Verification using in vivo optically stimulated luminescent dosimetry of the predicted skin surface dose in patients receiving postmastectomy radiotherapy

Wake, Johnathon R.; Chen, Feng Qin; Ashworth, Simon; Wang, Wei; Stuart, Kirsty

doi:10.1016/j.meddos.2020.10.001

Cited by 6 publications

(4 citation statements)

References 18 publications

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“…These results were in agreement for similar bolus treatments. [ 17 32 ] In another group, gel bolus thickness of 0.5 cm was applied for PMRT and they reported Grade 2 acute skin toxicity (RTOG) was observed in (37%). [ 33 ]…”

Section: Discussionmentioning

confidence: 99%

Surface Dose Measurements in Chest Wall Postmastectomy Radiotherapy to Achieve Optimal Dose Delivery with 6 MV Photon Beam

Srinivas¹,

Lobo²,

Banerjee³

et al. 2021

Journal of Medical Physics

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Aim: A tissue-equivalent bolus of sufficient thickness is used to overcome build up effect to the chest wall region of postmastectomy radiotherapy (PMRT) patients with tangential technique till Radiation Therapy Oncology Group (RTOG) Grade 2 (dry desquamation) skin reaction is observed. The aim of this study is to optimize surface dose delivered to chest wall in three-dimensional radiotherapy using EBT3 film. Materials and Methods: Measurements were conducted with calibrated EBT3 films with thorax phantom under “open beam, Superflab gel (0.5 cm) and brass bolus conditions to check correlation against TPS planned doses. Eighty-two patients who received 50 Gy in 25# were randomly assigned to Group A (Superflab 0.5 cm gel bolus for first 15 fractions followed by no bolus in remaining 10 fractions), Group B or Group C (Superflab 0.5 cm gel or single layer brass bolus, respectively, till reaching RTOG Grade 2 skin toxicity). Results: Phantom measured and TPS calculated surface doses were within − 5.5%, 4.7%, and 8.6% under open beam, 0.5 cm gel, and single layer of brass bolus applications, respectively. The overall surface doses (OSD) were 80.1% ±2.9% ( n = 28), 92.6% ±4.6% ( n = 28), and 87.4% ±4.7% ( n = 26) in Group A, B, and C, respectively. At the end of treatment, 7 out of 28; 13 out of 28; and 9 out of 26 patients developed Grade 2 skin toxicity having the OSD value of 83.0% ±1.6% ( n = 7); 93.7% ±3.2% ( n = 13); and 89.9% ±5.6% ( n = 9) in Groups A, B, and C, respectively. At the 20 th –23 rd fraction, 2 out of 7; 6 out of 13; and 4 out of 9 patients in Groups A, B, and C developed a Grade 2 skin toxicity, while the remaining patients in each group developed at the end of treatment. Conclusions: Our objective to estimate the occurrence of optimal dose limit for bolus applications in PMRT could be achieved using clinical EBT3 film dosimetry. This study ensured correct dose to scar area to protect cosmetic effects. This may also serve as quality assurance on optimal dose delivery for expected local control in these patients.

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Section: Discussionmentioning

confidence: 99%

Surface Dose Measurements in Chest Wall Postmastectomy Radiotherapy to Achieve Optimal Dose Delivery with 6 MV Photon Beam

Srinivas¹,

Lobo²,

Banerjee³

et al. 2021

Journal of Medical Physics

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“…An Inlight OSL nanodot (Landauer, Inc.) dosimeters were used for skin dose measurements on the moving phantom surface. 14 The calibration of the nanoDot was performed on a linear accelerator under a 6MV photon beam using a 30 × 30 × 20 cm solid water phantom with a depth of 1.5 cm and field size of 10 × 10 cm. This allows for the concomitant use of a Farmer ionization chamber under the same calibration conditions.…”

Section: Methodsmentioning

confidence: 99%

Impact of Respiratory Motion on the Skin Dose for Breast Cancer in Tomotherapy: A Study in the In-house Moving Phantom

