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Abdulameer MS, Pallathadka H, Menon SV, Rab SO, Hjazi A, Kaur M, Sivaprasad GV, Husseen B, Al-Mualm M, Banaei A. Dosimetric effect of collimator rotation on intensity modulated radiotherapy and volumetric modulated arc therapy for rectal cancer radiotherapy. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2024:XST240172. [PMID: 39093110 DOI: 10.3233/xst-240172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/04/2024]
Abstract
INTRODUCTION Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) are the main radiotherapy techniques for treating and managing rectal cancer. Collimator rotation is one of the crucial parameters in radiotherapy planning, and its alteration can cause dosimetric variations. This study assessed the effect of collimator rotation on the dosimetric results of various IMRT and VMAT plans for rectal cancer. MATERIALS AND METHODS Computed tomography (CT) images of 20 male patients with rectal cancer were utilized for IMRT and VMAT treatment planning with various collimator angles. Nine different IMRT techniques (5, 7, and 9 coplanar fields with collimator angles of 0°, 45°, and 90°) and six different VMAT techniques (1 and 2 full coplanar arcs with collimator angles of 0°, 45°, and 90°) were planned for each patient. The dosimetric results of various treatment techniques for target tissue (conformity index [CI] and homogeneity index [HI]) and organs at risk (OARs) sparing (parameters obtained from OARs dose-volume histograms [DVH]) as well as radiobiological findings were analyzed and compared. RESULTS The 7-fields IMRT technique demonstrated lower bladder doses (V40Gy, V45Gy), unaffected by collimator rotation. The 9-fields IMRT and 2-arcs VMAT (excluding the 90-degree collimator) had the lowest V35Gy and V45Gy. A 90-degree collimator rotation in 2-arcs VMAT significantly increased small bowel and bladder V45Gy, femoral head doses, and HI values. Radiobiologically, the 90-degree rotation had adverse effects on small bowel NTCP (normal tissue complication probability). No superiority was found for a 45-degree collimator rotation over 0 or 30 degrees in VMAT techniques. CONCLUSION Collimator rotation had minimal impact on dosimetric parameters in IMRT planning but is significant in VMAT techniques. A 90-degree rotation in VMAT, particularly in a 2-full arc technique, adversely affects PTV homogeneity index, bladder dose, and small bowel NTCP. Other evaluated collimator angles did not significantly affect VMAT dosimetrical or radiobiological outcomes.
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Affiliation(s)
| | | | - Soumya V Menon
- Department of Chemistry and Biochemistry, School of Sciences, JAIN (Deemed to be University), Bangalore, Karnataka, India
| | - Safia Obaidur Rab
- Department of Clinical Laboratory Sciences, College of Applied Medical Science, King Khalid University, Abha, Saudi Arabia
| | - Ahmed Hjazi
- Department of Medical Laboratory, College of Applied Medical Sciences, Prince Sattam bin Abdulaziz University, Al-Kharj, Saudi Arabia
| | - Mandeep Kaur
- Department of Sciences, Vivekananda Global University, Jaipur, Rajasthan, India
| | - G V Sivaprasad
- Department of Basic Science & Humanities, Raghu Engineering College, Visakhapatnam, India
| | - Beneen Husseen
- Medical Laboratory Technique College, the Islamic University, Najaf, Iraq
- Medical Laboratory Technique College, the Islamic University of Al Diwaniyah, Al Diwaniyah, Iraq
- Medical Laboratory Technique College, the Islamic University of Babylon, Babylon, Iraq
| | - Mahmood Al-Mualm
- Department of Medical Laboratories Technology, Al-Nisour University College, Nisour Seq. Karkh, Baghdad, Iraq
| | - Amin Banaei
- Department of Medical Physics, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran
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Chen ZJ, Li XA, Brenner DJ, Hellebust TP, Hoskin P, Joiner MC, Kirisits C, Nath R, Rivard MJ, Thomadsen BR, Zaider M. AAPM Task Group Report 267: A joint AAPM GEC-ESTRO report on biophysical models and tools for the planning and evaluation of brachytherapy. Med Phys 2024; 51:3850-3923. [PMID: 38721942 DOI: 10.1002/mp.17062] [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: 12/05/2023] [Revised: 02/28/2024] [Accepted: 03/08/2024] [Indexed: 06/05/2024] Open
Abstract
Brachytherapy utilizes a multitude of radioactive sources and treatment techniques that often exhibit widely different spatial and temporal dose delivery patterns. Biophysical models, capable of modeling the key interacting effects of dose delivery patterns with the underlying cellular processes of the irradiated tissues, can be a potentially useful tool for elucidating the radiobiological effects of complex brachytherapy dose delivery patterns and for comparing their relative clinical effectiveness. While the biophysical models have been used largely in research settings by experts, it has also been used increasingly by clinical medical physicists over the last two decades. A good understanding of the potentials and limitations of the biophysical models and their intended use is critically important in the widespread use of these models. To facilitate meaningful and consistent use of biophysical models in brachytherapy, Task Group 267 (TG-267) was formed jointly with the American Association of Physics in Medicine (AAPM) and The Groupe Européen de Curiethérapie and the European Society for Radiotherapy & Oncology (GEC-ESTRO) to review the existing biophysical models, model parameters, and their use in selected brachytherapy modalities and to develop practice guidelines for clinical medical physicists regarding the selection, use, and interpretation of biophysical models. The report provides an overview of the clinical background and the rationale for the development of biophysical models in radiation oncology and, particularly, in brachytherapy; a summary of the results of literature review of the existing biophysical models that have been used in brachytherapy; a focused discussion of the applications of relevant biophysical models for five selected brachytherapy modalities; and the task group recommendations on the use, reporting, and implementation of biophysical models for brachytherapy treatment planning and evaluation. The report concludes with discussions on the challenges and opportunities in using biophysical models for brachytherapy and with an outlook for future developments.
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Affiliation(s)
- Zhe Jay Chen
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - X Allen Li
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - David J Brenner
- Center for Radiological Research, Columbia University Medical Center, New York, New York, USA
| | - Taran P Hellebust
- Department of Oncology, The Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
| | - Peter Hoskin
- Mount Vernon Cancer Center, Mount Vernon Hospital, Northwood, UK
- University of Manchester, Manchester, UK
| | - Michael C Joiner
- Department of Radiation Oncology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Christian Kirisits
- Department of Radiation Oncology, Medical University of Vienna, Vienna, Austria
| | - Ravinder Nath
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Mark J Rivard
- Department of Radiation Oncology, Brown University School of Medicine, Providence, Rhode Island, USA
| | - Bruce R Thomadsen
- Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA
| | - Marco Zaider
- Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, New York, USA
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Yoshimura T, Nishioka K, Hashimoto T, Seki K, Kogame S, Tanaka S, Kanehira T, Tamura M, Takao S, Matsuura T, Kobashi K, Kato F, Aoyama H, Shimizu S. A treatment planning study of urethra-sparing intensity-modulated proton therapy for localized prostate cancer. Phys Imaging Radiat Oncol 2021; 20:23-29. [PMID: 34693040 PMCID: PMC8517200 DOI: 10.1016/j.phro.2021.09.006] [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: 06/04/2021] [Revised: 09/24/2021] [Accepted: 09/29/2021] [Indexed: 11/17/2022] Open
Abstract
US-IMPT can potentially reduce the risk of genitourinary toxicities. The urethral NTCP value in US-IMPT is significantly lower than in the clinical plan. TCP for CTV did not differ significantly between the clinical and US-IMPT plans.
