World Journal of Nuclear Medicine最新文献

{"title":"3D-OSEM versus FORE + OSEM: Optimal Reconstruction Algorithm for FDG PET with a Short Acquisition Time.","authors":"Keisuke Tsuda,&nbsp;Takayuki Suzuki,&nbsp;Kazuhito Toya,&nbsp;Eisuke Sato,&nbsp;Hirofumi Fujii","doi":"10.1055/s-0043-1774418","DOIUrl":"https://doi.org/10.1055/s-0043-1774418","url":null,"abstract":"<p><p><b>Objective</b>  In this study, we investigated the optimal reconstruction algorithm in fluorodeoxyglucose (FDG) positron emission tomography (PET) with a short acquisition time. <b>Materials and Methods</b>  In the phantom study, six spheres filled with FDG solution (sphere size: 6.23-37 mm; radioactivity ratio of spheres to background = 8:1) and placed in a National Electrical Manufacturers Association phantom were evaluated. Image acquisition time was 15 to 180 seconds, and the obtained image data were reconstructed using each of the Fourier rebinning (FORE) + ordered subsets expectation-maximization (OSEM) and 3D-OSEM algorithms. In the clinical study, mid-abdominal images of 19 patients were evaluated using regions of interest placed on areas of low, intermediate, and high radioactivity. All obtained images were investigated visually, and quantitatively using maximum standardized uptake value (SUV) and coefficient of variation (CV). <b>Results</b>  In the phantom study, FORE + OSEM images with a short acquisition time had large CVs (poor image quality) but comparatively constant maximum SUVs. 3D-OSEM images showed comparatively constant CVs (good image quality) but significantly low maximum SUVs. The results of visual evaluation were well correlated with those of quantitative evaluation. Small spheres were obscured on 3D-OSEM images with short acquisition time, but image quality was not greatly deteriorated. The clinical and phantom studies yielded similar results. <b>Conclusion</b>  FDG PET images with a short acquisition time reconstructed by FORE + OSEM showed poorer image quality than by 3D-OSEM. However, images obtained with a short acquisition time and reconstructed with FORE + OSEM showed clearer FDG uptake and more useful than 3D-OSEM in the light of the detection of lesions.</p>","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10581748/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49682934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Prognostic Value of Sequential ¹⁸ F-FDG PET/CT Metabolic Parameters in Outcomes of Upper-Third Esophageal Squamous Cell Carcinoma Patients Treated with Definitive Chemoradiotherapy.","authors":"Le Ngoc Ha,&nbsp;Nguyen Dinh Chau,&nbsp;Bui Quang Bieu,&nbsp;Mai Hong Son","doi":"10.1055/s-0043-1774417","DOIUrl":"https://doi.org/10.1055/s-0043-1774417","url":null,"abstract":"<p><p><b>Objective</b>  The aim of this study is to determine prognostic values of sequential ¹⁸ F-FDG PET/CT metabolic parameters in locally advanced esophageal squamous cell carcinoma (ESCC) patients treated with definitive chemoradiotherapy. <b>Materials and Methods</b>  Forty locally advanced ESCC patients treated with definitive chemoradiotherapy (dCRT) who received pre-treatment ¹⁸ F-FDG PET/CT (PET1) and 3-months post-treatment ¹⁸ F-FDG PET/CT (PET2) were enrolled in the prospective study. ¹⁸ F-FDG PET parameters of the primary tumor including maximum and mean standardized uptake values (SUVmax, SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were calculated on PET delineated primary tumor. Using Kaplan-Meier curves to estimated overall survival (OS), progression-free survival (PFS), and local-regional control (LRC). Cox regression analysis was performed to find significant prognostic factors for survival. <b>Results</b>  With a median follow-up of 13.5 months, the 4-year OS, PFS, and LRC rates were 67.3%, 52.6%, and 53.4% respectively. Patients with MTV 2 > 5.7 had lower OS, PFS, and LRC rates than the lower MTV 2 group (p < 0.05). Univariate Cox regression analysis showed that MTV2 was a significant prognostic factor for OS, PFS, and LRC (p < 0.05). <b>Conclusion</b>  MTV parameter of sequential ¹⁸ F-FDG PET/CT could be used as a prognostic factor for OS, PFS, and LRC in locally advanced ESCC patients treated with dCRT.