Impact of temporal resolution on perfusion metrics, therapy decision, and radiation dose reduction in brain CT perfusion in patients with suspected stroke.

PURPOSE: CT perfusion of the brain is a powerful tool in stroke imaging, though the radiation dose is rather high. Several strategies for dose reduction have been proposed, including increasing the intervals between the dynamic scans. We determined the impact of temporal resolution on perfusion metrics, therapy decision, and radiation dose reduction in brain CT perfusion from a large dataset of patients with suspected stroke. METHODS: We retrospectively included 3555 perfusion scans from our clinical routine dataset. All cases were processed using the perfusion software VEOcore with a standard sampling of 1.5 s, as well as simulated reduced temporal resolution of 3.0, 4.5, and 6.0 s by leaving out respective time points. The resulting perfusion maps and calculated volumes of infarct core and mismatch were compared quantitatively. Finally, hypothetical decisions for mechanical thrombectomy following the DEFUSE-3 criteria were compared. RESULTS: The agreement between calculated volumes for core (ICC = 0.99, 0.99, and 0.98) and hypoperfusion (ICC = 0.99, 0.99, and 0.97) was excellent for all temporal sampling schemes. Of the 1226 cases with vascular occlusion, 14 (1%) for 3.0 s sampling, 23 (2%) for 4.5 s sampling, and 63 (5%) for 6.0 s sampling would have been treated differently if the DEFUSE-3 criteria had been applied. Reduction of temporal resolution to 3.0 s, 4.5 s, and 6.0 s reduced the radiation dose by a factor of 2, 3, or 4. CONCLUSION: Reducing the temporal sampling of brain perfusion CT has only a minor impact on image quality and treatment decision, but significantly reduces the radiation dose to that of standard non-contrast CT.

Predictive factors for dose reduction and discontinuation of nintedanib in fibrotic interstitial lung diseases: Real life data.

Nintedanib, an intracellular inhibitor targeting multiple tyrosine kinases, has emerged as a standard treatment for various fibrotic lung diseases. Despite its efficacy, side effects such as nausea, diarrhea, and hepatotoxicity often lead to dose reduction or discontinuation. In this retrospective analysis at an university hospital's interstitial lung disease clinic, we aimed to identify baseline characteristics associated with dose adjustment or treatment discontinuation. Of the 58 patients included, 41.4% maintained the full nintedanib dose, while 31.0% required dosage reduction, and 27.6% discontinued treatment due to adverse events, predominantly gastrointestinal and hepatotoxic effects. Multivariate analysis revealed body surface area (BSA) as an independent and significant baseline risk factor (adjusted Odds Ratio [aOR] 0.22), suggesting a 78% decreased chance of requiring dose modification for every decimal point increase in BSA. A BSA cutoff of ≤1.73 m [2] exhibited a sensitivity of 73% and specificity of 91.7%, with significant impact on one-year survival under full-dose treatment (p < 0.001). Lower BSA was associated with early onset adverse effects, particularly gastrointestinal, supporting the need for regular clinical monitoring. The study emphasizes the importance of recognizing baseline factors to ensure the safety and tolerability of nintedanib, thereby preventing the progression of pulmonary fibrosis. These findings contribute to the evolving understanding of nintedanib management in fibrotic interstitial lung diseases, guiding clinicians in personalized treatment approaches.

Comparing one dose of HPV vaccine in girls aged 9-14 years in Tanzania (DoRIS) with one dose in young women aged 15-20 years in Kenya (KEN SHE): an immunobridging analysis of randomised controlled trials.

