ABSTRACT: The Strut-Adjusted Volume Implant (SAVI; Cianna Medical, Aliso Viejo, CA) is a multichannel single-entry brachytherapy device designed to allow dose modulation to minimize normal tissue dose while simultaneously maximizing target coverage. This is the first report on the initial 102 patients with nearly 2 years of median follow-up.
One hundred two patients were treated at two institutions. Data were collected on eligibility and dosimetry and followed for toxicity and recurrence.
The median follow-up is 21 months. Overall dosimetry is outstanding (median percent of target volume receiving 90% of the prescription dose was 95.9%, volume of target receiving 150% of the prescription dose was 27.8 mL, and volume of target receiving 200% of the prescription dose was 14.0 cm(3)). No devices were pulled prior to treatment completion. For patients with a skin bridge of less than 7 mm, the maximum median skin dose was 280 cGy (median percent of target volume receiving 90% of the prescription dose was 95.2%, volume of target receiving 150% of the prescription dose was 25.8 cm(3) and volume of target receiving 200% of the prescription dose was 12.7 mL). For patients with both chest wall and skin of less than 7 mm, the maximum median lung dose was 205 cGy with simultaneous skin dose of 272 cGy. The rate of telangiectasia was 1.9%. Grade 1 hyperpigmentation developed in 10 patients (9.8%) and Grade 2 fibrosis in 2 patients (1.9%). There were 2 symptomatic seromas and 2 cases of asymptomatic fat necrosis (1.9%). Of the patients, 27% were not eligible for MammoSite balloon brachytherapy (Hologic, Inc., Marlborough, MA) and 5% were not eligible for any balloon brachytherapy. The recurrence rate was 1%.
The SAVI appears to safely allow an increase in eligibility for APBI over balloon brachytherapy or three-dimensional conformal radiation, highlighting the outstanding device flexibility to maximize the target dose and minimize the normal tissue dose. The device was well tolerated by patients.
International journal of radiation oncology, biology, physics 07/2011; 80(3):765-70. · 4.59 Impact Factor
ABSTRACT: To assess the degree of intra- and inter-fraction cervical motion throughout a course of intensity modulated radiation therapy (IMRT) for cervical cancer patients.
A retrospective study of 10 women with stage 1B1-3B cervical cancer diagnosed from September 2007 to July 2008 was conducted. All patients were treated with chemoradiation using IMRT followed by intracavitary brachytherapy. Pretreatment, patients had 2 seeds placed at a depth of 10mm into the cervix. On-Board Imaging (OBI) was used to obtain anterior/posterior (AP) and lateral X-rays before and after each treatment. OBI images were rigidly aligned to baseline digitally reconstructed radiographs (DRRs), and movement of cervical seeds was determined in the lateral, vertical, and AP directions. Mean differences in cervical seed position and standard error of the mean (SEM) were calculated.
A total of 922 images were reviewed, with approximately 90 images per patient. The mean intra-fractional movement in cervical seed position in the lateral, vertical, and AP directions were 1.6mm (SD±2.0), 2.6mm (SD±2.4), and 2.9mm (SD±2.7), respectively, with a range from 0 to 15mm for each direction. The mean inter-fractional movement in the lateral, vertical, and AP directions were 1.9mm (SD±1.9), 4.1mm (SD±3.2), and 4.2mm (SD±3.5), respectively, with a range from 0 to 18mm for each direction.
This is the first study to assess intra- and inter-fractional movement of the cervix using daily imaging before and after each fraction. Within and between radiation treatments, cervical motion averages approximately 3mm in any given direction. However, maximal movement of the cervix can be as far as 18mm from baseline. This wide range of motion needs to be accounted for when generating planning treatment volumes.
Radiotherapy and Oncology 01/2011; 98(3):347-51. · 5.58 Impact Factor
ABSTRACT: To evaluate the differences between target and normal tissue delineation between magnetic resonance imaging (MRI) and computed tomography (CT) in cervical cancer patients and to explore the differences in dosimetry after brachytherapy planning.
High-dose-rate brachytherapy was performed on 11 patients. Planning CT and MRI were performed with tandem and ring in place. The radiation oncologist contoured the rectum, the bladder, the sigmoid, and the high-risk clinical target volume (HR-CTV) on CT and MRI. The values compared between CT and MRI included D90 and D100 to HR-CTV; coronal, sagittal, and axial measurements of HR-CTV; and minimum dose to most irradiated 0.1-, 0.5-, 1.0-, and 2.0-cm volumes for the organs at risk (OAR). Doses were converted to the equivalent dose in 2 Gy by applying the linear quadratic model. Volume optimization was also performed, and the above parameters were evaluated.
Magnetic resonance imaging showed a significantly greater HR-CTV length in the sagittal plane (P = 0.006), with CT showing a greater length in the coronal plane (P = 0.004). The equivalent dose in 2 Gy to 2.0 cm for the bladder was greater on CT than MRI (P = 0.041). The remainder of the dose volume histogram values for the OAR were similar between CT and MRI. With volume optimization, no significant differences were seen between HR-CTV dose parameters or doses to OAR.
The CT- and MRI-based brachytherapy tissue delineation seems adequate for evaluation of OAR and target tissues, although the shapes of HR-CTV and OAR do differ. When adopting volume-based prescription, these differences may lead to altered target dosing. The clinical impact of these differences seems to be small and may demonstrate that planning with CT, if combined with one MRI, may be sufficient.
International Journal of Gynecological Cancer 01/2010; 20(1):47-53. · 1.65 Impact Factor