bluuebunny/crossref_metadata_2025_split huggingface dataset:
SU‐FF‐I‐96: Motion Adaptation for Registering Daily Online CBCT Images to Planning CT Images
Authors: Nguyen T‐N , Moseley J , Dawson L , Jaffray D , Brock K 
Published: April 2010

Purpose: Perform online image guidance (IGRT) and motion assessment using deformable registration by adapting patient liver motion models. Materials and Methods: 4DCT and daily 4DCBCT images were obtained for 15 patients treated under a stereotactic‐body radiotherapy protocol. Finite element models of patient liver respiratory motion were generated using a biomechanical‐model based platform, MORFEUS from 4DCT images. Motion was assessed using a Navigator channels (NC) technique. Five NCs, rectangular regions of interest, were placed on two images at corresponding spatial locations to define left (LR), anterior‐posterior (AP), and superior‐inferior (SI) liver edges. To determine interfraction liver/tumour positioning, the 4DCT exhale and daily 4DCBCT exhale images were used, while intrafraction liver/ tumour motion used exhale and inhale 4DCBCT images. The NC determines the 1D displacement between both images. This 1D motion adapts the MORFEUS‐based liver motion model. NC adaptation accuracy was evaluated by comparing the results with MORFEUS registration. Results: NC refinement has been performed on 8 patients to date in less than 2 mins each. Inter‐fraction motion of the liver exceeded 1 cm. Inter‐fraction NC technique accuracy (absolute mean (SD)) was 0.15 (0.11), 0.16 (0.10), and 0.15 (0.09) cm, in the LR, AP, and SI directions, respectively. Intra‐fraction motion exceeded 1.5cm. NC technique accuracy was 0.14 (0.10), 0.15 (0.08), and 0.18 (0.09) cm, in the LR, AP, and SI directions, respectively. The accuracy of the NC technique to identify the center of mass shift of the tumour for intra‐fraction motion was 0.16 (0.15), 0.14 (0.12), and 0.15 (0.10) cm, in the LR, AP, and SI directions, respectively. Conclusion: NC adaptation technique can accurately and efficiently integrate deformable registration into the IGRT process to account for inter and intra‐fraction motion.Research sponsored by the National Cancer Institute of Canada‐Terry Fox Foundation, Elekta Oncology Systems, and NIH 5RO1CA124714‐02.
SU‐FF‐I‐110: Dynamic Model for Validation and Quality Assurance of Quantification of DCE Imaging
Authors: Cao Y , Li D , Shen Z 
Published: April 2010

Introduction: Dynamic contrast enhanced (DCE) MR imaging is emerging as a biomarker for assessment of cancer therapy and normal tissue toxicity. It is extremely important to standardize DCE MR imaging acquisition and evaluate software of pharmacokinetic (PK) quantification for multi‐center clinical trials. A synthesized dynamic model with known values of physiological parameters could provide a platform to evaluate PK modeling software. This study aims to create and validate a synthesized model for evaluation of quantification of the general Toft's model. Methods: The synthesized DCE model has Ktrans values from 0 to 0.5 min−1, and νp from 0.01 to 0.1, and kep from 0.0 to 3.33 min−1. The temporal sampling is 1 second. The dynamic series is ̃4 minutes. The Gaussian‐distributed random noise was added to the theoretic model to yield contrast‐to‐noise ratios (CNR) of 10, 20, 50, 100, and indefinite. For each parameter combination, the synthesized data were generated 2500 times for each of the CNR levels to evaluate the mean, relative SD, and relative error between the known and estimated values of the vascular parameters derived from quantification software. The relative SD and error assess the stability and accuracy (or bias) of an estimated parameter, respectively. Results and Discussions: Without noise, the estimated values of the three vascular parameters by our in‐house software are equal to the known values, suggesting the excellent quality of the dynamic model. With noise, the relative SDs and errors increase with a decrease in CNRs. For both stability and accuracy, νp is superior compared to Ktrans and kep, suggesting the different tolerances to noise. For Ktrans values of 0 and 0.001 and vp values of 0.1, stability and accuracy were substantial worse than other conditions, suggesting that it is necessary to determine acceptable parameter ranges with given CNRs and acquisition.Supported by 3P01CA59827
SU‐FF‐I‐140: Cone Beam Breast CT Versus Mammography for Breast Density Measurement
Authors: Han T , Lai C , Chen L , Shen Y , Zhong Y , Liu X , Ge S , Yi Y , You Z , Wang T , Whitman G , Yang W , Shaw C 
Published: April 2010

