Dosimetric assessment of tumor control probability in intensity and volumetric modulated radiotherapy plans

OBJECTIVE:

Radiobiological models have been used to calculate the outcomes of treatment plans based on dose-volume relationship. This study examines several radiobiological models for the calculation of tumor control probability (TCP) of intensity modulated radiotherapy plans for the treatment of lung, prostate, and head and neck (H&N) cancers.

METHODS:

Dose volume histogram (DVH) data from the intensity modulated radiotherapy plans of 36 lung, 26 prostate, and 87  H&N cases were evaluated. The Poisson, Niemierko, and Marsden models were used to calculate the TCP of each disease group treatment plan. The calculated results were analyzed for correlation and discrepancy among the three models, as well as different treatment sites under study.

RESULTS:

The median value of calculated TCP in lung plans was 61.9% (34.1-76.5%), 59.5% (33.5-73.9%) and 32.5% (0.0-93.9%) with the Poisson, Niemierko, and Marsden models, respectively. The median value of calculated TCP in prostate plans was 85.1% (56.4-90.9%), 81.2% (56.1-88.7%) and 62.5% (28.2-75.9%) with the Poisson, Niemierko, and Marsden models, respectively. The median value of calculated TCP in H&N plans was 94.0% (44.0-97.8%) and 94.3% (0.0-97.8%) with the Poisson and Niemierko models, respectively. There were significant differences between the calculated TCPs with the Marsden model in comparison with either the Poisson or Niemierko model (p < 0.001) for both lung and prostate plans. The TCPs calculated by the Poisson and Niemierko models were significantly correlated for all three tumor sites.

CONCLUSION:

There are variations with different radiobiological models. Understanding of the correlation and limitation of a TCP model with dosimetric parameters can help develop the meaningful objective functions for plan optimization, which would lead to the implementation of outcome-based planning. More clinical data are needed to refine and consolidate the model for accuracy and robustness.

ADVANCES IN KNOWLEDGE:

This study has tested three radiobiological models with varied disease sites. It is significant to compare different models with the same data set for better understanding of their clinical applicability.

[The expression of Semaphorin 5A in patients with rheumatoid arthritis and its effect on osteoclastogenesis]

Objective: To investigate the clinical significance of soluble Semaphorin 5A(Sema 5A) in patients of rheumatoid arthritis(RA) and the effect of Sema 5A on osteoclastogenesis in RAW264.7 cells. Methods: (1)Soluble Sema 5A was detected in the serum of 62 RA patients, 30 osteoarthritis(OA) patients and 48 healthy controls(HC) by enzyme-linked immunosorbent assay(ELISA).The relationships between serum Sema 5A and disease activity, radiographic severity and laboratory parameters were investigated in RA patients.(2)RAW264.7 cells were treated with different concentrations of Sema 5A(0,0.5,1,2.5,5 μg/ml).After 7 days, tartrate-resistant acid phosphate(TRAP) staining was performed. The mRNA levels of TRAP, cathepsin-K and matrix metallopeptidase 9(MMP-9) were tested using real-time polymerase chain reaction (RT-PCR).(3)Bone resorption area of dentine slides cultured with RAW264.7 cells was calculated after Sema 5A(5μg/ml) treatment. Results: (1)The serum Sema 5A in RA patients[(5.24±0.59)μg/L] was significantly higher than those in healthy controls[(2.93±0.34)μg/L,P<0.01] and OA patients[(2.68±0.47)μg/L,P<0.05]. The Sema 5A level in RA patients was positively correlated with disease activity score with 28 joint using C-reactive protein(DAS28-CRP), clinical disease activity index (CDAI),C-reactive protein(CRP) and sharp scores(P<0.05 or P<0.01).In addition,the serum Sema 5A in RA patients with positive anti-cyclic citrullinated peptide(CCP) antibody was significantly greater than that of anti-CCP antibody-negative patients(P<0.05).(2)After RAW264.7 cells were treated with Sema 5A, the number of TRAP positive osteoclasts increased according to the increase of Sema 5A concentration with maximal effect at 5 μg/ml. Meanwhile, Sema 5A promoted mRNA expression of TRAP,Cathepsin-K and MMP-9.(3)Bone resorption area increased when RAW264.7 cells were treated with Sema 5A(5 μg/ml). Conclusions: Serum Sema 5A is elevated in RA patients and correlated with disease activity and radiographic severity. Sema 5A promotes osteoclastogenesis of RAW264.7 cells.

