Assessment of Parotid Gland Dose Changes During Head and Neck Cancer Radiotherapy Using Daily Megavoltage Computed Tomography and Deformable Image Registration

Lee, Choonik; Langen, K; Lu, Weiguo; Haimerl, Jason; Schnarr, Eric; Ruchala, K; Olivera, G.; Meeks, Sanford L.; Kupelian, Patrick A.; Shellenberger, Thomas D.; Mañon, R.

doi:10.1016/j.ijrobp.2008.04.013

Cited by 184 publications

(169 citation statements)

References 26 publications

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“…Despite the limited number of patients entered in our study (16), an important part of our results were nevertheless statistically significant. Furthermore, our sample size is also larger than most used in published works related to this topic — for example, studies carried out by Barker et al, (8) Hansen et al, (16) Robar et al, (13) Lee et al, 11 , 15 and Castadot et al (9) included 14, 13, 15, 10, and 10 patients, respectively. Taking into account all of the above factors, the average data shown in Tables 3and 4 could therefore help to identify dosimetric variables at risk of suffering changes during patient radiation treatment.…”

Section: Discussionmentioning

confidence: 99%

“…Several scheduled rescanning studies have evaluated these volumetric changes in both target volumes and normal tissues, 8 , 11 mostly on the parotid glands and their consequent effects on dose distribution 12 , 15 . The information obtained from these studies indicates that anatomical changes during the treatment can cause deviations between the planned and delivered dose, specifically reducing dosage to target volumes whilst increasing dosage to critical structures.…”

Section: Introductionmentioning

confidence: 99%

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Dose variations in tumor volumes and organs at risk during IMRT for head‐and‐neck cancer

Beltran

Ramos

Rovira

et al. 2012

J Applied Clin Med Phys

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Many head‐and‐neck cancer (HNC) patients treated with radiotherapy suffer significant anatomical changes due to tumor shrinkage or weight loss. The purpose of this study was to assess dose changes over target volumes and organs at risk during intensity‐modulated radiotherapy for HNC patients. Sixteen HNC IMRT patients, all requiring bilateral neck irradiation, were enrolled in the study. A CTplan was performed and the initial dose distribution was calculated. During the treatment, two subsequent CTs at the 15th (CT15) and 25th (CT25) fractions were acquired. The initial plan was calculated on the CT15 and CT25, and dose‐volume differences related to the CTplan were assessed. For target volumes, mean values of nearmaximun absorbed dose (normalD2%) increased at the 25th fraction, and doses covering 95% and 98% of volume decreased significantly at the 15th fraction. Contralateral and ipsilateral parotid gland mean doses increased by 6.1% (range: ‐5.4, 23.5%) and 4.7% (range: ‐9.1, 22.3%), respectively, at CT25. The normalD2% in the spinal cord increased by 1.8 Gy at CT15. Mean absorbed dose increases at CT15 and CT25 were observed in: the lips, 3.8% and 5.3%; the oral cavity, 3.5% and 2.5%; and lower middle neck structure, 1.9% and 1.6%. Anatomical changes during treatment of HNC patients affect dose distribution and induce a loss of dose coverage to target volumes and an overdosage to critical structures. Appropriate organs at risk have to be contoured and monitored in order to know if the initial plan remains suitable during the course of the treatment. Reported dosimetric data can help to identify patients who could benefit from adaptive radiotherapy.PACS numbers: 87.53.Kn, 87.55.Dk

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dose variations in tumor volumes and organs at risk during IMRT for head‐and‐neck cancer

Beltran

Ramos

Rovira

et al. 2012

J Applied Clin Med Phys

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“…Several investigators have looked for indicators to predict substantial dosimetric change. Although correlations between several parameters (such as weight loss, skin separation, and others) and dose change to target or organ at risk (OAR) were observed,4, 5, 6 no single parameter can be reliably used to decide the time of replanning for patients with head and neck cancer 4. Therefore, decisions on replanning are frequently based on the practical experience of clinicians.…”

Section: Introductionmentioning

confidence: 99%

Feasibility of CBCT‐based dose with a patient‐specific stepwise HU‐to‐density curve to determine time of replanning

