First Clinical Release of an Online, Adaptive, Aperture-Based Image-Guided Radiotherapy Strategy in Intensity-Modulated Radiotherapy to Correct for Inter- and Intrafractional Rotations of the Prostate

The purpose of this study is to use the same diagnostic‐quality verification and planning CTs to validate planning margin account for residual interfractional variations with image‐guided soft tissue alignment of the prostate. For nine prostate cancer patients treated with IMRT to 78 Gy in 39 fractions, daily verification CT‐on‐rails images of the first seven and last seven fractions false(n=126false) were retrospectively selected for this study. On these images, prostate, bladder, and rectum were delineated by the same attending physician. Clinical plans were created with a margin of 8 mm except for 5 mm posteriorly, referred to as 8/5 mm. Three additional plans were created for each patient with the margins of 6/4 mm, 4/2 mm, and 2 mm uniform. These plans were subsequently applied to daily images and radiation doses were recalculated. The isocenters of these plans were placed according to clinical online shifts, which were based on soft tissue alignment to the prostate. Retrospective offline shifts by aligning prostate contours were compared to online shifts. The resultant daily target dose was analyzed using D99, the percentage of the prescription dose received by 99% of CTV. The percent of bladder volume receiving 65 Gy false(normalV65Gyfalse) and rectum normalV70Gy were also analyzed. After interfractional correction, using CTV normalD99>97%% criteria, 8/5 mm, 6/4 mm, 4/2 mm, and 2 mm planning margins met the CTV dose coverage in 95%, 91%, 65%, and 53% of the 126 fractions with online shifts, and 99%, 98%, 85%, and 68% with offline shifts. The rectum normalV70Gy and bladder normalV65Gy were significantly decreased at each level of margin reduction (p<0.05). With daily diagnostic quality imaging‐guidance, the interfractional planning margin may be reduced from 8/5 mm to 6/4 mm. The residual interfractional uncertainties most likely stem from prostate rotation and deformation.PACS number(s): 87.53.‐j

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“…Wang et al (22) showed that a 5 mm uniform margin offers an average prostate

V_{95}

\sim 97 %

. Other margin studies used either daily kV‐CBCT images 23 , 24 or implanted markers 17 , 25 , 26 …”

Section: Discussionmentioning

confidence: 99%

Using daily diagnostic quality images to validate planning margins for prostate interfractional variations

Vassil

Godley

et al. 2016

J Applied Clin Med Phys

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“…The rotational motion provided by KIM in real-time allows large rotation differences between planned and actual target positions to be corrected, and opens up possibilities for real-time rotation correction strategies such as MLC adaptation [18,28], or couch rotation. , compared with dose reconstructions for delivered with KIM (broken line) and without KIM correction (dotted line) using KIM acquired tumour motion for each successful fraction and the total course of treatment.…”

Section: Discussionmentioning

confidence: 99%

The first clinical implementation of a real-time six degree of freedom target tracking system during radiation therapy based on Kilovoltage Intrafraction Monitoring (KIM)

Nguyen

O’Brien

Kim

et al. 2017

Radiotherapy and Oncology

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Purpose: We present the first clinical implementation of a real-time six-degree of freedom (6DoF) Kilovoltage Intrafraction Monitoring (KIM) system which tracks the cancer target translational and rotational motions during treatment. The method was applied to measure and correct for target motion during stereotactic body radiotherapy (SBRT) for prostate cancer. The 6 DoF KIM system has sub-millimetre accuracy and precision in all three translational axes, and less than 1° accuracy and 4° precision in all three rotational axes.

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“…ART had been used clinically for prostate cancer since 1997, with a total of 1269 patients reported as treated at six different institutions [11,12,[13][14][15][16][17][18][19][20][21]. For the reviewed studies reporting CTV extension, the volume included prostate only in 405 patients, prostate and parts of the seminal vesicles in 649 patients and prostate, seminal vesicles and pelvic lymph nodes in one patient.…”

Section: Prostate Cancermentioning

confidence: 99%

“…Toxicity reports were limited to the bladder with an incidence of acute CTC Grade 3 of 9% [19]. The other study reporting ART for intra-fractional motion was conducted in 2009 in Salzburg [20]. As for the Toronto patients, the prostate and parts of the seminal vesicles were treated.…”

Section: Prostate Cancermentioning

confidence: 99%

Adaptive radiotherapy strategies for pelvic tumors – a systematic review of clinical implementations

et al. 2016

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First Clinical Release of an Online, Adaptive, Aperture-Based Image-Guided Radiotherapy Strategy in Intensity-Modulated Radiotherapy to Correct for Inter- and Intrafractional Rotations of the Prostate

Cited by 73 publications

References 20 publications

Using daily diagnostic quality images to validate planning margins for prostate interfractional variations

Using daily diagnostic quality images to validate planning margins for prostate interfractional variations

The first clinical implementation of a real-time six degree of freedom target tracking system during radiation therapy based on Kilovoltage Intrafraction Monitoring (KIM)

Adaptive radiotherapy strategies for pelvic tumors – a systematic review of clinical implementations

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