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At least 865 records · Page 48Linked to original sources
PubMed2001

Mechanistic bases for modelling space radiation risk and planning radiation protection of astronauts.

The approaches generally adopted for planning radiation protection in ground-based facilities cannot be applied straightforward for astronaut protection in space. Indeed in such extreme conditions, modelling methods and shielding design must be based on a detailed mechanistic knowledge of the peculiar astronauts irradiation conditions. Great help can derive from mechanistic modelling, generally aimed to better understand the intermediate steps leading from the initial energy depositions to different biological endpoints, up to organ and organism level. In the present work, criteria will be illustrated for using mechanistic approaches in developing practical tools for astronauts radioprotection, once the external field and the interaction cross sections with the spacecraft walls are known; particular attention will be given to the treatment of mixed fields. Techniques for integrating into condensed-history codes stochastic information provided by event-by-event simulations will be presented.

Aerospace Medicine↗
PubMedDate not supplied

[Postirradiation change in the radiosensitivity of rats in relation to the preliminary radiation dose in the cutaneous form of radiation injury].

The experimental animals were exposed two times to soft 17kV X-radiation. Post-irradiation changes in radiosensitivity were shown to depend upon dose of preliminary irradiation (10, 18 and 25 Gy). The state of radiosensitive tissues was studied and a comparison was made of a residual damage curve with a change in the proliferative activity of dividing tissue elements during 30 days after irradiation.

Animals↗
PubMedDate not supplied

[Decrease of toxic effects of aminothiol radiation-protective agents and increase of chemical protection action against ionizing radiation by the use of unithiol].

It has been shown that unithiol diminishes toxic action of cysteamine, AET, and disulfide of WR-1065 on mice. This permits to enhance protection of animals against X-rays by increasing of protector doses. The effect of unithiol on cysteamine action in rats was the same. Antitoxic effect of unithiol on cysteamine was shown both at i.p. and p.o. protector administration. The effect was also revealed in Chinese hamster V-79 cell culture. Combined disulfide of cysteamine and unithiol was synthetized, which ensures effective prolonged protection against ionizing radiation.

Animals↗
PubMed1979

Radiation-induced pharyngeal stenosis. A report of two cases after planned postoperative radiation therapy.

Two cases of almost complete stenosis of the hypopharynx occurred after laryngectomy, radical neck dissection, and postoperative radiation therapy. Successful reconstruction that utilized a tubed, deltopectoral flap was accomplished in each case. In the absence of evidence indicating increased long-term survival with combined surgery and postoperative radiation therapy, one must question the utilization of these methods. Decreased local recurrence or cervical metastasis may not be an adequate justification if the rate of complications is notably increased, especially when complications can be as severe as these.

Aged↗
PubMed2004

6-month androgen suppression plus radiation therapy vs radiation therapy alone for patients with clinically localized prostate cancer: a randomized controlled trial.

CONTEXT: Survival benefit in the management of high-grade clinically localized prostate cancer has been shown for 70 Gy radiation therapy combined with 3 years of androgen suppression therapy (AST), but long-term AST is associated with many adverse events. OBJECTIVE: To assess the survival benefit of 3-dimensional conformal radiation therapy (3D-CRT) alone or in combination with 6 months of AST in patients with clinically localized prostate cancer. DESIGN, SETTING, AND PATIENTS: A prospective randomized controlled trial of 206 patients with clinically localized prostate cancer who were randomized to receive 70 Gy 3D-CRT alone (n = 104) or in combination with 6 months of AST (n = 102) from December 1, 1995, to April 15, 2001. Eligible patients included those with a prostate-specific antigen (PSA) of at least 10 ng/mL, a Gleason score of at least 7, or radiographic evidence of extraprostatic disease. MAIN OUTCOME MEASURES: Time to PSA failure (PSA >1.0 ng/mL and increasing >0.2 ng/mL on 2 consecutive visits) and overall survival. RESULTS: After a median follow-up of 4.52 years, patients randomized to receive 3D-CRT plus AST had a significantly higher survival (P =.04), lower prostate cancer-specific mortality (P =.02), and higher survival free of salvage AST (P =.002). Kaplan-Meier estimates of 5-year survival rates were 88% (95% confidence interval [CI], 80%-95%) in the 3D-CRT plus AST group vs 78% (95% CI, 68%-88%) in the 3D-CRT group. Rates of survival free of salvage AST at 5 years were 82% (95% CI, 73%-90%) in the 3D-CRT plus AST group vs 57% (95% CI, 46%-69%) in the 3D-CRT group. CONCLUSION: The addition of 6 months of AST to 70 Gy 3D-CRT confers an overall survival benefit for patients with clinically localized prostate cancer.

