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PubMed2001

Interferon-gamma in 5 patients with cutaneous radiation syndrome after radiation therapy.

BACKGROUND: Irradiation can cause acute inflammatory responses as well as chronic fibrotic alterations of the skin. Cutaneous radiation fibrosis evokes a complex of therapeutic problems. However, therapeutic options, apart from surgical approaches, are limited. PATIENTS AND METHODS: Five female patients suffering from severe cutaneous fibrosis were treated with interferon-gamma on a low-dose regimen, 3 x 100 microg/week subcutaneously for 6 months, then once per week for another 6 months. In 4 patients, skin thickness was measured with high-frequency (20 MHz) ultrasound in a clinically well-defined target skin lesion. In 1 patient, nuclear magnetic resonance imaging was performed to quantify the extent of cutaneous radiation fibrosis and to monitor the therapeutic outcome. RESULTS: All patients suffered from radiation-induced cutaneous fibrosis. Additionally, in 1 patient, a fistula, as assessed by lymph vessel scintigraphy, and in another patient a radiation ulcer was diagnosed. In all patients, reduction of radiation-induced fibrosis could be documented. Both fistula and radiation ulcer regressed completely under interferon-gamma therapy. CONCLUSION: Low-dose interferon-gamma therapy is a new and effective treatment modality for cutaneous radiation fibrosis caused by radiation therapy. The positive impact of interferon-gamma on our patients warrants randomized double-blind trials on therapy of radiation fibrosis.

Adolescent↗
PubMed2003

Radiation-induced genomic instability and bystander effects: inter-related nontargeted effects of exposure to ionizing radiation.

The paradigm of genetic alterations being restricted to direct DNA damage after exposure to ionizing radiation has been challenged by observations in which cells that are not exposed to ionizing radiation exhibit responses typically associated with direct radiation exposure. These effects are demonstrated in cells that are the descendants of irradiated cells (radiation-induced genomic instability) or in cells that are in contact with irradiated cells or receive certain signals from irradiated cells (radiation-induced bystander effects). There is accumulating evidence that radiation-induced genomic instability may be a consequence of, and in some cell systems may also produce, bystander interactions involving intercellular signalling, production of cytokines and free-radical generation. These processes are also features of inflammatory responses that are known to have the potential for both bystander-mediated and persisting damage as well as for conferring a predisposition to malignancy. Thus, radiation-induced genomic instability and untargeted bystander effects may reflect inter-related aspects of inflammatory-type responses to radiation-induced stress and injury and contribute to the variety of pathological consequences of radiation exposures.

Animals↗
PubMed2004

Explosive radiations and the reliability of molecular clocks: island endemic radiations as a test case.

The reliability of molecular clocks has been questioned for several key evolutionary radiations on the basis that the clock might run fast in explosive radiations. Molecular date estimates for the radiations of metazoan phyla (the Cambrian explosion) and modern orders of mammals and birds are in many cases twice as old as the palaeontological evidence would suggest. Could some aspect of explosive radiations speed the molecular clock, making molecular date estimates too old? Here we use 19 independent instances of recent explosive radiations of island endemic taxa as a model system for testing the proposed influence of rapid adaptive radiation on the rate of molecular evolution. These radiations are often characterized by many of the potential mechanisms for fast rates in explosive radiations--such as small population size, elevated speciation rate, rapid rate of morphological change, release from previous ecological constraints, and adaptation to new niches--and represent a wide variety of species, islands, and genes. However, we find no evidence of a consistent increase in rates in island taxa compared to their mainland relatives, and therefore find no support for the hypothesis that the molecular clock runs fast in explosive radiations.

Adaptation, Biological↗
PubMed1987

Multimodal therapy for limited small-cell lung cancer: a randomized study of induction combination chemotherapy with or without thoracic radiation in complete responders; and with wide-field versus reduced-field radiation in partial responders: a Southwest Oncology Group Study.