Improved Dose Conformity for Adjacent Targets: A Novel Planning Technique for Gamma Knife Stereotactic Radiosurgery

Purpose

In the current Gamma Knife (GK) planning system (GammaPlan, version 10.2, Elekta AB, Stockholm, Sweden), multiple adjacent brain metastasis (BMs) had to be planned sequentially if BMs were drawn separately, leading to less conformal target dose in the composite plan due to inter-target dose contribution and fine-tuning of the shots being quite tedious. We proposed a method to improve target dose conformality and planning efficiency for such cases.

Methods and Materials

Fifteen patients with multiple BMs treated on the Leksell GK Perfexion system were retrospectively replanned in the Institutional Review Board (IRB) approved study. The recruitment criterion was all the BMs should be entirely encompassed within the maximum dose grid allowed in the GammaPlan. The BMs were first planned sequentially as routine clinic cases. The contours of the BMs were then exported to the VelocityAI (Varian, CA, USA) to generate a composite contour after a union operation, and all the BMs were planned again simultaneously using this composite contour in the GammaPlan. The inverse planning (IP) was employed in both methods with the same treatment time allowed for a fair plan comparison. Dose evaluation was performed in the VelocityAI with all planning magnetic resonance (MR) images, structure set and dose were exported to the VelocityAI. The dosimetery parameters, including conformality index (CI), V20Gy, V16Gy, V12Gy, and V5Gy, were compared between the two methods.

Results

The planning results from both methods were reviewed qualitatively and quantitatively. The proposed method exhibited superior CI, except for an outlier case with very tiny BMs. The mean and standard deviation (std.) of the Paddick CI for all patients were 0.76±0.11 for the proposed method, comparing to 0.69±0.13 for the sequential method. The V20Gy, V16Gy, V12Gy, and V5Gy for the proposed method were 10.9±0.9%, 9.5±10.2%, 6.2±16.4% and 3.3±21.8%, all lower than those from the sequential method.

Conclusions

The proposed method showed improved target dose conformality for all cases except for very tiny BMs. Planning efficiency is considerably better with the combined target technique. The improved dose conformality will be beneficial to patients in long term with lowered risk of radiation necrosis after GK stereotactic radiosurgery (SRS).

[Application of scalp-recorded high-frequency oscillations in epileptic encephalopathy with continuous spike-and-wave during sleep]

OBJECTIVE

To investigate the clinical significance of high-frequency oscillations (HFOs) on scalp electroencephalography (EEG) in patients with epileptic encephalopathy with continuous spike-and-wave during sleep (CSWS).

METHODS

Twenty-one CSWS patients treated for epilepsy from January 2006 to December 2016 in Pediatric Department of Peking University First Hospital were enrolled into the study. Selected clinical variables including gender, age parameters, seizure frequencies and antiepileptic drugs were compared between (a). HFO-positive group and HFO-negative group before methylprednisolone treatment and (b). excellent seizure outcome group and not-excellent seizure outcome group after methylprednisolone treatment. Interictal HFOs and spikes in pre- and post-methylprednisolone scalp EEG were measured and analyzed.

