Xiaodong Zhao, Markus Baur, Phillip D. H. Wall, Eric Laugeman
Background
Quality assurance (QA) remains unstandardized for CT-guided online adaptive radiotherapy (CTgART) platforms (Ethos, Varian Medical Systems, Inc., Palo Alto, CA), as they become more clinically prevalent. A secondary dose calculation software (Mobius3D, Varian Medical Systems, Inc., Palo Alto, CA) is provided for this closed CTgART system. However, the clinical impact of tuning dosimetric leaf gap (DLG) correction values for specific delivery techniques for CTgART secondary dose calculations remains uninvestigated.
Purpose
Tuning the DLG correction value for different delivery techniques of the independent secondary dose verification software for adaptive online QA.
Methods
A total of 31 volumetric arc therapy (VMAT) and 13 fixed-gantry intensity modulated radiation therapy (IMRT) plans were selected from representative anatomical sites treated in our clinic. All plans were evaluated on a patient CT dataset and a QA dataset of a solid water phantom with an embedded ion chamber placed at the center in both primary treatment planning systems (TPS) and secondary dose verification software. Primary TPS plan doses were compared with secondary calculation doses on patient CT by calculating 3D gamma passing criteria under different DLG correction values ranging from –2 to 2 mm to determine the optimal DLG correction range. Ion chamber verification measurements were then compared to secondary calculation dose to determine the optimal DLG correction value by minimizing the difference for IMRT and VMAT plans, separately.
Results
The optimal DLG correction values for VMAT and IMRT techniques were –0.3 and 0.4 mm respectively for the selected clinical cohort of patients. The mean gamma passing rate between primary and secondary doses for VMAT and IMRT were 99.0% ± 1.0% and 99.9% ± 0.1% with 3%/2 mm and excluding 10% low dose criteria. The mean ion chamber agreement for VMAT and IMRT were 0.0% ± 2.1% and 0.2% ± 1.4%.
Conclusion
DLG correction value should be tuned for each delivery technique (VMAT and IMRT) separately to maximize the robustness of CTgART online QA programs.
背景：ct引导的在线适应性放疗（CTgART）平台（Ethos, Varian Medical Systems, Inc., Palo Alto， CA）的质量保证（QA）仍未标准化，因为它们在临床上越来越普遍。二次剂量计算软件（Mobius3D, Varian Medical Systems, Inc., Palo Alto， CA）为这个封闭的CTgART系统提供。然而，调整剂量学叶间隙（DLG）校正值对CTgART二次剂量计算的特定递送技术的临床影响仍未得到研究。目的：调整自适应在线QA中独立二次剂量验证软件不同给药技术的DLG校正值。方法：选取31个体积弧线治疗方案（VMAT）和13个固定门调强放射治疗方案（IMRT），均为临床代表性解剖部位。在初级治疗计划系统（TPS）和次级剂量验证软件中，所有计划都在患者CT数据集和固体水幻影的QA数据集上进行评估，固体水幻影的中心放置了嵌入式离子室。通过计算不同DLG校正值（-2 ~ 2mm）下的三维伽马通过标准，比较TPS计划初始剂量与患者CT的二次计算剂量，确定最佳DLG校正范围。然后将离子室验证测量值与二次计算剂量进行比较，分别通过最小化IMRT和VMAT计划的差异来确定最佳DLG校正值。结果：对于选定的临床队列患者，VMAT和IMRT技术的最佳DLG矫正值分别为-0.3和0.4 mm。VMAT和IMRT一次和二次剂量的平均伽玛通过率分别为99.0%±1.0%和99.9%±0.1%，为3%/2 mm，不包括10%的低剂量标准。VMAT和IMRT的平均离子室一致性分别为0.0%±2.1%和0.2%±1.4%。结论：为使CTgART在线质量保证程序的稳健性最大化，应分别对VMAT和IMRT两种给药技术的DLG校正值进行调整。
{"title":"Tuning a secondary dose verification software for a CT-guided online adaptive delivery system","authors":"Xiaodong Zhao, Markus Baur, Phillip D. H. Wall, Eric Laugeman","doi":"10.1002/acm2.14563","DOIUrl":"10.1002/acm2.14563","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Quality assurance (QA) remains unstandardized for CT-guided online adaptive radiotherapy (CTgART) platforms (Ethos, Varian Medical Systems, Inc., Palo Alto, CA), as they become more clinically prevalent. A secondary dose calculation software (Mobius3D, Varian Medical Systems, Inc., Palo Alto, CA) is provided for this closed CTgART system. However, the clinical impact of tuning dosimetric leaf gap (DLG) correction values for specific delivery techniques for CTgART secondary dose calculations remains uninvestigated.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Tuning the DLG correction value for different delivery techniques of the independent secondary dose verification software for adaptive online QA.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A total of 31 volumetric arc therapy (VMAT) and 13 fixed-gantry intensity modulated radiation therapy (IMRT) plans were selected from representative anatomical sites treated in our clinic. All plans were evaluated on a patient CT dataset and a QA dataset of a solid water phantom with an embedded ion chamber placed at the center in both primary treatment planning systems (TPS) and secondary dose verification software. Primary TPS plan doses were compared with secondary calculation doses on patient CT by calculating 3D gamma passing criteria under different DLG correction values ranging from –2 to 2 mm to determine the optimal DLG correction range. Ion chamber verification measurements were then compared to secondary calculation dose to determine the optimal DLG correction value by minimizing the difference for IMRT and VMAT plans, separately.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The optimal DLG correction values for VMAT and IMRT techniques were –0.3 and 0.4 mm respectively for the selected clinical cohort of patients. The mean gamma passing rate between primary and secondary doses for VMAT and IMRT were 99.0% ± 1.0% and 99.9% ± 0.1% with 3%/2 mm and excluding 10% low dose criteria. The mean ion chamber agreement for VMAT and IMRT were 0.0% ± 2.1% and 0.2% ± 1.4%.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>DLG correction value should be tuned for each delivery technique (VMAT and IMRT) separately to maximize the robustness of CTgART online QA programs.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.14563","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142749977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Junjie Ruan, Xiaotong Huang, Tong Wang, Xiuying Mai, Chuyan Lin, Fanghua Li, Yunfeng Li, Feng Chi, Bin Li
Objective: The objective of this study is to evaluate the impact of different belly board and daily changes in patient's body-mass factor (BMF) on setup displacement in radiotherapy for rectal cancer.