In 1979 we initiated a phase III study in the Southwest Oncology Group (SWOG) which was designed to determine the value of chest radiation in limited-stage small-cell lung cancer patients achieving complete response after induction chemotherapy, and to test the use of wide-field v more limited-volume radiation in patients with partial responses (PRs) and patients with stable disease (SD). The induction chemotherapy (VMV-VAC) consisted of vincristine, 2 mg intravenously (IV) every week for six doses; methotrexate, 60 mg/m2 IV days 1 and 43; VP-16, 50 mg/m2/d IV days 1 to 5 and 43 to 47; doxorubicin, 60 mg/m2 IV days 22 and 64; and cyclophosphamide, 1,000 mg/m2 IV days 22 and 64. Four hundred ninety-four patients were registered, of whom 473 were eligible. Of 466 response-evaluable patients, 153 (33%) achieved complete disease remission (CR) with chemotherapy. A total of 387 patients entered the consolidation phase of treatment after chemotherapy and response determination. CR patients were prospectively randomized to receive chest radiation, consisting of 4,800 rad administered in a split-course scheme, or to continue chemotherapy without interruption. The treatment volume was based on tumor extent before the induction chemotherapy. Maintenance chemotherapy consisted of cyclophosphamide and VP-16 administered for four cycles before a period of reinduction chemotherapy consisting of VMV-VAC as described above. Patients receiving chest radiation therapy were given the same maintenance and reinduction chemotherapy programs following completion of the chest radiation. One hundred ninety-one eligible patients achieving PR or SD status after induction chemotherapy were randomized to a preinduction treatment volume or to a postinduction reduced tumor volume, with treatment portals designed according to tumor extent before or after induction chemotherapy, respectively. After completion of the entire treatment plan, there were 218 (47%) CRs and 121 (26%) PRs. These figures represent the greatest response achieved at any point in the treatment program. The median survival for all eligible patients was 57 weeks (74 weeks for CRs). Overall survival for CR patients was not different for patients who did or did not receive chest radiation. However, patterns of tumor relapse were affected by the chest radiation, as 38 of 42 relapsing patients who did not receive radiation had intrathoracic recurrences in comparison to only 20 of 36 radiated patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed2003

Radiation dosimetry and biophysical models of space radiation effects.

Estimating the biological risks from space radiation remains a difficult problem because of the many radiation types including protons, heavy ions, and secondary neutrons, and the absence of epidemiology data for these radiation types. Developing useful biophysical parameters or models that relate energy deposition by space particles to the probabilities of biological outcomes is a complex problem. Physical measurements of space radiation include the absorbed dose, dose equivalent, and linear energy transfer (LET) spectra. In contrast to conventional dosimetric methods, models of radiation track structure provide descriptions of energy deposition events in biomolecules, cells, or tissues, which can be used to develop biophysical models of radiation risks. In this paper, we address the biophysical description of heavy particle tracks in the context of the interpretation of both space radiation dosimetry and radiobiology data, which may provide insights into new approaches to these problems.

Astronauts↗
PubMed1999

[Activity leakage and radiation exposure in radiation synovectomy of the knee: influence of different therapeutic modalities].

In rheumatic diseases, radiation synovectomy is a reliable method. Meanwhile, radiation synovectomy is an outpatient therapy. In addition, combination with arthroscopic synovectomy is an increasing therapeutic modality. In comparison to the hitherto inpatient modality, a greater lymphatic emigration of the radionuclide and, therefore, a higher radiation exposure is possible. In 35 patients we found radionuclide emigration in 17 cases by whole body scintigraphy, resulting in a 50%-percentile with 68.27%-confidence interval of 1.8 (0.45-4.78)% of the injected yttrium-90-activity. Comparison of 3 groups with the above mentioned therapy modalities resulted in no statistical difference (p>0.05). Because of the found radionuclide emigration, a radiation dose of 0. 1 (0.05-0,18) mSv in women and 0.2 (0.1-0.38) mSv in men was calculated. For lymph nodes, liver, spleen and whole body radiation doses of 619 (154-1644) mSv, 62 (15-165) mSv, 62 (15-165) mSv and 37 (9-99) mSv were calculated. Gonadal radiation dose can be neglected and the morbidity rate for tumors because of the whole body radiation dose is low with a value of 0.4 per thousand. Therefore, radiation synovectomy can be used unlimited by patients age and independent of the therapeutic modality.

