Minneapolis Radiation Oncology

Maple Plain, MN, United States

Minneapolis Radiation Oncology

Maple Plain, MN, United States
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Sprawls P.,Sprawls Educational Foundation | Fox M.,Minneapolis Radiation Oncology
Medical Physics | Year: 2012

Providing medical physics education to the general society has two valuable goals. For adults it helps them develop an understanding of medical science, technology, and clinical applications that they might encounter and have a better comprehension of a variety of scientific and technical issues in the news media. For students it enhances their interest in physics by showing applications that provide major benefits to society and introduces possible career paths. In the first part Perry Sprawls describes educational activities for adults. A course generally begins with the principles of the various imaging modalities with an emphasis on what can be visualized with each and typical clinical applications. The principles of modern radiation therapy are included with special attention to terminology associated with the various methods. There is always an interest in the effects of radiation so that is included with emphasis of benefits to risk. I always include one class on cardiac electronics, a special interest of mine, and plan to add a session on the physics and technology associated with hearing in future programs.Google Images is an excellent resource that can provide extensive visuals for courses of this type. Community senior‐adult lifelong learning courses and programs sponsored by Road Scholar, formerly ElderHostel, provide opportunities for medical physicists to share their knowledge and experience with citizens in their local communities. The second half of this symposium, given by Mary Fox, will focus on the elementary & high school age group. How do you educate young students about the career of medical physics? A sample presentation along with ideas for speaking to both these age levels will be demonstrated. Learning Objectives: 1. Provide adults with the knowledge to understand various medical procedures and effectively communicate with medical professionals. 2. Enhance the ability of adults to understand a variety of scientific and technological issues that are in the news 3. Provide the medical physicists with examples of presentation material for elementary and high school age groups. © 2012, American Association of Physicists in Medicine. All rights reserved.


Varadhan,Minneapolis Radiation Oncology | Hui S.,University of Minnesota
Medical Physics | Year: 2013

Purpose: The purpose of this work is to verify accuracy of deformable dose arising from deformable image registration (DIR) algorithms where the mass and density of tissue is conserved. This was done by using custom built deformable phantom mimicking bladder geometry with implanted MOSFETs that can be positioned in multiple locations thereby enabling direct measurement of dose delivered in different deformation states. Methods: The phantom was made using viscoelastic polymer which is nearly tissue equivalent with high tensile strength and elasticity. The phantom was deformed by positioning it with in a compression plate. 5 parallel air canals that run along the organ were used for positioning MOSFET detectors at multiple locations. Dose calculation was performed in undeformed geometry with varying degree of dose gradients. DIR was performed using both B‐Splines algorithm using 3D Slicer and commercial MimVista platform which uses intensity based free form algorithm. The resultant DVF was applied to the original dose distribution and compared with directly measured dose in deformed geometry at multiple locations. For IMRT fields the accuracy of dose warp was also validated by recalculating the original fluence map on the deformed data set and comparing the resultant dose distribution with the deformed dose from DIR. Results: For non IMRT type fields, both B‐Splines and MimVista yielded excellent point dose agreement to directly measured dose (within 2 cGy or 2%). For IMRT fields with large modulation since the inherent uncertainty in MOSFET measurement is 4.6%, agreement was less satisfactory. However comparison between IMRT doses recalculated in the deformed geometry with deformed dose from DIR yielded γ3%/3mm greater than 90%. Conclusion: We have verified that DIR based dose warping can yield accurate results for the algorithms studied. The magnitude of deformation and degree of dose modulation has the greatest impact on accuracy of dose warp. © 2013, American Association of Physicists in Medicine. All rights reserved.


Sperduto P.W.,Minneapolis Radiation Oncology | Shanley R.,University of Minnesota | Luo X.,University of Minnesota | Andrews D.,Thomas Jefferson University | And 6 more authors.
International Journal of Radiation Oncology Biology Physics | Year: 2014

