The National Cyclotron and PET Centre at Chulabhorn Hospital offers nuclear medicine diagnostic services using state-of-the-art digital PET/CT and PET/MRI machines as well as other related devices. Additionally, the center plays a vital role by having a cyclotron to produce radiopharmaceuticals, which are used both in-house and in other hospitals throughout the country. Despite the center's strict adherence to international standards regarding the use of radioactive substances in patients, there remains a potential risk of radiation exposure for operators, workers, and the public due to radioactive contamination and emissions from unsealed sources. Hence, it is imperative to assess and continuously monitor radiation levels in the work area to ensure the utmost level of safety for personnel. Methods: This study used optically stimulated luminescence dosimeters to measure radiation levels in 17 areas, consisting of 9 controlled and 8 supervised areas. Over a 3-mo period, the average monthly radiation dose was recorded for each location. Results: The PET/CT room registered the highest radiation dose within the controlled area, with a monthly average of 1.81 ± 0.29 mSv, equivalent to an annual dose of 21.72 mSv. This higher dose can be attributed to the significant number of patients served in this room. In supervised areas, the nursing counter located between the examination room and the patient waiting area exhibited the highest radiation exposure. The average monthly dose measured at this location was 0.085 ± 0.019 mSv, resulting in an annual dose of 1.015 mSv. Conclusion: The evaluation of radiation dose in controlled and supervised areas indicated that the overall radiation level remains within the prescribed limits. However, the slight excess that was observed at the nursing counter indicates the need for improvement to ensure compliance with the as-low-as-reasonably-achievable principle. Continuous monitoring of radiation levels should be conducted annually to maintain safety standards and minimize the risk that workers and the general public will be exposed to radioactivity.
Background: Optimizing image quality and radiation dose is crucial in general radiography, adhering to the As Low As Reasonably Achievable (ALARA) principle. Objective: This study aimed to evaluate the impact of applying the 10 kVp and 15% rules on image quality and patient dose in extremity X-ray imaging using both computed radiography (CR) and digital radiography (DR) systems. Materials and methods: X-ray imaging of hand, elbow, knee, and foot phantoms was performed using three different exposure techniques on both CR and DR systems. These techniques included the standard technique (ST) based on the established guidelines of the imaging systems, increased 10 kVp with a 50% mAs reduction from ST (10 kVp rule), and increased 15% kVp with a 50% mAs reduction from ST (15% rule). The entrance skin dose (ESD) was measured using nanoDot™placed on the phantom’s surface. The physical image qualities in contrast-to-noise ratio (CNR) and figure of merit (FOM) were utilized to assess the balance between image quality and radiation doses. Results: The ESD was reduced by an average of -16% and -25% when applying the 10 kVp and 15% rules for all extremity imaging. This reduction decreased image CNR by -18% and -12%, respectively. There was no significant difference in CNR between the 15% and 10 kVp rule techniques for all extremity examinations in both CR and DR systems (p>0.05). Meanwhile, the exposure and deviation indexes remained within the established guidelines for CR and DR systems. However, the FOM values tended to be greater with the 15% rule technique than other techniques. Conclusion: The ESD reduction was observed when applying the 10 kVp and 15% rules for all extremity imaging, both in CR and DR systems, with a slight degradation in image quality. The 15% rule represents the best option for optimization of image quality and patient dose based on the FOM results.
The intercomparison of Personal Dose Equivalent (Hp(10)) among the Individual monitoring laboratory (IMS) from 27 laboratories in 9 economies in Southeast and East Asia was carried out in 2023. In this program, a whole-body dose assessment from Cs-137 and N-80 x-ray with two different incident beam angles (0º and 30º) was performed using Optically Stimulated Luminescence (OSL) dosimeter. The trumpet curve recommended by IAEA GSG-7 was used to be a criterion of acceptance value. In the first round, there was 95% of all data within the acceptable value and 13 data from two laboratories was unacceptable. However, the intercomparison in the second round was performed for the two laboratories with the same protocol. The result shows a good agreement between the estimated dose and delivery dose for all laboratories after the improvement of the assessment and calibration method of the two laboratories. All data from 27 laboratories are now within the acceptable value, indicating the performance of the measurement. This contributes to the harmonization of radiological quantities and units for IMS laboratories in the Southeast and East Asia region. Also, each laboratory fulfils the performance and standard requirements for the individual monitoring service laboratory.
