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Purpose: To investigate critical aspects and effectiveness of in vivo dosimetry (IVD) tests obtained by an electronic portal imaging device (EPID) in a multicenter and multisystem context. Materials and methods: Eight centers with three commercial systems—SoftDiso (SD, Best Medical Italy, Chianciano, Italy), Dosimetry Check (DC, Math Resolution, LCC), and PerFRACTION (PF, Sun Nuclear Corporation, SNC, Melbourne, FL)—collected IVD results for a total of 2002 patients and 32,276 tests. Data are summarized for IVD software, radiotherapy technique, and anatomical site. Every center reported the number of patients and tests analyzed, and the percentage of tests outside of the tolerance level (OTL%). OTL% was categorized as being due to incorrect patient setup, incorrect use of immobilization devices, incorrect dose computation, anatomical variations, and unknown causes. Results: The three systems use different approaches and customized alert indices, based on local protocols. For Volumetric Modulated Arc Therapy (VMAT) treatments OTL% mean values were up to 8.9% for SD, 18.0% for DC, and 16.0% for PF. Errors due to "anatomical variations" for head and neck were up to 9.0% for SD and DC and 8.0% for PF systems, while for abdomen and pelvis/prostate treatments were up to 9%, 17.0%, and 9.0% for SD, DC, and PF, respectively. The comparison among techniques gave 3% for Stereotactic Body Radiation Therapy, 7.0% (range 4.7–8.9%) for VMAT, 10.4% (range 7.0–12.2%) for Intensity Modulated Radiation Therapy, and 13.2% (range 8.8–21.0%) for 3D Conformal Radiation Therapy. Conclusion: The results obtained with different IVD software and among centers were consistent and showed an acceptable homogeneity. EPID IVD was effective in intercepting important errors. [ABSTRACT FROM AUTHOR]

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Purpose: The aim of this work is to investigate the predictive power of a common conventional intensity modulated radiation therapy (IMRT) quality assurance (QA) performance metric, the gamma passing rate (%GP), through the analysis of the sensitivity and of the correlation between %GP and different dose discrepancies between planned dose-volume histogram (DVH) and perturbed DVH. The perturbed DVH is calculated by using a dedicated software, 3DVH (Sun Nuclear Corporation, Melbourne, FL), which is able to modify the dose distribution calculated by the treatment planning system (TPS) according to the dose discrepancies detected with planar measurements in order to predict the delivered 3D dose distribution in the patient. Methods: Twenty-seven high-risk prostate cancer (PP) patients and 15 head and neck (HN) cancer patients, treated with IMRT technique, were analyzed. Pretreatment verifications were performed for all patients' plans by acquiring planar dose distributions of each treatment field with 2D-diode array. Measured dose distributions were compared to the calculated ones using the gamma index (GI) method applying both global (Van Dyk) and local normalization, and %GP were generated for each pair of planar doses using the following acceptance criteria: 1%/1, 2%/2, and 3%/3 mm. Planar dose distributions acquired during pretreatment verifications, together with patient's DICOM RT plan, RT structure set, and RT dose files from TPS were loaded into the 3DVH software. Percentage dose differences (%DE) between DVHs, obtained by TPS and by 3DVH, were calculated; statistical correlation between %DE and %GP was studied by using Pearson's correlation coefficient (r). This analysis was performed, for each patient, on planning target volumes and on some typical organs at risk of the prostatic and head and neck anatomical district. The sensitivity was calculated to correctly identify the pretreatment plans with high dose errors and to quantify the incidence of false negatives, on varying the gamma index method. Results: Analysis of %DE vs %GP showed that there were only weak correlations (Pearson's r-values < 0.8). The results also showed numerous instances of false negatives (cases where high IMRT QA passing rates did not imply good agreement in anatomy dose metrics) and the reverse, mainly for the 3%/3 mm global gamma passing rate. Conclusions: The lack of correlation between conventional IMRT QA performance metrics gamma passing rates and dose errors in DVHs values and the low sensitivity of 3%/3 mm global gamma method show that the most common published acceptance criteria have disputable predictive power for per-patient IMRT QA. [ABSTRACT FROM AUTHOR]

Background The antigens of the Colton blood group system, Coa and Cob, are encoded by a single gene that produces the aquaporin-1 (AQP1) protein, a water channel-forming protein, and are characterized by a single nucleotide polymorphism (SNP). A healthy Caucasoid blood donor originally typed as Co(a−b−) with commercial anti-Cob typed Co(a−b+) when retested with another anti-Cob. Retyped with two different molecular biology methods, the sample came out Co a /Co b. With the aim of understanding these discrepancies, serological, cytometric and molecular biology tests were carried out. Methods Absorption/elution studies with propositus red cells and controls were performed. The region spanning exon 1 to exon 4 of the Colton gene was sequenced, and flow cytometry analyses were carried out. Results Absorption/elution studies showed the absence of Coa and a weak expression of Cob. DNA sequencing confirmed a CT heterozygosity at nucleotide position 134 (i.e. Co a /Co b), and an additional heterozygous CT was found at position 112. The presence of the Co b allele that encodes for the Cob antigen was confirmed. The new allele has the base cytosine at nucleotide 134 ( Co a), in cis with the new nucleotide 112T. The nucleotide substitution 112C>T causes a missense mutation leading to an amino acid change from proline (CCG) to serine (TCG) at codon 38. Conclusion The substitution found at codon 38 results in a modified AQP1 protein which explains the Co(a−b+) phenotype and possibly the weak expression of Cob. [ABSTRACT FROM AUTHOR]

The performance and clinical relevance of a qualitative PCR-based assay for the detection of HIV-1 DNA sequences in peripheral blood mononuclear cells (PBMCs) was evaluated by two different laboratories. Four hundred and one samples were obtained from 397 individuals from different risk populations. All blood donors tested had negative results; positive signals were obtained from all infected patients. HIV-1 DNA was detected in 3 of 17 infants born to seropositive mothers; Western blot indeterminate blood donors and exposed healthcare workers had negative results. Our results demonstrate that this PCR assay provides both sensitive and specific results and is suitable for testing large numbers of samples and for rapid identification of HIV-1 infection. [ABSTRACT FROM AUTHOR]

Severe combined immunodeficiency (SCID) comprises a heterogenous group of disorders that are fatal unless treated by bone marrow transplantation (BMT). The most common form of SCID (T-B+ SCID) is due to mutations of either the common gamma chain (γc) or of γc-coupled JAK3 kinase. We report an unusual JAK3 defect in a female who was successfully treated > 20 years ago with a BMT using her HLA-identical father as the donor. Persistence of genetically and biochemically defective autologous B cells, associated with reconstitution of cellular and humoral immunity, suggests that integrity of the γc-JAK3 signalling pathway is not strictly required for immunoglobulin production. [ABSTRACT FROM AUTHOR]