Mark J Rivard

University of Massachusetts Boston, Boston, Massachusetts, United States

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Publications (254)640.33 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Second primary malignancies (SPMs) are among the most serious late adverse effects after radiotherapy experienced over time by the increasing population of cancer survivors worldwide. The study aim was to determine the rate and distribution of SPMs for neutron- and photon-emitting brachytherapy (BT) sources for patients treated for cervical cancer. The cohort comprised 662 patients with invasive cervical cancer (Stages IIB and IIIB) and contributed 5,224 patient-years (PY) of observation. These patients were treated by radiotherapy during the 1989-1999 year period with cobalt-60 source ((60)Co) teletherapy. The first group of patients (N = 375; 3,154 PY) received high-dose-rate (HDR) californium-252 source ((252)Cf) BT, whereas the second group (N = 287; 2,070 PY) received HDR (60)Co BT. Over a 25-year period, 35 SPMs were observed, amounting to 5.3% of all observed patients: in 16 (2.4%) heavily, 2 (0.3%) moderately, 14 (2.1%) lightly irradiated body sites, and 3 (0.5%) other sites. Of these, 21 cases (5.6%) were observed in the HDR (252)Cf BT group, whereas 14 cases (4.9%) were observed in the HDR (60)Co BT group. Exposures received during (60)Co teletherapy and HDR BT with either (252)Cf or (60)Co had statistically equivalent (p = 0.68) effects on SPM development. Cure rates are improving, and therefore, there are more long-term survivors from cervical cancer. This study shows no significant difference in rates or distribution of SPMs in women treated with neutron BT compared with photon BT (p = 0.68). After reviewing related literature and our research results, it is evident that a detailed investigation of SPM frequency, localization, and dose to adjacent organs is a suitable topic for further research. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
    Brachytherapy 07/2015; DOI:10.1016/j.brachy.2015.06.006 · 2.76 Impact Factor
  • Brachytherapy 06/2015; 14. DOI:10.1016/j.brachy.2015.02.215 · 2.76 Impact Factor
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    ABSTRACT: Previously, generic HDR (192)Ir source and shielded applicator were designed by WG- MBDCA, the AAPM-ESTRO-ABG Working Group on model-based dose calculation algorithms. TPS vendors have incorporated both into their TPS. A charge of WG-MBDCA is to develop a limited number of well-defined test cases and perform MBDCA dose calculations and comparisons. Here, we describe the test cases proposed, the 3D dosimetric data generation process and the 3D gamma analysis performed. A voxelized phantom of 512×512×512 voxels (HU=-1024,Air), with each voxel being 1×1×1 mm(3), containing a concentric cubic contour structure (HU=0,Water) of dimension 201×201×201 voxels, was created in the DICOM- RT format. Three configurations were tested: i) source located at the center with surrounding structure assigned to water to mimic TG-43 conditions, ii) source displaced +7 cm along the x axis, iii) source located at the center with the shielded applicator in place. Advanced Collapsed-cone Engine (ACE, Elekta) and AcurosBV (Varian) were benchmarked. Reference datasets were independently produced by different groups using BrachyDose (10(10) photons), GEANT4(4×10(10)), Penelope (2×10(10)), MCNP5(2 x10(10)), MCNP6(10(11)), and ALGEBRA(4×10(10)) Monte Carlo (MC) dose calculation platforms. For the three configurations, MC agreed within 1% for the volume bounded by the 1% isodose surface; MCNP6 data sets were designated as reference (statistical error < 0.2% across the phantom). A 2%/1mm 3D γ- index criteria was used, within the volume bounded by 5% isodose surface, to account for both dose difference and source placement errors in TPS. Voxel pass rates were 95.2%, 99.5% and 90% for ACE and 98%, 98.4% and 95.9% for AcurosBV, respectively. The evaluated test cases are suitable for MBDCA QA. DICOM-RT files are being integrated into the joint AAPM/IROC Houston registry to support end-user TPS software commissioning.