Background: Computed tomography examinations have produced high radiation doses to patients, especially the CT brain. This study aimed to optimize the radiation dose and image quality in adult CT brain protocol. Materials and Methods: Images were acquired by Catphan 700 phantom. Radiation doses were recorded as CTDIvol and dose length product (DLP). CT brain protocols were optimized by varying parameters such as kVp, mAs, signal-to-noise ratio (SNR) level, and Clearview iterative reconstruction (IR). Image quality were also evaluataion by The AutoQA Plus software. Results: CT Number accuracy and linearity had a robust positive correlation with the linear attenuation coefficient (µ) and showed more inaccurate CT numbers when using 80 kVp. MTF showed a higher value in 100 and 120 kVp protocols, while high contrast spatial resolution showed a higher value in 80 and 100 kVp protocols. Low contrast detectability and CNR tended to increase when using high mAs, SNR and Clearview IR protocol. Noise decreased when using a high radiation dose and a high percentage of Clearview IR. CTDIvol and DLP were increased with increasing kVp, mAs, and SNR levels, while the increasing percentage of Clearview did not affect the radiation dose. Conclusion: Optimized protocols, including radiation dose and image quality, should be evaluated to preserve diagnostic capability. The recommended parameter settings include kVp set between 100-120 kVp, mAs ranging from 200-300 mAs, SNR level within the range of 0.7-1.0, and an iterative reconstruction value of 30% Clearview to 60% or higher.
Computed tomography examinations have caused high radiation doses for patients, especially for CT scans of the brain. This study aimed to optimize the radiation dose and image quality in adult brain CT protocols. Images were acquired using a Catphan 700 phantom. Radiation doses were recorded as CTDIvol and dose length product (DLP). CT brain protocols were optimized by varying parameters such as kVp, mAs, signal-to-noise ratio (SNR) level, and Clearview iterative reconstruction (IR). The image quality was also evaluated using AutoQA Plus v.1.8.7.0 software. CT number accuracy and linearity had a robust positive correlation with the linear attenuation coefficient (µ) and showed more inaccurate CT numbers when using 80 kVp. The modulation transfer function (MTF) showed a higher value in 100 and 120 kVp protocols (p < 0.001), while high-contrast spatial resolution showed a higher value in 80 and 100 kVp protocols (p < 0.001). Low-contrast detectability and the contrast-to-noise ratio (CNR) tended to increase when using high mAs, SNR, and the Clearview IR protocol. Noise decreased when using a high radiation dose and a high percentage of Clearview IR. CTDIvol and DLP were increased with increasing kVp, mAs, and SNR levels, while the increasing percentage of Clearview did not affect the radiation dose. Optimized protocols, including radiation dose and image quality, should be evaluated to preserve diagnostic capability. The recommended parameter settings include kVp set between 100 and 120 kVp, mAs ranging from 200 to 300 mAs, SNR level within the range of 0.7–1.0, and an iterative reconstruction value of 30% Clearview to 60% or higher.
Based on a new occupational dose limit recommended by ICRP (2011), the annual dose limit for the lens of the eye for workers should be reduced from 150 mSv/y to 20 mSv/y averaged over 5 consecutive years in which no single year exceeding 50 mSv. This new dose limit directly affects radiologists and cardiologists whose work involves high radiation exposure over 20 mSv/y. Eye lens dosimetry (Hp(3)) has become increasingly important and should be evaluated directly based on dosimeters that are worn closely to the eye. Normally, Hp(3) dose algorithm was carried out by the combination of Hp(0.07) and Hp(10) values while dosimeters were calibrated on slab PMMA phantom. Recently, there were three reports from European Union that have shown the conversion coefficients from air kerma to Hp(3). These conversion coefficients carried out by ORAMED, PTB and CEA Saclay projects were performed by using a new cylindrical head phantom. In this study, various delivered doses were calculated using those three conversion coefficients while nanoDot, small OSL dosimeters, were used for Hp(3) measurement. These calibrations were performed with a standard X-ray generator at Secondary Standard Dosimetry Laboratory (SSDL). Delivered doses (Hp(3)) using those three conversion coefficients were compared with Hp(3) from nanoDot measurements. The results showed that percentage differences between delivered doses evaluated from the conversion coefficient of each project and Hp(3) doses evaluated from the nanoDots were found to be not exceeding -11.48 %, -8.85 % and -8.85 % for ORAMED, PTB and CEA Saclay project, respectively.
