Effect of diagnostic cone-beam computed tomography protocols on image quality,patient dose,and lesion detection

ObjectiveTo evaluate the effect of cone-beam computed tomography (CBCT) image acquisition protocols on image quality, lesion detection, delineation, and patient dose.Methods100-patients and a CTDI phantom combined with an electron density phantom were examined using four different CBCT-image acquisition protocols during image-guided transarterial chemoembolization (TACE). Protocol-1 (time: 6 s, tube rotation: 360°), protocol-2 (5 s, 300°), protocol-3 (4 s, 240°) and protocol-4 (3 s, 180°) were used. The protocols were first investigated using a phantom. The protocols that were found to be clinically appropriate in terms of image quality and radiation dose were then assessed on patients. A higher radiation dose and/or a poor image quality were inappropriate for the patient imaging. Patient dose (patient-entrance dose and dose-area product), image quality (Hounsfield Unit, noise, signal-to-noise ratio and contrast-to-noise ratio), and lesion delineation (tumor-liver contrast) were assessed and compared using appropriate statistical tests. Lesion detectability, sensitivity, and predictive values were estimated for CBCT-image data using pre-treatment patient magnetic resonance imaging.ResultsThe estimated patient dose showed no statistical significance (p > 0.05) between protocols-2 and -3; the assessed image quality between these protocols manifested insignificant difference (p > 0.05). Two other phantom protocols were not considered for patient imaging due to significantly higher dose (protocols-1) and poor image quality (protocol-4). Lesion delineation and detection were insignificant (p > 0.05) between protocols-2 and -3. Lesion sensitivities generated were 81–89% (protocol-2) and 81–85% (protocol-3) for different lesion types.ConclusionData acquisition using protocols-2 and -3 provided good image quality, lesion detection and delineation with acceptable patient dose during CBCT-imaging mainly due to similar frame numbers acquired.     

An empirical artifact correction for proton computed tomography

Purpose: To reduce image artifacts of proton computed tomography (pCT) from a preclinical scanner, for imaging of the relative stopping power (RSP) needed for particle therapy treatment planning using a simple empirical artifact correction method.Methods: We adapted and employed a correction method previously used for beam-hardening correction in x-ray CT which makes use of a single scan of a custom-built homogeneous phantom with known RSP. Exploiting the linearity of the filtered backprojection operation, a function was found which corrects water-equivalent path lengths (RSP line integrals) in experimental scans using a prototype pCT scanner. The correction function was applied to projection values of subsequent scans of a homogeneous water phantom, a sensitometric phantom with various inserts and an anthropomorphic head phantom. Data were acquired at two different incident proton energies to test the robustness of the method.Results: Inaccuracies in the detection process caused an offset and known ring artifacts in the water phantom which were considerably reduced using the proposed method. The mean absolute percentage error (MAPE) of mean RSP values of all inserts of the sensitometric phantom and the water phantom was reduced from 0.87% to 0.44% and from 0.86% to 0.48% for the two incident energies respectively. In the head phantom a clear reduction of artifacts was observed.Conclusions: Image artifacts of experimental pCT scans with a prototype scanner could substantially be reduced both in homogeneous, heterogeneous and anthropomorphic phantoms. RSP accuracy was also improved.     

Feasibility and safety of definite volumetric modulated arc therapy with simultaneous integrated boost to the dominant intraprostatic lesion in patients with unfavorable intermediate to high-risk prostate cancer

