Multiscale 3D genome organization underlies ILC2 ontogenesis and allergic airway inflammation.

Innate lymphoid cells (ILCs) are well-characterized immune cells that play key roles in host defense and tissue homeostasis. Yet, how the three-dimensional (3D) genome organization underlies the development and functions of ILCs is unknown. Herein, we carried out an integrative analysis of the 3D genome structure, chromatin accessibility and gene expression in mature ILCs. Our results revealed that the local 3D configuration of the genome is rewired specifically at loci associated with ILC biology to promote their development and functional differentiation. Importantly, we demonstrated that the ontogenesis of ILC2s and the progression of allergic airway inflammation are determined by a unique local 3D configuration of the region containing the ILC-lineage-defining factor Id2, which is characterized by multiple interactions between the Id2 promoter and distal regulatory elements bound by the transcription factors GATA-3 and RORα, unveiling the mechanism whereby the Id2 expression is specifically controlled in group 2 ILCs.

Using focus groups to inform a peer health navigator service for people who are transgender and gender diverse in Saskatchewan, Canada.

BACKGROUND: This study investigated healthcare access and quality for people who are transgender and gender-diverse (PTGD) in Saskatchewan (SK), Canada, to inform a larger project that was piloting two peer health navigators for PTGD. METHODS: Two online focus groups were held. Nineteen participants were recruited to represent a broad range in age, gender and location in SK. Transcripts of the focus groups were analyzed using a thematic approach. RESULTS: The core theme that was identified was participants' desire for culturally safe healthcare. This core theme had two component themes: (1) systemic healthcare factors and (2) individual healthcare provider (HCP) factors. The healthcare system primarily acted as a barrier to culturally safe healthcare. HCPs could be either barriers or facilitators of culturally safe care; however, negative experiences outweighed positive ones. CONCLUSIONS: PTGD in SK face discrimination, with delays and barriers to care at all levels of the healthcare system. Peer health navigators can address some of these discrepancies; however, greater support is required for PTGD to be able to access culturally safe healthcare. PATIENT OR PUBLIC CONTRIBUTION: People with lived experience/PTGD were involved in all stages of this project. They were included on the team as community researchers and co-developed the research project, conducted the focus groups, participated in the analyses and are co-authors. As well, both navigators and all the participants in the focus groups were also PTGD.

A systematic review of physical function tests as predictors of key clinical outcomes for adults with blood cancers.

PURPOSE: To determine which standardized physical performance tests are being used specifically in the assessment of adult patients before, during, or after undergoing treatment for hematologic malignancy and which of these functional tests have been demonstrated to have a correlation with key objective clinical outcome measures including mortality, progression-free survival, complete remission, hospital readmissions, emergency department visits, and hospital length of stay. METHODS: PubMed/MEDLINE electronic databases were searched up to June 2021. Searches were restricted to English language. All resulting studies from the electronic database search were assessed by two reviewers for original research with physical performance data exclusive to patients with hematological malignancy. Studies with confounding intervention or the inclusion of pediatric patients were excluded. The quality of the remaining studies was assessed using PRISMA guidelines and Tooth Criteria by two reviewers, using a third reviewer to resolve any discrepancies. The main characteristics of each article, including sample size, population characteristics, physical performance testing methods, and significant and non-significant findings were extracted and compared. Additionally, one reviewer performed a literature review of the safety of physical performance testing. RESULTS: One thousand two hundred fifty-six screened database results resulted in 14 studies included in the systematic review. All studies scored ≥ 0.59 on the Tooth Criteria, indicating moderate to high quality of reporting. Our review found six recurring measures of objective physical function assessed for correlation with clinical outcomes, primarily morbidity and mortality. The heterogeneity of each study precluded aggregate data analysis. CONCLUSIONS: This review was a first step in evaluating which objective physical performance tests are best suited for identifying functional impairment before, during, and after oncologic treatment for adults with blood cancers. Additional studies are needed to determine the optimal objective functional measures to use as a guide in clinical decision-making in the hematologic patient population.

Wellness Wheel Clinics: A First Nation community-partnered care model improving healthcare access, from healthcare providers' perspectives.

