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Journal of Cutaneous and Aesthetic... 2021Keloids are dermal tumors that are due to increased production of collagen caused by abnormal and prolonged wound healing. The incidence of recurrence is extremely high...
BACKGROUND
Keloids are dermal tumors that are due to increased production of collagen caused by abnormal and prolonged wound healing. The incidence of recurrence is extremely high if only conservative measures are used. This study was conducted to evaluate the feasibility and efficacy surgery and high dose rate brachytherapy as an adjuvant therapy for treatment of keloids.
MATERIALS AND METHODS
50 patients with clinically diagnosed 71 keloids were treated with excision of keloid and post-operative high-dose rate brachytherapy were studied. Complete excision of the keloid till the healthy skin margin was excised. The wound were closed in 2 layers. Subcutaneous tissue closed using absorbable suture, over which a 6F flexible polyethylene tube was placed. High dose rate cobalt-60 brachytherapy was administered. Total of 15 Gy in divided dose, 5 Gy in 3 fractions were administered.
RESULTS
50 patients with 71 keloids were studied. Out of the 50 patients, 12 were male (24%) and 38 were females (76%). Age of the patients ranged between 14 and 71 years. Recurrence rate was 2% with 2 keloids recurring at 5 months interval. 4 patients scored the results as unacceptable, remaining 45 patients rated their results as excellent during their follow up at 10 days, 3 months and 6 months.
CONCLUSION
Treatment of keloids in the plastic surgeon's practice even today is still challenging. Many therapies have been described, but recurrence rate is high with mono-therapy. Combination therapy especially surgical excision with postoperative radiotherapy is best in preventing recurrence.
PubMed: 34908777
DOI: 10.4103/JCAS.JCAS_120_16 -
International Journal of Molecular... Nov 2022Ultra-high dose rate (UHDR) irradiation regimes have the potential to spare normal tissue while keeping equivalent tumoricidal capacity than conventional dose rate...
Ultra-high dose rate (UHDR) irradiation regimes have the potential to spare normal tissue while keeping equivalent tumoricidal capacity than conventional dose rate radiotherapy (CONV-RT). This has been called the FLASH effect. In this work, we present a new simulation framework aiming to study the production of radical species in water and biological media under different irradiation patterns. The chemical stage (heterogeneous phase) is based on a nonlinear reaction-diffusion model, implemented in GPU. After the first 1 μs, no further radical diffusion is assumed, and radical evolution may be simulated over long periods of hundreds of seconds. Our approach was first validated against previous results in the literature and then employed to assess the influence of different temporal microstructures of dose deposition in the expected biological damage. The variation of the Normal Tissue Complication Probability (NTCP), assuming the model of Labarbe et al., where the integral of the peroxyl radical concentration over time (AUC-ROO) is taken as surrogate for biological damage, is presented for different intra-pulse dose rate and pulse frequency configurations, relevant in the clinical scenario. These simulations yield that overall, mean dose rate and the dose per pulse are the best predictors of biological effects at UHDR.
Topics: Radiotherapy Dosage; Computer Simulation
PubMed: 36362271
DOI: 10.3390/ijms232113484 -
Physics in Medicine and Biology Jun 2022To introduce a methodology to predict tissue sparing effects in pulsed ultra-high dose rate radiation exposures which could be included in a dose-effect prediction...
To introduce a methodology to predict tissue sparing effects in pulsed ultra-high dose rate radiation exposures which could be included in a dose-effect prediction system or treatment planning system and to illustrate it by using three published experiments.The proposed system formalises the variability of oxygen levels as an oxygen dose histogram (ODH), which provides an instantaneous oxygen level at a delivered dose. The histogram concept alleviates the need for a mechanistic approach. At each given oxygen level the oxygen fixation concept is used to calculate the change in DNA-damage induction compared to the fully hypoxic case. Using the ODH concept it is possible to estimate the effect even in the case of multiple pulses, partial oxygen depletion, and spatial oxygen depletion. The system is illustrated by applying it to the seminal results by Town (Nat. 1967) on cell cultures and the pre-clinical experiment on cognitive effects by Montay-Gruel(2017365-9).The proposed system predicts that a possible FLASH-effect depends on the initial oxygenation level in tissue, the total dose delivered, pulse length and pulse repetition rate. The magnitude of the FLASH-effect is the result of a redundant system, in that it will have the same specific value for a different combination of these dependencies. The cell culture data are well represented, while a correlation between the pre-clinical experiments and the calculated values is highly significant ( < 0.01).. A system based only on oxygen related effects is able to quantify most of the effects currently observed in FLASH-radiation.
