The ICRU, Inter-Society Council for Radiation Oncology (USA), and ESTRO have for many years had a great interest in quality assurance. The Committee for Quality Assurance of JASTRO published a “Guidelines for QA Systems in External Radiotherapy” in 1997. In this Paper, we review the various components of quality assurance based on the Guidelines. The role of QA committees in hospitals are reviewed, stressing its interdisciplinary nature relative to medical physicists, radiation oncologist, and radiation oncology technologists. Implementations of QA systems are reviewed for inventory of the existing protocols, quality audit procedures, detection of weaknesses in systems for continuous quality improvement, and clinical aspects. The latter increases efficiency and improves the quality of care for patients. The recommendations in this paper rely on reports by the AAPM and ACR, and discussions by the Committee for Quality Assurance of the JASTRO.

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Rationales for chemoradiation to overcome the limitations of radiotherapy alone were discussed in this article from a viewpoint of the purpose for combined use of chemotherapy. Accumulated evidence indicates that radioresistance of advanced cancer seems primarily due to increased in-situ radioresistance of tumor stem cells and not to their large number. Thus, radiosensitization for the tumor cells is required for these cancers by the combined use of chemotherapy.
Its combination with platinum compounds administered prior to irradiation causes radiosensitization of hypoxic tumor cells. Furthermore the accompanied inhibition of recovery from sublethal cell damage further increases the effectiveness of the concurrent chemoradiation therapy in the fractionated schedule. Experiments have revealed that this type of combination increases therapeutic ratio against early and late normal tissue reactions. Furthermore the efficacy of chemoradiation is considered higher when chemotherapy is combined during the late phase in the fractionated radiotherapy course, since combination in this phase will not increase the severity of early normal tissue reaction, but effectively inhibit the repopulation of tumor cells, which is accelerated during the late phase in the fractionated schedule.
The effect of chemoradiation on tumor cells outside the target volume seems extremely limited as revealed in clinical trials, and thus further study is certainly needed.

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This study examined the temporal responses in preventing neointimal proliferation of rabbit iliac arteries where ¹⁹²Ir-HDR intra-vascular irradiation was carried out after PTA with a cutting balloon catheter. PTA was performed in both iliac arteries of twenty rabbits. Intravascular irradiation was performed on the same segment with PTA on the iliac artery of one side and the unirradiated side was studied as a control. The radiation dose was 12 Gy. Animals were euthanatized at 1, 2, 3, 4, 8, and 12 weeks after angioplasty. Histopathologic and morphometric analyses were then carried out.
PTA caused radial stretching of the artery and medial compression. Internal elastic lamina was cut with a cutting blade and deep dissections were made extending into the media. Histopathology showed that cellular accumulation repaired the dissection and neointimal proliferation followed. A striking reduction in the amount of neointimal proliferation in the irradiated arteries was observed compared with the control vessels. At a week, the neointima area had markedly increased to 0.63 ± 0.21 × 10^-4 mm² in the control arteries, while no evidence of neointimal proliferation was noted in the irradiated artery segments. At 2-4 weeks, a marked and statistically significant decrease in the neointima area was observed compared with the control arteries. The control arterial segments had a neointimal area of 9.06 ± 3.47 × 10^-4 mm². The neointimal area was 3.24 ± 1.61 × 10^-4 mm² in the irradiated artery (p<0.01). At 8-12 weeks as well, a significant difference was noted between the irradiated and the control arterial segments. The control arterial segments had a neointimal area of 9.18 ± 3.63 × 10^-4 mm², while the irradiated arterial segments had 3.51 ± 1.55 × 10^-4 mm².
From the above results, the ¹⁹²Ir-HDR afterloading irradiation with a dose of 12 Gy can be considered sufficient for inhibiting neointimal proliferation in angioplastied rabbit iliac arteries with a cutting balloon catheter.

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To evaluate the effectiveness of accelerated hyperfractionated radiationtherapy (AHF) and the impact of biologically effective dose corrected for overall treatment time (cBED) upon tumor control, a retrospective study was carried out on 54 previously untreated patients with stage I or II laryngeal cancers. Irradiation was performed using bilateral opposing fields of a ⁶⁰Co teletherapy unit. Fourteen patients treated with AHF exhibited a significantly better tumor control than 40 others receiving conventional radiation therapy. The patients with high cBED included all those treated with AHF, and exhibited a significantly better tumor control than those with low cBED. Multivariate analyses demonstrated cBED to be a significant variable for tumor control, although clinical stage (I/II), site (glottis/ supraglottis), total target dose, and combination with intensive chemotherapy were not significant. These results indicate that AHF holds promise for the radiotherapeutic management of stage I and II laryngeal cancers, and that the biological effectiveness of various dose fractionations can be interpreted using cBED.

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Purpose: To evaluate definitive radiation therapy delivering doses in excess of 60 Gy for elderly patients with non-small cell lung cancer (NSCLC).
Materials and Methods: The treatment results for 93 patients aged 75 years or older (mean age, 78 years; elderly group) with limited NSCLC were retrospectively analyzed and compared with those for 193 patients younger than 75 years old (mean age, 64 years; younger group). The elderly patients were classified into two groups: 64 patients aged 75-79 years (the elderly A) and 29 patients aged 80 years or older (the elderly B). All patients were treated with 10 MV X-rays using 2 Gy daily standard fractionation between 1976 and 1994. The total dose ranged from 60 Gy to 80 Gy.
Results: The overall two and five year survival rates were 31% and 12% for the elderly A group, and 28% and 6% for the elderly B group, respectively, compared with 34% and 12% for the younger group. There was not a statistically significant difference in survival rates among three groups. In stage I-II NSCLC patients, the 2-year and 5-year disease-specific survival rates were 61% and 43% for the elderly A group, and 55% and 17% for the elderly B group, respectively, while the corresponding rates for younger group were 56% and 22%, respectively. There was also no significant difference in survival curves among three groups. In patients with stage III disease, however, the survival curves of the elderly B were inferior to those of the younger group and the elderly A group, although the difference was not statistically significant. Only two elderly patients died of late pulmonary insufficiency associated with highdose irradiation of 80 Gy to the proximal bronchus. No other treatment-related event was observed except for mild acceptable acute complications in the elderly groups. The condition of two patients aged more than 80 years, however, deteriorated in mentality during hospitalization.
Conclusions: Definitive radiation therapy is recommended to the elderly aged 75 years or older with limited NSCLC, especially early stage disease, as an acceptable choice of treatment.

