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The quality control of nuclear medicine imaging equipment is essential to ensure the quality and safety of nuclear medicine imaging. Phantoms are indispensable tools in quality control, performance comparison, and multicenter clinical trials of nuclear medicine imaging equipment. The structure of phantoms is developed from a simple form to a complicated form which can simulate real clinical conditions, and they are provided in various forms in combination with modern technologies. Different types of phantoms have their unique advantages and application situations. This article investigated and summarizes common phantoms and their performance evaluation indicators used in nuclear medicine imaging to provide a reference for the quality control of nuclear medicine equipment and selection of phantoms for clinical research.
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@#Positron emission tomography/computed tomography (PET/CT) scanner is an irreplaceable instrument in clinical diagnosis. The exposure dose that a patient receives is the sum of the doses caused by PET and CT examination. This study discussed the exposure dose level that a patient received during PET/CT examination according to the research data. Like other radiological diagnostic methods, PET/CT examination brings benefits outweighing its radiation risk. It is not advisable to exaggerate or ignore the exposure dose. The patient’s exposure dose caused by PET/CT examination should be controlled as much as possible under the premise of meeting clinical needs.
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@#<b>Objective</b> To investigate the outcomes and prognostic factors of differentiated thyroid cancer (DTC) with bone metastasis. <b>Methods</b> A retrospective study was conducted on 108 DTC patients with bone metastasis who were treated in the Cancer Hospital of Chinese Academy of Medical Sciences. Kaplan-Meier survival curves were generated. Log-rank test and Cox proportional hazards model were used to screen the prognostic factors. The correlation between treatment and prognosis was analyzed. <b>Results</b> The median overall survival was 70 months. The 5-, 10-, 15-, and 20-year overall survival rates were 54.4%, 24.3%, 9.8%, and 4.3%, respectively. Univariate analysis showed improved prognosis in patients with single bone metastasis, without skeletal-relatedevents (SREs), and without cervical lymph node metastasis (<i>P </i>= 0.003-0.019). Patients who received combined treatments (<i>P</i> < 0.001) or <sup>131</sup>I treatment alone (<i>P</i> = 0.109) showed better prognosis than those without <sup>131</sup>I treatment. Multivariate analysis identified single bone metastases, SREs, and treatmentas independent prognostic factors. <b>Conclusion</b> In DTC patients with bone metastasis, good prognosis is significantly associated with single bone metastases, absence of SREs, and <sup>131</sup>I therapy in combination with other therapeutic approaches.
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Objective To study the radioactive concentration of 131I in the air of workplaces where sodium iodide [131I] oral solution was administrated for patients with differentiated thyroid cancer (DTC) in the Department of Nuclear Medicine, and to estimate the internal radiation dose to the staff. Methods Workplaces of radioiodine 131I therapy for DTC patients in the Department of Nuclear Medicine of a hospital were investigated. Air samples in 131I administration areas and treatment wards were collected respectively and were measured by low-background gamma-ray spectrometry to calculate the activity concentration of 131I in the air and to further estimate the internal radiation dose to staffs. Results The activity concentration in the 131I administration area within the first 3 h of administration was 3～187 Bq/m3. During administration and within the first 3 h of administration, the staff exposed in the administration area for 5～30 min received an internal radiation dose of 0.08～0.50 μSv and 0.00～0.04 μSv, respectively. The highest activity concentration of 131I in the air of the ward was measured on the day of administration, reaching 3091 Bq/m3. After patients were discharged, the activity concentration in the ward gradually decreased to 10～242 Bq/m3 within 48 h. Within 48 h after patients were discharged, the staff exposed in the ward for 5～30 min received an internal radiation dose of 0.01～14.11 μSv. Conclusion A high activity concentration of 131I in the air was recorded during administration for DTC patients in radioiodine 131I therapy, and thus we recommend remote instructed administration or administration through a shielded window. We also recommend that non-treatment related personnel except medical staffs should not enter the ward during patients’ hospitalization at which the activity concentration of 131I in the ward was the highest. After patients were discharged, a delayed entry into the ward is recommended to reduce the internal radiation dose.
