Intercomparison and performance assessment of radionuclide calibrators used in nuclear medicine departments in Serbia.

The purpose of this work is to assess accuracy and compare the performance of radionuclide calibrators (RNCs) used in nuclear medicine departments in Serbia. Testing of the RNCs included verification of measurement accuracy, as well as analysis of routinely used quality control protocols, by using the certified radioactivity standards (57Co, 137Cs). RNCs performances were assessed with 99mTc through comparison of reference value for radionuclide activity and RNC measurements. Results of the intercomparison revealed that RNCs, 15 in total, are accurate within 10% in vial geometry and within 15% in syringe geometry. Most of them showed similar performance. The results revealed that container geometry is an important influencing parameter in the accuracy of activity measurement. Obtained results indicate a need for regular calibration and implementation of Quality Control program in order to achieve and maintain the accuracy of activity measurements in nuclear medicine.

Occupational radiation dose of personnel involved in sentinel node biopsy procedure.

INTRODUCTION: Sentinel node biopsy is a procedure used for axillary nodal staging in breast cancer surgery. The process uses radioactive 99mTc isotope for mapping the sentinel node(s) and all the staff involved in the procedure is potentially exposed to ionizing radiation. The colloid for radiolabelling (antimone-sulphide) with 99mTc isotope (half-life 6 h) is injected into the patient breast. The injection has activity of 18.5 MBq. The surgeon removes the primary tumor and detects active lymph nodes with gamma detection unit. The tumor as well as the active nodal tissue is transferred to pathologist for the definitive findings. The aim of the study was to measure dose equivalents to extremities and whole body for all staff and suggest practice improvement in order to minimize exposure risk. MATERIALS AND METHODS: The measurements of the following operational quantities were performed: Hp(10) personal dose equivalent to whole body and Hp(0.07) to extremities for staff as well as ambiental dose for operating theatre and during injection. Hp(0.07) were measured at surgeon's finger by ring thermoluminescent dosimeter (TLD) type MTS-N, and reader RADOS RE2000. Surgeon and nurse were wearing TLD personal dosimeter at the chest level. Anesthesiologist and anesthetist were wearing electronic personal dosimeters, while pathologist was wearing ring TLD while manipulating tissue samples. Electronic dosimeters used were manufactured by Polimaster, type PM1610. All TLD and electronic dosimeters data were reported, including background radiation. Background radiation was also monitored separately. Personal TLDs are standard for this type of personal monitoring, provided by accredited laboratory. Measurements of ambiental dose in workplaces of other staff involved around the patient was performed before the surgery took place, by calibrated survey meters manufactured by Atomtex, type 1667. The study involved two surgeons and one pathologist, two anesthesiologists and three anesthetists during two months period. RESULTS AND DISCUSSION: The doses received by all staff are evaluated using passive and active personal dosimeters and ambiental dose monitors and practice was improved based on results collected. Average annual whole body dose for all staff involved in the procedure was less than 0.8 mSv. Extremity dose equivalents to surgeon and pathologist were far below the limits set for professionally exposed (surgeon) and for public (pathologist). CONCLUSIONS: Although has proven to be very safe for all staff, additional measures for radiation protection, in accordance to ALARA principle (As Low As Reasonably Achievable) should be conducted. The recommendations for practice improvement with respect to radiation protection were issued.

Fractional excretion of magnesium and kidney function parameters in nondiabetic chronic kidney disease.

AIM: Elevated fractional excretion of magnesium (FEMg) is a noninvasive biomarker of kidney damage, but its association with kidney functional parameters in nondiabetic chronic kidney disease (CKD) patients has not been sufficiently explored thus far. METHODS: We enrolled 111 adult patients with nondiabetic CKD and 30 controls. To precisely investigate kidney function, the following parameters were assessed measured glomerular filtration rate (mGFR), effective renal plasma flow (ERPF), Cystatin C, albuminuria, and fractional excretion of magnesium (FEMg). All the CKD patients were divided into two groups according to the values of mGFR (mL/min/1.73m2): the first group consisted of those with GFR≥ 60 mL/min/1.73m2, whereas the second group included those with GFR< 60 mL/min/1.73m2. RESULTS: FEMg (%) was significantly higher in the group of nondiabetic patients with CKD compared to the healthy subjects [6.3 vs. 5.3 %, P=0.013]. There was also significant difference in the value of FEMg between the first and second groups of CKD patients. Increased FEMg was significantly correlated with all the investigated kidney function parameters, mGFR, ERPF, Cystatin C and albuminuria (r=-0.62; r=-0.60; r=0.77; r=0.39; p<0.01 for all). In multiple regression analyses based on observed parameters of kidney function, only cystatin C was independently and significantly associated with FEMg (multiple correlation coefficients: 0.738, p < 0.001)). Nondiabetic CKD patients with GFR< 60 mL/min/1.73m2 have increased FEMg above 6.1% with 78.7 % specificity and 83.7% sensitivity. CONCLUSION: Highly significant association between kidney functional parameters and FEMg may indicate significance of this parameter in clinical practice.