BACKGROUND: The first randomised controlled trial of single-dose human papillomavirus (HPV) vaccine efficacy, the Kenya single-dose HPV-vaccine efficacy (KEN SHE) trial, showed greater than 97% efficacy against persistent HPV16 and HPV18 infection at 36 months among women in Kenya. We compared antibody responses after one dose of HPV vaccine in the Dose Reduction Immunobridging and Safety Study (DoRIS), the first randomised trial of the single- dose regimen in girls aged 9-14 years, the target age range for vaccination, with those after one dose of the same vaccine in KEN SHE. METHODS: In the DoRIS trial, 930 girls aged 9-14 years in Tanzania were randomly assigned to one, two, or three doses of the 2-valent vaccine (Cervarix) or the 9-valent vaccine (Gardasil-9). The proportion seroconverting and geometric mean concentrations (GMCs) at month 24 after one dose were compared with those in women aged 15-20 years who were randomly assigned to one dose of the same vaccines at the same timepoint in KEN SHE. Batched samples were tested together by virus-like particle ELISA for HPV16 and HPV18 IgG antibodies. Non-inferiority of GMC ratios (DoRIS trial:KEN SHE) was predefined as a lower bound of the 95% CI less than 0·50. FINDINGS: Month 24 HPV16 and HPV18 antibody GMCs in DoRIS were similar or higher than those in KEN SHE. 2-valent GMC ratios were 0·90 (95% CI 0·72-1·14) for HPV16 and 1·02 (0·78-1·33) for HPV18. 9-valent GMC ratios were 1·44 (95% CI 1·14-1·82) and 1·47 (1·13-1·90), respectively. Non-inferiority of antibody GMCs and seropositivity was met for HPV16 and HPV18 for both vaccines. INTERPRETATION: HPV16 and HPV18 immune responses in young girls 24 months after a single dose of 2-valent or 9-valent HPV vaccine were comparable to those in young women who were randomly assigned to a single dose of the same vaccines and in whom efficacy had been shown. A single dose of HPV vaccine, when given to girls in the target age range for vaccination, induces immune responses that could be effective against persistent HPV16 and HPV18 infection at least two years after vaccination. FUNDING: The UK Department of Health and Social Care, the Foreign, Commonwealth, & Development Office, the Global Challenges Research Fund, the UK Medical Research Council and Wellcome Trust Joint Global Health Trials scheme, the Bill and Melinda Gates Foundation, the US National Cancer Institute; the US National Institutes of Health, and the Francis and Dorothea Reed Endowed Chair in Infectious Diseases. TRANSLATION: For the KiSwahili translation of the abstract see Supplementary Materials section.

Primary Treatment Modification and Treatment Tolerability Among Older Chemotherapy Recipients With Advanced Cancer.

Importance: Older adults with advanced cancer are less likely to tolerate treatment with cytotoxic chemotherapy compared with younger patients due to their aging-related conditions. Hence, oncologists sometimes opt to employ primary treatment modifications (deviation from standard of care) during the first cycle of chemotherapy. Objective: To examine the association between primary treatment modification and treatment tolerability in older adults with advanced cancer who were starting new palliative chemotherapy regimens. Design, Setting, and Participants: This cohort study was a secondary analysis of the GAP70+ (Geriatric Assessment Intervention for Reducing Toxicity in Older Patients with Advanced Cancer) trial, which was conducted between July 2014 and March 2019. The GAP70+ trial included patients aged 70 years or older who had advanced (ie, incurable) cancer, had 1 or more geriatric assessment domain impairments, and planned to start a new palliative chemotherapy regimen. Data analysis was conducted in November 2022. Exposures: Receipt of standard-of-care chemotherapy regimens vs primary treatment modification defined as any change from National Comprehensive Cancer Network guidelines or published clinical trials (eg, primary dose reduction, schedule change). Main Outcomes and Measures: Tolerability outcomes were assessed within 3 months of treatment. These outcomes included the following: (1) any grade 3 to 5 toxic effect, according to the National Cancer Institute Common Terminology Criteria for Adverse Events; (2) patient-reported functional decline, defined as the development of worse dependency in activities of daily living using scale scores; and (3) a composite adverse outcome (an end point that combined toxic effects, functional decline, and 6-month overall survival). Multivariable cluster-weighted generalized estimating equation models examined the association between primary treatment modification and outcomes adjusting for covariates. Results: This study included 609 patients with a mean (SD) age of 77.2 (5.2) years; more than half (333 [54.7%]) were men. Race and ethnicity was available for 607 patients: 39 (6.4%) were Black, 539 (88.5%) were non-Hispanic White, and 29 (4.8%) were of other race or ethnicity. Nearly half (281 [46.1%]) received a primary modified treatment regimen. The most common cancer types were gastrointestinal cancer (228 [37.4%]) and lung cancer (174 [28.6%]). In multivariable analysis, primary treatment modification was associated with a reduced risk of grade 3 to 5 toxic effects (relative risk [RR], 0.85 [95% CI, 0.77-0.94]) and functional decline (RR, 0.80 [95% CI, 0.67-0.95]). Patients who received primary treatment modification had 32.0% lower odds of having a worse composite adverse outcome (odds ratio, 0.68 [95% CI, 0.48-0.97]). Conclusions and Relevance: In this cohort study, primary treatment modification was associated with improved tolerability of chemotherapeutic regimens among older adults with advanced cancer and aging-related conditions. These findings may help optimize cancer treatment dosing in older adults with advanced cancer and aging-related conditions.

