Abstract
BackgroundMOSFET dosimetry is a method that has been used to measure in-vivo doses during brachytherapy treatments and during linac based radiotherapy treatment. Rectal displacement devices (RDDs) allow for safe dose escalation for prostate cancer treatment. This study used dual MOSkin detectors to assess real-time in vivo rectal wall dose in patients with an RDD in place during a high dose prostate stereotactic body radiation therapy (SBRT) boost trial.MethodsThe PROMETHEUS study commenced in 2014 and provides a prostate SBRT boost dose with a RDD in place. Twelve patients received two boost fractions of 9.5–10 Gy each delivered to the prostate with a dual arc volumetric modulated arc therapy (VMAT) technique. Two MOSkins in a face-to-face arrangement (dual MOSkin) were used to decrease angular dependence. A dual MOSkin was attached to the anterior surface of the Rectafix and read out at 1 Hz during each treatment. The planned dose at each measurement point was exported from the planning system and compared with the measured dose. The root mean square error normalised to the total planned dose was calculated for each measurement point and treatment arc for the entire course of treatment.ResultsThe average difference between the measured and planned doses over the whole course of treatment for all arcs measured was 9.7% with a standard deviation of 3.6%. The cumulative MOSkin reading was lower than the total planned dose for 64% of the arcs measured. The average difference between the final measured and final planned doses for all arcs measured was 3.4% of the final planned dose, with a standard deviation of 10.3%.ConclusionsMOSkin detectors were an effective tool for measuring dose delivered to the anterior rectal wall in real time during prostate SBRT boost treatments for the purpose of both ensuring the rectal doses remain within acceptable limits during the treatment and for the verification of final rectal doses.
Highlights
MOSFET dosimetry is a method that has been used to measure in-vivo doses during brachytherapy treatments and during linac based radiotherapy treatment
Delivery of a boost dose using high dose rate (HDR) brachytherapy in combination with conventionally fractionated external beam radiation therapy (EBRT) has been shown to improve tumour control rates when compared with conventionally fractionated EBRT alone [3,4,5]
MOSkin detectors attached to a Rectafix were used to measure anterior rectal wall dose in real time during prostate stereotactic body radiation therapy (SBRT) boost treatments
Summary
MOSFET dosimetry is a method that has been used to measure in-vivo doses during brachytherapy treatments and during linac based radiotherapy treatment. Rectal displacement devices (RDDs) allow for safe dose escalation for prostate cancer treatment. This study used dual MOSkin detectors to assess real-time in vivo rectal wall dose in patients with an RDD in place during a high dose prostate stereotactic body radiation therapy (SBRT) boost trial. Prostate cancer shows a radiation response consistent with a low α/β ratio, indicating that hypofractionated treatment schedules may increase the effectiveness of treatment [1, 2]. Delivery of a boost dose using high dose rate (HDR) brachytherapy in combination with conventionally fractionated external beam radiation therapy (EBRT) has been shown to improve tumour control rates when compared with conventionally fractionated EBRT alone [3,4,5]. Rectal complications can arise as a result of radiation therapy for prostate cancer, and delivery of higher doses through hypofractionation increases the risk of damage to surrounding healthy tissues [9]. The Rectafix has been found to provide an average increase in separation of 0.5 cm and to assist in immobilising the rectal wall by preventing changes in filling by gas or faeces [12]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
