Patient Dose Reduction Research Articles

Baricitinib Dose Reduction in Patients With Rheumatoid Arthritis Achieving Sustained Disease Control: Final Results From the RA-BEYOND Study.

This study examined the effect of dose step-down in patients with rheumatoid arthritis (RA) who achieved sustained disease control with baricitinib 4 mg once daily for up to 96 weeks. Patients who completed a baricitinib phase III study could enter a long-term extension (LTE). In the LTE, patients who received baricitinib 4 mg for ≥ 15 months and maintained Clinical Disease Activity Index (CDAI) low disease activity (LDA) or remission (REM) were blindly randomized to continue with 4 mg or taper to 2 mg. If needed, 2-mg-treated patients could be rescued to 4 mg, and 4-mg-treated patients could be rescued by adding or increasing conventional synthetic disease-modifying antirheumatic drugs. Efficacy and safety were assessed through 96 weeks. Nonresponder imputation (NRI), considering rescued or discontinued patients as nonresponders, was used for CDAI response analyses. At 96 weeks, most patients maintained LDA in both 2-mg and 4-mg arms, with a lower maintenance rate in the 2-mg than the 4-mg group (NRI 59.9% and 70.2%, respectively). Patients maintained REM in the 2-mg and 4-mg arms at 30.8% and 36.6%, respectively. Rescue rates were 14.7% for baricitinib 4 mg and 22.5% for 2 mg. Of 112 patients who lost LDA in the 2-mg arm and were rescued to 4 mg, 76.2% and 75.6% achieved LDA again at 12 and 24 weeks postrescue, respectively. In a randomized, blinded, phase III LTE study, maintenance of disease control following induction of sustained LDA/REM with baricitinib 4 mg was greater with continued 4 mg than after tapering to 2 mg. Nonetheless, 76% of patients tapered to 2 mg could maintain LDA/REM or recapture with return to 4 mg, if needed.

Establishment of local diagnostic reference levels in terms of dose area product (DAP) in conventional radiology at the Regional Hospital Center of Souss Massa, Morocco

Introduction: The effectiveness of diagnostic reference levels (DRLs) in reducing the doses delivered to patients has been demonstrated. Establishing DRLs in terms of the dose surface product (DSP) is an essential step in the management of radiation doses in conventional radiology. Objective: This retrospective study aimed to assess local diagnostic reference levels (LDRLs) for four types of X-ray examinations in terms of DAP at the Regional Hospital Center of Souss Massa. Materials and methods: Data from 120 adult patients, 30 per location (thorax (PA), pelvis (AP), lumbar spine (AP) and abdomen (AP)) were collected. Patient parameters such as gender, age, BMI, clinical indications, and examination acquisition parameters such as kV, mAs, patient source distance (PSD), and exposure field dimensions were recorded for each patient. The calculation of DRLs is based on a statistical method known as the 75th percentile of the distribution of DAP. The data were statistically analysed by SPSS software V 21.0. Pearson’s parametric test was used to explore the relationship between the different quantitative variables. Results: The mean ESDs for the thorax (PA), lumbar spine (AP), abdomen (AP), and pelvis (AP) were 0.17, 2.55, 2.16, and 2.63 mGy, respectively. The mean DAP values for the thorax (PA), lumbar spine (AP), abdomen (AP), and pelvis (AP) were 16.53, 213.11, 230.55, and 265.19 cGy.cm2, respectively. The DRLs in terms of ESD for the thorax (PA), lumbar spine (AP), abdomen (AP), and pelvis (AP) were 0.17, 2.77, 2.64, 2.87 mGy, respectively. In terms of DAP, they were 16.58, 245, 291.83, and 300.45 cGy.cm², respectively. The results show a significant relationship between DAP and tension, charge, and ESD for all examinations. In addition, there was a significant relationship between DAP and BMI for abdomen X-ray, and no significant relationship for the three other X-ray examinations. Conclusion: It is possible to reduce the dose delivered to patients in the Regional Hospital Center of Souss Massa through the continuous training of radiology workers, implementation of a quality assurance program for equipment, and institutionalization of DRL as an approach to reducing patient doses and health service costs.

Ceftriaxone encephalopathy in a very elderly dialysis patient.

