[Multicenter Survey on Phantom Entrance Surface Air Kerma of Angiography and IVR in Japan].

PURPOSE: In DRLs 2020, the entrance surface air kerma (Ka,e) was set to 17 mGy/min as the reference dose rate in fluoroscopy. But, Ka,e in fluoroscopy for different regions and Ka,e in exposure was not set. A multicenter survey was conducted to evaluate Ka,e by each area. METHODS: Ka,e for each area was analyzed for 79 facilities attending this survey (274 machines and 461 protocols). When the protocols were changed by the difference in disease, angiography, or IVR, the difference rate of Ka,e was evaluated. Ka,e before and after modifying the incident air kerma at the patient entrance reference point (Ka,r) and air kerma area product (PKA) difference rate were calculated when protocols were changed, considering the DRLs 2020. RESULTS: There were dose differences in Ka,e by each area. Compared to DRLs 2020, 36 protocols from 13 facilities modified their protocols, all of which reduced Ka,e. CONCLUSION: Although reducing Ka,e does not necessarily reduce Ka,r, and PKA, comparison of Ka,e by each area is expected to optimize medical exposure protection, including evaluation of quality control.

[Development of Dose Calculation Application for Computed Tomography Dose Management When Facility Protocols Differ from Diagnostic Reference Level (DRL)].

PURPOSE: In this study, we aimed to develop an application that computes dose values resembling diagnostic reference level (DRL) conditions when disparity prevents direct dose comparisons between the national diagnostic reference levels in Japan 2020 (Japan DRLs_2020) and facility-specific computed tomography (CT) protocols. METHODS: We developed an application using the R programming language and RStudio software that computes dose values and median values based on Japan DRLs_2020 imaging conditions following extraction of necessary information for dose calculations from the Radiation Dose Structured Report (RDSR) and Digital Imaging and Communications in Medicine (DICOM) tags. To ensure a user-friendly experience, we used the Shiny package to develop a graphical user interface that enables the application to operate seamlessly in web browsers. RESULTS: The developed application successfully facilitated the calculation of dose and median values that aligned with the Japan DRLs_2020 for protocols whose imaging range and acquisition timing differed from those of the Japan DRLs_2020. CONCLUSION: By calculating dose values that align with DRL conditions, our application contributes to the implementation and optimization of dose management in CT for facilities that use diverse imaging protocols.

An Analysis of Computed Tomography Diagnostic Reference Levels in India Compared to Other Countries.

Computed Tomography (CT) is vital for diagnosing and monitoring medical conditions. However, increased usage raises concerns about patient radiation exposure. Diagnostic Reference Levels (DRLs) aim to minimize radiation doses in CT imaging. This study examines CT DRLs in India compared to other countries to identify optimization opportunities. A literature review was conducted to gather data from published studies, guidelines, and regulatory authorities. Findings show significant international variations in CT DRLs, with differences up to 50%. In India, DRLs also vary significantly across states. For head CT exams, Indian DRLs are generally 20-30% lower than international standards (27-47 mGy vs. 60 mGy). Conversely, for abdominal CT scans, Indian DRLs are 10-15% higher (12-16 mGy vs. 13 mGy). Factors influencing DRL variations include equipment differences, imaging protocols, patient demographics, and regulatory conditions. Dose-optimization techniques like automatic exposure control and iterative reconstruction can reduce radiation exposure by 25-60% while maintaining image quality. Comparative data highlight best practices, such as the United Kingdom's 30% reduction in CT doses from 1984 to 1995 via DRL implementation. This study suggests that adopting similar practices in India could reduce radiation doses by 20-40% for common CT procedures, promoting responsible CT usage and minimizing patient exposure.

Assessment of radiation exposure among pediatric patients referred for CT imaging at three government hospitals in Addis Ababa, Ethiopia.

