Independent 6D quality assurance of stereotactic radiotherapy repositioning on linacs.

PURPOSE: A high level of accuracy while positioning the patient is mandatory for frameless stereotactic radiotherapy (SRT), as large doses in multiple fractions can be delivered near organs at risk. The objective of this study is to propose an end-to-end quality assurance method to verify that submillimetre alignment can be achieved with stereotactic conventional linacs. METHODS: We used a TrueBeam® linear accelerator equipped with a 6DOF robotic couch. The "ISO Cube" phantom was used with a homemade stand designed to generate known translational and rotational offsets. A reference CT scan was performed with straight alignment of the phantom. The procedure introduced 1.6° angular offset for the couch pitch and roll, at various gantry angles. The couch base was also moved between 0° and 270°. We compared the results with the daily machine performance check tests (MPC, Varian). RESULTS: The mean isocentre size, MV and kV imager offsets were found to agree to within 0.1mm, 0.1mm and 0.3mm respectively, and were in close agreement between the methods. For a total four months data collection period, the mean deviation between requested and measured 6DOF couch shifts was 0.6mm and 0.2°. Errors on field size were smaller than 1mm for 97.7% of the 324 data points. CONCLUSION: Results demonstrate that the linac equipped with a 6DOF robotic positioner and CBCT imaging satisfies requirements for SRT. Our methodology, based on a modified Winston-Lutz quality control, allowed us to quantitatively assess end-to-end accuracy of a linac in order to safely deliver SRT.

[Ocular manifestations in patients affected by Morquio syndrome (MPS IV)]. / Manifestations ophtalmologiques de la maladie de Morquio.

PURPOSE: The purpose of this study was to investigate the ocular manifestations in patients suffering from Morquio syndrome. METHODS: We reviewed the hospital records of 20 patients who underwent ophthalmological follow-up at hôpital Femme-Mère-Enfant, Bron, France, between December 2008 and February 2010. RESULTS: This retrospective study included 20 patients: 12 males and eight females. The mean age at the beginning of the retrospective study was 23 years. The most common ocular manifestations encountered, in order of frequency, were: corneal opacification (13/20), astigmatism (12/20) and the presence of punctate cataract (6/20). Visual acuity after optical correction was over 7/10 on average. The average best corrected visual acuity was estimated to be over 0.7. CONCLUSION: Although ocular complications in Morquio syndrome appeared to be associated with relatively well preserved visual acuity, ophthalmological follow-up is recommended to identify potentially curable complications such as astigmatism or lens opacities.

[Dosimetric impact of the 2D motion of a platform simulating breathing during a dynamic mode treatment]. / Impact dosimétrique du mouvement 2D d'une plateforme simulant la respiration lors d'un traitement en mode dynamique.

Breathing-adapted techniques in external radiotherapy lead to the improvement of the taken into account of the tumour motion during the patient treatment. Indeed, this motion involves dosimetric uncertainties, in particular during a dynamic treatment (intensity-modulated radiation therapy, dynamic wedge...). As tumoral movement is complex and is carried out in various directions of space, a dynamic platform moving in one or two plans was conceived. This article approaches the technical aspects of design and functioning of this prototype. A study of the dosimetric effects of the respiratory movement on one and two plans during a dynamic treatment without gating will be presented. Films were irradiated while varying the rates with wedged fields at various speeds. The penumbra of beams were compared with the static case and appeared twice broader in the majority of the cases. The results highlighted the contributions of the longitudinal and the axial components of the motion on the form of the dose distribution. These results were completed with gamma index measurements to determine an internal margin. Moreover, this platform proves to be a promising tool for breathing-adapted treatment, in particularly to test the synchronisation of RPM system in fluoroscopic mode in board imaging system.

[Dosimetric influence of hip prosthesis during radiotherapeutic treatement]. / Impact dosimétrique des prothèses de hanche lors d'un traitement radiothérapeutique.

As the population become aged, many patients with hip prosthesis are treated for a pelvic cancer. The recommended ballistic must avoid to pass in the prosthesis, but sometimes it is inevitable. So it is essential to quantify with accuracy the dose modifications linked to the presence of metallic implant. The aim of this study is to analyze by Monte Carlo method these modifications in simple and complex models (anthropomorphic phantom) which take into account the geometry and the composition of the prosthesis and its coatings. Then, this methodology was used to study the behaviour of a treatment planning system in theses extreme conditions.

