SU-E-T-637: 4D-VMAT Vs. Gated VMAT in Lung Cancer SBRT.

PURPOSE: To assess plan quality and treatment efficiency of 4D-VMAT and gated-VMAT in the treatment of non-small cell lung cancer using SBRT. METHODS: Treatment planning software was developed in Matlab to simulate both 4D-VMAT and gated-VMAT on patients with stage I lung cancer and at least 1 cm of tumour motion. Gated-VMAT delivers radiation to the tumour during only a portion of the respiratory cycle and hence requires frequent start and stop motions of the gantry. In the 4D-VMAT algorithm, target and organ motion from the entire respiratory cycle is incorporated during optimization. Gantry moves continuously but delivery of each MLC aperture is synchronized to specific phases of target motion. All 4D-CT scan consisted of 10 phases and were acquired with the patients breathing freely. The SBRT fractionation scheme was 48 Gy in 4 fractions with at least 95% of the PTV receiving 100% of the prescription dose. For gated-VMAT, the PTV was derived from the ITV of the relevant respiratory phases plus a 5mm margin. In the 4D VMAT algorithm, the GTV was defined on a single phase and the PTV created with a 5mm margin. PTVs for the other respiratory phases were determined through 4D-image registration and deformation using a bspline transformation model. For both treatment deliveries, dose was accumulated on the maximum exhale phase and DVHs generated. RESULTS: Findings show gated-VMAT and 4D-VMAT deliveries resulted in maximum doses to most OARs far below SBRT protocol constraints. The 4D-VMAT beam on time is on average 8 min. Gated-VMAT will have similar beam on time but treatment time can more than double after accounting for 25 to 35 beam interruptions per arc. CONCLUSIONS: Gated-VMAT and 4D-VMAT were able to produce dosimetrically acceptable lung SBRT plans. The advantage of 4D-VMAT is the greater efficiency in treatment delivery.

Diurnal and monthly variation of indoor radon and thoron progeny concentrations at a hillside place of northern India.

The natural radioactivity levels all over the world can create health problems due to the inhalation of radioactive aerosols. Radon and thoron progeny content of indoor air have major contribution to natural radiation dose. In the present study, simultaneous indoor measurements of radon and thoron progeny concentrations have been carried out over a period of four months at a low activity hilly area of northern Punjab, India to see their diurnal and monthly variations. The method used for this purpose is based on the defined solid angle absolute beta counting of radioactive aerosols sampled on a filter. The average values of equilibrium equivalent radon and thoron concentrations were 5.20 Bq m(-3) and 0.235 Bq m(-3), respectively, over the period August to November 2003. Both, EECRn and EECTh show a negative correlation with temperature.

Effect of short pulsed nonablative infrared laser irradiation on vascular cells in vitro and neointimal hyperplasia in a rabbit balloon injury model.

BACKGROUND: Neointimal hyperplasia after PTCA is an important component of restenosis. METHODS AND RESULTS: Cultures of rabbit endothelial cells and smooth muscle cells (SMCs) were irradiated with different doses of nonablative infrared (1064-nm) radiation. Normalized viability index detected with nondestructive Alamar Blue assay and direct cell count were studied. Our experiments demonstrated dose-dependent cytostatic or cytotoxic effects of laser irradiation. We also evaluated the long-term effect of endoluminal nonablative infrared laser irradiation on neointimal hyperplasia in a rabbit balloon injury model. PTCA of both iliac arteries of 23 New Zealand White rabbits was performed. One iliac artery was subjected to intra-arterial subablative infrared irradiation via a diffuse tip fiber. The contralateral vessel served as control. The diet was supplemented with 0.25% cholesterol and 2% peanut oil for 10 days before and 60 days after PTCA. Morphometry after 60 days showed that intimal areas were 0.76+/-0.18 and 1.85+/-0.30 mm(2) in the laser and control arteries, respectively (P=2.2x10(-11)). CONCLUSIONS: We conclude that nonablative infrared laser inhibited neointimal hyperplasia after PTCA in cholesterol-fed rabbits for up to 60 days.

Intravascular low-power laser irradiation after coronary stenting: long-term follow-up.

