The Results of Radiation Therapy as Definitive, Postoperative, and Salvage Therapy for Meningioma / 이화의대지

OBJECTIVES: Radiation therapy has multiple roles in the treatment of meningioma although surgery remains the primary treatment of choice. In this retrospective study, we report the results of radiation therapy for meningioma as definitive, postoperative or salvage therapies. METHODS: Seventeen patients diagnosed with meningioma were treated with radiation therapy in our institute from May 2000 to October 2009. Radiation therapies were performed as definitive therapies in 8 patients, as postoperative therapies in 5 and as salvage therapies in 4. Nine patients received stereotactic radiosurgery (SRS), 2 patients fractionated stereotactic radiotherapy (FSRT), and 5 patients 3-dimensional conformal radiotherapy (3DCRT). Radiation dose were 12 to 20 Gy for SRS, 36 Gy in 9 fractions for FSRT and 50.4 Gy in 28 fractions for 3DCRT. Follow-up imaging study of computed tomography or magnetic resonance imaging was performed at 6 to 12 months intervals and neurologic exam was performed with an interval less than 6 months. RESULTS: The median follow-up duration was 38 months (range, 12 to 85 months). Tumor progression after radiation therapy developed in one patient. The reduction of tumor volume measured on follow-up images were more than 20% in 4 patients and minimal change of tumor volume less than 20% were observed in 12 patients. Peritumoral edema developed in 4 patients and disappeared without any treatment. One patient had radiation necrosis. CONCLUSION: Our experience is consistent with the current understanding that radiotherapy is as an effective and safe treatment modality for meningiomas when the tumor cannot be resected completely or when recurred after surgery.

Development of Ultrasound Phantom for Volume Calibration / 의학물리

The purpose of this study was to design and construct an ultrasound phantom for volume calibration and evaluate the volume measurement accuracy of a 2 dimensional ultrasonic system. Ultrasound phantom was designed, constructed and tested. The phantom consisted of a background material and a target. The background was made by mixing agarose gel with water. A target, made with an elastic material, was filled with water to vary its volume and shape and inserted into background material. To evaluate accuracy of a 2 dimensional ultrasonic system (128XP, ACUSON), three different shapes of targets (a sphere, 2 ellipsoids and a triangular prism) were constructed. In case of ellipsoid shape, two targets, one with same size length and width (ellipsoid 1) and another with the length 2 times longer than width (ellipsoid 2) were examined. The target volumes of each shape were varied from 94cc to 450cc and measurement accuracy was examined. The volume difference between the real and measured target of the sphere shape ranged between 6.7 and 11%. For the ellipsoid targets, the differences ranged from 9.2 to 10.5% with ellipsoid 1 and 25.7% with ellipsoid 2. The volume difference of the triangular prism target ranged between 20.8 and 35%. An easy and simple method of constructing an ultrasound phantom was introduced and it was possible to check the volume measurement accuracy of an ultrasound system.

Effectiveness of Bellyboard Device for Displacement of Small Bowel in Pelvic Irradiation / 의학물리

Various techniques were evaluated to determine the best method for reducing small bowel involvement in pelvic irradiation. Fourteen patients receiving radiation in pelvic area were enrolled for this study. Five sets of small bowel images were obtained. Patients were positioned on a simulation couch with full bladder in prone and supine positions and 2 sets of images were taken. Then they were asked to empty their bladder and 2 sets of images were taken in prone and supine positions. A belly board device (BBD) was placed and one set of images was obtained. Using a software, the area of small bowel inside treatment field was contoured, measured, and analyzed. In both full and empty bladder cases, small bowel area reduction was observed in prone position as compared to supine position. Especially statistically significant reduction is noted in lateral film. An average decreases of 13% in PA and 26% in lateral direction were noted with bladder distention as compared to empty bladder. With the use of BBD for empty bladder, a significant reduction of 62.8+/-27.1% and 63.1+/-32.9% in PA and lateral directions were observed as compared to without BBD in prone position, respectively. In conclusion, the best sparing of small bowel concerning the area included in the treatment fields was achieved with BBD in prone position with empty bladder. However, further reduction is expected if the bladder was filled fully because the analysed data with empty vs full bladder study shows increased sparing of small bowel with distended bladder.

Preliminary Results of Concurrent Chemotherapy and Radiation Therapy using High-dose-rate Brachytherapy for Cervical Cancer / 대한방사선종양학회지

PURPOSE: To determine the efficacy and safety of concurrent chemotherapy and radiation therapy with high-dose-rate brachytherapy for cervical cancer. MATERIALS AND METHODS: From January 2001 to December 2002, 30 patients with cervical cancer were treated with concurrent chemotherapy (cisplatin and 5-FU) and definitive radiation therapy. The median age was 58 (range 34~74) year old. The pathology of the biopsy sections was squamous cell carcinoma in 29 patients and one was adenocarcinoma. The distribution to FIGO staging system was as follows: stage IB, 7 (23%); IIA, 3 (10%); IIB, 12 (40%); IIIA, 3 (10%); IIIB, 5 (17%). All patients received pelvic external beam irradiation (EBRT) to a total dose of 45~50.4 Gy (median: 50.4 Gy) over 5~5.5 weeks. Ir-192 HDR intracavitary brachytherapy (ICBT) was given after a total dose of 41.4 Gy. HDR-ICBT was performed twice a week, with a fraction point A dose of 4 Gy and median dose to point A was 28 Gy (range: 16~32 Gy) in 7 fractions. The median cumulative biologic effective dose (BED) at point A (EBRT+ICBT) was 88 Gy10 (range: 77~94 Gy10). The median cumulative BED at ICRU 38 reference point (EBRT+ICBT) was 131 Gy3 (range: 122~140 Gy3) at point A, 109 Gy3 (range: 88~125 Gy3) at the rectum and 111 Gy3 (range: 91~123 Gy3) at the urinary bladder. Cisplatin (60 mg/m2) and 5-FU (1,000 mg/m2) was administered intravenously at 3 weeks interval from the first day of radiation for median 5 (range: 2~6) cycles. The assessment was performed at 1 month after completion of radiation therapy by clinical examination and CT scan. The median follow-up time was 36 months (range: 8~50 months). RESULTS: The complete response rate after concurrent chemoradiation therapy was 93.3%. The 3-yr actuarial pelvic control rate was 87% and 3-yr actuarial overall survival and disease-free survival rate was 93% and 87%, respectively. The local failure rate was 13% and distant metastatic rate was 3.3%. The crude rate of minor hematologic complications (RTOG grade 1-2) occurred in 3 patients (10%) and one patient had suffered from severe leukopenia (RTOG grade 4) during concurrent treatment. Acute minor enterocolitis (RTOG grade 1-2) occurred in 11 patients (37%) and one patient (3%) was suffered from colon perforation during radiation therapy. Late colitis of RTOG grade 1 occurred in 5 patients (15%). Acute cystitis of RTOG grade 1 occurred in 12 patients (40%) and late cystitis of RTOG grade 2 occurred in one patient (3%). No treatment related death was seen. CONCLUSION: The results of this study suggest that the concurrent chemoradiation therapy with HDR brachytherapy could be accepted as an effective and safe treatment for cervical cancer.

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.