Standardisation and decay data of 177Lu and 188Re

Purpose: The combination of single photon emission computed tomography (SPECT) and computer tomography (CT) that incorporates iterative reconstruction algorithms with attenuation and scatter correction should facilitate accurate non-invasive quantitative imaging. Quantitative SPECT (QSPECT) may improve diagnostic ability and could be useful for many applications including dosimetry assessment. Using 177Lu, we developed a QSPECT method using a commercially available SPECT/CT system. Methods: Serial SPECT of 177Lu sources (89–12,400 MBq) were acquired with multiple contiguous energy windows along with a co-registered CT, and were reconstructed using an iterative algorithm with attenuation and scatter correction. Camera sensitivity (based on reconstructed SPECT count rate) and dead-time (based on wide-energy spectrum count rate) were resolved by non-linear curve fit. Utilizing these parameters, a SPECT dataset can be converted to a QSPECT dataset allowing quantitation in Becquerels per cubic centimetre or standardized uptake value (SUV). Validation QSPECT/CT studies were performed on a 177Lu cylindrical phantom (7 studies) and on 5 patients (6 studies) who were administered a therapeutic dose of [177Lu]octreotate. Results: The QSPECT sensitivity was 1.08 × 10−5 ± 0.02 × 10−5 s−1 Bq−1. The paralyzing dead-time constant was 0.78 ± 0.03 µs. The measured total activity with QSPECT deviated from the calibrated activity by 5.6 ± 1.9% and 2.6 ± 1.8%, respectively, in phantom and patients. Dead-time count loss up to 11.7% was observed in patient studies. Conclusion: QSPECT has high accuracy both in our phantom model and in clinical practice following [177Lu]octreotate therapy. This has the potential to yield more accurate dosimetry estimates than planar imaging and facilitate therapeutic response assessment. Validating this method with other radionuclides could open the way for many other research and clinical applications.

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“…The main photopeak of 177 Lu (208 keV; 10.4% probability) [ 10 ] was the photopeak of interest. Fig.…”

Section: Methodsmentioning

confidence: 99%

Quantitative 177 Lu SPECT (QSPECT) imaging using a commercially available SPECT/CT system

et al. 2011

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“…Two of these g-photons, with the energies of 112.9 (6.17%) and 208.4 keV (10.36%), have been successfully used in 177 Lu imaging studies. Table 1 summarizes information about 177 Lu g-photon energies and intensities based on previous studies (22)(23)(24)(25)(26)(27)(28). Moreover, bremsstrahlung radiation generated by interactions of b 2 -particles with tissue may be observed.…”

Section: Decay Of 177 Lumentioning

confidence: 99%

MIRD Pamphlet No. 26: Joint EANM/MIRD Guidelines for Quantitative ¹⁷⁷Lu SPECT Applied for Dosimetry of Radiopharmaceutical Therapy

et al. 2015

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The accuracy of absorbed dose calculations in personalized internal radionuclide therapy is directly related to the accuracy of the activity (or activity concentration) estimates obtained at each of the imaging time points. MIRD Pamphlet no. 23 presented a general overview of methods that are required for quantitative SPECT imaging. The present document is next in a series of isotope-specific guidelines and recommendations that follow the general information that was provided in MIRD 23. This paper focuses on 177 Lu (lutetium) and its application in radiopharmaceutical therapy. Theradi onuclide 177 Lu (lutetium) has been proven useful in several targeted radionuclide therapies because of its favorable decay characteristics and the possibility of reliable labeling of biomolecules used for tumor targeting. Initially, 177 Lu was used in a colloidal form for interstitial injections for sterilization of peritumoral lymph nodes (1). A second important clinical application of 177 Lu has been for peptide receptor radionuclide therapy (PRRT) with 177 Lu-DOTATATE and other structurally related peptides. The PRRT use in treatment of neuroendocrine tumors (NETs) is motivated by the fact that the carrier peptide, octreotate, shows highaffinity binding to somatostatin receptors, which are overexpressed on the cell surface of many NETs (2-6). Furthermore, 177 Lu has been used in radioimmunotherapy clinical trials to label different kinds of monoclonal antibodies (7-15).There is a growing body of evidence that radionuclide therapy should follow patient-specific planning protocols, similar to those that are being routinely used in external-beam radiation therapy. Recent literature reviews show correlations between absorbed dose and tumor response as well as normal-tissue toxicity (16). Such correlations indicate that treatments should be based on personalized dosimetry, aiming to deliver therapeutically effective absorbed doses to tumors, while keeping doses to organs at risk below the threshold levels for deterministic adverse effects. In clinical PRRT studies, the primary adverse effects have been mainly renal and hematologic toxicities (2,6).Although several studies have reported estimates of absorbed doses (4,7-9,12) for 177 Lu-DOTATATE PRRT and 177 Lu radioimmunotherapy, most of these estimates have been based on planar imaging and conjugate-view activity quantification. Planar imaging, however, is known to have inherent limitations regarding the accuracy of activity quantification (17). As a result, an increasing number of clinical dosimetry protocols currently include 177 Lu SPECT/CT imaging studies (15,(17)(18)(19) because of their superior accuracy. Comparisons of renal dose estimates in 177 Lu-DOTATATE PRRT based on planar imaging and SPECT/CT, for example, have been reported (17,20) and are summarized in Cremonesi et al. (21).This document presents a set of guidelines outlining data acquisition protocols and image reconstruction techniques that are recommended for quantitative 177 Lu SPECT imaging. The guidelines are...

