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The present concept of dosimetric radiation protection quantities for external radiation is reviewed. For everyday application of the concept some adaptations are recommended. The check of the compliance with dose limits should be performed either by the comparison with values of the respective operational quantities directly or by the calculation of the protection quantity by means of the operational quantity, the appertaining conversion coefficient and additional information of the radiation field. Only four operational quantities are regarded to be sufficient for most applications in radiation protection practice. The term equivalent should be used in the connection dose equivalent only. Proposals are made for names of frequently used operational quantities which are denoted up to now by symbols only.
A historical perspective is given of the current paradigm that does not explicitly protect nonhuman biota from radiation but instead relies on the concept that if dose limits are set to protect humans, then the environment is automatically protected as well. We summarize recent international questioning of this paradigm and briefly present three frameworks for protecting biota that are being considered by the U.S. Department of Energy, the Canadian Nuclear Safety Commission, and the International Commission on Radiological Protection. We point out a controversial component in each of the three frameworks and suggest topics that need additional research. We emphasize that to properly address radiation protection of the environment, we need to understand how effects are integrated across different levels of biological organization. We caution that the proposed use of molecular end points to estimate ecological risks from radioactive contamination is applicable only if we understand the extent of the impact that molecular damage has on individual organisms and populations of exposed biota. To accomplish the latter, enhanced collaborations are required among the traditionally separate disciplines of radiation biology and radiation ecology.
Radiation sickness manifestations have been studied in two species (Macaca fascicularis and Papio hamadryas) exposed to electron and gamma-neutron radiations in a wide supralethal doses range. Dose-response relationships have been calculated for mortality and some clinical manifestations of the intestinal and cerebral forms of radiation sickness. Higher radiosensitivity of baboons in comparison with Macaca fascicularis and clinically more dangerous damage due to electrons as compared to gamma-neutron radiation have been demonstrated.
Radiation sickness manifestations have been studied in dogs exposed to electrons (electron energy 25 MeV) and gamma-neutron radiation (neutron energies of 0.37 and 1.2 MeV) in a wide dose range. Dose-response relationships have been calculated for mortality and some clinical manifestations of the intestinal and cerebral forms of radiation sickness. With regard to mortality, the highest effect has been observed for gamma-neutron radiation with a neutron energy of 1.2 MeV. For equal physical doses and for those equally effective in relation to mortality, clinical manifestations of damage are more prominent following exposure to electrons.
A phase Ilate/II trial of hyperfractionated (HFX) radiation therapy for non-small-cell carcinoma of the lung (NSCCL) was conducted by the Radiation Therapy Oncology Group (RTOG) between 1983 and 1987. Fractions of 1.2 Gy were administered twice daily with greater than or equal to 4 hours between fractions. Patients were randomized to receive minimum total doses of 60.0, 64.8, and 69.6 Gy. After acceptable risks of acute and late effects were found, 74.4 Gy and 79.2 Gy arms were added, and the lowest total dose arms were closed. No significant differences in the risks of acute or late effects in normal tissues were found among the 848 patients analyzed in the five arms; risks of severe or life-threatening pneumonitis were 2.6% for 60.0 to 64.8 Gy, 5.7% for 69.6 to 74.4 Gy, and 8.1% for 79.2 Gy. Among 350 patients who had the same criteria as Cancer and Leukemia Group B (CALGB) protocol 84-33 (American Joint Committee on Cancer Staging [AJCCS], 1984, stage III; Karnofsky performance status [KPS] 70 to 100; less than 6% weight loss), there was a dose response for survival: survival with 69.6 Gy (median, 13.0 months; 2 years, 29%) was significantly (P = .02) better than the lower total doses. There were no differences in survival among the three highest total-dose arms. Comparisons with results in similar patients treated with 60 Gy in 30 fractions of 2.0 Gy 5 days per week for 6 weeks suggest benefit from HFX radiation therapy with 69.6 Gy. Improvement in survival with HFX radiation therapy at 69.6 Gy total dose without increase in normal tissue effects, justifies phase III comparison with standard fractionation alone and combined with systemic chemotherapy in this common presentation of NSCCL.