Implementing a coronary CT angiography protocol based on the body mass index: Radiation dose reduction, image quality, and diagnostic performance.

OBJECTIVES: To evaluate the relation between the coronary calcium score and the posterior choice of kilovoltage according to radiologists' criteria in a standard coronary CT angiography protocol to rule out coronary disease. To quantify the reduction in ionizing radiation after linking kilovoltage to patients' body mass index in a low-dose protocol with iterative model reconstruction. To evaluate the image quality and diagnostic performance of the low-dose protocol. MATERIAL AND METHODS: We compared anthropometric characteristics, calcium score, kilovoltage levels, size-specific dose estimates (SSDE), and the dose-length product (DLP) between a group of 50 patients who were prospectively recruited to undergo coronary CT angiography with a low-dose protocol and a historical group of 50 patients who underwent coronary CT angiography with the standard protocol. We correlated these parameters, the number of coronary segments that could not be evaluated with and without temporal padding, the attenuation, and the signal-to-noise ratio in the ascending aorta in the low-dose protocol with excellent imaging quality according to a semiquantitative scale. To calculate the diagnostic performance per patient, we used 24-month clinical follow-up including all tests as the gold standard. RESULTS: In the standard protocol, the presence of coronary calcium correlated with the selection of high kilovoltage (p = 0.02); this correlation was not found in the low-dose protocol (p = 0.47). Median values of SSDE and DLP were significantly (p < 0.001) lower and less dispersed in the low-dose protocol [9.22 mGy (IQR 7.84-12.1 mGy) vs. 26.5 mGy (IQR 21.3-36.3 mGy) in the standard protocol] and [97 mGy cm (IQR 78-134 mGy cm) vs. 253 mGy cm (IQR 216-404 mGy cm) in the standard protocol], respectively. The overall quality of the images obtained with the low-dose protocol was considered good or excellent in 96% of the studies. The parameters associated with image quality in a multivariable model (C statistic = 0.792) were heart rate (estimated coefficient, -0,12 [95% confidence interval: -0.2, -0.04]; p < 0.01) and the SSDE (estimated coefficient, -0,26 [95% confidence interval: -0.51, -0.01]; p < 0.05). The CAD-RADS modifier for a not fully evaluable or diagnostic study was used on two occasions (4%); the final measures for the diagnosis of coronary disease were sensitivity 100%, specificity 94%, and efficacy 94%. CONCLUSIONS: In the standard protocol, the radiologist selects higher kilovoltage for CT angiography studies for patients whose previous calcium score indicates the presence of coronary calcium. In the low-dose protocol, linking kilovoltage with body mass index enables the dose of radiation to be reduced by 65% while obtaining excellent or good image quality in 96% of studies and excellent diagnostic performance.

Smaller nadroparin dose reductions required for patients with renal impairment: A multicenter cohort study.

