Dose-area Product Values Research Articles

Correlation of acquisition time of C-arm cone-beam CT with image quality and radiation doseduring cerebral angiography using an anthropomorphic head phantom

Objective To investigate the influence of acquisition time of C-arm cone-beam CT on image quality and radiation dose of cerebral angiography.Methods C-arm cone-beam CT of cerebral angiography was performed on the male anthropomorphic head phantom,with DynaCT imaging mode and the acquisition time of 5 s,8 s and 20 s were used.Scanning was performed with each acquisition time for three times,and VR,MIP and MPR images were reconstructed.The attenuation values and their standard deviations of intracranial segment of the internal carotid artery (ICA),middle cerebral artery(MCA),anterior cerebral artery(ACA) and uniformed brain tissues were measured to calculate the image noise,signal to noise ratio (SNR) and contrast to noise ratio (CNR).We used the image noise,SNR and CNR as the objective standard to evaluate the image quality,and One-way ANOVA analysis of variance was used to assess the difference among them.A scale with scores 1 to 5 was used to rate the quality of the reconstructed image of ICA,MCA,ACA as a subjective evaluation,the difference among the evaluation scores were analyzed using Kruskal-wallis.We recorded the dose area product (DAP) of each acquisition time and the effective dose(ED) was calculated to assess the radiation dose,the difference among them were analyzed using One-way ANOVA analysis of variance.Results In C-arm cone beam CT 20 s imaging,the SNR of intracranial segment of the ICA,M CA,ACA were 22.29± 1.41,29.36 ±0.11 and 23.13 ±2.10 respectively,in 5 s imaging13.83 ±0.61,14.65 ±0.16 and 12.79±0.19 respectively,in 8 s imaging 14.92±0.96,18.97 ± 1.24 and 16.65 ±0.46 respectively,all the results showed a significant difference (F valued 58.19,327.29,52.74 respectively,all P valued＜0.01),the CNR of 20 s imaging were higher than that of 5 s and 8 s imaging,the Noise of ICA,MCA,ACA and the uniformed brain tissues of 20 s imaging were lower than that of 5 s and 8 s imaging,all the results showed significant difference (all P valued＜0.01).The subjective evaluation scores of VR imaging of 5 s,8 s and 20 s were 3.61 ±0.49,4.06±0.53,4.72±0.45 respectively,the scores of MIP imaging were 3.42±0.50,3.83±0.65 and 4.50±0.51 respectively,the scores of MPR imaging were 2.83±0.45,3.14±0.35 and 3.67±0.49 respectively,all the results showed significant difference (x2 valued 51.29,42.25 and 43.56 respectively,all P valued ＜0.01).The DAP values in C-arm cone beam CT 5 s,8 s and 20 s imaging were (9.11 ±0.18),(13.81±0.75)and(58.62±0.62)Gy· cm2,ED values were (0.91 ±0.02),(1.38±0.75)and(5.84± 0.11) mSv,all the results showed significant difference (F valued 3 720.30 and 3 654.85 respectively,all P valued＜0.01).Conclusion The image quality and radiation dose of C-arm cone-beam computed tomography are closely correlated with acquisition time. Key words: Tomography,X-ray computed ; Angiography ; Image quality ; Radiation dose

Diagnostic reference levels for panoramic and lateral cephalometric radiography of Korean children.

Pediatric patients are considered to be more radiosensitive than adults; thus, radiation dose evaluations based on radiologic examinations are particularly important in this population. However, no national diagnostic reference levels (DRLs) are available for pediatric patients in the Republic of Korea. Therefore, the aim of this study was to determine the usage of panoramic and cephalometric radiography under the National Health Insurance (NHI) scheme and to investigate the current DRLs for child panoramic and lateral cephalometric radiography using dose area product (DAP). DAP values were obtained for standard child exposure settings used routinely by dentists. Analysis was performed on data obtained from 28 panoramic and 20 cephalometric x-ray units for the DAP investigation. DRLs for child panoramic and cephalometric radiography were found to be 95.9 mGy cm and 121.3 mGy cm, respectively. These DRLs are higher than those recommended in the UK and Germany, which indicates that further effort is required to reduce pediatric doses in the Republic of Korea.

