Irradiation of Langmuir-Blodgett multilayer preparations of phospholipids and a fatty acid. 1: Effect of UV radiation.

Langmuir-Blodgett (LB) preparations containing stacked monolayers of phospholipids or stearic acid were irradiated with UV light and the electric conductance perpendicular to the planes of the monolayers was measured. There was no observable change of conductance when LB preparations of stearic acid were irradiated. For LB preparations of phospholipids, a rise of conductance, dependent on dose rate, was observed, reaching an equilibrium level after a few hours. After irradiation the conductance fell with a temperature-dependent time constant, and eventually reached a final level a little above the initial value. A three-state model is proposed for the LB phospholipid preparations. This suggests that the absorption of one photon raises a molecule from the ground to an excited state; and the absorption of a second photon carries it into a damaged but repairable or metastable state.     

Fading characteristics of an alanine-polystyrene dosimeter

Alanine dosimetry is useful for transfer dosimetry by long distance mailing, because of its stability. It has the advantage that the measurement of electron spin resonance (ESR) spectral signal is non-destructive to the dosimeter, with the promise that the method may supply archival dosimetry data, depending on the degree of post-irradiation stability of the signal. The effects of temperature during irradiation and storage on fading of the ESR signal were studied using an alanine dosimeter molded with polystyrene (alanine-PS dosimeter). This investigation covered a long range of storage time (up to 160 days) after irradiation to absorbed doses in the range 1 to 100 kGy, for application to transfer dosimetry between Japan and neighboring Asian countries.Dose response of an alanine-PS dosimeter depends on the temperature during irradiation. The same temperature coefficient of +0.24%/°C was measured at different dose levels of 1, 10 and 100 kGy administered at a constant dose rate of 7 kGy/h. Fading of the dose response was measured under storage at various temperatures (5–40°C). The fading curve generally has two phases with fast and slow fading rates. The response of an alanine dosimeter is relatively stable for doses of 1.4 and 14 kGy, when stored at temperatures below 25°C. However, the degree of fading was roughly 3 and 5% under a storage temperature of 40°C for 5 and 100 days, respectively, after irradiation to 14 kGy. The fading percentages at 100 kGy were 2 and 4% (after 5 days) and 6 and 15% (after 100 days) under the storage temperature of 25 and 40°C, respectively. The fading rates have a relatively small dependence on irradiation temperature. This is observed even when irradiation are made at high temperatures (60°C) and for the doses 100 kGy and above. The mechanism of decay of radicals is discussed to explain the fading characteristics of the two phases of fading. The alanine-PS dosimeter is useful for transfer standard dosimetry up to a dose level of 10 kGy when stored after irradiation at temperature below 40°C. However, consideration of temperature effects during and after irradiation is vital for accurate transfer dosimetry of high doses, especially in the southern Asian countries.     

Influence of X-irradiation on the motor activity of rat urinary bladder in vitro and in vivo

Preparations of rat detrusor vesicae urinariae exposed to 50 kV X-irradiation with 10 to 200 Gy (single dose) at dose-rates of 30 and 60 Gy/min reacted immediately with a dose and dose-rate dependent reversible or persistent increase (up to ten hours) of the basal tone and an increase or a decrease of the acetylcholine contractile response. The motor activity was recorded isotonically. For measurements of time changes following treatment in vivo the bladder was locally irradiated from lateral position with single 300 kV X-ray doses of 10, 25 and 50 Gy. The motor reaction of isolated detrusor preparations to acetylcholine had a threshold concentration in control animals of 2.3 X 10(-10) mol/l (n = 33); the sensitivity to acetylcholine was diminished as early as one to two hours after local irradiation with 50 Gy as reflected in a ten times higher threshold concentration, which decreased further with time past treatment up to 40 days. The inhibitory effect after 25 Gy was weaker. The contractile response of acetylcholine at different concentrations (10(-10) to 10(-5) mol/l) was also diminished after irradiation (50 Gy). It is suggested that the pathophysiological reactions of the radiogenic bladder are based on multifactorial mechanisms and X-ray induced tonic contraction as well as inhibition of the acetylcholine contractile response could be essential factors for the clinically observed hypertonia of the irradiated bladder ("radiogene Harnblase") and its functional volume decrease as well as of the diminished pressure during micturition.     

