Dose-length Product Research Articles

Size-Specific Dose Estimate for Chest of Adult Patients in 128- Slice Computed Tomography at Rajavithi Hospital

Aims: To determine the patient radiation dose using Size-Specific Dose Estimates (SSDEs) for chest CT in adult patients performed with 128-slice CT technology. Study Design: A descriptive cross-sectional study was conducted as a retrospective analysis. Place and Duration of Study: Department of Radiology, Rajavithi Hospital, between April 1 and September 30, 2021. Methods: We included 500 patients (209 males, 291 females). All patients underwent chest contrast enhancement with a venous phase protocol. The patient radiation dose in terms of SSDE was calculated based on AP+Lat dimensions, effective diameter, and water-equivalent diameter. SSDEs was measured from the middle slice of the scan range. The conversion factors following body size and composition were applied according to the AAPM Reports No. 204 and 220 recommendations. Additionally, the study assessed the effective dose and dose-length product (DLP). Key parameters, including DLP, CTDIvol, effective dose, and SSDEs at the 75th percentile, were evaluated to determine radiation dose levels. These values were then compared with established national and international diagnostic reference levels. Results: The study found that the mean DLP was 301.74 mGy·cm, CTDIvol was 8.38 mGy, effective dose was 4.22 mSv, SSDE (AP+Lat) was 11.80 mGy, SSDE (Effective Diameter) was 11.86 mGy, and SSDE (Dw) was 12.91 mGy. When compared with reference radiation dose values from Thailand and international standards, the DLP, CTDIvol, and effective dose values were found to be lower than both Thai and international reference values. In contrast, the SSDE (AP+Lat) was also lower than previously reported findings. Additionally, the study found no available comparative data for SSDE (Effective Diameter) and SSDE (Dw). Conclusion: The comparison of radiation dose values using SSDE across the three methods revealed highly consistent results. The SSDE values obtained from this study can serve as reference levels for the radiation doses received by patients undergoing CT scans at the Radiology Department of Rajavithi Hospital. These values are instrumental in assessing the appropriateness of radiation doses applied during CT imaging and can serve as benchmarks for future dose optimization efforts. Furthermore, this study highlights the significance of evaluating radiation doses in diagnostic imaging, providing valuable baseline data that enhances our understanding of the radiation risks associated with various types of examinations. Further research is warranted to investigate radiation exposure in computed tomography for other body regions.

AI-based automatic patient positioning in a digital-BGO PET/CT scanner: efficacy and impact

BackgroundA recently released digital solid-state positron emission tomography/x-ray CT (PET/CT) scanner with bismuth germanate (BGO) scintillators provides an artificial intelligence (AI) based system for automatic patient positioning. The efficacy of this digital-BGO system in patient placement at the isocenter and its impact on image quality and radiation exposure was evaluated.MethodThe digital-BGO PET/CT with AI-based auto-positioning was compared (χ2, Mann–Whitney tests) to a solid-state lutetium-yttrium oxyorthosilicate (digital-LYSO) PET/CT with manual patient positioning (n = 432 and 343 studies each, respectively), with results split into groups before and after the date of a recalibration of the digital-BGO auto-positioning camera. To measure the transverse displacement of the patient center from the scanner isocenter (off-centering), CT slices were retrospectively selected and automatically analyzed using in-house software. Noise was measured as the coefficient of variation within the liver of absolute Hounsfield units referenced to air. Radiation exposure was recorded as dose-length product (DLP). Off-centering measurements were validated by a phantom study.ResultsThe phantom validation study gave < 1.6 mm error in 15 off-centering measurements.Patient off-centering was biased 1.92 ± 1.79 cm (mean ± standard deviation) in the posterior direction which was significantly different from the 0.22 ± 1.21 cm bias in the left lateral direction (p < 0.0001, Wilcoxon). After recalibration, 27% (38/140) of the studies had off-centering results > 2.5cm for the digital-BGO, which was significantly better than the 49% (143/292, p < 0.001) before recalibration and better than for the digital-LYSO: 54% (119/222, p < 0.001) before and 55% (66/121, p < 0.001) after. On average, CT image quality was superior for non-obese patients who were most closely aligned with the isocenter: noise increased by 3.2 ± 0.1% for every 1 cm increase in off-centering. DLP increased by 144 ± 22 Gy cm for every 1 cm increase in anterior off-centering.ConclusionAI-based automatic patient positioning in a digital-BGO PET/CT scanner significantly reduces patient off-centering, thereby improving image quality and ensuring proper radiation exposure.

