Small field measurements using electronic portal imaging device.

Purpose/Objective Small-field measurement poses challenges. Although many high-resolution detectors are commercially available, the EPID for small-field dosimetry remains underexplored. This study aimed to evaluate the performance of EPID for small-field measurements and to derive tailored correction factors for precise small-field dosimetry verification. Material/Methods Six high-resolution radiation detectors, including W2 and W1 plastic scintillators, Edge-detector, microSilicon, microDiamond and EPID were utilized. The output factors, depth doses and profiles, were measured for various beam energies (6 MV-FF, 6 MV-FFF, 10 MV-FF, and 10 MV-FFF) and field sizes (10 x 10 cm2, 5 x 5 cm2, 4 x 4 cm2, 3 x 3 cm2, 2 x 2 cm2, 1 x 1 cm2, 0.5 x 0.5 cm2) using a Varian Truebeam linear accelerator. During measurements, acrylic plates of appropriate depth were placed on the EPID, while a 3D water tank was used with five-point detectors. EPID measured data were compared with W2 plastic scintillator and measurements from other high-resolution detectors. The analysis included percentage deviations in output factors, differences in percentage for PDD and for the profiles, FWHM, maximum difference in the flat region, penumbra, and 1D gamma were analyzed. The output factor and depth dose ratios were fitted using exponential functions and fractional polynomial fitting in STATA 16.2, with W2 scintillator as reference, and corresponding formulae were obtained. The established correction factors were validated using two Truebeam machines. Results When comparing EPID and W2-PSD across all field-sizes and energies, the deviation for output factors ranged from 1% to 15%. Depth doses, the percentage difference beyond dmax ranged from 1% to 19%. For profiles, maximum of 4% was observed in the 100% - 80% region. The correction factor formulae were validated with two independent EPIDs and closely matched within 3%. Conclusion EPID can effectively serve as small-field dosimetry verification tool with appropriate correction factors.

Early occlusal caries detection using targeted fluorescent starch nanoparticles.

OBJECTIVES: We have previously shown fluorescent cationic starch nanoparticles (FCSNs) penetrate enamel surface porosity of active carious lesions, potentially aiding their detection. Here, we evaluate the in vitro diagnostic accuracy of FCSNs in detecting occlusal caries compared to histologic reference standard. METHODS: 100 extracted human teeth were selected with sound (50), or either non-cavitated (25) or cavitated (25) lesions. A region of interest (ROI) on the occlusal surface was assessed for fluorescence by two independent examiners, after immersion in FCSN solution, water rinse, and illumination by dental curing lamp viewed through orange UV-filter glasses. ROIs were sectioned and evaluated by histology (Downer Criteria) as a gold standard for caries presence. Cohen's Kappa was determined for inter- and intra-examiner agreement, and sensitivity, specificity, and area under the curve of Receiver Operator Curves (ROCAUC) were calculated. The analysis was repeated for the subset of "early" lesions, defined as being limited to enamel. RESULTS: FCSN use resulted in substantial inter-user (k=0.74±0.07), and high intra-user agreement (k=0.80±0.06; 0.94±0.03, by examiner). Sensitivity, specificity and ROCAUC for FCSNs were 88.9%; 94.6%; 0.92±0.06 for all, and 76.9%, 94.6%, and 0.86±0.10 for early lesions. In post hoc analysis, sensitivity seemed to be greater with the FCSN than the expert visual exam, particularly for early lesions. CONCLUSIONS/CLINICAL SIGNIFICANCE: FCSNs are a reproducible and accurate novel technology for occlusal caries detection, with high sensitivity and specificity compared to histology. Future clinical validation is necessary. FCSNs can improve early caries detection and shift treatment towards non-invasive approaches, improving oral health.

Using natural language processing to compare task-specific verbal cues in coached versus noncoached cardiac arrest teams during simulated pediatrics resuscitation.

OBJECTIVES: Coaches improve cardiopulmonary (CPR) outcomes in real-world and simulated settings. To explore verbal feedback that targets CPR quality, we used natural language processing (NLP) methodologies on transcripts from a published pediatric randomized trial (coach vs. no coach in simulated CPR). Study objectives included determining any differences by trial arm in (1) overall communication and (2) metrics over minutes of CPR and (3) exploring overall frequencies and temporal patterns according to degrees of CPR excellence. METHODS: A human-generated transcription service produced 40 team transcripts. Automated text search with manual review assigned semantic category; word count; and presence of verbal cues for general CPR, compression depth or rate, or positive feedback to transcript utterances. Resulting cue counts per minute (CPM) were corresponded to CPR quality based on compression rate and depth per minute. CPMs were compared across trial arms and over the 18 min of CPR. Adaptation to excellence was analyzed across four patterns of CPR excellence determined by k-shape methods. RESULTS: Overall coached teams experienced more rate-directive, depth-directive, and positive verbal cues compared with noncoached teams. The frequency of coaches' depth cues changed over minutes of CPR, indicating adaptation. In coached teams, the number of depth-directive cues differed among the four patterns of CPR excellence. Noncoached teams experienced fewer utterances by type, with no adaptation over time or to CPR performance. CONCLUSION: NLP extracted verbal metrics and their patterns in resuscitation sessions provides insight into communication patterns and skills used by CPR coaches and other team members. This could help to further optimize CPR training, feedback, excellence, and outcomes.

