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At least 649 records · Page 36Linked to original sources
PubMed1981

The influence of ultraviolet radiation on allergic contact dermatitis in the guinea-pig. II. Psoralen/UVA radiation.

Guinea-pigs were sensitized by percutaneous application of dinitrochlorobenzene and exposed to UVA (320-400 nm) radiation following systemic administration of methoxsalen. This treatment diminished the response to an elicitation dose of the hapten administered 14 days later within the site of irradiation. The site of elicitation of the allergic response had to be included in the field of exposure, an reduction of the allergic response was observed only when the exposure to radiation was commenced at the time of induction of contact allergy. Established contact skin sensitivity was not affected by radiation.

Animals↗
PubMed2002

Exposure of the operator to ionizing radiation during intracoronary radiation therapy.

This study examined the radiation exposure levels and safety of medical personnel during intracoronary radiotherapy procedures. The data of 34 stenosis patients from a total of 42 irradiated patients who participated in the Seoul National University Hospital Postangioplasty Rhenium (SPARE) trial were analyzed. Intracoronary radiotherapy was delivered to the patient immediately after angioplasty ballooning. The prescribed dose was 17 Gy to the media of the diseased artery and was delivered via a Re-188 filled balloon catheter. Dosimetry was carried out with a Geiger-Müller counter at eight different points. The selected maximum and whole-body exposed doses to the operator were 10 cm and 40 cm from the patient's heart. Median delivered activity was 111.6 MCi, with an average treatment time of 576 seconds. Average exposed dose rates at 10 cm and 40 cm from the patient's heart level were 47.2 mrem/hour and 29.6 mrem/hour, respectively, and average exposed doses per treatment were 7.0 mrem and 4.9 mrem, respectively. Exposure levels measured were much lower than the recommended limit of 50 mSv for radiation workers or 1 mSv for the general population, as recommended by the International Commission on Radiological Protection. This study proves that the method of intracoronary radiotherapy currently adopted and which is the basis of this trial is safe with respect to radiation protection.

Coronary Disease↗
PubMed2006

Intraoperative radiation therapy using mobile electron linear accelerators: report of AAPM Radiation Therapy Committee Task Group No. 72.

Intraoperative radiation therapy (IORT) has been customarily performed either in a shielded operating suite located in the operating room (OR) or in a shielded treatment room located within the Department of Radiation Oncology. In both cases, this cancer treatment modality uses stationary linear accelerators. With the development of new technology, mobile linear accelerators have recently become available for IORT. Mobility offers flexibility in treatment location and is leading to a renewed interest in IORT. These mobile accelerator units, which can be transported any day of use to almost any location within a hospital setting, are assembled in a nondedicated environment and used to deliver IORT. Numerous aspects of the design of these new units differ from that of conventional linear accelerators. The scope of this Task Group (TG-72) will focus on items that particularly apply to mobile IORT electron systems. More specifically, the charges to this Task Group are to (i) identify the key differences between stationary and mobile electron linear accelerators used for IORT, (ii) describe and recommend the implementation of an IORT program within the OR environment, (iii) present and discuss radiation protection issues and consequences of working within a nondedicated radiotherapy environment, (iv) describe and recommend the acceptance and machine commissioning of items that are specific to mobile electron linear accelerators, and (v) design and recommend an efficient quality assurance program for mobile systems.

Electrons↗
PubMed2000

Sarcoma after radiation therapy: retrospective multiinstitutional study of 80 histologically confirmed cases. Radiation Therapist and Pathologist Groups of the Fédération Nationale des Centres de Lutte Contre le Cancer.