Background: Due to the high sensitivity of their growing tissues to ionizing radiation, pediatric patients are at a greater risk of cancer development. Objective: This study aimed to evaluate the level of radiation exposure experienced by pediatric patients undergoing a common CT examination at the three government hospitals in Addis Ababa, Ethiopia. Materials and methods: Structured formats were designed for data collection at three government hospitals, and then information about pediatric patients' demography, CT protocols, and CT systems was retrieved and recorded from March 2018 up to July 2018. CT dose indicators: CTDIvol (mGy) and DLP (mGy.cm) values for abdomen, chest, and head CT scans were recorded based on pediatric patients' age ⩽1, (1-5], (5-10], and (10-15] years old. The data were analyzed through SPSS version 25 software. Finally, the third quartile values of CTDIvol and DLP were determined and compared with other international DRLs. Results: The third quartile values of radiation dose descriptors for abdomen, chest, and head CT scans, respectively, in terms of CTDIvol (mGy): 58, 10, 17, 51; 23, 23, 34, 51; 62, 41, 50, 51; and in terms of DLP (mGy.cm), 377, 314, 624, 664; 523, 571, 406, 739; 927, 806, 929, and 1197 corresponded to pediatric patients of age ⩽1, (1-5], (5-10], and (10-15] years old, respectively. Conclusion: There were significant differences in the radiation dosage of some CT examinations between the same age groups, indicating a need for dose optimization. Therefore, this study recommends the need for enhancing radiation safety, ensuring appropriate imaging practices, and prioritizing the well-being of pediatric patients who visit CT examinations in Addis Ababa, Ethiopia.

Data analysis of average glandular dose in mammography toward revision of the diagnostic reference level of Japan.

Diagnostic reference level (DRL) for mammography for 2015 and 2020 has been published by J-RIME. More new dose studies are needed to revise the next DRL. In preparation for the next revision of the DRL for mammography, this study investigated data from the Japan Central Organization on Quality Assurance of Breast Cancer Screening on the mean average glandular dose (AGD) for institutional image accreditation in 2019-2023 and the relationship between the average at eligible institutions to date and the type of breast X-ray system. The 95th percentile values of the AGD distributions for the Computed Radiography (CR) and Flat Panel Detector (FPD) systems were 2.5 mGy and 2.0 mGy, respectively. Moreover, it is assumed that AGD is decreasing due to the spread of FPD systems, and it is expected that the further spread of FPD systems and systems with W/Rh target/filter will reduce AGD in future.

National Diagnostic Reference Levels for Standard Descending Thoracic Endovascular Aortic Repair and Optimisation Strategies.

OBJECTIVE: The International Commission on Radiological Protection has highlighted the large number of medical specialties that use fluoroscopy outside diagnostic imaging departments without radiation protection programmes for patients and staff. Vascular surgery is one of these specialties. Thoracic endovascular aortic repair (TEVAR) is a complicated procedure requiring radiation protection guidance and optimisation. The recent EU Basic Safety Standards Directive requires the use and periodic updating of diagnostic reference levels (DRLs) for interventional procedures. The aim of this study was to determine doses for patients undergoing TEVAR with mobile Xray systems and hybrid rooms (fixed Xray systems) to obtain national DRLs and to suggest optimisation actions. METHODS: This was a retrospective cross sectional study. The Spanish Chapter of Endovascular Surgery conducted a national survey in 11 autonomous communities representing around 77.6% of the Spanish population (47.33 million inhabitants). A total of 266 TEVAR procedures from 17 Spanish centres were analysed, of which 53.0% were performed in hybrid operating rooms. National DRLs were obtained and defined as the third quartile of the median values from the different participating centres. RESULTS: The proposed national DRLs are: for kerma area product (KAP), 113.81 Gy·cm2 for mobile Xray systems and 282.59 Gy·cm2 for hybrid rooms; and for cumulative air kerma (CAK) at the patient entry reference point, 228.38 mGy for mobile systems and 910.64 mGy for hybrid rooms. CONCLUSION: Based on the requirement to know radiation doses for standard endovascular procedures, this study of TEVARs demonstrated that there is an increased factor of 2.48 in DRLs for KAP when the procedure is performed in a hybrid room compared with mobile C-arm systems, and an increased factor of 3.98 in DRLs for CAK when the procedure is performed with hybrid equipment. These results will help to optimise strategies to reduce radiation doses during TEVAR procedures.

