Hippocampal-Sparing Whole-Brain Radiotherapy: A “How-To” Technique Using Helical Tomotherapy and Linear Accelerator–Based Intensity-Modulated Radiotherapy

Gondi, Vinai; Tolakanahalli, Ranjini; Mehta, Minesh P.; Tewatia, D; Rowley, Howard A.; Kuo, John S.; Khuntia, Deepak; Tomé, Wolfgang A.

doi:10.1016/j.ijrobp.2010.01.039

Cited by 314 publications

(279 citation statements)

References 22 publications

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“…All of our IMAT plans met all RTOG 0933 dosimetric compliance requirements. Using helical tomotherapy and linac‐based IMRT technique, Gondi and colleagues (11) have presented excellent results in sparing the hippocampi in the course of WBRT treatments for patients with brain metastasis. For five WBRT patients, with helical tomotherapy the median dose to the hippocampus was 5.5 Gy and maximum dose of 12.8 Gy.…”

Section: Discussionmentioning

confidence: 99%

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Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Pokhrel

Sood

Lominska

et al. 2015

J Applied Clin Med Phys

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The purpose of this study was to retrospectively investigate the accuracy, plan quality, and efficiency of using intensity‐modulated arc therapy (IMAT) for whole brain radiotherapy (WBRT) patients with sparing not only the hippocampus (following RTOG 0933 compliance criteria) but also other organs at risk (OARs). A total of 10 patients previously treated with nonconformal opposed laterals whole‐brain radiotherapy (NC‐WBRT) were retrospectively replanned for hippocampal sparing using IMAT treatment planning. The hippocampus was volumetrically contoured on fused diagnostic T1‐weighted MRI with planning CT images and hippocampus avoidance zone (HAZ) was generated using a 5 mm uniform margin around the hippocampus. Both hippocampi were defined as one paired organ. Whole brain tissue minus HAZ was defined as the whole‐brain planning target volume (WB‐PTV). Highly conformal IMAT plans were generated in the Eclipse treatment planning system for Novalis TX linear accelerator consisting of high‐definition multileaf collimators (HD‐MLCs: 2.5 mm leaf width at isocenter) and 6 MV beam for a prescription dose of 30 Gy in 10 fractions following RTOG 0933 dosimetric criteria. Two full coplanar arcs with orbits avoidance sectors were used. In addition to RTOG criteria, doses to other organs at risk (OARs), such as parotid glands, cochlea, external/middle ear canals, skin, scalp, optic pathways, brainstem, and eyes/lens, were also evaluated. Subsequently, dose delivery efficiency and accuracy of each IMAT plan was assessed by delivering quality assurance (QA) plans with a MapCHECK device, recording actual beam‐on time and measuring planed vs. measured dose agreement using a gamma index. On IMAT plans, following RTOG 0933 dosimetric criteria, the maximum dose to WB‐PTV, mean WB‐PTV D2%, and mean WB‐PTV D98% were 34.9±0.3 Gy,33.2±0.4 Gy, and 26.0±0.4 Gy, respectively. Accordingly, WB‐PTV received the prescription dose of 30 Gy and mean V30 was 90.5%±0.5%. The D100%, and mean and maximum doses to hippocampus were 8.4±0.3 Gy,11.2±0.3 Gy, and 15.6±0.4 Gy, on average, respectively. The mean values of homogeneity index (HI) and conformity index (CI) were 0.23×0.02 and 0.96×0.02, respectively. The maximum point dose to WB‐PTV was 35.3 Gy, well below the optic pathway tolerance of 37.5 Gy. In addition, compared to NC‐WBRT, dose reduction of mean and maximum of parotid glands from IMAT were 65% and 50%, respectively. Ear canals mean and maximum doses were reduced by 26% and 12%, and mean and maximum scalp doses were reduced by 9 Gy (32%) and 2 Gy (6%), on average, respectively. The mean dose to skin was 9.7 Gy with IMAT plans compared to 16 Gy with conventional NC‐WBRT, demonstrating that absolute reduction of skin dose by a factor of 2. The mean values of the total number of monitor units (MUs) and actual beam on time were 719×44 and 2.34×0.14 min, respectively. The accuracy of IMAT QA plan delivery was (98.1±0.8) %, on average, with a 3%/3 mm gamma index passing rate criteria. All of these plans were considered clinically acceptable per ...

