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Tara Rosewall - One of the best experts on this subject based on the ideXlab platform.
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impact of image registration surrogates on the Planning Target Volume geometry for bladder radiation therapy
Practical radiation oncology, 2016Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Maisie Kwan, Peter Chung, J MoseleyAbstract:Abstract Purpose The use of Lipiodol and cone beam computed tomography (CT) has facilitated the generation of patient-specific Planning Target Volumes (PTV) to reduce irradiation of normal tissue. However, injecting Lipiodol to demarcate the Target Volume is an invasive procedure. Center of bladder (COB) and bladder wall surface (BWS) encompassed by the clinical Target Volume (CTV) are proposed to be the alternative noninvasive surrogates. This study examines the impact of using these 3 surrogates for image registration on the resultant geometry of patient-specific PTVs. Methods and materials Twenty bladder cancer patients who had Lipiodol injection before Planning CT were included. Lipiodol, CTV, and bladder were delineated on the Planning CT. In addition, CTVs were delineated on 5 cone beam CT scans from each patient. Cone beam CT scans were registered to Planning CT using Lipiodol, COB, and BWS to generate Lipiodol-PTV, COB-PTV, and BWS-PTV. Using Lipiodol as the reference, the difference in the 2-dimensional/3-dimensional displacement values and the geometry of the resultant PTVs were quantified. Results A total of 1200 displacement values and 60 Volumes were included for analysis. The overall median and standard deviation (SD) of the 3-dimensional displacement (mm) measured by Lipiodol, BWS, and COB are 25 (SD, 15), 24 (SD, 14), and 21 (SD, 15), respectively. Lipiodol-PTV has the smallest mean Volume, followed by BWS-PTV and COB-PTV. BWS-PTV was more geometrically similar to Lipiodol-PTV when compared with COB-PTV. Six of 20 COB-PTVs who had CTV located at either the dome or the base of the bladder were larger than the corresponding Lipiodol-PTV by more than 20%. Conclusion Lipiodol is the optimal image registration surrogate for partial bladder radiation therapy. However, for patients who are contraindicated for Lipiodol injection, BWS is the preferred noninvasive surrogate because the derived PTV has a smaller geometric variation from the Lipiodol-PTV when compared with COB, especially when the CTV was located at the dome or the base of the bladder.
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deriving patient specific Planning Target Volume for partial bladder image guided radiation therapy
Practical radiation oncology, 2014Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Robert G Bristow, Michael Milosevic, Maisie Kwan, Peter ChungAbstract:Abstract Purpose Image guided radiation therapy (IGRT) using bony anatomy for bladder cancer requires the use of large population-based Planning Target Volume (PTV) margins to compensate for geometric uncertainties. This may result in a large Volume of normal tissue being irradiated unnecessarily. Identification of the clinical Target Volume (CTV) is also a challenge during Target delineation and treatment position verification. This study describes the use of lipiodol (Guerbet, US) and cone beam computed tomography (CBCT) in deriving patient-specific PTV (PS-PTV) for partial bladder IGRT. Methods and materials Twelve patients underwent lipiodol injection into the bladder wall prior to radiation treatment. A PS-PTV was generated by the following: (1) Delineating partial bladder CTV (CTVpb) on 15 CBCTs; (2) registering the CBCTs with the Planning CT image using lipiodol; (3) c ombining the 15 CTVpb to create an occupancy Volume (OV); and (4) expanding the OV by 3 mm. Its efficacy in reducing irradiated Volume and in providing coverage was assessed by comparing it with a 20-mm population-based PTV (popPTV) and using phase 2 CBCTs. Results The median PS-PTV and popPTV (cm 3 ) were 102 (range, 37-336) and 325 (range, 211-631), respectively. Median distance between the CTVpb and the PS-PTV edge (mm) were 6 superior, 6 right, 7 left, 7 anterior, 8 posterior, and 11 inferior. The absolute median reduction in the overlapping Volume of rectum, small bowel, and large bowel were 0.3 cm 3 , 5.3 cm 3 , and 13.0 cm 3 , respectively. Despite large reductions in Volume and margin compared with popPTV, PS-PTV achieved 100% Target coverage. Conclusions Using lipiodol and CBCT to derive PS-PTV facilitated large reductions in the irradiated normal tissue Volume without compromising Target coverage.
Peter Chung - One of the best experts on this subject based on the ideXlab platform.
