1
|
Garrido-Hernandez G, Henjum H, Winter RM, Alsaker MD, Danielsen S, Boer CG, Ytre-Hauge KS, Redalen KR. Interim 18F-FDG-PET based response-adaptive dose escalation of proton therapy for head and neck cancer: a treatment planning feasibility study. Phys Med 2024; 123:103404. [PMID: 38852365 DOI: 10.1016/j.ejmp.2024.103404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Revised: 05/06/2024] [Accepted: 06/05/2024] [Indexed: 06/11/2024] Open
Abstract
BACKGROUND Image-driven dose escalation to tumor subvolumes has been proposed to improve treatment outcome in head and neck cancer (HNC). We used 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) acquired at baseline and into treatment (interim) to identify biologic target volumes (BTVs). We assessed the feasibility of interim dose escalation to the BTV with proton therapy by simulating the effects to organs at risk (OARs). METHODS We used the semiautomated just-enough-interaction (JEI) method to identify BTVs in 18F-FDG-PET images from nine HNC patients. Between baseline and interim FDG-PET, patients received photon radiotherapy. BTV was identified assuming that high standardized uptake value (SUV) at interim reflected tumor radioresistance. Using Eclipse (Varian Medical Systems), we simulated a 10% (6.8 Gy(RBE1.1)) and 20% (13.6 Gy(RBE1.1)) dose escalation to the BTV with protons and compared results with proton plans without dose escalation. RESULTS At interim 18F-FDG-PET, radiotherapy resulted in reduced SUV compared to baseline. However, spatial overlap between high-SUV regions at baseline and interim allowed for BTV identification. Proton therapy planning demonstrated that dose escalation to the BTV was feasible, and except for some 20% dose escalation plans, OAR doses did not significantly increase. CONCLUSION Our in silico analysis demonstrated the potential for interim 18F-FDG-PET response-adaptive dose escalation to the BTV with proton therapy. This approach may give more efficient treatment to HNC with radioresistant tumor subvolumes without increasing normal tissue toxicity. Studies in larger cohorts are required to determine the full potential for interim 18F-FDG-PET-guided dose escalation of proton therapy in HNC.
Collapse
Affiliation(s)
| | - Helge Henjum
- Department of Physics and Technology, University of Bergen, Bergen, Norway
| | - René Mario Winter
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
| | - Mirjam Delange Alsaker
- Department of Radiotherapy, Cancer Clinic, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway
| | - Signe Danielsen
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway; Department of Oncology, St. Olav's Hospital, Trondheim University Hospital, Trondheim, Norway
| | | | | | - Kathrine Røe Redalen
- Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway
| |
Collapse
|
2
|
Mallum A, Mkhize T, Akudugu JM, Ngwa W, Vorster M. The Role of Positron Emission Tomography and Computed Tomographic (PET/CT) Imaging for Radiation Therapy Planning: A Literature Review. Diagnostics (Basel) 2022; 13:diagnostics13010053. [PMID: 36611345 PMCID: PMC9818506 DOI: 10.3390/diagnostics13010053] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 12/15/2022] [Accepted: 12/15/2022] [Indexed: 12/28/2022] Open
Abstract
PET/CT is revolutionising radiotherapy treatment planning in many cancer sites. While its utility has been confirmed in some cancer sites, and is used in routine clinical practice, it is still at an experimental stage in many other cancer sites. This review discusses the utility of PET/CT in cancer sites where the role of PET/CT has been established in cases such as head and neck, cervix, brain, and lung cancers, as well as cancer sites where the role of PET/CT is still under investigation such as uterine, ovarian, and prostate cancers. Finally, the review touches on PET/CT utilisation in Africa.
Collapse
Affiliation(s)
- Abba Mallum
- Department of Radiotherapy and Oncology, College of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
- Department of Radiotherapy and Oncology, Inkosi Albert Luthuli Central Hospital, Durban 4091, South Africa
- University of Maiduguri Teaching Hospital, Maiduguri 600104, Nigeria
- Correspondence: or
| | - Thokozani Mkhize
- Department of Nuclear Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
- Department of Nuclear Medicine, Inkosi Albert Central Hospital, Durban 4091, South Africa
| | - John M. Akudugu
- Division of Radiobiology, Department of Medical Imaging and Clinical Oncology, Faculty of Medicine and Health Sciences, Stellenbosch University, Tygerberg 7505, South Africa
| | - Wilfred Ngwa
- School of Medicine, Johns Hopkins University, Baltimore, MD 21218, USA
- Brigham and Women’s Hospital, Dana-Farmer Cancer Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Mariza Vorster
- Department of Nuclear Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban 4000, South Africa
- Department of Nuclear Medicine, Inkosi Albert Central Hospital, Durban 4091, South Africa
| |
Collapse
|
3
|
Therapeutic optimization in head and neck radiotherapy planning: Advocacy for 18FDG PET-CT in treatment condition. Bull Cancer 2022; 109:1262-1268. [DOI: 10.1016/j.bulcan.2022.07.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 07/20/2022] [Accepted: 07/24/2022] [Indexed: 11/27/2022]
|
4
|
Abdollahi H, Chin E, Clark H, Hyde DE, Thomas S, Wu J, Uribe CF, Rahmim A. Radiomics-guided radiation therapy: opportunities and challenges. Phys Med Biol 2022; 67. [DOI: 10.1088/1361-6560/ac6fab] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 05/13/2022] [Indexed: 11/11/2022]
Abstract
Abstract
Radiomics is an advanced image-processing framework, which extracts image features and considers them as biomarkers towards personalized medicine. Applications include disease detection, diagnosis, prognosis, and therapy response assessment/prediction. As radiation therapy aims for further individualized treatments, radiomics could play a critical role in various steps before, during and after treatment. Elucidation of the concept of radiomics-guided radiation therapy (RGRT) is the aim of this review, attempting to highlight opportunities and challenges underlying the use of radiomics to guide clinicians and physicists towards more effective radiation treatments. This work identifies the value of RGRT in various steps of radiotherapy from patient selection to follow-up, and subsequently provides recommendations to improve future radiotherapy using quantitative imaging features.
