Translational and rotational localization errors in cone-beam CT based image-guided lung stereotactic radiotherapy

Garibaldi, Cristina; Piperno, Gaia; Ferrari, Annamaria; Surgo, A.; Muto, Matteo; Ronchi, Sara; Bazani, A.; Pansini, F.; Cremonesi, Marta; Jereczek‐Fossa, Barbara Alicja; Orecchia, Roberto

doi:10.1016/j.ejmp.2016.05.055

Cited by 28 publications

(24 citation statements)

References 32 publications

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“…In current clinical practice, translational errors can be corrected online since they are easily implemented using couch shifts along three axes. Rotational setup differences between the patient's position in the linac and the CT scanning position can be corrected using advanced couches that have six degrees of freedom . While the use of such couches is increasingly prevalent, there are still many linacs with conventional couches that cannot correct for pitch, roll, or yaw.…”

Section: Introductionmentioning

confidence: 99%

A study of nonuniform CTV to PTV margin expansion incorporating both rotational and translational uncertainties

Miao

Tian

et al. 2019

J Applied Clin Med Phys

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PurposeIn this work, we implemented a method to obtain a nonuniform clinical target volume (CTV) to planning target volume (PTV) margin caused by both rotational and translational uncertainties and evaluated it in the treatment planning system (TPS).Materials and methodBased on a previously published statistical model, the relationship between a target margin and the distance d (from isocenter to target point), setup uncertainties, and significance level was established. For a single CTV, it can be thought as a combination of many small volume elements or target points. The margin of each point could be obtained using the suggested statistical model. The whole nonuniform CTV–PTV margin was determined by the union of all possible margins of the CTV boundary points. This method was implemented in the Pinnacle3 treatment planning system and compared with uniform margin algorithm. Ten vertebral metastases targets and multiple brain metastases targets were chosen for evaluation.ResultsThe combined CTV–PTV margin as a function of d for various initial translational margin and rotational uncertainties was calculated. The combined margin increases as d, rotational uncertainties and translational margin increase. For the same rotational uncertainty, a smaller initial translational margin requires a larger rotational margin to compensate for the rotational error. Compared with the uniform margin algorithm, the advantage of this method is that it could minimize the PTVs volume for given CTVs to obtain same significance level. Using vertebral metastases targets and multiple brain metastases targets, a series of volume difference was obtained for various translational margins and rotational uncertainties. The volume difference of PTV could be more than 17% when translational margin is 2 mm and rotational uncertainty is 1.4°.ConclusionNonuniform margin algorithm could avoid excessive compensation for the CTV boundary points near isocenter. This method could be used for clinical margin determination and might be useful for the protection of risk organs.

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Section: Introductionmentioning

confidence: 99%

A study of nonuniform CTV to PTV margin expansion incorporating both rotational and translational uncertainties

Miao

Tian

et al. 2019

J Applied Clin Med Phys

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“…Due to the factors such as respiratory, body weight, skin traction, arm lift, etc, the repeatability of whole‐treatment process is poor 4. There are a variety of factors influencing the setup errors in radiation therapy for patients with thoracic tumors 5, 6, 7. In order to reduce these setup errors, many researchers tried to improve setup accuracy by improving the fixation of patients 8, 9, 10.…”

Section: Introductionmentioning

confidence: 99%

Setup errors in radiation therapy for thoracic tumor patients of different body mass index

Zhao

Zhang

Zhai

et al. 2018

J Applied Clin Med Phys

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PurposeTo assess the setup errors in radiation therapy for thoracic tumors patients of different somatotypes, and to seek an individualized mathematical basis for defining the planning target volume (PTV).MethodsSixty patients with thoracic tumors were divided into four somatotypes according to their body mass index (BMI), and their body positions were setup by two groups of technicians independently. CT simulations were performed and the reconstructed radiography was digitally generated as reference images for location verification and error measurement. By setting positioning error ranges, the within‐range positioning correction rate was compared among groups.ResultsPosition setups for patients in the emaciated group, moderate group, and overweight group were relatively stable (with minor setup error differences between the two groups of technicians). In emaciated group, moderate group, overweight group, and obese group, setup errors in the right–left direction (R‐L) were 2.2 ± 1.3 mm, 2.2 ± 1.6 mm, 3.9 ± 3.1 mm, and 8.8 ± 3.5 mm, respectively; whereas the setup errors in the four groups in the superior–inferior(S‐I) direction were 2.4 ± 1.8 mm, 2.1 ± 1.9 mm, 3.2 ± 2.6 mm, and 5.4 ± 3.5 mm, and in the anterior–posterior (A‐P) direction were 2.2 ± 1.7 mm, 1.9 ± 1.9 mm, 3.2 ± 2.9 mm, and 6.2 ± 4.2 mm, respectively. Moreover, in the moderate group, the positioning correction rate in the three directions (R‐L, S‐I, and A‐P) was 20%, 9%, 8% within the error range of 5–10 mm, and 3%, 0%, 1% with a more than 10 mm error range. However, in overweight group and obese group, the positioning correction rate in these three directions (also with a more than 10 mm error range) was 23%, 27%, 19% and 21%, 16%, 23%, respectively.ConclusionsIn radiation therapy for patients with thoracic tumors, the definition of PTV should be individualized. Meanwhile, with the increase in BMI, positioning correction rate has a tendency to rise too.

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“…including the systematic and random setup errors for patient positioning with CBCT (R setup ¼ r setup ¼ 0:8 mm 49 ), uncertainties due to baseline shifts over the course of treatment (R BL ¼ 0:99 mm and r BL ¼ 1:08 mm 50 ), delineation uncertainties (R del ¼ 1:7 mm 47 ), the standard deviation of the breathing motion of the GTV in direction d (r br;d ) and the Gaussian beam penumbra width in lung (r p ¼ 6:4 mm 16 ). The approximation r br;d ¼ A d cen =3 was used, where A d cen is the median motion amplitude of the GTV centroid on the reference day in SI, AP and LR direction.…”

Section: C5 Ptv Formationmentioning

confidence: 99%

Real‐time 4DMRI‐based internal target volume definition for moving lung tumors

et al. 2020

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PTVs were smaller than the ITV-based PTVs. While the SE was high for patients with small breathing pattern variations, changes of the median breathing amplitudes in different imaging sessions led to inferior SE values for the mid-ventilation PTV for one patient. In contrast, PTV 5% r and PTV 10% r showed higher SE values with a higher robustness against interfractional changes, at the cost of larger target volumes. Conclusions:The results indicate that rt-4DMRI could be valuable for the definition of target volumes based on the GTV POP to achieve a higher robustness against interfractional changes than feasible with today's 4D-CT-based target definition concepts.

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Translational and rotational localization errors in cone-beam CT based image-guided lung stereotactic radiotherapy

Cited by 28 publications

References 32 publications

A study of nonuniform CTV to PTV margin expansion incorporating both rotational and translational uncertainties

A study of nonuniform CTV to PTV margin expansion incorporating both rotational and translational uncertainties

Setup errors in radiation therapy for thoracic tumor patients of different body mass index

Real‐time 4DMRI‐based internal target volume definition for moving lung tumors

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