Irish X-ray departments demonstrate varying levels of adherence to European guidelines on good radiographic technique

Evaluation of patient radiation doses using DAP meter in diagnostic radiology procedures in Birjand, Iran

Background

The concept of diagnostic reference level (DRL) is considered a regular method to optimize radiation protection in diagnostic imaging system. The objective of implementing a reference level for dose is to produce high-quality images by applying a minimum dose of radiation based on the As Low As Reasonably Achievable (ALARA) principle. Therefore, this study aimed to evaluate the status of radiation protection in diagnostic radiology wards of educational hospitals affiliated with Birjand University of Medical Sciences.

Methods

This study was performed during a period of 11-months in the radiology center of the teaching hospital of Birjand University of Medical Sciences. The studied population included 477 patients who were referred to as clinically indicated x-ray radiography. In order to calculate local DRLs, dose area product (DAP) was measured by a DAP-meter (KERMAX-plus SPD, model 120–131 HS) for 11 devices at educational hospitals affiliated with Birjand University of Medical Sciences. The local DRL values was calculated as 75% of the mean DAP distribution for a specific patient trial at each center.

Results

DAP for Chest PA examination was gained to be in the range from 0.12 Gy.cm2 to 0.42 Gy.cm2 with an average value of 0.23 Gy.cm2 which is above the value of the reference level (0.12 Gy.cm2) for Chest PA. For Chest lateral the observed DAP was found to be in the range from 0.18 Gy.cm2 to 1.48 Gy.cm2 with an average value of 0.65 Gy.cm2 and are therefore twice the reference value (0.3 Gy.cm2). The higher DRL values (average = 2.73) are for lumbar spine lateral radiography. It is observed that the DRL values of chest PA, abdomen AP and Lumbar spine AP are much lower with the earlier studies.

Conclusions

The DRLs helps in understanding the current practices in radiographic examinations. Comparison with other hospitals, the scope of dose optimization and ultimately patient dose reduction in hospitals affiliated with Birjand University of Medical Sciences needs further investigation.

Impact of acquisition parameters on dose and image quality optimisation in paediatric pelvis radiography-A phantom study

PURPOSE

Within paediatric pelvis imaging there is a lack of systematic dose optimisation studies which consider age and size variations. This paper presents data from dose optimisation studies using digital radiography and pelvis phantoms representing 1 and 5-year-old children.

MATERIAL AND METHOD

Dose optimisation included assessments of image quality and radiation dose. Systematic variations using a factorial design for acquisition factors (kVp, mAs, source-detector distance [SDD] and filtration) were undertaken to acquire AP pelvis X-ray images. Perceptual image quality was assessed using a relative and absolute visual grading assessment (VGA) method. Radiation doses were measured by placing a dosimeter at the radiographic centring point on the surface of each phantom. Statistical analyses for determining the optimised parameters included main effects analysis.

RESULTS

Optimised techniques, with diagnostically acceptable image quality, for each paediatric age were: 1-year-old; 65 kVp, 2 mAs and 115 cm SDD, while, 5-year-old; 62 kVp, 8 mAs and 130 cm SDD both included 1 mm Al +0.1 mm Cu additional filtration. The main effect analysis identified situations in which image quality and radiation dose increased or decreased, except for kVp which showed peak image quality when exposure factors were increased. A set of minimum mAs values for producing diagnostic image quality were identified. Increasing SDD, unlike the other exposure factors, showed no trends for producing non-diagnostic images.

CONCLUSION

The factorial design provided an opportunity to identify suitable acquisition factors. This study provided a method for investigating the combined effect of multiple acquisition parameters on image quality and radiation dose for children.