Collapse
|
5
|
Laskar SG, Kakoti S. Modern Radiation Oncology: From IMRT to Particle Therapy—Present Status and the Days to Come. Indian J Med Paediatr Oncol 2022. [DOI: 10.1055/s-0042-1742446] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Abstract
AbstractThere has been tremendous technological development in the field of radiation oncology, mainly during the last few decades. Parallel advancements in imaging and accelerator technologies have contributed significantly to the same. Present-day radiation therapy is aimed at precision, in terms of physical accuracy of both its planning and delivery. This has been made possible by improvements in defining the target (use of various radiological and functional imaging modalities), advanced radiotherapy planning methods (intensity-modulated radiation therapy and recent emergence of particle therapy), and robust verification techniques (image-guided radiation therapy). These developments have enabled delivery of adequate tumoricidal doses conforming to the target, thereby improving disease control with reduced normal tissue toxicity in a wide range of malignancies. Elucidation of molecular pathways determining radioresistance or systemic effects of radiotherapy and strategies for therapeutic manipulation of the same are also being explored. Overall, we look forward to ensuring basic radiotherapy access to all patients, and precision radiation therapy to appropriate candidates (triaged by disease anatomy or biology and associated cost-effectiveness).
Collapse
Affiliation(s)
- Sarbani Ghosh Laskar
- Department of Radiation Oncology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra, India
| | - Sangeeta Kakoti
- Department of Radiation Oncology, Tata Memorial Hospital, Homi Bhabha National Institute, Mumbai, Maharashtra, India
| |
Collapse
|
6
|
Kim SY, Beer M, Tshering Vogel DW. Imaging in head and neck cancers: Update for non-radiologist. Oral Oncol 2021; 120:105434. [PMID: 34218063 DOI: 10.1016/j.oraloncology.2021.105434] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 06/14/2021] [Accepted: 06/22/2021] [Indexed: 12/24/2022]
Abstract
Head and neck cancer (HNC) is the fifth most frequent cancer worldwide and associated with significant morbidity. Along with clinical examination and endoscopic evaluation, imaging plays an important role in pre- and posttherapeutic evaluation of patients with HNC. Cross-sectional Imaging techniques such as computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography / computed tomography (PET/CT) are routinely used in the assessment of these patients. This review provides an overview of the various cross-sectional imaging modalities used in the evaluation of HNC and will give a short summary of the latest imaging technologies regarding head and neck cancer diagnosis.
Collapse
Affiliation(s)
- Soung Yung Kim
- Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Ulm, Germany.
| | - Meinrad Beer
- Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Ulm, Germany
| | - Dechen W Tshering Vogel
- University Institute for Diagnostic, Interventional and Paediatric Radiology, Inselspital University Hospital Bern, University of Bern, Freiburgstrasse 10, Bern 3010, Switzerland
| |
Collapse
|
7
|
Chang CC, Chen CJ, Hsu WL, Chang SM, Huang YF, Tyan YC. Prognostic Significance of Metabolic Parameters and Textural Features on 18F-FDG PET/CT in Invasive Ductal Carcinoma of Breast. Sci Rep 2019; 9:10946. [PMID: 31358786 PMCID: PMC6662792 DOI: 10.1038/s41598-019-46813-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Accepted: 06/25/2019] [Indexed: 12/19/2022] Open
Abstract
To investigate the prognostic significance of metabolic parameters and texture analysis on 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) in patients with breast invasive ductal carcinoma (IDC), from August 2005 to May 2015, IDC patients who had undergone pre-treatment FDG PET/CT were enrolled. The metabolic parameters, including maximal standardized uptake value of breast tumor (SUVbt) and ipsilateral axillary lymph node (SUVln), metabolic tumor volume (MTVbt) and total lesion glycolysis (TLGbt) of breast tumor, whole-body MTV (MTVwb) and whole-body TLG (TLGwb) were recorded. Nine textural features of tumor (four co-occurrence matrices and five SUV-based statistics) were measured. The prognostic significance of above parameters and clinical factors was assessed by univariate and multivariate analyses. Thirty-five patients were enrolled. Patients with low and high MTVwb had 5-year progression-free survival (PFS) of 81.0 and 14.3% (p < 0.0001). The 5-year overall survival for low and high MTVwb was 88.5% and 43.6% (p = 0.0005). Multivariate analyses showed MTVwb was an independent prognostic factor for PFS (HR: 8.29, 95% CI: 2.17–31.64, p = 0.0020). The SUV, TLG and textural features were not independently predictive. Elevated MTVwb was an independent predictor for shorter PFS in patients with breast IDC.
