Evaluation of the water-equivalent characteristics of the SP34 plastic phantom for film dosimetry in a clinical linear accelerator.

In this study, some confusing points about electron film dosimetry using white polystyrene suggested by international protocols were verified using a clinical linear accelerator (LINAC). According to international protocol recommendations, ionometric measurements and film dosimetry were performed on an SP34 slab phantom at various electron energies. Scaling factor analysis using ionometric measurements yielded a depth scaling factor of 0.

Standard follow-up after curative surgery for advanced gastric cancer: secondary analysis of a multicentre randomized clinical trial (KLASS-02).

Background: The benefit of regular follow-up after curative resection for gastric cancer is controversial as there is no evidence that it will improve survival. This study assessed whether regular follow-up leads to improved survival in patients after surgery for gastric cancer.

Methods: A secondary analysis was undertaken of patients who participated in an RCT of laparoscopic versus open distal gastrectomy for advanced gastric cancer between November 2011 and April 2015.

Consistency of dose rates after applying machine-specific reference correction factors for the gamma knife 16 mm collimator field.

Background: The machine-specific reference (msr) correction factors ( ) were introduced in International Atomic Energy Agency (IAEA) Technical Report Series 483 (TRS-483) for reference dosimetry of small fields. Several correction factor sets exist for a Leksell Gamma Knife (GK) Perfexion or Icon. Nevertheless, experiments have not rigorously validated the correction factors from different studies.

Clinical Efficacy of an Electronic Portal Imaging Device versus a Physical Phantom Tool for Patient-Specific Quality Assurance.

Pre-treatment patient-specific quality assurance (QA) is critical to prevent radiation accidents. The electronic portal imaging device (EPID) is a dose measurement tool with good resolution and a low volume-averaging effect. EPIbeam—an EPID-based portal dosimetry software—has been newly installed in three institutions in Korea.

Laparoscopic vs Open Distal Gastrectomy for Locally Advanced Gastric Cancer: 5-Year Outcomes of the KLASS-02 Randomized Clinical Trial.

Importance: The long-term safety of laparoscopic distal gastrectomy for locally advanced gastric cancer (AGC) remains uncertain given the lack of 5-year follow-up results.

Objective: To compare the 5-year follow-up results in patients with clinically AGC enrolled in the Korean Laparoendoscopic Gastrointestinal Surgery Study (KLASS)-02 randomized clinical trial who underwent laparoscopic or open distal gastrectomy.

Design, Setting, And Participants: The KLASS-02, a multicenter randomized clinical trial, showed that laparoscopic surgery was noninferior to open surgery for patients with locally AGC.

Early experience of laparoscopic resection and comparison with open surgery for gastric gastrointestinal stromal tumor: a multicenter retrospective study.

The advantages of laparoscopic resection over open surgery in the treatment of gastric gastrointestinal stromal tumor (GIST) are not conclusive. This study aimed to evaluate the postoperative and oncologic outcome of laparoscopic resection for gastric GIST, compared to open surgery. We retrospectively reviewed the prospectively collected database of 1019 patients with gastric GIST after surgical resection at 13 Korean and 2 Japanese institutions.

Effect of non-curative endoscopic submucosal dissection on short-term outcomes of subsequent surgery for early gastric cancer.

Background: With growing incidence of early gastric cancer (EGC), endoscopic submucosal dissection (ESD) is widely performed as a standard treatment for mucosal cancer. Due to the increasing application of ESD, the number of non-curative resection after ESD is also growing, leading to escalating number of patients who require additional gastrectomy with lymph node dissection after non-curative ESD. However, effects of ESD prior to surgery on technical difficulties during operation for EGC remain unclear.

Surgeon Quality Control and Standardization of D2 Lymphadenectomy for Gastric Cancer: A Prospective Multicenter Observational Study (KLASS-02-QC).

Objective: To qualify surgeons to participate in a randomized trial comparing laparoscopic and open distal D2 gastrectomy for advanced gastric cancer.

