Plan Evaluation Process Research Articles

Exploration of overlap volumes for radiotherapy plan evaluation with the aim of healthy tissue sparing

Purpose:Development of a novel interactive visualization approach for the exploration of radiotherapy treatment plans with a focus on overlap volumes with the aim of healthy tissue sparing. Methods:We propose a visualization approach to include overlap volumes in the radiotherapy treatment plan evaluation process. Quantitative properties can be interactively explored to identify critical regions and used to steer the visualization for a detailed inspection of candidates. We evaluated our approach with a user study covering the individual visualizations and their interactions regarding helpfulness, comprehensibility, intuitiveness, decision-making and speed. Results:A user study with three domain experts was conducted using our software and evaluating five data sets each representing a different type of cancer and location by performing a set of tasks and filling out a questionnaire. The results show that the visualizations and interactions help to identify and evaluate overlap volumes according to their physical and dose properties. Furthermore, the task of finding dose hot spots can also benefit from our approach. Conclusions:The results indicate the potential to enhance the current treatment plan evaluation process in terms of healthy tissue sparing.

Teacher Evaluation Processes that Lead to Professional Growth: The Role of the Principal as Perceived by Administrators and Teachers

This article aims at inspecting the perceptions of administrators and teachers regarding the role of the administrator in improving the teacher’s professional growth provided by the Armenian High schools in Beirut; Lebanon. It is also conducted to study, on one hand, the principals’ role in the teacher evaluation process, while on the other hand, to determine whether they are capable of improving teacher’s professional growth. Both quantitative and qualitative data were gathered from seven Armenian High schools in Lebanon. Quantitative data was gathered through Teacher Evaluation Profile (TEP), where N=10 administrators and N=50 teachers participated in the filling out the questionnaire; Qualitative data was gathered through interview questions, where N=7 administrators and N=14 teachers participated in the interviews. The results of the research conveys the role of the administrators in teacher evaluation process, in addition, it might help them plan evaluation process that helps the teacher’s professional growth.

Analysis of the treatment plan evaluation process in radiotherapy through eye tracking

Background and purposeTreatment plan evaluation is a clinical decision-making problem that involves visual search and analysis in a contextually rich environment, including delineated structures and isodose lines superposed on CT data. It is a two-step process that includes visual analysis and clinical reasoning. In this work, we used eye tracking methods to gain more knowledge about the treatment plan evaluation process in radiation therapy. Materials and methodsDose distributions on a single transverse slice of ten prostate cancer treatment plans were presented to eight decision makers. Their eye movements and fixations were recorded with an EyeLink1000 remote eye-tracker. Total evaluation time, dwell time, number and duration of fixations on pre-segmented areas of interest were measured. ResultsThe main structures receiving more and longer fixations (PTV, rectum, bladder) correspond to the main trade-offs evaluated in a typical prostate plan. Radiation oncologists made more fixations on the main structures compared to the medical physicists. Radiation oncologists fixated longer on the rectum when visited for the first time, while medical physicists fixated longer on the bladder. ConclusionOur results quantify differences in the visual evaluation patterns between radiation oncologists and medical physicists, which indicate differences in their decision making strategies.

Rapid implementation of the repair-misrepair-fixation (RMF) model facilitating online adaption of radiosensitivity parameters in ion therapy

Introduction: Treatment planning for ion therapy must account for physical properties of the beam as well as differences in the relative biological effectiveness (RBE) of ions compared to photons. In this work, we present a fast RBE calculation approach, based on the decoupling of physical properties and the ratio commonly used to describe the radiosensitivity of irradiated cells or organs.Material and methods: In the framework of the mechanistic repair-misrepair-fixation (RMF) model, the biological modeling can be decoupled from the physical dose. This was implemented into a research treatment planning system for carbon ion therapy.Results: The presented implementation of the RMF model is very fast, allowing online changes of . For example, a change of including a complete biological modeling and a recalculation of RBE for voxel takes 4 ms on a 4 CPU, 3.2 GHz workstation.Discussion and conclusion: The derived decoupling within the RMF model allows fast changes in , facilitating online adaption by the user. This provides new options for radiation oncologists, facilitating online variations of the radiobiological input parameters during the treatment plan evaluation process as well as uncertainty and sensitivity analyses.

