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At least 991 records · Page 55Linked to original sources
PubMed2005

Lauriston S. Taylor Lecture: Radiation protection in the aftermath of a terrorist attack involving exposure to ionizing radiation.

I would like to start this Twenty-Eighth Lauriston S. Taylor Lecture by expressing my gratitude to the National Council on Radiation Protection and Measurements (NCRP) for this unique occasion. I feel particularly honored for this opportunity to address a highly specialized and qualified audience of professionals who are specifically interested in what appears to be a forthcoming worldwide challenge, namely radiological terrorism and managing its potential radiological consequences.

Benchmarking↗
PubMed2002

Radiation-induced changes in MR signal intensity and contrast enhancement of lumbosacral vertebrae: do changes occur only inside the radiation therapy field?

PURPOSE: To evaluate temporal changes in signal intensity (SI) and degree of contrast enhancement (CE) of bone marrow in lumbosacral vertebrae inside and outside the radiation therapy (RT) field. MATERIALS AND METHODS: Twenty-three patients with advanced uterine cervical cancer who were treated with RT were prospectively evaluated. Each patient underwent four dynamic magnetic resonance (MR) studies: before RT, 2 and 4 weeks after initiation of RT, and 4 weeks after completion of RT. SI and CE were calculated in all four studies of each patient. RESULTS: Bone marrow inside the RT field showed steady and marked increase in precontrast SI and early and transient increase in CE at 2 weeks after initiation of RT followed by progressive and marked decrease in CE at 4 weeks after initiation of RT and 4 weeks after completion of RT. Bone marrow outside the RT field showed slight increase in precontrast SI and steady and moderate decrease in CE to a lesser degree without early increase as seen in bone marrow inside the RT field. CONCLUSION: RT causes an increase in precontrast SI predominantly in bone marrow inside the RT field. However, a decrease in CE is seen in bone marrow not only inside but also outside the RT field.

Adult↗
PubMed2006

Phase III randomized trial of very accelerated radiation therapy compared with conventional radiation therapy in squamous cell head and neck cancer: a GORTEC trial.

PURPOSE: With the aim to increase the dose intensity of radiation therapy (RT), and subsequently the locoregional control rate, a very accelerated RT regimen was compared with conventional RT in a series of patients with head and neck squamous cell carcinoma (HNSCC). PATIENTS AND METHODS: Between 1994 and 1998, 268 patients with T3 or T4, N0 to N3 HNSCC (staged by 1997 International Union Against Cancer criteria) that was not eligible for surgery were randomly assigned to receive either conventional RT, delivering 70 Gy in 7 weeks to the primary tumor and 35 fractions of 2 Gy over 49 days, or to receive very accelerated RT, delivering 62 to 64 Gy in 31 to 32 fractions of 2 Gy over 22 to 23 days (2 Gy/fraction bid). RESULTS: The most common tumor site was the oropharynx and most of the patients (70%) had T4 and N1 to N3 tumors in 72% of patients. The main patient and tumor characteristics were well-balanced between the two arms. The median total doses were 63 Gy (accelerated) and 70 Gy (conventional), with a median overall time of 22 days and 48 days, respectively. Acute mucositis was markedly increased in the accelerated-RT arm (P < .001). The locoregional control rate was improved by 24% at 6 years with accelerated RT. In contrast, disease-free survival and overall survival were not significantly different between the two arms. There was no difference in late effects between the two arms. CONCLUSION: The very accelerated RT regimen was feasible and provided a major benefit in locoregional control but had a modest effect on survival.

Carcinoma, Squamous Cell↗
PubMed1990

[Studies on chemical protectors against radiation. XXXII. Protective effects of methanol extracts of various Taiwan crude drugs on radiation injuries].

This study is to investigate radioprotective effects of 23 Taiwan crude drugs on X-ray induced bone marrow death and skin injury in mice. Each methanol extract of these Taiwan crude drugs was injected intraperitoneally into ICR male mice at 6 weeks of age before irradiation. Mice were whole-body irradiated with a soft X-ray generator. Radiation factors of the two screening tests used were as follows: 70 kVp, 10 mA, 10 mm acrylate filter, 70R/min, 2100R for survival test, and 30 kVp, 10 mA, 190R/min, 1100R for protective test on skin injury. As a result of these studies, the survival effect was recognized in Solani Incani Herba and Orthosiphi Aristati Herba. On the other hand, Mimosae Herba, Canarii Radix, Bombacis Radix, Arecae Fructus, Hedyotidis Diffusae Herba and Cynomorii Caulis were shown to have significant protective potency on skin injury.

