Low energy excitation in liquid Sb and liquid Bi observed in inelastic x-ray scattering spectra

The dynamic structure factorS(Q,E), whereQandEare momentum and energy transfer, respectively, has been measured for liquid Sb, using inelastic x-ray scattering. A modified damped harmonic oscillator model function was applied to analyseS(Q,E) of liquid Sb and also to that of liquid Bi by Inuiet al(2015Phys. Rev.B92, 054206). The obtained excitation energy was in fairly good agreement with that predicted byab initiomolecular dynamics simulations on these liquid semi-metals. The excitation energy of the longitudinal acoustic mode in liquid Sb and liquid Bi exhibits flat-toppedQdependence whereas the lower excitation energy below the longitudinal acoustic excitation showsQ-gap behaviour. From the viscosity estimated from theQ-gap experimentally obtained, it is inferred that the lower energy excitation arises from the transverse acoustic excitation in the liquids.

Developmental potential of cryopreserved gonadal germ cells from 7-day-old chick embryos recovered using the PBS(-) method

1. A series of experiments were conducted to examine the developmental potential of cryopreserved gonadal germ cells (GGCs) recovered from both males and females on embryo day 7 (7 d-GGCs) using the PBS(-) method. Germline chimeras were produced by transferring 200 frozen/unfrozen 7 d-GGCs recovered from female/male Rhode Island Red (RIR) embryos into the dorsal aorta of 2-day-old female and male white leghorn (WL) embryos.2. Germ-cell recipient embryos were hatched and raised to sexual maturity and progeny testing was conducted by mating with RIR of the opposite sex. Brown-feathered progeny chicks were hatched in all eight possible progeny testing combinations, except for male GGC recipients produced by transferring female GGCs. Furthermore, brown-feathered progeny chicks were hatched when frozen-thawed sperm from male germline chimeras, produced by transferring unfrozen 7d-GGCs, were inseminated in normal female RIR and female WL germline chimeras.3. The results indicated that cryopreserved female/male GGCs from 7-day-old chick embryos, recovered using the PBS(-) method, were fully capable of developing into normal spermatozoa and ova in the gonad of recipient embryos under appropriate GGC donor/recipient combinations.

Phase II clinical trial of separation surgery followed by stereotactic body radiotherapy for metastatic epidural spinal cord compression

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a postoperative treatment option for spinal metastases. As data on surgery with SBRT are limited to retrospective studies, this single-center, single-arm, phase II study aimed to prospectively evaluate the outcomes of separation surgery and SBRT for metastatic epidural spinal cord compression (MESCC).

METHODS

Patients with symptomatic MESCC due to a solid carcinoma were enrolled. The protocol for treatments comprised preoperative embolization, separation surgery, and spine SBRT. Surgical procedures were performed via the posterior approach, with decompression and a fixation procedure. The prescribed dose for spine SBRT was 24 Gy in two fractions. The primary endpoint was the 12-month local failure (LF) rate. The secondary endpoints were ambulatory functions and adverse effects.

RESULTS

Thirty-three patients were registered between November 2017 and October 2019. All patients satisfied the inclusion criteria, and all but one completed the protocol treatment. Twenty-three patients (70%) had radioresistant lesions. The Bilsky grade at registration was 1c, 2, and 3 in 4, 8, and 21 patients, respectively. The median follow-up duration after registration was 15 (range 3-35) months. Three months after the administration of treatments according to the protocol, 90% of the patients (26/29) had diseases of Bilsky grade ≤ 1. The 12-month LF rate was 13%. Twenty patients could walk normally or with a cane 12 months after registration. Radiation-induced myelopathy, radiculopathy, and vertebral compression fracture were observed in zero, one, and six patients, respectively.

CONCLUSIONS

Separation surgery with SBRT for MESCC was effective in decompression and long-term local control. These findings warrant larger randomized controlled trials to compare SBRT with conventional radiotherapy.

Development of a physical geometric phantom for deformable image registration credentialing of radiotherapy centers for a clinical trial

PURPOSE

This study aimed to develop a physical geometric phantom for the deformable image registration (DIR) credentialing of radiotherapy centers for a clinical trial and tested the feasibility of the proposed phantom at multiple domestic and international institutions.