</p>","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10581756/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49682939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Radiation Safety and External Radiation Exposure Rate of Patients Receiving I-131 Therapy for Hyperthyroidism and Remnant Ablation as Outpatient: An Institutional Experience","authors":"Nisha Bhatia, Vandana K. Dhingra, Pulkit Mittal, Sunil Saini","doi":"10.1055/s-0043-1771285","DOIUrl":"https://doi.org/10.1055/s-0043-1771285","url":null,"abstract":"Abstract Objective  Our objective was to study the radiation exposure rate as function of time in the administration of radioiodine iodine-131 (I-131) for the treatment of thyrotoxicosis or Graves' disease and remnant ablation on an outpatient basis at the Department of Nuclear Medicine, and also, to study the impact of revised discharge criteria for radioiodine therapy enforced by the Atomic Energy Regulatory Board (AERB) of India. Materials and Methods  This study included patients who underwent low-dose radioiodine therapy using I-131. Patients were classified into two different groups, that is, group A and group B. Group A included patients receiving low dose I-131 for the treatment of thyrotoxicosis, whereas group B included patients receiving I-131 therapy for the ablation of residual thyroid tissue after total thyroidectomy. The radiation exposure rate was measured using a radiation detector in milli roentgen per hour (mR/h) at 5 cm distance of stomach and neck levels and with the patient standing at the distance of 1 m after oral administration of I-131 at 0, 1, and 2 hours. Results  A total of 134 (17 males and 117 females) patients were included in the study. Group A comprised 102 (14 male and 88 females) patients and group B of 32 (3 males and 29 females) patients. At the neck level, the average exposure rate in group A versus group B after 0, 1, and 2 hours was observed to be 6.9 versus 22.27 mR/h, 33.67 versus 43.39 mR/h, and 41.75 versus 48.90 mR/h, respectively. At the stomach level, the exposure rate was 23.65 versus 71.32 mR/h, 13.27 versus 48.45 mR/h, and 9.91 versus 39.43 mR/h after 0, 1, and 2 hours, respectively. At a distance of 1 m, the exposure rate was 1.31 versus 2.99 mR/h, 1.05 versus 2.58 mR/h, and 0.92 versus 2.21 mR/h, respectively. Conclusion  Exposure rate measured for patients treated with up to 1,110 MBq (30 mCi) of I-131 was under permissible limits as per revised discharged limits, that is, 50 µSv/h (5 mR/h) prescribed by AERB, India. The patients undergoing radioiodine therapy I-131 (up to 1,110 MBq/30 mCi) can be discharged safely 2 hours postadministration following good work practice along with providing proper radiation safety instructions to patients.","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47601736","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adverse Allergic Reaction to Intrathecally Administered Technetium-99m Diethylenetriamine Pentaacetate: A Case Report","authors":"Ahalya Nair, Guneshwaran Poolpandian, Kabilash Dhayalan, Jayaram Saibaba","doi":"10.1055/s-0043-1771281","DOIUrl":"https://doi.org/10.1055/s-0043-1771281","url":null,"abstract":"Abstract Intrathecal administration of radiopharmaceuticals is an infrequently performed procedure in most nuclear medicine facilities. It is possible that adverse allergic reactions following the intrathecal administration of radiopharmaceuticals often go unreported. Here we present a case of spontaneous cerebrospinal fluid rhinorrhea with recurrent bacterial meningitis, who underwent radionuclide cisternography for localization of the site of leak and developed an adverse allergic reaction following the intrathecal administration of technetium-99m diethylenetriamine pentaacetate that resolved with appropriate treatment. Imaging, however, could be carried out to our satisfaction and the allergic reaction did not interfere with, or result in discontinuation of the scan procedure.","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45986712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Establishing a Cutoff Serum Thyroglobulin Value for the Diagnosis and Management of Well-Differentiated Thyroid Cancer.","authors":"Jiwan Paudel","doi":"10.1055/s-0043-1771286","DOIUrl":"10.1055/s-0043-1771286","url":null,"abstract":"<p><p><b>Objective</b>  The aim of this study was to define a cutoff serum thyroglobulin (Tg) level associated with either residual or metastasis that may help decide postoperative