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Jaberi R, Babaloui S, Siavashpour Z, Moshtaghi M, Shirazi A, Joya M, Gholami MH, Jafari S. 3D in vivo dosimetry of HDR gynecological brachytherapy using micro silica bead TLDs. J Appl Clin Med Phys 2022; 23:e13729. [PMID: 35946855 PMCID: PMC9512342 DOI: 10.1002/acm2.13729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 06/30/2022] [Accepted: 07/01/2022] [Indexed: 11/26/2022] Open
Abstract
Purpose This study aimed to evaluate the feasibility of defining an in vivo dosimetry (IVD) protocol as a patient‐specific quality assurance (PSQA) using the bead thermoluminescent dosimeters (TLDs) for point and 3D IVD during brachytherapy (BT) of gynecological (GYN) cancer using 60Co high‐dose‐rate (HDR) source. Methods The 3D in vivo absorbed dose verification within the rectum and bladder as organs‐at‐risk was performed by bead TLDs for 30 GYN cancer patients. For rectal wall dosimetry, 80 TLDs were placed in axial arrangements around a rectal tube covered with a layer of gel. Ten beads were placed inside the Foley catheter to get the bladder‐absorbed dose. Beads TLDs were localized and defined as control points in the treatment planning system (TPS) using CT images of the patients. Patients were planned and treated using the routine BT protocol. The experimentally obtained absorbed dose map of the rectal wall and the point dose of the bladder were compared to the TPSs predicted absorbed dose at these control points. Results Relative difference between TPS and TLDs results were −8.3% ± 19.5% and −7.2% ± 14.6% (1SD) for rectum‐ and bladder‐absorbed dose, respectively. Gamma analysis was used to compare the calculated with the measured absorbed dose maps. Mean gamma passing rates of 84.1%, 90.8%, and 92.5% using the criteria of 3%/2 mm, 3%/3 mm, and 4%/2 mm were obtained, respectively. Eventually, a “considering level” of at least 85% as pass rate with 4%/2‐mm criteria was recommended. Conclusions A 3D IVD protocol employing bead TLDs was presented to measure absorbed doses delivered to the rectum and bladder during GYN HDR‐BT as a reliable PSQA method. 3D rectal absorbed dose measurements were performed. Differences between experimentally measured and planned absorbed dose maps were presented in the form of a gamma index, which may be used as a warning for corrective action.
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Affiliation(s)
- Ramin Jaberi
- Radiation Oncology Department, Yas Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran.,Department of Physics, University of Surrey, Guildford, UK
| | - Somayyeh Babaloui
- Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Zahra Siavashpour
- Radiotherapy Oncology Department, Shohada-e-Tajrish Educational Hospital, Medical School, Shahid Beheshti University of Medical Sciences, Tehran, Iran
| | - Maryam Moshtaghi
- Radiation Oncology Department, Yas Hospital Complex, Tehran University of Medical Sciences, Tehran, Iran
| | - Alireza Shirazi
- Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Musa Joya
- Department of Medical Physics and Biomedical Engineering, Faculty of Medicine, Tehran University of Medical Sciences, Tehran, Iran.,Radiology Department, Kabul University of Medical Sciences, Afghanistan
| | - Mohammad Hadi Gholami
- Department of Medical Radiation Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.,Mahdieh Radiotherapy Oncology Center, Hamedan, Iran
| | - Shakardokht Jafari
- Department of Physics, University of Surrey, Guildford, UK.,Medical Physics Dept., Portsmouth Hospitals University NHS Trust, Portsmouth, UK.,Medical Research Centre, Kateb University, Kabul, Afghanistan
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Correlation analysis of CT-based rectal planning dosimetric parameters with in vivo dosimetry of MOSkin and PTW 9112 detectors in Co-60 source HDR intracavitary cervix brachytherapy. Phys Eng Sci Med 2021; 44:773-783. [PMID: 34191272 DOI: 10.1007/s13246-021-01026-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 06/03/2021] [Indexed: 10/21/2022]
Abstract
Intracavitary cervical brachytherapy delivers high doses of radiation to the target tissue and a portion of these doses will also hit the rectal organs due to their close proximity. Rectal dose can be evaluated from dosimetric parameters in the treatment planning system (TPS) and in vivo (IV) dose measurement. This study analyzed the correlation between IV rectal dose with selected volume and point dose parameters from TPS. A total of 48 insertions were performed and IV dose was measured using the commercial PTW 9112 semiconductor diode probe. In 18 of 48 insertions, a single MOSkin detector was attached on the probe surface at 50 mm from the tip. Four rectal dosimetric parameters were retrospectively collected from TPS; (a) PTW 9112 diode maximum reported dose (RPmax) and MOSkin detector, (b) minimum dose to 2 cc (D2cc), (c) ICRU reference point (ICRUr), and (d) maximum dose from additional points (Rmax). The IV doses from both detectors were analyzed for correlation with these dosimetric parameters. This study found a significantly high correlation between IV measured dose from RPmax (r = 0.916) and MOSkin (r = 0.959) with TPS planned dose. The correlation between measured RPmax with both D2cc and Rmax revealed high correlation of r > 0.7, whereas moderate correlation (r = 0.525) was observed with ICRUr. There was no significant correlation between MOSkin IV measured dose with D2cc, ICRUr and Rmax. The non-significant correlation between parameters was ascribable to differences in both detector position within patients, and dosimetric volume and point location determined on TPS, rather than detector uncertainties.
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Jamalludin Z, Jong W, Malik R, Rosenfeld A, Ung N. Evaluation of rectal dose discrepancies between planned and in vivo dosimetry using MOSkin detector and PTW 9112 semiconductor probe during 60Co HDR CT-based intracavitary cervix brachytherapy. Phys Med 2020; 69:52-60. [DOI: 10.1016/j.ejmp.2019.11.025] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 11/26/2019] [Accepted: 11/29/2019] [Indexed: 10/25/2022] Open
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Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer. Phys Med 2014; 30:980-4. [DOI: 10.1016/j.ejmp.2014.07.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Revised: 06/03/2014] [Accepted: 07/13/2014] [Indexed: 11/19/2022] Open
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