PURPOSE: To evaluate the best strategy for treatment of sarcoma that occurs after radiation therapy. MATERIALS AND METHODS: Records were retrospectively reviewed for 80 patients with a confirmed histologic diagnosis of sarcoma that occurred after radiation therapy performed during 1975-1995. The patients were treated for breast cancer (n = 33, 42%), non-Hodgkin lymphoma (n = 9, 11%), cervical cancer (n = 9, 11%), benign lesions (n = 4, 5%), or other tumors (n = 25, 31%). Sarcoma occurred after a mean latency of 12 years (range, 3-64 years), with most (70%) developing in the soft tissue. Treatment included surgery (28 patients), surgery and chemotherapy (18 patients), chemotherapy only (15 patients), and radiation therapy (14 patients). RESULTS: By the end of the study, 51 patients were dead, including 46 due to sarcoma. Median survival was 23 months. Overall survival rates at 2 and 5 years, respectively, were 69% and 39% for patients treated with surgery, 10% and 0% for those treated with chemotherapy, and 52% and 35% for those treated with surgery and chemotherapy (P =.001). The 2- and 5-year rates for survival without recurrence were 54% and 32%, respectively. CONCLUSION: The results confirm the beneficial effect of surgery. Further study is needed to explore the roles of combined treatments.

Adolescent↗
PubMed2004

Effect of smoking on chromosomes compared with that of radiation in the residents of a high-background radiation area in China.

Cytogenetic investigation of stable-type aberrations (translocations) was carried out with our improved methods on 28 elderly individuals in a high-background radiation area (HBRA) in China, and on 24 elderly individuals in a control area (CA). The level of radiation in HBRA is 3 to 5 times higher than in CA. The mean frequencies of translocations per 1,000 cells in HBRA and CA were 12.4 +/- 5.3 and 10.0 +/- 3.8, respectively. No significant difference was found in the frequencies between HBRA and CA (P>0.05, Mann-Whitney U test). When elderly individuals in HBRA and CA were classified into four subgroups of HBRA nonsmokers, HBRA smokers, CA nonsmokers, and CA smokers, a significant difference was found in the frequencies between CA smokers and CA nonsmokers (P<0.05, Mann-Whitney U test). Furthermore a tendency of difference (a near T-value of 0.05 level) was found in a comparison of HBRA smokers vs. CA nonsmokers. The present results indicate that the elevated level of natural radiation in HBRA plays a less significant part than smoking in bringing about the induction rate of stable-type aberrations (translocations) in those areas.

Aged↗
PubMed2005

Assessment of the ultraviolet radiation field in ocean waters from space-based measurements and full radiative-transfer calculations.

Quantitative assessment of the UV effects on aquatic ecosystems requires an estimate of the in-water radiation field. Actual ocean UV reflectances are needed for improving the total ozone retrievals from the total ozone mapping spectrometer (TOMS) and the ozone monitoring instrument (OMI) flown on NASA's Aura satellite. The estimate of underwater UV radiation can be done on the basis of measurements from the TOMS/OMI and full models of radiative transfer (RT) in the atmosphere-ocean system. The Hydrolight code, modified for extension to the UV, is used for the generation of look-up tables for in-water irradiances. A look-up table for surface radiances generated with a full RT code is input for the Hydrolight simulations. A model of seawater inherent optical properties (IOPs) is an extension of the Case 1 water model to the UV. A new element of the IOP model is parameterization of particulate matter absorption based on recent in situ data. A chlorophyll product from ocean color sensors is input for the IOP model. Verification of the in-water computational scheme shows that the calculated diffuse attenuation coefficient Kd is in good agreement with the measured Kd.

Algorithms↗
PubMed2001

The shape of the dose-response curve for radiation-induced neoplastic transformation in vitro: evidence for an adaptive response against neoplastic transformation at low doses of low-LET radiation.

A dose-response curve for gamma-radiation-induced neoplastic transformation of HeLa x skin fibroblast human hybrid cells over the dose range 0.1 cGy to 1 Gy is presented. In the experimental protocol used, the spontaneous (background) frequency of neoplastic transformation of sham-irradiated cultures was compared to that of cultures which had been irradiated with (137)Cs gamma radiation and either plated immediately or held for 24 h at 37 degrees C prior to plating, for assay for neoplastic transformation. The pooled data from a minimum of three repeat large-scale experiments at each dose demonstrated a reduced transformation frequency for the irradiated compared to the sham-irradiated cells for doses of 0.1, 0.5, 1, 5 and 10 cGy for the delayed-plating arm. The probability of this happening by chance is given by 1/2(n), where n is the number of observations (5); i.e., 1/32 congruent with 0.031. This is indicative of an adaptive response against spontaneous neoplastic transformation at least up to a dose of 10 cGy of gamma radiation. The high-dose data obtained at 30 and 50 cGy and 1 Gy showed a good fit to a linear extrapolation through the sham-irradiated, zero-dose control. The delayed-plating data at 10 cGy and below showed a statistically significant divergence from this linear extrapolation.

