Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer

Zaman, Z. K.; Ung, Ngie Min; Malik, Rozita Abdul; Ho, Gwo Fuang; Phua, Vincent Chee Ee; Jamalludin, Zulaikha; Baharuldin, Mohamad Taufik Hidayat; Ng, Kwan Hoong

doi:10.1016/j.ejmp.2014.07.002

Cited by 23 publications

(13 citation statements)

References 18 publications

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“…3 IVD is widely utilized for external radiotherapy treatments 4 but it has yet to be optimized for HDRBT so that a precise detection of errors during treatment can be guaranteed. 5 Thermoluminescent dosimeters (TLDs) and semiconductor diodes have been used for this purpose over the past few decades [6][7][8][9][10] but they have some undesirable characteristics. For instance, TLDs do not provide immediate measurements, while the response of semiconductor diodes can be markedly affected by measurement conditions, due to their dependence on temperature and altered sensitivity from radiation damage.…”

Section: Introductionmentioning

confidence: 99%

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

et al. 2020

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Purpose: The objective of this study was to characterize the Best Medical Canada microMOSFET detectors for their application in in vivo dosimetry for high-dose-rate brachytherapy (HDRBT) with 192 Ir. We also developed a mathematical model to correct dependencies under the measurement conditions of these detectors. Methods: We analyzed the linearity, reproducibility, and interdetector variability and studied the microMOSFET response dependence on temperature, source-detector distance, and angular orientation of the receptor with respect to the source. The correction model was applied to 19 measurements corresponding to five simulated treatments in a custom phantom specifically designed for this purpose. Results: The detectors (high bias applied in all measurements) showed excellent linearity up to 160 Gy. The response dependence on source-detector distance varied by (8.65 AE 0.06)% (k = 1) for distances between 1 and 7 cm, and the variation with temperature was (2.24 AE 0.05)% (k = 1) between 294 and 310 K. The response difference due to angular dependence can reach (10.3 AE 1.3)% (k = 1). For the set of measurements analyzed, regarding angular dependences, the mean difference between administered and measured doses was À4.17% (standard deviation of 3.4%); after application of the proposed correction model, the mean difference was À0.1% (standard deviation of 2.2%). For the treatments analyzed, the average difference between calculations and measures was 4.7% when only the calibration coefficient was used, but it is reduced to 0.9% when the correction model is applied. Conclusion: Important response dependencies of microMOSFET detectors used for in vivo dosimetry in HDRBT treatments, especially the angular dependence, can be adequately characterized by a correction model that increases the accuracy of this system in clinical applications.

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Section: Introductionmentioning

confidence: 99%

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

et al. 2020

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“…It is recommended to calibrate them and validate the output of these software to have better treatment responses and less complications in the clinic [10]. Physical measurement of the radiation dose prevents technical and calculation errors as well as post-RT problems [11]. Gafchromic film dosimetry is accepted in the dose verification [12,13], especially in 2D dose distribution [14,15].…”

Section: Introductionmentioning

confidence: 99%

Comparison of the 2-D Dose Distribution Calculated by Planning System and Measured by Gafchromic Film Physical Dosimetry for 60Co and 192Ir Brachytherapy Sources

Gholami

Sadeghi

Mofrad

et al. 2020

jbpe

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Background: High Dose Rate (HDR) brachytherapy sources with high photon energy have been widely used in treating tumors. Dosimetric parameter of these brachytherapy sources should be determined according to the AAPM TG-43 recommendation. Gafchoromic films are reliable tools for this evaluation.Objective: The aim of this study is to evaluate and compare dose accuracy of the two-brachytherapy sources in a dedicated phantom. Material and Methods:In this analytical study, two common sources, including Cobalt and Iridium, were loaded into the dedicated phantom. The two-dimensional dose distribution around the source was calculated by TPS system for certain activities and geometries around the sources. Then, the experimental dose measured by Gafchromic film dosimetry was reported for different angles ranging from 0 to 180 degrees. Results:The difference between calculated and measured doses was less than 6 percent (-5 to +6 percent) for all of the channels and angles. These errors are smaller and mainly more than zero (D film >D TPS ) for angles less than 20 and larger than 110 degrees. There is no statistically significant discrepancy in dose calculation by treatment planning system. Conclusion:Although the estimated error in dose calculation is not significant, there is still an opportunity to increase the treatment precision. The correlation between the error and the angle should be considered in further plans of brachytherapy. The present study showed comparable errors compared to results of other research studies.

