Comparison of skin dose in IMRT and VMAT with TrueBeam and Halcyon linear accelerator for whole breast irradiation

With the increasing use of flattening filter free (FFF) beams, it is important to evaluate the impact on the skin dose and target coverage of breast cancer treatments. This study aimed to compare skin doses of treatments using FFF and flattening filter (FF) beams for breast cancer. The study established treatment plans for left breast of an anthropomorphic phantom using Halcyon's 6-MV FFF beam and TrueBeam's 6-MV FF beam. Volumetric modulated arc therapy (VMAT) with varying numbers of arcs and intensity modulated radiation therapy (IMRT) were employed, and skin doses were measured at five points using Gafchromic EBT3 film. Each measurement was repeated three times, and averaged to reduce uncertainty. All plans were compared in terms of plan quality to ensure homogeneous target coverage. The study found that when using VMAT with two, four, and six arcs, in-field doses were 19%, 15%, and 6% higher, respectively, when using Halcyon compared to TrueBeam. Additionally, when using two arcs for VMAT, in-field doses were 10% and 15% higher compared to four and six arcs when using Halcyon. Finally, in-field dose from Halcyon using IMRT was about 1% higher than when using TrueBeam. Our research confirmed that when treating breast cancer with FFF beams, skin dose is higher than with traditional FF beams. Moreover, number of arcs used in VMAT treatment with FFF beams affects skin dose to the patient. To maintain a skin dose similar to that of FF beams when using Halcyon, it may be worth considering increasing the number of arcs.

The relative importance of left atria reservoir strain compared with components of HFA-PEFF diagnostic algorithm

Background/Introduction

The relative importance of the left atrial reservoir strain (LARS) compared to the parameters constituting the HFA-PEFF score developed as a diagnostic tool for patients with heart failure with preserved ejection fraction (HFpEF) is not well known.

Purpose

We aimed to identify the relative importance of LARS compared with variables associated with HFpEF and HFA-PEFF score including echocardiographic parameters, demographic data, and NT-proBNP.

Methods

From August 2021 to March 2022, we obtained data retrospectively from the participants visiting our clinic in a single cardiovascular center. The 1,252 participants with sinus rhythm and ejection fraction more than 50% were enrolled in the present study (61.8±16.6 years and 55% female). Multivariable regression analysis using backward elimination and random forest analysis, supervised learning algorithm, were performed to identify the relative importance of LARS on the HFA-PEFF score.

Results

The median HFA-PEFF score was 3 points (interquartile range 2 to 4 points). Two hundred forty-one subjects (19.2%) had more than 5 points. LARS showed a moderate correlation with the HFA-PEFF score (r=−0.632, p<0.001). In multivariable regression analysis, LARS was independent variable affecting HFA-PEFF score with female sex, left atrial volume index (LAVI), septal e', E over e' (septal), the maximal tricuspid regurgitation velocity (TR-Vmax), left ventricular global longitudinal strain (LV-GLS), NT-proBNP, interventricular septal wall thickness (standardized β=−0.106; P<0.001). In random forest analysis, LARS was a more relatively important variable than TR-Vmax, NT-proBNP, septal E/e', septal e', the major echocardiographic components of HFA-PEFF score estimating more than 5 points of HFA-PEFF score.

Conclusions

LA reservoir strain is one of the important factors with components of the HFA-PEFF score which is a useful tool to assess the patients with HFpEF.

Funding Acknowledgement

Type of funding sources: None.

Radiation-induced C-reactive protein triggers apoptosis of vascular smooth muscle cells through ROS interfering with the STAT3/Ref-1 complex

Damage to normal tissue can occur over a long period after cancer radiotherapy. Free radical by radiation can initiate or accelerate chronic inflammation, which can lead to atherosclerosis. However, the underlying mechanisms remain unclear. Vascular smooth muscle cells (VSMCs) proliferate in response to JAK/STAT3 signalling. C-reactive protein (CRP) can induce VSMCs apoptosis via triggering NADPH oxidase (NOX). Apoptotic VSMCs promote instability and inflammation of atherosclerotic lesions. Herein, we identified a VSMCs that switched from proliferation to apoptosis through was enhanced by radiation-induced CRP. NOX inhibition using lentiviral sh-p22^phox prevented apoptosis upon radiation-induced CRP. CRP overexpression reduced the amount of STAT3/Ref-1 complex, decreased JAK/STAT phosphorylation and formed a new complex of Ref-1/CRP in VSMC. Apoptosis of VSMCs was further increased by CRP co-overexpressed with Ref-1. Functional inhibition of NOX or p53 also prevented apoptotic activity of the CRP-Ref-1 complex. Immunofluorescence showed co-localization of CRP, Ref-1 and p53 with α-actin-positive VSMC in human atherosclerotic plaques. In conclusion, radiation-induced CRP increased the VSMCs apoptosis through Ref-1, which dissociated the STAT3/Ref-1 complex, interfered with JAK/STAT3 activity, and interacted with CRP-Ref-1, thus resulting in transcription-independent cell death via p53. Targeting CRP as a vascular side effect of radiotherapy could be exploited to improve curability.

