Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the <scp>AAPM</scp> Therapy Physics Committee Task Group 180

Ding, G; Alaei, Parham; Curran, Bruce; Flynn, R; Gossman, Michael S.; Mackie, T; Miften, Moyed; Morin, Richard L.; Xu, Xiaobin; Zhu, Timothy C.

doi:10.1002/mp.12824

Cited by 117 publications

(139 citation statements)

References 113 publications

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“…The significant differences in image dose between patient‐1 and patient‐2 or ‐3 are mainly due to the differences in the numbers of image acquisition arcs. By comparing the imaging doses between patient‐2 and patient‐3, it can be seen that the effect of patient size has significant impact on the kV imaging dose with variation in 30%–50% which is constant with the data in literature . Only small effect is observed for MV imaging dose and this is expected as megavoltage beam has larger penetrating power is not affected by patient size significantly.…”

Section: Resultssupporting

confidence: 66%

“…As seen in these three patient cases, the additional image dose with optimized LIVE system from kV beam acquisition procedures is clinically insignificant (<2 cGy). Although the imaging dose from MV may be significant, it is still not exceeding the image dose threshold (5% of the prescribed target dose for a typical dose of 8–20 Gy per faction in SBRT) recommended by AAPM TG‐180 . The MV image doses are generally confined to the target area due to limited field opening of the MV imaging beams.…”

Section: Resultsmentioning

confidence: 99%

“…A recent study demonstrated that LIVE can reconstruct the target volume for each respiratory phase accurately using kV/MV projections acquired at 1°/projection over orthogonal view 30° scan angles. Like any new image technique to be develop for clinical applications, the additional imaging dose to patient resulting from the 4D MV/kV imaging needs to be evaluated and managed …”

Section: Introductionmentioning

confidence: 99%

“…The purpose of this study is to determine the image dose resulting from a typical MV/kV image acquisition procedure with the parameters used in the LIVE system in order to manage the additional image dose if it exceeds the image dose threshold . The recommended threshold beyond which imaging dose should be accounted for as part of the total dose to patient is 5% of the therapeutic target dose …”

Section: Introductionmentioning

confidence: 99%

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Technical Note: Imaging dose resulting from optimized procedures with limited‐angle intrafractional verification system during stereotactic body radiation therapy lung treatment

2019

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Purpose The limited‐angle intrafractional verification (LIVE) system was developed to track tumor movement during stereotactic body radiation therapy (SBRT). However, the four‐dimensional (4D) MV/kV imaging procedure results in additional radiation dose to patients. This study is to quantify imaging radiation dose from optimized MV/kV image acquisition in the LIVE system and to determine if it exceeds the American Association of Physicists in Medicine Task Group Report 180 image dose threshold. Methods TrueBeam™ platform with a fully integrated system for image guidance was studied. Monte Carlo‐simulated kV and MV beams were calibrated and then used as incident sources in an EGSnrc Monte Carlo dose calculation in a CT image‐based patient model. In three representative lung SBRT treatments evaluated in this study, tumors were located in the patient's posterior left lung, mid‐left lung, and right upper lung. The optimized imaging sequence comprised of arcs ranging from 2 to 7, acquired between adjacent three‐dimensional (3D)/IMRT beams, with multiple simultaneous kV (125 kVp) and MV (6 MV) image projections in each arc, for different optimization scenarios. The MV imaging fields were generally confined to the treatment target while kV images were acquired with a normal open field size with a full bow‐tie filter. Results In a seven‐arc acquisitions case (highest imaging dose scenario), the maximum kV imaging doses to 50% of the tissue volume (D50 from DVHs), for spinal cord, right lung, heart, left lung, and the target, were 0.4, 0.4, 0.6, 0.7, and 1.4 cGy, respectively. The corresponding MV imaging doses were 0.1 cGy to spinal cord, right lung, heart, and left lung, and 11 cGy to target. In contrast, the maximum radiation dose from two cases treated with two Volumetric‐Modulated Arc Therapy (VMAT) fields and two‐arc image acquisitions is approximately 30% of that of the seven‐arc acquisition. Conclusions We have evaluated the additional radiation dose resulting from optimized LIVE system MV/kV image acquisitions in two best (least imaging dose) and one worst (highest imaging dose) lung SBRT treatment scenarios. The results show that these MV/kV imaging doses are comparable to those resulting from current imaging procedures used in Image‐Guided Radiation Therapy (IGRT) and are within the dose threshold of 5% target dose as recommended by the AAPM TG‐180 report.

