Persistent left superior vena cava into left atrium.
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Adult↗
Biomedical subjects
Takashi Mizowaki
Publications and source records attributed to Takashi Mizowaki.
Development of a four-dimensional image-guided radiotherapy system with a gimbaled X-ray head.
PURPOSE: To develop and evaluate a new four-dimensional image-guided radiotherapy system, which enables precise setup, real-time tumor tracking, and pursuit irradiation. METHODS AND MATERIALS: The system has an innovative gimbaled X-ray head that enables small-angle (+/-2.4 degrees ) rotations (pan and tilt) along the two orthogonal gimbals. This design provides for both accurate beam positioning at the isocenter by actively compensating for mechanical distortion and quick pursuit of the target. The X-ray head is composed of an ultralight C-band linear accelerator and a multileaf collimator. The gimbaled X-ray head is mounted on a rigid O-ring structure with an on-board imaging subsystem composed of two sets of kilovoltage X-ray tubes and flat panel detectors, which provides a pair of radiographs, cone beam computed tomography images useful for image guided setup, and real-time fluoroscopic monitoring for pursuit irradiation. RESULTS: The root mean square accuracy of the static beam positioning was 0.1 mm for 360 degrees of O-ring rotation. The dynamic beam response and positioning accuracy was +/-0.6 mm for a 0.75 Hz, 40-mm stroke and +/-0.4 mm for a 2.0 Hz, 8-mm stroke. The quality of the images was encouraging for using the tomography-based setup. Fluoroscopic images were sufficient for monitoring and tracking lung tumors. CONCLUSIONS: Key functions and capabilities of our new system are very promising for precise image-guided setup and for tracking and pursuit irradiation of a moving target.
Equipment Design↗
[Evaluation of setup error and adequate setup margins in patients with prostate cancer treated by IMRT and fixed in the prone position using a set of immobilization devices].
PURPOSE: Positional reproducibility in patients with prostate cancer fixed in the prone position with a set of immobilization devices for external-beam intensity-modulated radiation therapy (IMRT) was evaluated. In addition, the adequacy of our positional error reduction strategy and current planning target volume (PTV) margins was also evaluated. RESULTS: Systematic error was corrected by the positional correction that we executed at the first stage of irradiation. The setup margin that we had calculated was 1.1 mm in the L-R direction, 1.3 mm in the A-P direction, and 2.7 mm in the C-C direction. CONCLUSION: We determined that the effectiveness of the method of correcting the error margin and the setup accuracy of the fixed method were well maintained.
Humans↗
Results of radiation therapy combined with neoadjuvant hormonal therapy for stage III prostate cancer: comparison of two different definitions of PSA failure.
BACKGROUND: We herein report the clinical outcome of radical radiation therapy combined with neoadjuvant hormonal therapy (NHT) for stage III (International Union Against Cancer [UICC] 1997: UICC 97) prostate cancer. Prostate-specific antigen (PSA) failure-free survival was assessed according to two different definitions, and the appropriateness of each definition is discussed. METHODS: Between October 1997 and December 2000, 27 patients with stage III prostate cancer were enrolled in this study. The median pretreatment PSA level was 29 ng/ml (range, 7.4-430 ng/ml). The Gleason score (GS) was 7 or more in 22 patients (81%). All patients received 3 months of NHT with a luteinizing hormone-releasing hormone (LH-RH) analogue, in combination with an antiandrogen (flutamide), given during the first 2 weeks, followed by 70-Gy external-beam radiation therapy (EBRT) in 35 fractions. The initial 46 Gy was given with a four-field technique, while the remainder was given with a dynamic conformal technique. No adjuvant hormonal therapy (AHT) was given. RESULTS: The median follow-up time was 63 months. PSA levels decreased to the normal range (<4 ng/ml) after irradiation in all but one patient. The 5-year PSA failure-free survival was 34.8% according to the American Society for Therapeutic Radiology and Oncology (ASTRO) definition and it was 43.0% according to the "nadir plus 2" definition. Discordance of the results between the two definitions was seen in two patients. The 5-year overall and cause-specific survivals were 83.0% and 93.3%, respectively. No severe acute or late adverse effects were observed. CONCLUSION: Seventy Gy of EBRT following 3 months of NHT produced therapeutic results comparable to those reported in other studies which used long-term AHT. The value of long-term AHT for Japanese men should be tested in a clinical trial.