    Medical Physics 06/2015; 42(6):3707. DOI:10.1118/1.4926145 · 2.64 Impact Factor
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    ABSTRACT: To describe a new infrastructure and process that will enable end-users to commission model-based dose calculation (MBDC) software for brachytherapy planning, and to invite end-users to participate in the beta testing phase of this process. The AAPM working groups on model-based dose calculation algorithms in brachytherapy (WGDCAB) and brachytherapy source registry (WGBSR) collaboratively implemented the basic MBDC software commissioning workflow described in the AAPM+ESTRO TG-186 report. For a small number of initial test cases virtual CT image, anatomical structure set, treatment plan, and associated 3D dose data for a single dwell position occupied by a WGDCAB generic high-dose-rate Ir-192 virtual source, with or without a generic shielded applicator, were generated. Dose distributions were calculated using Monte Carlo (MC) code MCNP6, Elekta's Advanced Collapsed cone Algorithm (ACE™), and Varian's Acuros™ BV module. All data were saved in DICOM RT format and uploaded to a provisional, web-accessible repository in the joint AAPM-IROC Houston brachytherapy source registry. It is envisioned that end-users will download data for a test case from the repository, verify its correctness, calculate 3D dose locally, and then compare with MCNP6 and MBDC doses obtained from the repository using TPS-based comparison tools. User guides in preparation for each TPS will facilitate the process. Initial evaluations of DICOM data download, TPS import, MBDC dose calculation, and reference dose comparison indicate that the infrastructure and process described above are both viable and practicable. Ancillary data including generic source and shielded applicator specifications, CAD drawings, and MC code definitions are also available in the repository. With further refinement and beta-test input from end-users, a practical MBDC software commissioning process for brachytherapy can be established. A procedure for adding new test cases submitted by end-users to the repository will be put in place by WGDCAB.
    Medical Physics 06/2015; 42(6):3708. DOI:10.1118/1.4926148 · 2.64 Impact Factor
  • Prakash Aryal · Janelle A. Molloy · Mark J. Rivard
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    ABSTRACT: Scitation is the online home of leading journals and conference proceedings from AIP Publishing and AIP Member Societies
    Medical Physics 06/2015; 42(6):3085-3088. DOI:10.1118/1.4919619 · 2.64 Impact Factor
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    ABSTRACT: In this project, the possibility of utilizing the BEBIG 60Co HDR system for AccuBoostTM treatment has been evaluated. Dose distributions in various breast sizes have been calculated for both Co-60 and Ir-192 sources using the MCNP5 code. These calculations were performed in breast tissues with thicknesses of 4cm, 6cm, and 8cm. The initial calculations were performed with the same applicator dimensions as the existing applicators used with the HDR Ir-192 system. The activity of the Co-60 source was selected such that the dose at the breast center was the same as the values from 192Ir. Then, the applicator thicknesses were increased to twice of those used with HDR Ir-192 system, for reducing skin and chest doses by Co-60 system. Dose to breast skin and chest wall were compared for both applicators types, with and without inclusion of a focusing cone at the applicator center. The results showed that loading HDR Co-60 source inside the thin applicators impose higher doses to breast skin and chest wall compared to the 192Ir source. The area of the chest wall covered by 10Gy when treated by Co-60 with the thin and thick applicators, or treated by Ir-192 with thin applicator are 79cm2, 39cm2, and 3.8cm2, respectively. These values are reduced to 34cm2, 0cm2, and 0cm2 by using the focusing cone. It is worth noting that the breast skin areas covered by the 60Gy isodose line are 9.9cm2 and 7.8cm2 for Co-60 with the thin and thick applicators, respectively, while it is 20cm2 for Ir-192 when no focusing cone is present. These values are 0cm2, 0cm2, and 11cm2 in the presence of the focusing cone. The results indicate that using Co-60 with the thicker applicators is beneficial because of the higher half-life of Co-60, and the reduced maximum skin dose when compared with Ir-192.
    Medical Physics 06/2015; 42(6):3421. DOI:10.1118/1.4924741 · 2.64 Impact Factor
  • Jessica R. Hiatt · Stephen D. Davis · Mark J. Rivard
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    ABSTRACT: Purpose: The model S700 Axxent electronic brachytherapy source by Xoft, Inc., was characterized by Rivard et al. in 2006. Since then, the source design was modified to include a new insert at the source tip. Current study objectives were to establish an accurate source model for simulation purposes, dosimetrically characterize the new source and obtain its TG-43 brachytherapy dosimetry parameters, and determine dose differences between the original simulation model and the current model S700 source design.
