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1.  Optimisation of Radiation Exposure to Gastroenterologists and Patients during Therapeutic ERCP 
This study intended to optimize the radiation doses for gastroenterologists and patients during therapeutic endoscopic retrograde cholangiopancreatography (ERCP) and to compare the doses based on available data obtained by other researchers. A total of 153 patients were studied in two Gastroenterology Departments, (group A, 111; group B, 42). Thermoluminescent dosimeters (TLD) were used to measure the staff and patients entrance surface air kerma (ESAK) at different body sites. The mean ESAK and effective doses per procedure were estimated to be 68.75 mGy and 2.74 mSv, respectively. Staff was exposed to a heterogonous doses. The third examiner (trainee) was exposed to a high dose compared with other examiners because no shield was located to protect him from stray radiation. Patients and examiners doses were lower compared to the lowest values found in previous studies taking into consideration the heterogeneity of patients and equipment. Staff doses during ERCP are within the safety limit in the light of the current practice.
PMCID: PMC3622381  PMID: 23589714
2.  Radiation exposure to personnel performing endoscopic retrograde cholangiopancreatography 
Postgraduate Medical Journal  2005;81(960):660-662.
Background: Endoscopic retrograde cholangiopancreatography (ERCP) relies on the use of ionising radiation but risks to operator and patient associated with radiation exposure are unclear. The aim of this prospective study was to estimate the radiation dose received by personnel performing fluoroscopic endoscopic procedures, mainly ERCP.
Methods: Consecutive procedures over a two month period were included. The use of thermoluminescent dosimeters to measure radiation exposure to the abdomen, thyroid gland, and hands of the operator permitted an estimation of the annual whole body effective dose equivalent.
Results: During the study period 66 procedures (61 ERCP) were performed and the estimated annual whole body effective dose equivalent received by consultant operators ranged between 3.35 and 5.87 mSv. These values are similar to those received by patients undergoing barium studies and equate to an estimated additional lifetime fatal cancer risk between 1 in 7000 and 1 in 3500. While within legal safety limits for radiation exposure to personnel, these doses are higher than values deemed acceptable for the general public.
Conclusions: It is suggested that personnel as well as patients may be exposed to significant values of radiation during ERCP. The study emphasises the need to carefully assess the indication for, and to use measures that minimise radiation exposure during any fluoroscopic procedure.
PMCID: PMC1743365  PMID: 16210465
3.  Safety of endoscopic retrograde cholangiopancreatography in pregnancy: Fluoroscopy time and fetal exposure, does it matter? 
AIM: To estimate the fetal radiation exposure using thermoluminescent dosimeters (TLD’s) in pregnant patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) and assess its relevance.
METHODS: Data on thirty-five therapeutic ERCPs conducted in pregnant patients from 2001 to 2009 were retrieved from a prospective database. Techniques to minimize fluoroscopy time were implemented and the fluoroscopy times captured. TLD’s were placed on the mother to estimate the fetal radiation exposure and the results were compared to the maximum allowed dose of radiation to the fetus [0.005 gray (Gy)]. Obstetrics consultations were obtained and the fetus was monitored before and after the ERCP. Fluoroscopy was performed at 75 kVp. ERCP was performed with the patients supine by dedicated biliary endoscopists performing more than 500 cases a year.
RESULTS: A total of 35 pregnant patients underwent ERCP and biliary sphincterotomy (14 in first trimester, 11 in second trimester, and 10 in third trimester). Mean maternal age was 25 years (range 16-37 years) and mean gestational age was 18.9 wk (range 4-35 wk). Mean fluoroscopy time was 0.15 min (range 0-1 min). For 23 women, the estimated fetal radiation exposure was almost negligible (< 0.0001 Gy) while for 8 women, it was within the 0.0001-0.0002 Gy range. Three women had an estimated fetal radiation exposure between 0.0002 and 0.0005 Gy and 1 woman had an estimated fetal radiation exposure greater than 0.0005 Gy. Complications included 2 post-sphincterotomy bleeds, 2 post-ERCP pancreatitis, and 1 fatal acute respiratory distress syndrome. One patient developed cholecystitis 2 d after ERCP.
CONCLUSION: ERCP with modified techniques is safe during pregnancy, and estimating the fetal radiation exposure from the fluoroscopy time or measuring it via TLD’s is unnecessary.
PMCID: PMC3627836  PMID: 23596536
Endoscopic retrograde cholangiopancreatography; Pregnancy; Fluoroscopy; Fetal exposure; Pancreaticobiliary disease
4.  Radiation Dose to Newborns in Neonatal Intensive Care Units 
Iranian Journal of Radiology  2012;9(3):145-149.
With the increase of X-ray use for medical diagnostic purposes, knowing the given doses is necessary in patients for comparison with reference levels. The concept of reference doses or diagnostic reference levels (DRLs) has been developed as a practical aid in the optimization of patient protection in diagnostic radiology.