P818 Association between baseline left ventricular longitudinal strain and follow-up left ventricular ejection fraction in patients with dilated cardiomyopathy

Funding Acknowledgements

no

Background

Left ventricular global longitudinal strain (LV GLS) offers sensitive and reproducible measurement of myocardial dysfunction. The authors sought to evaluate whether LV GLS at the time of diagnosis may predict LV reverse remodeling (LVRR) in DCM patients with sinus rhythm and also investigate the relationship between baseline LV GLS and follow-up LVEF.

Methods

We enrolled patients with DCM who had been initially diagnosed, evaluated, and followed at our institute.

Results

During the mean follow-up duration of 37.3 ± 21.7 months, LVRR occurred in 28% of patients (n = 45) within 14.7 ± 10.0 months of medical therapy. The initial LV ejection fraction (LVEF) of patients who recovered LV function was 26.1 ± 7.9% and was not different from the value of 27.1 ± 7.4% (p = 0.49) of those who did not recover. There was a moderate and highly significant correlation between baseline LV GLS and follow-up LVEF (r = 0.717; p <0.001).

Conclusion

There was a significant correlation between baseline LV GLS and follow-up LVEF in this population.

Baseline Follow-up Difference (95% CI) p-value All patients (n = 160) LVEDDI, mm/m2 35.6 ± 6.6 35.6 ± 6.6 -2.7 (-3.4 to -2.0) <0.001 LVESDI, mm/m2 30.3 ± 6.1 26.6 ± 6.6 -3.7 (-4.6 to -2.8) <0.001 LVEDVI, mL/m2 95.0 ± 30.7 74.3 ± 30.2 -20.7 (-25.6 to -15.8) <0.001 LVESVI, mL/m2 70.0 ± 24.8 50.2 ± 26.8 -19.8 (-24.2 to -15.4) <0.001 LVEF, % 26.8 ± 7.5 33.9 ± 12.6 7.2 (5.2 to 9.2) <0.001 LV GLS (-%) 9.2 ± 3.1 11.0 ± 4.8 1.8 (1.3 to 2.2) <0.001 Patients without LVRR (n = 115) LVEDDI, mm/m2 34.9 ± 6.8 34.1 ± 6.8 -0.8 (-1.3 to -0.3) 0.002 LVESDI, mm/m2 29.5 ± 6.1 28.4 ± 6.4 -1.4 (-1.8 to -0.4) 0.002 LVEDVI, mL/m2 92.0 ± 30.5 83.4 ± 29.8 -8.6 (-12.4 to -4.8) <0.001 LVESVI, mL/m2 67.1 ± 24.4 59.5 ± 25.3 -7.6 (-10.9 to -4.3) <0.001 LVEF, % 27.1 ± 7.4 27.8 ± 7.4 0.7 (-0.2 to 1.6) 0.126 LV GLS (-%) 8.2 ± 2.9 8.7 ± 3.2 0.5 (0.7 to 3.6) <0.001 Patients with LVRR (n = 45) LVEDDI, mm/m2 37.4 ± 5.5 29.8 ± 5.2 -7.5 (-9.1 to -6.0) <0.001 LVESDI, mm/m2 32.2 ± 5.7 21.9 ± 4.4 -10.3 (-11.9 to -8.6) <0.001 LVEDVI, mL/m2 102.7 ± 30.2 51.1 ± 15.0 -51.7 (-61.6 to -41.7) <0.001 LVESVI, mL/m2 77.3 ± 24.5 26.4 ± 11.3 -50.9 (-58.8 to -43.1) <0.001 LVEF, % 26.1 ± 7.9 49.4 ± 9.5 23.9 (20.4 to 27.5) <0.001 LV GLS (-%) 11.9 ± 1.6 16.9 ± 2.7 5.1 (4.2 to 5.9) <0.001 Baseline and Follow-up LV Functional Echocardiographic Data

Abstract P818 Figure.