Purpose: Radiation Therapy Oncology Group (RTOG) 9508 showed a survival advantage for patients with 1 but not 2 or 3 brain metastasis (BM) treated with whole-brain radiation therapy (WBRT) and stereotactic radiosurgery (SRS) versus WBRT alone. An improved prognostic index, the graded prognostic assessment (GPA) has been developed. Our hypothesis was that if the data from RTOG 9508 were poststratified by the GPA, the conclusions may vary.Methods and Materials: In this analysis, 252 of the 331 patients were evaluable by GPA. Of those, 211 had lung cancer. Breast cancer patients were excluded because the components of the breast GPA are not in the RTOG database. Multiple Cox regression was used to compare survival between treatment groups, adjusting for GPA. Treatment comparisons within subgroups were performed with the log-rank test. A free online tool (brainmetgpa.com) simplified GPA use.Results: The fundamental conclusions of the primary analysis were confirmed in that there was no survival benefit overall for patients with 1 to 3 metastases; however, there was a benefit for the subset of patients with GPA 3.5 to 4.0 (median survival time [MST] for WBRT + SRS vs WBRT alone was 21.0 versus 10.3 months, P=.05) regardless of the number of metastases. Among patients with GPA 3.5 to 4.0 treated with WBRT and SRS, the MST for patients with 1 versus 2 to 3 metastases was 21 and 14.1 months, respectively.Conclusions: This secondary analysis of predominantly lung cancer patients, consistent with the original analysis, shows no survival advantage for the group overall when treated with WBRT and SRS; however, in patients with high GPA (3.5-4), there is a survival advantage regardless of whether they have 1, 2, or 3 BM. This benefit did not extend to patients with lower GPA. Prospective validation of this survival benefit for patients with multiple BM and high GPA when treated with WBRT and SRS is warranted. © 2014 Elsevier Inc.


Havnensmith A.,Minneapolis Radiation Oncology
Medical Physics | Year: 2012

Purpose: 3D surface image guidance (3D SIG) has been shown to improve patient positioning accuracy in the treatment of breast cancer, but limited information is available regarding the dosimetric consequences of setup tolerances associated with breast radiation therapy techniques. The purpose of this study was to determine the magnitude of dose‐delivery errors associated with setup tolerances of 3 mm/3deg and 5 mm/5deg for set‐up and monitoring of whole breast radiation treatment using (3D SIG). Methods: Five test patients were selected for direct simulation of the maximum acceptable deviation from reference position for tangential beams using field‐in‐field (FinF) techniques. Dosimetric impact was determined by simulating the maximum allowable patient translations and rotations, recalculating the dose distribution, and propagating the dosimetric error for a full treatment course. For the planned and off‐set positions, dosimetric consequences were evaluated by examining the plan maximum dose, the percent coverage of the prescription dose for the lumpectomy bed, the V20Gy and V13Gy percentages for the ipsilateral lung, and the maximum point dose to the heart. The results are shown in Table I below. Results: For both 3 mm/3deg and 5 mm/5deg off‐sets in relatively large‐breasted patients (> 500 cc) no significant change is observed. The ipsilateral lung V20Gy and V13Gy had a maximum increase of 5.4% and 5.7%, respectively. Maximum dose to the heart increased by a maximum of about 8% for those patients being treated to the left breast. The patient with the largest dosimetric impact was relatively small‐breasted with a lumpectomy cavity in close proximity to the field borders. Conclusions: As tumor bed coverage and ipsilateral lung dose were heavily impacted for the studied tolerances, it may be beneficial to utilize an appropriately tighter tolerance in patients with breast volume < 500 cc with tumor bed volumes near the periphery of the field apertures. © 2012, American Association of Physicists in Medicine. All rights reserved.


Varadhan R.,Minneapolis Radiation Oncology | Karangelis G.,Oncology Systems Ltd | Krishnan K.,Kitware | Hui S.,University of Minnesota
Journal of Applied Clinical Medical Physics | Year: 2013

Quantitative validation of deformable image registration (DIR) algorithms is extremely difficult because of the complexity involved in constructing a deformable phantom that can duplicate various clinical scenarios. The purpose of this study is to describe a framework to test the accuracy of DIR based on computational modeling and evaluating using inverse consistency and other methods. Three clinically relevant organ deformations were created in prostate (distended rectum and rectal gas), head and neck (large neck flexion), and lung (inhale and exhale lung volumes with variable contrast enhancement) study sets. DIR was performed using both B-spline and diffeomorphic demons algorithms in the forward and inverse direction. A compositive accumulation of forward and inverse deformation vector fields was done to quantify the inverse consistency error (ICE). The anatomical correspondence of tumor and organs at risk was quantified by comparing the original RT structures with those obtained after DIR. Further, the physical characteristics of the deformation field, namely the Jacobian and harmonic energy, were computed to quantify the preservation of image topology and regularity of spatial transformation obtained in DIR. The ICE was comparable in prostate case but the B-spline algorithm had significantly better anatomical correspondence for rectum and prostate than diffeomorphic demons algorithm. The ICE was 6.5 mm for demons algorithm for head and neck case when compared to 0.7 mm for B-spline. Since the induced neck flexion was large, the average Dice similarity coefficient between both algorithms was only 0.87, 0.52, 0.81, and 0.67 for tumor, cord, parotids, and mandible, respectively. The B-spline algorithm accurately estimated deformations between images with variable contrast in our lung study, while diffeomorphic demons algorithm led to gross errors on structures affected by contrast variation. The proposed framework offers the application of known deformations on any image datasets, to evaluate the overall accuracy and limitations of a DIR algorithm used in radiation oncology. The evaluation based on anatomical correspondence, physical characteristics of deformation field, and image characteristics can facilitate DIR verification with the ultimate goal of implementing adaptive radiotherapy. The suitability of application of a particular evaluation metric in validating DIR is dependent on the clinical deformation observed.