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impact of image registration surrogates on the Planning Target Volume geometry for bladder radiation therapy
Practical radiation oncology, 2016Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Maisie Kwan, Peter Chung, J MoseleyAbstract:Abstract Purpose The use of Lipiodol and cone beam computed tomography (CT) has facilitated the generation of patient-specific Planning Target Volumes (PTV) to reduce irradiation of normal tissue. However, injecting Lipiodol to demarcate the Target Volume is an invasive procedure. Center of bladder (COB) and bladder wall surface (BWS) encompassed by the clinical Target Volume (CTV) are proposed to be the alternative noninvasive surrogates. This study examines the impact of using these 3 surrogates for image registration on the resultant geometry of patient-specific PTVs. Methods and materials Twenty bladder cancer patients who had Lipiodol injection before Planning CT were included. Lipiodol, CTV, and bladder were delineated on the Planning CT. In addition, CTVs were delineated on 5 cone beam CT scans from each patient. Cone beam CT scans were registered to Planning CT using Lipiodol, COB, and BWS to generate Lipiodol-PTV, COB-PTV, and BWS-PTV. Using Lipiodol as the reference, the difference in the 2-dimensional/3-dimensional displacement values and the geometry of the resultant PTVs were quantified. Results A total of 1200 displacement values and 60 Volumes were included for analysis. The overall median and standard deviation (SD) of the 3-dimensional displacement (mm) measured by Lipiodol, BWS, and COB are 25 (SD, 15), 24 (SD, 14), and 21 (SD, 15), respectively. Lipiodol-PTV has the smallest mean Volume, followed by BWS-PTV and COB-PTV. BWS-PTV was more geometrically similar to Lipiodol-PTV when compared with COB-PTV. Six of 20 COB-PTVs who had CTV located at either the dome or the base of the bladder were larger than the corresponding Lipiodol-PTV by more than 20%. Conclusion Lipiodol is the optimal image registration surrogate for partial bladder radiation therapy. However, for patients who are contraindicated for Lipiodol injection, BWS is the preferred noninvasive surrogate because the derived PTV has a smaller geometric variation from the Lipiodol-PTV when compared with COB, especially when the CTV was located at the dome or the base of the bladder.
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deriving patient specific Planning Target Volume for partial bladder image guided radiation therapy
Practical radiation oncology, 2014Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Robert G Bristow, Michael Milosevic, Maisie Kwan, Peter ChungAbstract:Abstract Purpose Image guided radiation therapy (IGRT) using bony anatomy for bladder cancer requires the use of large population-based Planning Target Volume (PTV) margins to compensate for geometric uncertainties. This may result in a large Volume of normal tissue being irradiated unnecessarily. Identification of the clinical Target Volume (CTV) is also a challenge during Target delineation and treatment position verification. This study describes the use of lipiodol (Guerbet, US) and cone beam computed tomography (CBCT) in deriving patient-specific PTV (PS-PTV) for partial bladder IGRT. Methods and materials Twelve patients underwent lipiodol injection into the bladder wall prior to radiation treatment. A PS-PTV was generated by the following: (1) Delineating partial bladder CTV (CTVpb) on 15 CBCTs; (2) registering the CBCTs with the Planning CT image using lipiodol; (3) c ombining the 15 CTVpb to create an occupancy Volume (OV); and (4) expanding the OV by 3 mm. Its efficacy in reducing irradiated Volume and in providing coverage was assessed by comparing it with a 20-mm population-based PTV (popPTV) and using phase 2 CBCTs. Results The median PS-PTV and popPTV (cm 3 ) were 102 (range, 37-336) and 325 (range, 211-631), respectively. Median distance between the CTVpb and the PS-PTV edge (mm) were 6 superior, 6 right, 7 left, 7 anterior, 8 posterior, and 11 inferior. The absolute median reduction in the overlapping Volume of rectum, small bowel, and large bowel were 0.3 cm 3 , 5.3 cm 3 , and 13.0 cm 3 , respectively. Despite large reductions in Volume and margin compared with popPTV, PS-PTV achieved 100% Target coverage. Conclusions Using lipiodol and CBCT to derive PS-PTV facilitated large reductions in the irradiated normal tissue Volume without compromising Target coverage.
Timothy J Craig - One of the best experts on this subject based on the ideXlab platform.
