Enhancing target visualization and reducing set-up errors in image-guided radiotherapy (IGRT) are issues faced when trying to implement more conformal and partial bladder techniques. This review ...examines the evidence available pertaining to the clinical use of Lipiodol and gold fiducials for IGRT for bladder cancer.
Nine published articles relating to the feasibility of using Lipiodol injections or gold fiducial markers in IGRT for bladder patients were recruited from a database search strategy. Set-up errors were evaluated in addition to the stability and visibility of each on verification imaging. Adverse reactions from the insertion of each method were also assessed.
Both Lipiodol and gold fiducials have the potential to remain stable and visible in the bladder, however, fading, washout and seed loss was also reported. Set-up errors can be reduced by using Lipiodol or fiducial registration when compared to other registration techniques. Adverse reactions reported were minimal for each.
Current evidence suggests that Lipiodol injections and gold fiducial markers present as promising and highly accurate methods of overcoming interfraction bladder motion in IGRT.
Effective K-12 integrated STEM education should reflect an intentional effort to adequately represent and facilitate each of its component disciplines in a meaningful way. However, most research in ...this space has been conducted within the context of science classrooms, ignoring mathematics. Also missing from the literature is research that examines the level of cognitive demand required from mathematical tasks present within integrated STEM lessons. In order to seek insight pertaining to this gap in the literature, we sought to better understand how science teachers use mathematics within K-12 integrated STEM instruction. We used an explanatory sequential mixed methods research design to explore the enactment of mathematics in integrated STEM lessons that focus on physical, earth, and life science content. We first examined 2030 sets of video-recorded classroom observation scores generated from the 10-item STEM Observation Protocol (STEM-OP) designed for observing integrated STEM education in K-12 classrooms. We compared the STEM-OP scores of classroom observations that included mathematics with those that did not. This quantitative analysis was followed by a closer, more in-depth qualitative examination of how mathematics was employed, focusing on the degree of cognitive demand. To do this, we coded and analyzed transcripts from video-recorded classroom observations in which mathematical content was present. Our study yielded two main findings about mathematics in integrated STEM lessons: (1) the presence of mathematical content resulted in higher STEM-OP scores on nearly all items, and (2) mathematical tasks within these lessons were categorized as requiring mainly low levels of cognitive demand from students. This study highlights the need for the increased inclusion of mathematical tasks in integrated STEM teaching. Implications for including higher-order mathematical thinking within integrated STEM teaching are discussed.
We present results from a study evaluating the utility of supervised machine learning to classify single particle ultraviolet laser-induced fluorescence (UV-LIF) signatures to investigate airborne ...primary biological aerosol particle (PBAP) concentrations in a busy, multifunctional building using a Multiparameter Bioaerosol Spectrometer. First we introduce and demonstrate a gradient boosting ensemble decision tree algorithm’s ability to accurately classify laboratory generated PBAP samples into broad taxonomic classes with a high level of accuracy. We then develop a framework to appraise the classification accuracy and performance using the Hellinger distance metric to compare product parameter probability density function similarity; this framework showed that key training classes were sufficiently different in terms of particle fluorescence and morphology to facilitate classification. We also demonstrate the utility of including advanced morphological parameters to minimise inter-class conflation and improve classification confidence, where relying on the fluorescent spectra alone would likely result in misattribution. Finally, we apply these methods to ambient data collected within a large multi-functional building where ambient bacterial- and fungal-like classes were identified to display trends corresponding to human activity; fungal-like classes displayed a consistent diurnal trend with a maximum at midday and hourly peaks correlating to movements within the building; bacteria-like aerosol displayed complex, episodic events during opening hours. All PBAP classes fell to low baseline concentrations when the building was unoccupied overnight and at weekends.
Study Type – Therapy (case series)
Level of Evidence 4
What's known on the subject? and What does the study add?
High doses of radiotherapy correspond to higher cure rates. Most radiation centers in ...the UK and Australia limit prescription doses to 74–78 Gy and do not use IGRT and IMRT for all patients.
The combination of IGRT and IMRT can limit the rectum and bladder to low doses allowing doses above 78 Gy to be delivered, including pelvic lymph node treatment, with low side effects. This paper provides a detailed guide of planning technique and expected toxicity to enable implementation of similar dose escalated prostate programmes in other radiotherapy centres.
OBJECTIVE
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To determine the short‐term side‐effects of dose‐escalated image‐guided intensity‐modulated radiation therapy (IG‐IMRT) for the definitive treatment of prostate cancer.
PATIENTS AND METHODS
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Eligible patients were treated at doses >78 Gy and with definitive intent.