Treatment Outcome after Fractionated Conformal Radiotherapy for Hepatocellular Carcinoma in Patients with Child-Pugh Classification B in Korea (KROG 16-05)

Purpose

There is limited data on radiotherapy (RT) for hepatocellular carcinoma (HCC) in patients with Child-Pugh classification B (CP-B). This study aimed to evaluate the treatment outcomes of fractionated conformal RT in HCC patients with CP-B.

Materials and Methods

We retrospectively reviewed the data of HCC patients with CP-B treated with RT between 2009 and 2014 at 13 institutions in Korea. HCC was diagnosed by the Korea guideline of 2009, and modern RT techniques were applied. Fraction size was ≤ 5 Gy and the biologically effective dose (BED) ≥ 40 Gy₁₀ (α/β = 10 Gy). A total of 184 patients were included in this study.

Results

Initial CP score was seven in 62.0% of patients, eight in 31.0%, and nine in 7.0%. Portal vein tumor thrombosis was present in 66.3% of patients. The BED ranged from 40.4 to 89.6 Gy₁₀ (median, 56.0 Gy₁₀). After RT completion, 48.4% of patients underwent additional treatment. The median overall survival (OS) was 9.4 months. The local progression-free survival and OS rates at 1 year were 58.9% and 39.8%, respectively. In the multivariate analysis, non-classic radiation-induced liver disease (RILD) (p < 0.001) and additional treatment (p < 0.001) were the most significant prognostic factors of OS. Among 132 evaluable patients without progressive disease, 19.7% experienced non-classic RILD. Normal liver volume was the most predictive dosimetric parameter of non-classic RILD.

Conclusion

Fractionated conformal RT showed favorable OS with a moderate risk non-classic RILD. The individual radiotherapy for CP-B could be cautiously applied weighing the survival benefits and the RILD risks.

Long-term outcomes of the 2-week schedule of hypofractionated radiotherapy for recurrent hepatocellular carcinoma

Background

The 2-week schedule of hypofractionated radiotherapy as a salvage treatment for hepatocellular carcinoma (HCC) has previously exhibited promising results; this study aimed to assess its long-term clinical outcomes in patients with recurrent HCC ineligible for curative treatments.

Methods

We retrospectively enrolled 77 patients (84 lesions) with HCC who were treated with hypofractionated radiotherapy between December 2008 and July 2013. Primary inclusion criteria were HCC unsuitable for curative treatments and HCC located within 2 cm of a critical normal organ. We administered 3.5–5 Gy/fraction for 2 weeks, resulting in a total dose of 35–50 Gy.

Results

The median follow-up period was 33.6 (range, 4.8–78.3) months. The 3- and 5-year overall survival rates were 52.3% and 40.9%, respectively, and local control rates were 79.5% and 72.6% in all treated lesions, respectively. The 5-year local control rate was better in the higher radiation dose group than in the lower radiation dose group (50 Gy: 79.7% vs. < 50 Gy: 66.1%); however, the difference was not statistically significant (P = 0.493). We observed grade ≥ 3 hepatic toxicity in 2 (2.6%) patients and grade 3 gastrointestinal bleeding in 1 (1.3%) patient. However, grade ≥ 4 toxicity was not observed after hypofractionated radiotherapy.

Conclusions

The 2-week schedule of hypofractionated radiotherapy for recurrent HCC exhibited good local control and acceptable treatment-related toxicity during the long-term follow-up period. Thus, this fractionation schedule can be a potential salvage treatment option for recurrent HCC, particularly for tumors located close to a radiosensitive gastrointestinal organ.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4953-x) contains supplementary material, which is available to authorized users.

Clinical significance of the post-radiotherapy 18F-fludeoxyglucose positron emission tomography response in nasopharyngeal carcinoma

Objective:

The aim of the present study was to evaluate the clinical significance of the post-radiotherapy ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) response for detecting residual disease and predicting survival outcome in patients with nasopharyngeal cancer.

Methods:

We reviewed 143 patients with nasopharyngeal cancer who underwent ¹⁸F-FDG PET within 6 months after completion of radiotherapy between 2001 and 2012. ¹⁸F-FDG PET findings at the primary tumor (T–) and regional lymph nodes (N–) were separately assessed and considered negative [PET (–)] or positive [PET (+)] depending on the remaining focal increased uptake of ¹⁸F-FDG that was greater than that of the surrounding muscle or blood vessels. The standard of reference was histopathological confirmation or clinical/imaging follow-up. Overall survival (OS), distant metastasis-free survival (DMFS), and locoregional recurrence-free survival (LRRFS) rates were estimated from the date of the start of radiotherapy.

