Improvement of Prediction Performance for Radiation Pneumonitis by Using 3-Dimensional Dosiomic Features

INTRODUCTION

Patients with early non-small-cell lung cancer (NSCLC) have a relatively long survival time after stereotactic body radiation therapy (SBRT). Predicting radiation-induced pneumonia (RP) has important clinical and social implications for improving the quality of life of such patients. This study developed an RP prediction model by using 3-dimensional (3D) dosiomic features. The model can be used to guide radiation therapy to reduce toxicity.

METHODS

Radiomic features were extracted from pre-treatment CT, dose-volume histogram (DVH) parameters and dosiomic features were extracted from the 3D dose distribution of 140 lung cancer patients. Four predictive models: (1) CT; (2) CT + DVH; (3) CT + Rtdose; and (4) Hybrid, CT + DVH + Rtdose, were trained to predict symptomatic RP by extremely randomized trees. Accuracy, sensitivity, specificity, and area under the receiver operator characteristic curve were evaluated.

RESULT

Results showed that the fraction regimen was correlated with symptomatic RP (P < .001). The proposed model achieved promising prediction results. The performance metrics for CT, CT + DVH, CT + Rtdose, and Hybrid were as follows: accuracy: 0.786, 0.821, 0.821, and 0.857; sensitivity: 0.625, 1, 0.875, and 1; specificity: 0.8, 0.565, 0.5, and 0.875; and area under the receiver operator characteristic curve: 0.791, 0.809, 0.907, and 0.920, respectively.

CONCLUSION

Dosiomic features can improve the performance of the predictive model for symptomatic RP compared with that obtained with the CT + DVH model. The model proposed in this study can help radiation oncologists individually predict the incidence rate of RP.

A planning strategy may reduce the risk of heart diseases and radiation pneumonia: Avoiding the specific heart substructures

BACKGROUND

Dose to heart substructures is a better predictor for major adverse cardiac events (MACE) than mean heart dose (MHD). We propose an avoidance planning strategy for important cardiac substructures.

MATERIAL AND METHODS

Two plans, clinical and cardiac substructure-avoidance plan, were generated for twenty patients. Five dose-sensitive substructures, including left ventricle, pulmonary artery, left anterior descending branch, left circumflex branch and the coronary artery were chosen. The avoidance plan aims to meet the target criteria and organ-at-risk (OARs) constraints while minimizing the dose parameters of the above five substructures. The dosimetric assessments included the mean dose and the maximum dose of cardiac substructures and several volume parameters. In addition, we also evaluated the relative risk of coronary artery disease (CAD), chronic heart failure (CHF), and radiation pneumonia (RP).

RESULTS

Pearson correlation coefficient and R2 value of linear regression fitting demonstrated that MHD had poor prediction ability for the mean dose of the cardiac substructures. Compared to clinical plans, an avoidance plan is able to statistically significantly decrease the dose to key substructures. Meanwhile, the dose to OARs and the coverage of the target are comparable in the two plans. In addition, it can be observed that the avoidance plan statistically decreases the relative risks of CAD, CHF, and RP.

CONCLUSIONS

The substructure-avoidance planning strategy that incorporates the cardiac substructures into optimization process, can protect the important heart substructures, such as left ventricle, left anterior descending branch and pulmonary artery, achieving the substantive sparing of dose-sensitive cardiac structures, and have the potential to decrease the relative risks of CAD, CHF, and RP.

A novel lung-avoidance planning strategy based on 4DCT ventilation imaging and CT density characteristics for stage III non-small-cell lung cancer patients

BACKGROUND

Functional planning based merely on 4DCT ventilation imaging has limitations. In this study, we proposed a radiotherapy planning strategy based on 4DCT ventilation imaging and CT density characteristics.

MATERIALS AND METHODS

For 20 stage III non-small-cell lung cancer (NSCLC) patients, clinical plans and lung-avoidance plans were generated. Through deformable image registration (DIR) and quantitative image analysis, a 4DCT ventilation map was calculated. High-, medium-, and low-ventilation regions of the lung were defined based on the ventilation value. In addition, the total lung was also divided into high-, medium-, and low-density areas according to the HU threshold. The lung-avoidance plan aimed to reduce the dose to functional and high-density lungs while meeting standard target and critical structure constraints. Standard and dose-function metrics were compared between the clinical and lung-avoidance plans.

