Application of EPR dosimetry in bone for ex vivo measurements of doses in radiotherapy patients.

In the present study, bone samples from three patients treated in radiotherapy facilities in Poland were used for the determination of doses absorbed during radiotherapy. The samples were obtained during surgical treatments of patients performed due to medical indications. For the purpose of retrospective dosimetry, sensitivity of the radiation-induced EPR signal was individually calibrated in the samples by re-irradiation of the samples with known doses. The doses reconstructed in bones extracted within 6 months after irradiation were consistent with those calculated by treatment planning systems. The dose reconstructed in the bone removed 6 y after radiotherapy was ∼14% lower than the calculated one.

Influence of promethazine on cardiac repolarisation: a double-blind, midazolam-controlled study.

Drugs used in anaesthesia may provoke torsadogenic changes in cardiac repolarisation. The aim of this study was to assess the effect of promethazine on the parameters of ventricular repolarisation: QTc interval and transmural dispersion of repolarisation. Forty patients were randomly allocated to receive promethazine (25 mg) or midazolam (2.5 mg). Changes in the ECG and arterial blood pressure were recorded. Correction of QT interval was calculated using Bazett's formula and Fridericia's correction; transmural dispersion of repolarisation was determined as T(peak)-T(end) time. Significant prolongation of QT interval, corrected with both formulae, was detected in patients receiving promethazine, while no change in the QTc value was observed in the midazolam group. There were no significant differences in T(peak)-T(end) time either between or within the groups. In conclusion, promethazine induces significant QTc prolongation but the lack of influence on transmural dispersion of repolarisation makes the risk of its torsadogenic action very low.