bluuebunny/crossref_metadata_2025_split huggingface dataset:
WE‐AB‐207B‐05: Correlation of Normal Lung Density Changes with Dose After Stereotactic Body Radiotherapy (SBRT) for Early Stage Lung Cancer
Authors: Wu Q , Devpura S , Feghali K , Liu C , Ajlouni M , Movsas B , Chetty I 
Published: July 2016

Purpose:To investigate correlation of normal lung CT density changes with dose accuracy and outcome after SBRT for patients with early stage lung cancer.Methods:Dose distributions for patients originally planned and treated using a 1‐D pencil beam‐based (PB‐1D) dose algorithm were retrospectively recomputed using algorithms: 3‐D pencil beam (PB‐3D), and model‐basedMethods:AAA, Acuros XB (AXB), and Monte Carlo (MC). Prescription dose was 12 Gy × 4 fractions. Planning CT images were rigidly registered to the followup CT datasets at 6–9 months after treatment. Corresponding dose distributions were mapped from the planning to followup CT images. Following the method of Palma et al .(1–2), Hounsfield Unit (HU) changes in lung density in individual, 5 Gy, dose bins from 5–45 Gy were assessed in the peri‐tumor region, defined as a uniform, 3 cm expansion around the ITV(1).Results:There is a 10–15% displacement of the high dose region (40–45 Gy) with the model‐based algorithms, relative to the PB method, due to the electron scattering of dose away from the tumor into normal lung tissue (Fig.1). Consequently, the high‐dose lung region falls within the 40–45 Gy dose range, causing an increase in HU change in this region, as predicted by model‐based algorithms (Fig.2). The patient with the highest HU change (∼110) had mild radiation pneumonitis, and the patient with HU change of ∼80–90 had shortness of breath. No evidence of pneumonitis was observed for the 3 patients with smaller CT density changes (<50 HU). Changes in CT densities, and dose‐response correlation, as computed with model‐based algorithms, are in excellent agreement with the findings of Palma et al. (1–2).Conclusion:Dose computed with PB (1D or 3D) algorithms was poorly correlated with clinically relevant CT density changes, as opposed to model‐based algorithms. A larger cohort of patients is needed to confirm these results.This work was supported in part by a grant from Varian Medical Systems, Palo Alto, CA
WE‐AB‐207B‐08: Exploring and Refining the QUANTEC Guideline to Reduce Severe Hyposalivation Following IMRT for Head and Neck Cancer
Authors: Thor M , Owosho A , Rosenburg H , Yom S , Oh J , Riaz N , Tsai J , Lee N , Huryn J , Estilo C , Deasy J 
Published: July 2016

Purpose:The aim of this study was to investigate the usefulness of the QUANTEC guideline to prevent xerostomia after intensity‐modulated radiotherapy (IMRT) for head and neck cancer (HNC) with respect to follow‐up time. In addition, we explored alternative guidelines to further reduce xerostomia.Methods:The QUANTEC guideline suggests a mean dose to the contralateral (Dmeancontra) parotid<20 Gy, or Dmeancontra and Dmean to the ipsilateral parotid (Dmeanipsi)<25 Gy. Stimulated whole mouth saliva flow measurements (WMSFM) were conducted at a median of 11 (3–24) months for 63 patients treated with IMRT for HNC to a median dose of 70 Gy in 2006–2015. Severe hyposalivation/xerostomia was defined as WMSFM ≤25% post‐ relative to pre‐RT. Patients were stratified into a <6m (xerostomia: 27% (n=15)), and a 6–24m (xerostomia: 19% (n=10)) follow‐up group. Dose‐response modeling was performed using logistic regression including Dmeancontra, or Dmeancontra and Dmeanipsi. The area under the receiver‐operating characteristics curve (AUC) was used to assess discriminative ability, and the agreement between the estimated and observed rate of xerostomia was given by Spearman's rank correlation coefficient (Rs), and related p‐values.Results:Of the non‐xerostomia patients, 65% (<6m) and 56% (6–24m) fulfilled Dmeancontra<20 Gy. The estimated and observed rate of xerostomia agreed at <6m (AUC=0.78; Rs=0.46; p=0.001), and was 28% at Dmeancontra=20 Gy. A smaller number of non‐xerostomia patients fulfilled the two‐gland guideline (33% (<6m) and 26% (6–24m)), but the AUC was higher than using Dmeancontra only (<6m: AUC=0.90; Rs=0.63; p<0.0001; 6–24m: AUC=0.84; Rs=0.25; p=0.08), and the following amendment of the two‐gland guideline was suggested: (0.17*Dmeancontra+0.11*Dmeanipsi‐8.13)<‐1.60 (<6m), and (0.05*Dmeancontra+0.02*Dmeanipsi‐3.10)<‐1.60 (6–24m).Conclusion:The QUANTEC guideline is effective to prevent xerostomia <6m post‐RT, but its usefulness is reduced at later follow‐up times. The suggested amendment to the two‐gland QUANTEC guideline should be further investigated in an independent cohort of HNC patients treated with IMRT.
WE‐AB‐207B‐10: On Spinal Nerve Toxicity from Single‐Session SAbR in Pigs and the Translation of Small Animal NTCP Models
Authors: Hrycushko B , Medin P 
Published: July 2016