Adenocarcinoma↗
Initial experiences of palliative stereotactic radiosurgery for recurrent brain lymphomas.
In Kyoto University Hospital, stereotactic radiosurgery (SRS) has been performed for its rapid palliative effect in patients with recurrent primary central nervous system lymphoma (PCNSL), often in combination with salvage chemotherapy. In the present study, the treatment outcome and toxicity of SRS for recurrent PCNSL was retrospectively evaluated. Between March 1998 and June 2004, 17 histologically proven recurrent PCNSLs in nine patients were treated with linac-based stereotactic radiosurgery. All patients had developed intracranial recurrences after initial treatment including external beam radiation therapy (EBRT). The prescribed dose was 10.0-16.0 (median 12.0) Gy. Seven of nine patients received systemic chemotherapy around the time of SRS. The target volume was 0.4-24.5 ml (median 3.5 ml). Initial tumor response could be evaluated in 15 of 17 lesions. Among them, radiological complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD) was observed in 3, 10, 2, and 0 lesions, respectively. One-year overall survival rate and relapse-free survival rate after first SRS was 58% and 22%, respectively. Improvement of symptoms was observed in six patients. The time from SRS to symptomatic relief was 1-57 days (median 3 days). No > or = grade 2 acute toxicities related to SRS were observed. In conclusion, linac-based SRS with a prescription dose of 10-12 Gy for recurrent PCNSL is useful for palliation, especially considering the short time, rapid tumor response, and low treatment toxicity.
Aged↗
[Stereotactic body radiotherapy (SBRT)].
The techniques of three-dimensional conformal radiotherapy (3 D-CRT) and patient immobilization have recently been developed, enabling us to focus high doses on the target with relatively less irradiation of normal tissues. In radiotherapy for solitary lung tumors, the local control may be safely improved by delivering a higher dose at only the target volume using these techniques. Recently, several clinical studies on stereotactic body radiotherapy (SRT) using the 3 D-CRT technique for solitary lung tumors have been reported. The single dose used is 10-15 Gy, and the total sessions are three to five. The local control rate is more than 90% and complication rates are very low. Therefore, this treatment is a promising new non-invasive treatment for early stage lung cancer. A multi-institutional clinical study, JCOG 0403, in now underway.
Early Diagnosis↗
Chemoradiotherapy in patients with pancreatic carcinoma: phase-I study with a fixed radiation dose and escalating doses of weekly gemcitabine.
AIM: The aim of this phase-I study is to determine the maximum tolerated dose (MTD) of weekly gemcitabine in concurrent combination with a total radiation dose of 54 Gy in patients with pancreatic cancer. METHODS: In all patients, a total dose of 54 Gy was delivered in 30 fractions of 1.8 Gy/day. Gross tumor volume and regional lymph nodes were included in the irradiated volume with a 1- to 1.5-cm margin. The doses of weekly gemcitabine were escalated from 100 mg/m2 by increments of 50 mg/m2. Dose-limiting toxicity (DLT) was defined as hematologic toxicity, prolonged grade-3 non-hematologic toxicity, and incompletion of the planned treatment. RESULTS: Twenty-six patients entered the trial. From level 1 (100 mg/m2) to level 4 (250 mg/m2), no patient experienced DLT except for 1 patient at level 1. At level 5 (300 mg/m2), 3 of the 5 patients met the DLT criteria. One patient developed severe pulmonary abscess, and the other 2 patients had hematologic DLT. The overall partial response rate was 29%, and the median survival time was 13.7 months. The first relapse occurred at the in-field primary site in 6 patients and at distant organs in 13 patients. CONCLUSION: The MTD of weekly gemcitabine was 250 mg/m2 in the present chemoradiotherapy setting. The efficacy of this chemoradiotherapy regimen is currently being evaluated in the phase-II setting.
Adult↗
Clinical outcomes of a phase I/II study of 48 Gy of stereotactic body radiotherapy in 4 fractions for primary lung cancer using a stereotactic body frame.
