Multiple “slow” CT scans for incorporating lung tumor mobility in radiotheraphy planning

Lagerwaard, Frank J.; Koste, John R. van Sörnsen de; Nijssen-Visser, Margriet R.J; Schuchhard-Schipper, Regine H.; Oei, S.S.; Munne, Aristoteles; Senan, Suresh

doi:10.1016/s0360-3016(01)01716-3

Cited by 180 publications

(81 citation statements)

References 11 publications

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“…It is therefore desirable to eliminate these motioninduced effects from the images. Methods besides gating techniques have been proposed for this task, including the acquisition of a slow CT scan over several respiratory cycles that better fits the respiratory-blurred PET data (16) or the use of an averaged CT scan derived from 4-dimensional CT measurements (17), therefore simulating a stand-alone PET scan, avoiding major attenuation correction artifacts, and retaining the whole PET statistics. These methods, however, still lead to motion-blurred data, resulting in a potential effective loss of resolution and of quantitative information from the images.…”

Section: Discussionmentioning

confidence: 99%

List Mode–Driven Cardiac and Respiratory Gating in PET

Büther¹,

Dawood²,

Stegger³

et al. 2009

J Nucl Med

194

151

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Gating methods acquiring biosignals (such as electrocardiography [ECG] and respiration) during PET enable one to reduce motion effects that potentially lead to image blurring and artifacts. This study evaluated different cardiac and respiratory gating methods: one based on ECG signals for cardiac gating and video signals for respiratory gating; 2 others based on measured inherent list mode events. Methods: Twenty-nine patients with coronary artery disease underwent a 20-min ECG-gated single-bed list mode PET scan of the heart. Of these, 17 were monitored by a video camera registering a marker on the patient's abdomen, thus capturing the respiratory motion for PET gating (video method). Additionally, respiratory and cardiac gating information was deduced without auxiliary measurements by dividing the list mode stream in 50-ms frames and then either determining the number of coincidences (sensitivity method) or computing the axial center of mass and SD of the measured counting rates in the same frames (center-of-mass method). The gated datasets (respiratory and cardiac gating) were reconstructed without attenuation correction. Measured wall thicknesses, maximum displacement of the left ventricular wall, and ejection fraction served as measures of the exactness of gating. Results: All methods successfully captured respiratory motion and significantly decreased motion-induced blurring in the gated images. The center-of-mass method resulted in significantly larger left ventricular wall displacements than did the sensitivity method (P , 0.02); other differences were nonsignificant. List mode-based cardiac gating was found to work well for patients with high 18 F-FDG uptake when the center-of-mass method was used, leading to an ejection fraction correlation coefficient of r 5 0.95 as compared with ECG-based gating. However, the sensitivity method did not always result in valid cardiac gating information, even in patients with high 18 F-FDG uptake. Conclusion: Our study demonstrated that valid gating signals during PET scans cannot be obtained only by tracking the external motion or applying an ECG but also by simply analyzing the PET list mode stream on a frame-by-frame basis. PETi s an established diagnostic tool widely appreciated in the clinical fields of oncology, neurology, cardiology, and several others. PET can show functional, metabolic, and molecular processes in vivo with a high sensitivity and offers the unique feature of absolute quantification of radiotracer distribution. However, several mathematic corrections have to be applied to the measured PET raw data before or during image reconstruction to obtain absolute quantitative data. The most important of these is attenuation correction, that is, correcting for the loss of coincidence photons due to absorption while they are traversing the human body. Accurate attenuation correction requires knowledge of attenuation values in the field of view of the scanner. In stand-alone PET scanners, this information is acquired during an additional transmission scan u...

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Section: Discussionmentioning

confidence: 99%

List Mode–Driven Cardiac and Respiratory Gating in PET

Büther¹,

Dawood²,

Stegger³

et al. 2009

J Nucl Med

194

151

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“…The gross tumour volume was defined in both CT scans, and the internal target volume was defined as the fusion of the gross tumour volume from the slow and fast CT scans. [15][16][17] The planning target volume was obtained by a 1-cm uniform expansion from the internal target volume. Patients were treated with four to six coplanar beams.…”

Section: Radiotherapy Techniquementioning

confidence: 99%

Hypofractionated 3D radiotherapy for inoperable T1-3 N0-1 non-small-cell lung cancer