Purpose:The incidence of peripheral neuropathy has risen with increased utilization of SAbR. There is no consensus regarding the dose‐tolerance of the peripheral nervous system. In 2015, we commenced an investigation to test the hypotheses that single‐session irradiation to the pig spinal nerves exhibit a similar dose‐tolerance as that of the spinal cord and that a dose‐length effect exists. This work evaluates the direct application of small animal NTCP models to both large animal spinal cord and preliminary peripheral nerve data.Methods:To date, 16 of 25 Yucatan minipigs have received single‐session SAbR to a 1.5cm length and 4 of 25 have received irradiation to a 0.5cm length of left‐sided C6‐C8 spinal nerves. Toxicity related gait change has been observed in 13 animals (9 from the long length group and 4 from the short). This preliminary data is overlaid on several dose‐response models which have been fit to rodent spinal cord tolerance experiments. Model parameters define a toxicity profile between a completely serial or parallel behaving organ. Adequacy of model application, including how length effects are handled, to published minipig spinal cord dose‐response data and to preliminary peripheral nerve response data was evaluated through residual analysis.Results:No rodent‐derived dose‐response models were directly applicable to all pig data for the different lengths irradiated. Several models fit the long‐length irradiated spinal cord data well, with the more serial‐like models fitting best. Preliminary data on the short‐length irradiation suggests no length effect exists, disproving our hypothesis.Conclusion:Direct application of small‐animal NTCP models to pig data suggests dose‐length effect predictions from small animal data may not translate clinically. However, the small animal models used have not considered dose heterogeneity and it is expected that including the low‐to‐mid dose levels in the penumbral region will improve this match.This work was funded by the Cancer Prevention Research Institute of Texas (CPRIT).
WE‐AB‐207B‐12: Prospective Study of the Relationship Between Dose‐Volume Clinical Toxicity and Patient Reported Outcomes in Lung Cancer Patients Treated with SBRT
Authors: Mayyas E , Vance S , Brown S , Liu J , Kim J , Zhen S , Devpura S , Ajlouni M , Salim S , Chetty I , Movsas B 
Published: July 2016

Purpose:To determine in a prospective study, the correlation between radiation dose/volume, clinical toxicities and patient‐reported, quality of life (QOL) resulting from lung SBRT.Methods:For 106 non‐small cell lung cancer (NSCLC) patients receiving SBRT (12 Gy × 4), symptoms including cough, dyspnea, fatigue and pneumonitis were measured at baseline (before treatment), after treatment and 3, 6, and 12 months post‐treatment. Toxicity was graded from zero to five. Dosimetric parameters such as the MLD, D10%, D20%, and lung subvolumes (V10 and V20) were obtained from the treatment plan. Dosimetric parameters and number of patients demonstrating toxicity ≥ grade 2 were tabulated. Linear regression analysis was used to calculate correlations between MLD and D10, D20, V10 and V20.Results:The percentages of patients with > grade 2 pneumonitis, fatigue, cough, and dyspnea over 3 to 12 months increased from 0.0% to 3.5%, 3.2% to 10.5%, 4.3% to 8.3%, and 10.8% to 18.8%, respectively. Computed dose indices D10%, D20% were 7.9±4.8 Gy and 3.0±2.3 Gy, respectively. MLD ranged from 0.34 Gy up to 9.9 Gy with overall average 3.0±1.7 Gy. The averages of the subvolumes V10 and V20 were respectively 8.9±5.3% and 3.0±2.4%. The linear regression analysis showed that V10 and D10 demonstrated the strongest correlation to MLD; R2= 0.92 and 0.87, respectively. V20, and D20 were also strongly correlated with MLD; R2 = 0.81 and 0.84 respectively. A correlation was also found to exist between MLD > 2 Gy and ≥ grade 2 cough and dyspnea. Subvolume values for 2Gy MLD were 5.3% for V10 and 2% for V20.Conclusion:Dosimetric indices: MLD ≥ 2Gy, D10 ≥ 5Gy and V10 ≥ 5% of the total lung volume were predictive of > grade 2 cough and dyspnea QOL data. The QOL results are a novel component of this work.acknowledgement of the Varian grant support.
WE‐D‐204‐03: CAMPEP Residencies in a Canadian Context: Comprehensive Cancer Centers and Integrated Learning Environments
Authors: Parker W. 
Published: July 2016

