Variations In Radiation Dose Research Articles

Institutional Variation in Patient Radiation Doses During Transcatheter Valve Interventions: A Statewide Experience

BackgroundLittle is known about institutional radiation doses during transcatheter valve interventions. ObjectivesThe authors sought to evaluate institutional variability in radiation doses during transcatheter valve interventions. MethodsUsing a large statewide registry, transcatheter edge-to-edge mitral valve repair, transcatheter mitral valve replacement, and transcatheter aortic valve replacement procedures between January 1, 2020, and December 31, 2022, with an air kerma (AK) recorded were analyzed. Patient and procedural characteristics were compared between cases with AK ≥2 and <2 Gy. Associations of variables with AK ≥2 Gy were investigated using Bayesian random effects modeling and median ORs for the performing hospital. ResultsAmong 9,446 procedures across 30 hospitals, median (Q1-Q3) procedural AK was 0.592 Gy (0.348-0.989 Gy) with AK ≥2 Gy in 533 cases (5.6%). Wide variation in procedural AK was observed, with an institutional frequency of AK ≥2 Gy ranging from 0.0% to 29.5%. Bayesian modeling identified the performing hospital as more strongly associated with the odds of a procedural AK ≥2 Gy than any patient or procedural factors (hospital median OR: 3.54 [95% credible interval: 2.52-16.66]). ConclusionsIn a large, multicenter state-wide registry, there is wide institutional variability in patient-level radiation doses during transcatheter valve interventions, with the performing hospital having a higher odds of an AK ≥2 Gy than any patient or procedural factors. Future interventions are warranted to reduce procedural-related variation in radiation exposure.

MPPD: A User-Friendly Posture Deformation Program for Mesh-Type Computational Phantoms.

Recently, the International Commission on Radiological Protection (ICRP) released adult Mesh-type Reference Computational Phantoms (MRCPs), which have great advantage in high deformability. Previous studies have exploited their high deformability to investigate the dosimetric influence of varying statures and postures, demonstrating significant variations in radiation doses. However, the previous studies are constrained by their inability to consider both stature and posture concurrently and by the limited range of postures analyzed. In the present study, a computer program named MPPD (Mesh-type Phantom Posture Deformer) was developed, a user-friendly graphical user interface that enables users to adjust the posture of adult MRCPs and corresponding library phantoms. The MPPD program was applied to deform five adult male phantoms of different statures into sitting and kneeling postures, showcasing its rapid computational speed and minimal RAM usage. The effectiveness of the MPPD program for dose calculation was also investigated by computing the detriment-weighted doses for MPPD-deformed adult male MRCPs, which showed good agreement with dose values for existing posture-deformed phantoms of the previous study. Furthermore, as an application of the MPPD program, the combined dosimetric impact of stature and posture was investigated, which is the inaugural effort to estimate doses by considering these factors concurrently. The result showed that the impact of stature and posture on radiation doses could largely vary depending on the radiation source, highlighting the importance of simultaneous consideration of stature and posture for accurate dose estimation.

A Whole-Spine Radiography Study to Reduce Patient Exposure Dose and Artifacts Using the EOS Imaging System.

Whole-spine radiography can be accomplished through two methods: (1) segmented imaging employing X-ray tube angulation and detectors, or (2) the Euronext Paris Advanced Orthopedic Solutions (EOS) 2D Imaging system that can capture the entire spine in a single image using X-ray tubes and detectors oriented at a 90-degree angle. This study aimed to establish optimal EOS examination parameters based on patient morphotype and scan speed to reduce patient radiation exposure, repeat examinations, heat stress on equipment, and X-ray tube cooling time. X-ray exposure conditions involved adjustments of scan speed ranging from two to four steps, contingent upon the patient's morphotype ('S', small body; 'M', medium body; and 'L', large body. Patient dose measurements were conducted 20 times for each set of conditions. When transitioning from an 'S' to an 'M' morphotype at a constant scan speed, the entrance skin dose (ESD) exhibited an increase of approximately 41.25 ± 4.57%. A similar change from an 'M' to an 'L' morphotype resulted in an ESD increase of roughly 59.56 ± 24.00%. A transition from an 'S' to an 'L' morphotype at the same scan speed manifested an ESD elevation of approximately 124.21 ± 26.96%. This study underscores significant variations in radiation dose, ranging from 40% to 50%, when altering morphotype while maintaining a consistent scan speed.