BACKGROUND: Guidelines advise 50 % and 25 % dose reduction of the therapeutic nadroparin dose (86 IU/kg) in patients with eGFR 15-29 and 30-60 ml/min respectively. For monitoring, peak anti-Xa levels are suggested. Data lack whether this results in therapeutic anti-Xa levels or in anti-Xa levels that are comparable to those of patients without renal impairment. AIMS: To determine dose ranges in patients with renal impairment that result in therapeutic anti-Xa levels and to determine the percentage of the 86 IU/kg dose that results in anti-Xa levels normally occurring in patients without renal impairment. METHODS: A retrospective cohort study was conducted in five hospitals. Patients ≥18 years of age, with an eGFR ≥ 15 ml/min were included. The first correctly sampled peak (i.e. 3-5 h after ≥ third administration, regardless of dose per patient) was included. Simulated prediction models were developed using multiple linear regression. RESULTS: 770 patients were included. eGFR and hospital affected the association between dose and anti-Xa level. The doses for peak anti-Xa levels of 0.75 IU/ml differed substantially between hospitals and ranged from 55 to 91, 65-359 and 68-168 IU/kg in eGFR 15-29, 30-60 and > 60 ml/min/1.73m2, respectively. In eGFR 15-29 and 30-60 ml/min/1.73m2, doses of 75 % and 91 % of 86 IU/kg respectively, were needed for anti-Xa levels normally occurring in patients with eGFR > 60 ml/min. CONCLUSION: We advise against anti-Xa based dose-adjustments as long as anti-Xa assays between laboratories are not harmonized and an anti-Xa target range is not validated. A better approach might be to target levels similar to eGFR > 60 ml/min/1.73m2, which are achieved by smaller dose reductions.

CT image denoising methods for image quality improvement and radiation dose reduction.

With the ever-increasing use of computed tomography (CT), concerns about its radiation dose have become a significant public issue. To address the need for radiation dose reduction, CT denoising methods have been widely investigated and applied in low-dose CT images. Numerous noise reduction algorithms have emerged, such as iterative reconstruction and most recently, deep learning (DL)-based approaches. Given the rapid advancements in Artificial Intelligence techniques, we recognize the need for a comprehensive review that emphasizes the most recently developed methods. Hence, we have performed a thorough analysis of existing literature to provide such a review. Beyond directly comparing the performance, we focus on pivotal aspects, including model training, validation, testing, generalizability, vulnerability, and evaluation methods. This review is expected to raise awareness of the various facets involved in CT image denoising and the specific challenges in developing DL-based models.

Off-isocentric VMAT technique for breast cancer: Effective dose reduction to organs at risk and its applicability based on patient anatomy.

PURPOSE: This study aims to explore the off-isocentric volumetric modulated arc therapy (offVMAT) technique for breast cancer and determine its applicability based on patient anatomical parameters. METHODS: We retrospectively analyzed 44 breast cancer patients with varied lymph node involvement using different arc designs. Off-isocentric techniques were benchmarked against previously published arc techniques: classic arcs (clVMAT), tangential arcs (tVMAT), and split arcs (spVMAT). During optimization, target coverage was made for all plans as close as possible to the criteria D99% > 95% and Dmax < 110% of the prescribed dose. A novel patient categorization, based on anatomical parameters (auxiliary structures) rather than lymph node involvement, is introduced. This categorization considers the volume of ipsilateral organs at risk (OARs) adjacent to the target. A binary regression model was developed on these anatomical parameters. It predicts the likelihood of offVMAT (P[offVMAT]) achieving better criteria. RESULTS: Using the regression model, patients were divided into two groups: P(offVMAT) > 0.5 and P(offVMAT) < 0.5. For the P(offVMAT) > 0.5 group, most tVMAT plans are unable to achieve the clinical objectives. Comparing offVMAT with spVMAT, offVMAT exhibited better dose parameters for the heart (V20, V10, and D2 are 7.1, 2.4, and 1.5 times lower respectively), ipsilateral lung (V20, V10, V5 and the mean dose are 1.4, 1.3, 1.2, and 1.2 times lower respectively). The average doses to the contralateral side are consistent. In the P(offVMAT) < 0.5 group, the tVMAT technique showed increased doses at medium and high levels, yet reduced doses in contralateral OARs compared to spVMAT and offVMAT. spVMAT showed lower doses in the contralateral lung relative to the offVMAT technique, while clVMAT trailed in both groups. Validation of the model yielded a 90% accuracy rate. CONCLUSIONS: The new off-isocentric breast planning technique effectively reduces doses to ipsilateral OARs, maintaining acceptable contralateral mean doses. This technique has an advantage over other techniques for patients with intricate anatomies. It is evaluated using anatomical parameters, which are also used to build binary regression model, which shows the dependence of anatomical parameters on whether offVMAT is preferred for individual patients. Also, such anatomical parameters provide a more objective and precise comparison between different planning techniques.