Speakers in this session will present overview and details of a specific rotation or feature of their Medical Physics Residency Program that is particularly exceptional and noteworthy. The featured rotations include foundational topics executed with exceptional acumen and innovative educational rotations perhaps not commonly found in Medical Physics Residency Programs. A site‐specific clinical rotation will be described, where the medical physics resident follows the physician and medical resident for two weeks into patient consultations, simulation sessions, target contouring sessions, planning meetings with dosimetry, patient follow up visits, and tumor boards, to gain insight into the thought processes of the radiation oncologist. An incident learning rotation will be described where the residents learns about and practices evaluating clinical errors and investigates process improvements for the clinic. The residency environment at a Canadian medical physics residency program will be described, where the training and interactions with radiation oncology residents is integrated. And the first month rotation will be described, where the medical physics resident rotates through the clinical areas including simulation, dosimetry, and treatment units, gaining an overview of the clinical flow and meeting all the clinical staff to begin the residency program. This session will be of particular interest to residency programs who are interested in adopting or adapting these curricular ideas into their programs and to residency candidates who want to learn about programs already employing innovative practices.

Learning Objectives:
To learn about exceptional and innovative clinical rotations or program features within existing Medical Physics Residency Programs.
To understand how to adopt/adapt innovative curricular designs into your own Medical Physics Residency Program, if appropriate.
WE‐D‐204‐04: Learning the Ropes: Clinical Immersion in the First Month of Residency
Authors: Dieterich S. 
Published: July 2016

Speakers in this session will present overview and details of a specific rotation or feature of their Medical Physics Residency Program that is particularly exceptional and noteworthy. The featured rotations include foundational topics executed with exceptional acumen and innovative educational rotations perhaps not commonly found in Medical Physics Residency Programs. A site‐specific clinical rotation will be described, where the medical physics resident follows the physician and medical resident for two weeks into patient consultations, simulation sessions, target contouring sessions, planning meetings with dosimetry, patient follow up visits, and tumor boards, to gain insight into the thought processes of the radiation oncologist. An incident learning rotation will be described where the residents learns about and practices evaluating clinical errors and investigates process improvements for the clinic. The residency environment at a Canadian medical physics residency program will be described, where the training and interactions with radiation oncology residents is integrated. And the first month rotation will be described, where the medical physics resident rotates through the clinical areas including simulation, dosimetry, and treatment units, gaining an overview of the clinical flow and meeting all the clinical staff to begin the residency program. This session will be of particular interest to residency programs who are interested in adopting or adapting these curricular ideas into their programs and to residency candidates who want to learn about programs already employing innovative practices.

