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Brennsæter JA, Dahle TJ, Moi JN, Svanberg IF, Haaland GS, Pilskog S. Reduction of PTV margins for elective pelvic lymph nodes in online adaptive radiotherapy of prostate cancer patients. Acta Oncol 2023; 62:1208-1214. [PMID: 37682727 DOI: 10.1080/0284186x.2023.2252584] [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: 04/18/2023] [Accepted: 08/22/2023] [Indexed: 09/10/2023]
Abstract
BACKGROUND Cone beam CT (CBCT) based online adaptive radiotherapy (oART) is a new development in radiotherapy. With oART, the requirements for planning target volume (PTV) margins differ from standard therapy because motion occurs during a session. In this study, we aim to evaluate a margin reduction for locally advanced prostate patients treated with oART. MATERIAL AND METHODS Intrafraction motion of the elective pelvic lymph nodes was evaluated by two radiation therapists (RTTs) for 150 fractions from 10 prostate patients treated with oART. PTV margins of 3, 4 and 5 mm where added to these lymph nodes for all patients. The seven first patients were treated with 5 mm PTV margin, while the last three patients were treated with 4 mm margin. After treatment, the RTTs reviewed the verification CBCTs and evaluated whether the various PTV margins would have covered the adapted clinical target volume, scoring each fraction as approved, inconclusive or rejected. Couch shifts corresponding to the rigid prostate match between the CBCTs were analyzed with respect to the RTT evaluation. RESULTS The RTTs approved a 4 mm margin in 95% of the fractions, while 2% of the fractions were rejected. For a 3 mm margin, 57% of the fractions were approved, while 5% were rejected. The scoring from the two RTTs was consistent; e.g., for 3 mm, one RTT approved 58% of the fractions, while the other approved 55%. If the couch was moved less than 2 mm in any direction, 70% of the fractions were approved for a 3 mm margin, compared to 32% for shifts greater than 2 mm. CONCLUSION It is safe to reduce the PTV margin from 5 to 4 mm for the elective pelvic lymph nodes for prostate patients treated with oART. Further margin reductions can be motivated for patients presenting little intrafraction motion.
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Affiliation(s)
- John Alfred Brennsæter
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Tordis Johnsen Dahle
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Jannicke Nøkling Moi
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | | | - Gry Sandvik Haaland
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
| | - Sara Pilskog
- Department of Oncology and Medical Physics, Haukeland University Hospital, Bergen, Norway
- Department of Physics and Technology, University of Bergen, Bergen, Norway
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Kong VC, Rosewall T, Catton C, Chung P, Warde P, Craig T, Bayley A. Prostate or bone? Comparing the efficacy of image guidance surrogates for pelvis and prostate radiotherapy using accumulated delivered dose. J Med Imaging Radiat Sci 2020; 52:14-21. [PMID: 33139231 DOI: 10.1016/j.jmir.2020.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 09/30/2020] [Accepted: 10/02/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION This study assessed the impact of dosimetry to both the target and normal tissue when either bony anatomy (BA) or prostate (PRO) was used as surrogates for image guidance for pelvis and prostate radiotherapy using a dose accumulation process. METHODS Thirty patients who were prescribed 50-54Gy to the pelvic lymph nodes (PLN) and 78Gy to the prostate/seminal vesicles were included. Daily acquired CBCTs were rigidly registered to the CT using BA and PRO to simulate two different treatment positions. The accumulated delivered dose (DAcc) of PLN, prostate, bladder and rectum for each surrogate were compared with the planned dose. Deviation from the planned dose (ΔDAcc-Plan) of >5% was considered clinically significant. RESULTS Prostate was displaced from bony anatomy by > 5 mm in 96/755 fractions (12.7%). Deviation between the mean DAcc and the planned dose for PLN and prostate was <2% when either BA or PRO was used. No significant deviation from planned dose was observed for bladder (p > 0.2). In contrary, DAcc for rectum D50 was significantly greater than the planned dose when BA was used (Mean ΔDAcc-Plan = 6%). When examining individual patient, deviation from the planned dose for rectum D50 was clinically significant for 18 patients for BA (Range: 5-21%) and only 8 patients for PRO (Range: 5-8%). CONCLUSIONS The use of either BA or PRO for image guidance could deliver dose to PLN and prostate with minimal deviation from the plan using existing PTV margins. However, deviation for rectum was greater when BA was used.
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Affiliation(s)
- Vickie C Kong
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada.
| | - Tara Rosewall
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada
| | - Charles Catton
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada
| | - Peter Chung
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada
| | - Padraig Warde
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada
| | - Tim Craig
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada
| | - Andrew Bayley
- Radiation Medicine Program, Princess Margaret Cancer Centre, Department of Radiation Oncology, University of Toronto, Toronto, Canada
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Lawes R, Carter E, Hussein M, Murray J, McNair HA. Retrospective audit of inter-fraction motion for pelvic node radiotherapy in prostate cancer patients. Radiography (Lond) 2020; 27:266-271. [PMID: 32830012 DOI: 10.1016/j.radi.2020.08.002] [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: 04/16/2020] [Revised: 07/31/2020] [Accepted: 08/03/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Pelvic lymph nodes move independently to the prostate. When delivering radiotherapy to prostate and pelvic lymph nodes, daily inter- and intra-fraction anatomical changes need to be accounted for. Planning target volume (PTV) margins, grown from the pelvic lymph node clinical target volume need to be determined, to account for this variation in position. METHODS Twenty patients who had daily online image guided radiotherapy to prostate and pelvic lymph nodes between April and December 2018 were selected. Ten pre-treatment verification images using cone beam CT from each patient were registered to pelvic bone anatomy, prostate soft tissue or fiducial markers and pelvic lymph node soft tissue to assess the accuracy of treatment delivery. Population systematic and random errors and PTV margins were calculated. RESULTS PTV margins of 0.4 cm, 0.4 cm and 0.7 cm left-right (LR), superior-inferior (SI) and anterior-posterior (AP) respectively were derived for the pelvic lymph nodes when registering to prostate. PTV margins of 0.3 cm, 0.2 cm and 0.4 cm LR, SI and AP respectively were derived for the pelvic lymph nodes when registering to bone. There was a posterior systematic shift of the prostate during the treatment course. CONCLUSION There is differential motion of pelvic lymph nodes to prostate and in the era of prostate and pelvic radiotherapy for patients with node positive prostate cancer; there is increasing importance in the accuracy of dose delivery to the involved lymph node. Hence, this group of patients may benefit from personalised radiotherapy PTV margins, especially if the involved pelvic lymph node is within the anterior part of the clinical target volume. IMPLICATIONS FOR PRACTICE Optimisation of dose delivery to the pelvic lymph nodes when prioritising the prostate in prostate and pelvic lymph node image guided radiotherapy.
