Multichannel dosemeter and Al2O3:C optically stimulated luminescence fibre sensors for use in radiation therapy: evaluation with electron beams.

This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve.

Monte Carlo simulation of a medical linear accelerator for radiotherapy use.

A Monte Carlo code MCNPX (Monte Carlo N-particle) was used to model a 25 MV photon beam from a PRIMUS (KD2-Siemens) medical linear electron accelerator at the Centre Antoine Lacassagne in Nice. The entire geometry including the accelerator head and the water phantom was simulated to calculate the dose profile and the relative depth-dose distribution. The measurements were done using an ionisation chamber in water for different square field ranges. The first results show that the mean electron beam energy is not 19 MeV as mentioned by Siemens. The adjustment between the Monte Carlo calculated and measured data is obtained when the mean electron beam energy is approximately 15 MeV. These encouraging results will permit to check calculation data given by the treatment planning system, especially for small fields in high gradient heterogeneous zones, typical for intensity modulated radiation therapy technique.

Long-lasting recovery of locomotor function in chronic spinal rat following chronic combined pharmacological stimulation of serotonergic receptors with 8-OHDPAT and quipazine.

In chronic spinal rats, long-term stimulation of 5-HT receptors with quipazine or 8-OHDPAT by means of daily injection, promotes robust locomotor recovery. The question of a possible potentiation between treatments when applied together was addressed. Daily injections of both 8-OHDPAT and quipazine, were performed for a month in spinal animals. Animals were placed on a treadmill and the bipedal hindlimb locomotion was tested. Motor performances (behavioural test) and locomotor parameters (EMG and kinematic) were analysed weekly during the treatment. Furthermore, the locomotor performances were evaluated during two supplemental months following the end of the treatment. Our results suggest that association of both agonists induced long-lasting positive effects on locomotor function. Motor performances were significantly better after combined injection of both drugs than when the agonists were used separately. But, the most significant and new result is that the locomotor scores did not decrease during the weeks that followed the end of the treatment. These results suggests a long-lasting and 5-HT-dependent reorganisation of spinal networks.

Voltage-dependent block of NMDA responses by 5-HT agonists in ventral spinal cord neurones.

1. Modulation by 5-hydroxytryptamine receptor agonists of the NMDA responses of ventral spinal cord neurones was studied by use of the whole-cell patch-clamp technique. 2. In a Mg-free solution containing tetrodotoxin and glycine, 5-hydroxytryptamine (5-HT, 10-100 microM) reduced the NMDA response, the block increasing with hyperpolarization. Kainate responses were little affected. 3. Some classical agonists of 5-HT receptors induced similar blocking effects. At 10 microM, both a selective agonist of 5-HT2 receptors, (+/-)-2,5-dimethoxy-4 iodo amphetamine (DOI), and a selective agonist of some 5-HT1 receptors, (+/-)-8-hydroxy-2(n-dipropyl amino) tetralin (8-OH-DPAT), induced pronounced blocking effects, of 48% and 33% respectively at -100 mV, whereas another 5-HT1 agonist, 5-carboxamidotryptamine (5-CT) was ineffective. At 100 microM, 5-methoxytryptamine (5-MeOT) induced a complete block of the NMDA responses recorded at -100 mV. The order of potency was: 5-MeOT congruent to DOI > 8-OH-DPAT > 5-HT > 5-CT. 4. Neither spiperone nor ketanserin (1 microM) prevented the blocking effect of 5-HT or DOI. 5. Prolonged preincubations with 5-HT did not block the response if NMDA was applied without 5-HT. When 5-HT agonists were applied both by preincubation and with NMDA, the degree of block increased during the NMDA application. 6. Lowering the NMDA concentration (from 100 to 20 microM) slightly decreased the blocking effect of 5-MeOT. 7. External Mg2+ ions (1 mM) also reduced the blocking effects of 5-HT and 5-MeOT. 8. The blocking effects described appear to be independent of classical 5-HT receptors. Their voltage-dependence suggests a mechanism of open channel block consistent with all the results obtained.

"PCL" a new automatic fast reader suitable for in vivo dosimetry.

