{"title":"Dosimetric effect of silicone-based gel on skin surface during volumetric modulated arc therapy for breast cancer.","authors":"Tenyoh Suzuki, Shingo Ohira, Mami Ogita, Takeshi Ohta, Yuki Nozawa, Masanari Minamitani, Takuya Hayashi, Shigeki Saegusa, Toshikazu Imae, Tsuyoshi Ueyama, Atsuto Katano, Hideomi Yamashita, Weishan Chang, Keiichi Nakagawa","doi":"10.1002/acm2.70070","DOIUrl":"https://doi.org/10.1002/acm2.70070","url":null,"abstract":"<p><strong>Purpose: </strong>This study aims to quantify and compare the dosimetric effects of varying thicknesses of StrataXRT, a silicone-based gel, and other topical agents on the skin surface during volumetric modulated arc therapy (VMAT) for breast cancer.</p><p><strong>Methods: </strong>A VMAT plan was created for breast cancer treatment using a female RANDO phantom with a prescription dose of 50 Gy in 25 fractions. The planning target volume (PTV) encompassed the left breast and the regional lymph nodes. Irradiation was performed using a 6 MV photon beam. Three topical agents (StrataXRT, Hirudoid Soft Ointment, and RINDERON-Vs Ointment) having eight thicknesses (0.0-1.5 mm) were evaluated. Dosimetry was conducted using Gafchromic EBT4 films at three anatomical locations-subclavicular, medial, and lateral aspects of the left breast.</p><p><strong>Results: </strong>Mean dose enhancement ratios (DERs) of 102%-116% were observed in VMAT for topical agent thicknesses of 0.1-0.5 mm, increasing to 116%-126% at 1.0 and 1.5 mm. Among the evaluated agents, StrataXRT consistently exhibited the lowest DER, with a statistically significant difference (p < 0.05).</p><p><strong>Conclusions: </strong>This study demonstrated that StrataXRT exhibited the lowest DER among the evaluated topical agents in VMAT for breast cancer. Thicknesses exceeding 0.5 mm potentially exceeded the threshold dose for acute skin reactions.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70070"},"PeriodicalIF":2.0,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143624593","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}
{"title":"Methods for working with problem residents in medical physics residency education.","authors":"Christopher J Watchman, Dandan Zheng","doi":"10.1002/acm2.70068","DOIUrl":"https://doi.org/10.1002/acm2.70068","url":null,"abstract":"<p><p>Medical physics residency training programs may occasionally encounter residents requiring additional intervention beyond normal training efforts. In the literature, these residents are referred to as \"problem\" residents. While the physician literature on the subject is valuable, this paper specifically focuses on dealing with a problem medical physics resident. This work discusses a generalized strategy for addressing and correcting medical physics problem resident issues. A discussion of categories of problems that may be encountered is also presented. Additionally, a standardized process for resident intervention is given, along with a discussion of issues related to transparency and bias. Applying the principles in this work should assist medical physics residency programs in establishing a strong culture where all residents, including those experiencing difficulties, can successfully complete their medical physics residency training. This work is a result of collaborations facilitated by the Society of Directors of Academic Medical Physics Programs (SDAMPP).</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70068"},"PeriodicalIF":2.0,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143624601","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}
Eileen Cirino, Stanley H Benedict, Pamela J Dupre, Per H Halvorsen, Grace Gwe-Ya Kim, Meral L Reyhan, Christopher W Schneider, Lei Wang, Carl P Weaver, Sua Yoo
{"title":"AAPM-RSS Medical Physics Practice Guideline 9.b: SRS-SBRT.","authors":"Eileen Cirino, Stanley H Benedict, Pamela J Dupre, Per H Halvorsen, Grace Gwe-Ya Kim, Meral L Reyhan, Christopher W Schneider, Lei Wang, Carl P Weaver, Sua Yoo","doi":"10.1002/acm2.14624","DOIUrl":"https://doi.org/10.1002/acm2.14624","url":null,"abstract":"<p><p>The purpose of this Medical Physics Practice Guideline (MPPG) is to describe the minimum level of medical physics support deemed prudent for the practice of linear-accelerator, photon-based (linac) stereotactic radiosurgery (SRS), and stereotactic body radiation therapy (SBRT) services. This report is an update of MPPG 9.a<sup>1</sup> published in 2017. As SRS and SBRT services are rapidly adopted into the community-practice setting, this guideline has been developed to build on the work presented in MPPG 9.a and provide current appropriate minimum practice guidelines for such services.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14624"},"PeriodicalIF":2.0,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604827","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}