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“…Several authors have reported the activity ratio between the activity of 177m Lu and the activity of 177 Lu in solution: A( 177m Lu)/A( 177 Lu)= 0.007% [11] A( 177m Lu)/A( 177 Lu)= 0.031% [15], A( 177m Lu)/A( 177 Lu)= 0.035% [17] and A( 177m Lu)/A( 177 Lu)= 0.02% [19].…”

Section: Discussionmentioning

confidence: 99%

“…There have been 14 previous publications reporting half-life measurements of 177 Lu [6][7][8][9][10][11][12][13][14][15][16][17][18][19], which are summarised in Table 1. Of these only the measurement reported by Dryak et al [18] has used 177 Lu from production method 2) and therefore not required corrections for the 177m Lu impurity.…”

Section: Introductionmentioning

confidence: 99%

Half-life measurement of the medical radioisotope ¹⁷⁷Lu produced from the ¹⁷⁶Yb(n,γ) reaction

2017

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Abstract. 177 Lu is a medium energy beta-emitter commonly used in Nuclear Medicine for radiotherapeutic applications. In this work, the half-life of 177 Lu has been measured using a re-entrant ionisation chamber over a period of 82 days (approximately 12 half-lives). Unlike the majority of previous studies, the material used in this work was produced via the 176 Yb(n,γ ) 177 Yb reaction followed by the β-decay to 177 Lu, producing insignificant quantities of 177m Lu. This has resulted in the most precise half-life measurement of 177 Lu to date. A half-life of 6.6430 (11) days has been determined. This value is in statistical agreement with the currently recommended half-life of 6.6463 (15) days (z-score = 1.8).

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Standardisation and decay data of 177Lu and 188Re

Cited by 47 publications

References 21 publications

Quantitative 177 Lu SPECT (QSPECT) imaging using a commercially available SPECT/CT system

Quantitative 177 Lu SPECT (QSPECT) imaging using a commercially available SPECT/CT system

MIRD Pamphlet No. 26: Joint EANM/MIRD Guidelines for Quantitative ¹⁷⁷Lu SPECT Applied for Dosimetry of Radiopharmaceutical Therapy

Half-life measurement of the medical radioisotope ¹⁷⁷Lu produced from the ¹⁷⁶Yb(n,γ) reaction

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Standardisation and decay data of 177Lu and 188Re

Cited by 47 publications

References 21 publications

Quantitative 177 Lu SPECT (QSPECT) imaging using a commercially available SPECT/CT system

Quantitative 177 Lu SPECT (QSPECT) imaging using a commercially available SPECT/CT system

MIRD Pamphlet No. 26: Joint EANM/MIRD Guidelines for Quantitative 177Lu SPECT Applied for Dosimetry of Radiopharmaceutical Therapy

Half-life measurement of the medical radioisotope 177Lu produced from the 176Yb(n,γ) reaction

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MIRD Pamphlet No. 26: Joint EANM/MIRD Guidelines for Quantitative ¹⁷⁷Lu SPECT Applied for Dosimetry of Radiopharmaceutical Therapy

Half-life measurement of the medical radioisotope ¹⁷⁷Lu produced from the ¹⁷⁶Yb(n,γ) reaction