1
|
Nelson G, Sarkar V, Szegedi M, Molineu A, Olch AJ, Kunz JN, Zhao H, Huang YJ, Pillai S, Rassiah P. Validation of Acuros for total body irradiation at extended distance. J Appl Clin Med Phys 2024:e14468. [PMID: 39023298 DOI: 10.1002/acm2.14468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/23/2024] [Accepted: 06/20/2024] [Indexed: 07/20/2024] Open
Abstract
PURPOSE Standardized and accurately reported doses are essential in conventional total body irradiation (TBI), especially lung doses. This study evaluates the accuracy of the Acuros algorithm in predicting doses for extended-distance TBI. METHODS Measurements and calculations were done with both 6 and 18 MV. Tissue Maximum Ratio (TMR), output and off axis ratios (OAR) were measured at 200 and 500 cm source to detector distance and compared to Acuros calculated values. Two end-to-end tests were carried out, one with an in-house phantom (solid water and Styrofoam) with inserted ion chambers and the other was with the Imaging and Radiation Oncology Core (IROC) TBI anthropomorphic phantom equipped with TLDs. The end-to-end test was done for 6 and 18 MV both with and without lung blocks. The source to midplane distance for both phantoms were at 518 and 508 cm respectively. Lung blocks were placed at the phantom surface and a beam spoiler was positioned 30 cm from the surface of the phantoms as per our clinical set up. RESULTS The agreement between measured and calculated TMR, output and off axis ratios for both 6 and 18 MV were within 2%. Ion chamber measurements in both the Styrofoam and solid water for both energies carried out with and without lung blocks were within 2% of calculated values. TLD measured doses for both 6 and 18 MV in the IROC phantom were within 5% of calculated doses which is within the uncertainty of the TLD measurement. CONCLUSIONS The results indicate that the clinical beam model for Acuros 16.1 commissioned at standard clinical distances is capable of calculating doses accurately at extended distances up to 500 cm.
Collapse
Affiliation(s)
- Geoffrey Nelson
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | - Vikren Sarkar
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | - Martin Szegedi
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | - Andrea Molineu
- Imaging and Radiation Oncology Core, Houston QA Center, MD Anderson Cancer Center, Houston, Texas, USA
| | - Arthur J Olch
- Department of Radiation Oncology, University of Southern California and Children's Hospital of Los Angeles, Los Angeles, California, USA
| | - Jeremy N Kunz
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | - Hui Zhao
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | - Y Jessica Huang
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| | | | - Prema Rassiah
- Department of Radiation Oncology, University of Utah, Salt Lake City, Utah, USA
| |
Collapse
|
2
|
Ehler ED, Turcotte LM, Skamene S, Baker KS, Das SK, Constine LS, Yuan J, Dusenbery KE. Idiopathic Pneumonitis Syndrome After Total Body Irradiation in Pediatric Patients Undergoing Myeloablative Hematopoietic Stem Cell Transplantation: A PENTEC Comprehensive Review. Int J Radiat Oncol Biol Phys 2024; 119:625-639. [PMID: 36973099 DOI: 10.1016/j.ijrobp.2023.02.037] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 01/17/2023] [Accepted: 02/16/2023] [Indexed: 03/29/2023]
Abstract
PURPOSE Pulmonary complications, especially idiopathic pneumonitis syndrome (IPS), are potentially life altering or fatal sequelae of hematopoietic cell transplantation (HCT). Total body irradiation (TBI) as part of the conditioning regimen has been implicated in IPS. A comprehensive PENTEC (Pediatric Normal Tissues in the Clinic) review was performed to increase our understanding of the role of TBI in the development of acute, noninfectious IPS. METHODS AND MATERIALS A systematic literature search was conducted using the MEDLINE, PubMed, and Cochrane library databases for articles describing pulmonary toxicity in children treated with HCT. Data pertaining to TBI and pulmonary endpoints were extracted. Risk of IPS was analyzed in relation to patient age, TBI dose, fractionation, dose rate, lung shielding, timing, and type of transplant, with the goal to better understand factors associated with this complication in children undergoing HCT. A logistic regression model was developed using a subset of studies with comparable transplant regimens and sufficient TBI data. RESULTS Six studies met criteria for modeling of the correlation of TBI parameters with IPS; all consisted of pediatric patients undergoing allogeneic HCT with a cyclophosphamide-based chemotherapy regimen. IPS was variably defined, but all studies that reported IPS were included in this analysis. The mean incidence of post-HCT IPS was 16% (range, 4%-41%). Mortality from IPS, when it occurred, was high (median, 50%; range, 45%-100%). Fractionated TBI prescription doses encompassed a narrow range of 9 to 14 Gy. Many differing TBI methods were reported, and there was an absence of 3-dimensional dose analysis of lung blocking techniques. Thus, a univariate correlation between IPS and total TBI dose, dose fractionation, dose rate, or TBI technique could not be made. However, a model, built from these studies based on prescribed dose using a normalized dose parameter of equivalent dose in 2-Gy fractions (EQD2), adjusted for dose rate, suggested correlation with the development of IPS (P = .0004). The model-predicted odds ratio for IPS was 24.3 Gy-1 (95% confidence interval, 7.0-84.3). Use of TBI lung dose metrics (eg, midlung point dose) could not be successfully modeled, potentially because of dosimetric uncertainties in the actual delivered volumetric lung dose and imperfections in our modeling process. CONCLUSIONS This PENTEC report is a comprehensive review of IPS in pediatric patients receiving fractionated TBI regimens for allogenic HCT. IPS was not clearly associated with 1 single TBI factor. Modeling using dose-rate adjusted EQD2 showed a response with IPS for allogeneic HCT using a cyclophosphamide-based chemotherapy regimen. Therefore, this model suggests IPS mitigation strategies can focus on not just the dose and dose per fraction but also the dose rate used in TBI. More data are needed to confirm this model and to determine the influence of chemotherapy regimens and contribution from graft-versus-host disease. The presence of confounding variables (eg, systemic chemotherapies) that affect risk, the narrow range of fractionated TBI doses found in the literature, and limitations of other reported data (eg, lung point dose) may have prevented a more straightforward link between IPS and total dose from being observed.
