Helen Warren-Forward

Variations in dose response with x-ray energy of LiF:Mg,Cu,P thermoluminescence dosimeters: implications for clinical dosimetry

In many medical procedures where accurate radiation dose measurements are needed, the variation of detector response with x-ray energy is of concern. The response of LiF:Mg,Cu,P TLDs to a range of x-ray energies was analysed in monoenergetic (synchrotron), diagnostic and therapy radiation beams with the aim of implementing this dosimeter into clinical practice where existing dosimetry techniques are limited due to lack of sensitivity or tissue equivalence (e.g. neonatal radiography, mammography and brachytherapy). LiF:Mg,Cu,P TLDs in different forms from two manufacturers (MCP-N: TLD Poland, GR200: SDDML China) were irradiated using x-ray beams covering 10 keV to 18 MVp. Dose readings were compared with an ionization chamber. The effect of different TLD types and annealing cycles on clinical utility was investigated. The measured energy response of LiF:Mg,Cu,P TLDs was fit to a simple model devised by Kron et al (1998 Phys. Med. Biol. 43 3235-59) to describe the variation of TLD response with x-ray energy. If TLDs are handled as recommended in the present paper, the energy response of LiF:Mg,Cu,P deviates by a maximum of 15% from unity and agrees with the model to within 5% or experimental uncertainty between 15 keV and 10 MeV. LiF:Mg,Cu,P TLDs of all forms have consistent and superior energy response compared to the standard material LiF:Mg,Ti and are therefore suitable for a wide range of applications in diagnostic radiology and radiotherapy.

Reproducibility of visual assessment on mammographic density

BackgroundHigh mammographic density was an independent risk factor for breast cancer and has a higher associated risk than most other known risk factors. The reproducibility remains a major issue in assessment of breast parenchymal patterns. Misclassification of mammographic pattern can lead to significant underestimation of risk estimates. The purpose of this study was to assess the inter-rater and intra-rater reliability based on visual subjective mammographic density measurements.MethodThree density measures, Wolfe parenchymal pattern, Boyd classification scale, and a percentage of densities in total breast, were investigated. The study included 101 women who were participants of the International Breast Cancer Intervention Study I (IBIS I) for up to 7 years. Seven sets of mammograms were collected for each woman. Left breast mediolateral oblique films were digitized, and the scanned images were independently reviewed by two readers. These images were reassessed by one reader after a year. The agreements of measures were evaluated by Kappa statistics (Wolfe and Boyd scale) and intraclass correlation coefficient (percentage densities).ResultsFor the inter-rater agreement, Weighted Kappa for Wolfe scale was 0.89 (P < 0.0001) and for Boyd scale was 0.84 (P < 0.0001). The intraclass correlation coefficient was 0.94 for percentage densities. For the intra-rater agreement, Weighted Kappa for Wolfe scale was 0.87 (P < 0.0001) and for Boyd scale was 0.86 (P < 0.0001). The intraclass correlation coefficient was 0.96 for percentage densities.ConclusionThe study concludes that both visual qualitative and quantitative measurements on mammographic density are highly reproducible in the breast cancer research studies if appropriate training is provided. The method is appropriate for risk assessment in a prevention trial.

Optimization of radiographic technique for chest radiography

Over 1500 patients undergoing chest radiography in the West Midlands have been monitored for entrance surface doses using lithium borate thermoluminescent dosemeters. In total 63 X-ray tubes were monitored from 30 hospital departments. The mean patient entrance surface dose is 0.15 mGy, and the 75th percentile entrance surface dose is 0.18 mGy. A reference level of 0.18 mGy has been recommended for PA chest radiography in the West Midlands. Image quality has been assessed on patient radiographs. Departmental radiologists were responsible for assessing radiographs taken within their hospital. Independent analysis was performed by a control radiologist. Film-screen processor sensitivity has been assessed on 48 film-screen processor combinations. Significant differences were observed between the nominally quoted sensitivities and the measured sensitivities. Only 26% of systems produced measured sensitivities within 10% of the nominal values. A four variable regression model, explaining 78% of the variance, provided the best description for the variation in patient dose. These variables were actual sensitivity, applied potential, generator waveform and radiographic quality. Four recommendations have been made to lower patient doses; these are: (1) an increase in applied potential to a minimum of 90 kVp; (2) a film-screen sensitivity of 400; (3) optimization of processor performance and (4) regular radiological audits to reduce repeat rates to a level of 5%. If all of these recommendations are followed, an estimated overall entrance surface dose saving of 53% would result. Changing the applied potential alone will see the variation in the mean entrance surface dose from non-gridded systems reduce from a factor of 4 to a factor of 2.

