General radiographic patient dose monitoring using conformity test data

Currently, the Nuclear Energy Supervisory Agency (BAPETEN) is actively guiding users or license holders related to patient protection against radiation hazards or often referred to as radiation protection and safety on medical exposure. Protection against medical exposure became a big issue when the mandatory compliance test on X-ray equipment for diagnostic and interventional radiology was introduced. In addition, license holders through their medical practitioners are also required to use the level of medical exposure guidelines. While PERKA BAPETEN No. 9, 2011 concerning the Suitability Test of Diagnostic and Interventional Radiology X-Ray device, states that one of the test parameters that directly affect the patient's radiation dose and determine the feasibility of operating the X-Ray device to the patient is information on the dose or rate of radiation dose received by the patient. Monitoring doses with Entrance Surface Air Kerma (ESAK) or what is often referred to as ESD (entrance surface dose) using suitability conformity test data starting from 50,60,70,80,90 and 100 kVp with 20 mAs at SID 100 meters. The results of the research on the value of ESAK was 0.049 mGy, an ESAK value that still met the national I-DRL value from BAPETEN Regulation No. 1211/K/V/2021.

An Approach for Online Determining the Entrance Surface Air Kerma (ESAK) in Digital Radiology

An online method is proposed to determine the entrance surface air kerma (ESAK) in digital radiology from console-displayed kerma area product (PKA) data. ESAK values were calculated from X-ray tube outputs and patient exposure factors across five X-ray examinations. The corresponding PKAvalues were taken from the Digital Imaging and Communications in Medicine (DICOM) header. Using linear regression between ESAK and values, the slope and intercept coefficients for each type of X-ray equipment and procedure were determined. The coefficient to determine ESAK from ranged from 59% for a posteroanterior chest to 88% for anteroposterior lumbar spine view X-ray procedures. The results demonstrated the possibility of online estimates of ESAK from a console that displayed using readily available digital information in radiology. The results may have important implications in interventional radiology, where ESAK values are crucial for preventing skin injuries due to prolonged fluoroscopy times.

Comparison of entrance surface air kerma measurement with MTS-N (LiF: Mg, Ti) chips with a kilovoltage X-ray source

Objective: Radiation detectors are key components that ensure the accuracy and performances of dosimetry equipment. The study is aimed to compare the mean entrance surface air kerma (ESAK) between a DCT-10mm ionization chamber (IC) and MTS-N (LiF: Mg, Ti) chips when both detectors are exposed to ≤ 5mGy with a 10 by 10 field size, with an X-ray source and to determine the accuracy of the Thermoluminescent (TL) chips. Also, the dose will be compared to similar studies. Materials and Methods: A functional, Digital Radiography (DR) X-ray System was used. A DCT-10mm ionization chamber (IC) and an XR Multidetector was positioned at a Source to Image Distance (SID) of 100cm on polystyrene, about 20cm thick. An X-ray spectrum generated at a Practical Peak Voltage (PPV) of 60-107kV with Half Value Layer (HVL) of 2.4-4.3mmAl and filtration > 3mmAl was used. The same setup was used for the MTS-N chips. Results: The mean doses for 1-5 mGy with the MTS-N chips were 1.07±0.07, 1.60±0.13, 2.23±0.11, 2.58±0.07 and 3.45±0.10 mGy respectively, with accuracies of 7, 20, 26, 36 and 31%. Dose accuracy at 1and 2mGy was within 25% respectively. Dose accuracies at 3, 4 and 5mGy was within >25%. The correction factor for 1-5mGy was 0.94, 1.25, 1.35, 1.55 and 1.45 respectively. Conclusion: Validation of the MTS-N chips with the reference ionization chamber to this study was within 36%. The Radiation and Nuclear Safety Authority (STUK) recommends that ESAK be within 25% for entrance surface dose. ESAK accuracy mostly increased with dose as observed in this study.

ESTIMATION OF ENTRANCE SURFACE AIR KERMA IN DIGITAL RADIOGRAPHIC EXAMINATIONS

Purpose: Contribution of radiation doses from medical X-ray examination to collective dose is significant. Unusually, high doses may increase the risk of stochastic effects of radiations. Therefore, radiation dose assessment was performed in 241 digital X-ray examinations in the study and was compared with published dose reference levels (DRLs). Methods: Entrance surface air kerma (ESAK) was calculated in chest PA, cervical AP/Lat, abdomen AP, lumbar AP/Lat and pelvis AP digital radiographic examinations (119 male and 122 female) following the International Atomic Energy Agency recommended protocol. Initially, 270 digital examinations were selected, reject analysis was performed and final 241 examinations were enrolled in the study for dose calculations. The exposure parameters and X-ray tube output were used for dose calculations. Effective doses were estimated with the help of conversion coefficients from ICRP 103. Results: Median ESAK (mGy) and associated effective doses obtained were cervical spine AP (1.30 mGy, 0.045 mSv), cervical spine Lat (0.25 mGy, 0.005 mSv), chest PA (0.11 mGy, 0.014 mSv), abdomen AP (0.90 mGy, 0.118 mSv), lumbar spine AP (1.52 mGy, 0.177 mSv), lumbar spine Lat (7.76 mGy, 0.209 mSv) and pelvis AP (0.82 mGy, 0.081 mSv). Results were compared with the studies of UK, Oman, India and Canada. Conclusion: The calculated ESAK and effective dose values were less than or close to previously published literature except for cervical spine AP and lumbar spine Lat. The results reinforce the need for radiation protection optimization, improving examination techniques and appropriate use of automatic exposure control in digital radiography. ESAK values reported in this study could further contribute to establishing local DRLs, regional DRLs and national DRLs.

