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PubMedDate not supplied

[Radiation safety of exploitation of radiation sources at the civil aviation airlines].

Radiation risks from isotope-containing equipment, and ionizing and unused X-ray radiation sources are characterized and relevant normative documents with safety requirements to radiation sources installation, radiation safety of aircraft servicing and repair, hand luggage control and heavy luggage registration, personal protection items, system of radiation monitoring at airlines and aircraft works, and liability for breach of performance guidelines are cited.

Aviation↗
PubMed1998

Radiation proctitis. Clinical and pathological manifestations, therapy and prophylaxis of acute and late injurious effects of radiation on the rectal mucosa.

BACKGROUND: Often the rectum is the dose-limiting organ in curative radiation therapy of pelvic malignancies. It reacts with serous, mucoid, or more rarely bloody diarrhea. METHODS: A research for reports on prophylactic and supportive therapies of radiation-induced proctitis was performed (Medline, Cancerlit, and others). RESULTS: No proven effective prophylactic local or systemic therapies of radiation proctitis exist. Also, no reasonable causal medication is known. In the treatment of late radiation sequelae no clinically tested certain effective therapy exists, too. Antiinflammatory, steroidal or non-steroidal therapeutics as well as sucralfate can be used as topical measures. They will be successful in some patients. Side effects are rare and the therapy is cost-effective. Treatment failures can be treated by hyperbaric oxygen. This will achieve good clinical results in about 50% of the cases. Single or few mucosal telangiectasias with rectal bleeding can be treated sufficiently by endoscopic catheterization. CONCLUSION: Besides clinical studies acute proctitis should be treated just symptomatically. Radical surgery should be performed only when all conventional treatments have been uneffective, although no certain effective therapies of radiation-induced late proctitis exist.

Acute Disease↗
PubMedDate not supplied

[Analysis of the epidemiological data concerning radiation carcinogenic effects and approaches to the low doses' upper limits determination in the aspect of a threshold of the unhealthy influences of ionizing radiation].

The analysis of the epidemiological data regarding cancer mortality in cohorts of Japanese A-bomb survivors and Chermobyl liquidators exposed to different doses suggests that there are good reasons for recognizing the threshold of the radiocarcinogenic effect in the region of about 200 Gy (mSv). The analysis of solid cancer mortality in Japanese cohort, which exceeded the expected one in a dose diapason of 5-200 mSv, revealed a (quasi) plateau in a dose-effect curve and led to the conclusion that the nature of the overshoot is non-radiogenic. The analysis of supposedly dose dependent leucosis incidence in the limited low dose diapason in the Chernobyl cohort showed that the real coefficient of the excess absolute or relative radiation risk could not be received in the case because the larger part curve was placed under the control level. In supporting the principle of single hit in a cell nucleus as a base of microdosimetric determination of low radiation doses, the approach to objective delimitation between low, intermediate and high doses regions has been proposed. The low doses upper limit of sparse ionizing radiation for cell nucleus of 8 microns in diameter has been evaluated as 0.65 mGy. It can serve for evaluation of the dose rate threshold regarding the safe chronic radiation levels in the environment.

Cell Nucleus↗
PubMed1987

Hyperfractionated photon radiation therapy in the treatment of advanced squamous cell carcinoma of the oral cavity, pharynx, larynx, and sinuses, using radiation therapy as the only planned modality: (preliminary report) by the Radiation Therapy Oncology Group (RTOG).

From August 1979 to June 1983, the RTOG conducted a prospective Phase III study that compared a standard schedule with five fractions per week of 180 to 200 cGy per day to a total dose of 6600-7380 cGy, with a hyperfractionation regimen consisting of two fractions of 120 cGy per day, separated by a rest period of 3 to 6 hours for a total of 6000 cGy. A total of 210 patients were entered, of which 187 are analyzed. Complete initial tumor clearance in the head and neck was achieved by radiotherapy in 61% of the patients assigned to the standard schedules and in 59% of those assigned to the continuous hyperfractionation schedule; surgical salvage contributed towards achieving complete response in 5% and 7% of patients, respectively. The Kaplan-Meier estimates for loco-regional control of tumor at 1 and 2 years was 39% and 29% for the standard schedules, and 43% and 30% for the hyperfractionation schedule. The endpoints examined to evaluate therapeutic effects do not indicate that the stated hyperfractionation schedule is different than the standard RTOG treatment schedule for head and neck cancer. Acute normal tissue reactions appear to be more severe with the hyperfractionation schedule but the incidence of late reactions is similar in both groups. There is a tendency toward more severe acute reactions when the interval between the two fractions per day is 4.5 hrs or less in comparison to intervals longer than 4.5 hrs.

Aged↗
PubMed2001

Defining the optimal radiation dose with three-dimensional conformal radiation therapy for patients with nonmetastatic prostate carcinoma by using recursive partitioning techniques.