radioactive iodine (RAI) scan and treatment in differentiated thyroid cancer (DTC) patients residing in low-income countries like Nepal. <b>Methods</b>  We prospectively studied a total of 81 patients (female-to-male ratio of 3.0:1; mean age: 37.3 ± 14.0 years, within age range of 14-88 years) who underwent total thyroidectomy with/without neck dissection and were referred for RAI whole-body scan (WBS) ± RAI ablation or adjuvant treatment in the department of Nuclear Medicine, Chitwan Medical College. We calculated the cutoff value of Tg using receiver operating characteristic (ROC) curve analysis. <b>Results</b>  Forty-six of 81 patients (56.7%) had remnants in the thyroid bed, 26/81 (32.1%) had regional lymph node metastasis, 9/81 (11.1%) had distant lymph node metastasis, 3/81 (3.7%) had lung metastases, and only 1/81 (1.2%) had bone metastases. RAI WBS was positive in 61/81 (75.3%) patients and negative in 20/81 (24.7%) patients. Seventeen of 81 (20.9%) patients had negative RAI scans with low serum Tg levels; only 3/81 (3.7%) patients had Tg elevated negative RAI scan (TENIS). Although scan was positive in 61/81 (75.3%) patients, 64/81 (79.0%) patients received treatment with RAI, of which 3/81 (3.7%) patients were TENIS patients. There was a significant difference in serum Tg levels between patients who received or did not receive RAI ablation or treatment ( <i>p</i>  < 0.05). On ROC curve analysis, the cutoff value of Tg levels between patients who received and did not receive treatment was 2.9 ng/mL (sensitivity: 85.9%; specificity: 94.1%; positive predictive value [PPV], 98.2%; negative predictive value [NPV]: 64.0%; AUC: 0.938). <b>Conclusion</b>  We identified a cutoff value of 2.9 ng/mL between patients who required or did not require treatment with high sensitivity, specificity, and PPVs.</p>","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10581758/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48001005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of 18 F-FDG PET-CT in Urethral Malignant Melanoma and Analysis of the UK Guidelines on Ano-uro-genital Melanomas","authors":"Abhishek Mahato, Anurag Jain, M.G. Manoj, Richa Joshi","doi":"10.1055/s-0043-1771280","DOIUrl":"https://doi.org/10.1055/s-0043-1771280","url":null,"abstract":"Abstract Urethral melanomas are a rare subtype of noncutaneous melanomas. The disease has a tendency to have skip lesions and early metastases as compared with cutaneous melanomas. The role of fluorine-18 fluorodeoxyglucose ( 18 F-FDG) positron emission tomography computed tomography (PET-CT) is well established in cases of cutaneous melanomas and is recommended by the National Comprehensive Cancer Network (NCCN) for stage IIB to IV cancer. There are no established guidelines on the management of noncutaneous melanomas; however, a recently published United Kingdom national guideline aims to streamline the management of ano-uro-genital melanomas. The guideline describes a very limited role in the use of 18 F-FDG PET-CT in this case scenario. The tendency to skip lesions, early metastases, involvement of brain parenchyma, and finally the usage of anti-PD-1 medications are key areas where 18 F-FDG PET-CT has shown superiority over CT scan. With this case report, we aim to highlight the strength of 18 F-FDG PET-CT in the management of urethral melanomas, which can be extrapolated to other ano-uro-genital melanomas.","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41272306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimization of the Acquisition Time and Injected Dose of 18 F-Fluorodeoxyglucose Based on Patient Specifications for High-Sensitive Positron Emission Tomography/Computed Tomography Scanner","authors":"M. Al-Fatlawi, Farideh Pak, Saeed Farzanefar, Yalda Salehi, Abbas Monsef, P. Sheikhzadeh","doi":"10.1055/s-0043-1771284","DOIUrl":"https://doi.org/10.1055/s-0043-1771284","url":null,"abstract":"Abstract: Background  This study was aimed to optimize the fluorodeoxyglucose (FDG)-administered dose and scan time based on patient specifications using a highly sensitive five-ring bismuth germanium oxide (BGO)-based positron emission tomography/computed tomography (PET/CT) scanner (Discovery IQ). Methods  We retrospectively analyzed 101 whole-body 18 F-FDG PET/CT images. Patient data were reconstructed using ordered