Pions, and in particular negative pions, are of interest to radiology for at least three outstanding reasons: First, a beam of negative pions can produce in tissue depth and isodose distributions which, for treatment of deep-seated tumors, give a considerably better tumor-to-total-dose ratio than any other commonly used therapeutic radiation source (1). This improved ratio with pion irradiation is largely due to the short-ranged, heavily ionizing products resulting from nuclear pion interactions at the end of the pion track. Thus, second, an additional effectiveness of the dose delivered to the tumor relative to that delivered to healthy tissue is likely because of the oxygen effect observed with heavily ionizing radiation (2). Third, a pion beam seems at present to be the best choice in order to create a well-defined region in which nuclear reactions or nuclear stars give a substantial contribution to the radiation dose. Such conditions are essential for dosimetry and radio-biological research of strong nuclear interactions and thus for approaching a deeper understanding of the particular problems of high-energy dosimetry and radiobiology (3). In the following discussion, some experimental studies of the pion beam from the CERN 600-MeV Synchro-Cyclotron are reported. The results are limited to dosimetry and radiation quality measurements in a water phantom exposed to a 70-MeV pion beam; an attempt was also made to evaluate the average local energy deposition per stopped pion. The results are of a preliminary nature, and more extensive experimental investigations along the same lines are continuing.
{"title":"Radiological physics of pions.","authors":"J. Baarli","doi":"10.2307/3583695","DOIUrl":"https://doi.org/10.2307/3583695","url":null,"abstract":"Pions, and in particular negative pions, are of interest to radiology for at least three outstanding reasons: First, a beam of negative pions can produce in tissue depth and isodose distributions which, for treatment of deep-seated tumors, give a considerably better tumor-to-total-dose ratio than any other commonly used therapeutic radiation source (1). This improved ratio with pion irradiation is largely due to the short-ranged, heavily ionizing products resulting from nuclear pion interactions at the end of the pion track. Thus, second, an additional effectiveness of the dose delivered to the tumor relative to that delivered to healthy tissue is likely because of the oxygen effect observed with heavily ionizing radiation (2). Third, a pion beam seems at present to be the best choice in order to create a well-defined region in which nuclear reactions or nuclear stars give a substantial contribution to the radiation dose. Such conditions are essential for dosimetry and radio-biological research of strong nuclear interactions and thus for approaching a deeper understanding of the particular problems of high-energy dosimetry and radiobiology (3). In the following discussion, some experimental studies of the pion beam from the CERN 600-MeV Synchro-Cyclotron are reported. The results are limited to dosimetry and radiation quality measurements in a water phantom exposed to a 70-MeV pion beam; an attempt was also made to evaluate the average local energy deposition per stopped pion. The results are of a preliminary nature, and more extensive experimental investigations along the same lines are continuing.","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"1 1","pages":"10-9"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77059482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Physiological effects of space cabin atmospheres.","authors":"E M Roth","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"7 ","pages":"413-22"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15485512","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ultraviolet-induced excited states in deoxyribonucleic acid.","authors":"R O Rahn, R G Shulman, J W Longworth","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"7 ","pages":"139-46"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"15400944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Clinical studies of radiation effects in man: a preliminary report of a retrospective search for dose-relationships in the prodromal syndrome.","authors":"C C Lushbaugh, F Comas, R Hofstra","doi":"","DOIUrl":"","url":null,"abstract":"","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"7 ","pages":"398-412"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"17125208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite pioneering work by Snell and Aebersold (1, 2) nearly thirty years ago, our ignorance of the genetic effects of high-LET radiations in mammals was until recently almost complete. Large-scale studies now in progress on the genetic effects of fast neutrons in mice are rapidly changing the situation, however, so that a fairly coherent picture of one aspect of this subject is already emerging. This picture is one of high genetic effectiveness under most, but not all, conditions of irradiation. In the present paper we shall give the latest results of our own work in this field, then shall discuss these results in conjunction with those of other workers. In this manner, we hope to arrive at an overall view of the present state of knowledge, especially with regard to the immature germ-cell stages which are most important from the standpoint of long-term risk to populations. Preliminary results of a comparison of the genetic effectiveness of chronic neutron and y-ray exposures have already been published (3), and a full account of this experiment will appear shortly (4).