Advanced Computational Methods for Radiation Dose Optimization in CT.

BACKGROUND: In planning radiotherapy treatments, computed tomography (CT) has become a crucial tool. CT scans involve exposure to ionizing radiation, which can increase the risk of cancer and other adverse health effects in patients. Ionizing radiation doses for medical exposure must be kept "As Low As Reasonably Achievable". Very few articles on guidelines for radiotherapy-computed tomography scans are available. This paper reviews the current literature on radiation dose optimization based on the effective dose and diagnostic reference level (DRL) for head, neck, and pelvic CT procedures used in radiation therapy planning. This paper explores the strategies used to optimize radiation doses, and high-quality images for diagnosis and treatment planning. METHODS: A cross-sectional study was conducted on 300 patients with head, neck, and pelvic region cancer in our institution. The DRL, effective dose, volumetric CT dose index (CTDIvol), and dose-length product (DLP) for the present and optimized protocol were calculated. DRLs were proposed for the DLP using the 75th percentile of the distribution. The DLP is a measure of the radiation dose received by a patient during a CT scan and is calculated by multiplying the CT dose index (CTDI) by the scan length. To calculate a DRL from a DLP, a large dataset of DLP values obtained from a specific imaging procedure must be collected and can be used to determine the median or 75th-percentile DLP value for each imaging procedure. RESULTS: Significant variations were found in the DLP, CTDIvol, and effective dose when we compared both the standard protocol and the optimized protocol. Also, the optimized protocol was compared with other diagnostic and radiotherapy CT scan studies conducted by other centers. As a result, we found that our institution's DRL was significantly low. The optimized dose protocol showed a reduction in the CTDIvol (70% and 63%), DLP (60% and 61%), and effective dose (67% and 62%) for both head, neck, and pelvic scans. CONCLUSIONS: Optimized protocol DRLs were proposed for comparison purposes.

Managing radiation safety and protection in gastroenterology in Japan: insights from the REX-GI study.

Fluoroscopy-guided gastrointestinal procedures, including gastrointestinal stenting, balloon-assisted endoscopy (BAE), endoscopic retrograde cholangiopancreatography (ERCP), and endoscopic ultrasound (EUS), are essential for diagnosis and treatment in gastroenterology. Such procedures involve radiation exposure that necessitates strict safety measures to protect patients, doctors, and medical staff. The April 2020 update to Japan's Ionizing Radiation Injury Prevention Regulations for occupational exposure reduced the lens exposure dose limit to approximately one-seventh of its previous level. This change highlights the need for improved safety protocols. Without adaptation, the sustainability of fluoroscopy-based endoscopic techniques could be at risk due to the potential to exceed these new limits. This review examines the current state of medical radiation exposure in the field of gastroenterology in Japan and discusses the findings of the REX-GI study.

An audit of patient radiation doses during interventional cardiology procedures in Uttarakhand, India, and establishment of local diagnostic reference levels.

The objective of this study was to investigate patient radiation doses by a dose audit of three common interventional cardiology (IC) procedures: coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA) and CA-PTCA procedures performed in IC centres in the Uttarakhand state of India, for the establishment of local diagnostic reference levels (DRLs) and the estimation of average effective dose (Eav) for these procedures. For each procedure, the values of kerma-area product (PKA), reference air kerma (Ka,r), fluoroscopy time (FT) and the number of cine images were recorded from 1233 CA, 458 PTCA and 736 CA-PTCA procedures performed over a 12-month period at 13 IC centres of the state. From the recorded dose data, 0.6%, 1.53% and 7.9% patients were identified to have exceeded the PKA trigger level of 500 Gy cm2 for possible skin injury for CA, PTCA and CA-PTCA procedures, respectively. The 3rd quartile of the distribution of the recorded PKA values for each type of procedure was calculated to estimate local DRL values. The estimated values of DRLs and Eav were 37, 153 and 224 Gy cm2, and 6.72, 23.97 and 34.79 mSv for CA, PTCA and CA-PTCA procedures, respectively. For about 77% of the surveyed centres, the recorded patient doses were in agreement with the international standards. The local DRLs proposed in this study may be used to achieve patient dose optimization during IC procedures and the obtained patient dose data may also be archived into national dose database for the establishment of national DRLs.