To assess the radiation doses to neonates from diagnostic radiography (chest and abdomen). This study has been carried out in the neonatal intensive care unit of a province in Iran.
Patients and Methods
Entrance surface dose (ESD) was measured directly with thermoluminescent dosimeters (TLDs). The population included 195 neonates admitted for a diagnostic radiography, in eight NICUs of different hospital types.
The mean ESD for chest and abdomen examinations were 76.3 µGy and 61.5 µGy, respectively. DRLs for neonate in NICUs of the province were 88 µGy for chest and 98 µGy for abdomen examinations that were slightly higher than other studies. Risk of death due to radiation cancer incidence of abdomens examination was equal to 1.88 × 10 -6 for male and 4.43 × 10 -6 for female. For chest X-ray, it was equal to 2.54 × 10 -6 for male and 1.17 × 10 -5 for female patients.
DRLs for neonates in our province were slightly higher than values reported by other studies such as European national diagnostic reference levels and the NRPB reference dose. The main reason was related to using a high mAs and a low kVp applied in most departments and also a low focus film distance (FFD). Probably lack of collimation also affected some exams in the NICUs.
PMCID: PMC3522370  PMID: 23329980
Intensive Care Units; Neonatal; Radiation Dosimetry
5.  Radiation dose to patients during endoscopic retrograde cholangiopancreatography 
Endoscopic retrograde cholangiopancreatography (ERCP) is an important tool for the diagnosis and treatment of the hepatobiliary system. The use of fluoroscopy to aid ERCP places both the patient and the endoscopy staff at risk of radiation-induced injury. Radiation dose to patients during ERCP depends on many factors, and the endoscopist cannot control some variables, such as patient size, procedure type, or fluoroscopic equipment used. Previous reports have demonstrated a linear relationship between radiation dose and fluoroscopy duration. When fluoroscopy is used to assist ERCP, the shortest fluoroscopy time possible is recommended. Pulsed fluoroscopy and monitoring the length of fluoroscopy have been suggested for an overall reduction in both radiation exposure and fluoroscopy times. Fluoroscopy time is shorter when ERCP is performed by an endoscopist who has many years experience of performing ERCP and carried out a large number of ERCPs in the preceding year. In general, radiation exposure is greater during therapeutic ERCP than during diagnostic ERCP. Factors associated with prolonged fluoroscopy have been delineated recently, but these have not been validated.
PMCID: PMC3159502  PMID: 21860683
Endoscopic retrograde cholangiopancreatography; Radiation dose; Fluoroscopy; Radiation exposure; X-ray
6.  Fetal radiation exposure: Is monitoring really needed? 
The effect of fetal radiation during endoscopic retrograde cholangiopancreatography (ERCP) on pregnant women is a very interesting topic. Smith et al recently estimated the fetal radiation exposure in pregnant women undergoing ERCPs using thermoluminescent dosimeters (TLDs). The authors concluded that TLDs are unnecessary during ERCP with modified techniques. We believe that an extreme caution is needed in clinical practice before drawing such conclusions when they are not strongly supported by enough experimental evidence. Therefore, we recommend that fetal radiation exposure be monitored in clinical practice by using dosimeters, bearing in mind that all relevant techniques to control and minimize the exposure must be applied.
PMCID: PMC3742701  PMID: 23951391
Endoscopic retrograde cholangiopancreatography; Pregnancy; Fetal radiation exposure; Thermoluminescent dosimeters; Post-endoscopic retrograde cholangio-pancreatography pancreatitis
7.  Retrospective analysis of radiation exposure during endoscopic retrograde cholangiopancreatography: Critical determinants 
Although the risk of radiation-induced spontaneous malignancy and genetic anomalies from occupational radiological procedures is relatively low – and perhaps slightly lower still for the general population – patients and endoscopists in particular, should be aware of the cumulative risk associated with all exposure. Radiation dose has a direct linear relationship with fluoroscopy duration; therefore, limiting fluoroscopy time is one of the most modifiable methods of reducing exposure during fluoroscopic procedures. This retrospective study analyzed more than 1000 endoscopic retrograde cholangiopancreatography procedures and aimed to determine the specific patient, physician and procedural factors that affect fluoroscopy duration.
Fluoroscopy during endoscopic retrograde cholangiopancreatography (ERCP) has a logarithmic relationship with radiation exposure, and carries a known risk of radiation exposure to patients and staff. Factors associated with prolonged fluoroscopy duration have not been well delineated.
To determine the specific patient, physician and procedural factors that affect fluoroscopy duration.
A retrospective analysis of 1071 ERCPs performed at two tertiary care referral hospitals over an 18-month period was conducted. Patient, physician and procedural variables were recorded at the time of the procedure.
