TRUS-probe integrated MOSkin detectors for rectal wall in vivo dosimetry in HDR brachytherapy: In phantom feasibility study

Abstract

The increasing complexity and high amount of dose per fraction delivered in prostate high dose rate (HDR) brachytherapy treatments call for the implementation of accurate and effective methods for the systematic and independent quality control of the overall treatment procedure. In this study, MOSkin detectors were placed on a trans-rectal ultrasound (TRUS) probe with the aim of performing both imaging and real time rectal wall in vivo dosimetry with the use of just one single instrument. After an adequate calibration of the detectors, which was carried out in a solid water phantom, the use of MOSkins integrated to the TRUS probe was studied in a gel phantom with a typical (simplified) prostate implant. Measured and calculated doses from the treatment planning system were compared, with a resulting very low average discrepancy of -0.6 ± 2.6%. The results are very promising and of particular clinical importance, however, further in vivo investigation is planned to validate the proposed method. Disciplines Engineering | Science and Technology Studies Publication DetailsTenconi, C., Carrara, M., Borroni, M., Cerrotta, A., Cutajar, D., Petasecca, M., Lerch, M., Bucci, J., Gambarini, G., Pignoli, E. & Rosenfeld, A. (2014). TRUS-probe integrated MOSkin detectors for rectal wall in vivo dosimetry in HDR brachytherapy: in phantom feasibility study. Radiation Measurements, 71 379-383. ABSTRACTThe increasing complexity and high amount of dose per fraction delivered in prostate high dose rate (HDR) brachytherapy treatments call for the implementation of accurate and effective methods for the systematic and independent quality control of the overall treatment procedure. In this study, MOSkin detectors were placed on a trans-rectal ultrasound (TRUS) probe with the aim of performing both imaging and real time rectal wall in vivo dosimetry with the use of just one single instrument.After an adequate calibration of the detectors, which was carried out in a solid water phantom, the use of MOSkins integrated to the TRUS probe was studied in a gel phantom with a typical (simplified) prostate implant. Measured and calculated doses from the treatment planning system were compared, with a resulting very low average discrepancy of 0.6 ± 2.6%. The results are very promising and of particular clinical importance, however, further in vivo investigation is planned to validate the proposed method.

Real-time in vivo rectal wall dosimetry using MOSkin detectors during linac based stereotactic radiotherapy with rectal displacement

“…Previous studies using MO Skin s to measure dose in phantoms [ 14 , 16 ] during brachytherapy reported better agreement between total measured and planned doses than the patient measurements reported here, as did a phantom study of rectal wall dose measurement during tomotherapy [ 15 ]. A phantom study using plastic scintillation detectors attached to endorectal balloons found agreement between measured and planned doses to within 0.5%, [ 13 ] and plastic scintillation detectors measured rectal wall dose in patients during EBRT with the mean difference between measured and planned doses for each patient ranging from −3.3 to 3.3% [ 17 ].…”

“…One way to monitor the effect of any motion is real-time in-vivo dosimetric monitoring during treatment. Previous studies in this area have used plastic scintillation detectors and MOSFET based dosimeters in phantoms [ 13 – 16 ]. Plastic scintillation detectors attached to an endorectal balloon inserted in an anthropomorphic prostate phantom were used by Archambault et.…”

“…MO Skin s have been integrated into a transrectal ultrasound probe of the kind used to guide interstitial needle insertion during HDR brachytherapy treatment. MO Skin measurements taken during three HDR brachytherapy treatment deliveries to a phantom resulted in an average discrepancy of −0.6 ± 2.6% between the measured and planned doses [ 16 ].…”

In vivodosimetry: trends and prospects for brachytherapy

“…Occasional IVD feasibility studies have also been conducted in some clinics. [12][13][14][15][16][17][18][19][20][21][22][23][24] However, routine implementations of IVD for error detection monitoring and QA of the BT treatments is yet to come. One reason for this may be that the cost vs benefit relation of IVD is not established and that robust IVD systems that do not leave a significant footprint on the treatment workflow are not commercially available.…”

“…For phantom experiments of HDR BT, Tenconi et al 23 attached MOSkin detectors to a transrectal ultrasound (TRUS) probe, which was used for treatment planning and dosemeter position reconstruction and remained in place throughout the treatment delivery. With this implementation, sudden positional shifts of the TRUS probe with respect to the patient's anatomy, for example, owing to unexpected changes in posture, could be monitored online during the treatment.…”