Australas Phys Eng S
-
Poincaré indices are usually applied to HRV to summarise long data sets collected over 24 hrs. Many applications of HRV are interested in dynamic, short term changes (<1 min). This study uses Poincaré indices published through the 1990's to the present, to determine which of them are correlated over the short term (25 beats). ⋯ These indices will not be used for further investigation of dynamic effects of fentanyl and midazolam, two sedative drugs used in anaesthesia and intensive care. Indices that proved less suitable for short term analysis (eg. presence of outliers, inability to produce a valid index with smaller number of beats) were also identified. A shortlist of Poincaré indices that do not correlate strongly with commonly used measures may prove interesting in determining dynamic characteristics of the effect of sedative drugs on autonomic nervous system activity.
-
Australas Phys Eng S · Sep 2007
Thermoluminescence dosimetry for in-vivo verification of high dose rate brachytherapy for prostate cancer.
It was the aim of the study to verify dose delivered in urethra and rectum during High Dose Rate brachytherapy boost (HDRBB) of prostate cancer patients. During the first fraction of HDRBB measurement catheters were placed in the urethra and rectum of prostate cancer patients. These contained LiF:Mg,Ti Thermoluminescence Dosimetry (TLD) rods of 1 mm diameter, with up to 11 detectors positioned every 16 mm separated by radio-opaque markers. ⋯ TLD in-vivo measurements are easily performed in urethra and rectum during HDR brachytherapy of prostate patients. They verify the delivery and provide information about the dose delivered to critical structures. The latter may be of particular interest if higher doses are to be given per fraction such as in HDR monotherapy.
-
Australas Phys Eng S · Mar 2006
Comparative StudyTime-frequency analysis of heart rate variability for neonatal seizure detection.
The ECG has been much neglected in automatic seizure detection in the newborn. Changes in heart rate and ECG rhythm are often found in animal and adult patients with seizure. ⋯ The TFDs studied are the Wigner-Ville (WVD), the Spectrogram (SP), the Choi-Williams (CWD) and the Modified B (MBD) distributions. Based on our preliminary results, our current conclusion is MBD outperforms other TFDs in terms of time-frequency resolution, cross-terms suppression and to represent the newborn HRV signals of non-seizure and seizure which are closely-spaced components in the time-frequency domain.
-
Australas Phys Eng S · Mar 2006
Comparative StudySurvey of Poincaré indices for measuring heart rate variability.
Multiple indices have been developed to characterise the nonperiodic behaviour of heart rate variability displayed in Poincaré plots, particularly with R-R interval data collected over 24hr periods. Some of these indices have been compared to statistical time-domain indices and some to spectral indices, while others have been used to separate data sets such as cardiac abnormalities. ⋯ This study examined these Poincaré indices and determined their correlations with time-domain indices, and investigated how the correlations are affected by analysing shorter time periods. Further investigation of the Poincaré indices that do not correlate strongly with SD or rMSSD may prove interesting in determining dynamic characteristics of cardiac nervous system activity.