Background and Purpose Urethra-sparing radiation therapy for localized prostate cancer can reduce the risk of radiation-induced genitourinary toxicity by intentionally underdosing the periurethral transitional zone. We aimed to compare the clinical impact of a urethra-sparing intensity-modulated proton therapy (US-IMPT) plan with that of conventional clinical plans without urethral dose reduction. Materials and Methods This study included 13 patients who had undergone proton beam therapy. The prescribed dose was 63 GyE in 21 fractions for 99% of the clinical target volume. To compare the clinical impact of the US-IMPT plan with that of the conventional clinical plan, tumor control probability (TCP) and normal tissue complication probability (NTCP) were calculated with a generalized equivalent uniform dose-based Lyman–Kutcher model using dose volume histograms. The endpoints of these model parameters for the rectum, bladder, and urethra were fistula, contraction, and urethral stricture, respectively. Results The mean NTCP value for the urethra in US-IMPT was significantly lower than that in the conventional clinical plan (0.6% vs. 1.2%, p < 0.05). There were no statistically significant differences between the conventional and US-IMPT plans regarding the mean minimum dose for the urethra with a 3-mm margin, TCP value, and NTCP value for the rectum and bladder. Additionally, the target dose coverage of all plans in the robustness analysis was within the clinically acceptable range. Conclusions Compared with the conventional clinically applied plans, US-IMPT plans have potential clinical advantages and may reduce the risk of genitourinary toxicities, while maintaining the same TCP and NTCP in the rectum and bladder.
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Affiliation(s)
- Takaaki Yoshimura
- Department of Health Sciences and Technology, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.,Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Kentaro Nishioka
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Takayuki Hashimoto
- Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Kazuya Seki
- Division of Radiological Science and Technology, Department of Health Sciences, School of Medicine, Hokkaido University, Sapporo, Japan
| | - Shouki Kogame
- Division of Radiological Science and Technology, Department of Health Sciences, School of Medicine, Hokkaido University, Sapporo, Japan
| | - Sodai Tanaka
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Faculty of Engineering, Hokkaido University, Sapporo, Japan
| | - Takahiro Kanehira
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Masaya Tamura
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Seishin Takao
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Faculty of Engineering, Hokkaido University, Sapporo, Japan
| | - Taeko Matsuura
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Faculty of Engineering, Hokkaido University, Sapporo, Japan
| | - Keiji Kobashi
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan
| | - Fumi Kato
- Department of Diagnostic and Interventional Radiology, Hokkaido University Hospital, Sapporo, Japan
| | - Hidefumi Aoyama
- Department of Radiation Oncology, Faculty of Medicine, Hokkaido University, Sapporo, Japan
| | - Shinichi Shimizu
- Department of Medical Physics, Hokkaido University Hospital, Sapporo, Japan.,Department of Radiation Medical Science and Engineering, Faculty of Medicine, Hokkaido University, Sapporo, Japan
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Out-of-field organ doses and associated risk of cancer development following radiation therapy with photons. Phys Med 2021; 90:73-82. [PMID: 34563834 DOI: 10.1016/j.ejmp.2021.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 09/06/2021] [Accepted: 09/13/2021] [Indexed: 11/21/2022] Open
Abstract
Innovations in cancer treatment have contributed to the improved survival rate of these patients. Radiotherapy is one of the main options for cancer management nowadays. High doses of ionizing radiation are usually delivered to the tumor site with high energy photon beams. However, the therapeutic radiation exposure may lead to second cancer induction. Moreover, the introduction of intensity-modulated radiation therapy over the last decades has increased the radiation dose to out-of-field organs compared to that from conventional irradiation. The increased organ doses might result in elevated probabilities for developing secondary malignancies to critical organs outside the treatment volume. The organ-specific dosimetry is considered necessary for the theoretical second cancer risk assessment and the proper analysis of data derived from epidemiological reports. This study reviews the methods employed for the measurement and calculation of out-of-field organ doses from exposure to photons and/or neutrons. The strengths and weaknesses of these dosimetric approaches are described in detail. This is followed by a review of the epidemiological data associated with out-of-field cancer risks. Previously published theoretical cancer risk estimates for adult and pediatric patients undergoing radiotherapy with conventional and advanced techniques are presented. The methodology for the theoretical prediction of the probability of carcinogenesis to out-of-field sites and the limitations of this approach are discussed. The article also focuses on the factors affecting the magnitude of the probability for developing radiotherapy-induced malignancies. The restriction of out-of-field doses and risks through the use of different types of shielding equipment is presented.
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Spohn SKB, Sachpazidis I, Wiehle R, Thomann B, Sigle A, Bronsert P, Ruf J, Benndorf M, Nicolay NH, Sprave T, Grosu AL, Baltas D, Zamboglou C. Influence of Urethra Sparing on Tumor Control Probability and Normal Tissue Complication Probability in Focal Dose Escalated Hypofractionated Radiotherapy: A Planning Study Based on Histopathology Reference. Front Oncol 2021; 11:652678. [PMID: 34055621 PMCID: PMC8160377 DOI: 10.3389/fonc.2021.652678] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/08/2021] [Indexed: 11/13/2022] Open
Abstract
Purpose Multiparametric magnetic resonance tomography (mpMRI) and prostate specific membrane antigen positron emission tomography (PSMA-PET/CT) are used to guide focal radiotherapy (RT) dose escalation concepts. Besides improvements of treatment effectiveness, maintenance of a good quality of life is essential. Therefore, this planning study investigates whether urethral sparing in moderately hypofractionated RT with focal RT dose escalation influences tumour control probability (TCP) and normal tissue complication probability (NTCP). Patients and Methods 10 patients with primary prostate cancer (PCa), who underwent 68Ga PSMA-PET/CT and mpMRI followed by radical prostatectomy were enrolled. Intraprostatic tumour volumes (gross tumor volume, GTV) based on both imaging techniques (GTV-MRI and -PET) were contoured manually using validated contouring techniques and GTV-Union was created by summing both. For each patient three IMRT plans were generated with 60 Gy to the whole prostate and a simultaneous integrated boost up to 70 Gy to GTV-Union in 20 fractions by (Plan 1) not respecting and (Plan 2) respecting dose constraints for urethra as well as (Plan 3) respecting dose constraints for planning organ at risk volume for urethra (PRV = urethra + 2mm expansion). NTCP for urethra was calculated applying a Lyman-Kutcher-Burman model. TCP-Histo was calculated based on PCa distribution in co-registered histology (GTV-Histo). Complication free tumour control probability (P+) was calculated. Furthermore, the intrafractional movement was considered. Results Median overlap of GTV-Union and PRV-Urethra was 1.6% (IQR 0-7%). Median minimum distance of GTV-Histo to urethra was 3.6 mm (IQR 2 - 7 mm) and of GTV-Union to urethra was 1.8 mm (IQR 0.0 - 5.0 mm). The respective prescription doses and dose constraints were reached in all plans. Urethra-sparing in Plans 2 and 3 reached significantly lower NTCP-Urethra (p = 0.002) without significantly affecting TCP-GTV-Histo (p = p > 0.28), NTCP-Bladder (p > 0.85) or NTCP-Rectum (p = 0.85), resulting in better P+ (p = 0.006). Simulation of intrafractional movement yielded even higher P+ values for Plans 2 and 3 compared to Plan 1. Conclusion Urethral sparing may increase the therapeutic ratio and should be implemented in focal RT dose escalation concepts.