PURPOSE: To evaluate the clinical outcomes of 48 Gy of three-dimensional stereotactic radiotherapy in four fractions for treating Stage I lung cancer using a stereotactic body frame. METHODS AND MATERIALS: Forty-five patients who were treated between September 1998 and February 2004 were included in this study. Thirty-two patients had Stage IA lung cancer, and the other 13 had Stage IB lung cancer where tumor size was less than 4 cm in diameter. Three-dimensional treatment planning using 6-10 noncoplanar beams was performed to maintain the target dose homogeneity and to decrease the irradiated lung volume >20 Gy. All patients were irradiated using a stereotactic body frame and received four single 12 Gy high doses of radiation at the isocenter over 5-13 (median = 12) days. RESULTS: Seven tumors (16%) completely disappeared after treatment (CR) and 38 tumors (84%) decreased in size by 30% or more (PR). Therefore, all tumors showed local response. During the follow-up of 6-71 (median = 30) months, no pulmonary complications greater than an National Cancer Institute-Common Toxicity Criteria of Grade 3 were noted. No other vascular, cardiac, esophageal, or neurologic toxicities were encountered. Forty-four (98%) of 45 tumors were locally controlled during the follow-up period. However, regional recurrences and distant metastases occurred in 3 and 5 of T1 patients and zero and 4 of T2 patients, respectively. For Stage IA lung cancer, the disease-free survival and overall survival rates after 1 and 3 years were 80% and 72%, and 92% and 83%, respectively, whereas for Stage IB lung cancer, the disease-free survival and overall survival rates were 92% and 71%, and 82% and 72%, respectively. CONCLUSION: Forty-eight Gy of 3D stereotactic radiotherapy in 4 fractions using a stereotactic body frame is useful for the treatment of Stage I lung tumors.
Adenocarcinoma↗
Long-term results of definitive radiotherapy for stage I esophageal cancer.
PURPOSE: To analyze retrospectively the long-term results of external beam radiotherapy (RT) with or without intraluminal brachytherapy (ILBT) for patients with Stage I esophageal cancer. METHODS AND MATERIALS: A total of 34 patients with esophageal squamous cell carcinoma, clinically diagnosed as having Stage I disease, were treated with definitive RT, with or without ILBT. The median age was 69 years. Seven patients were treated with external beam RT alone (median, 64 Gy), and 27 were treated with external beam RT (median, 52 Gy) plus ILBT (8-12 Gy in two to three fractions). RESULTS: The 5-year overall survival, local relapse-free survival, and cause-specific survival rate was 58.9%, 68.4%, and 80.0%, respectively, with a median follow-up of 61 months. Of 9 patients with local recurrence after initial therapy, 7 were successfully treated, and the 5-year cumulative rate of esophagectomy was 19.6%. The 2-year local relapse-free rate for patients with and without ILBT was 79.1% and 53.6%, respectively. CONCLUSION: Although local recurrence was frequent within 2 years, the disease-specific survival rate was high owing to effective salvage therapy. Definitive RT is a reasonable treatment option for highly comorbid and elderly patients with Stage I esophageal cancer. The role of ILBT needs to be clarified.
Aged↗
Treatment planning of stereotactic radiotherapy for solitary lung tumor.
PURPOSE: To analyze the stereotactic radiotherapy (SRT) plans in terms of internal target volume (ITV) and organs at risk (OARs). METHODS AND MATERIALS: Treatment planning and dose distributions were analyzed using dose-volume histograms (DVHs) of ITV and OARs in 37 patients, who were treated for a solitary lung tumor with SRT. The stereotactic body frame (SBF) was used for immobilization and accurate setup. Prescription dose was 48 Gy in four fractions at the isocenter. RESULTS: Use of SBF limits the extent of the noncoplanar beam directions to prevent a collision with the Linac gantry. DVH analyses showed that the homogeneity index, defined as the ratio of maximum and minimum dose to ITV, ranged from 1.03 to 1.25 (mean, 1.12). The volume irradiated with 20 Gy or more (V(20)) of the lung ranged from 0.3 to 11.6% (mean, 4.4%) of the whole lung volume. The maximum dose to the other OARs ranged from 0 to 11.8 Gy (mean, 0.5-2.7) per fraction. No clinically significant complications were encountered. CONCLUSIONS: Despite the limitation of the beam arrangement, a homogeneous target dose distribution, while avoiding high doses to normal tissues, was obtained.
