EJNMMI Physics最新文献

{"title":"Estimation of the effective dose in torso ¹⁸F-fluorodeoxyglucose PET/CT: an analysis of real-world clinical data from 51,784 patient scans.","authors":"Jeongryul Ryu, Jungsu S Oh, Yong-Il Kim, Sangwon Han, Jae Seung Kim, Kyung-Hyun Do, Jin-Sook Ryu","doi":"10.1186/s40658-026-00857-5","DOIUrl":"10.1186/s40658-026-00857-5","url":null,"abstract":"<p><p>BACKGROUND: Large-scale estimation of effective dose (ED) for positron emission tomography (PET)/computed tomography (CT) remains limited. This study aimed to determine the ED of torso 18F-fluorodeoxyglucose (FDG) PET/CT using extensive real-world clinical data from a high-volume centre. Differences in ED were also evaluated according to PET/CT scanner type, patient sex, and body size. METHODS: A retrospective analysis was performed on PET/CT examinations from individuals aged ≥ 16 years and acquired between March 2019 and June 2022. Five PET/CT scanners were used during the study period. CT ED was calculated by multiplying the dose length product (DLP) by an ED/DLP conversion coefficient. PET ED was estimated using injected 18F-FDG activity and the conversion factor reported in International Commission on Radiological Protection Publication 106. Total PET/CT ED was computed as the sum of CT and PET ED values. RESULTS: A total of 51,784 examinations were analysed (mean age, 61.9 ± 12.6 years; 29,990 men). Mean CT ED was 3.7 ± 1.5 mSv in men and 3.7 ± 1.7 mSv in women. CT ED varied according to scanner type and protocol, with newer scanners and advanced image processing technologies associated with lower radiation exposure. A strong positive correlation was observed between volume CT dose index and body mass index across all scanners. Mean PET ED of PET was 6.6 ± 1.1 mSv in men and 5.6 ± 1.0 mSv in women. Mean total PET/CT ED was 10.2 ± 2.4 mSv in men and 9.3 ± 2.5 mSv in women. CONCLUSIONS: The mean ED of torso 18F-FDG PET/CT derived from extensive real-world clinical data was comparable to that of conventional diagnostic CT. Both patient-related factors, including sex and body size, and scanner-specific characteristics, such as dose modulation algorithms, significantly influenced ED. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13184019/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147644476","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of dual-energy window scatter correction on technetium image quality across different energy windows in cadmium-zinc-telluride-based SPECT/CT.","authors":"Ruyi Zhang, Shen Wang, Yiming Shen, Wei Zheng, Ning Li, Peng Wang, Jian Tan, Zhaowei Meng, Qiang Jia","doi":"10.1186/s40658-026-00844-w","DOIUrl":"10.1186/s40658-026-00844-w","url":null,"abstract":"<p><strong>Background: </strong>The digital cadmium-zinc-telluride (CZT)-based SPECT system offers good energy resolution. However, the impacts of dual-energy window scatter correction on image quality under narrower primary energy windows remain to be determined. This study aimed to assess the impacts of SC (with scatter correction) and NOSC (without scatter correction) on image quality under different primary energy windows.</p><p><strong>Methods: </strong>We used a standard NEMA/IEC 2007 phantom containing six hollow spheres of various sizes to simulate the human body at four target-to-background ratios (T/B ratio, the ratio of the average radioactive activity concentration in the target region to that in the background region, 32:1, 16:1, 8:1, and 4:1, respectively), by filling with ^99mTcO₄^-. For clinical validation, we recruited 20 patients and analyzed their whole-body bone scan images. Phantom and patient images were acquired with the Discovery NM/CT 670 CZT with list mode. Image quality of phantom was measured by calculating indicators from the NEMA NU 2-2018 standard, including percent background variability and percent contrast. Image quality of patients was measured by calculating coefficient of variation (COV), contrast-to-noise ratio (CNR), and signal-to-noise ratio (SNR). Visual quality was evaluated by two experts.</p><p><strong>Results: </strong>Higher percent background variability and COV values were present when SC was applied regardless of which energy window, acquisition time, or T/B ratio used, and statistically significant differences were observed between all SC and NOSC groups for both phantoms and patients. For phantoms, percent contrast values of most SC groups were higher than those of NOSC groups. For patients, CNRs and SNRs of SC groups were higher than those of NOSC groups (all P < 0.05). Visually, SC had higher visual scores than NOSC for both phantoms and patients.