Ceftriaxone is widely used clinically but it can potentially cause ceftriaxone encephalopathy in individuals who are on dialysis. We describe ceftriaxone encephalopathy in a dialysis patient. The 87-year-old Japanese woman had a 9-year dialysis history. She was admitted to our department with right subcostal pain and lower back pain and was diagnosed with renal cyst hemorrhage and infection. Post-admission, we treated her with ceftriaxone (CTRX) 2g/day and bed rest, which improved her symptoms. On the 7th hospitalization day, she began to exhibit incoherent speech and unresponsiveness; by day 10, her consciousness level had decreased to grade III and myoclonus appeared. Brain MRI and a cerebrospinal fluid examination ruled out cerebrovascular disease and encephalitis. EEG showed triphasic waves predominantly in the frontal lobe. Suspecting ceftriaxone encephalopathy, we switched the antibiotic to cefazolin 1g/day. By day 12, the myoclonus decreased and the patient was able to communicate. By day 14, her consciousness level had improved to her admission level. We treated ceftriaxone encephalopathy in a dialysis patient. Although CTRX is generally thought to not require dose reduction in patients with renal failure (due to its hepatic excretion), caution is necessary as overdosage in dialysis patients can lead to myoclonus and encephalopathy.

A 17-Years Follow-up of Occupational Radiation Doses in an Interventional Cardiology Department.

Various studies have demonstrated large variations in the annual occupational exposure of medical personnel working in interventional cardiology departments, ranging from 0.1 mSv to exceeding the annual effective occupational dose limit of 20 mSv. The purpose of this study was to investigate the 17-year dynamics in the personal dosimetry records of the medical staff in one interventional cardiology department in Bulgaria. The study was performed between 2007 and 2023 and included 31 interventional cardiologists. For each of them, data from all individual dosimetry control reports were analysed. The number and complexity of interventional procedures were analysed on an annual basis. A total number of 39639 procedures performed over 17 consecutive years were classified and analysed. The results have suggested that when a newly formed team gains clinical experience, the focus shifts towards optimizing radiation exposure to patients, and it has been observed to change from 40 Gy.cm2 in 2009 to 14.8 Gy.cm2 in 2023 for diagnostic and from 146 Gy.cm2 in 2009 to 51.2 Gy.cm2 in 2023 for interventional procedures, and from 19.5 mSv/year under the lead apron in 2012 and 3.7 mSv/year in 2023 for one of the interventional cardiologists among the medical staff. The optimization process in the department has been found to be slow but consistent, starting with the routine application of basic methods to reduce the likelihood of skin injury. Any practical implementation of a methodology or process requires periodic training to raise awareness of the topic and the use of different strategies to put it into practice. Most of the reported values from individual dosimetry monitoring have been found to be in the range below 4 mSv/year, consistent with the summarised results from other studies. The radiation protection awareness program introduced in 2014 has been found to result in between a 2- and 6-fold reduction in individual effective doses for some staff members and a 2-fold reduction in typical patient doses.

Construct validity and responsiveness of ASAS Health Index assessed in two longitudinal studies of tumour necrosis factor alpha inhibitor initiation and dose reduction in patients with axial spondyloarthritis

BackgroundThe Assessment of SpondyloArthritis international Society Health Index (ASAS HI) is a novel questionnaire of global functioning for patients with axial spondyloarthritis (SpA).ObjectiveThe objective was to assess the construct validity,...

Short-Course Blinatumomab Treatment as a Bridge to Further Salvage Therapy for Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia: A Retrospective Single-Center Study.

The high cost of blinatumomab in full doses of full treatments has led to dose reduction and fewer treatment cycles for most patients in China. With current needs for cost-efficiency and resource management in health care, we retrospectively evaluated the clinical effects of short-course blinatumomab treatment for R/R Ph- B-ALL at our center. Blinatumomab was administered with 24-h continuous intravenous infusion (9 μg/day for the first 3 days and 28 μg/day for 6-10 days). The clinical data of 30 R/R B-ALL patients were collected and analyzed. A total of 25 patients (83.3%) including 13 (43.3%) with a high leukemic load (> 50%) achieved morphological CR. Twelve patients (40%) were MRD-negative. The estimated 2-year OS rate was 82.62%. The 2-year PFS rate was 78.35%. The estimated 2-year OS and PFS were significantly better in patients receiving further treatment. Our findings provide novel insights into the optimization of blinatumomab therapy, proposing a viable treatment alternative that aligns with current needs for cost-efficiency and resource management in health care.

