No abstract

A range of still and sparkling mineral waters were assessed for their erosive potential together with comparator soft drinks using in vitro dissolution assays with extracted human teeth and powdered hydroxyapatite. Dissolution levels with all of the mineral waters were very low and for several still waters were undetectable. Sparkling mineral waters showed slightly greater dissolution than still waters, but levels remained low and were of the order of one hundred times less than the comparator soft drinks. De-gassing of a sparkling mineral water reduced its dissolution, but the total levels were still relatively low suggesting that carbonation of drinks may not be an important factor per se in respect of erosive potential. The complex and heterogeneous mineral compositions of mineral waters could influence the dissolution equilibrium of apatite in enamel and controlled addition of several ions to ultrapure deionized water was investigated. Calcium ions led to the greatest reduction in hydroxyapatite dissolution, but their effects were moderated by other ions including magnesium and sulphate. Thus, mineral waters appear to offer a safe alternative to more erosive acidic beverages and their complex mineral ion compositions may positively influence any dissolution processes at the tooth surface.

No abstract

A study was undertaken to explore the use of volumetric modulated arc therapy (VMAT) for total body irradiation (TBI). Five patient plans were created in Pinnacle3 using nine 6 MV photon dynamic arcs. A dose of 12 Gy in six fractions was prescribed. The planning target volume (PTV) was split into four subsections for the head, chest, abdomen, and pelvis. The head and chest beams were optimized together, followed by the abdomen and pelvis beams. The last stage of the planning process involved turning all beams on and performing a final optimization to achieve a clinically acceptable plan. Beam isocenters were shifted by 3 or 5 mm in the left–right, anterior–posterior, and superior–inferior directions to simulate the effect of setup errors on the dose distribution. Treatment plan verification consisted of ArcCheck measurements compared to calculated doses using a global 3%/3 mm gamma analysis. All five patient plans achieved the planning aim of delivering 12 Gy to at least 90% of the target. The mean dose in the PTV was 12.7 Gy. Mean lung dose was restricted to 8 Gy, and a dose reduction of up to 40% for organs such as the liver and kidneys proved feasible. The VMAT technique was found to be sensitive to patient setup errors particularly in the superior–inferior direction. The dose predicted by the planning system agreed with measured doses and had an average pass rate of 99.2% for all arcs. VMAT was found to be a viable treatment technique for total body irradiation.

Flavoured sparkling waters should be considered as potentially erosive, and preventive advice on their consumption should recognize them as potentially acidic drinks rather than water with flavouring.