Effect of γ-irradiation on gene expression of heat shock proteins in the foodborne pathogen Escherichia coli O157:H7

Abstract

Purpose: The expression levels of seven genes (clpB, dnaK, groES, grpE, htpG, htpX and ibpB) encoding heat shock proteins (HSP) in Escherichia coli O157:H7 (E. coli) gamma irradiated was investigated. Timing impact of post-irradiated RNA extraction on the expression levels of these seven genes was also studied at a dose damaging the bacterial cells (0.4 kGy).

Methods: Bacterial samples were γ-irradiated at 0.4 kGy and at a lethal dose of 1.3 kGy. RNA was extracted at 0 min post irradiation for both irradiation doses and at 15, 30, 60, 90 or 120 min post-irradiation at the dose damaging the cells. Quantification of the gene expression was performed using quantitative real-time polymerase chain reaction (q-RT-PCR).

Results: The expression of genes encoding HSP was a very dynamic process evolving rapidly when E. coli cells were irradiated at 0.4 kGy. Notably, groES, grpE and ibpB were more up- regulated at 1.3 kGy than those at 0.4 kGy.

Conclusions: For the seven genes studied there were more damaged proteins during irradiation at the lethal dose and this dose causes increased expression in HSP which contributes to damage reparation. Expression patterns of genes encoding HSP in E. coli treated by γ-irradiation are different from those treated by heat shock.     

The gamma-ray response of clear polymethylmethacrylate dosimeter radix RN15®

Basic characteristics of different batches of Radix RN15® dosimeter, a commercially available undyed polymethylmethacrylate dosimeter, was studied for its application to process control of radiation sterilization. Radix has relatively small deviation of thickness, optical absorption spectrum, and optical density values before irradiation. The response curves, in terms of net optical density per unit thickness (ΔOD/mm) as a function of absorbed dose, D_PMMA, are nearly linear up to 15 kGy and become sublinear at higher doses. Scattering of dose response in 5 dosimeter replicates is ± 1% (1 σ). The dose-response slope at 25 kGy while held at irradiation temperatures in the range 0–60°C, relative to those under 25°C, increases with temperature up to 40°C, the maximum point, and decreases at higher temperatures. Over the temperature range of 10–50°C, the variation with temperature of evaluated dose derived from the calibration curve at 25°C is less than 5% when using a dose rate of 6 kGy/h. At lower dose rates (e.g. 0.7 kGy/h) the irradiation temperature dependence is negligible over this temperature range. The temperature dependence at 40 kGy is less severe than that at 25 kGy. The post-irradiation stability of dose response is less than 5% for more than 100 h after 25 kGy irradiation and storage at 0–35°C. The change in optical density of unirradiated dosimeters 3 years after manufacturing is negligible when the dosimeters are stored at controlled laboratory conditions of temperature (25°C) and relative humidity (40%). The 3-year-old dosimeters by irradiation to a dose of 25 kGy show about 2% lower response than that at 25 kGy at the beginning of the 3-year period.     

Immediate mechanical reactions of isolated human detrusor muscle on x-irradiation.

The mechanical activity (isotonic registration) of isolated detrusor (smooth) muscle preparations from the human urinary bladder (surgical material) is investigated. The preparations reacted on X-irradiation (50 kV) with an immediate dose-dependent tonic contraction at threshold-doses of 100 to 1000 R (1 to 3 kR/min). The contraction was either reversible, semireversible or persistent, and the basal muscle tone was elevated. A tachyphylactic reaction was observed. The phasic activity of the preparations was temporarily increased, then inhibited after irradiation. The radiation-induced changes of the human and guinea-pig detrusor muscle are compared and their possible relation to the functional disturbances of the urinary bladder after radiotherapy is discussed.     

Reactions of isolated rat aorta to X-irradiation

The reaction of isolated helical strips of rat aorta to X-irradiation was studied: X-rays (50 kV) induced a reproducible, reversible contractile response at threshold doses of 2.5 Gy (60 Gy/min) and 10 Gy (30 Gy/min). After repeated irradiation with the same doses at equal time intervals and constant dose-rate (for example 50 Gy every 15 min, dose-rate 60 Gy/min) the contractile response was progressively diminished, i.e. a tachyphylaxis appeared. The preparations still reacted even after total doses over 1000 Gy. The X-ray induced contractile responses were dose- and dose-rate dependent. Quantitative analysis indicated no essential differences in the radiation-induced contractile response when recorded under isometric or isotonic conditions. After hypothermia (20 degrees C) or hyperthermia (42 degrees C) no visible radiation response could be induced. Part of the aortic strips were spontaneously active: X-ray doses of 5 to 10 Gy stimulated, while doses of 100 to 200 Gy inhibited or blocked the spontaneous phasic activity. A comparison between the immediate X-ray reaction of vascular and non-vascular smooth muscle preparations is given. Participation of cholinergic and adrenergic mechanisms in the X-ray induced contractions of rat aorta seems to be ruled out, because the blocking agents atropine, phentolamine, and bretylium had no effect.     

