Person: Cormack, Robert
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Cormack
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Robert
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Cormack, Robert
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Publication Variability in MRI vs. ultrasound measures of prostate volume and its impact on treatment recommendations for favorable-risk prostate cancer patients: a case series(BioMed Central, 2014) Murciano-Goroff, Yonina; Wolfsberger, Luciant D; Parekh, Arti; Fennessy, Fiona; Tuncali, Kemal; Orio, Peter; Niedermayr, Thomas R; Suh, W Warren; Devlin, Phillip; Tempany, Clare Mary C; Sugar, Emily H Neubauer; O’Farrell, Desmond A; Steele, Graeme; O’Leary, Michael; Buzurovic, Ivan; Damato, Antonio L.; Cormack, Robert; Fedorov, Andriy; Nguyen, PaulBackground: Prostate volume can affect whether patients qualify for brachytherapy (desired size ≥20 mL and ≤60 mL) and/or active surveillance (desired PSA density ≤0.15 for very low risk disease). This study examines variability in prostate volume measurements depending on imaging modality used (ultrasound versus MRI) and volume calculation technique (contouring versus ellipsoid) and quantifies the impact of this variability on treatment recommendations for men with favorable-risk prostate cancer. Methods: We examined 70 patients who presented consecutively for consideration of brachytherapy for favorable-risk prostate cancer who had volume estimates by three methods: contoured axial ultrasound slices, ultrasound ellipsoid (height × width × length × 0.523) calculation, and endorectal coil MRI (erMRI) ellipsoid calculation. Results: Average gland size by the contoured ultrasound, ellipsoid ultrasound, and erMRI methods were 33.99, 37.16, and 39.62 mLs, respectively. All pairwise comparisons between methods were statistically significant (all p < 0.015). Of the 66 patients who volumetrically qualified for brachytherapy on ellipsoid ultrasound measures, 22 (33.33%) did not qualify on ellipsoid erMRI or contoured ultrasound measures. 38 patients (54.28%) had PSA density ≤0.15 ng/dl as calculated using ellipsoid ultrasound volumes, compared to 34 (48.57%) and 38 patients (54.28%) using contoured ultrasound and ellipsoid erMRI volumes, respectively. Conclusions: The ultrasound ellipsoid and erMRI ellipsoid methods appeared to overestimate ultrasound contoured volume by an average of 9.34% and 16.57% respectively. 33.33% of those who qualified for brachytherapy based on ellipsoid ultrasound volume would be disqualified based on ultrasound contoured and/or erMRI ellipsoid volume. As treatment recommendations increasingly rely on estimates of prostate size, clinicians must consider method of volume estimation.Publication Near-infrared fluorescence imaging platform for quantifying in vivo nanoparticle diffusion from drug loaded implants(Dove Medical Press, 2016) Markovic, Stacey; Belz, Jodi; Kumar, Rajiv; Cormack, Robert; Sridhar, Srinivas; Niedre, MarkDrug loaded implants are a new, versatile technology platform to deliver a localized payload of drugs for various disease models. One example is the implantable nanoplatform for chemo-radiation therapy where inert brachytherapy spacers are replaced by spacers doped with nanoparticles (NPs) loaded with chemotherapeutics and placed directly at the disease site for long-term localized drug delivery. However, it is difficult to directly validate and optimize the diffusion of these doped NPs in in vivo systems. To better study this drug release and diffusion, we developed a custom macroscopic fluorescence imaging system to visualize and quantify fluorescent NP diffusion from spacers in vivo. To validate the platform, we studied the release of free fluorophores, and 30 nm and 200 nm NPs conjugated with the same fluorophores as a model drug, in agar gel phantoms in vitro and in mice in vivo. Our data verified that the diffusion volume was NP size-dependent in all cases. Our near-infrared imaging system provides a method by which NP diffusion from implantable nanoplatform for chemo-radiation therapy spacers can be systematically optimized (eg, particle size or charge) thereby improving treatment efficacy of the platform.Publication Clinical implementation of a novel applicator in high-dose-rate brachytherapy treatment of esophageal cancer(Termedia Publishing House, 2016) Buzurovic, Ivan; Hansen, Jorgen Lindberg; Bhagwat, Mandar; O'Farrell, Desmond; Friesen, Scott; Harris, Thomas C.; Damato, Antonio L.; Cormack, Robert; Martin, Neil; Devlin, PhillipPurpose In this study, we present the clinical implementation of a novel transoral balloon centering esophageal applicator (BCEA) and the initial clinical experience in high-dose-rate (HDR) brachytherapy treatment of esophageal cancer, using this applicator. Material and methods Acceptance testing and commissioning of the BCEA were performed prior to clinical use. Full performance testing was conducted including measurements of the