Are Pre and Post Imaging Sufficient to Assess Intrafraction Prostate Motion?

Noël, C.; Roy, M.; Parikh, Parag J.; Kupelian, P.; Mahadevan, A.; Weinstein, G.; Enke, Charles Arthur; Flores, N.; Beyer, David; Levine, L.

doi:10.1016/j.ijrobp.2007.07.039

Cited by 3 publications

(1 citation statement)

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“…is used to determine the global movement of the prostate by taking into account the inter-and intrafraction motion. Published data on the prostate intrafractional motion suggest that an additional internal margin of more than 2.5 mm may be needed to account for this motion [54][55][56][57][58][59][60][61][62][63], with reports of some cases where this motion is greater than 1 cm [64,65]. For our study, the positional error owing to intrafraction motion was considered to be 4 mm [66,67].…”

Section: Simulation Of Delivered Dose Distributionmentioning

confidence: 99%

Schedule for CT image guidance in treating prostate cancer with helical tomotherapy

Beldjoudi

Yartsev²,

Battista³

et al. 2010

BJR

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The aim of this study was to determine the effect of reducing the number of image guidance sessions and patient-specific target margins on the dose distribution in the treatment of prostate cancer with helical tomotherapy. 20 patients with prostate cancer who were treated with helical tomotherapy using daily megavoltage CT (MVCT) imaging before treatment served as the study population. The average geometric shifts applied for set-up corrections, as a result of co-registration of MVCT and planning kilovoltage CT studies over an increasing number of image guidance sessions, were determined. Simulation of the consequences of various imaging scenarios on the dose distribution was performed for two patients with different patterns of interfraction changes in anatomy. Our analysis of the daily set-up correction shifts for 20 prostate cancer patients suggests that the use of four fractions would result in a population average shift that was within 1 mm of the average obtained from the data accumulated over all daily MVCT sessions. Simulation of a scenario in which imaging sessions are performed at a reduced frequency and the planning target volume margin is adapted provided significantly better sparing of organs at risk, with acceptable reproducibility of dose delivery to the clinical target volume. Our results indicate that four MVCT sessions on helical tomotherapy are sufficient to provide information for the creation of personalised target margins and the establishment of the new reference position that accounts for the systematic error. This simplified approach reduces overall treatment session time and decreases the imaging dose to the patient.

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Section: Simulation Of Delivered Dose Distributionmentioning

confidence: 99%

Schedule for CT image guidance in treating prostate cancer with helical tomotherapy

Beldjoudi

Yartsev²,

Battista³

et al. 2010

BJR

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Overview of Image-Guided Localization Modalities

Parikh¹,

Michalski²

2008

Image-Guided Radiation Therapy of Prostate Cancer

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Dose-Volume Factors to Select Patient-Specific Image-Guidance Action Thresholds in Prostate Cancer

Block

Lin

Hoggarth

et al. 2011

Technol Cancer Res Treat

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For radiation delivery tracking systems that monitor intrafraction prostate motion, generalized departmental threshold protocols may be used. The purpose of this study is to determine whether predefined action thresholds can be generally applied or if patient-specific action thresholds may be required. Software algorithms were developed in the MatLab (The Mathworks Inc., Natick, MA) software environment to simulate shifts of the patient structure set consisting of prostate, bladder, and rectum. These structures were shifted by 1/2 10 mm in each direction in 1 mm increments to simulate displacements during treatment, without taking into consideration organ deformity. Dose-volume data at each shift were plotted and analyzed. A linear relationship was observed between planning dose-volume parameters and shifted dose-volume parameters. For a 5 mm anterior shift, it was observed that individual rectal V70 values increased by absolute magnitudes of 6-15%, dependent on the planning rectal V70 of each patient. Likewise, for a 5 mm inferior shift, individual bladder V70 values increased by 1-14%, dependent on planning bladder V70. This linear relationship was observed for all levels of shifts up to 10 mm. Since rectum and bladder dose-volume changes due to patient shifts are dependent on dose-volume parameters, this study suggests that patient-specific action thresholds may be necessary.

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Are Pre and Post Imaging Sufficient to Assess Intrafraction Prostate Motion?

Cited by 3 publications

References 0 publications

Schedule for CT image guidance in treating prostate cancer with helical tomotherapy

Schedule for CT image guidance in treating prostate cancer with helical tomotherapy

Overview of Image-Guided Localization Modalities

Dose-Volume Factors to Select Patient-Specific Image-Guidance Action Thresholds in Prostate Cancer

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