Topics: Humans; Hypoxia; Oxygen; Radiotherapy Dosage
PubMed: 35594854
DOI: 10.1088/1361-6560/ac71ef -
Precision Radiation Oncology Mar 2023EBT-XD model of Gafchromic films has a broader optimal dynamic dose range, up to 40 Gy, compared to its predecessor models. This characteristic has made EBT-XD films...
EBT-XD model of Gafchromic films has a broader optimal dynamic dose range, up to 40 Gy, compared to its predecessor models. This characteristic has made EBT-XD films suitable for high-dose applications such as stereotactic body radiotherapy and stereotactic radiosurgery, as well as ultra-high dose rate FLASH radiotherapy. The purpose of the current study was to characterize the dependence of EBT-XD film response on linear energy transfer (LET) and dose rate of therapeutic protons from a synchrotron. A clinical spot-scanning proton beam was used to study LET dependence at three dose-averaged LET (LET) values of 1.0 keV/µm, 3.6 keV/µm, and 7.6 keV/µm. A research proton beamline was used to study dose rate dependence at 150 Gy/second in the FLASH mode and 0.3 Gy/second in the non-FLASH mode. Film response data from LET values of 0.9 keV/µm and 9.0 keV/µm of the proton FLASH beam were also compared. Film response data from a clinical 6 MV photon beam were used as a reference. Both gray value method and optical density (OD) method were used in film calibration. Calibration results using a specific OD calculation method and a generic OD calculation method were compared. The four-parameter NIH Rodbard function and three-parameter rational function were compared in fitting the calibration curves. Experimental results showed that the response of EBT-XD film is proton LET dependent but independent of dose rate. Goodness-of-fit analysis showed that using the NIH Rodbard function is superior for both protons and photons. Using the "specific OD + NIH Rodbard function" method for EBT-XD film calibration is recommended.
PubMed: 37868341
DOI: 10.1002/pro6.1187 -
The Journal of Pediatric Pharmacology... 2022Medication errors are 3 times more likely to occur in pediatric populations due to calculation and rounding errors. The objective of this study was to determine the...
OBJECTIVE
Medication errors are 3 times more likely to occur in pediatric populations due to calculation and rounding errors. The objective of this study was to determine the effect of a pharmacist-driven pediatric dose rounding protocol on the dose rounding of medications, measurable volumes of inpatient and discharge prescriptions, and potential cost savings.
METHODS
This single center, quasi-experimental study evaluated patients younger than or equal to 18 years of age prescribed intravenous or enteral liquid medications during an inpatient, observation, or emergency department encounter. The primary outcome of rate of measurable dose volumes was evaluated pre- and post-implementation of the protocol. Secondary outcomes, including the number of discharge prescriptions affected by pharmacist dose rounding, an evaluation of protocol effect, and prescriptions dose rounded to limit the number of packages per dose, were evaluated using a cross-sectional analysis of the post-group.
RESULTS
Four hundred seventy-seven patients and 1060 medications were evaluated in a 1-month period. The rate of measurable volumes increased from 72% to 93% in the post-group (p = 0.0001). In the post-group, 197 patients had 313 medications dose rounded by pharmacists per protocol. Of the 55 discharge medications in the post-group, 21 prescriptions (38%) matched inpatient orders that had been dose rounded by pharmacists. Twenty-four medications were rounded down to a whole package size resulting in an estimated cost savings of $117 (approximately $1400 per year).
CONCLUSIONS
Implementation of a pharmacist-driven dose rounding protocol significantly increased the rate of measurable volumes administered to pediatric patients at our institution.