METHODS AND MATERIALS

The phantom reproduced tumor shrinkage, rectum shape change, and body shrinkage using several physical phantoms with custom inserts. We tested the feasibility of the proposed phantom using 5 DIR patterns at 17 domestic and 2 international institutions (21 datasets). Eight institutions used the MIM software (MIM Software Inc, Cleveland, OH); seven used Velocity (Varian Medical Systems, Palo Alto, CA), and six used RayStation (RaySearch Laboratories, Stockholm, Sweden). The DIR accuracy was evaluated using the Dice similarity coefficient (DSC) and Hausdorff distance (HD).

RESULTS

The mean and one standard deviation (SD) values (range) of DSC were 0.909 ± 0.088 (0.434-0.984) and 0.909 ± 0.048 (0.726-0.972) for tumor and rectum proxies, respectively. The mean and one SD values (range) of the HD value were 5.02 ± 3.32 (1.53-20.35) and 5.79 ± 3.47 (1.22-21.48) (mm) for the tumor and rectum proxies, respectively. In three patterns evaluating the DIR accuracy within the entire phantom, 61.9% of the data had more than a DSC of 0.8 in both tumor and rectum proxies. In two patterns evaluating the DIR accuracy by focusing on tumor and rectum proxies, all data had more than a DSC of 0.8 in both tumor and rectum proxies.

CONCLUSIONS

The wide range of DIR performance highlights the importance of optimizing the DIR process. Thus, the proposed method has considerable potential as an evaluation tool for DIR credentialing and quality assurance.

[Quality Assurance of Bone SBRT]

Stereotactic body radiation therapy (SBRT) is a high-precision radiation therapy technique that enables to deliver a high ablative biological dose in 1 to 5 high dose-fractions despite sparing the high dose of adjacent organs at risk. SBRT has emerged as an alternative to conventional radiation therapy for spinal metastases and has been applied to patients with non-spine bone metastases as well. Since bone SBRT is the technique of high biologically effective dose to the local lesion, quality assurance (QA) of the entire treatment process is an essential for performing SBRT. This report provides QA procedures for performing bone SBRT.

Efficacy and toxicity of re-irradiation spine stereotactic body radiotherapy with respect to irradiation dose history

OBJECTIVE

We aimed to clarify the outcomes of re-irradiation stereotactic body radiotherapy for spinal metastases with a uniform dose fractionation schedule at our institution.

METHODS

Data of patients treated with re-irradiation stereotactic body radiotherapy for spinal metastases (September 2013-March 2020) were retrospectively reviewed. The prescribed dose was 24 Gy in two fractions. The spinal cord dose constraint and dose for previously irradiated cases ≥50 Gy in 25 fractions were 12.2 Gy (maximum dose) and 11 Gy, respectively. The endpoints were pain control, local failure and adverse effects. Pain status was measured on a scale of 0-10 using the patients' self-reports and pain response was defined using international consensus criteria. Local failure was defined as tumor progression on imaging evaluations.

RESULTS

We assessed 133 lesions in 123 patients, where 70 (52.6%) had three or more spinal levels treated, 58 (43.6%) had previous irradiation doses of 40 Gy or more and 53 (39.8%) had the targets compressing the cord. The median follow-up was 12 months and the 3-, 6- and 12-month pain response rate was 75, 64 and 59%, respectively. The 1-year local failure rate was 25.8%. Previous irradiation dose was not correlated with local failure rate (P = 0.13). Radiation-induced myelopathy, radiculopathy and vertebral compression fractures were observed in 4 (3.0%), 2 (1.5%) and 17 (13.8%) lesions, respectively. A trend towards an association between any toxicity and previous irradiation dose was not observed.

CONCLUSIONS

Re-irradiation spine stereotactic body radiotherapy achieved good local control and pain control, with reduced risk of radiation myelopathy.

High neutrophil-to-lymphocyte ratio is a predictor of short-term survival for patients with recurrent cervical cancer after radiation-based therapy

AIM

Patients with recurrent cervical cancer after radiotherapy have poor prognoses because of the lack of effective treatment options. Biomarkers to predict survival outcomes for recurrent cervical cancer are warranted because patients with limited life expectancy sometimes benefit from less aggressive treatment in combination with early palliative care. Therefore, we aimed to explore a predictive biomarker for the outcomes of patients with recurrent cervical cancer.

