Purpose
To investigate the geometric and dosimetric impacts of intra-fractional movement for patients with single or multiple brain metastasis treated using Varian Hyperarc™ mono-isocentric radiosurgery.
Methods
A total of 50 single or hypo-fractionated Hyperarc™ treatment courses (118 lesions) were included in the analysis. Intra-fractional translational and rotational movements were quantified according to the post-treatment cone-beam CT (CBCT). Geometric displacements of all targets were calculated individually based on the assessed head movement in each treatment fraction and their relationships with treatment time and target-to-isocenter distances were studied. For dosimetric analysis, only single-fraction treatments (56 lesions) were included. Re-planning was performed with 0, 1, and 2 mm planning target volume (PTV) margins. Doses were then re-calculated on rotated CT images with isocenter shifted which emulate the change in patient treatment position. Target coverage, target and normal brain doses before and after intra-fractional movement were compared.
Results
The mean 3D target displacements was 0.6 ± 0.3 (SD) mm. Target shifts for patients treated within 10 min were significantly smaller than those treated in longer sessions. No correlation was found between target shift and target-to-isocenter distance as the origin of head rotation was not located at the isocenter. Loss of target coverage and minimum Gross Tumor Volume (GTV) dose due to intra-fractional movement were apparent only when no margin was used, leading to an extra 23% of the targets violating the dose acceptance criteria, in contrast, the effects on normal brain V12Gy were negligible regardless of the margin used. The use of 1 mm PTV margin can compensate clinically significant geographical miss caused by intra-fractional movements while limiting V12Gy to within dose criteria for 88% of the cases. The plan acceptance rate (fulfillment of both target and normal brain dose criteria) after intra-fractional movement was also the highest with the 1 mm margin.
Conclusion
Although intra-fractional movements during Hyperarc™ treatments were small, there were substantial dosimetric effects due to the sharp dose fall-off near target boundaries. These effects could be mitigated by using a 1 mm PTV margin and maintaining the effective treatment time to within 10 min.
VEN and frequency analysis were used to analyze the quality of pharmacotherapy of 79 patients with chronic hepatitis (CH) who were treated in a healthcare institution (HCI) in the city of Dnipropetrovsk in 2015. It has been found that pharmacotherapy at the HCI corresponded to main areas of the treatment specified in the clinical protocol of medical care (CPMC) to patients with CH. It has confirmed the rationality of drug prescriptions. However, a significant number of prescriptions per a patient (on average 8.9 drugs) indicates the polypharmacy in this department of the HCI. Moreover, according to the results of the formal VEN analysis a significant number of drugs with the index N (non-essential drugs) has been determined; it indicates the need for correction of drug prescription by doctors at this HCI in accordance with the current science-based medical regulations-the National Drug Formulary of Ukraine (the 7 th edition) and the CPMC to patients with CH-by reducing prescriptions of non-essential drugs that are not included in these regulations. Today, being developed 11 years ago, the CPMC to patients with CH needs to be updated since it does not meet modern requirements to the current science-based medical practice guidelines that allow making the best clinical decisions in favour of the patient in accordance with the requirements of evidence-based medicine.
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