Machine learning to extract communication and history-taking skills in OSCE transcripts.

OBJECTIVES: Observed Structured Clinical Exams (OSCEs) allow assessment of, and provide feedback to, medical students. Clinical examiners and standardised patients (SP) typically complete itemised checklists and global scoring scales, which have known shortcomings. In this study, we applied machine learning (ML) to label some communication skills and interview content information in OSCE transcripts and to compare several ML methodologies by performance and transferability. METHODS: One-hundred and twenty-one transcripts of two OSCE scenarios were manually annotated per utterance across 19 communication skills and content areas. Utterances were converted to two types of numeric sentence vector representations and were paired with three types of ML algorithms. First, ML models (MLMs) were evaluated using a five K-fold cross-validation technique on all transcripts in one scenario to generate precision and recall, and their harmonic mean, F1 scores. Second, ML models were trained on all 101 transcripts from scenario 1 and tested for transferability on 20 scenario 2 transcripts. RESULTS: Performance testing in the K-fold cross-validation demonstrated relatively high mean F1 scores: median 0.87 and range 0.53-0.98 across all 19 labels. Transferability testing demonstrated success: F1 median 0.76 and range 0.46-0.97. The combination of a bi-directional long short-term memory neural network (biLSTM) algorithm with GenSen numeric sentence vector representations was associated with greater F1 scores across both performance and transferability (P < .005). CONCLUSIONS: We report the first application of ML in the context of student-SP OSCEs. We demonstrated that several MLMs automatically labelled OSCE transcripts for a range of interview content and some clinical communications skills. Some MLMs achieved greater performance and transferability. Optimised MLMs could provide automated and accurate assessment of OSCEs with potential to track student progress and identify areas for further practice.

Validation of Three-dimensional Electronic Portal Imaging Device-based PerFRACTION™ Software for Patient-Specific Quality Assurance.

PURPOSE: PerFRACTION™ is a three-dimensional (3D) in vivo electronic portal imaging device-based dosimetry software. To validate the software, three phantoms with different inserts (2D array, ionization chamber, and inhomogeneity materials) were constructed to evaluate point dose and fluence map. MATERIALS AND METHODS: Phantoms underwent independent computed tomography simulation for planning and received repetitive fractions of volumetric modulated arc therapy, simulating prostate treatment. Fluence and absolute point dose measurements, PerFRACTION™ reconstructed doses, and the dose predictions of the planning system were compared. RESULTS: There was concordance between ionization chamber and PerFRACTION™ 3D absolute point dose measurements. Close agreement was also obtained between X- and Y-axis dose profiles with PerFRACTION™ calculated doses, MapCHECK measured doses, and planning system predicted doses. Setup shifts significantly influenced 2D gamma passing rates in PerFRACTION™ software. CONCLUSIONS: PerFRACTION™ appears reliable and valid under experimental conditions in air and with phantoms.

Radiotherapy utilization in developing countries: An IAEA study.

BACKGROUND: The planning of national radiotherapy (RT) services requires a thorough knowledge of the country's cancer epidemiology profile, the radiotherapy utilization (RTU) rates and a future projection of these data. Previous studies have established RTU rates in high-income countries. METHODS: Optimal RTU (oRTU) rates were determined for nine middle-income countries, following the epidemiological evidence-based method. The actual RTU (aRTU) rates were calculated dividing the total number of new notifiable cancer patients treated with radiotherapy in 2012 by the total number of cancer patients diagnosed in the same year in each country. An analysis of the characteristics of patients and treatments in a series of 300 consecutive radiotherapy patients shed light on the particular patient and treatments profile in the participating countries. RESULTS: The median oRTU rate for the group of nine countries was 52% (47-56%). The median aRTU rate for the nine countries was 28% (9-46%). These results show that the real proportion of cancer patients receiving RT is lower than the optimal RTU with a rate difference between 10-42.7%. The median percent-unmet need was 47% (18-82.3%). CONCLUSIONS: The optimal RTU rate in middle-income countries did not differ significantly from that previously found in high-income countries. The actual RTU rates were consistently lower than the optimal, in particular in countries with limited resources and a large population.

Patient perspectives regarding the value of total skin electron beam therapy for cutaneous T-cell lymphoma/mycosis fungoides: a pilot study.