The mean duration of 969 fluoroscopy procedures was 4.66 min (95% CI 4.38 to 4.93). Multivariable analysis showed that the specific patient factors associated with prolonged fluoroscopy duration included age and diagnosis (both P<0.0001). The endoscopist was found to play an important role in the duration of fluoroscopy (ie, all endoscopists studied had a mean fluoroscopy duration significantly different from the reference endoscopist). In addition, the following procedural variables were found to be significant: number of procedures, basket use, biopsies, papillotomy (all P<0.0001) and use of a tritome (P=0.004). Mean fluoroscopy duration (in minutes) with 95% CIs for different diagnoses were as follows: common bile duct stones (n=443) 5.12 (3.05 to 4.07); benign biliary strictures (n=135) 3.94 (3.26 to 4.63); malignant biliary strictures (n=124) 5.82 (4.80 to 6.85); chronic pancreatitis (n=49) 4.53 (3.44 to 5.63); bile leak (n=26) 3.67 (2.23 to 5.09); and ampullary mass (n=11) 3.88 (1.28 to 6.48). When no pathology was found (n=195), the mean fluoroscopy time was 3.56 min (95% CI 3.05 to 4.07). Comparison using t tests determined that the only two diagnoses for which fluoroscopy duration was significantly different from the reference diagnosis of ‘no pathology found’ were common bile duct stones (P<0.0001) and malignant strictures (P<0.0001).
Factors that significantly affected fluoroscopy duration included age, diagnosis, endoscopist, and the number and nature of procedures performed. Elderly patients with biliary stones or a malignant stricture were likely to require the longest duration of fluoroscopy. These identified variables may help endoscopists predict which procedures are associated with prolonged fluoroscopy duration so that appropriate precautions can be undertaken.
PMCID: PMC3206549  PMID: 22059160
ERCP; Fluoroscopy time; Radiation
8.  Occupational radiation dose to eyes from endoscopic retrograde cholangiopancreatography procedures in light of the revised eye lens dose limit from the International Commission on Radiological Protection 
The British Journal of Radiology  2013;86(1022):20120289.
Endoscopic retrograde cholangiopancreatography (ERCP) is a common procedure that combines the use of X-ray fluoroscopy and endoscopy for examination of the bile duct. Published data on ERCP doses are limited, including staff eye dose from ERCP. Occupational eye doses are of particular interest now as the International Commission on Radiological Protection (ICRP) has recommended a reduction in the dose limit to the lens of the eye. The aim of this study was to measure occupational eye doses obtained from ERCP procedures.
A new eye lens dosemeter (EYE-D™, Radcard, Krakow, Poland) was used to measure the ERCP eye dose, Hp(3), at two endoscopy departments in Ireland. A review of radiation protection practice at the two facilities was also carried out.
The mean equivalent dose to the lens of the eye of a gastroenterologist is 0.01 mSv per ERCP procedure with an undercouch X-ray tube and 0.09 mSv per ERCP procedure with an overcouch X-ray tube. Staff eye dose normalised to patient kerma area product is also presented.
Staff eye doses in ERCP have the potential to exceed the revised ICRP limit of 20 mSv per annum when an overcouch X-ray tube is used. The EYE-D dosemeter was found to be a convenient method for measuring lens dose. Eye doses in areas outside of radiology departments should be kept under review, particularly in light of the new ICRP eye dose limit.
Advances in knowledge:
Occupational eye lens doses from ERCP procedures have been established using a new commercially available dedicated Hp(3) dosemeter.
PMCID: PMC3608047  PMID: 23385992
9.  Investigation of patient dose from common radiology examinations in Isfahan, Iran 
The aim of this study was measurement of the radiation doses received by patients for common radiology examinations in hospitals under control of Isfahan University of Medical Sciences, Iran.
Materials and Methods:
Thermoluminescence (lithium fluoride chips, LiF: Mg, Tl) dosimeter was used to measure patient dose for four (chest, posterior-anterior and lateral and skull anterior-posterior, or posterior-anterior and lateral) common radiographic views in six hospitals (seven X-ray machines). The entrance surface dose was measured on 20 randomly patients for each X-ray room.
The maximum (8.85 ± 0.62 mGy) and the minimum (0.62 ± 0.22 mGy) values of ESD was obtained for X-ray machines of Shimadzu and Varian located in Ashrafi-Khomeini-shahr and Kashani hospitals, respectively. As results shows, the values of ESD of skull were higher than that of chest examinations.
The results of this study indicated that ESD measured doses were slightly greater than the ICRP and NRPB reference doses. Efforts should be made to further lower patient doses while securing image quality. In addition, the need to provide relevant education and training to staff in the radiology sections is of utmost importance.
PMCID: PMC3507008  PMID: 23210070
Diagnostic radiology; patient dose; X-ray examinations
10.  Radiation Exposure to Premature Infants in a Neonatal Intensive Care Unit in Turkey 
Korean Journal of Radiology  2008;9(5):416-419.
The aim of this work was to determine the radiation dose received by infants from radiographic exposure and the contribution from scatter radiation due to radiographic exposure of other infants in the same room.