Methods: Twenty-five patients were immobilized using the thermoplastic mask with belly board (TM-BB), and 30 used the vacuum bag cushion with belly board (VBC-BB), performing daily cone-beam computed tomography (CBCT) scans 625 times and 750 times, respectively. Daily pretreatment CBCT scans were registered to the planned CT images for BMF change determination and setup displacement measurement. Independent t-tests compared setup displacement between the two groups in left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions, as well as the BMF changes. The impact of daily BMF changes on setup displacement was evaluated using multivariate logistic regression and 10-fold cross-validation.
Results: The setup displacement for TM-BB in the LR, SI, and AP directions were 0.31 ± 0.25, 0.58 ± 0.40, and 0.19 ± 0.18 cm, respectively, while VBC-BB showed 0.19 ± 0.15, 0.26 ± 0.22, and 0.36 ± 0.29 cm in the corresponding directions, respectively. Margins of planning target volume (PTV) for TM-BB were 8, 10, and 6 mm in LR, SI, and AP directions, while VBC-BB showed margins of 5,7, and 8 mm, respectively. The daily BMF changes for both groups were ranked in descending order as follows: sacral rotation angle (RS), hip lateral diameter (HLD), and hip anterior-posterior diameter (HAPD). HAPD was the main factor affecting setup displacement in both the AP and SI directions in TM-BB, while RS was the primary factor for setup displacement in the AP direction in VBC-BB.
Conclusion: Compared with TM-BB, VBC-BB had a larger AP displacement but smaller in LR and SI displacement. Daily changes in BMF have distinct effects on setup displacement in different immobilization devices. Image-guided radiation therapy (IGRT) is highly recommended and BMF changes should be given consideration during radiotherapy.
{"title":"Impact of belly board immobilization devices and body mass factor on setup displacement using daily cone-beam CT in rectal cancer radiotherapy.","authors":"Junjie Ruan, Xiaotong Huang, Tong Wang, Xiuying Mai, Chuyan Lin, Fanghua Li, Yunfeng Li, Feng Chi, Bin Li","doi":"10.1002/acm2.14573","DOIUrl":"https://doi.org/10.1002/acm2.14573","url":null,"abstract":"<p><strong>Objective: </strong>The objective of this study is to evaluate the impact of different belly board and daily changes in patient's body-mass factor (BMF) on setup displacement in radiotherapy for rectal cancer.</p><p><strong>Methods: </strong>Twenty-five patients were immobilized using the thermoplastic mask with belly board (TM-BB), and 30 used the vacuum bag cushion with belly board (VBC-BB), performing daily cone-beam computed tomography (CBCT) scans 625 times and 750 times, respectively. Daily pretreatment CBCT scans were registered to the planned CT images for BMF change determination and setup displacement measurement. Independent t-tests compared setup displacement between the two groups in left-right (LR), superior-inferior (SI), and anterior-posterior (AP) directions, as well as the BMF changes. The impact of daily BMF changes on setup displacement was evaluated using multivariate logistic regression and 10-fold cross-validation.</p><p><strong>Results: </strong>The setup displacement for TM-BB in the LR, SI, and AP directions were 0.31 ± 0.25, 0.58 ± 0.40, and 0.19 ± 0.18 cm, respectively, while VBC-BB showed 0.19 ± 0.15, 0.26 ± 0.22, and 0.36 ± 0.29 cm in the corresponding directions, respectively. Margins of planning target volume (PTV) for TM-BB were 8, 10, and 6 mm in LR, SI, and AP directions, while VBC-BB showed margins of 5,7, and 8 mm, respectively. The daily BMF changes for both groups were ranked in descending order as follows: sacral rotation angle (RS), hip lateral diameter (HLD), and hip anterior-posterior diameter (HAPD). HAPD was the main factor affecting setup displacement in both the AP and SI directions in TM-BB, while RS was the primary factor for setup displacement in the AP direction in VBC-BB.</p><p><strong>Conclusion: </strong>Compared with TM-BB, VBC-BB had a larger AP displacement but smaller in LR and SI displacement. Daily changes in BMF have distinct effects on setup displacement in different immobilization devices. Image-guided radiation therapy (IGRT) is highly recommended and BMF changes should be given consideration during radiotherapy.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14573"},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142751028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Emily Draeger, Fada Guan, Min-Young Lee, Dae Yup Han, William Donahue, Zhe Jay Chen
Purpose: In vivo dosimetry is a common requirement to validate dose accuracy/uniformity in total body irradiation (TBI). Several detectors can be used for in vivo dosimetry, including thermoluminescent dosimeters (TLDs), diodes, ion chambers, optically stimulated luminescent dosimeters (OSLDs), and film. TLDs are well established for use in vivo but required expertise and clinical system availability may make them impractical for multifractionated TBI. OSLDs offer quick readout, but recalls have restricted their use. The purpose of this work was to validate the newly available Gafchromic EBT4 film for TBI in vivo dosimetry.