PubMed | University of Minnesota and Minneapolis Radiation Oncology
Type: Journal Article | Journal: Medical physics | Year: 2017

To verify experimentally the accuracy of Monaco (Elekta) electron Monte Carlo (eMC) algorithm to calculate small field size depth doses, monitor units and isodose distributions.Beam modeling of eMC algorithm was performed for electron energies of 6, 9, 12 15 and 18 Mev for a Elekta Infinity Linac and all available (6, 10, 14 20 and 25 cone) applicator sizes. Electron cutouts of incrementally smaller field sizes (20, 40, 60 and 80% blocked from open cone) were fabricated. Dose calculation was performed using a grid size smaller than one-tenth of the RThe measured dose and output factors of incrementally reduced cutout sizes (to 3cm diameter) agreed with eMC calculated doses within 2.5%. The profile comparisons at dmax, dOur results indicate that the Monaco eMC algorithm can accurately predict depth doses, isodose distributions, and monitor units in homogeneous water phantom for field sizes as small as 3.0 cm diameter for energies in the 6 to 18 MeV range at 100 cm SSD. Consequently, the old rule of thumb to approximate limiting cutout size for an electron field determined by the lateral scatter equilibrium (E (MeV)/2.5 in centimeters of water) does not apply to Monaco eMC algorithm.


PubMed | University of Minnesota and Minneapolis Radiation Oncology
Type: Journal Article | Journal: Medical physics | Year: 2017

To compare the plan quality between Eclipse (Varian) and Monaco (Elekta) TPS. To ascertain, if SBRT lung treatment could be delivered in a single coplanar arc (360 degrees) with both Elekta and Varian platforms. To assess if the smaller leaf width in Varian Millennium and Elekta Agility MLC heads have a dosimetric advantage over Elekta MLCi2 head METHODS: Ten SBRT lung patients (PTV volumes ranging from 11 cc to 103cc) who were previously treated on Varian Linac with non-coplanar arcs and received 50Gy in 5 fractions were chosen for this study. The patients were replanned in Eclipse TPS (AAA algorithm) using a 360 degree coplanar single arc (SA) delivery technique and 2 partial complimentary 180 degree arcs (PA). Treatment planning using single coplanar arc (360 degree arc) was also done on Monaco TPS (Montecarlo) for both Agility (160 leaf) and MLCi2 (80 leaf) Elekta MLC heads RESULTS: The average monitor units to deliver 10 Gy across all delivery methods were 3000 474 MU and did not vary with PTV size. Coplanar single arc and partial arc techniques did not compromise either the RTOG 0813 or 0915 low dose spillage criteria for R50% or the maximum dose to any point 2cm away from the PTV. OAR doses to spinal cord, heart, great vessels, esophagus, rib and lung were comparable on both Eclipse (Varian) and Monaco (Elekta) platforms regardless of the delivery method.SBRT lung tumors can be treated with a single coplanar 360 degree arc in both Varian and Elekta platforms. Non coplanar arcs and increasing arc degrees more than 360 degrees had no benefit in this study regardless of the volume of PTV. 0.5 cm leaf width used in Millennium and Agility MLC heads had no significant dosimetric improvement over 1 cm leaves in the MLCi2 head.