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Affiliation(s)
- R Lawes
- Radiotherapy, Royal Marsden NHS Foundation Trust, UK.
| | - E Carter
- Radiotherapy, Royal Marsden NHS Foundation Trust, UK
| | - M Hussein
- Radiotherapy, Royal Marsden NHS Foundation Trust, UK
| | - J Murray
- Radiotherapy, Royal Marsden NHS Foundation Trust, UK; Academic Urology Unit, Royal Marsden NHS Foundation Trust, UK; Institute of Cancer Research, UK
| | - H A McNair
- Radiotherapy, Royal Marsden NHS Foundation Trust, UK; Institute of Cancer Research, UK
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Tyagi N, Hipp E, Cloutier M, Charas T, Fontenla S, Mechalakos J, Hunt M, Zelefsky M. Impact of daily soft-tissue image guidance to prostate on pelvic lymph node (PLN) irradiation for prostate patients receiving SBRT. J Appl Clin Med Phys 2019; 20:121-127. [PMID: 31206236 PMCID: PMC6612686 DOI: 10.1002/acm2.12665] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 04/25/2019] [Accepted: 05/29/2019] [Indexed: 12/25/2022] Open
Abstract
PURPOSE To determine the impact of using fiducial match for daily image-guidance on pelvic lymph node (PLN) coverage for prostate cancer patients receiving stereotactic body radiation therapy (SBRT). METHODS Thirty patients underwent SBRT treatment to the prostate and PLN from 2014 to 2016. Each patient received either 800cGy × 5 or 500cGy × 5 to the prostate and 500cGy × 5 to the PLN. A 5 mm clinical target volume (CTV)-to-planning target volume (PTV) margin around the PLN was used for planning. Two registrations with planning computed tomography (PCT) for each of the daily cone beam CTs (CBCTs) were performed: a rigid registration to fiducials and to the bony anatomy. The average translational difference between fiducial and bony match as well as percentage of fractions with differences > 5mm were calculated. Changes in bladder and rectal volume as well as center-of-mass (COM) position from simulation parameters, and their correlation with translational difference were also evaluated. The dosimetric impact of the translational differences was calculated by shifting the plan isocenter. RESULTS The average translational difference between fiducial and bony match was 0.06 ± 0.82, 2.1 ± 4.1, -2.8 ± 4.3, and 5.5 ± 4.2 mm for lateral, vertical, longitudinal, and vector directions. The average change in bladder and rectal volume from simulation was -67.2 ± 163.04 cc (-12 ± 52%) and -1.6 ± 18.75 (-2 ± 30%) cc. The average change in COM of bladder from the simulation position was 0.34 ± 2.49, 4.4 ± 8.1, and -3.9 ± 7.5 mm along the LR, AP, and SI directions. The corresponding COM change for the rectum was 0.17 ± 1.9, 1.34 ± 3.5, and -0.6 ± 5.2 mm. CONCLUSIONS The 5 mm margin covered ~75% of fractions receiving PLN irradiation with SBRT, daily CBCT and fiducial-guided setup. The dosimetric impact on PLN coverage was significant in 19% of fractions or 25% of patients. A larger translational shift was due to variation in rectal volume and changes in COM position of the bladder and rectum. A consistent bladder positioning and/or rectum filling compared with presimulation volume were essential for adequate coverage of PLN in a hypofractionated treatment regime.