PURPOSE: Cutaneous T-cell lymphoma (CTCL) represents a group of lymphoid malignancies involving the skin with mycosis fungoides being most common. This prospective study was initiated to evaluate perceptions of total skin electron beam therapy (TSEBT) by patients with mycosis fungoides who had failed at least 3 prior therapies. MATERIALS AND METHODS: Before the start of TSEBT, at 1 month and 6 months after the completion of treatment, patients completed an anonymous questionnaire for each of the prior therapies and for TSEBT. It identified the following: (1) success of the therapy, (2) difficulty in the therapy, (3) ability to recover from the therapy, (4) risk/benefit ratio of the therapy, and (5) willingness to repeat the therapy or therapies in question. Mean values for each question were compared using the paired t test. RESULTS: Thirteen patients were enrolled in the study. At 1- and 6-months posttreatment, patients thought that TSEBT was more difficult to undergo and recover from in comparison to other therapies. At 6-months posttreatment, patients also opposed the repeat therapy with TSEBT compared with other treatments. Patients perceived TSEBT as more successful than other therapies, but this difference in perception was not statistically significant. CONCLUSIONS: TSEBT is perceived by patients to be a successful treatment. TSEBT is thought to be a difficult treatment to undergo and recover from compared with other treatments.

Vitritis as the initial manifestation of recurrent mycosis fungoides.

PURPOSE: To report a case of mycosis fungoides in which vitritis was the earliest manifestation of recurrence. METHODS: A 52-year-old man was followed-up from his initial presentation with vitritis to his death due to recurrent mycosis fungoides over a 5-month period. RESULTS: The patient presented with progressive visual loss in the left eye. Slit-lamp examination revealed severe vitritis, and analysis of a vitreous fluid sample demonstrated a monomorphic population of abnormal T-cell lymphocytes, typical of mycosis fungoides. Three months after developing vitritis, the patient had extraocular recurrence of the disease, and he died 2 months later. CONCLUSION: Recurrent mycosis fungoides may present with isolated intraocular involvement.

Central neurologic involvement in mycosis fungoides: ten cases, actuarial risk assessment, and predictive factors.

BACKGROUND: Neurologic involvement in mycosis fungoides is rare. Isolated case reports in the literature suggest the pattern and the natural history for such occurrences, while a literature summary can provide direction on diagnosis and management. Although case series may confirm such information, cohort data are required to establish an overall risk of occurrence and to evaluate possible predictive factors. METHODS: We presented a case of central nervous system involvement in mycosis fungoides from Haifa, Israel and tabulated a series of nine cases from Canada. To estimate the risk of neurologic involvement, a cohort of 680 consecutive patients with newly diagnosed mycosis fungoides, of which the nine cases of neurologic involvement emerged during follow up, was analyzed using the Kaplan-Meier method. The actuarial risk of developing neurologic involvement was related to the baseline tumor-node-metastasis-blood classification factors. RESULTS: The pattern of disease in these 10 additional cases confirms the overall pattern in the approximately 40 patients described in the literature. The main symptoms are fluctuating higher cognitive functions and cranial nerve dysfunction, with fairly rapid clinical onset of symptoms. Most cases of central neurologic involvement with mycosis fungoides emerge within a setting of advanced disease. In patients with newly diagnosed mycosis fungoides, the greatest risk of developing neurologic involvement is within the first several years after diagnosis and is associated with the initial stage of disease. Patients with two or more of the T3-4, N3, M1, and B1 classification factors have a one in six chance of developing central neurologic involvement, while there is about a one in a hundred chance for the corresponding control group. CONCLUSIONS: Neurologic involvement with mycosis fungoides is indeed rare, but it is associated with a more advanced stage at diagnosis and with other visceral disease that can precede it. Although the role of low-dose prophylactic cranial radiation is uncertain, overt neurologic involvement requires urgent palliative treatment.

Two-dimensional mapping of underdosed areas using radiochromic film for patients undergoing total skin electron beam radiotherapy.

PURPOSE: To demonstrate the viability of radiochromic film as an in vivo, two-dimensional dosimeter for the measurement of underdosed areas in patients undergoing total skin electron beam (TSEB) radiotherapy. The results were compared with thermoluminescent dosimeter measurements. METHODS AND MATERIALS: Dosimetry results are reported for an inframammary fold of 2 patients treated using a modified version of the Stanford six-position (i.e., six-field and dual-beam) TSEB technique. The results are presented as contour plots of film optical density and percentage of dose. A linear dose profile measured from film was compared with the thermoluminescent dosimeter measurements. RESULTS: The results showed that the percentage doses as measured by film are in good agreement with those measured by the thermoluminescent dosimeters. The isodose contour plots provided by film can be used as a two-dimensional dose map for a patient when determining the size of the supplemental patch fields. CONCLUSION: Radiochromic film is a viable dosimetry tool that the radiation oncologist can use to understand the surface dose heterogeneity better across complex concave regions of skin to help establish more appropriate margins to patch underdosed areas. Film could be used for patients undergoing TSEB for disorders such as mycosis fungoides or undergoing TSEB or regional skin electron beam for widespread skin metastases from breast cancer and other malignancies.