Decontamination of gum arabic with gamma-rays or electron beams and effects of these treatments on the material.

Samples of gum arabic were irradiated to 2.5, 5.0 and 10.0 kGy with gamma-rays and electrons for a comparison of the relative effectiveness of these two treatments and for investigation of the effects of these doses of radiation on the material. The initial raw samples were contaminated with various strains of bacteria, including fungi and spore-forming bacteria (such as Enteroccus faecalis, Bacillus cereus and Closstridum perfringens). The samples were completely decontaminated by irradiation to 10.0 kGy with either gamma-rays or electrons. Slight changes in the physical properties of the material, such as darkening and viscosity decrease, were noticeable after irradiation to the highest dose, but not to the lower doses. A linear relationship between the absorbed dose and the material degradation was observed. gamma-rays were found to be more destructive than electrons. An optimal decontamination regimen for the material to be used in food industry and medicine would be irradiation to 5 kGy with electrons. It would be a safe alternative to the methods using hazardous chemicals, such as pesticides and fungicides. It would provide sufficient decontamination without adverse effects on the physical properties of the final products.     

Residual radiation-induced damage to the kidney of the pig as assayed by retreatment.

The effect of re-irradiation on the previously irradiated kidney was studied in the Large White female pig. Both kidneys of 14-week-old pigs were initially irradiated with a single dose of 3-7 Gy of 250 kV X-rays. The individual kidney glomerular filtration rate (GFR), effective renal plasma flow (ERPF), and the haematocrit (Hct) were serially measured up to 24 weeks after X-irradiation. Doses of 3 and 5 Gy of X-rays had little effect on the GFR. However, 7 Gy of X-rays caused a marked decline in the GFR up to 12 weeks after irradiation; the GFR then began to recover. A similar pattern of response was seen in the ERPF. In contrast, the Hct was reduced in all pigs 4 weeks after X-irradiation. The extent of the decline and subsequent recovery 24 weeks after irradiation appeared to be related to dose. Twenty-four weeks after X-irradiation both kidneys were re-irradiated with a single dose of 7.9 Gy of 60Co gamma-rays; both kidneys of four age-matched control pigs which had not previously received X-irradiation were similarly treated. Individual kidney GFR, ERPF and Hct were again serially measured up to 24 weeks after gamma-irradiation. Re-irradiation resulted in a significantly greater reduction in the GFR, ERPF and Hct compared with that seen after gamma-irradiation alone. Moreover, the severity of the reduction in the GFR and Hct observed after gamma-irradiation was related, in a dose-dependent manner, to the initial X-ray doses employed. These results indicate that the kidney fails to exhibit complete long-term recovery in function following irradiation. Re-irradiation of the kidney in patients should thus be viewed with extreme caution.     

X射线对肺癌细胞株A549的P57kip2和TGF-β1蛋白表达的影响

目的 观察不同剂量X射线照射后不同时间A549肺癌细胞株中P57^kip2和TGF-β1蛋白表达水平,探讨X射线对p57^kip2和TGF-β1的影响及临床意义。方法 按常规方法培养肺癌细胞株A549,实验分5组,照射组分别给予不同剂量X射线(2、4、8和12 Gy)照射,于不同时间(6、12、24、36和48 h)提取蛋白,采用Western blot 检测p57^kip2和TGF-β1蛋白的表达水平。结果 X射线可导致肺癌细胞P57^kip2蛋白的表达增加,照后12 h达峰值,在2～8 Gy之间,p57随着照射剂量的增加而升高,12 Gy时,其含量较4～8 Gy减少。不同剂量和不同时间P57^kip2蛋白的表达,差异有统计学意义(P＜0.05),TGF-β1在照后6h达峰值,之后迅速下降,各不同剂量和不同时间水平之间差异有统计学意义(P＜0.05)。结论 X射线照射可以上调肺癌细胞株A549的p57^kip2和TGF-β1蛋白表达,两者有一定的相关性,且在一定剂量范围内呈剂量依赖性,可以反映肺癌细胞损伤的程度。     