Age-based diagnostic reference levels and achievable doses for paediatric CT: a survey in Shanghai, China.

Computed tomography (CT) is extensively utilised in medical diagnostics due to its notable radiographic superiority. However, the cancer risk associated with CT examinations, particularly in children, is of significant concern. The assessment of cancer risk relies on the radiation dose to examinees. Diagnostic reference levels (DRLs) and achievable doses (ADs) were used to assess the level of radiation dose in CT examinations widely. Although the national DRLs of paediatric CT have been explored in China, few local DRLs at the city level have been assessed. To set up the local DRLs and ADs of paediatric CT, we investigated the radiation dose level for paediatric CT in Shanghai. In this survey, a total of 3061 paediatric CT examinations underwent in Shanghai in 2022 were selected by stratified sampling, and the dose levels in terms of volume CT dose index (CTDIvol) and the dose-length product (DLP) were analysed by 4 age groups. The DRLs and ADs were set at the 75th and 50th percentile of the distribution and compared with the previous studies at home and abroad. The survey results revealed that, for head scan, the DRLs of CTDIvolwere from 25 to 46 mGy, and the levels of DLP were from 340 to 663 mGy·cm. For chest, the DRLs of CTDIvolwere from 2.2 to 8.3 mGy, and the levels of DLP were from 42 to 223 mGy·cm. For abdomen, the DRLs of CTDIvolwere from 6.3 to 16 mGy, and the levels of DLP were from 181 to 557 mGy·cm. The ADs were about 60% lower than their corresponding DRLs. The levels of radiation doses in children-based hospitals were higher than those in other medical institutions (P< 0.001). In conclusion, there was still potential for reducing radiation dose of paediatric CT, emphasising the urgent need for optimising paediatric CT dose in Shanghai.

Establishment of National Diagnostic Reference Levels for Administered Activity in Diagnostic Nuclear Medicine in Thailand.

The diagnostic reference level (DRL) is a patient-exposure optimization tool used to evaluate radiation doses in medical imaging and provide guidance for protection from them. In Thailand, nuclear medicine DRLs have not been established yet. Therefore, this study surveyed dose levels in routine nuclear medicine procedures to provide national DRLs (NDRLs). Methods: NDRLs in Thailand were established by investigating the administered activity of radiopharmaceuticals in nuclear medicine examination studies. The NDRLs were determined on the basis of the 75th percentile (third quartile) of administered activity distribution as recommended by the International Commission on Radiological Protection. As part of a nationwide survey, datasets for the period between June 1, 2018, and August 31, 2019, were collected from 21 Thailand hospitals with nuclear medicine equipment. All hospitals were asked to report the nuclear medicine imaging devices in use, the standard protocol parameters for selected examinations, the injected activities, and the ages and weights of patients. All data were calculated to determine Thailand NDRLs, which were compared with international NDRLs. Results: The data reported by the 21 hospitals consisted of 4,641 examinations with SPECT or SPECT/CT for general nuclear medicine and 409 examinations with PET. The most widely performed examinations for SPECT were bone, thyroid, oncology, and cardiovascular imaging. The NDRLs for SPECT or SPECT/CT agreed well with published NDRLs for Europe, the United States, Japan, Korea, Kuwait, and Australia. In contrast, the NDRLs for 18F-FDG PET in oncology studies were higher than for Japan, Korea, Kuwait, and Australia but lower than for the United States, the United Kingdom, and the European Union. Conclusion: This study presents NDRL results for adults in Thailand as a way to optimize radiation protection in nuclear medicine imaging. Moreover, the reported injected activity levels were comparable to those of other countries.