Purpose: To compare breast density measurements using CBCT with those based on mammograms. Materials and Methods: 19 mastectomy specimens were imaged with a bench top aSi/CsI flat panel based CBCT system. Scans were performed at 80 kVp with a voxel size of 0.29 mm and an estimated dose level of 24 mGy at the isocenter. The reconstructed images were corrected and segmented to separate glandular tissue from adipose tissue. The voxel numbers for glandular tissue and the entire breast were counted from the segmented images and used to calculate the volume based breast density. The breast density was also calculated based on mammograms using a commercial software package. The number of pixels for dense tissue regions was counted and divided by that for the entire breast to compute the area based breast density. These two breast densities were used for comparison. The volume based breast densities were also converted into BI‐RADS categories for comparison with those from mammographic reading as recorded in the diagnostic report. Results: The volume based breast densities were mostly equal or lower than the mammographic ones (fig. 1 and Table 1) with a correlation (coefficient = 0.73) between the two. Comparison based on the BI‐RADS categories, more breasts with volume based measure were classified as categories 1 and 2 while most breasts with mammographic reading were classified as category 3 (Fig. 2) with a correlation coefficient of 0.55. Conclusion: It was found that breast densities calculated from CBCT images were significantly lower than those from mammograms for the 19 patients studied. Implication to the use of CBCT breast density as a risk factor for breast cancer remains to be investigated.This work was supported in part by grants CA104759 and CA124585 from NIH‐NCI, a grant EB00117 from NIH‐NIBIB, and a subcontract from NIST‐ATP.
SU‐FF‐J‐20: A Multimodality Imaging Approach for Predicting Radiation Induced Lung Injury
Authors: El Naqa I , Vaidya M , Apte A , Fergus S , Deasy J , Bradley J 
Published: April 2010

Purpose: Radiation pneumonitis (RP), is a major dose limiting toxicity in thoracic irradiation for patients with lung or breast cancer. Multimodality imaging and particularly integrated PET/CT imaging is increasing used in radiotherapy treatment staging, planning, and monitoring. In this work, we are investigating the potential of a new hybrid feature‐based approach utilizing post‐radiotherapy PET/CT images to predict the risk of later RP. Method and Materials: As a demonstrative example for analyzing normal tissue toxicities using the proposed multimodality approach, we analyzed post‐treatment PET/CT scans (typically, 3 mos. post‐RT) of 20 lung cancer radiotherapy patients for the endpoint of pneumonitis. The rate of RP in this group was 20%. The lung region minus the Gross Tumor Volume (GTV) was designated as the region of interest (ROI). We extracted features based on descriptive statistics of intensity (in units of SUV in PET and Hounsfield in CT), image intensity volume histogram (IVH) metrics, and texture‐based features. Statistical association was performed using Spearman's rank correlation (Rs). Results: Thirty candidate features were extracted from each image modality. Preliminary results indicate that texture features in both PET and CT seems to predict RP. For instance, the PET ROI standard deviation had Rs=0.14 in PET and Rs=−0.035 in CT while the texture (related to roughness) local heterogeneity had Rs=0.33 (p=0.08) in PET and Rs=0.63 (p=0.002) in CT. Conclusion: We have proposed a new approach for predicting RP risk pneumonitis from hybrid PET/CT image features. Texture related features on the post‐RT CT scan provide the best prediction. Estimating of these features could provide the physician with an early warning enabling a more proactive management of RP symptoms. Further analysis of these multimodality features, their complementary effect, and the optimal time of imaging, is needed to fully understand this finding.Partially supported by K25 CA128809 and R01 CA85181.
SU‐FF‐J‐32: Comparison of Manual Plus MI Registration to SWMI Registration Using MVCT for Head‐And‐Neck Cancer Patients
Authors: Park SB , Yao M , Sohn JW 
Published: April 2010