RESULTS

Before methylprednisolone treatment, there were 12 of 21 (57%) CSWS patients had HFOs, with a mean value 43.17 per 60 s per patient. The 12 patients with HFOs tended to have more frequent epileptic negative myoclonus/atonic/myoclonus/atypical absences than those without HFOs in a month before methylprednisolone treatment. A total of 518 HFOs and 22 592 spikes were found in the pre-methylprednisolone EEG data of 21 patients, and 441 HFOs (86%) were associated with spikes. The highest amplitudes of HFOs were significantly positively correlated with that of spikes (r=0.279, P<0.001). Rates reduced by methylprednisolone treatment were statistically significant for both HFOs (P=0.002) and spikes (P=0.006). The percentage of reduction was 91% (473/518) and 39% (8 905/22 592) for spikes and HFOs, respectively. The percentage of spike and HFOs changes was respectively 100% decrease and 47% decrease in the excellent seizure outcome group, and they were 79% decrease and 18% increase in the not-excellent seizure outcome group.

CONCLUSION

Prevalence of HFOs might reflect some aspect of epileptic activity. HFOs were more sensitive to methylprednisolone treatment than spikes and had a good correlation with the prognosis of seizures, and HFOs could be applied to assess epilepsy severity and antiepileptic therapy.

Abstract P5-07-05: LOC283299 suppress the lymphnode metastatic cascade in breast cancer patients

Background

Long non-coding RNAs (lncRNAs) have been proved to play an essential role in cancer metastasis. The accuracy of intraoperative assessment of lymph nodes metastasis need to be improved. In this study, we aimed to define the lncRNA biomarker ectopic expressed in breast cancer patients' metastatic lymph nodes, and to explore the potential molecular mechanisms.

Experimental Design

RNA-seq analyses in 3 paired breast cancer patients' primary tumor and metastatic lymph node was used as training set to determine differentially expressed lncRNAs that may be associated with lymph node metastasis. The other 40 patients were analyzed as validation set to test the accuracy of lncRNAs identification by quantitative real-time PCR. The correlation between LOC283299 expression level and prognosis in other 282 breast cancer patients was confirmed. In parallel, in vitro and in vivo analyses were carried out to determine the potential mechanisms of LncRNA-dependent lymph node metastases and prognosis.

Results

RNA-seq analyses in the training set revealed significant correlation between high expression level of LOC283299 and lower lymph node metastasis potential in breast cancer patients. We further validated that the expression level of LOC283299 was significantly higher in tumor primary tissue than that in paired metastatic lymph node (P=0.0245), and higher LOC283299 expression level was markedly associated with good metastasis-free survival in breast cancer patients (P=0.04). In breast cancer cell lines, CRISPR-on overexpression of LOC283299 inhibited proliferation, migration, invasion, and metastases both in vivo and in vitro. shRNA knockdown LOC283299 promotes the ability of tumor proliferation and metastasis. The molecular mechanisms by which LOC283299 as metastasis-suppressing lncRNAs regulates recurrence and metastasis may involve regulation of epithelial to mesenchymal transition (EMT), cellular invasion and microenvironment in breast cancer cells.

Conclusion

Our study revealed a strong correlation between LOC283299 expression and lymph node metastases in breast cancers. High level of LOC283299 was associated with better metastasis-free survival. The changed metastasis phenotype may be mediated by the interaction of LOC283299 and breast cancer cells. Therefore, LOC283299 may represent a potential predictive biomarker for early lymph node metastasis in breast cancer.

Citation Format: Guo R, Xue J, Su Y, Xiu B, Ji W, Chi Y, Wu J. LOC283299 suppress the lymphnode metastatic cascade in breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-07-05.

Single- and Multi-Fraction Stereotactic Radiosurgery Dose Tolerances of the Optic Pathways

PURPOSE

Dosimetric and clinical predictors of radiation-induced optic nerve/chiasm neuropathy (RION) after single-fraction stereotactic radiosurgery (SRS) or hypofractionated (2-5 fractions) radiosurgery (fSRS) were analyzed from pooled data that were extracted from published reports (PubMed indexed from 1990 to June 2015). This study was undertaken as part of the American Association of Physicists in Medicine Working Group on Stereotactic Body Radiotherapy, investigating normal tissue complication probability (NTCP) after hypofractionated radiation.

