Evaluation of changes in the size and location of the prostate, seminal vesicles, bladder, and rectum during a course of external beam radiation therapy

Roeske, John C.; Forman, Jeffrey D.; Mesina, Carmen F.; He, T.; Pelizzari, Charles A.; Fontenla, Ernesto; Vijayakumar, Srinivasan; Chen, George T.Y.

doi:10.1016/0360-3016(95)00225-1

Cited by 384 publications

(182 citation statements)

References 11 publications

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“…Dosimetric studies 3 , 4 , 5 have shown the change in bladder and rectum volume during radiation therapy and the impact of it on delivered doses. McParland et al (6) in a study of five patients with prostate radiotherapy also observed that there was a significant difference in bladder and rectum volumes and doses as compared to the planning CT volumes and doses.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation

Pearson

Gill

Campbell

et al. 2016

J Applied Clin Med Phys

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Delivered dose can be calculated by transferring the planned treatment beams onto the daily CBCT. Bladder and rectum volumetric doses were calculated and correlated to the daily bladder and rectum fullness. Patients for this study underwent hypofractionated prostate IMRT to 70 Gy in 28 fractions. Daily CBCT was utilized for image guidance. A clinically acceptable plan was created using a CTV‐to‐PTV uniform margin of 5 mm. Image fusion was performed to transfer the bladder and rectum contours onto each CBCT. Contours were then edited to match the anatomy of each CBCT. Using the daily treatment isocenter, the planned beams were transferred onto the CBCT and daily and cumulative DVHs calculated. For the results a total of 168 daily CBCTs were evaluated. The bladder was found to be smaller for 74.7% of the 168 daily CBCTs accessed in this study. This reduction in volume correlated to an increase in the cumulative bladder V70 Gy from 9.47% on the planning CT to 10.99% during treatment. V70Gy for the rectum was 7.27% on the planning CT, when all six patients were averaged, and increased to 11.56% on the average of all daily treatment CBCTs. Increases in volumetric rectum dose correlated with increases in rectal volume. For one patient, the rectum and bladder absolute V70 Gy, averaged over the course of treatment, increased by 295% and 61%, respectively. Larger variations in the daily bladder and rectal volume were observed and these correlated to large deviations from the volumetric dose received by these structures. In summary, bladder and rectum volume changes during treatment have an effect on the cumulative dose received by these organs. It was observed that the volumetric dose received by the bladder decreases as the volume of the bladder increases. The inverse was true for the rectum.PACS number(s): 87.55.dk‐, 87.57.Q‐

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Section: Introductionmentioning

confidence: 99%

Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation

Pearson

Gill

Campbell

et al. 2016

J Applied Clin Med Phys

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“…During the course of radiation therapy, daily changes such as bowel gas and bladder filling alter the soft‐tissue landscape within a patient's anatomy, ( 1 – 3 ) adding to the more gradual changes in tumor or target‐structure volume and shape over the course of treatment. Positional changes are usually assessed using electronic portal images acquired either weekly or, less commonly, immediately before delivery of each fraction.…”

Section: Introductionmentioning

confidence: 99%

Quantitative evaluation of a cone‐beam computed tomography–planning computed tomography deformable image registration method for adaptive radiation therapy

Lawson

Schreibmann

Jani

et al. 2007

J Applied Clin Med Phys

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Deformable (non‐rigid) registration is an essential tool in both adaptive radiation therapy and image‐guided radiation therapy to account for soft‐tissue changes during the course of treatment. The evaluation method most commonly used to assess the accuracy of deformable image registration is qualitative human evaluation. Here, we propose a method for systematically measuring the accuracy of an algorithm in recovering artificially introduced deformations in cases of rigid geometry, and we use that method to quantify the ability of a modified basis spline (B‐Spline) registration algorithm to recover artificially introduced deformations. The evaluation method is entirely computer‐driven and eliminates biased interpretation associated with human evaluation; it can be applied to any chosen method of image registration.Our method involves using planning computed tomography (PCT) images acquired with a conventional CT simulator and cone‐beam computed tomography (CBCT) images acquired daily by a linear accelerator–mounted kilovoltage image system in the treatment delivery room. The deformation that occurs between the PCT and daily CBCT images is obtained using a modified version of the B‐Spline deformable model designed to overcome the low soft‐tissue contrast and the artifacts and distortions observed in CBCT images. Clinical CBCT images and contours of phantom and central nervous system cases were deformed (warped) with known random deformations. In registering the deformed with the non‐deformed image sets, we tracked the algorithm's ability to recover the original, non‐deformed set. Registration error was measured as the mean and maximum difference between the original and the registered surface contours from outlined structures. Using this approach, two sets of tests can be devised. To measure the residual error related to the optimizer's convergence performance, the warped CBCT image is registered to the unwarped version of itself, eliminating unknown factors such as noise and positioning errors. To study additional errors introduced by artifacts and noise in the CBCT image, the warped CBCT image is registered to the original PCT image.Using a B‐Spline deformable image registration algorithm, mean residual error introduced by the algorithm's performance on noise‐free images was less than 1 mm, with a maximum of 2 mm. The chosen deformable image registration model was capable of accommodating significant variability in structures over time, because the artificially introduced deformation magnitude did not significantly influence the residual error. On the second type of test, noise and artifacts reduced registration accuracy to a mean of 1.33 mm and a maximum of 4.86 mm.The accuracy of deformable image registration can be easily and consistently measured by evaluating the algorithm's ability to recover artificially introduced deformations in rigid cases in which the true solution is known a priori. The method is completely automated, applicable to any chosen registration algorithm, and does not require user interact...

