Longer time to testosterone recovery impacts favorably on outcomes for prostate cancer following androgen deprivation and radiotherapy

PURPOSE

To evaluate the impact of sustained hypogonadism after androgen deprivation therapy (ADT) associated with radiotherapy in prostate cancer (PCa) patients with biochemical relapse-free survival (bRFS).

METHODS

A retrospective cohort analysis of 213 consecutive PCa patients referred for radiotherapy plus ADT was carried out. Follow-up times including time to testosterone recovery (TTR) and bRFS were calculated from the end of ADT. Univariate and multivariate Cox regression analyses predicting bRFS were used. The optimal cutoffs for TTR and duration of ADT were determined using the maximally selected rank statistics (MSRS).

RESULTS

After a median follow-up of 104 months, 18 patients relapsed among those who had recovered testosterone levels and 9 among those who did not. Median ADT duration was 36 months. The optimal cutoff for TTR was determined using MSRS. TTR >48 months was significantly associated with better bRFS (logrank, p < 0.0027). Five-year bRFS was 100% for >48 months vs. 85% for <48 months. TTR was the only significant variable for bRFS in multivariate Cox analysis.

CONCLUSION

Our data show an association between longer TTR and bRFS values among PCa patients treated with ADT.

Study of the influence of nanoscale porosity on the microbial electroactivity between expanded graphite electrodes and Geobacter sulfurreducens biofilms

Expanded graphite (EG) electrodes gather several advantages for their utilization in microbial electrochemical technologies (MET). Unfortunately, the low microbial electroactivity makes them non-practical for implementing them as electrodes. The objective of this work is to explore the enhancement of microbial electroactivity of expanded graphite (commercial PV15) through the generation of nanopores by CO2 treatment. The changes in properties were thoroughly analysed by TG, XRD, Raman, XPS, gas adsorption, SEM and AFM, as well as microbial electroactivity in the presence of Geobacter sulfurreducens. Nanopores remarkably enhance the microbially derived electrical current (60-fold increase). Given the inaccessibility of micron-sized bacteria to these nanopores, it is suggested that the electric charge exchanged by electroactive microorganisms might be greatly affected by the capability of the electrode to compensate these charges through ion adsorption. The increased microbial current density produced on activated PV15 opens the possibility of using such materials as promising electrodes in MET.

Pilot Study for the Assessment of the Best Radiomic Features for Bosniak Cyst Classification Using Phantom and Radiologist Inter-Observer Selection

Since the Bosniak cysts classification is highly reader-dependent, automated tools based on radiomics could help in the diagnosis of the lesion. This study is an initial step in the search for radiomic features that may be good classifiers of benign-malignant Bosniak cysts in machine learning models. A CCR phantom was used through five CT scanners. Registration was performed with ARIA software, while Quibim Precision was used for feature extraction. R software was used for the statistical analysis. Robust radiomic features based on repeatability and reproducibility criteria were chosen. Excellent correlation criteria between different radiologists during lesion segmentation were imposed. With the selected features, their classification ability in benignity-malignity terms was assessed. From the phantom study, 25.3% of the features were robust. For the study of inter-observer correlation (ICC) in the segmentation of cystic masses, 82 subjects were prospectively selected, finding 48.4% of the features as excellent regarding concordance. Comparing both datasets, 12 features were established as repeatable, reproducible, and useful for the classification of Bosniak cysts and could serve as initial candidates for the elaboration of a classification model. With those features, the Linear Discriminant Analysis model classified the Bosniak cysts in terms of benignity or malignancy with 88.2% accuracy.

MRI prostate contouring is not impaired by the use of a radiotherapy image acquisition set-up. An intra- and inter-observer paired comparative analysis with diagnostic set-up images

PURPOSE

The use of MRI for radiotherapy planning purposes is growing but image acquisition using radiotherapy set-ups has impaired image quality. Whether differences in image acquisition set-up could modify organ contouring has not been evaluated. Therefore, we aimed to evaluate differences in contouring between paired of image sets that were acquired in the same scanning session using different parameters.

MATERIAL AND METHODS

Ten patients underwent RT treatment planning with MRI co-registration. MRI was carried out using two different set-ups during the same session, MRI radiotherapy set-ups and MRI diagnostic set-ups. Prostates and rectums were retrospectively contoured in both image sets by 5 radiation oncologists and 4 radiologists. Intra-observer analysis was carried out comparing organ volumes, the Dice coefficient and hausdorff distance values between two contouring rounds. Inter-observer analysis was carried out by comparing individual contours to a generated STAPLE consensus contour, which is considered the gold standard reference.

