Biomedical subjects

Rikiya Onimaru

Publications and source records attributed to Rikiya Onimaru.

22 records · Page 2Linked to original sources

PubMed2001

[Gated Radiotherapy]

Recent external radiotherapy requires precise localization of the target because advance in diagnostic imaging has made it possible to visualize a tiny tumor which would be curable with focused high dose irradiation. However, tumors in respiratory and bowel organs have been difficult to be given the high dose because of 1 to 3 cm movement during delivery of irradiation. Respiratory-gating techniques have been used with medical linear accelerators and particle therapy machines. Real-time tumor-tracking radiotherapy has been realized using fluoroscopic x-rays, internal gold-markers, and pattern recognition technology. Advantage and disadvantage of each gating technique have been realized. Active breath control method would be a cost-effective way of precise treatment without gating. More work is required to find the relationship between abdominal wall and internal movement of the tumor in many respiratory-gating radiotherapy and between the internal markers and target volume in real-time tracking radiotherapy.

Journal Article↗

PubMedDate not supplied

Reduction in acute morbidity using hypofractionated intensity-modulated radiation therapy assisted with a fluoroscopic real-time tumor-tracking system for prostate cancer: preliminary results of a phase I/II study.

PURPOSE: The positioning of the prostate is improved with the use of the fluoroscopic real-time tumor-tracking radiation therapy system for prostate cancer. The acute radiation reaction and preliminary tumor response of prostate cancer to hypofractionated intensity-modulated radiation therapy assisted with real-time tumor-tracking radiation therapy were investigated in this study. METHODS: Patients were classified into prognostic risk groups on the basis of the presence of the pretreatment prostate-specific antigen, clinical stage, and histologic differentiation. Neoadjuvant hormonal therapy was administered to patients in the high-risk group for 6 months before radiation therapy commenced. The intensity-modulated radiation therapy employed a segmental multileaf collimator, which generated a field made up of two or more shaped subfields using forward planning. Real-time tumor-tracking radiation therapy was used for the precise positioning of the prostate to minimize geometric uncertainties, while the dose was escalated in increments of 5 Gy from 65 Gy using a daily dose of 2.5 Gy (65 Gy/2.5 Gy), following the dose-escalation rules. Acute and late gastrointestinal and genitourinary morbidities due to radiation therapy were scored according to the toxicity criteria of Radiation Therapy Oncology Group/European Organization for Research and Treatment of Cancer. RESULTS: Thirty-one patients were enrolled in this study between 1998 and 2001. Eighteen patients were classified as being members of the high-risk group. Total dose was escalated, with 65 Gy/2.5 Gy being administered to 12 patients and 70 Gy/2.5 Gy to 19 patients. The median follow-up period was 37 months (range, 30-43 months), and 19 months (range, 10-27 months), for the 65-Gy and 70-Gy arms, respectively. Patients experienced no acute toxicity and grade 1 late gastrointestinal toxicity (8.3%) in the 65-Gy/2.5-Gy arm. Patients in the 70-Gy/2.5-Gy arm experienced grade 1 acute gastrointestinal toxicity (5.3%) and grade 1 and 2 acute genitourinarytoxicities (15.8%). No patients experienced dose-limiting toxicity (defined as a grade 3 or higher acute toxicity) or a grade 2 or higher late complication in this study period. One and two prostate-specific antigen relapses were observed in the 65-Gy and 70-Gy arms, respectively. CONCLUSION: Up to 70 Gy/2.5 Gy, equivalent to 80 Gy with a daily dose of 2.0 Gy, assuming alpha/beta ratio of 1.5, intensity-modulated radiation therapy assisted with real-time tumor-tracking radiation therapy was administered safely with a reasonable biochemical control rate. A further dose-escalation study using this system is justifiable.

Acute Disease↗

PubMedDate not supplied

Long-term results of ethmoid squamous cell or undifferentiated carcinoma treated with radiotherapy with or without surgery.

PURPOSE: Ethmoidal malignant tumors, for which intensity-modulated radiotherapy is expected to improve outcome, consist of heterogeneous pathological types. Reports about their outcome are influenced by the inclusion of favorable histology, such as adenocarcinoma and adenoid cystic carcinoma. We investigated the long-term treatment outcome of squamous cell carcinoma and undifferentiated carcinoma of the ethmoid sinus. MATERIALS AND METHODS: Between August 1976 and April 2002, 25 patients (20 squamous cell carcinomas and five undifferentiated carcinomas) received radical radiotherapy or preoperative radiotherapy in our institution. One (4%) had stage T2 disease, seven (28%) had stage T3, three (12%) had stage T4a, and 14 (56%) had stage T4b. Surgery was performed in 13 patients. Radiation dose varied from 50.4 Gy in 16 fractions (50.4 Gy/16 Fr) to 65 Gy in 26 fractions with or without stereotactic boost irradiation. Eleven patients received chemotherapy consisting mainly of platinum-based compounds. RESULTS: The 3- and 5-year overall survival rates for all 25 patients were 34% (95% confidence interval [CI]: 14%-54%) and 24% (CI: 6%-42%), respectively. The 3- or 5-year local progression-free rates for all patients were 48.9% and 36.7%, respectively. Visual acuity of a single eye was impaired in three patients and was lost in five patients as a result of tumor progression, but no patient had visual impairment or loss due to radiotherapy. CONCLUSION: Ethmoid squamous cell carcinoma or undifferentiated carcinoma was diagnosed at advanced T stages and was treated with radiotherapy; these patients had a poorer outcome than patients with adenocarcinoma or adenoid cystic carcinoma. Prospective trials using advanced technology should be carefully compared with historical controls because pathological types can considerably influence the treatment results.

Adult↗

PubMedDate not supplied

Characteristics of patients who developed radiation pneumonitis requiring steroid therapy after stereotactic irradiation for lung tumors.

BACKGROUND: To find possible risk factors for symptomatic radiation pneumonitis (RP) after stereotactic irradiation (STI) for peripheral non-small cell lung cancer (NSCLC), pre-treatment pulmonary function test and dose volume statistics in patients who developed RP requiring steroid intake were retrospectively compared with statistics of those who did not develop RP. MATERIALS AND METHODS: From 1996 to 2002, 156 patients with Stage I NSCLC received STI at 5 hospitals in Japan. Of those patients, 12 were medicated with steroids for RP after treatment (RP group). For comparison, 31 patients were randomly selected from the remaining 144 patients who received STI but did not receive steroids (control group). RESULTS: There were no statistical differences in age, sex, tumor size, performance status, forced expiratory volume in 1 sec (FEV1.0%), or percent vital capacity (%VC) between patients medicated with steroids for RP and those who did not have RP and received no steroids. V20 (%) was 7 to 18% (median 8%) in patients medicated with steroids for RP and 2 to 16% (median 7%) in those who did not have RP. No difference was observed in V20, the biologically effectively dose (BED) at the periphery of the planning target volume, or the dose per fraction between the two groups. CONCLUSIONS: Pre-treatment pulmonary function test (%VC, FEV1.0%), and dose volume statistics V20, total dose, BED, dose per fraction, peripheral dose) were not predictive of RP requiring steroid intake after STI for stage I NSCLC.

Adrenal Cortex Hormones↗