Long‐term cerebral effects of small doses of X‐irradiation in childhood as manifested in adult visual evoked responses

Yaar, Israel; Ron, Elaine; Modan, Michaela; Peretz, Hava; Modan, Baruch

doi:10.1002/ana.410080307

Cited by 26 publications

(8 citation statements)

References 30 publications

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“…A separate analysis of visual evoked responses on 44 irradiated and 57 controls also showed significant differences between the groups (Yaar et al, 1980).…”

Section: Exposure To Doses Of <5 Gymentioning

confidence: 84%

ICRP PUBLICATION 118: ICRP Statement on Tissue Reactions and Early and Late Effects of Radiation in Normal Tissues and Organs — Threshold Doses for Tissue Reactions in a Radiation Protection Context

Stewart¹,

Akleyev²,

et al. 2012

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This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

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“…A separate analysis of visual evoked responses on 44 irradiated and 57 controls also showed significant differences between the groups (Yaar et al, 1980).…”

Section: Exposure To Doses Of <5 Gymentioning

confidence: 84%

ICRP PUBLICATION 118: ICRP Statement on Tissue Reactions and Early and Late Effects of Radiation in Normal Tissues and Organs — Threshold Doses for Tissue Reactions in a Radiation Protection Context

Stewart¹,

Akleyev²,

et al. 2012

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“…It is still possible that, with the passing of time, additional basal meningiomas will be identified. Yaar,et al,54 stated that in irradiated individuals the left side of the head was exposed to a higher radiation dose than the right side. Our PIM's were equally distributed on the left and right side, presumably because the difference in irradiation dose between the two sides was of small magnitude and had no effect on our relatively small series.…”

Section: Discussionmentioning

confidence: 98%

Intracranial meningiomas following low-dose irradiation to the head

Soffer¹,

Pittaluga²,

Feiner³

et al. 1983

Journal of Neurosurgery

153

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Earlier reports have suggested that low-dose ionizing irradiation might be involved in induction of intracranial meningiomas. One of the problems in evaluating irradiation-induced neoplasms is the belief that these tumors have no distinguishing features to indicate their etiology. In an attempt to identify such features in meningiomas following irradiation, a group of 42 post-irradiation meningiomas (PIM's) has been compared with a group of 84 non-PIM control meningiomas. These 42 PIM's included all the intracranial meningiomas diagnosed at the Hadassah University Hospital during the years 1952 to 1981 in individuals treated in childhood with low-dose x-ray therapy for tinea capitis. Although the individual PIM does not seem to differ from a "spontaneous" meningioma, this study indicates that PIM's as a group have distinct characteristics, namely, their location at the site of maximal irradiation, and features suggesting rapid growth and aggressive biological behavior. There was a significantly higher number of calvarial tumors (p less than 0.001), a high proportion of multiple meningiomas, a higher recurrence rate following apparent complete excision (p less than 0.02), and an increased number of histologically malignant meningiomas (p less than 0.01). The demonstration of features that distinguish PIM's from meningiomas of other etiology supports the suggestion that low-dose ionizing irradiation was involved in the pathogenesis of these tumors.

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“…At the same time, evidence of delayed radiation brain damage (lower examination scores on scholastic aptitude, IQ, and psychological tests, completed fewer school grades, increased risk for mental hospital admissions, slightly higher frequency of mental retardation, and EEG abnormalities) was revealed 20 years after childhood scalp irradiation in average doses to the brain of only 1.3 Gy in a cohort of nearly 20,000 Israel children exposed to X-ray irradiation of the head for ringworm (tinea capitis) management (Yaar, Ron, Modan, Perets, & Modan, Data Science Journal, Volume 8, 24 September 20091980Yaar, Ron, Modan, Rinott, Yaar, & Modan, 1982;Ron, Modan, Flora, Harkedar, & Gurewitz, 1982). Among these persons 40 years after radiotherapy (the mean estimated radiation dose to the brain was 1.5 Gy), excessive relative risks per 1 Gy were observed for benign meningiomas and malignant brain tumors (Sadetzki, Chetrit, Freedman, Stovall, Modan, & Novikov, 2005).…”

Section: 3mentioning

confidence: 99%