Adenocarcinoma↗
PubMed1980

A randomized combined modality trial in small cell carcinoma of the lung: comparison of combination chemotherapy-radiation therapy versus cyclophosphamide-radiation therapy effects of maintenance chemotherapy and prophylactiv whole brain irradiation.

A randomized trial of combined modality therapy employing combination chemotherapy (cyclophosphamide (CTX) and methotrexate (MTX), CTX, MTX and Vincristine (VCR) and CTX, VCR and high-dose MTX with citrovorum rescue) and radiation therapy was compared to cyclophosphamide and radiation therapy in 258 patients with pulmonary small cell carcinoma. Patients were also rendomized: 1) to determine the effects of prophylactic whole brain irradiation; and 2) to establish the effects of maintenance chemotherapy. Survival, frequency of response and site of relapse were different in patients with limited disease (LD) (disease confined to lung, mediastinum and supraclavicular lymph nodes) when compared with disease spread beyond these sites (extensive disease) (ED). No survival advantage was seen in LD when combination chemotherapy was employed, although the frequency of complete remission was greater with three drugs than with one or two drugs (40% vs. 32%). In ED frequency of response was greater for three drugs than for one and two drugs (60% vs. 40%), but there was no survival advantage. The median survival time for complete responders was similar for limited or extensive disease (12.1 months), but 23.8% were alive at 24 months with LD compared to none with ED. Maintenance chemotherapy significantly prolonged survival by 16.8 months with 33% alive at 24 months compared to 9% who were unmaintained. Prophylactic while brain irradiation prevented brain metastases with only 4% developing this complication as compared to 18% of control subjects, but did not influence survival.

Antineoplastic Agents↗
PubMed1983

The role of radiation therapy in the palliation of metastatic genitourinary tract carcinomas. A study of the Radiation Therapy Oncology Group.

The Radiation Therapy Oncology Group has conducted several randomized clinical trials to evaluate the efficacy of various radiation therapy schedules in palliating symptomatic brain and bone metastases. Among the patients entered in these studies, there were 225 patients with primary tumors of the genitourinary tract. Of these, 68 patients had cerebral metastases and 157 patients had osseous metastases. These patients were analyzed further as to the effectiveness of radiotherapy in palliation of their symptoms, and the results were compared to those for comparable metastases in patients with other primary sites. Relief of symptoms occurred in 54% of neurologic function (NF) Class III and 28% of NF Class II patients with cerebral metastases. This result compared favorably with those for the total group of patients consisting of patients with brain and bone metastases from various primary sites. Improvement was seen in 80% of patients with headaches and 88% of patients with convulsions. Motor loss improved in 62% of the patients. Of the patients with bone metastases, 81% with prostatic carcinoma and 59% with renal primaries had lessening of pain. Complete relief of pain at eight weeks occurred in 36% of the patients, compared to 24% in the total group. The median survival for patients with solitary bone metastases from a prostatic primary was 39 weeks, compared to 30 weeks for those with multiple metastatic sites.

Bone Neoplasms↗
PubMed1988

Medulloblastoma at the joint center for radiation therapy between 1968 and 1984. The influence of radiation dose on the patterns of failure and survival.

