Barriers and facilitators to clinical implementation of radiotherapy treatment planning automation: A survey study of medical dosimetrists.

PURPOSE: Little is known about the scale of clinical implementation of automated treatment planning techniques in the United States. In this work, we examine the barriers and facilitators to adoption of commercially available automated planning tools into the clinical workflow using a survey of medical dosimetrists. METHODS/MATERIALS: Survey questions were developed based on a literature review of automation research and cognitive interviews of medical dosimetrists at our institution. Treatment planning automation was defined to include auto-contouring and automated treatment planning. Survey questions probed frequency of use, positive and negative perceptions, potential implementation changes, and demographic and institutional descriptive statistics. The survey sample was identified using both a LinkedIn search and referral requests sent to physics directors and senior physicists at 34 radiotherapy clinics in our state. The survey was active from August 2020 to April 2021. RESULTS: Thirty-four responses were collected out of 59 surveys sent. Three categories of barriers to use of automation were identified. The first related to perceptions of limited accuracy and usability of the algorithms. Eighty-eight percent of respondents reported that auto-contouring inaccuracy limited its use, and 62% thought it was difficult to modify an automated plan, thus limiting its usefulness. The second barrier relates to the perception that automation increases the probability of an error reaching the patient. Third, respondents were concerned that automation will make their jobs less satisfying and less secure. Large majorities reported that they enjoyed plan optimization, would not want to lose that part of their job, and expressed explicit job security fears. CONCLUSION: To our knowledge this is the first systematic investigation into the views of automation by medical dosimetrists. Potential barriers and facilitators to use were explicitly identified. This investigation highlights several concrete approaches that could potentially increase the translation of automation into the clinic, along with areas of needed research.

Infants Younger Than 6 Months Infected With SARS-CoV-2 Show the Highest Respiratory Viral Loads.

There is a paucity of reports on the characteristics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in infants, because most studies have grouped infants with older children. We analyzed the viral loads of 45318 SARS-CoV-2-positive nasopharyngeal swab samples obtained in Buenos Aires, Argentina. Infants younger than 6 months presented higher viral loads than any other age group. Children older than 6 months showed significantly lower viral loads, similar to those founds in adults. This observation raises new questions regarding the role of infants in the spreading of SARS-CoV-2 infection.

Predicting severe hematologic toxicity from extended-field chemoradiation of para-aortic nodal metastases from cervical cancer.

PURPOSE: The purpose of this study was to determine factors predictive for severe hematologic toxicity (HT) in cervical cancer patients with para-aortic lymph node metastasis treated with concurrent cisplatin chemoradiation to an extended field (EFCRT). METHODS AND MATERIALS: Thirty-eight patients with cervical cancer and para-aortic lymph node metastasis who underwent EFCRT were analyzed. Active bone marrow was defined as the region within irradiated total bone marrow (BMTOT) with a standard uptake value on 18F-fluorodeoxyglucose positron emission tomography/computed tomography greater than the mean standard uptake value for BMTOT. Serial weekly blood counts from the beginning to the end of radiation treatment were evaluated for HT using Common Terminology Criteria for Adverse Events, version 4.0. RESULTS: Nineteen patients had grade 3 or higher hematologic toxicity (HT3+), not including lymphocyte toxicity. Obese patients (n = 12) were less likely to get HT3+ (P = .03) despite getting equivalent doses of chemotherapy. Volumes of BMTOT and active bone marrow receiving doses of 20, 30, and 45 Gy and body mass index significantly predicted HT3+. Patients who had HT3+ had prolonged treatment time (62 vs 53 days, P < .001). CONCLUSIONS: For patients receiving EFCRT, bone marrow irradiation parameters and patient body mass index were associated with HT3+. A simplified nomogram has been created to predict HT3+ in these patients, allowing the potential to explore bone marrow-sparing delivery techniques.

Deep inspiration breathhold for left-sided breast cancer patients with unfavorable cardiac anatomy requiring internal mammary nodal irradiation.