{"title":"Genetic effects of high-LET radiations in mice.","authors":"A. Searle, R. Phillips","doi":"10.2307/3583723","DOIUrl":"https://doi.org/10.2307/3583723","url":null,"abstract":"Despite pioneering work by Snell and Aebersold (1, 2) nearly thirty years ago, our ignorance of the genetic effects of high-LET radiations in mammals was until recently almost complete. Large-scale studies now in progress on the genetic effects of fast neutrons in mice are rapidly changing the situation, however, so that a fairly coherent picture of one aspect of this subject is already emerging. This picture is one of high genetic effectiveness under most, but not all, conditions of irradiation. In the present paper we shall give the latest results of our own work in this field, then shall discuss these results in conjunction with those of other workers. In this manner, we hope to arrive at an overall view of the present state of knowledge, especially with regard to the immature germ-cell stages which are most important from the standpoint of long-term risk to populations. Preliminary results of a comparison of the genetic effectiveness of chronic neutron and y-ray exposures have already been published (3), and a full account of this experiment will appear shortly (4).","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"19 1","pages":"294-303"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82519433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ions in passing through matter. The transverse distribution results from absorption of energy by the medium due primarily to the slowing down of the secondary electrons which have been ejected from the primary particle's track. Delta (5) rays are generally those secondary electrons that have an initial energy above some arbitrary threshold value so that there is a high probability that most of their energy will not be deposited in the vicinity of the ion track. An alternative definition would be that a rays are all secondary electrons which are ejected further than a given arbitrary distance from the ion track. In radiation biology, many radiation effects of heavy ions have been interpreted in terms of an inactivation cross section. Part of this total cross section is due to the ion track, and another part is due to 6 rays. The estimated cross section due to the 5 rays is subtracted from the total cross section to obtain the cross section due to the ion track. This procedure is called the 5-ray correction. Although it is well known that the contribution of 5 rays to the radiation effect of heavy ions is quite significant, our knowledge of 5 rays is very poor experimentally as well as theoretically. Thus far, almost all the 5-ray corrections have been made with several simplified assumptions about the processes of 5-ray production as well as on their slowing down, which have not yet been verified by experiment. Although it is most desirable to obtain complete experimental knowledge of the physical properties of the 8 rays, some specific information on 5 rays may suffice (depending on the methods of interpretation of the radiation effects, such as the target-theoretical analysis) for the study of the biological effect. Therefore, first let us discuss two alternative possible approaches to the 5-ray correction in connection with the present status of experimental information available for the low-energy secondary electrons. Then we shall present results of the measurements carried out on the secondary electrons from heavy ions from the Lawrence Radiation Laboratory's Hilac.
{"title":"Secondary-electron distribution for heavy ions.","authors":"N. Oda, J. Lyman","doi":"10.2307/3583696","DOIUrl":"https://doi.org/10.2307/3583696","url":null,"abstract":"ions in passing through matter. The transverse distribution results from absorption of energy by the medium due primarily to the slowing down of the secondary electrons which have been ejected from the primary particle's track. Delta (5) rays are generally those secondary electrons that have an initial energy above some arbitrary threshold value so that there is a high probability that most of their energy will not be deposited in the vicinity of the ion track. An alternative definition would be that a rays are all secondary electrons which are ejected further than a given arbitrary distance from the ion track. In radiation biology, many radiation effects of heavy ions have been interpreted in terms of an inactivation cross section. Part of this total cross section is due to the ion track, and another part is due to 6 rays. The estimated cross section due to the 5 rays is subtracted from the total cross section to obtain the cross section due to the ion track. This procedure is called the 5-ray correction. Although it is well known that the contribution of 5 rays to the radiation effect of heavy ions is quite significant, our knowledge of 5 rays is very poor experimentally as well as theoretically. Thus far, almost all the 5-ray corrections have been made with several simplified assumptions about the processes of 5-ray production as well as on their slowing down, which have not yet been verified by experiment. Although it is most desirable to obtain complete experimental knowledge of the physical properties of the 8 rays, some specific information on 5 rays may suffice (depending on the methods of interpretation of the radiation effects, such as the target-theoretical analysis) for the study of the biological effect. Therefore, first let us discuss two alternative possible approaches to the 5-ray correction in connection with the present status of experimental information available for the low-energy secondary electrons. Then we shall present results of the measurements carried out on the secondary electrons from heavy ions from the Lawrence Radiation Laboratory's Hilac.","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"5 1","pages":"20-32"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85415986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. F. Leong, N. P. Page, E. J. Ainsworth, G. Hanks
