Quantitative Imaging in Radionuclide Therapy with Lutetium-177 : Towards Traceability and Comparability

Abstract

Radionuclide therapy involving 177Lu-labelled somatostatin analogues for the treatment of neuroendocrine tumours is
increasing. While the treatment is currently administered according to a standard protocol, patient-specific treatments
based on dosimetry are believed to be beneficial. However, commonly adopted dosimetry procedures are lacking, and
locally developed dosimetry methods are used, which makes pooling and comparisons of dosimetry data between
sites challenging. In this thesis, procedures and protocols are presented to achieve traceability and comparability in
activity measurements as a basis for dosimetry in radionuclide therapy.
In Paper I, a procedure for cross-calibration of activity meters with traceability to primary standards was presented.
The procedure was especially developed when national services for traceable calibrations are lacking. The method
enabled local cross-calibrations for any geometry considered relevant. Furthermore, a method to estimate the amount
of activity adsorption onto container walls was presented in Paper IV. Adsorption would lead to a discrepancy
between prepared reference and actual activity concentration in phantoms which results in inaccuracies of
quantitative single photon emission computed tomography (SPECT). Carrier solutions used to prevent adsorption for
177LuCl3 was confirmed both in small test tubes and larger container volumes. Carrier solutions for the radiolabelled
peptides 177Lu-DOTA-TATE/TOC, were identified which enable phantom measurements using surplus of the
radiopharmaceuticals.
To evaluate quantitative SPECT methods, a 3D-printing grid-technique was developed and combined with
anthropomorphic phantoms in Paper II. Non-uniform activity distributions were created without the use of nonradioactive
walls between compartments. Activity meters calibrated traceably to primary standards from Paper I and
the realistic phantoms from Paper II were used to design a validation protocol for quantitative SPECT as a basis for
177Lu-PRRT dosimetry in a multicentre setting in Paper III. The validation protocol was considered valuable for both
centralised and locally performed patient dosimetry.
Together, these papers formulate methods and procedures for achieving comparability in radionuclide therapy.

Abstract (Swedish)

Radionuclide therapy involving 177Lu-labelled somatostatin analogues for the treatment of neuroendocrine tumours is
increasing. While the treatment is currently administered according to a standard protocol, patient-specific treatments
based on dosimetry are believed to be beneficial. However, commonly adopted dosimetry procedures are lacking, and
locally developed dosimetry methods are used, which makes pooling and comparisons of dosimetry data between
sites challenging. In this thesis, procedures and protocols are presented to achieve traceability and comparability in
activity measurements as a basis for dosimetry in radionuclide therapy.
In Paper I, a procedure for cross-calibration of activity meters with traceability to primary standards was presented.
The procedure was especially developed when national services for traceable calibrations are lacking. The method
enabled local cross-calibrations for any geometry considered relevant. Furthermore, a method to estimate the amount
of activity adsorption onto container walls was presented in Paper IV. Adsorption would lead to a discrepancy
between prepared reference and actual activity concentration in phantoms which results in inaccuracies of
quantitative single photon emission computed tomography (SPECT). Carrier solutions used to prevent adsorption for
177LuCl3 was confirmed both in small test tubes and larger container volumes. Carrier solutions for the radiolabelled
peptides 177Lu-DOTA-TATE/TOC, were identified which enable phantom measurements using surplus of the
radiopharmaceuticals.
To evaluate quantitative SPECT methods, a 3D-printing grid-technique was developed and combined with
anthropomorphic phantoms in Paper II. Non-uniform activity distributions were created without the use of nonradioactive
walls between compartments. Activity meters calibrated traceably to primary standards from Paper I and
the realistic phantoms from Paper II were used to design a validation protocol for quantitative SPECT as a basis for
177Lu-PRRT dosimetry in a multicentre setting in Paper III. The validation protocol was considered valuable for both
centralised and locally performed patient dosimetry.
Together, these papers formulate methods and procedures for achieving comparability in radionuclide therapy.

• author: Jessen, Lovisa
• supervisor: Katarina Sjögreen Gleisner; Johan Ruben Gustafsson; Michael Ljungberg
• opponent: Dr. Murray, Iain, Joint Department of Physics, The Royal Marsden NHS Foundation Trust, London, UK
• organization: Medical Radiation Physics, Lund; Nuclear Medicine Physics (research group)
• publishing date: 2025
• type: Thesis
• publication status: published
• subject: Natural Sciences; Physical Sciences
• keywords: Sjukhusfysik, Nukleärmedicin, Radionuklidterapi, medical radiation physics, nuclear medicine, Radionuclide therapy
• pages: 78 pages
• defense location: Föreläsningssal F2, Centralblocket, Entrégatan 7, Skånes Universitetssjukhus, Lund.
• defense date: 2025-10-24 09:00:00
• ISBN: 978-91-8104-608-3
• ISBN: 978-91-8104-609-0
• language: Swedish
• LU publication?: yes
• id: 720dd137-db3e-47d0-addd-92392e78b287
• date added to LUP: 2025-09-25 10:50:32
• date last changed: 2025-09-29 10:37:59