First Nation people residing in rural and remote communities have limited primary healthcare access, which often affects chronic disease management leading to poor health outcomes. Individuals with lived experiences of chronic disease and substance use, along with health directors, advocated for improved services. Subsequently, an urban healthcare team in partnership with four First Nation communities developed an Outreach clinic to address healthcare access barriers. Established in 2016, this community-led clinic improves primary care access and chronic disease management in First Nation communities. Employing a qualitative research design, interviews were conducted with 15 clinic providers and 9 community members to explore the clinic's 1-year post-implementation impacts. Thematic data analysis indicated that engagement and approval by community leadership, support from Elders and community members and collaboration with existing community healthcare staff were crucial for establishing the Outreach clinic. Initial logistical challenges with space allocation, equipment, medical supplies, funding, staffing, medical records and appointment scheduling were resolved through community consultation and creative solutions. A nurse coordinator ensured continuity of care and was integral to ensuring clients receive seamless care. The commitment of the outreach team and the collective goal of providing client-centered care were instrumental in the clinic's success. In partnership with communities, access to healthcare in First Nation communities can be enhanced by coordinating Outreach clinics through existing community healthcare facilities.

Cross-sectional survey of Australian and New Zealand clinical staff to explore attitudes regarding medication prescription and administration during neonatal emergencies.

AIM: To survey Australasian neonatal medical and nursing staff to determine confidence regarding medication use, prior experience with medication errors and common resources utilised in neonatal emergencies. METHODS: Data were collected through a cross-sectional online survey distributed to clinical staff affiliated with the Australian and New Zealand Neonatal Network. Information collected included: demographics, confidence in medication use, medication errors and resources used to assist with medication administration. Outcomes were compared between medical staff and nursing staff, and between clinical staff with differing levels of clinical experience (<5 years, 5-10 years and >10 years). RESULTS: Respondents (n = 133) were most confident in calculating medication doses (89%, n = 119), but least confident in prescribing medication (50%, n = 67). Nurses were more likely to be confident than doctors with respect to appropriately diluting and drawing up medication (88% nurses vs. 28% doctors, P < 0.0001), and administering intravenous medications to critically ill neonates (97% nurses vs. 82% doctors, P < 0.01). Over half of respondents reported being personally involved in a medication error in the last 12 months: 33% had been involved in an error related to delayed administration, 18% related to incorrect documentation and 17% related to an incorrect dose. Free-text responses highlighted issues relating to adrenaline (epinephrine) administration and difficulties with equipment (syringe drivers and/or infusion pumps). CONCLUSIONS: Medication errors in neonatal emergencies are common. Strategies to reduce such errors should be implemented in settings where neonates may require emergency care or resuscitation.

The long noncoding RNA Morrbid regulates CD8 T cells in response to viral infection.

The transcriptional programs that regulate CD8 T-cell differentiation and function in the context of viral infections or tumor immune surveillance have been extensively studied; yet how long noncoding RNAs (lncRNAs) and the loci that transcribe them contribute to the regulation of CD8 T cells during viral infections remains largely unexplored. Here, we report that transcription of the lncRNA Morrbid is specifically induced by T-cell receptor (TCR) and type I IFN stimulation during the early stages of acute and chronic lymphocytic choriomeningitis virus (LCMV) infection. In response to type I IFN, the Morrbid RNA and its locus control CD8 T cell expansion, survival, and effector function by regulating the expression of the proapoptotic factor, Bcl2l11, and by modulating the strength of the PI3K-AKT signaling pathway. Thus, our results demonstrate that inflammatory cue-responsive lncRNA loci represent fundamental mechanisms by which CD8 T cells are regulated in response to pathogens and potentially cancer.

Profiles and predictors of thriving in children on the autism spectrum.

BACKGROUND: Thriving is defined as the growth of attributes that mark a flourishing, healthy individual and include Competence, Confidence, Connectedness, Character, Caring and Contribution to self, family, community and civil society. Thriving has been linked to positive youth outcomes in neurotypical children and adolescents but has rarely been explored for individuals on the autism spectrum. METHOD: This study explored the profiles and predictors of parent-reported thriving in 111 school children on the autism spectrum, aged 6 to 14 years. RESULTS: Parents rated children as having relative strengths in the Caring and Connectedness dimensions and relative challenges in the Competence dimension. Stronger thriving outcomes were consistently predicted by stronger socialization scores; however, the other predictors of outcome differed by dimensions. CONCLUSION: The current findings provide insight into the individual and contextual factors that predict thriving in children on the autism spectrum. As research into thriving is in its infancy, more work is needed to understand how child, family and contextual factors relate to thriving in individuals on the autism spectrum to foster positive outcomes.

