[Which photon energy for intensity-modulated radiotherapy and volumetric-modulated arctherapy in 2019?] / Quelle énergie de photons pour la modulation d'intensité et l'arcthérapie volumétrique en 2019 ?

For more than a decade, the majority of radiation oncology centres have been delivering intensity-modulated radiotherapy (then volumetric-modulated arctherapy) with 6 MV photons as their standard of care. This « dogma ¼ had been supported by the usual absence of dosimetric advantages with high-energy photons (15 to 18 MV or more), at least for the planning target volume and the dose received by the adjacent organs at risk, and by the neutron component as soon as the photon energy exceeds 10 MV. Recent data could question such a dogma. First, in 2019, one cannot avoid taking into account the integral dose, delivered outside the treated volume. Actually, most available data show that integral dose is higher with low energy photons (as 6 MV) than with higher energies. Moreover, recent studies have shown that the neutron component at high energies may have been overestimated in the past; in fact, the neutron dose appears to be lower, and sometimes much lower, than the dose we accept for imaging. Finally, a few cohort studies did not show any increase in second cancers incidence after high-energy photon radiotherapy. In such a context, the American Association of Physicists in Medicine (AAPM) TG 158 document, released a few months ago, clearly states that there is a trade-off between high- and low-energy treatments. High-energy therapy is associated with neutron production, while low-energy therapy results in higher stray photon dose. According to the AAPM, « the optimal energy is likely an intermediate such as 10 MV ¼.

Comparative dose levels between CT-scanner and slot-scanning device (EOS system) in pregnant women pelvimetry.

PURPOSE: To estimate fetal absorbed doses for pregnant women pelvimetry, a comparative study between EOS imaging system and low-dose spiral CT-scanner was carried out. For this purpose three different studies were investigated: in vivo, in vitro and Monte Carlo calculations. METHODS: In vivo dosimetry was performed, using OSL NanoDot dosimeters, to determine the dose to the skin of twenty pregnant women. In vitro studies were established by using a cubic phantom of water, in order to estimate the out of field doses. In the latter study, OSLDs were placed at depths corresponding to the lowest, average and highest position of the uterus. Monte Carlo calculations of effective doses to high radio-sensitive organs were established, using PCXMC and CTExpo software suites for EOS imaging system and CT-scanner, respectively. RESULTS: The EOS imaging system reduces radiation exposure 4 to 8 times compared to the CT-scanner. The entrance skin doses were 74% (p-values <0.01) higher with the CT-scanner than with the EOS system. In the out of field region, the measured doses of the EOS system were reduced by 80% (p-values <0.02). Monte Carlo calculations confirmed that effective doses to organs are less accentuated for EOS than for CT pelvimetry. CONCLUSIONS: The EOS system is less irradiating than the CT exam. The out-of-field dose which is significant, is lower in the EOS than in the CT-scanner and could be reduced even further by optimizing the time used for image acquisition.

Degenerative pleomorphic adenoma of the nasal cavity.

INTRODUCTION: Malignant salivary gland tumor usually involves the parotid gland. Although unusual locations have been reported for such tumors, we here report an extremely rare case of nasal location in a salivary gland adenoma with malignant transformation. OBSERVATION: A 65-year-old man with diabetes and hypertension presented with left nasosinal tumefaction causing nasal obstruction with slow evolution and recent onset of epistaxis and slight telecanthus. CT, MRI and nasosinal bone biopsy were performed. Treatment was by surgical exeresis on an external approach. CONCLUSION: Malignant transformation of a pleomorphic adenoma with nasal location is extremely rare and little described in the literature. Imaging found strong signs of malignancy, confirmed on histology. Surgical exeresis was the only effective treatment option.

[Postvaccination myelitis. Aspect and course followed by MRI]. / Myélite post-vaccinale. Aspect et évolution en IRM.

We report the assessment by MRI of a case of radiculomyelitis after vaccination against tetanus-poliomyelitis. In the acute stage the appearance was an isolated myelitis of the conus medullaris with contrast enhancement. The upper thoracic cord presented central areas of high signal intensity on T2 weighted images. Rapid clinical recovery was correlated with resolution of abnormal enhancement. Follow-up MR at 5 months showed persistence of slight T2 prolongation in the conus medullaris and syringohydromyela of the thoracic cord. A single lesion of the spinal cord is a rare presentation of acute disseminated encephalomyelitis, the course of such lesions, to date not previously displayed by MR, is unknown. Proper diagnosis should help prevent administration of further vaccine doses.

Role of 3D Display MR Angiography in the Study of Intracranial Aneurysms.

SUMMARY: This paper determines the usefulness of threedimensional (3D) phase-contrast (PC) magnetic resonance (MR) angiography with 3D display in characterizing large intracranial saccular aneurysms. Eight patients referred for non invasive confirmation of unruptured aneurysm (n=9) detected by conventional CT and/or MR imaging were studied by 3D PC (VENC of 20 cm/s, 3 axes) in axial acquisition localised on the circle of Willis using a 0.5 T unit (Vectra, GE). We used 3D display images to assess the feasibility of selective treatment. Results were correlated with catheter angiograms in 3 patients. In two thirds of the cases, location and size of the orifice, size of the sac, and clarification of parent artery were clearly provided allowing prediction of therapeutic management. In the remaining cases results remained doubful because of lack of spatial resolution. The benefit of the method was coupled with the clinical status of the patients to influence the final decision. 3D PC MR angiography with 3D display has emerged as an improvement in predicting therapeutic management, and is especially useful in large unruptured aneurysms in elderly or ill patients.

[Value and limits of fine needle aspiration biopsy in Hodgkin disease. Usefulness in developing countries]. / Intérêt et limites de l'adénogramme dans le diagnostic de la maladie de Hodgkin. Utilité dans les pays en voie de développement.

The efficiency of a diagnostic procedure is evaluated by the percentage of subjects accurately identified, as either suffering from the disease looked for (true positive, TP) or not (true negative, TN). Sensitivity and specificity are the percentage of TP or TN, respectively, accurately identified. Cytological diagnosis of Hodgkin's disease (HD) was evaluated; smears were made from fine-needle aspiration. One hundred and nine smears were examined independently by two cytologists; adenopathies were benign in 43 cases (tuberculosis 25, non-specific reactive hyperplasia 16, sarcoidosis 2) and malignant in 66 cases (HD 36, Non-Hodgkin's lymphoma 22, malignant histiocytosis 2, metastasis 5, blast crisis of chronic myeloid leukemia 1). Benign and malignant diseases were diagnosed by lymph node biopsy; diagnosis of HD was made in 36 TP patients; the 73 others are TN. Sensitivity, specificity and efficiency are: 75, 90.4, 85.3, respectively for one observer; 77.7, 91.8, 87.1 respectively for the other: 63.8, 90.4, 81.6 respectively when diagnosis was the same for the two cytologists. Fine-needle aspiration permits the diagnosis of HD in eight out of 10 cases; it is useful when biopsy is difficult or too expensive, as is often the case in developing countries.