BackgroundThe most common site of recurrence of prostate cancer after definite radiation therapy is the dominant intraprostatic lesion (DIL). This study aimed to investigate the feasibility and safety of definite volumetric modulated arc therapy (VMAT) with simultaneous integrated boost (SIB) to the DIL in patients with unfavorable intermediate to high-risk prostate cancer.Materials and methodsIn this prospective uncontrolled clinical trial, patients were delivered VMAT at a dose of 87.75 Gy in 39 fractions or 70 Gy in 20 fractions to the DIL in combination with androgen deprivation therapy. Genitourinary (GU) and rectal toxicity, International Prostate Symptom Score (IPSS) and IPSS quality of life (IPSS-QOL) score were collected.ResultsForty-five patients with a median follow-up of 20 months were analyzed. The cumulative incidence of acute grade ≥ 2 GU and rectal toxicity was 33.1% and 9.5%, respectively. Regarding late toxicity, the cumulative incidence of grade ≥ 2 GU and rectal toxicity was 12.6% and 2.8%, respectively. During treatment, the mean increase of IPSS was +7.4 ± 4.2 and the mean increase of IPSS-QOL was +1.7 ± 1.3. However, both IPSS and IPSS-QOL scores returned to their baseline levels by 3-months post-treatment. No significant correlation between baseline characteristics and grade ≥ 2 GU or rectal toxicity was found.ConclusionFocal SIB to the DIL of ≥ 90 Gy EQD2 in unfavorable intermediate to high-risk prostate cancer patients resulted in tolerable toxicity profiles. The mean IPSS and IPSS-QOL scores both worsened during treatment; however, both scores returned to baseline level by 3 months after treatment.     

Analysis of the planned,delivered dose distributions and quality assurance for helical tomotherapy and volumetric modulated arc therapy in locally advanced non-small cell lung cancer

BackgroundWith full access to both helical tomotherapy (HT) and volumetric modulated arc therapy (VMAT), we compared locally advanced non-small cell lung cancer (LA-NSCLC) treatment plans and verified the plans using patient-specific pretreatment quality assurance (PSQA).Materials and methodsFor each of the seventeen patients included in the study, two treatment plans (i.e. HT and VMAT) were created. Optimized plans were evaluated following the ICRU 83 criteria. Planned quality indexes and dosimetric parameters were compared. Lastly, all plans were subjected to PSQA assessment by determining the gamma passing rate (GPR).ResultsAll dosimetry results obtained from the planning target volume passed the ICRU 83 criteria. With regard to similar homogeneity indices, VMAT produced better conformity number values than HT (0.78 vs. 0.64), but differences in the values were insignificant. Furthermore, VMAT was associated with a significantly shorter mean treatment time (1.91 minutes vs. 6.66 minutes). For PSQA assessment, both techniques resulted in adequate GPR values (> 90% at the 3%/3 mm criteria).ConclusionBoth HT and VMAT techniques led to the generation of clinically satisfactory and reliable radiotherapy plans. However, the VMAT plan was associated with a non-significantly better degree of conformity and a significantly shorter treatment time. Thus, VMAT was determined to be a better choice for LA-NSCLC.     

A comparative analysis of Acuros XB and the analytical anisotropic algorithm for volumetric modulation arc therapy

BackgroundThis study aimed to verify the dosimetric impact of Acuros XB (AXB) (AXB, Varian Medical Systems Palo Alto CA, USA), a two model-based algorithm, in comparison with Anisotropic Analytical Algorithm (AAA ) calculations for prostate, head and neck and lung cancer treatment by volumetric modulated arc therapy (VMAT ), without primary modification to AA. At present, the well-known and validated AA algorithm is clinically used in our department for VMAT treatments of different pathologies. AXB could replace it without extra measurements. The treatment result and accuracy of the dose delivered depend on the dose calculation algorithm.Materials and methodNinety-five complex VMAT plans for different pathologies were generated using the Eclipse version 15.0.4 treatment planning system (TPS). The dose distributions were calculated using AA and AXB (dose-to-water, AXB_w and dose-to-medium, AXB_m), with the same plan parameters for all VMAT plans. The dosimetric parameters were calculated for each planning target volume (PTV) and involved organs at risk (OA R). The patient specific quality assurance of all VMAT plans has been verified by Octavius^®-4D phantom for different algorithms.ResultsThe relative differences among AA, AXB_w and AXB_m, with respect to prostate, head and neck were less than 1% for PTV D_95%. However, PTV D_95% calculated by AA tended to be overestimated, with a relative dose difference of 3.23% in the case of lung treatment. The absolute mean values of the relative differences were 1.1 ± 1.2% and 2.0 ± 1.2%, when comparing between AXB_w and AA, AXB_m and AA, respectively. The gamma pass rate was observed to exceed 97.4% and 99.4% for the measured and calculated doses in most cases of the volumetric 3D analysis for AA and AXB_m, respectively.ConclusionThis study suggests that the dose calculated to medium using AXB_m algorithm is better than AAA and it could be used clinically. Switching the dose calculation algorithm from AA to AXB does not require extra measurements.     