Chen

Mutaf

et al. 2017

J Applied Clin Med Phys

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Purpose(a) To investigate the accuracy of cone‐beam computed tomography (CBCT)–derived dose distributions relative to fanbeam–based simulation CT‐derived dose distributions; and (b) to study the feasibility of CBCT dosimetry for guiding the appropriateness of replanning.Methods and materialsImage data corresponding to 40 patients (10 head and neck [HN], 10 lung, 10 pancreas, 10 pelvis) who underwent radiation therapy were randomly selected. Each patient had both intensity‐modulated radiation therapy and volumetric‐modulated arc therapy plans; these 80 plans were subsequently recomputed on the CBCT images using a patient‐specific stepwise curve (Hounsfield units‐to‐density). Planning target volumes (PTVs; D98%, D95%, D2%), mean dose, and V95% were compared between simulation‐CT–derived treatment plans and CBCT‐based plans. Gamma analyses were performed using criterion of 3%/3 mm for three dose zones (>90%, 70%~90%, and 30%~70% of maximum dose). CBCT‐derived doses were then used to evaluate the appropriateness of replanning decisions in 12 additional HN patients whose plans were previously revised during radiation therapy because of anatomic changes; replanning in these cases was guided by the conventional observed source‐to‐skin‐distance change‐derived approach.ResultsFor all disease sites, the difference in PTV mean dose was 0.1% ± 1.1%, D2% was 0.7% ± 0.1%, D95% was 0.2% ± 1.1%, D98% was 0.2% ± 1.0%, and V95% was 0.3% ± 0.8%; For 3D dose comparison, 99.0% ± 1.9%, 97.6% ± 4.4%, and 95.3% ± 6.0% of points passed the 3%/3 mm criterion of gamma analysis in high‐, medium‐, and low‐dose zones, respectively. The CBCT images achieved comparable dose distributions. In the 12 previously replanned 12 HN patients, CBCT‐based dose predicted well changes in PTV D2% (Pearson linear correlation coefficient = 0.93; P < 0.001). If 3% of change is used as the replanning criteria, 7/12 patients could avoid replanning.Conclusions CBCT‐based dose calculations produced accuracy comparable to that of simulation CT. CBCT‐based dosimetry can guide the decision to replan during the course of treatment.

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“…Megavoltage computed tomography (MVCT) images are acquired daily in the helical tomotherapy unit (Tomotherapy Inc., Madison, Wisconsin, USA) with the primary purpose of more accurate target localisation1 and can also be used for daily dose computation 2. The ability to monitor inter‐fractional anatomical variations is a prerequisite to enable plan adjustments which account for discrepancies, changes in target volume and organs at risk.…”

Section: Introductionmentioning

confidence: 99%

“…The ability to monitor inter‐fractional anatomical variations is a prerequisite to enable plan adjustments which account for discrepancies, changes in target volume and organs at risk. As head and neck cancer patients may undergo significant anatomical changes over a 6‐ to 7‐week course of radiation treatment for various reasons, any volume shrinkage near the facial surface is likely to cause migration of the radiation‐sensitive parotid glands towards high‐dose regions 1. This might result in unforeseen changes in delivered dose such as non‐uniform coverage of the target volumes and increased dose to the organs at risk (OAR) 3.…”

Section: Introductionmentioning

confidence: 99%

Accuracy of eight deformable image registration (DIR) methods for tomotherapy megavoltage computed tomography (MVCT) images

Nobnop

Neamin

Chitapanarux

et al. 2017

J of Medical Radiation Sci

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IntroductionThe application of deformable image registration (DIR) to megavoltage computed tomography (MVCT) images benefits adaptive radiotherapy. This study aims to quantify the accuracy of DIR for MVCT images when using different deformation methods assessed in a cubic phantom and nasopharyngeal carcinoma (NPC) patients.MethodsIn the control studies, the DIR accuracy in air‐tissue and tissue‐tissue interface areas was observed using twelve shapes of acrylic and tissue‐equivalent material inserted in the phantom. In the clinical studies, the 1st and 20th fraction MVCT images of seven NPC patients were used to evaluate application of DIR. The eight DIR methods used in the DIRART software varied in (i) transformation framework (asymmetric or symmetric), (ii) DIR registration algorithm (Demons or Optical Flow) and (iii) mapping direction (forward or backward). The accuracy of the methods was compared using an intensity‐based criterion (correlation coefficient, CC) and volume‐based criterion (Dice's similarity coefficient, DSC).ResultsThe asymmetric transformation with Optical Flow showed the best performance for air‐tissue interface areas, with a mean CC and DSC of 0.97 ± 0.03 and 0.79 ± 0.11 respectively. The symmetric transformation with Optical Flow showed good agreement for tissue‐tissue interface areas with a CC of (0.99 ± 0.01) and DSC of (0.89 ± 0.03). The sequences of target domains were significantly different in tissue‐tissue interface areas.ConclusionsThe deformation method and interface area affected the accuracy of DIR. The validation techniques showed satisfactory volume matching of greater than 0.7 with DSC analysis. The methods can yield acceptable results for clinical applications.

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Assessment of Parotid Gland Dose Changes During Head and Neck Cancer Radiotherapy Using Daily Megavoltage Computed Tomography and Deformable Image Registration

Cited by 184 publications

References 26 publications

Dose variations in tumor volumes and organs at risk during IMRT for head‐and‐neck cancer

Dose variations in tumor volumes and organs at risk during IMRT for head‐and‐neck cancer

Feasibility of CBCT‐based dose with a patient‐specific stepwise HU‐to‐density curve to determine time of replanning

Accuracy of eight deformable image registration (DIR) methods for tomotherapy megavoltage computed tomography (MVCT) images

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