Products from polycrystalline DNA constituents after X-irradiation and heavy-ion bombardment: formation of the 5,6-dihydroadduct in thymidine 5'-monophosphate and release of unaltered bases in nucleotides

PURPOSE: The major products from polycrystalline purine and pyrimidine DNA nucleotides after low- and high-LET irradiation were investigated quantitatively by HPLC and 1H-NMR spectroscopy. MATERIALS AND METHODS: Solid nucleotide samples were either X-irradiated as cylindrical pellets or heavy-ion bombarded (LET range of 100-12,500 keV/microm) as very thin tablets at 300K. Product analysis was performed by HPLC and 1H-NMR. RESULTS: For TMP the 5,6-dihydroadduct was found to be formed as product of electron reaction. In addition, all four DNA nucleotides showed a radiation-induced base release, which is probably connected with the oxidative radiation action. The formation of the products was linear with dose up to 300 kGy for X-irradiation or 200 kGy for heavy-ion bombardment. The estimation of the radiation chemical yields revealed G-values of about 10(-7) mol x J(-1) and were typically smaller for irradiation with charged particles than those for X-rays. After heavy-ion bombardment the G-values first increased with increasing LET and decreased for very heavy ions. CONCLUSIONS: The yields for base release from both purine and pyrimidine nucleotides are comparable in magnitude. The 5,6-dihydroadduct from TMP is a major radiation induced product with larger yields than found for base release after X-irradiation and comparable yields after heavy-ion bombardment. The LET dependence of the G-values for base release in nucleotides is similar and resembles the double strand break formation in DNA. The observed similarity in the LET dependence of the G-values might derive from an inhomogeneous distribution of energy deposition resulting in 'clustered damage'.     

Products from polycrystalline DNA constituents after X-irradiation and heavy-ion bombardment: Formation of the 5,6-dihydroadduct in thymidine 5'-monophosphate and release of unaltered bases in nucleotides

Purpose : The major products from polycrystalline purine and pyrimidine DNA nucleotides after low- and high-LET irradiation were investigated quantitatively by HPLC and 1H-NMR spectroscopy. Materials and methods : Solid nucleotide samples were either X-irradiated as cylindrical pellets or heavy-ion bombarded (LET range of 100-12500keV/ μ m) as very thin tablets at 300K. Product analysis was performed by HPLC and 1H-NMR. Results : For TMP the 5,6-dihydroadduct was found to be formed as product of electron reaction. In addition, all four DNA nucleotides showed a radiation-induced base release, which is probably connected with the oxidative radiation action. The formation of the products was linear with dose up to 300 kGy for X-irradiation or 200kGy for heavy-ion bombardment. The estimation of the radiation chemical yields revealed G-values of about 10 -7 molJ -1 and were typically smaller for irradiation with charged particles than those for X-rays. After heavy-ion bombardment the G-values first increased with increasing LET and decreased for very heavy ions. Conclusions : The yields for base release from both purine and pyrimidine nucleotides are comparable in magnitude. The 5,6-dihydroadduct from TMP is a major radiation induced product with larger yields than found for base release after X-irradiation and comparable yields after heavy-ion bombardment. The LET dependence of the G-values for base release in nucleotides is similar and resembles the double strand break formation in DNA. The observed similarity in the LET dependence of the G-values might derive from an inhomogeneous distribution of energy deposition resulting in 'clustered damage'.     

Repair of DNA strand breaks at hyperthermic temperatures in Chinese hamster ovary cells.

The repair of DNA double-strand breaks was measured by pH 7.2 filter elution in cells incubated at 25-45 degrees C either before or after X-irradiation. Exposure to 45 degrees C for 15 minutes immediately prior to X-irradiation significantly increased both the half-time for DNA double-strand break closure and the number of DNA double-strand breaks remaining in nuclear DNA 180 minutes after irradiation. Exposure to temperatures between 41 and 45 degrees C immediately after X-irradiation accelerated DNA double-strand break closure and resulted in no increase in the number of DNA double-strand breaks remaining in the cell's genome 180 minutes after irradiation. The results indicate either that the radiosensitization produced by the administration of hyperthermic temperatures before and after irradiation result from two characteristically different molecular mechanisms, or that neither the rate of DNA strand break closure nor the number of DNA strand breaks remaining in nuclear DNA after irradiation accurately predict hyperthermic radiosensitization. These conclusions assume that no DNA strand breaks are below the resolution of this DNA damage assay and that a comparison between cytotoxicity and DNA repair after exposure to high radiation doses is valid.     

