Formulating adaptive radiation therapy (ART) treatment planning into a closed-loop control framework

Zerda, Adam de la; Armbruster, Benjamin; Li, Xing

doi:10.1088/0031-9155/52/14/008

Cited by 80 publications

(38 citation statements)

References 38 publications

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“…An alternative to the hybrid method proposed in this study is the online adaptive planning (de la Zerda et al 2007). One assumption in that paper and many others on the topic is that target contours were available online.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

Liu¹,

Wu²

2011

Phys. Med. Biol.

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For prostate cancer patients, online image-guided (IG) radiotherapy has been widely used in clinic to correct the translational inter-fractional motion at each treatment fraction. For uncertainties that cannot be corrected online, such as rotation and deformation of the target volume, margins are still required to be added to the clinical target volume (CTV) for the treatment planning. Offline adaptive radiotherapy has been implemented to optimize the treatment for each individual patient based on the measurements at early stages of treatment process. It has been shown that offline adaptive radiotherapy can effectively reduce the required margin. Recently a hybrid strategy of offline adaptive replanning and online IG was proposed and the geometric evaluation was performed. It was found that the planning margins can be further reduced by 1–2 mm compared to online IG only strategy. The purpose of this study was to investigate the dosimetric benefits of such hybrid strategy on the target and organs at risk (OARs). A total of 420 repeated helical computed tomography (HCT) scans from 28 patients were included in the study. Both low-risk patients (LRP, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles, SV) were included in the simulation. Two registration methods, based on center-of-mass (COM) shift of prostate only and prostate plus SV, were performed for IRP. The intensity modulated radiotherapy (IMRT) was used in the simulation. Criteria on both cumulative dose and fractional doses were evaluated. Furthermore, the geometric evaluation was extended to investigate the optimal number of fractions necessary to construct the internal target volume (ITV) for the hybrid strategy. The dosimetric margin improvement was smaller than its geometric counterpart and was in the range of 0 mm to 1 mm. The optimal number of fractions necessary for the ITV construction is 2 for LRP and 3–4 for IRP in a hypofractionation protocol. A new cumulative index of target volume (CITV) was proposed for the evaluation of adaptive radiotherapy strategies, and it was found that it had the advantages over other indices in evaluating different adaptive radiotherapy strategies.

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Section: Discussionmentioning

confidence: 99%

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

Liu¹,

Wu²

2011

Phys. Med. Biol.

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“…The IGART framework consists of a closed-loop system that incorporates feedback from the updated patient geometry and anatomical information in order to recompute dose and determine the actual dose delivered to the target and surrounding healthy tissues. While similar concepts have been proposed previously (Yan et al 1997, de la Zerda et al 2007), our approach includes a systematic validation of the DIR algorithm and dose accumulation techniques, as well as a novel method, based on unbalanced energy (UE), for the verification of the DIR accuracy. Moreover, we have applied our IGART framework to a patient planning study and have performed thorough evaluation of the delivered dose distributions using standard dose metrics as well as radiobiological dose indices.…”

Section: Methodsmentioning

confidence: 99%

Evaluation of the deformation and corresponding dosimetric implications in prostate cancer treatment

Wen¹,

Glide-Hurst²,

Nurushev³

et al. 2012

Phys. Med. Biol.

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The cone-beam computed tomography (CBCT) imaging modality is an integral component of image-guided adaptive radiation therapy (IGART), which uses patient-specific dynamic/temporal information for potential treatment plan modification. In this study, an offline process for the integral component IGART framework has been implemented that consists of deformable image registration (DIR) and its validation, dose reconstruction, dose accumulation and dose verification. This study compares the differences between planned and estimated delivered doses under an IGART framework of five patients undergoing prostate cancer radiation therapy. The dose calculation accuracy on CBCT was verified by measurements made in a Rando pelvic phantom. The accuracy of DIR on patient image sets was evaluated in three ways: landmark matching with fiducial markers, visual image evaluation and unbalanced energy (UE); UE has been previously demonstrated to be a feasible method for the validation of DIR accuracy at a voxel level. The dose calculated on each CBCT image set was reconstructed and accumulated over all fractions to reflect the ‘actual dose’ delivered to the patient. The deformably accumulated (delivered) plans were then compared to the original (static) plans to evaluate tumor and normal tissue dose discrepancies. The results support the utility of adaptive planning, which can be used to fully elucidate the dosimetric impact based on the simulated delivered dose to achieve the desired tumor control and normal tissue sparing, which may be of particular importance in the context of hypofractionated radiotherapy regimens.

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“…According to the routine adaptive radiotherapy (ART) strategy,9, 10 a repeat imaging scan to check whether it needs a re‐planning is implemented 2.5–3 weeks after the beginning of the treatment, whereas the time interval between the planning CT (pCT) and the repeat CT is too long to timely prevent the radiation overdose to the normal liver. Stewart et al reported that the dose accumulation over weekly repeat magnetic resonance imaging (MRI) scans could be used to cope with the motion of the organ and tumor regression.…”

Section: Introductionmentioning

confidence: 99%

Investigation of dosimetric variations of liver radiotherapy using deformable registration of planning CT and cone‐beam CT

Huang

Chen

et al. 2016

J Applied Clin Med Phys

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Many patients with technically unresectable or medically inoperable hepatocellular carcinoma (HCC) had hepatic anatomy variations as a result of interfraction deformation during fractionated radiotherapy. We conducted this retrospective study to investigate interfractional normal liver dosimetric consequences via reconstructing weekly dose in HCC patients. Twenty‐three patients with HCC received conventional fractionated three‐dimensional conformal radiation therapy (3DCRT) were enrolled in this retrospective investigation. Among them, seven patients had been diagnosed of radiation‐induced liver disease (RILD) and the other 16 patients had good prognosis after treatment course. The cone‐beam CT (CBCT) scans were acquired once weekly for each patient throughout the treatment, deformable image registration (DIR) of planning CT (pCT) and CBCT was performed to acquire modified CBCT (mCBCT), and the structural contours were propagated by the DIR. The same plan was applied to mCBCT to perform dose calculation. Weekly dose distribution was displayed on the pCT dose space and compared using dose difference, target coverage, and dose volume histograms. Statistical analysis was performed to identify the significant dosimetric variations. Among the 23 patients, the three weekly normal liver D50 increased by 0.2 Gy, 4.2 Gy, and 4.7 Gy, respectively, for patients with RILD, and 1.0 Gy, 2.7 Gy, and 3.1 Gy, respectively, for patients without RILD. Mean dose to the normal liver (Dmean) increased by 0.5 Gy, 2.6 Gy, and 4.0 Gy, respectively, for patients with RILD, and 0.4 Gy, 3.1 Gy, and 3.4 Gy, respectively, for patients without RILD. Regarding patients with RILD, the average values of the third weekly D50 and Dmean were both over hepatic radiation tolerance, while the values of patients without RILD were below. The dosimetric consequence showed that the liver dose between patients with and without RILD were different relative to the planned dose, and the RILD patients suffered from liver dose over hepatic radiation tolerance. Evaluation of routinely acquired CBCT images during radiation therapy provides biological information on the organs at risk, and dose estimation based on mCBCT could potentially form the basis for personalized response adaptive therapy.

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Formulating adaptive radiation therapy (ART) treatment planning into a closed-loop control framework

Cited by 80 publications

References 38 publications

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

Dosimetric and geometric evaluation of a hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

Evaluation of the deformation and corresponding dosimetric implications in prostate cancer treatment

Investigation of dosimetric variations of liver radiotherapy using deformable registration of planning CT and cone‐beam CT

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