METHODS

We retrospectively investigated 231 patients initially treated with radiation-based therapy between January 2004 and December 2015. The associations between clinicopathological features at the time of relapse and overall survival after relapse were assessed. As factors which reflect patients' conditions, we particularly focused on C-reactive protein-to-albumin ratio (CAR) and neutrophil-to-lymphocyte ratio (NLR) at the time of relapse. Additionally, we investigated biomarkers predictive of short-term survival.

RESULTS

Among 231 patients, 91 patients experienced relapse and 74 patients died during the follow-up period. Multivariate analysis revealed that treatment after relapse, CAR, and NLR was significantly associated with overall survival. Among them, treatment after relapse significantly affected survival outcomes, and patients who received definitive local treatment had a better 3-year survival rate than those who received other treatments. Conversely, NLR was the most influential biomarker for short-term survival, and the prognosis of patients with high NLRs was much worse than those with low NLRs.

CONCLUSIONS

This study thus demonstrated that, for the patients with recurrent cervical cancer who received radiation-based therapy, definitive local treatment can provide long-term survival and extremely high NLRs are predictive of short-term survival.

Stereotactic body radiotherapy for bone metastases in patients with colorectal cancer

OBJECTIVE

To clarify the clinical outcomes of stereotactic body radiotherapy for colorectal cancer-derived bone metastases and identify factors predicting treatment failure.

METHODS

Patients treated with stereotactic body radiotherapy for bone metastases from colorectal cancer between September 2013 and June 2019 were retrospectively reviewed. The prescribed dose for spine and non-spine bone metastases was 24 Gy in two fractions and 35 Gy in five fractions, respectively. The end point was local failure, which was defined as tumour progression on imaging evaluations. In addition, various treatment- and tumour-specific factors were evaluated to determine predictors of local failure.

RESULTS

This study included 43 lesions in 38 patients, with solitary bone metastases in 18 lesions (42%), re-irradiation stereotactic body radiotherapy in 28 lesions (65%) and postoperative stereotactic body radiotherapy due to spinal cord compression in 10 lesions (23%). The median follow-up after stereotactic body radiotherapy was 12 (range, 2-60) months. The 1-year LF rate was 44%. In the univariate analysis, sacral metastases (P = 0.02) were found to be significantly correlated with LF, and multiple-course systemic therapy before stereotactic body radiotherapy (P= 0.06) and large target volume (P = 0.07) showed a trend towards an association with LF. However, these factors were not independent predictors of LF in the multivariate analysis.

CONCLUSION

More than 40% of the lesions treated with stereotactic body radiotherapy for bone metastases from colorectal cancer showed LF within 1 year. No poor prognostic factors could be identified statistically. The poor outcomes in all groups indicate that the treatment intensity of the stereotactic body radiotherapy was insufficient to control colorectal cancer bone metastases.

Dose-Dependent Radiation-Induced Myocardial Damage in Esophageal Cancer Treated With Chemoradiotherapy: A Prospective Cardiac Magnetic Resonance Imaging Study

Purpose

The purpose of this prospective study was to evaluate radiation-induced myocardial damage after mediastinal radiation therapy (RT) using late gadolinium-enhancement (LGE) magnetic resonance imaging (MRI).

Methods and Materials

We enrolled 19 patients with esophageal cancer who were expected to have long-term survival by definitive treatment. They underwent delayed contrast-enhanced MRI (19 patients before treatment, 19 patients 6 months after treatment, and 12 patients 1.5 years after treatment). Dose distribution of the left ventricle was made using computed tomography, and the dose volume histogram of the left ventricle was calculated. Myocardial signal intensities in individual MRIs were normalized by the mean values in regions receiving low doses (<5 Gy). Changes in the normalized signal intensities after mediastinal radiation therapy were compared among regions where irradiation doses were 0 to 10 Gy, 10 to 20 Gy, 20 to 30 Gy, 30 to 40 Gy, 40 to 50 Gy, and 50 to 60 Gy, and we investigated whether intensity change was detected in a dose-dependent manner.