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Affiliation(s)
- Simon K B Spohn
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany.,Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ilias Sachpazidis
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Rolf Wiehle
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Benedikt Thomann
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - August Sigle
- Department of Urology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Peter Bronsert
- Institute for Surgical Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Juri Ruf
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Matthias Benndorf
- Department of Radiology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Nils H Nicolay
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany
| | - Tanja Sprave
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany
| | - Anca L Grosu
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany
| | - Dimos Baltas
- German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany.,Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Constantinos Zamboglou
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK). Partner Site Freiburg, Freiburg, Germany.,Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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Kuperman VY, Lubich LM. Effect of reoxygenation on hypofractionated radiotherapy of prostate cancer. Med Phys 2020; 47:5383-5391. [DOI: 10.1002/mp.14343] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 06/05/2020] [Accepted: 06/09/2020] [Indexed: 11/07/2022] Open
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Panettieri V, Rancati T, Onjukka E, Ebert MA, Joseph DJ, Denham JW, Steigler A, Millar JL. External Validation of a Predictive Model of Urethral Strictures for Prostate Patients Treated With HDR Brachytherapy Boost. Front Oncol 2020; 10:910. [PMID: 32596153 PMCID: PMC7300245 DOI: 10.3389/fonc.2020.00910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 05/11/2020] [Indexed: 12/12/2022] Open
Abstract
Purpose: For prostate cancer treatment, comparable or superior biochemical control was reported when using External-Beam-Radiotherapy (EBRT) with High-Dose-Rate-Brachytherapy (HDRB)-boost, compared to dose-escalation with EBRT alone. The conformal doses produced by HDRB could allow further beneficial prostate dose-escalation, but increase in dose is limited by normal tissue toxicity. Previous works showed correlation between urethral dose and incidence of urinary toxicity, but there is a lack of established guidelines on the dose constraints to this organ. This work aimed at fitting a Normal-Tissue-Complication-Probability model to urethral stricture data collected at one institution and validating it with an external cohort, looking at neo-adjuvant androgen deprivation as dose-modifying factor. Materials and Methods: Clinical and dosimetric data of 258 patients, with a toxicity rate of 12.8%, treated at a single institution with a variety of prescription doses, were collected to fit the Lyman–Kutcher–Burman (LKB) model using the maximum likelihood method. Due to the different fractionations, doses were converted into 2 Gy-equivalent doses (α/β = 5 Gy), and urethral stricture was used as an end-point. For validation, an external cohort of 187 patients treated as part of the TROG (Trans Tasman Radiation Oncology Group) 03.04 RADAR trial with a toxicity rate of 8.7%, was used. The goodness of fit was assessed using calibration plots. The effect of neo-adjuvant androgen deprivation (AD) was analyzed separating patients who had received it prior to treatment from those who did not receive it. Results: The obtained LKB parameters were TD50 = 116.7 Gy and m = 0.23; n was fixed to 0.3, based on numerical optimization of the likelihood. The calibration plot showed a good agreement between the observed toxicity and the probability predicted by the model, confirmed by bootstrapping. For the external validation, the calibration plot showed that the observed toxicity obtained with the RADAR patients was well-represented by the fitted LKB model parameters. When patients were stratified by the use of AD TD50 decreased when AD was not present. Conclusions: Lyman–Kutcher–Burman model parameters were fitted to the risk of urethral stricture and externally validated with an independent cohort, to provide guidance on urethral tolerance doses for patients treated with a HDRB boost. For patients that did not receive AD, model fitting provided a lower TD50 suggesting a protective effect on urethra toxicity.
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Affiliation(s)
- Vanessa Panettieri
- Alfred Health Radiation Oncology, Alfred Hospital, Melbourne, VIC, Australia.,Medical Imaging and Radiation Sciences, Monash University, Clayton, VIC, Australia
| | - Tiziana Rancati
- Prostate Cancer Program, Scientific Directorate, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy
| | - Eva Onjukka
- Medical Radiation Physics and Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - Martin A Ebert
- Radiation Oncology, Sir Charles Gairdner Hospital, Perth, WA, Australia.,School of Physics, Mathematics and Computing, University of Western Australia, Perth, WA, Australia.,5D Clinics, Claremont, WA, Australia
| | - David J Joseph
- 5D Clinics, Claremont, WA, Australia.,GenesisCare, Subiaco, WA, Australia.,School of Surgery, University of Western Australia, WA, Australia
| | - James W Denham
- School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia
| | - Allison Steigler
- School of Medicine and Public Health, University of Newcastle, Newcastle, NSW, Australia
| | - Jeremy L Millar
- Alfred Health Radiation Oncology, Alfred Hospital, Melbourne, VIC, Australia.,Central Clinical School, Monash University, Melbourne, VIC, Australia
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Splinter M, Bostel T, Sachpazidis I, Fechter T, Zamboglou C, Jäkel O, Huber PE, Debus J, Baltas D, Nicolay NH. Dosimetric Impact of Interfractional Variations for Post-prostatectomy Radiotherapy to the Prostatic Fossa-Relevance for the Frequency of Position Verification Imaging and Treatment Adaptation. Front Oncol 2019; 9:1191. [PMID: 31788450 PMCID: PMC6856079 DOI: 10.3389/fonc.2019.01191] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 10/21/2019] [Indexed: 12/15/2022] Open
Abstract
Background and purpose: To analyze divergences between the planned and applied treatment doses for post-prostatectomy radiotherapy to the prostatic fossa on a voxel-by-voxel basis based on interfractional anatomic variations and imaging frequency. Materials and methods: For 10 patients receiving intensity-modulated postoperative radiotherapy to the prostatic fossa, position verification was carried out by daily in-room CT imaging in treatment position (340 fraction CTs). Applied fraction doses were recalculated on daily CT scans, and treatment doses were accumulated on a voxel-by-voxel basis after deformable image registration. To simulate weekly imaging, derived weekly position correction vectors were used to rigidly register all daily scans of the respective treatment week onto the planning CT before dose accumulation. Detailed dose statistics of the prescribed and applied treatment doses were compared in relation to the frequency of position verification imaging. Derived NTCP and Pinjury values were calculated for the rectum and bladder. Results: Despite a large variability in the pelvic anatomy, daily CT-based patient repositioning resulted in largely negligible deviations of the analyzed dose-volume, conformity, and uniformity parameters from the planned doses for post-prostatectomy radiotherapy, and only the bladder exhibited significant increases in the accumulated mean and median doses. Derived NTCP for the applied doses to the rectum and bladder and Pinjury values did not significantly deviate from the treatment plan. In contrast, weekly CT-based repositioning resulted in significant decreases of the PTV coverage and dose conformity as well as large deviations of the applied doses to the rectum and bladder from the planned doses. Consecutively, NTCP for the rectum and Pinjury were found falsely reduced for weekly patient repositioning. Conclusions: Our data indicate for the first time in a voxel-by-voxel analysis that daily imaging is required for reliable adaptive delivery of intensity-modulated radiotherapy to the prostatic fossa. This work will help guiding adaptive treatment strategies for post-prostatectomy radiotherapy.
