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Dupont F, Dechambre D, Sterpin E. Evaluation of safety margins for cone beam CT-based adaptive prostate radiotherapy. Phys Med 2024; 121:103368. [PMID: 38663348 DOI: 10.1016/j.ejmp.2024.103368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Revised: 04/15/2024] [Accepted: 04/19/2024] [Indexed: 05/12/2024] Open
Abstract
Adaptive radiotherapy is characterized by the use of a daily imaging system, such as CBCT (Cone-Beam Computed Tomography) images to re-optimize the treatment based on the daily anatomy and position of the patient. By systematically re-delineating the Clinical Target Volume (CTV) at each fraction, target delineation uncertainty features a random component instead of a pure systematic. The goal of this work is to identify the random and systematic contributions of the delineation error and compute a new relevant Planning Target Volume (PTV) safety margin. 169 radiotherapy sessions from 10 prostate cancer patients treated on the Varian ETHOS treatment system have been analyzed. Intra-patient and inter-patient delineation variabilities were computed in six directions, by considering the prostate as a rigid, non-rotating volume. By doing so, we were able to directly compare the delineations done by the physicians on daily CBCT images with the initial delineation done on the CT-sim and MRI, and sort them by direction using the polar coordinates of the points. The computed variabilities were then used to compute a PTV margin based on Van Herk margin recipe. The total margin computed with random and systematic delineation uncertainties was of 2.7, 2.4, 5.6, 4.8, 4.9 and 3.6 mm in the left, right, anterior, posterior, cranial and caudal directions, respectively. According to our results, the gain offered by the separation of the delineation uncertainty into systematic and random contributions due to the adaptive delineation process justifies a reduction of the PTV margin down to 3 to 5 mm in every direction.
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Affiliation(s)
- Florian Dupont
- UCLouvain, Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Brussels, Belgium; Cliniques Universitaires Saint-Luc (CUSL), Nuclear Medicine Department, Brussels, Belgium.
| | - David Dechambre
- Cliniques Universitaires Saint-Luc (CUSL), Radiotherapy Department, Brussels, Belgium
| | - Edmond Sterpin
- UCLouvain, Center of Molecular Imaging, Radiotherapy and Oncology (MIRO), Brussels, Belgium; KU Leuven, Department of Oncology, Laboratory of Experimental Radiotherapy, Leuven, Belgium; Particle Therapy Interuniversity Center Leuven (ParTICLe), Leuven, Belgium
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Shimomura A, Wu T, Rusu I, Kishan AU, Tree AC, Solanki AA, Liauw SL. Monitoring Intrafraction Motion of the Prostate During Radiation Therapy: Suggested Practice Points From a Focused Review. Pract Radiat Oncol 2024; 14:146-153. [PMID: 37875222 DOI: 10.1016/j.prro.2023.08.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/30/2023] [Accepted: 08/31/2023] [Indexed: 10/26/2023]
Abstract
PURPOSE External beam radiation therapy to the prostate is typically delivered after verification of prostatic position with image guidance. Prostate motion can occur during the delivery of each radiation treatment between the time of localization imaging and completion of treatment. The objective of this work is to review the literature on intrafraction motion (IFM) of the prostate during radiation therapy and offer clinical recommendations on management. METHODS AND MATERIALS A comprehensive literature review was conducted on prostate motion during prostate cancer radiation therapy. Information was organized around 3 key clinical questions, followed by an evidence-based recommendation. RESULTS IFM of the prostate during radiation therapy is typically ≤3 mm and is unlikely to compromise prostate dosimetry to a clinically meaningful degree for men treated in a relatively short treatment duration with planning target volume (PTV) margins of ≥3 to 5 mm. IFM of 5 mm or more has been observed in up to ∼10% of treatment fractions, with limited dosimetric effect related to the infrequency of occurrence and longer fractionation of therapy. IFM can be monitored in continuous or discontinuous fashion with a variety of imaging platforms. Correction of IFM may have the greatest value when tighter PTV margins are desired (such as with stereotactic body radiation therapy or intraprostatic nodule boosting), ultrahypofractionated courses, or when treatment time exceeds several minutes. CONCLUSIONS This focused review summarizes literature and provides practical recommendations regarding IFM in the treatment of prostate cancer with external beam radiation therapy.
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Affiliation(s)
- Aoi Shimomura
- Department of Radiation and Cellular Oncology, University of Chicago Medicine, Chicago, Illinois
| | - Tianming Wu
- Department of Radiation and Cellular Oncology, University of Chicago Medicine, Chicago, Illinois
| | - Iris Rusu
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, Illinois
| | - Amar U Kishan
- Department of Radiation Oncology, University of California, Los Angeles, California
| | - Alison C Tree
- The Royal Marsden NHS Foundation Trust, Sutton, United Kingdom; Division of Radiotherapy and Imaging, Institute of Cancer Research, Sutton, United Kingdom
| | - Abhishek A Solanki
- Department of Radiation Oncology, Stritch School of Medicine, Cardinal Bernardin Cancer Center, Loyola University Chicago, Maywood, Illinois
| | - Stanley L Liauw
- Department of Radiation and Cellular Oncology, University of Chicago Medicine, Chicago, Illinois.