Materials and Methods
We retrospectively evaluated the entrance skin doses (ESDs) and effective doses of 23 infants with a gestational age as low as 28 weeks. ESDs were determined from tube output measurements (ESDTO) (n = 23) and from the use of thermoluminescent dosimetry (ESDTLD) (n = 16). Scattered radiation was evaluated using a 5 cm Perspex phantom. Effective doses were estimated from ESDTO by Monte Carlo computed software and radiation risks were estimated from the effective dose. ESDTO and ESDTLD were correlated using linear regression analysis.
The mean ESDTO for the chest and abdomen were 67 µGy and 65 µGy per procedure, respectively. The mean ESDTLD per radiograph was 70 µGy. The measured scattered radiation range at a 2 m distance from the neonatal intensive care unit (NICU) was (11-17 µGy) per radiograph. Mean effective doses were 16 and 27 µSv per procedure for the chest and abdomen, respectively. ESDTLD was well correlated with ESDTO obtained from the total chest and abdomen radiographs for each infant (R2 = 0.86). The radiation risks for childhood cancer estimated from the effective dose were 0.4 × 10-6 to 2 × 10-6 and 0.6 × 10-6 to 2.9 × 10-6 for chest and abdomen radiographs, respectively.
The results of our study show that neonates received acceptable doses from common radiological examinations. Although the contribution of scatter radiation to the neonatal dose is low, considering the sensitivity of the neonates to radiation, further protective action was performed by increasing the distance of the infants from each other.
PMCID: PMC2627210  PMID: 18838850
Radiation dose; Entrance skin dose; Effective dose; Radiography
11.  Dosimetry during intramedullary nailing of the tibia 
Acta Orthopaedica  2009;80(5):568-572.
Background Intramedullary nailing under fluoroscopic guidance is a common operation. We studied the intraoperative radiation dose received by both the patient and the personnel.
Patients and methods 25 intramedullary nailing procedures of the tibia were studied. All patients suffered from tibial fractures and were treated using the Grosse-Kempf intramedullary nail, with free-hand technique for fixation of the distal screws, under fluoroscopic guidance. The exposure, at selected positions, was recorded using an ion chamber, while the dose area product (DAP) was measured with a DAP meter, attached to the tube head. Thermoluminescent dosimeters (TLDs) were used to derive the occupational dose to the personnel, and also to monitor the surface dose on the gonads of some of the patients.
Results The mean operation time was 101 (48–240) min, with a mean fluoroscopic time of 72 seconds and a mean DAP value of 75 cGy·cm2. The surface dose to the gonads of the patients was less than 8.8 mGy during any procedure, and thus cannot be considered to be a contraindication for the use of this technique. Occupational dose differed substantially between members of the operating personnel, the maximum dose recorded being to the operator of the fluoroscopic equipment (0.11 mSv).
Interpretation Our findings underscore the care required by the primary operator not to exceed the dose constraint of 10 mSv per year. The rest of the operating personnel, although they do not receive very high doses, should focus on the dose optimization of the technique.
PMCID: PMC2823322  PMID: 19916691
12.  The Principle of Digital Subtraction Angiography and Radiological Protection 
Interventional Neuroradiology  2001;6(Suppl 1):25-31.
Recent improvements in x-ray technology have greatly contributed to the advancement of diagnostic imaging. Fluoroscopically guided neurointerventional procedures with digital subtraction angiography (DSΛ) are being performed with increasing frequency as the treatment of choice for a variety of neurovascular diseases. Radiation-induced skin injuries can occur after extended fluoroscopic exposure times, and the injuries have recently been reported. In this article, measured radiation doses at the surface of Rando Phantom with Skin Dose Monitor, and estimated and measured entrance skin doses in patients underwent neurointerventional procedures are reported as well as means of reducing radiation doses absorbed by patients and personnel to avoid occurrence of radiation-induced injuries.
PMCID: PMC3685929  PMID: 20667218
fluoroscopically guided interventional procedure, digital subtraction angiography, radiation protection
13.  Estimating the Absorbed Dose to Critical Organs During Dual X-ray Absorptiometry 
Korean Journal of Radiology  2008;9(2):102-110.
The purpose of this study is to estimate a patient's organ dose (effective dose) during performance of dual X-ray absorptiometry by using the correlations derived from the surface dose and the depth doses in an anthropomorphic phantom.
Materials and Methods
An anthropomorphic phantom was designed and TLDs (Thermoluminescent Dosimeters) were placed at the surface and these were also inserted at different depths of the thyroid and uterus of the anthropomorphic phantom. The absorbed doses were measured on the phantom for the spine and femur scan modes. The correlation coefficients and regression functions between the absorbed surface dose and the depth dose were determined. The derived correlation was then applied for 40 women patients to estimate the depth doses to the thyroid and uterus.