Collapse
Affiliation(s)
| | | | - Sonia Skamene
- Division of Radiation Oncology, McGill University, Montreal, Quebec, Canada
| | - K Scott Baker
- Fred Hutchinson Cancer Research Center, Seattle Children's Hospital, Seattle, Washington
| | - Shiva K Das
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Louis S Constine
- Department of Radiation Oncology, James P. Wilmot Cancer Institute, University of Rochester, Rochester, New York
| | | | | |
Collapse
|
3
|
Liang X, Li P, Wu Q. A novel AP/PA total body irradiation technique using abutting IMRT fields at extended SSD. J Appl Clin Med Phys 2024; 25:e14213. [PMID: 38425126 PMCID: PMC11005982 DOI: 10.1002/acm2.14213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 11/06/2023] [Accepted: 11/07/2023] [Indexed: 03/02/2024] Open
Abstract
PURPOSE To develop a Total Body Irradiation (TBI) technique using IMRT at extended SSD that can be performed in any size Linac room. METHODS Patients studied were placed on a platform close to the floor, directly under the gantry with cranial-caudal axis parallel to the gantry rotation plane and at SSD ∼200 cm. Two abutting fields with the same external isocenter at gantry angles of ±21˚, collimator angle of 90˚, and field size of 25 × 40 cm2 are employed for both supine and prone positions. An iterative optimization algorithm was developed to generate a uniform dose at the patient mid-plane with adequate shielding to critical organs such as lungs and kidneys. The technique was validated in both phantom and patient CT images for treatment planning, and dose measurement and QA were performed in phantom. RESULTS A uniform dose distribution in the mid-plane within ±5% of the prescription dose was reached after a few iterations. This was confirmed with ion-chamber measurements in phantom. The mean dose to lungs and kidneys can be adjusted according to clinical requirements and can be as low as ∼25% of the prescription dose. For a typical prescription dose of 200 cGy/fraction, the total MU was ∼2400/1200 for the superior/inferior field. The overall treatment time for both supine/prone positions was ∼54 min to meet the maximum absorbed dose rate criteria of 15 cGy/min. IMRT QA with portal dosimetry shows excellent agreement. CONCLUSIONS We have developed a promising TBI technique using abutting IMRT fields at extended SSD. The patient is in a comfortable recumbent position with good reproducibility and less motion during treatment. An additional benefit of this technique is that full 3D dose distribution is available from the TPS with a DVH summary for organs of interest. The technique allows precise sparing of lungs and kidneys and can be executed in any linac room.
Collapse
Affiliation(s)
- Xiaomin Liang
- Medical Physics Graduate ProgramDuke Kunshan UniversityKunshanJiangsuChina
| | - Peixiong Li
- Medical Physics Graduate ProgramDuke Kunshan UniversityKunshanJiangsuChina
| | - Qiuwen Wu
- Department of Radiation OncologyDuke University Medical CenterDurhamNorth CarolinaUSA
| |
Collapse
|
4
|
Hao C, Ladbury C, Wong J, Dandapani S. Modern Radiation for Hematologic Stem Cell Transplantation: Total Marrow and Lymphoid Irradiation or Intensity-Modulated Radiation Therapy Total Body Irradiation. Surg Oncol Clin N Am 2023; 32:475-495. [PMID: 37182988 DOI: 10.1016/j.soc.2023.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
The development of large-field intensity-modulated radiation therapy (IMRT) has enabled the implementation of total marrow irradiation (TMI), total marrow and lymphoid irradiation (TMLI), and IMRT total body irradiation (TBI). IMRT TBI limits doses to organs at risk, primarily the lungs and in some cases the kidneys and lenses, which may mitigate complications. TMI/TMLI allows for dose escalation above TBI radiation therapy doses to malignant sites while still sparing organs at risk. Although still sparingly used, these techniques have established feasibility and demonstrated promise in reducing the adverse effects of TBI while maintaining and potentially improving survival outcomes.
Collapse
Affiliation(s)
- Claire Hao
- Department of Radiation Oncology, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Colton Ladbury
- Department of Radiation Oncology, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Jeffrey Wong
- Department of Radiation Oncology, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Savita Dandapani
- Department of Radiation Oncology, City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA.
