[en] Radiopharmaceuticals are chemical compounds including proteins and antibodies which are labelled with a radioactive tracer. High radiochemical purity of the labelled compounds is essential for normal biodistribution and high quality images. Photochemical reaction (light induced chemical reaction) has the potential to compromise the quality of radiopharmaceuticals. The aim of this paper is to review the photosensitive radiopharmaceuticals in use in Australia and New Zealand. There are some radiopharmaceutical products which are documented as light-sensitive by the suppliers. If adequate precautions are not taken to prevent exposure to light, they may undergo photochemical degradation which may give rise to abnormal biodistribution. This paper will explain briefly photochemistry and identify the potential causes of photodegradation of radiopharmaceuticals. It will also provide additional information about the intensity of light required to degrade the product and how to eliminate photochemical degradation. Photochemistry is not always undesirable for all radiopharmaceuticals, it has been used to improve/simplify radiolabelling of monoclonal antibody based radiopharmaceuticals with Tc-99m. In routine practice of radiopharmacy, we take various precautionary measures with radiopharmaceuticals and it is important to understand the possible photosensitivity as well. (author)

[en] Short communication

[en] Full text: Cardiolite and Ceretec are two very useful but costly ^99mTc labelled radiopharmaceuticals. To improve cost-effectiveness, various fractionation techniques have been developed with normal saline, SnCI₂ solution and stannous ion augmentation. The aim of this study was to simplify and test the best method of fractionation and assess cost savings in clinical use. Fractionation of Cardiolite kit with normal saline has the limitation that it can take only 2.5 GBq of ^99mTc and the stannous augmentation method requires the preparation of fresh stannous solution for every use. Fractionation using nitrogen purged 50 pg/mL SnCI₂ solution to 1:5 and stored at -20 degree C overcomes these limitations. They are ready to use vials and each vial can be reconstituted with 6.5 GBq of ^99mTc. These fractionated kits were tested for a period of three months (n = 180) . The mean radiochemical purity was 92.1 + 2.7% and produced satisfactory clinical images. Cost savings were calculated as $40 000 per year if performing >3 patients per day and $56 000 per if <3 patients per day. Ceretec kit was fractionated to 1:5 using nitrogen purged normal saline and stored at -20 degree C. Subsequent stannous enhancement was done by the addition of 0.1 ml of Sn-PYP (18μg SnCI₂) prior to reconstitution with ^99mTc (1.3 GBq). Published methodology recommends preparation of fresh Sn-PYP solution for every use. To simplify this, we prepared and stored Sn-PYP in a 1 mL aliquot at 20 degree C for a period of one month. These kits (n = 33) produced acceptable clinical images and the mean radiochemical purity was 93.4%(range 86 - 98%). This yields an estimated saving of $22 000 per year in a department performing twice a week Ceretec studies. We conclude that fractionation of Cardiolite kit to 1:5 using SnCI₂ solution and fractionation of Ceretec kit to 1:5 using normal saline and subsequent stannous enhancement prior to reconstitution are effective. In our view, these are the optimal techniques of fractionation for routine clinical use

[en] Short communication. 1 tab

[en] Short communication

[en] Highlights: • Structural and surface morphological properties of AlGaN with different Al composition were investigated. • Increasing the Al composition growth rate decreases with dislocation increases, which are confirmed by wet etch and HRXRD. • Surface morphology are investigated in H_3PO_4 etchant and α, β and γ type pits are observed. • PL intensity enhanced due to the increases surface roughness of the AlGaN film after etching. - Abstract: In this work, Al_xGa_1_−_xN epilayers have been grown on sapphire substrate with GaN template by the metal organic chemical vapor deposition (MOCVD) method. The structural and morphological properties of these samples have been investigated and compared. The growth rate of AlGaN has been found to decrease with increasing Al composition. By increasing Al composition of AlGaN epilayer, tilt and twist angle has been found to increase, indicating higher threading dislocation density. Surface morphology and dislocation density (DD) have been investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Different types of dislocation etch pits have been observed in Al_xGa_1_−_xN/GaN epilayers, using orthophosphoric acid (85% H_3PO_4) as defect selective etchant. Three types of etch pits like screw type (α), edge type (β) and mixed type (α + β) dislocations have been observed. The mechanism of etch pits formation has been explained using Cabrera’s thermodynamic model. The etch pit density (EPDs) has been correlated with threading dislocation density (TDs) estimated using HRXRD measurements. Photoluminescence (PL) studies have revealed an increase in intensity of near band edge emission due to etching

[en] Short communication

[en] Helicobacter pylori infection is traditionally diagnosed by endoscopy followed by gastric biopsy and histologic demonstration of organisms, rapid urease test and culture. The non-invasive carbon-14-urea breath test has been widely accepted now for the diagnosis of this bacterium. This study was aimed to establish and validate normal and abnormal values for an Australian population, for a single sample carbon-14-urea breath test at ten minutes. A dose of 185 kBq was used in order to achieve reasonable counting statistics. The derived values were validated with the results of the rapid urease test. This method has a high sensitivity, specificity and greater patient acceptance, and could be used in many clinical settings as the first modality for the diagnosis of H. pylori infection and for documenting response or cure after antibiotic therapy for eradication. 11 refs., 1 tab., 4 figs

[en] Full text: Plasma clearance of ^99mTc-DTPA is a standard method for GFR assessment. Protein binding (PB) of ^99mTc-DTPA is thought to affect the accuracy of the GFR measurement. Therefore, eliminating PB portion would improve the accuracy of this measurement. Methods to eliminate PB are usually complex, but a simple Amicon micropartition system has been proposed to eliminate the PB effect. This study is aimed to assess if this simple method effectively excluded the PB fraction and improved the accuracy of the GFR measurement. Therefore, eliminating PB portion would improve the accuracy of this measurement. Methods to eliminate PB are usually complex, but a simple Amicon micropartition system separates free ^99mTc-DTPA from the PB fraction after a 10 min centrifugation of patient plasma. The ultrafiltrate obtained is totally free of PB ^99mTc-DTPA. 20 consecutive patients had GFRs performed using the two sample method with blood drawn at 60 and 150 min. All samples had an Ultrafiltrate ^99mTc-DTPA and normal plasma ^99mTc-DTPA. The GFRs were calculated from both samples. The findings showed a mean PB of 6.5 + 3.9% and 13 + 5.0% at 60 min and 150 min respectively for our DTPA. The mean GFR from normal plasma 85.7 + 26.4 mL/min and from ultrafiltrate = 97.2 + 28.8 mL/min. Statistical analysis using Student''s ''t'' test shows that there is a significant difference between the values of GFR (P < 0.05). Our result confirms that the PB of DTPA is substantial and affects the GFR estimation significantly. The method of ultrafiltration eliminates the PB, and very simple to use. This method could be used on a routine basis and/or to assess the suitability of the DTPA used in various departments for GFR measurement

[en] Short communication