There was a correlation between the surface dose and depth dose of the thyroid and uterus in both scan modes. For the women's dosimetry, the average surface doses of the thyroid and uterus were 1.88 µGy and 1.81 µGy, respectively. Also, the scan center dose in the women was 5.70 µGy. There was correlation between the thyroid and uterus surface doses, and the scan center dose.
We concluded that the effective dose to the patient's critical organs during dual X-ray absorptiometry can be estimated by the correlation derived from phantom dosimetry.
PMCID: PMC2627225  PMID: 18385556
Dual X-ray absorptiometry; TLD dosimetry; Phantom; Absorbed dose; Critical organs
14.  International Live Endoscopic Multichannel Demonstration Using Superfast Broadband Internet Connections 
Clinical Endoscopy  2012;45(1):73-77.
Telemedicine is a convenient and efficient tool for remote education in various fields. The telemedicine system can also be used to educate doctors and medical students. The aim of our study was to establish the effectiveness of the telemedical system for use in a live endoscopic multichannel demonstration conference and to test the effectiveness and usefulness of a multicenter-based live endoscopic demonstration through live, interactive, high resolution video transmission using advanced networks and the digital video transport system (DVTS).
This study is a prospective multicenter pilot study. A live demonstration of an endoscopic submucosal dissection (ESD) and an endoscopic retrograde cholangiopancreatography (ERCP) using advanced network technology was performed.
The DVTS successfully transmitted uncompressed, high-resolution, digital lectures with endoscopy video during a multichannel endoscopic live demonstration of ESD and ERCP over multiple advanced networks. The overall satisfaction rating when the endoscopic lecture demonstration was performed by combining DVTS was generally good.
We believe that a multicenter-based live endoscopic demonstration is a very effective conferencing method when using advanced networks and DVTS.
PMCID: PMC3363122  PMID: 22741135
Telemedicine; Internet; International educational exchange
15.  Evaluation of target dose based on water-equivalent thickness in external beam radiotherapy 
In vivo dosimetry was carried out for 152 patients receiving external beam radiotherapy and the treatment sites were divided into two main groups: Thorax, Abdomen, and Pelvic (120 fields) and Head and Neck (52 fields). Combined entrance and exit dose measurements were performed using LiF: Mg, Cu, P thermoluminescent dosimeters (TLDs). Water-equivalent (effective) thicknesses and target dose were evaluated using dose transmission data. The ratio of measured to expected value for each quantity was considered as an indicator for the accuracy of the parameter. The average ratio of the entrance dose was evaluated as 1.01 ± 0.07. In the diameter measurement, the mean ratio of effective depth divided by the contour depth is 1.00 ± 0.13 that shows a wide distribution which reflects the influence of contour inaccuracies as well as tissue inhomogeneities. At the target level, the mean ratio of measured to the prescribed dose is 1.00 ± 0.07. According to our findings, the difference between effective depth and patient depth has a direct relation to target dose discrepancies. There are some inevitable sources which may cause the difference. Evaluation and application of effective diameter in treatment calculations would lead to a more reliable target dose, especially for fields which involve Thorax, Abdomen, and Pelvic.
PMCID: PMC3607346  PMID: 23532059
External beam radiotherapy; in vivo do simetry; target dose; thermoluminescent dosimetry
16.  Radiation risk from fluoroscopically-assisted anterior cruciate ligament reconstruction 
Precise tunnel positioning is crucial for success in anterior cruciate ligament (ACL) reconstruction. The use of intra-operative fluoroscopy has been shown to improve the accuracy of tunnel placement. Although radiation exposure is a concern, we lack information on the radiation risk to patients undergoing fluoroscopically-assisted ACL reconstruction with a standard C-arm. The aim of our study was to determine the mean radiation doses received by our patients.
Radiation doses were recorded for 18 months between 1 April 2007 and 30 September 2008 for 58 consecutive patients undergoing ACL reconstruction assisted by intra-operative fluoroscopy. Dose area product (DAP) values were used to calculate the entrance skin dose (ESD), an indicator of potential skin damage and the effective dose (ED), an indicator of long-term cancer risk, for each patient.
The median age of 58 patients included in data analysis was 28 years (range, 14–52 years), of whom 44 were male (76%). The mean ESD during intra-operative fluoroscopy was 0.0015 ± 0.0029 Gy. The mean ED was 0.001 ± 0.002 mSv. No results exceeded the threshold of 2 Gy for skin damage, and the life-time risk of developing new cancer due to intra-operative fluoroscopy is less than 0.0001%.
Radiation doses administered during fluoroscopically-assisted ACL reconstruction were safe and do not represent a contra-indication to the procedure.
PMCID: PMC3025191  PMID: 20501019
Anterior cruciate ligament; Reconstruction; Intra-operative fluoroscopy; Radiation dose; Radiation risk
17.  Optimization of the Radiological Protection of Patients Undergoing Digital Radiography 
Journal of Digital Imaging  2011;25(1):196-200.