Risks of nimodipine dose reduction during the high-risk period for delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage.

Nimodipine dose reduction is recommended in case of high vasopressor demand after aneurysmal subarachnoid hemorrhage (aSAH). The aim of this study was to assess potential adverse effects of nimodipine reduction during the high-risk period for delayed cerebral ischemia (DCI) and cerebral vasospasm (CVS) between days 5 and 10 after hemorrhage. Demographic and clinical data as well as daily nimodipine dose of aSAH patients admitted between 2010 and 2019 were retrospectively analyzed. Univariable and multivariable regression analyses were performed to identify factors associated with DCI, angiographic CVS, DCI-related infarction, and unfavorable outcome. A total of 205 patients were included. Nimodipine dose reduction occurred in 108 (53%) patients ('nimodipine reduction group'), while 97 patients (47%) received the full dose ('no nimodipine reduction group'), Patients in the 'nimodipine reduction group' had significant worse WFNS and Fisher grades and developed significantly more often DCI and angiographic CVS. DCI-related infarction and unfavorable outcome were also significantly increased in the 'nimodipine reduction group.' 'Reduced nimodipine dose' was the only independent predictor for the occurrence of DCI and angiographic CVS in multivariable regression analysis. 'Poor WFNS grade' and 'reduced nimodipine dose' were identified as independent risk factors for DCI-related infarction while 'older age,' 'poor WFNS grade,' and 'reduced nimodipine dose' were associated with unfavorable outcome at 3 months after discharge. Nimodipine dose reduction during the high-risk period of DCI and CVS between days 5 and 10 after hemorrhage might abrogate the positive prognostic effects of nimodipine and should be critically evaluated.

The boundary of posterior to level V region and the theoretical feasibility of irradiation dose reduction of level Va in nasopharyngeal carcinoma.

The lymph node involvement in the posterior to level V (PLV) region is mainly observed in nasopharyngeal carcinoma (NPC). Recently, we have reported the distribution of metastatic lymph nodes in the PLV region and there are correlations between the neck node levels (NNL) of NPC, but what is the boundary of the PLV region and how to delineate it remains unclear, and we further to elaborate whether the bilateral level Va should be covered as intermediate-risk nodal regions (CTVn2, about 60 Gy equivalent) for all T and N categories based on these correlations. A total of 1021 consecutive NPC patients with N1-3 stage from January 2012 to December 2020 were reviewed. The lymph node metastasis level of each patient was evaluated according to the updated guidelines proposed in 2013. According to the distribution pattern of lymph node metastasis and the anatomical structure in the PLV region, the boundaries of PLV region was delineated, and whether it is appropriate to cover the bilateral level Va as CTVn2 for all the NPC patients was further discussed. The correlations of level Va with other NNL were studied using logistic regression model. The cranial boundary of PLV region is the caudal border of cricoid cartilage, the caudal boundary is the plane serratus anterior muscle begins to appear, the anterior boundary is the anterior border of trapezius, and the posterior boundary is the convergence of levator scapulae and trapezius. Laterally, the PLV region is limited by the medial edge of trapezius and medially by the lateral surface of levator scapulae. The nodal spread in level Va is based on the lymph node metastasis of level IIb in NPC. The PLV region is a missing NNL of head and neck tumors, especially in NPC. The proposed boundaries of the PLV region can provide a preliminary proposal for the further revision of NNL in head and neck tumors. It is theoretically feasible to reduce the prophylactic irradiation dose of the bilateral level Va in patients with N0 stage or with isolated metastases in level VIIa.

Dose reduction is a feasible strategy in patients with plaque psoriasis who achieve sustained response with secukinumab: a retrospective, multicenter cohort study in daily practice setting.