Adult↗
PubMed2007

Beta radiation shielding with lead and plastic: effect on bremsstrahlung radiation when switching the shielding order.

Lead and plastic are commonly used to shield beta radiation. Radiation protection literature is ubiquitous in advising the placement of plastic first to absorb all the beta particles before any lead shielding is used. This advice is based on the well established theory that radiative losses (bremsstrahlung production) are more prevalent in higher atomic number (Z) materials than in low Z materials. Using 32P beta radiation, we measured bremsstrahlung photons transmitted through lead and plastic (Lucite) shielding in different test configurations to determine the relative efficacy of lead alone, plastic alone, and the positional order of lead and plastic. With the source (32P) and detector held at a constant separation distance, we inserted lead and/or plastic absorbers and measured the reduction in bremsstrahlung radiation level measured by the detector. With these test conditions, analysis of measured bremsstrahlung radiation in various thicknesses and configurations of lead and plastic shielding shows the following: placing plastic first vs. lead first reduces the transmitted radiation level only marginally (10% to 40%); 2 mm of additional lead is sufficient to correct the "mistake" of placing the lead first; and for equal thicknesses or weights of lead and plastic, lead is a more efficient radiation shield than plastic.

Beta Particles↗
PubMed2006

Radiation injury: imaging findings in the chest, abdomen and pelvis after therapeutic radiation.

Radiation may be used as adjuvant or primary therapy in a variety of tumors in the chest, abdomen and pelvis. Therapeutic radiation affects not only malignant tumors but also surrounding normal tissues. The risk of injury depends on the size, number and frequency of radiation fractions, volume of irradiated tissue, duration of treatment, and method of radiation delivery. Concomitant chemotherapy can act synergistically to produce injury. Other predisposing factors include infection, prior surgery and chronic illness like hypertension, diabetes mellitus and atherosclerosis. Radiation changes vary, based on the target organ and the time from completion of therapy. While most serious complications related to radiotherapy are relatively uncommon, given the number of patients that are treated and the relatively long latency period for development of radiation changes, follow-up imaging studies frequently have findings that should be recognized as radiation related. Familiarity with the spectrum of imaging findings after radiation injury permits differentiation from other etiologies such as recurrent malignancy. The following will discuss imaging findings that may be seen during imaging surveillance in patients with malignancy affecting the chest, abdomen and pelvis.

Abdominal Neoplasms↗
PubMed2003

Radiation hormesis, or, could all that radiation be good for us?

OBJECTIVE: Nuclear medicine technologists work under significant radiation protection constraints. These constraints are based on the linear no-threshold (LNT) radiation paradigm, which was developed in the 1960s and was based largely on the deleterious effects of radiation as they were understood at the time. More recently, the theory of radiation hormesis, or a beneficial effect of low-level exposure to radiation, has gained recognition. This article reviews the history of attitudes toward radiation, describes the radiation hormesis hypothesis, examines some of the evidence that supports it, and suggests ways that radiation protection regulations might change if the hypothesis were to become accepted.

Dose-Response Relationship, Radiation↗
PubMed1965

RADIATION PROTECTION IN CANADA: VII. THE ROLE OF INDUSTRIAL HYGIENE IN THE FIELD OF RADIATION PROTECTION.

The main emphasis of a provincial radiation protection program is on ionizing radiation produced by machines, although assistance is given to the Federal Radiation Protection Division in its program relating to radioactive substances. The basis for the Saskatchewan program of radiation protection is the Radiological Health Act 1961. An important provision of the Act is annual registration of radiation equipment. The design of the registration form encourages a "do-it-yourself" radiation and electrical safety inspection.Installations are inspected every two years by a radiation health officer. Two hundred and twenty-one deficiencies were found during inspection of 224 items of radiation equipment, the commonest being failure to use personal film badges. Insufficient filtration of the beam, inadequate limitation of the beam, and unnecessary exposure of operators were other common faults.Physicians have a responsibility to weigh the potential advantages against the hazards when requesting radiographic or fluoroscopic procedures.