The authors present a new automatic TLD reader specially designed for medical dosimetric applications, which allow considerable time-saving. The "PCL" reader is based on an isothermal heating kinetics and can be used with TL material of any nature and any shape (powder, microrods, pellets). Doses from 1 microGy to 10 Gy can be measured, or higher doses by interposing an optical absorber in front of the PM. The readout system is controlled by an IBM compatible personal computer. Results can be printed under the form defined by the users and then can be straightly stored in a patient sheet or an experience book. Tests performed with LiF chips TLD 100 and 700 (HARSHAW), Li2B4O7:Mn discs LiB (ALNOR), LiF powder PTL 717 (DESMARQUET) and Li2B4O7:Cu powder (CEN-FAR) are presented. They show a good reproducibility and interesting dosimetric properties.

In vitro, proctolin and serotonin induced modulations of the abdominal motor system activities in crayfish.

An in vitro thoraco-abdominal preparation of the crayfish (Procambarus clarkii) ventral nerve cord was used to study the sites of action and the effects of proctolin and serotonin on the nervous activities of the two abdominal motor systems, namely the swimmeret and the abdominal positioning systems. In this preparation spontaneous motor activity was recorded corresponding to continuous rhythmic bursts in the swimmeret motor nerves and tonic discharge of motoneurons in both abdominal extensor and flexor motor nerves. Proctolin applied on the abdominal ganglia elicited bursts of spikes in the flexor motor nerve which were able to disturb and even stop the swimmeret activity. Increasing concentrations of serotonin applied on the thoracic ganglia were able, first, to increase the period durations of the swimmeret bursting activity and, second, to stop it. In this last condition, continuous swimmeret activity resumed by application of proctolin on the abdominal ganglia although period durations stayed slightly longer than in control. The actions of serotonin and proctolin on the two abdominal motor systems were discussed in terms of modulations and interactions between central neuronal networks and behaviors.

Dopamine and motor activity in the lobster Homarus gammarus.

Motor activity similar to agonistic behaviour is obtained after dopamine (DA) injection in lobster. Specially vigorous swimmeret beatings are observed and can be compared to the 'in vitro' motor activity elicited by DA superfusion of the isolated abdominal nervous system. DA-immunoreactive neurons stained by monoclonal antibodies in abdominal ganglia may be involved in swimmeret activation during the agonistic behavior.

Calculation of perturbation correction factors for some reference dosimeters in high-energy photon beams with the Monte Carlo code PENELOPE.

The BNM-LNHB (formerly BNM-LPRI, the French national standard laboratory for ionizing radiation) is equipped with a SATURNE 43 linear accelerator (GE Medical Systems) dedicated to establishing national references of absorbed dose to water for high-energy photon and electron beams. These standards are derived from a dose measurement with a graphite calorimeter and a transfer procedure to water using Fricke dosimeters. This method has already been used to obtain the reference of absorbed dose to water for cobalt-60 beams. The correction factors rising from the perturbations generated by the dosimeters were determined by Monte Carlo calculations. To meet these applications, the Monte Carlo code PENELOPE was used and user codes were specially developed. The first step consisted of simulating the electron and photon showers produced by primary electrons within the accelerator head to determine the characteristics of the resulting photon beams and absorbed dose distributions in a water phantom. These preliminary computations were described in a previous paper. The second step, described in this paper, deals with the calculation of the perturbation correction factors of the graphite calorimeter and of Fricke dosimeters. To point out possible systematic biases, these correction factors were calculated with another Monte Carlo code, EGS4, widely used for years in the field of dose metrology applications. Comparison of the results showed no significant bias. When they were possible, experimental verifications confirmed the calculated values.

Obstruction of aortocoronary bypass due to blunt chest trauma.

We report the first case in the literature of acute myocardial infarction due to blunt chest trauma in a patient with saphenous vein aortocoronary bypass to the anterior descending coronary artery. Angiograms demonstrated two stumps - aortic and coronary - suggesting that the primary obstruction was at the graft level with subsequent anterior descending occlusion. A large left ventricular aneurysm developed. As his clinical situation was stable, early aneurysmectomy was not done, and the patient is asymptomatic 15 months after the trauma.

[Penetrating aortic ulcer: clinical and angiographic characteristics]. / Ulcera penetrante de aorta: características clínicas y angiográficas.