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“…Cobalt-60 is a relatively new radioactive source used in high-dose rate brachytherapy [11]. Compared with the more widely used and studied iridium-192 sources, it has a higher γ mean energy ( 60 Co~1.25 MeV, 192 Ir~0.375 MeV) and a longer half-life ( 60 Co 5.27 years, 192 Ir 73.8 days) [12].…”

Section: Introductionmentioning

confidence: 99%

“…On review however of the PubMed database done prior to initiation of this study with the search terms "in-vivo," "dosimetry," "Cobalt 60," and "brachytherapy," there had only been 1 reported study testing in vivo rectal dosimetry for cobalt-60 for cervical cancer brachytherapy. The study by Zaman et al [11] published in 2014 compared planned and measured rectal doses from the HDR 60 Co brachytherapy of 11 cervical cancer patients. Their results showed that there were dose differences ranging from 8.5-41.2%, with an absolute difference of 0.3-1.5 Gy between treatment planning system (TPS) computed dose from axial computed tomography images compared with dose measured by rectal probes in vivo.…”

Section: Introductionmentioning

confidence: 99%

Comparison of ICRU 38 rectal reference point dose estimates with measured dose in vivo in cobalt-60 HDR brachytherapy for cervical cancer

2020

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Objective The objective of this study was to compare the ICRU 38 calculated rectal dose with in vivo dosimetry measured doses in cobalt-60 HDR brachytherapy for cervical cancer. Methods A total of 48 brachytherapy insertions done on 15 patients treated from January to March 2017 at our institution were included in this prospective cross-sectional study. ResultsThe results demonstrated no significant difference between the computed ICRU rectal point dose and in vivo maximum measured rectal dose ((r) 0.6208, p < 0.0001 [S]; t test p = 0.1578 [NS] 95% CI − 0.78 to 0.46), but a significant difference between ICRU rectal point and in vivo mean measured rectal dose ((r) 0.6033, p < 0.0001 [S]; t test p < 0.0001 [S] 95% CI − 0.81 to 0.35). These findings were seen even when sub-analyzed for the two used fraction sizes of 7 Gy and 8 Gy. The results also showed no significant differences in the maximum ((r) 0.9029, p < 0.0001 [S]; t test p = 0.2576 [NS], 95% CI − 0.21 to 0.06) and mean ((r) 0.9766, p < 0.0001 [S]; t test p = 0.2786 [NS], 95% CI − 0.93 to 0.03) doses taken from treatment planning system assigned dose points coinciding with the imaged probes of the in vivo dosimeter. Conclusion Overall, this study was able to provide additional evidence that in vivo dosimetry can be validly used in the clinical setting to estimate the dose to the rectum during Co-60 HDR brachytherapy. Use of this technique allows for an additional quality assurance method that can contribute to reductions of errors in dose delivery.

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Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer

Cited by 23 publications

References 18 publications

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

Comparison of the 2-D Dose Distribution Calculated by Planning System and Measured by Gafchromic Film Physical Dosimetry for 60Co and 192Ir Brachytherapy Sources

Comparison of ICRU 38 rectal reference point dose estimates with measured dose in vivo in cobalt-60 HDR brachytherapy for cervical cancer

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Comparison of planned and measured rectal dose in-vivo during high dose rate Cobalt-60 brachytherapy of cervical cancer

Cited by 23 publications

References 18 publications

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with 192Ir

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with 192Ir

Comparison of the 2-D Dose Distribution Calculated by Planning System and Measured by Gafchromic Film Physical Dosimetry for 60Co and 192Ir Brachytherapy Sources

Comparison of ICRU 38 rectal reference point dose estimates with measured dose in vivo in cobalt-60 HDR brachytherapy for cervical cancer

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Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir

Characterization of microMOSFET detectors for in vivo dosimetry in high‐dose‐rate brachytherapy with ¹⁹²Ir