Results:

The median follow-up period was 73 months (range, 9–182 months). Overall, 83 and 66% of patients achieved T–PET (-) and N–PET (-) responses, and the negative-predictive values (NPVs) for T– and N– were 100 and 99%, respectively. The sensitivity, specificity, and positive-predictive value were 100, 84, and 8% for T–, and 67, 80, and 7% for N–, respectively. The 5-year OS, DMFS, and LRRFS rates were 83, 83, and 87%, respectively, and patients with N–PET (+) with SUV_max >2.5 showed significantly inferior 5-year OS and DMFS rates than patients with N–PET (-) or N–PET (+) with SUV_max ≤2.5 (44 vs 86%, p = 0.004; 36 vs 85%, p < 0.001).

Conclusion:

In patients that have received definitive (chemo)radiotherapy for nasopharyngeal cancer, ¹⁸F-FDG PET within 6 months of completion of treatment has a high NPV for predicting residual disease and is prognostic for long-term treatment outcomes. Patients with remaining focal increased uptake of ¹⁸F-FDG at lymph nodes may benefit from more aggressive treatments, and further studies are needed to validate the clinical significance of post-radiotherapy ¹⁸F-FDG PET.

Advances in knowledge:

We found that post-radiotherapy ¹⁸F-FDG PET findings have a high NPV for detecting residual disease and are a significant prognostic factor for treatment outcomes.

High-dose radiotherapy is associated with better local control of bone metastasis from hepatocellular carcinoma

We evaluated the pain and radiologic response, time to progression, and dose-response relationship after palliative radiotherapy for bone metastasis from hepatocellular carcinoma. We retrospectively reviewed the medical records of 91 patients between January 2004 and August 2012. The reviewed medical records included data on changes in pain, local tumor progression, and radiologic response evaluated via follow-up images. The radiologic response was assessed based on the Response Evaluation Criteria In Solid Tumors. The pain response was defined according to the International Bone Metastases Consensus Working Party palliative radiotherapy endpoints. Median radiation dose was 40 Gy (range, 20-66 Gy), with various fraction sizes (range, 2.0-6.0 Gy). Pain response rate was 81.4%. During the follow-up periods, radiologic local tumor progression was found in 42 patients (46.2%). The median time to progression was 14.1 months. When the patients were divided into two groups according to their radiation dose (< 55 Gy10 vs. ≥ 55 Gy10), the pain response rates of the high- and low-dose groups did not differ significantly (p = 0.728). However, the radiologic response rate and the time to progression showed significant differences between the two groups (p = 0.009 and p = 0.018, respectively). With dose escalation, higher radiologic response rates and a longer time to progression were achieved in patients with mass-forming bone metastases from hepatocellular carcinoma.

Feasibility of normal tissue dose reduction in radiotherapy using low strength magnetic field

Purpose

Toxicity of mucosa is one of the major concerns of radiotherapy (RT), when a target tumor is located near a mucosal lined organ. Energy of photon RT is transferred primarily by secondary electrons. If these secondary electrons could be removed in an internal cavity of mucosal lined organ, the mucosa will be spared without compromising the target tumor dose. The purpose of this study was to present a RT dose reduction in near target inner-surface (NTIS) of internal cavity, using Lorentz force of magnetic field.

Materials and Methods

Tissue equivalent phantoms, composed with a cylinder shaped internal cavity, and adjacent a target tumor part, were developed. The phantoms were irradiated using 6 MV photon beam, with or without 0.3 T of perpendicular magnetic field. Two experimental models were developed: single beam model (SBM) to analyze central axis dose distributions and multiple beam model (MBM) to simulate a clinical case of prostate cancer with rectum. RT dose of NTIS of internal cavity and target tumor area (TTA) were measured.

Results

With magnetic field applied, bending effect of dose distribution was visualized. The depth dose distribution of SBM showed 28.1% dose reduction of NTIS and little difference in dose of TTA with magnetic field. In MBM, cross-sectional dose of NTIS was reduced by 33.1% with magnetic field, while TTA dose were the same, irrespective of magnetic field.

Conclusion

RT dose of mucosal lined organ, located near treatment target, could be modulated by perpendicular magnetic field.

Clinical outcome of fiducial-less CyberKnife radiosurgery for stage I non-small cell lung cancer

Purpose

To evaluate the treatment results in early stage non-small cell lung cancer patients who have undergone fiducial-less CyberKnife radiosurgery (CKRS).

Materials and Methods

From June 2011 to November 2013, 58 patients underwent CKRS at Asan Medical Center for stage I lung cancer. After excluding 14 patients, we retrospectively reviewed the records of the remaining 44 patients. All analyses were performed using SPSS ver. 21.