METHODS AND MATERIALS

Eligible studies described dose delivered to optic nerve/chiasm and provided crude or actuarial toxicity risks, with visual endpoints (ie, loss of visual acuity, alterations in visual fields, and/or blindness/complete vision loss). Studies of patients with optic nerve sheath tumors, optic nerve gliomas, or ocular/uveal melanoma were excluded to obviate direct tumor effects on visual outcomes, as were studies not specifying causes of vision loss (ie, tumor progression vs RION).

RESULTS

Thirty-four studies (1578 patients) were analyzed. Histologies included pituitary adenoma, cavernous sinus meningioma, craniopharyngioma, and malignant skull base tumors. Prior resection (76% of patients) did not correlate with RION risk (P = .66). Prior irradiation (6% of patients) was associated with a crude 10-fold increased RION risk versus no prior radiation therapy. In patients with no prior radiation therapy receiving SRS/fSRS in 1-5 fractions, optic apparatus maximum point doses resulting in <1% RION risks include 12 Gy in 1 fraction (which is greater than our recommendation of 10 Gy in 1 fraction), 20 Gy in 3 fractions, and 25 Gy in 5 fractions. Omitting multi-fraction data (and thereby eliminating uncertainties associated with dose conversions), a single-fraction dose of 10 Gy was associated with a 1% RION risk. Insufficient details precluded modeling of NTCP risks after prior radiation therapy.

CONCLUSIONS

Optic apparatus NTCP and tolerance doses after single- and multi-fraction stereotactic radiosurgery are presented. Additional standardized dosimetric and toxicity reporting is needed to facilitate future pooled analyses and better define RION NTCP after SRS/fSRS.

Head and Neck Tumor Control Probability: Radiation Dose-Volume Effects in Stereotactic Body Radiation Therapy for Locally Recurrent Previously-Irradiated Head and Neck Cancer: Report of the AAPM Working Group

PURPOSE

Stereotactic body radiation therapy (SBRT) has emerged as a viable reirradiation strategy for locally recurrent previously-irradiated head and neck cancer. Doses in the literature have varied, which challenges clinical application of SBRT as well as clinical trial design.

MATERIAL & METHODS

A working group was formed through the American Association of Physicists in Medicine to study tumor control probabilities for SBRT in head and neck cancer. We herein present a systematic review of the available literature addressing the dose/volume data for tumor control probability with SBRT in patients with locally recurrent previously-irradiated head and neck cancer. Dose-response models are generated that present tumor control probability as a function of dose.

RESULTS

Data from more than 300 cases in 8 publications suggest that there is a dose-response relationship, with superior local control and possibly improved overall survival for doses of 35 to 45 Gy (in 5 fractions) compared with <30 Gy.

CONCLUSION

Stereotactic body radiation therapy doses equivalent to 5-fraction doses of 40 to 50 Gy are suggested for retreatment.

High expression of HO-1 predicts poor prognosis of ovarian cancer patients and promotes proliferation and aggressiveness of ovarian cancer cells

PURPOSE

HO-1 has been proved to be associated with tumor aggressivity and poor prognosis in various cancers. Our study provides the first study to demonstrate the relationship of HO-1 expression and clinical characteristics in ovarian cancer patients.

METHODS

Immunohistochemistry and western blotting were used to examine the expression of HO-1 in tissue species and fresh tissues. CCK-8 was used to investigate cell viability. Transwell chamber was performed to estimate migration and invasion capacities in A2780 and Skov-3 cells.

RESULTS

Immunohistochemistry and western blotting showed that the expression of HO-1 was higher in ovarian cancer tissues than normal ovarian tissues. High expression of HO-1 was significantly associated with serous ovarian cancer, high FIGO stage, lymph node metastasis, and non-optimal debulking. Patients with high expression of HO-1 exhibited an unfavorable prognosis. In vitro inducing the expression of HO-1 promoted the proliferation and metastasis of A2780 and Skov-3 cells, with the increased expressions of mesenchymal marker (Vimentin), epithelial-mesenchymal transition-associated transcript factor (Zeb-1), anti-apoptotic protein (Bcl-2), and the decreased expressions of epithelial marker (Keratin) and pro-apoptotic protein (Bax). Meanwhile, after incubating A2780 and Skov-3 together with HO-1 inhibitor, above results could be reversed.