Learning Objectives:
To learn about exceptional and innovative clinical rotations or program features within existing Medical Physics Residency Programs.
To understand how to adopt/adapt innovative curricular designs into your own Medical Physics Residency Program, if appropriate.
WE‐DE‐201‐01: BEST IN PHYSICS (THERAPY): A Fast Multi‐Target Inverse Treatment Planning Strategy Optimizing Dosimetric Measures for High‐Dose‐Rate (HDR) Brachytherapy
Authors: Guthier C , Damato A , Viswanathan A , Hesser J , Cormack R 
Published: July 2016

Purpose:Inverse treatment planning (ITP) for interstitial HDR brachytherapy of gynecologic cancers seeks to maximize coverage of the clinical target volumes (tumor and vagina) while respecting dose‐volume‐histogram related dosimetric measures (DMs) for organs at risk (OARs). Commercially available ITP tools do not support DM‐based planning because it is computationally too expensive to solve. In this study we present a novel approach that allows fast ITP for gynecologic cancers based on DMs for the first time.Methods:This novel strategy is an optimization model based on a smooth DM‐based objective function. The smooth approximation is achieved by utilizing a logistic function for the evaluation of DMs. The resulting nonconvex and constrained optimization problem is then optimized with a BFGS algorithm. The model was evaluated using the implant geometry extracted from 20 patient treatment plans under an IRB‐approved retrospective study. For each plan, the final DMs were evaluated and compared to the original clinical plans. The CTVs were the contoured tumor volume and the contoured surface of the vagina. Statistical significance was evaluated with a one‐sided paired Wilcoxon signed‐rank test.Results:As did the clinical plans, all generated plans fulfilled the defined DMs for OARs. The proposed strategy showed a statistically significant improvement (p<0.001) in coverage of the tumor and vagina, with absolute improvements of related DMs of (6.9 +/− 7.9)% and (28.2 +/− 12.0)%, respectively. This was achieved with a statistically significant (p<0.01) decrease of the high‐dose‐related DM for the tumor. The runtime of the optimization was (2.3 +/− 2.0) seconds.Conclusion:We demonstrated using clinical data that our novel approach allows rapid DM‐based optimization with improved coverage of CTVs with fewer hot spots. Being up to three orders of magnitude faster than the current clinical practice, the method dramatically shortens planning time.
WE‐DE‐201‐04: Cross Validation of Knowledge‐Based Treatment Planning for Prostate LDR Brachytherapy Using Principle Component Analysis
Authors: Roper J , Ghavidel B , Chanyavanich V , Godette K , Schreibmann E 
Published: July 2016

Purpose:To validate a knowledge‐based algorithm for prostate LDR brachytherapy treatment planning.Methods:A dataset of 100 cases was compiled from an active prostate seed implant service. Cases were randomized into 10 subsets. For each subset, the 90 remaining library cases were registered to a common reference frame and then characterized on a point by point basis using principle component analysis (PCA). Each test case was converted to PCA vectors using the same process and compared with each library case using a Mahalanobis distance to evaluate similarity. Rank order PCA scores were used to select the best‐matched library case. The seed arrangement was extracted from the best‐matched case and used as a starting point for planning the test case. Any subsequent modifications were recorded that required input from a treatment planner to achieve V100>95%, V150<60%, V200<20%. To simulate operating‐room planning constraints, seed activity was held constant, and the seed count could not increase.Results:The computational time required to register test‐case contours and evaluate PCA similarity across the library was 10s. Preliminary analysis of 2 subsets shows that 9 of 20 test cases did not require any seed modifications to obtain an acceptable plan. Five test cases required fewer than 10 seed modifications or a grid shift. Another 5 test cases required approximately 20 seed modifications. An acceptable plan was not achieved for 1 outlier, which was substantially larger than its best match. Modifications took between 5s and 6min.Conclusion:A knowledge‐based treatment planning algorithm for prostate LDR brachytherapy is being cross validated using 100 prior cases. Preliminary results suggest that for this size library, acceptable plans can be achieved without planner input in about half of the cases while varying amounts of planner input are needed in remaining cases. Computational time and planning time are compatible with clinical practice.
WE‐DE‐201‐07: Measurement of Real‐Time Dose for Tandem and Ovoid Brachytherapy Procedures Using a High Precision Optical Fiber Radiation Detector
Authors: Belley MD , Faught A , Moore B , Subashi E , Langloss B , Therien MJ , Yoshizumi TT , Chino JP , Craciunescu O 
Published: July 2016

