Realizing the potential of magnetic resonance image guided radiotherapy in gynaecological and rectal cancer

White, I.; Scurr, Erica; Wetscherek, Andreas; Brown, Gina; Sohaib, Aslam; Nill, Simeon; Oelfke, Uwe; Dearnaley, David P.; Lalondrelle, Susan; Bhide, Shreerang A.

doi:10.1259/bjr.20180670

Cited by 15 publications

(15 citation statements)

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“…A limitation of this study is the moderate number of patients [20] and fractions (300) used for analyses. The significance and large difference between the online strategy and plan selection for all dose levels and for both SCRT and LCRT is, however, convincing.…”

Section: Discussionmentioning

confidence: 99%

“…Recent developments in improved image quality for treatment guidance, such as MRI-guided radiotherapy and CBCT guidance, as well as developments in fast and precise auto-contouring [18] and auto-planning 'marks the beginning of a new era' [19]. Online adaptive treatment, based on both MRI and CBCT guidance, is now a real possibility [19][20][21][22] and surely promising in reducing dose to the OARs even further.…”

Section: Introductionmentioning

confidence: 99%

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Online adaptive radiotherapy compared to plan selection for rectal cancer: quantifying the benefit

et al. 2020

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Background: To compare online adaptive radiation therapy (ART) to a clinically implemented plan selection strategy (PS) with respect to dose to the organs at risk (OAR) for rectal cancer. Methods: The first 20 patients treated with PS between May-September 2016 were included. This resulted in 10 short (SCRT) and 10 long (LCRT) course radiotherapy treatment schedules with a total of 300 Conebeam CT scans (CBCT). New dual arc VMAT plans were generated using auto-planning for both the online ART and PS strategy. For each fraction bowel bag, bladder and mesorectum were delineated on daily Conebeam CTs. The dose distribution planned was used to calculate daily DVHs. Coverage of the CTV was calculated, as defined by the dose received by 99% of the CTV volume (D99%). The volume of normal tissue irradiated with 95% of the prescribed fraction dose was calculated by calculating the volume receiving 95% of the prescribed fraction or more dose minus the volume of the CTV. For each fraction the difference between the plan selection and online adaptive strategy of each DVH parameter was calculated, as well as the average difference per patient. Results: Target coverage remained the same for online ART. The median volume of the normal tissue irradiated with 95% of the prescribed dose dropped from 642 cm3 (PS) to 237 cm3 (online-ART)(p < 0.001). Online ART reduced dose to the OARs for all tested dose levels for SCRT and LCRT (p < 0.001). For V15Gy of the bowel bag the median difference over all fractions of all patients was − 126 cm 3 in LCRT, while the average difference per patient ranged from − 206 cm 3 to − 40 cm 3. For SCRT the median difference was − 62 cm 3 , while the range of the average difference per patient was − 105 cm3 to − 51 cm 3. For V15Gy of the bladder the median difference over all fractions of all patients was 26% in LCRT, while the average difference per patient ranged from − 34 to 12%. For SCRT the median difference of V95% was − 8%, while the range of the average difference per patient was − 29 to 0%. Conclusions: Online ART for rectal cancer reduces dose the OARs significantly compared to a clinically implemented plan selection strategy, without compromising target coverage. Trial registration: Medical Research Involving Human Subjects Act (WMO) does not apply to this study and was retrospectively approved by the Medical Ethics review Committee of the Academic Medical Center (W19_357 # 19.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Online adaptive radiotherapy compared to plan selection for rectal cancer: quantifying the benefit

et al. 2020

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“…The importance of MRI imaging in cervical cancer management is well established [51]; including its transformation of IGABT. Magnetic resonanceguided radiation therapy (MRgRT) uses superior image quality [54,69] compared to computed tomography (CT), enhancing soft-tissue visibility and reducing inter-observer variability in contour delineation. Studies comparing CTand MRI-guided contour delineation for IGABT have shown that tumour contours can be significantly overestimated on CT [56,70].…”