Animals↗
PubMed1990

[Studies on chemical protectors against radiation. XXVIII. Protective effect of nucleic acid constitutional compounds on radiation damages induced by X-irradiation].

The effects of various nucleic acid constitutional compounds, base, nucleoside and nucleotide on lethality and skin injury induced by soft X-irradiation were studied. The survival effect was determined by use of survival days after irradiation of lethal dose of 70 kVp, 2100R and the protective effect on skin injury was determined by use of degrees on skin injury after 30 kVp, 1100R soft X-irradiation. As a result of these studies, the survival effect was observed by single injection of inosine at 120, 60 and 5 min before irradiation and three times injection after irradiation. And the other nucleic acid constitutional compounds had no effect on survival. Protective effect of skin injury was observed by single injection of adenosine, guanosine, inosine, 5'-adenosine monophosphate (5'-AMP), 5'-guanosine monophosphate (5'-GMP) and 5'-inosine monophosphate (5'-IMP) before irradiation. Protective effect of skin injury by three time injection before irradiation were revealed in adenosine, inosine, 5'-AMP and 5'-IMP. For the investigation of superoxide anions and hydroxyl radicals scavenge activities, the relationship between radical scavenge activities and protective effect of radiation by using various nucleosides was not observed.

Adenosine↗
PubMed1991

[Studies on chemical protectors against radiation. XXXIV. Survival effects of aqueous extracts of various Chinese traditional medicines on radiation injury].

In order to develop a nontoxic radioprotector, 60 kinds of Chinese traditional medicines were chosen, and their aqueous extracts tested for their survival effects against the lethal effect of X-irradiation in mice. Radiation factors used were as follows: soft X-rays, 2100R (5.418 x 10(-1) Ckg-1), 70 kVp, 10 mA, 10 mm acrylic filter, 70R (1.806 x 10(-2) Ckg-1)/min. Among 60 medicines tested by intraperitoneal injection immediately before the irradiation, 15 are shown to have the significant survival effect. These 15 effective medicines were also tested by intraperitoneal injection after the irradiation, and the survival effect was recognized in Keisi-syakuyaku-chimo-to, Keigai-rengyo-to, Simotu-to, Syakuyaku-kanzo-to and Hange-syasin-to. On the other hand, the survival effects of 25 medicines including the above-mentioned 15 medicines were investigated by the oral administration at various times before or after the irradiation. As the result of these studies, only Keigai-rengyo-to and Bukuryo-in are shown to have the significant survival effect when administered 2 h before the irradiation.

Administration, Oral↗
PubMed2006

Radiation-induced osteosarcoma 16 years after surgery and radiation for glioma--case report.

A 35-year-old man developed osteosarcoma of the left parietal and occipital bones 16 years after radiotherapy for glioma in the right occipital lobe. Radiotherapy of the primary neoplasm used 50 Gy administered to a localized field through two lateral ports. The secondary neoplasm arose contralateral to the primary lesion but within the irradiated field. The tumor had a multilocular cyst with considerable intracranial extension, and symptoms of elevated intracranial pressure were prominent early in the course. After a short-lived initial remission following surgical intervention and chemotherapy, the patient deteriorated because of tumor recurrence and died 18 months after the diagnosis. Radiation-induced osteosarcoma is a well-known but rare complication of radiotherapy for brain neoplasms with a poor prognosis.

Adult↗
PubMed1975

Spectral measurements and Monte Carlo calculations of scattered radiation from therapeutic radiation sources.

Spectral measurements have been made on scattered radiation in a perspex phantom in various depths from a kilocurie 60Co unit and a 6 MeV linear accelerator using a NaI crystal spectrometer. The measurements are compared to Monte Carlo calculations and a good agreement is obtained. The measured total photon distributions make the basis for calculations of absorbed dose and track length distributions in LET and their average values for the different depths and fields.

Cobalt Radioisotopes↗
PubMed1994

The correct usage of the new radiation oncology codes. 77395--3-dimensional simulation; 77419--conformal weekly radiation therapy treatment management; 77432--stereotactic treatment management.