Rebecca Milman, Nicholas B Bevins, Mosa Alhamami, Nathan Busse, Andreea Dohatcu, Katie W Hulme, Mary Ellen Jafari, Steven M LaFontaine, Richard D Nawfel, Jeffrey S Nelson, Megan K Russ, Michael Silosky, John M Wait
{"title":"AAPM Medical Physics Practice Guideline MPPG 17.a: Quality management for mammography review workstation displays.","authors":"Rebecca Milman, Nicholas B Bevins, Mosa Alhamami, Nathan Busse, Andreea Dohatcu, Katie W Hulme, Mary Ellen Jafari, Steven M LaFontaine, Richard D Nawfel, Jeffrey S Nelson, Megan K Russ, Michael Silosky, John M Wait","doi":"10.1002/acm2.14625","DOIUrl":"https://doi.org/10.1002/acm2.14625","url":null,"abstract":"<p><p>The Mammography Quality Standards Act (MQSA) sets quality standards for displays used to interpret mammography images. With the shift to digital mammography and the widespread use of remote reading workstations (RWS), updated quality management (QM) programs are needed to ensure consistent image presentation and accurate interpretation. This document recommends a QM framework for mammography RWS displays, addressing challenges such as remote environments, regulatory compliance, and evolving technology. The QM model highlights the central role of medical physicists in program design, oversight, and data review. It emphasizes periodic quality assurance (QA) and quality control (QC) procedures and training for interpreting physicians and staff. A structure for QM for remote RWS, including guidance on environmental conditions, hands-on testing, and remote monitoring solutions, is included. The proposed program balances scientific rigor, cost-effectiveness, and practical implementation, maintaining image quality and safety. By providing a structured approach to RWS display management, this framework supports regulators, accreditation bodies, and healthcare facilities in adapting to advancements in mammography technology while addressing logistical and operational challenges.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e14625"},"PeriodicalIF":2.0,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604803","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}
Arttu Ruohola, Ville Haapamäki, Eero Salli, Tuomas Kaseva, Marko Kangasniemi, Sauli Savolainen
{"title":"Bone-wise rigid registration of femur, tibia, and fibula for the tracking of temporal changes.","authors":"Arttu Ruohola, Ville Haapamäki, Eero Salli, Tuomas Kaseva, Marko Kangasniemi, Sauli Savolainen","doi":"10.1002/acm2.70053","DOIUrl":"https://doi.org/10.1002/acm2.70053","url":null,"abstract":"<p><strong>Background: </strong>Multiple myeloma (MM) induces temporal alterations in bone structure, such as osteolytic bone lesions, which are challenging to identify through manual image interpretation. The large variation in radiologists' assessments, even at expert centers, further complicates diagnosis. Automatic image analysis methods, including segmentation and registration, can expedite detecting and tracking these bone changes.</p><p><strong>Purpose: </strong>This study presents an automated pipeline for accurately tracking temporal changes in the femurs, tibiae, and fibulae of MM patients using 3D whole-body CT images. The pipeline leverages image segmentation, rigid registration, and temporal subtraction to accelerate disease monitoring and support clinical decision-making.</p><p><strong>Methods: </strong>A convolutional neural network (CNN) was trained to segment bones in 3D CT images of 30 MM patients. Nine patients with pre- and post-diagnosis CT scans were used to validate the segmentation and registration process. A two-phase bone-wise rigid registration was applied, followed by temporal subtraction to generate difference images. Segmentation and registration accuracy were assessed using the Dice similarity coefficient (DSC) and mean surface distance (MSD). The proposed method was compared to a non-rigid registration method.</p><p><strong>Results: </strong>The neural network segmentation resulted in a mean DSC of 0.93 across all bone types and all test data. The registration accuracy measured by the mean DSC across the test data was at least 0.94 for all bone types. The second phase of rigid registration improved the registration fibulae. Metric-wise, the nonrigid method performed better but diminished lesion visibility in difference images.</p><p><strong>Conclusions: </strong>An automated pipeline for the longitudinal tracking of bone alterations was presented. Both segmentation and registration demonstrated high accuracy as measured by DSC and MSD. In the difference images produced by temporal subtraction, osteolytic lesions were clearly visible in the femurs. The methodology lays a solid foundation for future improvements, such as inclusion of the axial spine.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70053"},"PeriodicalIF":2.0,"publicationDate":"2025-03-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143604828","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}