Section: Magnetic Resonance Imaging-guided Online Adaptive Radiotherapymentioning

confidence: 99%

Adaptive Radiotherapy in the Management of Cervical Cancer: Review of Strategies and Clinical Implementation

et al. 2021

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“…[1][2][3][4][5][6] The potential for real-time adaptive radiotherapy (ART) could help us to achieve more accurate treatment delivery for pelvic sites, which are subject to large and irreproducible inter-and intra-fractional anatomical variations. [5][6][7] Variations in rectal gas have been shown to influence target coverage during conventional cervical, bladder and prostate cancer radiotherapy. [8][9][10][11][12][13] Furthermore, due to the electron return effect (ERE), there is a potential for dose perturbation in the rectal wall during MRIgRT treatment of these sites.…”

Section: Introductionmentioning

confidence: 99%

“…With superior soft tissue contrast to cone-beam computed tomography (CBCT) and the potential for real-time imaging, magnetic resonance imaging guided radiotherapy (MRIgRT) shows promise for pelvic sites including the cervix, bladder and prostate. [1][2][3][4][5][6] The potential for real-time adaptive radiotherapy (ART) could help us to achieve more accurate treatment delivery for pelvic sites, which are subject to large and irreproducible inter-and intra-fractional anatomical variations. [5][6][7] Variations in rectal gas have been shown to influence target coverage during conventional cervical, bladder and prostate cancer radiotherapy.…”

Section: Introductionmentioning

confidence: 99%

Inter‐ and intra‐fractional stability of rectal gas in pelvic cancer patients during MRIgRT

et al. 2020

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Purpose Due to the electron return effect (ERE) during magnetic resonance imaging guided radiotherapy (MRIgRT), rectal gas during pelvic treatments can result in hot spots of over‐dosage in the rectal wall. Determining the clinical impact of this effect on rectal toxicity requires estimation of the amount and mobility (and stability) of rectal gas during treatment. We therefore investigated the amount of rectal gas and local inter‐ and intra‐fractional changes of rectal gas in pelvic cancer patients. Methods To estimate the volume of gas present at treatment planning, the rectal gas contents in the planning computed tomography (CT) scans of 124 bladder, 70 cervical and 2180 prostate cancer patients were calculated. To estimate inter‐ and intra‐fractional variations in rectal gas, 174 and 131 T2‐w MRIs for six cervical and eleven bladder cancer patients were used. These scans were acquired during four scan‐sessions (~20–25 min each) at various time‐points. Additionally, 258 T2‐w MRIs of the first five prostate cancer patients treated using MRIgRT at our center, acquired during each fraction, were analyzed. Rectums were delineated on all scans. The area of gas within the rectum delineations was identified on each MRI slice using thresholding techniques. The area of gas on each slice of the rectum was used to calculate the inter‐ and intra‐fractional group mean, systematic and random variations along the length of the rectum. The cumulative dose perturbation as a result of the gas was estimated. Two approaches were explored: accounting or not accounting for the gas at the start of the scan‐session. Results Intra‐fractional variations in rectal gas are small compared to the absolute volume of rectal gas detected for all patient groups. That is, rectal gas is likely to remain stable for periods of 20–25 min. Larger volumes of gas and larger variations in gas volume were observed in bladder cancer patients compared with cervical and prostate cancer patients. For all patients, local cumulative dose perturbations per beam over an entire treatment in the order of 60 % were estimated when gas had not been accounted for in the daily adaption. The calculated dose perturbation over the whole treatment was dramatically reduced in all patients when accounting for the gas in the daily set‐up image. Conclusion Rectal gas in pelvic cancer patients is likely to remain stable over the course of an MRIgRT fraction, and also likely to reappear in the same location in multiple fractions, and can therefore result in clinically relevant over‐dosage in the rectal wall. The over‐dosage is reduced when accounting for gas in the daily adaption.

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Realizing the potential of magnetic resonance image guided radiotherapy in gynaecological and rectal cancer

Cited by 15 publications

References 100 publications

Online adaptive radiotherapy compared to plan selection for rectal cancer: quantifying the benefit

Online adaptive radiotherapy compared to plan selection for rectal cancer: quantifying the benefit

Adaptive Radiotherapy in the Management of Cervical Cancer: Review of Strategies and Clinical Implementation

Inter‐ and intra‐fractional stability of rectal gas in pelvic cancer patients during MRIgRT

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