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di Franco F, Baudier T, Pialat PM, Munoz A, Martinon M, Pommier P, Sarrut D, Biston MC. Ultra-hypofractionated prostate cancer radiotherapy: Dosimetric impact of real-time intrafraction prostate motion and daily anatomical changes. Phys Med 2024; 118:103207. [PMID: 38215607 DOI: 10.1016/j.ejmp.2024.103207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 11/28/2023] [Accepted: 01/04/2024] [Indexed: 01/14/2024] Open
Abstract
PURPOSE To retrospectively assess the differences between planned and delivered dose during ultra-hypofractionated (UHF) prostate cancer treatments, by evaluating the dosimetric impact of daily anatomical variations alone, and in combination with prostate intrafraction motion. METHODS Prostate intrafraction motion was recorded with a transperineal ultrasound probe in 15 patients treated by UHF radiotherapy (36.25 Gy/5 fractions). The dosimetric objective was to cover 99 % of the clinical target volume with the 100 % prescription isodose line. After treatment, planning CT (pCT) images were deformably registered onto daily Cone Beam CT to generate pseudo-CT for dose accumulation (accumulated CT, aCT). The interplay effect was accounted by synchronizing prostatic shifts and beam geometry. Finally, the shifted dose maps were accumulated (moved-accumulated CT, maCT). RESULTS No significant change in daily CTV volumes was observed. Conversely, CTV V100% was 98.2 ± 0.8 % and 94.7 ± 2.6 % on aCT and maCT, respectively, compared with 99.5 ± 0.2 % on pCT (p < 0.0001). Bladder volume was smaller than planned in 76 % of fractions and D5cc was 33.8 ± 3.2 Gy and 34.4 ± 3.4 Gy on aCT (p = 0.02) and maCT (p = 0.01) compared with the pCT (36.0 ± 1.1 Gy). The rectum was smaller than planned in 50.3 % of fractions, but the dosimetric differences were not statistically significant, except for D1cc, found smaller on the maCT (33.2 ± 3.2 Gy, p = 0.02) compared with the pCT (35.3 ± 0.7 Gy). CONCLUSIONS Anatomical variations and prostate movements had more important dosimetric impact than anatomical variations alone, although, in some cases, the two phenomena compensated. Therefore, an efficient IGRT protocol is required for treatment implementation to reduce setup errors and control intrafraction motion.
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Affiliation(s)
- Francesca di Franco
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France; Univ. Grenoble Alpes, CNRS, Grenoble INP, LPSC UMR5821, 38000 Grenoble, France.
| | - Thomas Baudier
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | | | - Alexandre Munoz
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | | | - Pascal Pommier
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France
| | - David Sarrut
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
| | - Marie-Claude Biston
- Centre Léon Bérard, 28 rue Laennec 69373, LYON Cedex 08, France; CREATIS, CNRS UMR5220, Inserm U1044, INSA-Lyon, Université Lyon 1, Villeurbanne, France
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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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Arumugam S, Wong K, Do V, Sidhom M. Reducing the margin in prostate radiotherapy: optimizing radiotherapy with a general-purpose linear accelerator using an in-house position monitoring system. Front Oncol 2023; 13:1116999. [PMID: 37519807 PMCID: PMC10373585 DOI: 10.3389/fonc.2023.1116999] [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: 12/06/2022] [Accepted: 06/27/2023] [Indexed: 08/01/2023] Open
Abstract
Purpose To study the feasibility of optimizing the Clinical Target Volume to Planning Target Volume (CTV-PTV) margin in prostate radiotherapy(RT) with a general-purpose linear accelerator using an in-house developed position monitoring system, SeedTracker. Methods A cohort of 30 patients having definitive prostate radiotherapy treated within an ethics-approved prospective trial was considered for this study. The intrafraction prostate motion and the position deviations were measured using SeedTracker system during each treatment fraction. Using this data the CTV-PTV margin required to cover 90% of the patients with a minimum of 95% of the prescription dose to CTV was calculated using van Herk's formula. The margin calculations were performed for treatment scenarios both with and without applying the position corrections for observed position deviations. The feasibility of margin reduction with real-time monitoring was studied by assessing the delivered dose that incorporates the actual target position during treatment delivery and comparing it with the planned dose. This assessment was performed for plans generated with reduced CTV-PTV margin in the range of 7mm-3mm. Results With real-time monitoring and position corrections applied the margin of 2.0mm, 2.1mm and 2.1mm in LR, AP and SI directions were required to meet the criteria of 90% population to receive 95% of the dose prescription to CTV. Without position corrections applied for observed position deviations a margin of 3.1mm, 4.0mm and 3.0mm was required in LR, AP and SI directions to meet the same criteria. A mean ± SD reduction of 0.5 ± 1.8% and 3 ± 7% of V60 for the rectum and bladder can be achieved for every 1mm reduction of PTV margin. With position corrections applied, the CTV D99 can be delivered within -0.2 ± 0.3 Gy of the planned dose for plans with a 3mm margin. Without applying corrections for position deviations the CTV D99 was reduced by a maximum of 1.1 ± 1.1 Gy for the 3mm margin plan and there was a statistically significant difference between planned and delivered dose for 3mm and 4mm margin plans. Conclusion This study demonstrates the feasibility of reducing the margin in prostate radiotherapy with SeedTracker system without compromising the dose delivery accuracy to CTV while reducing dose to critical structures.
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Affiliation(s)
- Sankar Arumugam
- Department of Medical Physics, Liverpool and Macarthur Cancer Therapy Centres and Ingham Institute, Sydney, NSW, Australia
- South Western Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Karen Wong
- South Western Clinical School, University of New South Wales, Sydney, NSW, Australia
- Department of Radiation Oncology, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Viet Do
- South Western Clinical School, University of New South Wales, Sydney, NSW, Australia
- Department of Radiation Oncology, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
| | - Mark Sidhom
- South Western Clinical School, University of New South Wales, Sydney, NSW, Australia
- Department of Radiation Oncology, Liverpool and Macarthur Cancer Therapy Centres, Sydney, NSW, Australia
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Highlights from the 59th scientific congress of the French Society of Medical Physics. Phys Med 2022; 101:18-19. [PMID: 35853386 DOI: 10.1016/j.ejmp.2022.07.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/11/2022] [Indexed: 11/20/2022] Open
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