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Objective To investigate the influence of PET/CT imaging conditions (acquisition time, bed overlap, reconstruction matrix, iteration times, filter kernel size, and attenuation correction) on the spatial resolution of images. Methods Two PET/CT devices, GE Discovery Elite and GE Discovery ST-16, were used to scan the elliptical column resolution model in one and two beds (list mode, acquisition time of 6 min). Images were reconstructed under the commonly used clinical reconstruction conditions (Elite: VPFX-S algorithm, ST-16: VUE Point HD algorithm) at 1-6 min/bed, different iteration times of 2-10 times, different filter kernel sizes of 2.0-10.0 mm (Elite), and different reconstruction matrices, with attenuation correction or not. The spatial resolution of reconstructed PET images was represented by the full width at half maximum (FWHM) of the line spread function. Results Under the clinical acquisition conditions, when the acquisition time was 1 min, 2 min, 3 min, 4 min, 5 min, and 6 min, the FWHMElite of spatial resolution at the center of field of view was (4.06 ± 0.08) mm, (4.05 ± 0.20) mm, (4.01 ± 0.01) mm, (4.05 ± 0.07) mm, (4.05 ± 0.03) mm, and (4.08 ± 0.06) mm, and the FWHMST-16 was (5.76 ± 0.12) mm, (5.72 ± 0.11) mm, (5.74 ± 0.09) mm, (5.78 ± 0.05) mm, (5.75 ± 0.09) mm, and (5.77 ± 0.07) mm. When the phantom was located in the center of one bed and the overlap of two beds, the line FWHMElite at the center was (4.04 ± 0.01) mm and (4.04 ± 0.01) mm, and the FWHMST-16 was (5.39 ± 0.19) mm and (5.38 ± 0.07) mm, respectively. The FWHMElite at the center was (4.07 ± 0.18) mm, (4.25 ± 0.10) mm, and (4.73 ± 0.08) mm at the matrices of 256 × 256, 192 × 192, and 128 × 128, respectively. The FWHMElite at the center was (4.65 ± 0.43) mm, (4.77 ± 0.27) mm, (4.02 ± 0.01) mm, (4.11 ± 0.04) mm, and (9.94 ± 0.01) mm at the filter kernel sizes of 2.0 mm-10.0 mm (interval of 2.0 mm), respectively. The FWHMElite at the center was (4.17 ± 0.27) mm, (4.27 ± 0.21) mm, (4.11 ± 0.05) mm, (4.18 ± 0.04) mm, and (4.12 ± 0.06) mm at 2-10 iterations (interval of 2 times), respectively. The FWHMElite at the center was (4.14 ± 0.01) mm and (4.18 ± 0.08) mm with and without attenuation correction, respectively. At the same acquisition time and bed, the spatial resolution of Elite images was improved by about 40.57% compared with that of ST-16 images. Conclusion The spatial resolution of images obtained at the matrix of 256 × 256 is higher than that of images obtained at the matrices of 192 × 192 and 128 × 128 in the same model. Elite images have the best spatial resolution at the reconstruction filter kernel size of 6.0 mm. Under the same imaging conditions, Elite images show significantly better spatial resolution compared with ST-16 images. Acquisition time, overlap of beds, iteration times, and attenuation correction have no significant effect on the spatial resolution of PET images.
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Nuclear medicine physicists play an important role in nuclear medicine, and they are also a significant part of medical physicists. This study investigated the regulations and requirements of international organizations such as International Atomic Energy Agency (IAEA) and International Organization Medical Physics (IOMP)for medical physicists in nuclear medicine, and discussed the necessity, role, responsibilities and the quantity requirements of nuclear medicine physicists staffing in hospitals according to the demand for nuclear medicine physicists and the present situation of nuclear medicine physicists in China, so as to provide a reference for the work of nuclear medicine physicists in China.
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Objective:To discuss the problems existing in the implementation of the Chinese health industry standard WS 523-2019 by testing SPECT device.Methods:Under the WS 523-2019 standards, a total of 10 SPECT devices were tested with regard to their SPECT reconstructed spatial resolution (SRSR), system planar sensitivity (SPS), system spatial resolution (SSR), whole body system spatial resolution (WSSR), intrinsic uniformity (IU), intrinsic count rate performance (ICR), intrinsic spatial resolution (ISR) and intrinsic spatial linearity(ISL).Result:Under the requirements of WS 523-2019 standards for qualified limits, there are 3 devices with ISL unqualified and the rest of the performances qualified. The new standards basically can meet the clinical requirements and reflected the overall performance of SPECT.Conclusions:The distance between the radiation source and the surface of the detector has great influence on the spatial resolution.In the measurement of ISL, there must be a lead grid separately in the x and y directions. The lead grids with the parallel slits shall be positioned on the detector with the center slit centered on the detector. It is suggested to add rotation center in the new standards.
