Design of 4D treatment planning target volumes

Rietzel, Eike; Liu, Arthur K.; Doppke, Karen P.; Wolfgang, John A.; Chen, Aileen B.; Chen, George T.Y.; Choi, Noah C.

doi:10.1016/j.ijrobp.2006.05.024

Cited by 168 publications

(114 citation statements)

References 37 publications

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“…That is to say,

{CTV}_{3 D}

centroids randomly scatter around the center of

{PTV}_{4 D}

. Our study in liver cancer was in agreement with the study in lung caner reported by other authors 5 , 25 . Therefore, the margin accounting for tumor motion should be isotropic in a single direction for 3D CT treatment planning.…”

Section: Discussionsupporting

confidence: 91%

“…The use of 4D CT scanning is not only able to determine the intrafractional tumor motion, 6 , 8 but also to eliminate respiration motion artifacts 9 , 11 . Moreover, the size of PTVs of lung cancers can be reduced using the technique of 4D CT compared with the technique of 3D CT 5 , 12 , 13 . This is particularly important in the radiotherapy of liver cancer, yet there are only a few reports on this field 14 , 16 …”

Section: Introductionmentioning

confidence: 99%

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Analysis of the advantage of individual PTVs defined on axial 3D CT and 4D CT images for liver cancer

Xing

et al. 2012

J Applied Clin Med Phys

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The purpose of this study was to compare positional and volumetric differences of planning target volumes (PTVs) defined on axial three dimensional CT (3D CT) and four dimensional CT (4D CT) for liver cancer. Fourteen patients with liver cancer underwent 3D CT and 4D CT simulation scans during free breathing. The tumor motion was measured by 4D CT. Three internal target volumes (ITVs) were produced based on the clinical target volume from 3DCT (CTV3D): i) A conventional ITV (ITVconv) was produced by adding 10 mm in CC direction and 5 mm in LR and and AP directions to CTV3D; ii) A specific ITV (ITVspec) was created using a specific margin in transaxial direction; iii) ITVvector was produced by adding an isotropic margin derived from the individual tumor motion vector. ITV4D was defined on the fusion of CTVs on all phases of 4D CT. PTVs were generated by adding a 5 mm setup margin to ITVs. The average centroid shifts between PTVs derived from 3DCT and PTV4D in left–right (LR), anterior–posterior (AP), and cranial–caudal (CC) directions were close to zero. Comparing PTV4D to PTVconv, PTVspec, and PTVvector resulted in a decrease in volume size by 33.18% ±12.39%, 24.95% ±13.01%, 48.08% ±15.32%, respectively. The mean degree of inclusions (DI) of PTV4D in PTVconv, and PTV4D in PTVspec, and PTV4D in PTVvector was 0.98, 0.97, and 0.99, which showed no significant correlation to tumor motion vector (r=‐0.470, 0.259, and 0.244; p=0.090, 0.371, and 0.401). The mean DIs of PTVconv in PTV4D, PTVspec in PTV4D, and PTVvector in PTV4D was 0.66, 0.73, and 0.52. The size of individual PTV from 4D CT is significantly less than that of PTVs from 3DCT. The position of targets derived from axial 3DCT images scatters around the center of 4D targets randomly. Compared to conventional PTV, the use of 3D CT‐based PTVs with individual margins cannot significantly reduce normal tissues being unnecessarily irradiated, but may contribute to reducing the risk of missing targets for tumors with large motion.PACS number: 87

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“…That is to say,

{CTV}_{3 D}

centroids randomly scatter around the center of

{PTV}_{4 D}

Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Analysis of the advantage of individual PTVs defined on axial 3D CT and 4D CT images for liver cancer

Xing

et al. 2012

J Applied Clin Med Phys

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“…An internal target volume (ITV) was defined in accordance with an established target volume concept 22 , 23 as the intersection of GTV volumes at the extreme phases (end‐inspiration and end‐expiration) with no expansion for the CTV margin. A 5 mm margin was added for generation of the planning target volume (PTV).…”

Section: Methodsmentioning

confidence: 99%

Evaluation of dosimetric misrepresentations from 3D conventional planning of liver SBRT using 4D deformable dose integration