A Retrospective Cost-Effectiveness Analysis of Mifepristone-Misoprostol Medical Abortions in the First Year at the Regina General Hospital.

OBJECTIVE: In July 2017, mifepristone-misoprostol (mife/miso) became available for medical abortion at the Regina General Hospital's Women's Health Centre (RGH WHC). We investigated whether the proportion of abortions performed medically changed as a result of the introduction of mife/miso, whether using mife/miso instead of the surgical alternative would result in cost savings to the health care system, and whether abortion type differed between patients residing in and outside of Regina. METHODS: We conducted a retrospective chart review of all 306 medical abortions from the RGH WHC between July 1, 2017 and June 30, 2018. We obtained medical and surgical abortion information from that year and the preceding one from an administrative database. Statistical methods were used to calculate the costs of mife/miso, methotrexate-misoprostol (MTX/miso) and surgical abortion, as well as cost-effectiveness ratios. RESULTS: The proportion of medical abortions increased from 15.4% in 2016/2017 to 28.7% in 2017/2018 (χ21 = 54.629; P < 0.001). Calculated costs for mife/miso, with and without complications were CAD $1173.70 and CAD $1708.90, respectively, versus CAD $871.10 and CAD $1204.10, respectively, for MTX/miso, and CAD $1445.95 and CAD $2261.95, respectively, for hospital-based vacuum aspiration. At a willingness-to-pay threshold of CAD $318 (the cost of mife/miso), statistical modelling showed a 61.3% chance that mife/miso was more cost-effective than surgical abortion and a 90.8% chance that it was more cost-effective than MTX/miso. Patients from Regina were significantly more likely (χ21 = 29.406; P < 0.001) to receive a medical abortion (34.9% of abortions) than those living outside of Regina (19.6% of abortions). CONCLUSION: The proportion of abortions completed medically increased significantly over the period studied. Patients from Regina were more likely to receive medical abortion during both time periods. Mife/miso had a >50% probability of cost-effectiveness over both surgical and MTX/miso options.

Hospital admissions and mortality due to complications of injection drug use in two hospitals in Regina, Canada: retrospective chart review.

BACKGROUND: Infectious complications of injection drug use (IDU) often require lengthy inpatient treatment. Our objective was to identify the number of admissions related to IDU in Regina, Canada, as well as describe patient demographics and comorbidities, yearly mortality, readmission rate, and cumulative cost of these hospitalizations between January 1 and December 31, 2018. Additionally, we sought to identify factors that increased risk of death or readmission. METHODS: This study is a retrospective chart review conducted at the two hospitals in Regina. Eligible study cases were identified by querying the discharge database for predetermined International Classification of Diseases code combinations. Electronic medical records were reviewed to assess whether each admission met inclusion criteria, and hospitalization and patient data were subsequently extracted for all included admissions. Mortality data were gleaned from hospital and Ministry of Health databases. Data were analyzed using Excel and IBM SPSS Statistics to identify common comorbidities, admission diagnoses, and costs, as well as to compare patients with a single admission during the study period to those with multiple admissions. Logistic regression analysis was used to identify the relationship between individual variables and in- and out-of-hospital annual mortality. RESULTS: One hundred and forty-nine admissions were included, with 102 unique patients identified. Common comorbidities included hepatitis C (47%), human immunodeficiency virus (HIV) (25%), and comorbid psychiatric disorders (19%). In 23% of all admissions, patients left hospital prior to treatment completion, and 27% of patients experienced multiple admissions. Female patients and those with chronic pain were more likely to be readmitted (p = 0.024 and p = 0.029, respectively). Patients admitted with infective endocarditis were more likely to die during hospitalization (p = 0.0001). The overall mortality was 15% in our cohort. The estimated cumulative cost of inpatient treatment of complications of IDU in Regina was $3.7 million CAD in 2018. CONCLUSION: Patients with history of IDU and hospital admission experience high mortality rates in Regina, a city with paucity of inpatient supports for persons who use injection drugs. Needle syringe programs, opioid agonist therapy, and safe consumption sites have been shown to improve outcomes as well as reduce healthcare costs for this patient population. We will use our findings to advocate for increased access to these harm reduction strategies in Regina, particularly for inpatients.