Impact of Hybrid Rooms with Image Fusion on Radiation Exposure during Endovascular Aortic Repair

To evaluate exposure to radiation during endovascular aneurysm repair (EVAR) performed with intraoperative guidance by preoperative computed tomographic angiogram fusion. All consecutive patients who underwent standard bifurcated (BIF) or thoracic (THO), and complex fenestrated (FEN) or branched (BR) EVAR were prospectively enrolled. Indirect dose-area product (DAP), fluoroscopy time (FT), and contrast medium volume were recorded. These data were compared with a previously published prospective EVAR cohort of 301 patients and to other literature. Direct DAP and peak skin dose were measured with radiochromic films. Results are expressed as median (interquartile range). From December 2012 to July 2013, 102 patients underwent standard (56.8%) or complex (43.2%) EVAR. The indirect DAP (Gy.cm(2)) was as follows: BIF 12.2 (8.7-19.9); THO 26.0 (11.9-34.9); FEN 43.7 (24.7-57.5); andBR 47.4 (37.2-108.2). The FT (min) was as follows: BIF 10.6 (9.1-14.7); THO 8.9 (6.0-10.5); FEN 30.7 (20.2-40.5); and BR 39.5 (34.8-51.6). The contrast medium volume (mL) was as follows: BIF 59.0 (50.0-75.0); THO 80.0 (50.0-100.0); FEN 105.0 (70.0-136.0); and BR 120.0 (100.0-170.0). When compared with a previous cohort, there was a significant reduction in DAP during BIF, FEN, and BR procedures, and a significant reduction of iodinated contrast volume during FEN and BR procedures. There was also a significant reduction in DAP during BIF procedures when compared with the literature (p<.01). DAP measurement on radiochromic films was strongly correlated with indirect DAP values (r(2)=.93). The exposure of patients and operators to radiation is significantly reduced by routine use of image fusion during standard and complex EVAR.

Patient radiation exposure during carotid artery stenting.

The main purpose of this study was to document the radiation doses to patients during carotid stenting. Fluoroscopy and exposure time, air kerma and dose-area product during carotid artery stenting in 160 patients were retrospectively reviewed with regard to body mass index, degree of stenosis and use of cerebral protection devices. Total air kerma was lower than 0.5 Gy in 80%, 0.5-1 Gy in 17% and higher than 1 Gy (maximum 1.2) in 3% of patients. Mean total dose-area product value for carotid stenting was 54 Gy cm(2). The mean air kerma (fluoroscopy), air kerma (exposure), total air kerma and dose-area product (fluoroscopy), dose-area product (exposure), total dose-area product of patients with body mass index within the range 25-29.9 and with body mass index >30 were significantly increased compared to that of patients with body mass index 18-24.9 (H = 40.2, df = 2; p = 0.0000001 and p = 0.000003, respectively). Carotid artery stenting is a relatively safe radiological procedure in terms of the radiation dose acquired by the patient. The main factors contributing to possible radiation overdosing are body mass index value and complexity of the carotid lesion. Proper preoperative planning in obese and complicated patients may reduce the fluoroscopy time and contribute to reduced dose acquisition.

Evaluation of organ and effective doses during paediatric barium meal examinations using PCXMC 2.0 Monte Carlo code.

Radiation protection and estimation of the radiological risk in paediatric radiology is essential due to children's significant radiosensitivity and their greater overall health risk. The purpose of this study was to estimate the organ and effective doses of paediatric patients undergoing barium meal (BM) examinations and also to evaluate the assessment of radiation Risk of Exposure Induced cancer Death (REID) to paediatric patients undergoing BM examinations. During the BM studies, fluoroscopy and multiple radiographs are involved. Since direct measurements of the dose in each organ are very difficult if possible at all, clinical measurements of dose-area products (DAPs) and the PCXMC 2.0 Monte Carlo code were involved. In clinical measurements, DAPs were assessed during examination of 51 patients undergoing BM examinations, separated almost equally in three age categories, neonatal, 1- and 5-y old. Organs receiving the highest amounts of radiation during BM examinations were as follows: the stomach (10.4, 10.2 and 11.1 mGy), the gall bladder (7.1, 5.8 and 5.2 mGy) and the spleen (7.5, 8.2 and 4.3 mGy). The three values in the brackets correspond to neonatal, 1- and 5-y-old patients, respectively. For all ages, the main contributors to the total organ and effective doses are the fluoroscopy projections. The average DAP values and absorbed doses to patient were higher for the left lateral projections. The REID was calculated for boys (4.8 × 10(-2), 3.0 × 10(-2) and 2.0 × 10(-2) %) for neonatal, 1- and 5-y old patients, respectively. The corresponding values for girl patients were calculated (12.1 × 10(-2), 5.5 × 10(-2) and 3.4 × 10(-2) %).