PubMed: 36186243
DOI: 10.5863/1551-6776-27.7.636 -
Journal of Radiation Research Mar 2023While epidemiological data are available for the dose and dose-rate effectiveness factor (DDREF) for human populations, animal models have contributed significantly to... (Review)
Review
While epidemiological data are available for the dose and dose-rate effectiveness factor (DDREF) for human populations, animal models have contributed significantly to providing quantitative data with mechanistic insights. The aim of the current review is to compile both the in vitro experiments with reference to the dose-rate effects of DNA damage and repair, and the animal studies, specific to rodents, with reference to the dose-rate effects of cancer development. In particular, the review focuses especially on the results pertaining to underlying biological mechanisms and discusses their possible involvement in the process of radiation-induced carcinogenesis. Because the concept of adverse outcome pathway (AOP) together with the key events has been considered as a clue to estimate radiation risks at low doses and low dose-rates, the review scrutinized the dose-rate dependency of the key events related to carcinogenesis, which enables us to unify the underlying critical mechanisms to establish a connection between animal experimental studies with human epidemiological studies.
Topics: Animals; Humans; Dose-Response Relationship, Radiation; Neoplasms, Radiation-Induced; Mammary Glands, Human; Risk Assessment; Radiation Exposure; Carcinogenesis; Models, Animal; Gastrointestinal Tract
PubMed: 36773323
DOI: 10.1093/jrr/rrad002 -
Journal of Contemporary Brachytherapy Dec 2018Cervical cancer (CC) is a neoplasm with great potential for prevention, but it is still an important public health problem in most developing countries. No significant... (Review)
Review
Cervical cancer (CC) is a neoplasm with great potential for prevention, but it is still an important public health problem in most developing countries. No significant difference is found in the literature between intracavitary high-dose-rate (HDR) and low-dose-rate (LDR) brachytherapy, when considering overall, disease specific, and recurrence-free survivals. Cervical dilatation is mandatory for the insertion of intra-uterine tandems for CC intracavitary brachytherapy. Pain and discomfort may eventually be the limiting factors of the procedure, sometimes leading to unsatisfactory results in terms of adequate position of the applicator set. In this paper, we critically reviewed the current sedation and anesthetic options for comfort and safety procedures when performing intracavitary brachytherapy.
PubMed: 30662480
DOI: 10.5114/jcb.2018.81027 -
Ophthalmology Science 2024To describe a pilot study on the use of single-session, high-dose-rate, Food and Drug Administration-cleared, yttrium-90 (Y) plaque brachytherapy for iris and...
PURPOSE
To describe a pilot study on the use of single-session, high-dose-rate, Food and Drug Administration-cleared, yttrium-90 (Y) plaque brachytherapy for iris and iridociliary melanoma.
DESIGN
A single-center, clinical case series.
PARTICIPANTS
Six consecutive patients were included in this study. Each was diagnosed with an iris or iridociliary melanoma based on clinical examination with or without biopsy.
METHODS
Each tumor was staged according to the American Joint Committee on Cancer criteria and received Y eye plaque brachytherapy. The main variables were tumor size, patient age, sex, and method of diagnosis (clinical or biopsy). Surgical techniques, treatment durations, and ocular side effects were recorded. Local control was defined as a lack of tumor growth or regression determined by clinical examinations, including slit-lamp and gonio photography, as well as high-frequency ultrasound measurements. Toxicity parameters included acute and short-term corneal/scleral change, anterior segment inflammation, and cataract progression.
MAIN OUTCOME MEASURES
Local and systemic cancer control, tumor regression, visual acuity, as well as radiation-related normal tissue toxicity.
RESULTS
High-dose-rate Y plaque brachytherapy was used to treat small (American Joint Committee on Cancer cT1) category melanomas. Single-surgery high-dose-rate irradiations were performed under anesthesia. Because of short treatment durations, high-dose-rate Y did not require the additional procedures used for low-dose-rate plaque (e.g., sutures, amniotic membrane epicorneal buffering, Gunderson flaps, and second surgeries for plaque removal). Only conjunctival recession was used to avoid normal tissue irradiation. High-dose-rate Y treatment durations averaged 8.8 minutes (median, 7.9; range, 5.8-12.9). High-dose-rate Y brachytherapy was associated with no periorbital, corneal (Descemet folds), or conjunctival edema. There was no acute or short-term anterior uveitis, secondary cataract, scleropathy, radiation retinopathy, maculopathy, or optic neuropathy. The follow-up was a mean of 16.0 (range 12-24) months. Evidence of local control included a lack of expansion of tumor borders ( = 6, 100%), darkening with or without atrophy of the tumor surface ( = 5/6, 83%), and a mean 24.5% reduction in ultrasonographically measured tumor thickness. There were no cases of metastatic disease.
