Ra-223 SPECT for semi-quantitative analysis in comparison with Tc-99m HMDP SPECT: phantom study and initial clinical experience

Owaki, Yoshiki; Nakahara, Tsutomu; Kosaka, Takeo; Fukada, Junichi; Kumabe, Atsuhiro; Ichimura, Atsuhiko; Mikoto, Murakami; Nakajima, Koji; Fukushi, Masahiro; Inoue, Kazuaki; Oya, Mototsugu; Jinzaki, Masahiro

doi:10.1186/s13550-017-0330-z

Cited by 21 publications

(27 citation statements)

References 15 publications

(22 reference statements)

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“…crystal and a medium-energy general-purpose (MEGP) collimator, was used. Note that Owaki et al [24] proved in a clinical study that a high-energy general-purpose (HEGP) collimator gives a higher image contrast than a MEGP collimator, yet an HEGP collimator was not available in our study. The energy window setting was chosen based on the maximum intensities of photons emitted by 223 Ra.…”

Section: Methodsmentioning

confidence: 90%

“…Three energy emission windows (85.0 keV ± 20%, 154.0 keV ± 10%, and 270.0 keV ± 10%) and three scatter windows (47.0 keV to 67.0 keV, 103.0 keV to 123.0 keV, and 210.2 keV to 242.8 keV) are recommended. Although Owaki et al [24] used a single energy window at 84 keV ± 20%, we precise that the gamma camera used in our study is equipped with a 5/8-in. crystal.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, lesions are sometimes visible only in the anterior or posterior view, which limits the quantification of 223 Ra activity [14]. Further, the improved quantitative accuracy of 3D tomographic imaging modalities over 2D planar imaging is well established [21–23]; yet only one study so far investigated the feasibility and usefulness of single-photon emission computed tomography (SPECT) semi-quantitative imaging for 223 Ra [24]. In [24], Owaki et al demonstrated the advantage of SPECT imaging on separating pathological bone uptakes from bowel uptakes.…”

Section: Introductionmentioning

confidence: 99%

“…Further, the improved quantitative accuracy of 3D tomographic imaging modalities over 2D planar imaging is well established [21–23]; yet only one study so far investigated the feasibility and usefulness of single-photon emission computed tomography (SPECT) semi-quantitative imaging for 223 Ra [24]. In [24], Owaki et al demonstrated the advantage of SPECT imaging on separating pathological bone uptakes from bowel uptakes. This result suggests that quantitative SPECT/CT 223 Ra imaging is a promising method able to overcome the limitations of planar imaging and to better assess individual lesions.…”

Section: Introductionmentioning

confidence: 99%

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223Ra-dichloride therapy of bone metastasis: optimization of SPECT images for quantification

et al. 2019

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Background 223 Ra imaging is crucial to evaluate the successfulness of the therapy of bone metastasis of castration-resistant prostate cancer (CRPC). The goals of this study were to establish a quantitative tomographic 223 Ra imaging protocol with clinically achievable conditions, as well as to investigate its usefulness and limitations. We performed several experiments using the Infinia Hawkeye 4 gamma camera (GE) and physical phantoms in order to assess the optimal image acquisition and reconstruction parameters, such as the windows setting, as well as the iteration number and filter of the reconstruction algorithm. Then, based on the MIRD pamphlet 23, we used a NEMA phantom and an anthropomorphic TORSO® phantom to calibrate the gamma camera and investigate the accuracy of quantification. Results Experiences showed that the 85 keV ± 20%, 154 keV ± 10%, and 270 keV ± 10% energy windows are the most suitable for 223 Ra imaging. The study with the NEMA phantom showed that the OSEM algorithm with 2 iterations, 10 subsets, and the Butterworth filter offered the best compromise between contrast and noise. Moreover, the calibration factors for different sphere sizes (26.5 ml, 11.5 ml, and 5.6 ml) were constant for 223 Ra concentrations ranging between 6.5 and 22.8 kBq/ml. The values found are 73.7 cts/s/MBq, 43.8 cts/s/MBq, and 43.4 cts/s/MBq for 26.5 ml, 11.5 ml, and 5.6 ml sphere, respectively. For concentration lower than 6.5 kBq/ml, the calibration factors exhibited greater variability pointing out the limitations of SPECT/CT imaging for quantification. By the use of a TORSO® phantom, we simulated several tumors to normal tissue ratios as close as possible to clinical conditions. Using the calibration factors obtained with the NEMA phantom, for 223 Ra concentrations higher than 8 kBq/ml, we were able to quantify the activity with an error inferior to 18.8% in a 5.6 ml lesion. Conclusions Absolute quantitative 223 Ra SPECT imaging appears feasible once the dimension of the target is determined. Further evaluation should be needed to apply the calibration factor-based quantitation to clinical 223 Ra SPECT/CT imaging. This will open the possibility for patient-specific 223 Ra treatment planning and therapeutic outcome prediction in patients.