Impact of equipment technology on reference levels in fluoroscopy-guided gastrointestinal procedures.

OBJECTIVES: To evaluate the effect of equipment technology on reference point air kerma (Ka,r), air kerma-area product (PKA), and fluoroscopic time for fluoroscopically-guided gastrointestinal endoscopic procedures and establish benchmark levels. METHODS: This retrospective study included the consecutive patients who underwent fluoroscopically-guided gastrointestinal endoscopic procedures from May 2016 to August 2023 at a tertiary care hospital in the U.S. Fluoroscopic systems included (a) Omega CS-50 e-View, (b) GE Precision 500D, and (c) Siemens Cios Alpha. Radiation dose was analyzed for four procedure types of endoscopic retrograde biliary, pancreas, biliary and pancreas combined, and other guidance. Median and 75th percentile values were computed using software package R (version 4.0.5, R Foundation). RESULTS: This large study analyzed 9,459 gastrointestinal endoscopic procedures. Among four procedure types, median Ka,r was 108.8-433.2 mGy (a), 70-272 mGy (b), and 22-55.1 mGy (c). Median PKA was 20.9-49.5 Gy∙cm2 (a), 13.4-39.7 Gy∙cm2 (b), and 8.91-20.9 Gy∙cm2 (c). Median fluoroscopic time was 2.8-8.1 min (a), 3.6-9.2 min (b), and 2.9-9.4 min (c). Their median value ratio (a:b:c) was 8.5:4.8:1 (Ka,r), 2.7:2.1:1 (PKA), and 1.0:1.1:1 (fluoroscopic time). Median value and 75th percentile are presented for Ka,r, PKA, and fluoroscopic time for each procedure type, which can function as benchmark for comparison for dose optimization studies. CONCLUSION: This study shows manifold variation in doses (Ka,r and PKA) among three fluoroscopic equipment types and provides local reference levels (50th and 75th percentiles) for four gastrointestinal endoscopic procedure types. Besides procedure type, imaging technology should be considered for establishing diagnostic reference level. SUMMARY: With manifold (2 to 12 times) variation in doses observed in this study among 3 machines, we recommend development of technology-based diagnostic reference levels for gastrointestinal endoscopic procedures.

Establishment of local diagnostic reference levels for CT colonography at a tertiary hospital.

Background: Diagnostic reference levels (DRLs) are an important metric in identifying abnormally high radiation doses in diagnostic examinations. National DRLs for CT colonography do not currently exist in South Africa, but there are efforts to collect data for a national DRL project. Objectives: This study investigated radiation doses for CT colonography in adult patients at a large tertiary hospital in South Africa with the aim of setting local DRLs. Method: Patient data from two CT scanners (Philips Ingenuity and Siemens Somatom go.Top) in the period March 2020 - March 2023 were obtained from the hospital's picture archiving and communication system (PACS) (n = 115). Analysis involved determining the median computed tomography dose index-volume (CTDIvol) and dose-length product (DLP) values. The findings were compared with DRLs established internationally. Results: Ingenuity median CTDIvol was 20 mGy and DLP was 2169 mGy*cm; Somatom median CTDIvol was 6 mGy and DLP was 557 mGy*cm. Ingenuity exceeded the United Kingdom's (UK) recommended DRLs by 82% and 214%, respectively. Somatom median CTDIvol and DLP were 45% and 19% lower than UK NDRLs. Conclusion: Somatom's tin filter and other dose reduction features provided significant dose reduction. These data were used to set DRLs for CT colonography at the hospital; CTDIvol: 6 mGy and DLP: 557 mGy*cm. Contribution: In addition to informing radiation protection practices at the level of the institution, the established local DRLs contribute towards implementing regional and national DRLs.