CONCLUSION

HO-1 might be a potential marker for prediction of ovarian cancer prognosis and a target for ovarian cancer treatment.

Serum YKL-40, a prognostic marker in patients with large-artery atherosclerotic stroke

BACKGROUND AND PURPOSE

Inflammation comprises important aspects of large-artery atherosclerosis (LAA) stroke pathophysiology. YKL-40 is a new and emerging biomarker that is associated with both acute and chronic inflammations. Elevated serum concentrations of YKL-40 have been reported in patients with atherosclerosis and other cardiovascular diseases. This study investigates whether serum YKL-40 concentrations on admission can predict 3-month clinical outcomes after LAA stroke.

METHODS

We recruited control patients (n=85) and those with LAA stroke (n=141) according to the TOAST classification system. The modified Rankin scale at 3 months after stroke was used to evaluate the prognosis. The prognostic accuracy was assessed by the receiver operating characteristic curve.

RESULTS

Serum YKL-40 level was significantly higher for LAA patients than for controls (P<.001). Patients with poor outcomes (n=36) had significantly increased serum YKL-40 concentrations on admission (P=.01). High YKL-40 levels predicted poor functional outcome (OR=6.47, P=.02). Moreover, the combination of YKL-40 level and the NIHSS score could improve the prognostic accuracy of the NIHSS in predicting functional outcome (combined areas under the curve, 0.87; 95% CI, 0.80-0.94; P<.001).

CONCLUSIONS

The level of serum YKL-40 is a significant and independent biomarker to predict the clinical outcome of LAA stroke.

[Clinical and genetic characteristics and detection of urinary pipecolic acid in pyridoxine dependent epilepsy]

OBJECTIVE

To analyze the clinical and genetic characteristics of patients with pyridoxine dependent epilepsy (PDE), and build a method to detect and analyze the concentration of urinary pipecolic acid in PDE patients receiving pyridoxine treatment.

METHOD

Twelve patients (8 were male, 4 were female) were diagnosed as PDE in Peking University First Hospital between April 2012 and September 2015. The clinical manifestations, diagnosis and treatment process, video-electroencephalogram, magnetic resonance imaging were retrospectively analyzed. ALDH7A1 gene was detected using Sanger sequencing or targeted next-generation sequencing. The concentration of urinary pipecolic acid in PDE patients was detected with gas chromatography-mass spectrometry (GC-MS), as well as in some non-PDE children served as normal control. All controls, 58 cases totally, were neonates born in our hospital or children came to our hospital for reasons such as syncope (without disturbing pipecolic acid metabolism) from November 2015 to January 2016. Of them, 25 were ≤6 months old(14 were male, 11 were female), 33 were >6 months old(14 were male, 19 were female). The Student's t-test or Mann-Whitney U test was used for comparing the pipecolic acid between the two groups. Correlation analysis was conducted using Pearson or Spearman test.

RESULT

Of the 12 patients, seven of them were abnormal at birth. The age of epilepsy onset was from 5 h to 5 months, within 10 d in 8 patients. After a diagnostic delay time of 15 d to 20 months, seizures in all patients were controlled by pyridoxine monotherapy, at a dose of higher than 10.0 mg/(kg·d) in 10 patients, and 8.5 and 2.5 mg/(kg·d) in the other 2 patients respectively. The range of maintenance dose was 2.5-20.0 mg/(kg·d) during the follow up. Interictal electroencephalogram showed nonspecific abnormality in 10, normal in 2. Brain magnetic resonance imaging showed nonspecific abnormality in 7, normal in 5. ALDH7A1 mutations were found in all patients, including 15 different mutation sites, four of which were never reported before. Splicing mutation IVS11+ 1G>A was carried in 6 patients, with a frequency of 25% (6/24). At the last follow-up, eleven patients were in various degree of psychomotor development delay, including the 4 patients with severe delay in whom birth abnormalities presented, and no significant delay was found in one patient. The concentration of urinary pipecolic acid in control: age ≤6 months, median 8.47 (0.46-35.33) mmol/mol creatinine; age >6 months, median 0.66 (0.12-3.52) mmol/mol creatinine. The concentration of urinary pipecolic acid was different between two groups of control (Z=-5.464, P<0.01). Twelve patients were all older than 6 months when they were tested, and the concentration was only mildly elevated in one patient, the range of 12 patients was 0.14-4.08 mmol/mol creatinine. The concentration was not significantly different between the control with age >6 months and our PDE patients (Z=-0.655, P>0.05). There were no significant correlations between the concentration of urinary pipecolic acid and the initial dose or maintenance dose at last follow-up of pyridoxine (r=0.418 and 0.166, P=0.176 and 0.607).