In summary, radiation oncology now has three new related codes describing the 3-dimensional simulation and treatment of relatively small tumor volumes. These codes, when properly used and completely documented, are reimbursable at rates higher than the conventional simulation and treatment delivery codes that they replace. The physician should be cautioned however, that the indiscriminate use of these codes without accurate documentation of the medical necessity could result in penalties and/or pay back in the event of an audit. As with all new codes, we may rest assured that the insurance carrier will be looking very carefully at the documentation of these new and expensive procedures.

Computer Simulation↗
PubMedDate not supplied

[Possible modification of radiation injury using radio frequency electromagnetic radiation].

The possibility of radioprotective action of electromagnetic fields and radiations in radiofrequency range have been considered. It has been shown that the EMF and EMR effects depend on parameters of acting field. It is necessary to establish biophysical and biochemical ways and mechanisms of EMF and EMR action for effective use of radioemissions as radioprotectors.

Animals↗
PubMedDate not supplied

[A radiation method of determining the voltage of x-ray radiation generation. Its status and the outlook].

The paper reviews currently available methods for noninvasive determination of the voltage of X-ray radiation generation. It describes their advantages and disadvantages. The technical data of some commercially produced devices are presented. The paper shows it necessary to develop a standard for noninvasive X-ray tube voltage control and describes the main points of the standard presently developed in the framework of the International Electrical Committee 62C.

Calibration↗
PubMed2001

[Radiation exposure in diagnostic radiation: a quantification model for analytic epidemiological studies].

The present paper introduces a model for retrospective assessment of radiation exposure to patients undergoing conventional diagnostic radiography. The model allows for the quantification of relevant organ doses as well as the effective dose from exposures in the time period between 1946 and 1995. The assessment procedure consists of three consecutive steps. The first step uses a set of ideal doses that were measured under optimum conditions. In the second step, we account for the state of radiological technology available at the time of a given exposure. The third step, finally, considers the prevailing standard of radiological practice. Model parameters are derived from a compilation of data from the contemporary radiologic literature as well as from a multitude of historic sources. The three-dimensional matrix of ideal doses and respective correction factors presented here can be readily implemented in the context of analytic epidemiological studies.

Humans↗
PubMed1969

A radiation source for testing optical solar radiation effects.

This paper discusses the recent engineering developments incorporated in a new mercury injection lamp. The injection of mercury through one of the electrodes into the arc permits constructing a cooling system for electrodes and bulb. This results in a higher powered mercury lamp than previously known. The realized highest electrical input of 7.5 kw was given by our power supply; it is not the limitation of the lamp. To simulate solar radiation, it is necessary to have a lamp with a high radiance. The second interesting point is the variability of the spectral energy distribution. To improve the spectrum, perhaps to simulate solar spectral match, many elements can be added to the mercury. Most of the metals build fluid amalgams with mercury.

Equipment Design↗
PubMed2003

Symptomatic cardiac events following radiation therapy for left-sided breast cancer: possible association with radiation therapy-induced changes in regional perfusion.

Our group has demonstrated that tangential radiation therapy (RT) to the left breast or chest wall can cause perfusion changes in the anterior myocardium. We assess if RT-induced perfusion changes are associated with the development of symptoms consistent with cardiac dysfunction. Between 1998 and 2001, 114 patients were enrolled into an institutional review board-approved prospective study and had pre-RT and serial post-RT (range, 6-24 months) single photon emission computed tomography (SPECT) scans to assess changes in regional cardiac perfusion. Thirty-one patients were excluded. The incidence of cardiac symptoms in patients with and without RT-induced perfusion defects was compared using a 2-tailed Fisher's exact test. With a median follow-up of 16 months (range, 6-24 months), 10 of 83 evaluable patients had > or = 1 episode of transient chest pain, occurring 0-14 months after RT (median, 6 months). The rates of chest pain in the patients with and without new perfusion defects were 9 of 31 and 1 of 52, respectively (P = 0.0004). A similar result was found when patients were segregated based on the use of chemotherapy. Two of these 10 cases were diagnosed as pericarditis. No patient had myocardial infarction or congestive heart failure. Cardiac symptoms occur more frequently in patients with perfusion abnormalities by SPECT after RT than in patients with normal SPECT scans, suggesting that such perfusion defects may be clinically significant. One confounding factor is that women who know they have RT-induced perfusion defects may be more likely to report episode of chest pain. Long-term follow-up will be necessary to better assess the clinical significance of RT-induced perfusion defects.