News Article | November 17, 2016
Site: www.eurekalert.org

A new article published online by JAMA Oncology updates a tool to estimate survival in patients with lung cancer and brain metastases. Lung cancer is a leading cause of death in the United States and around the world. A frequent and serious consequence of the disease is metastasis to the brain. New therapies mean survival from lung cancer continues to improve and patients are at increased risk of developing later complications of the disease, such as brain metastases. Understanding prognosis for lung cancer is important, both for designing individualized care and future clinical trials. In their article, Paul W. Sperduto, M.D., M.P.P., of Minneapolis Radiation Oncology and the University of Minnesota, Minneapolis, and coauthors update the original Diagnosis-Specific Graded Prognostic Assessment(DS-GPA) with new genetic and molecular data to create a new index called the Lung-moIGPA, which can be accessed electronically. The updated Lung-moIGPA was designed by analyzing data from 2,186 patients in a multi-institution database from 2006 through 2014 with non-small cell lung cancer and newly diagnosed brain metastases. Two new prognostic factors were used in the new Lung-moIGPA: EGFR and ALK gene mutations. The authors reported overall median survival in the patient group was 12 months. Study limitations include its design, which cannot establish causality. "The updated Lung-moIGPA incorporating gene alteration data into the DS-GPA is a user-friendly tool that may facilitate clinical decision-making and appropriate stratification of future clinical trials," the study concludes. Editor's Note: The article contains conflict of interest and funding/support disclosures. Please see the article for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.


News Article | November 19, 2016
Site: www.sciencedaily.com

A new article published online by JAMA Oncology updates a tool to estimate survival in patients with lung cancer and brain metastases. Lung cancer is a leading cause of death in the United States and around the world. A frequent and serious consequence of the disease is metastasis to the brain. New therapies mean survival from lung cancer continues to improve and patients are at increased risk of developing later complications of the disease, such as brain metastases. Understanding prognosis for lung cancer is important, both for designing individualized care and future clinical trials. In their article, Paul W. Sperduto, M.D., M.P.P., of Minneapolis Radiation Oncology and the University of Minnesota, Minneapolis, and coauthors update the original Diagnosis-Specific Graded Prognostic Assessment(DS-GPA) with new genetic and molecular data to create a new index called the Lung-moIGPA, which can be accessed electronically. The updated Lung-moIGPA was designed by analyzing data from 2,186 patients in a multi-institution database from 2006 through 2014 with non-small cell lung cancer and newly diagnosed brain metastases. Two new prognostic factors were used in the new Lung-moIGPA: EGFR and ALK gene mutations. The authors reported overall median survival in the patient group was 12 months. Study limitations include its design, which cannot establish causality. "The updated Lung-moIGPA incorporating gene alteration data into the DS-GPA is a user-friendly tool that may facilitate clinical decision-making and appropriate stratification of future clinical trials," the study concludes.


Varadhan R.,Minneapolis Radiation Oncology
Journal of applied clinical medical physics / American College of Medical Physics | Year: 2013

Quantitative validation of deformable image registration (DIR) algorithms is extremely difficult because of the complexity involved in constructing a deformable phantom that can duplicate various clinical scenarios. The purpose of this study is to describe a framework to test the accuracy of DIR based on computational modeling and evaluating using inverse consistency and other methods. Three clinically relevant organ deformations were created in prostate (distended rectum and rectal gas), head and neck (large neck flexion), and lung (inhale and exhale lung volumes with variable contrast enhancement) study sets. DIR was performed using both B-spline and diffeomorphic demons algorithms in the forward and inverse direction. A compositive accumulation of forward and inverse deformation vector fields was done to quantify the inverse consistency error (ICE). The anatomical correspondence of tumor and organs at risk was quantified by comparing the original RT structures with those obtained after DIR. Further, the physical characteristics of the deformation field, namely the Jacobian and harmonic energy, were computed to quantify the preservation of image topology and regularity of spatial transformation obtained in DIR. The ICE was comparable in prostate case but the B-spline algorithm had significantly better anatomical correspondence for rectum and prostate than diffeomorphic demons algorithm. The ICE was 6.5 mm for demons algorithm for head and neck case when compared to 0.7 mm for B-spline. Since the induced neck flexion was large, the average Dice similarity coefficient between both algorithms was only 0.87, 0.52, 0.81, and 0.67 for tumor, cord, parotids, and mandible, respectively. The B-spline algorithm accurately estimated deformations between images with variable contrast in our lung study, while diffeomorphic demons algorithm led to gross errors on structures affected by contrast variation. The proposed framework offers the application of known deformations on any image datasets, to evaluate the overall accuracy and limitations of a DIR algorithm used in radiation oncology. The evaluation based on anatomical correspondence, physical characteristics of deformation field, and image characteristics can facilitate DIR verification with the ultimate goal of implementing adaptive radiotherapy. The suitability of application of a particular evaluation metric in validating DIR is dependent on the clinical deformation observed.

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