Collapse
Affiliation(s)
- Chin-Chuan Chang
- Department of Nuclear Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Graduate Institute of Clinical Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan.,Neuroscience Research Center, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Chao-Jung Chen
- Departments of Nuclear Medicine, Yuan's General Hospital, Kaohsiung, Taiwan.,Department of Health Business Administration, Meiho University, Pingtung, Taiwan
| | - Wen-Ling Hsu
- Department of Nuclear Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Shu-Min Chang
- Department of Nuclear Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Ying-Fong Huang
- Department of Nuclear Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.,Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Yu-Chang Tyan
- Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Department of Medical Imaging and Radiological Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. .,Institute of Medical Science and Technology, National Sun Yat-sen University, Kaohsiung, Taiwan. .,Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan.
| |
Collapse
|
8
|
Sun R, Orlhac F, Robert C, Reuzé S, Schernberg A, Buvat I, Deutsch E, Ferté C. In Regard to Mattonen et al. Int J Radiat Oncol Biol Phys 2016; 95:1544-1545. [DOI: 10.1016/j.ijrobp.2016.03.038] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 03/28/2016] [Indexed: 11/17/2022]
|
9
|
Kornerup JS, Brodin P, Birk Christensen C, Björk-Eriksson T, Kiil-Berthelsen A, Borgwardt L, Munck Af Rosenschöld P. Use of PET/CT instead of CT-only when planning for radiation therapy does not notably increase life years lost in children being treated for cancer. Pediatr Radiol 2015; 45:570-81. [PMID: 25378209 DOI: 10.1007/s00247-014-3197-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 07/03/2014] [Accepted: 08/13/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND PET/CT may be more helpful than CT alone for radiation therapy planning, but the added risk due to higher doses of ionizing radiation is unknown. OBJECTIVE To estimate the risk of cancer induction and mortality attributable to the [F-18]2-fluoro-2-deoxyglucose (FDG) PET and CT scans used for radiation therapy planning in children with cancer, and compare to the risks attributable to the cancer treatment. MATERIALS AND METHODS Organ doses and effective doses were estimated for 40 children (2-18 years old) who had been scanned using PET/CT as part of radiation therapy planning. The risk of inducing secondary cancer was estimated using the models in BEIR VII. The prognosis of an induced cancer was taken into account and the reduction in life expectancy, in terms of life years lost, was estimated for the diagnostics and compared to the life years lost attributable to the therapy. Multivariate linear regression was performed to find predictors for a high contribution to life years lost from the radiation therapy planning diagnostics. RESULTS The mean contribution from PET to the effective dose from one PET/CT scan was 24% (range: 7-64%). The average proportion of life years lost attributable to the nuclear medicine dose component from one PET/CT scan was 15% (range: 3-41%). The ratio of life years lost from the radiation therapy planning PET/CT scans and that of the cancer treatment was on average 0.02 (range: 0.01-0.09). Female gender was associated with increased life years lost from the scans (P < 0.001). CONCLUSION Using FDG-PET/CT instead of CT only when defining the target volumes for radiation therapy of children with cancer does not notably increase the number of life years lost attributable to diagnostic examinations.
Collapse
Affiliation(s)
- Josefine S Kornerup
- Section of Radiotherapy, Department of Oncology, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark,
| | | | | | | | | | | | | |
Collapse
|
10
|
Kornerup JS, Brodin NP, Björk-Eriksson T, Birk Christensen C, Kiil-Berthelsen A, Aznar MC, Hollensen C, Markova E, Munck Af Rosenschöld P. PET/CT-guided treatment planning for paediatric cancer patients: a simulation study of proton and conventional photon therapy. Br J Radiol 2014; 88:20140586. [PMID: 25494657 DOI: 10.1259/bjr.20140586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE To investigate the impact of including fluorine-18 fludeoxyglucose ((18)F-FDG) positron emission tomography (PET) scanning in the planning of paediatric radiotherapy (RT). METHODS Target volumes were first delineated without and subsequently re-delineated with access to (18)F-FDG PET scan information, on duplicate CT sets. RT plans were generated for three-dimensional conformal photon RT (3DCRT) and intensity-modulated proton therapy (IMPT). The results were evaluated by comparison of target volumes, target dose coverage parameters, normal tissue complication probability (NTCP) and estimated risk of secondary cancer (SC). RESULTS Considerable deviations between CT- and PET/CT-guided target volumes were seen in 3 out of the 11 patients studied. However, averaging over the whole cohort, CT or PET/CT guidance introduced no significant difference in the shape or size of the target volumes, target dose coverage, irradiated volumes, estimated NTCP or SC risk, neither for IMPT nor 3DCRT. CONCLUSION Our results imply that the inclusion of PET/CT scans in the RT planning process could have considerable impact for individual patients. There were no general trends of increasing or decreasing irradiated volumes, suggesting that the long-term morbidity of RT in childhood would on average remain largely unaffected. ADVANCES IN KNOWLEDGE (18)F-FDG PET-based RT planning does not systematically change NTCP or SC risk for paediatric cancer patients compared with CT only. 3 out of 11 patients had a distinct change of target volumes when PET-guided planning was introduced. Dice and mismatch metrics are not sufficient to assess the consequences of target volume differences in the context of RT.
