Evaluation of the calibration parameters of radiochromic films for patient dosimetry in interventional radiology.

The study aims to analyse the effects of beam energy, dose fractionation, response homogeneity, long-term fading and response sensitivity of radiochromic films. It also investigates the effect of the scanner, ambient temperature and storage conditions on the response of the films. The radiochromic films were irradiated at various air kerma from 20 mGy to about 8 Gy. Results showed that the response of the films is not energy dependent for low doses ranging from 300 to 700 mGy (coefficient of variation = 5-12%) but starts to show a slight dependence for high doses above 2 Gy (coefficient of variation = 20%). There is no significant difference (4%) in optical densities (OD) and pixel values when doses were fractionated and when using scanner with and without warm-up lamp. The curve fitting of OD and pixel values for the sensitivity test at different kilovolt potential gave an r(2) value of 0.99.

Altered gene expression may underlie prolonged duration of the QT interval and ventricular action potential in streptozotocin-induced diabetic rat heart.

Ventricular electrical conduction has been investigated in the streptozotocin (STZ)-induced diabetic rat. Diabetes was induced with a single injection of STZ (60 mg/kg bodyweight, ip). The ECG was measured continuously, in vivo, using a biotelemetry system. Left ventricular action potentials were recorded with an extracellular suction electrode. Expression of mRNA transcripts for selected ion transport proteins was measured in left ventricle with real-time RT-PCR. At 10 weeks after STZ treatment, in vivo heart rate (HR) was reduced (267 +/- 3 vs. 329 +/- 5 BPM), QRS complex duration and QT interval were prolonged in diabetic rats compared to controls. In vitro spontaneous HR was reduced and paced heart action potential repolarization was prolonged in diabetic rats compared to controls. The mRNA expression for Kcnd2 (I (to) channel) and Kcne2 (I (kr) channel) was significantly reduced in diabetic rats compared to controls. Altered gene expression and, in particular, genes that encode K(+) channel proteins may underlie delayed propagation of electrical activity in the ventricular myocardium of STZ-induced diabetic rat.

Radiation dose profile in 125I brachytherapy: an 8-year review.

The use of episcleral plaques containing radioactive 125I seeds for brachytherapy treatment of selected retinoblastoma cases of patients is being done in Riyadh, Saudi Arabia since 1994. There are about three to four patients per year. A total of 31 patients were treated with a tumour dose in the range of 40-60 Gy using 8 seeds of 125I each from 1994 to 2002. This study determines the trend of occupational doses received by surgeons, anaesthesiologists and nurses and the dose rate profile around the eyes. Only 3% of the 275 persons monitored for Hp(10) have measurable doses with a weighted average of 4 microSv and 7% of the 175 persons monitored for Hp(0.07) have measurable doses with a weighted average of 0.3 mSv. The dose rate is maximum (110 microSv h(-1)) at the point of contact with the eye plaque and reduces to approximately 40% on the side of the other eye.

Occupational doses during the injection of contrast media in paediatric CT procedures.

The administration of intravenous contrast media by hand or power injection in paediatric computed tomography (CT) procedures is carried out at King Faisal Specialist Hospital and Research Centre for chest, abdomen and torso diagnostic examinations. Some procedures require the CT unit to commence patient scanning during the injection of the last volume of the contrast medium. During the injection, even if the nurse is wearing a 0.5 mm lead equivalent protective apron, the head region and the hand are likely to receive high doses. This study was therefore made to assess the head and extremity doses to the nurses during CT procedures where typical exposure parameters of 200 to 220 mA s and 120 kVp were used. Thermoluminescence dosemeters were deployed for three consecutive months in two CT rooms. A total of 96 procedures were performed during this period and they were included in this study. Scattered radiation measurements were done at different locations where the nurse may be positioned. Results showed that the average dose to the head region and the hands per paediatric case were 50 microSv and 80 microSv respectively. This study investigated the factors that affect the dose and found them to be the length of stay inside the room, type of CT examination. exposure parameters and location of the nurse.

Incidence and seasonal variation of Type 1 diabetes in children in Farwania area, Kuwait (1995-1999).

The aim of our study was to confirm the continuing rise in the incidence of Type 1 diabetes among Kuwaiti children aged 0-14, and to assess the effect of seasonality on incidence. Data from all newly diagnosed diabetic children between the period of 1995 and 1999 were analyzed. A total of 129 cases of Type 1 diabetes were diagnosed during the study period, of whom 68 were Kuwaiti nationals and were included in the study. The incidence was 20.18 per 100,000 (95% CI 16.3-28.2). Incidence rates for the age-groups 0-4, 5-9 and 10-14 were 8.12, 21.07 and 34.06, respectively. There was a significant female predominance (F:M ratio was 1.4:1, P<0.05). More cases were diagnosed in the cool months (November-February) compared with the warm months (June-September, P<0.05). There was increase in incidence from 1995 to 1999, but compared with data from the 1980s on the same age group, incidence has increased. A positive family history of Type 1 diabetes in a close relative was recorded for 30% of the patients. Although, only data from one hospital were included, Kuwait is very small geographically and not likely to have differences between different areas. Stress factors, economic growth, changes in the nutritional habits and the adoption of the western lifestyle may explain some of this increase.

123I isotope as a diagnostic agent in the follow-up of patients with differentiated thyroid cancer: comparison with post 131I therapy whole body scanning.

Radioactive iodine (131I) plays a major role in the diagnosis and management of differentiated thyroid cancer (DTC); however, data on the use of the 123I isotope in DTC are limited. We compared 238 diagnostic whole body scans performed 24 h after oral ingestion of 185-555 MBq 123I with their corresponding 131I posttherapy whole body scans obtained 4-5 d after 131I therapy. We studied scans in 3 clinical situations: with the first 131I therapy, with the second 131I therapy, and in cases of elevated Tg and negative diagnostic scan. One hundred and seventy-seven pairs were obtained with the first 131I therapy and showed complete concordance between pretreatment and posttreatment scans in 166 pairs (concordance rate, 93.8%). Six other posttreatment scans showed more foci in the thyroid bed than the pretreatment scans, but no evidence of uptake in new areas. Only 5 posttreatment scans showed foci in new locations: 3 in cervical lymph nodes (CLN), 1 in the lung, and 1 new bone metastasis in a patient with known skeletal metastases. With the second 131I therapy, 34 pairs were obtained and showed complete concordance in 28 pairs (concordance rate, 82.4%). Five discordant pairs showed additional foci in areas that were already positive on pretreatment scans. Only 1 posttreatment scan showed a new bone metastasis in a different site from the bone metastases that were seen on its corresponding pretreatment scan. Of 27 pairs of scans in patients with elevated Tg and negative pretreatment scans, 15 posttreatment scans remained negative, 6 posttreatment scans showed an uptake in the thyroid bed, and 3 other posttreatment scans showed lung uptake in patients whose computed tomography scans of the chest showed only bronchiectasis (in 2 patients) and lung scarring (in the third patient) without evidence of lung metastases. Three posttreatment scans showed definite uptake (in thyroid bed, thyroid bed and lung, and CLN) compared with their corresponding pretreatment scans, which were initially reported negative but were retrospectively thought to have had faint uptake. In 56 pretreatment scans, the 123I diagnostic activity was 185 MBq, and the results showed complete concordance in 54 pairs. Two posttreatment scans showed additional uptake: 1 in the bone and 1 in CLN. These data suggest that pretreatment scanning using 123I is highly comparable to 131I posttreatment scanning and that 123I is an excellent diagnostic agent in DTC.