</p><p><strong>Conclusions: </strong>SC significantly improves image contrast while minimizing concomitant image noise to a great extent and provides good visual image quality across different primary energy windows overall.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":"13 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13062129/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147638260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep learning-enhanced data-driven gating improves FDG PET/CT clinical image quality.","authors":"Zoë Wilson, Meghi Dedja, Kuan-Hao Su, Robert Johnsen, Kevin M Bradley, Daniel R McGowan","doi":"10.1186/s40658-026-00851-x","DOIUrl":"10.1186/s40658-026-00851-x","url":null,"abstract":"<p><p>BACKGROUND: Respiratory motion can affect PET image quality. One way to reduce motion effects is respiratory gating. The objective of this study, as we seek to further optimise Data-Driven Gating (DDG) algorithms, is to compare two types of DDG phase-gating methodologies: Method-1 has fixed quiescent period offset while Method-2 has an optimised offset for each cycle based on the amplitude of the waveform. The use of Deep Learning is becoming more prevalent for medical images. A previously validated Deep Learning Enhancement (DLE) algorithm will be assessed in conjunction with DDG PET data as an additional method to improve clinical images impacted by respiratory motion. Six reconstructions were assessed: Ungated 3 min (Clinical Standard), Ungated 6 min (Gold Standard), both gating methods with BSREM reconstructions, and both gating methods with OSEM + DLE. These six reconstructions were compared with data from the NEMA IQ phantom, placed on the QUASAR motion platform. Contrast Recovery (CR), Background Variability (BV) and Contrast to Noise Ratio (CNR) were calculated across 6 hot spheres. The same six reconstructions were assessed for 39 FDG PET-CT patient scans with lesions in the lungs or liver. All patients were identified as “high motion” patients with lesions in the region of interest. An experienced radiologist ranked the images and scored them on a 5-point Likert Scale for lesion detectability, diagnostic confidence, and image quality. Lesion maximum standard uptake value (SUVmax) and liver background noise were analysed across all images. RESULTS: The DLE methods with both gating methods demonstrated significantly better CNR than the ungated images in the phantom data (p<0.05). The performance of DLE with DDG data was also supported by the clinician’s preferences and decreased liver noise across the patient reconstructions. Both phantom and patient data indicated a slight preference for Method 2 for patients with irregular breathing. CONCLUSIONS: DLE algorithm effectively produces BSREM-like images from OSEM inputs with data-driven gated data. Clinician preference strongly indicated a preference for the two DDG DLE methods (p<0.05). Preliminary results may indicate an improved image quality with cycle-specific phase offset gated images for patients with irregular breathing patterns characterized by breathing period variance. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13176395/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147621851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Intravascular position-sensitive positron-counting catheter for atherosclerotic plaques.","authors":"Takehiro Nakahara, Shinichiro Fujimoto, Jagat Narula, H William Strauss, Navneet Narula, Tohru Minamino, Hiroyuki Daida, Masahiro Jinzaki","doi":"10.1186/s40658-026-00861-9","DOIUrl":"10.1186/s40658-026-00861-9","url":null,"abstract":"<p><p>PURPOSE: Rupture prone high-risk atheromatous plaques are characterized by large necrotic core volumes covered by thin fibrous caps which are positively remodeled; these plaques are significantly inflamed by the cells of monocyte-macrophage origin. We propose that the development of a position-sensitive positron-counting catheter, adding directionality with lead shields (sCath), would help record quantitative location-specific uptake of specifically targeted radiotracers against inflammation. METHODS: For in-vitro study, the catheter was placed on 18F point sources to measure the radioactivity counts. For ex-vivo study, the 9 aortas dissected from the rabbit model of atherosclerosis were exposed, and catheters were pulled back every 1 cm and counts measured the for 1 min by non-shielded catheter (nsCath), sCath-R (right side) and sCath-L (left side). RESULTS: In-vitro study showed linear correlation between counts and 18F point source dose until at least 100 kBq (r = 0.98, p < 0.0001). In ex-vivo study, total 100 sections were obtained from 9 aortas and counts-per-minute (cpm) from each catheter nsCath, sCath-R, -L and the average of sCath-R and -L demonstrated high correlation coefficients with quantitative %ID/g (r = 0.49, 0.38, and 0.48, 0.48, respectively. p < 0.0001). They showed excellent agreement with ipsilateral macrophage numbers (sCath-R: r = 0.80, sCath-L: r = 0.73, p < 0.0001). Although the average macrophage numbers correlated with sCath-average of both sides (r = 0.80, p < 0.0001) and non-shielded Cath (nsCath) (r = 0.48, p < 0.0001), the positron count rate of sCath showed stronger correlation with ipsilateral macrohpage number. CONCLUSION: The directional superiority of sCath should potentially be useful in ecentric plaques for inflammation localization, compared with circumferential inflammatory load by the use of nsCath. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13176407/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147621865","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mitigating bladder signal in ⁶⁸Ga-PSMA-11 PET/CT for prostate cancer: a clinical comparative study of dynamic whole-body parametric imaging.","authors":"Rui Zuo, Mu Kong, Fei Kang, Chunxiao Zheng, Ying Jiang, Qin Wang, Hua Pang, Zhengjie Wang, Jing Wang","doi":"10.1186/s40658-026-00862-8","DOIUrl":"10.1186/s40658-026-00862-8","url":null,"abstract":"<p><strong>Background: </strong>The pharmacokinetics of ⁶⁸Ga-PSMA-11 leads to intense bladder accumulation, obscuring adjacent lesions. This study evaluated the feasibility of dynamic whole-body ⁶⁸Ga-PSMA-11 PET/CT Patlak parametric imaging to reduce bladder signal interference, and compared the difference between the long axial field of view (LAFOV) PET/CT and short axial field of view (SAFOV) PET/CT.</p><p><strong>Results: </strong>A total of 18 patients with prostate cancer were prospectively enrolled in this study, 9 patients were scanned on the uMI Panorama GS (FOV = 148 cm), and the other 9 patients were scanned on the uMI Panorama 35 C (FOV = 35 cm). The V images demonstrated a significant reduction in bladder TBR [LAFOV: TBR_SUV: 26.71 (14.50-34.83) vs. TBR_V: 0, P < 0.001; SAFOV: TBR_SUV: 14.56 (12.64-17.97) vs. TBR_V: 0.08 (0-1.42), P < 0.001] and SV [LAFOV: TBR_SUV: 154.06 ± 86.64 cm³ vs. SV_V: 0.94 ± 2.83 cm³, P < 0.001; SAFOV: SV_SUV: 174.33 ± 95.48 cm³ vs. SV_V: 12.90 ± 11.41 cm³, P < 0.001], achieving a 99.5% and 91.0% volume reduction in LAFOV and SAFOV PET, respectively. Prostatic base obscuration occurred in 33.3% (3 + 3/18) of SUV images (score = 2) but was absent in V images. All primary prostate lesions (15/15) and 96.7% (58/60) metastases were detected on V images in LAFOV PET. All primary prostate lesions (10/10) and 90.9% (20/22) metastases were detected on V images in SAFOV PET. In LAFOV PET, whether it is a primary or metastatic lesion, TBR_SUV is higher than TBR_V, but lower than TBR_Ki, all of which differ significantly. In SAFOV PET, lymph node metastases exhibited higher, while bone metastases showed no significant TBR difference, and primary prostate TBR_V was lower than TBR_SUV but remained above background. Compared with SAFOV PET, TBR_SUV, TBR_V, TBR_Ki of LAFOV PET were significantly higher (all P < 0.01).</p><p><strong>Conclusions: </strong>Patlak V imaging significantly reduces bladder signal intensity and obscuration in ⁶⁸Ga-PSMA-11 PET/CT while preserving lesion TBR, enabling improved visualization of prostatic base lesions. Whether LAFOV or SAFOV PET, dynamic whole-body Patlak parametric imaging is feasible for mitigating bladder interference. Our results indicate that parametric imaging contributes to improved clinical evaluation of prostate cancer lesions.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13176365/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147618529","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Performance of high-resolution PET detectors consisting of long GAGG slabs with different reflectors.","authors":"Zhonghua Kuang, Samuel Mungai Kinyanjui, Ling Zhang, Ning Ren, Zheng Liu, Qiaolai Tan, Jianquan Huang, Zhanli Hu, Yongfeng Yang","doi":"10.1186/s40658-026-00856-6","DOIUrl":"10.1186/s40658-026-00856-6","url":null,"abstract":"&lt;p&gt;&lt;strong&gt;Background: &lt;/strong&gt;Depth of interaction (DOI) encoding detectors are essential for pre-clinical or organ-dedicated PET scanners to simultaneously achieve high spatial resolution and high sensitivity. Semi-monolithic scintillator PET detectors inherently possess the DOI encoding capability that monolithic scintillator detectors have and can also improve the spatial resolution of the detector by reducing the edge effect. Compared to the widely used lutetium yttrium oxyorthosilicate (LYSO) scintillator, the newly developed gadolinium aluminum gallium garnet (GAGG) scintillator has a higher light output, which may lead to a better energy resolution and higher three-dimensional positioning accuracy in semi-monolithic PET detectors.