Andrew Wu

Initial surgeon training for single port access surgery: our first year experience.

This study suggests that single port access techniques can be easily learned in an animate laboratory setting.

Effects of extended SSD on electron-beam depth-dose curves

The effects of extended source-to-surface distance (SSD) on the electron-beam depth dose curves were examined for five electron beam energies ranging from 6 MeV to 20 MeV. The depth dose curves were measured with the water phantom surface set at 100 cm, 110 cm, and 120 cm from the source. Except for the dose in the build-up region, negligible depth dose curve changes due to extended SSD were observed for electron energies less than or equal to 12 MeV. For electron beams greater than 12 MeV, the percent surface dose decreases and, additionally, the depth of maximum dose shifts deeper into the phantom as the SSD increases. Changes in the rapid falloff region of the depth dose curves were apparent only for the higher energy electron beams, in particular 20 MeV. Extended SSD has no observable effect on the tail portion of the depth dose curves. As such, the energies of the electron beams are not changed significantly by increasing the SSD.

Dose volume assessment of high dose rate 192IR endobronchial implants

PURPOSE To study the dose distributions of high dose rate (HDR) endobronchial implants using the dose nonuniformity ratio (DNR) and three volumetric irradiation indices. METHODS AND MATERIALS Multiple implants were configured by allowing a single HDR 192Ir source to step through a length of 6 cm along an endobronchial catheter. Dwell times were computed to deliver a dose of 5 Gy to points 1 cm away from the catheter axis. Five sets of source configurations, each with different dwell position spacings from 0.5 to 3.0 cm, were evaluated. Three-dimensional (3D) dose distributions were then generated for each source configuration. Differential and cumulative dose-volume curves were generated to quantify the degree of target volume coverage, dose nonuniformity within the target volume, and irradiation of tissues outside the target volume. Evaluation of the implants were made using the DNR and three volumetric irradiation indices. RESULTS The observed isodose distributions were not able to satisfy all the dose constraints. The ability to optimally satisfy the dose constraints depended on the choice of dwell position spacing and the specification of the dose constraint points. The DNR and irradiation indices suggest that small dwell position spacing does not result in a more homogeneous dose distribution for the implant. This study supports the existence of a relationship between the dwell position spacing and the distance from the catheter axis to the reference dose or dose constraint points. Better dose homogeneity for an implant can be obtained if the spacing of the dwell positions are about twice the distance from the catheter axis to the reference dose or dose constraint points.

Single Port Access (SPA™) technique: video summary

The Single Port Access (SPA) technique offers a novel approach to minimally invasive abdominal surgery [1–2]. Using standard instrumentation, laparoscopic procedures can be performed entirely through the umbilicus in a similar fashion to standard multiport procedures. Utilizing subcutaneous flaps, very low-profile trocars, and standard instruments, we have demonstrated a platform that allows ‘‘independence of motion’’ for each of three instruments and a camera in a wide array or laparoscopic procedures, including cholecystectomy, colon resection, GE jxn procedures, hysterectomy, splenectomy, and adrenalectomy [3–6]. This technique allows the entire incision to be hidden within the umbilicus. In addition, based on standard instrumentation, the technique can be learned in a stepwise progression from multiport to Single Port Access surgery [1, 3–6]. This video demonstrates the technique as it applies to cholecystectomy.

Toxicity analysis of direct nonthermal plasma treatment of living tissue

Non-thermal dielectric barrier discharge plasma produced at normal atmospheric pressure and applied directly to living tissues is now being widely considered for various applications in medicine, viz; skin sterilization, wound treatment, treatment in malignant tissues and many others. One of the key questions that arise in this type of topical treatment is whether the skin remains undamaged after non-thermal plasma treatment. In this paper we study the possible short term and long term toxic effects of the non-thermal plasma treatment on intact living tissue. The results from the previous rodent model provided strong evidence for the ability of non-thermal plasma to sterilize the surface of the tissue without any visible or microscopic damage to the tissue. We evaluated the potential toxic effects of non-thermal plasma treatment on underlying skin cells and tissue on intact porcine skin, since it is well established that porcine (pig) skin closely resembles human skin. Based on prior knowledge that non-thermal plasma has non-damaging and damaging regimes, an experimental protocol based on the pig model was constructed. In a Yorkshire pig model, the intact skin treatment was carried out at varying doses to locate the damaging power/time (dose) combination and the resulting skin damage was analyzed. Once the dose where damage occurred was located, the treatment was stopped recording the power level and time of application. Then successively lower power levels were applied on different patches to find a dose (power/time) which was non-damaging for prolonged treatment times. The pig was kept alive for one day post treatment and the tissue samples were sectioned before euthanizing the animal. From the experiments we determined that a dose of 15 mins at a low power of 0.2 Watt/cm2 caused no visible or microscopic damage to the tissue while a dose of 3 mins at high power of 1.0 Watt/cm2 caused a second degree burn. These results were confirmed by histology staining. Of note is that sterilization is achieved in about 5 sec at a low power treatment of 0.2 Watt/cm2. Detailed analysis of any biochemical changes and inflammatory response initiation in the treated tissue will be carried out. In this paper we show that low power plasma treatment is non-toxic to intact pig skin.

[Reduced port surgery : Developing a safe pathway to single port access surgery].

