bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dosimetric evaluation of multilumen intracavitary balloon applicator rotation in high‐dose‐rate brachytherapy for breast cancer
Authors: Kim Yongbok , Trombetta Mark G. 
Published: February 2017

The objective of this work is to evaluate dosimetric impact of multilumen balloon applicator rotation in high‐dose‐rate (HDR) brachytherapy for breast cancer. Highly asymmetrical dose distribution was generated for patients A and B, depending upon applicator proximity to skin and rib. Both skin and rib spacing was for A; only rib spacing was for B. Thirty‐five rotation scenarios were simulated for each patient by rotating outer lumens every 10° over range with respect to central lumen using mathematically calculated rotational matrix. Thirty‐five rotated plans were compared with three plans: 1) original multidwell multilumen (MDML) plan, 2) multidwell single‐lumen (MDSL) plan, and 3) singledwell single‐lumen (SDSL) plan. For plan comparison, planning target volume for evaluation (PTV_EVAL) coverage (dose to 95% and 90% volume of PTV_EVAL) (D95 and D90), skin and rib maximal dose (Dmax), and normal breast tissue volume receiving 150% (V150) and 200% (V200) of prescribed dose (PD) were evaluated. Dose variation due to device rotation ranged from to 0.8% (A) and to 0.2% (B) for PTV_EVAL D95; to 0.4% (A) and to 0.7% (B) for PTV_EVAL D90; to 18.4% (A) and to 17.5% (B) for skin Dmax; to 22.8% (A) and to 55.1% (B) of PD for rib Dmax, respectively. Normal breast tissue V150 and V200 variation was , except for to 2.5 cc (B) of V200. Furthermore, 30° device rotation increased rib Dmax over 145% of PD: 152.9% (A) by clockwise 30° rotation and 152.5% (B) by counterclockwise 30° rotation. For a highly asymmetric dose distribution, device rotation can outweigh the potential benefit of improved dose shaping capability afforded by multilumen and make dosimetric data worse than single‐lumen plans unless it is properly corrected.PACS number: 87.53.Jw
Energy response of EBT3 radiochromic films: implications for dosimetry in kilovoltage range
Authors: Eduardo Villarreal‐Barajas J. , Khan Rao F.H. 
Published: February 2017

The objective of this study is to evaluate the suitability of recently introduced radiochromic film EBT3 for clinical dosimetry in the kilovoltage (kV) range. For this purpose, a kV X‐ray irradiator, X RAD 320ix in the range 70 to 300 kVp, a clinical source, a 6 MV and an 18 MV X‐ray clinical beam from a Varian linear accelerator were calibrated following AAPM dosimetry protocols. EBT3 films from two different EBT3 batches were placed side‐by‐side on the surface of a water phantom; doses from 0.5 to 4 Gy were delivered. Similarly, irradiations were performed for and 6 and 18 MV beams in a water‐equivalent phantom. Films were reproducibly placed at the center of a flatbed scanner and 48‐bit RGB scans were obtained both pre‐ and postirradiations. Net optical density (netOD) and response for a given radiation quality relative to was determined for each EBT3 film. The netOD of the red color showed reproducible response (within 1%) for both batches when irradiated using the source. For a given dose of 1 Gy of kVp X‐ray, the response relative to using the three color channels (red, green, and blue) decreases with decrease in kVp, reaching a maximum underresponse of for the 70 kVp. A significant underresponse of was observed at 300 kVp. Responses of MV X‐ray beams with respect to at the 1 Gy dose level showed no statistically significant difference. A relatively small difference in the response was observed between the two EBT3 batches used in this study in the kV X‐ray range.PACS numbers: 87.56.B, 87.57.uq
Monte Carlo calculation of beam quality correction for solid‐state detectors and phantom scatter correction at 137Cs energy
Authors: Selvam T. Palani , Mishra Subhalaxmi , Vishwakarma R.S. 
Published: February 2017