In order to assess the efficacy of high-dose irradiation to the posterior fossa and low-dose irradiation to the spinal axis, we reviewed the results of 60 patients with biopsy-proven medulloblastoma treated at the Joint Center for Radiation Therapy (JCRT) between 1968 and 1984. The 5- and 10-year actuarial survival rates for all patients were 68% and 44%, respectively. The median time to recurrence was 19 months. Extent of surgery, age, and radiation dose to the posterior fossa all were of prognostic value. Complete or subtotal gross resection appeared to be a favorable prognostic indicator compared with biopsy only (P less than 0.05), with a 69% versus 40% actuarial survival rate at 5 years, respectively. Infants 2 years of age or less had a diminished 5-year actuarial survival rate of 48% (P less than 0.05) compared with older age groups. The posterior fossa was the predominant site of recurrence and accounted for 78% of all failures. Local control in the posterior fossa was dose dependent. Seventy-nine percent of the tumors that received 5000 cGy or greater were controlled versus only 33% of the tumors that received less than 5000 cGy (P less than 0.02). There were no supratentorial failures, and there was only one isolated spinal cord failure. There were no solitary spinal failures in 24 patients who received a median dose of only 2400 cGy to the spinal axis. We concluded that low-dose irradiation to the spine and whole brain may be indicated with maintenance of a posterior fossa dose of greater than 5000 cGy.

Adolescent↗
PubMed2004

Impact of radiation dose on late clinical outcome after intracoronary radiation therapy: three-year follow-up of Long WRIST.

To determine the safety and efficacy, including the impact, on the late recurrence rate of an incremental gamma-radiation dose from 15 to 18 Gy, we report the 3-year clinical outcome of Washington Radiation for In-Stent Restenosis Trial for Long Lesions (Long WRIST). One hundred eighty patients with recurrent in-stent restenosis (ISR) were enrolled in the Long WRIST series and treated with (192)Ir with 1 month of antiplatelet therapy. Between 6 months and 3 years, the need for repeat revascularization was low and similar among the three groups. At 3 years, target lesion revascularization (TLR) and major adverse cardiac events (MACE) were less frequent in the 18 Gy group than in the 15 Gy group (P = 0.12 for TLR, P < 0.05 for MACE) and less frequent in the 15 Gy group as compared to the placebo group (P < 0.05 for TLR and MACE). At 3 years, a higher dose of 18 Gy with (192)Ir continues to improve the outcome of patients treated for ISR when compared to patients treated with 15 Gy or placebo.

Analysis of Variance↗
PubMed2004

Radiation-induced genomic instability: a role for secreted soluble factors in communicating the radiation response to non-irradiated cells.

Radiation induced genomic instability can be described as the increased rate of genomic alterations occurring in the progeny of an irradiated cell. Its manifestations are the dynamic ongoing production of chromosomal rearrangements, mutations, gene amplifications, transformation, microsatellite instability, and/or cell killing. In this prospectus, we present the hypothesis that cellular exposure to ionizing radiation can result in the secretion of soluble factors by irradiated cells and/or their progeny, and that these factors can elicit responses in other cells thereby initiating and perpetuating ongoing genomic instability.

Bystander Effect↗
PubMed1993

Soft tissue studies with 805 nm diode laser radiation: thermal effects with contact tips and comparison with effects of 1064 nm Nd:YAG laser radiation.

This study compares the perioperative depths of thermal coagulation, charring, and incision in rabbit liver, internal anterior abdominal wall skeletal muscle, and abdominal skin and in swine liver and abdominal skin obtained with 805 nm diode laser and 1,064 nm Nd:YAG laser radiation using 300-microns-diameter conical-tip and 1,200-microns-diameter spherical-tip contact fibers by hand. Additionally, the total depth of tissue necrosis surrounding incisions made with both lasers and contact tips is determined 48 hours postoperatively in the three tissues, and healing of the liver and abdominal wall muscle 21 and 35 days postoperatively is assessed histologically. Perioperatively determined charring, coagulation, and incision depth obtained in all tissues with either 805 nm or 1,064 nm laser radiation were sensibly equivalent at equal laser power values for each of the two contact tip shapes tested. At equal laser power values, coagulation depths obtained in rabbit abdominal skin using the 300-microns-diameter conical tip differed significantly (P < or = 0.01) from those values obtained with the 1,200-microns-diameter spherical tip. Incision depths obtained with the two different contact tip shapes at equal laser power settings in the different tissues studied differed in a few instances with no apparent pattern relating to tissue type or laser power. Depth of incisions obtained with both laser and tip types increases in the range of 6-12 w, but plateaus in the range 12-18 w in the tissues studied. Incisions obtained with both diode and Nd:YAG laser contact were essentially hemostatic, with self-limiting oozing at most.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdominal Muscles↗
PubMed1995

Endobronchial radiation therapy for obstructing malignancies: ten years' experience with iridium-192 high-dose radiation brachytherapy afterloading technique in 365 patients.