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Patients from a prospective database with International Prostate Symptom Score (IPSS) and Common Terminology Criteria for Adverse Events, version 3.0 (CTCAE) toxicity were recorded weekly during treatment and at follow‐up.
RESULTS
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In all, 101 patients were included, with doses ranging from 78.3 to 84 Gy (median = 79.3).
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The median (range) age was 71 (46–83) years; 60% received concurrent androgen deprivation and 35% had pelvic lymph node treatment.
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The median (range) IPSS at baseline, on treatment and at first follow‐up were 7 (0–35), 15 (1–34) and 6 (0–30), respectively.
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The percentages of patients with grade 2 or higher toxicity during treatment, at 3 months and at 2 years were, respectively, 6.9%, 1% and 2% for gastrointestinal symptoms and 39%, 6.9% and 3% for genitourinary symptoms.
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There was no significant difference in gastrointestinal toxicity during treatment (P= 0.860) or at 3 months (P= 0.334) between patients with and without lymph node treatment.
CONCLUSION
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Doses >78 Gy delivered using daily image guidance and IMRT are well tolerated, and by 3 months short‐term side‐effects have normalized for the majority of patients.
Because of the steep dose gradient associated with dose-escalated intensity-modulated radiation therapy, interfraction motion and variation in rectal volume may result in the rectum receiving a ...larger dose than predicted at treatment planning. This study aims to quantify the variation in daily rectal dose-volume histograms (DVHs) from the treatment plan and to discuss the potential clinical significance of this variation.
Daily cone beam computed tomography scans of nine patients treated with definitive prostate intensity-modulated radiation therapy were collected. The daily dose distribution to the rectum was calculated retrospectively. The variation between the planned and on-treatment rectal DVHs was determined using Friedman tests with post hoc analysis and Wilcoxon matched-pairs tests. The on-treatment DVHs were compared with dose-volume constraints (DVCs) to assess the potential clinical significance of this variation using Wilcoxon signed-rank tests.
Significant variation (P < .05) was observed between the planned and on-treatment DVHs. The DVCs for the volume receiving 50 Gy (V50), V60, and V65 were adhered to. The mean V70 and V75 values were above the DVC; however, this variation was not statistically significant.
The initial treatment plan does not accurately represent the dose received by the rectum on treatment. Investigation into the most effective rectal protocol is recommended to reduce the likelihood of these variations occurring on a daily basis.
With margin reduction common in head and neck radiotherapy, it is critical that the dosimetric effects of setup deviations are quantified. With past studies focusing on the quantification of ...positional and volumetric changes of organs at risk (OARs), this study aimed to measure the dose delivered to these the parotid gland (PG) and pharyngeal constrictor muscles (PCMs) using cone beam computed tomography (CBCT). Furthermore, this investigation sought to establish a potential time trend of change in dose delivered to target volumes secondary to ascertaining the need for daily image guidance (IG) to reduce the dose burden to these important OARs. Intensity modulated radiotherapy (IMRT) plans for 5 locally advanced head and neck patients׳ plans were created and mapped to weekly CBCTs. Each plan was recalculated without heterogeneity correction allowing for dosimetric comparison. Dosimetric endpoints recorded to assess the effect of positional variation were as per ICRU 83 and included D
and D
for the target volumes, mean dose (MD) and V
for the PGs, and V
and MD for the PCMs. Results were deemed statistically significant if p < 0.05. No significant time trends were established for these OARs. A significant decrease in V
was observed for all PCMs (p < 0.001) on all CBCTs relative to the original plan. Regarding target volumes, a highly significant decrease in MD (MD = 20Gy, CI: -20.310 to -19.820) in D
of the high-dose planning target volume (PTV 70Gy; PTVD
= 70Gy) for case 3 was found (p ≤ 0.001). A nonpredictable, yet significant dosimetric effect was found. A clinically acceptable balance must be achieved between OAR dosimetry and target coverage as can be achieved by frequent IG.
Stereotactic body radiation therapy (SBRT) delivers a high biologically effective dose while minimizing toxicities to surrounding tissues. Within the scope of clinical trials and local practice, ...there are inconsistencies in dosimetrics used to evaluate plan quality. The purpose of this critical review was to determine if dosimetric parameters used in SBRT plans have an effect on local control (LC), overall survival (OS), and toxicities. A database of relevant trials investigating SBRT for patients with early-stage non-small cell lung cancer was compiled, and a table of dosimetric variables used was created. These parameters were compared and contrasted for LC, OS, and toxicities. Dosimetric end points appear to have no effect on OS or LC. Incidences of rib fractures correlate with a lack of dose-volume constraints (DVCs) reported. This review highlights the great disparity present in clinical trials reporting dosimetrics, DVCs, and toxicities for lung SBRT. Further evidence is required before standard DVCs guidelines can be introduced. Dosimetric end points specific to stereotactic treatment planning have been proposed but require further investigation before clinical implementation.