Bronchi↗
Comparison of three radiotherapy treatment planning protocols of definitive external-beam radiation for localized prostate cancer.
BACKGROUND: Three radiotherapy treatment planning (RTTP) protocols for definitive external-beam radiation for localized prostate cancer, designed and clinically applied at Kyoto University, were compared. METHODS: Treatment plans were created according to three different RTTP protocols (old three-dimensional conformal radiotherapy [3D-CRT], new 3D-CRT, and intensity-modulated radiotherapy [IMRT]) on computed tomography (CT) data sets of five patients with localized prostate cancer. The dynamic-arc conformal technique was used in the 3D-CRT protocols. Differences in dose distribution were evaluated and compared based on dose-volume histogram (DVH) analyses. RESULTS: The coverage of the clinical target volume (= prostate alone) was comparable among the three RTTP protocols. However, the average values for the percent volume that received at least 95% of the prescription dose (V95), the percent of the prescription dose covering 95% of the volume (D95), and the conformity index of the planning target volume (PTV) were 99%, 97%, and 0.88 for the IMRT; 93.9%, 94.5%, and 0.76 for the new 3D-CRT; and 59.6%, 82.9%, and 0.6 for the old 3D-CRT protocol, respectively. Inhomogeneity of doses to the PTV was larger with the IMRT protocol than with the new 3D-CRT protocol. Doses to both the rectal wall and bladder wall were almost comparable with the new 3D-CRT and IMRT protocols, but were lower with the old 3D-CRT protocol, due to the lowest prescription dose and incomplete dose coverage of the PTV. CONCLUSION: The old 3D-CRT protocol could not achieve the goals for the PTV set in the IMRT protocol. The new 3D-CRT and IMRT protocols were generally comparable in terms of both the PTV coverage and normal tissue-sparing, although the IMRT protocol achieved the most conformal dose distribution to the PTV, in return for a larger, but acceptable, dose inhomogeneity.
Clinical Protocols↗
Evaluation of lung injury after three-dimensional conformal stereotactic radiation therapy for solitary lung tumors: CT appearance.
PURPOSE: To evaluate the computed tomographic (CT) appearance of tumors and lung injury in patients who have undergone stereotactic radiation therapy (SRT) for solitary lung tumors. MATERIALS AND METHODS: Twenty-seven patients with primary lung cancer and four with metastatic lung cancer who underwent SRT for solitary lung tumors were enrolled for evaluation. SRT was delivered by using a three-dimensional conformal technique with a stereotactic body frame. A total dose of 48 Gy was administered in four fractions during a period of 2 weeks. After SRT, follow-up CT images were obtained every 2-3 months. Radiation-induced pulmonary injuries were classified into four patterns on CT images. The minimal lung dose to areas demonstrating pulmonary injury at CT was evaluated, and the correlation between the dose and the percentage volume of the whole lung irradiated by more than 20 Gy in total (V20) was assessed by using Spearman rank correlation. RESULTS: Tumor shrinkage continued for 2-15 months after SRT. Asymptomatic changes in the irradiated lung were noted at CT in all patients within 2-6 months (median, 4 months) after SRT. As the pattern at pulmonary CT changed, patchy consolidation was more predominantly seen as an acute change than were slight homogeneous increase in opacity, discrete consolidation, or solid consolidation; solid consolidation was the more predominantly seen late change. The minimal lung dose to the area demonstrating pulmonary injury in each patient ranged between 16 and 36 Gy (median, 24 Gy). The dose was significantly (P <.001) inversely correlated with the V20 in each patient. CONCLUSION: The reaction to SRT of the lungs seems similar to the reaction to conventional radiation therapy.
Follow-Up Studies↗
Clinical evaluation of dynamic arc conformal radiotherapy for paraaortic lymph node metastasis.