    Medical Physics 06/2015; 42(6):2764-2776. DOI:10.1118/1.4919280 · 2.64 Impact Factor
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    ABSTRACT: The purpose of this multi-institutional study was to compare two new gamma stereotactic radiosurgery (GSRS) dosimetry protocols to existing calibration methods. The ultimate goal was to guide AAPM Task Group 178 in recommending a standard GSRS dosimetry protocol. Nine centers (ten GSRS units) participated in the study. Each institution made eight sets of dose rate measurements: six with two different ionization chambers in three different 160mm-diameter spherical phantoms (ABS plastic, Solid Water and liquid water), and two using the same ionization chambers with a custom in-air positioning jig. Absolute dose rates were calculated using a newly proposed formalism by the IAEA working group for small and non-standard radiation fields and with a new air-kerma based protocol. The new IAEA protocol requires an in-water ionization chamber calibration and uses previously reported Monte-Carlo generated factors to account for the material composition of the phantom, the type of ionization chamber, and the unique GSRS beam configuration. Results obtained with the new dose calibration protocols were compared to dose rates determined by the AAPM TG-21 and TG-51 protocols, with TG-21 considered as the standard. Averaged over all institutions, ionization chambers and phantoms, the mean dose rate determined with the new IAEA protocol relative to that determined with TG-21 in the ABS phantom was 1.000 with a standard deviation of 0.008. For TG-51, the average ratio was 0.991 with a standard deviation of 0.013, and for the new in-air formalism it was 1.008 with a standard deviation of 0.012. Average results with both of the new protocols agreed with TG-21 to within one standard deviation. TG-51, which does not take into account the unique GSRS beam configuration or phantom material, was not expected to perform as well as the new protocols. The new IAEA protocol showed remarkably good agreement with TG-21. Conflict of Interests: Paula Petti, Josef Novotny, Gennady Neyman and Steve Goetsch are consultants for Elekta Instrument A/B; Elekta Instrument AB, PTW Freiburg GmbH, Standard Imaging, Inc., and The Phantom Laboratory, Inc. loaned equipment for use in these experiments; The University of Wisconsin Accredited Dosimetry Calibration Laboratory provided calibration services.
    Medical Physics 06/2015; 42(6):3627. DOI:10.1118/1.4925739 · 2.64 Impact Factor
  • M J Rivard
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    ABSTRACT: A flexible polymer membrane (CivaSheet) has been developed by CivaTech Oncology, Inc. (Research Triangle Park, NC) for permanent brachytherapy. Distributed throughout the array are small plastic disks containing Pd-103 and gold foil shielding on one side to provide a directional dose distribution and facilitate imaging. This study evaluated dosimetry for the CivaSheet. Manufacturer-provided dimensional and compositional information for the device were compared to physical samples for validation of design information, then entered into the MCNP6 radiation transport code for dosimetry simulations. Three device sizes (6×6, 6×12, or 6×18 disk-arrays) were simulated as the membrane can be custom-sized preceding surgical placement. Dose to water was estimated with 0.01 cm resolution from the surface to 10 cm on both sides of the device. Because this is a novel device with calibration methods under development, results were normalized using DVHs to provide 90% prescription coverage to a plane positioned 0.5 cm from the front surfaces. This same normalization was used for creating isodose distributions. Planar dose distributions of flat CivaSheets were relatively homogeneous with acceptable dose uniformity variations. Differences in the results between the differently sized CivaSheets were not significant. At 0.5 mm, 87% of the target volume was within the therapeutic dose range. Dose hotspots on the CivaSheet forward surfaces were directly above the disks. However, dose hotspots on the rear-facing surfaces were positioned between the disks. Doses in contact with the front surface were similar to those observed for currently available brachytherapy sources. Maximum doses that occurred on the rear surface were approximately 55 times lower than the dose on the front surface. Monte Carlo calculations validated the directional capabilities and advantageous dosimetry of the new Pd-103 brachytherapy device. It appears feasible to re-size the CivaSheet in the operating room with an acceptable variation in prescription dose. Research was supported by CivaTech Oncology, Inc.