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Objective: This study aimed to develop a new shielding device, a bed skirt, and compare the radiation protection effectiveness between lead and antimony-tungsten (Sb-W) bed skirts in fluoroscopic-guided urological surgery. Material and Methods: The simulated surgery of ureteroscopy (URS) and percutaneous nephrolithotomy (PCNL), using the phantoms, was set. The lead and Sb-W skirts were mounted around the operating table. The fluoroscopy time was 120 seconds, and the experiment was repeated 10 times. The radiation dose to the body parts of the patient, surgeon, and anesthesiologist was measured with optically stimulated luminescent dosimeters and compared in the following conditions: conventional operating table, Sb-W bed skirt, and lead bed skirt.Results: By installing a bed skirt, the radiation dose was decreased, with lead being dominant in all areas. The lead bed skirt reduced the radiation dose by 20% to the patient, 66% to the surgeon, and 91% to the anesthesiologist. The absorbed radiation dose of the lead bed skirt was lower than the Sb-W bed skirt in URS settings (23.3±1.8 µGy vs 32.0±1.9 µGy, p-value<0.001) as well as PCNL settings (257.2±15.6 µGy vs 296.5±24.6 µGy, p-value<0.001). There was no statistically significant difference between the conventional operating table and the Sb-W bed skirt in both URS settings (p-value=0.066) and PCNL settings (p-value=0.153).Conclusion: The lead bed skirt significantly reduced the radiation exposure and provided superior radiation protection compared with the Sb-W bed skirt. This shielding technique is practical to minimize the harmful effects of radiation from fluoroscopy.
การประเมนปรมาณรงทผวทผปวยไดรบในการถายภาพทางรงสดจทลในโรงพยาบาลศรนครนทร
ตองจต มหาจนทวงศ1, ธวชชย ปราบศตร1,2,*, วรนนท ครสตยกล1,2, สมศกด วงษาศานนท1 วราภรณ สดใจ3
1ภาควชารงสวทยา คณะแพทยศาสตร มหาวทยาลยขอนแกน
2กลมวจยรงสวทยาหลอดเลอดและรงสรวมรกษาระบบประสาท คณะแพทยศาสตร มหาวทยาลยขอนแกน
3สถาบนเทคโนโลยนวเคลยรแหงชาต
บทคดยอ
หลกการและวตถประสงค: การถายรงสดจทลถอเปนการวนจฉยโรคโดยทวไป ทเพมจำนวนมากขนอยางมนยสำคญในการตรวจดวยรงสเอกซ ทำใหผปวยทเขารบการตรวจทางรงสมความเสยงจากการไดรบรงสเพมมากขน การศกษานมวตถประสงคเพอประเมนปรมาณรงสทผวผปวยไดรบ (entrance skin dose,ESD) ในการถายภาพรงสดจทลในทาทวไป ของโรงพยาบาลศรนครนทร คณะแพทยศาสตร มหาวทยาลยขอนแกน และเปรยบเทยบคาปรมาณรงสทผวไดรบกบคาระดบปรมาณรงสอางอง (diagnostic reference level,DRL) ของหนวยงานระดบและระดบนานาชาต รวมทงมการศกษาถงปจจยทมผลตอปรมาณรงสทผวผปวย
วธการศกษา: เปนการศกษายอนหลง ตงแตเดอนมกราคม ถง พฤษภาคม พ.ศ. 2562 จากระบบการจดเกบรปภาพทางการแพทย โดยเกบขอมลพารามเตอรสำหรบการถายภาพรงสดจทลจากผปวยจำนวน 1,010 ราย ทหนวยรงสวนจฉย ภาควชารงสวทยา คณะแพทยศาสตร มหาวทยาลยขอนแกน จากการถายภาพรงสทรวงอก กระดกสนหลงสวนคอ สวนอกและสวนเอว กะโหลกศรษะ ในดานตรง (anteroposterior; AP) และดานขาง (Lateral view; LAT) การถายภาพรงสชองทองและกระดกเชงกรานดาน AP คำนวณหาปรมาณรงส ESD โดยใชสตรคำนวณเฉพาะ วเคราะหขอมลโดยใชสถตพรรณนา และหาความสมพนธระหวางปรมาณรงส ESD และคาพารามเตอรสำหรบการถายภาพรงสดจทล
ผลการศกษา: ผลการศกษาพบวา Chest LAT ใชคาความตางศกยไฟฟา (kVp) สำหรบการถายภาพสงทสด สวน Lumbar spine LAT ใชคากระแสหลอดคณกบเวลา (mAs) สงทสด คามธยฐานปรมาณรงส ESD ของการถายภาพรงสดจทลทกสวนมคาตำกวาคาระดบปรมาณรงสอางองมาตรฐานนานาชาต (IAEA) ในขณะท ESD ของการถาย chest PA, abdomen AP, pelvis AP, lumbar spine LAT และ skull AP/PA มคาตำกวา DRL ในระดบชาต ยกเวน Lumbar spine AP และ skull LAT ทมคา ESD สงกวา มากไปกวานนยงมการเปรยบเทยบ ESD ของการศกษานกบคา DRL ประเทศญปนและสหราชอาณาจกร โดยการเปรยบเทยบคา ESD กบ DRL ของประเทศญปนไดผลการเปรยบเทยบเหมอนกบคา DRLในระดบชาต ในขณะทเปรยบเทยบกบคา DRL ของสหราชอาณาจกรพบวาคา ESD ของการถายภาพรงสสวน abdomen AP, pelvis AP and lumbar spine LAT นอยกวาคา DRL ของสหราชอาณาจกร สวนการถายภาพรงสสวน chest PA, lumbar spine AP, skull AP/PA และ skull LAT มคา ESD มากกวา นอกจากนพบวาคา mAs มความสมพนธในระดบสงในทศทางเดยวกนกบคา ESD ในขณะทนำหนก อายและ kVp มความสมพนธในระดบตำกบคา ESD