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Objective To investigate the relationship between image quality of PET/CT in automatic tube current modulation and effective dose(ED) of patients and to determine the optimal acquisition scheme.Methods Scanning was performed on anthropomorphic phantom RS-550 using GE Discovery ST-16 or Discovery Elite PET/CT.The same CT acquisition conditions was used:tube voltage 120 kV,pitch 1.375,rotation speed 0.8 s,noise index ranged from 8 to 30,interval 2,automatic tube current low limit 30 mA,high limit ranged from 200 to 350 mA,interval 50 mA.The images were analyzed,and the noise,signal to noise ratio (SNR) and figure of merit (FOM) of main organs in the abdomen were calculated.The relationship between image quality and ED was analyzed.Two-sample t test was used for data analysis.Results The noise of each organ decreased significantly along with the increase of ED until the ED of ST-16 increased to 15 mSv or Elite increased to 12 mSv,then the image noise decreased gently.SNR of each organ image increased along with the increase of ED.The FOM of liver decreased along with the increase of ED,while the FOM of other organs did not change significantly with ED.All image indicators of Elite PET/CT were better than ST-16 PET/CT at the same ED (5-20 mSv),though there was no significant difference (t:0.133-4.701,all P＞0.05).When ED was 5 mSy,the noise of liver with ST-16 was 12.0％ (28.9 vs 25.8)higher than that with Elite,and the SNR and FOM of liver with Elite was 13.9％ (4.1 vs 3.6) and 66.7％ (0.50 vs 0.30) higher than that with ST-16,respectively.Conclusion When the ED caused by the 2 PET/CT systems was between 5-20 mSy,the image quality is improved along with the ED increasing in a certain range.
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Objective To study the radiation level in the surrounding of patients undergoing 99Tcm-MDP SPECT bone imaging and associated influencing factors and provide experimental data for the radiation safety of personnel around the patients.Methods A total of 367 patients undergoing whole-body bone imaging in Cancer Hospital,Chinese Academy of Medical Sciences were investigated to measure the ambient dose equivalent rate around the patients at different time and different distances from the patients,analyze the variations of ambient dose equivalent rate with time and distances,estimate the dose level at different distances around the patients,and evaluate the radiation dose to personnel around the patients.Results The ambient dose equivalent rate around the patient decreased exponentially with time;the effective half-life of 99Tcm in patients' body increased with time.The ambient dose equivalent rate varied by power function with increasing distance within 4 meters from the patient with the mean power value of -1.45.The radiation levels were 238.3 μSv at 0.5 m,99.7 μSv at 1 m,and 61.8 μSv at 1.5 m from the patient undergoing 99Tcm injection to its vanishing in patients' body.At different time points,the radiation doses at 0.5 m off the patient for 10 min were:9.9,3.0,1.9 μSv at 0,3 and 6 h,respectively.Conclusions The ambient dose equivalent rate around the patients undergoing 99Tcm-MDP SPECT bone imaging decrease rapidly with increasing time and distance.The patients can cause a certain degree of exposures to the surrounding personnel,but the exposure level is far lower than the relevant national standards.It is suggested that the patients should not receive other types of diagnosis and treatments spending lot of time and in close contact with medical staff while bone imaging being conducted on the same day.
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Objective:To study the radiation dose rate around patients underwent renal dynamic imaging of SPECT with 99Tcm-DTPA, so as to provide the basis for ensuring the radiation safety of the surrounding environment and the general public.Methods: 109 patients who underwent renal dynamic imaging were enrolled in this study, and the radiation dose rates of different time and different distance after 99Tcm-DTPA was injected patients were measured. And then, the changes of dose rate following time and distance were analyzed. Results: At the 0.5h, 1h, 2h, 3h, 6h, and 7h after radiopharmaceuticals were injected patients underwent renal dynamic imaging, the radiation dose rates were 0.76-8.86 μSv/h, 0.68-7.27 μSv/h, 0.57-4.52 μSv/h, 0.56-3.90 μSv/h, 0.23-2.07 μSv/h and 0.21-1.05 μSv/h, respectively, between 0.5 m and 4 m away from patients. At 24h after radiopharmaceuticals were injected, all of radiation dose rates at different distances around patients were same with background values.Conclusion: The radiation dose rates around patients underwent renal dynamic imaging will rapidly decrease with the increasing of time and distance. At 24h after radiopharmaceuticals were injected, all of radiation dose rates at different distances away from patients were same with background values.
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PET-CT, SPECT, and SPECT-CT examinations could lead to inevitable medical exposure for patients, and the radiation dose of this examinations and whether it was harmful to patients have attracted attention from the public and professionals. At the same time, there was still a controversy about whether the biological effect of low dose radiation was useful to human body. The research investigates and reviews the radiation dose of PET-CT, SPECT, and SPECT-CT scans and their biological effects. Under achieved to the demands of clinical conditions, operators should try to reduce the radiation dose of PET-CT, SPECT, SPECT-CT scans for patients. Although PET-CT, SPECT, SPECT-CT scans deliver inevitable radiation, the dose of single examination will not lead to deterministic effect, and even the view of the random effect of linear no-threshold from these scans also have been questioned.