Intradermal Synthetic DNA Vaccination Generates Leishmania-Specific T Cells in the Skin and Protection against Leishmania major.

Vaccination remains one of the greatest medical breakthroughs in human history and has resulted in the near eradication of many formerly lethal diseases in many countries, including the complete eradication of smallpox. However, there remain a number of diseases for which there are no or only partially effective vaccines. There are numerous hurdles in vaccine development, of which knowing the appropriate immune response to target is one of them. Recently, tissue-resident T cells have been shown to mediate high levels of protection for several infections, although the best way to induce these cells is still unclear. Here we compare the ability to generate skin-resident T cells in sites distant from the immunization site following intramuscular and intradermal injection using optimized synthetic DNA vaccines. We found that mice immunized intradermally with a synthetic consensus DNA HIV envelope vaccine by electroporation (EP) are better able to maintain durable antigen-specific cellular responses in the skin than mice immunized by the intramuscular route. We extended these studies by delivering a synthetic DNA vaccine encoding Leishmania glycosomal phosphoenolpyruvate carboxykinase (PEPCK) by EP and again found that the intradermal route was superior to the intramuscular route for generating skin-resident PEPCK-specific T cells. We observed that when challenged with Leishmania major parasites, mice immunized intradermally exhibited significant protection, while mice immunized intramuscularly did not. The protection seen in intradermally vaccinated mice supports the viability of this platform not only to generate skin-resident T cells but also to promote durable protective immune responses at relevant tissue sites.

CD8+ T cell cytotoxicity mediates pathology in the skin by inflammasome activation and IL-1ß production.

Deregulated CD8+ T cell cytotoxicity plays a central role in enhancing disease severity in several conditions. However, we have little understanding of the mechanisms by which immunopathology develops as a consequence of cytotoxicity. Using murine models of inflammation induced by the protozoan parasite leishmania, and data obtained from patients with cutaneous leishmaniasis, we uncovered a previously unrecognized role for NLRP3 inflammasome activation and IL-1ß release as a detrimental consequence of CD8+ T cell-mediated cytotoxicity, ultimately resulting in chronic inflammation. Critically, pharmacological blockade of NLRP3 or IL-1ß significantly ameliorated the CD8+ T cell-driven immunopathology in leishmania-infected mice. Confirming the relevance of these findings to human leishmaniasis, blockade of the NLRP3 inflammasome in skin biopsies from leishmania-infected patients prevented IL-1ß release. Thus, these studies link CD8+ T cell cytotoxicity with inflammasome activation and reveal novel avenues of treatment for cutaneous leishmaniasis, as well as other of diseases where CD8+ T cell-mediated cytotoxicity induces pathology.

Lymphocytic Choriomeningitis Virus Expands a Population of NKG2D+CD8+ T Cells That Exacerbates Disease in Mice Coinfected with Leishmania major.

Leishmaniasis is a significant neglected tropical disease that is associated with a wide range of clinical presentations and a lifelong persistent infection. Because of the chronic nature of the disease, there is a high risk for coinfection occurring in patients, and how coinfections influence the outcome of leishmaniasis is poorly understood. To address this issue, we infected mice with Leishmania major and 2 wk later with lymphocytic choriomeningitis virus (LCMV) and then monitored the course of infection. Leishmania parasites are controlled by production of IFN-γ, which leads to macrophage-mediated parasite killing. Thus, one might predict that coinfection with LCMV, which induces a strong systemic type 1 response, would accelerate disease resolution. However, we found that infection with LCMV led to significantly enhanced disease in L. major-infected animals. This increased disease correlated with an infiltration into the leishmanial lesions of NKG2D(+) CD8(+) T cells producing granzyme B, but surprisingly little IFN-γ. We found that depletion of CD8 T cells after viral clearance, as well as blockade of NKG2D, reversed the increased pathology seen in coinfected mice. Thus, this work highlights the impact a secondary infection can have on leishmaniasis and demonstrates that even pathogens known to promote a type 1 response may exacerbate leishmanial infections.

Effect of acute and regular exercise on growth hormone secretagogue receptor-1a expression in human lymphocytes, T cell subpopulation and monocytes.