Purpose: To measure the value of manual adjustment after MI (Mutual Information) image registration technique for head‐and‐neck cancer cases, we compared the result to those performed with Spatially Weighted Mutual Information (SWMI) measure. Methods and Materials: We chose 6 head‐and‐neck cancer patients treated with Helical Tomotherapy machine and retrieved 199 daily MVCT image sets. Each patient had three CTVs and total superior‐inferior extent of CTVs was greater than 15cm. The daily images were manually aligned after automated registration with the MI software provided by Tomotherapy. Then, it was compared to the registration result of in‐house image registration software using SWMI with a Gaussian‐shaped weight. Gaussian‐shaped weight function was set to be centered in the primary CTV. And the variance of the Gaussian for each direction was set to cover CTVs and the critical organs. Each patient had the same variance of the Gaussian setup through a whole treatment course. Our in‐house image registration software was implemented to receive DICOM and DICOM‐RT from various planning systems. Since the Tomotherapy machine without a robotic couch cannot deliver yaw and pitch corrections, only roll was considered among the rotational transformation. Results and Discussion: Manual registration is not accurate enough if there is organ deformation. Fifty nine treatments among 199 treatments for 6 head‐and‐neck cancer patients showed the difference from our automated SWMI registration by more than 3mm. Our PTVs were created from CTVs by adding a 3mm margin. The minimal dose of CTV was reduced by 52% in maximum. SWMI incorporated with the Gaussian‐shaped weight shows better target coverage for all 199 cases. The main advantage of the automated SWMI is not relying on the user's expertise of visual image matching.(This work is partly supported by Susan G. Komen Breast Foundation Grant: BTCR126506)
SU‐FF‐J‐33: Error Propagation in Tracking Geometry and Dose Through the Course of Treatment for Dose Accumulation in Adaptive Therapy of Head‐And‐Neck Cancers
Authors: Kashani R , Jee K , Feng M , Balter J , Dong L , McShan D , Haken R Ten , Fraass B 
Published: April 2010

Purpose: In making re‐planning decisions in response to observed geometric changes in head‐and‐neck patients, the daily dose distribution is often compared to the initially planned dose distribution. A more accurate approach would evaluate the total delivered dose up the point when new patient model becomes available, making decisions based on deviations of the accumulated dose from the planned dose. The aim of this study is to compare the accuracy of two different dose accumulation methodologies that utilize deformable image registration for tracking dose. Methods: In the first method, the dose is tracked directly from each fraction to the new patient model, which requires N‐1 deformable registrations for dose accumulation at fraction N. In the second method, the total delivered dose is accumulated starting with fraction 2, such that at fraction N, the dose is already mapped to fraction N‐1 and a single deformation map would be sufficient to track dose to the new geometry. This study evaluates the accuracy of each technique by comparing deformed contours generated using each method for a single head‐and‐neck patient. Contours at fractions 5, 15, and 25 are compared visually and quantitatively using distance to agreement at specific points of interest. Results: Visual assessment indicates that method 1 is more accurate than method 2. The largest difference between the two simulated surfaces of CTV was observed near the edge of pharynx and was measured to be 0.49, 0.39 and 0.53 cm, for fractions 5, 15, and 25 respectively. Discussion: Propagation of deformable alignment errors has the potential to negatively impact cumulative dose evaluation. Caution is recommended in evaluating adaptive therapy implementations that relay on the accumulation of deformations for summation of dose evaluation in later treatment fractions.Supported by NIHP01CA59827
SU‐FF‐J‐34: Can 4D Dose Be Constructed Without Using Deformable Organ Registration?
Authors: Liang J , Chi Y , Qin X , Yan D 
Published: April 2010