| |
Collapse
|
5
|
Köksal M, Baumert J, Schoroth F, Scafa D, Koch D, Leitzen C, Sarria GR, Giordano FA, Chatzikonstantinou G, Schmeel LC. Lung sparing and ribcage coverage in total body irradiation delivered by helical tomotherapy. Eur J Med Res 2022; 27:287. [PMID: 36496388 PMCID: PMC9737733 DOI: 10.1186/s40001-022-00918-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Accepted: 11/29/2022] [Indexed: 12/13/2022] Open
Abstract
PURPOSE Helical tomotherapy (HT) is a viable method for delivering total body irradiation (TBI) when preparing patients for allogenic stem cell or bone-marrow transplantation. TBI can be planned to reduce the amount of radiation delivered to organs at risk, such as the lungs, with the aim of decreasing toxicity. However, it is important for the ribcage to receive the prescribed radiation dose in preparation for bone-marrow transplantation. In this retrospective study, we analyzed radiation dose coverage of the lungs and ribcage in patients who underwent TBI delivered by HT to achieve lung dose sparing. METHODS Thirty-five patients were included in the analysis and divided into three groups based on their prescribed radiation dose (4, 8, or 12 Gy). HT was performed using a rotating gantry to reduce radiation to the lungs. Dosimetric parameters for the lungs and ribcage as well as dose-volume histograms were calculated. RESULTS The mean lung D95 was 60.97%, 54.77%, and 37.44% of the prescribed dose for patients receiving 4 Gy, 8 Gy, and 12 Gy, respectively. Ribcage coverage was most optimal for patients receiving 4 Gy, with a D95 of 91.27% and mean homogeneity index of 1.17, whereas patients receiving 12 Gy had a mean D95 of 78.65% and homogeneity index of 1.37, which is still within the range recommended by treatment guidelines. CONCLUSIONS Using HT to achieve lung tissue sparing is a viable approach to minimizing pulmonic complications in patients undergoing TBI. As this planning adjustment does not compromise the dose and quality of coverage received by the ribcage, it is a feasible tool within conditioning regimens for allogeneic bone-marrow transplantation.
Collapse
Affiliation(s)
- Mümtaz Köksal
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - Jonathan Baumert
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - Felix Schoroth
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - Davide Scafa
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - David Koch
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - Christina Leitzen
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - Gustavo R. Sarria
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| | - Frank A. Giordano
- grid.411778.c0000 0001 2162 1728Department of Radiation Oncology, University Medical Centre Mannheim, Mannheim, Germany
| | - Georgios Chatzikonstantinou
- grid.411088.40000 0004 0578 8220Department of Radiation Oncology, University Hospital Frankfurt, Frankfurt, Germany
| | - Leonard C. Schmeel
- grid.15090.3d0000 0000 8786 803XDepartment of Radiation Oncology, University Hospital Bonn, Bonn, Germany
| |
Collapse
|
6
|
Farag NM, Zaghloul MS, El-Gebaly RH, Hassan ZET, Hamza NM, Mohamad EA. A comprehensive method for calculating total body irradiation. J Med Imaging Radiat Sci 2022; 53:460-470. [DOI: 10.1016/j.jmir.2022.06.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2022] [Revised: 06/24/2022] [Accepted: 06/30/2022] [Indexed: 10/16/2022]
|
7
|
Hoeben BAW, Pazos M, Seravalli E, Bosman ME, Losert C, Albert MH, Boterberg T, Ospovat I, Mico Milla S, Demiroz Abakay C, Engellau J, Jóhannesson V, Kos G, Supiot S, Llagostera C, Bierings M, Scarzello G, Seiersen K, Smith E, Ocanto A, Ferrer C, Bentzen SM, Kobyzeva DA, Loginova AA, Janssens GO. ESTRO ACROP and SIOPE recommendations for myeloablative Total Body Irradiation in children. Radiother Oncol 2022; 173:119-133. [PMID: 35661674 DOI: 10.1016/j.radonc.2022.05.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Accepted: 05/26/2022] [Indexed: 01/28/2023]
Abstract
BACKGROUND AND PURPOSE Myeloablative Total Body Irradiation (TBI) is an important modality in conditioning for allogeneic hematopoietic stem cell transplantation (HSCT), especially in children with high-risk acute lymphoblastic leukemia (ALL). TBI practices are heterogeneous and institution-specific. Since TBI is associated with multiple late adverse effects, recommendations may help to standardize practices and improve the outcome versus toxicity ratio for children. MATERIAL AND METHODS The European Society for Paediatric Oncology (SIOPE) Radiotherapy TBI Working Group together with ESTRO experts conducted a literature search and evaluation regarding myeloablative TBI techniques and toxicities in children. Findings were discussed in bimonthly virtual meetings and consensus recommendations were established. RESULTS Myeloablative TBI in HSCT conditioning is mostly performed for high-risk ALL patients or patients with recurring hematologic malignancies. TBI is discouraged in children <3-4 years old because of increased toxicity risk. Publications regarding TBI are mostly retrospective studies with level III-IV evidence. Preferential TBI dose in children is 12-14.4 Gy in 1.6-2 Gy fractions b.i.d. Dose reduction should be considered for the lungs to <8 Gy, for the kidneys to ≤10 Gy, and for the lenses to <12 Gy, for dose rates ≥6 cGy/min. Highly conformal techniques i.e. TomoTherapy and VMAT TBI or Total Marrow (and/or Lymphoid) Irradiation as implemented in several centers, improve dose homogeneity and organ sparing, and should be evaluated in studies. CONCLUSIONS These ESTRO ACROP SIOPE recommendations provide expert consensus for conventional and highly conformal myeloablative TBI in children, as well as a supporting literature overview of TBI techniques and toxicities.