Mollà

Saez

Ramos

et al. 2016

BJR

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Objective: This study assessed the toxicity and clinical outcomes of three-dimensional (3D) hypofractionated radiotherapy (HFRT) for medically inoperable T1-3 N0-1 non-small-cell lung cancer (NSCLC). Methods: 34 patients with inoperable early-stage NSCLC were treated from August 2008 to April 2013. Prior to enrolment, patients were required to be evaluated by an experienced thoracic surgeon to determine the "operability". All received 57 Gy in 19 fractions followed by escalated doses of 3-Gy fractions, up to a total dose of 66 Gy using a 3D conformal technique. Toxicities were measured using the Common Terminology Criteria for Adverse Effects v. 4.0. Results: The median follow-up was 33 months (7-74 months). Toxicity grades $3 were not observed. Local control (LC) was 80.4% at 2 years, whereas regional control (RC) was 78%. The overall survival (OS), time to progression (TTP) and time to distant metastasis (TTM) at 2 years were 60%, 59% and 80%, respectively. For patients with T1-2 N0 and a tumour size ,45 mm (n 5 19), rates of OS, TTP and TTM at 2 years were 71%, 75% and 94%, respectively. LC and RC at 2 years were 85% and 94%, respectively. Conclusion: HFRT using 3.0-Gy fractions amounting to a total dose of 66 Gy is the recommended dose. A Phase 2 trial is warranted in order to assess the safety and efficacy of this fractionation scheme. Advances in knowledge: HFRT results in a favourable outcome in early-stage lung cancer without the usual restrictions in tumour size and/or location associated with previous treatment methods. No special equipment is required, therefore permitting its application in any centre.

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“…In the case of PET, the simplest strategy would be to apply no motion correction to PET images, as both PET imaging and radiation therapy delivery encompass all phases of respiratory motion. Likewise, slow CT imaging can be used to create a phase-averaged CT image (17). Not accounting for motion during planning and radiation therapy delivery, however, can result in an unnecessary dose to nearby healthy organs.…”

Section: Motionmentioning

confidence: 99%

Molecular Imaging to Plan Radiotherapy and Evaluate Its Efficacy

2015

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Learning Objectives: On successful completion of this activity, participants should be able to describe (1) how to acquire high-quality molecular images for use in radiation therapy; (2) how molecular imaging can be used to plan radiotherapy and evaluate treatment efficacy; and (3) the limitations and challenges to widespread use of molecular imaging in radiation oncology.Financial Disclosure: The authors of this article have indicated no relevant relationships that could be perceived as a real or apparent conflict of interest. CME Credit: SNMMI is accredited by the Accreditation Council for Continuing Medical Education (ACCME) to sponsor continuing education for physicians. SNMMI designates each JNM continuing education article for a maximum of 2.0 AMA PRA Category 1 Credits. Physicians should claim only credit commensurate with the extent of their participation in the activity. For CE credit, SAM, and other credit types, participants can access this activity through the SNMMI website (http://www.snmmilearningcenter.org) through November 2018.Molecular imaging plays a central role in the management of radiation oncology patients. Specific uses of imaging, particularly to plan radiotherapy and assess its efficacy, require an additional level of reproducibility and image quality beyond what is required for diagnostic imaging. Specific requirements include proper patient preparation, adequate technologist training, careful imaging protocol design, reliable scanner technology, reproducible software algorithms, and reliable data analysis methods. As uncertainty in target definition is arguably the greatest challenge facing radiation oncology, the greatest impact that molecular imaging can have may be in the reduction of interobserver variability in target volume delineation and in providing greater conformity between target volume boundaries and true tumor boundaries. Several automatic and semiautomatic contouring methods based on molecular imaging are available but still need sufficient validation to be widely adopted. Biologically conformal radiotherapy (dose painting) based on molecular imaging-assessed tumor heterogeneity is being investigated, but many challenges remain to fully exploring its potential. Molecular imaging also plays increasingly important roles in both early (during treatment) and late (after treatment) response assessment as both a predictive and a prognostic tool. Because of potentially confounding effects of radiation-induced inflammation, treatment response assessment requires careful interpretation. Although molecular imaging is already strongly embedded in radiotherapy, the path to widespread and all-inclusive use is still long. The lack of solid clinical evidence is the main impediment to broader use. Recommendations for practicing physicians are still rather scarce. 18 F-FDG PET/CT remains the main molecular imaging modality in radiation oncology applications. Although other molecular imaging options (e.g., proliferation imaging) are becoming more common, their widespread use is limited ...

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Multiple “slow” CT scans for incorporating lung tumor mobility in radiotheraphy planning

Cited by 180 publications

References 11 publications

List Mode–Driven Cardiac and Respiratory Gating in PET

List Mode–Driven Cardiac and Respiratory Gating in PET

Hypofractionated 3D radiotherapy for inoperable T1-3 N0-1 non-small-cell lung cancer

Molecular Imaging to Plan Radiotherapy and Evaluate Its Efficacy

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