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impact of image registration surrogates on the Planning Target Volume geometry for bladder radiation therapy
Practical radiation oncology, 2016Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Maisie Kwan, Peter Chung, J MoseleyAbstract:Abstract Purpose The use of Lipiodol and cone beam computed tomography (CT) has facilitated the generation of patient-specific Planning Target Volumes (PTV) to reduce irradiation of normal tissue. However, injecting Lipiodol to demarcate the Target Volume is an invasive procedure. Center of bladder (COB) and bladder wall surface (BWS) encompassed by the clinical Target Volume (CTV) are proposed to be the alternative noninvasive surrogates. This study examines the impact of using these 3 surrogates for image registration on the resultant geometry of patient-specific PTVs. Methods and materials Twenty bladder cancer patients who had Lipiodol injection before Planning CT were included. Lipiodol, CTV, and bladder were delineated on the Planning CT. In addition, CTVs were delineated on 5 cone beam CT scans from each patient. Cone beam CT scans were registered to Planning CT using Lipiodol, COB, and BWS to generate Lipiodol-PTV, COB-PTV, and BWS-PTV. Using Lipiodol as the reference, the difference in the 2-dimensional/3-dimensional displacement values and the geometry of the resultant PTVs were quantified. Results A total of 1200 displacement values and 60 Volumes were included for analysis. The overall median and standard deviation (SD) of the 3-dimensional displacement (mm) measured by Lipiodol, BWS, and COB are 25 (SD, 15), 24 (SD, 14), and 21 (SD, 15), respectively. Lipiodol-PTV has the smallest mean Volume, followed by BWS-PTV and COB-PTV. BWS-PTV was more geometrically similar to Lipiodol-PTV when compared with COB-PTV. Six of 20 COB-PTVs who had CTV located at either the dome or the base of the bladder were larger than the corresponding Lipiodol-PTV by more than 20%. Conclusion Lipiodol is the optimal image registration surrogate for partial bladder radiation therapy. However, for patients who are contraindicated for Lipiodol injection, BWS is the preferred noninvasive surrogate because the derived PTV has a smaller geometric variation from the Lipiodol-PTV when compared with COB, especially when the CTV was located at the dome or the base of the bladder.
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deriving patient specific Planning Target Volume for partial bladder image guided radiation therapy
Practical radiation oncology, 2014Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Robert G Bristow, Michael Milosevic, Maisie Kwan, Peter ChungAbstract:Abstract Purpose Image guided radiation therapy (IGRT) using bony anatomy for bladder cancer requires the use of large population-based Planning Target Volume (PTV) margins to compensate for geometric uncertainties. This may result in a large Volume of normal tissue being irradiated unnecessarily. Identification of the clinical Target Volume (CTV) is also a challenge during Target delineation and treatment position verification. This study describes the use of lipiodol (Guerbet, US) and cone beam computed tomography (CBCT) in deriving patient-specific PTV (PS-PTV) for partial bladder IGRT. Methods and materials Twelve patients underwent lipiodol injection into the bladder wall prior to radiation treatment. A PS-PTV was generated by the following: (1) Delineating partial bladder CTV (CTVpb) on 15 CBCTs; (2) registering the CBCTs with the Planning CT image using lipiodol; (3) c ombining the 15 CTVpb to create an occupancy Volume (OV); and (4) expanding the OV by 3 mm. Its efficacy in reducing irradiated Volume and in providing coverage was assessed by comparing it with a 20-mm population-based PTV (popPTV) and using phase 2 CBCTs. Results The median PS-PTV and popPTV (cm 3 ) were 102 (range, 37-336) and 325 (range, 211-631), respectively. Median distance between the CTVpb and the PS-PTV edge (mm) were 6 superior, 6 right, 7 left, 7 anterior, 8 posterior, and 11 inferior. The absolute median reduction in the overlapping Volume of rectum, small bowel, and large bowel were 0.3 cm 3 , 5.3 cm 3 , and 13.0 cm 3 , respectively. Despite large reductions in Volume and margin compared with popPTV, PS-PTV achieved 100% Target coverage. Conclusions Using lipiodol and CBCT to derive PS-PTV facilitated large reductions in the irradiated normal tissue Volume without compromising Target coverage.
