S. Dieterich

University of California, Davis, Davis, California, United States

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Publications (164)419.75 Total impact

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    ABSTRACT: Precise and accurate patient positioning is necessary when doing stereotactic radiosurgery (SRS) to ensure adequate dosing to the tumor and sparing of normal tissues. This prospective cross-sectional study aimed to assess feasibility of a commercially available modified frameless SRS positioning system for use in veterinary radiotherapy patients with brain tumors. Fifty-one dogs and 12 cats were enrolled. Baseline and verification CT images were acquired. The verification CT images from 32 dogs and five cats had sufficient images for fusion to baseline CT images. A rigid box-based fusion was performed to determine interfraction motion. Forty-eight dogs and 11 cats were assessed for intrafraction motion by cine CT. Seventy percent of dogs and 60% of cats had interfraction 3D vector translational shifts >1 mm, with mean values of 1.9 mm in dogs, and 1.8 mm in cats. In dogs muscle wasting was weakly correlated with translational shifts. The maximum angular interfraction motion observed was 6.3° (roll), 3.5° (pitch), and 3.3° (yaw). There was no correlation between angular interfraction motion and weight, brachycephaly, or muscle wasting. Fifty-seven percent of dogs and 50% of cats had respiration-related intrafraction motion. Of these, 4.5% of dogs and 10% of cats had intrafraction motion >1 mm. This study demonstrates the modified Brainlab system is feasible for SRS in dogs and cats. The smaller cranial size and difference in anatomy increases setup uncertainty in some animals beyond limits usually accepted in SRS. Image-guided positioning is recommended to achieve clinically acceptable setup accuracy (<1 mm) for SRS. © 2015 American College of Veterinary Radiology.
    No preview · Article · Jun 2015 · Veterinary Radiology & Ultrasound
  • S Dieterich · J Perks · R Fragoso
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    ABSTRACT: Medical Physicists and Radiation Oncologists are two professions who should be working as a team for optimal patient care, yet lack of mutual understanding about each others respective role and work environment creates barriers To improve collaboration and learning, we designed a shared didactic and work space for physics and radiation oncology residents to maximize interaction throughout their professional training. Physician and Physics residents are required to take the same didactic classes, including journal clubs and respective seminars. The residents also share an office environment among the seven physician and two physic residents. By maximizing didactic overlap and sharing office space, the two resident groups have developed a close professional relationship and supportive work environment. Several joint research projects have been initiated by the residents. Awareness of physics tasks in the clinic has led to a request by the physician residents to change physics didactics, converting the physics short course into a lab-oriented course for the medical residents which is in part taught by the physics residents. The physics seminar is given by both residency groups; increased motivation and interest in learning about physics has led to several medical resident-initiated topic selections which generated lively discussion. The physics long course has changed toward including more discussion among residents to delve deeper into topics and study beyond what passing the boards would require. A supportive work environment has developed, embedding the two physics residents into a larger residents group, allowing them to find mentor and peers more easily. By creating a shared work and didactic environment, physician and physics residents have improved their understanding of respective professional practice. Resident-initiated changes in didactic practice have led to improved learning and joint research. A strong social support system has developed, embedding physics residents into a larger peer group.
    No preview · Article · Jun 2015 · Medical Physics
  • S Dieterich · E Trestrail · R Holt · S Saini · I Pfeiffer · M Kent · K Hansen