Beam quality correction , which reflects the absorbed energy dependence of the detector, is calculated for solid‐state detector materials diamond, LiF, , and for the RTR brachytherapy source using the Monte Carlo‐based EGSnrc code system. The study also includes calculation of detector‐specific phantom scatter corrections for solid phantoms such as PMMA, polystyrene, RW1, solid water, virtual water, and plastic water. Above corrections are calculated as a function of distance r along the transverse axis of the source. is about unity for the detector. LiF detector shows a gradual decrease in with r (decrease is about 2% over the distance range of 1‐15 cm). Diamond detector shows a gradual increase in with r (about 3% larger than unity at 15 cm). In the case of detector, decreases with r steeply (about 14% over the distance range of 1‐15 cm). The study shows that some solid‐state detectors demonstrate distance‐dependent values, but the degree of deviation from unity depends on the type of solid phantom and the detector.PACS number: 87.10.Rt, 87.53.Bn, 87.53.Jw, 87.56.Bg
Monte Carlo‐based investigation of absorbed‐dose energy dependence of radiochromic films in high energy brachytherapy dosimetry
Authors: Subhalaxmi Mishra , Selvam T. Palani 
Published: February 2017

Relative absorbed dose energy response correction, R, for various radiochromic films in water phantom is calculated by the use of the Monte Carlo‐based EGSnrc code system for high energy brachytherapy sources , , and . The corrections are calculated along the transverse axis of the sources (1‐15 cm). The radiochromic films investigated are EBT, EBT2 (lot 020609 and lot 031109), RTQA, XRT, XRQA, and HS. For the source, the value of R is about unity and is independent of distance in the water phantom for films other than XRT and XRQA. The XRT and XRQA films showed distance‐dependent R values for this source (the values of R at 15 cm from the source in water are 1.845 and 2.495 for the films XRT and XRQA, respectively). In the case of and sources, XRT, XRQA, EBT2 (lot 031109), and HS films showed distant‐dependent R values. The rest of the films showed no energy dependence (HS film showed R values less than unity by about 5%, whereas the other films showed R values higher than unity). In the case of source, the EBT film showed no energy dependence and EBT2 film (lot 031109) showed a distance‐independent R value of 1.041. The rest of the films showed distance‐dependent R values (increases with distance for the films other than HS). The solid phantoms PMMA and polystyrene enhance the R values for some films when compared the same in the water phantom.PACS number: 87.53.Jw
Dependency of planned dose perturbation (PDP) on the spatial resolution of MapCHECK 2 detectors
Authors: Keeling Vance P. , Ahmad Salahuddin , Algan Ozer , Jin Hosang 
Published: February 2017

The purpose of this study is to determine the dependency of the planned dose perturbation (PDP) algorithm (used in Sun Nuclear 3DVH software) on spatial resolution of the MapCHECK 2 detectors. In this study, ten brain (small target), ten brain (large target), ten prostate, and ten head‐and‐neck (H&N) cases were retrospectively selected for QA measurement. IMRT validation plans were delivered using the field‐by‐field technique with the MapCHECK 2 device. The measurements were performed using standard detector density (standard resolution; SR) and a doubled detector density (high resolution; HR) by merging regular with shifted measurements. SR and HR measurements were fed into the 3DVH software and ROI (region of interest), planning target volume (PTV), and organ at risk (OAR)) dose statistics (. and ) were determined for each. Differences of the dose statistics normalized to prescription dose for ROIs between original planning and PDP‐perturbed planning were calculated for and , and difference between and was also calculated. In addition, 2D and 3D γ passing rates (GPRs) were determined for both resolutions, and a correlation between GPRs and or for PTV dose metrics was determined. No considerably high mean differences between and were found for almost all ROIs and plans (); however, , and for PTV were found to significantly increase as the PTV size decreased (e.g., ). And statistically significant differences between SR and HR were observed for OARs proximal to targets in large brain target and H&N cases. As plan modulation represented by fractional MU/prescription dose (MU/cGy) became more complex, the 2D/3D GPRs tended to decrease; however, the modulation complexity did not make any noticeable distinctions in the DVH statistics of PTV between SR and HR, excluding the small brain cases whose PTVs were extremely small (). Moderate to strong negative correlations () between GPRs and PTV dose metrics indicated that small clinical errors for PTV occur at the higher GPRs. In conclusion, doubling the detector density of the MapCHECK 2 device is recommended for small targets (i.e., ) and multiple targets with complex geometry with minimum setup error in the DVH‐based plan evaluation.PACS numbers: 87.55.dk, 87.55.kd, 87.55.km, 87.55.Qr, 87.56.Fc
Measurement of gantry rotation time in modern ct
Authors: Fukuda Atsushi , Lin Pei‐Jan P. , Matsubara Kosuke , Miyati Tosiaki 
Published: February 2017