Methods: Film calibration curves were created under standard conditions (6MV/15MV, 1.5/3.0 cm depth, 100 cm source-to-surface distance (SSD), 10 × 10 cm2 field), and films were scanned at several time points (0.5-24 h) to determine the shortest development time that yielded accurate dose measurements. 4 × 4 cm2 films were placed under 1.5 cm thick bolus on the anterior and posterior sides of a solid water phantom to measure entrance and exit dose under TBI conditions (∼600 cm SSD, 39.5 × 39.5 cm2 field, 6 MV/15 MV). These measurements were compared to ion chamber and diode readings for validation. Film measurements were also compared to OSLD measurements for three TBI patients.
Results: The shortest development time that resulted in accurate dosimetry and allowed for adequate physician review time was 4 h (± 4% dose accuracy). Film entrance and exit dose measurements were within ± 3.8% of ion chamber and diode readings for 6MV and 15MV beams. Patient film measurements were within ∼ ± 5% for the majority of anatomical measurement locations; however, film and OSLD readings for some anatomic locations deviated by > 10%.
Conclusions: These results indicate that EBT4 film can be utilized for accurate in vivo dosimetry for TBI patients and shows good agreement with diode and ion chamber measurements. Further investigation into film and OSLD differences was not possible due to OSLD recalls.
{"title":"Clinical use of Gafchromic EBT4 film for in vivo dosimetry for total body irradiation.","authors":"Emily Draeger, Fada Guan, Min-Young Lee, Dae Yup Han, William Donahue, Zhe Jay Chen","doi":"10.1002/acm2.14574","DOIUrl":"https://doi.org/10.1002/acm2.14574","url":null,"abstract":"<p><strong>Purpose: </strong>In vivo dosimetry is a common requirement to validate dose accuracy/uniformity in total body irradiation (TBI). Several detectors can be used for in vivo dosimetry, including thermoluminescent dosimeters (TLDs), diodes, ion chambers, optically stimulated luminescent dosimeters (OSLDs), and film. TLDs are well established for use in vivo but required expertise and clinical system availability may make them impractical for multifractionated TBI. OSLDs offer quick readout, but recalls have restricted their use. The purpose of this work was to validate the newly available Gafchromic EBT4 film for TBI in vivo dosimetry.</p><p><strong>Methods: </strong>Film calibration curves were created under standard conditions (6MV/15MV, 1.5/3.0 cm depth, 100 cm source-to-surface distance (SSD), 10 × 10 cm<sup>2</sup> field), and films were scanned at several time points (0.5-24 h) to determine the shortest development time that yielded accurate dose measurements. 4 × 4 cm<sup>2</sup> films were placed under 1.5 cm thick bolus on the anterior and posterior sides of a solid water phantom to measure entrance and exit dose under TBI conditions (∼600 cm SSD, 39.5 × 39.5 cm<sup>2</sup> field, 6 MV/15 MV). These measurements were compared to ion chamber and diode readings for validation. Film measurements were also compared to OSLD measurements for three TBI patients.</p><p><strong>Results: </strong>The shortest development time that resulted in accurate dosimetry and allowed for adequate physician review time was 4 h (± 4% dose accuracy). Film entrance and exit dose measurements were within ± 3.8% of ion chamber and diode readings for 6MV and 15MV beams. Patient film measurements were within ∼ ± 5% for the majority of anatomical measurement locations; however, film and OSLD readings for some anatomic locations deviated by > 10%.</p><p><strong>Conclusions: </strong>These results indicate that EBT4 film can be utilized for accurate in vivo dosimetry for TBI patients and shows good agreement with diode and ion chamber measurements. Further investigation into film and OSLD differences was not possible due to OSLD recalls.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14574"},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750924","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Niklas Lackner, Lou Dietrich, Andre Karius, Rainer Fietkau, Christoph Bert, Juliane Szkitsak
Purpose
Respiratory-guided computed tomography (CT) typically employs breathing motion surrogates to feed image reconstruction or visual breathing coaching. Our study aimed to assess the impact of table movements and table sag on the breathing curves recorded in four-dimensional (4D) CT and deep-inspiration breath-hold (DIBH) CT.
Methods
For breathing curve measurements, static and dynamic phantom scenarios were used. Breathing curves were recorded using three different surrogate systems and the impact of table sag due to weights of up to 130 kg was analyzed and compared to a non-weighted setting, respectively. The calibration procedure of the system used as an input for the visual coaching device used for clinical DIBH CT scans was adapted. We evaluated corresponding breathing curves acquired during DIBH and 4DCT scans of altogether 70 patients using various stability metrics.
Results
The various surrogate systems showed consistent table sag measurements below 4 mm, even under loads up to 130 kg, compared to a reference scan conducted without additional weight. Higher weight loads were related to steeper table sag fall-offs towards the deepest table position. For DIBH CT scans, the visual guidance was heavily affected by artifacts. This resulted in breathing threshold limits, which could not be achieved by 48% (n = 21) of the, respectively, examined patients. Using the new calibration workflow, the baseline drift was compensated better and 90% (n = 20) of the addressed patients stayed within the thresholds. The evaluated table sag in clinical 4DCT scans (n = 29) stayed below 3 mm compared to the non-weighted situation.
Conclusion
Table movement and sag can impact breathing curves recorded by different surrogate systems. Correcting table movement and sag artifacts is crucial for reliable breathing curve acquisition in respiratory-guided CT.