Collapse
Affiliation(s)
- Bianca A W Hoeben
- Dept. of Radiation Oncology, University Medical Center Utrecht, The Netherlands; Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands.
| | - Montserrat Pazos
- Dept. of Radiation Oncology, University Hospital, LMU Munich, Germany
| | - Enrica Seravalli
- Dept. of Radiation Oncology, University Medical Center Utrecht, The Netherlands
| | - Mirjam E Bosman
- Dept. of Radiation Oncology, University Medical Center Utrecht, The Netherlands
| | - Christoph Losert
- Dept. of Radiation Oncology, University Hospital, LMU Munich, Germany
| | - Michael H Albert
- Dept. of Pediatrics, Dr. von Hauner Children's Hospital, University Hospital, LMU Munich, Germany
| | - Tom Boterberg
- Dept. of Radiation Oncology, Ghent University Hospital, Ghent, Belgium
| | - Inna Ospovat
- Dept. of Radiation Oncology, Tel Aviv Sourasky Medical Center, Tel Aviv, Israel
| | - Soraya Mico Milla
- Dept. of Radiation Oncology, Vall d'Hebron University Hospital, Barcelona, Spain
| | - Candan Demiroz Abakay
- Dept. of Radiation Oncology, Uludag University Faculty of Medicine Hospital, Bursa, Turkey
| | - Jacob Engellau
- Dept. of Radiation Oncology, Skåne University Hospital, Lund, Sweden
| | | | - Gregor Kos
- Dept. of Radiation Oncology, Institute of Oncology Ljubljana, Slovenia
| | - Stéphane Supiot
- Dept. of Radiation Oncology, Institut de Cancérologie de l'Ouest, Nantes St. Herblain, France
| | - Camille Llagostera
- Dept. of Medical Physics, Institut de Cancérologie de l'Ouest, Nantes St. Herblain, France
| | - Marc Bierings
- Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Giovanni Scarzello
- Dept. of Radiation Oncology, Veneto Institute of Oncology-IRCCS, Padua, Italy
| | | | - Ed Smith
- Dept. of Radiation Oncology, The Christie NHS Foundation Trust, Manchester, United Kingdom
| | - Abrahams Ocanto
- Dept. of Radiation Oncology, La Paz University Hospital, Madrid, Spain
| | - Carlos Ferrer
- Dept. of Medical Physics and Radiation Protection, La Paz University Hospital, Madrid, Spain
| | - Søren M Bentzen
- Dept. of Epidemiology and Public Health, Division of Biostatistics and Bioinformatics, University of Maryland School of Medicine, Baltimore, United States
| | - Daria A Kobyzeva
- Dept. of Radiation Oncology, Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Anna A Loginova
- Dept. of Radiation Oncology, Dmitry Rogachev National Research Center of Pediatric Hematology, Oncology and Immunology, Moscow, Russia
| | - Geert O Janssens
- Dept. of Radiation Oncology, University Medical Center Utrecht, The Netherlands; Princess Máxima Center for Pediatric Oncology, Utrecht, The Netherlands
| |
Collapse
|
8
|
Luk SMH, Wallner K, Glenn MC, Ermoian R, Phillips MH, Tseng YD, Kim M. Effect of total body irradiation lung block parameters on lung doses using three-dimensional dosimetry. J Appl Clin Med Phys 2022; 23:e13513. [PMID: 34985180 PMCID: PMC8992940 DOI: 10.1002/acm2.13513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 12/05/2022] Open
Abstract
Purpose Total body irradiation (TBI) is an integral part of stem cell transplant. However, patients are at risk of treatment‐related toxicities, including radiation pneumonitis. While lung dose is one of the most crucial aspects of TBI dosimetry, currently available data are based on point doses. As volumetric dose distribution could be substantially altered by lung block parameters, we used 3D dosimetry in our treatment planning system to estimate volumetric lung dose and measure the impact of various lung block designs. Materials and methods We commissioned a TBI beam model in RayStation that matches the measured tissue‐phantom ratio under our clinical TBI setup. Cerrobend blocks were automatically generated in RayStation on thoracic Computed Tomography (CT) scans from three anonymized patients using the lung, clavicle, spine, and diaphragmatic contours. The margin for block edge was varied to 0, 1, or 2 cm from the superior, lateral, and inferior thoracic borders, with a uniform margin 2.5 cm lateral to the vertebral bodies. The lung dose was calculated and compared with a prescription dose of 1200 cGy in six fractions (three with blocks and three without). Result The point dose at midplane under the block and the average lung dose are at the range of 73%–76% and 80%–88% of prescription dose respectively regardless of the block margins. In contrast, the percent lung volume receiving 10 Gy increased by nearly two‐fold, from 31% to 60% over the margins from 0 to 2 cm. Conclusions The TPS‐derived 3D lung dose is substantially different from the nominal dose assumed with HVL lung blocks. Point doses under the block are insufficient to accurately gauge the relationship between dose and pneumonitis, and TBI dosimetry could be highly variable between patients and institutions as more descriptive parameters are not included in protocols. Much progress remains to be made to optimize and standardize technical aspects of TBI, and better dosimetry could provide more precise dosimetric predictors for pneumonitis risk.
Collapse
Affiliation(s)
- Samuel M H Luk
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA.,Department of Radiation Oncology, University of Vermont Medical Center, Burlington, Vermont, USA
| | - Kent Wallner
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Mallory C Glenn
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Ralph Ermoian
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Mark H Phillips
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| | - Yolanda D Tseng
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA.,Clinical Research Division, Fred Hutchinson cancer Research Center, Seattle, Washington, USA
| | - Minsun Kim
- Department of Radiation Oncology, University of Washington, Seattle, Washington, USA
| |
Collapse
|
9
|
Glenn MC, Wallner K, Luk SM, Ermoian R, Tseng YD, Phillips M, Kim M. Impact of lung block shape on cardiac dose for total body irradiation. Phys Imaging Radiat Oncol 2022; 21:30-34. [PMID: 35243029 PMCID: PMC8875787 DOI: 10.1016/j.phro.2022.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 01/14/2022] [Accepted: 01/26/2022] [Indexed: 11/23/2022] Open
Abstract
Partial cardiac shielding in TBI is not commonly reported and varies among clinics. We evaluated the effects of cardiac shielding in TBI using 3D beam modeling in a commercial TPS. Partial cardiac shielding can reduce mean heart dose and reduce LAD dose up to 30%.