PURPOSE: The purpose of this study was to evaluate the utility of moderate deep inspiration breathhold (mDIBH) in reducing heart exposure in left breast cancer patients who have unfavorable cardiac anatomy and need internal mammary lymph node (IMLN) radiation therapy (RT). METHODS AND MATERIALS: We used maximum heart distance (MHD), defined as the maximum distance of the heart within the treatment field, >1 cm as a surrogate for unfavorable cardiac anatomy. Twenty-two left breast cancer patients with unfavorable cardiac anatomy requiring IMLN-RT underwent free-breathing (FB) and mDIBH computed tomography simulation and planning. Three-dimensional partially wide tangents (3D-PWTs) and intensity modulated RT plans were generated. Dose-volume histograms were used to compare heart and lung dosimetric parameters. Duration of treatment delivery was recorded for all fractions. RESULTS: MHD decreased significantly in mDIBH scans. mDIBH significantly reduced mean heart dose (222.7 vs 578.4 cGy; P < .0001) and percentage of left lung receiving doses ≥20 Gy (V20; 31.93 vs 38.41%; P = .0006) in both 3D-PWT and intensity modulated RT plans. The change in MHD after breathhold reliably predicted mean heart dose reduction after mDIBH. Radiation was effectively delivered in 11.31 ± 3.40 minutes with an average of 10.06 ± 2.74 breathholds per fraction. CONCLUSIONS: mDIBH is efficient and can effectively decrease mean heart dose in patients with unfavorable cardiac anatomy who need IMLN-RT, thus simplifying planning and delivery for them. The reduction in mean heart dose is proportional to the reduction in maximum heart distance.

Single fraction radiosurgery/stereotactic body radiation therapy (SBRT) for spine metastasis: A dosimetric comparison of multiple delivery platforms.

There are numerous commercial radiotherapy systems capable of delivering single fraction spine radiosurgery/SBRT. We aim to compare the capabilities of several of these systems to deliver this treatment when following standardized criteria from a national protocol. Four distinct target lesions representing various case presentations of spine metastases were contoured in both the thoracic and lumbar spine of an anthropomorphic SBRT phantom. Single fraction radiosurgery/SBRT plans were designed for each target with each of our treatment platforms. Plans were prescribed to 16 Gy in one fraction to cover 90% of the target volume using normal tissue and target constraints from RTOG 0631. We analyzed these plans with priority on the dose to 10% of the partial spinal cord and dose to 0.03 cc of the spinal cord. Each system was able to maintain 90% target coverage while meeting all the constraints of RTOG 0631. On average, CyberKnife was able to achieve the lowest spinal cord doses overall and also generated the sharpest dose falloff as indicated by the Paddick gradient index. Treatment times varied widely depending on the modality utilized. On average, treatment can be delivered faster with Flattening Filter Free RapidArc and Tomotherapy, compared to Vero and Cyberknife. While all systems analyzed were able to meet the dose constraints of RTOG 0631, unique characteristics of individual treatment modalities may guide modality selection. Specifically, certain modalities performed better than the others for specific target shapes and locations, and delivery time varied significantly among the different modalities. These findings could provide guidance in determining which of the available modalities would be preferable for the treatment of spine metastases based on individualized treatment goals.

Single-fraction spine SBRT end-to-end testing on TomoTherapy, Vero, TrueBeam, and CyberKnife treatment platforms using a novel anthropomorphic phantom.