{"title":"Investigating the effects of table movement and sag on optical surrogate-driven respiratory-guided computed tomography","authors":"Niklas Lackner, Lou Dietrich, Andre Karius, Rainer Fietkau, Christoph Bert, Juliane Szkitsak","doi":"10.1002/acm2.14565","DOIUrl":"10.1002/acm2.14565","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Respiratory-guided computed tomography (CT) typically employs breathing motion surrogates to feed image reconstruction or visual breathing coaching. Our study aimed to assess the impact of table movements and table sag on the breathing curves recorded in four-dimensional (4D) CT and deep-inspiration breath-hold (DIBH) CT.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>For breathing curve measurements, static and dynamic phantom scenarios were used. Breathing curves were recorded using three different surrogate systems and the impact of table sag due to weights of up to 130 kg was analyzed and compared to a non-weighted setting, respectively. The calibration procedure of the system used as an input for the visual coaching device used for clinical DIBH CT scans was adapted. We evaluated corresponding breathing curves acquired during DIBH and 4DCT scans of altogether 70 patients using various stability metrics.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The various surrogate systems showed consistent table sag measurements below 4 mm, even under loads up to 130 kg, compared to a reference scan conducted without additional weight. Higher weight loads were related to steeper table sag fall-offs towards the deepest table position. For DIBH CT scans, the visual guidance was heavily affected by artifacts. This resulted in breathing threshold limits, which could not be achieved by 48% (<i>n</i> = 21) of the, respectively, examined patients. Using the new calibration workflow, the baseline drift was compensated better and 90% (<i>n</i> = 20) of the addressed patients stayed within the thresholds. The evaluated table sag in clinical 4DCT scans (<i>n</i> = 29) stayed below 3 mm compared to the non-weighted situation.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Table movement and sag can impact breathing curves recorded by different surrogate systems. Correcting table movement and sag artifacts is crucial for reliable breathing curve acquisition in respiratory-guided CT.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.14565","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142751029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Objectives: This study proposes a novel approach, "Low-energy photon Lipiodol-Enhanced Radiotherapy" (LEPERT), for patients with liver cancer. Moreover, we evaluate the dose difference of the conventional treatment planning with 10 MV X-ray beam (MV-plan) and LEPERT.
Methods: The computed tomography (CT) was modeled with the Monte Carlo simulation. For LEPERT, 120 kV X-ray beams collimated with CT were irradiated on a virtual tumor filled with Lipiodol at 10-50 mg/mL, which was inserted into a whole-body phantom. A prescribed dose of 40 Gy/4fr was irradiated to achieve D95% of the target. The doses to the target and organs at risk (OARs), such as the bone, normal liver, spinal cord, and kidneys, were evaluated by comparison with conventional radiotherapy with a 10 MV VMAT plan (MV-plan).
Results: Differences in the effective energy and off-axis ratio between the measurements and simulations were within 2 keV and 3%, respectively. The D2% of tumors exceeded 130% of the prescribed dose at 50 mg. The difference in the D98% of the tumor between LEPERT and MV-plan was within 0.7 Gy. The V5Gy of the normal liver (>40 mg/mL) was lower for LEPERT than for MV-plan. The V20Gy of the normal liver (>10 mg/mL) for LEPERT was over 80% lower than that for MV-plan. Dose constraints for the OARs were satisfied.
Conclusion: The LEPERT can selectively enhanced only the tumor region with sparing the OAR dose. It could be a novel and effective treatment technique in the point that the treatment machine is a general CT device.
{"title":"Enhancing targeted doses: Low-energy photon lipiodol-enhanced radiotherapy (LEPERT) for liver cancer patients.","authors":"Daisuke Kawahara","doi":"10.1002/acm2.14578","DOIUrl":"https://doi.org/10.1002/acm2.14578","url":null,"abstract":"<p><strong>Objectives: </strong>This study proposes a novel approach, \"Low-energy photon Lipiodol-Enhanced Radiotherapy\" (LEPERT), for patients with liver cancer. Moreover, we evaluate the dose difference of the conventional treatment planning with 10 MV X-ray beam (MV-plan) and LEPERT.</p><p><strong>Methods: </strong>The computed tomography (CT) was modeled with the Monte Carlo simulation. For LEPERT, 120 kV X-ray beams collimated with CT were irradiated on a virtual tumor filled with Lipiodol at 10-50 mg/mL, which was inserted into a whole-body phantom. A prescribed dose of 40 Gy/4fr was irradiated to achieve D<sub>95%</sub> of the target. The doses to the target and organs at risk (OARs), such as the bone, normal liver, spinal cord, and kidneys, were evaluated by comparison with conventional radiotherapy with a 10 MV VMAT plan (MV-plan).</p><p><strong>Results: </strong>Differences in the effective energy and off-axis ratio between the measurements and simulations were within 2 keV and 3%, respectively. The D<sub>2%</sub> of tumors exceeded 130% of the prescribed dose at 50 mg. The difference in the D<sub>98%</sub> of the tumor between LEPERT and MV-plan was within 0.7 Gy. The V<sub>5Gy</sub> of the normal liver (>40 mg/mL) was lower for LEPERT than for MV-plan. The V<sub>20Gy</sub> of the normal liver (>10 mg/mL) for LEPERT was over 80% lower than that for MV-plan. Dose constraints for the OARs were satisfied.</p><p><strong>Conclusion: </strong>The LEPERT can selectively enhanced only the tumor region with sparing the OAR dose. It could be a novel and effective treatment technique in the point that the treatment machine is a general CT device.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14578"},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750928","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Giulianne Rivelli R. Zaratim, Luis Felipe Oliveira e Silva, Ricardo G. dos Reis, Cristiano Jacques M. R. Mendes, Marília Miranda F. Gomes
Purpose
This study aimed to identify the fluence smoothing threshold that preserves the dosimetric quality of planning for breast cancer intensity-modulated radiation therapy (IMRT).
