Therapeutic benefits in grid irradiation on Tomotherapy for bulky, radiation-resistant tumors

Narayanasamy, G.; Zhang, Xin; Meigooni, Ali S.; Paudel, Naba R.; Morrill, Steven; Maraboyina, Sanjay; Peacock, Loverd M.; Peñagarícano, José

doi:10.1080/0284186x.2017.1299219

Cited by 13 publications

(17 citation statements)

References 26 publications

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“…Detailed summaries can be found in two recent reviews by Billena and Khan [5] for GRID therapy and by Eling et al [6,7] for MRT. Today, there are a number of modern treatment delivery technologies available for clinical SFRT including multi-leaf collimator generated [8][9][10][11], Tomotherapy [5], and particle GRID therapy [12,13]. For preclinical SFRT, newer technologies include "minibeams" with larger spatial fractionation scales (on the order of millimeter instead of the tens of microns used in classical MRT [14,15] and with conventional dose-rates [16,17], [4].…”

Section: Introductionmentioning

confidence: 99%

Conventional dose rate spatially-fractionated radiation therapy (SFRT) treatment response and its association with dosimetric parameters—A preclinical study in a Fischer 344 rat model

et al. 2020

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To identify key dosimetric parameters that have close associations with tumor treatment response and body weight change in SFRT treatments with a large range of spatial-fractionation scale at dose rates of several Gy/min. Methods Six study arms using uniform tumor radiation, half-tumor radiation, 2mm beam array radiation, 0.3mm minibeam radiation, and an untreated arm were used. All treatments were delivered on a 320kV x-ray irradiator. Forty-two female Fischer 344 rats with fibrosarcoma tumor allografts were used. Dosimetric parameters studied are peak dose and width, valley dose and width, peak-to-valley-dose-ratio (PVDR), volumetric average dose, percentage volume directly irradiated, and tumor-and normal-tissue EUD. Animal survival, tumor volume change, and body weight change (indicative of treatment toxicity) are tested for association with the dosimetric parameters using linear regression and Cox Proportional Hazards models. Results The dosimetric parameters most closely associated with tumor response are tumor EUD (R 2 = 0.7923, F-stat = 15.26*; z-test =-4.07***), valley (minimum) dose (R 2 = 0.7636, Fstat = 12.92*; z-test =-4.338***), and percentage tumor directly irradiated (R 2 = 0.7153, Fstat = 10.05*; z-test =-3.837***) per the linear regression and Cox Proportional Hazards models, respectively. Tumor response is linearly proportional to valley (minimum) doses

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Section: Introductionmentioning

confidence: 99%

Conventional dose rate spatially-fractionated radiation therapy (SFRT) treatment response and its association with dosimetric parameters—A preclinical study in a Fischer 344 rat model

et al. 2020

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“…Since MLCs are integral parts of each medical linear accelerator (by now), our technique can be easily adopted to other small radiotherapy clinics with less extensive physics or machine support for GRID therapy patients. Our future work includes the following: generating an MLC‐based GRID template in Eclipse for automation, prospectively quantifying the therapeutic gain and treatment related toxicity by escalating tumor dose to the deep‐seated tumors and potentially using DIBH with FFF‐beams in the management of tumor motion for the MLC‐based GRID therapy patients. Moreover, the potential use of the 3D‐MLC crossfire approach for highly irregular GRID targets will be explored.…”

Section: Discussionmentioning

confidence: 99%

“…Currently, MV GRID therapy treatments are delivered using a high attenuation GRID-block with divergent holes, with step and shoot multileaf collimator (MLC) control points, and/or Tomotherapy machines. [4][5][6][7][8][9][10][11][12][13][14][15] Although, the treatment planning studies for GRID therapy using tomotherapy and step and shoot MLCs are evolving, these techniques require longer treatment times due to beam modulation and need patient-specific quality assurance (QA). Moreover, noninterdigitating MLCs potentially may not allow an efficient implementation of this method.…”

Section: Discussionmentioning

confidence: 99%

“…generating an MLC-based GRID template in Eclipse for automation, prospectively quantifying the therapeutic gain and treatment related toxicity 8,16,22,27 by escalating tumor dose to the deep-seated tumors and potentially using DIBH with FFF-beams 31,32 in the management of tumor motion for the MLC-based GRID therapy patients. Moreover, the potential use of the 3D-MLC crossfire approach for highly irregular GRID targets will be explored.…”

Section: G | Simulating Dose Escalated Plansmentioning

confidence: 99%

“…gain can be achieved by escalating dose > 12 Gy in one fraction 8,16,22,27. However, for deep-seated bulky tumors, a single-field Cerrobend GRID-block could potentially produce difficulties in avoiding skin toxicity.…”

