美國《保健物理》(Health Physics)雜志英文摘要(2023 年 126 卷第 1 期)

Health Phys. Abstracts，Volume 126，Number 1

Radiation Protection Considerations for Cancer Patients with End-stage Renal Disease Receiving 131 I Treatment

Matthew Louis1 ， Emmanuel M. Mate-Kole1 ， Landon Aziz2 ， Shaheen A. Dewji1

（1. Nuclear and Radiological Engineering and Medical Physics Programs， Georgia Institute of Technology， 770 State Street NW，Atlanta， GA 30332-0405;2. Houston Methodist Hospital， 6565 Fannin St， Ste. SM539， Houston， TX 77030）

Abstract：Differentiated thyroid cancer （ DTC） is commonly treated first with a partial or complete thyroidectomy， followed byradioiodine （RAI） ablative therapy to eliminate remaining cancer cells. In such treatments， physical decay and urinary excretionare the primary means of 131 I. As such， patients with impaired urinary ability clearance， such as patients with end-stage renaldisease （ESRD） whose urinary ability is impaired by dysfunction， can retain abnormally high activities of RAI， posing a concern toboth the patient and those with whom the patient interacts. Additionally， ESRD patients are commonly administered dialysistherapy， wherein their blood is externally cycled through a dialyzer （hemodialysis） or filtered by instilling a dialysate fluid into theperitoneum （peritoneal dialysis） to filter uremic toxins from their blood that accumulate due to kidney dysfunction. These factorsmake determining release and dosing for ESRD patients receiving RAI therapy dependent on a plurality of variables. An evaluationof the current patient release guidelines， as given in US Nuclear Regulatory Commission （US NRC） Regulatory Guide 8. 39 Rev. 1for ESRD patients receiving RAI， has yet to be addressed. In this study， a biokinetic model for 131 I in ESRD patients receivingdialysis has been developed， improving on traditional two-compartment models， reflective of kinetics from multi-compartmentmodels with updated transfer coefficients modified to reflect the different physiological functions of compartments. This updatedbiokinetic model was integrated with Monte Carlo radiation transport calculations using stylized computational hermaphroditicphantoms to calculate dose rate coefficients in exposure scenarios and compared with those of the point source models of NRC RegGuide 8. 39 Rev. 1 （and the proposed verbiage in Rev. 2）. Results demonstrated that the baseline models of Rev. 1 and Rev. 2overestimated the effective dose rate to an exposed individual for the majority of time post-administration， where both modelsoverestimated the total dose to the maximally exposed individual. However， the application of several patient-specific modifyingfactors to the Rev. 2 model resulted in an overestimation by only a factor of 1. 25， and in general， the results produced with thepatient-specific modifications provide improved convergence with the dose rate coefficients computed in this study for ESRDpatients.

Key words： 131 I; nuclear medicine; phantom; mathematical; regulations

Health Phys. 126（1）：1-17; 2024

Natural Radioactivity of Granitic Rocks and Their Health Risk around Ingesana Mountains， Sudan

Nooreldin Fadol1，2 ， Ali Abdelrazig3 ， Hajo Idriss4 ， Yazeed Alashban5 ， Nasser Shubayr3

（1. Department Physics， Faculty of Education， Blue Nile University， El Damazin， Sudan;2. Physics Department， Mai Nafhi College of Science， Asmara， Eritera;3. Diagnostic Radiography Technology Department， College of Applied Medical Sciences， Jazan University， Jazan， Saudi Arabia;4. Department Physics， College of Science， Imam Mohammad Ibn Saud Islamic University， （IMSIU） Riyadh， Saudi Arabia;5. Radiological Sciences Department， College of Applied Medical Sciences， King Saud University， P. O. Box 145111， Riyadh4545， Saudi Arabia）

