Mean heart dose variation over a course of breath-holding breast cancer radiotherapy.

Objective The purpose of the work was to estimate the dose received by the heart throughout a course of breath-holding breast radiotherapy.Methods 113 cone-beam CT (CBCT) scans were acquired for 20 patients treated within the HeartSpare 1A study, in which both an active breathing control (ABC) device and a voluntary breath-hold (VBH) method were used. Predicted mean heart doses were obtained from treatment plans. CBCT scans were imported into a treatment planning system, heart outlines defined, images registered to the CT planning scan and mean heart dose recorded. Two observers outlined two cases three times each to assess interobserver and intraobserver variation.Results There were no statistically significant differences between ABC and VBH heart dose data from CT planning scans, or in the CBCT-based estimates of heart dose, and no effect from the order of the breath-hold method. Variation in mean heart dose per fraction over the three imaged fractions was <6 cGy without setup correction, decreasing to 3.3 cGy with setup correction. If scaled to 15 fractions, all differences between predicted and estimated mean heart doses were <0.5 Gy and in 80% of cases, they were <0.25 Gy.Conclusion Variation in mean heart dose was at an acceptable level over the duration of breath-holding radiotherapy and was well predicted by the planning system. Advances in knowledge: Mean heart dose was not adversely affected by fraction-to-fraction variations throughout a course of heart-sparing radiotherapy using two well-established breath-holding methods

Decentralisation's effects on public investment: evidence and policy lessons from Bolivia and Colombia

This paper examines decentralisation in Bolivia and Colombia to explore its effects on the uses and spatial distribution of public investment, as well as government responsiveness to local needs. In both countries, investment shifted from infrastructure to social services and human capital formation. Resources were rebalanced in favour of poorer districts. In Bolivia, decentralisation made government more responsive by re-directing public investment to areas of greatest need. In Colombia, municipalities increased investment significantly while running costs fell. Six important lessons emerge from the comparison. For decentralisation to work well: (i) local democracy must be transparent, fair and competitive; (ii) local governments must face hard budget constraints; (iii) central government must be scaled back; (iv) significant tax-raising powers must be devolved; and (v) decentralisation is composed of distinct, separable components, the sequencing of which is important. Finally, (vi) what decentralisation achieves, and whether it is advisable, hinges on how central government behaved pre-reform

Correction of dust event frequency from MODIS Quick-Look imagery using in-situ aerosol measurements over the Lake Eyre Basin, Australia

Subjective visual interpretation of MODIS Quick-Look imagery has proven useful in characterising dust source geomorphology and dust event frequency over diverse areas, but is limited by the small temporal sampling window of polar orbiting platforms, and obscuration by cloud. In this paper we seek to quantify the inevitable under-reporting of dust events in Quick-Look imagery, via a three-year case study over the Lake Eyre Basin (LEB), the largest dust source in Australia and the southern hemisphere. Dust event identification from MODIS imagery is compared with the level of dust mobilization inferred from measurements of near-surface aerosol made by a continuously-operating integrating nephelometer, located at the AeroSpan/AERONET station at Tinga Tingana in the Strzelecki Desert, adjacent to major dust sources in the LEB. The analysis indicates a major upward revision in the overall dust event frequency by ~ 72%, including a doubling of the incidence of major dust outbreaks. The intensity of missed events increases toward late afternoon and evening, although without a net day-night bias. These factors suggest the potential of new geostationary sensors and the analysis of night-time polar orbiting imagery in improving the reporting of dust mobilization over active dust-source regions. For the LEB, the corrections are crucial in understanding not only the seasonal distribution of dust mobilization, but its interannual variability and climatology.No Full Tex