PURPOSE: This study was performed to evaluate the efficacy and safety of dynamic arc conformal radiotherapy, a simple intensity modulated radiation therapy (IMRT), for the treatment of paraaortic lymph node metastases. MATERIALS AND METHODS: Twenty-nine patients with paraaortic lymph node metastases were enrolled in this study. The total planned dose was 55-60 Gy. A computed tomography (CT) simulator was used in the treatment planning. RESULTS: The total radiation dose delivered was 50-63.4 Gy (median 60 Gy). Sixteen of 29 patients showed local tumor shrinkage on CT, and the 2 year in-field recurrence free survival rate was 58%. Acute Grade 1 and Grade 2 gastrointestinal disorders occurred in 31% and 17%, respectively, and acute Grade 2 liver dysfunction occurred in 7%. As a late complication, Grade 1 and Grade 2 liver dysfunction occurred in six patients (21%) and five patients (17%), respectively. There was no renal dysfunction or myelopathy detected. CONCLUSION: Dynamic arc conformal radiotherapy, a simple IMRT, is a safe and effective treatment method for paraaortic lymph node metastasis.
Aorta↗
Concurrent chemotherapy and radiotherapy with low-dose Cisplatin for nasopharyngeal carcinoma.
Eighty-one patients with nondisseminated nasopharyngeal carcinoma consecutively treated between January 1977 and December 1998 were analyzed to evaluate whether a concurrent adjunction of low-dose cisplatin enhances the outcome of definitive radiotherapy. Ninety-eight percent (n = 79) of the cases were ranked as stage III/IV according to the 1987 Union International Contre le Cancer staging criteria. Patients treated before 1987 and treated after 1988 were mainly managed by radiotherapy alone (historical group: n = 48) and concurrent chemoradiotherapy with relatively low-dose cisplatin (CCRT group: n = 33), respectively. The locoregional failure-free survival rate of the CCRT group was significantly better than that of the historical group (72.8% vs. 35.9% at 5 years, p = 0.0041). However, multivariate analysis identified only the total dose and the T-stage as significant independent factors for locoregional control. No difference was observed on overall, disease-specific, and distant failure-free survival between the two groups. The results of the present study suggest that concurrent adjunction of low-dose cisplatin will not improve the outcome of definitive radiotherapy for nasopharyngeal carcinoma. Full-dose concurrent chemoradiotherapy, as well as the appropriate dose escalation for better locoregional control, will be mandatory to achieve better survival.
Adult↗
Towards integrating functional imaging in the treatment of prostate cancer with radiation: the registration of the MR spectroscopy imaging to ultrasound/CT images and its implementation in treatment planning.
PURPOSE: Dose-escalation to intraprostatic tumor deposits detected by magnetic resonance spectroscopy (MRS) is an example of tumor-targeted radiation therapy. Because treatment planning for prostate brachytherapy is performed based on ultrasound (US)/computed tomography (CT) images, a sine qua non of this technique is the ability to map MRS-positive volumes (obtained in a gland deformed by the endorectal balloon coil) to the US/CT images. An empirical algorithm designed to perform this function, and its validation, are described. METHODS AND MATERIALS: Mathematically, the problem of mapping points between the MR and US/CT domains comes to: (a) ascertaining that the position of any point in the interior of the prostate is uniquely determined by the shape of the gland, and (b) finding an algorithm that describes this relationship. The image registration algorithm described here is based on the assumption that points within the gland maintain the same relative position with respect to both the axial contours of the prostate and the center of the prostate along the superior-inferior direction. Relative positions of MRS-positive voxels are calculated with this method in both MR and US/CT space. For a particular voxel in the MR space, one obtains first the z coordinate in the US/CT space, that is, along the superior-inferior direction. This determines the axial slice in the US/CT frame of reference where the other two coordinates (x, y) will be calculated. The validity of this algorithm was examined with the aid of a pelvic phantom built to simulate realistically the prostate and its surrounding bony and tissue structures and with CT scans of implanted patients obtained, at several weeks' intervals, as part of an edema-resolution study. Seventy-five "dummy" seeds were placed in the phantom, within the simulated prostate gland, in a quasi-regular pattern. The coordinates of these seeds were determined and thus served as markers of prostate deformation when an inflated rectal probe was introduced in the phantom. CT images of this phantom were taken for different volumes of the MR rectal probe and in each case the prostate outlines were contoured and seed coordinates calculated. Using these data, the predictions of the mapping algorithm could be directly verified. RESULTS: Absolute values of the 3D-positional errors in this algorithm were 2.2 mm +/- 1.2 mm (average +/- SD). Only 6 of 75 seeds had positional displacement of 4 mm or more. Similar results were obtained in the patient analysis. CONCLUSIONS: In comparison to the MRS voxel size (6.25 x 6.25 x 3.0 mm3), the present algorithm achieves the desired clinical accuracy. As well, with this 3D algorithm seed positions are reconstructed with an uncertainty that, along the z direction, is less than half the thickness of the typical US slice (0.5 cm).
