This paper is based on my invited talk at the Brachytherapy Subcommittee of JASTRO meeting in June of 2003 in Tokyo. It presents basic information regarding seed implant, specifically, iodine 125 (I-125) seed implant history, characteristics and dosimetry of I-125, minimum equipment requirements for implant and snapshots of pictures taken during a seed implant procedure in the operating room. It can not be stressed enough that the seed implant program is only successful when one has a good collaborative team including members from Urology, Radiology, Radiation Oncology, Medical Physics and other medical support staff.

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Education in radiation biology for medical students was initiated about 40 years ago. Radiation biology supports the diagnostics and therapeutics of radiology and radiation oncology. The studies about the effectiveness of these disciplines in promoting human health have been advanced remarkably since the discovery of radiation and radioactivity. At the same time, these fields have been swayed by many misgivings. Recently, the progress in radiation biology has continued to receive support from advances of molecular biology. Therefore, radiation diagnostics and therapeutics are also explained from a molecular basis. However, molecular biology has also provided much important information about the biological harmful effects of radiation and radioactivity on human health such as the cell death, mutation and carcinogenesis. Radiation sensitivities and radiation-induced cancer are well understood from the perspective of advance in the classification of DNA damage, DNA repair mechanism and function of cancer-related genes. Furthermore, radiation biology has given much useful information to the beginning of life, evolution and continuance of life. Herein, I introduce the contributions of radiation biology in medical education.

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In radiation therapy of malignant tumors, more than 40years has elapsed since the conformation radiotherapy was introduced for clinical use. The idea of this irradiation technique is that in order to obtain a good local control rate for tumors and reduce severe complications, a high dose is given as much as possible to the tumorous lesion, and irradiation is spared to the surrounding normal tissue. This treatment policy is now actively used and this technique has been developed furthermore through an application of diagnostic imaging for treatment planning, use of treatment planning system with computer technology, and broad distribution of a newly designed multi-leaf collimator (MLC). These examples of development in technology are stereotactic radiotherapy, three-dimensional conformation radiotherapy (3D-CRT), and IMRT (intensity modulated radiotherapy). With such a situation, various kinds of conformation radiotherapy have been introduced with different methodologies and technologies, and the term of the meaning of “conformal” is now understood with various methods in use. Now, radiation oncology has been developed in the field of computerized technology and fundamental biochemical research such as normal tissue tolerance or gene analysis. The object of research work in conformation radiotherapy had been mainly to improve the dose distribution so far, however, more optimal irradiation methods might be developed with the support of modern biochemical research projects. In this article, development of conformation radiotherapy is overviewed historically and future prospects are discussed.

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The purpose of this paper is to compare miniphantoms and build-up caps for determination of head scatter factors. We measured the head scatter factors of photon beams of 4MV, 6MV, 10MV (Varian-Clinac600C and 2100C) and 10MV, 14MV, 20MV, 21MV, 25MV, 50MV (Scanditronix-Microtron MM22 and MM50) with miniphantoms and build-up caps. In the range of higher energy than 10MV, the head scatter factors measured with the build-up caps were higher than those measured with the miniphantoms. The differences were getting more significant in larger fields and in higher energy than 10MV. The differences were insignificant in 4MV, 6MV and 10MV of Clinac. We confirmed the contamination electrons had much influence on the build-up caps with higher energy photon beams than 10MV. The build-up caps were useful to determine head scatter factors in lower energy than 10MV. The miniphantoms were useful to determine head scatter factors in higher energy than 10MV. Both of miniphantoms and build-up caps are necessary for measuring head scatter factors for 10 MV photon beams. Either miniphantoms or build-up caps can be selected depending on accuracy head scatter factors.