Abstract：This work was carried out mainly to analyze radioactive elements 40 K， 232 Th， and 226 Ra and non-radioactive elements insome granitic rocks and study their health risk for humans and non-humans. Radioisotope activity was evaluated using a high-puritygermanium （HPGe） detector， and various radiological hazard indices were calculated. We also measured some non-radioactiveelements using X-ray fluorescence analysis and performed Pearson correlation analysis to examine the relationships between theradionuclides and the non-radioactive elements. Furthermore， we used the ERICA software to estimate the total dose rate perorganism for some non-human biota. The means of 226 Ra， 232 Th， and 40 K are （25. 13 ± 5. 22）Bq kg- 1 ， （29. 01 ± 6. 95）Bq kg-1 ，and （323. 07 ± 97. 83）Bq kg-1 ， respectively. Hence， 226 Ra， 232 Th， and 40 K radioactivities were lower than the worldwide averagelimits. The 226 Ra， 232 Th， and 40 K levels were under the global average values. The hazardous radiometric variables were computed，and the findings observed that the mean absorbed dosage was （ 23. 48 ± 7. 36） nGy h- 1 ， the yearly effective dose rate was（29. 82 ± 10. 46）μSv y-1 ， and the radium equivalent activity was （88. 88 ± 18. 64） Bq kg-1 . The average dose and yearlyeffective dose rates were lower than the global average absorbed dose rate of 60 nGy h-1 and the ICRP standard of 1. 0 mSv y-1 . Theresults of Ra-equivalent activity were lower than the recommended maximum criterion for building materials limit of Ra-equivalentactivity （370 Bq kg- 1 ） proposed by UNSCEAR. Tests of Pearson correlation coefficients indicate a substantial positive relationshipbetween 226 Ra and 232 Th and a modest correlation between 226 Ra and 40 K. Meanwhile， no association between 226 Ra and 40 K andnon-radioactive components has been identified. Thorium-232 exhibits a moderately favorable connection with Ti， Fe， and Ni. Theestimated total dose rate per organism for the studied non-human is less than the ambient dose rate. However， the total dose rate forsmall burrowing mammals and reptiles exceeds the background exposure rate. In accordance with the findings， granite rocks may besafe to use as construction materials and pose no threat to human health.

Key words： dose; environmental; environmental assessment; environmental impact; radioactivity; environmental

Health Phys. 126（1）：18-24; 2024

Exploratory Data Analysis of the Groundwater Contaminants at the Former Panna Maria Uranium Recovery Facility

Mark C. Harvey1 ， Nancy L. Glenn Griesinger2

（1. Department of Physics， Texas Southern University， Houston， TX 77004;2. Department of Mathematical Sciences， Texas Southern University， Houston， TX 77004）

Abstract：The former Panna Maria mill was a uranium recovery facility that operated from 1979 to December 1992. Sulfuric acidleach was used to process several tons of ore daily. Therefore， the groundwater was sampled at the site to monitor the concentrationof background chemical pollutants. The purpose of this study was to perform exploratory data analysis to evaluate whether thearsenic， nickel， selenium， sulfate， and uranium concentrations were in accord with state-regulated groundwater drinking standardsat the site. To accomplish this， a substitution method was used to replace concentration values that were below measurable ranges ofwell monitoring units. Additionally， random forest regression was employed to account for missing not-at-random values in thedataset. Groundwater samples collected in wells before the facility began operations were used to determine an upper bound onbackground pollutants consistent with US Environmental Protection Agency Standards. The upper tolerance limit comprising 90% ofthe groundwater sample at a confidence coefficient of 95% was used to establish alternate concentration limits for each chemicalbased on well data from the National Uranium Resource Hydrogeochemical and Stream Sediment Reconnaissance program. Resultsobtained in this analysis establish a baseline on the chemical concentrations in the background groundwater at the former PannaMaria mill.

