Dosimetry Reports Research Articles

Patient Dose Analysis Using GafchromicTM EBT3 Film: A Retrospective Study with a Four Dual-Field Technique in Total Skin Electron Therapy.

The Six dual-field is the most commonly used treatment technique in total skin electron therapy (TSET). Because of the prolonged treatment period, the patient may experience discomfort, and routine radiotherapy treatments may be affected. This reflects the idea of using a modified technique in TSET. The study aims to report our experience with the four dual-field technique and review the in-vivo dosimetry using gafchromic film. The in-vivo dosimetry reports using gafchromic EBT-3 films of 12 patients who received TSET with the four dual-field techniques in our hospital were analysed in this study. The dosimetric parameter including percentage depth dose, dose homogeneity, flatness and symmetry were analysed in this study. For all the patients, the mean dose to the skin was close to the prescription dose, and it was within 10% (99.3%-103%) of the prescription dose. The standard deviation was observed between 5.8 and 12.4 cGy. According to international standards, all of the measured dosimetric parameters were within the acceptable limit and thereby validating our technique. The in-vivo dosimetry study using radiochromic film in TSET is relatively uncommon. So, based on our results, gafchromic films are a viable choice. The objective of our four dual-field techniques is to reduce the overall treatment time on the machine, whereas our study shows a time reduction when compared to regular techniques, which aids in the smooth operation of daily routines. The preliminary results of this novel modified technique in TSET demonstrated favourable effectiveness with minimal skin toxicity. This four dual-field technique is simple and easy to implement. Comparatively, this study shows the dose homogeneity of ±10% and better dose in the underdose areas proving the reliability and homogeneity of four-dual field technique.

Monitoring Individual Occupational Radiation Exposure at Multiple Institutions.

Within a few years of its' discovery, ionizing radiation demonstrated adverse effects on biological systems. Since that time great strides were made in both radiation protection, detection, and personnel monitoring. Monitoring occupational radiation dose to individuals is enforced by several regulatory agencies in the United States (U.S.) and is referenced in numerous sections of the Code of Federal Regulations (CFR). A literature review with an examination of regulatory guidelines and a Radiation Safety Officers (RSO) survey was conducted to evaluate how often radiation dose exposure is monitored when an individual receives occupational radiation dose at more than one facility. The length of time an RSO has overseen the radiation safety program at his/her institution can impact if dosimetry reports are requested for individuals that work at multiple places. Despite having safer equipment and occupational radiation exposure standards, there is no universal mechanism to track and record exposure for individuals working at more than one institution.

P1384Radiation safety and electrophysiologists: radiation protection status

Abstract INTRODUCTION Ionizing radiation is typically used during variety electrophysiological (EP) procedures, although it may contribute to deterministic effects especially for staff. PURPOSE The purpose of this study was to perform an analysis of EP operators’ radiation protective devices for occupational exposure. METHODS Data reported herein were gathered from international, multi-site, prospective, Go 4 Zero Fluoroscopy registry. The registry encompassed 25 European EP centers, and up to 5 operators from each center. The presence of operators’ X-ray protection tools was examined to determine the level of operators’ protection. Additionally, the tests included availability of measures to decrease radiation output and exposure control measures. Finally, the analysis of correlation between the X-ray protection and degree of operators’ experience (<5, 5-15,>15 years) as well as number of procedures performed per month (1-9, 10-19, 20-39, >40 procedures/month) was performed. RESULTS Our analysis included 95 operators (median age: 39 years, 85% of male, median training time: 5 years). The whole study group performed annually medical examinations due to radiation exposure and 56% of them received dosimetry reports once a month, 5% - once every 3 months, and 39% - once a year. Irrespectively of experience or number of performed procedures the most frequently used X-ray protection tools (used by >80% of group) were lead apron, thyroid shields, screen below the table, glass in the lab, and least often (used by < 6% of group) – protective gloves and cabin. The most often exposure control measures used were chest (95%) followed by collar (31%), ring (24%) and eye (7%) dosimeters. The inverse correlation between level of experience and measures to decrease radiation output was observed (collimation: 84%, 80% and 78%; minimizing the tube-to intensifier distance: 100%, 93% and 91% of operators with <5, 5-15 and >15 years of experience, respectively). There were not observed differences between type of radiation protection equipment and operators’ level of experience or number of procedures. Additionally, there were no differences between male and female operators regarding protective equipment, expect eyeglasses or cabin that were more often used by men. Operators who were protected by >4 X-ray protection tools were exposed for higher radiation levels as compared to those protected by <4 X-ray protection tools (median [IQR] radiation exposure: 0.6 [0.2-1.1] vs 0.2 [0.1-0.2] mSv per month, p < 0.0001; 1.1 [0.1-12.0] vs 0.5 [0.1-1.1] mSv per year, p < 0.0001). There were no differences between the type of (universitary vs non-universitary) or institution’s localization (Eastern vs Central vs Western Europe) and used protective equipment. CONCLUSIONS Both proper radiation protective equipment, and regular medical examination due to professional exposure are mandatory to reduce radiation exposure in practice.