Clinical impact of dosimetric changes for volumetric modulated arc therapy in log file-based patient dose calculations

PurposeA log file-based method cannot detect dosimetric changes due to linac component miscalibration because log files are insensitive to miscalibration. Herein, clinical impacts of dosimetric changes on a log file-based method were determined.Methods and materialsFive head-and-neck and five prostate plans were applied. Miscalibration-simulated log files were generated by inducing a linac component miscalibration into the log file. Miscalibration magnitudes for leaf, gantry, and collimator at the general tolerance level were ±0.5 mm, ±1°, and ±1°, respectively, and at a tighter tolerance level achievable on current linac were ±0.3 mm, ±0.5°, and ±0.5°, respectively. Re-calculations were performed on patient anatomy using log file data.ResultsChanges in tumor control probability/normal tissue complication probability from treatment planning system dose to re-calculated dose at the general tolerance level was 1.8% on planning target volume (PTV) and 2.4% on organs at risk (OARs) in both plans. These changes at the tighter tolerance level were improved to 1.0% on PTV and to 1.5% on OARs, with a statistically significant difference.ConclusionsWe determined the clinical impacts of dosimetric changes on a log file-based method using a general tolerance level and a tighter tolerance level for linac miscalibration and found that a tighter tolerance level significantly improved the accuracy of the log file-based method.     

Examination of the dose distribution of volumetric modulated arc radiotherapy using a high-definition multi-leaf collimator for breast cancer patients with irradiated regional lymph nodes

BackgroundA high-definition multi-leaf collimator (HD-MLC) with 5- and 10-mm fine MLCs is useful for radiotherapy. However, it is difficult to irradiate the mammary gland and supraclavicular region using a HD-MLC because of the narrow field of volumetric modulated arc radiotherapy (VMAT). Therefore, we aimed to evaluate the dose distribution of the VMAT dose using a HD-MLC in 15 patients with left breast cancer undergoing postoperative irradiation of breast and regional lymph nodes, including the internal mammary node.Materials and methodsThe following four plans were generated: three-arc VMAT using HD-MLC (HD-VMAT), two tangential arcs and one-arc VMAT using HD-MLC (tHD-VMAT), three-dimensional conformal radiotherapy (3DCRT) using HD-MLC, and two-arc VMAT using the Millennium 120-leaf MLC (M-VMAT). We assessed the doses to the target volume and organs at risk.ResultsThe target dose distributions were higher for HD-VMAT than 3DCRT. There were no significant differences in the heart mean dose (D_mean) or lung volume receiving 20 Gy (V20 Gy) between HD-VMAT and 3DCRT. The heart D_mean and lung V20 Gy of tHD-VMAT were higher than those of HD-VMAT, and the heart D_mean of M-VMAT was higher than that of HD-VMAT. However, the target doses of tHD-VMAT, M-VMAT, and HD-VMAT were equivalent.ConclusionsIn cases of the mammary gland and regional lymph node irradiation, including the internal mammary node in patients with left breast cancer, HD-VMAT was not inferior to M-VMAT and provided a better dose distribution to the target volume and organs at risk compared with 3DCRT and tHD-VMAT.     