The orexigenic peptide hormone ghrelin exerts potent inhibitory effects on pro-inflammatory cytokine release via the growth hormone secretagogue receptor-1a (GHS-R1a) on T cells and monocytes. As such, ghrelin is a promising therapeutic agent for the treatment of inflammatory conditions, but these effects depend on the availability of GHS-R1a. The aim of this study was to determine the effect of acute exercise on GHS-R1a expression on circulating CD14+ monocytes, total lymphocytes and CD3+ T cells. Nine male club-standard cyclists cycled for 1h at 75% V̇O2peak (EX) or rested (REST) in a randomised cross-over design. Compared with the equivalent times in REST, the concentration of circulating GHS-R1a+ lymphocytes and monocytes was higher in EX at immediately and 1 and 2h post-exercise (all p<.05). The concentration of CD3+GHS-R1a+ cells was higher in EX than in REST immediately post-exercise only (258 (203)cellsµl(-1) vs. 62 (42)cellsµl(-1), p<.05). Density of GHS-R1a receptor expression was unaffected by trial or time. Comparison of active participants at rest with 7 age-, sex- and BMI-matched sedentary controls revealed a higher concentration of GHS-R1a+ lymphocytes in active males (p<.05). These findings suggest a preferential recruitment of specific cell subpopulations expressing GHS-R1a into the peripheral circulation with acute and regular exercise. Given that the anti-inflammatory effects of ghrelin depend on the availability of GHS-R1a, the preferential recruitment of subpopulations with high anti-inflammatory potential found here add a novel aspect to the potential mechanisms by which exercise acts to reduce pro-inflammatory cytokine levels.

Identifying a Cohort of People Who Are Transgender and Gender-Diverse Within Saskatchewan's Administrative Health Databases.

This was a retrospective cohort study. Algorithms were developed to identify a cohort of people who were trans and gender diverse (PTGD) among provincial-level administrative health databases (physician, hospital, emergency department, and pharmacy) from April 1, 2012 to September 30, 2020. Then, healthcare usage was compared between the identified cohort and the general population. There were 6466 unique individuals identified in the cohort, out of a total population of 1.2 million Saskatchewan residents (~0.5%). They had a mean age of 42.5 (SD 17.7) years. 1946 (30.1%) had a female sex marker and 4560 (69.9%) had a male sex marker, which may not indicate their lived gender. The cohort had increased healthcare usage 2 years prior to their index date, compared to the general population, which continued to rise to 1 year past their index date across physician, emergency department visits, and hospitalizations. The results for drugs were mixed. The percentage of PTGD identified in Saskatchewan was comparable to other studies. Healthcare utilization among the cohort was higher than the general population. Further research could use external data sources to validate and improve the cohort identification methods. The large majority of individuals with a male sex marker deserves further investigation.

Intracellular Oxygen Transient Quantification in Vivo During Ultra-High Dose Rate FLASH Radiation Therapy.

PURPOSE: Large, rapid extracellular oxygen transients (ΔpO2) have been measured in vivo during ultra-high dose rate radiation therapy; however, it has been unclear if they match intracellular oxygen levels. Here, the endogenously produced protoporphyrin IX (PpIX) delayed fluorescence signal was measured as an intracellular in-vivo oxygen sensor to quantify these transients, with direct comparison to extracellular pO2. Intracellular ΔpO2 is closer to the cellular DNA, the site of major radiobiological damage, and therefore should help elucidate radiochemical mechanisms of the FLASH effect and potentially be translated to human tissue measurement. METHODS AND MATERIALS: PpIX was induced in mouse skin through intraperitoneal injection of 250 mg/kg of aminolevulinic acid. The animals were also administered a 50 µL intradermal injection of 10 µM oxyphor G4 (PdG4) for phosphorescence lifetime pO2 measurement. Paired oxygen transients were quantified in leg or flank tissues while delivering 10 MeV electrons in 3 µs pulses at 360 Hz for a total dose of 10 to 28 Gy. RESULTS: Transient reductions in pO2 were quantifiable in both PpIX delayed fluorescence and oxyphor phosphorescence, corresponding to intracellular and extracellular pO2 values, respectively. Reponses were quantified for 10, 22, and 28 Gy doses, with ΔpO2 found to be proportional to the dose on average. The ΔpO2 values were dependent on initial pO2 in a logistic function. The average and standard deviations in ΔpO2 per dose were 0.56 ± 0.18 mm Hg/Gy and 0.43 ± 0.06 mm Hg/Gy for PpIX and oxyphor, respectively, for initial pO2 > 20 mm Hg. Although there was large variability in the individual animal measurements of ΔpO2, the average values demonstrated a direct and proportional correlation between intracellular and extracellular pO2 changes, following a linear 1:1 relationship. CONCLUSIONS: A fundamentally new approach to measuring intracellular oxygen depletion in living tissue showed that ΔpO2 transients seen during ultra-high dose rate radiation therapy matched those quantified using extracellular oxygen measurement. This approach could be translated to humans to quantify intracellular ΔpO2. The measurement of these transients could potentially allow the estimation of intracellular reactive oxygen species production.