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Purpose: Radiation myelopathy is one of the most serious late effects of irradiation. An investigation of different doses local effect with/without CDDP for the cervical spinal cord in Wister rats after single doses of irradiation was performed. In this study, radiation myelopathy was evaluated clinically, pathologically and using MR imaging with time course.
Materials and methods: Totally, 61 male wister rats were examined. 41 animals were evaluable. Single doses of 20, 25 and 30 Gy were given to the cervical spine of the animals using 3 MV X-ray sourse. In another group of rats, 4 mg/kg of CDDP was injected intraperitoneally 30 minutes before irradiation. Every rat was observed at least twice a day, and body weight was measured every week. The incidence of radiation-inducd paralysis was used as the endpoint. MR imaging was performed serially. Finally, the rat was dissected and cervical spinal cord was taken and fixed in formarin. A specimen was made and radiation-induced myelopathy was pathologically confirmed.
Results: In 18 months of follow up, 32 animals out of a total of 40 developed paralysis, with histological evidence of parencymal and vascular changes in the white matter. Mass effects and higher T2 signal within the irradiated cervical spinal cord were detected in the paralytic rats. The number of paralytic rats of each dose with/without CDDP was as follows: for CDDP (-) 20, 25 and 30 Gy, CDDP (+) 20, 25 and 30 Gy, 2/7, 6/6, 6/6, and 5/8, 6/6 7/7 respectively. Latent periods before initial onset of paralysis in each goupe ware, 30 Gy: 24.2 (±8.1) weeks, 25 Gy: 44.7 (±11.5) weeks and 20 Gy: 65.0 (±12.4) weeks. There was a significant difference between irradiated dose and latent periods of paralysis.(p<0.05) A tendency of shorter latent period of paralysis with CDDP was observed. As histopathological findings, vascular changes and vast demyelinization were seen in cervical spinal cord of paralytic rats.
Conclusion:
1. Significant dose-related differences in responce were detectable in the cervical spinal cord of Wister rats after a single dose of irradiation.
2. A tendency of quicker onset of paralysis with CDDP was observed comparing with the group without CDDP.
3. In irradiated cervical spinal cord, mass effects with low T1 and high T2 signal within the cord parencyma were seen in MR imaging. These findings could be detected 7-14 days before the onset of paralysis, and emphasized with its degree.
4. Vascular changees and vast necrosis and/or demyelinization in white matter were detected in cervical spinal cord in paralytic rats.

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In an effort to improve upon the historically poor local control and survival rates for locally advanced prostate cancer, a clinical trial was performed using intraoperative radiation therapy (IORT). Between April 1983 and May 1996, 54 patients with locally advanced prostate cancer (18 Stage B2, 26 Stage C, 10 Stage D1) were treated with a combination of (a) local external irradiation of 30 Gy in 2 Gy daily fractions, (b) IORT of 25 or 30 Gy, (c) pelvic lymphadenectomy, and (d) neoadjuvant and/or adjuvant hormonal therapy. A retropubic approach was employed as an operative procedure, and the electron energies selected ranged from 9 to 20 MeV. Since July 1987, a spacer had been inserted into the rectum at IORT to minimize the posterior rectal dose.
When 30 Gy was delivered at IORT without using a spacer, the incidence of grade 3 or 4 rectal morbidity was 20%, while, with the use of a spacer and delivering 30 Gy, the incidence of grade 3 morbidity decreased to 7 % and no grade 4 morbidity was observed. And when delivering 25 Gy using a spacer, no major morbidity was observed. The 5-year disease specific survival, relapse-free survival, and clinical local control rates for all patients were 89%, 74%, and 83%, respectively. The 2 and 5-year biochemical no evidence of disease (b-NED) survival rates for patients treated since 1992 were 90% and 75%, respectively. These results suggest that locally advanced prostate cancer can be well controlled by this unique and aggressive approach. Because of the small sample size and the relatively short follow-up period of time, however, further investigation is required for complete assessment.

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The importance of Quality Assurance (QA) has well been recongnized in radiotherapy. However, no standard report on manpower and equipment has been available in Japan. This study is the consensus recommendation of the research group organized under the support of the grant from the Ministry of Health & Wealfare. In this recommendation, radiotherapy institutions were categolized in three groups. The large institution has 300 or more radiotherapy patients per year, medium one 150-300, and small one 150 or less, respectively. The institutions were also categorized according to the following criteria:(1) number of the board certified radiotherapists, (2) number of medical physicists, (3) number of radiotherapy technologists, (4) area of radiotherapy facility, (5) radiotherapy related equipment, (6) experience in intraoperative radiotherapy, stereotactic irradiation, total body irradiation, brachytherapy, conformal radiotherapy, and hyperthermia, (7) patient registration for the JASTRO data base, (8) annual dose calibration by the Radiotherapy Dosimetry Center.

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