Patient rotation during linac‐based photon electron radiotherapy

Kairn, Tanya

doi:10.1111/1754-9485.12757

Cited by 9 publications

(10 citation statements)

References 42 publications

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“…Of the 721 treatment plans that were identified as breast treatments containing PTV, heart and lung structures, 1.7% of cases were found to have involved patients treated in the prone (HFP) position. These treatment plans were not removed from the study, but were separated from the treatment plans for supine patients to allow separate analysis, due to the expected differences between prone and supine treatment plans, in terms of achievable PTV coverage and OAR sparing …”

Section: Resultsmentioning

confidence: 99%

Retrospective analysis of breast radiotherapy treatment plans: Curating the ‘non‐curated’

Kairn

Crowe

2019

J Med Imag Rad Onc

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Introduction: This paper provides a demonstration of how non-curated data can be retrospectively cleaned, so that existing repositories of radiotherapy treatment planning data can be used to complete bulk retrospective analyses of dosimetric trends and other plan characteristics. Methods: A non curated archive of 1137 radiotherapy treatment plans accumulated over a 12-month period, from five radiotherapy centres operated by one institution, was used to investigate and demonstrate a process of clinical data cleansing, by: identifying and translating inconsistent structure names; correcting inconsistent lung contouring; excluding plans for treatments other than breast tangents and plans without identifiable PTV, lung and heart structures; and identifying but not excluding plans that deviated from the local planning protocol. PTV, heart and lung dose-volume metrics were evaluated, in addition to a sample of personnel and linac load indicators. Results: Data cleansing reduced the number of treatment plans in the sample by 35.7%. Inconsistent structure names were successfully identified and translated (e.g. 35 different names for lung). Automatically separating whole lung structures into left and right lung structures allowed the effect of contralateral and ipsilateral lung dose to be evaluated, while introducing some small uncertainties, compared to manual contouring. PTV doses were indicative of prescription doses. Breast treatment work was unevenly distributed between oncologists and between metropolitan and regional centres. Conclusion: This paper exemplifies the data cleansing and data analysis steps that may be completed using existing treatment planning data, to provide individual radiation oncology departments with access to information on their own patient populations. Clearly, the well-planned and systematic recording of new, high quality data is the preferred solution, but the retrospective curation of non-curated data may be a useful interim solution, for radiation oncology departments where the systems for recording of new data have yet to be designed and agreed.

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Section: Resultsmentioning

confidence: 99%

Retrospective analysis of breast radiotherapy treatment plans: Curating the ‘non‐curated’

Kairn

Crowe

2019

J Med Imag Rad Onc

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“…These technological advances have renewed interest in utilisation of patient rotation with a fixed radiation source, or gantry-free radiation therapy. [6][7][8][9][10] Gantry-free systems could greatly reduce costs and design complexity of x-ray therapy systems, and proton and heavy-ion therapy where large gantries contribute to significant capital costs. Theoretically, removing rotating gantries could allow proton systems to be installed within 1-2 conventional x-ray therapy bunkers, making more widespread clinical uptake of protons viable.…”

Section: Introductionmentioning

confidence: 99%

“…These technological advances have renewed interest in utilisation of patient rotation with a fixed radiation source, or gantry‐free radiation therapy 6–10 . Gantry‐free systems could greatly reduce costs and design complexity of x‐ray therapy systems, and proton and heavy‐ion therapy where large gantries contribute to significant capital costs.…”

Section: Introductionmentioning

confidence: 99%

Measurements of human tolerance to horizontal rotation within an MRI scanner: Towards gantry‐free radiation therapy

et al. 2020

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Introduction Recent advances in image guidance and adaptive radiotherapy could enable gantry‐free radiotherapy using patient rotation. Gantry‐free radiotherapy could substantially reduce the cost of radiotherapy systems and facilities. MRI guidance complements a gantry‐free approach because of its ability to visualise soft tissue deformation during rotation. A potential barrier to gantry‐free radiotherapy is patient acceptability, especially when combined with MRI. This study investigates human experiences of horizontal rotation within an MRI scanner. Methods Ten healthy human participants and nine participants previously treated with radiotherapy were rotated within an MRI scanner. Participants' anxiety and motion sickness was assessed before being rotated in 45‐degree increments and paused, representing a multi‐field intensity‐modulated radiotherapy treatment. An MR image was acquired at each 45‐degree angle. Following imaging, anxiety and motion sickness were re‐assessed, followed by a comfort questionnaire and exit interview. The significance of the differences in anxiety and motion sickness pre‐ versus post‐imaging was assessed using Wilcoxon signed‐rank tests. Content analysis was performed on exit interview transcripts. Results Eight of ten healthy and eight of nine patient participants completed the imaging session. Mean anxiety scores before and after imaging were 7.9/100 and 11.8/100, respectively (P = 0.26), and mean motion sickness scores were 5.3/100 and 13.7/100, respectively (P = 0.02). Most participants indicated likely acceptance of rotation if MRI were to be used in a hypothetical treatment. Physical discomfort was reported to be the biggest concern. Conclusions Horizontal rotation within an MRI scanner was acceptable for most (17/19) participants.

