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Dose deformation-invariance in adaptive prostate radiation therapy: implication for treatment simulations.

ABSTRACT: PURPOSE:To investigate dose deformation-invariance in adaptive prostate radiation treatment. METHODS:A 19 patient prostate cancer-cohort with 8-13 CTs/patient is used. The 79.2 Gy plans are developed on the reference image using seven 6 and 18 MV intensity-modulated beams with identical RTOG 0126 objectives. Dose on the subsequent images is evaluated in two ways: (A1) Dose is recalculated on each image. (A2) The initially planned dose distribution is copied to each image. A2 assumes dose-invariance in the accelerator-coordinate-system. Effects of patient miss-alignment are simulated by 27 per-patient image shifts; 0 and ±10 mm in left-right, anterior-posterior and superior-inferior directions. The per-voxel dose differences for each patient image, total accumulated patient dose, and dose-volume metrics (CTV-D98 and -D90, bladder- and rectum-D50, -D35, -D25 and -D15) are used to compare A1 and A2. RESULTS:The per-voxel mean percent difference in A1 and A2 dose over all patient images at 6 MV is (0.01±1.56)% and at 18 MV is (0.00±0.96)%. For 6 MV and 18 MV plans, the root-mean-square-percentage-error (RMSPE) in A2 over all patient image shifts are CTV-D98=0.94 and 0.55, CTV-D90=0.92 and 0.55, rectum-D50, -D35, -D25 and -D15=1.00, 0.96, 0.86, 0.80 and 0.84, 0.96, 0.92, 1.05; and bladder-D50, -D35, -D25, -D15=1.07, 0.88, 0.78, 0.72 and 1.61, 0.93, 0.67, 0.51. The dose differences are not correlated to the dice-similarity coefficients; with respective correlation-coefficients for CTV, rectum and bladder being -0.17, -0.17 and 0.081. CONCLUSIONS:Assumption of shift- and deformation-invariant dose distributions on an average introduces <2% error in evaluated dose-volume metrics for 6 and 18 MV IMRT prostate plans. Use of invariant dose distributions has a potential to reduce online re-planning time and permit pre-planning based on tissue deformation models.

SUBMITTER: Sharma M

PROVIDER: S-EPMC6559364 | biostudies-literature | 2012 Nov

REPOSITORIES: biostudies-literature

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Dose deformation-invariance in adaptive prostate radiation therapy: implication for treatment simulations.

Sharma Manju M Weiss Elisabeth E Siebers Jeffrey V JV

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 20121129 2

<h4>Purpose</h4>To investigate dose deformation-invariance in adaptive prostate radiation treatment.<h4>Methods</h4>A 19 patient prostate cancer-cohort with 8-13 CTs/patient is used. The 79.2 Gy plans are developed on the reference image using seven 6 and 18 MV intensity-modulated beams with identical RTOG 0126 objectives. Dose on the subsequent images is evaluated in two ways: (A1) Dose is recalculated on each image. (A2) The initially planned dose distribution is copied to each image. A2 assum ...[more]

PMID: 23200409

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Project description:PurposeThis work aims to study the generalizability of a pre-developed deep learning (DL) dose prediction model for volumetric modulated arc therapy (VMAT) for prostate cancer and to adapt the model, via transfer learning with minimal input data, to three different internal treatment planning styles and one external institution planning style.MethodsWe built the source model with planning data from 108 patients previously treated with VMAT for prostate cancer. For the transfer learning, we selected patient cases planned with three different styles, 14-29 cases per style, in the same institution and 20 cases treated in a different institution to adapt the source model to four target models in total. We compared the dose distributions predicted by the source model and the target models with the corresponding clinical plan dose used for patient treatments and quantified the improvement in the prediction quality for the target models over the source model using the Dice similarity coefficients (DSC) of 0% to 100% isodose volumes and the dose-volume-histogram (DVH) parameters of the planning target volume and the organs-at-risk.ResultsThe source model accurately predicts dose distributions for plans generated in the same source style, but performs sub-optimally for the three different internal and one external target styles, with the mean DSC ranging between 0.81-0.94 and 0.82-0.91 for the internal and the external styles, respectively. With transfer learning, the target model predictions improved the mean DSC to 0.88-0.95 and 0.92-0.96 for the internal and the external styles, respectively. Target model predictions significantly improved the accuracy of the DVH parameter predictions to within 1.6%.ConclusionWe demonstrated the problem of model generalizability for DL-based dose prediction and the feasibility of using transfer learning to solve this problem. With 14-29 cases per style, we successfully adapted the source model into several different practice styles. This indicates a realistic way forward to widespread clinical implementation of DL-based dose prediction.

Project description:BackgroundTo evaluate acute and late genitourinary and gastrointestinal toxicities and patient reported urinary and sexual function following accelerated, hypofractionated external beam radiotherapy to the prostate, seminal vesicles and pelvic lymph nodes and high dose rate (HDR) brachytherapy or stereotactic body radiation therapy (SBRT) prostate boost.MethodsPatients at a single institution with NCCN intermediate- and high-risk localized prostate cancer with logistical barriers to completing five weeks of whole pelvic radiotherapy (WPRT) were retrospectively reviewed for toxicity following accelerated, hypofractionated WPRT (41.25 Gy in 15 fractions of 2.75 Gy). Patients also received prostate boost radiotherapy with either HDR brachytherapy (1 fraction of 15 Gy) or SBRT (19 Gy in 2 fractions of 9.5 Gy). The duration of androgen deprivation therapy was at the discretion of the treating radiation oncologist. Toxicity was evaluated by NCI CTCAE v 5.0.ResultsBetween 2015 and 2017, 22 patients with a median age of 71 years completed accelerated, hypofractionated WPRT. Median follow-up from the end of radiotherapy was 32 months (range 2-57). 5%, 73%, and 23% of patients had clinical T1, T2, and T3 disease, respectively. 86% of tumors were Gleason grade 7 and 14% were Gleason grade 9. 68% and 32% of patients had NCCN intermediate- and high-risk disease, respectively. 91% and 9% of patients received HDR brachytherapy and SBRT prostate boost following WPRT, respectively. Crude rates of grade 2 or higher GI and GU toxicities were 23% and 23%, respectively. 3 patients (14%) had late or persistent grade 2 toxicities of urinary frequency and 1 patient (5%) had late or persistent GI toxicity of diarrhea. No patient experienced grade 3 or higher toxicity at any time. No difference in patient-reported urinary or sexual function was noted at 12 months.ConclusionsAccelerated, hypofractionated whole pelvis radiotherapy was associated with acceptable GU and GI toxicities and should be further validated for those at risk for harboring occult nodal disease.

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Dataset Information

Dose deformation-invariance in adaptive prostate radiation therapy: implication for treatment simulations.

Publications

Dose deformation-invariance in adaptive prostate radiation therapy: implication for treatment simulations.

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