Because of a much higher dynamic range of flat panel detectors, patient dose can vary without change of image quality being perceived by radiologists. This condition makes optimization (OT) of radiation protection undergoing digital radiography (DR) more complex, while a chance to reduced patient dose also exists. In this study, we evaluated the difference of patient radiation and image rejection before and after OT to identify if it is necessary to carry out an OT procedure in a routine task with DR. The study consisted of a measurement of the dose area product (DAP) and entrance surface dose (ESD) received by a reference group of patients for eight common radiographic procedures using the DR system before and after OT. Meanwhile image rejection data during two 2-month periods were collected and sorted according to reason. For every radiographic procedure, t tests showed significant difference in average ESD and DAP before and after OT (p < 0.005). The ESDs from most examinations before OT were three times higher than that after OT. For DAPs, the difference is more significant. Image rejection rate after OT is significantly lower than that before OT (χ2 = 36.5, p < 0.005). The substantial reductions of dose after OT resulted from appropriate mAs and exposure field. For DR patient dose, less than recommended diagnostic reference level can meet quality criteria and clinic diagnosis.
PMCID: PMC3264715  PMID: 21725621
Optimization; Digital radiography; Radiation dose; Diagnostic image quality; Exposure index
18.  Peripheral dose measurements with diode and thermoluminescence dosimeters for intensity modulated radiotherapy delivered with conventional and un-conventional linear accelerator 
The objective of this paper was to measure the peripheral dose (PD) with diode and thermoluminescence dosimeter (TLD) for intensity modulated radiotherapy (IMRT) with linear accelerator (conventional LINAC), and tomotherapy (novel LINAC). Ten patients each were selected from Trilogy dual-energy and from Hi-Art II tomotherapy. Two diodes were kept at 20 and 25 cm from treatment field edge. TLDs (LiF:MgTi) were also kept at same distance. TLDs were also kept at 5, 10, and 15 cm from field edge. The TLDs were read with REXON reader. The readings at the respective distance were recorded for both diode and TLD. The PD was estimated by taking the ratio of measured dose at the particular distance to the prescription dose. PD was then compared with diode and TLD for LINAC and tomotherapy. Mean PD for LINAC with TLD and diode was 2.52 cGy (SD 0.69), 2.07 cGy (SD 0.88) at 20 cm, respectively, while at 25 cm, it was 1.94 cGy (SD 0.58) and 1.5 cGy (SD 0.75), respectively. Mean PD for tomotherapy with TLD and diode was 1.681 cGy SD 0.53) and 1.58 (SD 0.44) at 20 cm, respectively. The PD was 1.24 cGy (SD 0.42) and 1.088 cGy (SD 0.35) at 25 cm, respectively, for tomotherapy. Overall, PD from tomotherapy was found lower than LINAC by the factor of 1.2-1.5. PD measurement is essential to find out the potential of secondary cancer. PD for both (conventional LINAC) and novel LINACs (tomotherapy) were measured and compared with each other. The comparison of the values for PD presented in this work and those published in the literature is difficult because of the different experimental conditions. The diode and TLD readings were reproducible and both the detector readings were comparable.
PMCID: PMC3607344  PMID: 23531765
Diode; TLD-100; intensity modulated radiotherapy; linear accelerator; peripheral dose; tomotherapy
19.  Infant Cardiac CT Angiography with 64-Slice and 256-Slice CT: Comparison of Radiation Dose and Image Quality Using a Pediatric Phantom 
PLoS ONE  2012;7(11):e49609.
The aims of this study were to investigate the image quality and radiation exposure of pediatric protocols for cardiac CT angiography (CTA) in infants under one year of age.
Methodology/Principal Findings
Cardiac CTA examinations were performed using an anthropomorphic phantom representing a 1-year-old child scanned with non-electrocardiogram-gated (NG), retrospectively electrocardiogram-gated helical (RGH) and prospectively electrocardiogram-gated axial (PGA) techniques in 64-slice and 256-slice CT scanners. The thermoluminescent dosimeters (TLD) were used for direct organ dose measurement, while dose-length product and effective mAs were also used to estimate the patient dose. For image quality, noise and signal-to-noise-ratio (SNR) were assessed based on regions-of-interest drawn on the reconstructed CT images, and were compared with the proposed cardiac image quantum index (CIQI). Estimated dose results were in accordant to the measured doses. The NG scan showed the best image quality in terms of noise and SNR. The PGA scan had better image quality than the RGH scan with 83.70% dose reduction. Noise and SNR were also corresponded to the proposed CIQI.
The PGA scan protocol was a good choice in balancing radiation exposure and image quality for infant cardiac CTA. We also suggested that the effective mAs and the CIQI were suitable in assessing the tradeoffs between radiation dose and image quality for cardiac CTA in infants. These results are useful for future implementation of dose reduction strategies in pediatric cardiac CTA protocols.