Strategies for minimizing repeated exposures in diagnostic radiography

Advancements in diagnostic radiography have significantly improved medical imaging, yet the associated radiation exposure poses health risks, particularly with repeated examinations. Technological innovations, including the transition from analog to digital radiography, have led to substantial reductions in radiation doses while enhancing image quality. Digital systems, coupled with automatic exposure control (AEC), dynamically adjust radiation levels based on patient size and diagnostic requirements, minimizing unnecessary exposure. Iterative reconstruction algorithms in CT imaging further reduce radiation doses by efficiently processing images and reducing noise. Hardware improvements, such as high-efficiency detectors, capture high-quality images with lower radiation levels, contributing to dose reduction. Standardizing radiographic protocols across healthcare settings ensures consistent practices, reducing variability in radiation doses. Techniques such as beam collimation and appropriate shielding protect surrounding tissues and enhance image quality, while continuous education for technologists maintains proficiency in dose-reduction strategies. Patient education is crucial for minimizing repeated exposures. Informing patients about the risks of ionizing radiation and the importance of adhering to follow-up schedules can reduce unnecessary examinations. Electronic health records (EHRs) facilitate the tracking of cumulative radiation doses, enabling informed decision-making regarding additional imaging studies. Adherence to the ALARA principle (As low as reasonably achievable) in clinical practice ensures that radiation exposure is minimized while achieving diagnostic goals. Special considerations for vulnerable populations, such as children and pregnant women, further enhance safety. Implementing radiation safety measures and maintaining a commitment to ongoing professional development for healthcare providers fosters a culture of safety within radiology departments. By integrating these strategies, healthcare providers can balance the diagnostic benefits of radiography with the imperative to protect patients from unnecessary radiation exposure, ultimately enhancing patient safety and improving diagnostic outcomes. This comprehensive approach ensures that radiographic procedures remain both effective and safe, optimizing patient care in medical imaging.

Analysis and consideration of radiation dose distribution in cardiac catheterization interventions

objective: To assess the variations in radiation dose at different areas in the cardiac catheterization room during cardiac catheterization interventions. methods:To simulate the conventional operation in cardiac catheterization interventions, perform angiography on standard manikins ,the radiation dose was collected from 22 areas in the cardiac catheterization room under 8 projection angles, and each area was repeated 5 times, and the collected data was analyzed using one-way ANOVA and independent sample t-test. results:Analysis of the radiation dose in 22 areas under 8 projection angles revealed that the lowest radiation dose was found in the area at the end of the operating table in the cardiac catheterization room (p &lt; 0.05), and the highest radiation dose was found in the area on the left and right sides of the X-ray tube (p &lt; 0.05); the radiation dose in the area on the right side of the X-ray tube of the DSA machine was greater than that in the conventional standing area of the first operator (p &lt; 0.05)，and the radiation dose in the conventional standing area of the second operator was greater than that in the conventional standing area of the first operator (p &lt; 0.05); the radiation dose in the standing area of the first operator was highest in the cephalic position (CRA 30°) (p &lt; 0.05), and the radiation dose in the standing area of the second operator was highest in the left anterior oblique position (LAO 45°) (p &lt; 0.05); in the angle of RAO projection, the radiation dose in the right area of the X-ray tube was greater than that in the left area of the X-ray tube (p &lt; 0.05). Under the RAO projection angle, the radiation dose from the right side of the X-ray tube of the DSA machine was greater than that from the left side (p&lt;0.05), and the result was reversed at the projection angle of the LAO. conclusion:The radiation dose during cardiac catheterization interventions is lowest in the area at the end of the operating table, which can be used as a standing area for nurses and as an area for the placement of surgical equipment and supplies. At the same time, it is necessary to pay attention to the radiation dose to the second operator and to further improve the radiation protection measures for the second operator, and additional measures are needed to minimize the radiation dose to the operators in the cephalic position (CRA 30°) and in the left anterior oblique position (LAO 45°).

