Intra-fraction motion of the prostate during treatment with helical tomotherapy

Thomas, S J; Ashburner, M; Tudor, G.; Treeby, Jo; Dean, J.C.; Routsis, D.; Rimmer, Y.; Russell, Simon; Burnet, N.G.

doi:10.1016/j.radonc.2013.09.011

Cited by 18 publications

(19 citation statements)

References 23 publications

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“…Margins of 2.2, 2.1 and 2.1 in the LR, SI and AP directions were required for translational motion only, and inclusion of the effect of rotations and matching errors increased these margins to approximately 4 mm in the LR and 5 mm in the SI and AP directions. 39 In a similar analysis, larger margins of 11.30, 9.95 and 13.49 mm in the same directions were proposed by Murthy et al 40 Kilovoltage cone beam CT Hirose et al 41 evaluated dosimetric consequences using kV CBCT guidance with either 8-mm margins (5-mm margin posteriorly and superiorly) or 5-mm margins isotropically. They showed that even with bony set-up correction, the target coverage was sufficient with both margins.…”

Section: Use Of Daily Ultrasoundmentioning

confidence: 76%

“…27 The intrafraction motion pattern has been shown to differ between patients and even in different fractions for the same treatment course. 91 Intratreatment motion has been evaluated by imaging before and after radiation delivery 39,48,90,[98][99][100] or directly during treatment using implanted electromagnetic transponders (beacons). 20,101,102 Fluoroscopy can also be used for prostate tracking at the expense of increased imaging dose, but Crocker et al 103 argued that this dose could be significantly reduced if the imaging field size is tailored to specific patients.…”

Section: Accounting For Intrafraction Motionmentioning

confidence: 99%

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Target margins in radiotherapy of prostate cancer

Yartsev

2016

BJR

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We reviewed the literature on the use of margins in radiotherapy of patients with prostate cancer, focusing on different options for image guidance (IG) and technical issues. The search in PubMed database was limited to include studies that involved external beam radiotherapy of the intact prostate. Post-prostatectomy studies, brachytherapy and particle therapy were excluded. Each article was characterized according to the IG strategy used: positioning on external marks using room lasers, bone anatomy and soft tissue match, usage of fiducial markers, electromagnetic tracking and adapted delivery. A lack of uniformity in margin selection among institutions was evident from the review. In general, introduction of pre- and in-treatment IG was associated with smaller planning target volume (PTV) margins, but there was a lack of definitive experimental/clinical studies providing robust information on selection of exact PTV values. In addition, there is a lack of comparative research regarding the cost-benefit ratio of the different strategies: insertion of fiducial markers or electromagnetic transponders facilitates prostate gland localization but at a price of invasive procedure; frequent pre-treatment imaging increases patient in-room time, dose and labour; online plan adaptation should improve radiation delivery accuracy but requires fast and precise computation. Finally, optimal protocols for quality assurance procedures need to be established.

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Section: Use Of Daily Ultrasoundmentioning

confidence: 76%

Section: Accounting For Intrafraction Motionmentioning

confidence: 99%

Target margins in radiotherapy of prostate cancer

Yartsev

2016

BJR

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“…This does not take into account rectal movements during the actual treatment fraction, which may be significant and may depend on the overall treatment time. 42,43 …”

Section: Discussionmentioning

confidence: 99%

Random variation in rectal position during radiotherapy for prostate cancer is two to three times greater than that predicted from prostate motion

Scaife

Harrison²,

Romanchikova³

et al. 2014

BJR

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Objective:Radiotherapy for prostate cancer does not explicitly take into account daily variation in the position of the rectum. It is important to accurately assess accumulated dose (DA) to the rectum in order to understand the relationship between dose and toxicity. The primary objective of this work was to quantify systematic (Σ) and random (σ) variation in the position of the rectum during a course of prostate radiotherapy.Methods:The rectum was manually outlined on the kilo-voltage planning scan and 37 daily mega-voltage image guidance scans for 10 participants recruited to the VoxTox study. The femoral heads were used to produce a fixed point to which all rectal contours were referenced.Results:Σ [standard deviation (SD) of means] between planning and treatment was 4.2 mm in the anteroposterior (AP) direction and 1.3 mm left–right (LR). σ (root mean square of SDs) was 5.2 mm AP and 2.7 mm LR. Superior–inferior variation was less than one slice above and below the planning position.Conclusion:Our results for Σ are in line with published data for prostate motion. σ, however, was approximately twice as great as that seen for prostate motion. This suggests that DA may differ from planned dose in some patients treated with radiotherapy for prostate cancer.Advances in knowledge:This work is the first to use daily imaging to quantify Σ and σ of the rectum in prostate cancer. σ was found to be greater than published data, providing strong rationale for further investigation of individual DA.

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“…Daily MVCT image guidance scans were acquired immediately prior to treatment delivery for the purposes of online target localisation [22]. Following our department protocol, scans were inspected for rectal dilation and if deemed excessive, remedial action was taken prior to delivery of radiation therapy [23].…”

Section: Methodsmentioning

confidence: 99%

Delivered dose can be a better predictor of rectal toxicity than planned dose in prostate radiotherapy

Shelley

Scaife

Romanchikova

et al. 2017

Radiotherapy and Oncology

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Background and purposeFor the first time, delivered dose to the rectum has been calculated and accumulated throughout the course of prostate radiotherapy using megavoltage computed tomography (MVCT) image guidance scans. Dosimetric parameters were linked with toxicity to test the hypothesis that delivered dose is a stronger predictor of toxicity than planned dose.Material and methodsDose–surface maps (DSMs) of the rectal wall were automatically generated from daily MVCT scans for 109 patients within the VoxTox research programme. Accumulated-DSMs, representing total delivered dose, and planned-DSMs, from planning CT data, were parametrised using Equivalent Uniform Dose (EUD) and ‘DSM dose-width’, the lateral dimension of an ellipse fitted to a discrete isodose cluster. Associations with 6 toxicity endpoints were assessed using receiver operator characteristic curve analysis.ResultsFor rectal bleeding, the area under the curve (AUC) was greater for accumulated dose than planned dose for DSM dose-widths up to 70 Gy. Accumulated 65 Gy DSM dose-width produced the strongest spatial correlation (AUC 0.664), while accumulated EUD generated the largest AUC overall (0.682). For proctitis, accumulated EUD was the only reportable predictor (AUC 0.673). Accumulated EUD was systematically lower than planned EUD.ConclusionsDosimetric parameters extracted from accumulated DSMs have demonstrated stronger correlations with rectal bleeding and proctitis, than planned DSMs.

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Intra-fraction motion of the prostate during treatment with helical tomotherapy

Cited by 18 publications

References 23 publications

Target margins in radiotherapy of prostate cancer

Target margins in radiotherapy of prostate cancer

Random variation in rectal position during radiotherapy for prostate cancer is two to three times greater than that predicted from prostate motion

Delivered dose can be a better predictor of rectal toxicity than planned dose in prostate radiotherapy

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