RESULTS

Lung avoidance plans led to significant reductions in high-function and high-density lung doses, without significantly increasing other organ at risk (OAR) doses, but at the expense of a significantly degraded homogeneity index (HI) and conformity index (CI; p < 0.05) of the planning target volume (PTV) and a slight increase in monitor units (MU) as well as in the number of segments (p > 0.05). Compared with the clinical plan, the mean lung dose (MLD) in the high-function and high-density areas was reduced by 0.59 Gy and 0.57 Gy, respectively.

CONCLUSION

A lung-avoidance plan based on 4DCT ventilation imaging and CT density characteristics is feasible and implementable, with potential clinical benefits. Clinical trials will be crucial to show the clinical relevance of this lung-avoidance planning strategy.

A novel CRT-IMRT-combined (Co-CRIM) planning technique for peripheral lung stereotactic body radiotherapy in pinnacle treatment planning system

Objectives

This study attempts to explore a novel peripheral lung stereotactic body radiotherapy (SBRT) planning technique that can balance the pros and cons of three‐dimensional conformal radiotherapy (CRT) and intensity‐modulated radiation therapy (IMRT) / volumetric modulated arc therapy (VMAT).

Methods

Treatment plans were retrospectively designed based on CRT, IMRT, VMAT, and the proposed CRT‐IMRT‐combined (Co‐CRIM) techniques using Pinnacle treatment planning system (TPS) for 20 peripheral lung cancer patients. Co‐CRIM used an inverse optimization algorithm available in Pinnacle TPS. To develop a Co‐CRIM plan, the number of segments in each field was limited to one, the minimum segment area was set to the internal target volume (ITV), and the minimum monitor units (MU) of the segment was the quotient of fractional dose divided by twice the number of total fields. The performance of Co‐CRIM was then compared with other techniques.

Results

For conformity index (CI), Co‐CRIM performed comparably to IMRT/VMAT but better than CRT. For gradient index (GI), Co‐CRIM was similar to IMRT/VMAT or CRT. For heterogeneity index (HI), Co‐CRIM was comparable to IMRT/VMAT, higher than CRT. The dosimetric results of spinal cord and lung with Co‐CRIM were better than CRT, comparable to IMRT, but inferior to VMAT. The MU resulted from Co‐CRIM was lower than IMRT/VMAT but higher than CRT. For plan verification γ passing rate, Co‐CRIM was higher than IMRT/VMAT, comparable to CRT. For planning time, Co‐CRIM was shorter than CRT or VMAT but similar to IMRT.

Conclusions

The proposed Co‐CRIM technique on Pinnacle TPS is an effective planning technique for peripheral lung SBRT.

Evaluation of IGRT-Induced Imaging Doses and Secondary Cancer Risk for SBRT Early Lung Cancer Patients In Silico Study

Objectives:

This study performed dosimetry studies and secondary cancer risk assessments on using electronic portal imaging device (EPID) and cone beam computed tomography (CBCT) as image guided tools for the early lung cancer patients treated with SBRT.

Methods:

The imaging doses from MV-EPID and kV-CBCT of the Edge accelerator were retrospectively added to sixty-one SBRT treatment plans of early lung cancer patients. The MV-EPID imaging dose (6MV Photon beam) was calculated in Pinnacle TPS, and the kV-CBCT imaging dose was simulated and calculated by modeling of the kV energy beam in TPS using Pinnacle automatic modeling program. Three types of plans, namely Plan_EPID, Plan_CBCT and Plan_origin, were generated with incorporating doses of EPID, CBCT and no imaging, respectively, for analysis. The effects of imaging doses on dose-volume-histogram (DVH) and plan quality were analyzed, and the excess absolute risk (EAR) of secondary cancer for ipsilateral lung was evaluated.

Results:

The regions that received less than 50 cGy were significantly impacted by the imaging doses, while the isodose lines greater than 1000 cGy were barely changed. The DVH values of ipsilateral lung increased the most in Plan_EPID, followed by Plan_CBCT. Compared to Plan_origin on the average, the estimated EAR of ipsilateral lung in Plan_EPID increased by 3.43%, while the corresponding EAR increase in Plan_CBCT was much smaller (about 0.4%). Considering only the contribution of the imaging dose, the EAR values for the ipsilateral lung due to the MV-EPID dose in 5 years,10 years and 15 years were 1.49 cases, 2.09 cases and 2.88 cases per 10⁴PY respectively, and those due to the kV-CBCT dose were about 9 times lower, correspondingly.

