Wie nicht-lineare Zeitrepräsentationen zukunftsbezogene Urteile und Entscheidungen beeinflussen können : ein entwicklungspsychologischer Ansatz

Die vorliegende Arbeit untersuchte in drei Experimenten den Einfluss der Zeit auf Bewertungen und Entscheidungen in unterschiedlichen Altersstufen. Experiment 1 beschäftigte sich mit dem Einfluss des Zeithorizontes auf die Beurteilung der Riskantheit einer Investition sowie auf das Investitionsverhalten bei 12-Jährigen. Im Gegensatz zu typischen Ergebnissen von Erwachsenen führte bei den Kindern eine lange Zeitspanne zwischen Investition und Erfolgsfeedback zur Annahme eines höheren Risikos und damit zu geringeren Investitionen. In Experiment 2 wurde die Bewertung materieller und nicht-materieller Werte, deren Erhalt verzögert war, bei 12-Jährigen und Erwachsenen untersucht. Dabei zeigte sich, dass Erwachsene Geld als materiellen Wert und Hilfe als nicht-materiellen Wert in ähnlicher Weise mit zunehmender Verzögerung abwerteten. Die Kinder hingegen werteten das verzögerte Geld deutlich stärker ab als Erwachsene, die Hilfe jedoch gar nicht. In Experiment 3 wurde die Entwicklung des Wissens über exponentielles Mengenwachstum in verschiedenen Altersgruppen untersucht. So schätzten 13-Jährige ein solches Wachstum normativ, doch bereits 9-Jährige unterschieden in ihren Schätzungen bedeutsam zwischen exponentiellem und linearem Wachstum, was für ein frühes intuitives Wissen in diesem Bereich spricht. Im Anschluss wurde ein Modell zur altersabhängigen Zeitrepräsentation entwickelt, das versucht, den Einfluss der Zeitrepräsentation in allen drei Experimenten zu erklären. Three experiments were conducted to examine the role of time on judgments and decisions in different age groups. Experiment 1 investigated the influence of the time horizon on 12-year-olds judgments of riskiness and amount of investment into an endeavour. In contrast to typical results of adults, a long time span between the investment and a feedback about its success yielded judgments of higher riskiness and, thus, lower investments in children. Experiment 2 assessed 12-year-olds and adults evaluation of material and immaterial values, whose receipt was either immediate or delayed. Results showed similar subjective discount rates for delayed money (i.e. material value) and delayed help (i.e. immaterial value) in adults. However, children discounted the delayed money more than adults, but they devaluated the delayed help not at all. Experiment 3 investigated the development of knowledge about exponential growth in children, aged 7 to 13 years, and adults. Only 13-year-olds showed a normative estimation of exponential growth. However, 9-year-olds already differentiated between exponential and linear growth in their estimations. This result points to an early intuitive knowledge in this domain. Finally, a model of age-related time representation was proposed to explain the role of time representation in the three experiments

Carbon Ion Therapy of Rectal and Pancreatic Cancer

Carbon Ion Therapy of Rectal and Pancreatic CancerIntroduction: Pancreatic cancer is the fifth leading cause of cancer death and is considered to be one of the most lethal cancers in Japan. Chemotherapy and/or chemoradiotherapy are usually selected as standard treatment for unresectable pancreatic cancer. However, since pancreatic cancer is often resistant to chemotherapy and radiotherapy, the local control rate is very low. We initiated a phase I/II clinical trial of carbon-ion radiotherapy (C-ion RT) combined with gemcitabine in patients with locally advanced pancreatic cancer. Materials and Methods: The eligibility criteria for this study were as follows: locally advanced pancreatic cancer that involved the celiac trunk or superior mesenteric artery without distant metastasis. All patients had histologically or cytologically proven pancreatic adenocarcinoma. The radiation fractions were fixed at 12 fractions over three weeks, and the doses of gemcitabine andradiation were gradually increased. First, the radiation dose was fixed at 43.2 GyE/8 fractions, and the gemcitabine dose was increased from 400 to 700 to 1,000 mg/m2. Subsequently, the gemcitabine dose was fixed at 1,000 mg/m2 and the radiation dose was increased from 43.2 GyE to 55.2 GyE in 5% increments. Gemcitabine was administered for three consecutive weeks, once a week. Results: Seventy-five patients were registered from April 2007 through February 2012. Of these patients, 71 were clinically eligible for the study. Four patients were ineligible and excluded from the analyses due to liver metastases that became obvious before the administration of C-ion RT (n=3) and the inadequacy of histological confirmation (n=1). The median age was 63 (range: 39-74) years. The performance status was 0 in 10 patients, 1 in 48 patients and 2 in one patient. The clinical stage according to the UICC was stage III in 53 cases and stage IV in 18 cases. The most common grade 3 acute toxicities were hematological toxicity (51%) and anorexia (8%). Dose limiting toxicity (DLT) developed as an early adverse event in three of the 71 patients: grade 3 cholangitis in one patient and grade 4 leukopenia in two patients, indicating a low incidence. With regard to late toxicities, one patient treated at the 50.4 GyE dose level developed a grade 3 gastric ulcer 10 months after undergoing CIRT; however, the patient recovered with conservative management. No other serious adverse events were observed. The combination therapies with full-dose gemcitabine (1,000 mg/m2) were notassociated with an increased incidence of adverse events with dose escalation. The median survival time was 21 months. Among all patients, the two-year local control rate and two-year overall survival rate were 74% and 39%, respectively. In the high-dose group (n=47), in which the patients were irradiated with at least 45.6 GyE, the two-year local control rate and two-year overall survival rate were 86% and 49%, respectively.Conclusions: C-ion RT is well tolerable even when concomitantly administered with the highest dose of gemcitabine (1,000 mg/m2). Long-term survival or a radical cure can be expected following further dose escalation or the administration of maintenance chemotherapy.The Cancer Symposium: Advanced Radiation Oncology Treatment Strategies with Photon, Proton, and Carbon Ion Radiatio

