An education and training programme for radiological institutes: impact on the reduction of the CT radiation dose

Radiation dose and image quality in pediatric bitewing imaging

INTRODUCTION

Bitewing examinations are used to examine the pediatric dental status. The aim of this study was to compare the image quality and radiation dose between two different X-ray systems used for pediatric bitewing imaging.

MATERIALS AND METHODS

Data were obtained from both pediatric in vivo bitewing studies and phantom studies. Two X-ray systems were used: Trophy CCX digital (TCCX) (Trophy Irix 70, Marne-la-Vallee, France) and Planmeca Pro X (PPX) (Planmeca, Helsinki, Finland). An Unfors dosimeter (Unfors EDD-30, Billdal, Sweden) was used to measure the skin dose. Image quality was evaluated blindly by three experienced dentists using a Likert scale of 1-5 based on the visual representation of the anatomical structures with emphasis on caries.

RESULTS

The highest scoring in vivo bitewing images were obtained with TCCX, but the skin dose was 36% higher (mean 3029 ± 613 μGy) and 113% higher (mean 1364 ± 276 μGy) with standard settings than with compared to PPX. The evaluation of image quality revealed a higher median value for all ratings of TCCX compared to PPX for both the patient and phantom studies, meaning that the images of TCCX were rated as higher quality than the images from PPX. No correlation was found between the median score and the skin dose or between the median score and the exposure times.

CONCLUSION

A significant difference in radiation dose and image quality was found between TCCX and PPX in bitewing imaging. TCCX generally produced higher doses and better graded images, although all images were suitable for diagnosis.

The Importance of Radiation Protection Education and Training for Medical Professionals of All Specialties

The article is part of the series of articles on radiation protection. You can find further articles in the special section of the CVIR issue. Lately, more advanced techniques have been introduced in medical imaging expanding the diagnostic and therapeutic applications of ionizing radiation. Among the various strategies that have been proposed for the management of radiation exposure, education and training seem to have a strong impact on radiation protection and dose reduction. However, according to several studies, medical professionals appear to lack knowledge on basic radiation protection aspects. Therefore, the establishment of an accreditation and certification system in radiation protection for all medical professionals employing ionizing radiation is considered as high priority. The purpose of this review article is to highlight the importance of education and training in radiation protection, provide recommendations for an effective educational program and propose an educational program structure for the different medical specialties.

A questionnaire survey on radiation protection among 282 medical staff from 26 endoscopy-fluoroscopy departments in Japan

BACKGROUND AND AIMS

It is essential for endoscopists, technologists, and nurses to understand radiation protection. However, protective equipment usage is still low, and there is little awareness of radiation protection in practice.

METHODS

We conducted a questionnaire survey on radiation protection from January to February 2020. The participants were medical staff, including medical doctors, nurses, and radiological and endoscopy technician in endoscopy-fluoroscopy departments. The questionnaire included 14 multiple-choice questions divided among three parts: background, equipment, and knowledge.

RESULTS

We surveyed a total of 282 subjects from 26 institutions. There were 168 medical doctors (60%), 90 nurses (32%), and 24 technologists (9%). Although almost all staff members (99%) always wore a lead apron, only a few wore a thyroid collar (32%) and lead glasses (21%). The rate of wearing a radiation dosimeter was insufficient (69%), especially among doctors (52%). A few subjects knew the radiation exposure dose of each procedure (15%), and slightly over half had attended lectures on radiation protection (64%) and knew about the three principles of radiation protection (59%). Protection adherence did not differ by years of experience, knowledge of fluoroscopy, awareness of radiation exposure doses, or attendance at basic lectures on radiation protection. However, medical doctors who were aware of the radiation exposure dose of each procedure were significantly more likely to wear dosimeters than those who were not (p = 0.0008).

CONCLUSION

Medical staff in endoscopy departments in Japan do not have enough radiation protection equipment or education.