From 1983 to 1993, 365 patients with obstructing endobronchial malignancies were treated by endobronchial high-dose radiation (HDR) iridium-192 afterloading. In 346 patients, the objective was palliation, and in 19, the objective was curative. A dose of 5 Gy at 10 mm from the source axis was administered on three (palliation) and four (cure) occasions, at intervals of 14 days. The majority of patients were treated after exhaustion of external beam radiation therapy (EBRT), often in conjunction with other interventional bronchologic modalities such as endobronchial laser resection. Of the patients, 65% had a squamous cell carcinoma. Endobronchial HDR brachytherapy results in few acute complications and can be performed with no major discomfort on an outpatient basis. In approximately 66% of patients, a palliative effect is achieved, even after the exhaustion of conventional treatment. Life may be prolonged for a few months, but the enhancement of survival is difficult to assess for several reasons. Mean survival is 9 months for limited disease and 5 months for extensive disease. Endobronchial HDR brachytherapy influences the pattern of failure: a 21% rate of fatal hemorrhages is probably the result of the selection of patients for this treatment rather than a treatment-related complication. There is sufficient evidence to suggest the rational use of HDR brachytherapy in combination with EBRT to effect a cure, or even on its own when tumor growth is strictly limited. However, the standardization of radiotherapy and endoscopic indications is an urgent priority. Prospective, controlled, and cooperative studies are mandatory. Endobronchial iridium-192 HDR brachytherapy complements endobronchial laser resection and is currently an established technique in the treatment of advanced malignant airway obstruction.

Airway Obstruction↗
PubMed1998

Neutron, proton, and photonuclear cross-sections for radiation therapy and radiation protection.

I review recent work at Los Alamos undertaken to evaluate neutron, proton, and photonuclear cross-sections up to 150 MeV (to 250 MeV for protons), based on experimental data and nuclear model calculations. These data are represented in the ENDF format and can be used in computer codes to simulate radiation transport. They permit calculations of absorbed dose in the body from therapy beams, and through use of kerma coefficients allow absorbed dose to be estimated for a given neutron energy distribution. In radiation protection, these data can be used to determine shielding requirements in accelerator environments and to calculate neutron, proton, gamma-ray, and radionuclide production. Illustrative comparisons of the evaluated cross-section and kerma coefficient data with measurements are given.

Carbon↗
PubMed2006

Unusual behavior of foreign body granuloma that grew rapidly in the radiation field during radiation therapy.

We report our experience with two cases of a rapidly growing benign tumor in the radiation field despite radiotherapy. Case 1 was a 75-year-old man who was diagnosed as having postoperative recurrence of esophageal carcinoma in the right chest wall and underwent radiotherapy. A small nodule in the recurrent lesion grew to 20 mm in diameter at 70 Gy. The biopsy specimen was diagnosed as foreign body granuloma (FBG) with no malignancy. Case 2 was a 78-year-old woman who was diagnosed with axillary lymph node metastases of operated lung cancer and underwent lymphadenectomy and postoperative radiotherapy. No subcutaneous tumor was seen at the beginning of radiotherapy. However, a small nodule appeared in the radiation field at 40 Gy, and it had grown to 30 mm in diameter at 70 Gy. The biopsy specimen was diagnosed as FBG, showing granulation because of a remnant of surgical suture. Both FBGs disappeared within 3-6 months after radiotherapy. In cases in which a tumor has arisen from a site where surgical treatment had been performed and the tumor shows unnatural growth despite radiotherapy, FBG should be considered in the differential diagnosis.

Axilla↗
PubMed1984

Systemic suppression of contact hypersensitivity by ultraviolet b radiation or methoxsalen/ultraviolet a radiation in the guinea pig.

