Target volume changes through high-dose-rate brachytherapy for cervical cancer when evaluated on high resolution (3.0 Tesla) magnetic resonance imaging

Sun, Wenqing; Bhatia, Sudershan K.; Jacobson, Geraldine M.; Flynn, R; Kim, Yusung

doi:10.1016/j.prro.2012.03.012

Cited by 10 publications

(8 citation statements)

References 27 publications

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“…Orthogonal radiographs using a C-arm were taken before and after each MRI scan (Pre- and Post-X-ray). The institutional protocols for external beam radiotherapy and HDR BT fractionation schemes were detailed in previous studies [ 7 , 20 – 22 ]. High-risk clinical target volumes (HR-CTV), of the rectum, bladder, and sigmoid were retrospectively delineated as per GEC-ESTRO recommendations [ 2 , 3 ].…”

Section: Methodsmentioning

confidence: 99%

Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer

Schindel¹,

Zhang²,

Bhatia

et al. 2013

jcb

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PurposeTo quantify the dosimetric impact of applicator displacements and applicator reconstruction-uncertainties through simulated planning studies of virtual applicator shifts.Material and methodsTwenty randomly selected high-dose-rate (HDR) titanium tandem-and-ovoid (T&O) plans were retrospectively studied. MRI-guided, conformal brachytherapy (MRIG-CBT) plans were retrospectively generated. To simulate T&O displacement, the whole T&O set was virtually shifted on treatment planning system in the cranial (+) and the caudal (–) direction after each dose calculation. Each shifted plan was compared to an unshifted plan. To simulate T&O reconstruction-uncertainties, each tandem and ovoid was separately shifted along its axis before performing the dose calculation. After the dose calculation, the calculated isodose lines and T&O were moved back to unshifted T&O position. Shifted and shifted-back plan were compared.ResultsRegarding the dosimetric impact of the simulated T&O displacements, rectal D2cc values were observed as being the most sensitive to change due to T&O displacement among all dosimetric metrics regardless of point A (p < 0.013) or MRIG-CBT plans (p < 0.0277). To avoid more than 10% change, ± 1.5 mm T&O displacements were accommodated for both point A and MRIG-CBT plans. The dosimetric impact of T&O displacements on sigmoid (p < 0.0005), bladder (p < 0.0001), HR-CTV (p < 0.0036), and point A (p < 0.0015) were significantly larger in the MRIG-CBT plans than point A plans. Regarding the dosimetric impact of T&O reconstruction-uncertainties, less than ± 3.0 mm reconstruction-uncertainties were also required in order to avoid more than 10% dosimetric change in either the point A or MRIG-CBT plans.ConclusionsThe dosimetric impact of simulated T&O displacements was significantly larger in the MRIG-CBT plans than in the point A plans. Either ± 3 mm T&O displacement or a ± 4.5 mm T&O reconstruction-uncertainty could cause greater than 10% dosimetric change for both point A plans and MRIG-CBT plans.

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Section: Methodsmentioning

confidence: 99%

Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer

Schindel¹,

Zhang²,

Bhatia

et al. 2013

jcb

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“…A T&O applicator was reconstructed (digitized) on T1‐weighted MR images 6. The details of the HDR workflow, imaging, and planning have been previously described 21, 22, 23, 24…”

Section: Methodsmentioning

confidence: 99%

“…6 The details of the HDR workflow, imaging, and planning have been previously described. [21][22][23][24] An adaptive/conformal volume optimization HDR plan was retrospectively created for each clinical Point A plan through a hybrid-inverse optimization process that includes a combination of an inverse optimization and manual forward planning. The hybridinverse optimization process 21,22,25,26 5,7 and the ICRU Report #89.…”

Section: A | Ebrt and 3t Mri-guided Adaptive/conformal Volume Optimentioning

confidence: 99%

Patient's specific integration of OAR doses (D2 cc) from EBRT and 3D image‐guided brachytherapy for cervical cancer