Defining robustness protocols: a method to include and evaluate robustness in clinical plans

We aim to define a site-specific robustness protocol to be used during the clinical plan evaluation process. Plan robustness of 16 skull base IMPT plans to systematic range and random set-up errors have been retrospectively and systematically analysed. This was determined by calculating the error-bar dose distribution (ebDD) for all the plans and by defining some metrics used to define protocols aiding the plan assessment. Additionally, an example of how to clinically use the defined robustness database is given whereby a plan with sub-optimal brainstem robustness was identified. The advantage of using different beam arrangements to improve the plan robustness was analysed. Using the ebDD it was found range errors had a smaller effect on dose distribution than the corresponding set-up error in a single fraction, and that organs at risk were most robust to the range errors, whereas the target was more robust to set-up errors. A database was created to aid planners in terms of plan robustness aims in these volumes. This resulted in the definition of site-specific robustness protocols. The use of robustness constraints allowed for the identification of a specific patient that may have benefited from a treatment of greater individuality. A new beam arrangement showed to be preferential when balancing conformality and robustness for this case. The ebDD and error-bar volume histogram proved effective in analysing plan robustness. The process of retrospective analysis could be used to establish site-specific robustness planning protocols in proton therapy. These protocols allow the planner to determine plans that, although delivering a dosimetrically adequate dose distribution, have resulted in sub-optimal robustness to these uncertainties. For these cases the use of different beam start conditions may improve the plan robustness to set-up and range uncertainties.

Study of decision framework of wind farm project plan selection under intuitionistic fuzzy set and fuzzy measure environment

Project selection plays an important role in the entire life cycle of wind farm project and the multi-criteria decision making (MCDM) methods are very important in the whole wind farm project plan selection process. There are problems in the present MCDM methods decrease evaluation quality of the wind farm project plans: first, the information loss exists in the wind farm project plan evaluation process. Second, it is difficult to satisfy the independent assumption of the multi-criteria decision making methods used in the wind farm project plan evaluation in fact. Third, the compensatory problem of performance scores of the wind farm project plans is processed unreasonably. Hence the innovation points of this paper are as follows: first, the intuitionistic fuzzy numbers are used instead of fuzzy numbers or numerical values to reflect the experts’ intuitive preferences to decrease the probability of information loss; second, the fuzzy measure is used to rate the important degrees of criteria in order to avoid the independent assumption and to increase the reasonability; third, the partial compensatory problem of performance scores is well processed by using intuitionistic fuzzy Choquet (IFC) operator and generalized intuitionistic fuzzy ordered geometric averaging (GIFOGA) operator. These operators can deal with the compensatory performance scores and non-compensatory performance scores respectively. Finally, a case study demonstrates the effectiveness of decision framework.

A new plan quality index for nasopharyngeal cancer SIB IMRT

A new plan quality index integrating dosimetric and radiobiological indices was proposed to facilitate the evaluation and comparison of simultaneous integrated boost (SIB) intensity modulated radiotherapy (IMRT) plans for nasopharyngeal cancer (NPC) patients.Ten NPC patients treated by SIB-IMRT were enrolled in the study. Custom software was developed to read dose–volume histogram (DVH) curves from the treatment planning system (TPS). A plan filtering matrix was introduced to filter plans that fail to satisfy treatment protocol. Target plan quality indices and organ at risk (OAR) plan quality indices were calculated for qualified plans. A unique composite plan quality index (CPQI) was proposed based on the relative weight of these indices to evaluate and compare competing plans. Plan ranking results were compared with detailed statistical analysis, radiation oncology quality system (ROQS) scoring results and physician's evaluation results to verify the accuracy of this new plan quality index.The average CPQI values for plans with OAR priority of low, normal, high, and PTV only were 0.22 ± 0.08, 0.49 ± 0.077, 0.71 ± 0.062, and −0.21 ± 0.16, respectively. There were significant differences among these plan quality indices (One-way ANOVA test, p < 0.01). This was consistent with statistical analysis, ROQS results and physician's ranking results in which 90% OAR high plans were selected.Plan filtering matrix was able to speed up the plan evaluation process. The new matrix plan quality index CPQI showed good consistence with physician ranking results. It is a promising index for NPC SIB-IMRT plan evaluation.