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    ABSTRACT: To assess if the TrueBeam HD120 collimator is delivering small IMRT fields accurately and consistently throughout the course of treatment using the SunNuclear PerFraction software. 7-field IMRT plans for 8 canine patients who passed IMRT QA using SunNuclear Mapcheck DQA were selected for this study. The animals were setup using CBCT image guidance. The EPID fluence maps were captured for each treatment field and each treatment fraction, with the first fraction EPID data serving as the baseline for comparison. The Sun Nuclear PerFraction Software was used to compare the EPID data for subsequent fractions using a Gamma (3%/3mm) pass rate of 90%. To simulate requirements for SRS, the data was reanalyzed using a Gamma (3%/1mm) pass rate of 90%. Low-dose, low- and high gradient thresholds were used to focus the analysis on clinically relevant parts of the dose distribution. Not all fractions could be analyzed, because during some of the treatment courses the DICOM tags in the EPID images intermittently change from CU to US (unspecified), which would indicate a temporary loss of EPID calibration. This technical issue is still being investigated. For the remaining fractions, the vast majority (7/8 of patients, 95% of fractions, and 96.6% of fields) are passing the less stringent Gamma criteria. The more stringent Gamma criteria caused a drop in pass rate (90 % of fractions, 84% of fields). For the patient with the lowest pass rate, wet towel bolus was used. Another patient with low pass rates experienced masseter muscle wasting. EPID dosimetry using the PerFraction software demonstrated that the majority of fields passed a Gamma (3%/3mm) for IMRT treatments delivered with a TrueBeam HD120 MLC. Pass rates dropped for a DTA of 1mm to model SRS tolerances. PerFraction pass rates can flag missing bolus or internal shields. Sanjeev Saini is an employee of Sun Nuclear Corporation. For this study, a pre-release version of PerFRACTION 1.1 software from Sun Nuclear Corporation was used.
    No preview · Article · Jun 2015 · Medical Physics
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    ABSTRACT: Setup variability affects the appropriate delivery of radiation and informs the setup margin required to treat radiation patients. Twenty-four veterinary patients with head and neck cancers were enrolled in this prospective, cross-sectional study to determine the accuracy of an indexed board immobilization device for positioning. Couch position values were defined at the first treatment based on setup films. At subsequent treatments, patients were moved to the previously defined couch location, orthogonal films were acquired, table position was modified, and displacement was recorded. The mean systematic displacement, random displacement, overall displacement, and mean displacement values of the three-dimensional (3D) vector were calculated. Three hundred thirty-two pairs of orthogonal setup films were analyzed for displacement in cranial-caudal, lateral, and dorsal-ventral directions. The mean systematic displacements were 0.5, 0.8, and 0.5 mm, respectively. The mean random displacements were 1.0, 1.1, and 0.7 mm, respectively. The overall displacements were 1.1, 1.4, and 0.9 mm, respectively. The mean 3D vector value was 1.6 mm with a standard deviation of 1.2 mm. Ninety-five percent of the vectors were <3.6 mm. These values were compared to data obtained with a previously used immobilization device. A t-test was used to compare the two devices. The 3D vector, random displacement in all directions, and overall displacement in the cranial-caudal and dorsal-ventral directions were significantly smaller than displacements with the previous device. The precision and accuracy of the indexed board device was superior to the historical head and neck device. © 2015 American College of Veterinary Radiology.
    Full-text · Article · Apr 2015 · Veterinary Radiology & Ultrasound
  • G Ibbott · S Dieterich · M Yester · J Allison · J Seibert
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    ABSTRACT: While the vast majority of clinical medical physicists either have taken, or will take the ABR certification exams, there appears to be limited understanding about the process of creating, administering, scoring and evaluating the exams. In this course, ABR trustees and volunteers will educate current and future ABR diplomates about the process of question writing, written exam assembly, evaluation of the performance of the exams, and preparation and delivery of the oral board exam. By understanding the process behind creating the written and oral exams, ABR candidates and diplomates will gain a better understanding of the framework of the exams, including the financial resources needed. At the same time, understanding the many hours of volunteer work needed to create a fair and meaningful exam may create a positive incentive to respect the exam confidentiality. Learning Objectives: 1. Understand the characteristics of a well-written exam question. 2. Learn about the process of developing and administering an exam. 3. Review the application of psychometric analysis to the ABR exams. 4. Appreciate the effort and expense involved in preparing the certification exams.
    No preview · Article · Jun 2014 · Medical Physics
  • Sonja Dieterich · Paul J Keall · Colin G Orton

