Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “RADIATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources
PubMed1994

[International guidelines on the diagnostic applications of magnetic resonance. International Non-Ionizing Radiation Committee of the International Radiation Protection Association].

Magnetic resonance imaging has become an established diagnostic modality. The clinical usefulness of in vivo magnetic resonance spectroscopy was demonstrated in several instances and is being explored further. These techniques involve exposure of the patient to static and time-varying magnetic fields and radiofrequency electromagnetic fields. In particular exposure situations, these fields may pose a health hazard. The purpose of this paper is to provide information on the guidelines issued by the International Non-Ionizing Radiation Committee of the International Radiation Protection Association on levels of exposure and health effects from magnetic and radiofrequency electromagnetic fields associated with magnetic resonance diagnostic devices, and on precautions to be taken to minimize health hazards to patients undergoing magnetic resonance examinations.

Biophysical Phenomena↗
PubMed1996

Radiation hepatology of the rat: association of the production of prostacyclin with radiation-induced hepatic fibrosis.

The hypothesis that hepatic fibrosis is preceded by inflammation and formation of prostanoids from arachidonic acid liberated from damaged cell membranes was investigated. Liver slices were prepared using a Krumdieck precision tissue slicer from sham-irradiated rats or from rats whose livers had been irradiated with 25 Gy 137Cs gamma rays in which injury was allowed to develop in vivo for 6 to 55 days. Unused portions of the liver were analyzed for hydroxyproline content to determine hepatic fibrosis. A unique organ culture system was used to incubate liver slices for 2 h. Secretion into the incubation medium of aspartate aminotransferase and 6-keto prostaglandin F1 alpha were measured to quantify damage to the hepatocyte membrane and production of prostacyclin, respectively. A threefold increase in the concentration of 6-keto prostaglandin F1 alpha in the medium was evident by 13 days after irradiation. This elevated concentration of 6-keto prostaglandin F1 alpha persisted for the remainder of the study and preceded fibrosis, as measured by liver hydroxyproline concentration, and hepatocyte membrane damage, as measured by release of aspartate aminotransferase into the incubation medium or plasma. We therefore suggest that, in the non-generating liver, damage and breakdown of nonparenchymal liver cell membrane is the principal source of 6-keto prostaglandin F1 alpha. These results are also compatible with the supposition that inflammation and release of arachidonic acid metabolites are one of the early biochemical events leading to hepatic fibrosis. How the release of arachidonic acid metabolites might initiate and sustain radiation-induced fibrosis is discussed. An explanation for the difference in liver fibrosis induced by chemicals and radiation is also presented.

6-Ketoprostaglandin F1 alpha↗
PubMedDate not supplied

[Quantitative characteristics of radiation sickness clinical manifestations in large-sized laboratory animals exposed to extra-lethal radiation doses. The endocrine system reactions in dogs and monkeys].

The dynamics of cortisol, insulin and triiodothyronine content of the blood has been studied in dogs and two monkey species exposed to electron and gamma-neutron radiations in a wide supralethal--dose range. A calculated value--index of the endocrine status--has been used for integral estimation the function of the endocrine system. A considerable disintegration of the functions of separate endocrine glands has been observed, which correlates with degree of clinical manifestations in animals and radiation dose.

Animals↗
PubMed1965

RADIATION PROTECTION IN CANADA. VI. PROBLEMS IN THE ASSESSMENT OF GENETIC DAMAGE FROM EXPOSURE OF INDIVIDUALS AND POPULATIONS TO RADIATION.

Estimates of the genetic damage from radiation exposures of human populations are needed in order to set reasonable limits for future exposures. In addition to the three rads per generation received by the gonads from natural sources, a similar amount is currently contributed by medical radiology and a further five rads per generation has been suggested as an upper limit for exposures from the future peaceful uses of atomic energy. Two methods of estimating the genetic damage from such an increase suggest that there might be in the vicinity of 250 to 800 severely affected individuals per year in a population of 20 million people, or within an order of magnitude of the current highway fatality rate for Canada of about 4000 per year. Although the true value may be less, or greater, by as much as tenfold, the effect is in any case large enough to justify continued scrutiny.