Evaluation of patient effective dose of neurovascular imaging protocols for C-arm cone-beam CT.

The purpose of this study was threefold: to estimate the organ doses and effective doses (EDs) for seven neurovascular imaging protocols, to study the effect of beam collimation on ED, and to derive protocol-specific dose-area product (DAP)-to-ED conversion factors. A cone-beam CT system was used to measure the organ doses for seven neurovascular imaging protocols. Two datasets were obtained: seven protocols without beam collimation (FOV, entire head) and four with beam collimation (FOV, from the base to the top of the skull). Measurements were performed on an adult male anthropomorphic phantom with 20 metal oxide semiconductor field-effect transistor (MOSFET) detectors placed in selected organs. The DAP values were recorded from the console. The EDs of five protocols were also estimated using Monte Carlo simulations software. The ED values were computed by multiplying measured organ doses to corresponding International Commission on Radiological Protection tissue-weighting factors. Without collimation, the EDs ranged from 0.16 to 1.6 mSv, and the DAP-to-ED conversion factors ranged from 0.035 to 0.076 mSv/Gy·cm(2). For the four protocols investigated with beam collimation, the ED was reduced by a factor of approximately 2, and the DAP-to-ED conversion factors were reduced by approximately 30%. For the five protocols also estimated with the Monte Carlo method, the estimated EDs were in agreement (< 20% deviation) with those determined by the MOSFET method. We have estimated ED for standard adult neuroimaging protocols in a 3D rotational angiography system. Our results provide a simple means of ED estimation using DAP console readings.

Panoral dose assessment: a comparative report of methodologies

National guidance from the Institute of Physics and Engineering in Medicine (IPEM Report 91) currently recommends that the patient dose for a panoral X-ray unit is measured as dose area product (DAP) replacing dose width product described in earlier guidance. An investigation identifying different methods available to carry out this measurement has been undertaken and errors in the methodologies analysed. It has been shown that there may be up to a 30 % variation in DAP measurement between methods. This paper recommends that where possible a DAP meter is used to measure the dose-area product from a panoral X-ray unit to give a direct DAP measurement. However, by using a solid-state dose measurement and film/ruler to calculate DAP the authors have established a conversion factor of 1.4. It is strongly recommended that wherever a DAP value is quoted the methodology used to obtain that value is also reported.

Local Reference Levels and Organ Doses From Pediatric Cardiac Interventional Procedures

Interventional cardiology (IC) procedures can be responsible for relatively high radiation doses compared to conventional radiology especially for young patients. The aim of this study was to assess current exposure levels in a French reference centre of pediatric IC. Dosimetric data including dose area product (DAP), fluoroscopy time (FT) and number of cine frame (NF) were analysed taking into account patient weight. Doses to the lungs, esophagus, breast and thyroid were evaluated using anthropomorphic phantoms and thermoluminescent dosimeters. Finally, effective doses (E) were calculated using DAP and conversion factors calculated with PCXMC 2.0 software. 801 IC procedures performed between 2010 and 2011 were analysed. Large variations were observed for DAP, FT and NF values for a given procedure and a given weight group. The assessment of organ doses showed high levels of dose to the lungs and esophagus especially in new-born babies. For diagnostic procedures, E varied from 0.3 to 23 mSv with a mean value of 4.8 mSv and for therapeutic procedures, values ranged from 0.1 to 48.4 mSv with a mean value of 7.3 mSv. The highest values were recorded for angioplasty procedures (mean 13 mSv, range 0.6-48.4 mSv). The increasing use of IC in pediatric population stresses the need of setting up reference levels and keeping doses to children as low as possible.