The inclusion of fluoxetine into gamma-cyclodextrin increases its bioavailability: behavioral, electrophysiological and pharmacokinetic studies.

The inclusion of a drug into cyclodextrin generally results in the modification of its physical and chemical properties and sometimes can increase its oral bioavailability. The aim of this study was to compare the effects of the fluoxetine HCl/gamma-cyclodextrin complex to that of traditional fluoxetine HCl. In the forced swimming test in mice, fluoxetine HCl/gamma-cyclodextrin was more effective than fluoxetine HCl, the ED30s being, respectively, 9.5 and 16.9 mg/kg PO. Both compounds (10 mg/kg PO) were able to reduce the firing rate of dorsal raphe neurons in the rat. However, between-groups comparisons showed no significant differences between fluoxetine HCl treated animals and the vehicle group, while fluoxetine HCl/gamma-cyclodextrin appeared significantly more effective than vehicle from minute 25 of the measurement period. In healthy volunteers, the relative oral bioavailability, calculated as the ratio AUC 0-infinity fluoxetine HCl/gamma-cyclodextrin on AUC 0-infinity fluoxetine HCl (20 mg PO), was equal to 249.9%. The three experiments taken together suggest that the complexation of fluoxetine HCl into gamma-cyclodextrin increases its pharmacological efficacy in animals, this effect being related to an enhancement of its oral bioavailability as demonstrated in human healthy subjects.

[Persistent hyperplastic primary vitreous syndrome in a girl with Aicardi syndrome]. / Syndrome de persistance et d'hyperplasie du vitré primitif chez une fille présentant un syndrome d'Aicardi.

Aicardi syndrome is characterized by infantile spasms, agenesis of the corpus callosum and chorioretinal lacunae. This disorder affects mostly females with early embryonic lethality in males. We present a case of persistent hyperplastic primary vitreous (PHPV) in association with Aicardi syndrome in a 2-year-old girl.

Influence of food on tianeptine and its main metabolite kinetics.

The influence of a test meal on the absorption and disposition of tianeptine (Stablon), a new antidepressant, was investigated in 12 healthy subjects in a two-way, randomized, open cross-over study. Single 12.5-mg oral doses of tianeptine were administered following a night of fasting or immediately after a standardized breakfast. When subjects received tianeptine under fasting conditions the lag time before absorption onset, and the time of the maximum plasma concentration were 0.55 +/- 0.26 hours and 1.29 +/- 0.29 hours, respectively. The maximum plasma concentration was 322 +/- 44 ng/mL, and the total area under the curve 994 +/- 248 ng/hr/mL. When tianeptine was given at the end of the meal, several significant changes were found for tianeptine kinetic parameters; the lag time increased by 0.3 hour and the maximum plasma concentration was lowered (decreased by 25%) and occurred later (tmax increased by 0.5 hour). However, no significant change was found in the area under the plasma concentration-time curve. The trend and extent of changes in the MC5 metabolite parameters were similar to those observed for the parent drug. Absorption of tianeptine is slightly delayed and slowed down without modification of its extent when tianeptine is given at the end of a meal. These slight changes are not clinically relevant for an antidepressant administered three times a day. Despite the changes observed, tianeptine may be given at meal times to improve compliance with treatment.

Pharmacokinetics of oral dipyridamole (Persantine) and its effect on platelet adenosine uptake in man.

Two preparations of dipyridamole have been studied by oral administration to 11 normal volunteers. The plasma levels of dipyridamole and its glucuronide were determined simultaneously by high performance liquid chromatography. The instant form (I.F., 100 mg) was administered four times daily and the slow release preparation (SRP, 200 mg) twice daily, for 3 days. Multiple blood samples were collected on Days 1-4 to provide plasma for assay, and simultaneously, platelet rich plasma was prepared for ex vivo study of the effect of dipyridamole on platelet uptake of adenosine. The pharmacokinetics of absorption and distribution of dipyridamole were described using a two compartment model with lag time and prolonged absorption. Strong inhibition of the platelet adenosine uptake was observed at therapeutic plasma levels. The inhibition of platelet adenosine uptake may be related to some of the pharmacological properties of dipyridamole.