We report our initial clinical experience for image quality and diagnostic performance of a digital PET prototype scanner with time-of-flight (DigitalTF), compared with an analog PET scanner with time-of-flight (GeminiTF PET/CT). Methods: Twenty-one oncologic patients, mean age 58 y, first underwent clinical 18 F-FDG PET/CT on the GeminiTF. The scanner table was then withdrawn while the patient remained on the table, and the DigitalTF was inserted between the GeminiTF PET and CT scanner. The patients were scanned for a second time using the same PET field of view with CT from the GeminiTF for attenuation correction. Two interpreters reviewed the 2 sets of PET/CT images for overall image quality, lesion conspicuity, and sharpness. They counted the number of suggestive 18 F-FDG-avid lesions and provided the TNM staging for the 5 patients referred for initial staging. Standardized uptake values (SUVs) and SUV gradients as a measure of lesion sharpness were obtained. Results: The DigitalTF showed better image quality than the GeminiTF. In a side-by-side comparison using a 5-point scale, lesion conspicuity (4.3 ± 0.6), lesion sharpness (4.3 ± 0.6), and diagnostic confidence (3.4 ± 0.7) were better with DigitalTF than with GeminiTF (P , 0.01). In 52 representative lesions, the lesion maximum SUV was 36% higher with DigitalTF than with GeminiTF, lesion-toblood-pool SUV ratio was 59% higher, and SUV gradient was 51% higher, with good correlation between the 2 scanners. Lesions less than 1.5 cm showed a greater increase in SUV from GeminiTF to DigitalTF than those lesions 1.5 cm or greater. In 5 of 21 patients, DigitalTF showed an additional 8 suggestive lesions that were not seen using GeminiTF. In the 15 restaging patients, the true-negative rate was 100% and true-positive rate was 78% for both scanners. In the 5 patients for initial staging, DigitalTF led to upstaging in 2 patients and showed the same staging in the other 3 patients, compared with GeminiTF. Conclusion: DigitalTF provides better image quality, diagnostic confidence, and accuracy than GeminiTF. DigitalTF may be the most beneficial in detecting small tumor lesions and disease staging. PETcont inues to play a significant role in molecular imaging.Steady improvements in detector design and architecture as well as the implementation of time-of-flight (TOF) technology have created significant improvements in image quality and greater flexibility in reducing radiotracer dose and scanning time (1-4).The current trend in molecular imaging places emphasis on accurate, quantitative PET imaging for improved lesion characterization and treatment monitoring (5). A new type of scintillation detector, digital photon counters (DPC), was recently developed by Philips Healthcare (6-8). The key innovation of the new digital PET system is the replacement of conventional photomultipliers with high-performance digital detectors and the implementation of singlephoton avalanche photodiodes with low-voltage complementary metal-oxide semiconductor (CMOS) logic on the same silico...

This study evaluated the positron emission tomography (PET) imaging performance of the Ingenuity TF 128 PET/computed tomography (CT) scanner which has a PET component that was designed to support a wider radioactivity range than is possible with those of Gemini TF PET/CT and Ingenuity TF PET/MR. Spatial resolution, sensitivity, count rate characteristics and image quality were evaluated according to the NEMA NU 2–2007 standard and ACR phantom accreditation procedures; these were supplemented by additional measurements intended to characterize the system under conditions that would be encountered during quantitative cardiac imaging with 82Rb. Image quality was evaluated using a hot spheres phantom, and various contrast recovery and noise measurements were made from replicated images. Timing and energy resolution, dead time, and the linearity of the image activity concentration, were all measured over a wide range of count rates. Spatial resolution (4.8– 5.1 mm FWHM), sensitivity (7.3 cps kBq−1), peak noise-equivalent count rate (124 kcps), and peak trues rate (365 kcps)were similar to those of the Gemini TF PET/CT. Contrast recovery was higher with a 2 mm, body-detail reconstruction than with a 4 mm, body reconstruction, although the precision was reduced. The noise equivalent count rate peak was broad (within 10% of peak from 241–609 MBq). The activity measured in phantom images was within 10% of the true activity for count rates up to those observed in 82Rb cardiac PET studies.

Purpose: MR-based pseudo-CT has an important role in MR-based radiation therapy planning and PET attenuation correction. The purpose of this study is to establish a clinically feasible approach, including image acquisition, correction, and CT formation, for pseudo-CT generation of the brain using a single-acquisition, undersampled ultrashort echo time (UTE)-mDixon pulse sequence. Methods: Nine patients were recruited for this study. For each patient, a 190-s, undersampled, single acquisition UTE-mDixon sequence of the brain was acquired (TE = 0.1, 1.5, and 2.8 ms). A novel method of retrospective trajectory correction of the free induction decay (FID) signal was performed based on point-spread functions of three external MR markers. Two-point Dixon images were reconstructed using the first and second echo data (TE = 1.5 and 2.8 ms). R2 * images (1/T2 * ) were then estimated and were used to provide bone information. Three image features, i.e., Dixon-fat, Dixon-water, and R2 * , were used for unsupervised clustering. Five tissue clusters, i.e., air, brain, fat, fluid, and bone, were estimated using the fuzzy c-means (FCM) algorithm. A two-step, automatic tissue-assignment approach was proposed and designed according to the prior information of the given feature space. Pseudo-CTs were generated by a voxelwise linear combination of the membership functions of the FCM. A low-dose CT was acquired for each patient and was used as the gold standard for comparison. Results: The contrast and sharpness of the FID images were improved after trajectory correction was applied. The mean of the estimated trajectory delay was 0.774 µs (max: 1.350 µs; min: 0.180 µs). The FCM-estimated centroids of different tissue types showed a distinguishable pattern for different tissues, and significant differences were found between the centroid locations of different tissue types. Pseudo-CT can provide additional skull detail and has low bias and absolute error of estimated CT numbers of voxels (−22 ± 29 HU and 130 ± 16 HU) when compared to low-dose CT. Conclusions: The MR features generated by the proposed acquisition, correction, and processing methods may provide representative clustering information and could thus be used for clinical pseudo-CT generation. C 2015 American Association of Physicists in Medicine.

VMIs improve assessment of arterially hyper-enhancing liver lesions since they increase lesion contrast while maintaining low image noise throughout the entire keV spectrum. These data suggest that to consider VMI screening after arterially hyper-enhancing liver lesions.

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Derived from 2 yr of deliberations and community engagement, Medical Physics 3.0 (MP3.0) is an effort commissioned by the American Association of Physicists in Medicine (AAPM) to devise a framework of strategies by which medical physicists can maintain and improve their integral roles in, and contributions to, health care and its innovation under conditions of rapid change and uncertainty. Toward that goal, MP3.0 advocates a broadened and refreshed model of sustainable excellence by which medical physicists can and should contribute to health care. The overarching conviction of MP3.0 is that every healthcare facility can benefit from medical physics and every patient's care can be improved by a medical physicist. This large and expansive challenge necessitates a range of strategies specific to each area of medical physics: clinical practice, research, product development, and education. The present paper offers a summary of the Phase 1 deliberations of the MP3.0 initiative pertaining to strategic directions of the discipline primarily but not exclusively oriented toward the clinical practice of medical physics in the United States.

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The investigated O-MAR algorithm reduces artifacts from DBS electrodes and should be used in the assessment of postoperative patients; however, combination with VMI does not provide an additional benefit.