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

Conversion coefficients for the estimation of effective dose in cone-beam CT

PurposeTo determine the conversion coefficients (CCs) from the dose-area product (DAP) value to effective dose in cone-beam CT.Materials and MethodsA CBCT scanner with four fields of view (FOV) was used. Using two exposure settings of the adult standard and low dose exposure, DAP values were measured with a DAP meter in C mode (200mm×179 mm), P mode (154 mm×154 mm), I mode (102 mm×102 mm), and D mode (51 mm×51 mm). The effective doses were also investigated at each mode using an adult male head and neck phantom and thermoluminescent chips. Linear regressive analysis of the DAP and effective dose values was used to calculate the CCs for each CBCT examination.ResultsFor the C mode, the P mode at the maxilla, and the P mode at the mandible, the CCs were 0.049 µSv/mGycm2, 0.067 µSv/mGycm2, and 0.064 µSv/mGycm2, respectively. For the I mode, the CCs at the maxilla and mandible were 0.076 µSv/mGycm2 and 0.095 µSv/mGycm2, respectively. For the D mode at the maxillary incisors, molars, and mandibular molars, the CCs were 0.038 µSv/mGycm2, 0.041 µSv/mGycm2, and 0.146 µSv/mGycm2, respectively.ConclusionThe CCs in one CBCT device with fixed 80 kV ranged from 0.038 µSv/mGycm2 to 0.146 µSv/mGycm2 according to the imaging modes and irradiated region and were highest for the D mode at the mandibular molar.

Effective dose in percutaneous transhepatic biliary drainage examination using PCXMC2.0 and MCNP5 Monte Carlo codes

ObjectivesTo estimate the organ equivalent doses and the effective doses (E) in patient undergoing percutaneous transhepatic biliary drainage (PTBD) examinations, using the MCNP5 and PCXMC2 Monte Carlo-based codes. MethodsThe purpose of this study is to estimate the organ doses to patients undergoing PTBD examinations by clinical measurements and Monte Carlo simulation. Dose area products (DAP) values were assessed during examination of 43 patients undergoing PTBD examination separated into groups based on the gender and the dimensions and location of the beam. ResultsMonte Carlo simulation of photon transport in male and female mathematical phantoms was applied using the MCNP5 and PCXMC2 codes in order to estimate equivalent organ doses. Regarding the PTBD examination the organ receiving the maximum radiation dose was the lumbar spine. The mean calculated HT for the lumbar spine using the MCNP5 and PCXMC2 methods respectively, was 117.25 mSv and 131.7 mSv, in males. The corresponding doses were 139.45 mSv and 157.1 mSv respectively in females. The HT values for organs receiving considerable amounts of radiation during PTBD examinations were varied between 0.16% and 73.2% for the male group and between 1.10% and 77.6% for the female group. E in females and males using MCNP5 and PCXMC2.0 was 5.88 mSv and 6.77 mSv, and 4.93 mSv and 5.60 mSv. ConclusionThe doses remain high compared to other invasive operations in interventional radiology. There is a reasonable good coincidence between the MCNP5 and PCXMC2.0 calculation for most of the organs.

Niveles de referencia de dosis en radiología intervencionista

This article discusses the diagnostic reference levels for radiation exposure proposed by the International Commission on Radiological Protection (ICRP) to facilitate the application of the optimization criteria in diagnostic imaging and interventional procedures. These levels are normally established as the third quartile of the dose distributions to patients in an ample sample of centers and are supposed to be representative of good practice regarding patient exposure. In determining these levels, it is important to evaluate image quality as well to ensure that it is sufficient for diagnostic purposes. When the values for the dose received by patients are systematically higher or much lower than the reference levels, an investigation should determine whether corrective measures need to be applied. The European and Spanish regulations require the use of these reference values in quality assurance programs. For interventional procedures, the dose area product (or kerma area product) values are usually used as reference values together with the time under fluoroscopy and the total number of images acquired. The most modern imaging devices allow the value of the accumulated dose at the entrance to the patient to be calculated to optimize the distribution of the dose on the skin. The ICRP recommends that the complexity of interventional procedures be taken into account when establishing reference levels. In the future, diagnostic imaging departments will have automatic systems to manage patient dosimetric data; these systems will enable continuous dosage auditing and alerts about individual procedures that might involve doses several times above the reference values. This article also discusses aspects that need to be clarified to take better advantage of the reference levels in interventional procedures.