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“…Some skepticism exists toward patient rotation. 6 The main concerns relate to patient tolerability 7 and, for horizontal rotation, the deformation of the external body contour 8 and internal organ motion. 9 It has been suggested that accounting for anatomical changes caused by rotation would require significant plan adaptation.…”

Section: Introductionmentioning

confidence: 99%

“…9 It has been suggested that accounting for anatomical changes caused by rotation would require significant plan adaptation. 6 Pelvic external body contour deformations of up to 28 mm have been observed during rotation. 8 However, Whelan et al showed that rigid registration based on the prostate contour yielded overlap statistics superior to interobserver contouring variability reported in the literature.…”

Section: Introductionmentioning

confidence: 99%

Pelvic organ motion and dosimetric implications during horizontal patient rotation for prostate radiation therapy

et al. 2020

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Purpose Gantry‐free radiation therapy systems utilizing patient rotation would be simpler and more cost effective than the conventional gantry‐based systems. Such a system could enable the expansion of radiation therapy to meet global demand and reduce capital costs. Recent advances in adaptive radiation therapy could potentially be applied to correct for gravitational deformation during horizontal patient rotation. This study aims to quantify the pelvic organ motion and the dosimetric implications of horizontal rotation for prostate intensity‐modulated radiation therapy (IMRT) treatments. Methods Eight human participants who previously received prostate radiation therapy were imaged in a clinical magnetic resonance imaging (MRI) scanner using a bespoke patient rotation system (PRS). The patients were imaged every 45 degrees during a full roll rotation (0–360 degrees). Whole pelvic bone, prostate, rectum, and bladder motion were compared to the supine position using dice similarity coefficient (DSC) and mean absolute surface distance (MASD). Prostate centroid motion was compared in the left–right (LR), superior–inferior (SI), and anterior–posterior (AP) direction prior to and following pelvic bone‐guided rigid registration. Seven‐field prostate IMRT treatment plans were generated for each patient rotation angles under three adaption scenarios: No plan adaption, rigid planning target volume (PTV)‐guided alignment to the prostate, and plan re‐optimization. Prostate, rectum, and bladder doses were compared for each adaption scenario. Results Pelvic bone motion within the PRS of up to 53 mm relative to the supine position was observed for some participants. Internal organ motion was greatest at the 180‐degree PRS couch angle (prone), with prostate centroid motion range < 2 mm LR, 0 mm to 14 mm SI, and −11 mm to 4 mm AP. Rotation with no adaption of the treatment plan resulted in an underdose to the PTV –– in some instances up to 75% (D95%: 78 ± 0.3 Gy at supine to 20 ± 15.0 Gy at the 225‐degree PRS couch angle). Bladder dose was reduced during the rotation by up to 98% (V60 Gy: 15.0 ± 9.4% supine to 0.3 ± 0.5% at the 225‐degree PRS couch angle). In some instances, the rectum dose increased during rotation (V60Gy: 20.0 ± 4.5% supine to 25.0 ± 15.0% at the 135‐degree PRS couch angle). Rigid PTV‐guided alignment resulted in PTV coverage which, though statistically lower (P < 0.05 for all D95% values), was within 1 Gy of the supine plans. Plan re‐optimization resulted in a statistically equivalent PTV coverage compared to the supine plans (P > 0.05 for all D95% metrics and all within ±0.4 Gy). For both rigid PTV‐guided alignment and plan re‐optimization, rectum dose volume metrics were reduced compared to the supine position between the 90‐ and 225‐degree PRS couch angles (P < 0.05). Bladder dose volume metrics were not impacted by rotation. Conclusion Pelvic bone and internal organ motion are present during patient rotation. Rigid PTV‐guided alignment to the prostate will be a requirement if prostate IMRT is to be safel...

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Patient rotation during linac‐based photon electron radiotherapy

Cited by 9 publications

References 42 publications

Retrospective analysis of breast radiotherapy treatment plans: Curating the ‘non‐curated’

Retrospective analysis of breast radiotherapy treatment plans: Curating the ‘non‐curated’

Measurements of human tolerance to horizontal rotation within an MRI scanner: Towards gantry‐free radiation therapy

Pelvic organ motion and dosimetric implications during horizontal patient rotation for prostate radiation therapy

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