Canada↗
PubMedDate not supplied

[Formation of radiation and involution cataracts in man exposed to radiation].

An ophthalmologic follow-up of subjects exposed to chronic total external gamma-irradiation (747 subjects) and to gamma-neutron irradiation (1083 subjects) in total doses of 1 to 10 Gy has revealed no cases of radiation involvement of the eyes. Besides, a group of 8 patients with a history of acute radiation sickness were followed up, who were exposed to external gamma-neutron irradiation in total doses of 4 to 9.8 Gy. All these patients developed radiation burns of the skin of the face and eyelids, eyelashes and eyebrows epilation, 6 of these radiation cataracts and 2 mixed-type cataracts (radiation involutional ones). Radiation cataracts were developing within 10-32 months (the first stage). A forty-years' follow-up of the formation of radiation and involution cataracts permitted the authors single out the pathogenetic differences between these types and use these data for the solution of expert evaluation problems and problems related to social protection of people with acute radiation injuries of the eyes. The authors' results and the literature data evidence that, with due consideration for the irradiation dose and the patient's age, one can predict the type of a would-be cataract, periods of its formation and progress, and the treatment strategy.

Adult↗
PubMed1985

Radiation carcinogenesis in experimental animals and its implications for radiation protection.

Cancer induction is generally considered to be the most important somatic effect of low doses of ionizing radiation. It is therefore of great concern to assess the quantitative cancer risk of exposure to radiations of different quality and to obtain information on the dose-response relationships for carcinogenesis. Tissues in the human with a high sensitivity for cancer induction include the bone marrow, the lung, the thyroid and the breast in women. If the revised dosimetry estimates for the Japanese survivors of the atomic bomb explosions are correct, there is no useful data base left to derive r.b.e. values for human carcinogenesis. As a consequence, it will be necessary to rely on results obtained in biological systems, including experimental animals, for these estimates. With respect to radiation protection, the following aspects of experimental studies on radiation carcinogenesis are of relevance: Assessment of the nature of dose-response relationships. Determination of the relative biological effectiveness of radiations of different quality. Effects of fractionation or protraction of the dose on tumour development. For the analysis of tumour data in animals, specific approaches have to be applied which correct for competing risks. These methods include actuarial estimates, non-parametric models and analytical models. The dose-response curves for radiation-induced cancers in different tissues vary in shape. This is exemplified by studies on myeloid leukaemia in mice and mammary neoplasms in different rat strains. The results on radiation carcinogenesis in animal models clearly indicate that the highest r.b.e. values are observed for neutrons with energies between 0.5 and 1 MeV. On the basis of such results it might be concluded that the maximum quality factor of 10 for neutrons should be increased. Based on current evidence, an increase by a factor of 2 to 3 seems more realistic than a tenfold rise. The diversity of dose-response relationships point to different mechanisms involved in the induction of different tumours in various species and even in different strains of the same species.

Adenocarcinoma↗
PubMed2002

Radiation protection during percutaneous nephrolithotomy: a new urologic surgery radiation shield.

BACKGROUND AND PURPOSE: As endourology becomes an important part of the practice of urology, the use of fluoroscopic guidance has increased the exposure of urologists to the possibly deleterious effects of radiation. There is a need for a method of radiation protection for percutaneous nephrolithotomy (PCNL), as the exposure from radiation scatter may be significant, depending on the difficulty of establishing access. PATIENTS AND METHODS: We ascertained the effectiveness of a newly modified radiation shield during PCNL. Exposure readings were taken using a thermoluminescent dose monitor placed different distances from the radiation source during six PCNLs. We compared the exposure readings with and without the shield. RESULTS: The shield was able to reduce the radiation by an average of 96.1% at a distance of 25 cm and 71.2% at a distance of 50 cm from the source. CONCLUSION: The shield can be used as one step toward the goal of reducing surgeon radiation exposure. Other methods, such as dose-minimizing imaging protocols and adaptation of equipment optimized to reduce exposure, are also important measures in creating a safe environment for both the urologist and the patient.