Child and caregiver predictors of primary caregiver participation in families of school-aged Autistic children.

Engaging in meaningful activities (e.g., leisure, spiritual, fitness) significantly affects caregivers' quality of life (QoL), yet the determinants of participation in caregivers of Autistic children remain largely unknown. The current study examined child and caregiver correlates of primary caregiver participation in meaningful activities. One hundred and six primary caregivers of Autistic children (7-12 years) were recruited from three unique cohorts of Autistic children in this cross-sectional study. Primary caregivers completed online questionnaires measuring occupational gaps (i.e., desired activities caregivers are not participating in), QoL, parenting stress, perceived family outcomes, and social support. In addition to undertaking direct assessments of children's cognition and language, primary caregivers also reported on their child's adaptive behavior, social-emotional skills, and participation. Caregivers reporting fewer occupational gaps (i.e., ≤2 desired activities) were more likely to have Autistic children with no co-occurring conditions, who were older, and with better adaptive behaviors, social-emotional skills, and more frequent home and school participation, compared to caregivers reporting many gaps (i.e., ≥3 desired activities). Caregivers with fewer occupational gaps also reported improved QoL, parenting stress, social support, perceived community inclusiveness, and family outcomes. Logistic regression analysis identified child age, child adaptive behavior, social-emotional skills, home participation, and the caregivers' perceived family outcomes and QoL as important predictors of their occupational gaps. The findings demonstrate that caregiver participation in desired activities was associated with increased functional ability and independence of the child, as well as their perceived capacity to meet their child's needs. Supporting parents' sense of efficacy in meeting their children's needs and building their skills and knowledge will serve to improve both caregiver and child outcomes.

Leisure, community, workforce participation and quality of life in primary and secondary caregivers of autistic children.

Parents of Autistic children often modify their participation in leisure, social, and employment activities to meet the caregiving needs of their child. However, few studies have examined the impact this has on caregiver quality of life (QoL). The aim in the current study was to examine the role of participation in a range of activities on QoL amongst primary and secondary caregivers of school-aged Autistic children. Eighty-eight primary (93% mothers) and 63 secondary (91% fathers) caregivers of Autistic children (aged 7- to 12-years) participated in this cross-sectional study, with time pressure, participation, social support, parenting stress, and QoL measured via an online questionnaire. Compared to secondary caregivers, primary caregivers reported fewer employment hours, increased time pressure, less participation in desired activities, and higher perceived responsibility of domestic and child-rearing tasks. Similar levels of leisure frequency, parenting stress, and QoL were identified by both caregivers. Hierarchical regression revealed caregiver participation as important for QoL in both primary and secondary caregivers. However, when measures of caregiver well-being were added to the model, the unique contribution of participation to QoL was reduced, particularly for secondary caregivers. Overall, the findings demonstrate that despite differences in caregiver roles and responsibilities, participation in meaningful activities was important for QoL in all caregivers.

Quantitative, real-time scintillation imaging for experimental comparison of different dose and dose rate estimations in UHDR proton pencil beams.