EYE LENS DOSE OPTIMIZATION THROUGH GANTRY TILTING IN BRAIN CT SCAN: THE POTENTIAL EFFECT OF THE RADIOLOGICAL TECHNOLOGISTS' TRAINING

This study was designed to evaluate the effect of the radiological technologists' training on optimising the eye lens dose in brain computed tomography (CT) examinations. The lens dose of 50 adult patients was measured using thermoluminescent dosimeters before and after technologists' training. Dose values of lenses, dose length product (DLP), volumetric CT dose index (CTDIvol) as well as image quality in terms of quantitative (contrast to noise ratio and signal to noise ratio) and subjective (artefact) parameters were compared before and after training. Lens dose values were 31.57 ± 9.84 mGy and 5.36 ± 1.53 mGy before and after training, respectively, which was reduced by ~83% (p < 0.05). The values of DLP, CTDIvol and image quality parameters were not significantly different (p > 0.05) and all images were diagnostically acceptable. Excluding the orbits from the scanning range is an efficient approach to optimize the lens dose; the training of the technologists has also a pivotal role in dose reducing.

Transatlantic Comparison of CT Radiation Doses in the Era of Radiation Dose-Tracking Software

OBJECTIVE

The purpose of this study is to compare diagnostic reference levels from a local European CT dose registry, using radiation-tracking software from a large patient sample, with preexisting European and North American diagnostic reference levels.

MATERIALS AND METHODS

Data (n = 43,761 CT scans obtained over the course of 2 years) for the European local CT dose registry were obtained from eight CT scanners at six institutions. Means, medians, and interquartile ranges of volumetric CT dose index (CTDI_vol), dose-length product (DLP), size-specific dose estimate, and effective dose values for CT examinations of the head, paranasal sinuses, thorax, pulmonary angiogram, abdomen-pelvis, renal-colic, thorax-abdomen-pelvis, and thoracoabdominal angiogram were obtained using radiation-tracking software. Metrics from this registry were compared with diagnostic reference levels from Canada and California (published in 2015), the American College of Radiology (ACR) dose index registry (2015), and national diagnostic reference levels from local CT dose registries in Switzerland (2010), the United Kingdom (2011), and Portugal (2015).

RESULTS

Our local registry had a lower 75th percentile CTDI_vol for all protocols than did the individual internationally sourced data. Compared with our study, the ACR dose index registry had higher 75th percentile CTDI_vol values by 55% for head, 240% for thorax, 28% for abdomen-pelvis, 42% for thorax-abdomen-pelvis, 128% for pulmonary angiogram, 138% for renal-colic, and 58% for paranasal sinus studies.

CONCLUSION

Our local registry had lower diagnostic reference level values than did existing European and North American diagnostic reference levels. Automated radiation-tracking software could be used to establish and update existing diagnostic reference levels because they are capable of analyzing large datasets meaningfully.

Radiation dose levels in pediatric chest CT: experience in 499 children evaluated with dual-source single-energy CT

BACKGROUND

The availability of dual-source technology has introduced the possibility of scanning children at lower kVp with a high-pitch mode, combining high-speed data acquisition and high temporal resolution.

OBJECTIVE

To establish the radiation dose levels of dual-source, single-energy chest CT examinations in children.

MATERIALS AND METHODS

We retrospectively recorded the dose-length product (DLP) of 499 consecutive examinations obtained in children <50 kg, divided into five weight groups: group 1 (<10 kg, n = 129); group 2 (10-20 kg, n = 176); group 3 (20-30 kg, n = 99), group 4 (30-40 kg, n = 58) and group 5 (40-49 kg, n = 37). All CT examinations were performed with high temporal resolution (75 ms), a high-pitch mode and a weight-adapted selection of the milliamperage.