SU‐C‐211‐06: A New Treatment Plan Quality Index for NPC SIB‐IMRT

Purpose: To proposed a new plan quality index to fasten the evaluation and comparison of the competing multi‐isocenter SIB‐IMRT (intensity modulated radiotherapy with simultaneous integrated boost) plans for NPC (Nasopharyngeal Cancer) patients. Methods: Multi‐isocenter SIB‐IMRT plans at 2.5 Gy/fraction for GTV (gross tumor volume) and 2.0 Gy/fraction for CTVs (clinical tumor volume) with different OAR (Organ at Risk) constraint levels were generated with BrainSCAN 5.2 and m3 MLC. DVH (dose volume histogram) were read from treatment planning system by custom software (written with Matlab 7.1). Various items was read and calculated. A plan filter matrix with variable plan quality items was introduced to filter plans that fail to satisfy the customed criteria. PTV plan quality indices including TC (target coverage), V93, HI (homogeneity index), TCP (tumor control probability), and OAR plan quality indices including NTCP (normal tissue control probability), V26, and V32 of parotids were calculated for qualified plans. A unique composite plan quality index (CPQI) was proposed based on the relative weight of these indices to evaluate and compare plans. Plan ranking results were compared with physician's evaluation results to verify the accuracy of this new plan quality index. Results: The average CPQI values for plans with OAR constraint level of low, normal, high, and PTV only were 0.22±0.08, 0.49±0.077, 0.71±0.062, and −0.21±0.16, respectively. There were significant differences between these plan quality indices (One‐way ANOVA test, p&lt;0.01). This consistent with physician's ranking results with 99.3% OAR high plans accepted. Conclusions: Plan filter matrix was able to fasten the plan evaluation process. The new matrix plan quality index CPQI showed good consistence with physician ranking results, it is a promising tool for optimal plan selection.

SU‐E‐T‐654: Calculation of Cumulative Biological Effective Dose Distributions for Multimodality Treatment Regimes

Purpose: Evidence has recently been reported supporting the role of stereotactic body radiotherapy (SBRT) as a supplemental treatment option in the form of a boost or salvage reirradiation following conventional radiotherapy. It may therefore be desirable to augment the process of physical dose summation in the cumulative plan evaluation process by constructing corresponding biological effective dose (BED) distributions that incorporate the biological effects of the different dose fractionation schemes required for multimodality treatments. To that end, we developed a computational process for calculating cumulative BED distributions for patients receiving conventional radiotherapy followed by SBRT. Methods: We developed a program designed to accept two DICOM dose matrices, as calculated in standard treatment planning systems, and calculate the BED at each matrix element obeying the dose per fraction dependence in the BED formalism. It then calculates the cumulative BED distribution for multimodality treatment regimes by matrix summation and outputs the result in DICOM format. Two clinical head and neck IMRT cases (large field (2.13Gy × 33) and small field (2Gy × 32)) were evaluated as part of a pilot study to demonstrate the overall feasibility of the calculation scheme. Following clinical IMRT planning, each case was planned in a mock SBRT scenario (6Gy × 5) where a smaller planning volume was drawn to simulate a boost or salvage reirradiation. The clinical IMRT and mock SBRT dose matrices were then processed to generate cumulative BED distributions. Results: Our computational process was successful in producing cumulative BED distributions. For the large field IMRT case, the overall BED distribution beyond the initial treated volume was dominated by the initial IMRT course, whereas clear additive increase in the BED distribution beyond the initial treated volume was evident in the small field case. Conclusions: Cumulative BED distributions may reveal useful clinical information during plan evaluation.

Improving the Business Plan Evaluation Process: the Role of Intangibles

One of the main objectives of the European MUSING project is to design and test software tools in order to support the activities of small and medium sized businesses. In this paper we examine financial risk management and, more specifically, the self-assessment of business plans. The role of intangible assets is discussed, and we report on how intangible assets can be collected, how they can be represented, taking into account their semantic relationships, and how they can be used to build an analytical tool for business plans. The basic technology embedded in the tool is the construction of classification trees, a well-known technique in inductive learning. We show how using knowledge of intangible assets can improve the construction of the classifier, as proved by the testing carried out so far.

Dosimetric risk estimates of radiation-induced malignancies after intensity modulated radiotherapy

The increasing popularity of intensity-modulated radiotherapy (IMRT) stems from its ability to generate a more conformal plan than hitherto possible with conventional planning. As a result, IMRT is in widespread use across diverse indications. However, the inherent nature of IMRT delivery makes it monitor unit inefficient and leads to increased normal tissue integral dose. This in turn may result in an increased risk of radiation-induced second malignancies. To calculate the risk of second malignancy post-IMRT. Observational study in a tertiary care institute. Eighteen previously untreated patients with head and neck cancers (n = 10) and prostate cancer (n = 8) were selected. In these patients, selected infield organs around the planning target volume were contoured, viz. brain and thyroid in patients with head and neck cancer and bladder, rectum and small intestine in patients with carcinoma prostate. The estimates of radiation-induced malignancies in these organs and the whole of the body were derived using the concept of Organ Equivalent Dose. Descriptive statistics (SPSS version 12). The modal estimated incidence of radiation-induced malignancies was 129.87, 1.4, 0.10, 3.42, 7.789 and 129.85 per 10,000 person-years for the brain, thyroid, bladder, rectum, small intestine and whole body respectively. The estimated risk of radiation-induced malignancies in the thyroid and rectum was similar to the available literature, while the risk for bladder carcinomas was lower than that reported. However, the calculated risk of radiation-induced tumors of the brain was more than that reported with conventional radiation therapy. We propose that estimation of the risk of radiation-induced malignancies should be a part of the plan evaluation process and special care should be taken before using this modality in young patients with benign tumors in the head and neck region.