Canada↗
PubMed1992

Interruptions adversely affect local control and survival with hyperfractionated radiation therapy of carcinomas of the upper respiratory and digestive tracts. New evidence for accelerated proliferation from Radiation Therapy Oncology Group Protocol 8313.

Hyperfractionated radiation therapy (HFX) attempts to overcome tumor proliferation during treatment by permitting higher total doses in the same overall time as standard fractionation. Whereas interruptions, including splits, reduce local control with standard fractionation in carcinoma of the upper respiratory and digestive tracts, HFX might compensate for interruptions. Patients were randomized to receive total doses of 6720, 7200, 7680, and 8160 cGy, using 120 cGy twice daily, 5 days per week. Those analyzed received +/- 4% of assigned total dose and lived 90 days or more. Treatment was completed within 5 days of the time specified for each treatment arm in 233 patients; 48, 80, and 131 patients had delays 14, 10, and 5 days or more, respectively. Locoregional control and survival were significantly (P less than or equal to 0.03) reduced with delays of 5 days or more when corrected for prognostic factors. Late effects of radiation therapy were not affected by interruptions. These data support the hypothesis that proliferation (possibly accelerated) of tumor clonogens during treatment influences the outcome.

Aged↗
PubMed1997

Severe radiation-induced liver disease following localized radiation therapy for biliopancreatic carcinoma: activation of hepatic stellate cells as an early event.

Radiation-induced liver disease is recorded as a form of veno-occlusive disease. Its pathogenesis remains unclear even if the initial injury likely occurs in the endothelial cells of central veins. The aim of our study was to investigate liver morphological features in relation to alpha-isoform of smooth muscle actin expression in hepatic stellate cells in six patients treated by localized radiotherapy on the biliopancreatic area. Within the month after completion of treatment, an activation of hepatic stellate cells strictly confined to irradiated areas and coinciding with congestive changes was observed. At a later stage, collagen deposition gradually increased, replacing the congestive and destroyed areas. This new fibrotic tissue also contained numerous alpha-smooth muscle positive cells. Our data suggest that early hepatic stellate cells activation coinciding with congestive changes plays an important role in radiation liver injury and ensuing fibrosis.

Actins↗
PubMed1981

Osteoclastome-like giant cell thyroid carcinoma controlled by intensive radiation and adriamycin, in a patient with meningioma and multiple myeloma treated by radiation and cytoxan.

The eighth cases of osteoclastome-like giant cell carcinoma of the thyroid, and the first one to be treated with adriamycin in addition to surgery and radiation, is reported. This rare variant of anaplastic thyroid carcinoma appeared in a patient operated on for meningioma and treated for multiple myeloma with cranial radiation and chronic administration of cytoxan.

Carcinoma↗
PubMed1985

Radiation pneumonitis: a complication resulting from combined radiation and chemotherapy for early breast cancer.

Described is a patient with early breast carcinoma who developed clinical radiation pneumonitis during primary radiation therapy and concomitant chemotherapy that included prednisone. This syndrome developed three days following abrupt steroid withdrawal. Retrieval of steroids brought complete resolution of the clinical and radiological findings. Although this syndrome is rare, it is recommended that steroid therapy in a patient previously irradiated to the chest be avoided.

Breast Neoplasms↗
PubMed1987

Intraoperative interstitial hyperthermia in conjunction with intraoperative radiation therapy in a radiation-resistant carcinoma of the abdomen: report on the feasibility of a new technique.