CONCLUSION

Seizures start in early infancy in most PDE patients. The splicing mutation IVS11+ 1G>A is supposed to be a probable"hotspot"mutation with a high frequency in Chinese PDE patients. Most patients have different levels of psychomotor development delay after seizures are controlled, and the patients with birth abnormalities may have worse outcomes. No relationships between the diagnostic delay time and the development outcome are found. The concentration of urinary pipecolic acid can return to normal during treatment with pyridoxine.

Chemosensitive Phox2b-expressing neurons are crucial for hypercapnic ventilatory response in the nucleus tractus solitarius

KEY POINTS

Central hypercapnic hypoventilation is highly prevalent in children suffering from congenital central hypoventilation syndrome (CCHS). Mutations of the gene for paired-like homeobox 2b (Phox2b) are aetiologically associated with CCHS and Phox2b is present in central components of respiratory chemoreflex, such as the nucleus tractus solitarius (NTS). Injection of the neurotoxin substance P-saporin into NTS destroys Phox2b-expressing neurons. Impaired hypercapnic ventilatory response caused by this neurotoxin is attributable to a loss of CO₂ -sensitive Phox2b-expressing NTS neurons. A subgroup of Phox2b-expressing neurons exhibits intrinsic chemosensitivity. A background K⁺ channel-like current is partially responsible for such chemosensitivity in Phox2b-expressing neurons. The present study helps us better understand the mechanism of respiratory deficits in CCHS and potentially locates a brainstem site for development of precise clinical intervention.

ABSTRACT

The nucleus tractus solitarius (NTS) neurons have been considered to function as central respiratory chemoreceptors. However, the common molecular marker defined for these neurons remains unknown. The present study investigated whether paired-like homeobox 2b (Phox2b)-expressing NTS neurons are recruited in hypercapnic ventilatory response (HCVR) and whether these neurons exhibit intrinsic chemosensitivity. HCVR was assessed using whole body plethysmography and neuronal chemosensitivity was examined by patch clamp recordings in brainstem slices or dissociated neurons from Phox2b-EGFP transgenic mice. Injection of the neurotoxin substance P-saporin (SSP-SAP) into NTS destroyed Phox2b-expressing neurons. Minute ventilation and tidal volume were both reduced by 13% during exposure to 8% CO₂ in inspired air when ∼13% of the Phox2b-expressing neurons were eliminated. However, a loss of ∼18% of these neurons was associated with considerable decreases in minute ventilation by ≥18% and in tidal volume by≥22% when challenged by ≥4% CO₂ . In both cases, breathing frequency was unaffected. Most CO₂ -activated neurons were immunoreactive to Phox2b. In brainstem slices, ∼43% of Phox2b-expressing neurons from Phox2b-EGFP mice displayed a sustained or transient increase in firing rate during physiological acidification (pH 7.0 or 8% CO₂ ). Such a response was also present in dissociated neurons in favour of an intrinsic property. In voltage clamp recordings, a background K⁺ channel-like current was found in a subgroup of Phox2b-expressing neurons. Thus, the respiratory deficits caused by injection of SSP-SAP into the NTS are attributable to proportional lesions of CO₂ /H⁺ -sensitive Phox2b-expressing neurons.