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Purpose: To investigate the effects of inhomogeneity correction algorithms on dose calculations using an inhomogeneity phantom and clinical cases of lung cancer.
Materials and methods: Two inhomogeneity correction algorithms, the Batho (generalized Batho Power Law) and equivalent tissue-air-ratio (ETAR) equipped with Cadplan Helios ver. 6.01, were evaluated in the present study. Using phantoms with 5 and 10 cm cork layers between water density material layers, the central axis depth doses for points beyond the cork layer were measured and compared with the calculated doses, with and without inhomogeneity corrections. Photon beams of 6 and 10 MV were used. We analyzed the values of the monitor unit (MU) of 50 beams calculated with and without correction algorithms using patient data from patients with lung cancer.
Results: In the phantom experiments, the measured doses showed overdoses of 6.7-21.8% compared with the calculated doses without inhomogeneity correction algorithms. The measured doses with the Batho algorithm ranged from 0.938 to 1.003 of the calculated dose. The ETAR algorithm had a tendency to predict lower values than the Batho algorithm. In the patient data analysis, the Batho and ETAR yielded underdosing of 4.2% and 5.6% on average, respectively, compared with the uncorrected doses.
Conclusions: The inhomogeneity correction algorithms, Batho and ETAR, are effective in predicting the doses delivered to points beyond the lung. However, in using these correction algorithms in clinical studies, the underdosing of the tumor doses should be considered compared with the uncorrected doses.

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A new hospital-based proton radiotherapy facility having two treatment rooms with a rotating gantry each and an experiment room with two horizontal beam ports was built at the Proton Medical Research Center (PMRC), University of Tsukuba. We started proton beam therapy as a clinical study to test the safety of the treatment equipment in September 2001. Six patients, a patient with liver metastases from ovarian carcinoma, two patients with lung carcinoma, a patient with cholangiocarcinoma, a patient with local recurrence of rectal carcinoma and a patient with bone metastasis from breast carcinoma, were enrolled in the study. They were considered unsuitable for other modalities of treatment, and were treated by proton beam therapy alone according to the methods used in the old facility at the University of Tsukuba. They were evaluated with regard to unexpected occurrences due to treatment equipment failures and treatment related toxicities. We observed no occurrence of hazardous events to the patients and no toxicities greater than grade II skin toxicities in the six patients. The results showed that the treatment system was safe and reliable for proton beam therapy.

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The treatment for angiosarcoma remains challenging. The effectiveness of Interleukin-2 (IL-2) has been reported, but no previous reports have been made regarding infection with methicillin-resistant Staphylococcus aureus (MRSA) as a clinical toxicity that occurs with the continuous intraarterial infusion of IL-2 combined with radiation therapy for angiosarcoma. We report two cases of angiosarcoma of the scalp treated with this combination therapy. Intraarterial infusion of IL-2 was performed through selectively inserted 4-French catheters. The catheters were inserted into the external carotid artery under fluoroscopic guidance through the occipital artery, which was exposed by a skin incision. IL-2 was continuously administered through the catheter. Radiation therapy was performed using 6-9 MeV electrons at a fraction dose of 1.8-2.0Gy, 5times a week, for a total dose of 68.8-75.6 Gy. It was possible to obtain favorable treatment effects, but MRSA infection, which was probably related to intraarterial infusion of IL-2 through surgically tunnelled intraarterial catheters, occurred in both patients. A combination therapy of continuous intraarterial infusion of IL-2 and radiotherapy is an effective treatment method for angiosarcoma of the scalp. This treatment of choice could contribute to the future management of angiosarcoma. However, there is a possibility of MRSA infection with this treatment.

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A case of squamous cell lung cancer with paraneoplastic nephrotic syndrome, successfully treated with radiotherapy alone is reported. A 67-year-old man was admitted with remarkable leg edema and proteinuria. A Chest X-Ray film and CT scan demonstrated a large mass of the left pulmonary hilus with atelectasis of the left upper lobe and lift pleural effusion. His renal disorder was proven to be nephrotic syndrome clinically and membranous glomerulonephritis histopathologically. The patient was given a diagnosis of squamous cell lung cancer and paraneoplastic nephrotic syndrome. Because of his poor general condition, he received radiotherapy alone, consisting of a total dose of 70 Gy, given as fractions of 2 Gy per day 5 days a week. Because the tumor responsed well to radiotherapy, proteinuria and body weight improved with disappearance of leg edema. Paraneoplastic nephrotic syndrome is associated with various malignancies, lung cancer is well known among the causative tumors. Removal of the primary tumor frequently enables improvement of nephotic syndrome. We therefore consider that radiotherapy could be an alternative treatment for unresecteble malignant tumors with paraneoplastic nephrotic syndrome.

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