Results

The registered patients were treated with concurrent chemoradiotherapy with a median total dose of 60 Gy (50.4-66 Gy). Chemotherapy consisting of cisplatin and 5-fluorouracil was administered. In the population-based dose-response curve, dose-dependent intensity changes progressively increased in regions receiving more than 30 Gy. The averages of relative intensity change at 6 months and 1.5 years after treatment were 1.1% and −1.9% at 20 to 30 Gy and 37.5% and 17.5% at 40 to 50 Gy, respectively. LGE in regions receiving more than 30 Gy was detected in 68% (13/19) of the patients.

Conclusions

A dose-dependent relationship for myocardial signal intensity change was found by using LGE MRI. It may be necessary to reduce the volume of the myocardium receiving more than 30 Gy.

Phase 2 Clinical Trial of Stereotactic Body Radiation Therapy for Painful Nonspine Bone Metastases

PURPOSE

The present multicenter, single-arm, phase 2 study aimed to prospectively evaluate the palliative efficacy of stereotactic body radiation therapy (SBRT) in patients with painful nonspine bone metastases.

METHODS AND MATERIALS

Patients with painful (≥2 points on a 0-to-10 scale) nonspine bone metastases from a solid tumor were enrolled. The prescribed dose was 35 Gy in 5 fractions. The primary endpoint was overall pain response rate (complete response [CR] and partial response [PR]) as measured per the International Consensus on Palliative Radiotherapy Endpoints guideline 6 months after SBRT.

RESULTS

Forty-one osseous lesions in 38 patients were registered between June 2018 and June 2019. All lesions satisfied the inclusion criteria, and the patients completed the protocol treatment. Patients most commonly had lung cancer (22%), followed by prostate cancer, uterus cancer, and renal cell carcinoma (15%, 15%, and 12%, respectively). Bone metastases were most commonly located in coxal bones (56%). The median duration of follow-up after registration was 8 months (range, 1-19 months). Among evaluable lesions at 3 and 6 months after SBRT, the 3- and 6-month pain response rates were 78% and 75%, respectively. The local control rate at 6 months was 92%. Seven patients (17%) experienced bone fracture after irradiation, and 3 patients (7%) experienced grade 2 limb edema. One patient had regrowth of coxal bone metastases, and the tumor penetrated the sigmoid colon. Soft tissue abscess around the tumor and osteonecrosis of coxal bones were confirmed. The patient died of infection 4 months after SBRT and was determined to be a possible treatment-related death.

CONCLUSIONS

This prospective clinical trial showed that SBRT for nonspine bone metastases was effective in terms of pain palliation. These findings warrant a larger randomized controlled trial to compare SBRT with conventional radiation therapy. Additionally, operation history should be considered as a risk factor for edema.

Extreme skeletal muscle loss during induction chemotherapy is an independent predictor of poor survival in advanced epithelial ovarian cancer patients

AIM

Skeletal muscle loss is often observed in advanced cancer patients. This study investigates whether skeletal muscle loss is associated with survival outcomes of advanced epithelial ovarian cancer (EOC) patients after induction chemotherapy (IC) in a Japanese cohort. Whether serum inflammatory markers are associated with skeletal muscle changes is also addressed.

METHODS

We retrospectively reviewed 60 patients with stage III/IV EOC who underwent IC between 2010 and 2017. Skeletal muscle area (SMA) was measured at the third lumbar vertebrae level on a single axial computed tomography-scan image. Receiver operating curve analysis was used to determine cut-off values of pre- and post-IC SMA and SMA ratio (SMAR). Univariate and multivariate analyses of overall survival (OS) were conducted using the log-rank test and Cox proportional hazards regression model, respectively.

RESULTS

The SMA decreased significantly after IC (P = 0.019). The cut-off value between low and high SMAR was 0.96. High or low SMAR was observed in 34 (57%) and 26 (43%) patients, respectively. Univariate analysis revealed that low SMAR was associated with poor OS (P = 0.025). Multivariate analysis showed that incomplete resection during interval debulking surgery (hazard ratio, 0.30; 95% CI, 0.11-0.80; P = 0.016) and a low SMAR (hazard ratio, 3.17; 95% CI, 1.18-9.06; P = 0.022) were independent predictors of poor OS. Of the serum inflammatory markers investigated, only post-IC absolute neutrophil count correlated significantly with SMAR (P = 0.012).