Algorithms↗
Clinical outcomes of 3D conformal hypofractionated single high-dose radiotherapy for one or two lung tumors using a stereotactic body frame.
PURPOSE: This study was performed to evaluate the clinical outcomes of three-dimensional (3D) conformal hypofractionated single high-dose radiotherapy for one or two lung tumors using a stereotactic body frame. MATERIALS AND METHODS: Forty patients who were treated between July 1998 and November 2000 and were followed for >10 months were included in this study. Of the 40 patients, 31 had primary lung cancer and 9 had metastatic lung cancer. The primary lung cancer was staged as T1N0M0, T2N0M0, and T3N0M0 in 19, 8, and 4 patients, respectively. The primary sites of metastatic lung cancer were the colon in 4, tongue in 2, and osteosarcoma, lung cancer, and hepatocellular carcinoma in 1 each. 3D treatment planning was performed to maintain the target dose homogeneity within 15% and to decrease the irradiated lung volume from >20 Gy to <25%. All patients were irradiated using a stereotactic body frame and received 4 times 10-12 Gy single high-dose radiation at the isocenter during a period of 5-13 days (median 12). RESULTS: The initial 3 patients received 40, and the remaining 37 patients received 48 Gy after dose escalation. Of the 33 tumors followed >6 months, 6 tumors (18%) disappeared completely after treatment. Twenty-five tumors (76%) decreased in size by 30% or more after treatment. Therefore, 31 tumors (94%) showed a local response. During the follow-up of 4-37 months (median 19), no pulmonary complications greater than National Cancer Institute-Common Toxicity Criteria Grade 2 were noted. Of the 16 patients with histologically confirmed T1N0M0 primary lung cancer who received 48 Gy, all tumors were locally controlled during the follow-up of 6-36 months (median = 19). In 9 tumors with lung metastases that were irradiated with 48 Gy in total, 2 tumors did not show a local response. Finally, 3 tumors (33%) with lung metastases relapsed locally at 6-12 months (median 7) after treatment during the follow-up of 3-29 months (median 18). CONCLUSION: 3D conformal hypofractionated single high-dose radiotherapy of 48 Gy in 4 fractions using a stereotactic body frame was useful for the treatment of lung tumors.
Adolescent↗
[Three-dimensional conformal radiotherapy for extracranial tumors using a stereotactic body frame]
This paper was reviewed to evaluate the feasibility of three-dimensional (3-D) conformal radiotherapy for extracranial tumors, especially for solitary lung tumors using a stereotactic body frame. To extend the technique of stereotactic irradiation for intracranial tumors, accurate body fixation and regulation of internal target motion are essential. In our study, a stereotactic body frame was used, and daily setup accuracy was verified. As a result, its setup accuracy was maintained within 0-8.5 mm (Ave=2.5mm). In our initial clinical experiences for thirty-two patients with 6-10 non-coplanar static beams, forty or 48 Gy was irradiated. During the follow-up of 4-27 (Average=11) months, twenty-nine (94%) tumors were locally controlled without any symptomatic complications. Recently, respiratory-gated irradiation systems, CT-linac systems, a real-time tumor tracking system, Cyber-knife, and C-arm linac were developed. With all these techniques, stereotactic irradiation for extracranial tumors are future direction of three-dimensional conformal radiotherapy.
Journal Article↗