Conclusions:

The imaging doses produced by MV-EPID and kV-CBCT had little effects on the target dose coverage. The secondary cancer risk caused by MV-EPID dose is more than 8.5 times that of kV-CBCT.

Effect of MU-weighted multi-leaf collimator position error on dose distribution of SBRT radiotherapy in peripheral non-small cell lung cancer

PURPOSE

Position accuracy of the multi-leaf collimator (MLC) is essential in stereotactic body radiotherapy (SBRT). This study is aimed to investigate the dosimetric impacts of the MU-weighted MLC positioning uncertainties of SBRT for patients with early stage peripheral non-small cell lung cancer (NSCLC).

METHODS

Three types of MLC position error were simulated: Type 1, random error; Type 2, system shift, in which both MLC banks shifted to the left or right direction; and Type 3, in which both MLC banks moved with same magnitudes in the opposite directions. Two baseline plans were generated: an automatic plan (AP) and a manually optimized plan (MP). Multi-leaf collimator position errors were introduced to generate simulated plans with the preset MLC leaf position errors, which were then reimported into the Pinnacle system to generate simulated plans, respectively. The dosimetric parameters (CI, nCI, GI, etc.) and gEUD values of PTV and OARs were calculated. Linear regression between MU-weighted/unweighted MLC position error and gEUD was performed to obtain dose sensitivity.

RESULTS

The dose sensitivities of the PTVs were -4.93, -38.94, -41.70, -55.55, and 30.33 Gy/mm for random, left shift, right shift, system close, and system open MLC errors, respectively. There were significant differences between the MU-weighted and the unweighted dose sensitivity, which was -38.94 Gy/mm vs -3.42 Gy/mm (left shift), -41.70 Gy/mm vs -3.56 Gy/mm (right shift), -55.55 Gy/mm vs -4.84 Gy/mm (system close), and 30.33 vs 2.64 Gy/mm (system open). For the system open/close MLC errors, as the PTV volume became larger, the dose sensitivity decreased. APs provided smaller dose sensitivity for the system shift and system close MLC errors compared to the conventional MPs.

CONCLUSIONS

There was significant difference in dose sensitivity between MU-weighted and unweighted MLC position error of SBRT radiotherapy in peripheral NSCLC. MU is suggested to be included in the dosimetric evaluation of the MLC misalignments, since it is much closer to clinical radiotherapy.

Propionate alleviates high-fat diet-induced lipid dysmetabolism by modulating gut microbiota in mice

AIMS

The aims were to examine whether oral sodium propionate supplementation regulate lipid metabolism through modulating gut microbiota.

METHODS AND RESULTS

ICR male mice (26·98 ± 0·30 g) were randomly assigned to three groups (n = 10) and fed control diet (Con), high-fat diet (HFD) and HFD plus propionate (Pro) respectively. In this study, we found that HFD increased the weight of final body, inguinal white adipose tissues (iWAT), epididymal white adipose tissue (eWAT) and perirenal white adipose tissue (pWAT), as well as the adipocyte mean area of iWAT and eWAT in mice (P < 0·05), whereas sodium propionate treatment reduced the weight of iWAT and pWAT as well as adipocyte mean area of iWAT in mice fed a HFD (P < 0·05). Moreover, in the iWAT, the mRNA expression of lipogenesis genes, including peroxisome proliferator activated receptor γ, acetyl-CoA carboxylase and carnitine palmitoyl transferase-1β, was upregulated by HFD challenge (P < 0·05), and the elevation of these genes was nearly reversed to the level of control diet-fed mice by sodium propionate treatment. Meanwhile, sodium propionate treatment increased the hormone-sensitive lipase mRNA expression in the iWAT of HFD-fed mice (P < 0·05). High-throughput pyrosequencing of the 16S rRNA demonstrated that sodium propionate treatment significantly recovered the gut microbiota dysbiosis in HFD-fed mice, including the richness and diversity of microbiota and the ratio of Firmicutes to Bacteroidetes. Furthermore, the HFD-induced reductions in colonic levels of butyrate and valerate were reversed by sodium propionate treatment, which also normalized the serum LPS level seen in HFD-fed mice to the levels of the control diet-fed mice.

CONCLUSIONS

Collectively, these results indicated that sodium propionate treatment could improve lipid metabolism in HFD-fed mice, and the potential mechanisms might be via regulating gut microbiota.