Determination of the conversion coefficients from the dose-length product to the effective dose for CT-examinations of the whole body including lower extremitie

Determination of the conversion coefficients from the dose-length product to the effective dose for CT-examinations of the whole body including lower extremitie

Radiation exposure in concurrent abdominoplevic and chest CT Scans: an analysis of overlap and clinical impact.

This study investigated the additional radiation exposure, influencing factors, and clinical significance of overlappingZ-axis coverage in abdominopelvic CT scans performed consecutively after same-day chest CT scans. Data from 761 patients were analyzed, with measuring the total and overlappingZ-axis coverage of the portal venous phase in abdominopelvic CT scans. The average overlapping portion was 33.8 ± 12.1 mm, accounting for approximately 7.0% of the total scan length, contributing a dose-length product of 33.4 mGy*cm and an effective radiation dose of 0.5 mSv. Male sex and the total scan length were identified as significant factors influencing overlap (p= 0.002 and < 0.001, respectively). Despite overlapping scans frequently imaging the lower lungs, only 8.4% of abdominopelvic CT reports specifically mentioned lower lung abnormalities, indicating limited clinical utility. These findings underscore the importance of optimizing CT protocols to minimize the total length of the body covered in abdominopelvic scans, thereby reducing unnecessary radiation exposure during concurrent chest and abdominopelvic CT scans.

Age-specific DRLs for pediatric brain CT: A review for exploring the practices in Saudi Arabia.

This review explores the establishment of diagnostic reference levels (DRLs) for pediatric brain computed tomography (CT) examinations in Saudi Arabia and compares them with nine other countries. An extensive search strategy was employed across various databases, resulting in the inclusion of 9 studies. The studies included patient-based and phantom-based investigations into DRLs, highlighting variations across age groups and countries. Findings suggest notable differences in CT dose index (CTDI mGy) and dose length product (DLP mGy.cm) values. There was a difference in the classification of age group between Saudi food and drug administration (SFDA) and literature. For the age groups 0-5 years and 6-15 years, the DRLs for the SFDA were as follows: CTDI (28 and 42mGy) and DLP (482 and 697mGycm). The discussion emphasizes the importance of age-specific DRLs to optimize radiation doses while ensuring patient safety and diagnostic efficacy. Recommendations include adopting globally accepted standards for dose optimization and continued research into factors influencing DRL variations. Limitations include varying age groupings among studies and limited access to some relevant literature. Overall, this study underscores the importance of standardizing DRLs for pediatric CT to improve patient care and safety.

Establishment of Local Diagnostic Reference Levels for Pediatric Neck CT at Nine University Hospitals in South Korea.

To establish local diagnostic reference levels (DRLs) for pediatric neck CT based on age, weight, and water-equivalent diameter (WED) across multiple university hospitals in South Korea. This retrospective study analyzed pediatric neck CT examinations from nine university hospitals, involving patients aged 0-18 years. Data were categorized by age, weight, and WED, and radiation dose metrics, including volume CT dose index (CTDIvol) and dose length product, were recorded. Data retrieval and analysis were conducted using a commercially available dose-management system (Radimetrics, Bayer Healthcare). Local DRLs were established following the International Commission on Radiological Protection guidelines, using the 75th percentile as the reference value. A total of 1159 CT examinations were analyzed, including 169 scans from Institution 1, 132 from Institution 2, 126 from Institution 3, 129 from Institution 4, 128 from Institution 5, 105 from Institution 6, 162 from Institution 7, 127 from Institution 8, and 81 from Institution 9. Radiation dose metrics increased with age, weight, and WED, showing significant variability both within and across institutions. For patients weighing less than 10 kg, the DRL for CTDIvol was 5.2 mGy. In the 10-19 kg group, the DRL was 5.8 mGy; in the 20-39 kg group, 7.6 mGy; in the 40-59 kg group, 11.0 mGy; and for patients weighing 60 kg or more, 16.2 mGy. DRLs for CTDIvol by age groups were as follows: 5.3 mGy for infants under 1 year, 5.7 mGy for children aged 1-4 years, 7.6 mGy for ages 5-9 years, 11.2 mGy for ages 10-14 years, and 15.6 mGy for patients 15 years or older. Local DRLs for pediatric neck CT were established based on age, weight, and WED across nine university hospitals in South Korea.

Establishment of Local Diagnostic Reference Levels for Head CT Imaging in the Madina Region, Saudi Arabia.