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Affiliation(s)
- Neelam Tyagi
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Elizabeth Hipp
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Michelle Cloutier
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Tomer Charas
- Department of Radiation OncologyMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Sandra Fontenla
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - James Mechalakos
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Margie Hunt
- Department of Medical PhysicsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Michael Zelefsky
- Department of Radiation OncologyMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
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Kishan AU, Tyran M, Weng J, Upadhyaya S, Lamb J, Steinberg M, King C, Cao M. Stereotactic body radiotherapy to the prostate and pelvic lymph nodes: A detailed dosimetric analysis of a phase II prospective trial. Br J Radiol 2019; 92:20181001. [PMID: 30912957 DOI: 10.1259/bjr.20181001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
OBJECTIVE To evaluate the dosimetric ramifications of simultaneously irradiating the prostate and pelvic lymph nodes (PLNs) with a stereotactic body radiotherapy approach based on rigid registration to intraprostatic markers (IPMs). METHODS AND MATERIALS Nineteen patients received concurrent SBRT to the prostate and PLNs on a phase II clinical trial. The translational and rotation shifts required for rigid registration to bony anatomy and changes in bladder and rectal anatomy were compared between patients with > 90% and < 90% coverage of the nodal clinical target volume (CTVN ) as drawn on fractional kilovoltage cone-beam CTs. Stepwise multivariable regression models evaluated relationships between these anatomical parameters and the change in V100%CTVN. RESULTS The average V100%CTVN per patient was 92.4 % (IQR, 90.2 - 96.4 %). For five patients (26.3%), the average was 85.0 % (IQR, 82.4-88.3 %). The left-right and superior-inferior translational shifts, sagittal rotational shift, and change in bladder volume were significantly different ( p < 0.05 for all via Student's t-test). Changes in bladder height, left/right shift, superior/inferior shift, 3-D shift, and axial rotation as significant predictors of change in dosing of V100%CTVN. CONCLUSION While simultaneous SBRT to the prostate and PLNs based on rigid registration to IPMs provides adequate PLN coverage in most instances, overall coverage may be lower than anticipated if anatomy is unstable. Careful evaluation of bladder filling on kV-CBCT before treatment may be the most practical method for estimating accuracy prior to treatment. ADVANCES IN KNOWLEDGE Simultaneous SBRT to the prostate and PLNs based on rigid registration to IPMs provides adequate PLN coverage in most instances.
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Affiliation(s)
- Amar U Kishan
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA.,2 Department of Urology, University of California , Los Angeles , USA
| | - Marguerite Tyran
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA.,3 Institut Paoli Calmettes , Marseille , France
| | - Julius Weng
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA
| | - Shrinivasa Upadhyaya
- 4 Department of Biological and Agricultural Engineering, University of California , Davis , USA
| | - James Lamb
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA
| | - Michael Steinberg
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA
| | - Christopher King
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA
| | - Minsong Cao
- 1 Department of Radiation Oncology, University of California , Los Angeles , USA
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Björeland U, Jonsson J, Alm M, Beckman L, Nyholm T, Thellenberg-Karlsson C. Inter-fraction movements of the prostate and pelvic lymph nodes during IGRT. ACTA ACUST UNITED AC 2018; 7:357-366. [PMID: 30595810 PMCID: PMC6290663 DOI: 10.1007/s13566-018-0366-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 11/15/2018] [Indexed: 12/25/2022]
Abstract
Objectivities The aim of this study was to evaluate inter-fraction movements of lymph node regions that are commonly included in the pelvic clinical target volume (CTV) for high-risk prostate cancer patients. We also aimed to evaluate if the movements affect the planning target volumes. Methods Ten prostate cancer patients were included. The patients underwent six MRI scans, from treatment planning to near end of treatment. The CTV movements were analyzed with deformable registration technique with the CTV divided into sections. The validity of the deformable registration was assessed by comparing the results for individual lymph nodes that were possible to identify in all scans. Results Using repetitive MRI, measurements showed that areas inside the CTV (lymph nodes) in some extreme cases were as mobile as the prostate and not fixed to the bones. The lymph node volumes closest to the prostate did not tend to follow the prostate motion. The more cranial lymph node volumes moved less, but still independently, and they were not necessarily fixed to the pelvic bones. In 95% of the cases, the lymph node motion in the R-L direction was 2–4 mm, in the A-P direction 2–7 mm, and in the C-C direction 2–5 mm depending on the CTV section. Conclusion Lymph nodes and prostate were most mobile in the A-P direction, followed by the C-C and R-L directions. This movement should be taken into account when deciding the margins for the planning target volumes (PTV). Electronic supplementary material The online version of this article (10.1007/s13566-018-0366-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ulrika Björeland
- Department of Radiation Sciences, Umeå University, Sjukhusfysik, Sundsvallssjukhus, 85186 Sundsvall, Sweden
| | - Joakim Jonsson
- Department of Radiation Sciences, Umeå University, Sjukhusfysik, Sundsvallssjukhus, 85186 Sundsvall, Sweden
| | - Magnus Alm
- Department of Radiation Sciences, Umeå University, Sjukhusfysik, Sundsvallssjukhus, 85186 Sundsvall, Sweden
| | - Lars Beckman
- Department of Radiation Sciences, Umeå University, Sjukhusfysik, Sundsvallssjukhus, 85186 Sundsvall, Sweden
| | - Tufve Nyholm
- Department of Radiation Sciences, Umeå University, Sjukhusfysik, Sundsvallssjukhus, 85186 Sundsvall, Sweden
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La radiothérapie externe guidée par l’imagerie dans le cancer de la prostate ; comment, quand et pourquoi ? Cancer Radiother 2018; 22:586-592. [DOI: 10.1016/j.canrad.2018.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Accepted: 06/29/2018] [Indexed: 12/14/2022]
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8
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van Nunen A, van der Toorn P, Budiharto T, Schuring D. Optimal image guided radiation therapy strategy for organs at risk sparing in radiotherapy of the prostate including pelvic lymph nodes. Radiother Oncol 2018; 127:68-73. [DOI: 10.1016/j.radonc.2018.02.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/09/2018] [Accepted: 02/11/2018] [Indexed: 10/17/2022]
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Lyons CA, King RB, Osman SO, McMahon SJ, O’Sullivan JM, Hounsell AR, Jain S, McGarry CK. A novel CBCT-based method for derivation of CTV-PTV margins for prostate and pelvic lymph nodes treated with stereotactic ablative radiotherapy. Radiat Oncol 2017; 12:124. [PMID: 28778178 PMCID: PMC5543558 DOI: 10.1186/s13014-017-0859-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 07/21/2017] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Traditional CTV-PTV margin recipes are not generally applicable in the situation of stereotactic ablative radiotherapy (SABR) treatments of multiple target volumes with a single isocentre. In this work, we present a novel geometric method of margin derivation based on CBCT-derived anatomical data. METHODS Twenty patients with high-risk localized prostate cancer were selected for retrospective review. Individual volumes of interest (prostate, prostate and seminal vesicles and pelvic lymph nodes) were delineated on five representative CBCTs and registered to the planning CT using two registration protocols: bone match or prostate-based soft tissue match. Margins were incrementally expanded around composite CTV structures until 95% overlap was achieved. RESULTS CTV-PTV margins of 5.2, 6.5 and 7.6 mm were required for prostate, prostate and seminal vesicles and pelvic lymph nodes respectively using a prostate matching protocol. For the prostate and seminal vesicle structures, margins calculated using our method displayed good agreement with a conventional margin recipe (within ±1.0 mm). CONCLUSIONS We have presented an alternative method of CTV-PTV margin derivation that is applicable to SABR treatments with more than one isocentric target. These results have informed an institutional trial of prostate and pelvic nodal SABR in men with high-risk localized prostate cancer.