Image quality and radiation doses in abdominal CT: A multicenter study

PurposeTo benchmark image quality and corresponding radiation doses for acute abdominal CT examination across different laboratories and CT manufacturers. MethodAn anthropomorphic phantom was scanned once with local abdominal CT protocols at 40 CT scanners, from four vendors, in thirty-three sites. Quantitative image quality was evaluated by CNR and SNR in the liver and kidney parenchyma. Qualitative image quality was assessed by visual grading analysis performed by three experienced radiologists using a five-point Likert scale to score thirteen image quality criteria. The CTDIvol was recorded for each scan. Pearson’s correlation coefficient was calculated for the continuous variables, and the intraclass correlation coefficient was used to investigate interrater reliability between the radiologists. ResultsCTDIvol ranged from 3.5 to 12 mGy (median 5.3 mGy, third quartile 6.7 mGy). SNR in liver parenchyma ranged from 4.4 to 14.4 (median 8.5), and CNR ranged from 2.7 to 11.2 (median 6.1). A weak correlation was found between CTDIvol and CNR (r = 0.270, p = 0.092). Variations in CNR across scanners at the same dose level CTDIvol were observed. No significant difference in CTDIvol or CNR was found based on scanner installation year. The oldest scanners had a 15 % higher median CTDIvol and a 12 % lower median CNR. The ICC showed acceptable agreement for all dose groups: low (ICC=0.889), medium (ICC=0.767), high (ICC=0.847), and in low (ICC=0.803) and medium (ICC=0.811) CNR groups. ConclusionThere was large variation in radiation dose and image quality across the different CT scanners. Interestingly, the weak correlation between CTDIvol and CNR indicates that higher doses do not consistently improve CNR, indicating a need for systematic assessment and optimization of image quality and radiation doses for the abdominal CT examination.

Evaluation of the performance of digital x-ray systems in pelvis radiography

The aim of this study was to investigate the performance of eight digital radiography systems and to optimise the dose-image quality relationship for digital pelvis radiography. The study involved eight digital radiography systems used for general examinations at Vilnius University Hospital Santaros Klinikos. An anthropomorphic pelvic phantom (CIRS, US) was used to simulate a patient undergoing clinical pelvis radiography. Dose quantities entrance surface dose, dose area product (DAP) and exposure parameters (kVp, mA, mAs) were measured and the effects on the images were evaluated, considering physical contrast to noise ratio (CNR) and observer-based evaluations as image quality metrics. Increasing the tube voltage by 5 kVp from standard protocol led to a reduction in radiation dose (DAP) by 12%–20% with a slight impact on image quality (CNR decreases by 2%–10%). There was an inter-observer variability in image rating across different equipment (kappa value between 0 and 0.3); however, both observers agreed that increasing kVp up to 85–90 kV had no effect on perceived image quality. The results indicate that optimisation strategies should be tailored specifically for each x-ray system since significant performance differences and wide variations in radiation dose exist across various digital radiography systems used in clinical settings. The use of high kVp can be used for dose optimisation in digital pelvis radiography without compromising image diagnostic accuracy.

Quantitative analysis of radiosensitizing effect for magnetic hyperthermia-radiation combined therapy on prostate cancer cells.

