Evaluation of sequential SPECT and CT for targeted radionuclide therapy dosimetry

Li, Tiantian; Wu, Nien Yun; Song, Na; Mok, Greta S. P.

doi:10.1007/s12149-017-1218-8

Cited by 10 publications

(13 citation statements)

References 33 publications

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“…Integrated CT in SPECT/CT can be used for attenuation correction (AC) in SPECT reconstruction to improve quantitative accuracy, and provide anatomical reference for the activity uptakes in general. For TRT dosimetry, CT data can be further used in segmentations of tumors and critical organs, or registrations to reduce the misalignments among serial scans [4,5]. However, the accuracy of registration between SPECT and CT data is limited by certain voluntary and involuntary motion since CT scans take couple seconds while SPECT imaging needs at least several minutes.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Mismatch between SPECT and CT Images on Quantitative Activity Estimation – A Simulation Study

Lyu

Chen

Mok

2021

Preprint

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Background: Quantitative activity estimation is essential in targeted radionuclide therapy dosimetry. Misregistration between SPECT and CT images at the same imaging time point due to patient movement degrades accuracy. This work aims to study the mismatch effects between CT and SPECT data on attenuation correction (AC), volume-of-interest (VOI) delineation and registration for activity estimation.Methods: Nine 4D XCAT phantoms were generated at 1, 24, and 144 hrs post In-111 Zevalin injection, varying in activity distributions, body and organ sizes. Realistic noisy SPECT projections were generated by an analytical projection and reconstructed with quantitative OS-EM method. CT images were shifted from -5 to 5 voxels as well as according to clinical reference corresponding to SPECT images at each time point. For AC effect, mismatched CT images were used for AC in SPECT reconstruction while VOIs were mapped out from matched CTs. For VOI effect, target organs were mapped out using mismatched CTs with matched CTs for AC. For registration effect, non-rigid registrations were performed on sequential mismatched CTs to align corresponding SPECT images, with no AC and VOI mismatch. Bi-exponential curve fitting was performed to obtain time-integrated activity (TIA). Organ activity errors (%OAE) and TIA errors (%TIAE) were calculated.Results: According to clinical reference, %OAE was larger for organs near ribs for AC effect, e.g., -2.58%±0.81% for liver. For VOI effect, %OAE was larger for small and low uptake organs, e.g., -11.94%±10.34% for spleen. %OAE was proportional to mismatch magnitude, e.g., 4.77%±1.41%, 12.01%±3.97% and 42.81%±6.38% for 1-, 2-, and 5-voxel mismatch for lungs. For registration effect, %TIAE were larger when mismatch existed in more numbers of SPECT/CT images, while no substantial difference was observed when using mismatched CT at different time points for registration reference. %TIAE was highest for VOI, followed by registration and AC, e.g., 37.61%±5.08%, 14.25%±7.07% and 1.13%±0.90% respectively for kidneys.Conclusions: The mismatch between CT and SPECT images poses a significant impact on accuracy of quantitative activity estimation in dosimetry, attributed particularly from VOI delineation errors. It is recommended to perform registration between emission and transmission images at the same time point to ensure dosimetric accuracy.

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Section: Introductionmentioning

confidence: 99%

The Effects of Mismatch between SPECT and CT Images on Quantitative Activity Estimation – A Simulation Study

Lyu

Chen

Mok

2021

Preprint

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“…For vCT and rCT protocols, first we semi‐automatically segmented the target organs, that is, liver, spleen, kidneys, and lungs at all time points on respective vCTs and rCTs images. We then applied organ‐by‐organ nonrigid registration . For the conventional 1CT protocol, as some organ‐of‐interest regions cannot be delineated from SPECT images at later time points, whole‐body SPECT registrations were performed while the single CT was used for organ segmentation.…”