Purpose:Development of a novel on‐line dosimetry tool is needed to move toward patient‐specific quality assurance measurements for Ir‐192 HDR brachytherapy to verify accurate dose delivery to the intended location. This work describes the development and use of a nano‐crystalline yttrium oxide inorganic scintillator based optical‐fiber detector capable of acquiring real‐time high‐precision dose measurements during tandem and ovoid (T&O) gynecological (GYN) applicator Ir‐192 HDR brachytherapy procedures.Methods:An optical‐fiber detector was calibrated by acquiring light output measurements in liquid water at 3, 5, 7, and 9cm radial source‐detector‐distances from an Ir‐192 HDR source. A regression model was fit to the data to describe the relative light output per unit dose (TG‐43 derived) as a function of source‐detector‐distance. Next, the optical‐fiber detector was attached to a vaginal balloon fixed to a Varian Fletcher‐Suit‐Delclos‐style applicator (to mimic clinical setup), and localized by acquiring high‐resolution computed tomography (CT) images. To compare the physical point dose to the TPS calculated values (TG‐43 and Acuros‐BV), a phantom measurement was performed, by submerging the T&O applicator in a liquid water bath and delivering a treatment template representative of a clinical T&O procedure. The fiber detector collected scintillation signal as a function of time, and the calibration data was applied to calculate both real‐time dose rate, and cumulative dose.Results:Fiber cumulative dose values were 100.0cGy, 94.3cGy, and 348.9cGy from the tandem, left ovoid, and right ovoid dwells, respectively (total of 443.2cGy). A plot of real time dose rate during the treatment was also acquired. The TPS values at the fiber location were 458.4cGy using TG‐43, and 437.6cGy using Acuros‐BV calculated as Dm,m (per TG‐186).Conclusion:The fiber measured dose value agreement was 3% vs TG‐43 and −1% vs Acuros‐BV. This fiber detector opens up new possibilities for performing patient‐specific quality assurance for Ir‐192 HDR GYN procedures.Funding from Coulter Foundation, Duke Bio‐medical Engineering. Company is being created around the detector technology. Duke holds patents on the technology.
WE‐D‐BRB‐01: Basic Physics of Proton Therapy
Authors: Arjomandy B. 
Published: July 2016

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy.

Learning Objectives:
Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy.
The current state of volumetric image guidance equipment in proton therapy.
Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.B. Teo, B.K Teo had received travel funds from IBA in 2015.
WE‐D‐BRB‐02: Proton Treatment Planning and Beam Optimization
Authors: Pankuch M. 
Published: July 2016

The goal of this session is to review the physics of proton therapy, treatment planning techniques, and the use of volumetric imaging in proton therapy. The course material covers the physics of proton interaction with matter and physical characteristics of clinical proton beams. It will provide information on proton delivery systems and beam delivery techniques for double scattering (DS), uniform scanning (US), and pencil beam scanning (PBS). The session covers the treatment planning strategies used in DS, US, and PBS for various anatomical sites, methods to address uncertainties in proton therapy and uncertainty mitigation to generate robust treatment plans. It introduces the audience to the current status of image guided proton therapy and clinical applications of CBCT for proton therapy. It outlines the importance of volumetric imaging in proton therapy.

Learning Objectives:
Gain knowledge in proton therapy physics, and treatment planning for proton therapy including intensity modulated proton therapy.
The current state of volumetric image guidance equipment in proton therapy.
Clinical applications of CBCT and its advantage over orthogonal imaging for proton therapy.B. Teo, B.K Teo had received travel funds from IBA in 2015.
WE‐DE‐BRC‐00: Learning the New Approaches of TG‐100 and Beyond
Authors: Dunscombe Peter 
Published: July 2016

This SAMs Therapy Educational Course will introduce participants to the tools recommended by TG 100 for use in the development of a risk‐based Quality Management Program. The Course will start with an Overview of the background and rationale behind the TG 100 initiative, from which its charge was developed. After setting the scene, four 15 minute presentations will introduce the principal components of the soon to be published Report of TG 100. These are Process Mapping, Failure Modes and Effects Analysis, Fault Tree Analysis and the development of a QA/QM risk‐based Program. There will be time for two short exercises based on Failure Modes and Effects Analysis and a Discussion before the SAMs questions which will conclude the session.

Learning Objectives:
To appreciate the underlying philosophy of the TG 100 initiative.
To gain a brief overview of the principal risk‐based tools recommended by TG 100.
In an informal workshop format, to explore, at an introductory level, the use of risk analysis as proposed by TG 100 as a prelude to the development of a Quality Management Program.