A novel approach to manage gastric adenocarcinoma

158

Abstracts / Brachytherapy 8 (2009) 105e180

Purpose: To characterize a prototype ThermoBrachytherapy Surface Applicator (TBSA - Bionix Development Corporation, Paoli, PA) intended for simultaneous heat and hihg-dose-rate (HDR) brachytherapy treatment of large area superficial tissue disease. Methods and Materials: The TBSA combines an array of brachytherapy catheters with a thin and flexible copper printed circuit board (PCB) microwave antenna array coupled to the tissue surface with a temperaturecontrolled conformal water bolus. An early design TBSA was dosimetrically evaluated by Taschereau et al., 2004. Based on some of their findings, a 15 x 15 cm2 commercial prototype was fabricated and subjected to dosimetric evaluation on an elliptical tissue phantom. The configuration consisted of: elliptical phantom, 12 mm water bolus, 1 mm PCB, another 4 mm to center of catheter, and a 30 mm thick air-filled bladder to apply inward pressure over the entire assembly. Plans were generated to deliver 100 cGy to lesions at a depths varying from 5 to 15 mm from skin. The dwell times were optimized using the volume optimization tool in BrachyVision (VarianMedical Systems, Inc., Palo Alto, CA. Dose-volume metrics like V100, V140, V150, homogeneity index (HI 5 V100-V(150)), and skin overdose (OD 5 (Dskin eDPTV)x100%/DPTV) were calculated for each plan (1). The influence of brachytherapy catheter spacing (10 mm vs. 20 mm) on dose homogeneity was investigated. A plan was generated with 20 mm catheter spacing for a target depth of 10 mm and delivered to the elliptical phantom using a GammaMed 12i afterloader (Varian). Skin dose was measured at four locations using OneDoseÔ dosimeters (Sicel Technologies, Inc., Morrisville, NC) and compared with the calculated dose from BrachyVision. The dosimetric impact of the thin copper PCB heating array was also assessed with ion chamber and OneDoseÔ dosimetry. Results: Only results for lesions extending to 10 mm from skin are included here, with a bolus thickness of 12 mm, resulting in an overall 28 mm source to target distance in this particular configuration. With 19 brachytherapy catheters spaced 1o mm apart, the tumor coverage was V100 5 99%, the homogeneity index 97 %, and skin overdose 5 31%, with a total treatment time based on a 10 Ci source of 420 sec. With 10 brachytherapy catheters spaced 2o mm apart, the tumor coverage was V100 5 97%, the homogeneity index 93.5 %, and skin overdose 5 30%, with a total treatment time of 422 sec. The latter case was delivered on the elliptical phantom and the average skin dose measured at four different locations was 125  2 cGy, compared to 124.9  1.8 cGy calculated by the treatment planning system. The PCB attenuation coefficient was measured as 3  0.001% using ion chamber and 2.95  0.03 % when OneDoseÔ dosimeters were used. Conclusions: The prescribed dose can be delivered to lesions of varying depths ranging from 5 to 15 mm from skin, while maintaining an acceptable skin dose. Excellent agreement was obtained between the skin dose calculated using the TPS and measured with OneDoseÔ dosimeters. The copper PCB does not significantly attenuate the beam. Catheter spacing can be increased from 10 mm to 20 mm without significant loss of coverage or homogeneity index. Further evaluation of the impact of the chest wall geometry on dosimetric parameters of the TBSA will be studied in the context of an IRB approved volunteer study. Supported by NCI grant R44 CA104061 and Bionix Development Corporation.

