Quantification of biological range uncertainties in patients treated at the Krakow proton therapy centre.

BACKGROUND: Variable relative biological effectiveness (vRBE) in proton therapy might significantly modify the prediction of RBE-weighted dose delivered to a patient during proton therapy. In this study we will present a method to quantify the biological range extension of the proton beam, which results from the application of vRBE approach in RBE-weighted dose calculation. METHODS AND MATERIALS: The treatment plans of 95 patients (brain and skull base patients) were used for RBE-weighted dose calculation with constant and the McNamara RBE model. For this purpose the Monte Carlo tool FRED was used. The RBE-weighted dose distributions were analysed using indices from dose-volume histograms. We used the volumes receiving at least 95% of the prescribed dose (V95) to estimate the biological range extension resulting from vRBE approach. RESULTS: The vRBE model shows higher median value of relative deposited dose and D95 in the planning target volume by around 1% for brain patients and 4% for skull base patients. The maximum doses in organs at risk calculated with vRBE was up to 14 Gy above dose limit. The mean biological range extension was greater than 0.4 cm. DISCUSSION: Our method of estimation of biological range extension is insensitive for dose inhomogeneities and can be easily used for different proton plans with intensity-modulated proton therapy (IMPT) optimization. Using volumes instead of dose profiles, which is the common method, is more universal. However it was tested only for IMPT plans on fields arranged around the tumor area. CONCLUSIONS: Adopting a vRBE model results in an increase in dose and an extension of the beam range, which is especially disadvantageous in cancers close to organs at risk. Our results support the need to re-optimization of proton treatment plans when considering vRBE.

[Halitosis--diagnosis and treatment]. / Halitoza--diagnostyka i leczenie.

Halitosis (bad breath) applies to according to various authors--even 25-50% of the population. Volatile sulfur compounds are frequently encountered in the exhaled air. The article presents the most common causes of halitosis. It is believed that approximately 80-90% of the causes of halitosis are located in the head area (mouth, ear, nose, throat), whereas the remaining cases correspond to systemic illness, such as of the stomach and lung, certain medications or food. This paper describes different means to assess halitosis, which can be helpful in determining the diagnosis. The article describes ways to treat the symptoms and causes of halitosis associated with oral cavity. In patients who have had another source of halitosis, additional diagnostic procedures and appropriate treatment must be performed. Given the prevalence of the problem of the malodour and its impact on the quality of everyday life, halitosis is a phenomenon that should not be underestimated. The causes need to be detected and an appropriate therapy must be performed. Patients with diagnosed halitophobia should be directed to appropriate specialists.