BACKGROUND: Ultra-high dose rate radiotherapy (UHDR-RT) has demonstrated normal tissue sparing capabilities, termed the FLASH effect; however, available dosimetry tools make it challenging to characterize the UHDR beams with sufficiently high concurrent spatial and temporal resolution. Novel dosimeters are needed for safe clinical implementation and improved understanding of the effect of UHDR-RT. PURPOSE: Ultra-fast scintillation imaging has been shown to provide a unique tool for spatio-temporal dosimetry of conventional cyclotron pencil beam scanning (PBS) deliveries, indicating the potential use for characterization of UHDR PBS proton beams. The goal of this work is to introduce this novel concept and demonstrate its capabilities in recording high-resolution dose rate maps at FLASH-capable proton beam currents, as compared to log-based dose rate calculation, internally developed UHDR beam simulation, and a fast point detector (EDGE diode). METHODS: The light response of a scintillator sheet located at isocenter and irradiated by PBS proton fields (40-210 nA, 250 MeV) was imaged by an ultra-fast iCMOS camera at 4.5-12 kHz sampling frequency. Camera sensor and image intensifier gain were optimized to maximize the dynamic range; the camera acquisition rate was also varied to evaluate the optimal sampling frequency. Large field delivery enabled flat field acquisition for evaluation of system response homogeneity. Image intensity was calibrated to dose with film and the recorded spatio-temporal data was compared to a PPC05 ion chamber, log-based reconstruction, and EDGE diode. Dose and dose rate linearity studies were performed to evaluate agreement under various beam conditions. Calculation of full-field mean and PBS dose rate maps were calculated to highlight the importance of high resolution, full-field information in UHDR studies. RESULTS: Camera response was linear with dose (R2 = 0.997) and current (R22 = 0.98) in the range from 2-22 Gy and 40-210 nA, respectively, when compared to ion chamber readings. The deviation of total irradiation time calculated with the imaging system from the log file recordings decreased from 0.07% to 0.03% when imaging at 12 kfps versus 4.5 kfps. Planned and delivered spot positions agreed within 0.2 ± $\pm$ 0.1 mm and total irradiation time agreed within 0.2 ± $\pm$ 0.2 ms when compared with the log files, indicating the high concurrent spatial and temporal resolution. For all deliveries, the PBS dose rate measured at the diode location agreed between the imaging and the diode within 3% ± $\pm$ 2% and with the simulation within 5% ± $\pm$ 3% CONCLUSIONS: Full-field mapping of dose and dose rate is imperative for complete understanding of UHDR PBS proton dose delivery. The high linearity and various spatiotemporal metric reporting capabilities confirm the continued use of this camera system for UHDR beam characterization, especially for spatially resolved dose rate information.

Imaging and characterization of optical emission fromex vivotissue during conventional and UHDR PBS proton therapy.

Objective. Imaging of optical photons emitted from tissue during radiotherapy is a promising technique for real-time visualization of treatment delivery, offering applications in dose verification, treatment monitoring, and retrospective treatment plan comparison. This research aims to explore the feasibility of intensified imaging of tissue luminescence during proton therapy (PT), under both conventional and ultra-high dose rate (UHDR) conditions.Approach. Conventional and UHDR pencil beam scanning (PBS) PT irradiation of freshex vivoporcine tissue and tissue-mimicking plastic phantom was imaged using intensified complementary metal-oxide-semiconductor(CMOS) cameras. The optical emission from tissue was characterized during conventional irradiation using both blue and red-sensitive intensifiers to ensure adequate spectral coverage. Spectral characterization was performed using bandpass filters between the lens and sensor. Imaging of conventional proton fields (240 MeV, 10 nA) was performed at 100 Hz frame rate, while UHDR PBS proton delivery (250 MeV, 99 nA) was recorded at 1 kHz frame rate. Dependence of optical emission yield on proton energy was studied using an optical tissue-mimicking plastic phantom and a range shifter. Finally, we demonstrated fast beam tracking capability of fast camera towardsin vivomonitoring of FLASH PT.Main results. Under conventional treatment dose rates optical emission was imaged with single spot resolution. Spot profiles were found to agree with the treatment planning system calculation within >90% for all spectral bands and spot intensity was found to vary with spectral filtration. The resultant polychromatic emission presented a maximum intensity at 650 nm and decreasing signal at lower wavelengths, which is consistent with expected attenuation patterns of high fat and muscle tissue. For UHDR beam imaging, optical yield increased with higher proton energy. Imaging at 1 kHz allowed continuous monitoring of delivery during porcine tissue irradiation, with clear identification of individual dwell positions. The number of dwell positions matched the treatment plan in total and per row showing adequate temporal capability of iCMOS imaging.Significance. For the first time, this study characterizes optical emission from tissue during PT and demonstrates our capability of fast optical tracking of pencil proton beam on the tissue anatomy in both conventional and UHDR setting. Similar to the Cherenkov imaging in radiotherapy, this imaging modality could enable a seamless, independent validation of PT treatments.