Biomedical subjects

Y Aoki

Publications and source records attributed to Y Aoki.

953 records · Page 53Linked to original sources

PubMedDate not supplied

A new bisphosphonate treatment option for giant cell tumors.

Treatment of giant cell tumors (GCT) especially in the vertebrae remains controversial. With multidisciplinary treatments, their results are still insufficient. Moreover, GCT shows the potential for malignant transformation and metastasis, additional options such as adjuvant medication must be considered. We report favorable results in three consecutive cases diagnosed with GCT of the spine which were treated with radiotherapy and bisphosphonate (BP) as a new treatment option, and present a review of the literature and a comparison with these case reports.

Adult↗

PubMedDate not supplied

Enhancement of antitumor effect of hyperthermia with glucose administration in murine mammary carcinoma.

Antitumor effects of hyperthermia are enhanced by lowering the pH in the tumor tissue with administration of glucose. This decreased pH in the tumor tissue with glucose administration was determined using mouse experimental tumors. 31P-MRS microelectrodes were used for the measurement of pH. By using these two measurement methods, time course change in the tumor tissue was determined in the controls and the groups treated with 6 g/kg of intraperitoneal glucose. The determination of pH with 31P-MRS was calculated from the chemical shift of the peak of creatine phosphate (Pcr) and that of inorganic phosphate (Pi). Following glucose administration, the tumor tissue showed a decrease of 0.3 pH units with the microelectrode method, but did not show any significant decrease in pH with the MRS determination. This finding suggested that 31P-MRS showed intracellular pH (pHi) due to the localization of Pi and that the microelectrode indicated interstitial or extracellular pH (pHe). The ATP/Pi ratio obtained in tumor tissue 24 h after heat treatment (with, without glucose) was correlated with tumor inhibition.

Adenosine Triphosphate↗

PubMedDate not supplied

A quantitative analysis of rat osteoporosis model with a microfocus X-ray tube and digital radiography system.

We have developed an X-ray magnification radiographic system incorporating a microfocus X-ray tube and an imaging plate in order to analyze the trabecular structure and mineral content of rat bone. Femoral bones of control, ovariectomy, and leuprorelin acetate depot rat groups were extracted and tested after the animals were sacrificed. Eleven water-equivalent phantoms, which contained hydroxyapatite at a density of 0 to 400 mg/cm3, were set around each femur and radiographed at the same time. The mean read-out signal intensity of the region of interest in the femur was converted to bone mineral density expressed in hydroxyapatite density through the use of a calibration curve relating the signal intensity to the hydroxyapatite density of the phantoms. The bone mineral density of the ovariectomy group was significantly lower than that of the control group, and no differences were found between the control and the leuprorelin acetate depot group. The present system is thought to be useful for quantitative evaluation of the mineral density of the rat femur.

Absorptiometry, Photon↗

PubMedDate not supplied

C-MOS flat-panel sensor for real-time X-ray imaging.

PURPOSE: The aim of this report is to introduce a flat-panel, self-scanning, solid-state diagnostic X-ray imaging device using complementary metal-oxide-semiconductor (C-MOS) arrays for real time digital X-ray imaging and to present findings on its performance. METHODS: A device with a 5.12 cm by 5.12 cm sensor area was developed and tested. The device consists of a cesium iodide scintillator and C-MOS detector arrays. The detector arrays are composed of a regular arrangement of pixels (256x256), each of which is made of a C-MOS photodiode sensor coupled to a C-MOS FET (field effect transistor). RESULTS: A sampling speed of 30 frames per second and spatial resolution of 2.5 lines per mm were achieved. Noise level and maximum signal were 1.5 mV rms and 1.8 V, respectively. CONCLUSIONS: The C-MOS flat-panel sensor is a significant step in actualizing real-time X-ray imaging. A large area sensor needs to be fabricated for clincial use.

Cesium↗

PubMedDate not supplied

Three-dimensional CT in isolated dissecting aneurysm of the superior mesenteric artery: a case report.