BACKGROUND AND OBJECTIVE: A high restenosis rate remains a limiting factor for percutaneous transluminal coronary angioplasty and stenting. The objective of this study was to evaluate the effect of intravascular red laser therapy (IRLT) on restenosis after stenting procedures in de novo lesions. STUDY DESIGN/MATERIALS AND METHODS: A total of 68 consecutive patients were treated with IRLT in conjunction with coronary stenting procedures. Mean lesion length was 16.5 +/- 2.4 mm. Reference vessel diameter (RVD) and pre-minimal lumen diameter (MLD) were 2.90 +/- 0.15 mm and 1.12 +/- 0.26 mm, respectively. RESULTS: After treatment, MLD was 2.76 +/- 0.32 mm with no procedural complications or in-hospital adverse events. Angiographic follow-up (n = 61) revealed restenosis in nine patients (14.7%) with rate by artery size of > 3 mm (n = 21) 0%; 2.5--3.0 mm (n = 28) 14.2%; and < 2.5 mm (n = 12) 41.6%. CONCLUSION: Intravascular red light therapy is safe, feasible, and reduces expected restenosis rate after coronary stenting.

Study of nuclear quadrupole interactions in different environments of decaying atoms of 75Se by sum peak method.

The sum peak intensity I400 (279 + 121 keV) relative to its singles peak intensity I279 or I121 has been determined in various environments of 75Se by gamma-gamma summing technique in a single HPGe detector. The change in intensity has been used to determine nuclear quadrupole interaction frequencies and electric field gradient components in different environments, e.g. Se-glycerol, Se-hydrochloric acid (HCl), Se-perchloric acid (HClO4), Se-blood samples with and without anti-coagulant, Se-alanine and Se-cysteine at different pH values. The electric field gradient is found to vary with chemical complex formation.

Endoluminal reconstruction of the arterial wall with endothelial cell/glue matrix reduces restenosis in an atherosclerotic rabbit.

OBJECTIVES: The objectives of this study were 1) to improve the attachment of reimplanted endothelial cells (EC) using a fibrin glue, and 2) to assess the impact of endothelial reseeding on restenosis eight weeks after balloon angioplasty. BACKGROUND: A possible mechanism contributing to restenosis after balloon angioplasty is the loss of the EC lining. Previous attempts to reseed EC had little effect due to rapid loss of the seeded cells. METHODS: Twelve atherosclerotic rabbits were subjected to angioplasty of iliac arteries and reseeding procedure. One iliac artery was subjected to EC/glue reconstruction and a contralateral site to EC seeding without glue. The animals were sacrificed after 4 h. In another series 12 rabbits were treated in the same fashion and were restudied at eight weeks. Additionally, in 10 animals one iliac was subjected to glue treatment, and another served as control. RESULTS: Histological examination demonstrated the ability of this method to reattach the EC/glue matrix circumferentially to 68.0 +/- 6.7% of the arterial wall in comparison with 13.5 +/- 3.9% reattachment after EC seeding. Morphometry at eight weeks showed that the lumen area was significantly greater in the EC/glue group (1.23 +/- 0.35 mm2) than in the EC seeding alone (0.65 +/- 0.02 mm2) and 0.72 +/- 0.41 mm2 in the glue group. This was principally accounted for by the statistically significant differences in the intimal area (0.76 +/- 0.18 mm vs. 1.25 +/-0.26 mm2 and 1.01 +/- 0.53 mm2, respectively). CONCLUSIONS: The attachment of EC after angioplasty can be greatly improved with fibrin glue matrix. The near 70% endothelial coverage achieved by this method resulted in a significant reduction of restenosis in atherosclerotic rabbit.

Long-term follow-up after coronary stenting and intravascular red laser therapy.

A high restenosis rate remains a limiting factor for coronary angioplasty and stenting. Recently, use of intravascular red light therapy (IRLT) has been shown to be effective in different animal models and in humans in reducing the restenosis rate. Sixty-eight patients were treated with IRLT in conjunction with coronary stenting procedures. Mean age was 64 +/- 9 years. Treated lesions were type A (11), type B (42), and type C (18) with a mean lesion length of 16.5 +/- 2.4 mm. Reference vessel diameter and minimal lumen diameter (MLD) before therapy were 2.90 +/- 0.15 and 1.12 +/- 0.36 mm, respectively. After stenting and laser irradiation, MLD was 2.76 +/- 0.39 mm. No procedural complications or in-hospital adverse events occurred. All patients were followed up as depicted in the protocol. Sixty-one patients underwent angiographic restudy, which revealed restenosis in 9 patients (14.7%). Observed restenosis rate by artery size was > 3 mm (n = 21, 0%), 2.5 to 3.0 mm (n = 28, 14.2%), and <2.5 mm (n = 12, 41.6%). We conclude that IRLT is safe and feasible and reduces the expected restenosis rate in patients after coronary stenting in arteries of >2.5 mm.

Influence of different stent materials on endothelialization in vitro.