SIGNIFICANCE AND IMPACT OF THE STUDY

We demonstrated for the first time that oral sodium propionate significantly improved HFD-induced dysbiosis of gut microbiota, indicating that the mitigative effect of propionate for HFD-induced lipid dysmetabolism might be mediated by gut microbiota in mice.

Low-protein diet improves meat quality of growing and finishing pigs through changing lipid metabolism, fiber characteristics, and free amino acid profile of the muscle

The objective of the study was to investigate the effect of feeding reduced CP, AA-supplemented diets on meat quality in growing and finishing pigs as well as the related mechanism. In experiment 1, 18 growing pigs (36.5 kg BW) were assigned randomly and fed 1 of 3 corn-soybean meal diets containing either 18% CP (normal protein, NP), 15% CP (low protein, LP), or 12% CP (very low protein, VLP). In experiment 2, 18 finishing pigs (62.3 kg BW) were allotted randomly into 1 of the following diets: 16% CP (NP), 13% CP (LP), or 10% CP (VLP). In both experiments, the LP and VLP diets were supplemented with crystalline AA to achieve equal content of standardized ileal digestible lysine, methionine, threonine, and tryptophan. At the end of each experiment, all pigs were slaughtered to collect longissimus dorsi muscle (LM) samples. Samples were used for determining meat quality, intramuscular fat (IMF) content, fatty acid composition, free AA profile, and expression of genes for myosin heavy chain isoforms. Results showed that growing and finishing pigs fed the LP diets increased (P < 0.05) redness value of LM, while finishing pigs fed the LP and VLP diets decreased (P < 0.05) the shear force values. Compared with the NP diet, growing and finishing pigs fed lower CP diets had higher (P < 0.05) contents of IMF and MUFA, and lower (P < 0.05) contents of PUFA. Besides, higher (P < 0.05) expression levels of type I and/or IIa muscle fibers were observed in LP diet-fed growing and finishing pigs, and greater concentrations of taurine and tasty AA in VLP diet-fed growing and finishing pigs. Taken together, our results indicate that low-protein diets could positively affect meat quality of growing and finishing pigs, and likely through regulation of IMF content and fatty acid composition, fiber characteristics, and free AA profile in the muscle.

[The role and significance of digital reconstruction technique in liver segments based on portal vein structure]

Objective: To study the segment of liver according to the large amount of three-dimensional(3D) reconstructive images of normal human livers and the vascular system, and to recognize the basic functional liver unit based on the anatomic features of the intrahepatic portal veins. Methods: The enhanced CT primitive DICOM files of 1 260 normal human livers from different age groups who treated from October 2013 to February 2017 provided by 16 hospitals were analyzed using the computer-aided surgery system.The 3D liver and liver vascular system were reconstructed, and the digital liver 3D model was established.The vascular morphology, anatomical features, and anatomical distributions of intrahepatic portal veins were statistically analyzed. Results: The digital liver model obtained from the 3D reconstruction of CAS displayed clear intrahepatic portal vein vessels of level four.Perform a digital liver segments study based on the analysis of level four vascular distribution areas.As the less anatomical variation of left hepatic portal vein, the liver was classified into four types of liver segmentation mainly based on right hepatic portal vein.Type A was similar to Couinaud or Cho's segmentation, containing 8 segments(537 cases, 42.62%). Type B contained 9 segments as there are three ramifications of right-anterior portal vein(464 cases, 36.82%). The main difference for Type C was the variation of right-posterior portal vein which was sector shape(102 cases, 8.10%). Type D contained the cases with special portal vein variations, which needs three-dimensional simulation to design individualized liver resection plan(157 cases, 12.46%). These results showed that there was no significant difference in liver segmental typing between genders(χ(2)=2.179, P=0.536) and did not reveal any significant difference in liver segmental typing among the different age groups(χ(2)=0.357, P=0.949). Conclusions: The 3D digital liver model can demonstrate the true 3D anatomical structures, and its spatial vascular variations.The observation of anatomic features, distribution areas of intrahepatic portal veins and individualized liver segmentation achieved via digital medical 3D visualization technology is of great value for understand the complexity of liver anatomy and to guide the precise hepatectomy.