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Affiliation(s)
- Ciara A. Lyons
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Raymond B. King
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Sarah O.S. Osman
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Stephen J. McMahon
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
| | - Joe M. O’Sullivan
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Alan R. Hounsell
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Suneil Jain
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Clinical Oncology, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
| | - Conor K. McGarry
- Centre for Cancer Research and Cell Biology, Queen’s University Belfast, Belfast, BT7 1NN UK
- Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast City Hospital, Belfast, UK
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Zaorsky NG, Showalter TN, Ezzell GA, Nguyen PL, Assimos DG, D'Amico AV, Gottschalk AR, Gustafson GS, Keole SR, Liauw SL, Lloyd S, McLaughlin PW, Movsas B, Prestidge BR, Taira AV, Vapiwala N, Davis BJ. ACR Appropriateness Criteria for external beam radiation therapy treatment planning for clinically localized prostate cancer, part II of II. Adv Radiat Oncol 2017; 2:437-454. [PMID: 29114613 PMCID: PMC5605284 DOI: 10.1016/j.adro.2017.03.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 03/10/2017] [Indexed: 12/21/2022] Open
Abstract
PURPOSE To present the most updated American College of Radiology (ACR) Appropriateness Criteria formed by an expert panel on the appropriate delivery of external beam radiation to manage stage T1 and T2 prostate cancer (in the definitive setting and post-prostatectomy) and to provide clinical variants with expert recommendations based on accompanying Appropriateness Criteria for target volumes and treatment planning. METHODS AND MATERIALS The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a panel of multidisciplinary experts. The guideline development and revision process includes an extensive analysis of current medical literature from peer-reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In instances in which evidence is lacking or equivocal, expert opinion may supplement available evidence to recommend imaging or treatment. RESULTS The panel summarizes the most recent and relevant literature on the topic, including organ motion and localization methods, image guidance, and delivery techniques (eg, 3-dimensional conformal intensity modulation). The panel presents 7 clinical variants, including (1) a standard case and cases with (2) a distended rectum, (3) a large-volume prostate, (4) bilateral hip implants, (5) inflammatory bowel disease, (6) prior prostatectomy, and (7) a pannus extending into the radiation field. Each case outlines the appropriate techniques for simulation, treatment planning, image guidance, dose, and fractionation. Numerical rating and commentary is given for each treatment approach in each variant. CONCLUSIONS External beam radiation is a key component of the curative management of T1 and T2 prostate cancer. By combining the most recent medical literature, these Appropriateness Criteria can aid clinicians in determining the appropriate treatment delivery and personalized approaches for individual patients.
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Affiliation(s)
| | | | - Gary A. Ezzell
- Mayo Clinic, Phoenix, Arizona (research author [contributing])
| | - Paul L. Nguyen
- Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, Massachusetts (panel vice-chair)
| | - Dean G. Assimos
- University of Alabama School of Medicine, Birmingham, Alabama (American Urological Association)
| | - Anthony V. D'Amico
- Dana-Farber Cancer Institute/Brigham and Women's Hospital, Boston, Massachusetts (American Society of Clinical Oncology)
| | | | | | | | | | - Shane Lloyd
- Huntsman Cancer Hospital, Salt Lake City, Utah
| | | | | | | | - Al V. Taira
- Mills Peninsula Hospital, San Mateo, California
| | - Neha Vapiwala
- University of Pennsylvania, Philadelphia, Pennsylvania
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11
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Rosewall T, Yan J, Alasti H, Cerase C, Bayley A. 'Compromise position' image alignment to accommodate independent motion of multiple clinical target volumes during radiotherapy: A high risk prostate cancer example. J Med Imaging Radiat Oncol 2016; 61:271-278. [PMID: 27709834 DOI: 10.1111/1754-9485.12543] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 09/04/2016] [Indexed: 12/25/2022]
Abstract
INTRODUCTION Inclusion of multiple independently moving clinical target volumes (CTVs) in the irradiated volume causes an image guidance conundrum. The purpose of this research was to use high risk prostate cancer as a clinical example to evaluate a 'compromise' image alignment strategy. METHODS The daily pre-treatment orthogonal EPI for 14 consecutive patients were included in this analysis. Image matching was performed by aligning to the prostate only, the bony pelvis only and using the 'compromise' strategy. Residual CTV surrogate displacements were quantified for each of the alignment strategies. RESULTS Analysis of the 388 daily fractions indicated surrogate displacements were well-correlated in all directions (r2 = 0.95 (LR), 0.67 (AP) and 0.59 (SI). Differences between the surrogates displacements (95% range) were -0.4 to 1.8 mm (LR), -1.2 to 5.2 mm (SI) and -1.2 to 5.2 mm (AP). The distribution of the residual displacements was significantly smaller using the 'compromise' strategy, compared to the other strategies (p 0.005). The 'compromise' strategy ensured the CTV was encompassed by the PTV in all fractions, compared to 47 PTV violations when aligned to prostate only. CONCLUSIONS This study demonstrated the feasibility of a compromise position image guidance strategy to accommodate simultaneous displacements of two independently moving CTVs. Application of this strategy was facilitated by correlation between the CTV displacements and resulted in no geometric excursions of the CTVs beyond standard sized PTVs. This simple image guidance strategy may also be applicable to other disease sites that concurrently irradiate multiple CTVs, such as head and neck, lung and cervix cancer.