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Methods: &lt;/strong&gt;The semi-monolithic scintillator detectors consisted of 12 long GAGG slabs of 0.96 ⋅ 56 ⋅ 10 mm&lt;sup&gt;3&lt;/sup&gt;, with one using BaSO&lt;sub&gt;4&lt;/sub&gt; (detector 1) and the other using ESR (detector 2) as the reflector between the slabs. The front and two end surfaces of the slabs were painted with black ink. The detectors were single-ended read out by a 4×16 silicon photomultiplier (SiPM) array with an active pixel area of 3×3 mm&lt;sup&gt;2&lt;/sup&gt; and a pitch of 3.65 mm. A row and column summing signal readout circuit was used to convert the 64 SiPM signals into 4 row and 16 column signals. Different monolthic (y) and DOI (z) positions of the detector were selectively irradiated by using an electronic collimation plus a mechanical collimation. The electronic collimation is realized by using a 0.3 mm diameter &lt;sup&gt;22&lt;/sup&gt;Na point source and a coincidence reference detector consisting of a single LYSO crystal of 1×1×20 mm&lt;sup&gt;3&lt;/sup&gt;. The mechanical collimation is realized by using a 5 mm thick tungsten block with a 1 mm diameter hole drilled. The centroid of gravity (COG) and squared COG algorithms were used to determine the y position, and the inverse standard deviation algorithm was applied to obtain the DOI information.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Results: &lt;/strong&gt;All slabs are clearly identified from the flood histograms of both detectors. The average peak-to-valley ratios (PVRs), calculated from the line profiles through the center y-axis of the flood histograms, are 3.96 and 3.55 for detectors 1 and 2, respectively. The average energy resolutions are 15.6 ± 1.8% for detector 1 and 14.7 ± 1.2% for detector 2. The COG method provides y-position resolutions of 2.21 ± 0.77 mm for detector 1 and 2.16 ± 0.55 mm for detector 2, whereas the squared COG method provides y-position resolutions of 1.60 ± 0.32 mm and 1.59 ± 0.26 mm, respectively. The average DOI resolutions are 2.33 ± 0.68 mm for detector 1 and 2.37 ± 0.58 mm for detector 2. The average timing resolutions are 4.30 ± 0.57 ns for detector 1 and 4.76 ± 0.56 ns for detector 2. Compared to the detector using LYSO scintillator slabs, the detector using GAGG scintillator slabs provides similar y-position and DOI resolutions, a better energy resolution, a ","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13046888/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147503394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Smart scanning for two: [¹⁸F]FDG dose optimization for pregnant patients using LAFOV PET/CT technology.","authors":"Ilja S Deurloo, Milou M Steemers-de Boer, Johannes H van Snick, Klaas Pieter Koopmans, Riemer H J A Slart, Walter Noordzij, Adrienne H Brouwers, Gilles N Stormezand, Ton Velleman, Erik H J G Aarntzen, Berlinda J de Wit-van der Veen, Wouter V Vogel, Sanne M Jansen, Arthur J A T Braat, Andor W J M Glaudemans, Oleksandra V Ivashchenko","doi":"10.1186/s40658-026-00855-7","DOIUrl":"10.1186/s40658-026-00855-7","url":null,"abstract":"<p><strong>Purpose: </strong>This study aimed to evaluate the image quality-dose trade-off in pregnant patients imaged with long-axial field-of-view [¹⁸F]FDG PET/CT and to identify the most predictive body composition metric for image quality to develop a pregnancy-tailored dosage model.</p><p><strong>Methods: </strong>Patients imaged with [¹⁸F]FDG PET/CT according to local pregnancy protocols were included in this study. Using raw PET data, images of various degrees of image quality were reconstructed. Acceptable image quality was identified using signal-to-noise ratio (SNR) in the liver and Likert scores. The minimum required scan statistics was modelled based on SNR and patient body composition. F-tests were used to find the best-fitting model parameter out of weight, weight-to-height-ratio, body-mass-index, and body surface area (BSA). Foetal dose was estimated with PET conversion factors and size-specific CT dose index values.