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Affiliation(s)
- Mona Splinter
- Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Clinical Cooperation Unit "Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Tilman Bostel
- Clinical Cooperation Unit "Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.,Department of Radiation Oncology, University Medical Center Mainz, Mainz, Germany
| | - Ilias Sachpazidis
- Department of Radiation Oncology, Medical Center - University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Tobias Fechter
- Department of Radiation Oncology, Medical Center - University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Constantinos Zamboglou
- Department of Radiation Oncology, Medical Center - University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Oliver Jäkel
- Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany
| | - Peter E Huber
- Clinical Cooperation Unit "Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Jürgen Debus
- Clinical Cooperation Unit "Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology (HIRO), National Center for Radiation Research in Oncology (NCRO), Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany
| | - Dimos Baltas
- Department of Radiation Oncology, Medical Center - University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Nils H Nicolay
- Clinical Cooperation Unit "Radiation Oncology, German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.,Department of Radiation Oncology, Medical Center - University of Freiburg, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
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9
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Bostel T, Sachpazidis I, Splinter M, Bougatf N, Fechter T, Zamboglou C, Jäkel O, Huber PE, Baltas D, Debus J, Nicolay NH. Dosimetric Impact of Interfractional Variations in Prostate Cancer Radiotherapy-Implications for Imaging Frequency and Treatment Adaptation. Front Oncol 2019; 9:940. [PMID: 31612106 PMCID: PMC6776888 DOI: 10.3389/fonc.2019.00940] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/06/2019] [Indexed: 02/06/2023] Open
Abstract
Background and purpose: To analyze deviations of the applied from the planned doses on a voxel-by-voxel basis for definitive prostate cancer radiotherapy depending on anatomic variations and imaging frequency. Materials and methods: Daily in-room CT imaging was performed in treatment position for 10 patients with prostate cancer undergoing intensity-modulated radiotherapy (340 fraction CTs). Applied fraction doses were recalculated on daily images, and voxel-wise dose accumulation was performed using a deformable registration algorithm. For weekly imaging, weekly position correction vectors were derived and used to rigidly register daily scans of that week to the planning CT scan prior to dose accumulation. Applied and prescribed doses were compared in dependence of the imaging frequency, and derived TCP and NTCP values were calculated. Results: Daily CT-based repositioning resulted in non-significant deviations of all analyzed dose-volume, conformity and uniformity parameters to the CTV, bladder and rectum irrespective of anatomic changes. Derived average TCP values were comparable, and NTCP values for the applied doses to the bladder and rectum did not significantly deviate from the planned values. For weekly imaging, the applied D2 to the CTV, rectum and bladder significantly varied from the planned doses, and the CTV conformity index and D98 decreased. While TCP values were comparable, the NTCP for the bladder erroneously appeared reduced for weekly repositioning. Conclusions: Based on daily diagnostic quality CT imaging and voxel-wise dose accumulation, we demonstrated for the first time that daily, but not weekly imaging resulted in only negligible deviations of the applied from the planned doses for prostate intensity-modulated radiotherapy. Therefore, weekly imaging may not be adequately reliable for adaptive treatment delivery techniques for prostate. This work will contribute to devising adaptive re-planning strategies for prostate radiotherapy.
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Affiliation(s)
- Tilman Bostel
- Clinical Cooperation Unit "Radiation Oncology", German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.,Department of Radiation Oncology, University Medical Center Mainz, Mainz, Germany
| | - Ilias Sachpazidis
- Department of Radiation Oncology, University of Freiburg Medical Center, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Mona Splinter
- Heidelberg Institute of Radiation Oncology, National Center for Radiation Research in Oncology, Heidelberg, Germany.,Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg, Germany
| | - Nina Bougatf
- Clinical Cooperation Unit "Radiation Oncology", German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology, National Center for Radiation Research in Oncology, Heidelberg, Germany
| | - Tobias Fechter
- Department of Radiation Oncology, University of Freiburg Medical Center, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Constantinos Zamboglou
- Department of Radiation Oncology, University of Freiburg Medical Center, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Oliver Jäkel
- Heidelberg Institute of Radiation Oncology, National Center for Radiation Research in Oncology, Heidelberg, Germany.,Medical Physics in Radiation Oncology, German Cancer Research Center, Heidelberg, Germany
| | - Peter E Huber
- Clinical Cooperation Unit "Radiation Oncology", German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology, National Center for Radiation Research in Oncology, Heidelberg, Germany
| | - Dimos Baltas
- Department of Radiation Oncology, University of Freiburg Medical Center, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
| | - Jürgen Debus
- Clinical Cooperation Unit "Radiation Oncology", German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany.,Heidelberg Institute of Radiation Oncology, National Center for Radiation Research in Oncology, Heidelberg, Germany
| | - Nils H Nicolay
- Clinical Cooperation Unit "Radiation Oncology", German Cancer Research Center, Heidelberg, Germany.,Department of Radiation Oncology, University of Freiburg Medical Center, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, German Cancer Research Center, Heidelberg, Germany
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10
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Utsunomiya S, Yamamoto J, Tanabe S, Oishi M, Satsuma A, Kaidu M, Abe E, Ohta A, Kushima N, Aoyama H. Complementary Relation Between the Improvement of Dose Delivery Technique and PTV Margin Reduction in Dose-Escalated Radiation Therapy for Prostate Cancer. Pract Radiat Oncol 2019; 9:172-178. [PMID: 30772440 DOI: 10.1016/j.prro.2019.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/07/2019] [Accepted: 02/06/2019] [Indexed: 02/07/2023]
Abstract
PURPOSE The purpose of this study is to demonstrate quantitatively the complementary relationship between the introduction of intensity modulated radiation therapy (IMRT) and planning target volume (PTV) margin reduction with an image guided technique in reducing the risk of rectal toxicity in dose-escalating prostate radiation therapy. METHODS AND MATERIALS Three-dimensional conformal radiation therapy (CRT) and IMRT plans were generated for 10 patients with prostate cancer based on 2 PTV margin protocols (10/8 mm and 6/5 mm) and 2 dose prescriptions (70 Gy and 78 Gy). The normal tissue complication probability (NTCP) for each of the 8 scenarios was calculated using the Lyman-Kutcher-Burman model to estimate the risk of rectal and bladder late toxicity. The conformity and homogeneity indices of PTVs were calculated for each plan. RESULTS The IMRT plans showed superiority in conformity and inferiority in homogeneity over 3-dimensional CRT plans. The rectal NTCPs were increased 3.5 to 4.1 times when the prescribed total dose was changed from 70 Gy to 78 Gy and the dose delivery and the image guided radiation therapy techniques remained unchanged. PTV margin reduction was shown to reduce the value of rectal NTCP significantly. Overall, implementing the IMRT technique alone could reduce the NTCP values only by 2.1% to 7.3% from those of 3-dimensional CRT. The introduction of both IMRT and PTV margin reduction was found to be necessary for rectal NTCP to remain <5% in the dose escalation from 70 to 78 Gy. CONCLUSIONS The complementary relationship between the introduction of IMRT and PTV margin reduction was proven. We found that both approaches need to be implemented to safely deliver a curative dose in dose-escalating prostate radiation therapy.