PROPOSED NATIONAL DIAGNOSTIC REFERENCE LEVELS FOR STANDARD RADIOGRAPHIC X-RAY PROCEDURES IN SUDAN

This study aimed to calculate patient radiation doses for adults during the seven most commonly performed conventional X-ray procedures, and to propose national diagnostic reference levels (DRLs). A representative sample of patients from 29 hospitals was included. The entrance surface air kerma (ESAK) was calculated by measuring X-ray tube output and the corresponding technical and exposure factors for each patient. Third-quartile values of the mean ESAK distributions were proposed as DRL values. The DRLs in mGy were as follows: 0.6 for chest postero–anterior (PA), 3.5 for skull AP, 1.7 for skull lateral (LAT), 2.7 for abdominal, 2.6 for pelvic AP, 3.7 for lumbar spine AP and 8 for lumbar spine LAT. Compared with literature, the maximum percentages increase were in chest PA (329%) and skull AP (187%). Since the suggested DRL for chest PA was higher than literature values, dose optimization and a review of its value is recommended.

EVALUATION OF RADIATION DOSE FOR PATIENTS UNDERGOING MAMMOGRAPHY IN QATAR

In the absence of information on radiation doses in mammography in the Gulf countries, this study was designed to assess patient dose in terms of entrance surface air kerma and average glandular dose (AGD) in three mammography units in Qatar that covers 21% of all mammography systems in the country. The study of 150 patients involving 600 projections indicated that the average value of AGD in patients was 2.2 mGy for cranio-caudal and 2.5 mGy for mediolateral-oblique views, respectively. Dose assessment was also performed for polymethyl methacrylate phantoms of thicknesses, ranging from 20 to 80 mm. Comparing the patient dose values with several other publications in literature for full-field digital mammography, our values are typically higher, which can be likely attributed to the larger compressed breast thickness.

Eye lens radiation exposure in paediatric interventional treatment of retinoblastoma

Retinoblastoma represents 3% of cancers in children under fifteen years of age. The standard paediatric treatment for saving the affected eye is supraselective intra-arterial chemotherapy performed in interventional rooms. In order to address the radiation toxicity due to the angiography, the aim of this study was to determine the typical dose value corresponding to the procedure, estimate the paediatric patients’ eye lens dose and study the relationship between dose indicators and dose to the lens. An automatic dose management software was installed in two interventional rooms to obtain the distribution of the dose indicators kerma-area product and reference-point air kerma, getting a typical value 16 Gy·cm2 and 130 mGy, respectively (n = 35). The eye lens dose estimates were obtained with photoluminescent dosimeters placed on the patient’s eyelids. In the left eye, the entrance surface air kerma was 44.23 ± 2.66 mGy, and 12.72 ± 0.89 mGy in the right eye (n = 10). There was a positive correlation between dose to the lens per procedure and dose indicators, with R2 > 0.65 for both eyes. Based on this information, the threshold for the onset of radiation-induce cataracts (500 mGy) will be exceeded if the treatment is performed for more than 8 sessions.

Evaluation of Patient Radiation Doses in Skull Radiography

Purpose: Exposures to medical ionizing radiations elevate the risk of stochastic effects such as cancer in exposed individuals. It is of utmost importance to monitor the radiation doses delivered to patients and their optimization to reduce the associated radiation risks without limiting the diagnostic information. Methods: Entrance surface air kerma (ESAK) in a total of 64 adult patients in diagnostic digital Xray examinations were calculated and effective doses were estimated as per International Atomic Energy Agency (IAEA). Results: Median ESAK (mGy) and associated effective doses obtained were skull PA (0.45mGy, 0.005mSv) and skull Lat (0.25mGy, 0.003mSv). Results were compared with UK diagnostic reference levels and studies in India.Conclusion: The comparison revealed that the calculated ESAK and effective dose values wereless than the published literature. ESAK values reported in this study could further contribute toestablishing LDRLs.

A Study of Entrance Surface Air Kerma for Patients Undergoing Chest and Abdomen from Digital Radiography at Chulabhorn Hospital

Objective: The main purpose of this study was to investigate the typical dose for standard-sized patients in chest (posteroanterior; PA) and abdomen (anteroposterior; AP) digital radiography.Material and Methods: The air kerma was measured by the ionization chamber (Radical Corporation, model 10X6-6) in X-ray equipment manufactured by General Electric Healthcare Definium 8000 System for different kilovoltage peak (kVp) settings in each X-ray examination. The entrance surface air kerma (ESAK) was determined in 422 mediumsized patients in different projections: chest (PA) and abdomen (AP), according to the recommended protocol of the International Atomic Energy Agency Technical Report Series Number 457 (Technical Reports Series No. 457 “Dosimetry in Diagnostic Radiology: An International Code of Practice).Results: The mean entrance surface air kerma values for chest (PA) radiography in female and male patients were 0.08 milligray (mGy) and 0.09 mGy, respectively and for abdomen (AP) radiography for both genders were 0.98 mGy and 1.06 mGy, respectively.Conclusion: The mean entrance surface air kerma values of this study were less than the diagnostic reference levels from the IAEA 1996, Korea 2007, United Kingdom 2010 and Japan 2015, in all projections. Patient doses (ESAK) in chest (PA) and abdomen (AP) digital radiography at Chulabhorn Hospital were less than the other guidelines, because of the use of a high kVp technique for the chest and the automatic exposure control for the abdomen. Furthermore, Thai people are smaller than Westerners. We studied in digital radiography only that literally provides lowest radiation dose compares with screen film and computed radiography.