    No preview · Article · Oct 2013 · Medical Physics
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    ABSTRACT: Purpose: To determine how best to time respiratory surrogate-based tumor motion model updates by comparing a novel technique based on external measurements alone to three direct measurement methods. Methods: Concurrently measured tumor and respiratory surrogate positions from 166 treatment fractions for lung or pancreas lesions were analyzed. Partial-least-squares regression models of tumor position from marker motion were created from the first six measurements in each dataset. Successive tumor localizations were obtained at a rate of once per minute on average. Model updates were timed according to four methods: never, respiratory surrogate-based (when metrics based on respiratory surrogate measurements exceeded confidence limits), error-based (when localization error ≥ 3 mm), and always (approximately once per minute). Results: Radial tumor displacement prediction errors (mean ± standard deviation) for the four schema described above were 2.4 ± 1.2, 1.9 ± 0.9, 1.9 ± 0.8, and 1.7 ± 0.8 mm, respectively. The never-update error was significantly larger than errors of the other methods. Mean update counts over 20 min were 0, 4, 9, and 24, respectively. Conclusions: The same improvement in tumor localization accuracy could be achieved through any of the three update methods, but significantly fewer updates were required when the respiratory surrogate method was utilized. This study establishes the feasibility of timing image acquisitions for updating respiratory surrogate models without direct tumor localization.
    No preview · Article · Jul 2013 · Medical Physics
  • T Bichay · S Dieterich · D Schlesinger
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    ABSTRACT: Cranial radiosurgery has developed as a highly accurate treatment procedure for relatively small lesions. There is much discussion in the literature as to what degree of accuracy is possible when the treatment system is evaluated as a whole; including cranial fixation, localization, imaging, registration, contouring, dose calculation, etc. This is now commonly referred to as the end‐to‐end (E2E) test. The now‐dated AAPM report 54 (1995) suggested that the total uncertainty can reach 2–3 mm. However, many newer publications suggest a much tighter tolerance is achievable. This discussion will focus on the strengths, and weaknesses of well‐established cranial radiosurgery systems including Gamma Knife and CyberKnife, as well as linac‐based systems. The typical, and maximum accuracy of each system will be presented including benefits of mask immobilization and invasive ring fixation. The intent of these presentations is to outline the current state of cranial radiosurgery, and review relevant technologies that have improved our treatment accuracy. Limitations that still persist at this point will also be outlined and reviewed. Learning Objectives: 1. Advantages of various radiosurgery technologies. 2. Limitations of various radiosurgery technologies. 3. Main hurdles in achieving sub‐millimeter treatment accuracy. 4. Overall treatment accuracy assessed by E2E testing.
    No preview · Article · Jun 2013 · Medical Physics
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    Full-text · Article · May 2013 · International journal of radiation oncology, biology, physics
  • Tewfik Bichay · Sonja Dieterich · Colin G Orton
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    ABSTRACT: OVERVIEW With most external beam radiotherapy treatments an accuracy of ±3 mm is usually considered desirable and achievable. With stereotactic radiotherapy, however, a somewhat greater accuracy is desired and, with modern techniques, can be achieved, and some claim that even submillimeter accuracy is achievable. This is the topic debated in this month’s Point/Counterpoint.
    No preview · Article · May 2013 · Medical Physics
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    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    No preview · Dataset · Mar 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    No preview · Dataset · Mar 2013
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    Full-text · Article · Mar 2013 · Journal of Applied Clinical Medical Physics
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking. PACS number: 87.57.N-; 87.57.nm; 87.53.Ly Key words: implanted fiducial marker migration, stereotactic ablative radiotherapy (SABR), stereotactic body radiotherapy (SBRT), endovascular embolization coils, gold seed fiducial markers Conflict of Interest statement: BL and PM have received speaking honoraria from Varian Medical Systems and General Electric Medical Systems, and research fund-ing from Varian Medical Systems to the Department of Radiation Oncology.
    No preview · Dataset · Mar 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    No preview · Dataset · Mar 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    No preview · Dataset · Mar 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    No preview · Dataset · Mar 2013
  • [Show abstract] [Hide abstract]
    ABSTRACT: The purpose of this study was to quantify postimplantation migration of percu-taneously implanted cylindrical gold seeds ("seeds") and platinum endovascular embolization coils ("coils") for tumor tracking in pulmonary stereotactic ablative radiotherapy (SABR). We retrospectively analyzed the migration of markers in 32 consecutive patients with computed tomography scans postimplantation and at simulation. We implanted 147 markers (59 seeds, 88 coils) in or around 34 pulmonary tumors over 32 procedures, with one lesion implanted twice. Marker coordinates were rigidly aligned by minimizing fiducial registration error (FRE), the root mean square of the differences in marker locations for each tumor between scans. To also evaluate whether single markers were responsible for most migra-tion, we aligned with and without the outlier causing the largest FRE increase per tumor. We applied the resultant transformation to all markers. We evaluated migration of individual markers and FRE of each group. Median scan interval was 8 days. Median individual marker migration was 1.28 mm (interquartile range [IQR] 0.78–2.63 mm). Median lesion FRE was 1.56 mm (IQR 0.92–2.95 mm). Outlier identification yielded 1.03 mm median migration (IQR 0.52–2.21 mm) and 1.97 mm median FRE (IQR 1.44–4.32 mm). Outliers caused a mean and median shift in the centroid of 1.22 and 0.80 mm (95th percentile 2.52 mm). Seeds and coils had no statistically significant difference. Univariate analysis suggested no correlation of migration with the number of markers, contact with the chest wall, or time elapsed. Marker migration between implantation and simulation is limited and unlikely to cause geometric miss during tracking.
    No preview · Dataset · Mar 2013