New developed DR detector performs radiographs of hand, pelvic and premature chest anatomies at a lower radiation dose and/or a higher image quality

A newly developed Digital Radiography (DR) detector has smaller pixel size and higher fill factor than earlier detector models. These technical advantages should theoretically lead to higher sensitivity and higher spatial resolution, thus making dose reduction possible without scarifying image quality compared to previous DR detector versions. To examine whether the newly developed Canon CXDI-70C DR detector provides an improved image quality and/or allows for dose reductions in hand and pelvic bone examinations as well as premature chest examinations, compared to the previous (CXDI-55C) DR detector version. A total of 450 images of a technical Contrast-Detail phantom were imaged on a DR system employing various kVp and mAs settings, providing an objective image quality assessment. In addition, 450 images of anthropomorphic phantoms were taken and analyzed by three specialized radiologists using Visual Grading Analysis (VGA). The results from the technical phantom studies showed that the image quality expressed as IQFINV values was on average approximately 45 % higher with the CXDI-70C detector compared to the CXDI-55C detector. Consistently, the VGA results from the anatomical phantom studies indicated that by using the CXDI-70C detector, diagnostic image quality could be maintained at a dose reduction of in average 30 %, depending on anatomy and kVp level. This indicates that the CXDI-70C detector is significantly more sensitive than the previous model, and supports a better clinical image quality. By using the newly developed DR detector a significant dose reduction is possible while maintaining image quality.

Local reference dose evaluation in conventional radiography examinations in Iran

The goal of this study was to establish local diagnostic reference levels (LDRLs) for conventional radiography examinations in Sistan‐Baluchestan province of Iran, using dose area product (DAP) measurements followed by a comparison with international dose levels. DAP factor evaluation was carried out at eight radiography rooms in six public and one private health‐care centers. The study employed DAP, exposure, and demographic data (weight, age, height) for 1069 patients who presented for one of the 11 routine radiography examinations: chest (AP, PA, LAT), abdomen (AP), lumbar spine (AP, LAT), pelvis (AP), skull (AP/PA, LAT), and cervical spine (AP, LAT). The data were analyzed statistically and the minimum, median, mean, maximum, and third quartile DAP values were calculated. It was observed that LDRLs for chest PA (0.26 Gy.cm²) and chest LAT (0.66 Gy.cm²) projections were up to 136% and 113% higher, respectively, than their corresponding NRPB 2005 values. Other radiographic procedures had lower recommended reference doses compared with recently recommended national reference doses published in recent NRPB reports and other studies. Wide variations in DAP values and exposure parameters were observed for similar radiographic procedures between patients in different rooms and for different patients in the same room. These and other observations, such as poor radiographic techniques, high rate of radiographic reject/repeat, and lack of modern X‐ray machines and equipment, show that the need to carry out quality assurance programs is critical in Iran.

PACS numbers: 87.53.Bn, 87.59.B

Digital radiography: optimization of image quality and dose using multi-frequency software

BACKGROUND

New developments in processing of digital radiographs (DR), including multi-frequency processing (MFP), allow optimization of image quality and radiation dose. This is particularly promising in children as they are believed to be more sensitive to ionizing radiation than adults.

OBJECTIVE

To examine whether the use of MFP software reduces the radiation dose without compromising quality at DR of the femur in 5-year-old-equivalent anthropomorphic and technical phantoms.

MATERIALS AND METHODS

A total of 110 images of an anthropomorphic phantom were imaged on a DR system (Canon DR with CXDI-50 C detector and MLT[S] software) and analyzed by three pediatric radiologists using Visual Grading Analysis. In addition, 3,500 images taken of a technical contrast-detail phantom (CDRAD 2.0) provide an objective image-quality assessment.

RESULTS

Optimal image-quality was maintained at a dose reduction of 61% with MLT(S) optimized images. Even for images of diagnostic quality, MLT(S) provided a dose reduction of 88% as compared to the reference image. Software impact on image quality was found significant for dose (mAs), dynamic range dark region and frequency band.

CONCLUSION

By optimizing image processing parameters, a significant dose reduction is possible without significant loss of image quality.