Changes in eating behavior after laparoscopic adjustable gastric banding: a systematic review of the literature.

This systematic review evaluates the current evidence base for eating behavior changes after laparoscopic adjustable gastric banding (LAGB). A literature search from 1990 to February 2010 was conducted to identify original studies that assessed eating behavior in adults who have undergone LAGB. Sixteen articles (14 separate studies) met inclusion criteria. Although strength of the evidence base was limited by observational study designs and methodological weaknesses, results suggest that positive changes in eating behavior occur after surgery, including reduced over-eating in response to emotional and situational cues. There is some evidence to suggest that uncontrolled eating behaviors persist in some individuals, and that this may be problematic for weight loss after surgery. Few studies examined the relationship between changes in eating behavior and weight loss; thus, optimal behavioral strategies for promoting positive weight outcomes remain unclear. Further interventional research addressing the inherent limitations of the current-evidence base is required to guide development of evidence-based management guidelines for LAGB in future.

Research methods for formal consensus development.

AIM This paper reviews three research methods for developing consensus. BACKGROUND Consensus statements and guidelines are increasingly used to clarify and standardise practice, and inform health policy, when relevant and rigorous evidence is lacking. Clinicians need to evaluate the quality of practice guidelines to determine whether to incorporate them into clinical practice or reject them. Formal methods of developing consensus provide a scientific method that uses expert panel members to evaluate current evidence and expert opinions to produce consensus statements for clinical problems. DATA SOURCES Online search for relevant literature was conducted in Medline and CINAHL. REVIEW METHODS A literature review of consensus, consensus development and research methods papers published in English in peer-reviewed journals. DISCUSSION The three methods of developing consensus discussed are the Delphi technique, nominal group technique and the consensus development conference. The techniques and their respective advantages are described, and examples from the literature are provided. The three methods are compared and a flowchart to assist researchers selecting an appropriate method is included. Online resources with information on the development and evaluation of clinical guidelines are reviewed. CONCLUSION This paper will help researchers to select an appropriate research method for developing consensus statements and guidelines. IMPLICATIONS FOR RESEARCH/PRACTICE When developing consensus guidelines for clinical practice, researchers should use a formal research method to ensure rigour and credibility.

A retrospective planning analysis comparing intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) using two optimization algorithms for the treatment of early‐stage prostate cancer

The primary aim of this study is to compare intensity modulated radiation therapy (IMRT) to volumetric modulated arc therapy (VMAT) for the radical treatment of prostate cancer using version 10.0 (v10.0) of Varian Medical Systems, RapidArc radiation oncology system. Particular focus was placed on plan quality and the implications on departmental resources. The secondary objective was to compare the results in v10.0 to the preceding version 8.6 (v8.6).

A systematic review of dietary intake after laparoscopic adjustable gastric banding

BACKGROUND   Laparoscopic adjustable gastric banding (LAGB) is currently one of the most popular surgical obesity treatments worldwide. Although dietary modification is recognised as a key factor in determining weight loss and health outcomes post surgery, existing evidence regarding changes in dietary intake after LAGB has not been systematically evaluated. This is essential for developing best-practice dietetic guidelines for the management of LAGB patients. The aim of this systematic review was to evaluate the current evidence base regarding changes in dietary intake after LAGB. METHODS   A literature search of Medline, EMBASE, Scopus, Cinahl and the Cochrane Library from 1990 to February 2010 was conducted to identify original studies that assessed dietary intake in adults who have undergone LAGB. RESULTS   Only 11 articles (10 separate studies) met inclusion criteria. Although the strength of the evidence base is limited by the small number of studies, observational study designs and methodological weaknesses, the results indicate that short-term positive changes occur post surgery, including reduced caloric intake, contributed to by reductions in fat, carbohydrate and protein intake. Issues including optimal macronutrient intake, diet quality and longer-term sustainability of reduced food intake remain largely unexplored. Because no dietary intervention studies were identified, evidence-based dietary strategies that may help optimise weight loss outcomes and other health outcomes remain unknown. CONCLUSIONS   There is a paucity of high-quality evidence regarding changes in dietary intake after LAGB. Further well-designed, dietary-based intervention research will be beneficial to better establish dietetic management guidelines for optimising outcomes for individuals who have LAGB.