The Effects on Technologist Occupational Exposure in PET/CT Departments When Working with Students at Various Levels of Supervision.

The purpose of this study was to evaluate the effect that the presence of a student in the PET/CT department has on the technologist's occupational radiation exposure and whether this effect is influenced by the type of supervision performed. Methods: This was a retrospective, institutional review board-approved study that collected data from 2 PET/CT departments. Dosimetry reports, correlated with the clinical schedules of the students, were normalized for workflow (amount of radioactivity), the number of technologists, and the number of monitored days in the department. A 2-sample t test assuming unequal variance with an α of 0.05 was used to compare doses between with-student and without-student groups and between direct-supervision and indirect-supervision groups. Results: The study consisted of a dataset of 42 dosimetry reports, 19 with students and 23 without students. When comparing with-student and without-student groups, the total (n = 42) extremity dose had a P value of 0.012 with a mean of 0.0011665 μSv/MBq/technologist/d; all other dose comparisons between groups were greater than 0.05 (P > 0.05). For indirect supervision (n = 21), the extremity-dose P value was 0.298. The other dose P values were all less than 0.05. For direct supervision (n = 21), the dose P values were all greater than 0.05. There was a trend toward decreasing exposure of technologists when students were in the department. Conclusion: Extremity dose decreases when students are present. There is a trend toward decreasing dose with indirect supervision.

Occupational Eye Lens Radiation Dose While Performing Interventional Procedures over 18 Months Using a Face-Shield Equipped Suspended Radiation Protection System

Background: Numerous studies have demonstrated increasing evidence for cataractogenesis at lower levels of ionizing radiation than previously believed, with some suggesting possible absence of a threshold. Genetic differences between individuals also result in increased susceptibility in some operators, who might not be aware. European occupational exposure limits have been reduced and operators are seeking protective measures. Objective: To evaluate the protective effect of a face-shield equipped suspended protection system (Zero-Gravity®, TIDI Products, Neenah, WI) along with adherence to safety practices against radiation dose to the eye lens for an interventional radiologist performing a wide variety of procedures. Materials and Methods: In this institutional review board-approved single-institution study, one interventional radiologist wore a highly sensitive personnel monitoring dosimeter badge on the cap near the left eye while performing 299 procedures (3690 fluoroscopy minutes) over 18 consecutive months while utilizing the suspended protection system along with adherence to other generally recommended safety practices and movement away from the field during angiographic power injections. Dosimetry reports and procedural information were retrospectively reviewed. Results: Total lens dose equivalent to the left eye over 18 months was 0.11 mSv (annualized dose = 0.073 mSv, or 7.3 mRem). The patient-dose-area product standardized dose of 0.00576 μSv/Gy⋅cm2 is well below reports of conventional lead aprons, shields, and protective eyewear. Conclusion: Eye exposures were kept to near-background levels using the materials and methods of this study while performing a wide variety of complex procedures from all positions around the patient.