Particle Radiation Therapy for Gastrointestinal Cancers.

Particle irradiation of cancerous disease has gained great traction in recent years. The ability for particle therapy centers to deliver radiation with a highly conformal dose distribution while maintaining minimal exit or excess dose delivered to normal tissue, coupled with various biological advantages particularly found with heavy-ion beams, enables treatment of diseases inapproachable with conventional radiotherapy. Here, we present a review of the current status of particle therapy with regard to cancers of the gastrointestinal tract, including esophagus, liver, pancreas, and recurrent rectal cancer

Four-dimensional treatment planning in layer-stacking boost irradiation for carbon-ion pancreatic therapy

Purpose: We evaluated respiratory-gated carbon-ion beam dose distribution with boost irradiation in pancreatic therapy and compared results between the passive scattering and layer-stacking (a kind of semi-active scanning) irradiation techniques.Materials and Methods: A total of 21 patients who were treated with conventional passive carbon-ion beam for pancreatic cancer underwent 4DCT imaging under free-breathing conditions. We defined two types of clinical target volume (CTV) for the initial and boost irradiations: CTV1 included the gross tumor volume (GTV) and peripheral organs, and CTV2 included the GTV only with an added uniform 2-mm margin. Planning target volumes 1 and 2 (PTV1 and PTV2) were calculated by adding the range variation considered internal margin defined by 4DCT to the respective CTVs. The initial prescribed dose (= 45.6Gy(RBE); RBE-weighted absorbed dose) was given to PTV1, and the boost dose was increased up to 26.4Gy(RBE) and given to PTV2. Dose assessments were compared between irradiation techniques using the paired t-test.Results: D95(GTV, CTV2) values were increased from 44.2Gy(RBE) with the prescribed dose of 45.6Gy(RBE) to 69.8Gy(RBE) with the prescribed dose of 72.0Gy(RBE) with both irradiations. Layer-stacking irradiation reduced excessive dosing to normal tissues compared with passive scattering irradiation, particularly for boost irradiation. 1st-2nd portion V20/V40, and stomach V20 values up to the prescribed dose of 48.0, 60.0, and 52.8Gy(RBE) were smaller than those in passive scattering irradiation without boost. Kidney V15/V30 (0.6%(P=0.05)/0.1%(P>0.20) for right kidney, 10.4%(P0.06)), and stomach V20 (16.3%(P<0.01)) values in layer-stacking irradiation were smaller than those in passive scattering irradiation up to the prescribed dose of 72.0Gy(RBE) and also smaller than those with passive scattering irradiation without boost irradiation (= 45.6Gy(RBE)).Conclusions: In pancreatic particle beam therapy, delivery of the prescribed dose by layer-stacking boost irradiation provides a greater reduction in excessive dose to normal tissues than delivery by passive scattering irradiation

Four-dimensional Treatment Planning in Layer-stacking Boost Irradiation for Carbon-ion Pancreatic Therapy

American Society for Therapeutic Radiology and Oncology ASTRO\u27s 54th Annual Meetin