Collapse
Affiliation(s)
- J S Kornerup
- 1 Section of Radiotherapy, Department of Oncology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Yan S, Bowsher J, Tough M, Cheng L, Yin FF. A hardware investigation of robotic SPECT for functional and molecular imaging onboard radiation therapy systems. Med Phys 2014; 41:112504. [PMID: 25370663 DOI: 10.1118/1.4898121] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE To construct a robotic SPECT system and to demonstrate its capability to image a thorax phantom on a radiation therapy flat-top couch, as a step toward onboard functional and molecular imaging in radiation therapy. METHODS A robotic SPECT imaging system was constructed utilizing a gamma camera detector (Digirad 2020tc) and a robot (KUKA KR150 L110 robot). An imaging study was performed with a phantom (PET CT Phantom(TM)), which includes five spheres of 10, 13, 17, 22, and 28 mm diameters. The phantom was placed on a flat-top couch. SPECT projections were acquired either with a parallel-hole collimator or a single-pinhole collimator, both without background in the phantom and with background at 1/10th the sphere activity concentration. The imaging trajectories of parallel-hole and pinhole collimated detectors spanned 180° and 228°, respectively. The pinhole detector viewed an off-centered spherical common volume which encompassed the 28 and 22 mm spheres. The common volume for parallel-hole system was centered at the phantom which encompassed all five spheres in the phantom. The maneuverability of the robotic system was tested by navigating the detector to trace the phantom and flat-top table while avoiding collision and maintaining the closest possible proximity to the common volume. The robot base and tool coordinates were used for image reconstruction. RESULTS The robotic SPECT system was able to maneuver parallel-hole and pinhole collimated SPECT detectors in close proximity to the phantom, minimizing impact of the flat-top couch on detector radius of rotation. Without background, all five spheres were visible in the reconstructed parallel-hole image, while four spheres, all except the smallest one, were visible in the reconstructed pinhole image. With background, three spheres of 17, 22, and 28 mm diameters were readily observed with the parallel-hole imaging, and the targeted spheres (22 and 28 mm diameters) were readily observed in the pinhole region-of-interest imaging. CONCLUSIONS Onboard SPECT could be achieved by a robot maneuvering a SPECT detector about patients in position for radiation therapy on a flat-top couch. The robot inherent coordinate frames could be an effective means to estimate detector pose for use in SPECT image reconstruction.
Collapse
Affiliation(s)
- Susu Yan
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710
| | - James Bowsher
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
| | - MengHeng Tough
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710
| | - Lin Cheng
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
| | - Fang-Fang Yin
- Medical Physics Graduate Program, Duke University, Durham, North Carolina 27710 and Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina 27710
| |
Collapse
|
12
|
Son SH, Kim DH, Hong CM, Kim CY, Jeong SY, Lee SW, Lee J, Ahn BC. Prognostic implication of intratumoral metabolic heterogeneity in invasive ductal carcinoma of the breast. BMC Cancer 2014; 14:585. [PMID: 25112709 PMCID: PMC4148559 DOI: 10.1186/1471-2407-14-585] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 08/05/2014] [Indexed: 11/16/2022] Open
Abstract
Background The purpose of this study was to evaluate the prognostic implication of findings of intratumoral metabolic heterogeneity on pretreatment 18F-FDG PET/CT scans in patients with invasive ductal carcinoma (IDC) of the breast. Methods One hundred and twenty-three female IDC patients who underwent pretreatment 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (18F-FDG PET/CT) scans were retrospectively evaluated in this study. The heterogeneity factor (HF) defined as the derivative (dV/dT) of a volume threshold function from 40% to 80%, was computed for each primary tumor. Other metabolic PET parameters (maximum standardized uptake value [SUVmax], metabolic tumor volume [MTV], and total lesion glycolysis [TLG]) were measured. The HF was compared with clinicopathologic factors and other PET parameters. Univariate and multivariate analyses for the overall survival (OS) were performed. Results The HF ranged from 0.02 to 6.72 (mean, 0.35 ± 0.82) and significantly correlated with MTV (r = 0.955; p < 0.0001) and TLG (r = 0.354; p = 0.0001). The HF was significantly higher (implying more heterogeneity) in tumors with higher T and N stages. The optimal cut-off values for the OS determined using a receiver operating characteristic (ROC) curve were 0.34 for the HF, 5.6 for SUVmax, 8.55 cm3 for MTV, and 14.43 for TLG. The OS rate among the 123 patients was 86.2%. T stage (1, 2 vs. 3, 4), N stage (0, 1 vs. 2, 3), M stage (0 vs. 1), ER status (+ vs. –), SUVmax (≤ 5.6 vs. > 5.6), MTV (≤ 8.55 cm3 vs. > 8.55 cm3), TLG (≤ 14.43 vs. > 14.43), and HF (< 0.34 vs. ≥ 0.34) affected the OS on univariate analysis. After adjustment for the effects of TNM stage and ER status, the HF and MTV were significant predictors of OS. Among the PET parameters, the best prognostic factor for OS was the HF. Conclusions Intratumoral metabolic heterogeneity correlated closely with the MTV and significantly affected the OS in IDC patients. The HF may act as a robust surrogate marker for the prediction of OS in IDC patients.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Byeong-Cheol Ahn
- Department of Nuclear Medicine, Kyungpook National University School of Medicine and Hospital, 50 Samduk-dong 2-ga, Jung-gu, Daegu 700-721, Republic of Korea.