Key words： analysis; statistical; contamination; environmental; uranium milling; water; ground

Health Phys. 126（1）：25-36; 2024

Is It Appropriate to Completely Eliminate Contact Shielding during CT Examination？ A Discourse Based on Experimental Findings

Jiwei Chen1 ， Jianchun Tu2 ， Shengyan Huang3 ， Zhenhua Zhu1 ， Yu Tu4，5

（1. Department of Medical Engineering， Kunshan Hospital of Traditional Chinese Medicine， Kunshan， Jiangsu 215300， P. R.China;2. Department of Radiology， Kunshan Hospital of Traditional Chinese Medicine， Kunshan， Jiangsu 215300， P. R. China;3. Department of Nursing， Kunshan Hospital of Traditional Chinese Medicine， Kunshan， Jiangsu 215300， P. R. China;4. State Key Laboratory of Radiation Medicine and Protection， School of Radiation Medicine and Protection， Soochow University，Suzhou， Jiangsu 215123， P. R. China;5. Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions， Suzhou， Jiangsu 215123， P.R. China）

Abstract：Through the integration of experimental data and literature， this study examines whether complete elimination of contactshielding during CT examination is warranted， with a particular focus on potential impacts to children's thyroid and pregnantwomen， as well as limitations associated with contact shielding. Methods： The thermoluminescent dosimeter （TLD） tablets wereinserted into the phantom's five organs and tissues. Select fixed exposure， automatic exposure control （AEC）， and use contactshielding combined into four experimental modes， with scanning of the phantom s four parts. Obtain the absorbed dosemeasurements within or outside the FOV. Statistical analysis was conducted using SPSS software. Results： （ 1） The AECsignificantly reduces dose within and outside the FOV， with a dose reduction of 40% - 60%. （2） The application of contactshielding outside the FOV significantly reduced the dose adjoin the FOV. （3） Both the use of AEC mode and contact shielding can effectively minimize the dose， with a reduction of 50%-80%. （4） The shielding within the FOV may introduce image artifacts orinterfere with AEC， the implementation of contact shielding outside FOV provides little reduction in radiation exposure risk throughprevious literature. （5） Contact shielding exhibits certain drawbacks in all aspects. Conclusion： The utilization of AEC mode inclinical CT should be widely adopted to minimize patient radiation exposure. In general， contact shielding both inside and outsidethe FOV should be avoided during exposure. However for children under 12 years old with thyroid gland examination， contactshielding could maximally reduce external radiation and may be appropriate. Pregnant women require careful evaluation whenconsidering the use of contact shielding. Contact shielding should not be entirely abandoned.

Key words： computed tomography; dose; absorbed; dosimetry; thermoluminescent; shielding

Health Phys. 126（1）：46-55; 2024

Underestimation of Occupational Radiation Exposure During Endovascular Abdominal Aortic Aneurysm Repair

Hsien-Wen Chiang1 ， Tzu-Chao Chuang1 ， Tou-Rong Chen2，3

（1. Department of Electrical Engineering， National Sun Yat-Sen University， Kaohsiung， Taiwan;2. Department of Medical Imaging and Radiological Sciences， Chung Shan Medical University， Taichung， Taiwan;3. Department of Medical Imaging， Chung Shan Medical University Hospital， Taichung， Taiwan）

Abstract：During interventional procedures of endovascular abdominal aortic aneurysm repair （ EVAR）， the dosimeter wasconventionally placed on chest facing toward the surgical table， instead of the main source of scatter radiation. Purpose of this studyis to evaluate the underestimation of occupational radiation exposure. Phantom experiments were performed in a hybrid operatingroom equipped with an interventional angiography system. Electric personal dosimeters were placed at the level of eyes， chest，abdomen， and gonad of three positions， representing the principal operator （ PO）， assistant operator （ AO）， and sterile nurse（SN）. Personal dose equivalent was measured with two different orientations of radiation detection， facing the table and facing thephantom， respectively. In addition to fluoroscopy， the dose produced by digital subtraction angiography was also measured toestimate the radiation exposure of routine EVAR. In this study， staff doses of 26 EVAR cases were also collected in our hospital tocorrelate the estimated dose. Our results show that the facing-phantom dose normalized by dose area product of patient issignificantly higher than the facing-table dose when the latter is regularly seen in clinical practice. This underestimation could beeven worse at a more distant position （ e. g. ， AO and SN） as the incident angle of scatter radiation is larger. Besides， theestimated dose is highly correlated with the on-site measured dose （R2 ～ 0. 8） at chest and gonad of the PO.

Key words： operational topics; exposure， occupational; fluoroscopy; X rays