Dosimetric implications of two registration based patient positioning methods in prostate image guided radiation therapy (IGRT)

Rivest, D. Ryan C.; Riauka, Terence; Murtha, Albert; Fallone, B. G.

doi:10.2478/v10019-009-0030-z

Cited by 3 publications

(6 citation statements)

References 32 publications

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“…Our results suggest that the rectal dose is higher with bone matching due to anterior interfractional motion of the prostate. This corresponds with findings by Rivest et al [15] and Rijkhorst et al [17] showing that anterior interfractional motion of the prostate is associated with increased rectal dose.…”

Section: Discussionsupporting

confidence: 74%

“…Thongphiew et al [14] investigated the use of CBCT in five fractions/week between bone and target matching and reported that bone matching resulted in a higher rectal dose than target matching. Using MVCT for comparison, Rivest et al [15] reported that the rectal dose was higher with bone matching when interfractional motion of the prostate was in the anterior direction. Hirose et al [16] compared rectal wall dose and bladder wall dose using CBCT and reported no differences between doses from bone matching and target matching.…”

Section: Discussionmentioning

confidence: 99%

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Dosimetric Comparison between Bone and Target Matching Considering Interfractional Prostate Motion in Volumetric Modulated Arc Therapy

Nakahara¹,

Ishii²,

Wakai³

et al. 2018

IJMPCERO

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Adequate matching methods are critical for accurate volumetric-modulated arc therapy (VMAT). We investigated the dosimetric differences in the target and organs at risk (OARs) between bone matching and target matching in patients with prostate cancer treated with VMAT. The relationship between the dosimetric differences and interfractional motion of the prostate was also evaluated. Forty patients with prostate cancer classified as intermediate risk were enrolled in a study to assess the differences in dosimetry between two matching methods. These patients were treated with VMAT and prescribed dose was 78 Gy. The dose distribution was calculated using cone-beam computed tomography (CBCT) for this study. We selected clinical target volume (CTV) as the target, and the rectum and bladder as the OARs. The Dmean, D98, D95, and D2 to the target and V10-V70 to the OARs were calculated as different dose from target matching value minus bone matching value. Multiple regression analysis was used to evaluate the effect of interfractional motion of the prostate on the differences in dose. The CTV D95 values differed by −0.22 ± 1.01 Gy (mean ± standard deviation). Rectum and bladder V70 values differed by 4.6% ± 7.2% and −2.6% ± 7.2%, respectively. There was a correlation between interfractional motion of the prostate and the dose differences to OARs (R 2 = 0.73 -0.94). The dose differences to OARs also varied depending on the direction of the prostate's motion. We found that bone matching resulted in an increased rectal dose and high risk of decreasing dose to the CTV.

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Section: Discussionsupporting

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Dosimetric Comparison between Bone and Target Matching Considering Interfractional Prostate Motion in Volumetric Modulated Arc Therapy

Nakahara¹,

Ishii²,

Wakai³

et al. 2018

IJMPCERO

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“…Photons with energies above 10 MeV can interact with the atomic nucleus of a high-Z material, of which the target and the head of the accelerator consist, and lead to the neutron ejection. Consequently, this can increase the patient dose and pose a problem in room shielding dosimetry, which is essential for the quality assurance in radiotherapy 2,3…”

Section: Introductionmentioning

confidence: 99%

A neutron track etch detector for electron linear accelerators in radiotherapy

Vuković

Faj²,

Poje³

et al. 2010

Radiology and Oncology

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BackgroundElectron linear accelerators in medical radiotherapy have replaced cobalt and caesium sources of radiation. However, medical accelerators with photon energies over 10 MeV generate undesired fast neutron contamination in a therapeutic X-ray photon beam. Photons with energies above 10 MeV can interact with the atomic nucleus of a high-Z material, of which the target and the head of an accelerator consist, and lead to the neutron ejection.Results and conclusions.Our neutron dosimeter, composed of the LR-115 track etch detector and boron foil BN-1 converter, was calibrated on thermal neutrons generated in the nuclear reactor of the Josef Stefan Institute (Slovenia), and applied to dosimetry of undesirable neutrons in photon radiotherapy by the linear accelerator 15 MV Siemens Mevatron. Having considered a high dependence of a cross-section between neutron and boron on neutron energy, and broad neutron spectrum in a photon beam, as well as outside the entrance door to maze of the Mevatron, we developed a method for determining the effective neutron detector response. A neutron dose rate in the photon beam was measured to be 1.96 Sv/h. Outside the Mevatron room the neutron dose rate was 0.62 μSv/h. PACS: 87.52. Ga; 87.53.St; 29.40.Wk.

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“…1 The pre-treatment 3D images are compared with the 3D images obtained previously for planning purpose and the required correction shifts are applied by readjusting the treatment couch position. 3,4 However, there is an associated cost of increased total time for the treatment, additional radiation dose for imaging and more workload. 3,4 However, there is an associated cost of increased total time for the treatment, additional radiation dose for imaging and more workload.…”

Section: Introductionmentioning

confidence: 99%

“…2 This process decreases errors caused by inter-fraction prostate motion with a possibility to reduce the planning target volume (PTV) margin for better sparing of healthy tissues. 3,4 However, there is an associated cost of increased total time for the treatment, additional radiation dose for imaging and more workload. 5 Even the most sophisticated immobilisation devices cannot completely eliminate the need for image guidance.…”

Section: Introductionmentioning

confidence: 99%

Image guidance procedures in radiotherapy for prostate cancer and the influence of body mass index

Piotrowski

Kaczmarek

Jodda³

et al. 2014

J Radiother Pract

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Purpose: To investigate possible optimisation of the image guidance procedure for the prostate cancer patients with respect to imaging frequency and patient body mass index (BMI).Methods: The 6,085 setup correction shifts and BMI for 216 prostate cancer patients treated on tomotherapy units in two centres were analysed. Margins needed to account for inter-fraction target motion with daily only automatic correction and with automatic and manual corrections during one, three or five first fractions as a reference for further treatment without imaging were calculated.Results: The planning target volume margin calculated for the daily automatic correction only scheme was significantly lower than the margins calculated for the image guidance limited to a few initial fractions. Manual corrections after automatic fusion were more important for patients with higher BMI. On average, the patients with normal BMI had manual correction shift of 0?7 mm in anterioposterior direction, while overweight and obese patients required, correspondingly, the shifts of 1?3 and 1?4 mm. Conclusion:Overweight and obese patients require daily imaging with time saving available by performing automatic kV/MV computed tomography registration only. The patients with normal BMI may be treated with imaging guidance during a few initial treatment fractions.

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Dosimetric implications of two registration based patient positioning methods in prostate image guided radiation therapy (IGRT)

Cited by 3 publications

References 32 publications

Dosimetric Comparison between Bone and Target Matching Considering Interfractional Prostate Motion in Volumetric Modulated Arc Therapy

Dosimetric Comparison between Bone and Target Matching Considering Interfractional Prostate Motion in Volumetric Modulated Arc Therapy

A neutron track etch detector for electron linear accelerators in radiotherapy

Image guidance procedures in radiotherapy for prostate cancer and the influence of body mass index

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