Magnetic hyperthermia (MHT) has emerged as a promising therapeutic approach in the field of radiation oncology due to its superior precision in controlling temperature and managing the heating area compared to conventional hyperthermia. Recent studies have proposed solutions to address clinical safety concerns associated with MHT, which arise from the use of highly concentrated magnetic nanoparticles and the strong magnetic field needed to induce hyperthermic effects. Despite these efforts, challenges remain in quantifying therapeutic outcomes and developing treatment plan systems for combining MHTwith radiation therapy (RT). This study aims to quantitatively measure the therapeutic effect, including radiation dose enhancement (RDE) in the magnetic hyperthermia-radiation combined therapy (MHRT), using the equivalent radiation dose (EQD) estimation method. To conduct EQD estimation for MHRT, we compared the therapeutic effects between the conventional hyperthermia-radiation combined therapy (HTRT) and MHRT in human prostate cancer cell lines, PC3 and LNCaP. We adopted a clonogenic assay to validate RDE and the radiosensitizing effect induced by MHT. The data on survival fractions were analyzed using both the linear-quadradic model and Arrhenius model to estimate the biological parameters describing RDE and radiosensitizing effect of MHRT for both cell lines through maximum likelihood estimation. Based on these parameters, a new survival fraction model was suggested forEQD estimation of MHRT. The newly designed model describing the MHRT effect, effectively captures the variations in thermal and radiation dose for both cell lines (R2>0.95), and its suitability was confirmed through the normality test of residuals. This model appropriately describes the survival fractions up to 10Gy for PC3 cells and 8Gy for LNCaP cells under RT-only conditions. Furthermore, using the newly defined parameter r, the RDE effect was calculated as 29% in PC3 cells and 23% in LNCaP cells. EQDMHRT calculated through this model was 9.47Gy for PC3 and 4.71Gy for LNCaP when given 2Gy and MHT for 30 min. Compared to EQDHTRT, EQDMHRT showed a 26% increase for PC3 and a 20% increase for LNCaP. The proposed model effectively describes the changes of the survival fraction induced by MHRT in both cell lines and adequately represents actual data values through residual analysis. Newly suggested parameter r for RDE effect shows potential for quantitative comparisons between HTRT and MHRT, and optimizing therapeutic outcomes in MHRT for prostate cancer.

In-depth exploration of the radiation exposure to staff performing endoscopic retrograde cholangiopancreatography procedures (ERCP) through RANDO phantom and TLDs.

This study provides a comprehensive evaluation of the occupational radiation exposure faced by healthcare professionals during Endoscopic Retrograde Cholangiopancreatography (ERCP) procedures. Utilizing an anthropomorphic RANDO phantom equipped with Thermoluminescent Dosimeters (TLDs), we replicated ERCP scenarios to measure radiation doses received by medical staff. The study meticulously assessed radiation exposure in various corresponding body regions typically occupied by medical staff during ERCP, with a focus on eyes, thyroid, hands, and reproductive corresponding organ regions. The findings revealed significant variations in radiation doses across different body parts, highlighting areas of higher exposure and underscoring the need for improved protective measures and procedural adjustments. The effective radiation doses were calculated using standard protocols, considering the varying levels of protection offered by lead aprons and thyroid shields. The results demonstrate the substantial radiation exposure experienced by healthcare staff, particularly in regions not adequately shielded. This study emphasizes the necessity for enhanced radiation safety protocols in clinical settings, advocating for advanced protective equipment, training in radiation safety, and the exploration of alternative imaging modalities. The findings have crucial implications for both patient and staff safety, ensuring the continued efficacy and safety of ERCP and similar interventional procedures. This research contributes significantly to the field of occupational health and safety in interventional radiology, providing vital data for the development of safer medical practices.

B-42 | Institutional Variation in Radiation Doses During Transcatheter Valvular Interventions: A Statewide Experience

B-42 | Institutional Variation in Radiation Doses During Transcatheter Valvular Interventions: A Statewide Experience

A preliminary study of multispectral Cherenkov imaging and a Fricke-xylenol orange gel film (MCIFF) for online, absolute dose measurement.