Evaluating cardiac dose during total body irradiation (TBI) is of increasing interest. A three-dimensional beam model for TBI was commissioned and lung shielding was simulated in a treatment planning system with the cardiac silhouette partially blocked and unblocked. When blocked, the median heart dose decreased by 6% (IQR = 6%) and the median cardiac V12Gy decreased by 27% (IQR = 17%). The median left anterior descending artery dose decreased 20% (IQR = 12%) for blocked cases. Because using partial heart shielding may result in considerable changes in dose to cardiac structures, TBI protocols should explicitly consider lung block design parameters and their potential effects.
Collapse
|
10
|
Hoeben BAW, Wong JYC, Fog LS, Losert C, Filippi AR, Bentzen SM, Balduzzi A, Specht L. Total Body Irradiation in Haematopoietic Stem Cell Transplantation for Paediatric Acute Lymphoblastic Leukaemia: Review of the Literature and Future Directions. Front Pediatr 2021; 9:774348. [PMID: 34926349 PMCID: PMC8678472 DOI: 10.3389/fped.2021.774348] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2021] [Accepted: 11/03/2021] [Indexed: 12/13/2022] Open
Abstract
Total body irradiation (TBI) has been a pivotal component of the conditioning regimen for allogeneic myeloablative haematopoietic stem cell transplantation (HSCT) in very-high-risk acute lymphoblastic leukaemia (ALL) for decades, especially in children and young adults. The myeloablative conditioning regimen has two aims: (1) to eradicate leukaemic cells, and (2) to prevent rejection of the graft through suppression of the recipient's immune system. Radiotherapy has the advantage of achieving an adequate dose effect in sanctuary sites and in areas with poor blood supply. However, radiotherapy is subject to radiobiological trade-offs between ALL cell destruction, immune and haematopoietic stem cell survival, and various adverse effects in normal tissue. To diminish toxicity, a shift from single-fraction to fractionated TBI has taken place. However, HSCT and TBI are still associated with multiple late sequelae, leaving room for improvement. This review discusses the past developments of TBI and considerations for dose, fractionation and dose-rate, as well as issues regarding TBI setup performance, limitations and possibilities for improvement. TBI is typically delivered using conventional irradiation techniques and centres have locally developed heterogeneous treatment methods and ways to achieve reduced doses in several organs. There are, however, limitations in options to shield organs at risk without compromising the anti-leukaemic and immunosuppressive effects of conventional TBI. Technological improvements in radiotherapy planning and delivery with highly conformal TBI or total marrow irradiation (TMI), and total marrow and lymphoid irradiation (TMLI) have opened the way to investigate the potential reduction of radiotherapy-related toxicities without jeopardising efficacy. The demonstration of the superiority of TBI compared with chemotherapy-only conditioning regimens for event-free and overall survival in the randomised For Omitting Radiation Under Majority age (FORUM) trial in children with high-risk ALL makes exploration of the optimal use of TBI delivery mandatory. Standardisation and comprehensive reporting of conventional TBI techniques as well as cooperation between radiotherapy centres may help to increase the ratio between treatment outcomes and toxicity, and future studies must determine potential added benefit of innovative conformal techniques to ultimately improve quality of life for paediatric ALL patients receiving TBI-conditioned HSCT.
Collapse
Affiliation(s)
- Bianca A. W. Hoeben
- Department of Radiation Oncology, University Medical Center Utrecht, Utrecht, Netherlands
- Princess Máxima Center for Pediatric Oncology, Utrecht, Netherlands
| | - Jeffrey Y. C. Wong
- Department of Radiation Oncology, City of Hope National Medical Center and Beckman Research Institute, Duarte, CA, United States
| | - Lotte S. Fog
- Alfred Health Radiation Oncology, The Alfred Hospital, Melbourne, VIC, Australia
| | - Christoph Losert
- Department of Radiation Oncology, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany
| | - Andrea R. Filippi
- Department of Radiation Oncology, Fondazione IRCCS Policlinico San Matteo and University of Pavia, Pavia, Italy
| | - Søren M. Bentzen
- Division of Biostatistics and Bioinformatics, Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, United States
| | - Adriana Balduzzi
- Stem Cell Transplantation Unit, Clinica Paediatrica Università degli Studi di Milano Bicocca, Monza, Italy
| | - Lena Specht
- Department of Oncology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| |
Collapse
|
11
|
Teruel JR, Taneja S, Galavis PE, Osterman KS, McCarthy A, Malin M, Gerber NK, Hitchen C, Barbee DL. Automatic treatment planning for VMAT-based total body irradiation using Eclipse scripting. J Appl Clin Med Phys 2021; 22:119-130. [PMID: 33565214 PMCID: PMC7984467 DOI: 10.1002/acm2.13189] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 12/15/2020] [Accepted: 01/09/2021] [Indexed: 11/25/2022] Open
Abstract
The purpose of this work is to establish an automated approach for a multiple isocenter volumetric arc therapy (VMAT)‐based TBI treatment planning approach. Five anonymized full‐body CT imaging sets were used. A script was developed to automate and standardize the treatment planning process using the Varian Eclipse v15.6 Scripting API. The script generates two treatment plans: a head‐first VMAT‐based plan for upper body coverage using four isocenters and a total of eight full arcs; and a feet‐first AP/PA plan with three isocenters that covers the lower extremities of the patient. PTV was the entire body cropped 5 mm from the patient surface and extended 3 mm into the lungs and kidneys. Two plans were generated for each case: one to a total dose of 1200 cGy in 8 fractions and a second one to a total dose of 1320 cGy in 8 fractions. Plans were calculated using the AAA algorithm and 6 MV photon energy. One plan was created and delivered to an anthropomorphic phantom containing 12 OSLDs for in‐vivo dose verification. For the plans prescribed to 1200 cGy total dose the following dosimetric results were achieved: median PTV V100% = 94.5%; median PTV D98% = 89.9%; median lungs Dmean = 763 cGy; median left kidney Dmean = 1058 cGy; and median right kidney Dmean = 1051 cGy. For the plans prescribed to 1320 cGy total dose the following dosimetric results were achieved: median PTV V100% = 95.0%; median PTV D98% = 88.7%; median lungs Dmean = 798 cGy; median left kidney Dmean = 1059 cGy; and median right kidney Dmean = 1064 cGy. Maximum dose objective was met for all cases. The dose deviation between the treatment planning dose and the dose measured by the OSLDs was within ±4%. In summary, we have demonstrated that scripting can produce high‐quality plans based on predefined dose objectives and can decrease planning time by automatic target and optimization contours generation, plan creation, field and isocenter placement, and optimization objectives setup.