Sven Olberg, David M McClatchy, Colleen Foote, Susu Yan, Jennifer Pursley
{"title":"Commissioning a standalone adaptive radiotherapy linac in a multi-vendor environment.","authors":"Sven Olberg, David M McClatchy, Colleen Foote, Susu Yan, Jennifer Pursley","doi":"10.1002/acm2.70033","DOIUrl":"https://doi.org/10.1002/acm2.70033","url":null,"abstract":"<p><p>Current radiotherapy machines intended to perform streamlined online adaptive therapy are designed to be standalone, which makes it challenging to integrate them with the rest of the clinic. This work describes the installation of a standalone CT-guided online adaptive system, the Varian Ethos, in a busy clinic utilizing products from multiple vendors, including RayStation as the treatment planning system (TPS) and MOSAIQ as the oncology information system (OIS). The aim was to develop solutions that minimized workload increases for staff using redundant systems and to implement this new technology safely, with no increase in safety reports resulting from its integration into the clinic. The Ethos was delivered with a pre-configured beam model, and a separate Ethos beam model was developed in RayStation 10A. Non-adaptive treatments were planned in RayStation and transferred to Ethos for delivery. Although MOSAIQ 2.64 could not communicate with the Ethos, a machine characterization file was developed to allow manual recording of the treatment fields in MOSAIQ. Online adaptive therapy was performed using the Ethos TPS and OIS with documentation in MOSAIQ. Although dose calculations of the same plans differed by 1%-2% in the pelvis in RayStation compared to the Ethos TPS, dose computed in both systems passed measurement-based QA, end-to-end testing, and clinical trial credentialing, so both systems were commissioned for clinical use. RayStation plans were successfully modified for delivery on Ethos, and at go-live, all non-adaptive planning was performed in RayStation and adaptive planning in Ethos. Ethos treatments were documented in MOSIAQ, which remained the OIS of record for all patients. Monitoring of error reports indicated some unique failure modes to the new technology, but the overall number of safety reports remained comparable to other systems. In conclusion, Ethos was successfully deployed for both non-adaptive and online adaptive therapy in a multi-vendor environment.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70033"},"PeriodicalIF":2.0,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143596896","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}
Luis Agulles-Pedrós, R Lee MacDonald, Amanda Jean Cherpak, Nayha Dixit, Lei Dong, Tianyu Zhao, Kundan Thind, Anthony Doemer, Boon-Keng Teo, Shiqin Su, Alexander Moncion, James L Robar
{"title":"Multi-institutional study on image quality for a novel CBCT solution on O-ring linac.","authors":"Luis Agulles-Pedrós, R Lee MacDonald, Amanda Jean Cherpak, Nayha Dixit, Lei Dong, Tianyu Zhao, Kundan Thind, Anthony Doemer, Boon-Keng Teo, Shiqin Su, Alexander Moncion, James L Robar","doi":"10.1002/acm2.70023","DOIUrl":"https://doi.org/10.1002/acm2.70023","url":null,"abstract":"<p><strong>Introduction: </strong>This work presents a multi-institutional study on image quality provided by a novel cone beam computed tomography (CBCT). The main goal is to investigate the consistency of imaging performance across multiple institutions.</p><p><strong>Methods: </strong>Phantoms for measuring relative electron density (RED) and image quality were sent to six institutions for imaging on Ethos and Halcyon units equipped with HyperSight CBCT. The imaging protocols included tube potential from 100 to 140 kVp and exposure from 80 to 800 mAs. Imaging performance was evaluated with regard to RED versus Hounsfield units (HU), uniformity, contrast-to-noise ratio (CNR), slice thickness, circular symmetry, modulation transfer function (MTF), and spatial resolution.