Although numerous studies have been conducted to describe injury accumulation and recovery in several mammalian species during and after exposure to ionizing radiation, the characterization of the time-course curve for injury and repair has never been fully resolved. It has been suggested by Blair, 2 that, after radiation injury, the recovery rate of animals increases exponentially with time. Extensive data by Sacher (1, 2) and by Sacher and Grahn (3) indicate that in the mouse radiation injury goes through a series of maxima at specific time intervals which correspond to intestinal and bone marrow death. Earlier investigations in our laboratory with multiple mammalian species after x-ray exposure have shown significant departures from the "hypothetical" exponential recovery pattern (4, 5). For example, a transient increased radiosensitivity has been detected for the hamster and the rabbit, whereas an increased radioresistance has been detected for the dog, swine, and sheep. Thus, any attempt to characterize the time course of injury accumulation or recovery by a single rate constant may be a gross oversimplification of a complex process involving various modalities of damage. Since the LDs5, the mean survival time, size, and body dimensions for sheep approximate those of man (LD50 and MST estimated), studies with sheep were extended for the purpose of evaluating hazards encountered following protracted irradiation exposure. The usual method for estimating mammalian recovery rates utilizes the split-dose technique as described by Hagen and Simmons (6). The technique consists in subjecting a group of animals to a single sublethal exposure to radiation and then determining the LD50 for these animals at subsequent time intervals. These measurements of the injury accumulation and the recovery from this injury during and after protracted exposure situations would provide a better under-
{"title":"Injury accumulation and recovery in sheep during protracted gamma irradiation.","authors":"G. F. Leong, N. P. Page, E. J. Ainsworth, G. Hanks","doi":"10.2307/3583722","DOIUrl":"https://doi.org/10.2307/3583722","url":null,"abstract":"Although numerous studies have been conducted to describe injury accumulation and recovery in several mammalian species during and after exposure to ionizing radiation, the characterization of the time-course curve for injury and repair has never been fully resolved. It has been suggested by Blair, 2 that, after radiation injury, the recovery rate of animals increases exponentially with time. Extensive data by Sacher (1, 2) and by Sacher and Grahn (3) indicate that in the mouse radiation injury goes through a series of maxima at specific time intervals which correspond to intestinal and bone marrow death. Earlier investigations in our laboratory with multiple mammalian species after x-ray exposure have shown significant departures from the \"hypothetical\" exponential recovery pattern (4, 5). For example, a transient increased radiosensitivity has been detected for the hamster and the rabbit, whereas an increased radioresistance has been detected for the dog, swine, and sheep. Thus, any attempt to characterize the time course of injury accumulation or recovery by a single rate constant may be a gross oversimplification of a complex process involving various modalities of damage. Since the LDs5, the mean survival time, size, and body dimensions for sheep approximate those of man (LD50 and MST estimated), studies with sheep were extended for the purpose of evaluating hazards encountered following protracted irradiation exposure. The usual method for estimating mammalian recovery rates utilizes the split-dose technique as described by Hagen and Simmons (6). The technique consists in subjecting a group of animals to a single sublethal exposure to radiation and then determining the LD50 for these animals at subsequent time intervals. These measurements of the injury accumulation and the recovery from this injury during and after protracted exposure situations would provide a better under-","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"33 1","pages":"288-93"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81941630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The effects of total-body irradiation on man have been studied clinically since Walsh (1) first described "radiation sickness" in 1897. Thus it is well-known that exposure to ionizing radiations can result in a delayed illness that may prevent a man from working. The dose-response relationships are poorly known (2, 3), however, and present estimates are based largely on conjectures derived by extrapolation from animal experiments (3) or from experience with radiation accident victims (4-9), atomic bomb casualties (3, 10-12) and therapeutically irradiated patients (1-3, 13-17). Because these estimates are all we have, it has been necessary to use them in the past for guidance in civilian defense, radiotherapy, and occupational medicine. They are not, however, sufficiently accurate for prediction of the probability that sublethal doses of radiation will cause deleterious functional effects that could lead to sudden or delayed decrements in performance capabilities (2). In developing the estimated residual dose (ERD) concept on which most occupational and civilian defense medical plans are based today (18-20), the ERD Committee did not consider a form of radiation sickness so mild that medical care was not required but severe enough to cause performance failure that could result in death. The Committee's conclusion, that 9 out of 10 persons exposed to less than
{"title":"Clinical studies of radiation effects in man: a preliminary report of a retrospective search for dose-relationships in the prodromal syndrome.","authors":"Lushbaugh Cc, F. Comas, Ruth B. Hofstra","doi":"10.2307/3583733","DOIUrl":"https://doi.org/10.2307/3583733","url":null,"abstract":"The effects of total-body irradiation on man have been studied clinically since Walsh (1) first described \"radiation sickness\" in 1897. Thus it is well-known that exposure to ionizing radiations can result in a delayed illness that may prevent a man from working. The dose-response relationships are poorly known (2, 3), however, and present estimates are based largely on conjectures derived by extrapolation from animal experiments (3) or from experience with radiation accident victims (4-9), atomic bomb casualties (3, 10-12) and therapeutically irradiated patients (1-3, 13-17). Because these estimates are all we have, it has been necessary to use them in the past for guidance in civilian defense, radiotherapy, and occupational medicine. They are not, however, sufficiently accurate for prediction of the probability that sublethal doses of radiation will cause deleterious functional effects that could lead to sudden or delayed decrements in performance capabilities (2). In developing the estimated residual dose (ERD) concept on which most occupational and civilian defense medical plans are based today (18-20), the ERD Committee did not consider a form of radiation sickness so mild that medical care was not required but severe enough to cause performance failure that could result in death. The Committee's conclusion, that 9 out of 10 persons exposed to less than","PeriodicalId":77888,"journal":{"name":"Radiation research. Supplement","volume":"164 1","pages":"398-412"},"PeriodicalIF":0.0,"publicationDate":"1967-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78133439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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