A region growing method for tumor volume segmentation on PET images for rectal and anal cancer patients.

The application of automated segmentation methods for tumor delineation on 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) images presents an opportunity to reduce the interobserver variability in radiotherapy (RT) treatment planning. In this work, three segmentation methods were evaluated and compared for rectal and anal cancer patients: (i) Percentage of the maximum standardized uptake value (SUV% max), (ii) fixed SUV cutoff of 2.5 (SUV2.5), and (iii) mathematical technique based on a confidence connected region growing (CCRG) method. A phantom study was performed to determine the SUV% max threshold value and found to be 43%, SUV43% max. The CCRG method is an iterative scheme that relies on the use of statistics from a specified region in the tumor. The scheme is initialized by a subregion of pixels surrounding the maximum intensity pixel. The mean and standard deviation of this region are measured and the pixels connected to the region are included or not based on the criterion that they are greater than a value derived from the mean and standard deviation. The mean and standard deviation of this new region are then measured and the process repeats. FDG-PET-CT imaging studies for 18 patients who received RT were used to evaluate the segmentation methods. A PET avid (PETavid) region was manually segmented for each patient and the volume was then used to compare the calculated volumes along with the absolute mean difference and range for all methods. For the SUV43% max method, the volumes were always smaller than the PETavid volume by a mean of 56% and a range of 21%-79%. The volumes from the SUV2.5 method were either smaller or larger than the PETavid volume by a mean of 37% and a range of 2%-130%. The CCRG approach provided the best results with a mean difference of 9% and a range of 1%-27%. Results show that the CCRG technique can be used in the segmentation of tumor volumes on FDG-PET images, thus providing treatment planners with a clinically viable starting point for tumor delineation and minimizing the interobserver variability in radiotherapy planning.

Mature follow-up for high-risk stage I non-small-cell lung carcinoma treated with sublobar resection and intraoperative iodine-125 brachytherapy.

PURPOSE: To update the Allegheny General Hospital experience of high-risk Stage I non-small-cell lung cancer patients treated with sublobar resection and intraoperative (125)I Vicryl mesh brachytherapy. METHODS AND MATERIALS: Between January 5, 1996 and February 19, 2008, 145 patients with Stage I non-small-cell lung cancer who were not lobectomy candidates because of cardiopulmonary compromise underwent sublobar resection and placement of (125)I seeds along the resection line. The (125)I seeds embedded in Vicryl suture were attached with surgical clips to a sheet of Vicryl mesh, inserted over the target area, and prescribed to a 0.5-cm planar margin. RESULTS: The mean target area, total activity, number of seeds implanted, and prescribed total dose was 33.3 cm(2) (range, 18.0-100.8), 20.2 mCi (range, 11.1-29.7), 46 (range, 30-100), and 117 Gy (range, 80-180), respectively. The median length of the surgical stay was 6 days (range, 1-111), with a perioperative mortality rate of 3.4%. At a median follow-up of 38.3 months (range, 1-133), 6 patients had developed local recurrence (4.1%), 9 had developed regional failure (6.2%), and 25 had distant failure (17.2%). On multivariate analysis, no patient- or tumor-specific factors or surgical or dosimetric factors were predictive of local recurrence. The overall median survival was 30.5 months with a 3- and 5-year overall survival rate of 65% and 35%, respectively. CONCLUSION: (125)I brachytherapy for high-risk, Stage I non-small-cell lung cancer after sublobar resection is well tolerated and associated with a low local failure rate.

Comparison of conservative management techniques in the re-treatment of ipsilateral breast tumor recurrence.

PURPOSE: To compare brachytherapy and three-dimensional (3-D) conformal external beam radiotherapy for breast cancer presenting in the previously irradiated breast. METHODS AND MATERIALS: Thirty-six patients with TIS-T2 breast carcinomas received brachytherapy or 3-D conformal radiotherapy (3-D CRT) after lumpectomy in a previously irradiated breast as an alternative to salvage mastectomy. Brachytherapy consisted of low-dose-rate (LDR) interstitial technique in 21 patients, whereas 11 patients were treated using high-dose-rate (HDR) balloon technique. Four patients received 3-D CRT. Cosmesis was graded according to the Harvard criteria and the Allegheny General Modification of the Harvard criteria. Acute sequelae were graded according to the Common Terminology Criteria for Adverse Events (version 3.0). RESULTS: Thirty-five of 36 patients remained free of local failure, with a mean followup of 37 months. Five patients treated with LDR developed Grade II and two developed Grade III acute side effects. No patient treated with balloon brachytherapy or 3-D CRT developed a Grade II or higher acute effect. Cosmetically, 12 LDR interstitial patients were scored as Grade I, six as Grade II, and three as Grade III. Nine of the HDR patients were scored as Grade I, one as Grade II, and one as Grade III. Two 3-D CRT patients were scored as Grade II and two as Grade III. The Allegheny Modification of the Harvard criteria more accurately reflected the cosmetic effects of re-treatment. CONCLUSION: Brachytherapy is feasible for patients who desire breast preservation in a previously irradiated breast. All techniques demonstrated similar local control rates. Acute side effects were less, and cosmesis was superior in HDR balloon brachytherapy.