Background: Computed Tomography (CT) is crucial in medical diagnosis, particularly for head examinations. Diagnostic Reference Levels (DRLs) are pivotal in balancing diagnostic efficacy with radiation safety. International organizations such as the International Atomic Energy Agency (IAEA) and the International Commission on Radiological Protection (ICRP) provide guidelines for establishing DRLs, emphasizing their importance in optimizing radiation doses. Aim: This study aimed to establish and standardize DRLs for head CT imaging in institutional and regional settings, emphasizing the need for tailored reference levels specific to each region's practices and standards. Method: Data collection included patient demographics, imaging parameters, and radiation dose indices, namely volume-weighted CT dose index (CTDIvol) and dose-length product (DLP). Statistical analyses were conducted to determine the median and 3rd quartile values for establishing DRLs. The results were compared with national and international benchmarks to assess variations in radiation doses across regions. Results: Demographic profiles detailed gender distributions and ages across hospitals. Imaging parameters exhibited variability in tube voltage, milliampere-seconds (mAs), pitch, scan length, and field of view (FOV). For CTDIvol, the 3rd quartile value was 65.8 mGy (range: 24.8-85.9 mGy), and for DLP, it was 1230.95 mGy·cm (range: 382.3-1189.0 mGy·cm). These values were slightly higher than the national DRLs for Saudi Arabia in 2021 and other international benchmarks, underscoring the need for further optimization and alignment of protocols. Conclusion: Optimizing and standardizing DRLs for head CT imaging is crucial for effectively managing radiation doses while ensuring diagnostic accuracy. Comparison with national and international benchmarks highlighted the importance of tailoring reference levels to regional practices and standards, ensuring patient safety without compromising diagnostic efficacy.

Estimation of effective dose and risk of exposure-induced cancer death, and diagnostic reference level for CT scans in Tabriz, Iran.

This study aimed to estimate the effective dose and the risk of exposure-induced cancer death (REID), as well as to establish diagnostic reference levels (DRLs) for common CT examinations conducted in Tabriz, Iran. The investigation included adult patients undergoing abdomen-pelvis, brain, neck, sinus, and chest CT scans. Patient data, exposure parameters, and radiation dose metrics, such as volume CT dose index (CTDIvol) and dose length product (DLP), were collected and analyzed. The results showed significant variations in radiation dose across different centers for the CT scans. The average effective doses for the different CT scans were 5.65, 1.08, 1.40, 0.46, and 3.68mSv for abdomen-pelvis, brain, neck, sinus, and chest scans, respectively. The REID values ranged from 14 per million (for sinus scans) to 196 per million (for abdomen-pelvis scans). Additionally, the DRL values for CTDIvol were 11.03 (for abdomen-pelvis), 59.52 (for brain), 8.33 (for neck), 17.05 (for sinus), and 7.83mGy (for chest). Our results showed that most of the investigated CT scans had lower effective doses compared to the literature and the REIDs were estimated to be low. Minimizing radiation risk can be achieved by reducing CT exams and keeping doses as low as reasonably achievable. The local DRLs from this study were comparable to previous reports and can serve as benchmarks for setting national and international DRLs, helping healthcare facilities optimize radiation practices and improve patient safety in diagnostic imaging.

Optimizing Radiation Dose and Image Quality in Stroke CT Protocols: Proposed Diagnostic Reference Levels for Multiphase CT Angiography and Perfusion Imaging.

In suspected acute ischemic stroke, it is now reasonable to expand the conventional "stroke protocol" (non-contrast computed tomography (NCCT), arterial CT angiography (CTA), and optionally CT perfusion (CTP)) to early and late venous head scans yielding a multiphase CTA (MP-CTA) to increase diagnostic confidence. Diagnostic reference levels (DRLs) have been defined for neither MP-CTA nor CTP. We therefore present dosimetry data, while also considering image quality, for a large, unselected patient cohort. A retrospective single-center study of 1790 patients undergoing the extended stroke protocol with three scanners (2× dual-source, DSCT; 1× single-source, SSCT) between 07/21 and 12/23 was conducted. For each sequence, we analyzed the radiation dose (volumetric CT dose index (CTDIvol); dose length product; effective dose); objective image quality using manually placed regions of interest (contrast-to-noise ratio (CNR)); and subjective image quality (4-point scale: 1 = non-diagnostic, 4 = excellent). The DRL was defined as the 75% percentile of the CTDIvol distribution. The Kruskal-Wallis test was used initially to test for overall equality of median values in each data group. Single post-test comparisons were performed with Dunn's test, with an overall statistical significance level of 0.05. Dosimetry values were significantly higher for SSCT (p < 0.001, each). Local DRLs ranged between 37.3 and 49.1 mGy for NCCT, 3.6-5.5 mGy for arterial CTA, 1.2-2.5 mGy each for early/late venous CTA, and 141.1-220.5 mGy for CTP. Protocol adjustment (DSCT-1: CTP) yielded a 28.2% dose reduction. The highest/lowest CNRs (arterial/early venous CTA, respectively) were recorded for SSCT/DSCT-2 (p < 0.001). Subjective image quality was rated excellent except for slightly increased MP-CTA noise at DSCT-2 (median = 3). Our data imply that additive MP-CTA scans only yield a minor increase in radiation exposure, particularly when using DSCT. CTP should be limited to selected patients.

