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Patients with primary tumor progression after stereotactic body radiation therapy (SBRT) for stage I non-small cell lung cancer (NSCLC) have a second chance at complete tumor eradication with salvage local therapies, including lung resection, repeat course of SBRT, and percutaneous ablative therapies. In this paper, we presented our institutions initial experience with percutaneous high-dose-rate (HDR) brachyablation for a relapsed stage I NSCLC that had been treated with SBRT 4.3 years earlier. Lung tumor measuring approximately 5 cm in maximum tumor dimension at the time of relapse was histopathologically confirmed to be persistent squamous cell carcinoma, and successfully treated with a single fraction of 24 Gy with HDR brachyablation. Treatment was delivered via two percutaneous catheters inserted under CT-guidance, and treated in less than 20 minutes. The patient was discharged home later the same day without the need for a chest tube, and has been monitored with serial surveillance scans every 3 to 6 months without evidence of further lung cancer progression or complications at 2.8 years post-HDR brachyablation procedure and 7.8 years after initial SBRT.

Previous research explicates ordinal and disordinal interactions through the concept of the "crossover point." This point is determined via simple regression models of a focal predictor at specific moderator values and signifies the intersection of these models. An interaction effect is labeled as disordinal (or ordinal) when the crossover point falls within (or outside) the observable range of the focal predictor. However, this approach might yield erroneous conclusions due to the crossover point's intrinsic nature as a random variable defined by mean and variance. To statistically evaluate ordinal and disordinal interactions, a comparison between the observable range and the confidence interval (CI) of the crossover point is crucial. Numerous methods for establishing CIs, including reparameterization and bootstrap techniques, exist. Yet, these alternative methods are scarcely employed in social science journals for assessing ordinal and disordinal interactions. This note introduces a straightforward approach for calculating CIs, leveraging an extension of the Johnson–Neyman technique. [ABSTRACT FROM AUTHOR]

Previous research recommends using measurement models of service quality such as SERVQUAL and SERVPERF. However, these models may be insufficient for measuring service quality in competitive markets, as they do not account for comparisons between competitive services. This paper proposes a new model for measuring service quality based on two comparison processes that consumers use: internal and longitudinal comparison versus external and cross-sectional comparison. The former involves comparing the experienced quality to the expected quality of a focal firm, while the latter involves comparing the experienced quality of the focal firm and that of other firms. This paper shows that internal and longitudinal comparison significantly influences customer satisfaction through external and cross-sectional comparison. It also highlights the advantages of the new model and advocates for its use in competitive markets. By comparing these dual comparison processes, the proposed model offers a more comprehensive and nuanced understanding of service quality assessment in competitive market environments. [ABSTRACT FROM AUTHOR]

PurposeTo determine the ability of image-guided high-dose-rate brachytherapy (IG-HDR) to provide local control (LC) of lesions in non-traditional locations for patients with heavily pre-treated malignancies.Material and methodsThis retrospective series included 18 patients treated between 2012 and 2014 with IG-HDR, either in combination with external beam radiotherapy (EBRT; n = 9) or as monotherapy (n = 9). Lesions were located in the pelvis (n = 5), extremity (n = 2), abdomen/retroperitoneum (n = 9), and head/neck (n = 2). All cases were performed in conjunction between interventional radiology and radiation oncology. Toxicity was graded based on CTCAE v4.0 and local failure was determined by RECIST criteria. Kaplan-Meier analysis was performed for LC and overall survival.ResultsThe median follow-up was 11.9 months. Two patients had localized disease at presentation; the remainder had recurrent and/or metastatic disease. Seven patients had prior EBRT, with a median equivalent dose in 2 Gy fractions (EQD2) of 47.0 Gy. The median total EQD2s were 34 Gy and 60.9 Gy for patients treated with monotherapy or combination therapy, respectively. Image-guided high-dose rate brachytherapy was delivered in one to six fractions. Six patients had local failures at a median interval of 5.27 months with a one-year LC rate of 59.3% and a one-year overall survival of 40.7%. Six patients died from their disease at a median interval of 6.85 months from the end of treatment. There were no grade ≥ 3 acute toxicities but two patients had serious long term toxicities.ConclusionsWe demonstrate a good one year LC rate of nearly 60%, and a favorable toxicity profile when utilizing IG-HDR to deliver high doses of radiation with high precision into targets not readily accessible by other forms of local therapy. These preliminary results suggest that further studies utilizing this approach may be considered for patients with difficult to access lesions that require LC.