Radiation awareness among nurses in nuclear medicine departments

Objective: The aim of this study is to explore the awareness level of radiation risks among nurses working in nuclear medicine departments (NMDs). Design: A cross-sectional survey was used. Data were collected between February and March 2011.The data were collected using a self-administered, structured questionnaires. One open-ended question was added at the end of the questionnaire. Setting: The study was conducted in NMDs representing five Kuwaiti governmental general and specialised hospitals and centres. Subjects: This study comprised twenty one non-Kuwaiti female nurses who worked in NMDs. Results: Nearly all of the nurses did not attend any radiation protection courses, they were not aware of the ALARA principle and they were not familiar with Geiger-Mueller counter. Most of these nurses were not able to read the dosimetry reports and they were not familiar with the terms RSO, RSC, and the 10 day rule concept. Conclusion: Nearly all nurses working in NMDs in Kuwait are not aware of radiation protection and risks. This lack of awareness has serious implications on both patients and nurses. Courses on radiation risks and protection should be provided to nurses during and after their formal nursing education.

Absorbed radiation doses to staff after implementation of a radiopharmacy clean room.

In response to U.S. Pharmacopeia general chapter <797> standards, a clean room was constructed for our in-house radiopharmacy. Previously, most patient doses were prepared as needed just before injection. Currently, to minimize repeated entries into the clean room, most patient doses are prepared in batches; that is, early morning and noontime preparation of doses to be injected at various times throughout the morning and the afternoon, respectively. Because these patient doses may be prepared well before injection time, radioactive decay necessitates higher amounts of radioactivity to be handled for patient dose preparation. Hence, absorbed radiation doses to staff, all of whom rotate into the radiopharmacy clean room in addition to their regular patient-related activities, were retrospectively evaluated. Monthly dosimetry reports for body (chest badge) and extremities (finger ring) were retrospectively reviewed for each staff member for 12 mo before and 12 mo after implementation of the radiopharmacy clean room. Monthly data were evaluated for average and SD, and 12-mo groups were evaluated using a paired t test. Data for the second 12-mo period were also normalized to the same number of patient doses to account for an increase in procedure volume and were reevaluated. Before the radiopharmacy clean room had been implemented, average monthly absorbed radiation doses to body and extremities were 23 ± 15 mrem (0.23 ± 0.15 mSv) and 93 ± 59 mrem (0.93 ± 0.59 mSv), respectively. After the clean room had been implemented, average monthly absorbed radiation doses increased to 32 ± 16 mrem (0.32 ± 0.16 mSv) (P < 0.001) and 121 ± 89 mrem (1.21 ± 0.89 mSv) (P = 0.0015), respectively. When normalized for procedure volume, average monthly absorbed radiation doses after implementation of the clean room were still higher, at 29 ± 15 mrem (0.29 ± 0.15 mSv) (P = 0.001) and 110 ± 80 mrem (1.10 ± 0.80 mSv) (P = 0.039), respectively. After implementation of a radiopharmacy clean room, absorbed radiation doses to body and extremities increased by 26% and 18%, respectively, even after normalizing for procedure volume. Because absorbed radiation doses from other activities, such as patient dose administration and patient imaging, are assumed to remain relatively constant, these increases in absorbed radiation doses to staff are attributed to changes in work flow after implementation of the radiopharmacy clean room.

Fluoroscopy Procedure and Equipment Changes to Reduce Staff Radiation Exposure in the Interventional Spine Suite