RESULTS

No significant differences were observed between MRI acquisition set-ups. Significant differences were observed for the dice and hausdorff parameters, comparing individual contours to the STAPLE consensus contour, when analysing diagnostic images between rounds, although raw values were similar.

CONCLUSION

Prostate and rectum contours did not differ significantly when using diagnostic or radiotherapy MRI acquisition set-ups.

Radiomics of CT Features May Be Nonreproducible and Redundant: Influence of CT Acquisition Parameters

Purpose To identify the reproducible and nonredundant radiomics features (RFs) for computed tomography (CT). Materials and Methods Two phantoms were used to test RF reproducibility by using test-retest analysis, by changing the CT acquisition parameters (hereafter, intra-CT analysis), and by comparing five different scanners with the same CT parameters (hereafter, inter-CT analysis). Reproducible RFs were selected by using the concordance correlation coefficient (as a measure of the agreement between variables) and the coefficient of variation (defined as the ratio of the standard deviation to the mean). Redundant features were grouped by using hierarchical cluster analysis. Results A total of 177 RFs including intensity, shape, and texture features were evaluated. The test-retest analysis showed that 91% (161 of 177) of the RFs were reproducible according to concordance correlation coefficient. Reproducibility of intra-CT RFs, based on coefficient of variation, ranged from 89.3% (151 of 177) to 43.1% (76 of 177) where the pitch factor and the reconstruction kernel were modified, respectively. Reproducibility of inter-CT RFs, based on coefficient of variation, also showed large material differences, from 85.3% (151 of 177; wood) to only 15.8% (28 of 177; polyurethane). Ten clusters were identified after the hierarchical cluster analysis and one RF per cluster was chosen as representative. Conclusion Many RFs were redundant and nonreproducible. If all the CT parameters are fixed except field of view, tube voltage, and milliamperage, then the information provided by the analyzed RFs can be summarized in only 10 RFs (each representing a cluster) because of redundancy.

Vaginal cuff brachytherapy in endometrial cancer - a technically easy treatment?

Endometrial cancer (EC) is one of the most common gynecological cancers among women in the developed countries. Vaginal cuff is the main location of relapses after a curative surgical procedure and postoperative radiation therapy have proven to diminish it. Nevertheless, these results have not translated into better survival results. The preeminent place of vaginal cuff brachytherapy (VCB) in the postoperative treatment of high- to intermediate-risk EC was given by the PORTEC-2 trial, which demonstrated a similar reduction in relapses with VCB than with external beam radiotherapy (EBRT), but VCB induced less late toxicity. As a result of this trial, the use of VCB has increased in clinical practice at the expense of EBRT. A majority of the clinical reviews of VCB usually address the risk categories and patient selection but pay little attention to technical aspects of the VCB procedure. Our review aimed to address both aspects. First of all, we described the risk groups, which guide patient selection for VCB in clinical practice. Then, we depicted several technical aspects that might influence dose deposition and toxicity. Bladder distension and rectal distension as well as applicator position or patient position are some of those variables that we reviewed.

Rectal contrast increases rectal dose during vaginal cuff brachytherapy

PURPOSE

To evaluate the impact of rectal dose on rectal contrast use during vaginal cuff brachytherapy (VCB).

METHODS AND MATERIALS

A retrospective review of gynecology patients who received some brachytherapy fractions with and without rectal contrast was carried out. Rectal contrast was instilled at the clinician's discretion to increase rectal visibility. Thirty-six pairs of CT scans in preparation for brachytherapy were analyzed. Pairs of CTs were segmented and planned using the same parameters. The rectum was always defined from 1 cm above the cylinder tip up to 1.5 cm below the last activated dwell source position. An individual plan was computed at every VCB fraction. A set of values (Dmax, D(0.1cc), D(1cc), and D(2cc)) derived from dose-volume histograms were extracted and compared according to the rectal status.

RESULTS

Rectal volume was 26.7% larger in the fractions with rectal contrast. Such an increase in volume represented a significant increase from 7.7% to 10.4% in all parameters analyzed except Dmax dose-volume histogram.

CONCLUSIONS

Avoiding rectal contrast is a simple way of decreasing the rectal dose parameters of VCB, which would mean a better therapeutic ratio. Results also suggest that action directed at maintaining the rectum empty might have the same effect.

Body Mass Index and Doses at Organs at Risk in a Mediterranean Population Treated with Postoperative Vaginal Cuff Brachytherapy

Purpose

Association between body mass index (BMI) and doses in organs at risk during postoperative vaginal cuff brachytherapy (VCB) treatment has not been evaluated. The aim of this study was to analyse the impact of BMI on the dose delivered to bladder and rectum during high-dose-rate VCB using computed tomography (CT) scans at every fraction.