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Whole-body PET-CT scanning has been used in the diagnosis and treatment of tumor to providing functional and morphological imaging. As the most widely used semi-quantitative analysis index, the cutoff value of SUV would affect the final diagnosis, therapeutic regimen and prognosis estimation. Therefore, the article reviews the influential factors of SUV, its correction methods, its cutoff values of differential various tumors and the progress of SUV. Although there is no acknowledged cutoff value of SUV in tumor diagnosis, SUV is still an important semi-quantitative index, and its rational and prudent use would increase both of the sensitivity and specificity in tumor diagnosis.
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Whole-body PET/CT scanning is accompanied by substantial radiation dose in clinic. A large proportion of the radiation dose for examination obtained from whole-boby PET/CT is from CT scan. So how to control radiation dose without impairing CT image quality determined by the clinic is particularly important. Anthropomorphic phantom is the best choice for the study of radiation dose and image quality in PET/CT. The article reviews the meaning of anthropomorphic phantom and the study about PET/CT image quality and radiation dose with the phantom, Then analyzes the relationship between image quality of CT in PET/CT and radiation dose in the practical application.
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To assure the quality and safety of nuclear medicine imaging,quality control for the imaging equipment is essential.Quality control consists of a series of special tests for assurance and adjustment of equipment accuracy according to specific standards.The development and status of quality control and the standards for nuclear medicine imaging equipment are investigated and reviewed in this study.The results show that the quality control and feasibility of the standards are both in need of improvement in China.
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Normalizing GFR with variables is important for non-cancer patients,especially for kidney donors.The most frequently evaluated variables are body surface area (BSA),extracellular fluid volume (ECV) and lean body mass (LBM).It is difficult to accurately quantify BSA and the power of BSA normalization decreases in children and obesity population.The ECV normalization is suitable for healthy children,but its clinical value decreases in patients with damaged renal function.The LBM can be accurately measured and has a larger serviceable range in the normalization.Although the influence factors of LBM should be extensively evaluated,the available data indicate that LBM is more suitable in the normalization of GFR than BSA and ECV.
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BACKGROUND: The effects of low-level laser biostimulation have been proved by various experimental studies and clinical application, which are manifested as tissue repairing, analgesia, antiinflammation, etc.OBJECTIVE: To observe the effects of He-Ne laser and low-level CO2 laser irradiation on fracture healing.DESIGN: A randomized controlled animal experiment. SETTING: Research Room of Laser Medicine, Chengde Medical College.MATERIALS: Forty-eight healthy male New Zealand rabbits, weighing 2.0-2.5 kg, were used.METHODS: The experiments were carried out in the Research Room of Laser Medicine, Chengde Medical College from 1998 to 2003. ①The 48 rabbits were induced into models of experimental fracture of the left radius, and then they were divided into three groups with 16 rabbits in each group: control group, He-Ne laser irradiation group and CO2 laser irradiation group. The fracture areas of the animals in the He-Ne and CO2 laser irradiation groups were respectively irradiated with 28 mW/cm2 He-Ne laser and 150 mW/cm2 CO2 laser for 10 minutes, once a day. ② The animals were killed on the 15th and 35th days after taking roentgenogram respectively. At 15 days, the collagen and calcium contents in callus were detected. At 35 days, the biomechanic anti-torsion strength was examined.MAIN OUTCOME MEASURES: ①Results of roentgenogram in each group; ② Collagen and calcium contents in callus; ③ Results of biomechanic anti-torsion strength.RESULTS: Totally 45 rabbits were involved in the analysis of results. ① On the 15th and day after fracture, the roentgenogram, collagen and calcium contents in callus in the He-Ne and CO2 laser irradiation groups were better than those in the control group, and the collagen and calcium contents in callus were higher in the CO2 laser irradiation group than in the He-Ne laser irradiation group [(341.9±30.1) vs (302.1±28.7) mg/g; (197.1±19.7)vs (156.5±17.6) mg/g, P＜ 0.05]. ②On the 35th days after fracture, the biomechanic anti-torsion functions in the He-Ne and CO2 laser irradiation groups were superior to that in the control group, and there were no significant difference between the two laser irradiation groups. ③ The results of roentgenogram in the He-Ne and CO2 laser irradiation groups were better than that in the control group both on the 15th and 35th days after fracture, and there was no significant difference between the two irradiation groups.CONCLUSION: Both CO2 laser and He-Ne laser irradiations can accelerate the process of fracture healing, and the curative effect of CO2 laser is better than that of He-Ne laser on the 15th day after fracture, but there is no significant difference clinically between the CO2 laser and the He-Ne laser irradiations on the 35th day after fracture.
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0.05).However, the frequency of the allele of g(-1359)t polymorphisms was higher in patients than that in the controls(P