Biomedical subjects

Takehiro Inoue

Publications and source records attributed to Takehiro Inoue.

43 records · Page 3Linked to original sources

PubMedDate not supplied

Monte Carlo calculation of depth doses for small field of CyberKnife.

PURPOSE: A Monte Carlo (MC) model of CyberKnife was developed as a quality assurance tool. The percentage depth dose (%dd) was verified by using this model. MATERIALS AND METHODS: An MC model was developed with Electron Gamma Shower version 4 (EGS4) in two steps: (1) a model of the CyberKnife treatment head and (2) a model of the collimator and phantom. The bremsstrahlung spectrum was calculated using the first model, and this spectrum was then used to calculate %dds with the second model. The calculated %dds for a large field (60 mm diameter) and three small fields (30, 15, and 5 mm diameter) were compared with those measured with a diamond detector. RESULTS AND DISCUSSION: The MC-calculated and measured %dd-curves for the 60 mm diameter field were in excellent agreement (<1.85%), thus confirming the validity of the model. Discrepancies between the calculated and measured %dd-curves increased with decreasing field size, with considerable discrepancy (11.62%) for the 5 mm diameter field due to lateral electron disequilibrium. Accurate dose can be determined with MC even in small fields. CONCLUSION: The MC technique can provide reliable standard data for accurate dose delivery with high-technology radiotherapies using small beams.

Humans↗

PubMedDate not supplied

Influence of in vitro radiation on changes in nitric oxide in rat macrophages and smooth muscle cells.

We examined changes in nitric oxide (NO) levels resulting from irradiation of rat macrophage (RAM) and smooth muscle cells (SMC) in medium. Irradiation did not alter the NO concentration in the medium of either cell line. However, irradiation of 5 and 20 Gy enhanced the concentration of NO induced by lipopolysaccharide (LPS) in the medium containing RAM. Furthermore, 20 Gy of irradiation suppressed NO production induced by interferon-gamma in the RAM medium. Radiation seemed to enhance NO production more than that caused by Interleukin 1-beta only in the medium containing SMC. Next, mRNA levels of inducible NO synthase (NOS) were examined in RAM by Northern blotting following irradiation. Five Gy of irradiation did not generate iNOS mRNA expression, but did enhance iNOS piRNA expression induced by LPS, while 20 Gy suppressed the expression level of iNOS mRNA more than 5 Gy. This leads to the conclusion that radiation stimulation induced NO production through indirect action on the macrophage.

Animals↗

PubMedDate not supplied

Treatment results of radiotherapy with or without surgery for posterior pharyngeal wall cancer of oropharynx and hypopharynx: prognostic value of tumor extension.

PURPOSE: We have been treating posterior pharyngeal wall cancer of the oropharynx and hypopharynx with external radiotherapy according to our policy reported in the 1970s. MATERIALS AND METHODS: Between 1968 and 1995, 51 patients were treated. Treatment policy was decided on the basis of the treatment response after 40 Gy of radiotherapy. Thirty-six good responders were treated with radical radiotherapy, eight poor responders received radical surgery, and the other seven patients could not receive radical treatment because of tumor or patient factors. RESULTS: The 5-year local control and cause-specific survival rates were 56% and 48% for all 51 patients. The 5-year local control rate was 52% for radical radiotherapy. Tumors limited to the posterior wall showed better treatment results (76% for both local control and cause-specific survival) than tumors involving the postcricoid area (0% and 10%). CONCLUSION: Radiotherapy for carefully selected patients dependent on response after 40 Gy of radiotherapy is a useful policy. Tumor extension is an important prognostic factor.

Adult↗

PubMedDate not supplied

Acute tumor lysis syndrome caused by palliative radiotherapy in patients with diffuse large B-cell lymphoma.

Acute tumor lysis syndrome (TLS) is a condition that results from the rapid destruction of tumor cells accompanied with a massive release of cellular breakdown products. Acute renal failure resulting from TLS has been reported in cases of hematologic malignancies, spontaneous or treatment induced, the latter especially by chemotherapy. We present the case of a patient with diffuse large B-cell lymphoma who developed radiotherapy-induced TLS and subsequently acute renal failure. He presented with a large mediastinal tumor compressing the airway, thus causing dyspnea. After 6 Gy/3 fractions/3 days of palliative radiotherapy for the tumor, a decrease in urine volume was noted as well as rapid tumor shrinking. Because this patient died despite previous prophylaxic anti-uric acid treatment and hemodialysis, his case illustrates the need to anticipate the development of acute renal failure, even though there may be no remarkable serum uric acid elevation after the initiation of radiotherapy.