BACKGROUND: "Penetrating aortic ulcer", an atherosclerotic lesion with ulceration that penetrates the internal elastic lamina and allows haematoma formation within the aortic wall, is rarely considered in the differential diagnosis of patients with sudden onset of severe chest or back pain. It has been suggested that it is a pathologic process that involves elderly hypertensive patients with severe atherosclerosis and rarely has been observed in the ascending aorta. METHODS: To determine the characteristics of this process, 11 clinical, 2 hemodynamic, 3 angiographic and 4 surgical variables were compared between 10 consecutive patients with penetrating aortic ulcers and 20 matched patients with classic acute aortic dissection. RESULTS: Clinical and hemodynamic variables were similar in both compared groups. In the group of patients with penetrating ulcer mean age was 58 +/- 6 years, previous hypertension was observed in 6 patients and the penetrating ulcer was located in the ascending aorta in 6 cases. In comparison to patients with aortic dissection, more angiographic projections were necessary to obtain the diagnosis in the group of patients with penetrating ulcer (2.4 +/- 0.8 vs 1.7 +/- 0.6; p < 0.05). In addition, the presence of angiographic aortic valve regurgitation was only observed in the group of patients with acute dissection (60% vs 0%; p < 0.001). Severe atherosclerosis was not present angiographically in any patient with penetrating ulcer. CONCLUSIONS: Penetrating aortic ulcer can also affect middle age patients without severe atherosclerosis and is frequently observed in the ascending aorta. Its form of presentation and clinical characteristics are similar to classic aortic dissection. The lack of angiographic confirmatory evidence of dissection with suggestive clinical history, should raise the possibility of penetrating aortic ulcer.

[The mechanism producing nausea during ventriculography performed with ioxaglate: the implications of a randomized study]. / Mecanismo de producción de las náuseas durante la ventriculografía realizada con ioxaglato: implicaciones de un estudio randomizado.

INTRODUCTION: The mechanism of ioxaglate-induced nausea has not been fully elucidated. Recent studies have demonstrated that serotonin is one of the principal neurotransmitters of emesis in humans. On the other hand, the greater capacity of ioxaglate to stimulate vomiting has been ascribed to its great ability to inhibit cholinesterase. METHODS: To determine if oral metoclopramide (a serotonin receptor-blocker) is effective in the prophylaxis of ioxaglate-induced nausea during left ventriculography, 637 of 711 consecutive eligible patients were included in a prospective study. Patients were randomized to receive, 60-90 minutes before the procedure, either diazepam 10 mg p.o. (control group [n = 315]) or diazepam 10 mg p.o. plus metoclopramide 10 mg p.o. (metoclopramide group [n = 322]). RESULTS: The two randomized groups were similar in relation to baseline clinical and hemodynamic characteristics. Nausea was documented in 103 patients (16.1%) with similar incidence in the two groups (control group: 16.8%, metoclopramide group: 15.5%; p = NS). Nausea duration was also similar (56 +/- 63 s vs 52 +/- 63 s; p = NS). When patients with and without nausea were compared, the following variables showed a significant difference between the two groups: male gender (86% vs 76%; p < 0.05), age (53 +/- 10 yrs vs 56 +/- 9 yrs; p < 0.05) and body surface area (1.84 +/- 0.2 m2 vs 1.78 +/- 0.1 m2; p < 0.01). Stepwise multiple regression analysis identified low age (p = 0.02) and male gender (p = 0.06) as independent predictors of nausea. The incidence of nausea was 24% in males < or = 45 yrs vs 9% in females > 45 yrs (p < 0.05). CONCLUSIONS: Prophylaxis with oral metoclopramide did not reduce the incidence of ioxaglate-induced nausea during left ventriculography. This data do not support a role of serotonin in the production of nausea by ioxaglate. Low age an male gender are independent predictors of nausea apparition during left ventriculography. A cholinergic mechanism is probably involved in the capacity of ioxaglate to stimulate vomiting.

[Left ventricular function and state of the coronary tree in patients with significant coronary lesions (author's transl)]. / Estado del árbol coronario y de la función ventricular izquierda en los pacientes con lesiones coronarias significativas.

The prognosis of patients with ischemic cardiopathy is mainly based upon the number of affected vesssels, the state of the distal coronary tree, and the left ventricular function. Coronary arteriographies and ventriculographies corresponding to 274 consecutive patients (January, 1975-October, 1978) with significant coronary lesions are reviewed. A singles vessel obstruction was registered in 36.5 percent of the patients; obstruction of two vessels was present in 28.5 percent, and of three vessels in 29.9 percent. The common left trunk was obstructed in 5.1 percent of the cases. The anterior descending coronary artery was affected in 78 percent of the patients, and the left coronary artery, circumflex, first marginal branch, and first diagonal branch showed narrowing in 62, 34, 36, and 26 percent, respectively. The distal tree of the above mentioned arteries was appropriate for coronary bypass operations in 51, 49, 50, 38, and 10 percent of the arteries, respectively. On the basis of coronary angiographic and ventriculographic criteria 117 patients (43 percent) were not candidates to coronary bypass surgery. The ejection fraction was less than 0.40 in 22 percent of the cases, and below to 0.30 in 12 percent (34 patients). The outstanding finding in the present series was the impairment of the distal coronary tree due to advanced atherosclerosis.

