Relative energy response of indigenously developed optically stimulated luminescence dosimeters Al2 O3 :C, LiMgPO4 :B and LiCaAlF6 :Eu,Y in therapeutic photon and electron beams.

The relative energy responses of three indigenously developed optically stimulated luminescence (OSL) phosphors in the disc form were studied in therapeutic photon and electron beams. Calibration in terms of absorbed dose was carried out in the dose range 5-500 cGy in 60 Co gamma rays, high energy X-rays, and electron beams used in radiotherapy. The combined standard uncertainty in the estimation of absorbed dose using these OSL discs (OSLDs) was 3.3%. Dose-response curves of these OSLDs in 60 Co gamma rays, 6 and 10 MV (flat and unflat), 15 MV and 6 and 15 MeV electron beams were found to be linear. Furthermore, these OSLDs exhibited a relative energy-dependent response for both photon and electron beams. The relative energy response correction factor for photon and electron beams were in the range 1.01-1.05 and 1.03-1.06, respectively.

Radiation dose measurements in a dental orthopantogram unit using indigenously developed optically stimulated luminescence dosimeters.

Dental orthopantogram (OPG)/cone beam computed tomography (CBCT) scanners are gaining popularity due to their 3D imaging with multiplanar view that provides clinical benefits over conventional dental radiography systems. Dental OPG/CBCT provides optimal visualization of adjacent overlaying anatomical structures that will be superpositioned in any single projection. The characteristics of indigenously developed optically stimulated luminescence dosimeters, namely, aluminium oxide doped with carbon (Al2 O3 :C), lithium magnesium phosphate doped with terbium and boron (LiMgPO4 :Tb,B) and lithium calcium aluminium fluoride doped with europium and yttrium (LiCaAlF6 :Eu,Y) were evaluated for their use in dental dosimetry. The dose-response of these dosimeters was studied at X-ray energies 60 kV, 70 kV and 81 kV. Radiation doses were also measured using Gafchromic film for comparison. Radiation dose was measured at eight different locations of a polymethyl methacrylate (PMMA) head phantom including eyes. The optically stimulated luminescence (OSL) sensitivity of LiMgPO4 :Tb,B is about 1.5 times and LiCaAlF6 :Eu, is about 20 times higher than the sensitivity of Al2 O3 :C. It was found that measured radiation doses by the three optically stimulated luminescence dosimeters (OSLDs) and Gafchromic film in the occipital region (back side) of a PMMA phantom, were consistent but variations in dose at other locations were significantly higher. The three OSLDs used in this study were found to be suitable for radiation dose measurement in dental units.

Predicting postoperative pain by using preoperative pain threshold in response to electrical stimulus in women undergoing gynaecological cancer surgery - Single-arm, prospective, observational study.

Background and Aims: Individual variability leading to different pain experiences makes pain prediction challenging. This study aimed to evaluate whether preoperative electrical pain threshold testing is predictive of postoperative pain. Methods: Following ethics committee approval and registration of the trial, 40 consenting patients undergoing open laparotomy (interval debulking surgery) for ovarian cancer were included in the study. Electrical stimulus (maximum of 256 µA) was used preoperatively to determine the current perception threshold (CPT) and pain equivalent current (PEC). A numerical rating scale (NRS; 0-10, with 0 indicating no pain and 10 indicating severe pain) was used to assess pain. All patients received intravenous paracetamol in accordance to body weight, diclofenac (1 mg/kg, maximum 50 mg), and tramadol (1 mg/kg, maximum 50 mg) eight hourly for 24 hours. The preoperative PEC was compared with worst pain score (PS) at movement at the end of 24 hours. PEC was also compared with average PS at rest, at movement, and with opioid requirement (24 hours). Results: The median values of CPT and PEC were 12.51 (45 [10.1-14.6]) µA and 94.75 (174 [48.8-94.7]) µA, respectively. A moderate correlation was observed between PEC and worst PS (P = 0.01, r = -0.402), with patients having PEC less than 60 µA being associated with moderate-to-severe PS. There was no correlation between PEC and average PS at rest (P = 0.16, r = 0.225), at movement (P = 0.46, r = 0.119), and the postoperative opioid consumption in the first 24 hours (P = 0.50, r = -0.110). Conclusion: There is a moderate association between preoperative pain threshold in response to electrical stimulus and worst PS in the postoperative period following interval debulking surgery for ovarian cancer.

PATIENT-SPECIFIC DOSIMETRY USING IN-HOUSE DEVELOPED OSL DISC DOSEMETERS.

Circular discs of diameter 5 mm were made from three indigenously developed optically stimulated luminescent (OSL) phosphors for medical dosimetry. Dosimetric characteristics of these discs were evaluated for their use in machine and patient-specific dosimetry in radiotherapy. Uncertainty in dosimetric measurements using these discs was also estimated, and combined standard uncertainty in measurement of absorbed dose was found to be 3.34%. Characterisation studies indicate that OSL discs are suitable for dosimetric application in radiotherapy. These discs were also used for patient-specific dosimetry in conventional and conformal radiotherapy treatments (five different cases) vis-à-vis ionisation chamber and Gafchromic EBT3 film. Doses measured by OSL discs were found comparable to ionisation chamber and Gafchromic EBT3 film measured values and radiotherapy treatment planning system (TPS) calculated dose values in all the cases. The variation between TPS calculated dose values and OSL discs measured dose values was found within the measurement uncertainty.

Comparative bioequivalence studies of tramadol hydrochloride sustained-release 200 mg tablets.

BACKGROUND: Tramadol hydrochloride is available as 50 mg immediate-release (IR) and 100 mg, 200 mg, and 300 mg sustained-release (SR) tablets. The recommended dose of tramadol is 50-100 mg IR tablets every 4-6 hours. The tramadol SR 200 mg tablet is a better therapeutic option, with a reduced frequency of dosing, and improved patient compliance and quality of life. The present study evaluated the bioequivalence of a generic tramadol SR 200 mg tablet. METHODS: A comparative in vitro dissolution study was performed on the test and reference products, followed by two separate single-dose bioequivalence studies under fasting and fed conditions and one multiple-dose bioequivalence study under fasting conditions. These bioequivalence studies were conducted in healthy human subjects using an open-label, randomized, two-treatment, two-period, two-sequence, crossover design. The oral administration of the test and reference products was done on day 1 for both the single-dose studies and on days 1-5 for the multiple-dose study in each study period as per the randomization code. Serial blood samples were collected at predefined time points in all the studies. Analysis of plasma concentrations of tramadol and O-desmethyltramadol (the M1 metabolite) was done by a validated liquid chromatography-mass spectrometry analytical method. The standard acceptance criterion of bioequivalence was applied on log-transformed pharmacokinetic parameters for tramadol and its M1 metabolite. RESULTS: The ratios for geometric least-square means and 90% confidence intervals were within the acceptance range of 80%-125% for log-transformed primary pharmacokinetic parameters for tramadol and its M1 metabolite in all the three studies. CONCLUSION: The test product is bioequivalent to the reference product in terms of rate and extent of absorption, as evident from the single-dose and multiple-dose studies. Both the treatments were well tolerated.