A generalized a priori dose uncertainty model of IMRT delivery

Multileaf collimator-based intensity modulated radiation therapy (IMRT) is complex because each intensity modulated field consists of hundreds of subfields, each of which is associated with an intricate interplay of uncertainties. In this study, the authors have revised the previously introduced uncertainty model to provide an a priori accurate prediction of dose uncertainty during treatment planning in IMRT. In the previous model, the dose uncertainties were categorized into space-oriented dose uncertainty (SOU) and nonspace-oriented dose uncertainty (NOU). The revised model further divided the uncertainty sources into planning and delivery. SOU and NOU associated with a planning system were defined as inherent dose uncertainty. A convolution method with seven degrees of freedom was also newly applied to generalize the model for practical clinical cases. The model parameters were quantified through a set of measurements, accumulated routine quality assurance (QA) data, and peer-reviewed publications. The predicted uncertainty maps were compared with dose difference distributions between computations and 108 simple open-field measurements using a two-dimensional diode array detector to verify the validity of the model parameters and robustness of the generalized model. To examine the applicability of the model to overall dose uncertainty prediction in IMRT, a retrospective analysis of QA measurements using the diode array detector for 32 clinical IM fields was also performed. A scatter diagram and a correlation coefficient were employed to investigate a correlation of the predicted dose uncertainty distribution with the dose discrepancy distribution between calculation and delivery. In addition, a gamma test was performed to correlate failed regions in dose verification with the dose uncertainty map. The quantified model parameters well correlated the predicted dose uncertainty with the probable dose difference between calculations and measurements. It was visually validated with the scatter diagrams. The average correlation coefficient between uncertainty and dose difference of 108 verification measurements was 0.80 +/- 0.04, indicating a strong linear correlation. In the clinical IM field studies, the dose uncertainty map mimicked the probable dose difference distribution. The average correlation coefficient between the overall dose uncertainty and the dose difference of 32 QA measurements (total 13 184 comparison points) was 0.75 +/- 0.07, which also indicated a strong linear correlation between them. The failed regions of the gamma test remarkably corresponded to relatively high dose uncertainty. In conclusion, the dose uncertainty map was able to highlight high dose uncertainty regions, where more care should be taken during the treatment plan. The a priori accurate prediction of dose uncertainty in IMRT will significantly improve the treatment plan evaluation process, thus improving the quality of radiation treatments.

Monitoring the sustainability of Brownfield redevelopment projects. The Redevelopment Assessment Framework (RAF)

Redevelopment of brownfield land is regarded as an essential component of the achievement of a sustainable urban regeneration, and is thus enshrined in a number of key urban policy frameworks (DETR 2000; ODPM 2004a). Brownfield redevelopment is considered to be de facto sustainable and presented as a headline sustainability indicator (DETR 1999). However, many examples exist where redevelopment of brownfield sites has not been sustainable, as it failed to assess the environmental, social, economic and physical impacts holistically, as well as to consider the long-term impacts of brownfield redevelopment projects (BRPs) in general. It is therefore important to develop and implement a Redevelopment Assessment Framework (RAF), that addresses sustainability throughout a site's life cycle of land use. Such a framework has been developed, and is discussed here. The RAF utilises sustainability indicators, while taking into account relevant existing UK planning evaluation processes and other sources of information, thus making it applicable in practice. The RAF embodies a participatory approach which offers greater communication and understanding between relevant stakeholders, and therefore also offers educational and communications benefits. A description of the RAF, a ctitical analysis of its intended use, and a discussion of benefits and potential barriers, are provided below. © 2005 EPP Publications Ltd.

Generating and evaluating alternative regional development plans

The generation of alternative spatial regional development plans is one of the two most important steps in a comprehensive rational planning process. The other step is the plan-evaluation process, which enables us to rank-order the alternative plans and, subsequently, to make a rational selection of the ‘best plan’. In order to generate the set of alternative spatial plans, it is necessary to identify and define adequately and clearly the goals and objectives that the plan is designed to serve. In this paper we report on an actual planning process in which development plans were generated and evaluated, and then the best plan was selected and prepared for the Northern (or Galilee) region of Israel. The Northern region is one of the most fascinating regions in Israel in terms of the composition of its residents, its settlements, and its landscape. The region is well endowed with breathtaking views and a wealth of natural resources. It is therefore necessary for the preferred spatial development plan both t...