Adult↗
PubMed2003

Non-targeted and delayed effects of exposure to ionizing radiation: II. Radiation-induced genomic instability and bystander effects in vivo, clastogenic factors and transgenerational effects.

The goal of this review is to summarize the evidence for non-targeted and delayed effects of exposure to ionizing radiation in vivo. Currently, human health risks associated with radiation exposures are based primarily on the assumption that the detrimental effects of radiation occur in irradiated cells. Over the years a number of non-targeted effects of radiation exposure in vivo have been described that challenge this concept. These include radiation-induced genomic instability, bystander effects, clastogenic factors produced in plasma from irradiated individuals that can cause chromosomal damage when cultured with nonirradiated cells, and transgenerational effects of parental irradiation that can manifest in the progeny. These effects pose new challenges to evaluating the risk(s) associated with radiation exposure and understanding radiation-induced carcinogenesis.

Animals↗
PubMedDate not supplied

[Small doses of ionizing radiation as radiation modifying factor].

To investigate the biological effects of small dose ionizing radiation has been acquiring greater importance. The awareness of how and in what direction it show its modifying effects in small doses is an essential scientific basis for developing standards, living conditions under specific environmental conditions. Cultured Hela cells and DEF 4/21 fibroblasts were used to evaluate the biological effects of small-dose ionizing radiation, by examining the conditions under which it showed its modifying effect in small doses (0.1 Gy) in particular. Preexposure to small-dose radiation was shown to alter cell responses to subsequent radiation in large doses. The modifying effects of small-dose radiation turned out to depend on the interval of exposure to small and large doses. Sensitization was recorded at an interval of 2-3 min; an adaptive response was achieved when the interval increased up to 3-5 hours. Upon exposure, intercellular contacts contribute to the modifying effects of small-dose radiation. There was neither effect of sensitization nor adaptive response if single cells were exposed to radiation.

Cell Line↗
PubMed2006

Radiation dose-response relationships for thyroid nodules and autoimmune thyroid diseases in Hiroshima and Nagasaki atomic bomb survivors 55-58 years after radiation exposure.

CONTEXT: Effects of irradiation on thyroid diseases such as thyroid nodules and autoimmune thyroid diseases have not been evaluated among people exposed to radiation more than 50 years in the past. OBJECTIVE: To evaluate the prevalence of thyroid diseases and their radiation-dose responses in atomic bomb survivors. DESIGN, SETTING, AND PARTICIPANTS: Survey study comprising 4091 cohort members (mean age, 70 [SD, 9] years; 1352 men and 2739 women) who participated in the thyroid study at the Radiation Effects Research Foundation. Thyroid examinations were conducted between March 2000 and February 2003. MAIN OUTCOME MEASURES: Prevalence of thyroid diseases, including thyroid nodules (malignant and benign) and autoimmune thyroid diseases, and the dose-response relationship of atomic bomb radiation in each thyroid disease. RESULTS: Thyroid diseases were identified in 1833 (44.8%) of the total participants (436 men [32.2% of men] and 1397 women [51.0% of women]) (P<.001). In 3185 participants, excluding persons exposed in utero, not in the city at the time of the atomic bombings, or with unknown radiation dose, the prevalence of all solid nodules, malignant tumors, benign nodules, and cysts was 14.6%, 2.2%, 4.9%, and 7.7%, respectively. The prevalence of positive thyroid antibodies, antithyroid antibody-positive hypothyroidism, and Graves disease was 28.2%, 3.2%, and 1.2%, respectively. A significant linear dose-response relationship was observed for the prevalence of all solid nodules, malignant tumors, benign nodules, and cysts (P<.001). We estimate that about 28% of all solid nodules, 37% of malignant tumors, 31% of benign nodules, and 25% of cysts are associated with radiation exposure at a mean and median thyroid radiation dose of 0.449 Sv and 0.087 Sv, respectively. No significant dose-response relationship was observed for positive antithyroid antibodies (P = .20), antithyroid antibody-positive hypothyroidism (P = .92), or Graves disease (P = .10). CONCLUSIONS: A significant linear radiation dose response for thyroid nodules, including malignant tumors and benign nodules, exists in atomic bomb survivors. However, there is no significant dose response for autoimmune thyroid diseases.