A Phase I-II study in the use of acupuncture-like transcutaneous nerve stimulation in the treatment of radiation-induced xerostomia in head-and-neck cancer patients treated with radical radiotherapy.

PURPOSE: Recent studies have suggested that acupuncture may improve radiation-induced xerostomia with an increase in the median salivary flow rate and sustained symptom relief. An acupuncture-like transcutaneous nerve stimulation method (Codetron) without invasive needles was developed to mimic acupuncture treatment. This Phase I-II study examined the effectiveness of Codetron in treating radiation-induced xerostomia. METHODS AND MATERIALS: Patients with symptomatic xerostomia after radical radiotherapy for head-and-neck cancer but with evidence of residual salivary function were recruited into the study. Two 6-week courses of Codetron treatment of acupuncture points preselected according to traditional Chinese medicine principles were given with a 2-week break between each course. Basal and citric acid-primed whole saliva production were measured at baseline and up to 1 year after treatment completion. Xerostomia symptoms were assessed by a five-item xerostomia symptom questionnaire with a visual analog scale and quality of life was evaluated using the Head and Neck Radiotherapy Questionnaire. RESULTS: We enrolled 46 patients in the study. All patients had received radiotherapy doses of >or=50 Gy to bilateral head-and-neck fields, including the parotid glands. Of the 46 patients, 37 completed the follow-up assessments at 3 and 6 months after treatment completion. No Codetron treatment-related complications occurred. Improvement in xerostomia symptoms was noted, with a mean increase in the visual analog scale score of 86 (p < 0.0005) and 77 (p < 0.0001) at 3 and 6 months after treatment completion, respectively. For all patients, the increase in the mean basal and citric acid-primed whole saliva production at 3 and 6 months after treatment completion was also statistically significant (p < 0.001 and p < 0.0001, respectively). No statistically significant change in the quality-of-life evaluation compared with baseline was observed. CONCLUSION: The results suggest that Codetron treatment improves whole saliva production and related symptoms in patients with radiation-induced xerostomia. The treatment effects were sustained for at least 6 months after Codetron treatment completion. A prospective randomized Phase III trial with appropriate controls is being planned.

Composite depth dose measurement for total skin electron (TSE) treatments using radiochromic film.

Total skin electron (TSE) radiotherapy is routinely used to treat cutaneous T-cell lymphomas and can be implemented using a modified Stanford technique. In our centre, the composite depth dose for this technique is achieved by a combination of two patient positions per day over a three-day cycle, and two gantry angles per patient position. Due to patient morphology, underdosed regions typically occur and have historically been measured using multiple thermoluminescent dosimeters (TLDs). We show that radiochromic film can be used as a two-dimensional relative dosimeter to measure the percent depth dose in TSE radiotherapy. Composite depth dose curves were measured in a cylindrical, polystyrene phantom and compared with TLD data. Both multiple films (1 film per day) and a single film were used in order to reproduce a realistic clinical scenario. First, three individual films were used to measure the depth dose, one per treatment day, and then compared with TLD data; this comparison showed a reasonable agreement. Secondly, a single film was used to measure the dose delivered over three daily treatments and then compared with TLD data; this comparison showed good agreement throughout the depth dose, which includes doses well below 1 Gy. It will be shown that one piece of radiochromic film is sufficient to measure the composite percent depth dose for a TSE beam, hence making radiochromic film a suitable candidate for monitoring underdosed patient regions.

Total skin electron radiation in the management of mycosis fungoides: Consensus of the European Organization for Research and Treatment of Cancer (EORTC) Cutaneous Lymphoma Project Group.

Radiotherapy has been successfully implemented in the treatment of mycosis fungoides (MF) for almost a century. With the development of the modern linear accelerator, it has become possible to treat extended areas of the skin with accelerated electrons. Total skin electron beam radiation (TSEB) has been in use for several decades, and a number of technical modifications have been made with the goals of optimizing dose distribution and improving clinical outcome. Emerging evidence from recent studies suggests an association between TSEB techniques and efficacy in the treatment of MF. Based on this evidence, the European Organization for Research and Treatment of Cancer Cutaneous Lymphoma Project Group, in association with experts from radiotherapy centers in North America, has reached a consensus on acceptable methods and clinical indications for TSEB in the treatment of MF. The aims of this report are to enhance accessibility of this highly efficacious treatment modality to patients with MF and to provide a point of reference for further clinical research.