The purpose of the work was to test if effective detective quantum efficiency (eDQE) could be useful for optimisation of radiographic factors for computed radiography (CR) for adult chest examinations. The eDQE was therefore measured across a range of kilovoltage, with and without an anti-scatter grid. The modulation transfer function, noise power spectra, transmission factor and scatter fraction were measured with a phantom made of sheets of Aluminum and Acrylic. The entrance air kerma was selected to give an effective dose of 4.9 μSv. The effective noise equivalent quanta (eNEQ) is introduced in this work. eNEQ can be considered equal to the number of X-ray quanta equivalent in the image corrected for the amount of scatter and the blurring processes. The eNEQ was then normalised to account for slight differences in the effective dose (eNEQ ED ). The peak eNEQ ED was largest at 80 kV and 100 kV with no grid and with grid respectively. At each kilovoltage, the eNEQ ED and eDQE were between 10% and 70% larger when the grid was not used. The results show that 80 kV without grid is the most suitable exposure conditions for CR in chest. This is consistent with clinical practice in the UK and previous publications recommending a low kV technique for CR for average sized adult chest imaging.

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This study aims to dosimetrically compare multi-leaf collimator (MLC)-based and cone-based 3D LATTICE radiotherapy (LRT) plans. Valley-peak ratios were evaluated using seven different 3D LATTICE designs. Target volumes of 8 cm and 12 cm were defined on the RANDO phantom. Valley-peak dose patterns were obtained by creating high-dose vertices in the target volumes. By changing the vertex diameter, vertices separation, and volume ratio, seven different LATTICE designs were generated. Treatment plans were implemented using CyberKnife and Varian RapidArc. Thermoluminescent dosimeter (TLD), EBT3 films, and electronic portal-imaging device (EPID) were employed for dosimetric treatment verification, and measured doses were compared to calculated doses. By changing the vertex diameter and vertices separation, the valley-peak ratio was exhibited little difference between the two systems. By changing the vertex diameter and volume ratio, the valley-peak ratio was observed nearly the same for the two systems. The film, TLD, and EPID dosimetry showed good agreement between the calculated and measured doses. Based on the results, we concluded that although smaller valley-peak ratios were obtained with cone-based plans, the dose-volume histograms were comparable in both systems. Also, when we evaluated the treatment duration, the MLC-based plans were more appropriate to apply the treatment in a single fraction.

Purpose/Objective(s): Adjuvant radiotherapy (ART) combined with chemotherapy (CT) is an effective adjuvant therapy in women with stage III uterine carcinoma (UC). However, there exists a sparse evidence for the optimal time to start ART. We evaluated the impact of time interval to ART initiation on survival endpoints for surgically staged patients with stage III EC receiving adjuvant multimodality therapy. Materials/Methods: We queried our prospectively-maintained database for women with FIGO stage III UC who underwent surgical staging at our institution between 12/1990 and 12/2019. All patients in the study received ART and CT with various sequences. CT consisted of 4-6 cycles of paclitaxel-carboplatin combined with ART (external beam RT (EBRT) AE vaginal brachytherapy (VB) boost). Time to RT initiation (TRTI) elapsing between surgical staging and 1 st fraction of ART was calculated in weeks for each patient. We studied the influence of TRTI on relapse-free (RFS), disease-specific (DSS) and overall (OS) survival using log-rank test (continuous) and Kaplan-Meier curves to compare outcomes at weekly increments (8-12 weeks). Clinico-pathological and treatment characteristics were dichotomized at the 8 weeks' time-point and compared. Cox regression multivariate analyses (MVA) were performed to determine independent predictors for survival endpoints. Results: 137 patients were identified. Median age was 64 years (range, 38-85), 45% of patients had non-endometrioid histology. Median number of lymph nodes (LN) examined was 23 (range, 1-55) and median number of positive LN was 2 (range, 0-18). Stage IIIC constituted 78% of the study cohort followed by stage IIIA (20%). 51% of the patients received EBRT alone, while 49% received an additional VB boost. 72 cases (52.5%) received ART 8 weeks after hysterectomy, and 47.5% (n Z 65) received ART > 8 weeks. After a median follow up of 58 months (CI: 42-66), longer TRTI > 8 weeks was associated with worse 5-year RFS (49% (CI:36-62) vs. 71% (CI:55-83); p Z 0.01), which persisted at latter time points (9-12 weeks), p<0.05 for all; with a trend when assessed as a continuous variable (p Z 0.053). TRTI was neither correlated with 5-year OS or DSS. On MVA for RFS, TRTI (> vs. 8 weeks) (HR 2.9 (CI:1.4-6.03); p Z 0.004), lymphovascular space invasion (HR 4.05; p Z 0.009) and advanced stage (HR 3.63; p Z 0.04) were all independent prognostic factors. African American race was the only independently predictive for shorter OS (HR 2.44; p Z 0.002) and DSS (HR 3.26; p Z 0.006). Conclusion: Within the context of multimodality therapy, our study suggests that earlier start of ART within 8 weeks was independently associated with improved recurrence-free survival in women with advanced stage endometrial cancer. Multi-institutional research collaboration is needed to validate our results.