The purpose of this study was to develop and evaluate a noninvasive method to assess rotation time in modern commercial computed tomography (CT) systems. The rotation time was measured at a selected nominal rotation time (400 ms) utilizing two types of solid‐state detectors: the RTI's CT Dose Profiler (CTDP) and Unfors’ Xi (Xi) probes. Either CTDP or Xi was positioned on the inner cover of the gantry and a sheet of lead (1 mm thick) placed on top of the detector. Since a pair of two successive peaks is used to determine the gantry rotation time, by necessity the helical scan must be employed. Upon completion of the data acquisition, these peak times were determined with the dedicated software to obtain rotation time. The average rotation time obtained with CTDP and Xi operated under the dedicated software was found to be 400.6 and 400.5 ms, respectively. The detector for this measurement need not be specifically designed for CT dosimetry. The measurements of CT scanner rotation time can be accomplished with a radiation probe designed for the CT application or a conventional radiation probe designed for radiography and fluoroscopy applications. It is also noteworthy to point out that the measurement results are in good agreement between the two radiation detector systems. Finally, clinical medical physicists should be aware of the accuracy and precision of gantry rotation time, and take into consideration for QA where and when applicable.PACS number: 87.57.Q‐
Primary peritoneal clear cell carcinoma treated with IMRT and interstitial HDR brachytherapy: a case report
Authors: Johnson Skyler B. , Prisciandaro Joann I. , Zhou Jessica , Hadley Scott W. , Reynolds R. Kevin , Jolly Shruti 
Published: February 2017

Primary peritoneal clear cell carcinoma (PP‐CCC), which is a rare tumor with poor prognosis, is typically managed with surgery and/or chemotherapy. We present a unique treatment approach for a patient with a pelvic PP‐CCC, consisting of postchemotherapy intensity‐modulated radiation therapy (IMRT) followed by interstitial high‐dose–rate (HDR) brachytherapy. A 54‐year‐old female with an inoperable pelvic‐supravaginal 5.6 cm T3N0M0 PP‐CCC tumor underwent treatment with 6 cycles of carboplatin and taxol chemotherapy. Postchemotherapy PET/CT scan revealed a residual 3.3 cm tumor. The patient underwent CT and MR planning simulation, and was treated with 50 Gy to the primary tumor and 45 Gy to the pelvis including the pelvic lymph nodes, using IMRT to spare bowel. Subsequently, the patient was treated with an interstitial HDR brachytherapy implant, planned using both CT and MR scans. A total dose of 15 Gy in 5 Gy fractions over two days was delivered with Ir‐192 HDR brachytherapy. The total prescribed equivalent 2 Gy dose (EQD2) to the HDR planning target volume (PTV) from both the EBRT and HDR treatments ranged between 63 and due to differential dosing of the primary and pelvic targets. The patient tolerated radiotherapy well, except for mild diarrhea not requiring medication. There was no patient‐reported acute toxicity one month following the radiotherapy course. At four months following adjuvant radiation therapy, the patient had near complete resolution of local tumor on PET/CT without any radiation‐associated toxicity. However, the patient was noted to have metastatic disease outside of the radiation field, specifically lesions in the liver and bone. This case report illustrates the feasibility of the treatment of a pelvic PP‐CCC with IMRT followed by interstitial HDR brachytherapy boost, which resulted in near complete local tumor response without significant morbidity.PACS number: 87.55.‐x
A bias‐free, automated planning tool for technique comparison in radiotherapy ‐ application to nasopharyngeal carcinoma treatments
Authors: Boylan Christopher , Rowbottom Carl 
Published: February 2017

In this study a novel, user‐independent automated planning technique was developed to objectively compare volumetric‐modulated arc therapy (VMAT) and intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma planning, and to determine which technique offers a greater benefit for parotid‐sparing and dose escalation strategies. Ten patients were investigated, with a standard prescription of three dose levels to the target volumes (70, 63, and 56 Gy), using a simultaneous integrated boost in 33 fractions. The automated tool was used to investigate three planning strategies with both IMRT and VMAT: clinically acceptable plan creation, parotid dose sparing, and dose escalation. Clinically acceptable plans were achieved for all patients using both techniques. For parotid‐sparing, automated planning reduced the mean dose to a greater extent using VMAT rather than IMRT (17.0 Gy and 19.6 Gy, respectively, ). For dose escalation to the mean of the main clinical target volume, neither VMAT nor IMRT offered a significant benefit over the other. The OAR‐limiting prescriptions for VMAT ranged from 84‐98 Gy, compared to 76‐110 Gy for IMRT. Employing a user‐independent planning technique, it was possible to objectively compare VMAT and IMRT for nasopharyngeal carcinoma treatment strategies. VMAT offers a parotid‐sparing improvement, but no significant benefit was observed for dose escalation to the primary target.PACS numbers: 87.55.D‐, 87.55.kd
Accuracy quantification of a deformable image registration tool applied in a clinical setting
Authors: Hoffmann Christoph , Krause Sonja , Stoiber Eva Maria , Mohr Angela , Rieken Stefan , Schramm Oliver , Debus Jürgen , Sterzing Florian , Bendl Rolf , Giske Kristina 
Published: February 2017

