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  • Author: Grzegorz Zwierzchowski x
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Quality assurance procedures based on dosimetric, gamma analysis as a fast reliable tool for commissioning brachytherapy treatment planning systems

Abstract

Background

Fast and easily repeatable methods for commissioning procedures for brachytherapy (BT) treatment planning systems (TPS) are needed. Radiochromic film dosimetry with gamma analysis is widely used in external beam quality assurance (QA) procedures and planar film dosimetry is also increasingly used for verification of the dose distribution in BT applications. Using the gamma analysis method for comparing calculated and measured dose data could be used for commissioning procedures of the newly developed TG-186 and MBDCA calculation algorithms. The aim of this study was dosimetric verification of the calculation algorithm used in TPS when the CT/MRI ring applicator is used.

Materials and methods

Ring applicators with 26 and 30 mm diameters and a 60 mm intra-uterine tube with 60° angle were used for verification. Gafchromic® EBT films were used as dosimetric media. Dose grids, corresponding to each plane (dosimetric film location), were exported from the TPS as a raw data. Gafchromic® films were digitized after irradiation. gamma analysis of the data were performed using the OMNI Pro I’mRT® system, as recommended by the AAPM TG-119 rapport criterion for gamma analysis of 3%, 3 mm and a level of 95%.

Results

For the 26 mm and 30 mm rings, the average gamma ranged, respectively, from 0.1 to 0.44 and from 0.1 to 0.27. In both cases, 99% of the measured points corresponded with the calculated data.

Conclusions

This analysis showed excellent agreement between the dose distribution calculated with the TPS and the doses measured by Gafchromic films. This finding confirms the viability of using film dosimetry in BT.

Open access
Locomotor activity and daily milk yield of dairy cows during the perioestrous period in successive lactations

Locomotor activity and daily milk yield of dairy cows during the perioestrous period in successive lactations

The experiment was conducted in a herd of high-producing Holstein-Friesian cows, using the AfiFarm Herd Management Software, to analyze their locomotor activity during 236 oestruses in relation to the daily milk yield determined during the periooestrous period in four successive production and reproductive cycles. Day "0" was the day of the observed oestrus. Locomotor activity and milk production levels were monitored five days before and five days after oestrus. A correlation was noted between high milk yield and the reproductive performance of cows. An increase in milk yield was accompanied by extended inter-pregnancy and inter-calving intervals and a drop in the insemination index which also tended to decrease in multiparous cows. Primiparous and the highest-yielding cows were characterized by the highest levels of locomotor activity. The physical activity of cows increased by around 67% during oestrus. However, daily milk yield declined at oestrus, compared with the average milk production levels determined five days before and five days after oestrus in each lactation. The installation of pedometers supported the detection of oestrus, including silent oestrus, in dairy cows, and the AfiFarm system was found to be an effective tool for dairy farming and herd management.

Open access