Internal radiation dose assessment of radiopharmaceuticals prepared with cyclotron-produced 99m Tc

Technetium-99m (99m Tc) is the radioisotope most widely used in diagnostic nuclear medicine. It is readily available from 99 Mo/99m Tc generators as the \u3b2- decay product of the 99 Mo (T\ubd =66 h) parent nuclide. This latter is obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct reactions using proton beams on specific target materials [100 Mo(p,2n)99m Tc], have the potential to be both reliable and relatively cost-effective. However, results showed that the 99m Tc extracted from proton-bombarded 100 Mo-enriched targets contains small quantities of several Tc radioisotopes (93m Tc, 93 Tc, 94 Tc, 94m Tc, 95 Tc, 95m Tc 96 Tc and 97m Tc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotron-produced 99m Tc (CP-99m Tc) using 99.05% 100 Mo-enriched metallic targets

Methods for preparation and administration of lutetium-177 oxodotreotide 3.7 GBq: proceedings from an Italian advisory board

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Quantitative analysis of image metrics for reduced and standard dose pediatric 18F-FDG PET/MRI examinations

The study performs a comprehensive analysis of image metrics to objectively support the reduction of injected activity in pediatric oncology 18F-FDG PET/MR (18F-fludeoxyglucose PET/MR) examinations. Contrast-to-Noise Ratio (CNR), Normalized Noise (NN), tumor burden, and standardized uptake value (SUV) parameters stability were investigated to robustly define the acceptable reduced activity level that preserves the clinical utility of images, considering different PET applications

Quality control in PET/CT and PET/MRI: Results of a survey amongst European countries.

International audiencePurpose: An EFOMP Working Group (WG) was created in 2020 to establish recommendations for PET/CT/MRI Quality Control (QC). The WG's intention was to create a document containing a set of measurements suitable for routine practice. In order to map the current situation in PET facilities, the WG prepared a survey addressed to European Medical Physics Experts (MPE).Methods: The survey was conducted using an electronic questionnaire with 10 sections, for a total of 43 multiple choice or open questions. Data regarding general information, model of installed scanners, contract of maintenance and phantoms available were collected. The focal part of the questionnaire concerned the QC protocol adopted and accreditation programs.Results: 123 answers from 24 countries were collected. 90.2% of the respondents are affiliated as staff MPEs; 45% have non-digital TOF PET/CT scanners with a contract of maintenance (97.6%). In 98.4% and 86.8% of responding centres a sealed source for daily QC and the NEMA Image Quality Phantom were present. 94.3% of respondents perform daily QC according to manufacturer recommendations, while NEMA Tests are not performed routinely (51.2%). 56.1% of the respondents have scanners accredited by a national or international organization. 56% of the centres perform annual CT tests, while more than 90% do not perform any MRI QCs.Conclusions: The results of the survey show that there is a lack of harmonization in the PET QC procedures across Europe. The information obtained will guide the WG in proposing a guideline containing a set of measurements suitable for the clinical routine

Role of radiomic analysis of [18F]fluoromethylcholine PET/CT in predicting biochemical recurrence in a cohort of intermediate and high risk prostate cancer patients at initial staging

AimTo study the feasibility of radiomic analysis of baseline [F-18]fluoromethylcholine positron emission tomography/computed tomography (PET/CT) for the prediction of biochemical recurrence (BCR) in a cohort of intermediate and high-risk prostate cancer (PCa) patients.Material and methodsSeventy-four patients were prospectively collected. We analyzed three prostate gland (PG) segmentations (i.e., PG(whole): whole PG; PG(41%): prostate having standardized uptake value - SUV > 0.41*SUVmax; PG(2.5): prostate having SUV > 2.5) together with three SUV discretization steps (i.e., 0.2, 0.4, and 0.6). For each segmentation/discretization step, we trained a logistic regression model to predict BCR using radiomic and/or clinical features.ResultsThe median baseline prostate-specific antigen was 11 ng/mL, the Gleason score was > 7 for 54% of patients, and the clinical stage was T1/T2 for 89% and T3 for 9% of patients. The baseline clinical model achieved an area under the receiver operating characteristic curve (AUC) of 0.73. Performances improved when clinical data were combined with radiomic features, in particular for PG(2.5) and 0.4 discretization, for which the median test AUC was 0.78.ConclusionRadiomics reinforces clinical parameters in predicting BCR in intermediate and high-risk PCa patients. These first data strongly encourage further investigations on the use of radiomic analysis to identify patients at risk of BCR