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sci sat am 1 Planning 08 estimating Planning Target Volume margins for fractionated stereotactic radiotherapy on perfexion
Medical Physics, 2010Co-Authors: Mark Ruschin, Timothy J Craig, N Nayebi, M Tamerou, Y Cho, Cynthia Menard, David A JaffrayAbstract:The purpose of this study was to estimate Planning Target Volume (PTV) margins for frame‐based Perfexion (PFX) SRT using the eXtend™ system's relocatable head frame (RHF). Patients with large brain metastases are currently undergoing hypofractionated (3 fractions) SRT on PFX enrolled on a phase 1 dose‐escalation clinical trial. In prior investigation, the performance of the RHF was quantified using cone‐beam CT (CBCT) in fourteen patients undergoing linac‐based SRT (median: 30 treatment fractions). Standard performance metrics — group mean (μ), systematic (Σ) and random (σ) uncertainties — were determined for frame‐guided positioning and intra‐fraction motion. A published margin‐determination formula (2.5*Σ) +0.7*σ) was used to estimate the PTV margin. An additional factor of (σ/√3) was added to the systematic component of the formula when initially designing the PTV for 3 fractions in PFX‐SRT. To more accurately account for PFX dose distributions and only 3 treatment fractions, a population‐based stochastic modeling approach is being developed to refine the PTV margin for hypofractionated PFX‐SRT. For frame‐guided SRT (30 fractions), the post‐correction positioning performance estimates were μ(position) = {0.1,−0.2,−0.6}mm, Σ(position) = {0.2;0.8;0.6}mm, and σ(position) = {0.3;0.6;0.4}mm in {Right; Superior;Anterior}. For intra‐fraction motion, μ(motion) = {−0.1;−0.1;0.0}mm, Σ(motion) = {0.2;0.2;0.1}mm, and σ(motion)={0.2;0.4;0.2}mm. The margin formula indicated an expansion of {1.0;2.6;1.8}mm and {1.6;3.1;2.3}mm for 30 fractions and 3 fractions, respectively. For three patients treated to date on PFX, μ(position) = (0.2mm;−0.9mm;−0.8mm). To ensure that the GTV receives the prescription dose, PTV margins have been calculated to account for the geometric uncertainties present in PFX‐SRT. The margins will be reviewed as more data are collected, RHF refinements are made, and stochastic‐based modeling is used.
Ning J Yue - One of the best experts on this subject based on the ideXlab platform.
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using respiratory motion to guide Planning Target Volume margins for external beam partial breast irradiation
International Journal of Radiation Oncology Biology Physics, 2012Co-Authors: Leonard Kim, Sharad Goyal, Bruce G Haffty, Neil K Taunk, Ning J YueAbstract:Although toxicity associated with external-beam accelerated partial breast irradiation (APBI) has been reported to be acceptable in some studies, others have shown higher rates of fibrosis and suboptimal cosmesis using the fractionation schedule of 385 cGy twice daily to 3850 cGy. Given that this fractionation schedule may be close to the limits of normal tissue toxicity, any reduction in irradiated normal tissue Volume that can be achieved without compromising Target coverage may have meaningful clinical significance. Recent studies have explored the use of image guidance to reduce the Planning Target Volume (PTV)margin required to accommodate setup errors. There have also been many recent studies of respiratory motion in patients treated with APBI in the supine position (1–19), and it may be time to reevaluate the PTV margin required to accommodate respiratory motion as well. The 19 studies summarized in the following table report a wide range of Target motion that, at its extremes, spans a whole order of magnitude. Harris et al. (19) reported the use of four-dimensional computed tomography (4D-CT) to track gold fiducial markers placed at the periphery of the surgical bed in 15 patients and found that ‘‘the average intrafraction respiration induced fiducial motion was 0.8 mm.’’ By contrast, Yue et al. reported an average CTV motion of 8.5 mm in 4D-CTs of 4 APBI patients (8). Of the 19 studies, the ‘‘take-home’’ motion magnitude was 5 mm in 4 studies. One early study on the larger end of the spectrum is that by Baglan et al. (1). Evaluating surgical clip positions in CTs of 16 patients acquired at normal inspiration and expiration breath-holds, they reported a mean motion of 6 mm (range, 3–9 mm). From this, they suggested that ‘‘a conservative margin of 5 mm around the CTV would completely account for breast motion during quiet respiration in all patients.’’ (Note that if a Target is localized to its midventilation posi-
Vickie Kong - One of the best experts on this subject based on the ideXlab platform.