Spine SBRT involves the delivery of very high doses of radiation to targets adjacent to the spinal cord and is most commonly delivered in a single fraction. Highly conformal planning and accurate delivery of such plans is imperative for successful treatment without catastrophic adverse effects. End-to-end testing is an important practice for evaluating the entire treatment process from simulation through treatment delivery. We performed end-to-end testing for a set of representative spine targets planned and delivered using four different treatment planning systems (TPSs) and delivery systems to evaluate the various capabilities of each. An anthropomorphic E2E SBRT phantom was simulated and treated on each system to evaluate agreement between measured and calculated doses. The phantom accepts ion chambers in the thoracic region and radiochromic film in the lumbar region. Four representative targets were developed within each region (thoracic and lumbar) to represent different presentations of spinal metastases and planned according to RTOG 0631 constraints. Plans were created using the TomoTherapy TPS for delivery using the Hi·Art system, the iPlan TPS for delivery using the Vero system, the Eclipse TPS for delivery using the TrueBeam system in both flattened and flattening filter free (FFF), and the MultiPlan TPS for delivery using the CyberKnife system. Delivered doses were measured using a 0.007 cm3 ion chamber in the thoracic region and EBT3 GAFCHROMIC film in the lumbar region. Films were scanned and analyzed using an Epson Expression 10000XL flatbed scanner in conjunction with FilmQAPro2013. All treatment platforms met all dose constraints required by RTOG 0631. Ion chamber measurements in the thoracic targets delivered an overall average difference of 1.5%. Specifically, measurements agreed with the TPS to within 2.2%, 3.2%, 1.4%, 3.1%, and 3.0% for all three measureable cases on TomoTherapy, Vero, TrueBeam (FFF), TrueBeam (flattened), and CyberKnife, respectively. Film measurements for the lumbar targets resulted in average global gamma index passing rates of 100% at 3%/3 mm, 96.9% at 2%/2mm, and 61.8% at 1%/1 mm, with a 10% minimum threshold for all plans on all platforms. Local gamma analysis was also performed with similar results. While gamma passing rates were consistently accurate across all platforms through 2%/2 mm, treatment beam-on delivery times varied greatly between each platform with TrueBeam FFF being shortest, averaging 4.4 min, TrueBeam using flattened beam at 9.5 min, TomoTherapy at 30.5 min, Vero at 19 min, and CyberKnife at 46.0 min. In spite of the complexity of the representative targets and their proximity to the spinal cord, all treatment platforms were able to create plans meeting all RTOG 0631 dose constraints and produced exceptional agreement between calculated and measured doses. However, there were differences in the plan characteristics and significant differences in the beam-on delivery time between platforms. Thus, clinical judgment is required for each particular case to determine most appropriate treatment planning/delivery platform.

Commissioning and initial stereotactic ablative radiotherapy experience with Vero.

The purpose of this study is to describe the comprehensive commissioning process and initial clinical performance of the Vero linear accelerator, a new radiotherapy device recently installed at UT Southwestern Medical Center specifically developed for delivery of image-guided stereotactic ablative radiotherapy (SABR). The Vero system utilizes a ring gantry to integrate a beam delivery platform with image guidance systems. The ring is capable of rotating ± 60° about the vertical axis to facilitate noncoplanar beam arrangements ideal for SABR delivery. The beam delivery platform consists of a 6 MV C-band linac with a 60 leaf MLC projecting a maximum field size of 15 × 15 cm² at isocenter. The Vero planning and delivery systems support a range of treatment techniques, including fixed beam conformal, dynamic conformal arcs, fixed gantry IMRT in either SMLC (step-and-shoot) or DMLC (dynamic) delivery, and hybrid arcs, which combines dynamic conformal arcs and fixed beam IMRT delivery. The accelerator and treatment head are mounted on a gimbal mechanism that allows the linac and MLC to pivot in two dimensions for tumor tracking. Two orthogonal kV imaging subsystems built into the ring facilitate both stereoscopic and volumetric (CBCT) image guidance. The system is also equipped with an always-active electronic portal imaging device (EPID). We present our commissioning process and initial clinical experience focusing on SABR applications with the Vero, including: (1) beam data acquisition; (2) dosimetric commissioning of the treatment planning system, including evaluation of a Monte Carlo algorithm in a specially-designed anthropomorphic thorax phantom; (3) validation using the Radiological Physics Center thorax, head and neck (IMRT), and spine credentialing phantoms; (4) end-to-end evaluation of IGRT localization accuracy; (5) ongoing system performance, including isocenter stability; and (6) clinical SABR applications.

Dosimetric and motion analysis of margin-intensive therapy by stereotactic ablative radiotherapy for resectable pancreatic cancer.