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.Peer ReviewedObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (published version

Assessment of dose increase after administration of radiopharmaceuticals prepared with cyclotron-produced 99mTc

Technetium-99m (99mTc) is currently available from 99Mo/99mTc generators as the \u3b2-decay product of 99Mo (T\ubd=66 h). Nowadays, 99Mo is mostly obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct production of 99mTc via 100Mo(p,2n)99mTc reaction using medical cyclotrons has the potential to be both reliable and relatively costeffective. However, results showed that the extracted 99mTc from the proton-bombarded 100Mo-enriched target contains small quantities of several Tc radioisotopes (93mTc, 93Tc, 94Tc, 94mTc, 95Tc, 95mTc, 96Tc and 97mTc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotronproduced 99mTc (CP-99mTc) using 99.05% 100Mo-enriched metallic targets. Four 99mTc radiopharmaceuticals (pertechnetate, sestamibi (MIBI), hexamethylpropylene- amine oxime (HMPAO) and disodium etidronate (HEDP)), were considered in this study. The biokinetic models reported by the International Commission on Radiological Protection (ICRP) for each radiopharmaceutical were used to define the main source organs and to calculate the number of disintegrations per MBq that occurred in each source organ (Nsource) for each Tc radioisotope present in the CP-99mTc solution. Then, target organ equivalent doses and effective dose were calculated for each Tc radioisotope with the OLINDA/EXM software versions 1.1 and 2.0, using the calculated Nsource values and the adult male phantom as program inputs. Total effective dose produced by all Tc isotopes impurities present in the CP-99mTc solution was calculated using the fraction of total activity corresponding to each radioisotope generated by the bombardment of 100Mo-enriched (99.05%) metallic target. Finally, the effective obtained dose was compared with the effective dose delivered by the generator-produced 99mTc. The total effective dose increases of CP-99mTc radiopharmaceuticals, calculated with both versions of the OLINDA software, remained within the 10% limit in all cases, from 6 up to 12 hours after end of bombardment (EOB). The Tc radioisotopes with the highest concentration in the CP-99mTc solution at EOB are 94mTc and 93mTc. However, their contribution to DI 6 hours after EOB is minimal, due to their short half-lives. 96Tc is the radioisotope with the largest contribution to the effective DI, followed by 95Tc and 94Tc, although their concentration in the CP-99mTc solution is 5 times less than 94mTc and 93mTc at the EOB. This is due to the types of their emissions and relatively long half-lives. The increase in the radiation dose caused by the other Tc radioisotopes contained in produced CP-99mTc, as described here, is quite low. Although the concentrations of the 94Tc and 95Tc radioisotopes in the CP-99mTc solution exceed the limits established by the European Pharmacopoeia, CP-99mTc radiopharmaceuticals could be used in routine nuclear medicine diagnostic studies if administered from 6 to 12 hours after the EOB; thus, maintaining the effective DI within the 10% limit

The Italian young medical physicist scenario: Results from the young AIFM group survey

International audiencePurposeThe young working group of the Italian Association of Medical and Health Physics (AIFM) designed a survey to assess the current situation of the under 35 AIFM members.MethodsAn online survey including 65 questions was designed to gather personal information, educational issues, working and research experience, and to evaluate the AIFM activities. The survey was distributed to the under 35 members between November 2022 and February 2023, through the young AIFM mailing list and social media.Results160 answers from 230 affiliates (70%, 31 years median age) were obtained. The results highlighted that 87% of the respondents had a fixed term/permanent employment, mainly in public hospitals (58%).Regarding Medical Physicists (MPs) training, 54% of the students left their region of origin due to the training plan (40%) and the availability of scholarships (25%) in the chosen university. Most of the respondents have no Radiation Protection Expert title, while the remaining 20%, 6%, and 3% are qualified to the first, second, and third level, respectively.Several young MPs (62.2%) were involved in research activities; however, only 28% had teaching experience, mainly within their workplace (20%, safety courses), during AIFM courses (4%), or university lectures (3%).ConclusionsThis survey reported the current situation of the under 35 AIFM members, highlighting the “brain drain” phenomenon from the south to the north of Italy, mainly due to the lack of post-graduate schools, scholarships, and job opportunities. The obtained results will help the future working program of the AIFM