Isolated dissecting aneurysm of the superior mesenteric artery (SMA) without aortic dissection is a rare condition. We report a case of isolated dissecting aneurysm of the SMA incidentally detected by postcontrast abdominal computed tomography (CT). Three-dimensional CT using helical scanning was helpful for the evaluation of dissecting aneurysmal structures such as the intimal flap, true lumen, and false lumen with thrombosis. CT angiography (CTA) was useful for the assessment of characteristic morphology and three-dimensional relationship between the dissecting portion and SMA branches.

Aortic Dissection↗

PubMedDate not supplied

Radiation therapy of intracranial germ cell tumors with radiosensitivity assessment.

Fifty patients with pineal and/or suprasellar tumors were treated in the Department of Radiology, University of Tokyo, from 1975 to 1988. Histological diagnosis was obtained in 28 cases, whereas 22 patients were irradiated without pathological verification. Of the 28 patients with histological diagnosis, 11 had germinomas, 13 non-germinoma germ cell tumors, including nine teratomas, two choriocarcinomas and two embryonal carcinomas, two pineocytomas and two pineoblastomas. The treatment protocol since 1981 has been that, after 20 Gy is given with a local irradiation field, if tumor regression is marked and germinoma is highly suspected, whole brain or whole CNS irradiation is performed subsequently; otherwise, surgical intervention is performed followed by systemic chemotherapy plus radiation therapy. The five-year survival rates of histologically proven germinomas, histologically proven non-germinoma germ cell tumors, and clinically suspected germinomas by means of the above-mentioned method as well as tumor marker status were 73%, 28%, and 83%, respectively. The overall five-year survival rate was 61.3%. A statistically significant difference was found between the survival rates for the 11 cases with histologically proven germinoma and the 13 cases with non-germinoma germ cell tumors, although there was no significant difference between the survival rates for the histologically proven germinomas and the clinically suspected germinomas. Therefore radiation therapy is an effective treatment method for the management of intracranial germ cell tumors.

Adolescent↗

PubMedDate not supplied

A dose distribution evaluation utilizing megavoltage CT imaging system.

An isodose distribution (collision kinetic energy distribution) was acquired using a megavoltage CT imaging system. Direct comparison of dose distributions has become important for verification in innovative treatment techniques. Three-dimensional implementation of this system is considered highly feasible.

Humans↗

PubMedDate not supplied

Radiation therapy of carcinoma of the oropharynx.

Forty consecutive cases of carcinoma of the oropharynx were treated by irradiation from 1973 through 1987. The overall five-year survival rate calculated by the Kaplan-Meier method was 21%. Data were also analyzed retrospectively to investigate the factors associated with prognosis. The following results were obtained. (1) The results of re-irradiation as salvage treatment were poor. (2) Irradiation to neck lymph node metastases was not particularly effective, especially under 50 Gy. (3) Stage T2(-4) primary tumors were difficult to control with irradiation of 50 Gy.

Adult↗

PubMedDate not supplied

Radiation therapy for primary non-Hodgkin's lymphoma of the head and neck in stages I and II.

From January 1975 through December 1986, 58 previously untreated patients with primary non-Hodgkin's lymphoma of the head and neck in stages I and II were treated at our department. Thirty-seven patients were classified as stage I and 21 as stage II. Complete local remission was obtained in all cases. The 5-year survival rates were 68% and 79% in stages I and II, respectively. The 5-year survival rates according to site of origin were as follows: Waldeyer's ring 77% and neck lymph node 63%. The 5-year survival rates according to the histological classification of the Working Formulation were 73% intermediate grade malignancy and 63% for high grade malignancy. Chemotherapy combined with radiotherapy was essential, especially for cases in stage II. The 5-year survival rate was 100% for patients with chemotherapy and 71% without chemotherapy. The relapse-free 5-year survival rate was 67% with chemotherapy and 36% without chemotherapy. Most first failures were due to the development of generalized disease and the 5-year survival rate after salvage was 44%.

Adolescent↗

PubMedDate not supplied

Carcinoma of the maxillary sinus: the role of radiotherapy.