subset expectation maximization with resolution recovery algorithms (OSEM + SharpIR). Signal-to-noise ratio (SNR) was calculated for each patient, standardized to SNR norm , and plotted against three body index parameters (weight, body mass index, and lean body mass). Two professional physicians blindly examined image quality at different patient time per bed positions to determine the minimum acceptable quality. To select images of acceptable quality, the noise index parameter was also measured. A new dose-time product (DTP) was established for each patient, and a predicted injected dose was assumed. Results  We found an almost linear association between patient weight and normalized SNR, and patient weight had the highest R 2 in the fitting. The redesigned DTP can reduce results by approximately 74 and 38% compared with ordinary DTP for 80- and 160-s scan durations. The new dose regimen formula was found to be DTP =  c/t × m 1.24 , where m is the patient weight, t is the scan time per bed position, and c is 1.8 and 4.3 for acceptable and higher confidence states, respectively, in Discovery IQ PET/CT. Conclusion  Patient weight is the best clinical parameter for the implementation of 18 F-FDG PET/CT image quality assessment. A new dose-time regimen based on body weight was proposed for use in highly sensitive five-ring BGO PET-CT scanners to significantly reduce the injection dose and scan times while maintaining sufficient image quality for diagnosis.","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47130800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FDG PET/CT Depicting Right Iliac Vein Tumor Thrombosis following Low Anterior Resection in Rectal Cancer Patient: A Case Report and Literature Review","authors":"Akram Al-Ibraheem, Serin Moghrabi","doi":"10.1055/s-0043-1771288","DOIUrl":"https://doi.org/10.1055/s-0043-1771288","url":null,"abstract":"Abstract Venous tumor thrombus is a rare complication of rectal cancer but is more common in other types of cancer, like renal cell carcinoma and hepatocellular carcinoma. The usual site of tumor thrombus in rectal cancer patients is the inferior mesenteric vein (IMV), which is seldom seen in the common iliac vein, with only a few cases reported till now. We present a case of fluorodeoxyglucose (FDG) avid right iliac vein tumor thrombosis after low anterior resection in a patient with rectal cancer and review the literature.","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42561427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Use of Oral Empagliflozin to Obtain Optimal Blood Sugar Levels for Conducting 18 F-FDG PET-CT in Patients with Hyperglycemia—A Pilot Study","authors":"Abhishek Mahato, Anurag Jain, V.S Prakash, Rajesh Nair, Richa Joshi, D. Paliwal, Awadhesh Tiwari, S. Khandpur, Harkirat Singh","doi":"10.1055/s-0043-1771283","DOIUrl":"https://doi.org/10.1055/s-0043-1771283","url":null,"abstract":"Abstract Background  Flourine-18 fluorodeoxyglucose positron emission tomography-computed tomography ( 18 F-FDG PET-CT) is a well-established imaging modality for the evaluation of patients with oncological and nononcological conditions. The underlying principle of imaging is the preferentially increased glucose consumption by cancer cells, due to overexpression of glucose type 1 receptors that are insulin independent. Thus, one of the factors that leads to decreased sensitivity of an 18 F-FDG PET-CT is elevated blood sugar levels, leading to decreased glucose uptake by cancer cells due to competitive inhibition. A significant percentage of patients scheduled for PET-CT scan has diabetes mellitus type II as a comorbid condition and often has elevated random blood sugar (RBS) precluding an upfront PET-CT evaluation. Such cases must be rescheduled. This causes delay in the evaluation and management of such patients. Empagliflozin is a novel sodium glucose type 2 inhibitor that prevents tubular reabsorption of glucose and increases renal glycosuria resulting in decreased blood sugar. This drug does not cause significant hypoglycemia or increase endogenous insulin secretion. This study was undertaken to evaluate a potential role for empagliflozin in facilitating optimal blood sugar control in patients with hyperglycemia on the day of the scheduled PET scan. Methods  This is an interventional prospective study and