Plan quality and consistency in spine radiosurgery treatment planning: comparison between automatic treatment planning with Elements Spine SRS and manual inverse planning with Varian Eclipse.

Spine radiosurgery treatment planning can be a challenging task since a high radiation dose is delivered to target volumes close to the spinal cord, therefore a steep dose gradient is required. Plan quality is greatly influenced by the planner skills, so automatic treatment planning has been proposed to overcome this issue and assure high-quality plans. The Brainlab Elements Spine SRS treatment planning system is specially designed for spine radiosurgery treatments. It is an automatic treatment planning system that works through predefined protocols, with minimal planner interaction required. In this work, we evaluated the plan quality and consistency among the planners within the same institution when using the Elements Spine SRS compared to manual inverse planning with the Varian Eclipse system. Six planners produced a plan for 3 sample target volumes representing different spine metastases in the thoracic region using both treatment planning systems. Dose prescription was 16 Gy in a single fraction, at more than 80% of the target volume. The most important organ at risk was the spinal canal. The dose constraint was V10 Gy < 0.35 cm3. High dose spillage outside the target volume, the homogeneity index, the Paddick conformity index and the number of monitor units were also evaluated. The mean dose to the target volumes in the Elements Spine SRS plans were consistently higher by 0.8 Gy to 1.5 Gy and the maximum dose to the target volumes were consistently higher by 1.8 Gy to 3.1 Gy. Spinal cord sparing was comparable to the Eclipse plans. However, the number of monitor units was greatly reduced, up to 2270 monitor units less. No difference was found in plan quality variability among the planners.

Patient-based low dose cone beam CT acquisition settings for prostate image-guided radiotherapy treatments on a Varian TrueBeam linear accelerator.

OBJECTIVE: To evaluate the performance of low dose cone beam CT (CBCT) acquisition protocols for image-guided radiotherapy of prostate cancer. METHODS: CBCT images of patients undergoing prostate cancer radiotherapy were acquired with the settings currently used in our department and two low dose settings at 50% and 63% lower exposure. Four experienced radiation oncologists and two radiation therapy technologists graded the images on five image quality characteristics. The scores were analysed through Visual Grading Regression, using the acquisition settings and the patient size as covariates. RESULTS: The low dose acquisition settings have no impact on the image quality for patients with body profile length at hip level below 100 cm. CONCLUSIONS: A reduction of about 60% of the dose is feasible for patients with size below 100 cm. The visibility of low contrast features can be compromised if using the low dose acquisition settings for patients with hip size above 100 cm. ADVANCES IN KNOWLEDGE: Low dose CBCT acquisition protocols for the pelvis, based on subjective evaluation of patient images.

Hypofractionated volumetric modulated arc therapy (VMAT) for fragile patients with oesophageal cancer.

PURPOSE: To evaluate the feasibility, safety, and dosimetric results of volumetric modulated arc therapy (VMAT) to deliver hypofractionated radiotherapy (RT) in oesophageal cancer patients, unfit for a multimodality curative strategy. PATIENTS/METHODS: From 2010 to 2017, 22 patients were treated with hypofractionated VMAT for palliative/symptomatic setting. The prescription dose was 40 Gy in 16 fractions (EQD2 41.7 Gy considering an α/ß ratio of 10 Gy, and 44 Gy considering an α/ß ratio of 3 Gy). RESULTS: Eight patients (36%) were symptomatic for grade 3 baseline dysphagia. RT was generally well tolerated, and no patient interrupted the daily treatment. Acute toxicity was generally mild; no G3 acute toxicities were reported. At the end of treatment, 5 patients (22.7%) experienced a stable dysphagia and 14 (63.6%) an improvement of baseline dysphagia, while 3 patients (13.7%) reported a worsening of oesophagitis. At a mean follow-up of 8.7 months, 15 patients (79%) had a complete clinical recovery (G0-1) of the symptomatic moderate/severe dysphagia. At 3 months after the end of RT, seven patients (31.8%) achieved a partial or complete response. Two coplanar arcs were employed for VMAT delivery. Dosimetric results were consistent in terms of both target coverage and normal tissue sparing. Finally, 1-year progression-free and overall survival was 20% and 27.3%, respectively. CONCLUSIONS: Hypofractionated VMAT was feasible, safe, and effective to deliver symptomatic radiation in locally advanced oesophageal cancer patients, non-suitable for a standard curative treatment.

Feline leishmaniosis due to Leishmania infantum in Italy.

A case of leishmaniosis in domestic cats (Felis catus domesticus) is described. The subject showed a nodular lesion on the eyelid. The diagnosis was achieved by serological, parasitological, and light and electron microscopic investigations. By molecular techniques the aetiological agent was identified as belonging to Leishmania infantum, the species implicated in human and canine leishmaniosis in southern Europe. A preliminary study on the prevalence of asymptomatic feline leishmaniosis, performed in the areas where the infected cat was identified, revealed a low seroprevalence of infection: only 1 (0.9%) of the 110 cat sera examined by indirect fluorescent antibody test was positive for anti-Leishmania antibodies. Because clinical signs in feline leishmaniosis are unspecific and similar to those observed in other diseases commonly found in this species, leishmaniosis must be added to the differential diagnosis by feline veterinary practitioners and adequate serologic and histopathologic investigations must be performed in endemic areas.