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  1. Article ; Online: 3D printing 18F radioactive phantoms for PET imaging

    Daniel Gillett / Daniel Marsden / Safia Ballout / Bala Attili / Nick Bird / Sarah Heard / Mark Gurnell / Iosif A. Mendichovszky / Luigi Aloj

    EJNMMI Physics, Vol 8, Iss 1, Pp 1-

    2021  Volume 14

    Abstract: Abstract Purpose Phantoms are routinely used in molecular imaging to assess scanner performance. However, traditional phantoms with fillable shapes do not replicate human anatomy. 3D-printed phantoms have overcome this by creating phantoms which ... ...

    Abstract Abstract Purpose Phantoms are routinely used in molecular imaging to assess scanner performance. However, traditional phantoms with fillable shapes do not replicate human anatomy. 3D-printed phantoms have overcome this by creating phantoms which replicate human anatomy which can be filled with radioactive material. The problem with these is that small objects suffer to a greater extent than larger objects from the effects of inactive walls, and therefore, phantoms without these are desirable. The purpose of this study was to explore the feasibility of creating resin-based 3D-printed phantoms using 18F. Methods Radioactive resin was created using an emulsion of printer resin and 18F-FDG. A series of test objects were printed including twenty identical cylinders, ten spheres with increasing diameters (2 to 20 mm), and a double helix. Radioactive concentration uniformity, printing accuracy and the amount of leaching were assessed. Results Creating radioactive resin was simple and effective. The radioactive concentration was uniform among identical objects; the CoV of the signal was 0.7% using a gamma counter. The printed cylinders and spheres were found to be within 4% of the model dimensions. A double helix was successfully printed as a test for the printer and appeared as expected on the PET scanner. The amount of radioactivity leached into the water was measurable (0.72%) but not visible above background on the imaging. Conclusions Creating an 18F radioactive resin emulsion is a simple and effective way to create accurate and complex phantoms without inactive walls. This technique could be used to print clinically realistic phantoms. However, they are single use and cannot be made hollow without an exit hole. Also, there is a small amount of leaching of the radioactivity to take into consideration.
    Keywords PET ; 3D printing ; Phantoms ; Quality control ; 18F ; Medical physics. Medical radiology. Nuclear medicine ; R895-920
    Subject code 500
    Language English
    Publishing date 2021-04-01T00:00:00Z
    Publisher SpringerOpen
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article ; Online: Development of a bespoke phantom to optimize molecular PET imaging of pituitary tumors

    Daniel Gillett / Daniel Marsden / Rosy Crawford / Safia Ballout / James MacFarlane / Merel van der Meulen / Bethany Gillett / Nick Bird / Sarah Heard / Andrew S. Powlson / Thomas Santarius / Richard Mannion / Angelos Kolias / Ines Harper / Iosif A. Mendichovszky / Luigi Aloj / Heok Cheow / Waiel Bashari / Olympia Koulouri /
    Mark Gurnell

    EJNMMI Physics, Vol 10, Iss 1, Pp 1-

    2023  Volume 23

    Abstract: Abstract Background Image optimization is a key step in clinical nuclear medicine, and phantoms play an essential role in this process. However, most phantoms do not accurately reflect the complexity of human anatomy, and this presents a particular ... ...

    Abstract Abstract Background Image optimization is a key step in clinical nuclear medicine, and phantoms play an essential role in this process. However, most phantoms do not accurately reflect the complexity of human anatomy, and this presents a particular challenge when imaging endocrine glands to detect small (often subcentimeter) tumors. To address this, we developed a novel phantom for optimization of positron emission tomography (PET) imaging of the human pituitary gland. Using radioactive 3D printing, phantoms were created which mimicked the distribution of 11C-methionine in normal pituitary tissue and in a small tumor embedded in the gland (i.e., with no inactive boundary, thereby reproducing the in vivo situation). In addition, an anatomical phantom, replicating key surrounding structures [based on computed tomography (CT) images from an actual patient], was created using material extrusion 3D printing with specialized filaments that approximated the attenuation properties of bone and soft tissue. Results The phantom enabled us to replicate pituitary glands harboring tumors of varying sizes (2, 4 and 6 mm diameters) and differing radioactive concentrations (2 ×, 5 × and 8 × the normal gland). The anatomical phantom successfully approximated the attenuation properties of surrounding bone and soft tissue. Two iterative reconstruction algorithms [ordered subset expectation maximization (OSEM); Bayesian penalized likelihood (BPL)] with a range of reconstruction parameters (e.g., 3, 5, 7 and 9 OSEM iterations with 24 subsets; BPL regularization parameter (β) from 50 to 1000) were tested. Images were analyzed quantitatively and qualitatively by eight expert readers. Quantitatively, signal was the highest using BPL with β = 50; noise was the lowest using BPL with β = 1000; contrast was the highest using BPL with β = 100. The qualitative review found that accuracy and confidence were the highest when using BPL with β = 400. Conclusions The development of a bespoke phantom has allowed the identification of optimal ...
    Keywords 3D printing radioactive phantom ; Optimization of molecular PET imaging ; Pituitary tumors/adenomas ; Medical physics. Medical radiology. Nuclear medicine ; R895-920
    Subject code 616
    Language English
    Publishing date 2023-06-01T00:00:00Z
    Publisher SpringerOpen
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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