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“…The issue of prostate motion has been investigated by many research groups. The previously reported range of inter-fractional motion of the prostate, as measured by a standard deviation from the initial setup, was 0.7 -5.2 mm for all directions [2] [3] [8]- [13]. Table 3 lists the previous studies of the daily inter-fractional motions of the prostate measured by various image guidance methods [5]- [7].…”

Section: Discussionmentioning

confidence: 99%

“…In the current prospective study of daily KV CBCT as part of a rescan protocol, both the mean displacement of the inter-fractional motion and the rate of <5 mm inter-fractional motion of the prostate were better than those in the previous studies (Table 3), thus indicating this protocol to be promising for improving radiation therapy. The general consensus among the studies of the inter-fractional motion of the prostate was that rectal filling has a larger effect on prostate motion than bladder filling [2] [3] [8]- [13]. Antolak et al reported in CT studies during a course of RT that the prostate mobility was not significantly correlated with the bladder volume, however, the mobility of both the prostate and seminal vesicles significantly correlated with the rectal volume [9].…”

Section: Discussionmentioning

confidence: 99%

“…More accurate delivery of the prescribed dose would allow for the reduction of the safety margin around the clinical target volume (CTV). Many recent studies have focused on localizing and quantifying prostate displacement [2]- [4]. Various targeting modalities have been used, such as two-dimensional portal imaging, and fiducial marker matching to three-dimensional (3D) volumetric computed tomography (CT) and ultrasound information [5]- [7].…”

Section: Introductionmentioning

confidence: 99%

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Efficacy of Daily Cone-Beam Computed Tomography as Part of a Rescan Protocol for Large Offset to Reduce the Inter-Fractional Motion of the Prostate

Yamaguchi¹,

Ohguri²,

Imada³

et al. 2014

IJMPCERO

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Purpose: To prospectively analyze the inter-fractional motion of the prostate in patients with prostate cancer treated with intensity-modulated radiation therapy (IMRT) using image-guided radiotherapy (IGRT) with daily cone-beam computed tomography (CBCT) as part of a rescan protocol for large offset, and to evaluate the efficacy of our protocol. Materials and Methods: Eligible patients were treated with the following protocol: 1) magnesium oxide and dimethylpolysiloxane were administered to ensure that patients had regular bowel movements; 2) the patients were instructed to have an appropriately distended bladder during the planning CT and daily irradiation; 3) the daily CBCT image was fused with the planning CT image using the prostate outline; and 4) if large offset was recognized, a rescan CBCT image was obtained after appropriate countermeasures, such as the discharge of gas and defecation, and re-registration was performed. Three shifts for the inter-fractional motion of the prostate were analyzed, in the fractions which needed the CBCT rescan; the displacement data after the final rescan were used. Results: Sixty-one patients were eligible, and a total of 2302 fractions were available for the analysis. Rescans of the CBCT for large offset were performed in 113 (5%) of the 2302 fractions. After the first rescan, the large offset was resolved in 106 (94%) of the 113 fractions. Excessive rectal gas was the reason for the large offset in 94 (83%) of the 113 fractions. The total mean and standard deviation of the inter-fractional motion of the prostate in the AP, LR, and SI directions were 1.1 ± 2.4, −0.1 ± 2.3, and 0.7 ± 3.0 mm, respectively. Conclusion: Large offset was recognized in 5% of all fractions. Daily * Corresponding author. S. Yamaguchi et al. 194CBCT with our rescan protocol could resolve the large offset, which was mainly caused by excessive rectal gas, and it may therefore be promising to reduce the inter-fractional motion of the prostate.

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Evaluation of changes in the size and location of the prostate, seminal vesicles, bladder, and rectum during a course of external beam radiation therapy

Cited by 384 publications

References 11 publications

Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation

Dosimetric and volumetric changes in the rectum and bladder in patients receiving CBCT‐guided prostate IMRT: analysis based on daily CBCT dose calculation

Quantitative evaluation of a cone‐beam computed tomography–planning computed tomography deformable image registration method for adaptive radiation therapy

Efficacy of Daily Cone-Beam Computed Tomography as Part of a Rescan Protocol for Large Offset to Reduce the Inter-Fractional Motion of the Prostate

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