An Approach to Establishing Diagnostic Reference Levels in Interventional Pediatric Cardiology from Different Regions of Brazil.

Diagnostic reference levels (DRLs) are a pivotal strategy to be implemented since pediatric interventional cardiology procedures are increasing. This work aimed to propose an initial set of Brazilian DRLs for pediatric interventional diagnostic and therapeutic (D&T) procedures. A retrospective study was carried out in four Brazilian states, distributed across the three regions of the country. Data were collected from pediatric patients undergoing cardiac interventional procedures (CIPs), including their age and anthropometric characteristics, and at least four parameters (number of images, exposure time, air kerma-area product-PKA, and cumulative air kerma). Data from 279 patients undergoing CIPs were gathered (147 diagnostic and 132 therapeutic procedures). There were no significant differences in exposure time and the number of images between the D&T procedures. A wide range of PKA was observed when the therapeutic procedures were compared to diagnostics for all age groups. There were significant differences between the D&T procedures, whether grouping data by patient weight or age. In terms of cumulative air kerma, it was noted that no value exceeded the level to trigger a monitoring process for patients. This study shows that it is possible to adopt them as the first proposal to establish national DRLs considering pediatric patient groups.

Diagnostic reference levels in spinal CT: Jordanian assessments and global benchmarks.

BACKGROUND: To reduce radiation dose and subsequent risks, several legislative documents in different countries describe the need for Diagnostic Reference Levels (DRLs). Spinal radiography is a common and high-dose examination. Therefore, the aim of this work was to establish the DRL for Computed Tomography (CT) examinations of the spine in healthcare institutions across Jordan. METHODS: Data was retrieved from the picture archiving and communications system (PACS), which included the CT Dose Index (CTDI (vol) ) and Dose Length Product (DLP). The median radiation dose values of the dosimetric indices were calculated for each site. DRL values were defined as the 75th percentile distribution of the median CTDI (vol)  and DLP values. RESULTS: Data was collected from 659 CT examinations (316 cervical spine and 343 lumbar-sacral spine). Of the participants, 68% were males, and the patients' mean weight was 69.7 kg (minimum = 60; maximum = 80, SD = 8.9). The 75th percentile for the DLP of cervical and LS-spine CT scans in Jordan were 565.2 and 967.7 mGy.cm, respectively. CONCLUSIONS: This research demonstrates a wide range of variability in CTDI (vol)  and DLP values for spinal CT examinations; these variations were associated with the acquisition protocol and highlight the need to optimize radiation dose in spinal CT examinations.

National UK Survey of Radiation Doses During Endovascular Aortic Interventions.

PURPOSE: Endovascular aortic repair (EAR) interventions, endovascular abdominal aortic repair (EVAR) and thoracic endovascular aortic repair (TEVAR), are associated with significant radiation exposures. We aimed to investigate the radiation doses from real-world practice and propose diagnostic reference level (DRL) for the UK. MATERIALS AND METHODS: Radiation data and essential demographics were retrospectively collected from 24 vascular and interventional radiology centres in the UK for all patients undergoing EAR-standard EVAR or complex, branched/fenestrated (BEVAR/FEVAR), and TEVAR-between 2018 and 2021. The data set was further categorised according to X-ray unit type, either fixed or mobile. The proposed national DRL is the 75th percentile of the collective medians for procedure KAP (kerma area product), cumulative air kerma (CAK), fluoroscopy KAP and CAK. RESULTS: Data from 3712 endovascular aortic procedures were collected, including 2062 cases were standard EVAR, 906 cases of BEVAR/FEVAR and 509 cases of TEVAR. The majority of endovascular procedures (3477/3712) were performed on fixed X-ray units. The proposed DRL for KAP was 162 Gy cm2, 175 Gy cm2 and 266 Gy cm2 for standard EVAR, TEVAR and BEVAR/FEVAR, respectively. CONCLUSION: The development of DRLs is pertinent to EAR procedures as the first step to optimise the radiation risks to patients and staff while maintaining the highest patient care and paving the way for steps to reduce radiation exposures.