RESULTS

CT examinations were obtained at 80 kVp with a milliamperage ranging between 40 mAs and 90 mAs, and a pitch of 2.0 (n = 162; 32.5%) or 3.0 (n = 337; 67.5%). The mean duration of data acquisition was 522.8 ± 192.0 ms (interquartile range 390 to 610; median 490). In the study population, the mean CT dose index volume (CTDIvol₃₂) was 0.83 mGy (standard deviation [SD] 0.20 mGy; interquartile range 0.72 to 0.94; median 0.78); the mean DLP₃₂ was 21.4 mGy.cm (SD 9.1 mGy.cm; interquartile range 15 to 25; median 19.0); and the mean size-specific dose estimate (SSDE) was 1.7 mGy (SD 0.4 mGy; interquartile range 1.5 to 1.9; median 1.7). The DLP₃₂, CTDI_vol32 and SSDE were found to be statistically significant in the five weight categories (P < 0.0001).

CONCLUSION

This study establishes the radiation dose levels for dual-source, single-kVp chest CT from a single center. In the five weight categories, the median values varied 15-37 mGy.cm for the DLP₃₂, 0.78-1.25 mGy for the CTDI_vol32 and 1.6-2.1 mGy for the SSDE.

Current utilization of cardiac computed tomography in mainland China: A national survey

BACKGROUND

Surveys that describe the utilization of cardiac CT are available for the United States, Germany, and Taiwan, but not mainland China.

OBJECTIVES

To analyze the clinical utilization of cardiac CT in mainland China.

METHODS

A 25-item questionnaire was created and 240 tertiary hospitals were randomly selected to participate. Survey data were collected and confirmed by email as well as phone interviews.

RESULTS

In total, 237 (99%) hospitals consented to this survey, but 85 were excluded because of lack of cardiac CT patient volume or advanced technology. Finally, 152 (64%) questionnaires were available for analysis. Median patient volume was 1,037 patients (range: 150-8,072) annually. The most common clinical indications for coronary CT angiography were exclusion of coronary artery disease in patients with low to intermediate pretest likelihood, asymptomatic individuals with cardiovascular risk factors, and follow-up after coronary bypass grafting. The median heart rate threshold for beta blocker administration was >70 beats/min; most centers (86%) used sublingual nitroglycerin. Prospectively ECG triggered acquisition was the predominant technique in 44% of hospitals. Most (59%) providers adjusted the tube current to the body mass, but few (16%) adjusted the contrast injection rate. Per case, the mean examination duration was 14.2 min; post-processing time 13.6 min; and reporting time 18.0 min.

CONCLUSIONS

Cardiac CT is widely established in clinical practice in mainland China but there is a need for more uniform standards regarding performance and clinical utilization.

Readjustment of abdominal computed tomography protocols in a university hospital: impact on radiation dose

Objective

To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters.

Materials and Methods

Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A – 551 studies) and three months after (group B – 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDI_vol per phase, mean DLP per phase, and mean DLP per scan.

Results

A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDI_vol per phase, DLP per phase and DLP per scan (p < 0.001).

Conclusion

The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans.

Effect of staff training on radiation dose in pediatric CT

OBJECTIVE

To evaluate the efficacy of staff training on radiation doses applied in pediatric CT scans.

METHODS

Pediatric patient doses from five CT scanners before (1426 scans) and after staff training (2566 scans) were compared statistically. Examinations included cranial CT (CCT), thoracic, abdomen-pelvis, and trunk scans. Dose length products (DLPs) per series were extracted from CT dose reports archived in the PACS.

RESULTS

A pooled analysis of non-traumatic scans revealed a statistically significant reduction in the dose for cranial, thoracic, and abdomen/pelvis scans (p<0.01). This trend could be demonstrated also for trunk scans, however, significance could not be established due to low patient frequencies (p>0.05). The percentage of scans performed with DLPs exceeding the German DRLs was reduced from 41% to 7% (CCT), 19% to 5% (thorax-CT), from 9% to zero (abdominal-pelvis CT), and 26% to zero (trunk; DRL taken as summed DRLs for thorax plus abdomen-pelvis, reduced by 20% accounting for overlap). Comparison with Austrian DRLs - available only for CCT and thorax CT - showed a reduction from 21% to 3% (CCT), and 15 to 2% (thorax CT).