dimensions and the catheter diameter, evaluation of the inflatable balloon consistency, visibility of the radio-opaque markers, congruence of the markers, absolute and relative accuracy of the HDR source in the applicator using the radiochromic film and source position simulator, visibility and digitization of the applicator on the computed tomography (CT) images under the clinical conditions, and reproducibility of the offset. Clinical placement of the applicator, treatment planning, treatment delivery, and patient's response to the treatment were elaborated as well. Results: The experiments showed sub-millimeter accuracy in the source positioning with distal position at 1270 mm. The digitization (catheter reconstruction) was uncomplicated due to the good visibility of markers. The treatment planning resulted in a favorable dose distribution. This finding was pronounced for the treatment of the curvy anatomy of the lesion due to the improved repeatability and consistency of the delivered fractional dose to the patient, since the radioactive source was placed centrally within the lumen with respect to the clinical target due to the five inflatable balloons. Conclusions: The consistency of the BCEA positioning resulted in the possibility to deliver optimized non-uniform dose along the catheter, which resulted in an increase of the dose to the cancerous tissue and lower doses to healthy tissue. A larger number of patients and long-term follow-up will be required to investigate if the delivered optimized treatment can lead to improved clinical outcomes.Publication Dose Volume Histogram Analysis of Normal Structures Associated with Accelerated Partial Breast Irradiation Delivered by High Dose Rate Brachytherapy and Comparison with Whole Breast External Beam Radiotherapy Fields(BioMed Central, 2008) Stewart, Alexandra J; O'Farrell, Desmond A; Cormack, Robert; Hansen, Jorgen Lindberg; Khan, Atif J.; Mutyala, Subhakar; Devlin, PhillipPurpose: To assess the radiation dose delivered to the heart and ipsilateral lung during accelerated partial breast brachytherapy using a MammoSite™ applicator and compare to those produced by whole breast external beam radiotherapy (WBRT). Materials and methods: Dosimetric analysis was conducted on patients receiving MammoSite breast brachytherapy following conservative surgery for invasive ductal carcinoma. Cardiac dose was evaluated for patients with left breast tumors with a CT scan encompassing the entire heart. Lung dose was evaluated for patients in whom the entire lung was scanned. The prescription dose of 3400 cGy was 1 cm from the balloon surface. MammoSite dosimetry was compared to simulated WBRT fields with and without radiobiological correction for the effects of dose and fractionation. Dose parameters such as the volume of the structure receiving 10 Gy or more (V10) and the dose received by 20 cc of the structure (D20), were calculated as well as the maximum and mean doses received. Results: Fifteen patients were studied, five had complete lung data and six had left-sided tumors with complete cardiac data. Ipsilateral lung volumes ranged from 925–1380 cc. Cardiac volumes ranged from 337–551 cc. MammoSite resulted in a significantly lower percentage lung V30 and lung and cardiac V20 than the WBRT fields, with and without radiobiological correction. Conclusion: This study gives low values for incidental radiation received by the heart and ipsilateral lung using the MammoSite applicator. The volume of heart and lung irradiated to clinically significant levels was significantly lower with the MammoSite applicator than using simulated WBRT fields of the same CT data sets. Trial registration: Dana Farber Trial Registry number 03-179Publication Effect of dental restorations and prostheses on radiotherapy dose distribution: a Monte Carlo study(John Wiley and Sons Inc., 2009) Chin, David W. H.; Treister, Nathaniel; Friedland, Bernard; Cormack, Robert; Tishler, Roy; Makrigiorgos, Gerassimos; Court, Laurence E.Dental restorations, fixed prosthodontics, and implants affect dose distribution in head and neck radiation therapy due to the high atomic number of the materials utilized. The backscatter of electrons from metallic materials due to the impinging treatment x‐ray results in localized dose enhancements. These dose enhancements cause localized mucositis in patients who have dental work, a significant clinical complication. We investigated the backscatter effect of 23 configurations of dental work using the EGS4nrc Monte Carlo (MC) simulation system. We found that all‐metal fixed partial dentures caused the highest amount of dose enhancement – up to 33% – while amalgam restorations did not cause a significant amount. Restorations with a ceramic veneer caused up to 8% enhancement. Between 3 mm and 5 mm of water‐equivalent material almost completely absorbed the backscatter. MC simulations provide an accurate estimate of backscatter dose, and may provide patient‐specific estimates in future.