Yeo

Taylor

Supple

et al. 2014

J Applied Clin Med Phys

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The purpose of this study is to evaluate dosimetric errors in 3D conventional planning of stereotactic body radiotherapy (SBRT) by using a 4D deformable image registration (DIR)‐based dose‐warping and integration technique. Respiratory‐correlated 4D CT image sets with 10 phases were acquired for four consecutive patients with five liver tumors. Average intensity projection (AIP) images were used to generate 3D conventional plans of SBRT. Quasi‐4D path‐integrated dose accumulation was performed over all 10 phases using dose‐warping techniques based on DIR. This result was compared to the conventional plan in order to evaluate the appropriateness of 3D (static) dose calculations. In addition, we consider whether organ dose metrics derived from contours defined on the average intensity projection (AIP), or on a reference phase, provide the better approximation of the 4D values. The impact of using fewer (<10) phases was also explored. The AIP‐based 3D planning approach overestimated doses to targets by 1.4% to 8.7% (mean 4.2%) and underestimated dose to normal liver by up to 8% (mean −5.5%; range −2.3% to −8.0%), compared to the 4D methodology. The homogeneity of the dose distribution was overestimated when using conventional 3D calculations by up to 24%. OAR doses estimated by 3D planning were, on average, within 10% of the 4D calculations; however, differences of up to 100% were observed. Four‐dimensional dose calculation using 3 phases gave a reasonable approximation of that calculated from the full 10 phases for all patients, which is potentially useful from a workload perspective. 4D evaluation showed that conventional 3D planning on an AIP can significantly overestimate target dose (ITV and GTV+5mm), underestimate normal liver dose, and overestimate dose homogeneity. Implementing nonadaptive quasi‐4D dose calculation can highlight the potential limitation of 3D conventional SBRT planning and the resultant misrepresentations of dose in some regions affected by motion and deformation. Where the 4D approach is unavailable, contouring on the full expiration phase may yield more accurate dose calculations, most relevant in the case of the healthy liver, but the absolute dose differences are in general small for the other healthy organs. The technique has the potential to quantify under‐ and over‐dosage and improve treatment plan evaluation, retrospective plan analysis, and clinical outcome correlation.PACS numbers: 87.55.‐x, 87.55.D‐, 87.55.de, 87.55.dk, 87.55.Qr, 87.57.nj

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“…While ICRU report 78 introduced range incorporation margins added to CTV, however, it is not clearly stated how to use it for intrafractional moving target. 15 The maximum intensity volume and average intensity projection approaches have been used in passive particle beam irradiation 16,17 and are utilized by a commercial TPS for treatment beam delivery to a moving target. Because these methods may result in expansion of the smeared beam field and density regions, however, and subsequent overdosage to normal tissue regions, their use in calculating intrafractional range variation has not been fully investigated.…”

Section: Field-specific Target Volume Calculationmentioning

confidence: 99%

Implementation of a target volume design function for intrafractional range variation in a particle beam treatment planning system

Mori¹,

Inaniwa²,

Miki³

et al. 2014

BJR

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Objective: Treatment planning for charged particle therapy in the thoracic and abdominal regions should take account of range uncertainty due to intrafractional motion. Here, we developed a design tool (4Dtool) for the target volume [field-specific target volume (FTV)], which accounts for this uncertainty using four-dimensional CT (4DCT). Methods: Target and normal tissue contours were input manually into a treatment planning system (TPS). These data were transferred to the 4Dtool via the picture archiving and communication system (PACS). Contours at the reference phase were propagated to other phases by deformable image registration. FTV was calculated using 4DCT on the 4Dtool. The TPS displays FTV contours using digital imaging and communications in medicine files imported from the PACS. These treatment parameters on the CT image at the reference phase were then used for dose calculation on the TPS. The tool was tested in single clinical case randomly selected from patients treated at our centre for lung cancer. Results: In this clinical case, calculation of dose distribution with the 4Dtool resulted in the successful delivery of carbon-ion beam at the reference phase of 95% of the prescribed dose to the clinical target volume (CTV). Application to the other phases also provided sufficient dose to the CTV. Conclusion: The 4Dtool software allows the design of the target volume with consideration to intrafractional range variation and is now in routine clinical use at our institution. Advances in knowledge: Our alternative technique represents a practical approach to four-dimensional treatment planning within the current state of charged particle therapy.Our centre treats .700 patients per year by passive carbonion beam irradiation therapy, conducted over 4 days per week. Carbon-ion scanning beam treatment without respiratory gating was successfully implemented in 2011.

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Design of 4D treatment planning target volumes

Cited by 168 publications

References 37 publications

Analysis of the advantage of individual PTVs defined on axial 3D CT and 4D CT images for liver cancer

Analysis of the advantage of individual PTVs defined on axial 3D CT and 4D CT images for liver cancer

Evaluation of dosimetric misrepresentations from 3D conventional planning of liver SBRT using 4D deformable dose integration

Implementation of a target volume design function for intrafractional range variation in a particle beam treatment planning system

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