PO54 The importance of internal, endoscopically placed fiducials and three dimensional treatment planning in esophageal brachytherapy Shlomo A. Koyfman, M.D.1 John A. Dumot, M.D.,2 Matthew D. Kolar, M.S.,1 Douglas A. Wilkinson, Ph.D.,1 Justin J. Juliano, M.D.1 1Radiation Oncology, Cleveland Clinic Taussig Cancer Institute, Cleveland, OH; 2 Gastroenterology and Hepatology, Cleveland Clinic Digestive Disease Institute, Cleveland, OH. Purpose: Esophageal brachytherapy is an important tool in the management of esophageal cancer. The efficacy and safety of this procedure relies on the ability to accurately identify the target region, while minimizing the amount of normal esophagus that is irradiated. Available literature, as well as current

ABS guidelines, provides little detail as to how to reliably delineate the target area and exclude normal esophagus from unnecessary dose. At our institution, we have historically used external radio-opaque fiducials (EF) placed under endoscopic guidance to identify the area of interest, and fluoroscopic based, two dimensional (2D) planning. We have recently begun to incorporate the use of implanted internal fiducials (IF) along with three dimensional (3D) planning, in addition to our standard approach. Herein, we describe our techniques and compare these two approaches. Methods and Materials: Patients were initially evaluated endoscopically whereby the superior and inferior borders of the target were identified. Under fluoroscopic guidance, a radio-opaque marker (i.e. paper clip) was taped onto the chest directly overlying the tip of the endoscope at both the superior and inferior borders of the target. Internal metallic clips (Olympus hemoclips) were then implanted at these same borders. A NucletronÔ esophageal brachytherapy catheter was then inserted and secured. Both fluoroscopic and CT simulations were performed with dummy sources in place. CT images were then transferred to the Nucletron PlatoÔ brachytherapy planning system for subsequent treatment planning. The inter-fiducial distance between each respective pair of IF and EF were measured on the CT for each fraction. The distance between the superior IF and EF, as well as the inferior IF and EF were also recorded. Two active lengths (AL) were determined for each fraction; one based on the EF as projected on the fluoroscopic simulation film representing our standard technique, and one based on a 3D target volume rendering from contours drawn on the CT simulation images using the IF as superior and inferior borders. Results: The above-mentioned procedures were accomplished in three patients, who underwent a total of seven esophageal brachytherapy treatments. The mean distance between IF was 38.6 mm (26-45), whereas the mean distance between the EF was 50.3 mm (30-62). The mean distance between the superior IF and EF in each fraction was 9.4 mm (022), whereas the mean distance between the inferior IF and EF was 10.3 mm (0-26). The mean change in AL between 2D planning with EF, and 3D planning with IF was 15 mm (0-25). In one patient, the AL was identical for both 2D and 3D planning, although in one fraction there was a ‘‘frameshift’’ error in which both EF were placed 10 mm superior to their corresponding IF. In all cases where discrepancies between IF and EF were observed, the IF with 3D planning led to a smaller target area and a shorter AL than EF with 2D planning. Conclusions: There is marked variability in the delineation of the target region and the determination of AL between the use of EF and 2D planning, as compared to the use of IF and 3D planning. In this study, treating based on the use of EF and 2D planning in some circumstances would have resulted in geographical misses and treating excessive normal esophagus, thereby placing the patient at higher risk for treatment related complications. Accordingly, the use of IF along with 3D based planning should be standard in esophageal brachytherapy.

PO55 A novel approach to manage gastric adenocarcinoma Sanaz Hariri,1 Mahmood Reza Aghamiri,1 Siamak Najarian.,2 Ramin Jaberi,3 Mehrdad Azmi,3 Hamid Reza Dehghan,4 Siamak Hajizadeh.2 1 Shahid Beheshti University, Tehran, Iran; 2Amirkabir University of Technology, Tehran, Iran; 3Institute of Cancer, Imam Khomeini Hospital, Tehran, Iran; 4Iran University of Medical Sciences, Tehran, Iran. Purpose: Although incidence of gastric cancer decreased over the past decade in the USA, it is still the second most common cause of cancer related death in women and the first one in men in Iran and many other Asian countries. Despite progress in diagnosis and treatment, gastric caner has still poor prognosis (five-year survival less than 20%). In this paper, we suggest an endoscopic guided brachytherapy method for managing unresectable advanced gastric cancer; whether as a treatment or neoadjuvant radiotherapy to make it resectable. This procedure was done by a new high-dose-rate (HDR) brachytherapy applicator. The advantage of this method in comparison with the previous study, which was accomplished by a Chinese group, is the noninvasive nature of it and a temporary type brachytherapy implementation.