</p><p><strong>Results: </strong>Eleven patients were included in image quality analysis and dosage model optimization. SNR strongly correlated with Likert scores (R² = 0.80), with 10.72 SNR indicating acceptable image quality. BSA best predicted image quality (R² = 0.85), outperforming weight (R² = 0.78), weight-to-height ratio (R² = 0.63), and body mass index (R² = 0.38). The proposed dosage model reduces activity by 41-96% compared to current local pregnancy and adult protocols, resulting in estimated foetal radiation doses of 0.066 mGy (PET) and 0.31 mGy (CT).</p><p><strong>Conclusion: </strong>BSA accurately predicted [¹⁸F]FDG PET/CT image quality in pregnant patients. The proposed dosage regimen allows significant dose reduction and can be used as a foundation for the development of pregnancy dosage protocols.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13106102/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147472977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An international study of factors affecting variability of dosimetry calculations, part 5: impact of segmentation methods.","authors":"Sara Kurkowska, Yuni K Dewaraja, Eric C Frey, Julia Brosch-Lenz, John Sunderland, Carlos Uribe","doi":"10.1186/s40658-026-00848-6","DOIUrl":"10.1186/s40658-026-00848-6","url":null,"abstract":"<p><strong>Background: </strong>Individualized radiopharmaceutical therapies guided by patient-specific absorbed dose assessments using imaging have the potential to improve both efficacy and safety. Understanding sources of variability in absorbed dose calculations is critical for standardization. The Society of Nuclear Medicine and Molecular Imaging Dosimetry Task Force launched the ¹⁷⁷Lu Dosimetry Challenge to evaluate variability across different steps within the dosimetry workflow. This work aimed to assess the variability in absorbed doses due to differences in segmentation methods.</p><p><strong>Methods: </strong>Anonymized datasets from two patients treated with ¹⁷⁷Lu-DOTATATE, including serial SPECT/CT scans, were made available online. Participants were asked to segment healthy organs and lesions and perform dosimetry calculations. In a subsequent task, participants were provided with standardized segmented VOIs and asked to perform dosimetry based on these pre-defined regions. Variability in segmentation was assessed by comparing absorbed dose estimates across two scenarios: participant-generated segmentations versus predefined reference segmentations. Relative absorbed dose variability was quantified using the quartile coefficient of dispersion (QCD) and interquartile range.</p><p><strong>Results: </strong>Variability in absorbed dose (measured as QCD difference between absorbed doses from participant-generated segmentations and those from reference segmentations) for kidneys was less than 5% in simple cases and 10.6% for more challenging scenarios (i.e. presence of intraparenchymal cysts, cortical defects). Lesion segmentation exhibited higher variability, with absorbed dose variability reaching up to 22.4%.</p><p><strong>Conclusions: </strong>Segmentation significantly contributes to variability in absorbed dose estimates, particularly for lesions and for kidneys with anatomical complexities. Standardizing segmentation protocols and providing training on advanced segmentation methods are essential to reduce variability.</p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13096261/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147442938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Whole-body parametric PET/CT imaging of the total distribution volume using a new reversible delayed Logan model.","authors":"Josefine R Madsen, Patricia B Danielsen, André H Dias, Lars C Gormsen, Anders B Rodell, Vladimir Panin, David Pigg, Bruce Spottiswoode, Ole L Munk","doi":"10.1186/s40658-026-00853-9","DOIUrl":"10.1186/s40658-026-00853-9","url":null,"abstract":"<p><p>PURPOSE: The widely used reversible Logan Model (LM) requires complete dynamic tissue data to estimate the total distribution volume (Vt), which restricts Vt imaging to the PET scanner’s axial field-of-view (FOV). This study validates a novel reversible delayed Logan Model (DLM) for whole-body (WB) Vt imaging, requiring only late steady-state tissue data, to complement the irreversible Patlak model for WB parametric imaging. METHODS: DLM was validated