CONCLUSIONS

Staff training together with application of DRLs provide an efficient approach for optimizing radiation dose in pediatric CT practice.

How are we protecting ourselves from radiation exposure? A nationwide survey

PURPOSE

We performed a nationwide survey of Brazilian urologists to study behaviors toward radiation exposure and the use of protective and monitoring equipment.

METHODS

A 13-question e-mail questionnaire was sent to 4,526 Brazilian urologists; the questions addressed demographic characteristics, radiation exposure, and the utilization of shielding devices and dosimeters. The reasons why these devices were not used were also investigated.

RESULTS

A total of 332 completed questionnaires were analyzed (7.3 %); the median age of the respondents was 43.3 ± 10.8 years. Lead aprons and thyroid protection are utilized in every procedure by 84.4 and 53.89 % of respondents, respectively. Protective eyeglasses are never used by 72.12 % of the respondents. Older urologists were more likely not to use adequate protection. Of the urologists who responded, 76.42 % never use dosimeters.

CONCLUSION

This study shows an unsatisfactory utilization of radiation-shielding devices and dosimeters, revealing a low compliance to the as low as reasonably achievable principle among Brazilian urologists.

Validation of a low dose simulation technique for computed tomography images

PURPOSE

Evaluation of a new software tool for generation of simulated low-dose computed tomography (CT) images from an original higher dose scan.

MATERIALS AND METHODS

Original CT scan data (100 mAs, 80 mAs, 60 mAs, 40 mAs, 20 mAs, 10 mAs; 100 kV) of a swine were acquired (approved by the regional governmental commission for animal protection). Simulations of CT acquisition with a lower dose (simulated 10-80 mAs) were calculated using a low-dose simulation algorithm. The simulations were compared to the originals of the same dose level with regard to density values and image noise. Four radiologists assessed the realistic visual appearance of the simulated images.

RESULTS

Image characteristics of simulated low dose scans were similar to the originals. Mean overall discrepancy of image noise and CT values was -1.2% (range -9% to 3.2%) and -0.2% (range -8.2% to 3.2%), respectively, p>0.05. Confidence intervals of discrepancies ranged between 0.9-10.2 HU (noise) and 1.9-13.4 HU (CT values), without significant differences (p>0.05). Subjective observer evaluation of image appearance showed no visually detectable difference.

CONCLUSION

Simulated low dose images showed excellent agreement with the originals concerning image noise, CT density values, and subjective assessment of the visual appearance of the simulated images. An authentic low-dose simulation opens up opportunity with regard to staff education, protocol optimization and introduction of new techniques.

Pediatric computed tomography imaging guideline

The use of computed tomography (CT) in pediatric diagnostic imaging is demanding generally, but when coupled with an awareness to limit the radiation dose associated with this imaging modality, the procedure becomes challenging. Although new techniques have been developed in line with the introduction of faster multidetector computed tomography (MDCT) scanners to aid radiation reduction, it still remains the responsibility of the clinical practitioner to ensure each examination request is justified and the scanning protocol and parameters selected are optimized to the individual patient's requirement. It is the purpose of this article to outline the basic principle of CT radiation dose optimization based on modification of scanning parameters and application of different imaging techniques.

Real practice radiation dose and dosimetric impact of radiological staff training in body CT examinations

OBJECTIVES

To evaluate the radiation dose of the main body CT examinations performed routinely in four regional diagnostic centres, the specific contribution of radiologists and technologists in determining CT dose levels, and the role of radiological staff training in reducing radiation doses.

METHODS

We retrospectively evaluated the radiation dose in terms of dose-length product (DLP) values of 2,016 adult CT examinations (chest, abdomen-pelvis, and whole body) collected in four different centres in our region. DLP values for contrast-unenhanced and contrast-enhanced CT examinations performed at each centre were compared for each anatomical area. DLP values for CT examinations performed before and after radiological staff training were also compared.