An evaluation of paediatric projection radiography in Ireland

PurposeThis study investigated common paediatric radiography examinations in Ireland and analysed any potential for improvement by considering compliance with requirements for justification, the range of doses delivered and potential Diagnostic Reference Levels, and technique approaches that enhance optimisation. MethodReferral information, Dose Area Product (DAP) dose, technique details and patient data were gathered from 568 paediatric examinations performed across several hospitals. The examinations were mobile infant chest (n = 66), chest (n = 266), abdomen (n = 96), lumbar spine (n = 14), full spine (n = 5), pelvis (n = 151) and skull (n = 28). Data were analysed to allow comment on the adequacy of justification, the range of doses being delivered and possible Diagnostic Reference Levels (DRLs), and the potential for optimisation of radiographic technique. Results/conclusionsResults indicate that the principle of justification is generally applied well in paediatric practice.Dose results indicate that age-related doses are generally comparable to published data, although dose variations exist within and between hospitals. Although differences between minimum and maximum DAP values were substantial, differences between the first and third quartile values were rarely greater than a factor of three. With regard to DRLs, age-related, 75th centile DAP values are presented for five paediatric X-ray examinations. While DAP DRLs stated as a function of age are a pragmatic approach to preliminary DRL values, size related DRLs are acknowledged as a better approach and the necessity of objective paediatric patient size measurement is emphasised.With regard to potential for optimisation, small samples limited analysis of factorial influences on DAP. However, trends indicate that objective consideration of kVp and mAs, careful collimation, and matching of exposure to baby weight in neonates and to measured patient depth in children could all contribute to better optimisation. These factors are all within the radiographer's control, thus highlighting the pivotal role of the radiographer in ensuring that the principle of optimisation is attained.

Evaluation of Maximum Patient Skin Dose Arising from Interventional Cardiology Using Thermoluminescence Dosimeter in Mashhad, Iran

Introduction The increasing practice of interventional fluoroscopy in diagnosis and treatment of cardiovascular disease has risen attention to improve radiation protection of patients and cardiologists in these relatively high dose techniques. Therefore, nowadays there is an emphasis on the measurement of radiation dose received by patients and cardiologists arising from the relevant procedures. Materials and Methods Maximum skin dose of 90 patients in two hospitals in Mashhad have been measured by a grid of 30 thermoluminescent dosimeters (TLDs). The X-ray units were Axiom Artis Siemens in both hospitals which were equipped with integrated dose area product (DAP) meters. The procedures were divided into two groups: diagnostic procedures (angiography and angiography with measurement of left or right ventricle and pulmonary artery) and therapeutic procedures (angioplasty with or without dilatation or stent and angiography with angioplasty). DAP value, fluoro time, and cumulative dose at Interventional Reference Point (CDIRP) were also registered for each procedure. Results The mean values of maximum skin dose (MSD) and DAP for diagnostic procedures were 68.51 mGy and 20.96 Gy.cm2, respectively and for therapeutic procedures 344.18 mGy and 70.94 Gy.cm2, respectively. A good correlation was found between MSD and DAP (R=0.88) but correlation between MSD and CDIRP was stronger (R=0.90). Conclusion MSD values did not exceed the 2000 mGy dose threshold for deterministic effects. The highest MSD obtained for diagnostic procedures was 229.40 mGy and for therapeutic procedures it was 820.50 mGy. The results show that CDIRP can be a fairly good estimate of MSD.

