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[en] Fuel Safety Research Specialists' Meeting, which was organized by Japan Atomic Energy Research Institute, was held on March 4-5, 2002 at JAERI in Tokai Establishment. Purposes of the Meeting are to exchange information and views on LWR fuel safety topics among the specialist participants from domestic and foreign organizations, and to discuss the recent and future fuel research activities in JAERI. In the Meeting, presentations were given and discussions were made on general report of fuel safety research activities, fuel behaviors in normal operation and accident conditions, FP release behaviors in severe accident conditions, and JAERI's ''Advanced LWR Fuel Performance and Safety Research Program''. A poster exhibition was also carried out. The Meeting significantly contributed to planning future program and cooperation in fuel research. This proceeding integrates all the pictures and papers presented in the Meeting. The 10 of the presented papers are indexed individually. (J.P.N.)
[en] Cochlear implant (CI) is an electronic device used to rehabilitate patients with sensorineural hearing loss. The intent of this review is to demonstrate the normal position of the electrode on computed tomography (CT) and contrast this with various examples of the electrode malpositioning. Post-implantation CT is performed to localize the cause of implant failure in patients in which radiographs suggest an anomalous course of the electrode. A common cause of device failure is extrusion or malpositioning of the electrode. It is important for the radiologists to recognize this important aspect of device failure. Post-implant CT can help identify patients with malpositioned electrode in whom another attempt can be made by correctly re-implanting the electrode.
[en] Purpose: The objectives of the present study were (a) to validate the prognostic classification derived from recursive partitioning analysis (RPA) of the Radiation Therapy Oncology Group (RTOG); (b) to identify prognostic factors in class 3; (c) to examine the impact of treatment related variables on the prognosis in class 3. Patients and methods: Nine hundred and sixteen patients with brain metastases had resection and whole brain radiotherapy (WBRT, n=257) or WBRT alone (n=659) at our institution from 1985 to 2000. Patients were grouped into RPA classes 1, 2, and 3 (n=67, 441, and 408, respectively). Results: Median survival of the whole group was 3.4 months. Median survival in classes 1, 2, and 3 was 8.2, 4.9, and 1.8 months, respectively. In class 3, age (n=51): age n=44): age ≥65 years, uncontrolled primary tumor, multiple brain metastases; class 3b (n=313): all other patients. Median survival in classes 3a, 3b, and 3c was 3.2, 1.9, and 1.2 months, respectively (PConclusion: Our results validate the RTOG RPA classification for patients with brain metastases. The variables age, status of the primary, and number of brain metastases allow the division of class 3 into prognostic subgroups. Even class 3 patients may benefit from more aggressive treatment strategies.
[en] A retrospective study evaluated 15 patients with pelvic recurrence of colorectal cancer in a previously irradiated region who received intraoperative radiation therapy (IORT) as part of salvage therapy. Total prior external beam radiation therapy (EBRT) doses ranged from 45 to 79.2 Gy. Tumor resection was accomplished in 14 patients, with an exenteration performed in seven. IORT dose was 15–20 Gy. Three patients received additional EBRT as a post-operative course of 25.2 Gy in 14 fractions. Actuarial 3-year local control rate was 25%. The 3-year overall survival rate was 29%. Patients with fixed and/or bulky pelvic tumors had a local control rate of 19% at 12 months and median overall survival of 9 months. Patients with less extensive clinical presentations of anastomotic non-fixed transmural recurrence, isolated pelvic node metastasis and rectal recurrence following local excision had a local control rate of 42% at 36 months and median survival of 43 months. We conclude that clinical presentation of recurrent disease is an important prognostic factor. The value of IORT may be limited to patients with less extensive clinical presentations.
