Investigating the Effect of Air Cavities of Sinuses on the Radiotherapy Dose Distribution Using Monte Carlo Method

Seif, Fatemeh; Bayatiani, Mohamad Reza; Hamidi, Saeid; Kargaran, M

doi:10.31661/jbpe.v0i0.1046

Cited by 4 publications

(4 citation statements)

References 13 publications

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“…The impact of inhomogeneity on dose distribution has been previously investigated using various methods such as water phantoms or animal models like dogs, as shown in previous studies. 10 - 12 The presence of inhomogeneities is a concern because x-rays interact differently with different materials, leading to variations in image contrast. 13 In the case of sinuses, the air-filled spaces cause a reduction in dose due to the lower density of air compared to other tissues in the head.…”

Section: Discussionmentioning

confidence: 99%

The impact of sinusitis on dose distribution in a radiotherapy plan by in silico study

Alzahrani

2024

SMJ

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Objectives: To assess the impact of changes in sinus aeration on dose variation in nasopharyngeal cases using a single beam with various field sizes and real patient computed tomography (CT) images. Methods: The calculations were carried out on a computer equipped with an Intel Xeon (R) Gold 5118 processor operating at 2.30 GHz in 2022 at Taibah University, Al Madinah Al Munawwarah for a retrospective nasopharyngeal case. At the patient level, the impact on dose distribution was examined for different field sizes by comparing the percentage depth dose. The dose discrepancy was evaluated by comparing the dose delivered without considering the anatomical changes observed in the initial fraction to the dose adjusted to account for these changes using a 2D gamma analysis. With a criterion of 1% dose difference and 1 mm distance to agreement, the gamma level for analysis was set at 95%. Results: The study findings indicated that the observed effect diminished by approximately 50% for both 5 cm x 5 cm and 10 cm x 10 cm field sizes compared to the 3 cm x 3 cm size, where there was an overlap between the planning target volume and sinusitis. Conclusion: The study concluded that the impact of dose discrepancy was more pronounced in smaller field sizes.

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Section: Discussionmentioning

confidence: 99%

The impact of sinusitis on dose distribution in a radiotherapy plan by in silico study

Alzahrani

2024

SMJ

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“…BRT was the preferred option due to prior irradiation and the presence of air-tissue interfaces in the target region. Therefore, an important dose inhomogeneity was expected if external beam radiotherapy was to be used [ 14 ].…”

Section: Discussionmentioning

confidence: 99%

Simple fabrication technique of personalized endocavitary brachytherapy applicator for maxillary alveolar cancer

Bacorro,

Genson,

Dueñas

et al. 2023

jcb

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Purpose We report on methods and outcomes of post-operative endocavitary brachytherapy after prior irradiation and salvage surgery in a patient with maxillary alveolar squamous cell carcinoma (SCC). Material and methods A 67-year-old male with right maxillary alveolar SCC was referred for brachytherapy after prior definitive chemoradiotherapy and salvage posterior maxillectomy. A personalized endocavitary applicator was fabricated using dental impression plastic tray, vinyl polysiloxane paste, and four flexible catheters to deliver fourteen 3.5 Gy high-dose-rate fractions. High-risk and intermediate-risk clinical target volumes were treated to 3.7 Gy (D 90 ) and 2.4 Gy (D 98 ), with mandibular dose limited to 2.3 Gy (D 2cc ) per fraction. These corresponded to total 2 Gy equivalent doses (EQD 2 ) of 72.8 Gy, 40.5 Gy, and 34 Gy, respectively. Results The patient developed grade 2 mucositis and was disease-free for six months. He had biopsy-confirmed local recurrence at 8 months. He refused further treatment and expired within a month. Conclusions This simple approach to a personalized endocavitary applicator is feasible and allows for lower costs and less treatment delays, while ensuring patient comfort and convenience.

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“…Therefore, there is an increase in absorbed dose after cavities. The dose increase or decrease in the air-tissue interface are dependent on geometry, size, and depth of the cavity [ 15 ]. The capability to address dose inhomogeneity, shorter overall treatment time, and better cosmetic outcomes of brachytherapy make it ideal for EAC cancers.…”

Section: Discussionmentioning

confidence: 99%

Technical details and clinical outcomes after high-dose-rate intracavitary brachytherapy for squamous cell carcinoma of external auditory canal and external beam radiotherapy for nodal coverage: A case report

Dumago¹,

Yu²,

Jacomina³

et al. 2023

jcb

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Purpose To report technical details and 15-month outcomes of a patient with node-positive external auditory canal (EAC) squamous cell carcinoma (SCC) treated with definitive intracavitary high-dose-rate (HDR) brachytherapy to primary tumor, and external beam radiotherapy (EBRT) to draining lymphatics. Material and methods A 21-year-old male was diagnosed with SCC of the right EAC. The patient underwent definitive HDR intracavitary brachytherapy, 340 cGy/fraction for 14 twice-daily fractions, followed by EBRT using intensity-modulated radiation therapy (IMRT) to cover the grossly enlarged pre-auricular node, ipsilateral intra-parotid, and cervical lymph node levels II and III. Results The approved brachytherapy plan had an average high-risk clinical tumor volume (CTV-HR) D 90 of 341 cGy with a total dose of 47.7 Gy (BED, 80.3 Gy, EQD 2 , 66.6 Gy). For the approved IMRT plan, the prescription to the involved right pre-auricular node was 66 Gy in 33 fractions, and more than 95% of the target received at least 62.7 Gy. High-risk nodal regions were simultaneously prescribed: 59.4 Gy in 1.8 Gy fractions, and more than 95% received at least 56.4 Gy. Organs at risk (OARs) were kept below their dose constraints. The patient tolerated both the procedures with no grade ≥ 2 treatment-related adverse events. Grade 1 dermatitis in the right pre-auricular and cervical areas during the course of EBRT was experienced. Fifteen months post-RT, the patient has no evidence of disease, and was noted to have EAC stenosis, which translated to moderate conductive hearing loss of the right ear. Thyroid function was normal at 15 months after EBRT. Conclusions This case report illustrates that the delivered definitive radiotherapy is technically feasible, effective, and well-tolerated in patients with SCC of EAC.

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Investigating the Effect of Air Cavities of Sinuses on the Radiotherapy Dose Distribution Using Monte Carlo Method

Cited by 4 publications

References 13 publications

The impact of sinusitis on dose distribution in a radiotherapy plan by in silico study

The impact of sinusitis on dose distribution in a radiotherapy plan by in silico study

Simple fabrication technique of personalized endocavitary brachytherapy applicator for maxillary alveolar cancer

Technical details and clinical outcomes after high-dose-rate intracavitary brachytherapy for squamous cell carcinoma of external auditory canal and external beam radiotherapy for nodal coverage: A case report

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