Real-world outcomes following ibrutinib dose reduction in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma

This study used real-world data from three separate United States (US) databases to evaluate dosing patterns and time to next treatment (TTNT) following the first-incident adverse event (AE) in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) treated with first-line ibrutinib with and without dose reduction (DR). Median TTNT or death in patients with and without a DR following an AE in each database was as follows: Optum Clinformatics Data Mart (CDM): 59.5 and 30.6 months; ConcertAI: 27.1 and 18.0 months; and Medicare Fee-for-Service (FFS): 49.8 and 22.0 months, respectively. Median TTNT or death in patients with cardiac AEs, with and without a DR, was: Optum CDM: 44.4 and 22.9 months; ConcertAI: 29.9 and 18.3 months; and Medicare FFS: 49.6 and 14.0 months, respectively. Ibrutinib DR was associated with fewer outpatient visits and lower CLL/SLL-related medical costs. These findings suggest that utilizing ibrutinib DR may effectively manage tolerability without compromising clinical efficacy.

Feasibility of new thresholds for coronary artery calcium score using low-tube voltage protocols in postmortem computed tomography1

ObjectiveTo validate whether low tube voltage scans of 100 kilovolt-peak (kVp) and 80 kVp for measuring coronary artery calcium score (CACS) using computed tomography (CT) yield comparable results to the standard protocol of 120 kVp using postmortem CT (PMCT). Materials and MethodsWe obtained scans for cadavers where CAC was observed on PMCT scans. In addition to the standard protocol, tube voltage scans were also obtained under conditions of 100 kVp and 80 kVp. We obtained a newly adapted threshold under low tube voltage and compared them with the standard protocol. ResultsThe CACS was 851±1421 (p=0.99) and 861±1433 (p=0.99) for the 120-kVp and 100-kVp scans, respectively, and 845±1390 (p=0.99) for the 80-kVp scan using the newly adapted threshold. The 120-kVp and 100-kVp scans demonstrated an almost perfect correlation (r=0.99996, p<0.0001). In the Bland–Altman analysis, the 9 5% limits of agreement ranged from -44 to 25. Similarly, the CACS obtained using the adapted threshold for the 80-kVp scan also demonstrated an excellent correlation with the standard 120-kVp scan (r=0.99993, p<0.0001). In the Bland–Altman analysis, the 95 % limits of agreement ranged from -62 to 75. The effective radiation dose was 2.21±0.064 mSv (p<0.0001) for the 120-kVp scan, 1.35±0.070 mSv (p<0.0001) for the 100-kVp scan, and 0.72±0.48 mSv (p<0.0001) for the 80-kVp scan. ConclusionThis study suggests that PMCT can be used to measure CACS at low tube voltages and that significant dose reductions in patients can be expected in clinical practice.

Population Pharmacokinetic/Pharmacodynamic Study of Linezolid in Hospital-Acquired Pneumonia Patients with Renal Insufficiency.

The optimal treatment strategy in patients with hospital-acquired pneumonia (HAP) due to Gram-positive bacteria and renal insufficiency remains challenging. The objective of this study was to compare the outcomes of linezolid versus teicoplanin in HAP patients with renal insufficiency and to explore optimal dosage strategy for linezolid. The retrospective study enrolled adult patients treated with intravenous linezolid or teicoplanin at Suzhou Municipal Hospital between July 2018 and August 2023. For the comparative pharmacodynamic study, effectiveness, safety and target attainment of trough concentration (Cmin) for teicoplanin versus linezolid treatment in HAP patients with document Gram-positive bacteria and renal insufficiency were compared. For the population pharmacokinetics (PPK) analyses, linezolid concentrations collected exclusively from HAP patients with renal insufficiency were used and the optimal dosage strategy was investigated using Monte Carlo simulations. Linezolid-treated patients had a higher bacterial eradication rate than teicoplanin-treated patients (88.5% vs 63.4%, P < 0.001). A higher proportion of patients in the linezolid group experienced at least one adverse reaction (42.0% vs 25.0%, P = 0.025). Significantly more supratherapeutic Cmin, less therapeutic Cmin were achieved in the linezolid group (adjusted P < 0.05). A total of 207 linezolid concentrations from 166 patients with renal insufficiency were available for the PPK analysis. Age and creatinine clearance (CrCL) were identified as significant covariates that influenced clearance. Simulations show that 300 mg q12h provide the optimal exposure in patients with a CrCL of 60 or 45 mL/min, and 200 mg q12h was recommended for patients with a CrCL of 30 or 15 mL/min. Linezolid-treated patients with HAP and renal insufficiency had higher bacterial eradication rates, supratherapeutic exposure and adverse reactions than teicoplanin-treated patients. Linezolid dose reduction in patients with renal insufficiency improved the probability of achieving optimal exposure.