| |
Collapse
|
13
|
A partial volume effect correction tailored for 18F-FDG-PET oncological studies. BIOMED RESEARCH INTERNATIONAL 2013; 2013:780458. [PMID: 24163819 PMCID: PMC3791573 DOI: 10.1155/2013/780458] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/02/2013] [Accepted: 08/02/2013] [Indexed: 11/20/2022]
Abstract
We have developed, optimized, and validated a method for partial volume effect (PVE) correction of oncological lesions in positron emission tomography (PET) clinical studies, based on recovery coefficients (RC) and on PET measurements of lesion-to-background ratio (L/Bm) and of lesion metabolic volume. An operator-independent technique, based on an optimised threshold of the maximum lesion uptake, allows to define an isocontour around the lesion on PET images in order to measure both lesion radioactivity uptake and lesion metabolic volume. RC are experimentally derived from PET measurements of hot spheres in hot background, miming oncological lesions. RC were obtained as a function of PET measured sphere-to-background ratio and PET measured sphere metabolic volume, both resulting from the threshold-isocontour technique. PVE correction of lesions of a diameter ranging from 10 mm to 40 mm and for measured L/Bm from 2 to 30 was performed using measured RC curves tailored at answering the need to quantify a large variety of real oncological lesions by means of PET. Validation of the PVE correction method resulted to be accurate (>89%) in clinical realistic conditions for lesion diameter > 1 cm, recovering >76% of radioactivity for lesion diameter < 1 cm. Results from patient studies showed that the proposed PVE correction method is suitable and feasible and has an impact on a clinical environment.
Collapse
|
14
|
Schinagl DAX, Span PN, van den Hoogen FJA, Merkx MAW, Slootweg PJ, Oyen WJG, Kaanders JHAM. Pathology-based validation of FDG PET segmentation tools for volume assessment of lymph node metastases from head and neck cancer. Eur J Nucl Med Mol Imaging 2013; 40:1828-35. [PMID: 23942906 DOI: 10.1007/s00259-013-2513-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Accepted: 07/04/2013] [Indexed: 12/29/2022]
Abstract
PURPOSE FDG PET is increasingly incorporated into radiation treatment planning of head and neck cancer. However, there are only limited data on the accuracy of radiotherapy target volume delineation by FDG PET. The purpose of this study was to validate FDG PET segmentation tools for volume assessment of lymph node metastases from head and neck cancer against the pathological method as the standard. METHODS Twelve patients with head and neck cancer and 28 metastatic lymph nodes eligible for therapeutic neck dissection underwent preoperative FDG PET/CT. The metastatic lymph nodes were delineated on CT (NodeCT) and ten PET segmentation tools were used to assess FDG PET-based nodal volumes: interpreting FDG PET visually (PETVIS), applying an isocontour at a standardized uptake value (SUV) of 2.5 (PETSUV), two segmentation tools with a fixed threshold of 40% and 50%, and two adaptive threshold based methods. The latter four tools were applied with the primary tumour as reference and also with the lymph node itself as reference. Nodal volumes were compared with the true volume as determined by pathological examination. RESULTS Both NodeCT and PETVIS showed good correlations with the pathological volume. PET segmentation tools using the metastatic node as reference all performed well but not better than PETVIS. The tools using the primary tumour as reference correlated poorly with pathology. PETSUV was unsatisfactory in 35% of the patients due to merging of the contours of adjacent nodes. CONCLUSION FDG PET accurately estimates metastatic lymph node volume, but beyond the detection of lymph node metastases (staging), it has no added value over CT alone for the delineation of routine radiotherapy target volumes. If FDG PET is used in radiotherapy planning, treatment adaptation or response assessment, we recommend an automated segmentation method for purposes of reproducibility and interinstitutional comparison.
Collapse
Affiliation(s)
- Dominic A X Schinagl
- Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands,
| | | | | | | | | | | | | |
Collapse
|
15
|
18-fluoro-deoxy-glucose positron emission tomography with computed tomography-based gross tumor volume estimation and validation with magnetic resonance imaging for locally advanced cervical cancers. Int J Gynecol Cancer 2012; 22:1031-6. [PMID: 22622949 DOI: 10.1097/igc.0b013e318251046b] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
PURPOSE Anatomy and morphology-based imaging is routinely used for radiotherapy purpose to deliver precision treatment. There is an interest in using information from functional imaging for conformal radiation therapy planning. These functional imaging techniques need to be validated rigorously before their routine use. We attempted to evaluate and validate the use of 18-fluoro-deoxy-glucose positron emission tomography with computed tomography (¹⁸FDG PET-CT) on primary tumor of the cervical carcinoma, with an aim of arriving at a cutoff maximum standardized uptake value (SUVmax) at which the tumor volume correlates best with magnetic resonance imaging (MRI). This observational study was a part of an ethics committee-approved study evaluating pretreatment MRI and FDG PET-CT. MATERIALS AND METHODS Patients' biopsy-proven cervical carcinomas (stages IIB and IIIB) were included in this study and underwent pretreatment MRI and FDG PET-CT as per institutional protocol. Volumes of the disease at the cervix on the MR image were calculated. Volumes at the FDG PET-CT scan at different percentages of SUVmax were auto contoured. Volume at MRI was correlated with each different percentage cutoff of the SUVmax. RESULTS Data of 74 patients were available for the study. The mean (SD) SUVmax of the primary tumor was 15.7 (7.0). The mean MRI volume correlates significantly (P < 0.001) with 30% and 35% of SUVmax values with good correlation according to the Pearson bivariate correlation (r = 0.79 each). The mean difference between MRI and PET volumes was least with 30% SUVmax. CONCLUSIONS ¹⁸FDG PET-CT SUV-based primary tumor volume estimation at 30% to 35% of SUVmax values correlates significantly with the criterion standard MR volumes for primary cervical tumor with squamous histology in our population.
