Verification of representative data for output factors of SRS cones utilizing IAEA TRS 483 recommendations.

Measurements of small fields continue to be a clinical challenge despite the recent work done to identify their characteristics. Due to this challenge, many physicists use representative data supplied by their vendors to verify their own measurements for small field output factors. However, with recent guidelines being released in IAEA TRS 483, the question remains if this representative data provides an accurate representation for small field dosimetry. A Sun Nuclear EDGE detector, PTW 60012 stereotactic diode, and GafChromic EBT3 films were used to measure the output factor for a set of Varian SRS cones (4 mm-17.5 mm diameters) on a TrueBeam linear accelerator. The measured output factors were then compared to the Varian provided SRS representative data. IAEA TRS 483 recommendations for measuring small field output factors were applied and the impact of those recommendations were examined. The EDGE detector showed good agreement with the representative data when correction factors were not applied (0.01%-1.64% difference) but the PTW 60012 diode showed larger deviation (0.61%-3.35% difference). The EBT3 film showed the largest difference with the representative data (0.66%-9.19%). After application of IAEA TRS 483 detector specific correction factors the output factors measured by the diodes showed good agreement with the EBT3 film for 6MV (<1.8% difference) but showed a large deviation with the representative data (up to 9% difference). The 6FFF energy output factors agreed between the EDGE, the PTW 60012, and EBT3 Film. This work shows that the use of uncorrected representative data on the Truebeam can lead to a significant over estimation of the SRS cone output factors.

The effectiveness of topical preparations for the treatment of earwax: a systematic review.

BACKGROUND: Earwax is a common problem in both primary and secondary care. There is uncertainty as to the most effective topical treatment. AIM: To assess the evidence concerning the efficacy of topical preparations used for treating earwax. DESIGN OF STUDY: Systematic review and meta-analysis. METHOD: Searching for randomised controlled trials (RCTs) of relevant studies. Classification of preparations into three groups, enabling pooling of data and meta-analysis. RESULTS: Of the 18 RCTs included in the review, four were judged to be of high quality. Fifteen preparations including saline and plain water were studied. Oil-based and water-based preparations were equally effective at clearing earwax without syringing (odds ratio [OR] = 0.9, 95% confidence interval [CI] = 0.4 to 2.3) and facilitating successful syringing (OR = 1.0, 95% CI = 0.6 to 1.6). A non-water-, non-oil-based preparation appeared more effective than an oil-based preparation at both clearing earwax without syringing, and facilitating successful syringing. Immediate syringing after application of a preparation may be as effective as using eardrops for several days and delaying syringing. CONCLUSIONS: On current evidence, there is little to choose between water-based and oil-based preparations; non-water-, non-oil-based preparations appear promising at both clearing earwax and facilitating successful syringing, but further large trials are needed. Although immediate ear syringing is effective and convenient for patients, it may be less cost-effective than using eardrops and perhaps avoiding syringing. Most of the evidence regarding such a common and time-consuming problem is not of high quality.