[en] Background and purpose: The potential risk of prolongation of treatment time in cervical cancer has been reported for many low-dose rate (LDR) studies, with an estimated loss of local control ranging from 0.3 to 1.6% per day of treatment prolongation. Since the treatment schedule for fractionated high-dose rate intracavitary brachytherapy (HDRICB) is not directly comparable with that for low-dose rate studies, this report aims to evaluate the adverse effect of treatment prolongation specifically for cervical cancer treated with HDRICB. Material and methods: From September 1992 to December 1997, 257 patients diagnosed with uterine cervical cancer (35 Ib, 26 IIa, 122 IIb, 10 IIIa, 57 IIIb, 7 IVa), who underwent external radiotherapy combined with between two and four courses of HDRICB and a minimum of 3 years of follow-up (median 57 months), were analyzed. Treatment consisted of irradiation of the whole pelvis with 44–45 Gy consisting of 22–25 fractions by 5 weeks, with the dose boosted to 54–58 Gy (with central shielding) for patients diagnosed as FIGO stage IIb–IVa bilateral parametrial disease. HDRICB was performed using an Ir-192 remote afterloading technique at 1-week intervals. The standard prescribed dose for each course of HDRICB was 7.2 Gy to point A for three insertions (before July 1995), or 6.0 Gy to point A for four insertions (after July 1995). Total prescribed point A doses (external beam radiotherapy+HDRICB) ranged from 58 to 71.6 Gy (median, 65.6 Gy) for stage IB–IIA, while analogous dosage for larger lesions (stage IIb–IVa) ranged from 59 to 75.6 Gy (median, 65.6 Gy). Kaplan–Meier and multivariate analyses were used to test the effect of treatment time on pelvic control rate (PCR) and cause-specific survival (CSS) at 5 years. Results: Median treatment time was 63 days. For all stages of disease, the 5-year CSS and PCR were significantly different comparing treatment times of less than and greater than or equal to 63 days [83% and 65% (P=0.004], 93% and 83% (P=0.02), respectively]. These associations were also significant for stage Ib/IIa [97% and 79% (P=0.01), and 100% and 87% (P=0.02), respectively), but not for stage IIb [75% and 72% (P=0.79), and 93% and 87% (P=0.83), respectively] or stage III [66% and 49% (P=0.2), and 83% and 72% (P=0.21), respectively]. Multivariate analysis identified three prognostic factors for CSS, stage (PP=0.001), and overall treatment time (OTT; P=0.006). Prognostic factors for pelvic failure were stage (PP=0.001), and OTT (P=0.03). Prolongation of treatment time resulted in a daily decrease in pelvic control rate of 0.67% overall, and 0.43% for stage Ib–IIa, 0.57% for stage IIb, and 0.73% for stage III patients. Conclusion: Analysis of the data from the current study demonstrates that the adverse effect of treatment prolongation was observed later in the treatment course for the high-dose rate (HDR) series compared to the LDR analog, however, treatment-time prolongation still negatively influenced the cause-specific survival and pelvic control rate for both dosage groups.
[en] Summary The rationale for introducing ion beams in cancer therapy is the high level of physical selectivity that can be achieved with ions, equal or even better than with proton beams or modern photon techniques, as well as the potential advantage of high-LET radiations for some tumour types and sites. The radiobiological arguments for high-LET radiation in cancer therapy are reviewed: reduction of OER in the case of hypoxic and poorly-reoxygenating tumours, and the lesser importance of repair phenomena which are a problem in controlling repair-proficient photon-resistant tumours. Fast neutrons were the first type of high-LET radiation used clinically, and were often applied under suboptimal technical conditions. Nevertheless, useful clinical information was derived from the neutron experience. A greater benefit from neutrons than from conventional radiotherapy was found for several tumour sites. The present discussion is limited to the results for salivary gland tumours and prostatic adenocarcinoma. Based on the fast neutron experience, radiobiological arguments, and the added benefit of excellent physical selectivity of ion beams, the potential clinical indications for high-LET ions are discussed: hypoxic, slowly growing and well-differentiated photon-resistant tumours. One of the main remaining issues is the selection of individual patients for high- or low-LET radiation. Since the physical selectivity of ions now matches that obtained with other techniques, the selection of patients will be based only on the radiobiological characteristics of the tumour.
[en] High-spin terminating bands in heavy nuclei were first identified in nuclei around 158Er90. While examples of special terminating states have been identified in a number of erbium isotopes, almost nothing is known about the states lying beyond band termination. In the present work the high-spin structure of 157Er has been studied using the Gammasphere spectrometer. The subject of triaxial superdeformation and 'wobbling' modes in Lu nuclei has rightly attracted a great deal of attention. Very recently, four strongly or superdeformed (SD) sequences have been observed in 174Hf and ultimate cranker calculations predict such structures may have significant triaxial deformation. We have performed two experiments in an attempt to verify the possible triaxial nature of these bands. A lifetime measurement was performed to confirm the large (and similar) deformation of the bands. In addition, a high-statistics, thin-target experiment was run to search for linking transitions between the SD bands and possible wobbling modes
[en] Lifetimes for decays linking near-yrast states in 107Cd have been measured using the recoil distance method (RDM). The nucleus of interest was populated via the 98Mo(12C,3n)107Cd fusion-evaporation reaction at an incident beam energy of 60 MeV. From the measured lifetimes, transition probabilities have been deduced and compared with the theoretical B(E2) values for limiting cases of harmonic vibrational and axially deformed rotational systems. Our initial results suggest a rotor-like behavior for the structure based on the unnatural-parity, h11/2 orbital in 107Cd, providing further evidence for the role of this 'shape-polarizing' orbital in stabilizing the nuclear deformation in the A ∼ 100 transitional region