Collapse
|
16
|
Nasopharyngeal carcinoma: investigation of intratumoral heterogeneity with FDG PET/CT. AJR Am J Roentgenol 2012; 199:169-74. [PMID: 22733909 DOI: 10.2214/ajr.11.7336] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE The purpose of this study was to quantitatively evaluate the role of intratumoral heterogeneity of (18)F-FDG uptake in characterizing nasopharyngeal carcinoma (NPC). SUBJECTS AND METHODS Forty consecutively registered patients with newly diagnosed NPC underwent PET/CT. The heterogeneity factor, defined as the derivative of a volume threshold function, was computed for each tumor. The relations between heterogeneity factor and maximum standardized uptake value (SUV(max)), tumor volume, and TNM category were determined by two-tailed Spearman correlation. Factors that potentially affect outcome determined by disease-free survival were studied by Kaplan-Meier analysis with a log-rank test for univariate analysis and the Cox proportional hazard model for multivariate analysis. RESULTS The heterogeneity factor ranged from -1.80 to -0.13 (mean, -0.40 [SD, 0.40]) and significantly correlated with SUV(max) (r = -0.372; p = 0.018), tumor volume (r = -0.983; p < 0.001), and T category (r = -0.457; p = 0.003) but not with N and M categories. There was a significant difference in heterogeneity factor between T1 and T2 tumors and T3 and T4 tumors (p = 0.012). The 2-year disease-free survival rate among the 38 patients was 67.4%. According to the results of Kaplan-Meier analysis with the log-rank test, heterogeneity factor and M category significantly affected disease-free survival. Patients with tumors that had a heterogeneity factor greater than -0.24 (less-heterogeneous group) (p = 0.0498) or M0 status (p < 0.001) had better disease-free survival rates. Multivariate analysis showed only M category to be an independent predictor of disease-free survival (p < 0.001). CONCLUSION The intratumoral heterogeneity of FDG uptake varies across NPC tumors, significantly correlates with tumor aggressiveness, and is predictive of patient outcome. These findings may be useful for characterizing NPC, predicting survival, and improving patient care.
Collapse
|
17
|
Gwynne S, Mukherjee S, Webster R, Spezi E, Staffurth J, Coles B, Adams R. Imaging for target volume delineation in rectal cancer radiotherapy--a systematic review. Clin Oncol (R Coll Radiol) 2011; 24:52-63. [PMID: 22035634 DOI: 10.1016/j.clon.2011.10.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 09/15/2011] [Accepted: 09/19/2011] [Indexed: 01/09/2023]
Abstract
The global move towards more conformal radiotherapy for rectal cancer requires better imaging modalities that both visualise the disease accurately and are reproducible; to reduce interobserver variation. This review explores the advances in imaging modalities used in target volume delineation, with a view to make recommendations for current clinical practice and to propose future directions for research. A systematic review was conducted using MEDLINE and EMBASE. Articles considered relevant by the authors were included. Planning with orthogonal films is being replaced by computed tomography (CT) simulation. This is now considered the 'gold standard' and allows conformal three-dimensional planning. Magnetic resonance imaging (MRI) has been shown to overcome some of the limitations of CT and can be used either as a diagnostic image to visually aid planning, or as a 'planning' MRI carried out in the treatment position and co-registered with the planning CT. The latter approach has been shown to change the treated volumes compared with CT and in prostate cancer patients has been shown to reduce interobserver variation. There are remaining issues with four-dimensional motion that are yet to be fully appreciated or overcome. 2-[18F] fluoro-2-deoxy-d-glucose positron emission tomography/CT co-registered with planning CT results in smaller volumes than CT alone and also reduces interobserver variation, but requires further validation before routine implementation. Experimental work utilising novel positron emission tomography tracers and diffusion-weighted MRI shows promise and requires further evaluation. Rigorous quality assurance is important with processing of newer imaging modalities. Further work needs to be conducted into both interobserver variation and the formal evaluation of the clinical benefits of newer imaging modalities. Developments in image-guided radiotherapy are also required to ensure that improvements in target definition at the planning stage are reproducible throughout treatment.