EP.12B.10 Patterns and Clinical Impact of Alectinib Dose Reduction in Patients with ALK-Positive Non- Small Cell Lung Cancer (NSCLC)

EP.12B.10 Patterns and Clinical Impact of Alectinib Dose Reduction in Patients with ALK-Positive Non- Small Cell Lung Cancer (NSCLC)

Management of patients with reduced dihydropyrimidine dehydrogenase activity receiving combined 5-fluoruracil-/capecitabine-based chemoradiotherapy.

5‑Fluoruracil (5-FU) and its oral prodrug capecitabine are mainstays in combined chemoradiotherapy regimens. They are metabolized by dihydropyrimidine dehydrogenase (DPYD). Pathogenic variants of the DPYD gene cause areduction in DPYD activity, leading to possibly severe toxicities. Therefore, patients receiving 5‑FU-/capecitabine-based chemoradiotherapy should be tested for DPYD variants. However, there are limited clinical data on treatment adjustments and tolerability in patients with decreased DPYP activity receiving combined chemoradiotherapy. Therefore, aretrospective analysis of the toxicity profiles of patients with decreased DPYD activity treated at our center was conducted. For all patients receiving 5‑FU-/capecitabine-based chemo(radio)therapy at our department, DPYD activity was routinely tested. Genotyping of four DPYD variants (DPYD*2A, DPYD*13, c.2846A > T, and haplotype B3) was conducted according to the recommendation of the German Society for Hematooncology (DGHO) using TaqMan hydrolysis polymerase chain reaction (PCR; QuantStudy3, Thermo FisherScientific, Darmstadt). DPYD variants and activity score as well as clinical data (tumor entity, treatment protocol, dose adjustments, and toxicity according to the Common Terminology Criteria for Adverse Events [CTCAE]) were assessed and reported. Of 261 tested patients, 21exhibited DPYD variants, 18of whom received chemoradiotherapy. All but one patient was treated for rectal or anal carcinoma. The observed rate of DPYD variants was 8.0%, and heterozygous haplotype B3 was the most common (5.75%). One patient exhibited ahomozygous DPYD variant. DPYD activity score was at least 0.5in heterozygous patients; chemotherapy dose was adjusted accordingly, with an applied dose of 50-75%. CTCAE grade2 skin toxicity (50%) and grade3 leukopenia (33.3%) were most common. One patient experienced atransient grade4 increase in transaminases. All high-grade toxicities were manageable with supportive treatment and transient. No CTCAE grade5 toxicities related to 5‑FU administration were observed. With dose reduction in heterozygous patients, toxicity was within the range of patients without DPYD variants. Our clinical data suggest that dose-adapted 5‑FU-/capecitabine-chemoradiotherapy regimens can be safely considered in patients with heterozygous clinically relevant DPYD variants, but that the optimal dosage still needs to be determined to avoid both increased toxicity and undertreatment in acurative setting.