The purpose of this study was to test the accuracy of a commercially available deformable image registration tool in a clinical situation. In addition, to demonstrate a method to evaluate the resulting transformation of such a tool to a reference defined by multiple experts. For 16 patients (seven head and neck, four thoracic, five abdominal), 30‐50 anatomical landmarks were defined on recognizable spots of a planning CT and a corresponding fraction CT. A commercially available deformable image registration tool, Velocity AI, was used to align all fraction CTs with the respective planning CTs. The registration accuracy was quantified by means of the target registration error in respect to expert‐defined landmarks, considering the interobserver variation of five observers. The interobserver uncertainty of the landmark definition in our data sets is found to be . In general the deformable image registration tool decreases the extent of observable misalignments from 4‐8 mm to 1‐4 mm for nearly 50% of the landmarks (to 77% in sum). Only small differences are observed in the alignment quality of scans with different tumor location. Smallest residual deviations were achieved in scans of the head and neck region () and the thoracic cases (), followed by the abdominal cases (). No difference is observed in the alignment quality of different tissue types (bony vs. soft tissue). The investigated commercially available deformable image registration tool is capable of reducing a mean target registration error to a level that is clinically acceptable for the evaluation of retreatment plans and replanning in case of gross tumor change during treatment. Yet, since the alignment quality needs to be improved further, the individual result of the deformable image registration tool has still to be judged by the physician prior to application.PACS numbers: 87.57.nj, 87.57.N‐, 87.55.‐x
Defining internal target volume using positron emission tomography for radiation therapy planning of moving lung tumors
Authors: Riegel Adam C. , Bucci M. Kara , Mawlawi Osama R. , Ahmad Moiz , Luo Dershan , Chandler Adam , Pan Tinsu 
Published: February 2017

Substantial disagreement exists over appropriate PET segmentation techniques for non‐small cell lung cancer. Currently, no segmentation algorithm explicitly considers tumor motion in determining tumor borders. We developed an automatic PET segmentation model as a function of target volume, motion extent, and source‐to‐background ratio (the VMSBR model). The purpose of this work was to apply the VMSBR model and six other segmentation algorithms to a sample of lung tumors. PET and 4D CT were performed in the same imaging session for 23 patients (24 tumors) for radiation therapy planning. Internal target volumes (ITVs) were autosegmented on maximum intensity projection (MIP) of cine CT. ITVs were delineated on PET using the following methods: 15%, 35%, and 42% of maximum activity concentration, standardized uptake value (SUV) of 2.5 g/mL, 15% of mean activity concentration plus background, a linear function of mean SUV, and the VMSBR model. Predicted threshold values from each method were compared to measured optimal threshold values, and resulting volume magnitudes were compared to cine‐CT‐derived ITV Correlation between predicted and measured threshold values ranged from slopes of 0.29 for the simplest single‐threshold techniques to 0.90 for the VMSBR technique. values ranged from 0.07 for the simplest single‐threshold techniques to 0.86 for the VMSBR technique. The VMSBR segmentation technique that included volume, motion, and source‐to‐background ratio, produced accurate ITVs in patients when compared with cine‐CT‐derived ITV.PACS number: 87.57.nm
Medical Physics Residency Consortium: collaborative endeavors to meet the ABR 2014 certification requirements
Authors: Parker Brent C. , Duhon John , Yang Claus C. , Wu H. Terry , Hogstrom Kenneth R. , Gibbons John P. 
Published: February 2017