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Affiliation(s)
- Tara Rosewall
- Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Jing Yan
- Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Hamideh Alasti
- Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
| | - Carla Cerase
- Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada
| | - Andrew Bayley
- Radiation Medicine Program, Princess Margaret Hospital, Toronto, Ontario, Canada.,Department of Radiation Oncology, University of Toronto, Toronto, Ontario, Canada
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Katayama H, Ookubo M, Tsuzuki M, Sasakawa Y, Takahashi S, Shibata T. [Impact of Pelvic Rotational Setup Error on Lymph Nodal Dose in Whole Pelvic IMRT Using Fiducial Markers]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2016; 72:1152-1160. [PMID: 27867176 DOI: 10.6009/jjrt.2016_jsrt_72.11.1152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
PURPOSE The aim of this study was to investigate the impact of pelvic rotational setup error on lymph nodal dose in the whole pelvic intensity-modulated radiation therapy using the fiducial marker. METHODS The dose differences of clinical target volume for pelvic lymph node (CTVLN) due to isocenter (IC) shift and pelvic rotation were evaluated using the radiation treatment planning system. The rotated computed tomography (CT) images were created for the simulation of the pelvic rotation. The original CT images were rotated around the IC of the original plan in the pitch and roll directions up to±3.0 deg. at 1.0 deg. intervals. As simulated plans, IC positions were shifted in the anterior-posterior and superior-inferior directions up to±10 mm at 2 mm intervals in the original and rotated CT images, and the dose distributions were calculated. The dose calculation was performed for each CT image while keeping the movement of multi leaf collimator and the monitor unit of the original plan. The differences between D98% of CTVLN in the original plan and simulated plans were calculated. RESULTS In the posterior direction shifts of 4, 6, 8, and 10 mm, the dose reduction of 0.7, 2.1, 6.1, and 11.9% from the original plan were found for D98% of CTVLN, respectively. The dose reductions due to the rotation of pitch direction were greater than the rotation of roll direction. In the posterior direction shifts of 4, 6, 8, and 10 mm with 3.0 deg. rotation of pitch direction, the dose reduction of 2.2, 6.8, 12.8, and 19.0% from the original plan were found, respectively. CONCLUSION The dose reduction of CTVLN might be occurred due to the rotational setup error of pitch direction.
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Affiliation(s)
- Hiroki Katayama
- Department of Clinical Radiology, Kagawa University Hospital
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Lecavalier-Barsoum M, Souhami L, Cury F, Duclos M, Ruo R, Faria S. Pelvic lymph node displacement in high-risk prostate cancer patients treated with image guided intensity modulated radiation therapy with 2 independent target volumes. Pract Radiat Oncol 2015; 5:406-10. [PMID: 26127006 DOI: 10.1016/j.prro.2015.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Revised: 04/07/2015] [Accepted: 05/10/2015] [Indexed: 01/06/2023]
Abstract
PURPOSE To evaluate the displacement of the pelvic lymph node (PLN) target when using cone beam computed tomography (CBCT) for localization of the prostate in patients treated with simultaneous integrated boost. METHODS AND MATERIALS High-risk prostate cancer patients treated with image guided intensity modulated radiation therapy with simultaneous integrated boost receiving 60 Gy in 20 fractions to the prostate and proximal seminal vesicles (PTV60) and 44 Gy in the same 20 fractions to the PLN (PTV44) were studied. Two hundred weekly CBCTs of 50 patients were retrospectively reviewed to assess the displacement of the iliac vessels compared with the simulation computed tomography. For each CBCT, possible displacements were analyzed at 3 levels of PTV44: a superior, middle, and inferior slice, making a total of 600 slices reviewed. Geographical miss (GM) was defined when any part of the iliac vessels on the CBCT was outside of the PTV44 contour. RESULTS GM was found in 7 of the 600 CBCT slices, all in different patients. All GMs were of ≤5 mm. Four GMs occurred on the middle slice and 3 on the superior slice. In 3 cases, the GM was related to shifts ≥7 mm applied to the prostate. CONCLUSIONS Our review suggests that for high-risk prostate cancer, the chance of not appropriately covering the PLN target after adjusting the prostate is low. GM was uncommon and in the order of only a few millimeters when it occurred.
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Affiliation(s)
- Magali Lecavalier-Barsoum
- Department of Radiation Oncology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Luis Souhami
- Department of Radiation Oncology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Fabio Cury
- Department of Radiation Oncology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Marie Duclos
- Department of Radiation Oncology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Russel Ruo
- Department of Medical Physics, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
| | - Sergio Faria
- Department of Radiation Oncology, McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada.
