Fast, daily linac verification for segmented IMRT using electronic portal imaging

Vieira, Sandra; Bolt, René A.; Dirkx, M.; Visser, A.G.; Heijmen, B.

doi:10.1016/j.radonc.2006.06.010

Cited by 19 publications

(14 citation statements)

References 28 publications

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“…A more efficient tool for pre-treatment QA is the EPID as it is mounted on linac, providing real time feedback to the user. Although the primary purpose of EPID is to verify patient positioning, but with the introduction of on board imagers for image guidance the EPID has been more utilised for machine QA and pre-treatment patient specific QA [11][12][13][14]. Dosimetry using EPIDs or portal dosimetry has received considerable attention recently due to its relatively high-resolution of 0.392mm amorphous silicon (a-Si) flat-panel detector [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Mhatre¹,

Pilakkal²,

Chadha³

et al. 2018

J Nucl Med Radiat Ther

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Section: Introductionmentioning

confidence: 99%

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Mhatre¹,

Pilakkal²,

Chadha³

et al. 2018

J Nucl Med Radiat Ther

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“…2,12,15,27,29 EPIDs have been used for the QA of MLC performance in several studies. 7,9,15,[25][26][27][30][31][32][33] There have also been reports on the application of 2D array detectors such as MapCheck, MatriXX, and PTW-729 34,35 for this purpose. The major concern about these devices is their low spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

EPID‐based verification of the MLC performance for dynamic IMRT and VMAT

et al. 2012

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“…To correct for inter- and intra-fraction motion in prostate cancer patients, on-line set-up verification is performed before and during each treatment fraction [19,20]. On top of these individualized QA procedures, the IMRT performance of our linacs is checked daily with EPID measurements during the morning checks [23,24]. During the last eight years, we performed pre-treatment verification for all IMRT patients.…”

Section: Discussionmentioning

confidence: 99%

Accurate IMRT fluence verification for prostate cancer patients using ‘in-vivo’ measured EPID images and in-room acquired kilovoltage cone-beam CT scans

et al. 2013

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BackgroundTo investigate for prostate cancer patients the comparison of ‘in-vivo’ measured portal dose images (PDIs) with predictions based on a kilovoltage cone-beam CT scan (CBCT), acquired during the same treatment fraction, as an alternative for pre-treatment verification. For evaluation purposes, predictions were also performed using the patients’ planning CTs (pCT).MethodsTo get reliable CBCT electron densities for PDI predictions, Hounsfield units from the pCT were mapped onto the CBCT, while accounting for non-rigidity in patient anatomy in an approximate way. PDI prediction accuracy was first validated for an anatomical phantom, using IMRT treatment plans of ten prostate cancer patients. Clinical performance was studied using data acquired for 50 prostate cancer patients. For each patient, 4–5 CBCTs were available, resulting in a total of 1413 evaluated images. Measured and predicted PDIs were compared using γ-analyses with 3% global dose difference and 3 mm distance to agreement as reference criteria. Moreover, the pass rate for automated PDI comparison was assessed. To quantify improvements in IMRT fluence verification accuracy results from multiple fractions were combined by generating a γ-image with values halfway the minimum and median γ values, pixel by pixel.ResultsFor patients, CBCT-based PDI predictions showed a high agreement with measurements, with an average percentage of rejected pixels of 1.41% only. In spite of possible intra-fraction motion and anatomy changes, this was only slightly larger than for phantom measurements (0.86%). For pCT-based predictions, the agreement deteriorated (average percentage of rejected pixels 2.98%), due to an enhanced impact of anatomy variations. For predictions based on CBCT, combination of the first 2 fractions yielded gamma results in close agreement with pre-treatment analyses (average percentage of rejected pixels 0.63% versus 0.35%, percentage of rejected beams 0.6% versus 0%). For the pCT-based approach, only combination of the first 5 fractions resulted in acceptable agreement with pre-treatment results.ConclusionIn-room acquired CBCT scans can be used for high accuracy IMRT fluence verification based on in-vivo measured EPID images. Combination of γ results for the first 2 fractions can largely compensate for small accuracy reductions, with respect to pre-treatment verification, related to intra-fraction motion and anatomy changes.

show abstract

Fast, daily linac verification for segmented IMRT using electronic portal imaging

Cited by 19 publications

References 28 publications

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

EPID‐based verification of the MLC performance for dynamic IMRT and VMAT

Accurate IMRT fluence verification for prostate cancer patients using ‘in-vivo’ measured EPID images and in-room acquired kilovoltage cone-beam CT scans

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