The application of a new technique of intraoperative interstitial hyperthermia (IOHT) and intraoperative radiation therapy (IORT) was investigated for unresectable abdominal carcinoma. A 43-year-old white male presented with severe back pain due to metastatic adenocarcinoma in the left paravertebral area, producing erosion of the body of T12. The disease had not responded to external beam radiation therapy. The tumor was approached through a thoraco-abdominal incision and IOHT was delivered via interstitial electrodes. Temperature was monitored at 16 locations within the tumor. An LCF hyperthermia unit was utilized to deliver RF power and produced a treatment temperature of 43 degrees C for 60 minutes uniformly throughout the treatment volume. Immediately following hyperthermia treatment, the lesion was treated with 15 meV electrons via IORT to a tumor dose of 25Gy. The patient recovered without complication and had complete relief from pain. Posttreatment CT scans have demonstrated control of disease over a 5-month follow-up period. A clinical pilot study has been established to further investigate the application of this combination therapy.

Adenocarcinoma↗
PubMed1990

Rat liver tolerance for partial resection and intraoperative radiation therapy: regeneration is radiation dose dependent.

We studied the feasibility of delivering a large single dose of intraoperative radiation as an adjuvant to partial hepatic resection. Intraoperative radiation therapy (IORT) was delivered to the remaining liver of 84 rats after partial hepatectomy to determine the acute and chronic effects of treatment on blood chemistry values, histology, survival, hepatic regeneration, and cellular appearance of the normal liver. Transient elevations in SGOT, SGPT, and alkaline phosphatase were attributed both to hepatectomy and to liver parenchymal damage induced by IORT. Microscopic examination upon necropsy, performed at frequent intervals post-treatment revealed hepatic capsular thickening with some alteration of liver architecture mainly underneath the capsule, with localized inflammation and some areas of necrosis. Survival in all groups was 100% at 45 days. Liver weight increase proved to be dose-dependent and displayed a bisphasic pattern. This study demonstrated that IORT is a feasible adjunct to surgical resection of the liver in the rat model.

Alanine Transaminase↗
PubMed1978

Effects of ionizing radiations on human costal cartilage and exploration of the procedures to protect the tissue from radiation damage.

The chemical changes produced following 60Co-gamma-irradiation of human costal cartilage have been monitored using "critical electrolyte concentration" (CEC) measurements utilizing Alcian Blue--magnesium chloride and Toluidine Blue--sodium chloride systems. The decrease in the CEC with radiation can be related to the decrease in hexose and hexosamine contents of the cartilage. Such changes arise as a result of degradation of the glycosaminoglycan component of the tissue. The state of the collagen fibres after irradiation has been examined using the Van Giesson stain and by biochemical assay of the hydroxyproline moeity. Energy transfer methods have been utilized to protect the glycosaminoglycan component of the cartilage from radiation damage.

Aged↗
PubMed2000

Radiation risks in perspective: radiation-induced cancer among cancer risks.

The majority of the public in industrial countries believes that pollution and low doses of radiation are threats to good health. As a matter of fact, when these putative risks are compared to those originating from lifestyle, they appear very small. In particular, the risks associated with low doses of irradiation, even when they are assessed with the most pessimistic models, appear extremely small. Public anxiety is fuelled by the uncertainty regarding the magnitude of this risk and the use of the linear no threshold (LNT) hypothesis, which gives credence to the concept that even the smallest doses are harmful. There are a number of scientific and epidemiological data currently under debate that are not consistent with the LNT hypothesis. For example, no difference in the incidence of cancers or of birth defects has been observed between regions with low or high natural irradiation. This inconsistency between perceptions and data underlines the role of psychological factors studied since 1957 which should be placed in the perspective of the public's present attitude toward risk and technology. Social amplification or attenuation of risk may occur in several ways. Fearful concern about radiation began in 1955, with the beginning of the Cold War, when the possibility of a nuclear holocaust appeared very real. Analysis of the data shows that these fears of technology could have a detrimental effect; they should therefore be investigated and understood.

Cause of Death↗
PubMed2004

Effect of ionizing radiation on gene expression in CD4+ T lymphocytes and in Jurkat cells: unraveling novel pathways in radiation response.