PurposeTo report early clinical outcomes of high-dose-rate interstitial image-guided brachytherapy (BT) in the definitive management of locally advanced cervical cancer.MethodsWe retrospectively analyzed 31 locally advanced cervical cancer patients treated at our institution between January 2010 and April 2013. About 88% had advanced disease based on the International Federation of Gynecology and Obstetrics guidelines, and 87% received concurrent chemotherapy. All patients were treated with external beam radiation therapy to a median dose of 45 Gy (range, 39.6-58 Gy) before receiving BT. High-dose-rate BT was delivered in a single implant to a median dose of 6 Gy × five fractions to a CT-defined volume. Median total equivalent 2-Gy dose, dose covered by 90% of the high-risk clinical target volume (HR-CTV D90), and HR-CTV were 84, 87.4, and 49.9 cc, respectively. Kaplan-Meier method was used for actuarial survival analysis, and toxicity was graded using Common Terminology Criteria for Adverse Events, version 4.0.ResultsMedian followup was 19.3 months. Two-year actuarial local control, regional control, and distant metastasis (DM) were 90%, 93%, and 23.6%, respectively. Two-year disease-free survival was 55%. Genitourinary, gastrointestinal, or gynecologic Grade 3 toxicity was seen in 5 patients (3 T4a and 2 T3b) for crude rates of 13%, 7%, and 3%, respectively. Stratifying HR-CTV by 30 cc and then by HR-CTV D90 of 90 Gy showed that 100% of the local failures, regional failures, DM, and G3 toxicity occurred in >30 cc group. The rate of DM was also significantly higher in the >30 cc group (p = 0.036).ConclusionsAn interstitial approach can achieve excellent outcomes in cases where intracavitary and/or hybrid approaches are either not suitable or not available.

PurposeWe compared the dosimetry of brachyablation (BA) and stereotactic ablative radiotherapy (SABR) in the treatment of liver metastases.Methods and materialsTreatment plans for 10 consecutive liver metastasis patients, treated with SABR, were replanned for BA. BA treatment was planned using five 12 Gy fractions to the same planning target volume (PTV) used for SABR. Dosimetric parameters were compared using a Student's paired t test.Results and conclusionsBA and SABR plans had similar mean volume receiving 100% of the prescribed dose (94.1% vs. 93.9% of PTV, p = 0.8). Mean volume receiving 150% of the prescribed dose for BA was 63.6%, whereas for SABR it was 0. The minimum dose to the PTV was 65.8% for BA, whereas for SABR it was 87.4% (p = 0.0002). Liver volume receiving ≥15 Gy was similar for BA and SABR (278 vs. 256 cc, p = 0.3). Small bowel mean dose, as percent prescription dose, was higher for BA (10.8% vs. 7.1%, p = 0.006). Stomach mean dose was similar (4.9% vs. 4.8% of prescription dose, p = 0.98). Right kidney mean dose was greater for BA (6.7% vs. 4.2%, p = 0.07). BA leads to a higher target dose, similar dose to organs at risk, but potentially with lower target coverage compared with SABR. Further work is needed to determine ideal suitability for mono vs. combination therapy with this approach.

PurposeTo assess the magnitude of dosimetric reductions of a focal and ultra-focal high-dose-rate (HDR) prostate brachytherapy treatment strategy relative to standard whole gland (WG) treatment.Methods and materialsHDR brachytherapy plans for five patients treated with WG HDR monotherapy were optimized to assess different treatment strategies. Plans were generated to treat the hemigland (HG), one-third gland (1/3G), and one-sixth gland (1/6G), as well as to assess treating the WG with a boost to one of those sub-volumes (WG + HG, WG + 1/3G, WG + 1/6G). Dosimetric parameters analyzed included Target D90%, V100%, V150%, Bladder (B), Rectal (R), Urethral (U) D0.1, 1 and 2cc, Urethral V75%, and the V50% to the contralateral HG. Two-tailed t tests were used for comparison of means, and p-values less than 0.05 were considered statistically significant.ResultsTarget objectives (D90 > 100% and V100 > 97%) were met in all cases. Significant organs at risk dose reductions were achieved for all approaches compared with WG plans. 1/6G vs WG plans resulted in the greatest reduction in dose with a mean bladder D2cc 24.7 vs 64.8%, rectal D2cc 32.8 vs 65.3%, urethral D1cc 52.1 vs 103.8%, and V75 14.5 vs 75% (p < 0.05 for all comparisons).ConclusionSignificant dose reductions to organs at risk can be achieved using HDR focal brachytherapy. The magnitude of the reductions achievable with treating progressively smaller sub-volumes suggests the potential to reduce morbidity, but the clinical impact on morbidity and tumor control remain to be investigated.