Small field dose measurements using plastic scintillation detector in heterogeneous media

PURPOSE

The purpose of this study was to evaluate a plastic scintillation detector for the measurement of small field dosimetry and to verify the accuracy of measured dose in comparison with Monte Carlo calculation in a heterogeneous medium.

METHODS

The study is performed with CyberKnife planning and delivery system. The setup consists of a custom made solid lung phantom with the insert of an Exradin W1 scintillation detector or an Exradin A16 ion chamber. The measurement was done for a series of cone sizes from 5 mm to 60 mm, and the dose was calculated by Monte Carlo algorithm in MultiPlan workstation. The difference between measurement and calculation was reported.

RESULTS

Our preliminary results demonstrated the applicability of plastic scintillation detectors in the measurement of small field dosimetry in a heterogeneous medium. The difference between the calculated and measured output factors was less than 3% for all cone sizes from 60 mm down to 5 mm. Without any corrections, the measured dose from the scintillation detector calibrated to the ion chamber reading was also within 3% of the Monte Carlo calculation in the lung phantom for cone sizes 20 mm or larger.

CONCLUSIONS

Small field dosimetry is particularly relevant to stereotactic radiation treatment. The accuracy of dose calculation for small static beams is critical to dose planning so would potentially affect the treatment outcomes in a heterogeneous medium. Our results have shown good agreement with plastic scintillation detector in both homogeneous and heterogeneous medium.

Effect of beam profile measurement on arc therapy plan quality assurance: a case study

We present an example when profile measurement and modeling of an Elekta Agility multileaf collimator (MLC) had a large effect specifically on arc therapy plan quality assurance (QA) results using ArcCheck. ArcCheck absolute dose measurements of these plans were systematically lower than planned by 3–10%. Failing QA results were seen even with unmodulated static and conformal arcs. Furthermore, the effect was found to be dependent on collimator angle, with worse results associated with near‐zero collimator angles. In contrast, step‐and‐shoot QA results were not affected. Changing the beam model to match steeper profile measurements obtained using a different measurement device resolved the problem. This case study demonstrates that conventional gamma index analysis can be sensitive to small profile modeling changes.

Elevated semaphorin5A in systemic lupus erythematosus is in association with disease activity and lupus nephritis

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by extensive immune response, including over-activation of T and B cell development of pathogenic autoantibodies, organ damage induced by the formation and deposition of immune complex and the abnormal elevation of type I interferon. Semaphorin5A (Sema5A) is involved essentially in immune cell regulation and is also implicated in the pathogenesis of autoimmune disorders. We aimed to evaluate the role of Sema5A in patients with SLE. Serum levels of Sema5A were tested by enzyme-linked immunosorbent assay (ELISA) in 152 SLE patients and 48 healthy controls. The message ribonucleic acid (mRNA) expression levels of Sema5A and ADAM metallopeptidase domain 17 (ADAM17) in the peripheral blood mononuclear cells (PBMC) from 43 patients with SLE and 19 healthy controls were detected by the real-time-quantitative polymerase chain reaction (qPCR). Serum Sema5A levels were increased significantly in SLE patients compared with healthy controls (P < 0·001). Elevated levels of Sema5A were correlated positively with 24-h proteinuria excretion (r = 0·558, P < 0·0001), SLE disease activity index (SLEDAI) (r = 0·278, P = 0·0006) and C-reactive protein (CRP) (r = 0·266, P = 0·002), but negatively with planet (PLT) (r = -0·294, P = 0·0003) and complement 3 (C3) (r = -0·287, P = 0·0004) in SLE patients. Patients with elevated Sema5A levels showed higher incidence of rash, serositis and nephritis (P < 0·05 or P < 0·001). Patients with decreased PLT, C3 or positive for proteinuria also showed elevated Sema5A (P < 0·001 or P < 0·05). The mRNA ADAM17 was increased in SLE patients and correlated positively with serum Sema5A levels. Our data demonstrated that elevated serum Sema5A in SLE patients correlated with disease activity and are involved in kidney and blood system damage; ADAM17 might be involved in the release of secreted Sema5A.