NAT results of HBV and HCV under different vacuum collection tubes, storage temperature and storage time / 中国输血杂志

【Objective】 To verify the results of HBV DNA and HCV RNA screening under different brands of vacuum collection tubes for blood samples, storage temperature and storage time. 【Methods】 Experiment 1 was conducted as follows: blood samples were collected simultaneously from 52 voluntary blood donors using two brands(divided into group A and group B) of vacuum collection tubes for blood samples. The plasma separation of group A and group B were compared, and the effects of storage time on the NAT yield of HBV DNA and HCV RNA were statistically analyzed. Experiment 2 was conducted as follows: the effects of different storage temperature, time and tubes on the NAT yield of HBV DNA and HCV RNA samples with low viral load in group A and B were verified and compared in the simulated phlebotomy condition. 【Results】 In Experiment 1: After centrifugation, blood plasma layer and cells layer were separated completely in group A(100%, 52/52), but one sample was not well separated in group B(1/52, 1.92%). After 4 to 10 h after collection, blood samples of two groups were centrifuged and screened for HBV DNA, HCV RNA within 24 h. No positive samples were yielded and the Ct values of internal control(IC-DNA and IC-RNA) were uniform. In Experiment 2: Whole blood samples, stored for either 4 h or 6~10 h at 4 ℃ or 25℃ before centrifugation, showed no difference on the NAT-yield of HBV DNA nor HCV RNA samples with low viral load(P>0.05). Ct values of HBV DNA and HCV RNA of group A was similar to those of group B as centrifuged samples were stored for 24 h or 72~104 h at 4℃(P>0.05), but all increased as the storage time prolonged. Ct values of HBV DNA in group A increased from 33.45±0.29(24 h) to 33.82±0.08(72~104 h) and HCV RNA from 35.21±0.20 to 36.12±0.43; HBV DNA from 33.46±0.25 to 34.30±0.60 and HCV RNA from 35.47±0.24 to 36.49±0.51 in group B. 【Conclusion】 Under certain laboratory condition, different storage time, storage temperature and tubes shed few effect on the NAT-yield of HBV DNA and HCV RNA samples with low virus loads. However, it is suggested that the blood sample be detected within 72 h after centrifugation at 4 ℃ storage.

Quality of plasma samples and BD Vacutainer Barricor tubes: Effects of centrifugation.

BACKGROUNDS: The BD Vacutainer® Barricor™ Plasma collection tube (BD Barricor) uses an innovative non-gel separation method. This study compared the plasma residual cell count (PRCC) obtained from BD Barricor and from BD PST II plasma tubes. METHODS: Four BD Barricors and one BD PST II were collected from 40 donors. BD PST II was centrifuged at 1300g/10 min, while the BD Barricors were centrifuged at 1800g/10 min, 4000g/3 min, 4000g/7 min and 4000g/15 min. PRCC was evaluated measuring white blood cells (WBC), red blood cells (RBC) and Platelets (PLT) counts by Siemens ADVIA 2120. Cell-free hemoglobin was quantified by haemolysis index (HI) by Roche Cobas c501. RESULTS: BD PST II Median WBC, RBC and PLT counts were 0.38 (109/L), 0.0291 (1012/L) and 113.5 (109/L), respectively. Considering the BD PST II as reference, PRCC differences were expressed as median bias percentage. WBC showed a significant reduction at all the conditions (p < 0.01), being the reductions: 63.9% (1800g/10 min), 69.9% (4000g/3 min), 75.0% (4000g/7 min) and 82.7% (4000g/15 min). RBC reductions 29.7% (1800g/10 min), 33.8% (4000g/3 min), 39.6% (4000g/7 min) and 66.4 (4000g/15 min) were all significant (p < 0.01). PLT reductions were 1.6% at 1800g/10 min (p = ns), 1.2% at 4000g/3 min (p = ns), 27.1% at 4000g/7 min (p = 0.046) and 46.6% at 4000g/15 min (p = 0.005). BD Barricor centrifuged for 7 and 15 min at 4000g showed an increased haemolysis. CONCLUSIONS: BD Barricors plasma quality improved with increasing the centrifugation times but already at 4000g/3 min, the suggested centrifugation condition, a significant improvement was achieved.

Does laboratory automation for the preanalytical phase improve data quality?

Our aim was to evaluate whether automation for the preanalytical phase improves data quality. Blood from 100 volunteers was collected into two vacuum tubes. One sample from each volunteer was respectively assigned to (G1) traditional processing, starting with centrifugation at 1200 g for 10 min, and (G2) the MODULAR PRE-ANALYTICALS EVO-MPA system. The routine clinical chemistry tests were performed in duplicate on the same instrument Cobas 6000 module. G1 samples were uncapped manually and immediately placed into the instrument. G2 samples were directly fed from the MPA system to the instrument without further staff intervention. At the end, (1) the G1 samples were stored for 6 h at 4 °C as prescribed in our accredited laboratory and (2) the G2 samples were stored for 6 h in the MPA output buffer. Results from G1 and G2, before and after storage, were compared. Significant increases were observed in G1 compared with G2 samples as follows: (1) before storage for alkaline phosphatase (ALP), lactate dehydrogenase (LDH), phosphate (P), magnesium (MG), iron (FE), and hemolysis index and (2) after storage for total cholesterol (COL), triglycerides (TG), total protein (TP), albumin (ALB), blood urea nitrogen (BUN), creatinine (CRE), uric acid (UA), ALP, pancreatic amylase, aspartate aminotransferase (AST), alanine aminotransferase (ALT), g-glutamyltransferase (GGT), LDH, creatine kinase (CK), calcium (CA), FE, sodium (NA), potassium (K), and hemolysis index. Moreover, significant increases were observed in (3) G1-after versus G1-before storage samples for COL, high-density lipoprotein cholesterol, TG, TP, ALB, BUN, CRE, UA, AST, ALT, GGT, LDH, P, CA, MG, FE, NA, K, and hemolysis index and (4) G2-after versus G2-before storage only for BUN, AST, LDH, P, and CA. In conclusion, our results show that the MPA system improves the quality of laboratory testing.