Material and methods
We conducted automated treatment planning for 60 breast cancer patients using the Eclipse Scripting Application Programming Interface. The plans included four-field IMRT, emphasizing smoothing weight combinations while maintaining a 4:3 aspect ratio between the X and Y directions. Four weight sets (40 × 30, 100 × 75, 150 × 115.2, and 200 × 150) were tested, resulting in four plans per patient. A total dose of 40.05 Gy over 15 fractions was prescribed. Optimization weigths were dynamically adjusted based on dosimetric evaluations, with the maximum coverage priority set at 200. Statistical analyses were used to assess the dosimetric data.
Results
The median planning target volume (PTV) coverage varied across smoothing levels, with default smoothing (40 × 30) providing superior median PTV coverage. Lung constraints showed significant differences mainly at higher smoothing levels. Heart constraints exhibited less variation between smoothing levels, with significant differences primarily in the maximum and mean doses for right-sided patients and between default and higher smoothing levels for left-sided patients. No significant differences were observed in contralateral breast constraints among all smoothing levels, except at the maximum level for right-sided patients. Monitor units decreased with increasing smoothing weight, showing significant differences between default and other settings. For right-sided patients, the median number of monitor units varied from 1346 (40 × 30) to 754 (200 × 150), and for left-sided patients, from 1333 (40 × 30) to 804 (200 × 150). Chi-square tests revealed differences in dose constraint adherence between default and maximum smoothing levels, particularly in target coverage.
Conclusion
Our findings suggest that using a ratio of smoothing weights to target priorities between 1:1.5 and 1:1.6 leads to a favorable balance between complexity and dosimetric plan quality, with no significant impacts on dose constraint adherence.
{"title":"Fluence smoothing evaluation for whole-breast automatically generated treatment plans","authors":"Giulianne Rivelli R. Zaratim, Luis Felipe Oliveira e Silva, Ricardo G. dos Reis, Cristiano Jacques M. R. Mendes, Marília Miranda F. Gomes","doi":"10.1002/acm2.14564","DOIUrl":"10.1002/acm2.14564","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>This study aimed to identify the fluence smoothing threshold that preserves the dosimetric quality of planning for breast cancer intensity-modulated radiation therapy (IMRT).</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Material and methods</h3>\u0000 \u0000 <p>We conducted automated treatment planning for 60 breast cancer patients using the Eclipse Scripting Application Programming Interface. The plans included four-field IMRT, emphasizing smoothing weight combinations while maintaining a 4:3 aspect ratio between the X and Y directions. Four weight sets (40 × 30, 100 × 75, 150 × 115.2, and 200 × 150) were tested, resulting in four plans per patient. A total dose of 40.05 Gy over 15 fractions was prescribed. Optimization weigths were dynamically adjusted based on dosimetric evaluations, with the maximum coverage priority set at 200. Statistical analyses were used to assess the dosimetric data.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The median planning target volume (PTV) coverage varied across smoothing levels, with default smoothing (40 × 30) providing superior median PTV coverage. Lung constraints showed significant differences mainly at higher smoothing levels. Heart constraints exhibited less variation between smoothing levels, with significant differences primarily in the maximum and mean doses for right-sided patients and between default and higher smoothing levels for left-sided patients. No significant differences were observed in contralateral breast constraints among all smoothing levels, except at the maximum level for right-sided patients. Monitor units decreased with increasing smoothing weight, showing significant differences between default and other settings. For right-sided patients, the median number of monitor units varied from 1346 (40 × 30) to 754 (200 × 150), and for left-sided patients, from 1333 (40 × 30) to 804 (200 × 150). Chi-square tests revealed differences in dose constraint adherence between default and maximum smoothing levels, particularly in target coverage.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>Our findings suggest that using a ratio of smoothing weights to target priorities between 1:1.5 and 1:1.6 leads to a favorable balance between complexity and dosimetric plan quality, with no significant impacts on dose constraint adherence.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.14564","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hongwei Zeng, Qi Chen, Xiangyu E, Yue Feng, Minghe Lv, Su Zeng, Wenhao Shen, Wenhui Guan, Yang Zhang, Ruping Zhao, Shaobin Wang, Jingping Yu
Background
Lung cancer poses a significant global health challenge. Adaptive radiotherapy (ART) addresses uncertainties due to lung tumor dynamics. We aimed to investigate a comprehensively and systematically validated offline ART regimen with high clinical feasibility for lung cancer.
Methods
This study enrolled 102 lung cancer patients, who underwent kV iterative cone-beam computed tomography (iCBCT). Data collection included iCBCT and planning CT (pCT) scans. Among these, data from 70 patients were employed for training the UNet++ based deep learning model, while 15 patients were allocated for testing the model. The model transformed iCBCT into adaptive CT (aCT). Clinical radiotherapy feasibility was verified in 17 patients. The dosimetric evaluation encompassed GTV, organs at risk (OARs), and monitor units (MU), while delivery accuracy was validated using ArcCHECK and thermoluminescent dosimeter (TLD) detectors.