BACKGROUND: The retroperitoneal margin is a common site of positive surgical margins in patients with resectable pancreatic cancer. Preoperative margin-intensive therapy (MIT) involves delivery of a single high dose of ablative radiotherapy (30 Gy) focused on this surgically inaccessible margin, utilizing stereotactic techniques in an effort to reduce local failure following surgery. In this study, we investigated the motion of regional organs at risk (OAR) utilizing 4DCT, evaluated the dosimetric effects of abdominal compression (AC) to reduce regional motion, and compared various planning techniques to optimize MIT. METHODS: 10 patients were evaluated with 4DCT scans. All 10 patients had scans using AC and seven of the 10 patients had scans both with and without AC. The peak respiratory abdominal organ and major vessel centroid excursion was measured. A "sub-GTV" region was defined by a radiation oncologist and surgical oncologist encompassing the retroperitoneal margin typically lateral and posterior to the superior mesenteric artery (SMA), and a 3-5 mm margin was added to constitute the PTV. Identical 3D non-coplanar SABR (3DSABR) plans were designed for the average compression and non-compression scans. Compression scans were planned with 3DSABR, coplanar IMRT (IMRT), and Cyberknife (CK) planning techniques. Dose volume analysis was undertaken for various endpoints, comparing OAR doses with and without AC and for different planning methods. RESULTS: The mean PTV size was 20.2 cm3. Regional vessel motion of the SMA, celiac trunk, and renal vessels was small (< 5 mm) and not significantly impacted by AC. Mean pancreatic motion was > 5 mm, so AC has been used in all patients enrolled thus far. AC did not significantly increase OAR dose including the stomach and traverse colon. There were several statistically significant differences in the doses to OARs as a function of the type of planning modality used. CONCLUSIONS: AC does not significantly reduce the limited motion of structures in close proximity to the MIT target and does not significantly increase the dose to OARs that can be displaced by the compression plate. The treatment planning techniques evaluated in this study have different advantages with no clearly superior method in our analysis. Dose to adjacent vessels may be reduced with 3DSABR or IMRT techniques, while conformality is increased with IMRT or CK.

Efecto del butirato de sodio sobre algunos parámetros productivos de gallinas de postura en semilibertad / Effect of sodium butyrate on productive performance of laying hens in a semi-free range system

An experiment was conducted with 32 week-old 470 ISA-Babcock B380 laying hens, housed in floor pens with wheat-straw litter, to study the replacement of the antibiotic growth promoter (bacitracin zinc 30 ppm) with sodium butyrate (300 g/ton) in the diet. Results in 24 weeks of experimentation were similar between treatments (P > 0.05), in: egg production (92.6 and 91.9%), egg weight (63.0 and 62.9 g), egg mass / bird / day (58.4 and 57.7 g), feed consumption / bird / day (123.6 and 124.3 g), feed conversion (2.11 and 2.15), egg albumen quality (Haugh Units 82.9 and 83), yolk color DSM fan (10.3 and 9.9), shell thickness (0.392 and 0.394 mm) and weight of the shell (6.26 and 8.03 g). According to information obtained in 24 weeks with 32 week old hens, the addition of sodium butyrate to feed as a substitute for the growth promoter (bacitracin zinc), was similar in the productive performance and egg quality.

Se realizó un experimento con 470 gallinas de la estirpe ISA-Babcock B380 de 32 semanas de edad, alojadas en pisos con cama de paja de trigo, para estudiar la sustitución del antibiótico promotor de crecimiento (bacitracina cinc 30 ppm) por butirato de sodio (300 g/ton) en la dieta. Los resultados obtenidos en 24 semanas de experimentación fueron similares (P > 0.05) entre tratamientos, en: porcentaje de postura (92.6 y 91.9%), peso del huevo (63.0 y 62.9 g), masa del huevo/ ave/día (58.4 y 57.7 g), consumo/ave/día (123.6 y 124.3 g), conversión alimenticia (2.11 y 2.15), calidad de la albúmina del huevo (82.9 y 83 Unidades Haugh), color de la yema con el abanico DSM (10.3 y 9.9), grosor de cascarón (0.392 y 0.394 mm) y peso del cascarón (6.26 y 8.03 g). De acuerdo con la información obtenida en 24 semanas de experimentación, con gallinas de 32 semanas de edad, la adición de butirato de sodio en el alimento, como sustituto del promotor de crecimiento (bacitracina cinc), fue similar en el comportamiento productivo y la calidad del huevo.

Efecto del butirato de sodio en dietas para gallinas sobre el comportamiento productivo, calidad del huevo y vellosidades intestinales / Effect of sodium butyrate on diets for laying hens on the productive performance, egg quality and intestinal villi

In this study, productive performance, quality of eggs and histological analysis of intestinal villi of the duodenum (length and width) was evaluated in Bovans laying hens of 63 weeks of age, with the addition of butyrate in the diet ( 0, 300, 500 ppm). The results obtained in ten weeks of experimentation showed a response (P < 0.05) on egg production percentaje (86.4, 92.2 and 89.6), egg weight (63.4, 63.4 and 64.1 g), feed consumption/bird/day (111.4, 111.9 and 113.4 g), feed conversion (2.09, 1.95 and 2.03), micro-fractures percentaje (20.8, 14.9 and 12.9), broken eggs percentaje (2.6, 2.1 and 0.6), length of villi (1.15, 1.22 and 1.32 mm) and villi width (0.467, 0.500 and 0.532 mm) to the addition of butyrate. These results indicate the beneficial effect of butyrate in laying hens in the last third of its first production cycle. From information obtained in this study, it is concluded that sodium butyrate on diets at 500 ppm for Bovans laying hens of 63 weeks of age, improves the productive performance, shell quality and intestinal villi integrity.