CONCLUSION

Low SMAR can be used to predict poor prognosis in advanced EOC patients who have undergone IC.

Development of a dynamic deformable thorax phantom for the quality management of deformable image registration

The purpose of this study was to develop a novel dynamic deformable thorax phantom for deformable image registration (DIR) quality assurance (QA) and to verify as a tool for commissioning and DIR QA. The phantom consists of a base phantom, an inner phantom, and a motor-derived piston. The base phantom is an acrylic cylinder phantom with a diameter of 180 mm. The inner phantom consists of deformable, 20 mm thick disk-shaped sponges. To evaluate the physical characteristics of the phantom, we evaluated its image quality and deformation. DIR accuracies were evaluated using the three types of commercially DIR software (MIM, RayStation, and Velocity AI) to test the feasibility of this phantom. We used different DIR parameters to test the impact of parameters on DIR accuracy in various phantom settings. To evaluate DIR accuracy, a target registration error (TRE) was calculated using the anatomical landmark points. The three locations (i.e., distal, middle, and proximal positions) had different displacement amounts. This result indicated that the inner phantom was not moved but deformed. In cases with different phantom settings and marker settings, the ranges of the average TRE were 0.63-15.60 mm (MIM). In cases with different DIR parameters settings, the ranges of the average TRE were as follows: 0.73-7.10 mm (MIM), 8.25-8.66 mm (RayStation), and 8.26-8.43 mm (Velocity). These results suggest that our phantom could evaluate the detailed DIR behaviors with TRE. Therefore, this is indicative of the potential usefulness of our phantom in DIR commissioning and QA.

Evaluation of four-dimensional cone beam computed tomography ventilation images acquired with two different linear accelerators at various gantry speeds using a deformable lung phantom

We evaluated four-dimensional cone beam computed tomography (4D-CBCT) ventilation images (VI_CBCT) acquired with two different linear accelerator systems at various gantry speeds using a deformable lung phantom. The 4D-CT and 4D-CBCT scans were performed using a computed tomography (CT) scanner, an X-ray volume imaging system (Elekta XVI) mounted in Versa HD, and an On-Board Imager (OBI) system mounted in TrueBeam. Intensity-based deformable image registration (DIR) was performed between peak-exhale and peak-inhale images. VI_CBCT- and 4D-CT-based ventilation images (VI_CT) were derived by DIR using two metrics: one based on the Jacobian determinant and one on changes in the Hounsfield unit (HU). Three different DIR regularization values (λ) were used for VI_CBCT. Correlations between the VI_CBCT and VI_CT values were evaluated using voxel-wise Spearman's rank correlation coefficient (r). In case of both metrics, the Jacobian-based VI_CBCT with a gantry speed of 0.6 deg/sec in Versa HD showed the highest correlation for all the gantry speeds (e.g., λ = 0.05 and r = 0.68). Thus, the r value of the Jacobian-based VI_CBCT was greater or equal to that of the HU-based VI_CBCT. In addition, the ventilation accuracy of VI_CBCT increased at low gantry speeds. Thus, the image quality of VI_CBCT was affected by the change in gantry speed in both the imaging systems. Additionally, DIR regularization considerably influenced VI_CBCT in both the imaging systems. Our results have the potential to assist in designing CBCT protocols, incorporating VI_CBCT imaging into the functional avoidance planning process.

The impact of 4DCT-ventilation imaging-guided proton therapy on stereotactic body radiotherapy for lung cancer