SU‐E‐I‐31: Moving From Image Intensifier to Flat Panel Detector in Interventional Radiology: Initial Experiences in a Tertiary Referral Center in India

Purpose: To audit radiation doses imparted to patients from interventional procedures performed in image intensifier and flat panel based interventional systems in a tertiary referral center in India. Methods: Forty cerebral angiographies were performed using Siemens Multistar top Image intensifier (II) and nine using Artis Zee flat panel detector (FPD) based angiographic systems. Dose area product (DAP) meter was used to measure dose imparted to patients during interventional procedures. Dose audit involved assessment of radiation dose, exposure parameters and image quality relevant to the examination. Copper filtration of 0.2mm was selected in the II based system, whereas 0.6mm copper filters were selected in FPD system. Subjective evaluation of image quality was performed by the interventionalists performing the procedure. Results: The mean DAP values for cerebral angiography using II and FPD systems were 127.5 (32.96 to 366.47) and 94.6 (26.31 to 228.68) Gy cm2 respectively. Dose reduction of about 26 % without sacrificing diagnostic information was achieved using FPD compared to the II system. Conclusion: It is necessary to orient the interventional staff to strictly adhere to low dose protocols so that inadvertent selection of preset protocols may impart high doses to patients. Further data collection on several other interventions is necessary in order set reference levels for Indian adult. At present using low dose protocols involving high filtration does not degrade image quality and are suggestive for use in FPD systems for the Indian adult.

Optimisation of patient dose for the horizontal beam technique in lateral lumbar spine radiographic examinations

In the emergency department, patients undergoing lateral lumbar spine radiography examinations are positioned either lying on their side on an X-ray table with the X-ray beam vertical or lying supine on a trolley with the X-ray beam horizontal. The measured dose-area product (DAP) values were found to differ significantly, typically 1.3 Gy cm(2) for those patients examined on the X-ray table and 2.7 Gy cm(2) for those on a trolley. This work investigates the reason for higher DAP values with the horizontal beam technique. The UK's current recommended national diagnostic reference level (NDRL) for the lateral lumbar spine is 2.5 Gy cm(2). The measurements of body diameter on volunteers showed that rotating the patients from their side to their back resulted in an increase in tissue thickness of between 2 cm and 9 cm for the lumbar region. X-ray absorption increases exponentially with increasing tissue thickness. An increase of 5 cm in body diameter for a lateral lumbar spine at 93 kV will increase the DAP by more than two-fold. Mathematical modelling and measurements with polymethyl methacrylate provided data to predict the tube potential increase necessary to reduce the DAP. For the horizontal beam technique, the tube potential was increased from 93 kV to 102 kV and the average DAP reduced to 2.3 Gy cm(2). Radiographic technique should be understood when auditing the dose. Tube potential must be increased to optimise the horizontal beam technique. The 2.5-Gy cm(2) NDRL relates predominantly to the more common vertical beam technique. Separate local diagnostic reference levels for horizontal and vertical beam techniques are recommended.

Barium Swallow Examination: Radiographer and radiologist compliance to National Diagnostic Reference Levels

ObjectivesCompliance to the National Diagnostic Reference Levels (NDRLs) ensures the radiation dose to patients is maintained at an acceptable level thereby reducing the element of risk and should not be exceeded wherever possible. The aim of the audit was to determine compliance to NDRLs for Dose Area Product (DAP) and fluoroscopy screening time in patients having Barium Swallow Examinations (BSE) between a specialist radiographer (SR) and radiologists. Methods157 BSEs DAP and screening time values were collected retrospectively over a five-month period. 34 specialist radiographer (SR)-led, 65 trainee radiologist (TR)-led and 52 consultant radiologist (CR)-led were included in the analysis. Six were excluded. These values were compared to the NDRL; both by individual and group mean value. Statistical analysis was mean, standard deviation and Mann–Whitney U to assess for significant differences between the operator groups. Results129 of 151 BSEs were below the NDRL for either DAP, screening time or both, equating to 85.4% compliance. For the three operator group BSE mean DAP values were <9 Gycm2 and mean screening time values <2.3 min. CR-led produced the lowest mean DAP value (2.69 Gycm2) and SR-led produced the highest mean DAP value (5.56 Gycm2). DAP values: no significant difference between SR-led and TR-led (p > 0.05); a significant difference was noted between SR-led and CR-led and TR-led and CR-led (p < 0.05). Screening time: no significant difference between screening time for TR-led and CR-led (p > 0.05) was shown; a significant difference was noted between SR-led and TR-led, and SR-led and CR-led (p < 0.05). ConclusionsThis audit shows good compliance with the NDRLs for both DAP and screening time.Differences were demonstrated for both DAP values and screening time between the different operator groups. The highest mean values for both DAP and screening time were produced by examinations performed by the newly introduced specialist radiographer-led service.