Optimization of Radiation Dose and Effective Dose for CT Pelvis Examinations in Main Hospitals in ALTaif Region

Introduction: CT scan is one of the medical imaging methods that irradiate patients with significant amounts of radiation. These amount of radiation doses must be well estimated if the imaging area is in part containing radiation-sensitive organs such as the pelvic area. Objectives: the objectives of the current study were to assess radiation dose during pelvis and Abdomen CT imaging and estimate the effective dose as well as to propose diagnostic reference level (DRL).Methodology: 200 adult patients irradiated in two major governmental hospital in Taif city, Saudi Arabia, patients’ demographic data from was collected such as weight, height, and age. Scanner specifications and scan parameters for each pelvis examination were recorded in special data collection sheet. Volume CT dose index (CTDIvol and dose length product (DLP) were utilized to estimate the radiation dose and effective dose. Microsoft Excel was used to analyse the data.Main Results: there was variation in scanning parameters among two hospitals under study and this result in variation in effective dose between two hospitals. The average DLP, CTDIvol and effective dose were 368.5, 390.7 mGy-cm,10.2,10.8 mGy and 7, 7.4 mSv for hospital one and two respectively. Conclusion: Based on the third quartile of DLP and CTDIw, the recommended DRL for both hospitals was 405 mGy-cm and 21.75 mGy, respectively. The findings revealed a reduced effective dose value when compared with previous studies.

Reduced dose helical CT scout imaging on next generation wide volume CT system decreases scan length and overall radiation exposure

PurposeTraditional CT acquisition planning is based on scout projection images from planar anterior-posterior and lateral projections where the radiographer estimates organ locations. Alternatively, a new scout method utilizing ultra-low dose helical CT (3D Landmark Scan) offers cross-sectional imaging to identify anatomic structures in conjunction with artificial intelligence based Anatomic Landmark Detection (ALD) for automatic CT acquisition planning. The purpose of this study is to quantify changes in scan length and radiation dose of CT examinations planned using 3D Landmark Scan and ALD and performed on next generation wide volume CT versus examinations planned using traditional scout methods. We additionally aim to quantify changes in radiation dose reduction of scans planned with 3D Landmark Scan and performed on next generation wide volume CT. MethodsSingle-center retrospective analysis of consecutive patients with prior CT scan of the same organ who underwent clinical CT using 3D Landmark Scan and automatic scan planning. Acquisition length and dose-length-product (DLP) were collected. Data was analyzed by paired t-tests. Results104 total CT examinations (48.1 % chest, 15.4 % abdomen, 36.5 % chest/abdomen/pelvis) on 61 individual consecutive patients at a single center were retrospectively analyzed. 79.8 % of scans using 3D Landmark Scan had reduction in acquisition length compared to the respective prior acquisition. Median acquisition length using 3D Landmark Scan was 26.7 mm shorter than that using traditional scout methods (p < 0.001) with a 23.3 % median total radiation dose reduction (245.6 (IQR 150.0–400.8) mGy cm vs 320.3 (IQR 184.1–547.9) mGy cm). CT dose index similarly was overall decreased for scans planned with 3D Landmark and ALD and performed on next generation CT versus traditional methods (4.85 (IQR 3.8–7) mGy vs. 6.70 (IQR 4.43–9.18) mGy, respectively, p < 0.001). ConclusionScout imaging using reduced dose 3D Landmark Scan images and Anatomic Landmark Detection reduces acquisition range in chest, abdomen, and chest/abdomen/pelvis CT scans. This technology, in combination with next generation wide volume CT reduces total radiation dose.