Summary Of Background Data: No studies have sought to qualify surgeons for a randomized trial comparing laparoscopic and open D2 gastrectomy for advanced gastric cancer.

Methods: We conducted a multicenter prospective observational study evaluating unedited videos of laparoscopic and open D2 gastrectomy performed by 27 surgeons.

Long-Term Outcomes of Laparoscopic Distal Gastrectomy for Locally Advanced Gastric Cancer: The KLASS-02-RCT Randomized Clinical Trial.

Purpose: It is unclear whether laparoscopic distal gastrectomy for locally advanced gastric cancer is oncologically equivalent to open distal gastrectomy. The noninferiority of laparoscopic subtotal gastrectomy with D2 lymphadenectomy for locally advanced gastric cancer compared with open surgery in terms of 3-year relapse-free survival rate was evaluated.

Patients And Methods: A phase III, open-label, randomized controlled trial was conducted for patients with histologically proven locally advanced gastric adenocarcinoma suitable for distal subtotal gastrectomy.

Nutritional and Clinical Factors Affecting Weight and Fat-Free Mass Loss after Gastrectomy in Patients with Gastric Cancer.

After a gastrectomy, the nutritional status of patients with gastric cancer has great effect on the treatment outcome and patients' quality of life. We investigated the changes in body composition and nutrient intake after gastrectomy in 288 gastric cancer patients. A multiple linear regression analysis was used for each time period to verify the effects of nutritional and clinical factors on weight and fat-free mass loss rates.

Development of a Phosphor Screen with Mirror Coating to Improve Optical Properties in Radiography.

Phosphor screens have attracted increasing global interest because they can aid the acquisition of high-quality images while simultaneously reducing exposure. However, although increasing the thickness of the phosphor screen increases exposure efficiency due to scattered light, it also leads to a broader light spread, which results in poorer resolution. Hence, in this study, we implemented a reflector using a mirror-coating technique on the surface of a phosphor screen and analyzed its characteristics in terms of luminescence intensity and resolution.

Comparison of surgical outcomes among different methods of esophagojejunostomy in laparoscopic total gastrectomy for clinical stage I proximal gastric cancer: results of a single-arm multicenter phase II clinical trial in Korea, KLASS 03.

Background: Laparoscopic distal gastrectomy for early gastric cancer has been widely accepted, but laparoscopic total gastrectomy has still not gained popularity because of technical difficulty and unsolved safety issue. We conducted a single-arm multicenter phase II clinical trial to evaluate the safety and the feasibility of laparoscopic total gastrectomy for clinical stage I proximal gastric cancer in terms of postoperative morbidity and mortality in Korea. The secondary endpoint of this trial was comparison of surgical outcomes among the groups that received different methods of esophagojejunostomy (EJ).

Operation time as a simple indicator to predict the overcoming of the learning curve in gastric cancer surgery: a multicenter cohort study.

Background: The aim of this study is to identify an indicator to predict the overcoming of the learning curve of distal gastrectomy in gastric cancer surgery.

Method: A retrospective multicenter cohort study was conducted in 2100 patients who underwent radical distal gastrectomy performed by nine surgeons in eight hospitals between 2001 and 2006. For each surgeon, an individual CUSUM chart was formulated in terms of operation time or clinical outcomes, including severe complications, number of retrieved lymph nodes, positive resection margin, and hospital stay.

Short-term Outcomes of a Multicenter Randomized Controlled Trial Comparing Laparoscopic Distal Gastrectomy With D2 Lymphadenectomy to Open Distal Gastrectomy for Locally Advanced Gastric Cancer (KLASS-02-RCT).

Objective: The aim of the study was to evaluate the short-term outcomes of KLASS-02-RCT, a multicenter randomized controlled trial comparing laparoscopic distal gastrectomy (LDG) with D2 lymphadenectomy with open distal gastrectomy (ODG).

Summary Background Data: Although several benefits of laparoscopic gastric cancer surgery have been reported, strong evidence is still limited, especially in locally advanced gastric cancer which requires extensive lymph node dissection.