Adaptation, Physiological↗
PubMed2001

Fulminant radiation-induced necrosis after stereotactic radiation therapy to the posterior fossa. Case report and review of the literature.

The problem of radiation-induced necrosis of normal brain surrounding the target area has been a major catalyst for the development of stereotactically focused radiation therapy. According to current opinion, the effects of stereotactic irradiation are confined to the region targeted. The authors present a case in which the administration of a conventional dose of stereotactically focused irradiation for treatment of a pilocytic astrocytoma produced fulminant necrosis that necessitated a combination of intensive surgical and medical management, after which the patient improved over the course of 1 year. Concomitant with his improvement, the initially remarkable findings on magnetic resonance imaging gradually resolved. In this presentation the authors emphasize the need to evaluate alternatives carefully before a decision is made to administer therapeutic irradiation. Furthermore, they explore the roles that target, host, and dosage factors play in hypersensitivity to radiation injury, the detection of these factors before treatment, and the administration of radioprotective agents. With the growing use of stereotactically focused irradiation as a primary treatment modality for a variety of neurosurgical conditions, it is important to be cognizant of its uncommon but potentially lethal side effects. A cooperative multicenter database in which the outcomes and morbidity following stereotactic irradiation are recorded is essential to the detection of relatively uncommon but severe complications such as those observed in this case.

Adult↗
PubMed2005

Clinical and dosimetric factors of radiation-induced esophageal injury: radiation-induced esophageal toxicity.

AIM: To analyze the clinical and dosimetric predictive factors for radiation-induced esophageal injury in patients with non-small-cell lung cancer (NSCLC) during three-dimensional conformal radiotherapy (3D-CRT). METHODS: We retrospectively analyzed 208 consecutive patients (146 men and 62 women) with NSCLC treated with 3D-CRT. The median age of the patients was 64 years (range 35-87 years). The clinical and treatment parameters including gender, age, performance status, sequential chemotherapy, concurrent chemotherapy, presence of carinal or subcarinal lymph nodes, pretreatment weight loss, mean dose to the entire esophagus, maximal point dose to the esophagus, and percentage of volume of esophagus receiving >55 Gy were studied. Clinical and dosimetric factors for radiation-induced acute and late grade 3-5 esophageal injury were analyzed according to Radiation Therapy Oncology Group (RTOG) criteria. RESULTS: Twenty-five (12%) of the two hundred and eight patients developed acute or late grade 3-5 esophageal injury. Among them, nine patients had both acute and late grade 3-5 esophageal injury, two died of late esophageal perforation. Concurrent chemotherapy and maximal point dose to the esophagus > or =60 Gy were significantly associated with the risk of grade 3-5 esophageal injury. Fifty-four (26%) of the two hundred and eight patients received concurrent chemotherapy. Among them, 25 (46%) developed grade 3-5 esophageal injury (P = 0.0001<0.01). However, no grade 3-5 esophageal injury occurred in patients who received a maximal point dose to the esophagus <60 Gy (P = 0.0001<0.01). CONCLUSION: Concurrent chemotherapy and the maximal esophageal point dose > or =60 Gy are significantly associated with the risk of grade 3-5 esophageal injury in patients with NSCLC treated with 3D-CRT.

Adult↗
PubMed1994

Excerpts from "Maintaining Radiation Protection Records". National Council on Radiation Protection and Measurements.

This is the last in a three-part series of articles reprinted from a report by the National Council on Radiation Protection and Measurements (NCRP). Section 5, "Workplace Records," is reprinted below. The Introduction and Section 2, "Guidance for Systemic Generation and Retention of Records Relating to Radiation Protection," were reprinted in the winter 1994 issue of Radiology Management, and Section 3, "Radiation Protection Program Records," appeared in the spring 1994 issue.

Forms and Records Control↗
PubMedDate not supplied

[Classification of radiation protective agents as a basis of modern radiation pharmacology].