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confidence: 99%

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A novel, yet simple MLC‐based 3D‐crossfire technique for spatially fractionated GRID therapy treatment of deep‐seated bulky tumors

Pokhrel

Halfman

Sanford

et al. 2020

J Applied Clin Med Phys

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Purpose Treating deep‐seated bulky tumors with traditional single‐field Cerrobend GRID‐blocks has many limitations such as suboptimal target coverage and excessive skin toxicity. Heavy traditional GRID‐blocks are a concern for patient safety at various gantry‐angles and dosimetric detail is not always available without a GRID template in user’s treatment planning system. Herein, we propose a simple, yet clinically useful multileaf collimator (MLC)‐based three‐dimensional (3D)‐crossfire technique to provide sufficient target coverage, reduce skin dose, and potentially escalate tumor dose to deep‐seated bulky tumors. Materials/methods Thirteen patients (multiple sites) who underwent conventional single‐field cerrobend GRID‐block therapy (maximum, 15 Gy in 1 fraction) were re‐planned using an MLC‐based 3D‐crossfire method. Gross tumor volume (GTV) was used to generate a lattice pattern of 10 mm diameter and 20 mm center‐to‐center mimicking conventional GRID‐block using an in‐house MATLAB program. For the same prescription, MLC‐based 3D‐crossfire grid plans were generated using 6‐gantry positions (clockwise) at 60° spacing (210°, 270°, 330°, 30°, 90°, 150°, therefore, each gantry angle associated with a complement angle at 180° apart) with differentially‐weighted 6 or 18 MV beams in Eclipse. For each gantry, standard Millenium120 (Varian) 5 mm MLC leaves were fit to the grid‐pattern with 90° collimator rotation, so that the tunneling dose distribution was achieved. Acuros‐based dose was calculated for heterogeneity corrections. Dosimetric parameters evaluated include: mean GTV dose, GTV dose heterogeneities (peak‐to‐valley dose ratio, PVDR), skin dose and dose to other adjacent critical structures. Additionally, planning time and delivery efficiency was recorded. With 3D‐MLC, dose escalation up to 23 Gy was simulated for all patient's plans. Results All 3D‐MLC crossfire GRID plans exhibited excellent target coverage with mean GTV dose of 13.4 ± 0.5 Gy (range: 12.43–14.24 Gy) and mean PVDR of 2.0 ± 0.3 (range: 1.7–2.4). Maximal and dose to 5 cc of skin were 9.7 ± 2.7 Gy (range: 5.4–14.0 Gy) and 6.3 ± 1.8 Gy (range: 4.1–11.1 Gy), on average respectively. Three‐dimensional‐MLC treatment planning time was about an hour or less. Compared to traditional GRID‐block, average beam on time was 20% less, while providing similar overall treatment time. With 3D‐MLC plans, tumor dose can be escalated up to 23 Gy while respecting skin dose tolerances. Conclusion The simple MLC‐based 3D‐crossfire GRID‐therapy technique resulted in enhanced target coverage for de‐bulking deep‐seated bulky tumors, reduced skin toxicity and spare adjacent critical structures. This simple MLC‐based approach can be easily adopted by any radiotherapy center. It provides detailed dosimetry and a safe and effective treatment by eliminating the heavy physical GRID‐block and could potentially provide same day treatment. Prospective clinical trial with higher tumor‐dose to bulky deep‐seated tumors is anticipated.

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Dose evaluation of Grid Therapy using a 6 MV flattening filter‐free (FFF) photon beam: A Monte Carlo study

2017

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Therapeutic benefits in grid irradiation on Tomotherapy for bulky, radiation-resistant tumors

Abstract: HT-GRID therapy demonstrates a significant therapeutic advantage over uniform dose from an open field irradiation for the same tumor cell kill. TR increases with the radioresistance of the tumor cells and with prescription dose.

Cited by 13 publications

References 26 publications

Conventional dose rate spatially-fractionated radiation therapy (SFRT) treatment response and its association with dosimetric parameters—A preclinical study in a Fischer 344 rat model

Conventional dose rate spatially-fractionated radiation therapy (SFRT) treatment response and its association with dosimetric parameters—A preclinical study in a Fischer 344 rat model

A novel, yet simple MLC‐based 3D‐crossfire technique for spatially fractionated GRID therapy treatment of deep‐seated bulky tumors

Dose evaluation of Grid Therapy using a 6 MV flattening filter‐free (FFF) photon beam: A Monte Carlo study

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