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Affiliation(s)
- Satoru Utsunomiya
- Department of Radiological Technology, Niigata University Graduate School of Health Sciences, Niigata, Japan.
| | - Jun Yamamoto
- School of Medicine, Faculty of Medicine, Niigata University, Niigata, Japan
| | - Satoshi Tanabe
- Department of Radiation Oncology, Niigata University Medical and Dental Hospital, Niigata, Japan
| | - Mayu Oishi
- School of Medicine, Faculty of Medicine, Niigata University, Niigata, Japan
| | - Aruha Satsuma
- School of Medicine, Faculty of Medicine, Niigata University, Niigata, Japan
| | - Motoki Kaidu
- Department of Radiation Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Eisuke Abe
- Department of Radiation Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Atsushi Ohta
- Department of Radiation Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | | | - Hidefumi Aoyama
- Department of Radiation Oncology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
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11
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Zamboglou C, Thomann B, Koubar K, Bronsert P, Krauss T, Rischke HC, Sachpazidis I, Drendel V, Salman N, Reichel K, Jilg CA, Werner M, Meyer PT, Bock M, Baltas D, Grosu AL. Focal dose escalation for prostate cancer using 68Ga-HBED-CC PSMA PET/CT and MRI: a planning study based on histology reference. Radiat Oncol 2018; 13:81. [PMID: 29716617 PMCID: PMC5930745 DOI: 10.1186/s13014-018-1036-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/26/2018] [Indexed: 01/20/2023] Open
Abstract
Background Focal radiation therapy has gained of interest in treatment of patients with primary prostate cancer (PCa). The question of how to define the intraprostatic boost volume is still open. Previous studies showed that multiparametric MRI (mpMRI) or PSMA PET alone could be used for boost volume definition. However, other studies proposed that the combined usage of both has the highest sensitivity in detection of intraprostatic lesions. The aim of this study was to demonstrate the feasibility and to evaluate the tumour control probability (TCP) and normal tissue complication probability (NTCP) of radiation therapy dose painting using 68Ga-HBED-CC PSMA PET/CT, mpMRI or the combination of both in primary PCa. Methods Ten patients underwent PSMA PET/CT and mpMRI followed by prostatectomy. Three gross tumour volumes (GTVs) were created based on PET (GTV-PET), mpMRI (GTV-MRI) and the union of both (GTV-union). Two plans were generated for each GTV. Plan95 consisted of whole-prostate IMRT to 77 Gy in 35 fractions and a simultaneous boost to 95 Gy (Plan95PET/Plan95MRI/Plan95union). Plan80 consisted of whole-prostate IMRT to 76 Gy in 38 fractions and a simultaneous boost to 80 Gy (Plan80PET/Plan80MRI/Plan80union). TCPs were calculated for GTV-histo (TCP-histo), which was delineated based on PCa distribution in co-registered histology slices. NTCPs were assessed for bladder and rectum. Results Dose constraints of published protocols were reached in every treatment plan. Mean TCP-histo were 99.7% (range: 97%–100%) and 75.5% (range: 33%–95%) for Plan95union and Plan80union, respectively. Plan95union had significantly higher TCP-histo values than Plan95MRI (p = 0.008) and Plan95PET (p = 0.008). Plan80union had significantly higher TCP-histo values than Plan80MRI (p = 0.012), but not than Plan80PET (p = 0.472). Plan95MRI had significantly lower NTCP-rectum than Plan95union (p = 0.012). No significant differences in NTCP-rectum and NTCP-bladder were observed for all other plans (p > 0.05). Conclusions IMRT dose escalation on GTVs based on mpMRI, PSMA PET/CT and the combination of both was feasible. Boosting GTV-union resulted in significantly higher TCP-histo with no or minimal increase of NTCPs compared to the other plans. Electronic supplementary material The online version of this article (10.1186/s13014-018-1036-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Constantinos Zamboglou
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Robert-Koch Straße 3, 79106, Freiburg, Germany. .,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany. .,Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Benedikt Thomann
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Khodor Koubar
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Peter Bronsert
- Department of Pathology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Tobias Krauss
- Department of Radiology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Hans C Rischke
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Robert-Koch Straße 3, 79106, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Ilias Sachpazidis
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Vanessa Drendel
- Department of Pathology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Nasr Salman
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Robert-Koch Straße 3, 79106, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Kathrin Reichel
- Department of Urology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Cordula A Jilg
- Department of Urology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Martin Werner
- Department of Pathology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Philipp T Meyer
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Michael Bock
- Division of Medical Physics, Department of Radiology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Dimos Baltas
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
| | - Anca L Grosu
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, Robert-Koch Straße 3, 79106, Freiburg, Germany.,German Cancer Consortium (DKTK), Partner Site Freiburg, Freiburg, Germany
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12
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Han J, Zhu W, Yu C, Zhou X, Li T, Zhang X. Clinical Study of Concurrent Chemoradiotherapy or Radiotherapy Alone for Esophageal Cancer Patients with Positive Lymph Node Metastasis. TUMORI JOURNAL 2018; 98:60-5. [DOI: 10.1177/030089161209800108] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Aims and Background Esophageal cancer patients with pathologic lymph node involvement generally have a poor prognosis. Many randomized controlled trials have not achieved consistent results similar to those of the RTOG8501 trial, and the long-term survival rate has not increased. The present study aimed to compare the efficacy and toxic side effects of concurrent chemoradiotherapy and radiotherapy alone to treat N1 esophageal carcinoma. Methods and Study Design A total of 130 N1 esophageal carcinoma patients were enrolled and randomly divided into two groups: concurrent chemoradiotherapy group (n = 65) and radiotherapy group (n = 65). Both groups received three-dimensional conformal radiotherapy with a total dose of 64–66 Gy. Meanwhile, to the concurrent chemoradiotherapy group, an additional chemotherapy protocol (nedaplatin, 20 mg/m2/d, 5-FU, 500 mg/m2/d for four days) was given from day 1, and such treatment was repeated until day 29. From day 21 after radiotherapy, two cycles of a consolidated chemotherapy protocol were given at an interval of 28 days. Results The survival rates at one, two, and three years were 72.3%, 55.3%, and 40% in the concurrent chemoradiotherapy group, respectively, and 75.3%, 38.5%, and 18.5% in the radiotheray group (P = 0.007), respectively. The survival rates of the patients in the concurrent chemoradiotherapy group who completed one to two cycles and three to four cycles at one, two, and three years were 70%, 53.3%, and 30%, and 74.2%, 57.1%, 48.6% (P = 0.128), respectively. Three-year distant metastasis rates were 10.7% in the concurrent chemoradiotherapy group and 16.9% in the radiotherapy group. Acute toxicity in the concurrent chemoradiotherapy group was higher than in the radiotherapy group. Late toxic side effects were similar in the two groups. Conclusions Compared with radiotherapy alone, concurrent chemoradiotherapy in the treatment of esophageal carcinoma with local lymph node enlargement can improve the three-year survival rate. Moreover, completion of three to four cycles of chemotherapy may have better efficacy than one to two cycles.