CONCLUSIONS
High-dose-rate Y brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of iris and iridociliary melanomas.
FINANCIAL DISCLOSURES
Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
PubMed: 38840779
DOI: 10.1016/j.xops.2024.100513 -
BMC Pregnancy and Childbirth May 2023Neuraxial labor analgesia has been associated with fetal heart rate changes. Fetal bradycardia is multifactorial, and predicting it poses a significant challenge to...
BACKGROUND
Neuraxial labor analgesia has been associated with fetal heart rate changes. Fetal bradycardia is multifactorial, and predicting it poses a significant challenge to clinicians. Machine learning algorithms may assist the clinician to predict fetal bradycardia and identify predictors associated with its presentation.
METHODS
A retrospective analysis of 1077 healthy laboring parturients receiving neuraxial analgesia was conducted. We compared a principal components regression model with tree-based random forest, ridge regression, multiple regression, a general additive model, and elastic net in terms of prediction accuracy and interpretability for inference purposes.
RESULTS
Multiple regression identified combined spinal-epidural (CSE) (p = 0.02), interaction between CSE and dose of phenylephrine (p < 0.0001), decelerations (p < 0.001), and the total dose of bupivacaine (p = 0.03) as associated with decrease in fetal heart rate. Random forest exhibited good predictive accuracy (mean standard error of 0.92).
CONCLUSION
Use of CSE, presence of decelerations, total dose of bupivacaine, and total dose of vasopressors after CSE are associated with decreases in fetal heart rate in healthy parturients during labor. Prediction of changes in fetal heart rate can be approached with a tree-based random forest model with good accuracy with important variables that are key for the prediction, such as CSE, BMI, duration of stage 1 of labor, and dose of bupivacaine.
Topics: Pregnancy; Female; Humans; Heart Rate, Fetal; Bradycardia; Retrospective Studies; Analgesia, Epidural; Analgesia, Obstetrical; Bupivacaine
PubMed: 37211590
DOI: 10.1186/s12884-023-05632-3 -
Radiation Research Nov 2020Internal contamination by radionuclides may constitute a major source of exposure and biological damage after radiation accidents and potentially in a dirty bomb or...
Internal contamination by radionuclides may constitute a major source of exposure and biological damage after radiation accidents and potentially in a dirty bomb or improvised nuclear device scenario. We injected male C57BL/6 mice with radiolabeled cesium chloride solution (137CsCl) to evaluate the biological effects of varying cumulative doses and dose rates in a two-week study. Injection activities of 137CsCl were 5.71, 6.78, 7.67 and 9.29 MBq, calculated to achieve a target dose of 4 Gy at days 14, 7, 5 and 3, respectively. We collected whole blood samples at days 2, 3, 5, 7 and 14 so that we can publish the issue in Decemberfrom all injection groups and measured gene expression using Agilent Mouse Whole Genome microarrays. We identified both dose-rate-independent and dose-rate-dependent gene expression responses in the time series. Gene Ontology analysis indicated a rapid and persistent immune response to the chronic low-dose-rate irradiation, consistent with depletion of radiosensitive B cells. Pathways impacting platelet aggregation and TP53 signaling appeared activated, but not consistently at all times in the study. Clustering of genes by pattern and identification of dose-rate-independent and -dependent genes provided insight into possible drivers of the dynamic transcriptome response in vivo, and also indicated that TP53 signaling may be upstream of very different transcript response patterns. This characterization of the biological response of blood cells to internal radiation at varying doses and dose rates is an important step in understanding the effects of internal contamination after a nuclear event.
Topics: Animals; Cesium Radioisotopes; DNA Repair; Gene Ontology; Male; Mice; Radiation Dosage
PubMed: 32931585
DOI: 10.1667/RADE-20-00041