Dummy Run of Quality Assurance Program before Prospective Study of Hippocampus-Sparing Whole-Brain Radiotherapy and Simultaneous Integrated Boost for Multiple Brain Metastases from Non-small Cell Lung Cancer: Korean Radiation Oncology Group (KROG) 17-06 Study / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Lung Cancer Subcommittee of Korean Radiation Oncology Group (KROG) has recently launched a prospective clinical trial (KROG 17-06) of hippocampus-sparing whole brain radiotherapy (HS-WBRT) with simultaneous integrated boost (SIB) in treating multiple brain metastases from non-small cell lung cancer. In order to improve trial quality, dummy run studies among the participating institutions were designed. This work reported the results of two-step dummy run procedures of the KROG 17-06 study. MATERIALS AND METHODS: Two steps tested hippocampus contouring variability and radiation therapy planning compliance. In the first step, the variation of the hippocampus delineation was investigated for two representative cases using the Dice similarity coefficients. In the second step, the participating institutions were requested to generate a HS-WBRT with SIB treatment plan for another representative case. The compliance of the treatment plans to the planning protocol was evaluated. RESULTS: In the first step, the median Dice similarity coefficients of the hippocampus contours for two other dummy run cases changed from 0.669 (range, 0.073 to 0.712) to 0.690 (range, 0.522 to 0.750) and from 0.291 (range, 0.219 to 0.522) to 0.412 (range, 0.264 to 0.598) after providing the hippocampus contouring feedback. In the second step, with providing additional plan priority and extended dose constraints to the target volumes and normal structures, we observed the improved compliance of the treatment plans to the planning protocol. CONCLUSION: The dummy run studies demonstrated the notable inter-institutional variability in delineating the hippocampus and treatment plan generation, which could be decreased through feedback from the trial center.

Analysis of the Movement of Surgical Clips Implanted in Tumor Bed during Normal Breathing for Breast Cancer Patients / 대한방사선종양학회지

PURPOSE: To evaluate the movement of surgical clips implanted in breast tumor bed during normal breathing. MATERIALS AND METHODS: Seven patients receiving breast post-operative radiotherapy were selected for this study. Each patient was simulated in a common treatment position. Fluoroscopic images were recorded every 0.033 s, 30 frames per 1 second, for 10 seconds in anterior to posterior (AP), lateral, and tangential direction except one patient's images which were recorded as a rate of 15 frames per second. The movement of surgical clips was recorded and measured, thereby calculated maximal displacement of each clip in AP, lateral, tangential, and superior to inferior (SI) direction. For the comparison, we also measured the movement of diaphragm in SI direction. RESULTS: From AP direction's images, average movement of surgical clips in lateral and SI direction was 0.8+/-0.5 mm and 0.9+/-0.2 mm and maximal movement was 1.9 mm and 1.2 mm. Surgical clips in lateral direction's images were averagely moved 1.3+/-0.7 mm and 1.3+/-0.5 mm in AP and SI direction with 2.6 mm and 2.6 mm maximal movement in each direction. In tangential direction's images, average movement of surgical clips and maximal movement was 1.2+/-0.5 mm and 2.4 mm in tangential direction and 0.9+/-0.4 mm and 1.7 mm in SI direction. Diaphragm was averagely moved 14.0+/-2.4 mm and 18.8 mm maximally in SI direction. CONCLUSION: The movement of clips caused by breathing was not as significant as the movement of diaphragm. And all surgical clip movements were within 3 mm in all directions. These results suggest that for breast radiotherapy, it may not necessary to use breath-holding technique or devices to control breath.

Evaluation of Electron Boost Fields based on Surgical Clips and Operative Scars in Definitive Breast Irradiation / 대한방사선종양학회지

PURPOSE: To evaluate the role of surgical clips and scars in determining electron boost field for early stage breast cancer undergoing conserving surgery and postoperative radiotherapy and to provide an optimal method in drawing the boost field. MATERIALS AND METHODS: Twenty patients who had 4~7 surgical clips in the excision cavity were selected for this study. The depth informations were obtained to determine electron energy by measuring the distance from the skin to chest wall (SCD) and to the clip implanted in the most posterior area of tumor bed. Three different electron fields were outlined on a simulation film. The radiological tumor bed was determined by connecting all the clips implanted during surgery. Clinical field (CF) was drawn by adding 3 cm margin around surgical scar. Surgical field (SF) was drawn by adding 2 cm margin around surgical clips and an ideal field (IF) was outlined by adding 2 cm margin around both scar and clips. These fields were digitized into our planning system to measure the area of each separate field. The areas of the three different electron boost fields were compared. Finally, surgical clips were contoured on axial CT images and dose volume histogram was plotted to investigate 3-dimensional coverage of the clips. RESULTS: The average depth difference between SCD and the maximal clip location was 0.7+/-0.56 cm. Greater difference of 5 mm or more was seen in 12 patients. The average shift between the borders of scar and clips were 1.7, 1.2, 1.2, and 0.9 cm in superior, inferior, medial, and lateral directions, respectively. The area of the CF was larger than SF and IF in 6/20 patients. In 15/20 patients, the area difference between SF and IF was less than 5%. One to three clips were seen outside the CF in 15/20 patients. In addition, dosimetrically inadequate coverage of clips (less than 80% of prescribed dose) were observed in 17/20 patients when CF was used as the boost field. CONCLUSION: The electron field determined from clinical scar underestimates the tumor bed in superior-inferior direction significantly and thereby underdosing the tissue at risk. The electron field obtained from surgical clips alone dose not cover the entire scar properly. As a consequence, our technique, which combines the surgical clips and clinical scars in determining electron boost field, was proved to be effective in minimizing the geographical miss as well as normal tissue complications.