To better understand at the molecular level the effect of ionizing radiation in leukocytes, the global transcriptional response to X-ray irradiation was studied in human CD4+ T lymphocytes and in Jurkat cells. Microarray analysis performed on freshly isolated human CD4+ lymphocytes 8 h after an LD50 irradiation dose of 1 Gy revealed that out of 13,825 genes, 1084 were modulated more than 1.5-fold. The most strongly up-regulated genes were predominantly p53 targets. In contrast, exposure of the CD4+ T lymphocyte-derived Jurkat leukemic cell line (with no functional p53 gene) to an equivalent LD50 dose (0.5 Gy) induced a partly different and more limited set of genes. Interestingly, this set of genes belonged to the Rho and cytokine signaling pathways regulated by low-dose ionizing radiation.

Apoptosis↗
PubMed1998

Comparison of survival outcomes in patients with intracranial germinomas treated with radiation alone versus reduced-dose radiation and chemotherapy.

Concern about long-term sequelae of irradiation has led to the use of adjuvant chemotherapy with lower dose irradiation in the treatment of intracranial germinomas. To assess the feasibility of this approach versus radiation only, the survival of 16 evaluable patients (13 boys, 3 girls) with biopsy-proven intracranial germinomas treated at the Hospital for Sick Children was assessed. Between 1977 and 1988, 8 patients were treated with radiation only: 7 received tumour doses between 4000 and 5100 cGy and spinal prophylaxis; 1 received 3060 cGy to the tumour with no prophylaxis. After a median follow-up of 84 months, 7 are in continuous first CR and 1 is in second CR. Between 1988 and 1996, 8 patients received adjuvant platinum- and etoposide-based chemotherapy for two or three cycles followed by local irradiation to the tumour (2500-3500 cGy). After a median follow-up of 40 months, 6 are in continuous first CR and 1 in second CR; 1 has died of progression. Survival outcomes in the two groups are similar. Prospective trials to assess event-free survivals, neurocognitive and neuroendocrine outcomes are needed before definitive treatment recommendations can be made.

Adolescent↗
PubMed1998

Radiation-induced brain tumours: potential late complications of radiation therapy for brain tumours.

The development of neoplasms subsequent to therapeutic cranial irradiation is a rare but serious and potentially fatal complication. In this study, we retrospectively reviewed the clinical and pathological aspects of 11 patients who underwent cranial irradiation (range, 24-110 cGy) to treat their primary disease and thereafter developed secondary tumours within a span of 13 years. All tumours arose within the previous radiation fields, and satisfied the widely used criteria for the definition of radiation-induced neoplasms. There was no sex predominance (M: 5, F: 6) and the patients tended to be young at irradiation (1.3-42 years; median age: 22 years). The median latency period before the detection of the secondary tumour was 14.5 years (range: 6.5-24 years). Meningiomas developed in 5 patients, sarcomas in 4, and malignant gliomas in 2. A pre-operative diagnosis of a secondary tumour was correctly obtained in 10 patients based on the neuro-imaging as well as nuclear medicine findings. All patients underwent a surgical removal of the secondary tumour, 3 underwent additional chemotherapy, and one received stereotactic secondary irradiation therapy. During a median of 2 years of follow-up review after the diagnosis of a secondary tumour, 3 patients died related to the secondary tumours (2 sarcomas, 1 glioblastoma), one died of a recurrent primary glioma, while the remaining 7 have been alive for from 10 months to 12 years after being treated for the secondary tumours (median: 3 years). Based on these data, the clinicopathological characteristics and possible role of treatment for secondary tumours are briefly discussed.

Adolescent↗
PubMed1990

Endometrial carcinoma: a comparative analysis of the therapeutic results and causes of failure after treatment by radiation combined with surgery or radiation therapy alone.