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Kishan AU, Lamb JM, Jani SS, Kang JJ, Steinberg ML, King CR. Pelvic nodal dosing with registration to the prostate: implications for high-risk prostate cancer patients receiving stereotactic body radiation therapy. Int J Radiat Oncol Biol Phys 2015; 91:832-9. [PMID: 25752398 DOI: 10.1016/j.ijrobp.2014.11.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/28/2014] [Accepted: 11/24/2014] [Indexed: 10/23/2022]
Abstract
PURPOSE To determine whether image guidance with rigid registration (RR) to intraprostatic markers (IPMs) yields acceptable coverage of the pelvic lymph nodes in the context of a stereotactic body radiation therapy (SBRT) regimen. METHODS AND MATERIALS Four to seven kilovoltage cone-beam CTs (CBCTs) from 12 patients with high-risk prostate cancer were analyzed, allowing approximation of an SBRT regimen. The nodal clinical target volume (CTV(N)) and bladder were contoured on all kilovoltage CBCTs. The V100 CTV(N), expressed as a ratio to the same parameter on the initial plan, and the magnitude of translational shift between RR to the IPMs versus RR to the pelvic bones, were computed. The ability of a multimodality bladder filling protocol to minimize bladder height variation was assessed in a separate cohort of 4 patients. RESULTS Sixty-five CBCTs were assessed. The average V100 CTV(N) was 92.6%, but for a subset of 3 patients the average was 80.0%, compared with 97.8% for the others (P<.0001). The average overall and superior-inferior axis magnitudes of the bony-to-fiducial translations were significantly larger in the subgroup with suboptimal nodal coverage (8.1 vs 3.9 mm and 5.8 vs 2.4 mm, respectively; P<.0001). Relative bladder height changes were also significantly larger in the subgroup with suboptimal nodal coverage (42.9% vs 18.5%; P<.05). Use of a multimodality bladder-filling protocol minimized bladder height variation (P<.001). CONCLUSION A majority of patients had acceptable nodal coverage after RR to IPMs, even when approximating SBRT. However, a subset of patients had suboptimal nodal coverage. These patients had large bony-to-fiducial translations and large variations in bladder height. Nodal coverage should be excellent if the superior-inferior axis bony-to-fiducial translation and the relative bladder height change (both easily measured on CBCT) are kept to a minimum. Implementation of a strict bladder filling protocol may achieve this goal.
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Affiliation(s)
- Amar U Kishan
- Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California.
| | - James M Lamb
- Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Shyam S Jani
- Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Jung J Kang
- Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Michael L Steinberg
- Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
| | - Christopher R King
- Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California
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Eminowicz G, Dean C, Shoffren O, Macdougall N, Wells P, Muirhead R. Intensity-modulated radiotherapy (IMRT) to prostate and pelvic nodes-is pelvic lymph node coverage adequate with fiducial-based image-guided radiotherapy? Br J Radiol 2014; 87:20130696. [PMID: 24646126 PMCID: PMC4075533 DOI: 10.1259/bjr.20130696] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Revised: 01/20/2014] [Accepted: 03/17/2014] [Indexed: 12/25/2022] Open
Abstract
OBJECTIVE There remains concern regarding the use of fiducial-based image-guided radiotherapy (IGRT) in patients with high-risk prostate cancer also undergoing intensity-modulated radiotherapy (IMRT) to pelvic nodes. By a retrospective study, we aim to ascertain the impact of the use of fiducial-based IGRT on lymph node planned target volume (PTV) coverage. METHODS 30 consecutive IMRT prostate and pelvic node plans were reviewed, and dose was recalculated with 1-mm increment movements in anterior, posterior, superior, inferior, right and left directions up to 10 mm. All patients were treated with a full bladder after drinking 450-750 ml of water and empty rectum with the use of sodium citrate enemas daily. Dose-volume histogram parameters were recorded at each position, specifically nodal PTV V95%, V99% and V100%. A local IGRT database was used to identify the likelihood of a particular bony to fiducial offset in all directions. The combined data were used to calculate the percentage risk of underdosing the lymph node PTV on any given fraction. RESULTS The likelihood of an offset in the left, right and anterior directions occurring and resulting in a failure to cover the PTV was <0.25%. The likelihood of a posterior offset occurring and resulting in inadequate coverage was slightly higher but remained <1%. CONCLUSION This study confirms the safety of fiducial-based image-guided IMRT (IG-IMRT) with a strict bowel and bladder protocol, allowing a reduction of the clinical target volume to PTV margin of the prostate volume and consequent reduction in rectal toxicity. ADVANCES IN KNOWLEDGE This study strengthens the evidence supporting the safe implementation of fiducial-based IG-IMRT treating the prostate and pelvic nodes in high-risk prostate cancer.
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Affiliation(s)
- G Eminowicz
- Department of Radiotherapy, St Bartholomew's Hospital, London, UK
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Treatment simulations with a statistical deformable motion model to evaluate margins for multiple targets in radiotherapy for high-risk prostate cancer. Radiother Oncol 2013; 109:344-9. [DOI: 10.1016/j.radonc.2013.09.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Revised: 08/30/2013] [Accepted: 09/20/2013] [Indexed: 11/19/2022]
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Thörnqvist S, Hysing LB, Zolnay AG, Söhn M, Hoogeman MS, Muren LP, Heijmen BJM. Adaptive radiotherapy in locally advanced prostate cancer using a statistical deformable motion model. Acta Oncol 2013; 52:1423-9. [PMID: 23964658 DOI: 10.3109/0284186x.2013.818249] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
UNLABELLED Daily treatment plan selection from a plan library is a major adaptive radiotherapy strategy to account for individual internal anatomy variations. This strategy depends on the initial input images being representative for the variations observed later in the treatment course. Focusing on locally advanced prostate cancer, our aim was to evaluate if residual motion of the prostate (CTV-p) and the elective targets (CTV-sv, CTV-ln) can be prospectively accounted for with a statistical deformable model based on images acquired in the initial part of treatment. METHODS Thirteen patients with locally advanced prostate cancer, each with 9-10 repeat CT scans, were included. Displacement vectors fields (DVF) obtained from contour-based deformable registration of delineations in the repeat- and planning CT scans were used to create patient-specific statistical motion models using principal component analysis (PCA). For each patient and CTV, four PCA-models were created: one with all 9-10 DVF as input in addition to models with only four, five or six DVFs as input. Simulations of target shapes from each PCA-model were used to calculate iso-coverage levels, which were converted to contours. The levels were analyzed for sensitivity and precision. RESULTS A union of the simulated shapes was able to cover at least 97%, 97% and 95% of the volumes of the evaluated CTV shapes for PCA-models using six, five and four DVFs as input, respectively. There was a decrease in sensitivity with higher iso-coverage levels, with a sharper decline for greater target movements. Apart from having the steepest decline in sensitivity, CTV-sv also displayed the greatest influence on the number of geometries used in the PCA-model. CONCLUSIONS PCA-based simulations of residual motion derived from four to six DVFs as input could account for the majority of the target shapes present during the latter part of the treatment. CTV-sv displayed the greatest range in both sensitivity and precision.