Cherenkov luminescence imaging has shown potential for relative dose distribution and field verification in radiation therapy. However, to date, limited research utilizing Cherenkov luminescence for absolute dose calibration has been conducted owing to uncertainties arising from camera positioning and tissue surface optical properties. This paper introduces a novel approach to multispectral Cherenkov luminescence imaging combined with Fricke-xylenol orange gel (FXG) film, termed MCIFF, which can enable online full-field absolute dose measurement. By integrating these two approaches, MCIFF allows for calibration of the ratio between two spectral intensities with absorbed dose, thereby enabling absolute dose measurement. All experiments are conducted on a Varian Clinac 23EX, utilizing an electron multiplying charge-coupled device (EMCCD) camera and a two-way image splitter for simultaneous capture of two-spectral Cherenkov imaging. In the first part of this study, the absorbance curves of the prepared FXG film, which receives different doses, are measured using a fluorescence spectrophotometer to verify the correlation between absorbance and dose. In the second part, the FXG film is positioned directly under the radiation beam to corroborate the dose measurement capacity of MCIFF across various beams. In the third part, the feasibility of MCIFF is tested in actual radiotherapy settings via a humanoid model, demonstrating its versatility with various radiotherapy materials. The results of this study indicate that the logarithmic ratios of spectral intensities at wavelengths of 550±50 and 700±100nm accurately reflect variations in radiation dose (R2>0.96) across different radiation beams, particle energies, and dose rates. The slopes of the fitting lines remain consistent under varying beam conditions, with discrepancies of less than 8%. The optical profiles obtained using the MCIFF exhibit a satisfactory level of agreement with the measured results derived from the treatment planning system (TPS) and EBT3 films. Specifically, for photon beams, the lateral distances between the 80% and 20% isodose lines, referred to as the penumbra (P80-20) values, obtained through TPS, EBT3 films, and MCIFF, are determined as 0.537, 0.664, and 0.848cm, respectively. Similarly, for electron beams, the P80-20 values obtained through TPS, EBT3 films, and MCIFF are found to be 0.432, 0.561, and 0.634cm, respectively. Furthermore, imaging of the anthropomorphic phantom demonstrates the practical application of MCIFF in real radiotherapy environments. By combining an FXG film with Cherenkov luminescence imaging, MCIFF can calibrate Cherenkov luminescence to absorbed dose, filling the gap in online 2D absolute dose measurement methods in clinical practice, and providing a new direction for the clinical application of optical imaging to radiation therapy.

Study the variations in radiation doses in different multi-slice CT scan machines

Objectives: This study aimed to measure variations in dose output and patient’s effective dose across the different computed tomography scanners during standard CT examinations of head, chest and abdomen, so as to determine patient, and machine settings that contribute to variations in radiation dose to optimize patient effective dose. Methods: Retrospective, study performed in different hospitals, in Najran province (K.S.A) from October 2022 to June 2023. The study comprise 360 adults CT examinations. The mean values of CT dose index volume (CTDIvol) and dose length product (DLP) were measured. The patient effective dose (ED) were calculated for each protocol and compared among different CT scanners. Results: The mean values of CTDIvol , DLP, and ED, varied across the different CT scanners, Regarding abdomen CT, the CTDIvol mean values were (5.56 mGy to 18.655 mGy) , the DLP (289.78 to 968.241 mGy/cm), and mean effective doses were (4.34 to 14.5 mSv), in chest CTs the mean values of CTDIvol were (5.05 to 14.39mGy), the DLP were (202.84 to 499.098mGy/cm), and median effective doses were (2.85 to 6.97 mSv), in head CTs the mean values of CTDIvol were (42.4to 68.278mGy), the DLP were (781 to 1209.18mGy/cm), and effective doses were (1.636 to 2.528mSv). Conclusion: Regarding selected exams, CTDI, DLP and ED were found to be varied from low variations in head CT scan, to medium in chest CT scan and high variation in abdomen CTs among different CT scanners, The highest values of CTDI and DLP were noted in head CTs followed by abdomen, and the lowest were in chest CTs. The most factors affected the CT dose variations were the technical parameters settings, mainly the number of slices, however the scanner specifications reported some impact. Optimizing dose to a reliable standard for each anatomical part should be adjusting independently by each department according to the scanner characteristics, settings and patient factors.

The Impact of Radiation Dose Variation in Panoramic Dental Examination on Salivary Amylase Enzyme Activity

The surge in oral and dental diseases has amplified the significance of dental panoramic imaging as a diagnostic tool for healthcare professionals. However, such imaging subjects patients to radiation, impacting salivary pH and amylase enzyme activity. This study of 30 patients aimed to measure radiation doses and their effects on salivary pH and amylase enzyme activity. Radiation doses were quantified using a Thermoluminescent Dosimeter (TLD-100) and analyzed with a TLD reader. Salivary pH was determined using a digital pH meter, and amylase enzyme activity was assessed through the iodine method, involving a reaction between a 1% amylum solution, iodine solution, and saliva. Results showed an average radiation dose of 2.33 μSv, significantly affecting salivary pH. Specifically, 28 patients experienced an average pH decrease of 0.34, while 2 had an average pH increase of 0.385. These pH changes corresponded with variations in amylase enzyme activity. In 17 patients, amylase activity increased by an average of 0.75×10-4 units/mL, while 13 patients exhibited an average decrease of 0.96×10-4 units/mL. This underscores the intricate relationship between radiation dose, salivary pH, and amylase enzyme activity, warranting further exploration within dental panoramic imaging.