At the present time endometrial carcinoma is considered to be among the most frequent of gynecological tumors and its incidence is now reaching that of cervix carcinoma. In this paper, we present the results of two series of treatment for endometrial carcinoma, one using the combination of surgery and radiation, the second one using radiation treatment alone. Indeed, due to our recruitment criteria between 1968 and 1978 at the Montpellier Cancer Institute, the proportion of patients treated exclusively by physical agents was more or less equal to those receiving combined treatment. In many cases, either because of the poor condition of the patient, or due to local involvement, irradiation alone was used. The report of the results explain the therapeutic failures and show by means of two sequential series how techniques have been developed. Previously treated patients were excluded (44 cases).

Adenocarcinoma↗
PubMed1996

A simple and generally applicable method to estimate the peripheral dose in radiation teletherapy with high energy x-rays or gamma radiation.

PURPOSE: Many articles have been published on the measurement of the dose to points outside the primary beam, often called the peripheral dose (PD), for instance, to the gonads, for specific treatment machines and/or techniques. We investigated the possibilities for developing a generalized method based on the data from several publications. METHODS AND MATERIALS: The data from several publications were recalculated for a reference situation, then averaged, and the frequency distributions around the mean were determined. Published data were available for 60Co, 4, 6, 8, and 10 MV, and 18 to 25 MV for a large variety of treatment machines. Furthermore, an analysis of possible corrections for depth dependence, field elongation, irregularly shaped fields, wedges, and shielding blocks was carried out. RESULTS: The frequency distributions of all published PD values for square fields for photon energies of 4 MV to 25 MV showed a standard deviation of 33%. The PD values of 60Co are significantly different with a standard deviation of 25%. A difference in the leakage radiation between cobalt machines and linear accelerators can possibly explain this difference, especially for large distances, where leakage radiation predominates. Taking the uncertainty of the risk factors into consideration, we conclude that the use of average values is justified. Although statistically not significant, the peripheral dose appears to be dependent on photon energy with a minimum around 6 MV. CONCLUSIONS: It is possible to estimate the peripheral dose for photon energies of 4 MV to 25 MV with an accuracy of +/- 33%; for 60Co, the accuracy is even better. The variation of the PD between different treatment machines is so small that it is justified to use average PD values, irrespective of the treatment machine.

Cobalt Radioisotopes↗
PubMed1994

Evaluating intraoperative radiation therapy (IORT) and external beam radiation therapy (EBRT) in non-small cell lung cancer (NSCLC). Five years experience.

A pilot study on intraoperative radiation therapy (IORT) combined with external beam radiation therapy (EBRT) in nonresectable non-small cell lung cancer (NSCLC) was performed in 31 patients (mean age: 66.2 years, range: 51-80; 10 anatomically and functionally, 21 functionally, nonresectable; 20 squamous-cell, 11 adenocarcinoma). The tumor was exposed by lateral thoracotomy and a staging lymph node dissection was performed (final staging 7 T1, 16 T2, 8 T3; 11 nodal positive). Ten to 20 Gy IORT (energy: 7-20 MeV electrons) were delivered to the tumor. Unilateral continuous positive airway pressure ventilation of the diseased lung was used to reduce the amount of healthy lung tissue in the IORT port and to minimize the ventilatory movement. Secondary collimation and direct shielding of radio-sensitive structures within the IORT port by aluminium sheets were used to further reduce collateral damage. Four weeks after IORT, 46 Gy EBRT (2 Gy/day 5 times a week; 8-23 MeV photons) were administered to the mediastinum and to the tumor-bearing area on an outpatient basis. In nodal positive cases the mediastinal dose was increased to 56 Gy. Twenty-three patients were evaluable. In 13 complete, in 8 partial (50-97% regression) and in 2 minor response has been achieved. Five patients experienced a recurrence (local only: 2; local and distant: 1; distant only: 2). Twelve patients died of underlying cardio-respiratory disorders within 6 to 25 months after IORT; 7 died of cancer. The overall 5-year survival rate including the incidental deaths is 14.7%. The recurrence-free survival rate is 53.2%.

Adenocarcinoma↗