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  • Author: Jia-Li Zhang x
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Dosimetric comparison for volumetric modulated arc therapy and intensitymodulated radiotherapy on the left-sided chest wall and internal mammary nodes irradiation in treating post-mastectomy breast cancer

Abstract

Background. The aim of the study was to evaluate the dosimetric benefit of applying volumetric modulated arc therapy (VMAT) on the post-mastectomy left-sided breast cancer patients, with the involvement of internal mammary nodes (IMN).

Patients and methods. The prescription dose was 50 Gy delivered in 25 fractions, and the clinical target volume included the left chest wall (CW) and IMN. VMAT plans were created and compared with intensity-modulated radiotherapy (IMRT) plans on Pinnacle treatment planning system. Comparative endpoints were dose homogeneity within planning target volume (PTV), target dose coverage, doses to the critical structures including heart, lungs and the contralateral breast, number of monitor units and treatment delivery time.

Results. VMAT and IMRT plans showed similar PTV dose homogeneity, but, VMAT provided a better dose coverage for IMN than IMRT (p = 0.017). The mean dose (Gy), V30 (%) and V10 (%) for the heart were 13.5 ± 5.0 Gy, 9.9% ± 5.9% and 50.2% ± 29.0% by VMAT, and 14.0 ± 5.4 Gy, 10.6% ± 5.8% and 55.7% ± 29.6% by IMRT, respectively. The left lung mean dose (Gy), V20 (%), V10 (%) and the right lung V5 (%) were significantly reduced from 14.1 ± 2.3 Gy, 24.2% ± 5.9%, 42.4% ± 11.9% and 41.2% ± 12.3% with IMRT to 12.8 ± 1.9 Gy, 21.0% ± 3.8%, 37.1% ± 8.4% and 32.1% ± 18.2% with VMAT, respectively. The mean dose to the contralateral breast was 1.7 ± 1.2 Gy with VMAT and 2.3 ± 1.6 Gy with IMRT. Finally, VMAT reduced the number of monitor units by 24% and the treatment time by 53%, as compared to IMRT.

Conclusions. Compared to 5-be am step-and-shot IMRT, VMAT achieves similar or superior target coverage and a better normal tissue sparing, with fewer monitor units and shorter delivery time.

Open access
Effects of Electroacupuncture at Neiguan Acupoint on SOD and Mitochondrial Transmembrane Potential of Rabbits with Myocardial Ischemia-Reperfusion Injury

Abstract

Objective: To investigate the influence of electroacupuncture (EA) preconditioning at Nei Guan point (PC6) on the opening of mitochondrial permeability transition pore (MPTP) of rabbits with myocardial ischemia-reperrfusion injury, and its underlying mechanism that protects myocardium from injury.

Methods: 18 New Zealand rabbits were randomly assigned to pseudo-operation, model and EA groups, 6 in each group. Setting up models by ligation of coronary artery and electrically stimulating the rabbits in EA group 20 min per day in 5 days before modeling. Testing the activity of serum SOD with the method of actinochemistry, testing changes of mitochondrial transmembrane potential of myocardial cells with the method of synchronous spectrometry, using spectrophotometry to test the changes of the absorption of mitochondria at the spectrum of 520nm to check the opening of MPTP, and testing the apotosis of cells by means of terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).

Results: Compared with model groups, the SOD activity of myocardial cells was significantly enhanced, and the apotosis index (AI) was reduced(P<0.01),mitochondrial transmembrane potential was significantly increased (P<0.05),absorption of mitochondria was significantly decreased(P<0.01).

Conclusion: EA can remarkably improve myocardial ischemia - reperfusion injury, and protect myocardium.

Open access