SU-E-T-497: Study of Restricted Mass Stopping Power Ratio in Small Electron Tube Fields.

PURPOSE: Electron tubes with small radii are useful to treat narrow regions which cannot accommodate normal electron applicators. In small electron fields, it is not trivial to estimate restricted mass stopping power ratio (MSR), which is needed to evaluate dose from ion chamber measurement. We studied MSRs in small electron tube fields using the Monte Carlo simulation. METHODS: Electron tubes with radii, 3 and 2.5 cm, were used in this study. Nominal electron energies were 6 and 9 MeV. There were two types of tubes. One has a normal cut but the other has a 45-degree cut. For the normal cut tube, percent depth dose (PDD) in water was evaluated along the center of axis (CAX) of a beam. For the 45-degree cut tube, PDD was evaluated along the vertical line from the intersection of the CAX and the phantom surface with 45-degree gantry angle. The MSRs and mean electron energies were calculated using the Monte Carlo simulation. RESULTS: We found good agreement between the measured and calculated PDDs. The changes of mean energies from those in the 10×10 cm2 field at the depth of maximum dose (dmax) were very small for the normal cut electron tubes. For the 45-degree cut tubes, the changes of mean energies at dmax were less than 1 MeV. The MSRs in the normal cut tube fields were almost the same as those in the 10×10 cm2 field at the corresponding depths. The MSRs for the 45-degree cut tubes deviated from those in the 10×10 cm2 by about 1% (1.5 % at most). CONCLUSIONS: We evaluated the mean energies and MSRs in small electron tube fields. The deviations of them from the values in the 10×10 cm2 were small. The maximum difference of MSR was 1.5% in 45-degree cut tube fields. This work was supported by KAKENHI (23791449), Japan Society for the Promotion of Science, and Cancer Professional Training Plan, The Ministry of Education, Culture, Sports, Science and Technology, Japan.

Energy dependence of EBT-1 radiochromic film response for photon (10kVp-15MVp) and electron beams (6-18MeV) readout by a flatbed scanner.

PURPOSE: The aim of this article is to investigate the energy dependence of the radiochromic film type, Gafchromic™ EBT-1, when scanned with a flatbed scanner for film readout. METHODS: Dose response curves were determined for 12 different beam qualities ranging from a10kVp x-ray beam to a 15MVp x-ray beam and include also two high energy electron beam qualities (6 and 18MeV). The dose responses measured as net optical density (netOD) for the different beam qualities were normalized to the response of a reference beam quality (6MVp). RESULTS: A strong systematic energy dependence of the film response was found. The lower the effective beam energy, the less sensitive the EBT-1 films get. The maximum decrease in dose for the same film response between the25kVp and 6MVp beam qualities was 44%. Additionally, a difference in energy dependence for different doses was discovered, meaning that higher doses show a smaller dependency on energy than lower doses. The maximum decrease in the normalized netOD was found to be 25% for a dose of 0.5Gy relative to the normalized netOD for 10Gy. Moreover, a scaling procedure is introduced, allowing the correction of the energy dependence for the investigated beam qualities and also for comparable x-ray beam qualities within the energy range studied. CONCLUSIONS: A strong energy dependence for EBT-1 radiochromic films was found. The films were readout with a flatbed scanner. If the effective beam energy is known, the energy dependence can be corrected with the introduced scaling procedure. Further investigation of the influence of the spectral band of the readout device on energy dependence is needed to understand the reason for the different energy dependences found in this and previous works.

Robust x-ray tubes for use within magnetic fields of MR scanners.

A hybrid system that combines an x-ray fluoroscopic system and a magnetic resonance (MR) system can provide physicians with the synergy of exquisite soft tissue contrast (from MR) and high temporal and spatial resolutions (from x ray), which may significantly benefit a number of image-guided interventional procedures. However, the system configuration may require the x-ray tube to be placed in a magnetic field, which can hinder the proper functioning of the x-ray tube by deflecting its electron beam. From knowledge of how the magnetic field affects the electron trajectories, we propose creating another magnetic field along the cathode-anode axis using either solenoids or permanent magnets to reduce the deflection of the electron beam for two cases: a strong and slightly misaligned field or a weak field that is arbitrary in direction. Theoretical analysis is presented and the electron beam is simulated in various external magnetic fields with a finite element modeling program. Results show that both correction schemes enhance the robustness of the x-ray tube operation in an externally applied magnetic field.