</p><p><strong>Results: </strong>Among all institutions, some variability was observed among institutions in the RED-to-HU relationship, especially for RED values greater than 1, although no outliers were found (|z-score| < 2 in all cases). In this range, RED/HU slopes were 475 ± 25 10<sup>-6</sup> RED/HU at 100kVp, 505 ± 20 10<sup>-6</sup> RED/HU at 125kVp, and 550 ± 20 10<sup>-6</sup> RED/HU at 140kVp. Radial uniformity ranged from 1 to 7 HU, depending on protocol. Circular symmetry for two points 50 mm apart showed consistency within one-pixel dimension. Integral nonuniformity was between 1 and 10, with no difference observed between vertical and horizontal dimensions. Contrast rods with 1% gave CNR = 0.5, 1 and 2 for 100(88), 125(176), and 140(528) in kVp(mAs), and contrast rods with 0.5% had CNR = 0.2, 0.4 and 0.8 for 100(88), 125(176), and 140(528) in kVp(mAs). Spatial resolution given by MTF at 10% and 50% yielded values of 0.55 ± 0.01 mm<sup>-1</sup> and 0.35 ± 0.02 mm<sup>-1</sup>, respectively.</p><p><strong>Conclusions: </strong>This multi-institutional analysis of CBCT imaging performance showed consistency in radial uniformity, circular symmetry, integral nonuniformity, contrast, and spatial resolution. Some variability was seen in the RED-to-HU relationship for RED > 1 depending on exposure. More data from different institutions would be necessary to establish more robust statistical metrics, which ensure quality parameters.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70023"},"PeriodicalIF":2.0,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143573034","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}
{"title":"Stereotactic radiotherapy for metastatic brain tumors: A comparative analysis of dose distributions among VMAT, Helical TomoTherapy, CyberKnife, Gamma Knife, and ZAP-X.","authors":"Toshihiro Suzuki, Masahide Saito, Ryutaro Nomura, Hikaru Nemoto, Naoto Yanagisawa, Ryuma Sawada, Zennosuke Mochizuki, Naoki Sano, Hiroshi Onishi, Hiroshi Takahashi","doi":"10.1002/acm2.70046","DOIUrl":"https://doi.org/10.1002/acm2.70046","url":null,"abstract":"<p><p>This study evaluates various radiotherapy techniques for treating metastatic brain tumor (BT), focusing on non-coplanar volumetric modulated arc radiotherapy (NC-VMAT), coplanar VMAT (C-VMAT), Helical TomoTherapy (HT), CyberKnife (CK), Gamma Knife (GK), and ZAP-X. CT images and structures of 12 patients who underwent CK for a single BT were utilized. Twelve treatment plans were created for each planning device. All plans adopted the approach of prescription doses to planning target volume D99.5%. They were divided into stereotactic radiosurgery (SRS) (prescription dose; 21-23 Gy) and stereotactic radiotherapy (SRT) (prescription dose; 30-36.5 Gy) groups and the same parameters evaluated included Gradient Index (GI), Paddick Conformity Index (CI), and treatment time (t-time). In the SRS group, mean values of GI and CI values were: NC-VMAT (4.28, 0.60), C-VMAT (5.61, 0.44), HT (4.68, 0.42), CK (4.31, 0.61), GK (2.81, 0.82), and ZAP-X (2.99, 0.80). In the SRT group: NC-VMAT (3.27, 0.84), C-VMAT (3.81, 0.82), HT (3.76, 0.65), CK (2.98, 0.77), GK (2.61, 0.90), and ZAP-X (2.80, 0.84). There were no significant differences in the mean values of CI and GI between ZAP-X and GK in both groups (p > 0.05). NC-VMAT and C-VMAT had shorter t-time than other techniques in both groups. ZAP-X is relatively superior in CI and GI for small tumors, similar to GK, while differences with NC-VMAT and CK diminish as tumor volume increases. ZAP-X, CK, and GK have longer t-time than other treatment techniques, regardless of volume.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70046"},"PeriodicalIF":2.0,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143556890","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}
Reham Barghash, Tiffany W Martin, Amber R Prebble, Del Leary
{"title":"Monte Carlo modeling of radiation dose from radiation therapy with superficial x-rays.","authors":"Reham Barghash, Tiffany W Martin, Amber R Prebble, Del Leary","doi":"10.1002/acm2.70062","DOIUrl":"https://doi.org/10.1002/acm2.70062","url":null,"abstract":"<p><strong>Introduction: </strong>Superficial x-rays (50-100 kVp) are used for treating non-melanoma skin cancer and intraoperative radiation therapy (IORT). At these energies, the photoelectric effect significantly increases absorbed dose to bone compared to soft tissue.</p><p><strong>Methods: </strong>We used EGSnrc MC simulations to investigate bone dose enhancement during radiotherapy with the Sensus SRT-100 machine. Simulated beams were validated against laboratory measurements and compared to a commercial treatment planning system (SmART-ATP). Transmission simulations indirectly predicted bone dosage. Simulated beams were utilized as a mock treatment plan from a human cone-beam computed tomography (CBCT) image.