ZusammenfassungDie „narbenlose“ Chirurgie ist ein wünschenswertes Ziel in der Welt der Laparoskopie und interventionellen Endoskopie. Eine Möglichkeit, dieses Ziel zu erreichen, ist der abdominelle Zugang durch eine natürliche Körperöffnung („natural orifice translumenal endoscopic surgery”, NOTES); diesem Verfahren fehlt jedoch noch eine geeignete Plattform und die Anwendung ist bisher limitiert. Weitere Möglichkeiten sind Reduced-Port-Techniken oder die „single port access surgery“, die nur minimale fasziale Defekte hinterlassen. Die Entwicklungs- und Wachstumsmöglichkeiten auf diesem Gebiet umfassen eine weites Spektrum. Allerdings muss vor einer breiten Anwendung der Verfahren gewährleistet sein, dass diese Techniken auf sichere Art und Weise sowie wirtschaftlich und ökologisch sinnvoll umgesetzt werden können. Der Beitrag gibt einen Überblick über die Verfahrensentwicklung, die Erlernbarkeit und den Einsatz der neuen Verfahren.Abstract“Scarfree” surgery is a desired goal in the world of laparoscopy and interventional endoscopy. One possibility to achieve this goal is abdominal access via a natural orifice (natural orifice transluminal endoscopic surgery, NOTES); however, this procedure and its applications lack an appropriate platform. Further possibilities are reduced port techniques or single port access surgery, which result in minimal scarring. Development and continued growth in this area cover a broad spectrum. Although acceptance has been demonstrated, the technique must be adopted in a safe and effective manner and must be economically and ecologically safe. This article gives an overview of the development of the technique, the learning curve, and new applications for this new technique. An English full-text version of this article is available at SpringerLink as supplemental.

Reduced-Port-Chirurgie

ZusammenfassungDie „narbenlose“ Chirurgie ist ein wünschenswertes Ziel in der Welt der Laparoskopie und interventionellen Endoskopie. Eine Möglichkeit, dieses Ziel zu erreichen, ist der abdominelle Zugang durch eine natürliche Körperöffnung („natural orifice translumenal endoscopic surgery”, NOTES); diesem Verfahren fehlt jedoch noch eine geeignete Plattform und die Anwendung ist bisher limitiert. Weitere Möglichkeiten sind Reduced-Port-Techniken oder die „single port access surgery“, die nur minimale fasziale Defekte hinterlassen. Die Entwicklungs- und Wachstumsmöglichkeiten auf diesem Gebiet umfassen eine weites Spektrum. Allerdings muss vor einer breiten Anwendung der Verfahren gewährleistet sein, dass diese Techniken auf sichere Art und Weise sowie wirtschaftlich und ökologisch sinnvoll umgesetzt werden können. Der Beitrag gibt einen Überblick über die Verfahrensentwicklung, die Erlernbarkeit und den Einsatz der neuen Verfahren.Abstract“Scarfree” surgery is a desired goal in the world of laparoscopy and interventional endoscopy. One possibility to achieve this goal is abdominal access via a natural orifice (natural orifice transluminal endoscopic surgery, NOTES); however, this procedure and its applications lack an appropriate platform. Further possibilities are reduced port techniques or single port access surgery, which result in minimal scarring. Development and continued growth in this area cover a broad spectrum. Although acceptance has been demonstrated, the technique must be adopted in a safe and effective manner and must be economically and ecologically safe. This article gives an overview of the development of the technique, the learning curve, and new applications for this new technique. An English full-text version of this article is available at SpringerLink as supplemental.

Toxicity of direct non-thermal atmospheric pressure plasma treatment of living tissue

Non-thermal atmospheric pressure dielectric barrier discharge plasma applied directly to living tissues is now being widely considered for various clinical applications. One of the key questions that arise in this type of topical treatment is if the skin remains undamaged after non-thermal plasma treatment.

A simple technique for fabrication of transmission block for concomitant treatment of bilateral anterior inguinal lymphatics and pelvic/perineal structures

The efficacy of transmission block technique with contiguous photon irradiation of inguinal as well as pelvic and perineal structures has been reported in literature. In this paper, a simple and accurate method for the proper fabrication of transmission block has been described and also demonstrated to be effective and useful. The procedures for a precise geometrical alignment and dose verification are also detailed.

Validity of universal wedge equation over the range of 60cobalt to 25 MV photon beam energies

PURPOSE Evaluating the validity of the universal wedge equation over the range of 60Cobalt (60CO) to 25 MV photon beam energies. METHODS AND MATERIALS The universal wedge equation relates the beam weight of the wedged field to the effective wedge angle produced by combining the wedged field to the nonwedged field and is expressed as tan (theta) = B tan (theta w), where B is the normalized weight imposed on the wedged field, theta w is the maximum wedge angle of the wedge filter, and theta is the effective wedge angle. The isodose distributions from 60Co to 25 MV photon beam energies were used. For each photon energy, the isodose distributions of wedged and nonwedged fields were combined in different proportions. The effective wedge angle was determined from each resultant isodose distribution. RESULTS The relationship between the weight of wedged field and the effective wedge angle was found to be nonlinear for wedge filters with maximum wedge angle greater than 30 degrees. The universal wedge equation predicts the effective wedge angle to within 2 degrees compared to the measured value.