An investigation of patient doses during coronary interventional procedures in China

The purpose of this study was to estimate patient doses during coronary angiography (CA) and different complex percutaneous transluminal coronary angioplasty (PTCA) procedures in China. Consecutive 290 patients (90 CA, 200 PTCA) with known or suspected coronary artery disease were enrolled prospectively into six groups. Differences in patient doses among the six groups were analysed, and the patient doses observed in this study were compared with the recent literature. The median dose area product values were 27.0 and 195.0 Gy cm(2) for CA and PTCA, respectively. The patient doses during CA were similar to those reported by other authors, while those during PTCA were higher. The differences in radiation doses depended on the complexity of the procedures. Enhanced knowledge of radiation doses may help cardiologists implement radiation-sparing procedures to minimise patient exposure.

Feasibility Study of Needle Placement in Percutaneous Vertebroplasty: Cone-Beam Computed Tomography Guidance Versus Conventional Fluoroscopy

To investigate the accuracy, procedure time, fluoroscopy time, and dose area product (DAP) of needle placement during percutaneous vertebroplasty (PVP) using cone-beam computed tomography (CBCT) guidance versus fluoroscopy. On 4 spine phantoms with 11 vertebrae (Th7-L5), 4 interventional radiologists (2 experienced with CBCT guidance and two inexperienced) punctured all vertebrae in a bipedicular fashion. Each side was randomization to either CBCT guidance or fluoroscopy. CBCT guidance is a sophisticated needle guidance technique using CBCT, navigation software, and real-time fluoroscopy. The placement of the needle had to be to a specific target point. After the procedure, CBCT was performed to determine the accuracy, procedure time, fluoroscopy time, and DAP. Analysis of the difference between methods and experience level was performed. Mean accuracy using CBCT guidance (2.61mm) was significantly better compared with fluoroscopy (5.86mm) (p<0.0001). Procedure time was in favor of fluoroscopy (7.39 vs. 10.13min; p=0.001). Fluoroscopy time during CBCT guidance was lower, but this difference is not significant (71.3 vs. 95.8s; p=0.056). DAP values for CBCT guidance and fluoroscopy were 514 and 174mGy cm(2), respectively (p<0.0001). There was a significant difference in favor of experienced CBCT guidance users regarding accuracy for both methods, procedure time of CBCT guidance, and added DAP values for fluoroscopy. CBCT guidance allows users to perform PVP more accurately at the cost of higher patient dose and longer procedure time. Because procedural complications (e.g., cement leakage) are related to the accuracy of the needle placement, improvements in accuracy are clinically relevant. Training in CBCT guidance is essential to achieve greater accuracy and decrease procedure time/dose values.

A preliminary study to determine the diagnostic reference level using dose-area product for limited-area cone beam CT.

The aim of this study was to measure the dose-area product (DAP) of limited-area cone beam CT (CBCT) units used by dental offices, and to evaluate the rationale of the DAP with an aid of optically stimulated luminescence (OSL) dosemeter in measuring radiation dose. The DAPs of 21 CBCT units used in the dental offices of Tokyo and the surrounding areas from five different manufacturers were measured using OSL nanoDot dosemeter. An assembly of OSL dosemeters with an X-ray film was exposed by CBCT units at exposure parameters commonly used in each dental office. DAP values were then calculated as expressed in mGy cm(2). DAP values ranged from 126.7 mGy cm(2) to 1476.9 mGy cm(2), depending on the units used. OSL dosemeter coupled with film can be utilized for a large-scale study to measure DAP. The DAP values for individual CBCT units depend not only on the field of view, but also on the exposure parameters adapted by the dental offices.