Materials and Methods

A retrospective analysis of 220 planning CT sets derived from 59 patients was conducted. Every planning CT was re-segmented and re-planned under the same parameters. Rectum and bladder dose-volume histogram values (D_0.1cc, D_1cc, and D_2cc) were extracted and evaluated. The mean values for all applications per patient were calculated and correlated with BMI, as well as other factors influencing rectal and bladder doses. Multiple regression analysis performed to model organ at risk dose-volume parameters.

Results

According to World Health Organization (WHO), 6.8% of patients were normal, 35.6% were overweight, and 57.6% were class I obese. Median rectal doses were 133.5%, 110.9%, and 99.3% for D_0.1cc, D_1cc, and D_2cc, respectively. The corresponding median bladder doses were 96.2%, 80.6%, and 73.3%, respectively. BMI did not show significant association with rectal doses. However, BMI did show a significant association with evaluated bladder dose metrics (D_0.1cc, r=–0.366, p=0.004; D_1cc, r=–0.454, p < 0.001; D_2cc, r=–0.451, p < 0.001). BMI was retained in the multivariate regression models (D_0.1cc, p=0.004; D_1cc, p < 0.001; D_2cc, p=0.001).

Conclusion

In this group of Mediterranean, overweight, and moderately obese patients, BMI showed association with lower bladder dose values, but not with rectal doses.

How air influences radiation dose deposition in multiwell culture plates: a Monte Carlo simulation of radiation geometry

Radiation of experimental culture cells on plates with various wells can cause a risk of underdosage as a result of the existence of multiple air-water interfaces. The objective of our study was to quantify this error in culture plates with multiple wells. Radiation conditions were simulated with the GAMOS code, based on the GEANT4 code, and this was compared with a simulation performed with PENELOPE and measured data. We observed a slight underdosage of ∼ 4% on the most superficial half of the culture medium. We believe that this underdosage does not have a significant effect on the dose received by culture cells deposited in a monolayer and adhered to the base of the wells.

Do breast cups improve breast cancer dosimetry? A comparative study for patients with large or pendulous breasts

PURPOSE

Treating patients with large or pendulous breasts is challenging. Although brassiere cups are currently in use, no study has yet been carried out to assess their dosimetric impact. The aim of the present study was to evaluate the possible dosimetric advantages of the use of breast cups on patients with large or pendulous breasts.

MATERIALS AND METHODS

Two CT studies were carried out on 12 breast cancer patients with large or pendulous breasts, with one study involving the use of breast cups. Radiation plans were developed in accordance with each of the CT studies. The following were compared: planning target volume (PTV), volume irradiated by the 95% isodose, conformity index, homogeneity index, mean lung dose, and mean heart dose was also compared for left breast treatment. The plan involving the use of cups was found to be the best option, leading to all patients being treated with cups. The resulting acute toxicity and cosmesis were also recorded. Both scenarios involved the use of film dosimetry to evaluate the skin doses.

RESULTS

The use of breast cups resulted in a significant reduction of the PTV volume (from 1640 cm3 to 1283 cm3), of the irradiated volume (from 2154 cm3 to 1477 cm3) and of the conformity index (from 1383 to 1213). Despite slight improvements in the homogeneity index (from 0.12 to 0.10), statistical significance was not attained. The use of breast cups also led to significant dose reductions in V20 for lung (from 13.7% to 1.7%) and V5 for heart (from 9.8% to 2.7%). No differences in acute toxicity or cosmesis were observed compared to patients treated without cups.

CONCLUSIONS

Our results show that the use of brassiere cups during breast radiation therapy leads to improvements in the main dosimetric factors analyzed. Furthermore, modifications to standard irradiation protocols are not required. In summary, we consider the technique of using breast cups with radiation therapy highly appropriate when treating breast cancer patients with large or pendulous breasts.

Preparation and Characterization of Copper-Doped Cobalt Oxide Electrodes

Cobalt oxide (Co3O4) and copper-doped cobalt oxide (CuxCo(3-x)O4) films have been prepared onto titanium support by the thermal decomposition method. The electrodes have been characterized by different techniques such as cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy (XPS). The effect on the electrochemical and crystallographic properties and surface morphology of the amount of copper in the oxide layer has been analyzed. The XPS spectra correspond to a characteristic monophasic Cu-Co spinel oxides when x is below 1. However, when the copper content exceeds that for the stoichiometric CuCo2O4 spinel, a new CuO phase segregates at the surface. The analysis of the surface cation distribution indicates that Cu(II) has preference for octahedral sites.