The current status of radiation protection in Canada is discussed in the second of a three-part series and particular emphasis is placed on the role of the Radiation Protection Division of the Department of National Health and Welfare. Administrative and operational control procedures have been developed, involving prior approval of health safeguards in the radioisotope user's facilities and techniques, and systematic monitoring and inspection. Where necessary, a medical follow-up of accidents and excessive radiation exposures is carried out. In 1963 more than 1600 radioisotope licences were issued. Filmmonitoring service was provided to about 15,500 isotope and x-ray workers. Semiautomatic handling procedures have been developed to meet the increasing demand for film-monitoring services.Monitoring and inspection services have been provided for x-ray workers, and a committee has been formed to develop administrative procedures for health and safety control in x-ray work. Committees have also been set up to review the health and safety aspects of the operation of nuclear reactors and particle accelerators.
This paper (1) presents an analysis of published data on the molecular nature of spontaneously arising and radiation-induced mutations in mammalian somatic cell systems and (2) examines whether the molecular nature and mechanisms of origin of radiation-induced mutations, in mammalian in vivo and in vitro systems, as currently understood, are consistent with expectations based on the biophysical and microdosimetric properties of ionizing radiation. Depending on the test system (CHO cells, human T lymphocytes and human lymphoid cell line TK6), 80-97% of spontaneous HPRT mutations show normal Southern patterns; the remainder is due to gross changes, predominantly partial (intragenic) deletions. Total gene deletions at the HPRT locus are rare except in the TK6 cell line. At the APRT locus in CHO cells, 80-97% of spontaneous mutations are due to base-pair changes, the remainder being, mostly, partial deletions. The latter can extend upstream in the 5' direction but not beyond the APRT gene in the 3' direction. At the human HLA-A locus (T lymphocytes), the percentage of mutations with normal Southern patterns is lower than that for HPRT, and in the range of 50-60%. At the HLA-A locus, mitotic recombination contributes substantially to the mutation spectrum (approximately 30% of mutations recovered) and this is likely to be true of the TK locus in the TK6 cell line as well. With a few exceptions, most of the radiation-induced mutations show altered Southern patterns and are consistent with their being deletions and/or other gross changes (HPRT, 70-90% (CHO); 50-85% (TK6); 50-75% (T lymphocytes); TK, 60-80% (TK6); HLA-A, 80% (T lymphocytes); DHFR, 100% (CHO]. The exceptions are APRT mutations in CHO cells (16-20% of mutants with deletions or other changes) and HPRT mutations in T lymphocytes from A-bomb survivors (15-25%); the latter finding is consistent with the occurrence of in vivo selection against HPRT mutant cells. In cases of HPRT intragenic deletions analyzed (CHO cells and V79 Chinese hamster cells), there is evidence for a non-random distribution of breakpoints. The spontaneous mutation frequencies vary widely, from about 0.04/10(6) cells (sickle cell mutations at the human HBB locus) to 30.8/10(6) cells (HLA-A mutations in T lymphocytes) and are dependent on the locus, the system employed and a number of other factors. Those for the other loci fall between these limits.(ABSTRACT TRUNCATED AT 400 WORDS)
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The term "radiation hormesis" is thought of unsatisfactory one because it is difficult to define such concepts as "benefit", "harm" or "contributory" with respect to irradiation of biological species. The term does not take into account a fact that large doses stimulate the same biological processes and functions as low ones. The definition of the effect of radiation stimulation as physiological hyperfunction response of biological object to ionising radiation is proposed.
OBJECTIVES: Androgen deprivation therapy before and during radiation therapy could, by reducing tumor volume, increase local tumor control, disease-free survival, and overall survival in patients with locally advanced adenocarcinomas of the prostate. METHODS: In a randomized controlled clinical trial, patients with large T2, T3, and T4 prostate tumors, but no evidence of osseous metastasis, were randomized to receive goserelin 3.6 mg subcutaneously every 4 weeks and flutamide 250 mg orally three times daily 2 months before and during the radiation therapy course (Arm I) compared with radiation therapy alone (Arm II). Pelvic irradiation was administered with 1.8 to 2.0 Gy per day to a total dose of 45 +/- 1 Gy followed by a boost to the prostate target volume to a total dose of 65 to 70 Gy. RESULTS: Of 471 randomized patients, 456 were evaluable, 226 on Arm I and 230 on Arm II. With a median potential follow-up of 4.5 years, the cumulative incidence of local progression at 5 years was 46% in Arm I and 71% in Arm II (P < 0.001). The 5-year incidence of distant metastasis on Arms I and II was 34% and 41%, respectively (P = 0.09). Progression-free survival rates including normal prostate-specific antigen (PSA) levels for 396 patients with at least one PSA recorded were 36% in Arm I and 15% in Arm II at 5 years (P < 0.001). At this time, no significant difference in overall survival could be detected (P = 0.7). CONCLUSIONS: Short-term androgen deprivation with radiation therapy results in a marked increase in local control and disease-free survival compared with pelvic irradiation alone in patients with locally advanced carcinoma of the prostate. Long-term surveillance is required to assess effects on overall survival.