Ultra-low-dose chest computed tomography with model-based iterative reconstruction in the analysis of solid pulmonary nodules: A prospective study.

Incidental pulmonary nodules are an increasingly common finding on computed tomography (CT) scans of the thorax due to the exponential rise in CT examinations in everyday practice. The majority of incidental pulmonary nodules are benign and correctly identifying the small number of malignant nodules is challenging. Ultra-low-dose CT (ULDCT) has been shown to be effective in diagnosis of respiratory pathology in comparison with traditional standard dose techniques. Our hypothesis was that ULDCT chest combined with model-based iterative reconstruction (MBIR) is comparable to standard dose CT (SDCT) chest in the analysis of pulmonary nodules with significant reduction in radiation dose. To prospectively compare ULDCT chest combined with MBIR with SDCT chest in the analysis of solid pulmonary nodules. A prospective cohort study was conducted on adult patients (n = 30) attending a respiratory medicine outpatient clinic in a tertiary referral university hospital for surveillance of previously detected indeterminate pulmonary nodules on SDCT chest. This study involved the acquisition of a reference SDCT chest followed immediately by an ULDCT chest. Nodule identification, nodule characterisation, nodule measurement, objective and subjective image quality and radiation dose were compared between ULDCT with MBIR and SDCT chest. One hundred solid nodules were detected on ULDCT chest and 98 on SDCT chest. There was no significant difference in the characteristics of correctly identified nodules when comparing SDCT chest to ULDCT chest protocols. Signal-to-noise ratio was significantly increased in the ULDCT chest in all areas except in the paraspinal muscle at the maximum cardiac diameter level (P < 0.001). The mean subjective image quality score for overall diagnostic acceptability was 8.9/10. The mean dose length product, computed tomography volume dose index and effective dose for the ULDCT chest protocol were 5.592 mGy.cm, 0.16 mGy and 0.08 mSv respectively. These were significantly less than the SDCT chest protocol (P < 0.001) and represent a radiation dose reduction of 97.6%. ULDCT chest combined with MBIR is non-inferior to SDCT chest in the analysis of previously identified solid pulmonary nodules and facilitates a large reduction in radiation dose.

Estimation of Organ Dose, Effective Dose, and Cancer Risk in Abdominal CT Scan Patients

Computed tomography scan (CT scan) is a modality that is used to diagnose diseases inside the human body. In the scanning process, the patient will receive radiation from the CT scanner, so that it is necessary to calculate the amount of radiation dose. The purpose of this study was to determine the organ dose, effective dose, and cancer risk received by abdominal examination patients. Data taken from the results of abdominal examination patients at Radiology Installation of A.W. Sjahranie Regional Hospital Samarinda using 16-slice CT scan modality GE BRIVO type D3161T. The data collected included 150 patients, both female and male, with ages ranging from 15 to 79 years. Dosimetry parameters taken from CT scan results are the exposure factor (kV, mAs), scan length, computed tomography dosimetry indeks volume (CTDIvol), and dose length product (DLP) of the patient. CTDIvol and DLP of the patient are used to calculate the organ dose, effective dose, and cancer risk values of abdominal CT scan patients. Then the effective dose value received by the abdominal CT scan examination patient is compared with the Nuclear Energy Regulatory Agency of Indonesia (BAPETEN) standard based on the CTDIvol and DLP values of the patient, and also compared with the International Commission Radiological Protection (ICRP) standard. Based on the results of organ dose estimation calculations, the average value of the stomach is 0.82 mSv, the gonads are 0.54 mSv, and the bladder is 0.28 mSv. Meanwhile, the average value of effective dose received by abdominal examination patients is 5.28 mSv with an average cancer risk of 0.029 %. Based on the CTDIvol and DLP values of the patients, the 3rd quartile values of the patients were 8.25 mGy and 413.84 mGy.cm. This value is still below the value recommended by BAPETEN when viewed from the 2021 Diagnostic Reference Level (DRL) guidelines. The effective dose received by one patient exceeded the standard set by the ICRP. Meanwhile, the cancer risk received by patients is still in a low percentage.

Application of Multi-Model Adaptive Statistical Iterative Reconstruction-Veo in Ultra-Low Dose Chest CT Examination of Children in Plateau Area.

