Biomedical subjects

Shogo Yamada

Publications and source records attributed to Shogo Yamada.

58 records · Page 4Linked to original sources

PubMed2002

[Performance evaluation of dual-head coincidence gamma camera for positron imaging].

AIM AND METHODS: We assessed the performance evaluation of a dual-head coincidence gamma camera (Millennium VG, General Electric, Milwaukee, USA) as a positron emission tomography (PET) scanner based on the measurement indicator for performance evaluation of PET device. RESULTS: The axial spatial resolution was 4.98 mm FWHM at the center of the field of view. The true high count-rate characteristic curve was relatively straight within the range 0-0.2 microCi/ml. The relative recovery coefficient was 0.1 with a diameter of 10 mm and 0.39 with a diameter of 20 mm. CONCLUSION: In this study, we had to make a some change in the protocols described in the measurement indicator for performance evaluation of PET devices.

Gamma Cameras↗

PubMed2002

[Computed tomography appearance of high-dose-irradiated hepatic parenchyma surrounding small tumors after stereotactic radiotherapy].

INTRODUCTION: The purpose of this study was to demonstrate the computed tomography (CT) appearance of high-dose-irradiated hepatic parenchyma surrounding small tumors after stereotactic radiotherapy (SRT). MATERIALS AND METHODS: Thirteen patients were enrolled between September 1999 and August 2001. We treated 15 lesions [six hepatocellular carcinomas (HCC) and nine liver metastases] with SRT using a linear accelerator. We used two SRT protocols of 45 Gy/3 fractions or 60 Gy/8 fractions. Hepatic CT examinations were performed at 3- to 4-month intervals after SRT. RESULTS: We classified the appearance of high-dose-irradiated hepatic parenchyma on CT into three types: Type 1: eight lesions (53.3%) showed low attenuation areas on non-contrast CT and high attenuation areas on contrast CT; Type 2: five lesions (33.3%) showed low attenuation areas on non-contrast and contrast CT; Type 3: two lesions (13.3%) showed no change. The CT appearance of Type 1 after SRT was similar to that of pre-irradiated HCC, but the other types were easily differentiated from the primary tumors. These changes were observed and continued for 6 to 22 months after treatment. In two cases of Type 1, we performed histological examinations of the regions of high attenuation on contrast CT. These specimens revealed only radiation-induced hepatic injury. CONCLUSION: This study showed three types of CT appearance in high-dose-irradiated hepatic parenchyma. We suggest that other examinations be considered to distinguish between radiation hepatitis and local recurrences for HCC after SRT.

Adult↗

PubMedDate not supplied

Significance of plasminogen-activation system in the formation of macroscopic types and invasion in esophageal carcinoma.

BACKGROUND: The roles of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) in the formation of macroscopic types and invasion were investigated. MATERIALS AND METHODS: A total of 40 surgically-resected esophageal carcinoma tissues were immunohistochemically stained, and the expression of uPA, PAI-1 and the uPA/PAI-1 ratio, were evaluated. RESULTS: The expression of uPA was significantly stronger in the macroscopically infiltrative type (n = 20: p = 0.0027), whereas PAI-1 was significantly stronger in the localized type (n = 20: p = 0.0005). The uPA/PAI-1 ratio was significantly higher in the infiltrative type (p < 0.0001). A significant correlation was found between the U/P ratio and the depth of tumor invasion (r = 0.511, p = 0.0014). Analysis of tumors of uniform size (4.0-6.0 cm in length), showed that the depth of invasion was significantly greater in the infiltrative type (p = 0.0038). CONCLUSION: The results demonstrated that uPA and PAI-1 play important roles in invasion and formation of macroscopic types of esophageal carcinoma.

Aged↗

PubMedDate not supplied

Results of radiation therapy for superficial esophageal cancer using the standard radiotherapy method recommended by the Japanese Society of Therapeutic Radiology and Oncology (JASTRO) Study Group.

BACKGROUND: Superficial esophageal cancer (SEC) is defined as esophageal cancer limited to the submucosal layers, including mucosal cancer and submucosal cancer, and is squamous cell carcinoma in most patients. In 2000, the Japanese Society of Therapeutic Radiology and Oncology (JASTRO) Study Group for SEC published a consensus guideline of standard radiotherapy methods. In this study, the interim treatment outcomes of SEC patients, who had received radiation therapy following the standard radiotherapy methods, were investigated. PATIENTS AND METHODS: From 2000 to 2003, a total of 141 SEC patients were treated in 24 institutions in Japan. RESULTS: The 1-, 2- and 3-year survival rates were 95%, 90% and 90%, respectively, for patients with mucosal cancer and 90%, 81% and 70%, respectively, for patients with submucosal cancer. The overall survival was better in patients who had undergone chemotherapy than in patients who had received radiation therapy alone, though the difference was not statistically significant. The clinical target volume (CTV) did not influence overall survival and intracavitary irradiation did not influence the local control rate in either patients with mucosal or submucosal cancer. Radiation-induced esophageal ulcer was not observed in this series. CONCLUSION: The standard radiotherapy methods are safe and effective for treating SEC. However, the usefulness of chemotherapy and intracavitary irradiation and the optimal setting of the CTV should be clarified by future randomized trials.

Aged↗