BACKGROUND: The objective of this study was to determine the effect of dose and its interaction with known prognostic variables, including pretreatment prostate specific antigen (PSA), Gleason score (GS), and T classification, on patients with nonmetastatic prostate carcinoma treated with three-dimensional conformal radiation therapy (3DCRT) alone using recursive partitioning analysis. METHODS: Between November 1987 and November 1997, 939 patients with nonmetastatic prostate carcinoma were treated with 3DCRT alone at Fox Chase Cancer Center. Biochemical no evidence of disease (bNED) control was defined using the American Society of Therapeutic Radiology and Oncology Consensus definition. Recursive partitioning analysis was used to identify subgroups with similar risks of bNED failure. Prognostic factors used in the model included pretreatment PSA, GS, T classification, and radiation dose. The median follow-up was 47 months (range, 2-133 months). RESULTS: Twelve terminal nodes of the decision tree were merged to form four prognostic groups with similar bNED control rates. The 5-year actuarial rates of bNED control rates for Groups I, II, III, and IV were 84%, 41%, 16%, and 67%, respectively (P < 0.0001). Increasing the dose to greater than 7235 centigray (cGy) improved bNED control rates for patients with PSA levels of 10-19.9 ng/mL and T1/2a classification disease. Increasing the dose to greater than 7629 cGy improved bNED control rates for patients with T2b/3 classification disease with PSA levels less than 20 ng/mL. Patients with PSA levels greater than or equal to 20 ng/mL need high-dose 3DCRT. For those patients with GS 2-6 and T1/2a classification disease, treatment with greater than 7400 cGy resulted in 67% bNED control rate versus 16% at 5 years for treatment with less than 7400 cGy. High radiation dose (> 7700 cGy) improved bNED control rate from 16% to 41% for patients with high-risk disease (PSA > or = 20 ng/mL and GS 7-10) at 5 years. CONCLUSIONS: The authors showed that with recursive partitioning techniques radiation dose continues to be an important predictor of bNED control rate and that a radiation dose response for patients with clinically localized prostate carcinoma exists. Patients with one or more prognostic feature (PSA > 10 ng/mL, classification T2b/T3, GS 7-10, or the presence of perineural invasion) achieve similar rates of bNED control compared with those patients with lower volume disease when radiation dose is increased.

Adult↗
PubMed2000

The Effect of Simulated Solar Radiation on Escherichia coli: The Relative Roles of UV-B, UV-A, and Photosynthetically Active Radiation.

The relative role of components of solar radiation (UV-B, UV-A, and photosynthetically active radiation) as well as the effect of simulated sunlight upon the physiological state of Escherichia coli in fresh water were evaluated. Simulated solar radiation had a sublethal effect on E. coli populations in a short-time exposure by provoking loss of culturability and the formation of viable but nonculturable cells. Prolonged exposure increased the damage to cells but cellular integrity was never affected. However, important differences between the way the sunlight components acted were detected. After photosynthetically active radiation (PAR) exposure, cells remained metabolically active but only 10% of the cells were culturable. When cells were exposed to UV-A, the culturable fraction was similar to the one obtained after PAR irradiation, although formation of viable but nonculturable cells was not observed. For UV-B radiation short-time exposures (6 h) were enough to provoke loss of culturability and a reduction in activity similar to that of simulated sunlight exposed cells. The effect of simulated solar radiation on E. coli cells was mainly attributable to shorter wavelengths, but a synergistic interaction of the UV-B, UV-A and PAR components was detected. </hea

Journal Article↗
PubMed1991

Pancoast tumor: radiation therapy alone versus preoperative radiation therapy and surgery.

This is a retrospective analysis of 73 patients with non-oat cell carcinoma of the lung presenting as a Pancoast tumor. All patients were treated with curative intent between October 1964 and September 1987 (minimum follow-up 2 years). The treatment plan consisted of preoperative radiation therapy (usually 3000 cGy in 2 weeks or 4500 cGy in 5 weeks) in 41 patients and radiation therapy alone (usually 6500-7000 cGy in 6.5-8.0 weeks) in 32 patients. In general, radiation therapy alone was reserved for poor-prognosis patients (extensive disease or medical inoperability). Although 41 patients were initially scheduled to receive preoperative radiation therapy and surgery, the surgery was not performed in 12 cases (29%) because of patient refusal (4 patients), poor response to radiation therapy (4 patients), distant metastasis (2 patients), or debilitation (2 patients). Separate calculations were carried out for the patients who completed the surgery as planned (preoperative radiation therapy and surgery) and the entire group originally scheduled for combined-modality therapy. There was no significant difference in the absolute or cause-specific survival rates between treatment groups, but severe complications were significantly more common in patients receiving combined therapy.

Adult↗
PubMed1993

Three-dimensional conformal radiation therapy may improve the therapeutic ratio of high dose radiation therapy for lung cancer.

PURPOSE: The specific aim of 3-dimensional conformal radiation therapy is to improve the target dose distribution while concomitantly reducing normal tissue dose. Such an approach should permit dose escalation until the limits of acceptable normal tissue toxicity are reached. To evaluate the feasibility of tumor dose escalation for nine patients with lung cancer, we determined the dose distribution to the target and normal tissues with 3-dimensional conformal radiation therapy and conventional planning. METHODS AND MATERIALS: Plans were compared to assess adequacy of dose delivery to target volumes, dose-volume histograms for normal tissue, and normal tissue complication probabilities (NTCP) for nine patients with lung tumors. RESULTS: The mean percentage of gross disease which received < or = 70.2 Gy with 3-dimensional conformal radiation therapy (3DCRT) was 40% of the mean percentage of gross disease which received < or = 70.2 Gy with conventional treatment planning (CTP). The mean NTCP for lung parenchyma with 3DCRT was 36% of the mean NTCP with CTP. The mean esophageal NTCP with 3DCRT was 88% of the mean NTCP with CTP. CONCLUSION: This preliminary analysis suggests that three dimensional conformal radiation therapy may provide superior delivery of high dose radiation with reduced risk to normal tissue, suggesting that this approach may have the potential to improve the therapeutic ratio of high dose radiation therapy for lung cancer.

Adenocarcinoma↗