Evaluation of stereotactic radiosurgery conformity indices for 170 target volumes in patients with brain metastases

Stanley, Julia; Breitman, K.; Dunscombe, Peter; Spencer, David P.; Lau, Harold

doi:10.1120/jacmp.v12i2.3449

Cited by 45 publications

(36 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The established values for normal tissue dose were based on the healthy tissue overdosage factor (HTOF) of Salt (12,(16)(17)(18). The conformity index (CI) and the homogeneity index (HI) values for the target volume were calculated according to the following formulae (13,17,(19)(20)(21): i) CI RTOG = V RI / TV; where the volume of the reference isodose (V RI ) is the volume of the PTV receiving a 95% reference/planned dose, and the target volume (TV) is the volume of the PTV. ii) HI = I max / RI; where I max is the maximum dose to the target, and RI is the reference dose in the PTV.…”

Section: Methodsmentioning

confidence: 99%

Protection of organs at risk during neoadjuvant chemoradiotherapy for gastric cancer based on a comparison between conformal and intensity-modulated radiation therapy

et al. 2016

View full text Add to dashboard Cite

Abstract. The aim of the present study was to compare the techniques of dynamic intensity-modulated radiation therapy (IMRT) and three-dimensional conformal radiotherapy (3DCRT) in patients with gastric cancer. Implementation of the IMRT technique does not significantly affect the minimum and maximum dose levels in the planning target volume (PTV), but more effectively protects the critical organs. The study group consisted of 25 patients. The results of the analysis of the conformity index (CI) and the homogeneity index (HI) showed that the doses in the PTV regions were at a comparable level. The CI for the PTV was 0.95 for the 2-field technique, 0.95 for the 3-field technique, 0.96 for the 4-field technique and 0.94 for the IMRT technique. The CIs for these techniques for the clinical target volume (CTV) were 0.96, 0.96, 0.97 and 0.96, respectively, and the CIs for the gross tumor volume (GTV) were 0.99, 0.99, 0.99 and 0.98, respectively. The HI values for the PTV were 1.12 for the 2-field technique, 1.12 for the 3-field technique, 1.09 for the 4-field technique and 1.09 for the IMRT technique, and the HI values for the CTV were 1.12, 1.12, 1.09 and 1.08 for the same techniques, respectively. The HI values for the GTV were 1.09, 1.09, 1.07 and 1.06, respectively, which indicated significantly superior performance in the regions of healthy tissue. Statistical study was based on Friedman's rank analysis of variance to determine the level of reliability of the tested groups of variables (P<0.001). The present study demonstrated that the IMRT technique in the pre-operative radiotherapy of gastric cancer patients results in superior treatment tolerance and reduces the risk of damage to healthy tissue that is in close proximity to the irradiated area.

show abstract

Section: Methodsmentioning

confidence: 99%

Protection of organs at risk during neoadjuvant chemoradiotherapy for gastric cancer based on a comparison between conformal and intensity-modulated radiation therapy

et al. 2016

View full text Add to dashboard Cite

show abstract

“…CI RTOG is defined as the volume covered by the prescription isodose divided by the total target tumor volume. 45 Mathematically, perfect overlap between the targeted volume and total tumor volume would correspond to a CI value of 1.0. On the other hand, decreasing the volume of coverage or increasing the lesion volume would result in a lower CI value.…”