[Left ventricular aneurysm. Correlations with coronary arteriography (author's transl)]. / Aneurisma ventricular izquierdo. Correlación con la coronariografía.

Ventricular aneurysm is the most severe segmental disorder of ventricular function. A group of 45 patients with ventricular aneurysms have been evaluated, correlating a total of 80 aneurysmatic segments with cineventriculographic findings. Seventy-one percent of the patients had multiple lesions. Except for three patients with normal coronary blood supply and apical aneurysm there was a positive correlation between the remaining aneurysmatic segments and significant lesions in the corresponding arteries. As in the three cases with normal coronary arteries, associated spasm was suspected in other eight cases showing significant vessel stenosis of less than 75 percent of the lumen. Detection of ventricular aneurysm in the cineventriculographic examination is highly suggestive of severe arterial damage.

[Angiographic mitral regurgitation in patients with chronic ischemic cardiopathy. Coronarioangiographic and ventriculographic correlations (author's transl)]. / Insuficiencia mitral angiográfica en la cardiopatía isquémica crónica. Correlación con la coronariografía y ventriculografía.

Mitral regurgitation in patients with chronic ischemic cardiopathy may occur following dysfunction of the papillary muscles and left ventricular impairment. A total of 291 patients with significant coronary lesions and absence of associated cardiopathies are reviewed. Patients were divided into three groups: Group A, formed by 241 cases without mitral regurgitation; group B, including 42 patients with slight mitral regurgitation, and group C, formed by eight patients with moderate or severe mitral regurgitation. Significant differences between groups A and B in relation to the number of affected coronary arteries, inferior or anterolateral akinesia-dyskinesia, and left ventricular enlargement were observed. There were no significant differences between groups B and C, though all patients of the last group had two or three affected coronary arteries. Angiographic mitral regurgitation following chronic ischemic cardiopathy is uncommon, especially moderate or severe degrees of regurgitation. Mitral regurgitation is related to the number of affected coronary arteries, presence of inferior or anterolateral akinesia-dyskinesia, and enlargement of the left ventricle. Clinical signs of significant mitral regurgitation may suggest the existence of coronary lesions, at least in two vessels.

[Distribution of significant coronary lesions in patients with rheumatic valvular heart disease. Study of 300 consecutive cases (author's transl)]. / Distribución de las lesiones coronarias signifcativas en los pacietes con valvulopatía reumática. Estudio de 300 casos consecutivos.

Associated coronary atherosclerosis in patients with rheumatic valvular heart disease is an important finding under prognostic and therapeutic viewpoints. Selective coronary angiography was carried out in 300 patients with rheumatic valvular disease (157 cases with associated mitral and aortic lesions; 57 cases with aortic regkurgitation; 35 cases with aortic stenosis; 31 cases with mitral stenosis, and 20 cases with mitral regurgitation). Significant coronary atherosclerosis occurs in 11 percent of all patients. The distribution of the lesions was as follows: anterior descending artery (56 percent); right coronary artery (47 percent); circumflex artery (28 percent); marginal artery (22 percent); oblique branches (19 percent), and common left trunk (3 percent). Lesions in the common left trunk were only present in association with aortic regurgitation. Fourty-four percent of patients with significant atherosclerosis showed multiple lesions, and there was a distal coronary tree appropriated to coronary bypass in 78 percent of the cases. The distribution of significant coronary lesions in patients with rheumatic valvular heart disease is similar to that observed in patients with ischemic heart disease. The frequent finding, however, of a short common left trunk and/or a left coronary prevalence in patients with aortic lesions is stressed under diagnostic and therapeutic viewpoints.

[Coronary angiography and hemodynamic parameters in patients recovered from a myocardial infarction]. / Coronariografía y parámetros hemodinámicos en pacientes recuperados de un unfarto de miocardio.

