Finger doses due to68Ga-labelled pharmaceuticals in PET departments-results of a multi-centre pilot study.

INTRODUCTION: Although the use of68Ga has increased substantially in nuclear medicine over the last decade, there is limited information available on occupational exposure due to68Ga. The purpose of this study is to determine the occupational extremity exposure during the preparation, dispensing and administration of68Ga-labelled radiopharmaceuticals. METHOD: Workers in eight centres wore a ring dosimeter for all tasks involving68Ga-labelled radiopharmaceuticals for a minimum of one month. Additionally, the fingertip dose was monitored in two centres and the hand with the highest ring dose during68Ga procedures was also identified in one centre. RESULTS: The median normalised ring dose for68Ga procedures was found to be 0.25 mSv GBq-1(range 0.01-3.34). The normalised68Ga ring doses recorded in this study are similar to that found in the literature for18F. This study is consistent with previous findings that the highest extremity dose is found on the non-dominant hand. A limited sub study in two of the centres showed a median fingertip to base of the finger dose ratio of 4.3. Based on this median ratio, the extrapolated annual68Ga fingertip dose for 94% of the workers monitored in this study would be below Category B dose limit (150 mSv) and no worker would exceed Category A dose limit (500 mSv). CONCLUSION: When appropriate shielding and radiation protection practices are employed, the extremity dose due to68Ga is comparable to that of18F and is expected to be well below the regulatory limits for the majority of workers.

Review of extremity dosimetry in nuclear medicine.

The exposure of the fingers is one of the major radiation protection concerns in nuclear medicine (NM). The purpose of this paper is to provide an overview of the exposure, dosimetry and protection of the extremities in NM. A wide range of reported finger doses were found in the literature. Historically, the highest finger doses are found at the fingertip in the preparation and dispensing of18F for diagnostic procedures and90Y for therapeutic procedures. Doses can be significantly reduced by following recommendations on source shielding, increasing distance and training. Additionally, important trends contributing to a lower dose to the fingers are the use of automated procedures (especially for positron emission tomography (PET)) and the use of prefilled syringes. On the other hand, the workload of PET procedures has substantially increased during the last ten years. In many cases, the accuracy of dose assessment is limited by the location of the dosimeter at the base of the finger and the maximum dose at the fingertip is underestimated (typical dose ratios between 1.4 and 7). It should also be noted that not all dosimeters are sensitive to low-energy beta particles and there is a risk for underestimation of the finger dose when the detector or its filter is too thick. While substantial information has been published on the most common procedures (using99mTc,18F and90Y), less information is available for more recent applications, such as the use of68Ga for PET imaging. Also, there is a need for continuous awareness with respect to contamination of the fingers, as this factor can contribute substantially to the finger dose.

Biclonal lymphoproliferative disorders: another association with NOTCH1-mutated chronic lymphocytic leukaemias.

INTRODUCTION: Biclonal lymphoid disorders, when two distinct lymphoproliferative disorders (LPD) co-exist, are rare (incidence of 1.4%) and associated with a poor prognosis. NOTCH1 mutations occur in 10% of CLL at diagnosis, associated with a short disease-free interval and increased risk of Richter's transformation. We hypothesised that the incidence of NOTCH1 mutations in CLL with a second LPD may be increased, because the mutation occurs early in leukaemogenesis, permitting clonal divergence. METHODS: We identified 19 patients with biclonal LPD at diagnosis: 11 with CLL and a second LPD (group A) and 8 with a second distinct CLL (group B). NOTCH1 mutation analysis was performed and clinical outcome investigated. RESULTS: Ten of 19 (52%) were NOTCH1 mutated: 5 in group A (45%) and 5 in group B (62.5%) with a favourable clinical outcome observed among this cohort with 28.7 (range 1-99) months of follow-up. CONCLUSION: In conclusion, we identified a significant (52%) incidence of NOTCH1 mutations in CLL in the context of biclonal LPD, associated with an indolent clinical course.

Composite t(14;18)-Negative Follicular Lymphoma and Nodular Lymphocyte-Predominant Hodgkin Lymphoma.

A composite lymphoma is the rare simultaneous occurrence of two or more distinct lymphomas within a single tissue or organ. Herein, we describe a case of a 51-year-old man presenting with a history of lower limb rash, fatigue, and bulky abdominopelvic lymphadenopathy. An excisional left iliac lymph node biopsy was notable for the composite presence of two distinct lymphoid neoplasms, nodular lymphocyte-predominant Hodgkin lymphoma (NLPHL), and follicular lymphoma (FL). Multiplex PCR and FISH analyses failed to demonstrate a t(14;18)(q32;q21) translocation in either composite lymphoma component. A clonal light-chain kappa (V/JC intron-kde) gene rearrangement was detected in the FL component only.

Optimization and Validation of an 8-Color Single-Tube Assay for the Sensitive Detection of Minimal Residual Disease in B-Cell Chronic Lymphocytic Leukemia Detected via Flow Cytometry.

OBJECTIVE: The European Research Initiative on chronic lymphocytic leukemia (ERIC) has designed a single-tube, 8-color chronic lymphocytic leukemia CLL-MRD flow cytometric assay to standardize testing in patients with B-CLL. This study aims to optimize and validate the 8-color CLL-MRD assay, with the desired outcome of it being implemented in St. James's Hospital Dublin and potentially other hospitals worldwide as the most accurate flow-based B-CLL-MRD detection currently available. METHOD: The single-tube assay incorporates 8 antibodies, namely, CD5, CD3, CD19, CD20, CD22, CD43, CD79b, and CD81. We tested a combination of 52 peripheral blood and bone marrow specimens with the antibodies to develop a sequential gating strategy that uses the typical phenotype of B-CLL cells to enumerate small residual B-CLL populations after treatment, effectively distinguishing them from the normal polyclonal and regenerating B-cells. We performed sensitivity assays via a set of serial dilutions and compared the assay with the current International Standardized Approach (ISA) method currently in use for MRD testing in B-CLL. RESULTS: The 52 specimens that we analyzed displayed MRD levels from 0.004% through 78.000%. Dilutional studies demonstrated detection of disease to a level of 0.00702%, and an excellent correlation was achieved against the current ISA method (R(2)= 0.991). CONCLUSION: The 8-color CLL-MRD assay provides a more informative approach than its predecessors for the assessment of MRD in B-CLL by functioning as an important disease biomarker, with MRD negativity acting as an indicator to achieving a clinical endpoint.

Doses under automatic exposure control (AEC) for direct digital radiographic (DDR) X-ray systems.

Current guidelines quote tolerances for automatic exposure control (AEC) device performance for X-ray systems as 'Baseline ± X %'. However, in the situation where a baseline figure has not yet been achieved, as in the case of commissioning assessments, this tolerance is not relevant. The purpose of this work is to provide mean doses for direct digital radiography (DDR) X-ray system, operating in AEC, against which comparisons can be made. Dose measurements have been recorded under AEC operation on 29 DDR detectors from three different manufacturers. Two different testing protocols were examined: (1) water equivalent phantoms in front of the DDR detector and (2) aluminium block at the tube head. The average patient exit dose, using the aluminium block was 4.6 µGy with the antiscatter grid in place and 4.0 µGy with the grid removed. Using the water phantoms, the average dose was measured at 17.1 µGy with the antiscatter grid in place and 5.4 µGy with grid removed. Based on these results, it is clear that different testing configurations significantly impact on the measured dose.