Functional lung avoidance during radiotherapy can help reduce pulmonary toxicity. This study assessed the potential impact of four-dimensional computed tomography (4DCT)-ventilation imaging-guided proton radiotherapy (PT) on stereotactic body radiotherapy (SBRT) by comparing it with three-dimensional conformal radiotherapy (3D-CRT) and volumetric modulated arc therapy (VMAT), which employ photon beams. Thirteen lung cancer patients who received SBRT with 3D-CRT were included in the study. 4DCT ventilation was calculated using the patients' 4DCT data, deformable image registration, and a density-change-based algorithm. Three functional treatment plans sparing the functional lung regions were developed for each patient using 3D-CRT, VMAT, and PT. The prescribed doses and dose constraints were based on the Radiation Therapy Oncology Group 0618 protocol. We evaluated the region of interest (ROI) and functional map-based dose-function metrics for 4DCT ventilation and the irradiated dose. Using 3D-CRT, VMAT, and PT, the percentages of the functional lung regions that received ≥ 5 Gy (fV5) were 26.0%, 21.9%, and 10.7%, respectively; the fV10 were 14.4%, 11.4%, and 9.0%, respectively; and fV20 were 6.5%, 6.4%, and 6.6%, respectively, and the functional mean lung doses (fMLD) were 5.6 Gy, 5.2 Gy, and 3.8 Gy, respectively. These results indicated that PT resulted in a significant reduction in fMLD, fV5, and fV10, but not fV20. The use of PT reduced the radiation to highly functional lung regions compared with those for 3D-CRT and VMAT while meeting all dose constraints.

Radiation therapy and the risk of herpes zoster in patients with cancer

BACKGROUND

The role and impact of radiation therapy (RT) on the development of herpes zoster (HZ) has not been well studied. The objective of this study was to investigate the association between RT and HZ.

METHODS

A propensity score-matched, retrospective cohort study was conducted using institutional cancer registry data and medical records from 2011 to 2015. The risk of developing HZ in the RT and non-RT groups was compared using a Cox proportional hazards model. Associations also were explored between the RT field and the anatomic location of HZ in patients who developed HZ after RT. The expected number of HZ events within the radiation field was calculated according to the RT received by each patient; then, this number was compared with the observed number of in-field events.

RESULTS

Of 17,655 patients, propensity score matching yielded 4350 pairs; of these, 3891 pairs were eligible for comparison. The cumulative incidence of HZ in the RT group (vs the non-RT group) during the first 5 years after the index date was 2.1% (vs 0.7%) at 1 year, 3.0% (vs 1.0%) at 2 years, 3.4% (vs 1.3%) at 3 years, 4.1% vs 1.7% at 4 years, and 4.4% vs 1.8% at 5 years. The RT group showed a significantly higher risk of HZ than the non-RT group (hazard ratio, 2.59, 95% CI, 1.84-3.66). In the 120 patients who developed HZ after RT, HZ events were observed significantly more frequently within the RT field than expected (74 vs 43.8 events; P < .001).

CONCLUSIONS

Patients with cancer who received RT showed a significantly higher risk of HZ, which was commonly observed within the radiation field.

Quantitative analysis of intra-fractional variation in CT-based image guided brachytherapy for cervical cancer patients

We quantified intra-fractional dose variation and organ movement during CT-based 3D-image guided brachytherapy (3D-IGBT) in cervical cancer patients. Fifteen patients who underwent CT-based 3D-IGBT were studied. For all patients, pre-delivery CT for treatment planning after applicator insertion and post-delivery CT after dose delivery without changing the applicator position were acquired. Pre- and post-delivery CT were rigidly fused by matching the inserted applicator and planned dose on pre-delivery CT (pre-delivery dose) was mapped on post-delivery CT (post-delivery dose). D2, D1, and D0.1 cm³ of the rectum and bladder were compared between pre- and post-delivery doses with contours on each CT image. Organ movement and deformation was evaluated using deformation vector fields calculated by deformable image registration between pre- and post-delivery CT. We also evaluated dose variation and DVF between with and without a catheter to control filling. Differences in all DVH parameters were <±3% in physical dose and ± 5% in EQD2. However, a > 15% dose difference was found in 13.8% of the fractions in rectum D2 cm³ and in 11.1% of those in bladder D2 cm³. The mean value of DVF for bladder was larger than that of rectum, especially for the superior-inferior (S-I) direction. Insertion catheters in bladder reduced mean dose and DVF variation compared with that of without catheters. In fraction groups with large dose increasing, DVF in the S-I direction was significantly larger than that of other fraction groups. Our results indicated that preparation is needed to reduce changes in the S-I direction affect dose variation.

Search for Electron Antineutrino Appearance in a Long-Baseline Muon Antineutrino Beam

Electron antineutrino appearance is measured by the T2K experiment in an accelerator-produced antineutrino beam, using additional neutrino beam operation to constrain parameters of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. T2K observes 15 candidate electron antineutrino events with a background expectation of 9.3 events. Including information from the kinematic distribution of observed events, the hypothesis of no electron antineutrino appearance is disfavored with a significance of 2.40σ and no discrepancy between data and PMNS predictions is found. A complementary analysis that introduces an additional free parameter which allows non-PMNS values of electron neutrino and antineutrino appearance also finds no discrepancy between data and PMNS predictions.

