MIRD Pamphlet No. 24: Guidelines for Quantitative <sup>131</sup>I SPECT in Dosimetry Applications

Dewaraja, Yuni K.; Ljungberg, Michael; Green, Alan J.; Zanzonico, Pat; Frey, Eric; Bolch, Wesley E.; Brill, A. B.; Dunphy, Mark; Fisher, Darrell R.; Howell, Roger W.; Meredith, Ruby F.; Sgouros, George; Wessels, Barry W.

doi:10.2967/jnumed.113.122390

Cited by 133 publications

(129 citation statements)

References 27 publications

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“…The first method used 6 iterations with 8 subsets and triple-energy-window scatter correction (SC 6i8s), the second method used 6 iterations with 8 subsets and did not incorporate scatter correction (no-SC 6i8s), and the third method used 30 iterations with 8 subsets and triple-energy-window scatter correction (SC 30i8s). Reconstruction with 6 iterations and 8 subsets was performed to allow comparison with the clinical trial running at our hospital (14), and reconstruction with 30 iterations and 8 subsets was included for increased contrast recovery at the cost of increased image noise (18,19).…”

Section: Reconstructionmentioning

confidence: 99%

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

et al. 2015

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Radioiodine therapy with 131 I is used for treatment of suspected recurrence of differentiated thyroid carcinoma. Pretherapeutic 124 I PET/CT with a low activity (∼1% of 131 I activity) can be performed to determine whether uptake of 131 I, and thereby the desired therapeutic effect, may be expected. However, false-negative 124 I PET/CT results as compared with posttherapeutic 131 I SPECT/CT have been reported by several groups. The purpose of this study was to investigate whether the reported discrepancies may be ascribed to a difference in lesion detectability between 124 I PET/CT and 131 I SPECT/CT and, hence, whether the administered 124 I activity is sufficient to achieve equal detectability. Methods: Phantom measurements were performed using the National Electrical Manufacturers Association 2007 image-quality phantom. As a measure of detectability, the contrast-to-noise ratio was calculated. The 124 I activity was expressed as the percentage of 131 I activity required to achieve the same contrast-to-noise ratio. This metric was defined as the detectability equivalence percentage (DEP). Results: Because lower DEPs were obtained for smaller spheres, a relatively low 124 I activity was sufficient to achieve similar lesion detectability between 124 I PET/CT and 131 I SPECT/CT. DEP was 1.5%, 1.9%, 1.9%, 4.4%, 9.0%, and 16.2% for spheres with diameters of 10, 13, 17, 18, 25, and 37 mm, respectively, for attenuation-and scatter-corrected SPECT versus point-spread function (PSF) model-based and time-of-flight (TOF) PET. For no-PSF no-TOF PET, DEP was 3.6%, 2.1%, 3.5%, 7.8%, 15.1%, and 23.3%, respectively. Conclusion: A relatively low 124 I activity of 74 MBq (∼1% of 131 I activity) is sufficient to achieve similar lesion detectability between 124 I PSF TOF PET/CT and 131 I SPECT/CT for small spheres (#10 mm), since the reported DEPs are close to 1%. False-negative 124 I PET/CT results as compared with posttherapeutic 131 I SPECT/CT may be ascribed to differences in detectability for large lesions (.10 mm) and for no-PSF no-TOF PET, since DEPs are greater than 1%. On the basis of DEPs of 3.5% for lesion diameters of up to 17 mm on no-PSF no-TOF PET, 124 I activities as high as 170 MBq may be warranted to obtain equal detectability.

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Section: Reconstructionmentioning

confidence: 99%

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

et al. 2015

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“…40,41 Corrections for clinical factors, including involuntary (e.g., respiration), or voluntary motions, were only recently proposed. 40,42,43 Hence, the more sophisticated methods to correct SPECT counts to activity are not yet in widespread use, as full corrections of physical factors are not always available, and correction to respiratory motion is possible only in few research centers. Moreover, the hybrid SPECT-CT scanners are not available in all centers.…”