Oral Presentations / Brachytherapy 8 (2009) 105e180 192

Methods and Materials: An HDR afterloader machine using Ir source for brachytherapy purpose was used. Adding some tubes around an ordinary gastroscope, made the passage of brachytherapy applicators possible. Also, a novel applicator was developed. The main component of the applicator was an endoscope brush wire with a needle at the tip of it. The needle was mounted in order to allow insertion to the desired depth of tumor. Since the applicator was not a common and tested one, some dosimetry tests were done as well. The dosimetry tests were done by means of a well type chamber and some pieces of GAFCHROMICÔ EBT films. The well type chamber provided us a relative result in comparison with standard interstitial applicators, while the films were used for an absolute dosimetry as a function of distance from the applicator surface. In addition, the insertion procedure of the needles and the applicators, via the endoscope, was evaluated in a gastric simulator phantom. Results: Treatment planning of the determined CTV and two OARs (spinal cord and aorta) in the phantom showed 93.6% coverage of CTV while 90% of spinal cord and aorta got about one third of the prescribed dose. The chamber showed a reading between two proprietary applicators that was acceptable. Also, the film experiments on proposed applicator showed correlation coefficient of 99.15% with a standard interstitial applicator which was used in the treatment planning system. Conclusions: This study aimed to ensure the feasibility of a new treatment method for gastric adenocarcinoma using a new applicator. Considering the promising results, not only the procedure is feasible, but also the experiments showed a good agreement between the suggested and the standard applicators. Therefore, it can be used as a new HDR applicator after introducing the correction factors to the treatment planning systems. Although the results were acceptable, clinical trials are inevitable to examine the efficacy of this new treatment modality.

PO56 High-dose-rate brachyhterapy as a boost for carcinoma of the oral tongue Ahmed M. Akl, M.D.,1 Mohamad Elazizi, D.D.S.,1 Raof Mikhail, M.D.,2 Naser Ahmad, M.D.,2 Khaled Shukairy, M.D.2, Steven Marchetta, D.O.,3 Ashraf Heram, D.D.S.1 1Raduiation Oncology, Genesys Hurley Cancer Institute, Flint, MI; 2Hurely Medical Center, Flint, MI; 3ENT, Genesys Medical Center, Grand Blanc, MI. Purpose: To evaluate the outcome of patients with the diagnosis of invasive carcinoma of the oral tongue treated with external beam radiation and highdose-rate (HDR) brachytherapy as a boost. Methods and Materials: Charts from Genesys Hurley Cancer Institute of patients with the diagnosis of invasive carcinoma of the oral tongue treated with external beam radiation and high-dose-rate (HDR) brachytherapy between March 2002 and December 2005 were reviewed (9 patients with squamous cell carcinoma and 1 patient with adenoid cystic carcinoma). There was 1 patient with T1N0M0 and 9 patients with T2N0M0. The patient with T1 was treated with HDR brachytherapy as monotherapy (8 treatments each delivered 50 Gy to the tumor plus at least 2.5 cm margin). Patients with T2N0M0 received external beam radiation to the neck nodes to a total dose of 46 Gy in 23 treatments, or 50.4 Gy in 28 treatments were delivered to the primary and neck nodes. The technique used was parallel right and left lateral to the upper neck nodes and direct anterior to the lower neck nodes. Catheters were inserted in the operating room after patients were prepared with nasal intubation for general anesthesia and neck hyperextended. Needles were inserted through the submental and submandibular area through the floor of the mouth to the upper surface of the tongue. Subsequently, a guide wire was inserted in the needles at the upper surface of the tongue and the needles were pulled from the submental and submandibular area to allow the plastic tube insertion into the tongue. These tubes with a blind end and fixed to a button which were located at the upper surface of the tongue to prevent escape of the tubes. Patients subsequently were admitted to the hospital, then transferred to the Radiation Oncology Department and underwent CT treatment planning and computer-aided dosimetry to ensure adequate coverage of the target volume which would include the