Variations Between Dose-Ventilation and Dose-Perfusion Metrics in Radiation Therapy Planning for Lung Cancer

Purpose

Currently, several active clinical trials of functional lung avoidance radiation therapy using different imaging modalities for ventilation or perfusion are underway. Patients with lung cancer often show ventilation-perfusion mismatch, whereas the significance of dose-function metric remains unclear. The aim of the present study was to compare dose-ventilation metrics with dose-perfusion metrics for radiation therapy plan evaluation.

Methods and Materials

Pretreatment 4-dimensional computed tomography and ^99mTc-macroaggregated albumin single-photon emission computed tomography perfusion images of 60 patients with lung cancer treated with radiation therapy were analyzed. Ventilation images were created using the deformable image registration of 4-dimensional computed tomography image sets and image analysis for regional volume changes as a surrogate for ventilation. Ventilation and perfusion images were converted into percentile distribution images. Analyses included Pearson’s correlation coefficient and comparison of agreements between the following dose-ventilation and dose-perfusion metrics: functional mean lung dose and functional percent lung function receiving 5, 10, 20, 30, and 40 Gy (fV₅, fV₁₀, fV₂₀, fV₃₀, and fV₄₀, respectively).

Results

Overall, the dose-ventilation metrics were greater than the dose-perfusion metrics (ie, fV₂₀, 26.3% ± 9.9% vs 23.9% ± 9.8%). Correlations between the dose-ventilation and dose-perfusion metrics were strong (range, r = 0.94-0.97), whereas the agreements widely varied among patients, with differences as large as 6.6 Gy for functional mean lung dose and 11.1% for fV₂₀. Paired t test indicated that the dose-ventilation and dose-perfusion metrics were significantly different.

Conclusions

Strong correlations were present between the dose-ventilation and dose-perfusion metrics. However, the agreement between the dose-ventilation and dose-perfusion metrics widely varied among patients, suggesting that ventilation-based radiation therapy plan evaluation may not be comparable to that based on perfusion. Future studies should elucidate the correlation of dose-function metrics with clinical pulmonary toxicity metrics.

Homology-based radiomic features for prediction of the prognosis of lung cancer based on CT-based radiomics

PURPOSE

Radiomics is a new technique that enables noninvasive prognostic prediction by extracting features from medical images. Homology is a concept used in many branches of algebra and topology that can quantify the contact degree. In the present study, we developed homology-based radiomic features to predict the prognosis of non-small-cell lung cancer (NSCLC) patients and then evaluated the accuracy of this prediction method.

METHODS

Four datasets were used: two to provide training and test data and two for the selection of robust radiomic features. All the datasets were downloaded from The Cancer Imaging Archive (TCIA). In two-dimensional cases, the Betti numbers consist of two values: b₀ (zero-dimensional Betti number), which is the number of isolated components, and b₁ (one-dimensional Betti number), which is the number of one-dimensional or "circular" holes. For homology-based evaluation, computed tomography (CT) images must be converted to binarized images in which each pixel has two possible values: 0 or 1. All CT slices of the gross tumor volume were used for calculating the homology histogram. First, by changing the threshold of the CT value (range: -150 to 300 HU) for all its slices, we developed homology-based histograms for b₀ , b₁ , and b₁ /b₀ using binarized images. All histograms were then summed, and the summed histogram was normalized by the number of slices. 144 homology-based radiomic features were defined from the histogram. To compare the standard radiomic features, 107 radiomic features were calculated using the standard radiomics technique. To clarify the prognostic power, the relationship between the values of the homology-based radiomic features and overall survival was evaluated using LASSO Cox regression model and the Kaplan-Meier method. The retained features with nonzero coefficients calculated by the LASSO Cox regression model were used for fitting the regression model. Moreover, these features were then integrated into a radiomics signature. An individualized rad score was calculated from a linear combination of the selected features, which were weighted by their respective coefficients.