Collapse
Affiliation(s)
- Jose R Teruel
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | - Sameer Taneja
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | - Paulina E Galavis
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | | | - Allison McCarthy
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | - Martha Malin
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | - Naamit K Gerber
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | - Christine Hitchen
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| | - David L Barbee
- Department of Radiation Oncology, NYU Langone Health, New York, NY, USA
| |
Collapse
|
12
|
Esiashvili N, Lu X, Ulin K, Laurie F, Kessel S, Kalapurakal JA, Merchant TE, Followill DS, Sathiaseelan V, Schmitter MK, Devidas M, Chen Y, Wall DA, Brown PA, Hunger SP, Grupp SA, Pulsipher MA. Higher Reported Lung Dose Received During Total Body Irradiation for Allogeneic Hematopoietic Stem Cell Transplantation in Children With Acute Lymphoblastic Leukemia Is Associated With Inferior Survival: A Report from the Children's Oncology Group. Int J Radiat Oncol Biol Phys 2019; 104:513-521. [PMID: 30807822 PMCID: PMC6548591 DOI: 10.1016/j.ijrobp.2019.02.034] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/14/2019] [Accepted: 02/14/2019] [Indexed: 12/11/2022]
Abstract
PURPOSE To examine the relationship between lung radiation dose and survival outcomes in children undergoing total body irradiation (TBI)-based hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia on the Children's Oncology Group trial. METHODS AND MATERIALS TBI (1200 or 1320 cGy given twice daily in 6 or 8 fractions) was used as part of 3 HSCT preparative regimens, allowing institutional flexibility regarding TBI techniques, including lung shielding. Lung doses as reported by each participating institution were calculated for different patient setups, with and without shielding, with a variety of dose calculation techniques. The association between lung dose and transplant-related mortality, relapse-free survival, and overall survival (OS) was examined using the Cox proportional hazards regression model controlling for the following variables: TBI dose rate, TBI fields, patient position during TBI, donor type, and pre-HSCT minimal residual disease level. RESULTS Of a total of 143 eligible patients, 127 had lung doses available for this analysis. The TBI techniques were heterogeneous. The mean lung dose was reported as 904.5 cGy (standard deviation, ±232.3). Patients treated with lateral fields were more likely to receive lung doses ≥800 cGy (P < .001). The influence of lung dose ≥800 cGy on transplant-related mortality was not significant (hazard ratio [HR], 1.78; P = .21). On univariate analysis, lung dose ≥800 cGy was associated with inferior relapse-free survival (HR, 1.76; P = .04) and OS (HR, 1.85; P = .03). In the multivariate analysis, OS maintained statistical significance (HR, 1.85; P = .04). CONCLUSIONS The variability in TBI techniques resulted in uncertainty with reported lung doses. Lateral fields were associated with higher lung dose, and thus they should be avoided. Patients treated with lung dose <800 cGy in this study had better outcomes. This approach is currently being investigated in the Children's Oncology Group AALL1331 study. Additionally, the Imaging and Radiation Oncology Core Group is evaluating effects of TBI techniques on lung doses using a phantom.
