| Dokumentenart: | Artikel | ||||
|---|---|---|---|---|---|
| Titel eines Journals oder einer Zeitschrift: | Zeitschrift für Medizinische Physik | ||||
| Verlag: | ELSEVIER | ||||
| Ort der Veröffentlichung: | AMSTERDAM | ||||
| Band: | 30 | ||||
| Nummer des Zeitschriftenheftes oder des Kapitels: | 2 | ||||
| Seitenbereich: | S. 116-134 | ||||
| Datum: | 2020 | ||||
| Institutionen: | Biologie und Vorklinische Medizin > Institut für Biophysik und physikalische Biochemie Biologie und Vorklinische Medizin > Institut für Biophysik und physikalische Biochemie > Prof. Dr. Elmar Lang | ||||
| Identifikationsnummer: |
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| Stichwörter / Keywords: | RADIONUCLIDE THERAPY; DOSIMETRY; VALIDATION; KIDNEY; Voxelwise; Time-activity-curve; Nuclear medicine; Dosimetry | ||||
| Dewey-Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik > 570 Biowissenschaften, Biologie | ||||
| Status: | Veröffentlicht | ||||
| Begutachtet: | Ja, diese Version wurde begutachtet | ||||
| An der Universität Regensburg entstanden: | Ja | ||||
| Dokumenten-ID: | 50056 |
Web of ScienceZusammenfassung
Background: Currently, there is a high interest in Lu-177 targeted radionuclide therapies, which could be attributed to favorable results obtained from Lu-177 compounds targeting neuro-endocrine and prostate tumors. SPECT based dosimetry could be used for deriving dose values for individual voxels, as is the standard in external-beam radiation-therapy (EBRT). For this a time-activity-curve (TAC) ...
Zusammenfassung
Background: Currently, there is a high interest in Lu-177 targeted radionuclide therapies, which could be attributed to favorable results obtained from Lu-177 compounds targeting neuro-endocrine and prostate tumors. SPECT based dosimetry could be used for deriving dose values for individual voxels, as is the standard in external-beam radiation-therapy (EBRT). For this a time-activity-curve (TAC) at voxel resolution and also a voxel-wise modeling of radiation energy deposition are necessary. But a voxel-wise determination of TACs is problematic, since several confounding factors exist, such as e.g. poor count-statistics or registration inaccuracies, which add noise to the observed activity states. A particle filter (PF) is a class of methods which applies regularization based on a model of the temporal evolution of activity states. The aim of this study is to introduce the application of PFs for de-noising of per-voxel time-activity curves. Methods: We applied a PF for de-noising the TACs of 26 patients, who underwent Lu-177-DOTATOC or -PSMA therapy. The TACs were obtained from fiilly-quantitative, serial SPECT (/CT) data, acquired at 4 h, 24 h, 48 h, 72 h p.i. The model used in the PF was a mono-exponential decay and its free parameters were determined based on objective criteria. The time-integrated activities (TIA) resulting from the PF (PFF) were compared to the results of a mono-exponential fit (SF) of individual voxels in several volumes of interest (kidneys, spleen, tumors). Additionally, an organ-averaged TIA was derived from whole-organ VOIs and subsequent curve-fitting. This whole-organ TIA was also compared to the whole-organ TIAs obtained from summation of the voxel-wise TIAs from PFF and SF. Results: The number of particles was set to 1000. Optimal values for noise of observations and noise of the model were 0.25 and 0.5, respectively The deviation of whole-organ TIAs from conventional organ-based dosimetry and the summation of the voxel-wise TIAs was substantial for SF (kidneys -22.3%, spleen -49.6%, tumor -60.0%), as well as for PFF (kidneys -37.1%, spleen -57.9%, tumor -70.9%). The distribution of voxel-wise half-lives resulting from the PFF method was considerably closer to the organ-averaged value, and the number of implausibly long half-lives (>physical HL) was reduced. Conclusion: The PFF leads to voxel-wise half-lives, which are more plausible than those resulting from SF. However, one has to admit that voxel-wise fitting generally leads to considerable deviations from the organ-averaged TIA as obtained by conventional whole-organ evaluation. Unfortunately, we did not have ground-truth TIA of our patient data and proper ground-truth could even be impossible to obtain. Nevertheless, there are strong indicators that particle filtering can be used for reducing voxel-wise TAC noise.
Metadaten zuletzt geändert: 11 Okt 2021 12:50
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