Methods: Enrollment criteria included histologically confirmed cT2-4a and N0-1 gastric adenocarcinoma.

Effect of Laparoscopic Distal Gastrectomy vs Open Distal Gastrectomy on Long-term Survival Among Patients With Stage I Gastric Cancer: The KLASS-01 Randomized Clinical Trial.

Importance: Laparoscopic distal gastrectomy is gaining popularity over open distal gastrectomy for gastric cancer because of better early postoperative outcomes. However, to our knowledge, no studies have proved whether laparoscopic distal gastrectomy is oncologically equivalent to open distal gastrectomy.

Objective: To examine whether the long-term survival among patients with stage I gastric cancer undergoing laparoscopic distal gastrectomy is noninferior to that among patients undergoing open distal gastrectomy.

A feasibility study of laparoscopic total gastrectomy for clinical stage I gastric cancer: a prospective multi-center phase II clinical trial, KLASS 03.

Background: With improved short-term surgical outcomes, laparoscopic distal gastrectomy has rapidly gained popularity. However, the safety and feasibility of laparoscopic total gastrectomy (LTG) has not yet been proven due to the difficulty of the technique. This single-arm prospective multi-center study was conducted to evaluate the use of LTG for clinical stage I gastric cancer.

Safety of Laparoscopic Sentinel Basin Dissection in Patients with Gastric Cancer: an Analysis from the SENORITA Prospective Multicenter Quality Control Trial.

Purpose: We investigated complications after laparoscopic sentinel basin dissection (SBD) for patients with gastric cancer who were enrolled in a quality control study, prior to the phase III trial of sentinel lymph node navigation surgery (SNNS).

Materials And Methods: We analyzed prospective data from a Korean multicenter prerequisite quality control trial of laparoscopic SBD for gastric cancer and assessed procedure-related and surgical complications. All complications were classified according to the Clavien-Dindo Classification (CDC) system and were compared with the results of the previously published SNNS trial.

Which Factors Are Important for Successful Sentinel Node Navigation Surgery in Gastric Cancer Patients? Analysis from the SENORITA Prospective Multicenter Feasibility Quality Control Trial.

Background: We investigated the results of quality control study prior to phase III trial of sentinel lymph node navigation surgery (SNNS).

Methods: Data were reviewed from 108 patients enrolled in the feasibility study of laparoscopic sentinel basin dissection (SBD) in gastric cancer. Seven steps contain tracer injection at submucosa (step 1) and at four sites (step 2) by intraoperative esophagogastroduodenoscopy (EGD), leakage of tracer (step 3), injection within 3 minutes (step 4), identification of at least one sentinel basin (SB) (step 5), evaluation of sentinel basin nodes (SBNs) by frozen biopsy (step 6), and identification of at least five SBNs at back table and frozen sections (step 7).

Assessment of laparoscopic stomach preserving surgery with sentinel basin dissection versus standard gastrectomy with lymphadenectomy in early gastric cancer-A multicenter randomized phase III clinical trial (SENORITA trial) protocol.

Background: Along with the marked increase in early gastric cancer (EGC) in the Eastern countries, there has been an effort to adopt the sentinel node concept in EGC to preserve gastric function and reduce the occurrence of postoperative complications. Based on promising results from a previous quality control study, this prospective multicenter randomized controlled phase III clinical trial aims to elucidate the oncologic safety of laparoscopic stomach-preserving surgery with sentinel basin dissection (SBD) compared to a standard laparoscopic gastrectomy.

Methods/design: This trial is an investigator-initiated, open-label, multicenter randomized controlled phase III trial with a non-inferiority design.

A Novel Prediction Model of Prognosis After Gastrectomy for Gastric Carcinoma: Development and Validation Using Asian Databases.

Objective: The prognoses of gastric cancer patients vary greatly among countries. Meanwhile, tumor-node-metastasis (TNM) staging system shows limited accuracy in predicting patient-specific survival for gastric cancer. The objective of this study was to create a simple, yet universally applicable survival prediction model for surgically treated gastric cancer patients.