Local diagnostic reference levels in standard X-ray examinations

The national diagnostic reference levels (NDRLs) form an efficient, concise and powerful standard for optimising radiation protection of a patient. However, in a large hospital, where many radiological departments are present, it is also possible to calculate and define lower dose values as local diagnostic reference levels (LDRLs). In our hospital there are eight radiological departments; in each of these, the entrance skin dose (ESD) distributions were determined for 10 standard projections (AP Abdomen, PA and LAT Chest, AP and LAT Lumbar Spine, LAT Lumbo-Sacral Joint, AP Pelvis, PA and LAT Skull and AP Urinary tract) and then the ESDs were compared with data previously published and with Italian NDRLs. All ESD values were below the corresponding NDRLs. The maximum/minimum ratio of ESDs ranged from 3.9 (LAT Skull) to 34.3 (AP Abdomen) for individual adult patients and from 2.1 (PA Skull) to 6.5 (Urinary tract) across the mean values of the radiological departments. Finally, it is shown how LDRLs can be proposed to obtain a more fully optimised radiation protection of patients.

Do CEC guidelines under-utilise the full potential of increasing kVp as a dose-reducing tool?

Increasing beam energies are well established as a radiation dose-reducing tool in diagnostic radiology. This has led to useful recommendations by the Commission of European Communities (CEC) for appropriate kVp values to be employed for a variety of examinations. The current work tests the hypothesis that kVp levels above those recommended by the CEC will result in reduced patient dose while still producing images of acceptable quality. This study explored the effect of a range of kVp levels within and above CEC recommendations for lumbar spine radiology. A phantom investigation facilitated selection of appropriate kVp levels for a patient study ( n=59): 81 kVp (CEC) and 96 kVp (non-CEC) for the AP projection and 90 kVp (CEC) and 102 kVp (non-CEC) for the lateral projection. Entrance surface and effective dose were calculated and image quality quantified using CEC image criteria and images of a detail contrast test tool. Data analysis demonstrated significant reduction in effective radiation dose for AP (29.9%) and lateral (24.6%) when a kVp value above the CEC range was employed compared with a kVp recommended by the CEC. Although significant reductions in total image quality of 18.3% and 10.1% for the antero-posterior and lateral projections, respectively, were noted, all patient images produced with all kVp values were considered acceptable by each member of the evaluative panel with all image criteria receiving a score of 2 (out of 3) or better. The psychophysical tests revealed minor non-significant reductions in visualisation scores. The current study demonstrated that kVp values outside the CEC recommended range offer reductions in dose while producing acceptable images. Practitioners should be guided, rather than constrained, by the CEC recommendations on good radiographic technique. The need for further work exploring the effect of higher energies on visualisation of subtle pathological lesions has been identified.

Viewing conditions for diagnostic images in three major Dublin hospitals: a comparison with WHO and CEC recommendations

Accurate interpretation of X-ray images is dependent on image viewing conditions. A recent study in Ireland demonstrated that even with the advent of digital departments the majority of images are still viewed using viewing boxes. This investigation aimed to measure average viewing box brightness, percentage uniformity and ambient light levels in radiology and radiographer viewing areas and wards within three major Dublin hospitals. The results were compared with published recommendations by the World Health Organization and Commission of the European Communities. Following analysis of more than 4650 measurements, it was shown that mean values for average viewing box brightness for all departments failed to achieve recommended levels. Only one third of areas met the most lenient guideline for percentage uniformity. Ambient lighting was shown to be unacceptable for ward areas. For all three parameters, radiology areas generally fared best, with wards gaining the poorest scores. Following a 3 min cleaning regimen of viewing boxes, the average brightness and percentage uniformity were improved in 100% and 80%, respectively, of viewing boxes, but average brightness values remained below recommended levels. The importance of comprehensive quality assurance programmes for viewing boxes has been highlighted so that visualization of images is not reduced to sub-optimal levels. The need for consistent and more informative recommendations has been emphasized.