BACKGROUND: Biological therapy dose modification is a common practice in the long-term treatment of plaque psoriasis. OBJECTIVE: The objective of the study was to determine prevalence, characteristics of patients, effectiveness, treatment survival of secukinumab dose reduction (SEC-DR) strategy and assess its safety and cost implications. METHODS: A retrospective, observational, multicenter cohort study was conducted in patients with plaque psoriasis treated with secukinumab and up to 2 years of follow-up. RESULTS: In 63/347 patients with an initial standard dose regimen, SEC-DR was tried at any moment in 18.2% of them after sustained response. In 51 patients, the interval between administrations was increased while in 12 patients, monthly dose was reduced to 150 mg. Successful SEC-DR was achieved in 77.8% of the patients, with sustained PASI response to the end of the study. Survival of secukinumab treatment and safety profile were not compromised by DR. The use of DR saved 33% of the cost, including failures in which standard treatment was resumed. LIMITATIONS: The proper of the study designed and the arbitrary definition of "DR success." CONCLUSION: Off-label SEC-DR strategy was used in patients with sustained response to standard dose regimen; this strategy showed long-term efficacy without compromising treatment survival or worsening the safety profile while also being cost saving.

Early recapture of response with tofacitinib 10 mg twice daily in patients with ulcerative colitis in OCTAVE Open following dose reduction or treatment interruption in OCTAVE Sustain.

BACKGROUND AND AIM: Tofacitinib is an oral Janus kinase inhibitor for the treatment of ulcerative colitis. These post hoc analyses evaluated early improvement in patient-reported outcomes with tofacitinib 10 mg twice daily (BID) in OCTAVE Open among patients with ulcerative colitis who experienced treatment failure with placebo (retreatment subpopulation) or tofacitinib 5 mg BID (dose escalation subpopulation) during maintenance. METHODS: Endpoints based on Mayo subscores (rectal bleeding improvement, stool frequency improvement, and symptomatic [both rectal bleeding and stool frequency] improvement) were analyzed overall and by prior tumor necrosis factor inhibitor (TNFi) failure status from month (M)1-M6 in OCTAVE Open. Changes from baseline in partial Mayo score, rectal bleeding subscore, and stool frequency subscore at M1 were also analyzed, by M2 clinical response status. RESULTS: At M1 of OCTAVE Open, 83.2%, 70.3%, and 64.4% of patients in the retreatment subpopulation (n = 101) had rectal bleeding improvement, stool frequency improvement, and symptomatic improvement, respectively. Corresponding values in the dose escalation subpopulation (n = 57) were 59.6%, 50.9%, and 38.6%. For both subpopulations, results were generally consistent regardless of prior TNFi failure. In the dose escalation subpopulation, mean decrease from baseline in partial Mayo score and stool frequency subscore at M1 was greater in patients with versus without a clinical response at M2. CONCLUSIONS: Rectal bleeding improvement and stool frequency improvement were achieved by M1 in many patients receiving tofacitinib 10 mg BID in both subpopulations, with no apparent difference by prior TNFi failure. Analyses were limited by small sample sizes for some subgroups.

Hysterosalpingography: a step up for dose reduction.

AIM: To evaluate the efficiency of last image capture in interpreting a hysterosalpingogram (HSG) when compared to conventional spot views; to confirm its validity in showing pathology; to establish its use as the preferred method; and to decrease the radiation dose to the patient. MATERIALS AND METHODS: The study population consisted of women aged ≥18 years. A standard technique was performed including additional five last image capture after each spot view. Every patient had two stacks of images, one with the exposure film and one with the last image capture. The images were interpreted separately (high-dose versus low-dose) and blindly by two radiologists with different levels of training assessing for uterine abnormalities, fallopian tube abnormalities, peritoneal spillage, and incidental findings. Inter-reading variability was calculated using Kohen's kappa. RESULTS: Discrepancies between exposure film and last image capture were detected in only a minority of cases for all variables. Except for the presence of strictures, there was at least substantial agreement between the readers and almost perfect agreement regarding peritoneal spillage and fallopian tube patency, both on exposure film and last image capture. CONCLUSION: Reduction in radiation dose without compromising the diagnostic efficacy of HSG is mandatory. If the study is of sufficient quality and deemed negative on last image capture, conventional spot view can be avoided. If further detail is required, standard spot views can still be obtained. Using last image capture instead of spot films has the potential to reduce the overall radiation dose by up to 78%.