Gelover

Katherine

Mart

et al. 2018

J Applied Clin Med Phys

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The objective of this study was to assess the recommended DVH parameter (e.g., D2 cc) addition method used for combining EBRT and HDR plans, against a reference dataset generated from an EQD2‐based DVH addition method. A revised DVH parameter addition method using EBRT DVH parameters derived from each patient's plan was proposed and also compared with the reference dataset. Thirty‐one biopsy‐proven cervical cancer patients who received EBRT and HDR brachytherapy were retrospectively analyzed. A parametrial and/or paraaortic EBRT boost were clinically performed on 13 patients. Ten IMRT and 21 3DCRT plans were determined. Two different HDR techniques for each HDR plan were analyzed. Overall D2 cc and D0.1 cc OAR doses in EQD2 were statistically analyzed for three different DVH parameter addition methods: a currently recommended method, a proposed revised method, and a reference DVH addition method. The overall D2 ccEQD 2 values for all rectum, bladder, and sigmoid for a conformal, volume optimization HDR plan generated using the current DVH parameter addition method were significantly underestimated on average −5 to −8% when compared to the values obtained from the reference DVH addition technique (P < 0.01). The revised DVH parameter addition method did not present statistical differences with the reference technique (P > 0.099). When PM boosts were considered, there was an even greater average underestimation of −8~−10% for overall OAR doses of conformal HDR plans when using the current DVH parameter addition technique as compared to the revised DVH parameter addition. No statistically significant differences were found between the 3DCRT and IMRT techniques (P > 0.3148). It is recommended that the overall D2 cc EBRT doses are obtained from each patient's EBRT plan.

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“…Three Tesla (3T) MRI‐guided, titanium T&O HDR BT volume optimization planning is institutional standard care 23 , 24 , 25 , 26 . We validated the artifacts and distortions of titanium in the high 3T magnetic field (23) in order to use the 3T MRI as a single planning imaging modality for MRI‐guided GYN BT.…”

Section: Methodsmentioning

confidence: 99%

Commissioning of a 3D image‐based treatment planning system for high‐dose‐rate brachytherapy of cervical cancer

Kim

Modrick

Pennington

et al. 2016

J Applied Clin Med Phys

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The objective of this work is to present commissioning procedures to clinically implement a three‐dimensional (3D), image‐based, treatment‐planning system (TPS) for high‐dose‐rate (HDR) brachytherapy (BT) for gynecological (GYN) cancer. The physical dimensions of the GYN applicators and their values in the virtual applicator library were varied by 0.4 mm of their nominal values. Reconstruction uncertainties of the titanium tandem and ovoids (T&O) were less than 0.4 mm on CT phantom studies and on average between 0.8‐1.0 mm on MRI when compared with X‐rays. In‐house software, HDRCalculator, was developed to check HDR plan parameters such as independently verifying active tandem or cylinder probe length and ovoid or cylinder size, source calibration and treatment date, and differences between average Point A dose and prescription dose. Dose‐volume histograms were validated using another independent TPS. Comprehensive procedures to commission volume optimization algorithms and process in 3D image‐based planning were presented. For the difference between line and volume optimizations, the average absolute differences as a percentage were 1.4% for total reference air KERMA (TRAK) and 1.1% for Point A dose. Volume optimization consistency tests between versions resulted in average absolute differences in 0.2% for TRAK and 0.9 s (0.2%) for total treatment time. The data revealed that the optimizer should run for at least 1 min in order to avoid more than 0.6% dwell time changes. For clinical GYN T&O cases, three different volume optimization techniques (graphical optimization, pure inverse planning, and hybrid inverse optimization) were investigated by comparing them against a conventional Point A technique. End‐to‐end testing was performed using a T&O phantom to ensure no errors or inconsistencies occurred from imaging through to planning and delivery. The proposed commissioning procedures provide a clinically safe implementation technique for 3D image‐based TPS for HDR BT for GYN cancer.PACS number(s): 87.55.D‐

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Target volume changes through high-dose-rate brachytherapy for cervical cancer when evaluated on high resolution (3.0 Tesla) magnetic resonance imaging

Cited by 10 publications

References 27 publications

Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer

Dosimetric impacts of applicator displacements and applicator reconstruction-uncertainties on 3D image-guided brachytherapy for cervical cancer

Patient's specific integration of OAR doses (D2 cc) from EBRT and 3D image‐guided brachytherapy for cervical cancer

Commissioning of a 3D image‐based treatment planning system for high‐dose‐rate brachytherapy of cervical cancer

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