using data from 50 patients scanned with [18F]FDG (FDG) and 10 patients scanned with [68Ga]Ga-PSMA-11 (Ga-PSMA) using a 70-minute dynamic WB (D-WB) PET acquisition protocol on a short-axial FOV (SAFOV) PET/CT scanner. Organs in the chest region were segmented and analyzed using an image-derived input function (IDIF). For FDG, the use of a population-based input function (PBIF) was tested. Region-based kinetic analysis and voxel-based Vt imaging were generated with LM (0–70 min post injection (p.i.)) and DLM (50–70 min p.i.). For comparisons, region-based LM analysis was considered the reference. RESULTS: We found good agreement between Vt images generated by DLM and the reference region-based LM with organ-specific biases less than 12% and 25% for FDG and Ga-PSMA, respectively. Parametric images generated by LM had higher biases. The Vt images generated by LM and DLM showed similar characteristics, but DLM images had fewer artifacts and extended across the WB range. Furthermore, biases below 2% were observed when utilizing the PBIF, which allows for short, clinically feasible D-WB protocols. CONCLUSION: DLM allows quantitative WB Vt imaging using both SAFOV and long-axial FOV (LAFOV) PET systems. Clinically feasible D-WB PET examinations (20-min for SAFOV, and 10-min for LAFOV) with PBIF produce excellent Vt image quality. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13096263/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147442903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhanced data usability in dynamic ⁶⁸ Ga-PSMA-11 PET of intracranial tumors using a dynamic head motion correction algorithm.","authors":"Risheng Yang, Kun Guo, Guiyu Li, Ying Guo, Taoqi Ma, Fei Kang, Jing Wang","doi":"10.1186/s40658-026-00843-x","DOIUrl":"10.1186/s40658-026-00843-x","url":null,"abstract":"<p><p>BACKGROUND: Head motion during dynamic positron emission tomography (dPET) compromises pharmacokinetic modeling, especially in prolonged acquisitions where motion artifacts invalidate quantitative analysis. Although motion correction methods are well-established for static PET, their application in dynamic imaging remains limited. This study evaluates the efficacy of a data-driven dynamic head motion correction (dHMC) algorithm in preserving the reliability of kinetic parameter, using dynamic 68 Ga-PSMA-11 PET of intracranial tumors as a challenging model due to the tracer’s inability to cross the blood–brain barrier, unlike the diffusely distributed 18F-FDG used in prior studies. METHODS: Sixteen patients with suspected glioma based on preoperative imaging underwent 40-min dynamic 68 Ga-PSMA-11 PET head scans. Head motion was categorized into minor and high-motion groups based on maximum displacement (> 3 mm) or time-weighted mean displacement (> 2 mm) within the tumor region. The performance of dHMC was evaluated in tumor and reference organs (parotid and lacrimal glands) based on fitting metrics, including the coefficient of determination (R2) and Akaike information criterion (AIC), and quantitative kinetic parameters. Time-activity curves (TACs) and key kinetic parameters (k2 and k3) were generated using an irreversible two-tissue compartment model (2T3k). RESULTS: dHMC robustly corrected motion-induced inaccuracies across motion levels, enabling analysis in 43.75% of previously non-analyzable cases. The algorithm yielded three major improvements without introducing bias: First, it significantly enhanced pharmacokinetic modeling fidelity, evidenced by smoother TACs, along with increased R2 values of 8.35%, 4.54%, and 30.9% in tumor, parotid, and lacrimal glands, respectively, and reduced AIC values by 6.95%, 5.33%, and 13.32%. Second, it improved the accuracy and homogeneity of k2 and k3 estimates in reference organs, indicated by significantly reduced data dispersion. Third, it brought the quantitative parameters of the parotid gland closer to established reference standards. All improvements were most pronounced in high-motion cases. CONCLUSION: The dHMC algorithm enhances fitting performance, parametric accuracy, and inter-frame consistency in dynamic 68 Ga-PSMA-11 PET, validating its broad applicability across varying motion scenarios and underscoring the essential role of motion correction in maintaining quantitative accuracy in dPET. </p>","PeriodicalId":11559,"journal":{"name":"EJNMMI Physics","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13096463/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147442873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}