PMCID: PMC3504147  PMID: 23185380
20.  Losartan to prevent hyperenzymemia after endoscopic retrograde cholangiopan-creatography: A randomized clinical trial 
AIM: To study if the angiotensin II receptor blockers (ARB) losartan counteracts pancreatic hyperenzymemia as measured 24 h after endoscopic retrograde cholangiopancreatography (ERCP).
METHODS: A triple-blind and placebo-controlled randomized clinical trial was performed at two Swedish hospitals in 2006-2008. Patients over 18 years of age undergoing ERCP, excluding those with current pancreatitis, current use of ARB, and severe disease, such as sepsis, liver and renal failure. One oral dose of 50 mg losartan or placebo was given one hour before ERCP. The relative risk of hyperenzymemia 24 h after ERCP was estimated using multivariable logistic regression, and expressed as odds ratio with 95% confidence intervals (CIs), including adjustment for potential remaining confounding.
RESULTS: Among 76 participating patients, 38 were randomized to the losartan and the placebo group, respectively. The incidence rates of hyperenzymemia and acute pancreatitis among all 76 participating patients were 21% and 12%, respectively. Hyperenzymemia was detected in 9 and 7 patients in the losartan and placebo group, respectively. There were no major differences between the comparison groups regarding cannulation difficulty, findings, or proportion of patients requiring drainage of the bile ducts. There were, however, more pancreatic duct injections, a greater extent of pancreatography, and more biliary sphincterotomies in the losartan group than in the placebo group. Losartan was not associated with risk of hyperenzymemia compared to the placebo group after multi-varible logistic regression analysis (odds ratio 1.6, 95%CI 0.3-7.8).
CONCLUSION: In this randomized trial 50 mg losartan given orally had no prophylactic effect on development of hyperenzymemia after ERCP.
PMCID: PMC3506968  PMID: 23189222
Renin-angiotensin system; Pancreatitis; Prophylaxis; Placebo-controlled trial
21.  In vivo dosimetry of thyroid doses from different irradiated sites in children and adolescents: a cross-sectional study 
Scattered radiation can be assessed by in vivo dosimetry. Thyroid tissue is sensitive to radiation, even at doses <10 cGy. This study compared the scattered dose to the thyroid measured by thermoluminescent dosimeters (TLDs) and the estimated one by treatment planning system (TPS).
During radiotherapy to sites other than the thyroid of 16 children and adolescents, seventy-two TLD measurements at the thyroid were compared with TPS estimation.
The overall TPS/TLD bias was 1.02 (95% LA 0.05 to 21.09). When bias was stratified by treatment field, the TPS overestimated TLD values at doses <1 cGy and underestimated them at doses >10 cGy. The greatest bias was found in pelvis and abdomen: 15.01 (95% LA 9.16 to 24.61) and 5.12 (95% LA 3.04 to 8.63) respectively. There was good agreement in orbit, head, and spine: bias 1.52 (95% LA 0.48 to 4.79), 0.44 (95% LA 0.11 to 1.82) and 0.83 (0.39 to 1.76) respectively. There was small agreement with broad limits for lung and mediastinum: 1.13 (95% LA 0.03 to 40.90) and 0.39 (95% LA 0.02 to 7.14) respectively.
The scattered dose can be measured with TLDs, and TPS algorithms for outside structures should be improved.
PMCID: PMC3922907  PMID: 24479890
Thyroid gland; Thermoluminescent dosimetry; Radiotherapy; Child; Adolescent
22.  Practical dosimetry methods for the determination of effective skin and breast dose for a modern CT system, incorporating partial irradiation and prospective cardiac gating 
The British Journal of Radiology  2012;85(1011):237-248.
For CT coronary angiography (CTCA), a generic chest conversion factor returns a significant underestimate of effective dose. The aim of this manuscript is to communicate new dosimetry methods to calculate weighted CT dose index (CTDIw), effective dose, entrance surface dose (ESD) and organ dose to the breast for prospectively gated CTCA.
CTDIw in 32 cm diameter Perspex phantom was measured using an adapted technique, accounting for the segmented scan characteristic. Gafchromic XRCT film (International Speciality Products, New Jersey, NJ) was used to measure the distribution and magnitude of ESD. Breast dose was measured using high sensitivity metal oxide semiconductor field-effect transistors and compared to the computer based imaging performance assessment of CT scanners (ImPACT) dosimetry calculations.
For a typical cardiac scan the mean ESD remained broadly constant (7–9 mGy) when averaged over the circumference of the Perspex phantom. Typical absorbed dose to the breast with prospectively gated protocols was within the range 2–15 mGy. The subsequent lifetime attributable risk (LAR) of cancer incidence to the breast was found at 0.01–0.06 for a 20-year-old female. This compares favourably to 100 mGy (LAR ∼0.43) for a retrospectively gated CTCA.
Care must be taken when considering radiation dosimetry associated with prospectively gated scanning for CTCA and a method has been conveyed to account for this. Breast doses for prospectively gated CTCA are an order of magnitude lower than retrospectively gated scans. Optimisation of cardiac protocols is expected to show further dose reduction.