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Affiliation(s)
- Sara Thörnqvist
- Department of Medical Physics, Aarhus University Hospital , Aarhus , Denmark
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Dosimetric consequences of prostate-based couch shifts on the precision of dose delivery during simultaneous IMRT irradiation of the prostate, seminal vesicles and pelvic lymph nodes. Phys Med 2013; 30:228-33. [PMID: 23860339 DOI: 10.1016/j.ejmp.2013.06.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/02/2013] [Accepted: 06/25/2013] [Indexed: 11/20/2022] Open
Abstract
INTRODUCTION To evaluate the impact interfraction prostate (CTV1) motion corrections on doses delivered to seminal vesicles (CTV2) and lymph nodes (CTV3), and to determine ideal planning target volume (PTV) margins for these targets with prostate-based position verification. MATERIAL AND METHODS Retrospective analysis based on 253 cone beam computed tomography (CBCT) studies of 28 patients. The isocenter-shift method was used to estimate the interfraction prostate and bony shift effects on the original plan coverage. Friedman's test was used to assess statistical significance between dose-volume histogram (DVH) parameters which were calculated for prostate-based sum plans, bony-based sum plans and original treatment plans. The van Herk formula was used to determine the set-up margin size for prostate-based verification. RESULTS The tracked shifts influenced the minimum, maximum and mean CTV2 and CTV3 doses, with a range differential of 0.17%-2.63% (prostate shifts) and 0.13%-1.92% (bony shifts) compared to the corresponding original parameters. Friedman's test revealed significant differences in the minimum doses to the CTV3 and maximum doses to both the CTV2 and CTV3. The calculated set-up margins of 1.22 cm (vertical), 0.19 cm (longitudinal) and 0.39 cm (lateral) should be added to CTV3 while performing prostate-based positioning. CONCLUSION To avoid geographical miss during simultaneous irradiation of independently moving targets (CTV1-3) appropriate margins should be used in accordance with the position verification method used. Based on our findings the following margin sizes should be used: 0.7 cm for the CTV1, 0.8-0.9 cm for the CTV2 , and asymmetric 1.0 cm (vertically) and 0.5 cm (other axes) for the CTV3.
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Optimal planning target volume margins for elective pelvic lymphatic radiotherapy in high-risk prostate cancer patients. ISRN ONCOLOGY 2013; 2013:941269. [PMID: 23533814 PMCID: PMC3606762 DOI: 10.1155/2013/941269] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 02/04/2013] [Indexed: 12/04/2022]
Abstract
Purpose.
High-risk prostate cancer patients often receive radiotherapy (RT) to pelvic lymphatics (PLs). The aim of this study was to determine the safety
margin around clinical target volume for PL (PL-CTV) to construct planning target volume for PL (PL-PTV) and for planning elective PL irradiation.
Methods and Materials.
Six patients who received RT to PL as part of prostate cancer treatment were identified. To determine average daily shifts of PL,
the right and left IVs were contoured at 3 predetermined slices on the daily MV scans and their daily shifts were measured at these 3 levels using a measuring tool.
Results.
A total of 1,932 observations were made. Daily shifts of IV were random in distribution, and the largest observed shift was 13.6 mm in lateral and 15.4 mm
in AP directions. The mean lateral and AP shifts of IV were 2.1 mm (±2.2) and 3.5 mm (±2.7), respectively.
The data suggest that AP and lateral margins of 8.9 mm and 6.5 mm are necessary.
Conclusions.
With daily alignment to the prostate, we recommend an additional PL-CTV to PL-PTV conversion margin of 9 mm (AP) and 7 mm (lateral)
to account for daily displacement of PL relative to the prostate.