Acute Disease↗

PubMedDate not supplied

Quantitative evaluation of changes in irradiated lung fields after stereotactic irradiation by the Polygon Method.

PURPOSE: To evaluate areas of change in lung after thoracic stereotactic irradiation (STI). MATERIALS AND METHODS: We developed a method of evaluation named the Polygon Method, to measure the irradiated lung fields of 12 lung tumors treated by STI. Before treatment, each targeted field was divided into several circular zones of 2 cm in width centered at the tumor on high resolution computed tomography, and the areas of each zone before and after treatment were compared. RESULTS: Six months after treatment, the areas of the zone within 2 cm from the tumor decreased, and the mean ratio of areas after and before STI was 0.849 (range, 0.515 to 1.052, p=0.0254). By contrast, the areas of zones located at 4 to 6, 6 to 8, 8 to 10, and more than 10 cm from the tumor tended to increase, with mean ratios of 1.059, 1.058, 1.089 (p=0.0374), and 1.084, respectively. CONCLUSION: After thoracic STI, volume loss in the lung is limited to the field in close proximity to the tumor, while compensatory expansion of the lung occurs in fields distant from the tumor.

Adenocarcinoma↗

PubMedDate not supplied

Concurrent chemoradiotherapy with cisplatin and docetaxel for advanced head and neck cancer. A phase I study.

BACKGROUND: This phase I study of weekly low-dose administration of cisplatin (CDDP) and docetaxel (DOC) combined with concurrent conventionally fractionated radiotherapy was designed for locoregionally advanced head and neck cancer. PATIENTS AND METHODS: Twelve patients were treated at varying levels of DOC (level 1: 5 mg/m2/week, level 2: 7.5 mg/m2/week, level 3: 10 mg/m2/week) with CDDP constant at 20 mg/m2/week in four cohorts of three patients. Radiation was given at 1.8-2.0 Gy/fraction to a total dose of 60-70.2 Gy. RESULTS: Hematological toxicities, except lymphocytopenia, were minimal. Mucosal toxicities, especially grade 3 mucositis, were common. Dose-limiting toxicity was grade 3 pain, although level 3 did not reach a maximum tolerated dose. No grade 4 toxicities were observed. Complete response rate ranged from 33% to 67% in the various dose levels. CONCLUSION: This concurrent chemoradiotherapy seems to be a promising treatment modality, in which level 3 is the recommended dose for a phase II study.

Aged↗

PubMedDate not supplied

High-dose-rate interstitial brachytherapy for mobile tongue cancer: influence of the non-irradiated period.

BACKGROUND: It has been demonstrated that the outcome of primary radiotherapy in squamous cell carcinomas of the head and neck is strongly influenced by overall treatment time. The purpose of this study was to evaluate the results of high-dose-rate (HDR) interstitial brachytherapy (ISBT) for early mobile tongue cancer and to examine whether the non-irradiated period affected treatment results. MATERIALS AND METHODS: Seventy-one patients with early mobile tongue cancer (T1-T2N0M0) were treated with HDR ISBT alone. The total dose was 54-60 Gy/9-10 fractions/5-9 days. All patients were classified into 4 groups: R0, maximum non-irradiated period (NIP) was less than 24 h (n=16); R1, maximum NIP was from 24 to 48 h (n=24); R2, maximum NIP was from 48 to 72 h (n=26); R3, maximum NIP was from 72 to 96 h (n=5). RESULTS: The 3-year local control rate was 94% in R0, 83% in R1, 85% in R2 and 100% in R3. The 3-year overall survival rate was 84% in R0, 92% in R1, 71% in R2 and 80% in R3. There was no significant difference in the local control rate, overall survival rate, or complications among the 4 groups. CONCLUSION: In HDR ISBT for early mobile tongue cancer, the non-irradiated period did not affect the treatment results or complications.

Adult↗