On the evaluation of edgeless diode detectors for patient-specific QA in high-dose stereotactic radiosurgery

Abstract

In this work, the potential of an innovative "edgeless" silicon diode was evaluated as a response to the still unmet need of a reliable tool for plan dosimetry verification of very high dose, non-coplanar, patient-specific radiosurgery treatments. In order to prove the effectiveness of the proposed technology, we focused on radiosurgical treatments for functional disease like tremor or pain. Methods: The edgeless diodes response has been validated with respect to clinical practice standard detectors by reproducing the reference dosimetry data adopted for the Treatment Planning System. In order to evaluate the potential for radiosurgery patient-specific treatment plan verification, the anthropomorphic phantom Alderson RANDO has been adopted along with three edgeless sensors, one placed in the centre of the Planning Target Volume, one superiorly and one inferiorly. Results: The reference dosimetry data obtained from the edgeless detectors are within 2.6% for output factor, offaxis ratio and well within 2% for tissue phantom ratio when compared to PTW 60,018 diode. The edgeless detectors measure a dose discrepancy of approximately 3.6% from the mean value calculated by the TPS. Larger discrepancies are obtained in very steep gradient dose regions when the sensors are placed outside the PTV. Conclusions: The angular independent edgeless diode is proposed as an innovative dosimeter for patient quality assurance of brain functional disorders and other radiosurgery treatments. The comparison of the diode measurements with TPS calculations confirms that edgeless diodes are suitable candidates for patient-specific dosimetric verification in very high dose ranges delivered by non-isocentric stereotactic radiosurgery modalities.

IBA myQA SRS Detector for CyberKnife Robotic Radiosurgery Quality Assurance

“…135, a mistaken delivered dose or beam displacement errors may result "in inaccurate estimates of accumulated dose as well as inaccurate estimates of the steepness and location of the high dose gradient regions that may be designed to protect adjacent critical structures and organs at risk" [3]. A comprehensive QA program is therefore all the more important, but the challenges of such a program are still exacerbated by a lack of efficient and accurate equipment [4].…”

“…DQA tests are generally performed by means of ionization chambers, solid-state point detectors, or radiochromic films [4,5]. Recently, 2D and 3D detector arrays are increasingly being used in SRS, even just for specific tasks like planar dose mapping [6,7].…”

Implementing and evaluating a high‐resolution diode array for patient‐specific quality assurance of robotic brain stereotactic radiosurgery/radiotherapy

“…Other novel detector arrays have been proposed and hold promise for PSQA. 16,17 Recently CyberKnife delivery efficiency has been greatly improved with the newly introduced Volo optimization engine. [18][19][20] The total number of monitor unit (MU) and beams have been greatly reduced compared with plans using the prior sequential optimizer.…”

“…performed CyberKnife PSQA for nine patients using radiochromic film and an A16 small volume chamber in a head phantom. Other novel detector arrays have been proposed and hold promise for PSQA 16,17 . Recently CyberKnife delivery efficiency has been greatly improved with the newly introduced Volo optimization engine 18–20 .…”

Small static radiosurgery field dosimetry with small volume ionization chambers

“…More recently, with the increased use of highly modulated fields or small fields such as those used in Stereotactic Radiation Therapy (SRS) and Stereotactic Body Radiation Therapy (SBRT), chambers have been mostly replaced by solid state detectors such as synthetic diamond [8,9]. Latest developments in Radiotherapy may require new construction designs for both ion chambers and solid state detectors [10,11].…”