the models are segmented into 51 anatomic regions. The adult female model is the first of its kind in the world and both are the first Asian voxel models (representing average Japanese) that enable numerical evaluation of electromagnetic dosimetry at high frequencies of up to 3 GHz. In this paper, we will also describe the basic SAR characteristics of the developed models for the VHF/UHF bands, calculated using the finite-difference time-domain method.

Body Height↗

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↗

PubMed2003

[Visualization of intracranial arteriovenous malformation using multivariate analysis].

Intracranial arteriovenous malformations(AVMs) are composed of native deformed vessels where arteries and veins are directly connected in the absence of capillary vessels, and have a complicated three-dimensional(3D) shape. The purpose of this study was to define precisely the location of AVM areas for stereotactic irradiation. The proposed method used a sequence of dynamic X-ray CT images with contrast and opaque media. We analyzed these images by a principal component analysis(PCA) method and extracted component images: artery, vein, and background images. Then we made a fusion image with these three images and displayed the AVM areas. Results showed that the proposed method could identify the physiological location of these AVMs areas. Furthermore, we reconstructed 3D fusion images using two-dimensional component images extracted by the PCA method.

Angiography, Digital Subtraction↗

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↗

PubMed2002

Dose distribution of narrow beam irradiation for small lung tumor.

PURPOSE: To aid in the selection of incident X-ray energy for stereotactic irradiation (STI) of lung tumor, dose distribution was investigated in a model of a thorax embedded with a tumor. METHODS AND MATERIALS: The dose distribution in a thorax model was calculated using the EGS4 Monte Carlo simulation; it was also measured with dosimetric film of a tentative thorax phantom. Uniformity of dose distribution in a tumor region was compared among the results of irradiation for several X-ray energies, and optimal X-ray energy for STI of a lung tumor was discussed. RESULTS: Dose distributions in the thorax were obtained. An increase in X-ray energy led not only to an increased dose delivered to the tumor, but also to an increased dose to surrounding normal lung tissue. CONCLUSIONS: The flat range in dose distribution along the beam axis and in the beam profiles of the tumor increases with decreasing X-ray energy. Consequently, lower energy, rather than higher energy, is recommended for STI of a lung tumor in terms of higher uniformity in the target volume.

Computer Simulation↗

PubMedDate not supplied

Adenoid cystic carcinoma with hyperostosis after stereotactic radiosurgery.

Adenoid cystic carcinoma (ACC) of the head and neck is a relatively rare tumor characterized by slow evolution, recurrences, and protracted clinical course. We performed stereotactic radiosurgery in order to palliate symptoms for intraorbital recurrence of ACC that had been treated with total resection of the left parotid gland, radical neck dissection, and conventionally fractionated radiotherapy. We experienced interesting hyperostosis in the area irradiated by the stereotactic radiosurgery.

Carcinoma, Adenoid Cystic↗

PubMedDate not supplied

Effects of density changes in the chest on lung stereotactic radiotherapy.

To experimentally and theoretically evaluate dose distribution during lung stereotactic radiotherapy, we investigated the relative electron densities in lung and tumor tissues using X-ray computed tomography images obtained from 30 patients in three breathing states: free breathing, inspiration breath-hold, and expiration breath-hold. We also calculated dose distribution using Monte Carlo simulation for lung tissue with two relative electron densities. The effect of changes in relative electron density on dose distribution in lung tissue was evaluated using calculated differential and integral dose volume histograms. The relative electron density of lung tissue was 0.22 in free breathing, 0.23 in shallow expiration, and 0.17 in shallow inspiration, and there was a tendency for relative electron density to decrease with age. The relative electron density of tumor tissue was approximately 0.9, with little variation due to differences in breathing state. As the relative electron density of lung tissue decreases, the low-dose region expands and leads to changes in the marginal dose.

Age Factors↗

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↗