Section: Introductionmentioning

confidence: 99%

Impact of SPECT corrections on 3D‐dosimetry for liver transarterial radioembolization using the patient relative calibration methodology

et al. 2016

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Purpose: Many centers aim to plan liver transarterial radioembolization (TARE) with dosimetry, even without CT-based attenuation correction (AC), or with unoptimized scatter correction (SC) methods. This work investigates the impact of presence vs absence of such corrections, and limited spatial resolution, on 3D dosimetry for TARE. Methods: Three voxelized phantoms were derived from CT images of real patients with different body sizes. Simulations of 99m Tc-SPECT projections were performed with the SIMIND code, assuming three activity distributions in the liver: uniform, inside a "liver's segment," or distributing multiple uptaking nodules ("nonuniform liver"), with a tumoral liver/healthy parenchyma ratio of 5:1. Projection data were reconstructed by a commercial workstation, with OSEM protocol not specifically optimized for dosimetry (spatial resolution of 12.6 mm), with/without SC (optimized, or with parameters predefined by the manufacturer; dual energy window), and with/without AC. Activity in voxels was calculated by a relative calibration, assuming identical microspheres and 99m Tc-SPECT counts spatial distribution. 3D dose distributions were calculated by convolution with lesions and healthy parenchyma from different reconstructions were compared with those obtained from the reference biodistribution (the "gold standard," GS), assessing differences for D95%, D70%, and D50% (i.e., minimum value of the absorbed dose to a percentage of the irradiated volume). γ tool analysis with tolerance of 3%/13 mm was used to evaluate the agreement between GS and simulated cases. The influence of deep-breathing was studied, blurring the reference biodistributions with a 3D anisotropic gaussian kernel, and performing the simulations once again. Results: Differences of the dosimetric indicators were noticeable in some cases, always negative for lesions and distributed around zero for parenchyma. Application of AC and SC reduced systematically the differences for lesions by 5%-14% for a liver segment, and by 7%-12% for a nonuniform liver. For parenchyma, the data trend was less clear, but the overall range of variability passed from −10%/40% for a liver segment, and −10%/20% for a nonuniform liver, to −13%/6% in both cases. Applying AC, SC with preset parameters gave similar results to optimized SC, as confirmed by γ tool analysis. Moreover, γ analysis confirmed that solely AC and SC are not sufficient to obtain accurate 3D dose distribution. With breathing, the accuracy worsened severely for all dosimetric indicators, above all for lesions: with AC and optimized SC, −38%/−13% in liver's segment, −61%/−40% in the nonuniform liver. For parenchyma, D50% resulted always less sensitive to breathing and sub-optimal correction methods (difference overall range: −7%/13%). Conclusions: Reconstruction protocol optimization, AC, SC, PVE and respiratory motion corrections should be implemented to obtain the best possible dosimetric accuracy. On the other side, thanks to the relative calibration, D50% inaccuracy for the healthy paren...

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“…to destroy residual cervical thyroid tissues [2]. Therapy efficiency depends on the activity of administered radioiodine, remaining thyroid masses and 131 I biodistribution [2].…”

Section: Introductionmentioning

confidence: 99%

“…It is the only method that determines residual activity in organs, through region of interest (ROI) or volume of interest (VOI) quantification [2,7]. For dosimetry purposes, at least 3 points of different acquisition times are necessary to account for the retention and elimination stages [8].…”

Section: Introductionmentioning

confidence: 99%

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Impact of the counts density of calibration image and the image reconstruction parameters in 131I SPECT image quantification

et al. 2018

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131 I) has been used for diagnosis and therapy in Nuclear Medicine Centers in Brazil for more than 50 years.The present study aims to investigate the impact of the counts density and the reconstruction parameters in the calibration factor determination and in the image quantification, considering the reality of Brazilian dosimetry studies.For this task, images were quantified using calibration images with high and low counts density and reconstructed adopting two different parameters approaches, usually employed in patients images. SPECT quantification results presented in this work follow other previous 131 I SPECT studies and suggest that, due to the long time interval between the first e last images, as required by the Brazilian guideline, the image quantification accuracy can be improved if the counts density of calibration images is considered.

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MIRD Pamphlet No. 24: Guidelines for Quantitative ¹³¹I SPECT in Dosimetry Applications

Cited by 133 publications

References 27 publications

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

Impact of SPECT corrections on 3D‐dosimetry for liver transarterial radioembolization using the patient relative calibration methodology

Impact of the counts density of calibration image and the image reconstruction parameters in 131I SPECT image quantification

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MIRD Pamphlet No. 24: Guidelines for Quantitative 131I SPECT in Dosimetry Applications

Cited by 133 publications

References 27 publications

Quantitative Comparison of 124I PET/CT and 131I SPECT/CT Detectability

Quantitative Comparison of 124I PET/CT and 131I SPECT/CT Detectability

Impact of SPECT corrections on 3D‐dosimetry for liver transarterial radioembolization using the patient relative calibration methodology

Impact of the counts density of calibration image and the image reconstruction parameters in 131I SPECT image quantification

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MIRD Pamphlet No. 24: Guidelines for Quantitative ¹³¹I SPECT in Dosimetry Applications

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability

Quantitative Comparison of ¹²⁴I PET/CT and ¹³¹I SPECT/CT Detectability