Validation and use of the Newcastle Reflective Analysis Tool: a three‐year longitudinal study of RT students’ reflective journals

Freeform written personal development journals are used within the Radiation Therapy (RT) program at the University of Newcastle to promote reflection on practice. The journals are developed by students on completion of each semester based professional placement (clinical placement). To evaluate the level of reflection within journals the Newcastle Reflective Analysis Tool (NRAT) was developed. The NRAT allows for both narrow and broad classification of reflective writing, useful for formal and informal reflective writing assessments. This paper provides validation of the NRAT in the assessment of freeform reflective writing and its use in the assessment of reflection in RT student journals. The results also indicate the need to introduce interventions to foster students’ reflective writing ability within the RT program. As a result of these findings the Newcastle Reflective Inventories (NRI) have been developed. The NRIs are short form guided inventories aimed at assisting students with their reflective writing development.

Influence of dose reduction recommendations on changes in chest radiography techniques

A previous dosimetric study on chest radiography identified ways to reduce patient entrance surface dose (ESD). This present study was designed to monitor changes that had occurred in the use of applied potential and film-screen sensitivity, after a series of recommendations were issued. The study falls into two parts: (1) an assessment of the impact of the recommendations and (2) what factors were responsible for change. Where changes had occurred, exposure factors were collected for 30 patients per tube and the mean ESD was calculated for each tube. Intercomparison (r = 0.93, p < 0.001) was made between calculated and measured (TLDs) values of mean ESD for 10 X-ray units, to ensure that the calculated values provided accurate estimates of the new mean ESDs. 89% of units previously monitored for patient ESD now use average applied potentials greater than 90 kVp and 51% are using film-screen sensitivities of 400. The mean ESD has been reduced on average by 47%, from 0.15 mGy to 0.08 mGy. It has been estimated that the annual collective dose from diagnostic radiology procedures in 30 hospitals in the West Midlands has been reduced by a value in excess of 40 man Sv. Reasons for change could be attributed to some of the following factors: (a) a knowledge of dose levels in comparison with other centres; (b) personal contact with departments; (c) feedback in terms of results and dose savings and (d) positive encouragement to make changes.

Lateral cervical spine examinations: an evaluation of dose for grid and non-grid techniques

Abstract Purpose: Radiation doses have been monitored for a long time, as we are aware that radiation can produce biological effects. However, there is a limited amount of information available on patient dose from cervical spine examinations. In addition, the techniques used are variable between radiographic departments and even radiographers within one department. The difference in technique of particular concern is the use of radiographic grids. While it reduces scatter and improve image quality, the use of a grid demands increased exposure factors and dose to obtain the same optical density on the film. Method: This study investigated the range of doses for lateral cervical spine examinations in the Hunter and Sydney metropolitan regions of New South Wales, Australia. Radiation doses were calculated from X-ray tube output measurements and patient exposure parameters. Results: Differences in dose for 116 patients (53 non-grid, 63 grid) examined on 13 X-ray units were analysed. The study calculated the mean entrance surface dose for the non-grid system (228μGy) to be significantly lower at the 95% significance level than the mean entrance surface dose for the grid techniques (505μGy). However, the use of a grid for computed radiography systems did not produce any differences in dose with the use or non-use of a grid, while there was a three-fold increase for film-screen systems. Conclusion: The increased level of dose and the inherent air-gap nature of the lateral cervical spine examination raises severe doubt on the use of anti-scatter grids and the recommendation is that they should not be used.