Results
The UNet++ based deep learning model substantially improved image quality, reducing mean absolute error (MAE) by 70.05%, increasing peak signal-to-noise ratio (PSNR) by 17.97%, structural similarity (SSIM) by 7.41%, and the Hounsfield Units (HU) of aCT approaching a closer proximity to pCT compared to kV iCBCT. There were no significant differences observed in the dosimetric parameters of GTV and OARs between the aCT and pCT plans, confirming the accuracy of the dose maps in ART plans. Similarly, MU manifested no notable disparities, underscoring the consistency in treatment efficiency. Gamma passing rates for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans derived from aCT and pCT exceeded 98%, while the deviations in TLD measurements (within 2% to 7%) also exhibited no significant differences, thus corroborating the precision of dose delivery.
Conclusion
An offline ART regimen utilizing kV iCBCT and UNet++ based deep learning model is clinically feasible for lung cancer treatment. This approach provides enhanced image quality, comparable treatment plans to pCT, and precise dose delivery.
{"title":"Assessment of clinical feasibility:offline adaptive radiotherapy for lung cancer utilizing kV iCBCT and UNet++ based deep learning model","authors":"Hongwei Zeng, Qi Chen, Xiangyu E, Yue Feng, Minghe Lv, Su Zeng, Wenhao Shen, Wenhui Guan, Yang Zhang, Ruping Zhao, Shaobin Wang, Jingping Yu","doi":"10.1002/acm2.14582","DOIUrl":"10.1002/acm2.14582","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>Lung cancer poses a significant global health challenge. Adaptive radiotherapy (ART) addresses uncertainties due to lung tumor dynamics. We aimed to investigate a comprehensively and systematically validated offline ART regimen with high clinical feasibility for lung cancer.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>This study enrolled 102 lung cancer patients, who underwent kV iterative cone-beam computed tomography (iCBCT). Data collection included iCBCT and planning CT (pCT) scans. Among these, data from 70 patients were employed for training the UNet++ based deep learning model, while 15 patients were allocated for testing the model. The model transformed iCBCT into adaptive CT (aCT). Clinical radiotherapy feasibility was verified in 17 patients. The dosimetric evaluation encompassed GTV, organs at risk (OARs), and monitor units (MU), while delivery accuracy was validated using ArcCHECK and thermoluminescent dosimeter (TLD) detectors.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The UNet++ based deep learning model substantially improved image quality, reducing mean absolute error (MAE) by 70.05%, increasing peak signal-to-noise ratio (PSNR) by 17.97%, structural similarity (SSIM) by 7.41%, and the Hounsfield Units (HU) of aCT approaching a closer proximity to pCT compared to kV iCBCT. There were no significant differences observed in the dosimetric parameters of GTV and OARs between the aCT and pCT plans, confirming the accuracy of the dose maps in ART plans. Similarly, MU manifested no notable disparities, underscoring the consistency in treatment efficiency. Gamma passing rates for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) plans derived from aCT and pCT exceeded 98%, while the deviations in TLD measurements (within 2% to 7%) also exhibited no significant differences, thus corroborating the precision of dose delivery.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>An offline ART regimen utilizing kV iCBCT and UNet++ based deep learning model is clinically feasible for lung cancer treatment. This approach provides enhanced image quality, comparable treatment plans to pCT, and precise dose delivery.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.14582","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin'ang Jiang, Jun Hu, Qinling Jiang, Taohu Zhou, Fei Yao, Yi Sun, Chao Zhou, Qianyun Ma, Jingyi Zhao, Kang Shi, Wen Yang, Xiuxiu Zhou, Yun Wang, Shiyuan Liu, Xiaoyan Xin, Li Fan
Background
COVID-19 remains widespread and poses a threat to people's physical and mental health, especially middle-aged and elderly individuals. Early identification of COVID-19 patients at high risk of progressing to critical disease helps improve overall patient outcomes and healthcare efficiency.
Purpose
To develop a radiomics nomogram to predict the risk of newly admitted middle-aged and elderly COVID-19 patients progressing to critical disease.
Methods
A total of 794 patients (aged 40 years or above) were retrospectively included in the study from two institutions, all of them were with non-critical COVID-19 on admission. At follow-up, patients were divided into non-critical group and critical group. About 443 patients (384 non-critical and 59 critical) from the first hospital were randomly assigned to the training (n = 311) and internal validation (n = 132) set in a 7:3 ratio. Additionally, an independent external cohort of 351 patients (292 non-critical and 59 critical) from another hospital was evaluated. Radiomics signatures and clinical indicators were used to build a radiomics model and a clinical model after computed tomography (CT) image processing, CT whole-lung segmentation, feature extraction, and feature selection. The radiomics nomogram model integrated radiomics model and clinical model. The receiver operating characteristic curve (AUC) was used to assess the performance of the proposed models. Calibration curves and decision curve analysis were used to assess the performance of the radiomics nomogram.
Results
For the training, internal validation, and external validation sets, the AUC values of the radiomic nomogram for the prediction of COVID-19 progression were 0.916, 0.917, and 0.890, respectively. Calibration curves indicated that there was no significant departure between prediction and observation in three sets. The decision curve image demonstrated the clinical utility of the nomogram model.
Conclusions
Our nomogram model incorporates radiomics features and clinical indicators, it provides a new pathway to increase predictive accuracy or clinical utility, further helping to provide personalized management for middle-aged and elderly patients with COVID-19.