Evaluation of radionuclides in sugar samples from different regions of Brazil

Sugar contains radionuclides and its consumption may result in an increase of the internal dose in humans. Thus, this work evaluates the profile and activity of radionuclides present in 4 VHP sugar samples obtained from producers from 4 cities in Brazil, located in the Southeast and Midwest regions: Pirajuba (State of Minas Gerais), Edeia (Goiás), Pitangueira (São Paulo) and Mendonça (São Paulo). The samples were collected between the years 2019 and 2020. The analyzes were performed by gamma spectrometry using a hyper pure germanium semiconductor detector (HPGe) counting the samples over a period of 24 hours. The same profiles of radionuclides 226Ra, 212Pb, 214Bi, 40K were observed in all samples, except for the sample from Mendonça, which presented a low counting rate for 214Bi. Calculations of specific activity were carried out for the two most abundant radionuclides, 226Ra and 40K, obtaining the following values (in Bq kg-1): for 226Ra Pirajuba (22.43 Bq kg-1), Edeia (22.38 Bq kg-1), Pitangueira (18.25 Bq kg-1) and Mendonça (36.16 Bq kg-1) and for 40K Pirajuba (0.66 Bq kg-1), Edeia (0.99 Bq kg-1), Pitangueira (0.66 Bq kg-1) and Mendonça (0.33 Bq kg-1). Additionally, the values ​​of total absorbed dose rate were calculated: ​​Pirajuba (43.61 nGy h-1), Edeia (43.60 nGy h-1), Pitangueira (41.82 nGy h-1) and Mendonça (49.45 nGy h-1). Therefore, according to the United Nations Scientific Committee on the Effects of Atomic Radiation, the results obtained did not show a significant transfer of absorbed dose due to radionuclides from sugar consumption under the conditions adopted in this work. No variation of radiation dose according to the region or year of production was observed.

Large variation in radiation dose for routine abdomen CT: reasons for excess and easy tips for reduction

ObjectiveTo characterize the use and impact of radiation dose reduction techniques in actual practice for routine abdomen CT.MethodsWe retrospectively analyzed consecutive routine abdomen CT scans in adults from a large dose registry, contributed by 95 hospitals and imaging facilities. Grouping exams into deciles by, first, patient size, and second, size-adjusted dose length product (DLP), we summarized dose and technical parameters and estimated which parameters contributed most to between-protocols dose variation. Lastly, we modeled the total population dose if all protocols with mean size-adjusted DLP above 433 or 645 mGy-cm were reduced to these thresholds.ResultsA total of 748,846 CTs were performed using 1033 unique protocols. When sorted by patient size, patients with larger abdominal diameters had increased dose and effective mAs (milliampere seconds), even after adjusting for patient size. When sorted by size-adjusted dose, patients in the highest versus the lowest decile in size-adjusted DLP received 6.4 times the average dose (1680 vs 265 mGy-cm) even though diameter was no different (312 vs 309 mm). Effective mAs was 2.1-fold higher, unadjusted CTDIvol 2.9-fold, and phase 2.5-fold for patients in the highest versus lowest size-adjusted DLP decile. There was virtually no change in kV (kilovolt). Automatic exposure control was widely used to modulate mAs, whereas kV modulation was rare. Phase was the strongest driver of between-protocols variation. Broad adoption of optimized protocols could result in total population dose reductions of 18.6–40%.ConclusionThere are large variations in radiation doses for routine abdomen CT unrelated to patient size. Modification of kV and single-phase scanning could result in substantial dose reduction.Clinical relevanceRadiation dose-optimization techniques for routine abdomen CT are routinely under-utilized leading to higher doses than needed. Greater modification of technical parameters and number of phases could result in substantial reduction in radiation exposure to patients.Key Points• Based on an analysis of 748,846 routine abdomen CT scans in adults, radiation doses varied tremendously across patients of the same size and optimization techniques were routinely under-utilized.• The difference in observed dose was due to variation in technical parameters and phase count. Automatic exposure control was commonly used to modify effective mAs, whereas kV was rarely adjusted for patient size. Routine abdomen CT should be performed using a single phase, yet multi-phase was common.• kV modulation by patient size and restriction to a single phase for routine abdomen indications could result in substantial reduction in radiation doses using well-established dose optimization approaches.