RESULTS

When the patients in the training and test datasets were stratified into high-risk and low-risk groups according to the rad scores, the overall survival of the groups was significantly different. The C-index values for the homology-based features (rad score), standard features (rad score), and tumor size were 0.625, 0.603, and 0.607, respectively, for the training datasets and 0.689, 0.668, and 0.667 for the test datasets. This result showed that homology-based radiomic features had slightly higher prediction power than the standard radiomic features.

CONCLUSIONS

Prediction performance using homology-based radiomic features had a comparable or slightly higher prediction power than standard radiomic features. These findings suggest that homology-based radiomic features may have great potential for improving the prognostic prediction accuracy of CT-based radiomics. In this result, it is noteworthy that there are some limitations.

Postradiotherapy persistent lymphopenia as a poor prognostic factor in patients with cervical cancer receiving radiotherapy: a single-center, retrospective study

BACKGROUND

Radiotherapy (RT) is effective in cervical cancer; radiation-induced lymphopenia correlates with poor survival outcome in several cancer types. We investigated the association of total lymphocyte count (TLC) with survival outcomes in patients with cervical cancer.

METHODS

We retrospectively reviewed 168 patients with cervical cancer initially treated with definitive RT. We obtained clinicopathological data and TLCs before RT and at the end and at 6 months after RT. Patient-, treatment-, and tumor-specific factors were evaluated to determine their predictive values for overall survival. The association of overall and progression-free survivals with lymphopenia at each point was evaluated.

RESULTS

Median follow-up duration was 44 (interquartile range: 25-67) months. Median TLCs before RT and at the end and at 6 months after RT were 1625/mm³, 400/mm³, and 800/mm³ (interquartile range: 1270-1930/mm³, 290-550/mm³, and 600-1067/mm³), respectively. For overall survival, in addition to FIGO stage, body mass index, histology, treatment, and presence of para-aortic lymph node metastasis, lymphopenia at 6 months after RT was a poor prognostic factor in multivariate analysis (P = 0.0026; hazard ratio [HR], 3.06; 95% confidence interval [CI]: 1.48-6.33). For progression-free survival, TLCs before and at 6 months after RT were poor prognostic factors in univariate analysis (P = 0.0318 and 0.0081, respectively); however, the latter was the only independent prognostic factor in multivariate analysis (P = 0.0021; HR, 2.67; 95% CI: 1.43-4.99).

CONCLUSION

Post-RT persistent lymphopenia could be a poor prognostic factor for patients with cervical cancer who receive RT.

A low albumin to globulin ratio with a high serum globulin level is a prognostic marker for poor survival in cervical cancer patients treated with radiation based therapy

OBJECTIVE

We investigated whether the pretreatment albumin to globulin ratio, serum albumin level, and serum globulin level can be used to predict survival among cervical cancer patients treated with radiation based therapy and assessed globulin fractions.

METHODS

We retrospectively enrolled 128 patients with cervical cancer treated with radiation based therapy at our institution between 2010 and 2015. The associations of the pretreatment albumin to globulin ratio, and serum albumin and globulin levels with overall survival were assessed. Additionally, the associations of the globulin fractions with the serum globulin levels and overall survival were evaluated.

RESULTS

Median follow-up duration was 30 months (IQR 16-44 months). A low albumin to globulin ratio (< 1.53) was found to be an independent prognostic factor for overall survival (HR= 3.07; 95% CI, 1.03 to 13.3; P=0.044). On evaluating serum globulin and albumin separately, a high serum globulin level was significantly associated with overall survival (cut-off value 2.9 g/dL; HR=3.74; 95% CI 1.08 to 23.6; P=0.036) whereas a low serum albumin level was not associated with overall survival (cut-off value 3.6 g/dL; HR=1.77; 95% CI 0.57 to 4.54; P=0.29). Electrophoresis data of the serum proteins revealed that the γ-globulin fraction was most strongly correlated with the globulin levels (P<0.001). Furthermore, a high γ-globulin level (≥1.28 g/dL) was significantly associated with poor overall survival (log rank test, P=0.034).

CONCLUSIONS

A pretreatment low albumin to globulin ratio, which might be attributable to a high serum globulin level, can be used to predict poor prognosis in cervical cancer patients treated with radiation based therapy.