{"title":"CT-based whole lung radiomics nomogram to identify middle-aged and elderly COVID-19 patients at high risk of progressing to critical disease","authors":"Xin'ang Jiang, Jun Hu, Qinling Jiang, Taohu Zhou, Fei Yao, Yi Sun, Chao Zhou, Qianyun Ma, Jingyi Zhao, Kang Shi, Wen Yang, Xiuxiu Zhou, Yun Wang, Shiyuan Liu, Xiaoyan Xin, Li Fan","doi":"10.1002/acm2.14562","DOIUrl":"10.1002/acm2.14562","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Background</h3>\u0000 \u0000 <p>COVID-19 remains widespread and poses a threat to people's physical and mental health, especially middle-aged and elderly individuals. Early identification of COVID-19 patients at high risk of progressing to critical disease helps improve overall patient outcomes and healthcare efficiency.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>To develop a radiomics nomogram to predict the risk of newly admitted middle-aged and elderly COVID-19 patients progressing to critical disease.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>A total of 794 patients (aged 40 years or above) were retrospectively included in the study from two institutions, all of them were with non-critical COVID-19 on admission. At follow-up, patients were divided into non-critical group and critical group. About 443 patients (384 non-critical and 59 critical) from the first hospital were randomly assigned to the training (<i>n</i> = 311) and internal validation (<i>n</i> = 132) set in a 7:3 ratio. Additionally, an independent external cohort of 351 patients (292 non-critical and 59 critical) from another hospital was evaluated. Radiomics signatures and clinical indicators were used to build a radiomics model and a clinical model after computed tomography (CT) image processing, CT whole-lung segmentation, feature extraction, and feature selection. The radiomics nomogram model integrated radiomics model and clinical model. The receiver operating characteristic curve (AUC) was used to assess the performance of the proposed models. Calibration curves and decision curve analysis were used to assess the performance of the radiomics nomogram.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>For the training, internal validation, and external validation sets, the AUC values of the radiomic nomogram for the prediction of COVID-19 progression were 0.916, 0.917, and 0.890, respectively. Calibration curves indicated that there was no significant departure between prediction and observation in three sets. The decision curve image demonstrated the clinical utility of the nomogram model.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusions</h3>\u0000 \u0000 <p>Our nomogram model incorporates radiomics features and clinical indicators, it provides a new pathway to increase predictive accuracy or clinical utility, further helping to provide personalized management for middle-aged and elderly patients with COVID-19.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.14562","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jin Hwa Choi, Hyejo Ryu, Do Hoon Oh, Lee Yoo, Minsoo Chun
Purpose: This study aimed to assess the dosimetric advantages of dual arc increments in head and neck volumetric-modulated arc therapy (VMAT) in the Monaco treatment planning system (TPS).
Methods: Three VMAT plans were created for each of the 10 patients by prescribing 70 Gy in 35 fractions with arc increment combinations of 30°/30°, 15°/15°, and 30°/15° in the Monaco TPS. The dose to 0.03 cm3 volume (D0.03cc), conformity number, and homogeneity and gradient indices was compared for the planning target volume (PTV), and the D0.03cc and mean dose (Dmean) of the spinal cord, brain stem, parotid glands were compared. For plan complexity evaluation, the monitor unit and various related metrics were compared. Wilcoxon signed-rank tests were performed across plans for the evaluated indicators.
Results: For PTV, plans with 30°/15° showed comparable D0.03cc and homogeneity and gradient indices to those of plans with 30°/30° and 15°/15° while exhibiting a better conformity number. The D0.03cc for spinal cord and brain stem for plans with 30°/15° were 26.0% and 20.8% less than those with 30°/30° and 16.8% and 19.0% less than those with 15°/15°, respectively. The Dmean for the left and right parotid glands under plans with 30°/15° were 17.4% and 13.2% less than those with 30°/30° and 14.0% and 9.8% less than those with 15°/15°, respectively. The total monitor unit in plans with 30°/15° was less than that in other plans but with no significance. The plans with 30°/15° showed higher modulation complexity and plan-averaged irregularity, while no significant differences observed in both plan-averaged area and modulation compared with other plans.
Conclusion: In head and neck VMAT, a dual arc increment of 30°/15° seems advisable because it can substantially reduce doses to normal tissues with comparable delivery efficiency while maintaining target dose coverage.
{"title":"Dosimetric advantages of dual arc increments for head and neck volumetric-modulated arc therapy in the Monaco treatment planning system.","authors":"Jin Hwa Choi, Hyejo Ryu, Do Hoon Oh, Lee Yoo, Minsoo Chun","doi":"10.1002/acm2.14571","DOIUrl":"https://doi.org/10.1002/acm2.14571","url":null,"abstract":"<p><strong>Purpose: </strong>This study aimed to assess the dosimetric advantages of dual arc increments in head and neck volumetric-modulated arc therapy (VMAT) in the Monaco treatment planning system (TPS).</p><p><strong>Methods: </strong>Three VMAT plans were created for each of the 10 patients by prescribing 70 Gy in 35 fractions with arc increment combinations of 30°/30°, 15°/15°, and 30°/15° in the Monaco TPS. The dose to 0.03 cm<sup>3</sup> volume (D<sub>0.03cc</sub>), conformity number, and homogeneity and gradient indices was compared for the planning target volume (PTV), and the D<sub>0.03cc</sub> and mean dose (D<sub>mean</sub>) of the spinal cord, brain stem, parotid glands were compared. For plan complexity evaluation, the monitor unit and various related metrics were compared. Wilcoxon signed-rank tests were performed across plans for the evaluated indicators.</p><p><strong>Results: </strong>For PTV, plans with 30°/15° showed comparable D<sub>0.03cc</sub> and homogeneity and gradient indices to those of plans with 30°/30° and 15°/15° while exhibiting a better conformity number. The D<sub>0.03cc</sub> for spinal cord and brain stem for plans with 30°/15° were 26.0% and 20.8% less than those with 30°/30° and 16.8% and 19.0% less than those with 15°/15°, respectively. The D<sub>mean</sub> for the left and right parotid glands under plans with 30°/15° were 17.4% and 13.2% less than those with 30°/30° and 14.0% and 9.8% less than those with 15°/15°, respectively. The total monitor unit in plans with 30°/15° was less than that in other plans but with no significance. The plans with 30°/15° showed higher modulation complexity and plan-averaged irregularity, while no significant differences observed in both plan-averaged area and modulation compared with other plans.</p><p><strong>Conclusion: </strong>In head and neck VMAT, a dual arc increment of 30°/15° seems advisable because it can substantially reduce doses to normal tissues with comparable delivery efficiency while maintaining target dose coverage.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14571"},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ivan L. Cordrey, Sare Kucuk, Chester Ramsey, Joseph Bowling, Dharmin D. Desai
Purpose
Minimizing intermediate dose spill in stereotactic radiosurgery (SRS) for brain treatment is crucial. Intermediate dose spill correlates with the exposure of normal brain tissue to high doses, which increases the risk of radionecrosis. R50%, defined as the volume of the 50% of prescription isodose cloud/planning target volume, is one metric for intermediate dose spill. A predictive model for R50% in linear accelerator VMAT-delivered SRS has been developed Desai et al. (2020) and is called R50%Analytic. This study extends the R50%Analytic model to Gamma Knife (GK) delivered SRS, resulting in the R50%Analytic-GK model.