สรป: การศกษาครงนทำใหหนวยงานไดทราบคา ESD อางองในผปวยทรบการถายภาพรงสดจทลและไดเปรยบเทยบคา ESD กบคา DRL ของหนวยงานระดบชาต นานาชาต ประเทศญปน และสหราชอาณาจกร โดยเมอคา ESD สงกวาคา DRL ของหนวยงานระดบชาตและนานาชาต นกรงสการแพทยและทมงานควรสบคนและหาสาเหตของปญหาวาเกดจากอะไร ควรตรวจสอบโปรแกรมการประกนคณภาพและประสทธภาพของเครองเพอใหแนใจถงประสทธภาพของเครองเอกซเรยและปรมาณรงสทออกมา หลงจากนนควรมการทบทวนโปรโตคอลและเทคนคการใหปรมาณรงสแกผปวย ในขนตอนตอไปคอการ optimization เพอปรบลดปรมาณรงสในผปวยลงและจำกดความเสยงทจะเกดขนกบผปวย
คำสำคญ: การถายภาพรงสดจทล; ปรมาณรงสทผวทผปวยไดรบ; ปรมาณรงสอางอง
Abstract
Background and objectives: Digital radiography is a common diagnostic practice and it has been a significant increase in the number of x-ray examinations. Patients were frequently exposed to radiation may consider increasing the risk of exposure to radiation. The purpose of this study was set up to evaluate the entrance skin dose (ESD) in common digital radiography in Srinagarind hospital, faculty of medicine, Khon Kaen university and compared to ESD with national and international diagnostic reference level (DRL) including study of parameters which effect the ESD.
Material and method: The retrospective study was conducted from January to May 2019 by using picture achieving communication systems (PACS). The digital radiographic parameters from total 1,010 patients from 12 examinations including chest, cervical spine, thoracic spine and lumbar spine, skull in anteroposterior/posteroanterior (AP/PA) view and lateral view, abdomen and pelvis in AP view were recorded. The ESD was calculated using the specific formula. All data were analyzed using descriptive analysis and the correlation of digital radiographic parameters and ESD was also analyzed.
Result: The result showed that the highest kVp for DR was observed in chest LAT while the highest mAs was observed in lumbar spine LAT. The median ESD of all digital radiography examination was lower than the international IAEA DRL value while the median of ESD of chest PA, abdomen AP, pelvis AP, lumbar spine LAT and skull AP/PA was lower than Thai national DRL except for the median ESD of lumbar spine AP and skull LAT were higher than national DRL. Moreover, the median ESD was compared with the Japanese and United Kingdom (UK) DRL. The comparison between ESD and Japanese DRL was showed the result like the Thai national DRL. While the comparison between ESD and UK DRL, the median ESD of abdomen AP, pelvis AP and lumbar spine LAT were lower than UK DRL except for the median ESD of chest PA, lumbar spine AP, skull AP/PA and skull LAT were higher than UK DRL. In addition, mAs showed a high positive correlation with ESD while weight, age and kVp were showed a low correlation with ESD.
Conclusion: This study provided the median ESD in Srinagarind hospital and already compared with national DRL, international IAEA DRL, Japanese DRL and UK DRL. When the median ESD was higher than national and international DRL, technologist and team member could investigate and determine the cause of problem. The quality assurance program and efficiency of X-ray machine firstly check to ensure the good performance of the machine and radiation output and then the protocol and exposure technique were also revised. Further step, dose optimization is required to reduce the patient dose and limit the stochastic effect risk.
Keyword : Digital Radiography; Entrance Skin Dose; Diagnostic reference level
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