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impact of image registration surrogates on the Planning Target Volume geometry for bladder radiation therapy
Practical radiation oncology, 2016Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Maisie Kwan, Peter Chung, J MoseleyAbstract:Abstract Purpose The use of Lipiodol and cone beam computed tomography (CT) has facilitated the generation of patient-specific Planning Target Volumes (PTV) to reduce irradiation of normal tissue. However, injecting Lipiodol to demarcate the Target Volume is an invasive procedure. Center of bladder (COB) and bladder wall surface (BWS) encompassed by the clinical Target Volume (CTV) are proposed to be the alternative noninvasive surrogates. This study examines the impact of using these 3 surrogates for image registration on the resultant geometry of patient-specific PTVs. Methods and materials Twenty bladder cancer patients who had Lipiodol injection before Planning CT were included. Lipiodol, CTV, and bladder were delineated on the Planning CT. In addition, CTVs were delineated on 5 cone beam CT scans from each patient. Cone beam CT scans were registered to Planning CT using Lipiodol, COB, and BWS to generate Lipiodol-PTV, COB-PTV, and BWS-PTV. Using Lipiodol as the reference, the difference in the 2-dimensional/3-dimensional displacement values and the geometry of the resultant PTVs were quantified. Results A total of 1200 displacement values and 60 Volumes were included for analysis. The overall median and standard deviation (SD) of the 3-dimensional displacement (mm) measured by Lipiodol, BWS, and COB are 25 (SD, 15), 24 (SD, 14), and 21 (SD, 15), respectively. Lipiodol-PTV has the smallest mean Volume, followed by BWS-PTV and COB-PTV. BWS-PTV was more geometrically similar to Lipiodol-PTV when compared with COB-PTV. Six of 20 COB-PTVs who had CTV located at either the dome or the base of the bladder were larger than the corresponding Lipiodol-PTV by more than 20%. Conclusion Lipiodol is the optimal image registration surrogate for partial bladder radiation therapy. However, for patients who are contraindicated for Lipiodol injection, BWS is the preferred noninvasive surrogate because the derived PTV has a smaller geometric variation from the Lipiodol-PTV when compared with COB, especially when the CTV was located at the dome or the base of the bladder.
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deriving patient specific Planning Target Volume for partial bladder image guided radiation therapy
Practical radiation oncology, 2014Co-Authors: Vickie Kong, Tara Rosewall, Susan Chen, Timothy J Craig, Robert G Bristow, Michael Milosevic, Maisie Kwan, Peter ChungAbstract:Abstract Purpose Image guided radiation therapy (IGRT) using bony anatomy for bladder cancer requires the use of large population-based Planning Target Volume (PTV) margins to compensate for geometric uncertainties. This may result in a large Volume of normal tissue being irradiated unnecessarily. Identification of the clinical Target Volume (CTV) is also a challenge during Target delineation and treatment position verification. This study describes the use of lipiodol (Guerbet, US) and cone beam computed tomography (CBCT) in deriving patient-specific PTV (PS-PTV) for partial bladder IGRT. Methods and materials Twelve patients underwent lipiodol injection into the bladder wall prior to radiation treatment. A PS-PTV was generated by the following: (1) Delineating partial bladder CTV (CTVpb) on 15 CBCTs; (2) registering the CBCTs with the Planning CT image using lipiodol; (3) c ombining the 15 CTVpb to create an occupancy Volume (OV); and (4) expanding the OV by 3 mm. Its efficacy in reducing irradiated Volume and in providing coverage was assessed by comparing it with a 20-mm population-based PTV (popPTV) and using phase 2 CBCTs. Results The median PS-PTV and popPTV (cm 3 ) were 102 (range, 37-336) and 325 (range, 211-631), respectively. Median distance between the CTVpb and the PS-PTV edge (mm) were 6 superior, 6 right, 7 left, 7 anterior, 8 posterior, and 11 inferior. The absolute median reduction in the overlapping Volume of rectum, small bowel, and large bowel were 0.3 cm 3 , 5.3 cm 3 , and 13.0 cm 3 , respectively. Despite large reductions in Volume and margin compared with popPTV, PS-PTV achieved 100% Target coverage. Conclusions Using lipiodol and CBCT to derive PS-PTV facilitated large reductions in the irradiated normal tissue Volume without compromising Target coverage.