Nobnop,

Lertananpipat,

Watcharawipha

et al. 2023

Technol Cancer Res Treat

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Purpose: The dose expansion methods as the skin flash and virtual bolus were used to solve intrafraction movement for breast planning due to breathing motion. We investigated the skin dose in each planning method by using optically stimulated luminescence on an in-house moving phantom for breast cancer treatment in tomotherapy. The impact of respiratory motion on skin dose between static and dynamic phantom's conditions was evaluated. Methods: A phantom was developed with movement controlled by the respirator for generating the respiratory waveforms to simulate respiratory motion. Five optically stimulated luminescence dosimeters were placed on the phantom surface to investigate the skin dose for the TomoDirect and TomoHelical under static and dynamic conditions. Eight treatment plans were generated with and without skin flash or virtual bolus by varying the thickness. The difference in skin dose between the two phantom conditions for each plan was explored. Results: All plans demonstrated a skin dose of more than 87% of the prescription dose under static conditions. However, the skin dose was reduced to 84.1% (TomoDirect) and 78.9% (TomoHelical) for dynamic conditions. The treatment plans without skin flash or virtual bolus showed significant skin dose differences under static and dynamic conditions by 4.83% (TomoDirect) and 9.43% (TomoHelical), whereas the skin flash with two leaves (TomoDirect 2L) or virtual bolus of at least 1.0 cm thickness (VB1.0) application compensated the skin dose in case of intrafraction movements by presenting a skin dose difference of less than 2% between the static and dynamic conditions. Conclusion: The skin dose was reduced under dynamic conditions due to breathing motion. The skin flash method with TomoDirect 2L or virtual bolus application with 1.0 cm thickness was useful for maintaining skin dose following the prescription by compensating for intrafraction movement due to respiratory motion for breast cancer in tomotherapy.

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“…The sensitivity correction factor for the nanoDot TM accounts for corrections needed due to non-uniformity in therapy applications. [1][2][3][4][5][6] It is employed for in vivo dosimetry to determine organ doses during irradiation, such as for the skin [7][8][9][10] and eye lens. 11 The nanoDot TM offers several advantages, including its small size and repeatable readout, making it a preferred choice for in vivo dosimetry.…”

Section: Determination Of Nanodot Tm Sensitivity Correction Factormentioning

confidence: 99%

The development of a cylindrical phantom for nanoDotTM calibration with multiple beam angles

Yabsantia,

Munsing,

Chusin

et al. 2024

JAMS

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Background: The nanoDotTM dosimeter, an optically stimulated luminescent dosimeter (OSLD), is compact and precise, ideal for various applications like radiation dosimetry. The nanoDotTM requires calibration before use with the detector alignment perpendicular to the central beam axis. It exhibits angular dependence that may impact the calibration factor, requiring the fabrication of a specific cylindrical phantom for the calibration procedure. Objective: This study aimed to develop a cylindrical phantom for nanoDotTM calibration to facilitate dose measurements in composite fields with various beam angles and to evaluate the nanoDotTM calibration factors for different plans. Materials and methods: The cylindrical phantom was constructed using cast nylon material to accommodate the nanoDotTM or a cylindrical ionization chamber (IC). The novel phantom underwent validation for physical characteristics, including dimensions, density, and uniformity. Validation for the calibration factor, using cylindrical phantom (CF cylin) under standard conditions with a 10x10 cm² field size at 10 cm depth was conducted with 6 MV X-rays, comparing it with calibration factor using slab solid water phantoms (CFsolid). The CFcylin for different numbers of beams were determined and validated against a reference IC in various planning conditions. Furthermore, angular correction factors were determined for their application in the single-beam calibration factor. Results: The cylindrical phantom had dimensions of 20 cm in diameter and 30 cm in length, a density of 1.145 g/cm³ and good uniformity. As a result of single beam, the CF cylin, agreed well with CFsolid, showing a difference of -0.069%. The CFcylin increased with the number of beams, ranging between 1.179 and 1.242. Additionally, the angular correction factor increased as the number of beams increased, peaking at 1.058 with 9 beams. When comparing the results to the IC, it was observed that with an increase in the number of beams to 4 beams, the single-beam calibration factor exhibited a variation of more than 2%. However, when applying the CF cylin specific to the number of beams or correcting for the angular correction factor, the dose differences between nanoDotTM and IC measurements were within 2%. Conclusion: The developed cylindrical phantom is suitable for nanoDotTM calibration under single beam angle and in composite fields with various beam angles. The new calibration factors for specific numbers of beams allow for accurate dose measurements using nanoDotTM, thus reducing the dose difference from the IC to acceptable levels. Further studies should investigate its application in clinical situations.

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Verification using in vivo optically stimulated luminescent dosimetry of the predicted skin surface dose in patients receiving postmastectomy radiotherapy

Cited by 6 publications

References 18 publications

Surface Dose Measurements in Chest Wall Postmastectomy Radiotherapy to Achieve Optimal Dose Delivery with 6 MV Photon Beam

Surface Dose Measurements in Chest Wall Postmastectomy Radiotherapy to Achieve Optimal Dose Delivery with 6 MV Photon Beam

Impact of Respiratory Motion on the Skin Dose for Breast Cancer in Tomotherapy: A Study in the In-house Moving Phantom

The development of a cylindrical phantom for nanoDotTM calibration with multiple beam angles

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