En el presente estudio se evaluó el comportamiento productivo, calidad del huevo y análisis histológico de vellosidades intestinales de duodeno (largo y ancho) en gallinas de la estirpe Bovans, de 63 semanas de edad, con adición de butirato en la dieta (0, 300, 500 ppm). Los resultados obtenidos en diez semanas de experimentación mostraron respuesta (P < 0.05) en porcentaje de postura (86.4, 92.2 y 89.6), peso del huevo (63.4, 63.4 y 64.1 g) consumo/ave/día (111.4, 111.9 y 113.4 g), conversión alimentaria (2.09, 1.95 y 2.03), de microfracturas (20.8, 14.9 y 12.9), de huevos rotos (2.6, 2.1 y 0.6), longitud de vellosidades (1.15, 1.22 y 1.32 mm) y ancho de vellosidades (0.467, 0.500 y 0.532 mm) a la adición de butirato. Los resultados indican el efecto benéfico del butirato en gallinas ponedoras en el último tercio de su primer ciclo de producción. De la información obtenida en el presente estudio se concluye que el butirato de sodio en dietas a 500 ppm para gallinas Bovans, de 63 semanas de edad, mejora el comportamiento productivo, la calidad del cascarón y la integridad de las vellosidades intestinales.

Penetración de Salmonella enteriditis a través de huevos fértiles e infértiles sometidos a diferentes estadios de incubación / Salmonella enteritidis penetration in fertile and infertile chicken eggs at progressive stages of incubation

Se evaluó la penetración de Salmonella enteritidis fagotipo 13, realizada mediante la inoculación experimental en la cutícula de huevos fértiles e infértiles provenientes de gallinas Babcock B-300 de 59 semanas de edad y libres de Salmonella sp. El estudio fue realizado a los 8, 12 y 16 días de incubación. Se estudió la penetración de la bacteria dentro de las tres áreas del cascarón después de 24 h de incubación a 37.7ºC. Hacia los 8 días de incubación, no se encontraron diferencias estadísticas significativas entre los huevos fértiles e infértiles en todas las áreas estudiadas (P> 0.05); sin embargo, así hubo diferencias en los huevos fértiles que fueron penetrados (P< 0.05) a los 12 y 16 días de incubación, lo cual indica que el desarrollo embrionario retarda considerablemente la susceptibilidad a la invasión por Salmonella. La penetración a través de la cutícula fue similar en ambos huevos, en contraste con la marcada diferencia observada en las estructuras más internas. Los resultados indican que los hevos incubables no fértiles pueden ser considerados más susceptibles a la penetración por Salmonella que en aquellas que están en desarrollo embrionario

Efecto de la furazolidona sobre el glutatión sanguíneo del pollo de engorda / Effec of furazolidone on chicks blood glutathione

El objetivo de este trabajo fue establecer si la furazolidona utiliza el sistema detoxificante de glutatión en el organismo, mediante la determinación de la cantidad (µmol/ml de sangre) de glutatión total (GT), glutatión oxidado (GSSG), y glutatión reducido (GSH) durante las 5 semanas de vida del pollo de engorda que no consumió aditivos (testigo), comparado con los niveles de GT, GSSG y GSH sanguíneo de las aves que consumieron furazolidona durante las 5 primeras semanas de vida. Hubo diferencia significativa entre el GT (µmol/ml de sangre) y el peso corporal de pollos del grupo testigo y el que consumió furazolidona (55 ppm en el alimento) (R²= -0.709; P< 0.05, y = 2.15 - 0.607x y R²=-0.820 P< 0.05, y = 2.17 -0.61x respectivamente) hubo diferencia significativa (P< 0.05) entre el peso de los pollos del grupo testigo y el de los que consumieron furazolidona (751.3 vs 884.35 g respectivamente)