Setup Accuracy in Craniospinal Irradiation: Implications for Planning Treatment Volume Margins

Novák, Jakub; Du, D.; Shinde, Ashwin; Li, Richard; Amini, Arya; Chen, Yi Jen; Wong, Jeffrey Y.C.; Han, Chunhui; Neylon, John; Liu, An; Glaser, Scott

doi:10.1016/j.adro.2021.100747

Cited by 5 publications

(6 citation statements)

References 15 publications

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“…During the robust optimization, only ±5 mm longitudinal setup errors were considered; this is because the lateral and vertical errors were accounted for by the PTV margin expanding from CTV. Additionally, the amplitude of setup errors in cranial-spinal direction for CSI usually is < 5 mm after careful setup [21,22].…”

Section: Discussionmentioning

confidence: 99%

Script-Based Automatic Intensity-Modulated Radiotherapy Planning with Robust Optimization for Craniospinal Irradiation: A Retrospective Study

Wang

Zhao

et al. 2022

Preprint

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Background Craniospinal irradiation (CSI) is essential for treating central nervous system malignancies. However, it is very challenging and time-consuming to design a robust treatment plan capable of delivering a uniform dose to the entire treatment volume for standard linear accelerators. This study proposes a script-based automatic planning method with robust optimization for CSI to reduce sensitivity to setup errors and increase planning efficiency. Methods Ten CSI patients with planning target volume (PTV) lengths between 49.8 and 85.0 cm were retrospectively studied. IMRT plans with robust optimization were generated by the automatic planning script. The plans’ sensitivities to positional inaccuracy were evaluated by deliberately shifting the middle beamsets ±5 mm longitudinally. Non-robust optimization plans were also created and compared to the robust ones. The planning time was recorded to evaluate the efficiency of the automatic CSI planning. Results For the ten patients enrolled in the study, homogeneous dose coverage were achieved for both robust and non-robust plans with average conformity index value of 0.827 (±0.028) and 0.841 (±0.023) (p = 0.047), homogeneity index values of 0.076 (±0.014) and 0.078 (±0.027) (p = 0.114), respectively. In robust plans, the variations of D1% and D99% were between -0.17–0.99% and -1.18–0.53% for cranial PTV, and -1.02–7.2% and -4.78–0.31% for spinal PTV, while in non-robust plans, the variations were much more significant with corresponding values of -0.53–8.31% and -5.17–0.57% for cranial PTV, and 0.53–40.14% and -46.06% to -2.01% for spinal PTV. The total planning time of a robust optimization plan was about 9-13 minutes by the automatic planning script. Conclusions The script-based automatic CSI planning with robust optimization could efficiently create a uniform dose coverage for the entire target volume regardless of PTV length, with the advantage of being insensitive to setup errors and standardizing the planning process.

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Section: Discussionmentioning

confidence: 99%

Script-Based Automatic Intensity-Modulated Radiotherapy Planning with Robust Optimization for Craniospinal Irradiation: A Retrospective Study

Wang

Zhao

et al. 2022

Preprint

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“…The shift interval data of each patient and each treatment were combined into the population data, from which a histogram was drawn to evaluate the normality of the distribution. The 90% probability density interval

( {{{\mu}} - 1.65{\mathrm{s}},{{\mu}} + 1.65{\mathrm{s}}} )

of the population data was calculated to determine the minimum intrafraction margin range required for each anatomical layer of the population to have a 90% probability of achieving PTV3 29 …”

Section: Methodsmentioning

confidence: 99%

“…The 90% probability density interval (𝜇 − 1.65s, 𝜇 + 1.65s) of the population data was calculated to determine the minimum intrafraction margin range required for each anatomical layer of the population to have a 90% probability of achieving PTV3. 29 To verify the rationality of the margin of the three PTVs, the margin value in the three directions was compared with the 95% probability density shift interval value recorded in the log file. When the PTV was greater than or equal to the interval, the tumor was considered covered by the PTV; otherwise, it was considered missed.…”

Section: Ptv Margin Analysismentioning

confidence: 99%

SGRT‐based stereotactic body radiotherapy for lung cancer setup accuracy and margin of the PTV

Guo,

Wu,

Huan

et al. 2023

J Applied Clin Med Phys

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ObjectiveSurface‐guided radiation therapy (SGRT, AlignRT) was used to analyze motion during stereotactic body radiotherapy (SBRT) in lung cancer patients and to explore the margin of the planning target volume (PTV).MethodsThe residual errors of the AlignRT were evaluated based on grayscale cone‐beam computed tomography registration results before each treatment. AlignRT log file was used to analyze the correlation between the frequency and longest duration of errors larger than 2 mm and lasting longer than 2 s and maximum error with age and treatment duration. The displacement value at the end of treatment, the average displacement value, and the 95% probability density displacement interval were defined as intrafraction errors, and PTV1, PTV2, PTV3 were calculated by Van Herk formula or Z score analysis. Organ dosimetric differences were compared after the experience‐based margin was replaced with PTV3.ResultsThe interfraction residual errors were Vrt0, 0.06 ± 0.18 cm; Lng0, ‐0.03 ± 0.19 cm; Lat0, 0.02 ± 0.15 cm; Pitch0, 0.23 ± 0.7°; Roll0, 0.1 ± 0.69°; Rtn0, ‐0.02 ± 0.79°. The frequency, longest duration and maximum error in vertical direction were correlated with treatment duration (r = 0.404, 0.353, 0.283, p < 0.05, respectively). In the longitudinal direction, the frequency was correlated with age and treatment duration (r = 0.376, 0.283, p < 0.05, respectively), maximum error was correlated with age (r = 0.4, P < 0.05). Vertical, longitudinal, lateral margins of PTV1, PTV2, PTV3 were 2 mm, 4 mm, 2 mm; 2 mm, 2 mm, 2 mm, 3 mm, 5 mm, 3 mm, respectively. After replacing the original PTV, mean lung dose (MLD), 2‐cm3 chest wall dose (CD), lung V20 decreased by 0.2 Gy, 2.1 Gy, 0.5%, respectively (p < 0.05).ConclusionAlignRT can be used for interfraction setup and monitoring intrafraction motion. It is more reasonable to use upper and lower limits of the 95% probability density interval as an intrafraction error.

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“…However, these benefits of HT-IMRT are generally achieved at the cost of greater volume of normal tissue being irradiated with low doses [9] , [10] . The deleterious effects of radiation therapy are volume-, dose- and age-dependent; resulting from damages to healthy tissues within the irradiated volume [11] , [12] . Although HT reduces the occurrence of acute adverse events, many patients still experience haematological toxicities, particularly if their treatment included chemotherapy before radiation therapy.…”

Section: Introductionmentioning

confidence: 99%

Helical tomotherapy craniospinal irradiation in primary brain tumours: Toxicities and outcomes in a peadiatric and adult population

Savagner,

Ducassou,

Cabarrou

et al. 2024

Clinical and Translational Radiation Oncology

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Setup Accuracy in Craniospinal Irradiation: Implications for Planning Treatment Volume Margins

Cited by 5 publications

References 15 publications

Script-Based Automatic Intensity-Modulated Radiotherapy Planning with Robust Optimization for Craniospinal Irradiation: A Retrospective Study

Script-Based Automatic Intensity-Modulated Radiotherapy Planning with Robust Optimization for Craniospinal Irradiation: A Retrospective Study

SGRT‐based stereotactic body radiotherapy for lung cancer setup accuracy and margin of the PTV

Helical tomotherapy craniospinal irradiation in primary brain tumours: Toxicities and outcomes in a peadiatric and adult population

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