The objective of our study was to investigate the influence of different stent materials on endothelialization in vitro. Using the non-destructive Alamar Blue assay and scanning electron microscopy, we compared long-term growth and morphology of vascular cells on disks of three prospective stent materials, i.e., 316 L stainless steel, 18 K, and 24 K gold. Our results demonstrate superior human EC proliferative capacity on gold surfaces compared to that on 316 L stainless steel. Thus, both the hyperplasia and thrombotic complications which often follow stenting might be minimized by employing gold stents, which have a greater capacity than steel in supporting a functional neo-endothelium.

Photoremodeling of arterial wall reduces restenosis after balloon angioplasty in an atherosclerotic rabbit model.

OBJECTIVES: This study evaluated the long-term impact of endoluminal low power red laser light (LPRLL) on restenosis in an atherosclerotic rabbit model. BACKGROUND: Despite widespread application of balloon angioplasty for treatment of coronary artery disease, restenosis limits its clinical benefits. Restenosis is a complex process and may be partly attributed to the inability of the vascular endothelium to regenerate and cover the denuded area at the site of arterial injury. We previously demonstrated that LPRLL stimulates endothelial cell proliferation in vitro and contributes to rapid endothelial regeneration after balloon injury in nonatherosclerotic rabbits. METHODS: Rabbit abdominal aortas (n = 12) were treated in separate zones with balloon dilation and balloon dilation plus laser illumination. Endoluminal laser therapy was performed using a laser-balloon catheter delivering a single dose of 10 mW for 3 min from a helium-neon laser (632 nm). Angiography was performed before and after treatment and was repeated 8 weeks before harvesting the aortas. RESULTS: Quantitative angiographic analysis demonstrated no differences in the minimal lumen diameter (MLD) between the two zones before treatment; an increase in the MLD in both zones after balloon angioplasty and a significant versus slight reduction of the MLD in the balloon treatment versus balloon plus laser zones at 8 weeks. Histologic examination showed a very high level of myointimal hyperplasia in the balloon treatment zones but a minimal level in the LPRLL-treated zones. Morphometric analysis revealed a statistically significant difference in the lumen area, intimal area and intima/media ratio between the balloon versus balloon plus laser treatment sites. CONCLUSIONS: Our experimental data indicate that endoluminal irradiation with LPRLL prevents restenosis after balloon angioplasty in an atherosclerotic rabbit model.

A testing system for electric toothbrushes.

PURPOSE: To assess in vitro the contributions of mechanical and acoustic microstreaming forces around electric toothbrushes to remove cheese using an experimental model. MATERIALS AND METHODS: Four toothbrushes, Braun Oral-B Plaque Remover (D7), Braun Oral-B Ultra Plaque Remover (D9), Interplak (IP) & Sonicare (SC), were investigated. A model system consisting of a layer of 0.2 mm thick cheese was applied to a microscope slide. The toothbrushes were operated in contact with the slide under loads of 0.3 N dry or with the bristles immersed in 2 mm of water. Turbulence around the moving head was assessed with the bristles placed non-contacting, 1 mm above the slide. An experiment with contact for 2 seconds and then 10 seconds non-contact was also made. The slides were stained and image analyzed. The area of removal was measured together with the "average cleaning/brush contact unit area", (the area of removal was divided by bristle contact area. RESULTS: The removal pattern varied. D9 and SC were efficient when operated dry. When the brushes were operated in water, the D9, SC, and IP were efficient in removing the cheese. With no contact, SC produced disruption of the cheese layer while the other brushes did disturb the surface but did not remove completely the cheese. This disturbance without removal was not recorded by image analysis. When the vibrating brushes were allowed to touch the medium and then moved away, a large amount of removal occurred. Larger amounts of removal took place with the D7, D9 and the SC. The use of brushes with a larger head and bristle contact produced a larger area of removal. However, when the "average cleaning/brush contact unit area" was used, the smaller headed brushes produced a larger amount of removal relative to their size. These differences in the removal characteristics between the four electric toothbrushes in vitro suggest that such a model system may prove useful in testing such devices before they are assessed clinically.

Percutaneous Application of Fibrin Sealant to Achieve Hemostasis Following Arterial Catheterization.