Purpose: Image based deformable organ registration has been the primary means for 4D dose construction of moving organ. However, patient free breathing cone beam CT (FB‐CBCT) is more routinely obtained, instead of 4D CBCT. In this study, we examine if FB‐CBCT imaging can be directly applied for 4D dose construction. Method and Materials: Organs with the mean shape obtained from 4D reference CTs were mapped on a FB‐CBCT image by applying rigid‐body matching. The 4D dose in the organ was then constructed on the mean CT image using the 3‐dimenional‐motion pdf detected by the CB projection images. Three lung cancer patients with a planning and multiple daily 4D CTs were used to evaluate this method. The daily FB‐CBCT was constructed using the daily 4D CT. For each patient, dose distributions obtained from a 3D inverse planning and a 4D inverse planning were used in the evaluation. Dose distribution constructed using the mean organ and motion pdf was compared to the 4D dose calculated using the deformable organ registration on the daily 4D CTs. The minimal dose (D99) and EUD for the target, and the maximum dose (D1) for critical structures were used in the comparison. Results: Dose discrepancy (the mean ± SD) for D99 and EUD of the targets was −0.6%±2.6% and 0.0%±1.0%. Dose discrepancy of D1 was 1.5%±1.5% for heart, −1.6%±3.3% for Aorta and −0.6%±3.7% for Esophagus. Dose discrepancy in the lung was not evaluated in the current study due to the need of using variable pdfs at different location of the lung. Conclusion: 4D dose in organs of interest could be directly constructed using daily FB‐CBCT and measured pdf. The construction accuracy seems acceptable for the organs of interest inside of the lung.Support in part by Elekta Research Grant
SU‐FF‐J‐70: An Investigation of Interference Between Electromagnetic Transponders and Wireless MOSFET Dosimeters
Authors: Su Z , Zhang L , Ramakrishnan V , Hagan M , Anscher M 
Published: April 2010

Purpose: A phantom study to systematically investigate potential interferences between Calypso® Medical electromagnetic transponder and Sicel® DVS wireless MOSFET dosimeter when used in same patient. Method and Materials: A 30×30×5cm3 (Virtual Water®) phantom has a center hole for two separate 8cm diameter inserts with grooves for three pairs of transponders and dosimeters on each insert, respectively. The grooves of orthogonal and parallel orientations between transponders and dosimeters (long axes) were machined on the two inserts, respectively, with transponder‐dosimeter distance at 0, 1 and 2cm. In the transponder‐localization test (test1), transponder locations were obtained without and with dosimeters at different distances. Multivariate analysis tested the null hypothesis: the localized transponder coordinates are the same among datasets of control and various dosimeter locations. The 95% confidence‐intervals were also determined for the localization difference between control and test groups. In the dose‐measurement test (test2), 7 fractions of 1Gy were administrated to the dosimeters inside the phantom in an alternating fashion of without (fraction♯ 1, 3, 5, 7) and with transponders. Readings from fractions of no transponders were fit using a 2nd order polynomial. The dose differences between fit‐interpolated and corresponding measured values of fraction 2, 4, 6 were calculated. Results: For test1, multivariate analysis indicated that transponder localization accuracy was affected by the dosimeter. However, the 95% confidence‐intervals of the localized positional differences between control and test groups were less than 0.1mm, which is less than Calypso clinical display increment, 0.5mm. For test2, the maximum deviation of polynomial fitted dose values from measurements are within 1.5% and 0.8% for orthogonal and parallel configurations, respectively. Conclusion: This study showed no clinically significant interference between the transponder and dosimeter systems and demonstrated feasibility of combined use of transponders and dosimeters in the same patient.Research sponsored by Calypso Medical Technologies, Inc. and Sicel Technologies, Inc.
SU‐FF‐J‐78: Assessment of An Interpolated Ray Trace Algorithm for Deriving Motion From CBCT Scans
Authors: Siochi R 
Published: April 2010