Objective To explore the application value of multi-model adaptive statistical iterative reconstruction-Veo (ASiR-V) in ultra-low dose chest CT examination of children in the plateau area. Methods The children who underwent chest CT examination in Xizang Autonomous Region People's Hospital were enrolled in this study and assigned into two groups according to the scanning conditions.Group A underwent scanning at a tube voltage of 100 kV and ASiR-V 50% reconstruction,and group B underwent scanning at a tube voltage of 80 kV and ASiR-V 0 (Group B1) and ASiR-V 50% (Group B2) reconstruction.The image quality of each group was evaluated objectively and subjectively.The radiation dose and image quality were compared between groups. Results Groups A and B showed the volume CT dose indexes of (2.33±0.62) mGy and (0.86±0.01) mGy and the dose length products of (65.01±25.12) mGy·cm and (23.55±3.38) mGy·cm,respectively,which presented differences between groups (both P<0.001).The image noise in the bilateral upper and middle lung areas in group B2 was lower than that in group B1 but higher than that in group A (all P<0.001).There was no significant difference in image quality score of the lung window among groups (all P>0.05).Groups A,B1,and B2 had no significant differences in ascending aorta (P=0.538) or liver CT value (P=0.175) in the mediastinal window.The signal-to-noise ratios and contrast-to-noise ratios of ascending aorta and liver in group B2 were higher than those in group B1 (all P<0.001) and lower than those in group A (all P<0.05).The image quality score of the mediastinal window followed a descending order of group A>group B2>group B1 (all P<0.001). Conclusion ASiR-V combined with low tube voltage can effectively reduce the radiation dose and guarantee the image quality of chest CT of children in the plateau area.

DETERMINATION OF DIAGNOSTIC REFERENCE LEVEL (DRL) AND STUDY OF EXPOSURE PARAMETER SELECTION IN HEAD AND ABDOMEN CT SCAN AT BANGIL REGIONAL HOSPITAL

A study has been conducted to determine the local diagnostic reference level (DRL) value of CT scans at Bangil Regional Hospital. The determination and calculation of the DRL value are based on the measurement of the patient's dose, namely using the CT scan examination results in the form of CTDIVol values and DLP values. The DRL value is determined from the CTDIVol and DLP data distribution in quartile 3. Patient dose data uses a Toshiba 16-slice CT scan and a Canon 160-slice CT scan. Seven hundred twenty data were obtained, distinguished by 680 adults and 40 children. The local DRL value at Bangil Regional Hospital for CT scans of the Head without contrast for the adult group CTDIVol 47.5 mGy and DLP 1162 mGy.cm. CT scans of the Head with contrast for the adult group CTDIVol 47.22 mGy and DLP 2784.38 mGy.cm. DRL on CT scan Abdomen without contrast adult age group at Bangil Hospital CTDIVol 3.7 mGy and DLP 179.9 mGy.cm. CT scan of Abdomen with contrast CTDIVol 3.9 mGy and DLP 774.92 mGy.cm. When compared to the National DRL value, this value is still below the National DRL value. However, the nature of DRL is dynamic, so each period is expected to be lower. Efforts should focus on achieving lower DRL values by considering the selection of parameters and the skills of radiographers that influence the dose administered to patients. Values that exceed the DRL value are evaluated using the choice of parameters. Factors that affect the DRL value include kV, mAs, rotation time, pitch, iterative reconstruction, and number of phases. The parameters used in CT scans at Bangil Hospital must be adjusted to provide optimal doses to patients. Keywords: diagnostic reference level (DRL), dose length product (DLP), CT dose index (CTDI), CT Head, CT Abdomen, dose delivery parameters.

