Variation in patient position and impact on carbon-ion scanning beam distribution during prostate treatment.

OBJECTIVE: We assessed the impact of changes in patient position on carbon-ion scanning beam distribution during treatment for prostate cancer. METHODS: 68 patients were selected. Carbon-ion scanning dose was calculated. Two different planning target volumes (PTVs) were defined: PTV1 was the clinical target volume plus a set-up margin for the anterior/lateral sides and posterior side, while PTV2 was the same as PTV1 minus the posterior side. Total prescribed doses of 34.4 Gy [relative biological effectiveness (RBE)] and 17.2 Gy (RBE) were given to PTV1 and PTV2, respectively. To estimate the influence of geometric variations on dose distribution, the dose was recalculated on the rigidly shifted single planning CT based on two dimensional-three dimensional rigid registration of the orthogonal radiographs before and after treatment for the fraction of maximum positional changes. RESULTS: Intrafractional patient positional change values averaged over all patients throughout the treatment course were less than the target registration error = 2.00 mm and angular error = 1.27°. However, these maximum positional errors did not occur in all 12 treatment fractions. Even though large positional changes occurred during irradiation in all treatment fractions, lowest dose encompassing 95% of the target (D95)-PTV1 was >98% of the prescribed dose. CONCLUSION: Intrafractional patient positional changes occurred during treatment beam irradiation and degraded carbon-ion beam dose distribution. Our evaluation did not consider non-rigid deformations, however, dose distribution was still within clinically acceptable levels. ADVANCES IN KNOWLEDGE: Inter- and intrafractional changes did not affect carbon-ion beam prostate treatment accuracy.

Evaluation of salivary flow and drug interactions in patients with a diagnosis of diabetes mellitus.

AIM: Diabetes mellitus (DM) is one of the most common chronic diseases responsible for substantial loss on the quality of life in elderly. Oral manifestations in these patients include xerostomia and alterations in salivary flow and salivary pH. The aim of this study was to analyze the relationship between salivary flow, pH and medication. METHODS: The sample consisted of 53 subjects aged 60 years and older, including 30 patients with a diagnosis of type 2 DM and 23 controls. RESULTS: Salivary flow was 1.066±0.814 mL/min in the control group and 0.955±0.606 mL/min in the DM group, with no significant difference between groups (P=0.588). There was a significant difference (P=0.045) in mean salivary pH (DM: 5.267±0.828; control: 5.783±0.951). Only 32.07% of the patients reported to remove their denture while sleeping. Three of 53 subjects using medications presented severe drug interactions. CONCLUSION: In summary, dentists must be able to make the diagnosis, to recognize all factors related to salivary alterations in DM, and to prescribe adequate treatment related to oral condition. Patients with DM presented salivary pH below normal reference values. It is important to advice patients to remove their denture while sleeping in order to prevent traumatic irritations and infections with Candida albicans. Potentially harmful cases of drug interactions have to be observed in elderly patient. Further studies focusing on the nature of drug interactions as the cause of adverse events such as xerostomia and increased salivary pH are needed.