    Medical Physics 06/2015; 42(6):3534. DOI:10.1118/1.4925217 · 2.64 Impact Factor
  • P Aryal · JA Molloy · M J Rivard
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    ABSTRACT: To investigate the effect of plaque design and radionuclides on eye plaque dosimetry. The Monte Carlo N-particle Code version 6 (MCNP6) was used for radiation transport simulations. The 14 mm and 16 mm diameter COMS plaques and the model EP917 plaque were simulated using brachytherapy seeds containing I-125, Pd-103, and Cs-131 radionuclides. The origin was placed at the scleral inner surface. The central axis (CAX) doses of both COMS plaques at -1 mm, 0 mm, 1 mm, 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, and 22.6 mm were compared to the model EP917 plaque. Dose volume histograms (DVHs) were also created for both COMS plaques for the tumor and outer sclera then compared to results for the model EP917 plaque. For all radionuclides, the EP917 plaque delivered higher dose (max 343%) compared to the COMS plaques, except for the 14 mm COMS plaque with Cs-131 at 1 mm and 2 mm depths from outer sclera surface. This could be due to source design. For all radionuclides, the 14 mm COMS plaque delivered higher doses compared to the 16 mm COMS plaque for the depths up to 5 mm. Dose differences were not significant beyond depths of 10 mm due to ocular lateral scatter for the different plaque designs. Tumor DVHs for the 16 mm COMS plaque with Cs-131 provided better dose homogeneity and conformity compared to other COMS plaques with I-125 and Pd-103. Using Pd-103, DVHs for the 16 mm COMS plaque delivered less dose to outer sclera compared to other plaques. This study identified improved tumor homogeneity upon considering radionuclides and plaque designs, and found that scleral dose with the model EP917 plaque was higher than for the 16 mm COMS plaque for all the radionuclides studied.
    Medical Physics 06/2015; 42(6):3334. DOI:10.1118/1.4924376 · 2.64 Impact Factor
  • Source
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    ABSTRACT: Purpose: In order to facilitate a smooth transition for brachytherapy dose calculations from the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) formalism to model-based dose calculation algorithms (MBDCAs), treatment planning systems (TPSs) using a MBDCA require a set of well-defined test case plans characterized by Monte Carlo (MC) methods. This also permits direct dose comparison to TG-43 reference data. Such test case plans should be made available for use in the software commissioning process performed by clinical end users. To this end, a hypothetical, generic high-dose rate (HDR) 192 Ir source and a virtual water phantom were designed, which can be imported into a TPS.
    Medical Physics 06/2015; 42(6):3048-3062. DOI:10.1118/1.4921020 · 2.64 Impact Factor
  • Yun Yang · Mark J. Rivard
    Brachytherapy 05/2015; 14:S68. DOI:10.1016/j.brachy.2015.02.314 · 2.76 Impact Factor
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    ABSTRACT: Noninvasive image-guided breast brachytherapy (NIBB) is an attractive novel approach to deliver accelerated partial breast irradiation (APBI). Calculations of equivalent uniform dose (EUD) were performed to identify the appropriate APBI dose for this technique. APBI plans were developed for 15 patients: five with three-dimensional conformal APBI (3D-CRT), five with multi-lumen intracavitary balloons (m-IBB), and five simulating NIBB treatment. Prescription doses of 34.0 and 38.5 Gy were delivered in 10 fractions for m-IBB and 3D-CRT, respectively. Prescription doses ranging from 34.0 to 38.5 Gy were considered for NIBB. Dose-volume histogram data from all 3D-CRT, m-IBB, and NIBB plans were used to calculate the biologically effective EUD and corresponding EUD to the PTV_eval using the following equation: EUD = EUBED/(n [1 + EUD/α/β]). An α/β value of 4.6 Gy was assumed for breast tumor. EUD for varying NIBB prescription doses were compared with EUD values for the other APBI techniques. Mean PTV_eval volume was largest for 3D-CRT (372.9 cm(3)) and was similar for NIBB and m-IBB (88.7 and 87.2 cm(3), respectively). The EUD value obtained by prescribing 38.5 Gy with 3D-CRT APBI was 38.6 Gy. The EUD value of 34.0 Gy prescribed with m-IBB was 34.4 Gy. EUD values for NIBB ranged from 33.9 to 38.2 Gy for prescription doses ranging from 34.0 to 38.5 Gy. Using EUD calculations to compare APBI techniques and treatment doses, a prescription dose of 36.0 Gy in 10 fractions using NIBB has a comparable biologic equivalent dose to other established brachytherapy techniques. Copyright © 2015 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.