LOCAL DIAGNOSTIC REFERENCE LEVEL BASED ON CLINICAL INDICATIONS IN HEAD CT EXAMINATION

Diagnostic Reference Level (DRL) in Computed Tomography (CT) examination should be developed based on clinical indications because each clinical indication uses different scanning parameters. This study aimed to create Local DRL values based on clinical indications (DRLCIL) in Head CT examinations. A retrospective study was conducted on patients who underwent Head CT examinations with clinical indications of Hemorrhagic Stroke (HS), Non-Hemorrhagic Stroke (NHS), Space Occupying Lesion (SOL) without contrast (SOL –C), SOL with contrast (SOL + C) and trauma. The total number of patients used in this study was 745 patients, patients with clinical indications of HS 231 patients, NHS 163 patients, SOL –C 158 patients, SOL + C 67 patients, and trauma 126 patients. The local DRLCIL value was determined using the 2nd quartile value of each clinical indication. The DRLCIL values obtained for the volume weighted CT dose index (CTDIvol) and dose length product (DLP) were respectively HS (52.9 mGy; 1020.4 mGy.cm), NHS (52.9 mGy; 1046.9 mGy.cm), SOL –C (52.9 mGy; 941.1 mGy.cm), SOL +C (52.9 mGy; 1935.0 mGy.cm), and trauma (52.9 mGy; 1469.9 mGy.cm). The DRLCIL value is relatively lower (except for clinical indications of trauma) than the Indonesian Diagnostic Reference Level (I-DRL) for the type of Non-Contrast Head CT examination with the percentage difference of CTDIvol and DLP respectively being HS (–11.83%; –19.97%), NHS (–11.83%; –17.89%), SOL –C (–11.83%; –26.19%) and SOL +C compared to I-DRL Head CT with contrast (–11.83%; –22.60%). For clinical indications of trauma, the local DRLCIL value from DLP is higher than the I-DRL value, with a percentage difference of 15.29%. However, the local DRLCIL value from CTDIvol is lower, with a percentage difference of –11.83%. Local DRL has been developed at the hospital level and can be used as a recommendation for protocol optimization based on clinical indications. Keywords: X-ray, CT scan, Head CT, diagnostic reference level (DRL), local DRL from clinical indications (DRLCIL).

RADIATION PATIENT AND WORKER DOSE APPLICATION (SI PADI)

Medical procedures for diagnostic and therapeutic purposes currently use many sources of ionizing radiation. Monitoring patient and radiation worker doses is needed to keep the radiation dose received to a minimum. The purpose of the patient and radiation worker dose application is to facilitate the task of Medical Physicists in conducting patient and radiation worker dose audits so that they become faster and more effective. The patient and radiation worker dose application is made based on dose audits conducted by Medical Physicists by monitoring patient doses on CT Scan examinations using CT dose index volume (CTDIvol) and dose length product (DLP) parameters on CT Scans and patient doses of the Siemens Somatom 128 slice Cathlab using Dose Area Product (DAP) data on the Philips Azurion 7 C-Arm. Radiation worker dose audits are conducted using evaluation data from TLD badges, TLD eyes, and pocket dosimeters of radiation workers working at Karawang Regional Hospital. Data processing uses a spreadsheet program. The menus on the dashboard are combined with formulas so that the data automatically appears in tables, graphs, or special formats as needed. The radiation patient and worker dose information system (Si Padi) was successfully developed at Karawang Regional Hospital to realize efforts to optimize radiation protection and safety for patients and radiation workers. Keywords: patient dose, radiation worker dose, dose audit, CT dose index (CTDI), dose length product (DLP), dose area product (DAP), Si Padi application.

APPLICATION OF SIZE SPECIFIC DOSE ESTIMATE (SSDE) AS A LOCAL DIAGNOSTIC REFERENCE LEVEL IN HEAD CT SCAN EXAMINATION AT INDRIATI HOSPITAL SOLOBARU, DR. MOEWARDI HOSPITAL SURAKARTA, SLEMAN HOSPITAL, AND NATIONAL BRAIN CENTER HOSPITAL JAKARTA

CT scan is a modality that produces a higher radiation dose compared to other modalities in radiodiagnostic installations. The radiation dose received by patients from examinations with this CT scan device is expressed in the volume CT Dose Index (CTDIvol) and Dose Length Product (DLP), which are dose indicators from the Indonesian Diagnostic Reference Level (DRL) value regulated in the Decree of the Head of the Nuclear Energy Regulatory Agency (BAPETEN) nationally. However, the CTDIvol value is only an indicator of the output dose from the CT scan, and the DLP value is an indicator of the total dose during the examination, which is influenced by the length of the scan. Both do not represent the specific dose received by the patient because the patient's dose depends not only on the output dose but also on the patient's characteristics. The patient's dose, which includes the output dose and patient characteristics, is called the Size-Specific Dose Estimate (SSDE), which is used to estimate the dose received by the patient by including a correction factor depending on the patient's dimensions. This study aims to calculate the SSDE value in a CT Head examination with a standard protocol using the same type of device, namely a 128-slice CT scan in several hospitals. The values of CTDIvol and DLP patients are obtained from the dose report displayed on the CT scan monitor screen in the IndoseCT software. The patient samples studied were patients undergoing CT Head examinations from March 2023 to February 2024, with 100 patients in each hospital. The results of this study obtained local DRL values based on SSDE calculated at Indriati Hospital, Moewardi Hospital, Sleman Hospital, and the National Brain Center Hospital and then compared them with the national TPD values. Based on the SSDE value from Indriati Hospital, the TPD value was 30.26 mGy, Sleman Hospital was 39.5 mGy, Dr. Moewardi Hospital was 49.3 mGy, and RSPON was 51.7 mGy. The TPD value of CT Head examinations without contrast from each hospital was still below the national TPD value of 60 mGy. Keywords: CT scan, diagnostic reference level (DRL), local DRL, national DRL, Size-Specific Dose Estimate (SSDE), IndoseCT.