Collapse
Affiliation(s)
| | - Xiaomin Lu
- Children's Oncology Group Data Center, Biostatistics, University of Florida, Gainesville, Florida
| | - Ken Ulin
- Imaging and Radiation Oncology Rhode Island QA Center, Lincoln, Rhode Island
| | - Fran Laurie
- Imaging and Radiation Oncology Rhode Island QA Center, Lincoln, Rhode Island
| | - Sandy Kessel
- Imaging and Radiation Oncology Rhode Island QA Center, Lincoln, Rhode Island
| | - John A Kalapurakal
- Robert H. Lurie Comprehensive Cancer Center of Northwestern University, Chicago, Illinois
| | | | - David S Followill
- Imaging and Radiation Oncology Rhode Island QA Center, Houston, Texas
| | | | - Mary K Schmitter
- Imaging and Radiation Oncology Rhode Island QA Center, Lincoln, Rhode Island
| | - Meenakshi Devidas
- Children's Oncology Group Data Center, Biostatistics, University of Florida, Gainesville, Florida
| | - Yichen Chen
- Children's Oncology Group Data Center, Biostatistics, University of Florida, Gainesville, Florida
| | - Donna A Wall
- Manitoba Blood and Marrow Transplant Program, Winnipeg, Manitoba, Canada
| | - Patrick A Brown
- Johns Hopkins University Kimmel Cancer Center, Baltimore, Maryland
| | - Stephen P Hunger
- Children's Hospital of Philadelphia and the Perelman School of Medicine at The University of Pennsylvania, Philadelphia, Pennsylvania
| | - Stephan A Grupp
- Children's Hospital of Philadelphia and the Perelman School of Medicine at The University of Pennsylvania, Philadelphia, Pennsylvania
| | - Michael A Pulsipher
- Children's Center for Cancer and Blood Diseases, Children's Hospital Los Angeles, University of Southern California Keck School of Medicine, Los Angeles, California
| |
Collapse
|
13
|
Cunha J, Santos W, Carvalho Júnior A. Conversion Coefficients of equivalent and effective doses in terms of air kerma for computational scenarios of Total Body Irradiation in lying-down patients. Radiat Phys Chem Oxf Engl 1993 2019. [DOI: 10.1016/j.radphyschem.2019.02.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
|
14
|
Chen GL, Hahn T, Wilding GE, Groman A, Hutson A, Zhang Y, Khan U, Liu H, Ross M, Bambach B, Higman M, Neppalli V, Sait S, Block AW, Wallace PK, Singh AK, McCarthy PL. Reduced-Intensity Conditioning with Fludarabine, Melphalan, and Total Body Irradiation for Allogeneic Hematopoietic Cell Transplantation: The Effect of Increasing Melphalan Dose on Underlying Disease and Toxicity. Biol Blood Marrow Transplant 2018; 25:689-698. [PMID: 30300731 DOI: 10.1016/j.bbmt.2018.09.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 09/28/2018] [Indexed: 11/15/2022]
Abstract
Disease relapse and toxicity are the shortcomings of reduced-intensity conditioning (RIC) for allogeneic hematopoietic cell transplantation (alloHCT). We hypothesized that adding total body irradiation (TBI) to and decreasing melphalan (Mel) from a base RIC regimen of fludarabine (Flu) and Mel would increase cytoreduction and improve disease control while decreasing toxicity. We performed a phase II trial of Flu 160 mg/m2, Mel 50 mg/m2, and TBI 400 cGy (FluMelTBI-50, n = 61), followed by a second phase II trial of Flu 160 mg/m2, Mel 75 mg/m2, and TBI 400cGy (FluMelTBI-75, n = 94) as RIC for alloHCT. Outcomes were compared with a contemporaneous cohort of 162 patients who received Flu 125 mg/m2 and Mel 140 mg/m2. Eligibility criteria were equivalent for all 3 regimens. All patients were ineligible for myeloablative/intensive conditioning. The median (range) follow-up for all patients was 51 (15 to 103) months. Day 100 donor lymphoid chimerism and transplant-related mortality, neutrophil and platelet engraftment, acute and chronic graft versus host disease incidence, overall survival (OS), and progression-free survival (PFS) were equivalent between FluMel, FluMelTBI-50, and FluMelTBI-75. Stomatitis wasdecreased for FluMelTBI versus FluMel (P < .01). PFS for patients not in complete remission on alloHCT was improved for FluMelTBI-75 versus FluMel (P = .03). On multivariate analysis, OS (P = .05) and PFS (P = .05) were significantly improved for FluMelTBI-75 versus FluMel. FluMelTBI-75 is better tolerated than FluMel, with improved survival and disease control.
Collapse
Affiliation(s)
- George L Chen
- BMT Program, Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York.
| | - Theresa Hahn
- BMT Program, Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Gregory E Wilding
- Department of Biostatistics, School of Public Health and Health Professions, University at Buffalo, Buffalo, New York
| | - Adrienne Groman
- Department of Biostatistics and Bioinformatics, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Alan Hutson
- Department of Biostatistics and Bioinformatics, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Yali Zhang
- BMT Program, Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Usman Khan
- BMT Program, Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Hong Liu
- Department of Oncology, Buffalo Medical Group, Buffalo, New York
| | - Maureen Ross
- BMT Program, Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Barbara Bambach
- Department of Pediatrics, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Meghan Higman
- Department of Pediatrics, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Vishala Neppalli
- Department of Pathology, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Sheila Sait
- Cytogenetics Laboratory, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - AnneMarie W Block
- Cytogenetics Laboratory, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Paul K Wallace
- Flow Cytometry Laboratory, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Anurag K Singh
- Department of Radiation Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| | - Philip L McCarthy
- BMT Program, Department of Medicine, Roswell Park Comprehensive Cancer Center, Buffalo, New York
| |
Collapse
|
15
|
Cunha J, Souza D, Carvalho Júnior A. Dose calculation with MCNPX code for Total Body Irradiation technique in sitting and lying postures. Radiat Phys Chem Oxf Engl 1993 2018. [DOI: 10.1016/j.radphyschem.2018.03.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
16
|
Tyson TE, Podgorsak MB, Singh AK, Wang IZ. Improved dose homogeneity using electronic compensation technique for total body irradiation. J Appl Clin Med Phys 2018; 19:159-167. [PMID: 29654662 PMCID: PMC5978698 DOI: 10.1002/acm2.12316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Revised: 01/30/2018] [Accepted: 02/09/2018] [Indexed: 11/21/2022] Open
Abstract
In total body irradiation (TBI) utilizing large parallel‐opposed fields, the manual placement of lead compensators has conventionally been used to compensate for the varying thickness throughout the body. The goal of this study is to pursue utilizing the modern electronic compensation (E‐comp) technique to more accurately deliver dose to TBI patients. Bilateral parallel‐opposed TBI treatment plans were created using E‐comp for 15 patients for whom CT data had been previously acquired. A desirable fluence pattern was manually painted within each field to yield a uniform dose distribution. The conventional compensation technique was simulated within the treatment planning system (TPS) using a field‐in‐field (FIF) method. This allows for a meaningful evaluation of the E‐comp technique in comparison to the conventional method. Dose–volume histograms (DVH) were computed for all treatment plans. The mean total body dose using E‐comp deviates from the prescribed dose (4 Gy) by an average of 2.4%. The mean total body dose using the conventional compensation deviates from the prescribed dose by an average of 4.5%. In all cases, the mean body dose calculated using E‐comp technique deviates less than 10% from that of conventional compensation. The average reduction in maximum dose using E‐comp compared to that of the conventional method was 30.3% ± 6.6% (standard deviation). In all cases, the s‐index for the E‐comp technique was lower (10.5% ± 0.7%) than that of the conventional method (15.8% ± 4.4%), indicating a more homogenous dose distribution. In conclusion, a large reduction in maximum body dose can be seen using the proposed E‐comp technique while still producing a mean body dose that accurately complies with the prescription dose. Dose homogeneity was quantified using s‐index which demonstrated a reduction in hotspots with E‐comp technique. Electronic compensation technique is capable of more accurately delivering a total body dose compared to conventional methods.