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Affiliation(s)
- Jihua Han
- Department of Radiation Oncology, First Hospital of Huaian, Nanjing Medical University, Huaian, China
| | - Weiguo Zhu
- Department of Radiation Oncology, First Hospital of Huaian, Nanjing Medical University, Huaian, China
| | - Changhua Yu
- Department of Radiation Oncology, First Hospital of Huaian, Nanjing Medical University, Huaian, China
| | - Xilei Zhou
- Department of Radiation Oncology, First Hospital of Huaian, Nanjing Medical University, Huaian, China
| | - Tao Li
- Department of Radiation Oncology, First Hospital of Huaian, Nanjing Medical University, Huaian, China
| | - Xiaoye Zhang
- Department of Radiation Oncology, First Hospital of Huaian, Nanjing Medical University, Huaian, China
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13
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Zamboglou C, Sachpazidis I, Koubar K, Drendel V, Wiehle R, Kirste S, Mix M, Schiller F, Mavroidis P, Meyer PT, Werner M, Grosu AL, Baltas D. Evaluation of intensity modulated radiation therapy dose painting for localized prostate cancer using 68Ga-HBED-CC PSMA-PET/CT: A planning study based on histopathology reference. Radiother Oncol 2017; 123:472-477. [PMID: 28499607 DOI: 10.1016/j.radonc.2017.04.021] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 04/06/2017] [Accepted: 04/22/2017] [Indexed: 12/25/2022]
Abstract
PURPOSE To demonstrate the feasibility and to evaluate the tumour control probability (TCP) and normal tissue complication probability (NTCP) of IMRT dose painting using 68Ga-HBED-CC PSMA PET/CT for target delineation in prostate cancer (PCa). METHODS AND MATERIALS 10 patients had PSMA PET/CT scans prior to prostatectomy. GTV-PET was generated on the basis of an intraprostatic SUVmax of 30%. Two IMRT plans were generated for each patient: Plan77 which consisted of whole-prostate IMRT to 77Gy, and Plan95 which consisted of whole-prostate IMRT to 77Gy and a simultaneous integrated boost to the GTV-PET up to 95Gy (35 fractions). The feasibility of these plans was judged by their ability to adhere to the FLAME trial protocol. TCP-histo/-PET were calculated on co-registered histology (GTV-histo) and GTV-PET, respectively. NTCPs for rectum and bladder were calculated. RESULTS All plans reached prescription doses whilst adhering to dose constraints. In Plan77 and Plan95 mean doses in GTV-histo were 75.8±0.3Gy and 96.9±1Gy, respectively. Average TCP-histo values for Plan77 and Plan95 were 70% (range: 15-97%), and 96% (range: 78-100%, p<0.0001). Average TCP-PET values for Plan77 and Plan95 were 55% (range: 27-82%), and 100% (range: 99-100%, p<0.0001). There was no significant difference between TCP-PET and TCP-histo in Plan95 (p=0.25). There were no significant differences in rectal (p=0.563) and bladder (p=0.3) NTCPs. CONCLUSIONS IMRT dose painting using PSMA PET/CT was technically feasible and resulted in significantly higher TCPs without higher NTCPs.
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Affiliation(s)
- Constantinos Zamboglou
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany.
| | - Ilias Sachpazidis
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Khodor Koubar
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Vanessa Drendel
- Department of Pathology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Rolf Wiehle
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Simon Kirste
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Michael Mix
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Florian Schiller
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Panayiotis Mavroidis
- Department of Radiation Oncology, University of North Carolina, Chapel Hill, USA
| | - Philipp T Meyer
- Department of Nuclear Medicine, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Martin Werner
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Anca L Grosu
- Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
| | - Dimos Baltas
- Division of Medical Physics, Department of Radiation Oncology, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Germany; German Cancer Consortium (DKTK), Partner Site Freiburg, Germany
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14
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Buge F, Chiavassa S, Hervé C, Rigaud J, Delpon G, Supiot S. Preclinical Evaluation of Intraoperative Low-Energy Photon Radiotherapy Using Spherical Applicators in Locally Advanced Prostate Cancer. Front Oncol 2015; 5:204. [PMID: 26442216 PMCID: PMC4569969 DOI: 10.3389/fonc.2015.00204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 09/01/2015] [Indexed: 11/13/2022] Open
Abstract
Background Surgery plus adjuvant radiotherapy is standard care for locally advanced prostate cancer (stage pT3R1). Intraoperative low-energy photon radiotherapy offers several advantages over external beam radiotherapy, and several systems are now available for its delivery, using spherical applicators, which require only limited shielding. The aim of this study was to evaluate the feasibility of this technique for the prostate bed. Materials and methods Applicators were assessed using MRI image data and cadaveric dissection. In cadavers, targeted tissues, defined as a urethral section, both neurovascular bundle sections, the bladder neck and the beds of the seminal vesicles, were marked with metallic surgical clips. Distances between clips and applicator were measured using CT. A dosimetric study of the application of 12 Gy at 5 mm depth was performed using CT images of prostatectomized cadavers. Results Using MRI images from 34 prostate cancer patients, we showed that the ideal applicator diameter ranges from 45 to 70 mm. Using applicators of different sizes to encompass the prostate bed in nine cadavers, we showed that the distance between target tissues and applicator was <2 mm for all target tissues except the upper extremity of the seminal vesicles (19 mm). Dosimetric study showed a good dose distribution in all target tissues in contact with the applicator, with a low probability of rectum and bladder complication. Conclusion Intraoperative radiotherapy of the prostate bed is feasible, with good coverage of targeted tissues. Clinical study of safety and efficacy is now required.
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Affiliation(s)
- François Buge
- Department of Urology, Centre Hospitalier Universitaire de Nantes , Nantes , France
| | - Sophie Chiavassa
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France ; Department of Medical Physics, Institut de Cancérologie de l'Ouest , St-Herblain , France
| | - Chloé Hervé
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France
| | - Jérôme Rigaud
- Department of Urology, Centre Hospitalier Universitaire de Nantes , Nantes , France
| | - Grégory Delpon
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France ; Department of Medical Physics, Institut de Cancérologie de l'Ouest , St-Herblain , France
| | - Stéphane Supiot
- Centre de Recherche en Cancérologie Nantes-Angers, INSERM U892, Université de Nantes , Nantes , France ; Department of Radiation Oncology, Institut de Cancérologie de l'Ouest , St-Herblain , France
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15
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Jameson MG, Ohanessian L, Batumalai V, Patel V, Holloway LC. Comparison of Oncentra® Brachy IPSA and graphical optimisation techniques: a case study of HDR brachytherapy head and neck and prostate plans. J Med Radiat Sci 2015; 62:168-74. [PMID: 26229683 PMCID: PMC4462990 DOI: 10.1002/jmrs.107] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 04/08/2015] [Accepted: 04/08/2015] [Indexed: 11/15/2022] Open
Abstract
There are a number of different dwell positions and time optimisation options available in the Oncentra® Brachy (Elekta Brachytherapy Solutions, Veenendaal, The Netherlands) brachytherapy treatment planning system. The purpose of this case study was to compare graphical (GRO) and inverse planning by simulated annealing (IPSA) optimisation techniques for interstitial head and neck (HN) and prostate plans considering dosimetry, modelled radiobiology outcome and planning time. Four retrospective brachytherapy patients were chosen for this study, two recurrent HN and two prostatic boosts. Manual GRO and IPSA plans were generated for each patient. Plans were compared using dose–volume histograms (DVH) and dose coverage metrics including; conformity index (CI), homogeneity index (HI) and conformity number (CN). Logit and relative seriality models were used to calculate tumour control probability (TCP) and normal tissue complication probability (NTCP). Approximate planning time was also recorded. There was no significant difference between GRO and IPSA in terms of dose metrics with mean CI of 1.30 and 1.57 (P > 0.05) respectively. IPSA achieved an average HN TCP of 0.32 versus 0.12 for GRO while for prostate there was no significant difference. Mean GRO planning times were greater than 75 min while average IPSA planning times were less than 10 min. Planning times for IPSA were greatly reduced compared to GRO and plans were dosimetrically similar. For this reason, IPSA makes for a useful planning tool in HN and prostate brachytherapy.