Section: Methodsmentioning

confidence: 99%

“…However, SPECT images have relatively poor resolution, high noise levels, and insufficient anatomical information, leading to large uncertainties for image registration and segmentation . Previously, we showed that the use of sequential computed tomography (CT) images for nonrigid registration is superior to sequential SPECT in 3D TRT dosimetry . Nonetheless, CT‐aided dosimetry does require good alignment between SPECT and CT images at each time point.…”

Section: Introductionmentioning

confidence: 99%

Technical Note: Virtual CT for reducing CT dose in targeted radionuclide therapy dosimetry

Mok

2018

Medical Physics

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“…However, non-rigid registration based on whole body images is relatively computational intensive. Previously, we proposed that organ-based non-rigid registration on sequential quantitative SPECT or CT images can improve the dosimetric estimation (24,25). On the other hand, we also developed a virtual CT (vCT) method to generate CT at different time points when only a single CT is available in the sequential imaging protocol to sustain the dose calculation accuracy (26).…”

Section: Introductionmentioning

confidence: 99%

BIGDOSE: software for 3D personalized targeted radionuclide therapy dosimetry

Li¹,

Zhu

Lü³

et al. 2020

Quant Imaging Med Surg

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Background: Advance 3D quantitative radionuclide imaging techniques boost the accuracy of targeted radionuclide therapy (TRT) dosimetry to voxel level. The goal of this work is to develop a comprehensive 3D dosimetric software, BIGDOSE, with new features of image registration and virtual CT for patientspecific dosimetry.Methods: BIGDOSE includes a portable graphical user interface written in Python, integrating (I) input of sequential ECT/CT images; (II) segmentation; (III) non-rigid image registration; (IV) curve fitting and voxel-based integration; (V) dose conversion and (VI) 3D dose analysis. The accuracy of the software was evaluated using a simulation study with 9 XCAT phantoms. We simulated SPECT/CT acquisitions at 1, 12, 24, 72 and 144-hrs post In-111 Zevalin injection with inter-scans misalignments using an analytical projector for medium energy general purpose (MEGP) collimator, modeling attenuation, scatter and collimatordetector response. The SPECT data were reconstructed using quantitative OS-EM method. A CT organbased registration was performed before the dose calculation. Organ absorbed doses for the corresponding Y-90 therapeutic agent were calculated on target organs and compared with those obtained from OLINDA/ EXM, using dose measured from GATE as the gold standard. One patient with In-111 DTPAOC injection as well as two patients with Y-90 microsphere embolization were used to demonstrate the clinical effectiveness of our software.Results: In the simulation, the organ dose errors of BIGDOSE were −9.59%±9.06%, −8.36±5.82%, −23.41%±6.67%, −6.05%±2.06% for liver, spleen, kidneys and lungs, while they were −25.72%±12.52%, −14.93%±10.91%, −28.63%±12.97% and −45.30%±5.84% for OLINDA/EXM. Cumulative dose volume histograms, dose maps and iso-dose contours provided 3D dose distribution information on the simulated and patient data.Conclusions: BIGDOSE provides a one-stop platform for voxel-based dose estimation with enhanced functions. It is a promising tool to streamline the current clinical TRT dosimetric practice with high accuracy, incorporating 3D personalized imaging information for improved treatment outcome.

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Evaluation of sequential SPECT and CT for targeted radionuclide therapy dosimetry

Abstract: We conclude that if both sequential SPECT/CT scans are available, CT organ-based registration method can more effectively improve the 3D dose estimation. Sequential low-dose CT scans might be considered to be included in the standard TRT protocol.

Cited by 10 publications

References 33 publications

The Effects of Mismatch between SPECT and CT Images on Quantitative Activity Estimation – A Simulation Study

The Effects of Mismatch between SPECT and CT Images on Quantitative Activity Estimation – A Simulation Study

Technical Note: Virtual CT for reducing CT dose in targeted radionuclide therapy dosimetry

BIGDOSE: software for 3D personalized targeted radionuclide therapy dosimetry

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