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Section: Methodsmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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223Ra-dichloride therapy of bone metastasis: optimization of SPECT images for quantification

et al. 2019

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“…21,22 Recently, studies have also been conducted to explore the usefulness of SPECT/CT 223 Ra. 23,24 With regard to dosimetry, most conventional approaches are limited to average parameters such as absorbed dose to a macroscopic volume. Current dosimetry calculations predict a much higher level of hematotoxicity than experienced clinically.…”

Section: Radiobiological Properties and Dosimetry Of A-therapymentioning

confidence: 99%

Targeted Alpha Therapy: Current Clinical Applications

Liberal

O’Sullivan

McMahon

et al. 2020

Cancer Biotherapy and Radiopharmaceuticals

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a-Emitting radionuclides have been approved for cancer treatment since 2013, with increasing degrees of success. Despite this clinical utility, little is known regarding the mechanisms of action of a particles in this setting, and accurate assessments of the dosimetry underpinning their effectiveness are lacking. However, targeted alpha therapy (TAT) is gaining more attention as new targets, synthetic chemistry approaches, and a particle emitters are identified, constructed, developed, and realized. From a radiobiological perspective, a particles are more effective at killing cells compared to low linear energy transfer radiation. Also, from these direct effects, it is now evident from preclinical and clinical data that a emitters are capable of both producing effects in nonirradiated bystander cells and stimulating the immune system, extending the biological effects of TAT beyond the range of a particles. The short range of a particles makes them a potent tool to irradiate singlecell lesions or treat solid tumors by minimizing unwanted irradiation of normal tissue surrounding the cancer cells, assuming a high specificity of the radiopharmaceutical and good stability of its chemical bonds. Clinical approval of 223 RaCl 2 in 2013 was a major milestone in the widespread application of TAT as a safe and effective strategy for cancer treatment. In addition, 225 Ac-prostate specific membrane antigen treatment benefit in metastatic castrate-resistant prostate cancer patients, refractory to standard therapies, is another gamechanging piece in the short history of TAT clinical application. Clinical applications of TAT are growing with different radionuclides and combination therapies, and in different clinical settings. Despite the remarkable advances in TAT dosimetry and imaging, it has not yet been used to its full potential. Labeled 227 Th and 225 Ac appear to be promising candidates and could represent the next generation of agents able to extend patient survival in several clinical scenarios.

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Assessment of collimators in radium-223 imaging with channelized Hotelling observer: a simulation study

2018

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Ra-223 SPECT for semi-quantitative analysis in comparison with Tc-99m HMDP SPECT: phantom study and initial clinical experience

Cited by 21 publications

References 15 publications

223Ra-dichloride therapy of bone metastasis: optimization of SPECT images for quantification

223Ra-dichloride therapy of bone metastasis: optimization of SPECT images for quantification

Targeted Alpha Therapy: Current Clinical Applications

Assessment of collimators in radium-223 imaging with channelized Hotelling observer: a simulation study

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