patients detected to have RBS more than 200 mg/dL on the day of the scheduled scan were included in the study. The patients were administered two tablets of 10 mg empagliflozin and kept under observation. Samples for RBS were taken at approximately 2nd and 4th hour post administration by bedside method. These patients underwent scan on the same day after adequate sugar control and when an RBS of less than 200 mg/dL was achieved. The primary outcome studied was change in RBS values in the patient cohort and evaluation of PET SUV (standardized uptake value) compared with the rest of the patients scheduled on the same day. Secondary outcome was assessment of any side effects in the patients. Results  Total of 10 patients were found to have elevated blood sugar (RBS > 200 mg/dL; irrespective of being on medication) and did not meet the evaluation criteria for a PET-CT scan on the scheduled day. Following administration of the drug, all 10 patients were able to attain blood sugar levels and fulfill the criteria for undergoing a PET-CT scan. No obvious side effect was noted in any of the patient. The SUV values of the patient cohort were comparable with the rest of the patient scanned on the day. Conclusion  In this pilot study, 20 mg of empagliflozin (2 tablets of 10 mg) appears to be a safe and effective method for achieving optimal decrease in the RBS without causing hypoglycemia or hyperinsulinemia. It can be safely employed in the subset of population with RBS between 201 and 300 mg/dL to adequately bring the sugar levels at acceptable levels","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45304706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of Wolfmet Tungsten Alloys as Parallel-Hole Collimator Material on Single-Photon Emission Computed Tomography Image Quality and Functional Parameters: A Simulating Medical Imaging Nuclear Detectors Monte Carlo Study","authors":"Maryam Darami, B. Mahmoudian, Michael Ljungberg, Jalil Pirayesh Islamian","doi":"10.1055/s-0043-1771287","DOIUrl":"https://doi.org/10.1055/s-0043-1771287","url":null,"abstract":"Abstract Objectives  Collimators have a significant role in image quality and detectability in single-photon emission computed tomography (SPECT) imaging. Using an appropriate alloy that effectively absorbs scattered photons, without induced secondary x-rays, and with proper rigidity and weight may provide an effective approach to the image improvement that conventionally collimators made of lead (Pb). Materials and Methods  A Siemens E.CAM SPECT imaging system equipped with low-energy high-resolution (LEHR) collimator was simulated by the Simulating Medical Imaging Nuclear Detectors Monte Carlo program. Experimental and simulated data were compared based on a 2-mm 99m Tc point source in an acrylic cylindrical Deluxe phantom (Data Spectrum, Inc). Seven types of tungsten (W) alloys (Wolfmet), with W content from 90 to 97% by weight, were then used as collimator materials of the simulated system. Camera parameters, such as energy- and spatial resolution, image contrast, and collimator-related parameters, such as fraction of septal penetration, scatter-to-primary ratios, and percentage of induced secondary x-rays, due to interactions in the collimator, were evaluated. Results  Acceptable conformity was found for the simulated and experiment systems in terms of energy spectra, 10.113 and 10.140%, full width at half-maximum (FWHM) of the point spread function (PSF) curves, 8.78 and 9.06 mm, sensitivity, 78.46 and 78.34 cps/MBq, and contrast in images of 19.1 mm cold spheres in the Deluxe phantom, 79.17 and 78.97%, respectively. Results on the parameters of the simulated system with LEHR collimator made from the alloys showed that the alloy consisting of 90% W, 6% nickel, and 4% copper provided an FWHM of 8.76 mm, resulting in a 0.2% improvement in spatial resolution. Furthermore, all the Wolfmet collimators showed a 48% reduction in the amount of X-rays production compared to the Pb. Conclusion  A Wolfmet LEHR collimator, made by a combination of W (90%), Ni (6%), and Cu (6%) provides a better image quality and detectability compared to the Pb.","PeriodicalId":23742,"journal":{"name":"World Journal of Nuclear Medicine","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45080482","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}