Comparative evaluation of image quality between virtual grid and grid portable radiographic systems

Purpose. Virtual Grid (VG) is an image processing technique designed to address scattered radiation from radiographic systems without a physical grid. It aims to eliminate artifacts caused by grid misalignment and enhance radiographic workflow efficiency. We intend to evaluate image quality between Virtual Grid and grid-based radiographic systems across various patient thicknesses. Methods. A Fujifilm Virtual Grid and GE AMX-4 portable radiographic system was used. Image quality was assessed using MTF, NPS, LCR, and CNR. MTF calculations employed an edge-device method with a 0.1 mmCu sheet. For NPS evaluation, uniform images were acquired with multiple 30 × 30 cm solid water blocks (2 cm thick), overlaid in 2 cm increments to simulate patient sizes from 2cm to 40 cm. LCR and CNR were evaluated using a CIRS test plate with 9-hole depths for a hole diameter of 0.375’. The test object was placed on top of the detector then water blocks, while maintaining the same SID, beam quality, and exposure between the units. Visual assessments were conducted by four readers, quantifying perceived hole numbers. The weighted Cohen’s Kappa and Welch’s T-test were utilized for statistical analysis. Results. At 80% MTF, VG exhibited high contrast resolution of 1.1 l p/mm compared to 1.2 l p/mm for the grid system. VG demonstrated lower noise levels across all frequencies for equivalent patient thicknesses. Welch’s T-test indicated no significant differences in LCR (P = 0.31) and CNR (P = 0.34) between the systems. However, qualitative observation demonstrated VG’s better low contrast response for patient sizes ≥10 cm. The average weighted Cohen’s Kappa value was 0.78. Conclusion. This work indicates the Virtual Grid technology can effectively mitigate scattered radiation to improve granularity and low-contrast resolution in an image compared to a grid system. Furthermore, it can potentially reduce patient dose.

Pacritinib and concurrent azole antifungal therapy is deliverable in patients with hematologic malignancies.

Pacritinib is a novel kinase inhibitor approved for the treatment of adults with intermediate or high-risk primary or secondary myelofibrosis. Strong and moderate CYP3A4 inhibitors, such as some azole antifungals, are contraindicated or recommended to be avoided in combination with pacritinib, respectively. We aim to report our experience in patients who received pacritinib with concurrent azole antifungal therapy. We queried for patients with hematologic malignancies in the electronic medical record who received concurrent pacritinib and azole antifungal therapy. There were five cases of concurrent pacritinib and azole antifungal therapy in which none of the patients experienced grade 3 or higher non-hematologic toxicities. Some patients required dose modifications and/or interruptions in pacritinib therapy. This is the first clinical experience describing concurrent pacritinib and azole antifungals. Our experience shows that in the setting where this interaction cannot be avoided, concurrent administration is feasible with close monitoring and possible empiric dose reductions in select patients.

What are the benefits of therapeutic drug monitoring in the optimization of adalimumab therapy? a systematic review and meta-analysis up to 2022.

Persistent uncertainties exist surrounding the therapeutic drug monitoring (TDM) of adalimumab in clinical settings. To address these issues, we conducted a systematic review to assess the current evidence regarding the benefits of TDM for adalimumab. PubMed, EMBASE, and Cochrane Databases were searched from inception to October 2022. The trials regarding to the list three key questions were considered: 1) Could routine proactive TDM assist in improving outcomes in patients receiving adalimumab? 2) Could reactive TDM assist in guiding subsequent treatment strategies for patients with treatment failure to adalimumab? 3) Could TDM assist in informing dose reduction or discontinuation in patients with low disease activity or in remission treated with adalimumab? Two reviewers independently selected the studies and extracted the data. Meta-analysis was performed to calculate the relative risk (RR) and 95% confidence interval (CI). A total of 9 studies was included in this review. For proactive TDM, meta-analysis indicated that proactive TDM (n = 163/257, 63.42%) showed no significant superiority over reactive TDM and/or conventional management (n = 336/606, 55.44%) in achieving and/or maintaining clinical remission by random effects model (RR: 1.24, 95% CI 0.98-1.58, I 2 = 73%). There were three studies that supporting the reactive TDM, low drug levels in the absence of anti-drug antibodies (ADA) strongly indicate the need for dose intensification, and infliximab is a feasible choice for patients with low drug levels and ADA positivity. While swapping to another class should be considered in patients with adequate drug levels. In addition, TDM can help clinicians optimize dosing schedules and prevent overtreatment in patients who have achieved low disease activity and sufficient drug concentrations, with no predictive value for successful adalimumab discontinuation. Current evidence suggests that proactive TDM is numerically but not statistically significant superiority over reactive TDM and/or conventional management. Reactive TDM can aid in understanding treatment failure and developing subsequent therapy. For patients reaching low disease activity and remission, TDM can help successful dose reduction, while it cannot inform the successful drug discontinuation. However, existing trials are limited, and more well-designed trials are necessary to clarify the role of TDM in adalimumab treatment.