Development of 99mTc-labeled asymmetric urea derivatives that target prostate-specific membrane antigen for single-photon emission computed tomography imaging

Prostate-specific membrane antigen (PSMA) is expressed strongly in prostate cancers and is, therefore, an attractive diagnostic and radioimmunotherapeutic target. In contrast to previous reports of PMSA-targeting ^99mTc-tricarbonyl complexes that are cationic or lack a charge, no anionic ^99mTc-tricarbonyl complexes have been reported. Notably, the hydrophilicity conferred by both cationic and anionic charges leads to rapid hepatobiliary clearance, whereas an anionic charge might better enhance renal clearance relative to a cationic charge. Therefore, an improvement in rapid clearance would be expected with either cationic or anionic charges, particularly anionic charges. In this study, we designed and synthesized a novel anionic ^99mTc-tricarbonyl complex ([^99mTc]TMCE) and evaluated its use as a single-photon emission computed tomography (SPECT) imaging probe for PSMA detection. Direct synthesis of [^99mTc]TMCE from dimethyl iminodiacetate, which contains both the asymmetric urea and succinimidyl moiety important for PSMA binding, was performed using our microwave-assisted one-pot procedure. The chelate formation was successfully achieved even though the precursor included a complicated bioactive moiety. The radiochemical yield of [^99mTc]TMCE was 12–17%, with a radiochemical purity greater than 98% after HPLC purification. [^99mTc]TMCE showed high affinity in vitro, with high accumulation in LNCaP tumors and low hepatic retention in biodistribution and SPECT/CT studies. These findings warrant further evaluation of [^99mTc]TMCE as an imaging agent and support the benefit of this strategy for the design of other PSMA imaging probes.     

Absorbed dose and image quality of Varian TrueBeam CBCT compared with OBI CBCT

Purpose: Nowadays, patient positioning and target localization can be verified by using kilovolt cone beam computed tomography (kV-CBCT). There have been various studies on the absorbed doses and image qualities of different kV-CBCT systems. However, the Varian TrueBeam CBCT (TB CBCT) system has not been investigated so far. We assess the image quality and absorbed dose of TB CBCT through comparison with those of on-board imager (OBI) CBCT.Methods: The image quality was evaluated using two phantoms. A CATPHAN phantom measured the image quality parameters of the American Association of Physicists in Medicine Task Group 142 (AAPM TG-142) report. These factors are the pixel value stability and accuracy, noise, high-contrast resolution, low-contrast resolution, and image uniformity. A H₂SO₄ phantom was used to evaluate the image uniformity over a larger region than the CATPHAN phantom. In evaluating the absorbed dose, the radial dose profile and the patient organ doses at the prostate and rectum levels were evaluated.Results: The image quality parameters of AAPM TG-142 using TB CBCT are equal to or greater than those of OBI CBCT. In particular, the contrast-to-noise ratio with TB CBCT is 2.5 times higher than that with OBI CBCT. For the test of a large field uniformity, the maximum difference in the Hounsfield unit (HU) values between the centre and peripheral regions is within 30 HU with TB CBCT and 283 HU with OBI CBCT. The maximum absorbed dose with TB CBCT is decreased by 60%.Conclusions: We find that the image quality improved and the absorbed dose decreased with TB CBCT in comparison to those with OBI CBCT. Its image uniformity is also superior over a larger scanning range.     