Structural and functional alterations in the rat lung following whole thoracic irradiation with moderate doses: injury and recovery

PURPOSE: To characterize structural and functional injuries following a single dose of whole-thorax irradiation that might be survivable after a nuclear attack/accident. METHODS: Rats were exposed to 5 or 10 Gy of X-rays to the whole thorax with other organs shielded. Non-invasive measurements of breathing rate and arterial oxygen saturation, and invasive evaluations of bronchoalveolar lavage fluid, (for total protein, Clara cell secretory protein), vascular reactivity and histology were conducted for at least 6 time points up to 52 weeks after irradiation. RESULTS: Irradiation with 10 Gy resulted in increased breathing rate, a reduction in oxygen saturation, an increase in bronchoalveolar lavage fluid protein and attenuation of vascular reactivity between 4-12 weeks after irradiation. These changes were not observed with the lower dose of 5 Gy. Histological examination revealed perivascular edema at 4-8 weeks after exposure to both doses, and mild fibrosis beyond 20 weeks after 10 Gy. CONCLUSIONS: Single-dose exposure of rat thorax to 10 but not 5 Gy X-irradiation resulted in a decrease in oxygen uptake and vasoreactivity and an increase in respiratory rate, which paralleled early pulmonary vascular pathology. Vascular edema resolved and was replaced by mild fibrosis beyond 20 weeks after exposure, while lung function recovered.     

Operation and methodology of an alanine ion-selective electrode dosimetric system: II. Dose-response

Dissolution of irradiated α-alanine in an aqueous solution results in the liberation and formation of ammonia, which can be quantified for dosimetric purposes by means of an ion-selective gas sensing electrode. The operational principles, readout procedure as well as data analysis were presented and discussed in a preceding paper. Here the dose-response (0.5–1000 kGy) by direct concentration measurements is evaluated. A total ammonia yield decreasing from 6.5 (±0.3) × 10⁻⁷ mol J⁻¹ (i.e. 6.3 (±0.3) molecules per 100 eV) at 1 kGy, to 2.9 (±0.1) × 10⁻⁷ mol J⁻¹ (2.8 (±0.1) per 100 eV) at 1000 kGy is observed. No significant fading at ambient temperature is found during the first 2 months, even at 1000 kGy. Irradiation temperature coefficients of +0.34 to +0.47%°C⁻¹ were measured, dependent on dose level, The precision in concentration measurement for one calibration is within 1%; long-term precision varies from 2 to 4% (95% conf. lim.) for doses above 1 kGy.     

A comparison of the performance characteristics of four film dosimeters in a 10-MeV electron beam.

Performance characteristics of four routine film dosimeters (CTA, B-3, PVC and LiF (Sunna)) in a 10-MeV electron beam were investigated. Dose response curves for the range 5-40kGy are presented. The dose response curve is linear for the CTA film, supralinear for the LiF (Sunna) film and sublinear for the B-3 and PVC films. The low sensitivity of the CTA film to ionizing radiation restricts its use to high doses, while the supralinear response curve of the LiF (Sunna) dosimeter allows this film to be used only in measurements of low doses. The optical absorption temperature coefficients for the CTA, B-3 and LiF (Sunna) films were found to be at the level of +/-0.1%/( composite function)C. The temperature coefficient for the PVC film decreased from +0.35%/( composite function)C immediately after irradiation to +0.04%/( composite function)C three months later. Because of the significant time dependence of the PVC film signal, a careful standardization of the heating regimen and of the time between the irradiations and measurements is necessary.     

Disappearance of stress-induced hyperthermia following a low dose of X-irradiation: involvement of the vomeronasal system in the modulation of the radiation-induced effects

When the rectal temperatures of group-housed mice are measured sequentially, the temperature of the last mouse to be measured is higher than that of the first mouse. The hyperthermia effect observed in the last animal to be measured forms the basis of an experimental paradigm for studying the neurobiology of anticipatory anxiety. Stress-induced hyperthermia (SIH) was calculated as the difference (delta T) between the basal temperature (the averages of the first three mice) and the final temperature (the averages of the last three mice) when the temperatures of the 15 mice were measured sequentially, with a 2 min interval between each temperature measurement. The hyperthermia observed in the last animals measured was abolished by prior treatment with X-irradiation at the relatively low dose of 5-15 cGy. Prevention of the SIH response could be found when the irradiation was confined to the head region only, suggesting the importance of the brain in the radiation-induced effect. Relatively higher doses of 25 or 35 cGy failed to reduce the hyperthermia stress effect. Furthermore, the effect of X-irradiation was not observed following olfactory bulbectomy or resection of the vomeronasal tract. These results indicate that the disappearance of SIH response may only be found following irradiation at low dose levels. Furthermore, the results implicate the olfactory system in the radiation-induced anti-stress effect.     