In 2009, Mary Bird Perkins Cancer Center (MBPCC) established a Radiation Oncology Physics Residency Program to provide opportunities for medical physics residency training to MS and PhD graduates of the CAMPEP‐accredited Louisiana State University (LSU)‐MBPCC Medical Physics Graduate Program. The LSU‐MBPCC Program graduates approximately six students yearly, which equates to a need for up to twelve residency positions in a two‐year program. To address this need for residency positions, MBPCC has expanded its Program by developing a Consortium consisting of partnerships with medical physics groups located at other nearby clinical institutions. The consortium model offers the residents exposure to a broader range of procedures, technology, and faculty than available at the individual institutions. The Consortium institutions have shown a great deal of support from their medical physics groups and administrations in developing these partnerships. Details of these partnerships are specified within affiliation agreements between MBPCC and each participating institution. All partner sites began resident training in 2011. The Consortium is a network of for‐profit, nonprofit, academic, community, and private entities. We feel that these types of collaborative endeavors will be required nationally to reach the number of residency positions needed to meet the 2014 ABR certification requirements and to maintain graduate medical physics training programs.PACS numbers: 01.40.Fk, 01.40.gb
Evaluation of radiation dose to organs during kilovoltage cone‐beam computed tomography using Monte Carlo simulation
Authors: Son Kihong , Cho Seungryong , Kim Jin Sung , Han Youngyih , Ju Sang Gyu , Choi Doo Ho 
Published: February 2017

Image‐guided techniques for radiation therapy have improved the precision of radiation delivery by sparing normal tissues. Cone‐beam computed tomography (CBCT) has emerged as a key technique for patient positioning and target localization in radiotherapy. Here, we investigated the imaging radiation dose delivered to radiosensitive organs of a patient during CBCT scan. The 4D extended cardiac‐torso (XCAT) phantom and Geant4 Application for Tomographic Emission (GATE) Monte Carlo (MC) simulation tool were used for the study. A computed tomography dose index (CTDI) standard polymethyl methacrylate (PMMA) phantom was used to validate the MC‐based dosimetric evaluation. We implemented an MC model of a clinical on‐board imager integrated with the Trilogy accelerator. The MC model's accuracy was validated by comparing its weighted CTDI (CTDIw) values with those of previous studies, which revealed good agreement. We calculated the absorbed doses of various human organs at different treatment sites such as the head‐and‐neck, chest, abdomen, and pelvis regions, in both standard CBCT scan mode (125 kVp, 80 mA, and 25 ms) and low‐dose scan mode (125 kVp, 40 mA, and 10 ms). In the former mode, the average absorbed doses of the organs in the head and neck and chest regions ranged 4.09‐8.28 cGy, whereas those of the organs in the abdomen and pelvis regions were 4.30‐7.48 cGy. In the latter mode, the absorbed doses of the organs in the head and neck and chest regions ranged 1.61‐1.89 cGy, whereas those of the organs in the abdomen and pelvis region ranged between 0.79‐1.85 cGy. The reduction in the radiation dose in the low‐dose mode compared to the standard mode was about 20%, which is in good agreement with previous reports. We opine that the findings of this study would significantly facilitate decisions regarding the administration of extra imaging doses to radiosensitive organs.PACS number: 87.57.uq
Improving image accuracy of region‐of‐interest in cone‐beam CT using prior image
Authors: Lee Jiseoc , Kim Jin Sung , Cho Seungryong 
Published: February 2017

In diagnostic follow‐ups of diseases, such as calcium scoring in kidney or fat content assessment in liver using repeated CT scans, quantitatively accurate and consistent CT values are desirable at a low cost of radiation dose to the patient. Region‐of‐interest (ROI) imaging technique is considered a reasonable dose reduction method in CT scans for its shielding geometry outside the ROI. However, image artifacts in the reconstructed images caused by missing data outside the ROI may degrade overall image quality and, more importantly, can decrease image accuracy of the ROI substantially. In this study, we propose a method to increase image accuracy of the ROI and to reduce imaging radiation dose via utilizing the outside ROI data from prior scans in the repeated CT applications. We performed both numerical and experimental studies to validate our proposed method. In a numerical study, we used an XCAT phantom with its liver and stomach changing their sizes from one scan to another. Image accuracy of the liver has been improved as the error decreased from 44.4 HU to −0.1 HU by the proposed method, compared to an existing method of data extrapolation to compensate for the missing data outside the ROI. Repeated cone‐beam CT (CBCT) images of a patient who went through daily CBCT scans for radiation therapy were also used to demonstrate the performance of the proposed method experimentally. The results showed improved image accuracy inside the ROI. The magnitude of error decreased from −73.2 HU to 18 HU, and effectively reduced image artifacts throughout the entire image.PACS number: 87.57. Q‐