Simultaneous Multiple Liver Metastasis Treated with Pencil Beam Proton Stereotactic Body Radiotherapy (SBRT)

Compared with photon stereotactic body radiotherapy (SBRT) plans that may have to use many more penetrating x-ray beams for each isocenter, proton SBRT with ultrahypofractionated doses use fewer beam angles and offer significantly reduced low-dose radiation bath to normal liver tissue. We demonstrate techniques to deliver safe and effective proton SBRT, where planning and organ motion complexity further increased with multiple liver lesions. For treatment planning, we recommend robust and logical beam angles, avoiding devices and encouraging entry perpendicular to the dominant motion, as well as volumetric repainting to mitigate the interplay effect to clinically acceptable levels. This report highlights the significant technical challenges with ultrahypofractionated proton pencil beam scanning liver therapy, how they are managed, and the effectiveness of this treatment.

A Clinical Case of 5 Times Irradiated Recurrent Orbital Hemangiopericytoma

Orbital hemangiopericytomas (HPCs) are rare mesenchymal tumors with a high tendency to recur. Treatment options are quite limited in case of a relapse, but re-irradiation can be useful. Most of the available data limit the possibility of re-irradiation, while novel techniques (e.g., pencil beam proton therapy [PT]) open new approaches for the safe repeating of treatment. To the best of our knowledge, this is the first well-documented case of multi-times (>3) irradiation of tumors located intracranially. The case reported here describes orbital HPCs with proton irradiation performed two times since 1999 in a 30-year-old woman with a medical history as well as surgery followed by conventional radiotherapy (RT) and chemotherapy, and two times stereotactic RT (in 2009 and 2013).In 2016 the patient came to our hospital with the 3rd relapse of the tumor, located in the left orbit, with an intracranial part, involving cavernous sinus, which was close to the temporal lobe. The 4th course of irradiation was done in May to June 2016 by pencil beam PT. Radiation necrosis occurred after 2 years and was treated with bevacizumab (BVZ). Three years later, another relapse was treated with PT and BVZ. The 9-month follow-up showed complete tumor response without signs of brain toxicity. The patient died due to a brain abscess 1 year after the 5th irradiation. This case shows a possibility of irradiation, applied 5 times to the same location, with promising results and manageable toxicity.