From 1975 to 1986, 75 M0 patients with squamous cell carcinoma of the maxillary sinus were treated at the Department of Radiology, Tokyo University Hospital. The overall 5-year survival rate calculated with the Kaplan-Meier method was 24%. During the period of the study, the method of treatment used in our hospital changed. From 1975 to 1979 (the first period), the treatment of choice was low-dose irradiation and frequent necrotomy. From 1980 to 1982 (the second period), more extensive surgery was performed and 50 to 60 Gy of irradiation was given. The 5-year survival in the first period was 20%, that in the second 14%. From 1983 to 1986 (the third period), trimodal therapy (surgery + radiation + intra-arterial infusion) was introduced and 5-year survival was improved to 50%. Intra-arterial cisplatinum infusion and treatment planning using CT scans were especially useful in improving survival.

Adult↗

PubMedDate not supplied

An integrated radiotherapy treatment system and its clinical application.

A new total system for radiation therapy installed in our department consists of a linear accelerator unit with microcomputer-controlled multileaf collimators, along with a CT scanner installed in the same treatment room. Also included are a digitally controlled communal couch, a minicomputer, and a system of treatment planning devices. We have developed various kinds of external radiation treatment planning techniques (including dynamic ones) with this system on the basis of the concept of dose corresponding technique. A reference point setup method is needed to maintain a unified coordinate system through each step of the treatment procedure, and, as developed by us, permits a volume-oriented setup. This system has been evaluated for accuracy in a variety of clinical setups. A true three-dimensional dose calculation algorithm is required for treatment planning associated with multileaf collimator treatments in order to realize the potential accuracy of such a system.

Computer Simulation↗

PubMedDate not supplied

Radiation therapy for patients with xeroderma pigmentosum.

Our experience reported here, as well as a review of the literature, suggests that radiation therapy can be used in the palliative treatment of XP-related malignancy. However, radiation therapy should be used with caution in XP patients with an anticipated prolonged life expectancy, because the late side effects of ionizing radiation in XP are not well known.

Adult↗

PubMedDate not supplied

Clinical evaluation of gamma knife radiosurgery for intracranial arteriovenous malformation.

PURPOSE: Aim of the study is to compare our treatment results or gamma knife radiosurgery for arteriovenous malformation (AVM) and to obtain factors determining nidus obliteration and/or adverse effect. METHODS: We analyzed 236 patients with AVM treated between June 1990 and February 1994. The patients consisted of 137 men and 99 women, and ranged in age from 4 to 71 years. AVM volume ranged 0.7 to 37.7 ml. Maximum and peripheral doses ranged from 18.2 to 60.0 Gy and 10.0 to 28.0 Gy, respectively. RESULTS: Complete obliteration rates at 1,2, and 3 years were 36.2, 68.9, and 86.6%, respectively. The mean time to complete obliteration was 21.4 months. Univariated analysis revealed that calculated target volume, peripheral dose, peripheral percent dose and treatment optimality were significant factors for complete obliteration. In multivariate analysis, calculated target volume, treatment optimality, and CT-based planning were significant factors. The actuarial risk of post-radiosurgical brain edema at 2 years was 20.0%. In both univariate and multivariate analysis, calculated target volume was the only significant factor. Symptomatic complications developed in 10.0% of patients at 2 years, but no significant factors were identified. Permanent complications and severe neurological deficits were seen in 4.4 and 2.8% of patients, respectively. CONCLUSIONS: Our results were similar to those reported previously. Accurate CT-based planning contributed to an improved obliteration rate.

Actuarial Analysis↗

PubMedDate not supplied

Significance of informed consent and truth-telling for quality of life in terminal cancer patients.