Purpose: To asses the accuracy of an interpolated ray‐trace algorithm for deriving respiratory motion from megavoltage cone beam computed tomography (MVCBCT) scans. Method and Materials: 21 Siemens Oncor MVCBCT scans were taken of a tungsten pin attached to a motion phantom positioned with various orientations and table shifts to create motion with variable amplitudes of up to 1 cm along posterior‐anterior and right‐left axes and 3 cm in the cranio‐caudal axis. Edge detection found the pin in all 200 CBCT raw data projections. The intersection of ray‐traces, from the pin's image to the source, for two full exhale projections defined the exhale bounding point, while using two full inhale projections yields the inhale bounding point. These bounding points were ray‐traced into all projections. The position of the pin's image, relative to the projected bounding points, was used to interpolate between bounding points to find the pin's room coordinates for all projections. A plot of pin position versus projection time stamp was compared to the expected motion. Results: A bounding box, whose opposite corners are the projected bounding points, will contain the tungsten pin only if angular separations between projections used for bounding point determination are between 15 and 163 degrees, and differences in full inhale amplitudes are accounted for. Under these conditions, deviations between expected and calculated cranio‐caudal motion are primarily due to flat panel geometry error. The errors are worst at the edges of the CBCT reconstruction volume, with maximum and mean errors of 1.06 and 0.34 mm, respectively. When flat panel errors are corrected, the worst case mean error is 0.16 mm.Conclusion: For bounded motion of up to 3 cm, the interpolated ray‐trace algorithm will contribute little to the overall error for applications that determine diaphragm motion from patient CBCT scans.
SU‐FF‐T‐263: Evaluation of a PAGAT Gel for Use in An Anthropomorphic Phantom
Authors: Heard M , Ibbott G , Followill D , Jackson E , Salehpour M , White A 
Published: April 2010

Purpose: To evaluate the use of PAGAT, a normoxic polymer gel formulation, in the Radiological Physics Center's (RPC) Head and Neck Phantom. Methods and Materials: Conventional and IMRT treatment plans were developed for the RPC's head and neck phantom, which contained simulated planning target volumes and an organ at risk. A PAGAT dosimeter was placed in the phantom and the conventional treatment plan was delivered. A different PAGAT dosimeter was used to measure the IMRT treatment. An additional group of PAGAT dosimeters were irradiated to doses between 1 and 5 Gy through parallel‐opposed beams to develop a calibration curve. The dosimeters were imaged using an OCT‐OPUS™ laser CT scanner 24 hours after irradiation. Profile, isodose, and gamma index comparisons were performed between the treatment plan and the distribution measured with PAGAT. Results: Good agreement was observed between the conventional treatment plan and the gel distribution with the exception of one target region where the dose was most fractionated. The gel overestimated the dose in this region. The gel used to measure the IMRT treatment overestimated the dose by 35%. Relative comparisons of the IMRT treatment showed agreement consistent with that seen in the conventional treatment plan. Conclusions: The over‐response of the gel is attributed to the fractionation dependence of the gel, which was investigated. Calibration gels should be irradiated with a fractionation scheme similar to the experimental gels, particularly for IMRT treatments, so that absolute dose comparisons can be performed.The investigation was supported in part by PHS grant CA 10953 awarded by the NCI, DHHS.
SU‐FF‐T‐355: Investigation of Doped Quartz Fibre Detectors for Radiotherapy Dosimetry Applications
Authors: MacKay R , Aitkenhead A , Hardy M 
Published: April 2010

Purpose: The measurement of radiation dose and dose distributions is key to the delivery of safe radiotherapy treatments. The effectiveness of new radiation dosimeters manufactured by doping quartz fibres with copper and terbium has been investigated for a range of applications. Method and Materials: Doped quartz fibres exhibit spontaneous phosphorescence when irradiated. A prototype commercial system has been developed by splicing such a fibre has been to a commercial fibre optic cable and measuring the signal using a photomultiplier tube. The collection of the phosphorescence can be triggered using a number of methods such as using the linear accelerator current pulse or the detection of scattered radiation. Results: The gated signal from the fibre was averaged to determine the signal from the copper and terbium doped detectors. The half‐lives of the decay were found to be 0.08ms and 1.75ms for the copper and terbium detectors retrospectively. The slower decay of the terbium allows a higher signal to be collected but at standard accelerator pulse rates the signal of the fibre has not fully decayed before the next current pulse. The integrated signal from the fibres gives a repeatable measure of radiation dose. Fibres have been tested for a number of applications including IMRT point dosimetry for which there small volume is an advantage. The property of the dosimeters is dependant on the doping used. Terbium detectors will require correction of the signal when used at default dose rates for linear accelerators. Variation of the signal property with field size and energy will be presented. Conclusion: Doped quartz fibres have the potential to be an effective small volume dosimeter for a range of radiotherapy applications.Conflict of Interest: The detectors used in these experiments have been supplied by Global Dosimetry.