Cone-beam computed tomography (CBCT) for adaptive image guided head and neck radiation therapy

Hvid, C; Elstrøm, U.V.; Jensen, Kenneth; Grau, Cai

doi:10.1080/0284186x.2017.1398414

Cited by 42 publications

(23 citation statements)

References 28 publications

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“…It is therefore crucial to target patients with OAR overdose and/or target volume underdose. Systematic weekly dose surveillance based on CBCT resulted in an increased workload (100 min per patients) for a limited parotid gland dose decrease (<1 Gy) among a limited number of patients [58]. Ideally, replanning decisions should be based on early and simple anatomical predictors, with a clear objective of parotid gland overdose and/or tumor underdose correction.…”

Section: Discussionmentioning

confidence: 99%

Adaptive radiotherapy for head and neck cancer

et al. 2018

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Introduction: Large anatomical variations can be observed during the treatment course intensitymodulated radiotherapy (IMRT) for head and neck cancer (HNC), leading to potential dose variations. Adaptive radiotherapy (ART) uses one or several replanning sessions to correct these variations and thus optimize the delivered dose distribution to the daily anatomy of the patient. This review, which is focused on ART in the HNC, aims to identify the various strategies of ART and to estimate the dosimetric and clinical benefits of these strategies. Material and methods: We performed an electronic search of articles published in PubMed/MEDLINE and Science Direct from January 2005 to December 2016. Among a total of 134 articles assessed for eligibility, 29 articles were ultimately retained for the review. Eighteen studies evaluated dosimetric variations without ART, and 11 studies reported the benefits of ART. Results: Eight in silico studies tested a number of replanning sessions, ranging from 1 to 6, aiming primarily to reduce the dose to the parotid glands. The optimal timing for replanning appears to be early during the first two weeks of treatment. Compared to standard IMRT, ART decreases the mean dose to the parotid gland from 0.6 to 6 Gy and the maximum dose to the spinal cord from 0.1 to 4 Gy while improving target coverage and homogeneity in most studies. Only five studies reported the clinical results of ART, and three of those studies included a non-randomized comparison with standard IMRT. These studies suggest a benefit of ART in regard to decreasing xerostomia, increasing quality of life, and increasing local control. Patients with the largest early anatomical and dose variations are the best candidates for ART. Conclusion: ART may decrease toxicity and improve local control for locally advanced HNC. However, randomized trials are necessary to demonstrate the benefit of ART before using the technique in routine practice.

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Section: Discussionmentioning

confidence: 99%

Adaptive radiotherapy for head and neck cancer

et al. 2018

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“…Their results showed re-planning in 5 out of 110 patients (4.5%). In a study of Hvid et al RTTs performed daily treatment setup guided CBCT scans and recorded irregularities such as the need for manual adjustment of the treatment position after bony anatomy match, couch shifts > 3 degrees or > 1 cm change in body contour [21]. In their CBCT cohort, a total of 21 replans were performed in 17 out of 60 patients (28%).…”

Section: Discussionmentioning

confidence: 99%

“…Ahn et al preformed scheduled rescans mid-treatment and used CBCT scans to examine if the variations (systematic or random) were consistent by checking the position of the spinal cord, skull and upper neck [24]. Hvid et al on the other hand concluded that the presence of daily CBCT imaging, mid-course CT does not provide any added benefit, provided that skilled RTTs follow a match protocol to identify patients in need of adaptive re-planning [21]. Our findings are in line with these series.…”

Section: Discussionmentioning

confidence: 99%

Protocolised way to cope with anatomical changes in head & neck cancer during the course of radiotherapy

Beek¹,

Jonker²,

Hamming‐Vrieze

et al. 2019

Technical Innovations & Patient Support in Radiation Oncolo

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Introduction: During a course of radiotherapy for head-and-neck-cancer (HNC), non-rigid anatomical changes can be observed on daily Cone Beam CT (CBCT). To objectify responses to these changes, we use a decision support system (traffic light protocol). Action levels orange and red may lead to replanning. The purpose of this study was to evaluate how often re-planning was done for non-rigid anatomical changes, which anatomical changes led to re-planning and in which subgroups of patients treatment adaptation was deemed necessary. Materials and methods: A consecutive series of 388 HNC patients were retrospectively selected using the digital log of CBCT scans. The logs were analyzed for the number of new plans on an original planning CT scan (O-pCT) or a new pCT scan (N-pCT). Reasons for re-planning were categorized into: target volume increase/decrease, body contour decrease/increase and local shift of target volume. Subgroup analysis was performed to investigate relative differences of re-planning between treatment modalities. Results: For 33 patients the treatment plan was adapted due to anatomical changes, resulting in 37 new plans in total. Re-planning on a N-pCT with complete re-delineation was done 22 times. In fifteen cases a new plan was created after adjustment of contours on the O-pCT. Main reasons for re-planning were target volume increase, body contour decrease and local shifts of target volume. Most re-planning (23%) was seen in patients treated with chemoradiotherapy. Conclusion: Visual detection of anatomical changes on CBCT during treatment of HNC, results in replanning in 1 out of 10 patients.

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“…A verification process such as described here would increase availability on CT for all treatment sites within this busy department, whilst potentially reducing patient anxiety as many expect 'results' from the repeat planning CT. The safe omission of repeat CT during H&N RT has been previously justified [4,31]. Many institutions already acknowledge the benefit of rigid registrations using CBCT for on-treatment image guidance; and identifying anatomical changes.…”

Section: Verification At Mid-treatment Sct Vs Pct2mentioning

confidence: 99%

Analysis of dose using CBCT and synthetic CT during head and neck radiotherapy: A single centre feasibility study

Hay

Paterson

McLoone

et al. 2020

Technical Innovations & Patient Support in Radiation Oncolo

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a b s t r a c tObjectives: The study aimed to assess the suitability of deformable image registration (DIR) software to generate synthetic CT (sCT) scans for dose verification during radiotherapy to the head and neck. Planning and synthetic CT dose volume histograms were compared to evaluate dosimetric changes during the treatment course. Methods: Eligible patients had locally advanced (stage III, IVa and IVb) oropharyngeal cancer treated with primary radiotherapy. Weekly CBCT images were acquired post treatment at fractions 1, 6, 11, 16, 21 and 26 over a 30 fraction treatment course. Each CBCT was deformed with the planning CT to generate a sCT which was used to calculate the dose at that point in the treatment. A repeat planning CT2 was acquired at fraction 16 and deformed with the fraction 16 CBCT to compare differences between the calculations mid-treatment. Results: 20 patients were evaluated generating 138 synthetic CT sets. The single fraction mean dose to PTV_HR between the synthetic and planning CT did not vary, although dose to 95% of PTV_HR was smaller at week 6 compared to planning (difference 2.0%, 95% CI (0.8 to 3.1), p = 0.0). There was no statistically significant difference in PRV_brainstem or PRV_spinal cord maximum dose, although greater variation using the sCT calculations was reported. The mean dose to structures based on the fraction 16 sCT and CT2 scans were similar. Conclusions: Synthetic CT provides comparable dose calculations to those of a repeat planning CT; however the limitations of DIR must be understood before it is applied within the clinical setting.

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Cone-beam computed tomography (CBCT) for adaptive image guided head and neck radiation therapy

Cited by 42 publications

References 28 publications

Adaptive radiotherapy for head and neck cancer

Adaptive radiotherapy for head and neck cancer

Protocolised way to cope with anatomical changes in head & neck cancer during the course of radiotherapy

Analysis of dose using CBCT and synthetic CT during head and neck radiotherapy: A single centre feasibility study

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