The hemodynamic findings of a group of 112 patients with a prior history of myocardial infarction have been reviewed. The patients have been classified in three subgroups: anterior (48 cases), posterior (43 cases), and biventricular electrical infarction (21 cases). There was only one female in the 112 cases. There was a good correlation between the electrical region of infarction and ventricular asynergy localized to the same territory (76.65, and 90 %, respectively), as well as significant involvement of the corresponding coronary artery (89.88 and 100 %, respectively). A high percentage of patients with significant lesions of the coronary artery opposite the infarction was found (48 % in anterior necrosis, and 76 % in posterior lesions). In five cases the coronary vessels had no abnormalities. Ejection fraction and postangiography end diastolic pressure were the parameters of ventricular function most constantly altered. From this study it appears particularly relevant that there is a low incidence of women: there exists a good correlation between the infarct, the zone of asynergy, and the affected coronary; the number of affected coronaries increases with age; there are significant lesions in the opposite coronary, and there is a greater alteration of ventricular function in patients with biventricular infarction, followed by patients with anterior infarction.

[Myocardial ischemia caused by anomaly at the origin of the left coronary artery]. / Isquémia do miocárdio por anomalia na origem da artéria coronária esquerda.

The case of a 68 years old man admitted because of angina "de novo" and submitted to coronariography is reported. The rest ECG showed abnormalities of the ST-T suggesting myocardial ischemia. The coronariography showed: No significant atherosclerotic lesions. The left coronary artery had an anomalous origin; the left descending coronary artery originated from an independent ostium located at the right Valsalva sinus, the circumflex artery had its origin at the same ostium as the right coronary artery.

[Spontaneous multivessel coronary dissection as a cause of acute myocardial infarct--case report]]. / Dissecção coronária multivasos espontânea como causa de enfarte agudo do miocárdio--a propósito de um caso.

The authors describe a case reported in a young female with antecedents of aortic pathology and renovascular hypertension submitted to renal artery surgery admitted to emergency with an extensive acute myocardial infarction, treated with thrombolysis. After coronariography we identify, as etiological factor, a spontaneous coronary dissection involving the descending anterior coronary artery and circumflex coronary artery with no affect on the left main coronary artery. About this case, the authors make a brief review of the literature emphasizing the therapeutic options.

[Kinesitherapy for mucoviscidosis]. / Kinésithérapie dans la mucoviscidose.

Kinesitherapy is an important element in the therapeutic strategy for cystic fibrosis. The main objective is to clear the upper airways. The most effective and most widely used method is to accelerate expiratory air flow. Kinesitherapy should take into account the effect of bronchorrhoea on respiratory mechanics, re-train the ventilatory process, improve thoracomuscular mechanics, attempt to reduce dyspnoea and maintain functional capacity. Managed carefully from childhood to adulthood patients should not require ventilatory assistance. Patients and/or parents, in cooperation with the medical and para-medical team should become fully responsible for correct follow-up and effective treatment.

Evaluation of PENFAST--a fast Monte Carlo code for dose calculations in photon and electron radiotherapy treatment planning.

The aim of the present study is to demonstrate the potential of accelerated dose calculations, using the fast Monte Carlo (MC) code referred to as PENFAST, rather than the conventional MC code PENELOPE, without losing accuracy in the computed dose. For this purpose, experimental measurements of dose distributions in homogeneous and inhomogeneous phantoms were compared with simulated results using both PENELOPE and PENFAST. The simulations and experiments were performed using a Saturne 43 linac operated at 12 MV (photons), and at 18 MeV (electrons). Pre-calculated phase space files (PSFs) were used as input data to both the PENELOPE and PENFAST dose simulations. Since depth-dose and dose profile comparisons between simulations and measurements in water were found to be in good agreement (within +/-1% to 1 mm), the PSF calculation is considered to have been validated. In addition, measured dose distributions were compared to simulated results in a set of clinically relevant, inhomogeneous phantoms, consisting of lung and bone heterogeneities in a water tank. In general, the PENFAST results agree to within a 1% to 1 mm difference with those produced by PENELOPE, and to within a 2% to 2 mm difference with measured values. Our study thus provides a pre-clinical validation of the PENFAST code. It also demonstrates that PENFAST provides accurate results for both photon and electron beams, equivalent to those obtained with PENELOPE. CPU time comparisons between both MC codes show that PENFAST is generally about 9-21 times faster than PENELOPE.