The consistency of the classification of prophylactic antiradiation drugs have been given consideration as history of their discovery, theory of the radioprotection mechanisms and their use in applied medicine. To prophylactic antiradiation drugs can be related to the drugs of having capable of decreasing radiation injuries burden while administrated before or immediately after radiation. The ones consists of radioprotectors with short-term of long-term action, drugs stimulating radioresistance, the ones suppressing symptoms of primary radiation reaction, the ones of early detoxication, the ones for absorbtion and elimination of radionuclides from an organism.

Animals↗
PubMedDate not supplied

[Morphological types of radiation-induced hematopoietic tissue cell death, its biological essence and significance at various stages of developing acute radiation injury].

The results of morphologic investigation of radiation-induced cell death types in human and animal (dogs) hematopoietic tissue within an acute radiation injury are presented. It has been shown that early and late necrobiosis of myelokaryocytes occurs via apoptosis. An attempt to designate the pathogenic role of apoptosis in hematologic syndrome of acute radiation sickness was performed.

Animals↗
PubMed2002

[CT and MRI aspects of 28 patients with cerebral radiation necrosis irradiated for ORL tumors: correlation with the radiation technique].

PURPOSE: To describe and correlate with radiation therapy the occurrence of cerebral radiation necrosis in patients irradiated for nasopharyngeal or ethmoidal tumor. Materials and Methods. From 1986 to 1998, 1 201 patients, 981 with nasopharyngeal tumors, and 220 with ethmoidal tumors were treated by radiotherapy. Twenty eight developed cerebral necrosis. MRI were performed in all patients and CT in 18 patients. Diagnosis was considered at imaging, and confirmed by follow-up. RESULTS: The incidence of cerebral radionecrosis was 2.33%. The time interval between treatment and necrosis ranged from 2 months to 9 years. CT showed edema and/or focal enhancement in all cases except for 4 patients with normal CT examinations. MRI showed edema and/or abnormal focal punctate or gyriform enhancement in all patients. Lesions were localized in the temporal lobe (n=18), frontal lobe (n=9), pons (n=3) and optic nerve (n=2). The doses related to the areas of necrosis ranged from 13 to 135Gy. In 2 cases necrosis was situated at the boundaries of the radiation field. Imaging follow-up showed complete (n=3) or incomplete remission (n=1), lesion progression (n=11), cerebral atrophy (n=5) and stability (n=7). CONCLUSION: MRI is useful to diagnose cerebral necrosis. New technologies may reduce the incidence of this complication.

Adult↗
PubMedDate not supplied

Radiation sensitivity and the status of some radiation sensitivity markers in relatively sensitive lymphoid cells.

The most commonly used indicators of ionizing radiation exposure are cytogenetic measures and survival parameters. All these methods have their advantages, disadvantages and uncertainties, such that better biological estimators of the absorbed dose, especially in the low dose range, are being sought. In this study we analyzed apoptosis and several proteins involved in the regulation of apoptosis as possible indicators of irradiation after relatively small doses (0.1-2 Gy) of X-rays. The studies were carried out in seven lymphoid cell lines: two mouse lymphoma L5178Y, the human pre-B cell leukemia Reh, and four human Epstein-Barr virus-transformed lymphoid cell lines (two apparently normal and two Ataxia-telangiectasia (AT)). We detected apoptosis with the in situ terminal deoxynucleotidyl transferase assay and flow cytometry, and measured the expression of several apoptotic-regulatory proteins (Bcl-2, Bax, Bclx, NF kappa B) with Western blotting. The cytokinesis-block micronucleus assay, comet assay as a measure of DNA damage, and trypan blue survival test were also done for comparison Although for the most of examined parameters of radiation sensitivity: i.e. micronucleus assay, trypan blue test and percentage of apoptosis--there were observed clear dose-effect relationships for all cell lines examined, we did not find agreement between values for these measured parameters. There are marked differences in both timing of apoptosis and percentage of apoptotic cells. Variation in the apoptotic fraction in the controls for different sets of experiments is not very pronounced. There is however considerable variation for the same parameters in irradiated cells, possibly due to their cell cycle status during irradiation, as the cultures were not synchronized. Overall, neither the numbers of apoptotic cells nor the expression of apoptosis-related proteins, nor DNA repair can serve as dose estimators or sensors for these lines, but still these parameters can give valuable supplementary information about radiation sensitivity.