Dosimetric comparison of conformal technique (3D) with volumetric modulated arc therapy with respect to doses obtained in the temporal lobe area in patients irradiated for brain meningioma

AimThe aim of the analysis was to compare doses obtained for temporal lobes in patients being irradiated for meningiomas of the brain using the conformal technique and volumetric modulated arc therapy (VMAT). We try to answer the question whether the application of VMAT would lead to higher doses within temporal lobes.BackgroundIn recent years a significant increase in the detection of meningiomas and effectiveness of treatment has been observed. Hence quality of life should be considered as an important aspect after a treatment course.Materials and methodsTreatment plans of 27 patients were evaluated retrospectively. Radiotherapy procedures were carried out from 2007 until 2016 at the Department of Radiation Oncology in Wroclaw, Poland. For individual patients, alternative treatment plans were generated in relation to the ones originally used, wherein from dynamic techniques, volumetric modulated arc therapy was selected for analysis. Evaluated dosimetric parameters for temporal lobes were: mean dose, V10 Gy, V20 Gy, V45 Gy.ResultsStatistically significant differences were observed for V45 Gy for both temporal lobes (p = 0.023) and for V45 Gy for the right (p = 0.001) and the left temporal lobe (p = 0.016) considered for VMAT. The mean values of the V45 Gy for both temporal lobes, for the right temporal lobe and for the left temporal lobe were lower for VMAT than for 3D, respectively: 7.54% and 7.90%, 6.82% and 9.47%, 5.67% and 7.14%.Analysis of the remaining results found no statistical differences.ConclusionApplication of VMAT in patients treated for meningioma of the brain is not related to higher doses of radiation in the temporal lobe area, compared with the conformal technique.     

Dosimetric comparison of left-sided whole-breast irradiation with 3DCRT,forward-planned IMRT,inverse-planned IMRT,helical tomotherapy,and volumetric arc therapy

PurposeThis study evaluated the dose distribution and homogeneity of four different types of intensity-modulated radiotherapy (IMRT) in comparison with standard wedged tangential-beam three-dimensional conformal radiotherapy (3DCRT) of the left breast in patients who had undergone lumpectomy.Materials and methodsFive radiotherapy treatment plans, including 3DCRT, forward-planned IMRT (for-IMRT), inverse IMRT (inv-IMRT), helical tomotherapy (HT) and volumetric-modulated arc therapy (VMAT), were created for 15 consecutive patients.ResultsAll modalities presented similar target coverage. Target max doses were reduced with for-IMRT compared to 3DCRT, and these doses were further reduced with inv-IMRT and HT. HT resulted in the lowest max doses delivered to the heart, left anterior descending artery (LAD), and ipsilateral lung, but had higher mean, max, and low doses delivered to contralateral breast. HT resulted in increased low doses to a large volume of healthy tissue. Compared to other techniques, all inverse-planned modalities significantly improved conformity number; however, VMAT had worse homogeneity. The for-IMRT plan significantly lowered monitor unit (MU) compared to the inverse-planned techniques.ConclusionAll modalities evaluated provide adequate coverage of the whole breast. For-IMRT improves target homogeneity compared with 3DCRT, but to a lesser degree than the inverse-planned inv-IMRT and HT. HT decreases the ipsilateral OAR volumes receiving higher and mean doses with an increase in the volumes receiving low doses, which is known to lead to an increased rate of radiation-induced secondary malignancies.     

Normoxic polymer gel dosimetry using less toxic monomer of N-isopropyl acrylamide and X-ray computed tomography for radiation therapy applications

Background

Polymer gel dosimetry has been used extensively in radiation therapy for its capability in depicting a three dimensional view of absorbed dose distribution. However, more studies are required to find less toxic and more efficient polymers for application in radiotherapy dosimetry.

Aim

The purpose of this work was to evaluate the N-isopropyl acrylamide (NIPAM) gel dosimetric characteristics and optimize the protocol for X-ray computed tomography (CT) imaging of gel dosimeters for radiation therapy application.

Material and methods

A polymer gel dosimeter based on NIPAM monomer was prepared and irradiated with ⁶⁰Co photons. The CT number changes following irradiation were extracted from CT images obtained with different sets of imaging parameters.