The established dosimetric benefits of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy have lead to their increased use in prostate radiotherapy. Complimenting these ...techniques, volumetric image guidance has supported increased positional accuracy. In addition, 3-dimensional image guidance has also allowed for assessment of potential dosimetric variation that can be attributed to a deformation of either internal or external structures, such as rectal distension or body contour. Compounding these issues is the variation of tissue density through which the new field position passes and also the variation of dose across a modulated beam. Despite the growing level of interest in this area, there are only a limited number of articles that examine the effect of a variation in beam path length, particularly across a modulated field. IMRT and volumetric-modulated radiation therapy (VMAT) fields are dynamic in nature, and the dose gradient within these fields is variable. Assessment of variation of path length away from the beam׳s central axis and across the entire field is vital where there is considerable variation of dose within the field, such as IMRT and VMAT. In these cases, reliance on the traditional central axis to focus skin distances is no longer appropriate. This article discusses these more subtle challenges that may have a significant clinical effect if left unrecognized and undervalued.
This study is aimed to test a postprostatectomy volumetric-modulated arc therapy (VMAT) planning class solution. The solution applies to both the progressive resolution optimizer algorithm version 2 ...(PRO 2) and the algorithm version 3 (PRO 3), addressing the effect of an upgraded algorithm. A total of 10 radical postprostatectomy patients received 68 Gy to 95% of the planning target volume (PTV), which was planned using VMAT. Each case followed a set of planning instructions; including contouring, field setup, and predetermined optimization parameters. Each case was run through both algorithms only once, with no user interaction. Results were averaged and compared against Radiation Therapy Oncology Group (RTOG) 0534 end points. In addition, the clinical target volume (CTV) D100, PTV D99, and PTV mean doses were recorded, along with conformity indices (CIs) (95% and 98%) and the homogeneity index. All cases satisfied PTV D95 of 68 Gy and a maximum dose < 74.8 Gy. The average result for the PTV D99 was 64.1 Gy for PRO 2 and 62.1 Gy for PRO 3. The average PTV mean dose for PRO 2 was 71.4 Gy and 71.5 Gy for PRO 3. The CTV D100 average dose was 67.7 and 68.0 Gy for PRO 2 and PRO 3, respectively. The mean homogeneity index for both algorithms was 0.08. The average 95% CI was 1.17 for PRO 2 and 1.19 for PRO 3. For 98%, the average results were 1.08 and 1.12 for PRO 2 and PRO 3, respectively. All cases for each algorithm met the RTOG organs at risk dose constraints. A successful class solution has been established for prostate bed VMAT radiotherapy regardless of the algorithm used.
Primary biological aerosol particles (PBAPs) are an abundant subset of atmospheric aerosol particles which comprise viruses, bacteria, fungal spores, pollen, and fragments such as plant and animal ...debris. The abundance and diversity of these particles remain poorly constrained, causing significant uncertainties for modelling scenarios and for understanding the potential implications of these particles in different environments. PBAP concentrations were studied at four different sites in the United Kingdom (Weybourne, Davidstow, Capel Dewi, and Chilbolton) using an ultraviolet light-induced fluorescence (UV-LIF) instrument, the Wideband Integrated Bioaerosol Spectrometer (WIBS), versions 3 and 4.Using hierarchical agglomerative cluster (HAC) analysis, particles were statistically discriminated. Fluorescent particles and clusters were then analysed by comparing to laboratory data of known particle types, assessing their diurnal variation and examining their relationship to the meteorological variables temperature, relative humidity, wind speed, and wind direction. Using local land cover types, sources of the suspected fluorescent particles and clusters were then identified.Most sites exhibited a wet discharged fungal spore dominance, with the exception of one site, Davidstow, which had higher concentrations of bacteria, suggested to result from the presence of a local dairy factory and farm. Differences were identified as to the sources of wet discharged fungal spores, with particles originating from arable and horticultural land at Chilbolton, and improved grassland areas at Weybourne. Total fluorescent particles at Capel Dewi were inferred to comprise two sources, with bacteria originating from the broadleaf and coniferous woodland and wet discharged fungal spores from nearby improved grassland areas, similar to Weybourne.The use of the HAC method and a higher fluorescence threshold (9 standard deviations instead of 3) produced clusters which were considered to be biological following the complete analysis. More published data and information on the reaction of different speciated biological particle types to fluctuations in meteorological conditions, such as relative humidity and temperature, would aid particle type characterisation in studies such as this.
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