Measurement of Beam Data for Small Radiosurgical Fields: Comparison of CyberKnife Multi-sites in Korea

Abstract

The diode detector is recommended to measure the beam from CyberKnife recently. In this study, various detectors had been used to measure the beam data and compared that for each CyberKnife of domestic and foreign departments. All measurements of the beam data were performed by several detectors: diode detector, ion chamber, Gafchromic EBT film. These measured data compared with CyberKnife sites of the Korea. Also, these measured data are compared to a set of nationwide average data.For the collimators over than 20 mm, the beam data (TPR and OCR) from the different detectors showed a good agreement within ±3%. For the collimators less than 20 mm, the beam data have discrepancy of 10% or more for each detector. Comparing the measured output factors in this study and the average of foreign departments provided by Accuary, the agreement was less than ±0.5% except for 5 mm collimators for diode detector and ±1.5% for Gafchromic EBT film. For the collimators over than 20 mm, the beam data from the multi-sites showed a good agreement within ±1%. For the collimators less than 20 mm, it was found that the effective volume and the material of the detector affect the beam data.

Quality assurance of Cyberknife robotic stereotactic radiosurgery using an angularly independent silicon detector

“…Although the edgeless technology allows for processing of both p-and n-type substrates, in this work, the devices adopted are only n-type, with the top side junction being p + −n and the lateral junction n + −n. The diodes have dimensions of 0.5 × 0.5 × 0.5 mm 3 [ Fig. 1(a)] and are packaged using the "dropin" proprietary CMRP technology [ Fig.…”

“…1,2 It requires an accurate target localization and identification which can be achieved by physical stereotactic immobilization devices registering patient to a fixed frame (e.g., Gammaknife) or by imaging-guided methods (such as Cyberknife Synchrony). 3 Due to the small beam size and precise conformation of dose distribution, SRS treatment can reduce radiotoxicity to normal tissues and organs at risk and improve the probability of local tumor control. 4 It is used often for intracranial (brain tumor) and recently extracranial lesions such as spine and breast tumors.…”

Can Gafchromic EBT3 films effectively characterize small fields of 6 MV unflattened photon beams of Cyberknife system?

“…The main advantage of using EBT3 films is that it has high spatial resolution than any solid-state detectors and is tissue equivalent. Use of diode detectors for relative measurements in small fields are promising due to their small sensitive volume and diode P detector is employed widely for commissioning of Cyberknife photon beams [23].…”

Evaluation of nanoDot optically stimulated luminescence dosimeter for cone-shaped small-field dosimetry of cyberknife stereotactic radiosurgery unit: A monte carlo simulation and dosimetric verification study

“…Jang et al . [11] used a diode detector, ion chamber, and Gafchromic EBT3 film to measure beam data and compared them with the data obtained from other clinics with CyberKnife systems. Their results revealed that the beam data acquired using different detectors showed good consistency within ±3% for collimators larger than 20 mm.…”