Establishment of a local diagnostic reference level for computed tomography chest and abdomen in two different cities in Saudi Arabia.

BACKGROUND AND AIM: Spiral computed tomography (CT) scans, which are considered a high-contrast resolution, quick and cross-sectional imaging technique, have grown in popularity as a result of technological advancements. However, these advancements have brought with them the potential for significantly increased radiation doses to the patient. Consequently, many organizations recommended optimization and establishing diagnostic reference levels. The aim of the current study was to assess CT radiation dose and propose a local diagnostic reference level (LDRL) for the adult trunk [chest and abdomen] using CT dose parameters such as CT dose index volume (CTDIvol) and dose length product (DLP) as well as to compare the practices for aforementioned examinations between two hospitals in Taif and Abha cities in Saudi Arabia. MATERIALS AND METHODS: Data from 428 patients (216 for abdomen and 212 for chest) who were examined in two hospitals in Taif and Abha City in Saudi Arabia from December 2022 to March 2023, are used in this study. The data for hospitals in Taif and Abha are presented as 'T' and 'A' throughout this manuscript. The parameters of exposure and slice thickness were recorded in a specially designed data sheet together with the gender, age and patients morphometric. Microsoft Excel version 2010 was used to analyze results and plot the figures. The LDRL was achieved from the third quartile of CTDIvol and DLP for each hospital and examination. RESULTS: The average DLP (mGy-cm) and CTDIvol (mGy) for the chest and abdomen were 243 mGy cm, 5.8 mGy and 549 mGy cm, 8.6 mGy respectively. The average effective dose (ED) for chest and abdomen were 5.10 and 21.10 mSv, respectively. The proposed LDRL for the chest and abdomen were 6.9 mGy (CTDIvol), 375 mGy-cm (DLP), 7.8 mGy (CTDIvol), and 747 (DLP) mGy-cm, respectively. CONCLUSION: Hospital 'A' irradiated patients with a higher dose for the abdomen exam than Hospital 'T', but both hospitals agreed on the amount of radiation dose received by patients for chest imaging. The proposed LDRL for two examinations was less than the DRL obtained from the literature.

Fundamental study on diagnostic reference level quantities for endoscopic retrograde cholangiopancreatography using a C-arm fluoroscopy system.

The diagnostic reference level (DRL) is an effective tool for optimising protection in medical exposures to patients. However regarding air kerma at the patient entrance reference point (Ka,r), one of the DRL quantities for endoscopic retrograde cholangiopancreatography (ERCP), manufacturers use a variety of the International Electrotechnical Commission and their own specific definitions of the reference point. The research question for this study was whetherKa,ris appropriate as a DRL quantity for ERCP. The purpose of this study was to evaluate the difference betweenKa,rand air kerma incident on the patient's skin surface (Ka,e) at the different height of the patient couch for a C-arm system. Fluoroscopy and radiography were performed using a C-arm system (Ultimax-i, Canon Medical Systems, Japan) and a over-couch tube system (CUREVISTA Open, Fujifilm Healthcare, Japan).Ka,ewas measured by an ion chamber placed on the entrance surface of the phantom. Kerma-area product (PKA) andKa,rwere measured by a built-inPKAmeter and displayed on the fluoroscopy system.Ka,edecreased whileKa,rincreased as the patient couch moved away from the focal spot. The uncertainty of theKa,e/Ka,rratio due to the different height of the patient couch was estimated to be 75%-94%.Ka,rmay not accurately representKa,e.PKAwas a robust DRL quantity that was independent of the patient couch height. We cautioned against optimising patient doses in ERCP with DRLs set in terms ofKa,rwithout considering the patient couch height of the C-arm system. Therefore, we recommend thatKa,ris an inappropriate DRL quantity in ERCP using the C-arm system.