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Section: Discussionmentioning

confidence: 99%

“…However, tomotherapy or linear accelerator‐based IMRT requires a large number of total MUs and relatively longer treatment times 10 , 11 , 12 …”

Section: Introductionmentioning

confidence: 99%

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Pokhrel

Sood

Lominska

et al. 2015

J Applied Clin Med Phys

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“…Using modern radiotherapy planning systems, the mean dose of radiation to the neural stem-cell compartment of the hippocampus can be reduced by 80%, while ensuring an adequate dose coverage and homogeneity in the rest of the brain [20]. It has also been seen that the incidence of recurrences within 5 mm of the hippocampi is very low.…”

Section: Hippocampal Avoidance Radiation (Hart)mentioning

confidence: 99%

Emerging Role of Neurocognitive Sparing Radiotherapy: Can it be the New Standard of Care?

Mitra¹,

Kataria²

2017

J Neurol Neurophysiol

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Whole-brain radiation therapy has been the standard form of treatment for advanced cancers, metastatic to the brain. It has the advantage of easy availability and delivery, and effectiveness in offering relief from symptoms for many suitable patients. Since most of these patients have poor outcomes and limited survival, oncologists in the past had a nihilistic approach and as a result, the potential toxicities emerging from WBRT have been largely neglected. With advances been made in neurosurgery, imaging, medical and radiation oncology, the results for many patients have improved significantly, particularly for those having favorable prognostic factors. Hence, the use of WBRT has come under scrutiny, due to its potential effect on the neurocognitive functions of the patient and their quality of life. This review article attempts to investigate if the various Neurocognitive sparing radiotherapy procedures can become a standard radiotherapy method for selected patients receiving whole brain radiotherapy for metastatic disease.

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“…In addition, lenses, eyes, optic nerves, optic chiasm, brainstem, temporal lobes, hippocampi, cochleae, and parotid glands were contoured as organs at risk (OARs). The hippocampal contouring was based on the report by Gondi et al (6) …”

Section: Treatment Planningmentioning

confidence: 99%

Dosimetric advantages of O‐ring design radiotherapy system for skull‐base tumors

Ogura

Mizowaki

Ishida

et al. 2014

J Applied Clin Med Phys

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The purpose of this study was to investigate whether a new O‐ring design radiotherapy delivery system has advantages in radiotherapy planning for skull‐base tumors. Twenty‐five patients with skull‐base tumors were included in this study. Two plans were made using conventional (Plan A) or new (Plan B) techniques. Plan A consisted of four dynamic conformal arcs (DCAs): two were horizontal, and the other two were from cranial directions. Plan B was created by converting horizontal arcs to those from caudal directions making use of the O‐ring design radiotherapy system. The micromultileaf collimators were fitted to cover at least 99% of the planning target volume with prescribed doses, 90% of the dose at the isocenter. The two plans were compared in terms of target homogeneity, conformity, and irradiated volume of normal tissues, using a two‐sided paired t‐test. For evaluation regarding target coverage, the homogeneity indices defined by the International Commission on Radiation Units and Measurements 83 were 0.099±0.010 (mean ± standard deviation) and 0.092±0.010, the conformity indices defined by the Radiation Therapy Oncology Group were 1.720±0.249 and 1.675±0.239, and the Paddick's conformity indices were 0.585±0.078 and 0.602±0.080, in Plans A and B, respectively. For evaluation of irradiated normal tissue, the Paddick's gradient indices were 3.118±0.283 and 2.938±0.263 in Plans A and B, respectively. All of these differences were statistically significant (p‐values <0.05). The mean doses of optic nerves, eyes, brainstem, and hippocampi were also significantly lower in Plan B. The DCA technique from caudal directions using the new O‐ring design radiotherapy system can improve target homogeneity and conformity compared with conventional DCA techniques, and can also decrease the volume of surrounding normal tissues that receives moderate doses.PACS numbers: 87.55.‐x, 87.55.D‐, 87.55.dk

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Hippocampal-Sparing Whole-Brain Radiotherapy: A “How-To” Technique Using Helical Tomotherapy and Linear Accelerator–Based Intensity-Modulated Radiotherapy

Cited by 314 publications

References 22 publications

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Potential for reduced radiation‐induced toxicity using intensity‐modulated arc therapy for whole‐brain radiotherapy with hippocampal sparing

Emerging Role of Neurocognitive Sparing Radiotherapy: Can it be the New Standard of Care?

Dosimetric advantages of O‐ring design radiotherapy system for skull‐base tumors

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