Background: Fluoroscopic guided percutaneous interventional spine procedures are increasingly performed in recent years as they have been shown to be target specific and enhance patient safety. However, ionizing radiation has been associated with stochastic effects such as cancer and genetic defects as well as deterministic effects such as cataracts, erythema, epilation, and even death. These are dose related, and hence, measures should be taken to minimize radiation exposure to patients and health care personnel to reduce these adverse effects. Objective: A risk reduction project was completed with the goal of reducing effective doses to the staff and patients in a university-based spinal interventional practice. Effective dose reduction to the staff and patients was hypothesized to occur with technique and equipment changes in the procedure suite. The goal of this study was to quantify effective dose rates to staff before and after interventions. Study Design: Retrospective study comparing descriptive data of effective dose to the health care staff before and after implementation of a combination of technique and equipment changes. Methods: Technique changes from pre to post intervention period included continuous needle advancement under continuous fluoroscopic controlled by the interventional physician to intermittent needle advancement under pulsed fluoroscopic controlled by the radiology technician. Equipment changes included circumferential lead drape skirt around the procedure table and use of mobile transparent lead barriers on both sides of the procedure table. Effective dose exposure measured in Millirem (mrem) from the radiation dosimetry badges for pre-intervention (February 2009 through June 2009) and post-intervention (November 2009 through March 2010) periods were examined through monthly radiation dosimetry reports for the fluoroscopy suite staff. Results: A total of 685 interventional procedures were performed in the pre-intervention period and 385 in the post-intervention period. The median cumulative mrem (interquartile range) for all staff combined in the pre-intervention period was 71 (28,75) and post-intervention period was 1 (0,3). The median mrem per procedure was significantly higher in the pre-intervention group 0.46 (0.36, 0.54) compared to post-intervention 0.01 (0.0.03); P &lt; 0.01. The percentage reduction in overall effective dose per procedure to all staff was 97.3%. Limitations: Observational study, multiple radiation reduction interventions confound the individual effects of each intervention’s effective dose Conclusions: Spinal injection technique and equipment changes in the procedure suite significantly reduced the rate of effective dose to the clinical staff. Key words: Fluoroscopy, effective radiation dose, spine

Automatic in vivo portal dosimetry of all treatments

At our institution EPID (electronic portal imaging device) dosimetry is routinely applied to perform in vivo dose verification of all patient treatments with curative intent since January 2008. The major impediment of the method has been the amount of work required to produce and inspect the in vivo dosimetry reports (a time-consuming and labor-intensive process). In this paper we present an overview of the actions performed to implement an automated in vivo dosimetry solution clinically. We reimplemented the EPID dosimetry software and modified the acquisition software. Furthermore, we introduced new tools to periodically inspect the record-and-verify database and automatically run the EPID dosimetry software when needed. In 2012, 95% of our 3839 treatments scheduled for in vivo dosimetry were analyzed automatically (27 633 portal images of intensity-modulated radiotherapy (IMRT) fields, 5551 portal image data of VMAT arcs, and 2003 portal images of non-IMRT fields). The in vivo dosimetry verification results are available a few minutes after delivery and alerts are immediately raised when deviations outside tolerance levels are detected. After the clinical introduction of this automated solution, inspection of the detected deviations is the only remaining work. These newly developed tools are a major step forward towards full integration of in vivo EPID dosimetry in radiation oncology practice.

Presenting statistical uncertainty on cytogenetic dose estimates

Cytogenetic dosimetry results are customarily accompanied by 95% confidence limits and the derivation of these limits is discussed. Simply presenting values of the best estimate of dose and 95% limits assumes that recipients of dosimetry reports, possibly the patients themselves, have a sufficient grasp of statistics to comprehend the concept of uncertainty. Two further methods have been developed to aid improved understanding for the lay person. The first method, particularly useful for suspected low doses, presents a simple odds ratio indicating that the results favour either zero dose or that suspected; for example, from an unexpected dose recorded on a badge. The second method, described fully here for the first time, uses a graphical illustration of a normalised distribution of dose so that one may visualise the area beneath a curve that represents the probability that the dose lies within various bounds.

Patient dosimetry in diagnostic radiology-some practical considerations in an NHS region

The requirement to monitor the doses received by patients undergoing diagnostic X-ray examinations is discussed and reviewed in the context of the implementation and coordination of patient dosimetry services within an NHS Region by a regionally managed medical physics department. Four aspects of the dosimetry programme are described. Following installation of dose-area-product (DAP) meters, a region-wide data collection programme and associated database has been established, together with regular dosimetry reports. Thermoluminescence techniques are also widely employed and a complementary automated dosimetry system has been developed. Agreement between calculated and measured doses is generally within 15%. A survey of doses from or scanners in the region has resulted, in some cases, in changes in technique, in order to reduce doses. In mammography, regular assessment of 18 X-ray units has shown that mean glandular doses are consistently less than 2 mGy. An important consideration arising from the entire programme is the need to use the collected dose data to implement changes in technique if dose reduction is indicated or if NRPB reference levels are exceeded. The regionally managed programme ensures that a large database of relevant information, covering a comprehensive range of techniques and equipment, is available to a wide audience of physicists, radiographers and radiologists.