    Brachytherapy 04/2015; 14(4). DOI:10.1016/j.brachy.2015.03.007 · 2.76 Impact Factor
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    ABSTRACT: To assess the radiation dose to the fetus of a pregnant patient undergoing high-dose-rate (HDR) (192)Ir interstitial breast brachytherapy, and to design a new patient setup and lead shielding technique that minimizes the fetal dose. Radiochromic films were placed between the slices of an anthropomorphic phantom modeling the patient. The pregnant woman was seated in a chair with the breast over a table and inside a leaded box. Dose variation as a function of distance from the implant volume as well as dose homogeneity within a representative slice of the fetal position was evaluated without and with shielding. With shielding, the peripheral dose after a complete treatment ranged from 50 cGy at 5 cm from the caudal edge of the breast to <0.1 cGy at 30 cm. The shielding reduces absorbed dose by a factor of two near the breast and more than an order of magnitude beyond 20 cm. The dose is heterogeneous within a given axial plane, with variations from the central region within 50%. Interstitial HDR (192)Ir brachytherapy with breast shielding can be more advantageous than external-beam radiotherapy (EBRT) from a radiation protection point of view, as long as the distance to the uterine fundus is higher than about 10 cm. Furthermore, the weight of the shielding here proposed is notably lower than that needed in EBRT. Shielded breast brachytherapy may benefit pregnant patients needing localized radiotherapy, especially during the early gestational ages when the fetus is more sensitive to ionizing radiation. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
    Physica Medica 02/2015; 31(3). DOI:10.1016/j.ejmp.2015.01.010 · 2.40 Impact Factor
  • Source
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    ABSTRACT: Purpose: Noninvasive image-guided breast brachytherapy delivers conformal HDR Ir-192 brachytherapy treatments with the breast compressed, and treated in the cranial-caudal and medial-lateral directions. This technique subjects breast tissue to extreme deformations not observed for other disease sites. Given that, commercially-available software for deformable image registration cannot accurately co-register image sets obtained in these two states, a finite element analysis based on a biomechanical model was developed to deform dose distributions for each compression circumstance for dose summation.
    Journal of Contemporary Brachytherapy 02/2015; 7(1):55-71. DOI:10.5114/jcb.2015.49355 · 1.28 Impact Factor
  • Radiotherapy and Oncology 12/2014; 111:S329-S330. DOI:10.1016/S0167-8140(15)32039-9 · 4.36 Impact Factor
  • Source
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    ABSTRACT: In the last decade, there have been significant developments into integration of robots and automation tools with brachytherapy delivery systems. These systems aim to improve the current paradigm by executing higher precision and accuracy in seed placement, improving calculation of optimal seed locations, minimizing surgical trauma, and reducing radiation exposure to medical staff. Most of the applications of this technology have been in the implantation of seeds in patients with early-stage prostate cancer. Nevertheless, the techniques apply to any clinical site where interstitial brachytherapy is appropriate. In consideration of the rapid developments in this area, the American Association of Physicists in Medicine (AAPM) commissioned Task Group 192 to review the state-of-the-art in the field of robotic interstitial brachytherapy. This is a joint Task Group with the Groupe Européen de Curiethérapie-European Society for Radiotherapy & Oncology (GEC-ESTRO). All developed and reported robotic brachytherapy systems were reviewed. Commissioning and quality assurance procedures for the safe and consistent use of these systems are also provided. Manual seed placement techniques with a rigid template have an estimated in vivo accuracy of 3–6 mm. In addition to the placement accuracy, factors such as tissue deformation, needle deviation, and edema may result in a delivered dose distribution that differs from the preimplant or intraoperative plan. However, real-time needle tracking and seed identification for dynamic updating of dosimetry may improve the quality of seed implantation. The AAPM and GEC-ESTRO recommend that robotic systems should demonstrate a spatial accuracy of seed placement ≤1.0 mm in a phantom. This recommendation is based on the current performance of existing robotic brachytherapy systems and propagation of uncertainties. During clinical commissioning, tests should be conducted to ensure that this level of accuracy is achieved. These tests should mimic the real operating procedure as closely as possible. Additional recommendations on robotic brachytherapy systems include display of the operational state; capability of manual override; documented policies for independent check and data verification; intuitive interface displaying the implantation plan and visualization of needle positions and seed locations relative to the target anatomy; needle insertion in a sequential order; robot–clinician and robot–patient interactions robustness, reliability, and safety while delivering the correct dose at the correct site for the correct patient; avoidance of excessive force on radioactive sources; delivery confirmation of the required number or position of seeds; incorporation of a collision avoidance system; system cleaning, decontamination, and sterilization procedures. These recommendations are applicable to end users and manufacturers of robotic brachytherapy systems.
