The purpose of this study is to evaluate the accuracy of dose calculations by three algorithms.
Methods and Materials: Depth dose, OPF (Output Factor) and dose profiles were measured in a heterogeneous phantom. These values were also calculated by three algorithms of the Batho power law (BPL), Equivalent-TAR (ETAR) and Convolution superposition (CS). The data were obtained for 4, 6 and 10 MV photon beams with a linear accelerator (Varian 21EX). Field size ranged from 3-3cm2 to 10-10cm2. Dose profiles of beam penumbra were also measured by a 0.125ml ionization chamber at the point of 8, 13 and 18cm from the surface of the phantom at intervals of 1mm.
Result: Differences between measured and calculated depth doses were within 2% in BPL and CS, but depth doses were overestimated in ETAR. OPFs were also overestimated with the error of more than 4% in ETAR. Absorbed dose calculated by CS were in agreement with the values measured by the ionization chamber. The absorbed dose by BPL and ETAR, however, were overestimated in particular in absorbed dose of 85-95%. Conclusion: Although isodose lines by CS are precisely correct, the measured absorbed dose may be smaller than the prescribed doses calculated by BPL and ETAR. It should be noticed that calculated isodose lines may be significantly different from measured values in the treatment of lung tumors.

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Purpose: To determine whether proton beam irradiation induces the increase of IL-6 in plasma and which organ is most responsible for the irradiation.
Methods and Materials: Ten to twelve week old mice received whole body or partial body proton beam irradiation. Slit shaped ports were implemented for partial irradiation in order to distinguish the response of a designated organ, head, lung, liver, and lower abdomen. The concentrations of IL-6 in plasma were assayed three and half days after the irradiation.
Results: Whole body proton beam irradiation caused a significant elevation of IL-6 plasma levels the same as those occurred after photon beam irradiation. Partial proton beam irradiation explores the significant differences in the induction of IL-6 by the irradiated organ. Contrary to lung and head irradiation, lower abdominal irradiation and whole body irradiation lead the remarkable elevations of IL-6.
Conclusion: Although IL-6 was induced by proton beam irradiation to lower abdomen and to the whole body, proton beam irradiation to the liver did not cause elevation of IL-6. Because proton beam can avoid irradiation to digestive organs responsible for IL-6 induction, proton beam therapy is supposed to be an effective treatment for hepatocellular carcinoma.

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Since 1995, the Japanese Society for Therapeutic Radiology and Oncology (JASTRO) has held a teaching seminar for medical doctor candidates. In 1997, thirty-three students participated in the seminar. After graduation, eighteen (18/33) of the participants became radiologists and twelve of them (12/18) majored in radiation oncology. These results imply that the seminar might have an impact on their career paths. Hence, we propose that the seminar can have an influence upon the career decision of medical students, and it could yield a breakthrough to overcome in the shortage of radiation oncologists in Japan.

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Purpose: A NJRTOG survey was carried out to disclose the risk management of radiation therapy.
Materials and Methods: During April 2002, we sent questionnaires to radiation therapy facilities in northern Japan.
Results: There were 31 replies from 27 facilities. Many incidents and accidents were reported, including old cases. Although 60% of facilities had a risk management manual and/or risk manager, only 20% had risk management manuals for radiation therapy. Eighty five percent of radiation oncologists thought that incidents may be due to a lack of manpower. Ninety percent of radiation oncologists want to know the type of cases happened in other facilities.
Conclusion: The risk management system is still insufficient for radiation therapy. We hope that our data will be a great help to develop risk management strategies for radiation therapy for all radiation oncologists in Japan.

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In order to clarify the current status of treatment policies and treatment technique of high-dose rate brachytherapy practice for cervical cancer in Japan, national survey was performed in 2001. The questionnaire was sent to 215 institutions holding high and medium dose rate Remote Afterloading System (RALS), and 199 (93%) responses were received. Of these responders, 175 performed typical brachytherapy with tandem and ovoid for a total of 2, 007 patients with carcinoma of the cervix in 2000. There was a wide variant in the doses used. The median EBRT dose was 50 Gy and 50 Gy and the median HDR dose was 25 Gy and 24 Gy for early and advanced cancers, respectively. Brachytherapy was performed weekly by 138 (82%) institutions, and twice a week by 31 (18%) institutions. The median brachytherapy dose per fraction was 6 Gy for early and advanced cancer in the case of weekly brachytherapy. On the other hand, that dose was 5 Gy in the case of twice a week. The median total treatment time was 6.5 weeks and 7 weeks for early and advanced cancers, respectively.
This retrospective survey showed the current brachytherapy practice pattern in the treatment of cervical cancer in Japan. There was a variation in the brachytherapy practice pattern. We should discuss with each other about the dose evaluation method for reference volume and reference point.

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Purpose: To describe the implementation and use of a real-time radiotherapy conference system between a university hospital and a regional hospital.
Materials and methods: Remote desktop software was used to share the computer screen (desktop) and to operate the radiotherapy planning system in a regional hospital. Two hospitals were connected by an ADSL (12 Mbps) network. To secure the data, virtual private network (VPN) protocol was used. In the regional hospital, ECLIPSE (Varian Medical system) radiotherapy planning system and a remote desktop server software was installed. In the university hospital, a remote desktop viewer was installed in an Windows based PC; radiotherapy planning system was not installed.
To reveal the usefulness of this system, the time to open a radiotherapy plan, and time to modify the plan were measured using 11 cases.
Results: Sharing the same computer screen between the regional hospital and university hospital enabled real-time and interactive remote radiotherapy conferencing. Eight to 16 seconds was needed to send the computer screen data. Time to open a radiotherapy plan, 6.4±2.5 minutes was needed. To modify the radiation plan, an additional 3.8±1.6 minutes/field was needed. The time to complete the radiotherapy planning, 16±4.7 minutes was needed
Conclusions: Remote radiotherapy conference system using the remote desktop software was a real time, easy to use, low-cost, and useful system. Using the relatively slow network system (ADSL 12 Mbps; up-word speed 512 kbps), the discussion was concluded within 20 minutes for a patient in most cases. We recommend an optical fiber network to reduce time lag.

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