It appears that AB-132 potentiates radiation effects, and the local application of AET (MEG) protects the intestinal tract, the bladder and the skin against radiation toxicity. Combined use of selective radiation sensitizing and protecting agents may be considered for clinical studies.
In this study, a questionnaire survey was carried out to determine the actual situation of radiation safety management systems in Japanese medical institutions with nuclear medicine facilities. The questionnaire consisted of questions concerning the Radiation Protection Supervisor license, safety management organizations, and problems related to education and training in safety management. Analysis was conducted according to region, type of establishment, and number of beds. The overall response rate was 60%, and no significant difference in response rate was found among regions. Medical institutions that performed nuclear medicine practices without a radiologist participating accounted for 10% of the total. Medical institutions where nurses gave patients intravenous injections of radiopharmaceuticals as part of the nuclear medicine practices accounted for 28% of the total. Of these medical institutions, 59% provided education and training in safety management for nurses. The rate of acquisition of Radiation Protection Supervisor licenses was approximately 70% for radiological technologists and approximately 20% for physicians (regional difference, p=0.02). The rate of medical institutions with safety management organizations was 71% of the total. Among the medical institutions (n=208) without safety management organizations, approximately 56% had 300 beds or fewer. In addition, it became clear that 35% of quasi-public organizations and 44% of private organizations did not provide education and training in safety management (p<0.001, according to establishment).
PURPOSE: To evaluate the cost-effectiveness of adding hormone therapy to radiation for patients with locally advanced prostate cancer, using a Monte Carlo simulation of a Markov Model. METHODS AND MATERIALS: Radiation Therapy Oncology Group (RTOG) protocol 86-10 randomized patients to receive radiation therapy (RT) alone or RT plus total androgen suppression (RTHormones) 2 months before and during RT for the treatment of locally advanced prostate cancer. A Markov model was designed with Data Pro (TreeAge Software, Williamstown, MA). The analysis took a payer's perspective. Transition probabilities from one state of health (i.e., with no disease progression or with hormone-responsive metastatic disease) to another were calculated from published rates pertaining to RTOG 86-10. Patients remained in one state of health for 1 year. Utility values for each health state and treatment were obtained from the literature. Distributions were sampled at random from the treatment utilities according to a second-order Monte Carlo simulation technique. RESULTS: The mean expected cost for the RT-only treatments was 29,240 dollars (range, 29,138-29,403 dollars). The mean effectiveness for the RT-only treatment was 5.48 quality-adjusted life years (QALYs) (range, 5.47-5.50). The mean expected cost for RTHormones was 31,286 dollars (range, 31,058-31,555 dollars). The mean effectiveness was 6.43 QALYs (range, 6.42-6.44). Incremental cost-effectiveness analysis showed RTHormones to be within the range of cost-effectiveness at 2,153 dollars/QALY. Cost-effectiveness acceptability curve analysis resulted in a >80% probability that RTHormones is cost-effective. CONCLUSIONS: Our analysis shows that adding hormonal treatment to RT improves health outcomes at a cost that is within the acceptable cost-effectiveness range.
Long-term outcome of the Patterns of Care Study and the Radiation Therapy Oncology Group are used to demonstrate the national average results of treating early prostate cancer in the United States. A group of patients with stage T1B2 disease and pathologically negative lymph nodes showed excellent 10-year survival rates and freedom from clinical evidence of disease, while prostate specific antigen (PSA) correlations in 10-year survivors indicate that 88% were clinically free of cancer and had a PSA level of less than 4.0 mg./nl., and 65% had a PSA level of less than 1.5 ng./ml. The latter group represented clinical and biochemical cures. The improvement noted in outcome of locally advanced prostate cancer treatment by Radiation Therapy Oncology Group prospective trials combining androgen deprivation and radiation therapy is presented. These trials will be extended to the poor prognosis group with stage T1,2 disease. The advantages of conformal therapy in acute and late morbidity are illustrated with preliminary evidence of improved PSA response as a result of improved technique and higher dose associated with conformal 3-dimensional treatment.