Effects of Body Mass Index on Hypertriglyceridemia Associated with Oral Bexarotene Therapy: A Post Hoc Analysis of an Open-Label Comparative Clinical Study of Combined Bexarotene and Phototherapy Versus Bexarotene Monotherapy for Japanese Patients with Cutaneous T-Cell Lymphoma.

Bexarotene, which has been approved for use in Japan since 2016, is an effective drug for cutaneous T-cell lymphoma; however, careful management is imperative because of its adverse events. We previously demonstrated the severity of bexarotene-associated hypertriglyceridemia and the need for bexarotene dose reduction for patients with cutaneous T-cell lymphoma and high body mass index (BMI); however, high BMI does not affect the efficacy of combined bexarotene and phototherapy treatment. This study aimed to verify the effects of BMI on hypertriglyceridemia associated with oral bexarotene therapy. We conducted a post hoc analysis of data from a previous randomized, open-label clinical study that compared combined bexarotene-phototherapy treatment with bexarotene monotherapy for cutaneous T-cell lymphoma by dividing patients into two groups based on BMI (<23 kg/m2 and ≥23 kg/m2). No statistically significant association was observed between patients with BMI ≥23 kg/m2 and severe hypertriglyceridemia; however, there was a significant association between BMI ≥23 kg/m2 and severe hypertriglyceridemia for patients who received bexarotene monotherapy, but not for those who received combined bexarotene-phototherapy treatment. The exact reasons for the discrepancies between the results of this thorough analysis and those of our past research are unclear. However, high BMI may be a risk factor for hypertriglyceridemia. Additional unidentified risk factors could also affect treatment outcomes. High BMI is the primary reason for hypertriglyceridemia-associated bexarotene dose reduction; however, unexplored risk factors other than high BMI could exist.

Chemotherapy Primary Dose Reduction in Older Cancer Patients: A Retrospective Cohort

Primary dose reduction (PDR) in the first course of chemotherapy is an empirical practice, commonly used in older population. Patients over 70 years old receiving a first course of chemotherapy for a solid tumor were enrolled. A total of 179 patients were included. Standard dose was used in 69.8% of patients, while 30.2% received PDR of chemotherapy. Only 29.6% received a standardized geriatric assessment. Patients receiving standard doses presented 83.2% of toxicities, while 68% of toxicities were reported in patients receiving PDR. The toxicity rate was significantly decreased in patients treated with reduced first-cycle dose of chemotherapy.

Can the Dose of Belimumab be Reduced in Patients with Systemic Lupus Erythematosus?

The aims of this study were to investigate the prevalence of dose reduction in patients with SLE treated with belimumab (BEL) in Spain, analyze treatment modalities, and determine impact on control of disease activity. Retrospective longitudinal and multicentre study of SLE patients treated with BEL. Data on disease activity, treatments and outcomes were recorded before and after reduction (6-12 months), and they were compared. A total of 324 patients were included. The dose was reduced in 29 patients (8.9%). The dosing interval was increased in 9 patients receiving subcutaneous BEL and in 6 patients receiving intravenous BEL. The dose per administration was reduced in 16 patients.Pre-reduction status was remission (2021 DORIS) in 15/26 patients (57.7%) and LLDAS in 23/26 patients (88.5%). After reduction, 2/24 patients (8.3%) and 3/22 patients (13.6%) lost remission at 6 months and 12 months, respectively (not statistically significant [NS]). As for LLDAS, 2/23 patients (8.7%) and 2/21 patients (9.5%) lost their status at 6 and 12 months, respectively (NS). Significantly fewer patients were taking glucocorticoids (GCs) at their 12-month visit, although the median dose of GCs was higher at the 12-month visit (5 [0.62-8.75] vs 2.5 [0-5] at baseline). Doses of BEL can be reduced with no relevant changes in disease activity-at least in the short term-in a significant percentage of patients, and most maintain the reduced dose. However, increased clinical or serologic activity may be observed in some patients. Consequently, tighter post-reduction follow-up is advisable.