OBJECTIVES: The present study sought to investigate the safety and efficacy of a new fibrin sealant using percutaneous delivery techniques. BACKGROUND: The femoral approach has become the preferred means of access for percutaneous diagnostic and interventional procedures. Control of access site bleeding following catheterization, however, remains a significant problem in interventional cardiology. METHODS: Adult mongrel dogs were used in this study. Series 1 compared the effectiveness of fibrin sealant vs. manual compression alone in the presence of anticoagulants, thrombolytic, and antiplatelet agents. Series 2 assessed fibrin sealant safety. Series 3 examined fibrin sealant performance under elevated blood pressure levels. RESULTS: Series 1: Hemostasis was achieved in all fibrin sealant sites in significantly less time (8.5 +/- 4.3 min) with no major complications compared to manual compression sites (65.2 +/- 19.3 min) accompanied by serious complications. For all adjunctive agents employed, hemostasis was achieved in fibrin sealant sites in significantly less time (warfarin 9.9 +/-.2, urokinase 11.2 +/- 5.6, ReoProª 10.5 +/- 6.3 min) than for manual compression sites (warfarin 86.5 +/- 21.4, urokinase 89.8 +/- 36.3, ReoPro 77.9 +/- 26.5 min). Series 2: I25 iodine-labeled fibrinogen sealant was applied to puncture sites with no traces of circulating radioactivity observed over a one-hour period. Series 3: hemostasis was achieved under elevated blood pressure conditions in all animals. Histologic studies showed complete re-absorption of fibrin sealant 28 days post-procedure with no evidence of foreign body reaction. CONCLUSIONS: Percutaneous application of fibrin sealant to achieve hemostasis following catheterization appears to be a simple, safe, and highly effective procedure in a canine model.

Intravascular Low Power Red Laser Light as an Adjunct to Coronary Stent Implantation Evaluated in a Porcine Coronary Model.

BACKGROUND: It is believed that restenosis following coronary interventions is the result of endothelial denudation that leads to thrombus formation, vascular remodeling, and smooth muscle cell proliferation. We previously demonstrated that low power red laser light (LPRLL) irradiation enhances endothelial cell growth in vitro and in vivo and reduces restenosis in a small animal model. The present study investigated the effectiveness of intravascular LPRLL therapy in the reduction of restenosis following stenting in a porcine model. METHODS AND RESULTS: Stents were placed in the right coronary artery of domestic cross-bred pigs. After stent deployment, an additional inflation was performed with the laser-balloon. In group I (n = 18) no LPRLL was used; group II (n = 10) received LPRLL dosage of 10 mW for 1 minute; group III (n = 10) received LPRLL dosage of 34 mW for 1 minute. Quantitative coronary analysis of the stented vessel was performed before, immediately after stenting, and at 6 weeks. The pigs were sacrificed and histologic and planimetric analysis conducted. At 6 weeks, minimal luminal stent diameter was significantly narrower in the control group compared to the higher dose group (p < 0.05), late loss correlated inversely proportional to the dose used (r = 0.9; p < 0.03), these results were confirmed by morphometric analysis. Neointimal area was also significantly decreased in the higher dose group. CONCLUSIONS: Intravascular LPRLL contributes to reduction of angiographic restenosis and hyperplastic reaction in this animal model and seems to be dose dependent.

The application of energy-dispersive x-ray fluorescence spectrometry (EDXRF) to the analysis of cosmetic evidence in Indian nail polishes.

The application of energy-dispersive x-ray fluorescence (EDXRF) spectrometry in the quantitative analysis of samples of Indian nail polishes of apparently similar shades from different manufacturers has been examined by evaluating the possibility of detecting spurious material which is marketed under the guise of a popular brand. On the basis of the number of elements detected, and from the ratios of particular elements [Fe/Ti, Fe/Cu, Ti/Cu] the results are very encouraging.

Study of perturbed angular correlation parameters in bovine serum albumin using 133Ba as a probe.

The gamma-gamma sum peak method has been applied to the measurement of the total attenuation factors G22, in different concentrations of biological material, bovine serum albumin (BSA) using 133Ba as a probe. It is observed that G22 is inversely proportional to the correlation time of the two cascade radiations and to the concentration of biological sample surrounding the probe.

The suitability of 160Tb as a PAC probe for studies of biomolecules.

The gamma-ray perturbed angular correlation (PAC) studies were made with 160Tb as a probe in MES (2[N-morpholino]-ethane sulphonic acid) solutions of various concentrations. The measurements indicate no influence of concentration of the environment on its interaction with Tb3+ ion and as such reveal the fact that 160Tb is not a good probe for PAC studies.

Neutron activation analysis of trace elements in human hair: effect of dietary and environmental factors.

Effect of environment and dietary habits on trace element contents in human scalp hair has been investigated in the present work. Trace elements were detected with neutron activation technique. It was found that diet and environment contribute largely towards the trace elements in human body. Further trace elements Te, Lu, Ba, Cs, Yb, Re, Hf, In and Ir were detected for the first time in human scalp hair.

An unusual coronary abnormality.

An unusual case of an aberrant coronary artery is described. The aberrant artery arose from the L.A.D. branch and ended in the aorta. It had two aneurysmal dilatations.