Results

The results showed the dose sensitivity of ΔN_CT (H) = 0.282 ± 0.018 (H Gy⁻¹) for NIPAM gel dosimeter. The optimized set of imaging exposure parameters was 120 kV_p and 200 mA with the 10 mm slice thickness. Results of the depth dose measurement with gel dosimeter showed a great discrepancy with the actual depth dose data.

Conclusion

According to the current study, NIPAM-based gel dosimetry with X-ray CT imaging needs more technical development and formulation refinement to be used for radiation therapy application.     

Cone-beam breast computed tomography using ultra-fast image reconstruction with constrained,total-variation minimization for suppression of artifacts

Compressed sensing based iterative reconstruction algorithms for computed tomography such as adaptive steepest descent-projection on convex sets (ASD-POCS) are attractive due to their applicability in incomplete datasets such as sparse-view data and can reduce radiation dose to the patients while preserving image quality. Although IR algorithms reduce image noise compared to analytical Feldkamp-Davis-Kress (FDK) algorithm, they may generate artifacts, particularly along the periphery of the object. One popular solution is to use finer image-grid followed by down-sampling. This approach is computationally intensive but may be compensated by reducing the field of view. Our proposed solution is to replace the algebraic reconstruction technique within the original ASD-POCS by ordered subsets-simultaneous algebraic reconstruction technique (OS-SART) and with initialization using FDK image. We refer to this method as Fast, Iterative, TV-Regularized, Statistical reconstruction Technique (FIRST). In this study, we investigate FIRST for cone-beam dedicated breast CT with large image matrix. The signal-difference to noise ratio (SDNR), the difference of the mean value and the variance of adipose and fibroglandular tissues for both FDK and FIRST reconstructions were determined. With FDK serving as the reference, the root-mean-square error (RMSE), bias, and the full-width at half-maximum (FWHM) of microcalcifications in two orthogonal directions were also computed. Our results suggest that FIRST is competitive to the finer image-grid method with shorter reconstruction time. Images reconstructed using the FIRST do not exhibit artifacts and outperformed FDK in terms of image noise. This suggests the potential of this approach for radiation dose reduction in cone-beam breast CT.     

Enriched Au nanoclusters with mesoporous silica nanoparticles for improved fluorescence/computed tomography dual‐modal imaging

ObjectivesAu nanoclusters (AuNCs) have been used widely in fluorescence bio‐imaging because of their good fluorescence, small particle size and non‐cytotoxicity. AuNCs are also efficient in computed tomography (CT) imaging. Hence, a dual‐modal imaging probe can be constructed without any complicated modification processes by exploiting the excellent performance of AuNCs. In the present study, AuNCs were enriched with mesoporous silica nanoparticles (MSNs) to obtain enhanced fluorescence/CT dual‐modal imaging, which was capable of acquiring more imaging information for diseases compared with single‐mode imaging.Materials and methodsBiocompatible bovine serum albumin (BSA)‐capped AuNCs were prepared and loaded into amine‐functionalized MSNs to form MSN@AuNCs. BSA‐AuNCs, MSNs, and MSN@AuNCs were characterized by ultraviolet‐visible (UV‐vis) spectra, transmission electron microscopy (TEM), fluorescence spectra, and zeta potential. CT imaging was recorded using micro‐CT scanning. Fluorescence imaging was measured using confocal laser scanning microscopy and flow cytometry.ResultsThe prepared AuNCs and MSNs possessed good properties as previously reported. The fluorescence intensity and CT value of the AuNCs were enhanced after being enriched with MSNs. The nanoparticles were both non‐cytotoxic. Confocal laser scanning microscopy and flow cytometry indicated that MSN@AuNCs in CAL‐27 cells showed improved fluorescence imaging compared with simple AuNCs at the same concentration.ConclusionsThe results revealed that the strategy of enriching AuNCs with MSNs can obtain highly sensitive fluorescence/CT dual‐modal imaging, which indicated the potential of this nanoparticle in the diagnosis and treatment of disease.     