PurposeTo study the dosimetric differences of various channel combinations of the Capri vaginal applicator.Methods and materialsThe Capri consists of a single central channel (R1), an inner array of 6 channels (R2), and an outer array of 6 channels (R3). Three-dimensional plans were simulated for 6 channel arrangements (R1, R2, R12, R13, R23, and R123). Treatment plans were optimized to the applicator surface or 5-mm depth while minimizing dose to organs at risk (OARs: bladder, rectum, sigmoid, and urethra). The clinical target volume (CTV) was defined as a 5-mm circumferential shell extending 4 cm in length around the applicator. Clinical target volume coverage (Dmean, D90, V100, and V150) and OAR doses (D0.1 cm3, D1 cm3, D2 cm3, and Dmean) were compared. A comparison between the Capri (R123) and a conventional single-channel applicator was also done. Statistical significance (P value

PurposeTo determine the utility of focal high-dose-rate brachytherapy for localized prostate cancer, we investigated the impact on target coverage and dose to organs at risk (OARs) with hemigland (HG) compared with whole-gland (WG) treatment.Methods and materialsA total of 10 WG implants were used to generate 10 WG and 20 HG (left and right) treatment plans optimized with the inverse planning simulation annealing algorithm using Oncentra MasterPlan (Nucletron B.V., Veenendaal, The Netherlands). The standard distribution of 17-18 catheters designed for WG was used to generate HG plans. The same OARs namely bladder, rectum, and urethra contours and dose constraints were applied for HG and WG plans. The HG contour was a modification of the WG contour whereby the urethra divided the prostate into HGs. The prescription dose was 7.25 Gy×6. Evaluated dose parameters were target dose D90, V100, and V150 and D0.1 cc, D1 cc, and D2 cc to OARs.ResultsThe HG plans had a D90, V100, and V150 to the HG target of 112%, 97.6%, and 33.8%, respectively. The WG plans had a D90, V100, and V150 to the WG target of 108%, 98.8%, and 26.5%, respectively. The OAR D2 cc doses were significantly lower in HG vs. WG plans: rectum (53.1% vs. 64.1%, p

One may measure service quality either with additive models such as SERVQUAL, SERPERF, and two-predictor model of performance and expectation, or with multiplicative models obtained by log-transformation of variables in additive models. This paper analytically compares multiplicative models with additive models. In addition, it empirically compares predictive performance of alternative models on overall service quality and customer satisfaction with a three-way factorial design: 2 forms (additive vs. multiplicative) × 3 types (SERVQUAL vs. SERVPERF vs. two-predictor model) × 2 levels (5 dimensions vs. 22 items). The empirical comparison uses the data gathered to evaluate service quality in five service industries (Hamburger Shop, Pizza Shop, Family Restaurant, Movie Theater, and Bakery Shop) with a standard SERVQUAL questionnaire. The data set includes 1,410 respondents' evaluation of service quality. The analytical and empirical comparison shows that multiplicative models have three distinct advantages. First, multiplicative models are theoretically supported by the prospect theory and the Weber's law. Second, multiplicative models allow one to identify the optimal levels of performance and expectation maximizing overall quality or customer satisfaction. Third, multiplicative models predict overall service quality and customer satisfaction better than additive models do. [ABSTRACT FROM AUTHOR]

This paper addresses two questions regarding models of service quality: single- vs. two-predictor models and items vs dimensions. This paper derives six alternative models specified by a two-way factorial design: 3 types of models (SERVQUAL vs. SERVPERF vs. two-predictor model) × 2 abstraction levels (5 dimensions vs. 22 items). It compares the alternative models with the criteria of predictability, interpretability, and usefulness. It analytically examines the alternative models with the linkages between a theoretical three-predictor model and the alternative models, and empirically compares the alternative models based on data sets collected in five service industries with a convenient sampling technique. The analyses show that the two-predictor model is superior to SERVQUAL and SERVPERF in view of the three criteria. The two-predictor model allows one to examine the effects of expectation and performance on customer satisfaction. This property is important because the management of expectation is as important as the management of performance in managing customer satisfaction. It is possible to recover the two-predictor model as well as SERVPERF from a data set required for SERVQUAL. Thus, it is reasonable to use the two-predictor model as well as SERVQUAL and SERVPERF for gaining more meaningful insights on service quality. [ABSTRACT FROM AUTHOR]

The literature on service quality recommends one to find an efficient direction for revising service quality with a combination analysis of a measurement model of service quality (SERVQUAL or SERVPERF) and the importance-performance analysis (IPA). This paper analytically assesses this recommendation. To this end, it presents a simple rule with which service firms can optimally allocate their limited resources for service quality. The simple rule revises service attributes to be proportional to the normalised demand elasticities with respect to the service attributes. This paper shows that such a combination analysis can efficiently revise service quality based on the simple rule, supporting the recommendation. However, such a combination analysis may not be efficient when the marginal costs of service attributes are not equal. This paper presents an extended rule reflecting different marginal costs of service attributes. The extended rule can be used in an extended combination analysis with a measurement model evaluating the marginal costs. We end this paper with some practical guidance for the combination analysis. [ABSTRACT FROM AUTHOR]