Aged↗
PubMed1994

Morphology and pathology of radiation-induced esophagitis. Double-blind study of naproxen vs placebo for prevention of radiation injury.

Radiation-induced esophagitis can cause substantial morbidity. Experiments in lab animals have shown that pretreatment with indomethacin protects the esophagus from radiation damage. We conducted a prospective, double-blind, randomized trial of naproxen vs placebo in patients undergoing thoracic radiation therapy for lung cancer. Twenty-eight patients were enrolled, of which 26 completed the study. Sixteen patients were given a short course of radiation (30 Gy/10 fractions/2 weeks), and 10 patients were given a longer course and a larger dose (40-50 Gy/25 fractions/5 weeks). Half of the irradiated patients were treated with naproxen, 375 mg, taken orally twice a day, and half were given an identical placebo. All patients were given ranitidine 300 mg, taken orally once a day. Study drugs were taken throughout the course of radiation. Endoscopy with esophageal biopsies and brushings was performed before and on the last day of treatment. Patients kept a daily diary for symptom scoring. Symptoms such as chest pain, dysphagia, odynophagia, and/or heartburn were reported in 15 patients from both subgroups, resulting in diet restriction to liquids only in eight patients and requiring temporary discontinuation of radiation therapy in one of them. Approximately half the patients in each subgroup developed esophagitis, usually mild and usually limited to the proximal esophagus. Severity of symptoms was not proportional to the severity of esophagitis. Candidiasis was documented in eight patients, but only four had symptoms that were severe in one. We conclude that acute radiation injury to the esophagus is observed in approximately half the patients receiving radiation therapy and can result in substantial morbidity.(ABSTRACT TRUNCATED AT 250 WORDS)

Double-Blind Method↗
PubMed2001

[Chronic radiation effects on dental hard tissue (radiation caries). Classification and therapeutic strategies].

OBJECTIVES: Since the first description of rapid destruction of dental hard tissues following head and neck radiotherapy 80 years ago, "radiation caries" is an established clinical finding. The internationally accepted clinical evaluation score RTOG/EORTC however is lacking a classification of this frequent radiogenic alteration. MATERIAL AND METHODS: Medical records, data and images of radiation effects on the teeth of more than 1,500 patients, who underwent periradiotherapeutic care, were analyzed. Macroscopic alterations regarding the grade of late lesions of tooth crowns were used for a classification into 4 grades according to the RTOG/EORTC guidelines. RESULTS: No early radiation effects were found by macroscopic inspection. In the first 90 days following radiotherapy 1/3 of the patients complained of reversible hypersensitivity, which may be related to a temporary hyperemia of the pulp. It was possible to classify radiation caries as a late radiation effect on a graded scale as known from RTOG/EORTC for other organ systems. This is a prerequisite for the integration of radiation caries into the international nomenclature of the RTOG/EORTC classification. CONCLUSIONS: The documentation of early radiation effects on dental hard tissues seems to be neglectable. On the other hand the documentation of Late radiation effects has a high clinical impact. The identification of an initial lesion at the high-risk areas of the neck and incisal part of the tooth can lead to a successful therapy as a major prerequisite for orofacial rehabilitation. An internationally standardized documentation is a basis for the evaluation of the side effects of radiooncotic therapy as well as the effectiveness of protective and supportive procedures.

Adult↗