Assessment of breast cancer chemotherapy dose reduction in an integrated healthcare delivery system.

PURPOSE: Most cytotoxic drugs are dosed using body surface area (BSA), yet not all cancer patients receive the full BSA-determined dose. Prior work suggests that breast cancer patients who are obese are more likely to experience dose reduction than normal weight patients. However, the factors driving dose reduction remain unclear. METHODS: In 452 women diagnosed with stage I-IIIA primary breast cancer at Kaiser Permanente Northern California, we evaluated the association between obesity and dose reduction, and further explored other factors in relation to dose reduction, including various sociodemographic characteristics, tumor characteristics, and comorbidities. Study participants were a part of the Pathways Study, diagnosed between 2006 and 2013 and treated with cyclophosphamide + doxorubicin, followed by paclitaxel (ACT). Dose reduction was assessed using first cycle dose proportion (FCDP) and average relative dose intensity (ARDI), a metric of dose intensity over the course of chemotherapy. RESULTS: Overall, 8% of participants received a FCDP < 90% and 21.2% had an ARDI < 90%, with dose reduction increasing with body mass index. In adjusted logistic regression models, obese women had 4.1-fold higher odds of receiving an ARDI < 90% than normal weight women (95% CI: 1.9-8.9; p-trend = 0.0006). Increasing age was positively associated with an ADRI < 90%, as was the presence of comorbidity. Dose reduction was less common in later calendar years. CONCLUSION: Results offer insight on factors associated with chemotherapy dosing for a common breast cancer regimen. Larger studies are required to evaluate relevance to other regimens, and further work will be needed to determine whether dose reductions impact outcomes in obese women.

Dosimetric impact of adding non-coplanar arcs for scalp-avoidance whole-brain irradiation with volumetric-modulated arc radiotherapy on scalp dose reduction in pediatric patients with medulloblastomas.

PURPOSE: We performed scalp-avoidance whole-brain irradiation with volumetric-modulated arc therapy (SAWB-VMAT) as a component of craniospinal irradiation. In SAWB-VMAT with two coplanar arcs, radiation oncologists and medical physicists sometimes experience difficulty in reducing the dose to the scalp to below the cut-off equivalent dose in 2 Gy per fraction (assuming α/ß = 2) to 50% (EQD50%scalp ). To investigate the advantage of adding coplanar or non-coplanar arcs in reducing the dose to the scalp in SAWB-VMAT, we conducted a planning study to compare the EQD50%scalp , the dose to other organs at risk (OARs), and target coverage in VMAT with two coplanar arcs (Co2arcVMAT), VMAT with three coplanar arcs (Co3arcVMAT), and VMAT with two coplanar and two non-coplanar arcs (NcVMAT). METHODS: Co2arcVMAT, Co3arcVMAT, and NcVMAT plans were created for 10 pediatric patients with medulloblastoma. The planned target volume (PTV) included the regions of the whole brain, cervical spinal cord, cerebrospinal fluid space, and intervertebral foramen. The EQD50%scalp was evaluated separately for four areas (top, back, left, and right) in each case. The prescribed dose for the PTV was 35.2 Gy in 22 fractions. RESULTS: The median EQD50%scalp of the top area was 21.9 , 22.1 , and 18.3 Gy for Co2arcVMAT, Co3arcVMAT, and NcVMAT, respectively. The EQD50%scalp of the top area was significantly reduced in NcVMAT compared to those in Co2arcVMAT and Co3arcVMAT (p < 0.05). The median EQD50%scalp of the top area for NcVMAT was < 19.9 Gy, which is the cut-off dose for severe permanent alopecia. There were no significant differences in EQD50%scalp in the three other areas, the dose to other OARs, or the dose coverage of PTV among the three techniques. CONCLUSION: NcVMAT could reduce the EQD50%scalp of the top area below the cut-off dose of 19.9 Gy. NcVMAT appears to be a promising treatment technique for SAWB-VMAT.