Methods
Phantom calculations were performed on 11 spherical target volumes ranging from 0.001 to 44 cm3 to develop the R50%Analytic-GK model. R50%Analytic-GK was tested against clinical data from 18 brain metastasis cases with one to 11 targets treated on GK Icon and planned in GammaPlan with lightning dose optimizer. Thirty-five targets with volumes between 0.011 and 27.4 cm3 were analyzed by extracting the R50% achieved clinically (R50%Clinical) for comparison to the predicted intermediate dose spill from R50%Analytic-GK.
Results
The predicted R50%Analytic-GK values generally represent a lower bound for the R50%Clinical values as the model would predict. The Difference, R50%Clinical − R50%Analytic-GK, has a median value of 0.92, which quantifies the lower bound nature of R50%Analytic-GK. The model reflected the character of intermediate dose spill for the clinical cases. A few outliers were likely due to specific planning complexities.
Conclusion
The R50%Analytic-GK model for intermediate dose spill successfully extends the theoretical framework of R50%Analytic to GK-delivered SRS. It provides a method to predict the intermediate dose spill for GK Icon treatments. This model can aid in assessing SRS treatment plans by providing a benchmark for the intermediate dose spill for comparison.
{"title":"A predictive model for Gamma Knife intermediate dose spill: R50%Analytic-GK","authors":"Ivan L. Cordrey, Sare Kucuk, Chester Ramsey, Joseph Bowling, Dharmin D. Desai","doi":"10.1002/acm2.14579","DOIUrl":"10.1002/acm2.14579","url":null,"abstract":"<div>\u0000 \u0000 \u0000 <section>\u0000 \u0000 <h3> Purpose</h3>\u0000 \u0000 <p>Minimizing intermediate dose spill in stereotactic radiosurgery (SRS) for brain treatment is crucial. Intermediate dose spill correlates with the exposure of normal brain tissue to high doses, which increases the risk of radionecrosis. R50%, defined as the volume of the 50% of prescription isodose cloud/planning target volume, is one metric for intermediate dose spill. A predictive model for R50% in linear accelerator VMAT-delivered SRS has been developed Desai et al. (2020) and is called R50%<sub>Analytic</sub>. This study extends the R50%<sub>Analytic</sub> model to Gamma Knife (GK) delivered SRS, resulting in the R50%<sub>Analytic-GK</sub> model.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Methods</h3>\u0000 \u0000 <p>Phantom calculations were performed on 11 spherical target volumes ranging from 0.001 to 44 cm<sup>3</sup> to develop the R50%<sub>Analytic-GK</sub> model. R50%<sub>Analytic-GK</sub> was tested against clinical data from 18 brain metastasis cases with one to 11 targets treated on GK Icon and planned in GammaPlan with lightning dose optimizer. Thirty-five targets with volumes between 0.011 and 27.4 cm<sup>3</sup> were analyzed by extracting the R50% achieved clinically (R50%<sub>Clinical</sub>) for comparison to the predicted intermediate dose spill from R50%<sub>Analytic-GK</sub>.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Results</h3>\u0000 \u0000 <p>The predicted R50%<sub>Analytic-GK</sub> values generally represent a lower bound for the R50%<sub>Clinical</sub> values as the model would predict. The Difference, R50%<sub>Clinical</sub> − R50%<sub>Analytic-GK</sub>, has a median value of 0.92, which quantifies the lower bound nature of R50%<sub>Analytic-GK</sub>. The model reflected the character of intermediate dose spill for the clinical cases. A few outliers were likely due to specific planning complexities.</p>\u0000 </section>\u0000 \u0000 <section>\u0000 \u0000 <h3> Conclusion</h3>\u0000 \u0000 <p>The R50%<sub>Analytic-GK</sub> model for intermediate dose spill successfully extends the theoretical framework of R50%<sub>Analytic</sub> to GK-delivered SRS. It provides a method to predict the intermediate dose spill for GK Icon treatments. This model can aid in assessing SRS treatment plans by providing a benchmark for the intermediate dose spill for comparison.</p>\u0000 </section>\u0000 </div>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":"26 2","pages":""},"PeriodicalIF":2.0,"publicationDate":"2024-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/acm2.14579","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142750823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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