For 12 patients with terminal stage cancer who died within the period from June 1995 to the present, we retrospectively evaluated the correlation between the "information" concerning disclosure of the "diagnosis," "pathology," and "prognosis," with the length of the last admission before the death, "sedation" near death, and the choice of "do not resuscitate (DNR)." The average length of admission before death was markedly shorter for patients who had been told either the "diagnosis," "pathology," or "prognosis" than for patients who had not. A statistically significant difference was observed between those who had been told and those who had not been told the "pathology." Similarly, "sedation" tended to be done for those who had been provided with information on cancer. It was suggested that telling patients with terminal stage cancer the truth about "diagnosis," "pathology," and "prognosis" is important for them to spend a fulfilling terminal stage.

Adult↗

PubMedDate not supplied

Aiming at establishment of "palliative day care"--attempt at providing an outpatient salon for cancer patients in the Department of Radiology.

Reflecting a trend toward reconsideration of medical care which concentrates only on the treatment of disease, a new paradigm of "palliative care" has recently been developed with a focus on the treatment of cancer patients. As part of our palliative care program, we have provided an "outpatient salon" for outpatients in the Department of Radiology of this hospital. The goal of the outpatient salon is to assist patients who live at home in coping with their disease. We regard this outpatient salon as a preparatory step in establishing a palliative day care center to support patients and their families at home and to improve patient QOL. Currently, two staff members are acting as counselors at the salon, and most of the patients visiting the salon are breast cancer patients. The salon appears to provide the following benefits to patients: 1) self-assurance, by allowing them to talk to others about their problems, 2) development of self-help skills, through involvement with other patients, 3) a place to relax, and 4) comfort from focusing. We have two future goals: to develop the salon into a day care center, and to nurture a self-help group within the salon.

Adult↗

PubMedDate not supplied

Analysis of treatment results of hypopharyngeal cancer.

Sixty-three patients with squamous cell carcinoma of the hypopharynx were treated at the University of Tokyo between 1985 and 1993. Twelve patients were treated with surgery alone, 16 with preoperative irradiation, 26 with postoperative irradiation, and nine with irradiation alone. A tumor dose of 50 Gy (25 fractions/5 weeks) was used in postoperative irradiation, 40-60 Gy in preoperative irradiation, and 70 Gy in irradiation alone. When "number of indications," including, for example, partial pharyngectomy, positive or close (< or = 5 mm) margin, and extracapsular extension, was used for multivariate analysis in patients who underwent surgery, it proved to be the only significant prognostic factor for gross survival. Six of seven patients with a positive surgical margin or close margin who received postoperative irradiation had local recurrence. A tumor dose of 50 Gy (25 fractions/5 weeks) in postoperative irradiation is not enough. It is difficult to cure by irradiation metastases to the parapharyngeal lymph nodes large enough to be detected with CT. It is necessary to irradiate parapharyngeal lymph nodes prophylactically, but 50 Gy in postoperative irradiation may not be enough from our results. The same may be true for metastases to the paratracheal nodes, which lie close to the lower poles of the thyroid gland or within the superior mediastinum and are difficult to access through surgery. In the patients who were operated on, N stage and the number of lymph node metastases were significant for gross survival. When "number of indications" was used for analysis, "number of indications" proved to be the most significant prognostic factor for gross survival.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Clinical usefulness of the management and delivery of radiation dose-distribution images using the Internet.

Dose distribution images in radiation therapy play important roles in the management of cancer patients. To date, hard copies of these images have been stored for referral by radiation oncologists as needed. In most cases, these images are not available to medical personnel outside the radiation oncology department. We have developed a means to access these dose distribution images from the hospital via the World-Wide Web (WWW). A screen snapshot of a dose distribution image on the CRT of a treatment planning unit is copied to the WWW server and converted to a GIF (graphic interchange format) image. Similarly, we can register dose volume histograms and digitally reconstructed radiographs (DRR) on the WWW. Medical personnel can view these images through the WWW browser from anywhere in the hospital. As a result, radiation oncologists are given detailed information on target definition in treatment planning by expert physicians. The system also helps co-medical personnel in understanding dose distribution and predicting radiation injury. At the same time, it actualizes an electronic archive of dose distribution images, which is a database for quick and reliable review, evaluation, and comparison of treatment plans. This technique also fosters closer relationships among radiation oncologists, physicians, and co-medical personnel.

Humans↗