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Créhange G, Martin E, Supiot S, Chapet O, Mazoyer F, Naudy S, Maingon P. Radiothérapie guidée par l’image des cancers prostatiques : concepts et implications. Cancer Radiother 2012; 16:430-8. [DOI: 10.1016/j.canrad.2012.07.183] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Accepted: 07/13/2012] [Indexed: 11/26/2022]
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Thörnqvist S, Bentzen L, Petersen JBB, Hysing LB, Muren LP. Plan robustness of simultaneous integrated boost radiotherapy of prostate and lymph nodes for different image-guidance and delivery techniques. Acta Oncol 2011; 50:926-34. [PMID: 21767193 DOI: 10.3109/0284186x.2011.590522] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND AND PURPOSE Uncorrelated motion of targets and large deformations of organs at risk represent challenges for image-guidance in simultaneous integrated boost (SIB) radiotherapy (RT) of pelvic tumour sites. This study aims to evaluate the robustness towards geometrical uncertainties in prostate cancer using two image-guided RT (IGRT) set-up strategies for two SIB delivery methods. Secondly, we evaluate the ability of geometrical parameters to predict when the applied margins are insufficient, resulting in target underdosage (TUD). MATERIAL AND METHODS The study included nine patients with eight to nine repeat computed tomography (CT)-scans evenly distributed throughout their treatment course. The prostate target (CTV-p) and the lymph node target including seminal vesicles (CTV-ln/sv) were delineated in all scans. SIB treatment plans for intensity-modulated RT and volumetric modulated arc therapy were generated on the planning CT and transferred to the repeat CTs for dose re-calculation using registration based on either anatomy or intra-prostatic fiducial markers. Receiving operator characteristic analysis was used to deduce the ability of the parameters to predict TUD. RESULTS The dosimetric differences between the two positioning strategies were small for all parameters evaluated and significant only for the dose to rectum. Anatomy based registration resulted in inferior target coverage with a larger number of TUDs, mostly seen in the seminal vesicles. For both targets the highest sensitivity and specificity of predicting TUD was seen for the relative volume and the lowest was found for the displacement vector. CONCLUSIONS Positioning based on fiducials gave the best trade-off between coverage of the targets although resulting in the highest dose to rectum. Target underdosage occurred mostly in the seminal vesicles. For both targets, the best parameter to predict TUD was the relative volume.
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Thörnqvist S, Petersen JBB, Høyer M, Bentzen LN, Muren LP. Propagation of target and organ at risk contours in radiotherapy of prostate cancer using deformable image registration. Acta Oncol 2010; 49:1023-32. [PMID: 20831491 DOI: 10.3109/0284186x.2010.503662] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND Successful deformable image registration is an essential component of both dose accumulation and plan adaptation in radiotherapy. The aim of this study was to evaluate the performance of a deformable image registration application for propagation of contours using repeat CT scans of the pelvis, a region where considerable deformations are expected. MATERIAL AND METHODS The study involved four prostate cancer patients, each with 9-11 repeat CT scans. An oncologist contoured bladder, rectum, clinical target volume of pelvic lymph nodes (CTV-ln) and prostate (CTV-p) in all CT scans. The reference CT was retrospectively registered to the repeat CT scans with both rigid and deformable registration using a recently released commercial clinical software application. Two different diffusion-based 'demons' deformable registration algorithms were applied, differing in the amount of deformations being allowed, with algorithm A being more generous than algorithm B. The evaluation of the propagated structures included both quantitative measures and qualitative scoring. RESULTS We found the differences between the algorithms to be most evident for bladder and rectum. An increase in mean Dice similarity coefficient relative the rigid registrations of 12% and 13% was obtained with algorithm A for bladder and rectum, compared to 2% with algorithm B. For bladder the mean sensitivity and positive predictive value was 0.92 and 0.87 with algorithm A and 0.82 and 0.83 with algorithm B. Corresponding values for rectum was 0.81 and 0.76 with algorithm A and 0.75 and 0.69 with algorithm B. This translated into 57% and 26% passing the clinical evaluation for bladder and rectum, with algorithm A, compared to 17% and 14% with algorithm B. For CTV-ln and CTV-p both algorithms performed well by all measures, e.g. with 86% of the target structures passing the clinical evaluation. CONCLUSIONS Deformable image registration improved contour propagation in the pelvis for all organs investigated. Differences in the performance of the algorithms were seen which became more pronounced for the highly deformable organs of bladder and rectum.
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van Rooijen DC, Pool R, van de Kamer JB, Hulshof MCCM, Koning CCE, Bel A. Independent position correction on tumor and lymph nodes; consequences for bladder cancer irradiation with two combined IMRT plans. Radiat Oncol 2010; 5:53. [PMID: 20550672 PMCID: PMC2893191 DOI: 10.1186/1748-717x-5-53] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Accepted: 06/15/2010] [Indexed: 11/22/2022] Open
Abstract
Background The application of lipiodol injections as markers around bladder tumors combined with the use of CBCT for image guidance enables daily on-line position correction based on the position of the bladder tumor. However, this might introduce the risk of underdosing the pelvic lymph nodes. In this study several correction strategies were compared. Methods For this study set-up errors and tumor displacements for ten complete treatments were generated; both were based on the data of 10 bladder cancer patients. Besides, two IMRT plans were made for 20 patients, one for the elective field and a boost plan for the tumor. For each patient 10 complete treatments were simulated. For each treatment the dose was calculated without position correction (option 1), correction on bony anatomy (option 2), on tumor only (option 3) and separately on bone for the elective field (option 4). For each method we analyzed the D99% for the tumor, bladder and lymph nodes and the V95% for the small intestines, rectum, healthy part of the bladder and femoral heads. Results CTV coverage was significantly lower with options 1 and 2. With option 3 the tumor coverage was not significantly different from the treatment plan. The ΔD99% (D99%, option n - D99%, treatment plan) for option 4 was small, but significant. For the lymph nodes the results from option 1 differed not significantly from the treatment plan. The median ΔD99% of the other options were small, but significant. ΔD99% for PTVbladder was small for options 1, 2 and 4, but decreased up to -8.5 Gy when option 3 was applied. Option 4 is the only method where the difference with the treatment plan never exceeds 2 Gy. The V95% for the rectum, femoral heads and small intestines was small in the treatment plan and this remained so after applying the correction options, indicating that no additional hot spots occurred. Conclusions Applying independent position correction on bone for the elective field and on tumor for the boost separately gives on average the best target coverage, without introducing additional hot spots in the healthy tissue.
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