Animals↗
PubMed1992

[A survey of annual radiation dose for radiation workers from occupational and medical exposures in Kyushu].

This study was carried out to determine annual dose equivalents of exposure in workers exposed to medical radiation and occupational radiation in an enterprise associated with nuclear power plants. The results indicated that medical exposure is much higher than occupational exposure. Average annual effective dose equivalents for medical and occupational exposure were 4.0-7.5 mSv and 2.4-3.6 mSv, respectively. Individual occupational exposure limits have been well controlled and maintained at one-fifth of the dose limit for radiation workers (50 mSv/yr). On the other hand, medical exposure in the older workers of this enterprise has been increasing as a result of X-ray diagnosis with barium meal.

Adult↗
PubMedDate not supplied

[Several indices of the peripheral immune system in clean up team workers and patients who survived acute radiation disease 5 years after effects of the radiation accident factors].

A group of liquidators and patients survived acute radiation sickness (ARS) was studied five years after the effect of radiation factors resulted from the Chernobyl A.P.S. disaster. Studied were the number of T-lymphocytes (SD2+, SD3+, SD5+), subpopulations SD16+ and SD25+, the content of SD16+ and SD25+ lymphocytes and B-cells, as well as the levels of serum IgM, A, G; determined was the concentration of serum alpha 1-thymosin. A decrease was noted in the number of T-cells of the examined patients, with respect to all markers studied: the number of SD4+ cells was found decreased in patients with ARS sequelae and normal in liquidators. The decrease in serum alpha 1-thymosin was a function of dose. Dynamics of changes in the T-cells of the examinees may reflect the new trends in the radiation response of T-lymphocytes which were not directly related to initial damages to the latter. The injury to the stroma of the thymus and especially to its epithelial cells may be the basis for later postirradiation damages to the immune system. The decrease in the concentration of alpha 1-thymosin in the blood serum of the examinee is the manifestation of the thymus hypofunction. In liquidators and patients with the ARS sequelae the number of SD25+ cells increased markedly indicating the existence of the source of endogenous cell activation. The content of B-lymphocytes in all studied groups of patients was reduced which may serve as a criterion of chronic stress.

Accidents↗
PubMed2004

[Primary prevention in workers exposed to ultraviolet radiation and radiation-related risks].

This paper presents current views on the principles of primary prevention of ultraviolet radiation. Preventive interventions aimed at limiting exposure to solar light as well as cosmetics with adequate filters are one of the elements of work safety that should be ensured by employers. New generation of cosmetics contain several substances, including absorbing and chemical filters, and thus ensure effective protection against ultraviolet solar radiation with relatively low risk of adverse body effects. Application of several filters (physical and chemical) in one cosmetic provides an adequate skin protection. The issue to be thoroughly analyzed is the minimum amount of the used cosmetic to ensure effective protection against ultraviolet radiation.

Humans↗
PubMed1990

Radiation-blocking shields to localize periarticular radiation precisely for prevention of heterotopic bone formation around uncemented total hip arthroplasties.

Sixteen patients (18 hips) were treated with localized radiation therapy limited to periarticular regions surrounding the femoral neck by shielding the prosthesis and the adjacent regions to prevent heterotopic bone formation around the uncemented prosthesis. All hips received 1500 rads. Eight of these hips were irradiated after excising severe heterotopic bone, five because they developed extensive heterotopic ossification in the opposite hip, and five others because they were considered to be at high risk for developing heterotopic ossification. Only two of the 18 hips developed a small amount of heterotopic bone after localized periarticular radiation. All wounds healed primarily. No progressive radiolucencies developed at the bone-prosthesis interface. There was only one trochanteric nonunion of six trochanteric osteotomies. Localized periarticular radiation therapy with precision shielding of the prosthetic components and adjacent skeletal structures is an effective means to prevent heterotopic bone formation around cementless total hip arthroplasties. It also has the advantage of not adversely affecting the healing of the trochanteric osteotomy.

Adult↗