[Application of low dose CT angiography with 70 kV in patients with peripheral arterial diseases]

Objective: To assess the image quality, radiation dose and diagnostic efficiency of peripheral arterial CT angiography (CTA) performed at tube voltage of 70 and 120 kV. Methods: Between January 2014 and December 2015, a total of 200 consecutive patients with known or suspected lower extremity arteriosclerosis obliterans (LEASO) underwent CTA.Patients were randomly divided into 2 groups by different scanning protocols.Group A (n=100): 70 kV and 0.8 ml/kg contrast agent, group B (n=100): 120 kV and 100 ml contrast agent.The vessel enhancement, image noise, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of 3 segments were quantified for each protocol.30 patients in group A (420 vessels) and 28 patients in group B (384 vessels) confirmed by DSA.Based on vessel assessments, compared with DSA findings, the diagnostic efficacy of 70 kV and 120 kV protocols for the detection of stenoses over 50% was evaluated.The dose of radiation and contrast agent were recorded.Subjective image quality was evaluated. Results: The subjective image quality of segment crural of group A was significantly higher than that of group B (2.20±0.36 vs 1.72±0.34, P<0.01). The enhancement of 3 segments in group A (500 HU) were significantly higher than these in group B (310 HU) (P<0.05). For the detection of stenoses over 50%, the sensitivity, positive and negative predictive values and accuracy of segment crural in group A (98.6%, 95.8%, 98.1%, 96.7%) were significantly higher than that in group B (90.9%, 88.5%, 91.0%, 89.7%) (P<0.05). Mean DLP for 70-kV protocol was significantly lower than that for 120-kV protocol ( (396±34) vs (1 041±159) mGy·cm, P=0.001). Mean dose of contrast agent and the total amount of iodine for 70-kV protocol were significantly lower than that for 120-kV protocol (53.5 vs 100 ml; 18.7 vs 35 g; P<0.01). Conclusion: CT angiography of peripheral arteries with a low tube voltage of 70 kV and low dose of iodine provides reliable information and serves as a rapidly performed and easily available imaging modality in the diagnosis of LEASO.

Reduced dietary protein level influences the free amino acid and gene expression profiles of selected amino acid transceptors in skeletal muscle of growing pigs

This study was conducted to evaluate the effect of reduced dietary protein level on growth performance, muscle mass weight, free amino acids (FAA) and gene expression profile of selected amino acid transceptors in different fibre type of skeletal muscle tissues (longissimus dorsi, psoas major, biceps femoris) of growing pigs. A total of 18 cross-bred growing pigs (Large White × Landrace × Duroc) with initial body weight (9.57 ± 0.67 kg) were assigned into three dietary treatments: 20% crude protein (CP) diet (normal recommended, NP), 17% CP diet (low protein, LP) and 14% CP diet (very low protein, VLP). The results indicated improved feed-to-gain ratio was obtained for pigs fed LP and NP diets (p < 0.01), while the pigs fed VLP diet showed the worst growth performance (p < 0.01). There was no significant difference in the weights of longissimus dorsi and psoas major muscle between LP and NP groups (p > 0.05). Majority of the determined FAA concentration of LP group were greater than or equal to those of NP group in both longissimus dorsi and psoas major muscle (p < 0.01). Further, the mRNA expression levels of sodium-coupled neutral amino acid transceptor 2, L-type amino acid transceptor 1 and proton-assisted amino acid transceptors 2 were higher in skeletal muscle tissue in LP group compared to those of the pigs fed NP or VLP diet. These results suggested that reduced dietary protein level (3 points of percentage less than recommended level) would upregulate the mRNA expression of amino acid transceptors to enhance the absorption of FAA in skeletal muscle of growing pigs. There seems to be a relationship between response of AA transceptors to the dietary protein level in skeletal muscle tissue of different fibre type. To illustrate the underlying mechanisms will be beneficial to animal nutrition.

Source apportionment of polycyclic aromatic hydrocarbons in surface soil in Tianjin, China

Principal component analysis and multiple linear regression were applied to apportion sources of polycyclic aromatic hydrocarbons (PAHs) in surface soils of Tianjin, China based on the measured PAH concentrations of 188 surface soil samples. Four principal components were identified representing coal combustion, petroleum, coke oven plus biomass burning, and chemical industry discharge, respectively. The contributions of major sources were quantified as 41% from coal, 20% from petroleum, and 39% from coking and biomass, which are compatible with PAH emissions estimated based on fuel consumption and emission factors. When the study area was divided into three zones with distinctive differences in soil PAH concentration and profile, different source features were unveiled. For the industrialized Tanggu-Hangu zone, the major contributors were cooking (43%), coal (37%) and vehicle exhaust (20%). In rural area, however, in addition to the three main sources, biomass burning was also important (13%). In urban-suburban zone, incineration accounted for one fourth of the total.