Section: Adverse Radiation Effectsmentioning

confidence: 99%

Predictors of response to Gamma Knife radiosurgery for intracranial meningiomas

Mansouri

Larjani

Klironomos

et al. 2015

JNS

View full text Add to dashboard Cite

M eningioMas are the most common primary intracranial nonglial neoplasms in adults. 34 When feasible, the ideal management of meningiomas is complete resection of the tumor and associated dura mater, with the goal of minimizing further neurological morbidity for the patient. 28 However, not all meningiomas are amenable to gross-total resection (e.g., extensive involvement of skull base structures or invasion into the venous sinuses or other neurovascular structures), and alternative complementary treatment strategies are necessary. 4,27,40 abbreviatioNs ARE = adverse radiation event; CI RTOG = Radiation Therapy Oncology Group Conformity Index; RT = radiotherapy; SGR = specific growth rate; SRS = stereotactic radiosurgery; TVR = treatment volume ratio. obJect In this paper, the authors' aim was to determine short-term volumetric and diametric tumor growth and identify clinical, radiological, and dosimetric predictors of adverse radiation events (AREs) following stereotactic radiosurgery (SRS) for intracranial WHO Grade I meningiomas. methods This is a retrospective review of all WHO Grade I meningiomas that were treated with SRS (primary or adjuvant) between December 2005 and June 2012 at the University Health Network. Seventy-five patients had at least 24 months of both clinical and radiological follow-up and were, therefore, included in this study. Tumor growth was defined as any volumetric or diametric change greater than 10% per year. Any variation less than +10% was considered growth stability. Volumetric measurements were made using T1-weighted gadolinium-enhanced 3-T MRI scans and ITK-SNAP software. Tumor growth rates were calculated using the specific growth rate (SGR). Univariate statistics were used to identify predictors of post-SRS AREs. All statistical analyses were performed using IBM SPSS. results Women accounted for 69.3% of patients, and the mean treatment age was 58.6 years. Median follow-up was 36.2 months. Twenty-one (28%) patients had undergone prior resection. Two (3%) patients required salvage surgical intervention following SRS. The majority of the lesions (56%) were skull base tumors. Median tumor volume and diameter were 5.2 cm 3 and 27.5 mm, respectively. The absence of tumor growth was observed in 39 cases (52%) based on the volumetric measurements, while the absence of tumor growth was observed in 69 cases (92%) based on the diametric measurements. Twenty-six patients (34.6%) experienced new-onset AREs, including headache (17.3%), cranial neuropathy (10.6%), speech impairment (2.7%), tremors (2.7%), and ataxia (1.3%). Fourteen patients (18.7%) experienced new-onset edema, and 4 of these patients were symptomatic. A lower conformity index (1.24 vs 1.4) was significantly associated with the development of edema (p < 0.001 power > 0.8). Patients with meningiomas that had growth rates of more than 10% per year were more likely to experience long-term headaches after SRS (p = 0.022). coNclusioNs Volume-based reporting of SRS outcomes for meningiomas may be a more accurate method given the ...

show abstract

“…Protocol compliance is defined as HI RTOG ≤ 2.0, with a HI RTOG between 2.0 and 2.5 defined as minor and HI RTOG > 2.5 as major deviations. 11,12 Q RTOG evaluates how well the required dose covers the target and is defined as…”

Section: 12mentioning

confidence: 99%

“…It is inversely related to the RTOG conformity index. 12,13,15 An ideal plan would result in a CI Paddick of 1.0, with a conformity index of ≥ 0.6 considered acceptable. 16 The Paddick gradient index (GI Paddick ) attempts to reflect how fast the dose falls off beyond the target in trying to spare normal tissue and critical structures.…”

Section: 12mentioning

confidence: 99%

Hypofractionated image-guided radiotherapy for the treatment of acoustic neuromas: A dosimetrically acceptable alternative to stereotactic radiosurgery in a resource-constrained environment

Burger¹,

Gregor²,

Balchin³

et al. 2017

S. Afr. j. oncol.

View full text Add to dashboard Cite

Purpose: Treatment options for acoustic neuromas (ANs) are limited in low- and middle-income countries. The aim of this study was to investigate whether hypofractionated image-guided radiotherapy (IGRT) is a clinically acceptable treatment option for departments where no other radiosurgery options are available. Methods and materials: Fifteen dynamic conformal arc plans that had been clinically utilised were evaluated against the Radiation Therapy Oncology Group (RTOG) radiosurgery criteria and published indices. Analysis involved evaluating critical structure doses and the volume of normal tissue receiving 12 and 10 Gy single fraction equivalent dose (V12Eq and V10Eq). Results: Overall, there was only one RTOG protocol deviation in the whole patient group, where quality of coverage was compromised in order to achieve brainstem tolerance. Conformity indices were within clinically acceptable limits (CIPaddick ≥ 0.6) despite being inferior to the published Universitair Ziekenhuis Brussel (UZB) Gamma Knife and CyberKnife results (p < 0.0001). Homogeneity was superior to the Gamma Knife (p < 0.0001) and Novalis dynamic conformal arc (p = 0.0002) results. Gradient index results were inferior to all published techniques, but doses to the normal structures were well controlled with the exception of the cochlea. The V10Eq data showed increased sensitivity when compared with V12Eq. Conclusion: Dynamic arc IGRT allows for good coverage of AN lesions, but the dose fall-off is not as steep as that obtained with mainstream radiosurgery systems. Contouring and planning should include detailed critical structures analysis. For normal brain parenchyma analysis, V10Eq is a superior risk indicator when compared to V12Eq for this technique. Dynamic arc IGRT offers a dosimetrically acceptable treatment alternative for patients without serviceable hearing, in departments where there are no mainstream radiosurgery treatment options available.

show abstract

Evaluation of stereotactic radiosurgery conformity indices for 170 target volumes in patients with brain metastases

Cited by 45 publications

References 11 publications

Protection of organs at risk during neoadjuvant chemoradiotherapy for gastric cancer based on a comparison between conformal and intensity-modulated radiation therapy

Protection of organs at risk during neoadjuvant chemoradiotherapy for gastric cancer based on a comparison between conformal and intensity-modulated radiation therapy

Predictors of response to Gamma Knife radiosurgery for intracranial meningiomas

Hypofractionated image-guided radiotherapy for the treatment of acoustic neuromas: A dosimetrically acceptable alternative to stereotactic radiosurgery in a resource-constrained environment

Contact Info

Product

Resources

About