</p><p><strong>Results: </strong>EGSnrc accurately modeled the Sensus SRT-100 beams (100, 70, and 50 kVp) with a root mean square error (RMSE) of percentage depth dose ratios between Monte Carlo predictions and lab measurements of 1.66, 0.47, and 0.99, respectively. PDDs from simulations of a water phantom with bone slabs showed peak doses at water-bone interfaces relative to surface doses. At 0.3 cm depth bone slab, doses reached 410%, 490%, and 510% for 50, 70, and 100 kVp, respectively. At 1.5 cm depth, doses were 140%, 215%, and 270%. At 2.5 cm depth, peak doses were 74%, 130%, and 170% for 50, 70, and 100 kVp, respectively. A simulated treatment plan (4 Gy surface dose) using a CBCT of a human head predicted the dose to the skull to be around 20, 19, and 15 Gy for the 100, 70, and 50 kVp beams, respectively.</p><p><strong>Conclusions: </strong>The study demonstrated EGSnrc's efficiency in conjunction with SmART-ATP for treatment planning. MC simulations effectively quantified bone dose enhancement during superficial x-ray radiotherapy, highlighting its importance in treatment planning and dose calculations. Clinicians should consider measuring bone depth prior to treatment to avoid excessive bone dose.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70062"},"PeriodicalIF":2.0,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143556820","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}
Jingwei Duan, Joel A Pogue, Dennis N Stanley, Sui Shen, Natalie N Viscariello, Carlos E Cardenas, Richard A Popple, Joseph Harms
{"title":"Assessing HyperSight iterative CBCT for dose calculation in online adaptive radiotherapy for pelvis and breast patients compared to synthetic CT.","authors":"Jingwei Duan, Joel A Pogue, Dennis N Stanley, Sui Shen, Natalie N Viscariello, Carlos E Cardenas, Richard A Popple, Joseph Harms","doi":"10.1002/acm2.70038","DOIUrl":"https://doi.org/10.1002/acm2.70038","url":null,"abstract":"<p><strong>Purpose/objectives: </strong>Recent technological advancements have increased efficiency for clinical deliverability of online-adaptive-radiotherapy (oART). Previous cone-beam-computed-tomography (CBCT) generations lacked the ability to provide reliable Hounsfield-units (HU), thus requiring oART workflows to rely on synthetic-CT (sCT) images derived through deformable-image-registration (DIR) between the planning CT (pCT) and the daily CBCT. These sCTs are prone to errors stemming from DIR, potentially contributing to dosimetric errors. This study aims to evaluate the capability of direct dose calculation using a novel CBCT platform, HyperSight (Varian-Medical-Systems), as an alternative for sCT.</p><p><strong>Methods/materials: </strong>To validate the HyperSight iterative CBCT (HS-iCBCT) HU accuracy, 125 kV and 140 kV HS-iCBCT calibration curves were benchmarked against a pCT calibration curve. To determine the clinical impact of HS-iCBCT compared to sCT, daily adaptive sessions from 47 oART fractions from 10 patients were analyzed. For these patients, HS-iCBCT was acquired for daily adaption, and sCT was generated as part of the standard adaptive workflow. After daily adaption, dose was recalculated directly using the HS-iCBCT, and the HS-iCBCT and sCT dose distributions were compared by γ-index and dose-volume-histogram (DVH) analysis.</p><p><strong>Results: </strong>The mean HU differences of pCT minus HS-iCBCT (140/125 kV) were -40.97/-57.79, 9.86/21.74, and 87.22/158.20 for lung, water, and bone. In the patient cohort, the median gamma passing rates between HS-iCBCT and sCT-based dose calculations for 3%/2 mm and 1%/1 mm were 99.57 and 96.45% with 10% threshold, and 99.92% and 86.15% with 80% threshold. Dosimetric deviations in high dose regions were concentrated in areas with larger deformation, that is, surface change and variable bladder/bowel filling. The median (min-max) D98%/V100% absolute deviations were 0.3(0.0-1.6)/0.0(0.0-13.7) and 0.4(0.0-1.4)/0.5(0.0-17.5) for CTVs and PTVs.</p><p><strong>Conclusions: </strong>The HS-iCBCT platform with iterative reconstruction provides dose calculation comparable to sCT for pelvis and breast patients. However, acceptable, yet noticeable, dose discrepancies between HS-iCBCT and sCT exist, particularly in high-dose regions. Further investigations are needed to benchmark these methods against ground truth measurements.</p>","PeriodicalId":14989,"journal":{"name":"Journal of Applied Clinical Medical Physics","volume":" ","pages":"e70038"},"PeriodicalIF":2.0,"publicationDate":"2025-03-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143542057","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}