Collapse
Affiliation(s)
- S Gwynne
- Department of Clinical Oncology, Velindre Cancer Centre, Cardiff, UK.
| | | | | | | | | | | | | |
Collapse
|
18
|
Suehiro M, Yang G, Torchon G, Ackerstaff E, Humm J, Koutcher J, Ouerfelli O. Radiosynthesis of the tumor hypoxia marker [18F]TFMISO via O-[18F]trifluoroethylation reveals a striking difference between trifluoroethyl tosylate and iodide in regiochemical reactivity toward oxygen nucleophiles. Bioorg Med Chem 2011; 19:2287-97. [PMID: 21398131 DOI: 10.1016/j.bmc.2011.02.026] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 02/08/2011] [Accepted: 02/15/2011] [Indexed: 10/18/2022]
Abstract
The MRI hypoxia marker trifluoromisonidazole (TFMISO) [1-(2-nitro-1H-imidazol-1-yl)-3-(2,2,2-trifluoroethoxy)propan-2-ol] was successfully labeled with (18)F to expand its role into a bimodal PET/MRI probe. (18)F-Labeling was achieved via a three-step procedure in which 2,2,2-[(18)F]trifluoroethyl p-toluenesulfonate prepared by (18)F-(19)F exchange served as the [(18)F]trifluoroethylating agent. The O-[(18)F]trifluoroethylation reaction proceeded efficiently to give the intermediate 1,2-epoxy-3-(2,2,2-[(18)F]trifluoroethoxy)propane, with approximately 60% of (18)F incorporated from the tosylate precursor, which was condensed with 2-nitroimidazole to yield [(18)F]TFMISO. Approximately 40% of the [(18)F]trifluoroethyl tosylate precursor was converted into the final product. In stark contrast, 2,2,2-[(18)F]trifluoroethyl iodide failed to produce [(18)F]TFMISO, giving instead 1,1-[(18)F]difluoro-2-iodoethoxy and 1-[(18)F]fluoro-2-iodovinyloxy analogs of [(18)F]TFMISO. Thus, this investigation has identified 2,2,2-[(18)F]trifluoroethyl tosylate as an excellent [(18)F]trifluoroethylating agent, which can convert efficiently an alcohol into the corresponding [(18)F]trifluoroethyl ether.
Collapse
Affiliation(s)
- Makiko Suehiro
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
| | | | | | | | | | | | | |
Collapse
|
19
|
Shcherbinin S, Celler A. Quantitative accuracy of the closed-form least-squares solution for targeted SPECT. Phys Med Biol 2010; 55:5667-83. [DOI: 10.1088/0031-9155/55/19/004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
|
20
|
Troost EG, Schinagl DA, Bussink J, Oyen WJ, Kaanders JH. Clinical evidence on PET–CT for radiation therapy planning in head and neck tumours. Radiother Oncol 2010; 96:328-34. [DOI: 10.1016/j.radonc.2010.07.017] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2010] [Revised: 07/14/2010] [Accepted: 07/15/2010] [Indexed: 11/29/2022]
|
21
|
Troost EGC, Schinagl DAX, Bussink J, Boerman OC, van der Kogel AJ, Oyen WJG, Kaanders JHAM. Innovations in radiotherapy planning of head and neck cancers: role of PET. J Nucl Med 2009; 51:66-76. [PMID: 20009000 DOI: 10.2967/jnumed.108.061499] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Modern radiotherapy techniques heavily rely on high-quality medical imaging. PET provides biologic information about the tumor, complementary to anatomic imaging. Integrated PET/CT has found its way into the practice of radiation oncology, and (18)F-FDG PET is being introduced for radiotherapy planning. The functional information possibly augments accurate delineation and treatment of the tumor and its extensions while reducing the dose to surrounding healthy tissues. In addition to (18)F-FDG, other PET tracers are available for imaging specific biologic tumor characteristics determining radiation resistance. For head and neck cancer, the potential gains of PET are increasingly being recognized. This review describes the current role of PET and perspectives on its future use for selection and delineation of radiotherapy target volumes and for biologic characterization of this tumor entity. Furthermore, the potential role of PET for early response monitoring, treatment modification, and patient selection is addressed in this review.
Collapse
Affiliation(s)
- Esther G C Troost
- Department of Radiation Oncology, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
| | | | | | | | | | | | | |
Collapse
|
22
|
Zaidi H, Vees H, Wissmeyer M. Molecular PET/CT imaging-guided radiation therapy treatment planning. Acad Radiol 2009; 16:1108-33. [PMID: 19427800 DOI: 10.1016/j.acra.2009.02.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Revised: 02/11/2009] [Accepted: 02/19/2009] [Indexed: 01/01/2023]
Abstract
The role of positron emission tomography (PET) during the past decade has evolved rapidly from that of a pure research tool to a methodology of enormous clinical potential. (18)F-fluorodeoxyglucose (FDG)-PET is currently the most widely used probe in the diagnosis, staging, assessment of tumor response to treatment, and radiation therapy planning because metabolic changes generally precede the more conventionally measured parameter of change in tumor size. Data accumulated rapidly during the last decade, thus validating the efficacy of FDG imaging and many other tracers in a wide variety of malignant tumors with sensitivities and specificities often in the high 90 percentile range. As a result, PET/computed tomography (CT) had a significant impact on the management of patients because it obviated the need for further evaluation, guided further diagnostic procedures, and assisted in planning therapy for a considerable number of patients. On the other hand, the progress in radiation therapy technology has been enormous during the last two decades, now offering the possibility to plan highly conformal radiation dose distributions through the use of sophisticated beam targeting techniques such as intensity-modulated radiation therapy (IMRT) using tomotherapy, volumetric modulated arc therapy, and many other promising technologies for sculpted three-dimensional (3D) dose distribution. The foundation of molecular imaging-guided radiation therapy lies in the use of advanced imaging technology for improved definition of tumor target volumes, thus relating the absorbed dose information to image-based patient representations. This review documents technological advancements in the field concentrating on the conceptual role of molecular PET/CT imaging in radiation therapy treatment planning and related image processing issues with special emphasis on segmentation of medical images for the purpose of defining target volumes. There is still much more work to be done and many of the techniques reviewed are themselves not yet widely implemented in clinical settings.