Dosimetry verification of in vitro radiotherapy dose via laser polishing of 3D-printed metallic implant surface

Titanium alloys have been frequently used for medical implants. However, their presence can cause variability in radiation dose during radiotherapy, leading to potential complications. Herein, this work aims to explore the impact of 3D printed Ti6Al4V implants on the dose of 6MV X-ray in radiotherapy, through direct measurement in the ionization chamber. The findings indicate that the absorption effect of titanium alloy implants lowers the dose behind the implants, while the backscattering effect increases the dose in front of the implants. It is demonstrated that the size, thickness, and mesh density of the titanium alloy implant show no significant effect on the dose in front of the implants. Nonetheless, it is found that the dose behind the implants increases with mesh density and decreases with implant thickness. Laser polishing is implemented as a surface modification technique for titanium implants, resulting in significantly improved implant surface smoothness, a reduction of the surface roughness, a decrease in defects and an alteration in the elemental composition percentage. Furthermore, the reduction in surface roughness leads to a transition towards a hydrophilic implant surface, which also leads to the enhancement of specular reflection and the reduction of diffuse scattering on the implant surface, thus producing a complex influence on the radiation dose. It is also revealed that at a constant X-ray irradiation energy, the dose values in front of and behind the implant both exhibit a declining trend as the irradiation field size increases. Finally, the existence of a dose compensation effect of scattered radiation on the primary radiation during radiotherapy is confirmed. This work provides important reference for clinical practice, aiding medical professionals in formulating precise treatment plans, optimizing the efficacy of radiotherapy, and minimizing side effects.

Characterization of patient dose distributions and probabilistic risk analysis in cardiovascular catheterization laboratories

Purpose: Patient radiation doses in cardiovascular and interventional radiology are highly variable for similar procedures. This random nature may be better described by a distribution function, compared to a linear regression. This study develops a distribution function to characterize patient dose distributions and estimate probabilistic risk. Methods: Reference air kerma from 8647 patients over six years were retrospectively collected from an EP lab and two Cath labs. Data was first sorted into low dose (<100mGy) and high dose cases (>100mGy), and histograms of the data created. Dagum and Inverse gamma distributions were chosen to initially fit to both low and high dose cases. Fits between model and the data was optimized, and a linear regression analysis performed to obtain R squared values and standard errors for the correlation between model and data. Risk probabilities were estimated according to the modeled distribution function. BMI and time distributions were analyzed to understand their influence on the inverse gamma distribution error found in the data. 75th percentiles from both descriptive statistics and model were calculated. Results: The inverse gamma distribution can be used to characterize radiation dose distributions. Model predicted cases for radiation dose 3000mGy< x <5000mGy and >5000mGy are approximately 42 and 0 for 3651 cases for lab#1, and 14 and 1 for 3197 cases for lab#2, respectively, while the actual cases are 10 and 0, and 16 and 2. Descriptive and model statistics generated different 75th percentile levels for sorted data compared to unsorted data. Time has a greater influence on inverse gamma distribution function than BMI. Conclusion: This study creates a framework to understand the random error present in radiology practices that cause wide variations in patient radiation doses. It also provides an approach to evaluate different IR areas in terms of effectiveness of dose reduction measures.