  • No preview · Article · Nov 2012 · International Journal of Radiation OncologyBiologyPhysics
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    ABSTRACT: To determine the clinical impact of calculated dose differences between effective path length (EPL) and Monte Carlo (MC) algorithms in stereotactic ablative radiation therapy (SABR) of lung tumors. We retrospectively analyzed the treatment plans and clinical outcomes of 77 consecutive patients treated with SABR for 82 lung tumors between 2003 and 2009 at our institution. Sixty treatments were originally planned using EPL, and 22 using MC. All plans were recalculated for the same beam specifications using MC and EPL, respectively. The doses covering 95%, 50%, and 5% (D95, D50, D5, respectively) of the target volumes were compared between EPL and MC (assumed to be the actual delivered dose), both as physical dose and biologically effective dose. Time to local recurrence was correlated with dose by Cox regression analysis. The relationship between tumor control probability (TCP) and biologically effective dose was determined via logistic regression and used to estimate the TCP decrements due to prescribing by EPL calculations. EPL overestimated dose compared with MC in all tumor dose-volume histogram parameters in all plans. The difference was >10% of the MC D95 to the planning target volume and gross tumor volume in 60 of 82 (73%) and 52 of 82 plans (63%), respectively. Local recurrence occurred in 13 of 82 tumors. Controlling for gross tumor volume, higher physical and biologically effective planning target volume D95 correlated significantly with local control (P = .007 and P = .045, respectively). Compared with MC, prescribing based on EPL translated to a median TCP decrement of 4.3% (range, 1.2%-37%) and a >5% decrement in 46% of tumors. Clinical follow-up for local lung tumor control in a sizable cohort of patients treated with SABR demonstrates that EPL overestimates dose by amounts that substantially decrease TCP in a large proportion. EPL algorithms should be avoided for lung tumor SABR.
    No preview · Article · Oct 2012 · Practical Radiation Oncology

Publication Stats

2k Citations
419.75 Total Impact Points

Institutions

  • 2012-2015
    • University of California, Davis
      Davis, California, United States
    • University of California, Los Angeles
      Los Ángeles, California, United States
  • 2007-2013
    • Stanford University
      • Department of Radiation Oncology
      Stanford, California, United States
    • University of Maryland, Baltimore
      Baltimore, Maryland, United States
  • 2001-2011
    • Rutgers, The State University of New Jersey
      New Brunswick, New Jersey, United States
  • 2009
    • University of Miami Miller School of Medicine
      • Department of Radiation Oncology
      Miami, FL, United States
  • 2003-2008
    • Georgetown University
      • • Department of Radiation Medicine
      • • Department of Radiology
      Washington, Washington, D.C., United States
  • 2005
    • Johns Hopkins Medicine
      Baltimore, Maryland, United States
    • University of Maryland, College Park
      • Department of Physics
      College Park, MD, United States