RESULTS

DLP values for the same CT examinations varied among centres depending on radiologists' preferences, variable training of technologists, and diversified CT image acquisition protocols. A specific training programme designed for the radiological staff led to a significant overall reduction of DLP values, along with a significant reduction of DLP variability.

CONCLUSIONS

Training of both radiologists and technologists plays a key role in optimising CT acquisition procedures and lowering the radiation dose delivered to patients.

MAIN MESSAGES

• The effective dose for similar CT examinations varies significantly among radiological centres. • Staff training can significantly reduce and harmonise the radiation dose. • Training of radiologists and technologists is key to optimise CT acquisition protocols.

Rationale use of unenhanced multi-detector CT (CT KUB) in evaluation of suspected renal colic

OBJECTIVE

To assess the yield of non-contrast enhanced CT (CT KUB) across different ordering specialties and need of developing an algorithm for its rationale use.

MATERIALS AND METHODS

We retrospectively reviewed 1550 consecutive CT KUB studies requested for suspected renal colic carried out at a single institution in a calendar year. The data was analyzed for demographic characteristics, referring clinician and final diagnosis. Only patients with CT as primary imaging for clinically suspected reno-ureteral colic were included. Departments ordering these CT KUB examinations were divided into three divisions: Urologist, emergency room (ER) physician and others.

RESULTS

Of 1550 CT KUB performed in the study period 766 met the inclusion criteria. Urologists (57%), followed by ER physicians (30%) mostly ordered the examination. The overall positive yield for urolithiasis was 64% (n = 490), rate of incidental/alternate findings was 15% (n = 116) and 21% (n = 160) were negative. Urologist has the highest positive yield of 67.4% (n = 295) followed by ER physician 67% (n = 152) and others 42.5% (n = 43); p < 0.001. Rate of incidental/alternate findings was highest in CT ordered by other specialties 23.7% (n = 24) followed by ER physician 17.6% (n = 40) and urologist 11.8% (n = 52); p = 0.005.

CONCLUSION

There is statistically significant difference of yield across specialties. CT KUB as an initial imaging modality for suspected urolithiasis should be ordered in consultation with the urologist and ER physicians. Tool of good history taking and physical examination has proved to be essential steps in algorithm of ordering CT KUB, which can avoid unnecessary radiation exposure.

Radiation exposure--do urologists take it seriously in Turkey?

PURPOSE

A questionnaire was administered to urologists to evaluate attitudes and behaviors about protection from radiation exposure during fluoroscopy guided endourological procedures.

MATERIALS AND METHODS

The questionnaire was e-mailed to 1,482 urologists, including urology residents, specialists and urologists holding all levels of academic degrees, between May and June 2011. The questionnaire administered to study participants was composed of demographic questions, and questions on radiation exposure frequency, and the use of dosimeters and flexible protective clothes. If a respondent reported not using dosimeters or protective clothes, additional questions asked for the reason.

RESULTS

Of the 1,482 questionnaires 394 (26.58%) were returned, of which 363 had completed answers. A total of 307 physicians (84.58%) were exposed to ionizing radiation, of whom 79.61% stated that they perform percutaneous nephrolithotomy at the clinic. Fluoroscopy guidance was the initial choice of 96.19% of urologists during percutaneous nephrolithotomy. Despite the common use of lead aprons (75.24%) most urologists did not use dosimeters (73.94%), eyeglasses (76.95%) or gloves (66.67%) while 46.44% always used thyroid shields during fluoroscopy. When asked why they did not use protective clothing, the most common answers were that protective clothes are not ergonomic and not practical.

CONCLUSIONS

Results clearly highlight the lack of use of ionizing radiation protection devices and dosimeters during commonly performed fluoroscopy guided endourological procedures among urologists in Turkey.