Dummy run quality assurance study in the Korean Radiation Oncology Group 19 − 09 multi-institutional prospective cohort study of breast cancer

BackgroundThe Korean Radiation Oncology Group (KROG) 19 − 09 prospective cohort study aims to determine the effect of regional nodal irradiation on regional recurrence rates in ypN0 breast cancer patients. Dosimetric variations between radiotherapy (RT) plans of participating institutions may affect the clinical outcome of the study. We performed this study to assess inter-institutional dosimetric variations by dummy run.MethodsTwelve participating institutions created RT plans for four clinical scenarios using computed tomography images of two dummy cases. Based on a reference structure set, we analyzed dose-volume histograms after collecting the RT plans.ResultsWe found variations in dose distribution between institutions, especially in the regional nodal areas. Whole breast and regional nodal irradiation (WBI + RNI) plans had lower inter-institutional agreement and similarity for 95% isodose lines than WBI plans. Fleiss’s kappa values, which were used to measure inter-institutional agreement for the 95% isodose lines, were 0.830 and 0.767 for the large and medium breast WBI plans, respectively, and 0.731 and 0.679 for the large and medium breast WBI + RNI plans, respectively. There were outliers in minimum dose delivered to 95% of the structure (D95%) of axillary level 1 among WBI plans and in D95% of the interpectoral region and axillary level 4 among WBI + RNI plans.ConclusionWe found inter-institutional and inter-case variations in radiation dose delivered to target volumes and organs at risk. As KROG 19 − 09 is a prospective cohort study, we accepted the dosimetric variation among the different institutions. Actual patient RT plan data should be collected to achieve reliable KROG 19 − 09 study results.

Establishment of diagnostic reference level and radiation dose variation in head &amp; neck and pelvis treatment planning in radiation therapy computed tomography

Background: This observational study aims to establish a discrepancy in the radiation dose distributed for head &amp; neck and pelvis localization in Computed Tomography (CT) imaging in radiation therapy. The objective and need of the current study are to establish Diagnostic Reference Level (DRL) for head &amp; neck and pelvic CT protocols in Radiation Therapy planning and compare them with other regional, national and international DRL. The established DRL will be used to find further optimized DRL for Radiation Therapy Computed Tomography (RTCT). Methods: A total of 120 patients with Head &amp; Neck cancers and 90 patients with pelvic cancers to be treated with radiotherapy prescribed for the RTCT with ages above 18 years old and above were included in the current study. The advanced Philips 16 slice big bore CT acquired all the CT simulation images. Results: Third quartile standards of Dose Length Product and effective dose for Head &amp; Neck, and pelvis were 790.65mGy.cm, 2.45179 mSv, and 999.7 mGy.cm, 15.48mSv respectively. The third quartile CTDIvol value for the same order of procedure is 17.6 mGy. Tube voltage of 120kVp and 300mAs and used for radiotherapy planning. Conclusion: The first regional Radiation therapy Computed tomography simulation Diagnostic reference levels have been projected and deliver a platform for dose evaluation and optimization due to the limited number of papers on radiation therapy, computed tomography, and diagnostic reference levels. Comparison with previously available RT CT diagnostic reference levels indicated some radiation dose variation, so exposure parameters should be revised and improved.

Establishment of diagnostic reference level and radiation dose variation in head &amp; neck and pelvis treatment planning in radiation therapy computed tomography

Background: This observational study aims to establish a discrepancy in the radiation dose distributed for head &amp; neck and pelvis localization in Computed Tomography (CT) imaging in radiation therapy. The objective and need of the current study are to establish Diagnostic Reference Level (DRL) for head &amp; neck and pelvic CT protocols in Radiation Therapy planning and compare them with other regional, national and international DRL. The established DRL will be used to find further optimized DRL for Radiation Therapy Computed Tomography (RTCT). Methods: A total of 120 patients with Head &amp; Neck cancers and 90 patients with pelvic cancers to be treated with radiotherapy prescribed for the RTCT with ages above 18 years old and above were included in the current study. The advanced Philips 16 slice big bore CT acquired all the CT simulation images. Results: Third quartile standards of Dose Length Product and effective dose for Head &amp; Neck, and pelvis were 790.65mGy.cm, 2.45179 mSv, and 999.7 mGy.cm, 15.48mSv respectively. The third quartile CTDIvol value for the same order of procedure is 17.6 mGy. Tube voltage of 120kVp and 300mAs and used for radiotherapy planning. Conclusion: The first regional Radiation therapy Computed tomography simulation Diagnostic reference levels have been projected and deliver a platform for dose evaluation and optimization due to the limited number of papers on radiation therapy, computed tomography, and diagnostic reference levels. Comparison with previously available RT CT diagnostic reference levels indicated some radiation dose variation, so exposure parameters should be revised and improved.