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Affiliation(s)
- Michael G Jameson
- Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia ; Centre for Medical Radiation Physics, University of Wollongong Wollongong, New South Wales, Australia ; Ingham Institute of Applied Medical Research Liverpool, New South Wales, Australia
| | - Lucy Ohanessian
- Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia
| | - Vikneswary Batumalai
- Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia ; Ingham Institute of Applied Medical Research Liverpool, New South Wales, Australia ; South Western Sydney Clinical School, School of Medicine University of New South Wales, Australia
| | - Virendra Patel
- Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia
| | - Lois C Holloway
- Liverpool and Macarthur Cancer Therapy Centres Liverpool, New South Wales, Australia ; Centre for Medical Radiation Physics, University of Wollongong Wollongong, New South Wales, Australia ; Ingham Institute of Applied Medical Research Liverpool, New South Wales, Australia ; South Western Sydney Clinical School, School of Medicine University of New South Wales, Australia ; Institute of Medical Physics, School of Physics, University of Sydney Sydney, New South Wales, Australia
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16
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Mavroidis P, Ferreira BC, Papanikolaou N, Lopes MDC. Analysis of fractionation correction methodologies for multiple phase treatment plans in radiation therapy. Med Phys 2013; 40:031715. [PMID: 23464310 DOI: 10.1118/1.4792636] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Radiation therapy is often delivered by multiple sequential treatment plans. For an accurate radiobiological evaluation of the overall treatment, fractionation corrections to each dose distribution must be applied before summing the three-dimensional dose matrix of each plan since the simpler approach of performing the fractionation correction to the total dose-volume histograms, obtained by the arithmetical sum of the different plans, becomes inaccurate for more heterogeneous dose patterns. In this study, the differences between these two fractionation correction methods, named here as exact (corrected before) and approximate (after summation), respectively, are assessed for different cancer types. METHODS Prostate, breast, and head and neck (HN) tumor patients were selected to quantify the differences between two fractionation correction methods (the exact vs the approximate). For each cancer type, two different treatment plans were developed using uniform (CRT) and intensity modulated beams (IMRT), respectively. The responses of the target and normal tissue were calculated using the Poisson linear-quadratic-time model and the relative seriality model, respectively. All treatments were radiobiologically evaluated and compared using the complication-free tumor control probability (P+), the biologically effective uniform dose (D) together with common dosimetric criteria. RESULTS For the prostate cancer patient, an underestimation of around 14%-15% in P+ was obtained when the fractionation correction was applied after summation compared to the exact approach due to significant biological and dosimetric variations obtained between the two fractionation correction methods in the involved lymph nodes. For the breast cancer patient, an underestimation of around 3%-4% in the maximum dose in the heart was obtained. Despite the dosimetric differences in this organ, no significant variations were obtained in treatment outcome. For the HN tumor patient, an underestimation of about 5% in treatment outcome was obtained for the CRT plan as a result of an underestimation of the planning target volume control probability by about 10%. An underestimation of about 6% in the complication probability of the right parotid was also obtained. For all the other organs at risk, dosimetric differences of up to 4% were obtained but with no significant impact in the expected clinical outcome. However, for the IMRT plan, an overestimation in P+ of 4.3% was obtained mainly due to an underestimation of the complication probability of the left and right parotids (2.9% and 5.8%, respectively). CONCLUSIONS The use of the exact fractionation correction method, which is applying fractionation correction on the separate dose distributions of a multiple phase treatment before their summation was found to have a significant expected clinical impact. For regions of interest that are irradiated with very heterogeneous dose distributions and significantly different doses per fraction in the different treatment phases, the exact fractionation correction method needs to be applied since a significant underestimation of the true patient outcome can be introduced otherwise.
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Affiliation(s)
- Panayiotis Mavroidis
- Department of Radiation Oncology, University of Texas Health Sciences Center, San Antonio, Texas 78229, USA.
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Shiraishi Y, Hanada T, Ohashi T, Yorozu A, Toya K, Saito S, Shigematsu N. Novel parameter predicting grade 2 rectal bleeding after iodine-125 prostate brachytherapy combined with external beam radiation therapy. Int J Radiat Oncol Biol Phys 2013; 87:182-7. [PMID: 23747214 DOI: 10.1016/j.ijrobp.2013.04.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 04/19/2013] [Accepted: 04/22/2013] [Indexed: 11/16/2022]
Abstract
PURPOSE To propose a novel parameter predicting rectal bleeding on the basis of generalized equivalent uniform doses (gEUD) after (125)I prostate brachytherapy combined with external beam radiation therapy and to assess the predictive value of this parameter. METHODS AND MATERIALS To account for differences among radiation treatment modalities and fractionation schedules, rectal dose-volume histograms (DVHs) of 369 patients with localized prostate cancer undergoing combined therapy retrieved from corresponding treatment planning systems were converted to equivalent dose-based DVHs. The gEUDs for the rectum were calculated from these converted DVHs. The total gEUD (gEUDsum) was determined by a summation of the brachytherapy and external-beam radiation therapy components. RESULTS Thirty-eight patients (10.3%) developed grade 2+ rectal bleeding. The grade 2+ rectal bleeding rate increased as the gEUDsum increased: 2.0% (2 of 102 patients) for <70 Gy, 10.3% (15 of 145 patients) for 70-80 Gy, 15.8% (12 of 76 patients) for 80-90 Gy, and 19.6% (9 of 46 patients) for >90 Gy (P=.002). Multivariate analysis identified age (P=.024) and gEUDsum (P=.000) as risk factors for grade 2+ rectal bleeding. CONCLUSIONS Our results demonstrate gEUD to be a potential predictive factor for grade 2+ late rectal bleeding after combined therapy for prostate cancer.
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Affiliation(s)
- Yutaka Shiraishi
- Department of Radiology, Keio University School of Medicine, Tokyo, Japan.