    Medical Physics 10/2014; 41(10):101501. DOI:10.1118/1.4895013 · 2.64 Impact Factor
  • International journal of radiation oncology, biology, physics 09/2014; 90(1):S305-S306. DOI:10.1016/j.ijrobp.2014.05.1022 · 4.26 Impact Factor
  • Prakash Aryal · Janelle A Molloy · Mark J Rivard
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    ABSTRACT: Purpose: To investigate the influence of slot design on dose distributions and dose-volume histograms (DVHs) for the model EP917 plaque for episcleral brachytherapy. Methods: Dimensions and orientations of the slots were measured for three model EP917 plaques and compared to data in the Plaque Simulator (PS) treatment planning software (version 5.7.6). These independently determined coordinates were incorporated into the MCNP Monte Carlo simulation environment to obtain dose from the plaques in a water environment and in a clinical environment with ocular structures. A tumor volume was simulated as 5 mm in apical height and 11 mm in basal diameter. Variations in plaque mass density and composition; slot length, width, and depth; seed positioning; and Ag-marker rod positioning were simulated to examine their influence on plaque central axis (CAX) and planar dose distributions, and DVHs. Results: Seed shifts in a single slot toward the eye and shifts of the(125)I-coated Ag rod within the capsule had the greatest impact on CAX dose distribution. A shift of 0.0994 mm toward the eye increased dose by 14%, 9%, 4.3%, and 2.7% at 1, 2, 5, and 10 mm, respectively, from the inner sclera. When examining the fully-modeled plaque in the ocular geometry, the largest dose variations were caused by shifting the Ag rods toward the sclera and shifting the seeds away from the globe when the slots were made 0.51 mm deeper, causing +34.3% and -69.4% dose changes to the outer sclera, respectively. At points along the CAX, dose from the full plaque geometry using the measured slot design was 2.4%±1.1% higher than the manufacturer-provided slot design and 2.2%±2.3% higher than the homogeneous calculation of PS treatment planning results. The ratio of D10 values for the measured slot design to the D10 values for the manufacturer-provided slot design was higher by 9%, 10%, and 19% for the tumor, inner sclera, and outer sclera, respectively. In comparison to the measured slot design, a theoretical plaque having narrower and deeper slots delivered 30%, 37%, and 62% lower D10 doses to the tumor, inner sclera, and outer sclera, respectively. Conclusions: While the measured positions of the slots on the model EP917 plaque were in close agreement (<0.7 mm) with the PS values, small differences in the slot shape caused substantial differences in dose distributions and DVH metrics. Increasing slot depth by 0.1 mm decreased outer scleral dose by 20%, yet shifting the Ag rods in the seeds toward the globe by 0.1 mm increased outer scleral dose by 35%. The clinical medical physicist is advised to measure these types of plaques upon acceptance testing before clinical use to inspect slot shape and position for comparison with data used for treatment planning purposes.