Treatment of strain 2 guinea pigs with ultraviolet b (uvb) (280-320 nm) radiation or methoxsalen, followed by ultraviolet a (uva) (320-400 nm) radiation, decreased the contact hypersensitivity (CHS) reaction to sensitizing agents applied subsequently to unirradiated sites. The decreased reactivity could be transferred to syngeneic animals and appeared to be caused by antigen-specific suppressor T lymphocytes. Ultraviolet b irradiation of sensitized animals did not affect elicitation of CHS in unirradiated skin.

Animals↗
PubMed1989

Radiation inactivation analysis of the A1 adenosine receptor of rat brain. Decrease in radiation inactivation size in the presence of guanine nucleotide.

Radiation inactivation analysis of the binding of the A1 adenosine receptor antagonist, 8-cyclopentyl-1,3-dipropylxanthine to rat brain membranes yielded a radiation inactivation size of 58 kDa. In the presence of GTP gamma S this was reduced to 33 kDa, in good agreement with the size of the ligand-binding subunit detected after photoaffinity labelling. The data indicate that the structural association of A1 adenosine receptors with G-protein components is altered in situ in the presence of guanine nucleotides.

Adenosine↗
PubMed1987

Radiation therapy of tumors of the brainstem and midbrain in children: experience of the Joint Center for Radiation Therapy and Children's Hospital Medical Center (1971-1981).

Between 1971 and 1981, 79 previously untreated children with proven or presumed gliomas of the brainstem or midbrain were seen and treated at the Joint Center for Radiation Therapy and Children's Hospital Medical Center in Boston. Twenty-seven patients had tumors of the thalamus and midbrain (Group I) and 52 had lesions of the pons or medulla (Group II). Overall 5- and 10-year survivals were 50% and 41% respectively. Eighty percent of deaths occurred within 2 years of treatment. Eighty-six percent of the children (69/79) had clinical improvement or stabilization of disease after treatment. Group I patients had a 5-year survival of 73% which was significantly greater than that of Group II patients (38%) (p = 0.007). Children who presented with hypothalamic tumors in association with a diencephalic syndrome or other growth abnormality appeared to have had a better prognosis with 6/6 (100%) surviving without evidence of disease. Age at presentation was not correlated with prognosis. Of 10 children less than 3 years of age at presentation and treatment, 6 are alive (60%) at 2, 3, 7, 9, 10, and 12 years after treatment. The functional results in this group have been good--all six are leading apparently normal lives in regular schools with minor or no apparent neurologic deficits. Although these children will require long term follow-up to determine whether cures have actually been achieved, it appears that the majority achieve some benefit, that a significant proportion enjoy long term survival, and that very young children may be treated successfully with minimal radiation-induced neurologic sequela.

Adolescent↗
PubMed1989

Treatment of locally advanced rectal cancer with external beam radiation, surgical resection, and intraoperative radiation therapy.

To try to improve the local control and survival of patients with locally advanced rectal cancer we have used a combination of high-dose pre-operative radiation therapy to 5,040 cGy followed by surgical resection and intraoperative electron beam radiation therapy (IORT) when there was visible or palpable residual disease, microscopically positive surgical margins, or persisting tumor adherence. A total of 75 patients were taken to surgery for resection +/- IORT who did not have distant metastases. Of the 49 patients with primary tumors, 11 did not have IORT as the tumor was thought to be completely resected. Of these 11, there were two local recurrences and a 3-year survival of 71%. Thirty-six patients with primary tumors had resection (20 complete, 16 partial) plus IORT, with a 3-year survival of 58% and three local failures. Twenty-six additional patients were treated for locally advanced recurrence of whom four could not receive IORT because of pelvic size or the extent of tumor. Of the 22 who received IORT, 7/9 with complete resection, 2/8 with partial resection, and 1/5 with no resection had local control with an overall 3-year actuarial survival of 32%. The local control and survival results in the primary tumors appear favorable compared to other series in the literature and suggest benefit to the use of IORT. For patients treated for local recurrence, local control and long-term survival can be obtained, but the results are not as encouraging as for the primary tumors.

Combined Modality Therapy↗