Is single fraction the future of stereotactic body radiation therapy (SBRT)? A critical appraisal of the current literature.

Stereotactic Body Radiation Therapy (SBRT) is a standard of care for many localizations but the question of the optimal fractionation remains a matter of concern. If single fraction sessions are routinely used for intracranial targets, their utilization for mobile extracranial lesions is a source of debate and apprehension. Single session treatments improve patient comfort, provide a medico-economic benefit, and have proven useful in the context of the SARS-CoV 2 pandemic. However, both technical and radiobiological uncertainties remain. Experience from intracranial radiosurgery has shown that the size of the target, its proximity to organs at risk, tumor histology, and the volume of normal tissue irradiated are all determining factors in the choice of fractionation. The literature on the use of single fraction for extracranial sites is still scarce. Only primary and secondary pulmonary tumors have been evaluated in prospective randomized trials, allowing the integration of these fractionation schemes in daily practice, for highly selected cases and in trained teams. The level of evidence for the other organs is mainly based on dose escalation or retrospective trials and calls for caution, with further studies being needed before routine use in clinical practice.

Ion irradiation induced strain and structural changes in LiTaO3perovskite.

LiTaO3crystals irradiated with 3 MeV and 1.162 GeV Au ions were studied by single crystal x-ray diffraction and Raman scattering measurements. The maximum lattice strains after 3 MeV Au ion irradiation to a fluence of 1.2 × 1013 cm-2were 1.2% and 0.6% along thec- anda-/b-axes, respectively. Two effects were observed in 1.162 GeV Au ion irradiated samples: (i) the (0006) and (1120) Bragg peaks were split into doublets, which suggested a subtle structural change due to slight modification of chemical composition; and (ii) the pre-damaged 1.2% lattice strain along thec-axis was relaxed to 0.9% after subsequent irradiation with 1.162 GeV Au ions, while relaxation along thea- orb-axis was not obvious. A distinct change in the Raman spectrum of the 〈0001〉 oriented LiTaO3crystals was observed after 1.162 GeV Au ion irradiation, but no obvious change was observed in the 〈1120〉 oriented samples or in 3 MeV Au ion irradiated samples. Strain and structural changes in crystalline LiTaO3, with or without pre-existing defects, upon ion irradiation are delineated in its responding to inelastic ionization and elastic nuclear collisions.

[Apropos of a mediastinal teratoma invading the lung]. / A propos d'un cas de tératome médiastinal rompu dans le poumon.

Mediastinal mature teratomas are rare in children. Diagnosis is often made in the presence of a complication. We report a case of a mature mediastinal teratoma, complicated by its opening in the lung. The patient was a four-year-eight-month-old girl. She was admitted for fever, cough and dyspnea. The chest radiography showed a large mediastinal mass with calcifications. The CT scans and MRI aided in establishing the diagnosis. Biological tests (alpha-foetoproteins and beta-HCG) confirmed the benignity of the tumor. The child was operated on with full success.

[Lung metastasis disclosing a calf tumor]. / A propos d'une métastase pulmonaire révélatrice d'une tumeur du mollet.

Lung metastasis is a common finding, either before, with or after discovery of the primary tumor. Histological examination of a lung formation of unknown origin can lead to diagnosis of a primary tumor. We report the case of a 28-year old woman who presented an apparently primary tumor in the lower left pulmonary lobe. Pathology reported soft tissue alveolar sarcoma. The first manifestation of this rare soft tissue tumor can be a lung or brain tumor. Imaging evidenced the primary tumor in the left calf. Histology confirmed the diagnosis and the metastatic nature of the lung tumor.

[Endobronchial pulmonary rhabdomyosarcoma. A case report]. / Rhabdomyosarcome pulmonaire à présentation endobronchique. A propos d'une observation.

We report a case of pleiomorphous pulmonary rhabdomyosarcoma observed in a 64-year-old patient with no history of soft tissue tumor. The tumor was found extending into the right lower and middle lobes. The intra-parenchymatous extension protruded into the middle lobular bronchus and was prolonged by a 4 cm polyp. The polyp extended up to the carina and reached the contralateral common bronchus. Outcome was fatal after surgery performed in an emergency setting due to asphyxia. Explorations could not be continued to determine the primary or secondary nature of the tumor. An intraparenchymatous endobronchial localization is uncommon. Primary rhabdomyosarcoma is generally a purely intra-parenchymatous tumor. The endobronchial localization has been described before but is very exceptional. This localization would also be exceptional for secondary rhabdomyosarcoma mimicking a primary malignant tumor. The histology study revealed an undifferentiated pleiomorphous tumor. Immunohistochemistry provided the final diagnosis.