    Medical Physics 09/2014; 41(9):092102. DOI:10.1118/1.4892603 · 2.64 Impact Factor
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    ABSTRACT: Purpose To measure the 2D dose distributions with submillimeter resolution for 131Cs (model CS-1 Rev2) and 125I (model 6711) seeds in a Solid Water phantom using radiochromic EBT film for radial distances from 0.06 cm to 5 cm. To determine the TG-43 dosimetry parameters in water by applying Solid Water to liquid water correction factors generated from Monte Carlo simulations. Methods Each film piece was positioned horizontally above and in close contact with a 131Cs or 125I seed oriented horizontally in a machined groove at the center of a Solid Water phantom, one film at a time. A total of 74 and 50 films were exposed to the 131Cs and 125I seeds, respectively. Different film sizes were utilized to gather data in different distance ranges. The exposure time varied according to the seed air-kerma strength and film size in order to deliver doses in the range covered by the film calibration curve. Small films were exposed for shorter times to assess the near field, while larger films were exposed for longer times in order to assess the far field. For calibration, films were exposed to either 40 kV (M40) or 50 kV (M50) x-rays in air at 100.0 cm SSD with doses ranging from 0.2 Gy to 40 Gy. All experimental, calibration and background films were scanned at a 0.02 cm pixel resolution using a CCD camera-based microdensitometer with a green light source. Data acquisition and scanner uniformity correction were achieved with Microd3 software. Data analysis was performed using ImageJ, FV, IDL and Excel software packages. 2D dose distributions were based on the calibration curve established for 50 kV x-rays. The Solid Water to liquid water medium correction was calculated using the MCNP5 Monte Carlo code. Subsequently, the TG-43 dosimetry parameters in liquid water medium were determined. Results Values for the dose-rate constants using EBT film were 1.069±0.036 and 0.923±0.031 cGy U−1 h−1 for 131Cs and 125I seed, respectively. The corresponding values determined using the Monte Carlo method were 1.053±0.014 and 0.924±0.016 cGy U−1 h−1 for 131Cs and 125I seed, respectively. The radial dose functions obtained with EBT film measurements and Monte Carlo simulations were plotted for radial distances up to 5 cm, and agreed within the uncertainty of the two methods. The 2D anisotropy functions obtained with both methods also agreed within their uncertainties. Conclusion EBT film dosimetry in a Solid Water phantom is a viable method for measuring 131Cs (model CS-1 Rev2) and 125I (model 6711) brachytherapy seed dose distributions with submillimeter resolution. With the Solid Water to liquid water correction factors generated from Monte Carlo simulations, the measured TG-43 dosimetry parameters in liquid water for these two seed models were found to be in good agreement with those in the literature.
    Applied Radiation and Isotopes 09/2014; 92:102–114. DOI:10.1016/j.apradiso.2014.06.014 · 1.23 Impact Factor

Publication Stats

3k Citations
640.33 Total Impact Points


  • 2008–2015
    • University of Massachusetts Boston
      Boston, Massachusetts, United States
  • 2002–2015
    • Tufts University
      • Department of Radiation Oncology
      Бостон, Georgia, United States
  • 1999–2013
    • Tufts Medical Center
      • • Department of Radiation Oncology
      • • Department of Neurosurgery
      Boston, Massachusetts, United States
    • Harper University Hospital
      Detroit, Michigan, United States
    • New England Baptist Hospital
      Boston, Massachusetts, United States
  • 2012
    • East Carolina University
      North Carolina, United States
    • University Hospital Essen
      Essen, North Rhine-Westphalia, Germany
  • 2011
    • University of Wisconsin–Madison
      Madison, Wisconsin, United States
  • 2010
    • Beverly Hospital, Boston MA
      Beverly, Massachusetts, United States
  • 2006
    • Catholic University of Louvain
      Лувен-ла-Нев, Walloon, Belgium
    • Rush University Medical Center
      Chicago, Illinois, United States
    • Rhode Island Hospital
      Providence, Rhode Island, United States
  • 1998
    • Wayne State University
      • Department of Radiation Oncology
      Detroit, MI, United States
  • 1996
    • University of Detroit Mercy
      Detroit, Michigan, United States