Comparative Analysis of CT Fluoroscopy Modes and Gastropexy Techniques in CT-Guided Percutaneous Radiologic Gastrostomy.

This study was conducted to compare two modes of computed tomography fluoroscopy (CTF) and two gastropexy techniques used in CT-guided percutaneous radiologic gastrostomy (CT-PRG) aiming to identify the optimal techniques for image guidance and gastropexy and, thus, to overcome the current lack of consensus on the preferred modalities. We retrospectively identified 186 successful CT-PRG procedures conducted evenly across two university hospitals from January 2019 to December 2023. Patients were divided into two groups (intermittent multislice CT biopsy mode-guided technique (MS-CT BM) and retention anchor suture (T-fastener) versus real-time (RT-)CTF and gastropexy device) for descriptive analysis of demographics, indication for PRG, radiation exposure (DLP), procedural time, number of CT scans, gastropexy time, and complications. Differences were assessed for statistical significance using Fisher's exact test and the Mann-Whitney U-test. Our final study population comprised 100 patients (50 from each center; 62.52 ± 12.36 years, 73 men). There was a significant difference in radiation exposure between MS-CT BM (group 1) and RT-CTF (group 2), with an average dose-length product (DLP) of 56.28 mGycm×m ± 67.89 and 30.91 ± 27.53 mGycm×cm, respectively (p < 0.001). PRG with RT-CTF guidance was significantly faster than PRG with MS-CT BM, with an average difference of 10.28 min (p < 0.001). No significant difference in duration was found between the two gastropexy methods compared (retention anchor suture, 11.50 ± 5.239 s vs. gastropexy device, 11.17 ± 6.015 s; p = 0.463). Complication rates did not differ significantly either (p = 0.458). Our findings indicate comparable efficacy and safety of the two gastropexy methods and underscore that the choice of CTF mode for image guidance has only a small role in reducing radiation exposure in patients undergoing CT-PRG. Instead, it is essential to avoid control scans.

ESTIMATION OF PATIENT RADIATION DOSE WITH SIZE SPECIFIC DOSE ESTIMATE (SSDE) METHOD IN ABDOMEN CT-SCAN EXAMINATION AT SEMEN GRESIK HOSPITAL

CT-Scan abdomen is an examination to see the anatomy and pathology of the abdominal organs, and the scanning image results are in the form of three-dimensional axial images of the body. The radiation dose released from the CT-Scan examination is more significant than other radiology modalities. Therefore, it is very important to estimate the patient's dose accurately. Computed Tomography Dose Index (CTDIvol) and Dose Length Product (DLP) are dose parameters used in CT-Scan to describe the dose value received by the patient. However, these parameters are the output of the CT-Scan, not as the dose received by the patient. The Size Specific Dose Estimate (SSDE) method based on AAPM Report No. 204 is used to determine the estimated dose received by the CT-Scan Abdomen patient. Calculations are done manually and with IndoseCT software. The data used are secondary data of 60 patients, namely 21 females and 39 males, who were on the CT-Scan Abdomen examination without contrast from the Instalasi Radiologi Rumah Sakit Semen Gresik. The SSDE value is obtained from the multiplication between the conversion factor and CTDIvol, where the conversion factor is an effective diameter function. The analysis examined the error value in manual calculations and IndoseCT software in men and women, the relationship between effective diameter and scanning radiation output (CTDIvol), and dose estimation estimates (SSDE). The difference in SSDE values between manual calculations and IndoseCT software was insignificant. The highest error value in women was 3% and 3.2% in men. Meanwhile, the relationship between effective diameter (Deff) and scanning radiation output (CTDIvol) and dose estimation estimates (SSDE) showed that the correlation between effective diameter (Deff) and CTDIvol showed a stronger correlation, namely with R2 around 0.7 in women and men, compared to the correlation between effective diameter (Deff) and SSDE with R2 around 0.03 in women and 0.2 in men. Keywords: CT-Scan, Abdomen, Size Specific Dose Estimate (SSDE).