DRL as a common language in patient dose reduction and optimization: A short note from AsiaSafe in 2024 RCRT-RST Annual Congress, Bangkok, Thailand

The AsiaSafe Asian Oceanian Symposium at the 2024 RCRT-RST Annual Congress discussed the situation and role of radiology in patient dose reduction and optimization using Diagnostic Reference Levels (DRLs) as a common language. The scientific committee of the Royal College of Radiologists of Thailand (RCRT) and Radiological Society of Thailand (RST) established the Collaboration Symposia to discuss hot health topics with participated Asian Radiological societies. At the 2024 RCRT-RST Collaboration Symposia, different views, initiatives, and ideas were presented by representatives from societies.

Impact of dose reductions on adjuvant abemaciclib efficacy for patients with high-risk early breast cancer: analyses from the monarchE study

In monarchE, adjuvant abemaciclib significantly improved invasive disease-free survival (IDFS) and distant relapse-free survival (DRFS), with sustained benefit beyond the 2-year treatment period. Abemaciclib dose reductions were allowed to proactively manage adverse events. Exploratory analyses to investigate the impact of dose reductions on efficacy were conducted. Across the three patient subgroups as defined by relative dose intensity (≤66%, 66–93%, ≥93%), the estimated 4-year IDFS rates were generally consistent (87.1%, 86.4%, and 83.7%, respectively). In the time-dependent Cox proportional hazard model, the effect of abemaciclib was consistent at the full dose compared to being reduced to a lower dose (IDFS hazard ratio: 0.905; 95% confidence interval: 0.727, 1.125; DRFS hazard ratio: 0.942; 95% confidence interval: 0.742, 1.195). These analyses showed that the efficacy of adjuvant abemaciclib was not compromised by protocol mandated dose reductions for patients with node positive, hormone receptor positive, human epidermal growth factor 2-negative, high-risk early breast cancer.

Dose Reduction in Pediatric Oncology Patients with Delayed Total-Body [18F]FDG PET/CT.

Our aim was to define a lower limit of reduced injected activity in delayed [18F]FDG total-body (TB) PET/CT in pediatric oncology patients. Methods: In this single-center prospective study, children were scanned for 20 min with TB PET/CT, 120 min after intravenous administration of a 4.07 ± 0.49 MBq/kg dose of [18F]FDG. Five randomly subsampled low-count reconstructions were generated using ¼, ⅛, [Formula: see text], and [Formula: see text] of the counts in the full-dose list-mode reference standard acquisition (20 min), to simulate dose reduction. For the 2 lowest-count reconstructions, smoothing was applied. Background uptake was measured with volumes of interest placed on the ascending aorta, right liver lobe, and third lumbar vertebra body (L3). Tumor lesions were segmented using a 40% isocontour volume-of-interest approach. Signal-to-noise ratio, tumor-to-background ratio, and contrast-to-noise ratio were calculated. Three physicians identified malignant lesions independently and assessed the image quality using a 5-point Likert scale. Results: In total, 113 malignant lesions were identified in 18 patients, who met the inclusion criteria. Of these lesions, 87.6% were quantifiable. Liver SUVmean did not change significantly, whereas a lower signal-to-noise ratio was observed in all low-count reconstructions compared with the reference standard (P < 0.0001) because of higher noise rates. Tumor uptake (SUVmax), tumor-to-background ratio, and total lesion count were significantly lower in the reconstructions with [Formula: see text] and [Formula: see text] of the counts of the reference standard (P < 0.001). Contrast-to-noise ratio and clinical image quality were significantly lower in all low-count reconstructions than with the reference standard. Conclusion: Dose reduction for delayed [18F]FDG TB PET/CT imaging in children is possible without loss of image quality or lesion conspicuity. However, our results indicate that to maintain comparable tumor uptake and lesion conspicuity, PET centers should not reduce the injected [18F]FDG activity below 0.5 MBq/kg when using TB PET/CT in pediatric imaging at 120 min after injection.