159

tumor volume prior to external beam radiation and at least 2.5 cm margin. Patients received HDR treatment twice per day. Dose was given 4 Gy per fraction twice per day for 4-6 fractions depending on the tumor size and the response. The 1 patient with adenoid cystic carcinoma received 4 Gy per fraction for 6 treatments. Results: All patients had complete response. The median followup was 32.7 months (ranging from 8-84 months). Patients with T1 lesions had no evidence of disease at 50 months. One patient with T2, a 19-year-old male, relapsed locally at 12 months post radiation and salvaged with radical surgery to include subtotal glossectomy and hemimandibulectomy. The patient relapsed again locally and expired six months post surgery. Two patients expired with no evidence of disease at 8 and 14 months post radiation treatment. Remaining patients are alive with no evidence of disease at 24, 24, 25, 26, 50, 60 and 84 months. All patients were followed up regularly. All patients developed pain in the tongue post implant for approximately three months post treatment, except for two patients where the pain persisted with 1 patient one year and the other patient 1-1/2 years. All patients regained their taste completely within 4-6 months post treatment. One patient developed infection post implant and was placed on antibiotics for approximately 1 month. All patients tongue function is completely normal with no limitation of movement. Conclusions: High-dose-rate brachytherapy is an effective primary therapy for T1 squamous cell carcinoma of the tongue and as a boost post external beam for T2N0 squamous cell carcinoma of the tongue.

PO57 Comparison of outcomes of lung cancer patients treated with surgical resection with 125I lung brachytherapy vs stereotactic hypofractionated radiation therapy for single lung lesions Bhupesh Parashar, A. Gabriella Wernicke, M.D., Albert Sabbas, Ph.D., Samuel Trichter, Dattatreyudu Nori, M.D.Radiation Oncology, Weill Cornell Medical Center, New York, NY. Purpose: A single lung cancer lesion can be treated with surgical resection (lobectomy or wedge resection) with or without the addition of 125I radiation seeds. Alternatively, inoperable patients may be treated with hypofractionated stereotactic radiation therapy (SRT). The purpose of this study is to evaluate and compare the outcomes of patients with single lung cancer lesions treated at our institute with either surgery plus 125I radiation seeds or SRT. Methods and Materials: We did a retrospective chart review of 150 patients treated at our institution between 1999 and 2008. Of those, 39 patients were found to be eligible for the study. Eighteen patients received a surgical resection and an intraoperative 125I implant (surgery group) for 18 lesions and 20 patients received hypofractionated stereotactic radiation therapy (SRT) to 21 lesions. The study subjects were evaluated for local recurrence (LR) and development of distant metastasis (DM). Chi square test was employed to estimate LR and DM in both cohorts. Results: The median age of patients was 65.5 years (range 36-79 years) and 78 years (range 60-90 years) in surgery and SRT group respectively. In the surgery group there were 16/18 (88.8%) patients with non-small cell lung cancer, 1/18 (5.5%) with small cell carcinoma and 1/18 (5.5%) with high grade sarcoma. In the same group, 5/18 (27.7%) patients underwent lobectomy, 1/18 (5.5%) had a local excision of a mediastinal sarcoma, and 9/18 (50%) underwent a wedge resection. The median number of 125I seeds placed was 21 (range 10-46).The median tumor size was 2.3 cm (range 1.2-6 cm). The median activity of the seeds was 0.529 mCi (range 0.390-0.700 mCi). The median followup was 7 months (range 1-84 months). In the SRT group, 18/20 (90%) patients were non-small cell and 2/20 (10%) patients were metastatic carcinoma, 1 from an endometrial and 1 from parotid adenocarcinoma. The median tumor size in the SRT group was 1.7 cm (range 0.3-4.8 cm) and median followup was 14.5 months (Range 3-72 months). SRT dose to 13/21 (61.9%) lesions was 30 Gy in 3 fractions, 4/21 (19%) lesions was 40 Gy in 4 fractions, 1/21 (4.7%) lesions was 50 Gy in 5 fractions and 3/21 (14.2%) patients was 60 Gy in 4 fractions. The local control in the surgery group was 88.8% vs. 100% in the SRT group (p 5 0.117). Distant failure as the first site of