Results

The median age at diagnosis was 75 years. Most patients had inoperable primary lung cancer with a poor pulmonary function test with comorbidity or old age. The clinical stage was IA in 30 patients (68.2%), IB in 14 (31.8%). The mean tumor size was 2.6 cm (range, 1.2 to 4.8 cm), and the tumor was smaller than 2 cm in 12 patients (27.3%). The radiation dose given was 48-60 Gy in 3-4 fractions. In a median follow-up of 23.1 months, local recurrence occurred in three patients (2-year local recurrence-free survival rate, 90.4%) and distant metastasis occurred in 13 patients. All patients tolerated the radiosurgery well, only two patients developing grade 3 dyspnea. The most common complications were radiation-induced fibrosis and pneumonitis. Eight patients died due to cancer progression.

Conclusion

The results showed that fiducial-less CKRS shows comparable local tumor control and survival rates to those of LINAC-based SABR or CKRS with a fiducial marker. Thus, fiducial-less CKRS using Xsight lung tracking system can be effectively and safely performed for patients with medically inoperable stage I non-small cell lung cancer without any risk of procedure-related complication.

Effects of alpha-toxin of Staphylococcus aureus on the ciliary activity and ultrastructure of human nasal ciliated epithelial cells

OBJECTIVE

The in vitro effects of staphylococcal alpha-toxin on ciliary activity were investigated at different concentrations and exposure times.

STUDY DESIGN

Ciliated epithelial cells of the sphenoid sinus were taken from patients operated on for pituitary tumors. Video-computerized analysis technique and transmission electron microscopy were used to analyze the effects of the toxin on ciliary activity.

METHODS

Ciliary beat frequency (CBF) was measured in four different concentrations of alpha-toxin including 0.1, 1, 10, and 50 microg/mL. CBF was measured at 2, 4, 6, 12, 24, and 48 hours after administration of the toxin. To observe reversibility of the reduced ciliary activity, after 24-hour incubation in the media containing 10 microg/mL of alpha-toxin, the media were replaced with alpha-toxin-free media. The tissues were also processed for transmission electron microscopy to observe ultrastructural changes of the epithelial cells.

RESULTS

CBF increased significantly at 2-hour incubation and then decreased significantly after 12-hour incubation in 10 microg/mL of alpha-toxin (P< .05, repeated-measures ANOVA). The transmission electron microscopic findings showed mitochondrial swelling and a slight protrusion of the plasma membrane of the cilia. In toxin-free media, loss of ciliary activity was not recovered.

CONCLUSIONS

CBF increased at first, but with increasing incubation time ciliary movements decreased gradually and stopped eventually. This loss of CBF may be an irreversible change associated with ultrastructural changes in the mitochondria and the plasma membrane of the cilia.

Effects of free radicals on ciliary movement in the human nasal epithelial cells

OBJECTIVE

There have been few reports on the effects of free oxygen radicals on ciliary mobility of nasal respiratory epithelial cells. The aim of this study was to determine the effects of free radicals and antioxidants on human nasal epithelial cells (HNECs) using video-computerized analysis.

METHODS

Human nasal epithelial cells were obtained from the nasal cavity of normal volunteers. Ciliary beat frequency (CBF) was calculated as the mean value of ten randomly selected cells. The proportion of the area with normal CBF (above 8 Hz) was calculated from 10 randomly selected sites per specimen. Free radicals were produced by xanthine-xanthine oxidase enzymatic system. The generation of free radicals was confirmed by chemoilluminometer. CBF and the proportion of the area with normal CBF were measured at every 5 min for 30 min after the addition of enzyme. For the evaluation of the antioxidant effects on free radical-mediated ciliary slowing in HNECs, cells were incubated in superoxide dismutase solution (300 unit/ml) for 30 min and 3-aminobenzamide (5 mM).

RESULTS

Superoxide produced by 0.4 mM xanthine and 400 miliunit/ml xanthine oxidase decreased CBF (7.71 +/- 1.91 Hz). A total of 2 min later, ciliary slowing was evident (3.87 +/- 1.10 Hz). Regarding the changes in proportion of epithelial area that showed normal CBF experimental group showed a significant decrease in percentage of epithelial area with normal CBF over time. Superoxide dismutase prevented ciliary slowing (8.76 +/- 0.99 Hz). Moreover, 3-aminobenzamide, an inhibitor of the DNA repair enzyme poly-ADP ribose polymerase, prevented inhibition of CBF (8.32 +/- 0.61 Hz).

CONCLUSIONS

These results suggest that oxygen-mediated damage to DNA may be the mechanism of the deterioration effects of oxygen radicals on the ciliated respiratory nasal epithelium.