Enhanced tissue distribution of ritonavir-loaded nanostructured lipid carriers-recommending its dose reduction.

Human immunodeficiency virus (HIV) mainly attacks lymphocytes of the human immune system. The untreated infection leads to acquired immune deficiency syndrome (AIDS). Ritonavir (RTV) belongs to protease inhibitors (PIs), the crucial contributors of the combination therapy used in the treatment of HIV that is called highly active antiretroviral therapy (HAART). Formulations targeting the lymphatic system (LS) play a key role in delivering and maintaining therapeutic drug concentrations in HIV reservoirs. In our previous study, we developed RTV-loaded nanostructured lipid carriers (NLCs), which contain the natural antioxidant alpha-tocopherol (AT). In the current study, the cytotoxicity of the formulation was studied in HepG2, MEK293, and H9C2 cell lines. The formulation efficacy to reach the LS was evaluated through a cycloheximide-injected chylomicron flow blockade model in Wistar rats. Biodistribution and toxicity studies were conducted in rodents to understand drug distribution patterns in various organs and to establish the safety profile of the optimized formulation (RTV-NLCs). From the MTT assay, it was found that the cell viability of the formulation is comparable with the pure drug (RTV-API). More than 2.5-folds difference in AUC was observed in animals treated with RTV-NLCs with and without cycloheximide injection. Biodistribution studies revealed higher drug exposure in the lymphoidal organs with the RTV-NLCs. No significant increase in serum biomarkers for hepatotoxicity was observed in rats dosed with the RTV-NLCs. The current study reveals the lymphatic uptake of the RTV-NLCs and their safety in rodents. As the tissue distribution of RTV-NLCs is high, hence re-adjusting the RTV-NLCs dose to get the response equivalent to RTV-API may be more beneficial with respect to its safety and efficacy.

Factors Associated With Cardiac Radiation Dose Reduction After Hypofractionated Radiation Therapy for Localized, Left-Sided Breast Cancer in a Large Statewide Quality Consortium.

PURPOSE: Limiting cardiac radiation dose is important for minimizing long-term cardiac toxicity in patients with left-sided early-stage breast cancer. METHODS AND MATERIALS: Prospectively collected dosimetric data were analyzed for patients undergoing moderately hypofractionated radiation therapy to the left breast within the Michigan Radiation Oncology Quality Consortium from 2016 to 2022. The mean heart dose (MHD) goal was progressively tightened from ≤2 Gy in 2016 to MHD ≤ 1.2 Gy in 2018. In 2021, a planning target volume (PTV) coverage goal was added, and the goal MHD was reduced to ≤1 Gy. Multivariate logistic regression models were developed to assess for covariates associated with meeting the MHD goals in 2016 to 2020 and the combined MHD/PTV coverage goal in 2021 to 2022. RESULTS: In total, 4165 patients were analyzed with a median age of 64 years. Overall average cardiac metric compliance was 91.7%. Utilization of motion management increased from 41.8% in 2016 to 2020 to 46.5% in 2021 to 2022. Similarly, use of prone positioning increased from 12.2% to 22.2% in these periods. On multivariate analysis in the 2016 to 2020 cohort, treatment with motion management (odds ratio [OR], 5.20; 95% CI, 3.59-7.54; P < .0001) or prone positioning (OR, 3.21; 95% CI, 1.85-5.57; P < .0001) was associated with meeting the MHD goal, while receipt of boost (OR, 0.25; 95% CI, 0.17-0.39; P < .0001) and omission of hormone therapy (OR, 0.65; 95% CI, 0.49-0.88; P = .0047) were associated with not meeting the MHD goal. From 2021 to 2022, treatment with motion management (OR, 1.89; 95% CI, 1.12-3.21; P = .018) or prone positioning (OR, 3.71; 95% CI, 1.73-7.95; P = .0008) was associated with meeting the combined MHD/PTV goal, while larger breast volume (≥1440 cc; OR, 0.34; 95% CI, 0.13-0.91; P = .031) was associated with not meeting the combined goal. CONCLUSIONS: In our statewide consortium, high rates of compliance with aggressive targets for limiting cardiac dose were achievable without sacrificing target coverage.