PMCID: PMC3473996  PMID: 21896660
23.  Application of MOSFET Detectors for Dosimetry in Small Animal Radiography Using Short Exposure Times 
Radiation research  2008;170(2):260-263.
Digital subtraction angiography (DSA) X-ray imaging for small animals can be used for functional phenotyping given its ability to capture rapid physiological changes at high spatial and temporal resolution. The higher temporal and spatial requirements for small-animal imaging drive the need for short, high-flux X-ray pulses. However, high doses of ionizing radiation can affect the physiology. The purpose of this study was to verify and apply metal oxide semiconductor field effect transistor (MOSFET) technology to dosimetry for small-animal diagnostic imaging. A tungsten anode X-ray source was used to expose a tissue-equivalent mouse phantom. Dose measurements were made on the phantom surface and interior. The MOSFETs were verified with thermoluminescence dosimeters (TLDs). Bland-Altman analysis showed that the MOSFET results agreed with the TLD results (bias, 0.0625). Using typical small animal DSA scan parameters, the dose ranged from 0.7 to 2.2 cGy. Application of the MOSFETs in the small animal environment provided two main benefits: (1) the availability of results in near real-time instead of the hours needed for TLD processes and (2) the ability to support multiple exposures with different X-ray techniques (various of kVp, mA and ms) using the same MOSFET. This MOSFET technology has proven to be a fast, reliable small animal dosimetry method for DSA imaging and is a good system for dose monitoring for serial and gene expression studies.
PMCID: PMC2533764  PMID: 18666818
24.  Evaluation of clinical use of OneDose™ metal oxide semiconductor field-effect transistor detectors compared to thermoluminescent dosimeters to measure skin dose for adult patients with acute lymphoblastic leukemia 
Total body irradiation is a protocol used to treat acute lymphoblastic leukemia in patients prior to their bone marrow transplant. It involves the treatment of the whole body using a large radiation field with extended source-skin distance. Therefore, it is important to measure and monitor the skin dose during the treatment. Thermoluminescent dosimeters (TLDs) and the OneDose™ metal oxide semiconductor field effect transistor (MOSFET) detectors are used during treatment delivery to measure the radiation dose and compare it with the target prescribed dose.
The primary goal of this study was to measure the variation of skin dose using OneDose MOSFET detectors and TLD detectors, and compare the results with the target prescribed dose. The secondary aim was to evaluate the simplicity of use and determine if one system was superior to the other in clinical use.
Material and Methods:
The measurements involved twelve adult patients diagnosed with acute lymphoblastic leukemia. TLD and OneDose MOSFET dosimetry were performed at ten different anatomical sites of each patient.
The results showed that there was a variation between skin dose measured with OneDose MOSFET detectors and TLD in all patients. However, the variation was not significant. Furthermore, the results showed for every anatomical site there was no significant different between the prescribed dose and the dose measured by either TLD or OneDose MOSFET detectors.
There were no significant differences between the OneDose MOSFET and TLDs in comparison to the target prescribed dose. However, OneDose MOSFET detectors give a direct read-out immediately after the treatment, and their simplicity of use to compare with TLD detectors may make them preferred for clinical use.
PMCID: PMC3234142  PMID: 22171243
Skin Dose; Total Body Irradiation; MOSFET; TLD; ALL
25.  Radiation protection of the ovaries in young scoliosis patients 
European Spine Journal  1998;7(4):278-281.
Concerns in clinical practice arose over the amount of ovarian irradiation received from X-ray examinations in females with scoliosis. This study was instigated to assess the adequancy of ovarian protection in this young and genetically vulnerable group of patients. A total of 283 plain films in 20 patients with scoliosis were reviewed. If the area immediately adjacent to the medial wall of the acetabulum was clearly seen, then this was taken as indicative of ovarian irradiation. In a separate study, the radiation dose in the centre of the X-ray field on the surface of a tissue-equivalent anthropomorphic phantom was measured using thermoluminescent dosimeters. Standard conditions for scoliosis X-ray examination were used. The average age of patients was 21.5 years. The mean number of single X-ray exposures per patient was 14.1 over a mean of 44 months. The mean measured entrance dose to the skin in the 20 patients was 0.08 mGy (equivalent dose = 0.08 mSv). The mean percentage of examinations without lead protection was 18% per patient (range 0–40%). This would have resulted in a mean equivalent dose to the surface of the abdomen of 0.1 mSv per year per patient from the unprotected examinations. The maximum dose received in 1 year was 0.6 mSv. The maximum dose to the unprotected ovary was estimated to be 0.05 mSv from a single examination. The mean total cumulative ovarian dose was calculated as 180 μSv per patient (range 45–355 μSv) over the time period studied. The findings of this study indicate that ovarian protection should be improved. Reasons for this and suggestions for improvement are discussed.
PMCID: PMC3611264  PMID: 9765034
Key words Scoliosis; Radiation; dose; Ovary

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