Dose and dose-splitting effects of X-rays on lung tumour induction in mice

This paper reports lung-tumour induction 12 months after single or split doses of X-rays in C3H/He male mice. The early proliferative response of lung cells after doses which induced lung tumours was also examined after single X-irradiation. The lung-tumour incidence tended to increase with increasing dose after a single irradiation and peaked at 5 Gy. At more than 10 Gy it decreased sharply to the control level. The mean tumour diameters tended to increase with doses up to 7.5 Gy and then decreased beyond 10 Gy. These results suggested that suppression of tumour growth reduced the tumour incidence at doses of over 10 Gy. The lung-tumour incidence decreased with increasing intervals between two equal doses of 2.5 or 5 Gy. The decrease was thought to be caused by the repair of the tumorigenic injury. However, the tumour incidence after two 2.5 Gy irradiations at 1 day intervals or two 5 Gy irradiations at 6 h intervals was higher than that observed after a single dose. This phenomenon was regarded as a progression of the tumorigenic injury. The labelling indices of the lung cells, determined using tritiated thymidine after a single irradiation, were higher than those of non-irradiated control cells. This response was delayed as the dose increased. The responses versus days after irradiation could be classified into three patterns on the basis of their peaks. The possibility that the larger delay after higher doses had some relation to the reduction of target cells for tumour incidence is suggested.     

In utero haemopoietic sensitivity to alpha, beta or X-irradiation in CBA/H mice.

PURPOSE: To assess in utero sensitivity to x-rays, alpha-emissions from plutonium-239 and beta-emissions from tritium in terms of induction of chromosomal aberrations in bone marrow cells. MATERIALS AND METHODS: CBA/H mice were exposed to a single dose of X-rays (0.5Gy) on either day 7 or day 14 of pregnancy or given (239)Pu (100 kBq kg(-1)) by intraperitoneal injection on either day 6 or day 13. Tritium was administered to mice throughout pregnancy as either tritiated water, ad libitum in drinking water (total intake averaged 130 MBq), or as homogenized tritiated cress, administered by gastric intubation (total 60 MBq). Irradiated and unexposed control mice and their offspring were sacrificed at 2-8 weeks after birth. Direct metaphase preparations from femoral bone marrow cells from mothers and offspring were used for G-band analysis. RESULTS: The incidence of stable aberrations was significantly and similarly increased in neonatal and maternal marrow samples after exposure to X-rays, (239)Pu or (3)H. The estimated average bone absorbed doses from (239)Pu in pregnant females were similar to the X-ray dose of 0.5 Gy, suggesting a low RBE for alpha-irradiation in adults. The similar levels of damage observed in neonates after X-irradiation and 239Pu exposure are indicative of greater in utero sensitivity to alpha-irradiation since the overall estimated in utero alpha-particle doses to haemopoietic tissue were much lower. In utero doses from (3)H and corresponding maternal doses were around 0.5Gy, showing no evidence of greater in utero sensitivity, no significant difference between the effects of the two forms of tritium, and were consistent with an RBE value of 1-2. CONCLUSIONS: Comparison of stable aberration yields in haemopoietic cells suggests a greater sensitivity to alpha-particles from (239)Pu than X-rays or beta-particles from (3)H for irradiation in utero but a low RBE value in adults.     

Radiation in the treatment of high grade malignant gliomas in Queensland.

Two hundred and seventy eight patients with histologically proven grade 3 or grade 4 astrocytomas were referred to the Queensland Radium Institute for consideration of radiotherapy between January 1980 and December 1987. The role of radiation in the management of these tumours was examined with respect to the effects of field size, dose and age. It was found that field size did not have a significant effect on survival; in particular whole brain irradiation for patients with grade 4 tumours was not a significant advantage. The doses used at the Queensland Radium Institute produce similar survivals to those used in other centres. The effect of age was significant. For grade 3 tumours there was a survival advantage to those under 50 years receiving radiation, but not to those above that age. For grade 4 tumours, the survival advantage was for those under 60 years, but those over 60 years did seem to get some benefit although the difference did not reach significance. It is suggested that, as the tumour is generally incurable, these patients may be better served by a short simple palliative course of radiation.