Geant4 physics list comparison for the simulation of phase-contrast mammography (XPulse project).

PURPOSE: Breast cancer is the most frequent cancer in women. Early and accurate detection of the disease is a major factor in patient survival. To this end, phase-contrast imaging has gained significant interest in recent years. The aim of this work was to validate the physics models of a Geant4 mammography imaging simulation (in the context of the XPulse project) by comparing to EGSnrc results. METHODS: We used three Geant4 electromagnetic physics lists of the version 10.4 of the toolkit: Standard, Livermore and Penelope. We calculated energy distributions in homogeneous and inhomogeneous phantoms and breast doses in DICOM images. The simulations used photon beams of energies 20-100 keV. The Geant4 calculations were compared with EGSnrc/DOSXYZnrc simulations. RESULTS: We found a very good agreement between the Standard Electromagnetic option 4 and Livermore Physics Lists (within 1% for all beam energies). Larger differences were found between Standard Electromagnetic option 4 and Penelope Physics Lists (about 4%). The agreement of longitudinal energy distributions between Geant4 Standard Electromagnetic option 4 and EGSnrc was good in water and light biological materials, but important discrepancies were found in heavy elements. We confirmed with both codes that dose to the breast is minimal at beam energy around 60 keV. CONCLUSIONS: Overall, we found good agreement between the option 4 of the Standard Electromagnetic physics list and Livermore physics lists of Geant4, as well as EGSnrc for materials relevant to mammography screening. Further investigations are needed for the case of heavier materials.

Prenatal diagnosis of 18q-syndrome: a case of fetal mosaicism with a normal karyotype in chorionic villi.

We report a case of fetoplacental discrepancy with normal karyotype on chorionic villi and deletion of the long arm of chromosome 18 on amniotic fluid. Cytogenetic tests were repeated because of a short corpus callosum on ultrasound examination. This 18q-syndrome has been reported to be associated with poor neurodevelopmental outcome.

Prenatal and postnatal follow-up of a fetal interhemispheric arachnoid cyst with partial corpus callosum agenesis, asymmetric ventriculomegaly and localized polymicrogyria. Case report.

We report a case of a fetal interhemispheric arachnoid cyst associated with partial callosal agenesis and asymmetric ventriculomegaly. After second trimester ultrasound diagnosis and evaluation, magnetic resonance imaging (MRI) at 28 weeks showed polymicrogyria laterally to the cyst. The parents decided to continue the pregnancy. The diagnosis was confirmed after birth by transfontanellar ultrasound examination and MRI. In the neonatal period, the child was sleepy and showed axial hypotonia. At 1 month of age, he had a normal neurological examination. Cyst-peritoneal shunting was performed at 5 weeks of age because the cyst increased markedly in size, and shunt revision was required at 8 months of age. At 17 months, he had mild left-side hemiparesis but he could walk alone and had begun to speak. To date, the child never experienced seizures. We review other published cases and discuss the postnatal outcome of this rare association.

First-trimester ultrasound diagnosis in a recurrent case of Walker-Warburg syndrome.

We report on two siblings with Walker-Warburg syndrome (WWS) born to a consanguineous couple. In the index case, the second-trimester scan showed ventricular dilatation and we diagnosed WWS after observing retinal detachment at 26 weeks' gestation and lissencephaly by 32 weeks' gestation in addition to hypoplasia of the cerebellar vermis. The second case was first suspected at 12 weeks' gestation, when we observed a 2.8-mm nuchal translucency and an unusually large hindbrain vesicle. By 14 weeks' gestation, the lateral ventricles were clearly enlarged (12-13 mm), at 16 weeks' gestation the vitreous chamber appeared to be hyperechogenic, and by 17 weeks' gestation hydrocephalus was evident. The couple chose to continue the pregnancy, and during the third trimester lissencephaly, major hydrocephalus and polyhydramnios developed. Serial ultrasound examination should be offered to a family with a history of WWS and therefore a 1 in 4 risk of recurrence. In some cases, recurrence can be suspected as early as the first trimester, however the diagnosis cannot be excluded on the basis of normal ultrasound appearance until later in pregnancy.

[Megabladder. Microcolon. Prenatal ultrasonic diagnosis and a review of the literature. Apropos of a case]. / Mégavessie. Microcôlon. Diagnostic échographique anténatal et revue de la littérature. A propos d'un cas.

The condition of "megacystis-microcolon" is a very rare condition which can now be diagnosed ante-natally due to ultrasound. The presence of a megacystis (large bladder) with increased levels of amniotic fluid makes it possible to eliminate other ante-natal causes of dilatation of the bladder and in particular when it is found in a female fetus (as it is in 80% of cases). At birth, one finds, apart from the massive dilatation of the bladder with very little effect on the upper urinary tract, a microcolon with complete absence of peristalsis. This last abnormality always leads to a catastrophic short term result because treatment is quite ineffective. Many histological studies have been carried out and these sometimes differ from one another but it is possible to think that the condition is due to pathology of neurogenic origin in the muscle of the bladder and the aetiology of this is unknown. Finally, because there have been a few familial cases, there may be a genetic element in this illness that has such a poor prognosis.

[Thaumaturgical saints in phlebology in the Department of La Manche]. / A propos des Saints thaumaturges en phlébologie dans le Departement de La Manche.

We have just studied the system of the Saints' illnesses in the French Manche area. This worship is still alive, as proves the number of requested masses. Formerly the medical density was low, the means of intellectual awareness (newspapers, television, rapid transport) did not exist. Medicine was rudimentary and expensive, so much so that in the case of sickness a person appealed to the Saints. In 1977, all these reasons ceased to exist and nevertheless people still appeal to them with the same fervour. How to explain the intensity and persistency of this devotion? Of course the Saints illnesses are the heirs of a far gone tradition and are part of a deeply-rooted regional folklore, but they mainly express the eternal disarray of man facing sickness. The human spirit needs hope to remain balanced just as the body needs food. The sick man can find this spiritual food by placing himself under the auspices of the healing powers, particularly under the Saints of the catholic religion and notably Saint Veronica, during vascular afflictions.