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Section: Resultssupporting

confidence: 66%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Technical Note: Imaging dose resulting from optimized procedures with limited‐angle intrafractional verification system during stereotactic body radiation therapy lung treatment

2019

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“…In the case of kV x‐ray imaging beams, it has been demonstrated that accurate dose simulations requires full knowledge of the kV beam energy spectrum . The recently released AAPM TG180 report on image guidance doses delivered during radiotherapy provides a review of some of the literature on the dose delivered by the OBI during treatment. For example, older versions of the Varian OBI (Varian OBI 1.3) can deliver 1–9 cGy to soft tissue and 6–29 cGy to bones from a single cone‐beam CT scan, although lower doses are possible with advanced dose reduction technologies in modern imaging systems.…”

Section: Introductionmentioning

confidence: 99%

Use of a laser‐guided collimation system to perform direct kilovoltage x‐ray spectra measurements on a linear accelerator onboard imager

2018

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Clinical commissioning of a new patient positioning system, SyncTraX FX4, for intracranial stereotactic radiotherapy

Tanabe

Umetsu²,

Sasage³

et al. 2018

J Applied Clin Med Phys

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Background & AimsA new real‐time tracking radiotherapy (RTRT) system, the SyncTraX FX4 (Shimadzu, Kyoto, Japan), consisting of four X‐ray tubes and four ceiling‐mounted flat panel detectors (FPDs) combined with a linear accelerator, was installed at Uonuma Kikan Hospital (Niigata, Japan) for the first time worldwide. In addition to RTRT, the SyncTraX FX4 system enables bony structure‐based patient verification. Here we provide the first report of this system's clinical commissioning for intracranial stereotactic radiotherapy (SRT).Materials & MethodsA total of five tests were performed for the commissioning: evaluations of (1) the system's image quality; (2) the imaging and treatment coordinate coincidence; and (3) the localization accuracy of cone‐beam computed tomography (CBCT) and SyncTraX FX4; (4) the measurement of air kerma; (5) an end‐to‐end test.Results & DiscussionThe tests revealed the following. (1) All image quality evaluation items satisfied each acceptable criterion in all FPDs. (2) The maximum offsets among the centers were ≤0.40 mm in all combinations of the FPD and X‐ray tubes (preset). (3) The isocenter localization discrepancies between CBCT and preset #3 in the SyncTraX FX4 system were 0.29 ± 0.084 mm for anterior‐posterior, −0.19 ± 0.13 mm for superior‐inferior, 0.076 ± 0.11 mm for left‐right, −0.11 ± 0.066° for rotation, −0.14 ± 0.064° for pitch, and 0.072±0.058° for roll direction. the Pearson's product‐moment correlation coefficient between the two systems was >0.98 in all directions. (4) The mean air kerma value for preset #3 was 0.11 ± 0.0002 mGy in predefined settings (80 kV, 200 mA, 50 msec). (5) For 16 combinations of gantry and couch angles, median offset value in all presets was 0.31 mm (range 0.14–0.57 mm).ConclusionOur results demonstrate a competent performance of the SyncTraX FX4 system in terms of the localization accuracy for intracranial SRT.

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Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180

Abstract: Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient.

Cited by 117 publications

References 113 publications

Technical Note: Imaging dose resulting from optimized procedures with limited‐angle intrafractional verification system during stereotactic body radiation therapy lung treatment

Technical Note: Imaging dose resulting from optimized procedures with limited‐angle intrafractional verification system during stereotactic body radiation therapy lung treatment

Use of a laser‐guided collimation system to perform direct kilovoltage x‐ray spectra measurements on a linear accelerator onboard imager

Clinical commissioning of a new patient positioning system, SyncTraX FX4, for intracranial stereotactic radiotherapy

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