Breast Neoplasms↗
PubMed1991

Deletion of self-reactive T cells in the donor-derived T cells but not in the host-derived T cells in fully allogeneic radiation chimeras. Mls-reactive T cells in allogeneic radiation chimeras.

Kinetics of T cells bearing V beta 6 capable of recognizing Mls-1a were examined in the thymus and peripheral lymphoid organs of two allogeneic bone marrow chimeras; AKR/J(H-2k, Thy1.1,Mls-1a)----C3H/He(H-2k, Thy1.2,Mls-1b) and AKR/J----C57BL/6(H-2b,Thy1.2, Mls-1b). Sequential appearance of host- and donor-derived T cells occurred in the thymus and the peripheral lymphoid organs of both AKR----C3H and AKR----B6 chimeras. The first cells to repopulate the thymus were Thy1.2+ host-derived radioresistant cells, which were synchronized in their development. The host-derived cells in thymus of AKR----B6 chimeras differentiate more rapidly than those in AKR----C3H chimeras. An almost complete replacement from host-derived cells to donor-derived cells occurred by day 21 after reconstitution in AKR----C3H and AKR----B6 chimeras. In the donor-derived thymocytes, none of CD4- or CD8-single positive thymocytes expressed high density of V beta 6 in either AKR----C3H or AKR----B6 chimeras, whereas the host-derived thymocytes in AKR----B6 chimeras contained an appreciable number of CD4-single positive thymocytes bearing V beta 6. In the peripheral lymphoid organs, T cells bearing V beta 6 were virtually abolished in Thy1.1+ cell pool of both AKR----C3H and AKR----B6 chimeras. While V beta 6+ T cells of host-origin were detected in the peripheral lymphoid organs in AKR----B6 chimeras. These result indicated that the donor-derived mature T cells showed deletion of V beta 6 in the thymus and the peripheral lymphoid organs in both AKR----C3H and AKR----B6 chimeras, whereas lack of V beta 6 deletion was observed in the host-derived mature T cells in the AKR----B6 chimeras. These results suggested that the host-derived thymocytes may likely to escape undergoing a negative selection against donor-phenotype in the radiation bone marrow chimeras.

Animals↗
PubMedDate not supplied

Radiation therapy of the para-aortic lymph nodes in carcinoma of the uterine cervix: the concurrent use of cimetidine to reduce acute and subacute side effects from radiation.

A prospective study of the effects of radiation therapy (RT) on para-aortic lymph nodes in uterine cervical cancer was conducted. As part of the study, cimetidine (800 mg daily) was administered during RT to relieve and prevent adverse reactions of the gastrointestinal tract caused by RT. In half of the patients, cimetidine (400 mg daily) was continued after RT was finished. The RT field was 7 to 8 cm wide and covered the area from the 4th lumbar to 11th thoracic vertebrae. The total dose administered was 45 Gy in 25 fractions over a five-week period. From September 1986 through October 1987, 89 patients were entered in this study. During RT, only slight gastrointestinal symptoms, such as nausea, vomiting, appetite loss, fatigue, and epigastralgia, were observed. These symptoms increased when cimetidine was withdrawn, but not in the patients who continued to receive cimetidine. It is concluded that cimetidine during and after RT can reduce the acute and subacute side effects of RT.

Acute Disease↗
PubMed1989

[Effects of laser radiation on the periodontium. An animal model approach. Effects of usual radiation dosage].

Twenty four albino mice of forty days old were selected. Twelve forty days old albino mice were irradiated with a Helium-Neon laser source, dose of 10.50566 Jul/cm2. They were divided in two groups according to time of animal sacrifice (immediately after irradiation and ten days after). As control were used twelve mice using the same time as the experimental groups, but without radiation. T.E.M. ultrathin sections showed alteration only in the conjunctiva and in the bone tissues, but not in the epithelial tissue. The bone showed two osteocyte population according to their response to irradiation. The first population showed characteristic comparable with the controls, and the second showed alterations suggestive of a degenerative process. The connective tissue also showed two fibroblasts populations, the first showed signs of a big synthesizing activity, and the second, degenerative signs. The first fibroblast population appeared in the animals sacrificed immediately after irradiation.

Animals↗