Collapse
Affiliation(s)
- Tara E. Tyson
- Roswell Park Cancer Institute; State University of New York; Buffalo NY USA
| | | | - Anurag K. Singh
- Roswell Park Cancer Institute; State University of New York; Buffalo NY USA
| | - Iris Z. Wang
- Roswell Park Cancer Institute; State University of New York; Buffalo NY USA
| |
Collapse
|
17
|
Knutson N, Rao YJ, Yaddanapudi S, Perkins SM, Li HH. Simplified low-dose-rate infant total body irradiation. Pract Radiat Oncol 2017; 7:190-194. [DOI: 10.1016/j.prro.2016.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 10/10/2016] [Accepted: 10/19/2016] [Indexed: 10/20/2022]
|
18
|
Lamichhane N, Patel VN, Studenski MT. Going the distance: validation of Acuros and AAA at an extended SSD of 400 cm. J Appl Clin Med Phys 2016; 17:63-73. [PMID: 27074473 PMCID: PMC5875551 DOI: 10.1120/jacmp.v17i2.5913] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 12/08/2015] [Accepted: 12/02/2015] [Indexed: 11/30/2022] Open
Abstract
Accurate dose calculation and treatment delivery is essential for total body irradiation (TBI). In an effort to verify the accuracy of TBI dose calculation at our institution, we evaluated both the Varian Eclipse AAA and Acuros algorithms to predict dose distributions at an extended source‐to‐surface distance (SSD) of 400 cm. Measurements were compared to calculated values for a 6 MV beam in physical and virtual phantoms at 400 cm SSD using open beams for both 5×5 and 40×40 cm2 field sizes. Inline and crossline profiles were acquired at equivalent depths of 5 cm, 10 cm, and 20 cm. Depth‐dose curves were acquired using EBT2 film and an ion chamber for both field sizes. Finally, a RANDO phantom was used to simulate an actual TBI treatment. At this extended SSD, care must be taken using the planning system as there is good relative agreement between measured and calculated profiles for both algorithms, but there are deviations in terms of the absolute dose. Acuros has better agreement than AAA in the penumbra region. PACS number(s): 87.55.kd
Collapse
|
19
|
Ahmed S, Brown D, Ahmed SBS, Kakakhel MB, Muhammad W, Hussain A. Translating bed total body irradiation lung shielding and dose optimization using asymmetric MLC apertures. J Appl Clin Med Phys 2016; 17:112-122. [PMID: 27074477 PMCID: PMC5875554 DOI: 10.1120/jacmp.v17i2.5951] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 12/17/2015] [Accepted: 12/14/2015] [Indexed: 12/25/2022] Open
Abstract
A revised translating bed total body irradiation (TBI) technique is developed for shielding organs at risk (lungs) to tolerance dose limits, and optimizing dose distribution in three dimensions (3D) using an asymmetrically‐adjusted, dynamic multileaf collimator. We present a dosimetric comparison of this technique with a previously developed symmetric MLC‐based TBI technique. An anthropomorphic RANDO phantom is CT scanned with 3 mm slice thickness. Radiological depths (RD) are calculated on individual CT slices along the divergent ray lines. Asymmetric MLC apertures are defined every 9 mm over the phantom length in the craniocaudal direction. Individual asymmetric MLC leaf positions are optimized based on RD values of all slices for uniform dose distributions. Dose calculations are performed in the Eclipse treatment planning system over these optimized MLC apertures. Dose uniformity along midline of the RANDO phantom is within the confidence limit (CL) of 2.1% (with a confidence probability p=0.065). The issue of over‐ and underdose at the interfaces that is observed when symmetric MLC apertures are used is reduced from more than ±4% to less than ±1.5% with asymmetric MLC apertures. Lungs are shielded by 20%, 30%, and 40% of the prescribed dose by adjusting the MLC apertures. Dose‐volume histogram analysis confirms that the revised technique provides effective lung shielding, as well as a homogeneous dose coverage to the whole body. The asymmetric technique also reduces hot and cold spots at lung‐tissue interfaces compared to previous symmetric MLC‐based TBI technique. MLC‐based shielding of OARs eliminates the need to fabricate and setup cumbersome patient‐specific physical blocks. PACS number(s): 87.55.‐x, 87.55.de, 87.55.D‐
Collapse
Affiliation(s)
- Shahbaz Ahmed
- Pakistan Institute of Engineering and Applied Sciences (PIEAS).
| | | | | | | | | | | |
Collapse
|