Evaluation of In-room Volumetric Imaging Doses for Image-guided Radiotherapy: A Multi-institutional Study.

Aims: We investigated imaging dose and noise under clinical scan conditions at multiple institutions using a simple and unified method, and demonstrated the need for diagnostic reference levels in image-guided radiotherapy (IGRT). Materials and Methods: Nine cone-beam and helical computed tomography (CT) scanners (Varian, Elekta, Accuray Inc., and BrainLAB) from seven institutions were investigated in this study. The weighted cone-beam dose index (CBDIw) was calculated for head and pelvic protocols using a 100 mm pencil chamber under the conditions used in actual clinical practice at each institution. Cone-beam CT image noise was evaluated using polymethylmethacrylate head and body phantoms with diameters of 16 and 32 cm, respectively. Results: For head and pelvic protocols, CBDIw values ranged from 0.94-6.59 and 1.47-20.9 mGy, respectively. Similarly, standard deviation (SD) values ranged from 9.3-34.0 and 26.9-97.4 HU, respectively. The SD values tended to increase with decreasing imaging dose (r = -0.33 and -0.61 for the head and pelvic protocols, respectively). Conclusions: Among the nine machines, the imaging dose for high imaging dose institutions was approximately 20 mGy to the pelvic phantom, and there was a 14-fold difference in dose compared with the other institutions. These results suggest the need to establish DRLs for IGRT to guide clinical decision-making.

Establishment of local diagnostic reference levels for computed tomography with cloud-based automated dose-tracking software in Turkey.

PURPOSE: The purpose of this study is to establish local diagnostic reference levels (LDRLs) for computed tomography (CT) procedures using cloud-based automated dose-tracking software. METHODS: The study includes the dose data obtained from a total of 104,272 examinations performed on adult patients (>18 years) using 8 CT scanners over 12 months. The protocols included in our study were as follows: head CT without contrast, cervical spine CT without contrast, neck CT with contrast, chest CT without contrast, abdomen-pelvis CT without contrast, lumbar spine CT without contrast, high-resolution computed tomography (HRCT) of the chest, and coronary CT angiography (CTA). Dose data were collected using cloud-based automatic dose-tracking software. The 75th percentiles of the distributions of the median volume CT dose index (CTDIvol) and dose length product (DLP) values were used to determine the LDRLs for each protocol. The LDRLs were compared with national DRLs (NDRLs) and DRLs set in other countries. Inter-CT scanner variability, which is a measure of how well clinical practices are standardized, was determined for each protocol. Median values for each protocol were compared with the LDRLs for dose optimization in each CT scanner. RESULTS: The LDRLs (for DLP and CTDIvol, respectively) were 839 mGy.cm and 41.2 mGy for head CT without contrast, 530.6 mGy.cm and 19.8 mGy for cervical spine CT without contrast, 431.9 mGy.cm and 15.5 mGy for neck CT with contrast, 364.8 mGy.cm and 9.3 mGy for chest CT without contrast, 588.9 mGy. cm and 11.2 mGy for abdomen-pelvis CT without contrast, 713 mGy.cm and 24.3 mGy for lumbar spine CT without contrast, 326 mGy.cm and 9.5 mGy for HRCT, and 642.3 mGy.cm and 33.4 mGy for coronary CTA. The LDRLs were comparable to or lower than NDRLs and DRLs set in other countries for most protocols. The comparisons revealed the need for immediate initiation of an optimization process for CT protocols with higher dose distributions. Furthermore, protocols with high inter-CT scanner variability revealed the need for standardization. CONCLUSION: There is a need to update the NDRLs for CT protocols in Turkey. Until new NDRLs are established, local institutions in Turkey can initiate the optimization process by comparing their dose distributions to the LDRLs established in our study. Automated dose-tracking software can play an important role in establishing DRLs by facilitating the collection and analysis of large datasets.