Collapse
|
23
|
Suehiro M, Burgman P, Carlin S, Burke S, Yang G, Ouerfelli O, Oehler-Janne C, O'Donoghue J, Ling C, Humm J. Radiosynthesis of [(131)I]IAZGP via nucleophilic substitution and its biological evaluation as a hypoxia marker - is specific activity a factor influencing hypoxia-mapping ability of a hypoxia marker? Nucl Med Biol 2009; 36:477-87. [PMID: 19520288 DOI: 10.1016/j.nucmedbio.2009.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 02/24/2009] [Accepted: 03/06/2009] [Indexed: 11/25/2022]
Abstract
INTRODUCTION The hypoxia marker IAZGP, 1-(6-deoxy-6-iodo-beta-d-galactopyranosyl)-2-nitroimidazole, has been labeled with (123)I/(124)I/(125)I/(131)I via iodine-radioiodine exchange, which gives the radiotracer in a specific activity of 10-90 MBq/micromol. We synthesized the same radiotracer possessing several hundred to thousand times higher specific activity (high-SA IAZGP) via nucleophilic substitution and compared its biological behavior with that of conventionally produced IAZGP (low-SA IAZGP) to determine if specific activity is a factor influencing cell uptake kinetics, biodistribution and intratumor microregional localization of the radiotracer. METHODS High-SA [(131)I]IAZGP was prepared by substitution of the tosyl functionality with [(131)I]iodide. In vitro uptake of high- and low-SA [(131)I]IAZGP by HCT8 and HT29 cells was assessed in normoxic and hypoxic conditions. Biodistribution and intratumor localization of high- and low-SA [(131)I]IAZGP were determined by injection into HT29 tumor-bearing mice. RESULTS The nucleophilic substitution reaction proceeded efficiently in acetonitrile at 150 degrees C, giving the final product in an average yield of 42% and an average specific activity of 30 GBq/micromol. In vitro, high-SA [(131)I]IAZGP was incorporated into the tumor cells with similar kinetics and oxygen dependence to low-SA [(131)I]IAZGP. In HT29 tumor-bearing mice, biodistributions of high- and low-SA [(131)I]IAZGP were equivalent. Ex vivo autoradiography revealed heterogeneous intratumor localization of high-SA [(131)I]IAZGP corresponding closely to distributions of other exogenous and endogenous hypoxia markers. Comparable microregional distribution patterns were observed with low-SA [(131)I]IAZGP. CONCLUSIONS Radiolabeled IAZGP produced via nucleophilic substitution is validated as an exogenous hypoxia marker. Specific activity does not appear to influence the in vivo hypoxia-mapping ability of the radiotracer.
Collapse
Affiliation(s)
- Makiko Suehiro
- Department of Medical Physics, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Lecchi M, Fossati P, Elisei F, Orecchia R, Lucignani G. Current concepts on imaging in radiotherapy. Eur J Nucl Med Mol Imaging 2007; 35:821-37. [PMID: 17972074 DOI: 10.1007/s00259-007-0631-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2007] [Accepted: 10/02/2007] [Indexed: 11/29/2022]
Abstract
New high-precision radiotherapy (RT) techniques, such as intensity-modulated radiation therapy (IMRT) or hadrontherapy, allow better dose distribution within the target and spare a larger portion of normal tissue than conventional RT. These techniques require accurate tumour volume delineation and intrinsic characterization, as well as verification of target localisation and monitoring of organ motion and response assessment during treatment. These tasks are strongly dependent on imaging technologies. Among these, computed tomography (CT), magnetic resonance imaging (MRI), ultrasonography (US) and positron emission tomography (PET) have been applied in high-precision RT. For tumour volume delineation and characterization, PET has brought an additional dimension to the management of cancer patients by allowing the incorporation of crucial functional and molecular images in RT treatment planning, i.e. direct evaluation of tumour metabolism, cell proliferation, apoptosis, hypoxia and angiogenesis. The combination of PET and CT in a single imaging system (PET/CT) to obtain a fused anatomical and functional dataset is now emerging as a promising tool in radiotherapy departments for delineation of tumour volumes and optimization of treatment plans. Another exciting new area is image-guided radiotherapy (IGRT), which focuses on the potential benefit of advanced imaging and image registration to improve precision, daily target localization and monitoring during treatment, thus reducing morbidity and potentially allowing the safe delivery of higher doses. The variety of IGRT systems is rapidly expanding, including cone beam CT and US. This article examines the increasing role of imaging techniques in the entire process of high-precision radiotherapy.
Collapse
Affiliation(s)
- Michela Lecchi
- Institute of Radiological Sciences, University of Milan, Milan, Italy
| | | | | | | | | |
Collapse
|