Improvement of image quality for pancreatic cancer using deep learning-generated virtual monochromatic images: Comparison with single-energy computed tomography

PurposeTo construct a deep convolutional neural network that generates virtual monochromatic images (VMIs) from single-energy computed tomography (SECT) images for improved pancreatic cancer imaging quality.Materials and methodsFifty patients with pancreatic cancer underwent a dual-energy CT simulation and VMIs at 77 and 60 keV were reconstructed. A 2D deep densely connected convolutional neural network was modeled to learn the relationship between the VMIs at 77 (input) and 60 keV (ground-truth). Subsequently, VMIs were generated for 20 patients from SECT images using the trained deep learning model.ResultsThe contrast-to-noise ratio was significantly improved (p < 0.001) in the generated VMIs (4.1 ± 1.8) compared to the SECT images (2.8 ± 1.1). The mean overall image quality (4.1 ± 0.6) and tumor enhancement (3.6 ± 0.6) in the generated VMIs assessed on a five-point scale were significantly higher (p < 0.001) than that in the SECT images (3.2 ± 0.4 and 2.8 ± 0.4 for overall image quality and tumor enhancement, respectively).ConclusionsThe quality of the SECT image was significantly improved both objectively and subjectively using the proposed deep learning model for pancreatic tumors in radiotherapy.     

Image quality comparison of a nonlinear image-based noise reduction technique with a hybrid-type iterative reconstruction for pediatric computed tomography

PurposeTo compare computed tomography (CT) image properties between a vendor-independent image-based noise reduction technique, Image-space Noise Reduction (iNoir) and a hybrid-type iterative reconstruction technique, Adaptive Statistical Iterative Reconstruction (ASIR).MethodsA cylindrical water phantom, corresponding to pediatric body size, containing soft-tissue-equivalent rod and 12-mg iodine/ml rod was scanned at size-specific dose estimates of 8.4 and 16.7 mGy. For assessments of image quality and noise texture change, task-based system performance function (SPF) and peak frequency difference (PFD) were compared, respectively, among filtered back projection (FBP), IR image with 50%-blending rate (50%ASIR), 100%ASIR, 50%iNoir, and 100%iNoir. Human observer test for pediatric CT images was performed by radiologists.ResultsFor the soft-tissue contrast, SPF² of 100%iNoir was the highest. The average SPF² between 0.1 and 0.5 cycles/mm for 100%iNoir increased by approximately 70% compared with FBP, while ASIR indicted slight increases in the frequency region of >0.2 cycles/mm. For the iodine contrast, 100%iNoir indicated highest values at the spatial frequencies corresponding pediatric artery diameters. The PFDs of iNoir were negligible and lower than that of ASIR. The results of human observer test supported results of SPF² and PFD.ConclusionsCompared with ASIR, iNoir provided better image quality for pediatric abdominal CT without compromising noise texture change.     

Synthesis and radiolabeling of 111In-core-cross linked polymeric micelle-octreotide for near-infrared fluoroscopy and single photon emission computed tomography imaging

The objective of this study was the development of a dual-modality imaging device, namely ¹¹¹In-core-cross-linked polymeric micelle (CCPM)-octreotide, for neuroendocrine tumor detection, using near-infrared fluoroscopy (NIRF) and single photon emission computed tomography (SPECT). The tumor targeting ability of the ¹¹¹In-labeled CCPM-octreotide was evaluated in a tumor mouse model. SPECT/CT, NIRF and gamma imaging results showed high tumor uptake of ¹¹¹In-labeled CCPM-octreotide. In contrast, there was a much lower signal in the same mouse model injected with ¹¹¹In-labeled CCPM. The high accumulation of ¹¹¹In-labeled CCPM-octreotide in U87 tumor was reduced after co-injection with an excess amount of CCPM-octreotide. These results suggested CCPM-octreotide’s potential applications in tumor diagnosis, drug delivery and molecular imaging.