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van Nieuwenhuysen J, Waterhouse D, Bydder S, Joseph D, Ebert M, Caswell N. Survey of high-dose-rate prostate brachytherapy practice in Australia and New Zealand, 2010-2011. J Med Imaging Radiat Oncol 2013; 58:101-8. [PMID: 24529063 DOI: 10.1111/1754-9485.12101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 06/19/2013] [Indexed: 11/28/2022]
Abstract
INTRODUCTION A survey was designed to establish a baseline data set for the current routine practice of high-dose-rate prostate brachytherapy (HDR-PB) in Australia and New Zealand. Existing treatment protocols and clinical implementations are not generally known. METHODS The survey, for the 2010 and 2011 calendar years, collected data including number of patients treated; equipment used; imaging modalities; applicator verification and correction methods; dose prescriptions and normal tissue dose constraints. The number of HDR-PB patients treated was compared with the most recently published prostate cancer incidence data in Australia and in New Zealand. Total biologically equivalent doses in 2.0 Gy fractions (EQD2) were calculated for each prescription regime reported. RESULTS There were reductions, of 25-60%, in patients treated with HDR-PB from 2010 to 2011 in four departments. Prostate cancer patients are two to six times more likely to be prescribed HDR-PB in Western Australia than elsewhere in the region. There were 12 different treatment prescriptions, with EQD2 doses ranging from 73.5 to 97.6 Gy, among the 18 reported by survey respondents. Normal tissue definition methodology and dose constraints varied, and 13 of 15 departments reported that no particular published external guidelines were followed in full. CONCLUSION The high survey response rate, 15 of 17 departments, has provided a representative baseline data set of contemporary HDR-PB practice in Australia and New Zealand that may assist government and professional bodies, such as the Australasian Brachytherapy Group, in formulating recommendations, setting standards and future planning.
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Affiliation(s)
- Jane van Nieuwenhuysen
- Department of Radiation Oncology, Sir Charles Gairdner Hospital, Perth, Western Australia, Australia
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Breunig J, Hernandez S, Lin J, Alsager S, Dumstorf C, Price J, Steber J, Garza R, Nagda S, Melian E, Emami B, Roeske JC. A system for continual quality improvement of normal tissue delineation for radiation therapy treatment planning. Int J Radiat Oncol Biol Phys 2012; 83:e703-8. [PMID: 22583604 DOI: 10.1016/j.ijrobp.2012.02.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2011] [Revised: 02/03/2012] [Accepted: 02/03/2012] [Indexed: 02/08/2023]
Abstract
PURPOSE To implement the "plan-do-check-act" (PDCA) cycle for the continual quality improvement of normal tissue contours used for radiation therapy treatment planning. METHODS AND MATERIALS The CT scans of patients treated for tumors of the brain, head and neck, thorax, pancreas and prostate were selected for this study. For each scan, a radiation oncologist and a diagnostic radiologist, outlined the normal tissues ("gold" contours) using Radiation Therapy Oncology Group (RTOG) guidelines. A total of 30 organs were delineated. Independently, 5 board-certified dosimetrists and 1 trainee then outlined the same organs. Metrics used to compare the agreement between the dosimetrists' contours and the gold contours included the Dice Similarity Coefficient (DSC), and a penalty function using distance to agreement. Based on these scores, dosimetrists were re-trained on those organs in which they did not receive a passing score, and they were subsequently re-tested. RESULTS Passing scores were achieved on 19 of 30 organs evaluated. These scores were correlated to organ volume. For organ volumes <8 cc, the average DSC was 0.61 vs organ volumes ≥8 cc, for which the average DSC was 0.91 (P=.005). Normal tissues that had the lowest scores included the lenses, optic nerves, chiasm, cochlea, and esophagus. Of the 11 organs that were considered for re-testing, 10 showed improvement in the average score, and statistically significant improvement was noted in more than half of these organs after education and re-assessment. CONCLUSIONS The results of this study indicate the feasibility of applying the PDCA cycle to assess competence in the delineation of individual organs, and to identify areas for improvement. With testing, guidance, and re-evaluation, contouring consistency can be obtained across multiple dosimetrists. Our expectation is that continual quality improvement using the PDCA approach will ensure more accurate treatments and dose assessment in radiotherapy treatment planning and delivery.
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Affiliation(s)
- Jennifer Breunig
- Department of Radiation Oncology, Loyola University Medical Center, Maywood, Illinois, USA
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Urethra sparing – potential of combined Nickel–Titanium stent and intensity modulated radiation therapy in prostate cancer. Radiother Oncol 2012; 103:256-60. [DOI: 10.1016/j.radonc.2011.11.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Revised: 11/20/2011] [Accepted: 11/22/2011] [Indexed: 11/21/2022]
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Cury FL, Duclos M, Aprikian A, Patrocinio H, Kassouf W, Shenouda G, Faria S, David M, Souhami L. Single-Fraction High-Dose-Rate Brachytherapy and Hypofractionated External Beam Radiation Therapy in the Treatment of Intermediate-Risk Prostate Cancer – Long Term Results. Int J Radiat Oncol Biol Phys 2012; 82:1417-23. [DOI: 10.1016/j.ijrobp.2011.05.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 05/04/2011] [Accepted: 05/12/2011] [Indexed: 11/28/2022]
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Mavroidis P, Ferreira BC, Lopes MDC. Response-probability volume histograms and iso-probability of response charts in treatment plan evaluation. Med Phys 2011; 38:2382-97. [PMID: 21776773 DOI: 10.1118/1.3570613] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE This study aims at demonstrating a new method for treatment plan evaluation and comparison based on the radiobiological response of individual voxels. This is performed by applying them on three different cancer types and treatment plans of different conformalities. Furthermore, their usefulness is examined in conjunction with traditionally applied radiobiological and dosimetric treatment plan evaluation criteria. METHODS Three different cancer types (head and neck, breast and prostate) were selected to quantify the benefits of the proposed treatment plan evaluation method. In each case, conventional conformal radiotherapy (CRT) and intensity modulated radiotherapy (IMRT) treatment configurations were planned. Iso-probability of response charts was produced by calculating the response probability in every voxel using the linear-quadratic-Poisson model and the dose-response parameters of the corresponding structure to which this voxel belongs. The overall probabilities of target and normal tissue responses were calculated using the Poisson and the relative seriality models, respectively. The 3D dose distribution converted to a 2 Gy fractionation, D2(GY) and iso-BED distributions are also shown and compared with the proposed methodology. Response-probability volume histograms (RVH) were derived and compared with common dose volume histograms (DVH). The different dose distributions were also compared using the complication-free tumor control probability, P+, the biologically effective uniform dose, D, and common dosimetric criteria. RESULTS 3D Iso-probability of response distributions is very useful for plan evaluation since their visual information focuses on the doses that are likely to have a larger clinical effect in that particular organ. The graphical display becomes independent of the prescription dose highlighting the local radiation therapy effect in each voxel without the loss of important spatial information. For example, due to the exponential nature of the Poisson distribution, cold spots in the target volumes or hot spots in the normal tissues are much easier to be identified. Response-volume histograms, as DVH, can also be derived and used for plan comparison. RVH are advantageous since by incorporating the radiobiological properties of each voxel they summarize the 3D distribution into 2D without the loss of relevant information. Thus, more clinically relevant radiobiological objectives and constraints could be defined and used in treatment planning optimization. These measures become increasingly important when dose distributions need to be designed according to the microscopic biological properties of tumor and normal tissues. CONCLUSIONS The proposed methods do not aim to replace quantifiers like the probabilities of total tissue response, which ultimately are the quantities of interest to evaluate treatment success. However, iso-probability of response charts and response-probability volume histograms illustrates more clearly the difference in effectiveness between different treatment plans than the information provided by alternative dosimetric data. The use of 3D iso-probability of response distributions could serve as a good descriptor of the effectiveness of a dose distribution indicating primarily the regions in a tissue that dominate its response.
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Affiliation(s)
- Panayiotis Mavroidis
- Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, S-17176 Stockholm, Sweden.
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